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For the first time in Russia, the intraspecific structure of the brown rat Rattus norvegicus was studied using the mitochondrial control region (D-loop) as a molecular marker. The mtDNA sequence was determined in brown rats from eight regions of European and Asian Russia. Three rat clades were identified, including one in European Russia and two in Asian Russia. The synanthropic subspecies R. n. norvegicus was found to have two, European and Asian, lineages. The European lineage included haplotypes from central and southern regions of Russia, and the Asian lineage included haplotypes from Eastern Siberia and the Russian Far East. The exoanthropic subspecies R. n.caraco from the Russian Far East formed a separate genetic lineage. [ABSTRACT FROM AUTHOR]

Anticoagulants are widely used as potent cumulative rodenticides; however, they are also associated with adverse environmental effects, such as intoxication of non-target animals. To ensure user safety, in the EU the use of anticoagulants containing active substances of > 30 ppm is restricted to professionals as these substances are toxic to reproduction Kat.1 A or B. Therefore, new products with < 30 ppm anticoagulant substance have been developed and registered. While the biological efficacy of these new products has been evaluated, the effect of their application on liver residues in targeted rodents was not examined before product introduction to the market. Our laboratory no-choice study on wild brown rats (Rattus norvegicus) showed that baits with high (50 ppm) and low (25 ppm) brodifacoum concentrations (with identical nontoxic cereal-based food components) presented 100% efficacy, although the 25 ppm bait exhibited significantly higher palatability and 4.5 times higher liver residues. Rats consumed 13.6 and 167.7 g of the 50 and 25 ppm baits, respectively, which corresponded to 3.16 and 14.91 μg/g of brodifacoum liver residues at their time of death. The experiments demonstrated that a decreased concentration of brodifacoum anticoagulant in rodenticide baits may lead to greater accumulation in rodent liver, thus indicating the urgent need to perform a detailed study of the environmental risks of low-concentration anticoagulant baits. [ABSTRACT FROM AUTHOR]

The osmotic fragility of erythrocytes is a parameter that reflects the ability of cells to endure variations in the osmotic environment. The impairment of this ability is often associated with a variety of pathologies, encompassing hemolytic anemias, malignant tumors, and cardiovascular dysfunctions. Osmotic fragility exhibits variability across different animal taxa and is closely related with ecosystems. We developed the method for assessing osmotic fragility using a laser particle size analyzer, which facilitates real-time kinetic monitoring of cell concentration changes under controlled temperature conditions. The species examined included Homo sapiens, Rattus norvegicus domestica, Coturnix japonica domestica, Rana ridibunda, Carassius carassius, and Lampetra fluviatilis. The methodology was presented in two variants: (1) manual water additions and (2) automated medium dilution. The key parameters characterizing osmotic fragility included H50 (the osmolality that lysed half of lysis-susceptible cells), H90 (90% cell lysis), and W (population heterogeneity by the degree of lysis resistance). In terms of H50 and W, the results obtained via this method did not differ significantly from those obtained by spectrophotometry and flow cytometry. No significant differences were also observed between the outcomes of automated and manual variants of the method. Erythrocytes of aquatic and semiaquatic animals exhibited significantly higher resistance to hypotonic lysis. Among all species examined, amphibian (Rana ridibunda) and lamprey (Lampetra fluviatilis) erythrocytes demonstrated the lowest osmotic fragility. The most pronounced variability in the degree of lysis resistance was detected among amphibians, with an almost twofold difference compared to other taxa examined. While mammalian (human and rat) erythrocytes exhibited similar fragility levels, they were more variable in their resistance profiles. Avian erythrocytes demonstrated a half-lysis occurrence at higher osmolality levels compared to mammalian erythrocytes, although in the domestic quail (Coturnix japonica domestica), erythrocytes lysed over a considerably wider osmotic range and contained a subset of cells resistant to hypotonic lysis. These findings indicate that erythrocytes of lower vertebrates share a lower osmotic fragility compared to those of higher vertebrates, a phenomenon most likely attributable to embryonic characteristics, ecto-/endothermy, and habitat considerations. [ABSTRACT FROM AUTHOR]

Globally, low-income urban communities suffer from poor provision of services and degraded environments, favouring opportunistic zoonotic reservoirs, such as rats. Large-scale infrastructural improvements in these contexts are limited, but targeted control of disease reservoirs has sometimes been achieved. A starting point for the targeted control of rats is assessing the impact of existing basic services on rat abundance. However, there is no gold-standard metric for rat abundance, and studies have used different or multiple metrics. Here, therefore, in four low-income urban Brazilian communities, we address the question of whether basic urban services (BUS) – trash collection, rodenticide application and health community agent visits – affect rat abundance, through the first application of the rattiness modelling framework. This recently-developed geostatistical method combines multiple abundance metrics (here, three) to generate rattiness, a proxy for rat abundance, a spatially-continuous latent process common to all metrics. In a cross-sectional study, we exploited spatial heterogeneities in BUS to evaluate its association with the presence of rat signs, rat marks on track plates, and live-trapped rats, and with rattiness, which combined these three imperfect metrics. Rattiness proved to be a useful tool for pooling information among the three metrics and was associated with a greater range of baseline predictors than any single metric. Rat signs and rattiness were positively associated with higher levels of BUS provision and environmental variables known to provide resources for rats. The strong association of baseline environmental variables with rat abundance highlights the need for targeted, small-scale environmental modifications to reduce resources for rats. [ABSTRACT FROM AUTHOR]

In group-living animals, males are assumed to be dominant over females when they are larger than females. Despite this, females have sometimes been proven to be dominant over some males via the winner-loser effect, which becomes stronger when the intensity of aggression in the group is higher. To test whether the winner-loser effect leads to (partial) female dominance in a species with a pronounced sexual dimorphism, we studied the hierarchy in 12 rat colonies (Rattus norvegicus) in which the rats could freely interact with their group members within a spacious area. To investigate the underlying mechanisms, we compared the empirical data to hypotheses generated by the agent-based model 'DomWorld'. We show that females dominated on average 55% of the males, and occupied the alpha position in four colonies, in three of them they shared it with one or several males. Moreover, in line with the predictions of the computational model, females dominated a higher percentage of males when the intensity of aggression of the colony was higher. This shows that although females are only half as heavy as males, they dominate part of the males probably through the winner-loser effect. We suggest that this effect may be widespread in many other species and can be tested experimentally. Significance statement: It is often assumed that males automatically dominate females because males are bigger and stronger than females in many species. However, the present study shows that females can dominate males due to the winner-loser effect. We used an agent-based computational model to generate specific hypotheses that we empirically tested in a large sample of rat colonies. Despite this species having a pronounced male-biased sex dimorphism, some females dominated males – with one female even occupying an unshared alpha position. Such partial female dominance was stronger in colonies with higher intensity of aggression. Here, defeated males may suffer a drastic decrease in their fighting capability and consequently give females more opportunities to surpass them in the hierarchy. [ABSTRACT FROM AUTHOR]

Rats are multiparous rodents that have been used extensively in research; however, the low reproductive performance of some rat strains hampers the broader use of rats as a biomedical model. In this study, the possibility of increasing the litter size after natural mating in rats through superovulation using an anti-inhibin monoclonal antibody (AIMA) was examined. In outbred Wistar rats, AIMA increased the number of ovulated oocytes by 1.3-fold. AIMA did not affect fertilization and subsequent embryonic development, resulting in a 1.4-fold increase in litter size and a high pregnancy rate (86%). In contrast, conventional superovulation by eCG/hCG administration decreased the pregnancy rate to 6–40% and did not increase the litter size. In inbred Brown Norway rats, AIMA increased the litter size by 1.2-fold, and the pregnancy rate increased more than twice (86% versus 38% in controls). AIMA also increased the litter size by 1.5-fold in inbred Tokai High Avoiders and Fischer 344 rats. AIMA increased the efficiency of offspring production by 1.5-, 2.7-, 1.4-, and 1.4-fold, respectively, in the four rat strains. Thus, AIMA may consistently improve the reproductive performance through natural mating in rats, which could promote the use of AIMA in biomedical research. [ABSTRACT FROM AUTHOR]

Purpose: Rodents are one of the most abundant and diverse species of mammals and have recently been identified as carriers of numerous human pathogens. The current study was conducted to assess the prevalence, subtype (STs) distribution, and zoonotic potential of Blastocystis spp. in various species of rodents in Shiraz, southwestern Iran. Methods: For this aim, a total of 120 fresh fecal samples were collected from Mus musculus (n = 40), Rattus norvegicus (n = 40), and Rattus rattus (n = 40) in various municipality districts of Shiraz (6 out of 10 districts) between February and November 2020. Upon detecting parasites using light microscopy, a DNA fragment of the Blastocystis SSU rDNA gene was amplified using conventional PCR. Results: By employing direct wet mount examination, 8 out of 120 fecal samples (6.7%; 2 from house mice, 3 from black rats, and 3 from brown rats) tested positive. Similarly, 5% (2/40) of house mice, 7.5% (3/40) of black rats, and 7.5% (3/40) of brown rats tested positive using the molecular method. Phylogenetic analysis revealed that the Blastocystis infecting different rodent species in Shiraz belonged to two potentially zoonotic STs (ST1 and ST4). Accordingly, rodents should not be overlooked as potential reservoirs of zoonotic Blastocystis infections. Different sampled urban districts and their statistical association with reported prevalence rates were analyzed separately. Conclusion: Overall, the issue of the frequency and ST distribution of Blastocystis in urban rodents of Iran is still open to question and for a proper understanding, wider and more comprehensive studies are needed. [ABSTRACT FROM AUTHOR]

From July 2020 to June 2021, 248 wild house mice (Mus musculus), deer mice (Peromyscus maniculatus), brown rats (Rattus norvegicus), and black rats (Rattus rattus) from Texas and Washington, USA, and British Columbia, Canada, were tested for SARS-CoV-2 exposure and infection. Two brown rats and 11 house mice were positive for neutralizing antibodies using a surrogate virus neutralization test, but negative or indeterminate with the Multiplexed Fluorometric ImmunoAssay COVID-Plex, which targets full-length spike and nuclear proteins. Oro-nasopharyngeal swabs and fecal samples tested negative by RT-qPCR, with an indeterminate fecal sample in one house mouse. Continued surveillance of SARS-CoV-2 in wild rodents is warranted. [ABSTRACT FROM AUTHOR]

Across many taxa, the complexes of the electron transport system associate with each other within the inner mitochondrial membrane to form supercomplexes (SCs). These SCs are thought to confer some selective advantage, such as increasing cellular respiratory capacity or decreasing the production of damaging reactive oxygen species (ROS). In this study, we investigate the relationship between supercomplex abundance and performance of liver mitochondria isolated from rats that do not hibernate and hibernating ground squirrels in which metabolism fluctuates substantially. We quantified the abundance of SCs (respirasomes (SCs containing CI, CIII, and CIV) or SCs containing CIII and CIV) and examined the relationship with state 3 (OXPHOS) and state 4 (LEAK) respiration rate, as well as net ROS production. We found that, in rats, state 3 and 4 respiration rate correlated negatively with respirasome abundance, but positively with CIII/CIV SC abundance. Despite the greater range of respiration rates in different hibernation stages, these relationships were similar in ground squirrels. This is, to our knowledge, the first report of differential effects of supercomplex types on mitochondrial respiration and ROS production. [ABSTRACT FROM AUTHOR]

Objective: Malate dehydrogenase (MDH, ЕC 1.1.1.37) is a multifunctional enzyme complex that catalyzes the reversible conversion of malate to oxaloacetate using NADH as a coenzyme. Currently, the regulation of MDH expression is poorly understood and needs further study. The aim of the study was to study the role of transcription factor CREB1 in regulating the expression of the gene encoding the mitochondrial form of malate dehydrogenase in the liver of rats Rattus norvegicus L. with experimental diabetes. Methods: The work investigated the rate of malate dehydrogenase functioning and the features of its regulation by the transcription factor CREB. Results and Discussion: An increase in the rate of work of NAD-dependent malate dehydrogenase in rat liver cells during the development of experimental diabetes was shown, associated with the activation of the Mdh1 and Mdh2 genes encoding this enzyme. The analysis of the promoters of these genes showed that only in the Mdh2 gene there is a specific binding site with the transcription factor CREB1. It was found that in the liver of rats with pathology, there is an increase in the rate of expression of the gene encoding this transcription factor, which correlates with the expression of the Mdh2 gene. Conclusions: Thus, the data obtained by us confirm the possibility of positive regulation of the rate of the Mdh2 gene by the transcription factor CREB1. [ABSTRACT FROM AUTHOR]

The conditions of upbringing at an early age have a significant impact on the subsequent development, reproduction, and formation of behavioral characteristics of mammals, including rodents. Parents, primarily nursing females, are the main component of the social environment in the early period of postnatal ontogenesis in the majority of mammals. Therefore, the upbringing of mammalian pups in foster families of their own species or another one, even taxonomically distant ones, is one of the main methods for assessing the influence of early experience and the maternal environment on the formation of the behavioral characteristics and the choice of a sexual partner. Rearing of the adopted pups by females of their own or another species is used to preserve valuable species. This necessitates the development of the most effective methods of transferring offspring with maximum survival of the young. In this regard, we analyzed the survival rate and possible causes of mortality of young of a number of rodent species in foster families of mammals of their own and other species. We carried out cross-fostering (interspecific cross-upbringing) and in-fostering (intraspecific cross-upbringing) experiments using house (Mus musculus) and mound-building (Mus spicilegus) mouse pups, yellow steppe lemming (Eolagurusluteus) and brown rat (Rattus norvegicus) pups, and rearing of brown rat pups in foster families of the black polecat (Mustela putorius). As when feeding their own offspring, the main forms of maternal behavior ("maternal behavior complex") of the studied species in relation to adopted young during interspecific transfer are included and manifested in a complex manner if the adoptive mother accepts the young. The survival rate of adopted offspring depends on the degree of taxonomic proximity of the parent taxa: the highest rate was observed during cross-transfer between representatives of species belonging to the supraspecific complex Mus musculus s. l., while the lowest rate is observed when the pups are transferred between representatives of different families and orders of mammals. The success of upbringing adopted young can be determined by the similar composition of milk and the duration of lactation, the similarity of parental behavior (including the degree of male participation in raising the offspring), similar features of the ontogeny of young in closely related forms, and the significant difference in these characteristics in taxonomically distant species. However, successful upbringing of foster offspring is possible if there is similarity in the maternal behavior of taxonomically distant species and taking into account the suitability of milk (for example, feeding of rat pups by female black polecats). According to the results of the analysis of our data and published material, factors influencing the survival and mortality of pups in foster families also include the age of the pups at the time of transfer, species-specific differences in odor, the level of stress of the mother and offspring, the female's previous experience in rearing her own and other pups, and the expression of maternal instinct. All this must be taken into account when using the method of cross-fostering pups in experimental work. [ABSTRACT FROM AUTHOR]

Albeit diverse, human languages exhibit universal structures. A salient example is the syllable, an important structure of language acquisition. The structure of syllables is determined by the Sonority Sequencing Principle (SSP), a linguistic constraint according to which phoneme intensity must increase at onset, reaching a peak at nucleus (vowel), and decline at offset. Such structure generates an intensity pattern with an arch shape. In humans, sensitivity to restrictions imposed by the SSP on syllables appears at birth, raising questions about its emergence. We investigated the biological mechanisms at the foundations of the SSP, testing a nonhuman, non-vocal-learner species with the same language materials used with humans. Rats discriminated well-structured syllables (e.g., pras) from ill-structured ones (e.g., lbug) after being familiarized with syllabic structures conforming to the SSP. In contrast, we did not observe evidence that rats familiarized with syllables that violate such constraint discriminated at test. This research provides the first evidence of sensitivity to the SSP in a nonhuman species, which likely stems from evolutionary-ancient cross-species biological predispositions for natural acoustic patterns. Humans' early sensitivity to the SSP possibly emerges from general auditory processing that favors sounds depicting an arch-shaped envelope, common amongst animal vocalizations. Ancient sensory mechanisms, responsible for processing vocalizations in the wild, would constitute an entry-gate for human language acquisition. [ABSTRACT FROM AUTHOR]

Status epilepticus (SE) is described as continuous and self-sustaining seizures, which triggers hippocampal neurodegeneration, inflammation, and gliosis. N-formyl peptide receptor (FPR) has been associated with inflammatory process. N-formyl-methionyl-leucyl-phenylalanine (fMLP) peptide plays an anti-inflammatory role, mediated by the activation of G-protein-coupled FPR. Here, we evaluated the influence of fMLP peptides on the behavior of limbic seizures, memory consolidation, and hippocampal neurodegeneration process. Male Wistar rats (Rattus norvegicus) received microinjections of pilocarpine in hippocampus (H-PILO, 1.2 mg/μL, 1 μL) followed by fMLP (1 mg/mL, 1 μL) or vehicle (VEH, saline 0.9%, 1 μL). During the 90 min of SE, epileptic seizures were analyzed according to the Racine's Scale. After 24 h of SE, memory impairment was assessed by the inhibitory avoidance test and the neurodegeneration process was evaluated in hippocampal areas. There was no change in latency and number of wet dog shake (WDS) after administration of fMLP. However, our results showed that the intrahippocampal infusion of fMLP reduced the severity of seizures, as well as the number of limbic seizures. In addition, fMLP infusion protected memory dysfunction followed by SE. Finally, the intrahippocampal administration of fMLP attenuated the process of neurodegeneration in both hippocampi. Taken together, our data suggest a new insight into the functional role of fMLP peptides, with important implications for their potential use as a therapeutic agent for the treatment of brain disorders, such as epilepsy. Schematic drawing on the neuroprotective and anticonvulsant role of fMLP during status epilepticus. Initially, a cannula was implanted in hippocampus and pilocarpine/saline was administered into the hippocampus followed by fMLP/saline (A-C). fMLP reduced seizure severity and neuronal death in the hippocampus, as well as protecting against memory deficit (D). [ABSTRACT FROM AUTHOR]

Decomposition is a natural nutrient cycling process that begins with internal bacterial activities and followed by the occupation of various invertebrates, including ants. We reported a significant colonisation of big-headed ants, Pheidole megacephala (Fabricius 1973) on small and medium-sized mammal in a tropical rain forest in Selangor, Malaysia. Three rats (Rattus norvegicus, weight = 0.508 ± 0.023 kg) and three long-tailed macaques (Macaque fascicularis, weight = 5.750 ± 0.776 kg) carcasses were left to decompose naturally. Large P. megacephala colonies were constructed in two out of six carcasses represented by one rat and one macaque. The remaining four carcasses were undisturbed and decomposed naturally. For the colonised rat carcass, P. megacephala covered the entire carcass with soil particles, whereas for the colonised macaque carcass, it was partly covered. After six days of decomposition, the colonised macaque body mass reduced by 22.90%, which was lower than the other two non-colonised macaque carcasses with 80.06% and 83.41%, respectively. From the final hours of day three until day fiveof decomposition, the colonised macaque rectum body temperature was lower than the non-colonised macaque carcasses. Flies were not seen in colonised rat carcass until day five of decomposition. However, for the colonised macaque, their arrival timing was comparable to the uncolonised carcasses, but the number of flies reduced. In conclusion, P. megacephala colonisation on rat and macaque carcass had slowed down the decomposition rate, reduced internal body temperature and the abundance of flies. If these aspects are overlooked by forensic entomologists, it can potentially lead to an inaccurate postmortem interval (PMI) estimation. [ABSTRACT FROM AUTHOR]

Black rat (Rattus rattus), brown rat (Rattus norvegicus), and house mouse (Mus musculus) are known to be among the most common anthropophilic rodent species in cities worldwide. These species are responsible for the destruction of domestic and industrial materials, considerable damage to food stocks as well as zoonotic pathogens circulation and transmission to humans and animals. These invasive species have disseminated in all continents following human-mediated exchanges, especially maritime transports. In particular, seaports appear as privileged rats and mice's entry points into new regions, thus making them international regulations' priorities for rodent surveillance and management. Yet, studies on seaport rodents are rare; in particular, investigations on their genetic structure are almost inexistent, thus precluding science-guided interventions. In order to fill such a gap, our study focused on the population genetics of R. rattus, R. norvegicus and M. musculus in the Autonomous Port of Cotonou, Benin. Nine different sites were surveyed for three years. In total, 366 R. rattus, 188 R. norvegicus and 244 M. musculus were genotyped using 18 microsatellites, 16 microsatellites and 17 microsatellites, respectively. Our results show very well-structured genetic clusters in all three species as well as limited impacts of rodent control campaigns. Using comparisons with genotypes from other European, Asian and African countries, we suggest for the first time that settlement of newly introduced individuals may be a rare event. Implications in terms of management units and control and monitoring are discussed. [ABSTRACT FROM AUTHOR]

Dental enamel is a peculiar biological tissue devoid of any self-renewal capacity as opposed to bone. Thus, a thorough understanding of enamel composition is essential to develop novel strategies for dental enamel repair. While the mineral found in bone and dental enamel is generally viewed as the biologically-produced equivalent of hydroxy(l)apatite, the formation of these bioapatites is controlled by different organic matrix frameworks—mainly type-I collagen in bone and amelogenin in enamel. In lower vertebrates, such as rodents, two distinct types of enamel are produced. Iron-containing pigmented enamel protects the continuously growing incisor teeth while magnesium-rich unpigmented enamel covers the molar teeth. Using high-resolution Raman spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy, this work explores the differences in acid phosphate (HPO42−), carbonate (CO32−), hydroxyl (OH−), iron, and magnesium content of pigmented incisor enamel and unpigmented molar enamel of Sprague Dawley rats. Bundles of hydroxy(l)apatite nanowires comprise the enamel prisms, where prisms in pigmented enamel are wider and longer than those in unpigmented molars. In contrast to magnesium-rich unpigmented enamel, higher mineral crystallinity, and higher HPO42− and OH− levels are hallmark features of iron-rich pigmented enamel. Furthermore, the apparent absence of iron oxides or oxy(hydroxides) indicates that iron is introduced into the apatite lattice at the expense of calcium, albeit in amounts that do not alter the Raman signatures of the PO43− internal modes. Compositional idiosyncrasies of iron-rich pigmented and nominally iron-free unpigmented enamel offer new insights into enamel biomineralisation supporting the notion that, in rodents, ameloblast function differs significantly between the incisors and the molars. [ABSTRACT FROM AUTHOR]

Direct reciprocity requires the ability to recognize and memorize social partners, and to remember their previous actions. 'Insufficient cognitive abilities' have been assumed to potentially impair the ability to cooperate by direct reciprocity. Here we compare the propensity of rats to use direct reciprocity with their ability to memorize and recognize sensory cues in a non-social task. Female rats enriched in one of three sensory modalities (visual, olfactory or auditory) performed better in a learning task when they were tested with the specific sensory modality in which they have been enriched. For the cooperation test, during three subsequent reciprocity experiments the rats could provide two partners differing in their previous helpfulness with food. Individuals performing better in the non-social learning task that involved olfactory cues applied direct reciprocity more successfully in one experiment. However, in the experiment preventing visual cues and physical contact, rats applied direct reciprocity rules irrespective of their performance in the learning task with olfactory cues. This indicates that an enhanced olfactory recognition ability, despite being beneficial, is not a prerequisite for the rats' ability to cooperate by direct reciprocity. This might suggest that when rats have all types of information about their social partner, individuals may apply other criteria than the reciprocity decision rule when determining how much help to provide, as for instance coercion. Interestingly, when all individuals are constrained to mostly rely on olfactory memory, individuals apply direct reciprocity independently of their ability to memorize olfactory cues in a non-social context. 'Insufficient cognitive abilities' may thus not be the true reason when direct reciprocity is not observed. [ABSTRACT FROM AUTHOR]

Rodent population control is a global problem, complicated by evolved non-responsiveness to rodenticide treatment. Contraceptives could help mitigate this challenge, but questions remain about their efficacy, especially for rodenticide-resistant populations. We used an age-dependent demographic model to generate two hypotheses: Fertility reduction applied early in female lifetimes (1) is more effective in controlling rodent populations than when applied later in female lifetimes, and (2) is effective in controlling rodent populations that are expanding. Compared to controls, fertility reduction applied early, in mid-life, and late in female lifetimes, decreased, matched, and accelerated, respectively, the rates of population growth. Fertility reduction was effective in reducing population size only when sustained over multiple generations and was ineffective when application was episodic. Substituting classic Rattus norvegicus and Microtus agrestis life history data into our simulation framework confirmed that early fertility reduction was effective in controlling population growth, including expanding populations in both species. These simulations generated two additional hypotheses for field applications of fertility control: Over treatment durations, (3) the fraction of the population consisting of juveniles, and (4) the overall population size, will both decrease. We tested these predictions using a 12-month contraceptive bait application on rats in two urban US locations (Washington, DC) where rodenticides were already deployed. Consistent with our predictions, these populations showed marked decreases in the proportion of juvenile to adult rats, and in the total number of rats observed in camera traps over the study period. Our results support fertility control as an effective method for managing rodent populations. [ABSTRACT FROM AUTHOR]

Second-generation anticoagulant rodenticides potentially build persistent residues in animals and accordingly pose a risk of secondary poisoning. We examined the effect of a low concentration of cholecalciferol in brodifacoum bait on bait consumption by Norway rats (Rattus norvegicus Berkenhout 1769) and on the control success in a laboratory study and in field trials. Additionally, the efficacy of both baits was determined against resistant Y139C rats. Cholecalciferol caused a strong stop-feed effect after two days in the laboratory study. On two field study sites each, bait containing either 25 mg kg−1 brodifacoum or 25 mg kg−1 brodifacoum and 100 mg kg−1 cholecalciferol was applied to treat infestations of Norway rats. Infestations were assessed pre- and post-treatment. Rats were radio-tagged, and carcasses were searched for during the treatment period. DNA of each rat was genotyped to determine the resistance status conferred by the VKORC1 gene. On all farms, control success exceeded 90%. On farms treated with brodifacoum only, the ratio of total bait consumption to pre-treatment census was significantly higher (6.6 and 4.8 times) than on farms treated with the combination (2.7 and 2.9 times). 78.8% of 183 rats were confirmed Y139C resistant. Bait ingestion was reduced by almost fifty per-cent when cholecalciferol was added to the bait with no impact on control success. All treatments resulted in control levels exceeding 90%, despite a high proportion of anticoagulant-resistant rats. When the use of highly toxic compounds is required in resistance management, addition of cholecalciferol to these baits may reduce the transfer of residues to the environment. [ABSTRACT FROM AUTHOR]

Background: Allium cepa is well-known for its antioxidant capabilities and contains potent antioxidant quercetin (3, 30, 4, 5, 7-pentahydroxyflavone). We investigated the therapeutic effects of aqueous extract of Allium cepa (AEAC) that is quercetin-rich against potassium bromate (KBrO3)-induced oxidative damage in the brains of male Wistar rats using biochemical, immunohistochemical, and histological markers. For 90 days, 40 male Wistar rats were administered KBrO3, KBrO3 + AEAC, and/or quercetin on alternate days, or AEAC and quercetin alone. Results: KBrO3 significantly (p > 0.05) suppressed and diminished antioxidant enzymes and acetylcholinesterase activities with notable decreased total protein levels. Additionally, oxidative stress biomarkers (MDA and NO), as well as DNA fragmentation, all increased significantly (p > 0.05). The immunohistochemical expression of P53, caspase 3, and COX2 protein also increased significantly in the cerebral cortex of the KBrO3-treated groups, but BCL-2 protein expression decreased significantly. Histological examination of brain tissues revealed patterns that corresponded to the enzyme markers. The effects of KBrO3 were all attenuated by the administration of AEAC and quercetin. Conclusions: This research demonstrates the therapeutic effects of Allium cepa on KBrO3-induced oxidative stress, and biochemical perturbation in the brain of Rattus norvegicus. Even though the exact mechanism of action of Allium cepa at the molecular level cannot be completely deduced from the results presented above, it could possibly be due to a combination of its antioxidant, anti-inflammatory, and apoptotic mechanisms. Further studies are required to examine the molecular pathways responsible for these aforementioned therapeutic effects. [ABSTRACT FROM AUTHOR]

Previous magnetic resonance studies of the dorsal hippocampus in male rats selected for aggressive attitude toward humans revealed lower contents of γ-aminobutyric acid (GABA), N-acetylaspartate, and creatinine+phosphocreatinine (Cr+PCr), as well as a higher of phosphorylethanolamine content, as compared to males selected for tame behavior. The effect of early social instability on the hippocampal volume and spectrum of neurometabolites in the dorsal hippocampus was investigated in adult tame, aggressive, and unselected gray rats Rattus norvegicus. Experimental conditions of social instability included early weaning, subsequent housing of behaviorally matched males in pairs until the age of 3 months, and daily replacement of cagemates from days 19 to 25. In the control group, rat pups were weaned at the age of 30 days and then kept by 4–5 animals per cage until the age of 3 months. Control aggressive males were inferior to tame counterparts in hippocampal volumes, both absolute and normalized to individual brain volumes, while early social instability had no effect on these indices. In experimental groups, lower phosphorylethanolamine and higher alanine contents in the dorsal hippocampus, as compared to control animals, were detected in aggressive males only. This fact may be due to a lower level of stress response in these animals, as we observed previously. From the obtained results, it follows that aggressive rats are more sensitive to social instability conditions. Moreover, the early instability conditions and selection for aggressive behavior oppositely affect both phosphorylethanolamine metabolism and integral characteristics of the metabolic profile in the dorsal hippocampus. [ABSTRACT FROM AUTHOR]

Rats are abundant in the urban ecosystem, posing concerns for public health, infrastructural damage, and negative impacts for other urban wildlife. Sewers are considered to be one of the main reservoirs for urban rat populations, and rats may migrate between sewers and other surface areas in search of food and harbouring sites. Yet the ecology of rats in sewers has received little attention. To address this knowledge gap, this review identifies a number of sewer ecosystem characteristics that have been associated with rat activity. We demonstrate that sewers with narrower pipes, lower flow rates, and construction materials, such as brick and clay, are associated with more rat activity. Further, this review suggests that poorly maintained sewers may contain more crevices and cracks for rats to burrow, leading to greater levels of infestation. Finally, we find that sewers located in residential areas, or closer to food establishment, are more prone to rat presence. Together, these findings uncovered several significant implications for management of rats in sewers, as well as highlight the need for these characteristics to be considered in the urban planning process. Future work is needed to explore how rats in sewers and their management impact above ground populations of rats and other urban wildlife. [ABSTRACT FROM AUTHOR]

The degu (Octodon degus) is a rodent that normally constructs burrows for nesting and rearing. To navigate inside these burrows, degus may use idiothetic and/or sensory cues more than visual information, which is less effective in burrows. Spatial information for navigation is processed in several key brain regions including the retrosplenial cortex (RS). However, the structural characteristics of the degu RS have not been previously reported. The present study measured the sizes of the RS and constituent areas 29 and 30 in the degu, and compared these to those found in the rat, which is a terrestrial rodent. The proportion of the rostrocaudal length of the entire RS relative to that of the entire cortex was significantly larger in degus versus rats. The proportion of the rostrocaudal length of the RS at levels rostral to the splenium of the corpus callosum relative to that of the entire cortex was also significantly larger in degus versus rats. Furthermore, the ratio of the estimated volume of area 29 relative to that of area 30 was significantly larger in degus versus rats. These results show that the degu has a rostrocaudally longer rostral RS with a larger area 29 compared to the rat, which suggests that these structural features may be relevant to differences in spatial information processing between the fossorial degu and terrestrial rat. [ABSTRACT FROM AUTHOR]

Toxoplasmosis is a zoonotic disease in humans and animals caused by the protozoan parasite Toxoplasma gondii. Rodents not only act as intermediate hosts for T. gondii but are also a significant source of T. gondii infection for other hosts. There is limited information about the prevalence of this protozoan within rodents in Pakistan. The current study was conducted to determine the prevalence of T. gondii in commensal rodents as well as associated risk factors. A total of 236 rats including Rattus rattus and Rattus norvegicus were captured from three districts of the Sahiwal division in Punjab province, Pakistan. Brain samples were collected from each specimen. Data was gathered about rodent species, gender, age, location, districts, seasonality, and habitat type. PCR assays were used to screen for T. gondii from the brain samples. A Chi-square analysis was used to investigate the association between positive samples and risk factors. A total of 236 rodent spleen samples were examined for detection of the B1 and SAG3 genes of T. gondii DNA by conventional PCR, and 14 (5.9%) were positive. T. gondii prevalence was higher in R. norvegicus (8.2%) compared to R. rattus (4.6%). All risk factors were statistically non-significant. This study provides evidence of T. gondii in rodents in the Sahiwal division and indicates that other animals and humans are at risk of infection. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a neglected vector-borne parasitic disease caused in Italy only by the species Leishmania infantum of the Leishmania donovani complex, which is the causative agent of the zoonotic visceral leishmaniasis (VL) and the sporadic cutaneous leishmaniasis (CL) in humans, and of the canine leishmaniasis (CanL). The disease is considered endemic in southern, central, and insular Italian regions and recognizes phlebotomine sand flies as vector and dogs as main reservoir. Among northern Italian region, Emilia-Romagna shows peculiar epidemiological situation and recent studies are questioning the role of dog as main reservoir of L. infantum. Due to their synanthropic relationship with humans, rodents have been tested for Leishmania spp. in several European countries. The aim of this study was to assess the presence of Leishmania spp. in peridomestic rodents in the Emilia-Romagna. The study was carried out on 136 peridomestic rodents collected by professional pest control services: 47 brown rats (Rattus norvegicus), 39 black rats (Rattus rattus) and 50 mice (Mus musculus). Specimens of earlobe skin, spleen, liver and prescapular lymph nodes were tested with a real-time PCR. Fifteen (11%) rodents, tested positive for Leishmania spp. in particular five brown rats (10.6%), five black rats (12.8%) and five mice (10%). Positivity was obtained from different target organs. These findings revealed the presence of Leishmania spp. in peridomestic rodents of Emilia-Romagna Region, also in two species never tested before in Italy, namely R. norvegicus and M. musculus. [ABSTRACT FROM AUTHOR]

Anticoagulant rodenticides (AR) remain the most effective chemical substances used to control rodents in order to limit their agricultural and public health damage in both rural and urban environments. The emergence of genetically based resistance to AR worldwide has threatened effective rodent control. This study gives a first overview of the distribution and frequency of single nucleotide polymorphism in the vitamin K epoxide reductase subcomponent 1 (Vkorc1) gene in rodents in Lebanon. In the Mus genus, we detected two missense mutations Leu128Ser and Tyr139Cys, that confer resistance to anticoagulant rodenticides in house mice and a new missense mutation Ala72Val in the Mus macedonicus species, not previously described. In the Rattus genus, we found one missense mutation Leu90Ile in the roof rat and one missense mutation Ser149Ile in the Norway rat. This is the first study to demonstrate potential resistance to AR in Lebanese rodents and therefore it provides data to pest control practitioners to choose the most suitable AR to control rodents in order to keep their efficacy. [ABSTRACT FROM AUTHOR]

Circulating sex steroid hormones are critical for neural function and development of neuroplasticity in many regions of the central nervous system. In the spinal cord, our knowledge of steroid hormone influence mostly derives from mechanistic studies of pain processing in dorsal spinal cord circuits; less is known regarding hormonal influence of ventral spinal motor function. Gonadectomy (surgical removal of the testes in males and ovaries in females) rapidly and persistently reduces circulating sex steroids in both females and males, providing a means to interrogate the role of hormones on neural function. Here we provide a next-generation RNA sequencing (RNA-seq) data set to evaluate the impact of gonadectomy on the transcriptome of ventral spinal cord tissue of adult female and male rats. Measurement(s) Ventral spinal cord gene expression Technology Type(s) RNA Sequencing Factor Type(s) Ventral spinal cord gene expression Sample Characteristic - Organism Rattus norvegicus Sample Characteristic - Location United States [ABSTRACT FROM AUTHOR]

Abstract—Meta-analysis of the spontaneous activity of Internet users is proposed as an alternative to traditional methods of counting the abundance of species that people often encounter in their lives. Using the wordstat.yandex.ru tool, the statistics of search queries on the topic of struggle against the common hamster (Cricetus cricetus L., 1758) as an agricultural pest was collected for four years. The tool allows tying the obtained data array to particular administrative region. As a result, a "pest map" of the species (equivalent to its relative abundance) we have compiled. Our comparison of these data with those obtained earlier for the hamster pelt harvesting (1950s) has allowed us to reveal trends in its changes by regions. It is supposed that Internet search statistical analysis is an underestimated resource, which would allow one to obtain information effectively on the abundance and distribution not only of the common hamster, but also of other species frequently in contact with humans (brown rat, water vole, beaver, muskrat, etc.). [ABSTRACT FROM AUTHOR]

This study aims to evaluate whether the consumption of homeopathic products (Orgafig®) in Wistar rats (Rattus norvegicus) can protect the liver against two challenges (a) antipyretic/analgesic (acetaminophen), and (b) feed contaminated with aflatoxin B1. We used 60 animals divided into six groups of ten animals each (a) negative control (NC) that did not receive the drugs and was not challenged with aflatoxin B1; (b) negative control + Orgafig® (NC -H) receiving only homeopathy; (c) positive control for aflatoxin B1 (CP-A) receiving a mycotoxin-contaminated diet; (d) positive control for acetaminophen (CP-P) receiving daily doses of the drug orally; (e) Orgafig® + aflatoxin (HA) receiving homeopathic and challenged with diet contaminated with aflatoxin B1; and (f) Orgafig® + acetaminophen (HP) receiving homeopathic and were challenged with doses of acetaminophen. The Orgafig® was added to the diet for 32 days before the challenge with preventive intent. Then, a challenge was conducted over 10 days using aflatoxin B1 via diet and oral acetaminophen doses. Rats that consumed aflatoxin grew more slowly than the other groups. There were increases in serum activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), indicating liver damage in animals from the positive control groups (CP-A and CP-P); this did not occur in animals with preventive use of Orgafig® (HA and HP). Likewise, in the liver, there was an increase in cell injury and oxidative stress biomarkers (reactive oxygen species, thiobarbituric acid reactive substances, and glutathione S-transferase) that also signal liver damage in the positive control rats (CP-A and CP-P); this did not occur in animals with preventive or Orgafig® use (HA and HP). These results suggest that the prophylactic use of the Orgafig® minimizes the adverse effects caused by the daily consumption of aflatoxin B1 and acetaminophen, which are known for hepatotoxic action when used in high doses or for prolonged periods. [ABSTRACT FROM AUTHOR]

Several studies have attempted to reveal the evolutionary mechanisms of physical causal understanding in non-human animals by investigating their tool-use behavior. Rats are one of the most commonly used species in experiments in many fields, including neuroscience and physiological psychology, but behavioral tasks for investigating the mechanisms in rodents have not yet been established. The present study implemented a novel training paradigm: a rake-shaped tool was presented in the experimental apparatus without a reward. If rats manipulated the rake laterally over specific distances, the experimenter retrieved the rake and offered the reward by hand. The rats never obtained food directly with the tool during training, and the tool never touched the reward. In the test, the rake was placed at the center of the apparatus, and the reward was placed on either the left or right side of the rake. The rats had no prior experience of obtaining the reward with the tool before the test, and they could not use this simple strategy to manipulate the rake in the direction of the reward during the test. One of eight rats could manipulate the rake according to the position of the reward. The present study offers a tool-use task to reveal the evolutionary mechanisms of physical causal understanding. [ABSTRACT FROM AUTHOR]

Rats are abundant and ubiquitous in urban environments. There has been increasing attention to the need for evidence-based, integrated rat management and surveillance approaches because rats can compromise public health and impose economic costs. Yet there are few studies that characterize rat distributions in sewers and there are no studies that incorporate the complexity of sewer networks that encompass multiple sewer lines, all comprised of their own unique characteristics. To address this knowledge gap, this study identifies sewer characteristics that are associated with rat presence in the city of Seattle's urban sewer system. We obtained sewer baiting data from 1752 geotagged manholes to monitor rat presence and constructed generalized additive models to account for spatial autocorrelation. Sewer rats were unevenly distributed across sampled manholes with clusters of higher rat presence at upper elevations, within sanitary pipes, narrower pipes, pipes at a shallower depth, and older pipes. These findings are important because identifying features of urban sewers that promote rat presence may allow municipalities to target areas for rat control activities and sewer maintenance. These findings suggest the need to evaluate additional characteristics of the surface environment and identify the factors driving rat movement within sewers, across the surface, and between the surface and the sewers. [ABSTRACT FROM AUTHOR]

Animal models are essential for studying the pathophysiology of chronic pain disorders and as screening tools for new therapies. However, most models available do not reproduce key characteristics of clinical persistent pain. This has limited their ability to accurately predict which new medicines will be clinically effective. Here, we characterize the Dahl salt-sensitive (SS) rat strain as the first rodent model of inherited widespread hyperalgesia. We show that this strain exhibits physiological phenotypes known to contribute to chronic pain, such as neuroinflammation, defective endogenous pain modulation, dysfunctional hypothalamic–pituitary–adrenal axis, increased oxidative stress and immune cell activation. When compared with Sprague Dawley and Brown Norway rats, SS rats have lower nociceptive thresholds due to increased inflammatory mediator concentrations, lower corticosterone levels, and high oxidative stress. Treatment with dexamethasone, the reactive oxygen species scavenger tempol, or the glial inhibitor minocycline attenuated the pain sensitivity in SS rats without affecting the other strains while indomethacin and gabapentin provided less robust pain relief. Moreover, SS rats presented impaired diffuse noxious inhibitory controls and an exacerbated response to the proalgesic mediator PGE2, features of generalized pain conditions. These data establish this strain as a novel model of spontaneous, widespread hyperalgesia that can be used to identify biomarkers for chronic pain diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Pesticides based on organophosphorus compounds (OPCs) are widely used in agriculture worldwide, which is fraught with acute and chronic human poisoning. In general, toxic effects of OPCs on the mammalian organism are well studied, but many etiological aspects of immediate and long-term consequences of poisoning require additional attention. The aim of this study was to assess the dynamics of biochemical blood and urine parameters along with pathomorphological and ultrastructural changes in the kidneys after acute poisoning of experimental rats with O-O-diethyl O-(4-nitrophenyl) phosphate (Paraoxon-ethyl, DNPP). The study was carried out on white outbred male rats Rattus norvegicus weighing 200–250 g. DNPP was injected to animals of experimental groups at a median lethal dose (LD50, single injection). Blood serum and urine samples for biochemical analysis and kidney tissue samples for morphological examination were taken on days 1, 3 and 7 after poisoning. Daily diuresis and urine specific gravity, as well as serum and urine levels of bilirubin, total protein, glucose, pH, creatinine, albumin, D-3-hydroxybutyrate and uric acid, were assessed. Pathomorphological changes in kidney tissue were documented. After DNPP exposure, there were observed a decrease in albumin and an increase in uric acid, glucose and D-3-hydroxybutyrate serum levels, as well as a decrease in the volume of daily diuresis and urine pH, paralleled by an increase in urine specific gravity. Morphological analysis of kidney tissue revealed a damage to epithelial cells of the proximal convoluted tubules and an increase in the thickness of glomerular basement membranes, respectively, 1 and 7 days after DNPP exposure. A single sublethal dose of DNPP had a nephrotoxic effect, as manifested in changes in biochemical blood and urine parameters, as well as morphological parameters of kidney tissue. The most pronounced changes in biochemical parameters were recorded 1 day after DNPP exposure, indicative of a decrease in the excretory capacity of the kidneys and the development of metabolic ketoacidosis. The thickening of glomerular basal membranes 7 days after exposure suggests the prerequisites for the formation of delayed pathology. [ABSTRACT FROM AUTHOR]

A special in vitro model maintained with ultrathin cardiac slices with a preserved architecture, multi-cellularity, and physiology of the heart tissue was used. In our experiments, we performed label-free quantitative SWATH-MS proteomic analysis of the adult myocardial slices in vitro after biomimetic electromechanical stimulation. Rat myocardial slices were stretched to sarcomere lengths (SL) within the physiological range of 1.8–2.2 μm. Electromechanically stimulated slices were compared with slices cultured without electromechanical stimulation (unloaded and nonstimulated-TW) on a liquid–air interface and with fresh myocardial slices (0 h-C). Quantitative (relative) proteomic analyses were performed using a label-free SWATH-MS technique on a high-resolution microLC-MS/MS TripleTOF 5600+ system (SCIEX). The acquired MS/MS spectra from the DDA LC–MS/MS analyses of the rat heart samples were searched against the UniProt Rattus norvegicus database (version of 15.05.2018) using the Paragon algorithm incorporated into ProteinPilot 4.5 (SCIEX) software. The highest number of differential proteins was observed in the TW group—121 when compared to the C group. In the 1.8 and 2.2 groups, 79 and 52 proteins present at a significantly different concentration from the control samples were found, respectively. A substantial fraction of these proteins were common for two or more comparisons, resulting in a list of 169 significant proteins for at least one of the comparisons. This study found the most prominent changes in the proteomic pattern related to mitochondrial respiration, energy metabolism, and muscle contraction in the slices that were stretched and fresh myocardial slices cultured without electromechanical stimulation. [ABSTRACT FROM AUTHOR]

For the first 100+ million years of their evolutionary history, the majority of mammals were very small, and many exhibited relatively generalized locomotor ecologies. Among extant mammals, small-bodied, generalist species share similar hindlimb bone morphology and locomotor mechanics, but details of their musculature have not been investigated. To examine whether hindlimb muscle architecture properties are also similar, we dissected hindlimb muscles of the gray short-tailed opossum (Monodelphis domestica) and aggregated muscle properties from the literature for three other small-bodied mammals (Mus musculus, Rattus norvegicus, Cavia porcellus). We then studied hindlimb musculature from a whole-limb perspective and by separating the limb into nine anatomical regions. The region analysis explained substantially more variance in the data (r2: 0.601 > 0.074) but only detected six statistically significant pairwise species differences in muscle architecture properties. This finding suggests either deep conservation of therian hindlimb muscle properties or, more likely, a biomechanical constraint imposed by small body size. In addition, we find specialization for either large force production (i.e., PCSA) or longer active working ranges (i.e. long muscle fascicles) in proximal limb regions but neither specialization in more distal limb regions. This functional pattern may be key for small mammals to traverse across uneven and shifting substrates, regardless of environment. These findings are particularly relevant for researchers seeking to reconstruct and model soft tissue properties of extinct mammals during the early evolutionary history of the clade. [ABSTRACT FROM AUTHOR]

Genetic resistance to anticoagulants caused by mutations in the Vkorc1 gene of the most invasive rodent species—Norway rats and house mice, has not been studied in Russia. We analyzed the variability of the Vkorc1 gene in house mice and Norway rats in various settlements of Russia, and identified mutations responsible for resistance to rodenticides. Two exons of the Vkorc1 gene were analyzed in 71 Norway rats from four cities (Moscow, Tyumen, Chita, Rostov-on-Don) and 108 house mice from cities and small settlements (Moscow region, Tormosin, Nizhny Tsasuchei). Three Norway rats (15.8% of the studied individuals) in Moscow have a heterozygous state the Tyr139Ser mutation, which is responsible for resistance. House mice were not found to have mutations in the Vkorc1 gene responsible for resistance to anticoagulants of the first and second generation in the Leu128Ser and Tyr139Cys positions located in the third exon. However, in cities in the first exon, we identified two heterozygous mutations have not be described previously in the scientific literature: Lys58Arg and Ser31Trp. In Russia, the genetic resistance to rodenticides in settlements in the populations of house mice and Norway rats is significantly lower than in Western Europe. [ABSTRACT FROM AUTHOR]

Anticoagulants are a major component of rodenticides used worldwide, which function by effectively blocking the vitamin K cycle in rodents. The rat Vitamin K epoxide Reductase Complex (VKORC) subunit 1 is the enzyme responsible for recycling vitamin K, and five substitution mutations (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln and Leu120Gln) located in the VKORC1 could result in resistance to anticoagulant rodenticides. This study carried out a VKORC1-based survey to estimate the anticoagulant rodenticide resistance in three Rattus species (R. losea, R. norvegicus, and R. tanezumi) collected in Hong Kong. A total of 202 rats captured in Hong Kong between 2017 and 2021 were analysed. Sequencing of molecular marker cytochrome c oxidase subunit 1 (COX1) was carried out to assist the species identification, and the identities of 52 lesser ricefield rats (R. losea), 81 common rats (R. norvegicus) and 69 house rats (R. tanezumi) were confirmed. Three VKORC1 exons were amplified from individuals by PCR followed by Sanger sequencing. A total of 47 R. tanezumi (68.1%) contained Tyr139Cys mutation in VKORC1 gene, and half of them were homozygous. None of the collected R. losea and R. norvegicus were detected with the five known substitutions leading to anticoagulant rodenticides resistance, and previously undescribed missense mutations were revealed in each species. Whole genome sequencing was further carried out on some individuals, and single nucleotide polymorphisms (SNPs) were also identified in the introns. This is the first study investigating the situation of anticoagulant rodenticide resistance in the rats collected in Hong Kong. Given that the efficacy of rodenticides is crucial for effective rodent management, regular genetic testing as well as population genomic analyses will be required to both monitor the situation and understand the adaption of different rat haplotypes for integrated pest management. Susceptibility tests for individual rodenticides should also be conducted regularly to assess their effectiveness on local species. [ABSTRACT FROM AUTHOR]

A lack of toxicity data quantifying responses of Australian native mammals to agricultural pesticides prompted an investigation into the sensitivity of the stripe-faced dunnart, Sminthopsis macroura (Gould 1845) to the insecticide, fipronil (5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinyl pyrazole, CAS No. 120068-37-3). Using the Up-And-Down method for determining acute oral toxicity in mammals (OECD) median lethal dose estimates of 990 mg kg−1 (95% confidence interval (CI) = 580.7–4770.0 mg kg−1) and 270.4 mg kg−1 (95% CI = 0.0–>20,000.0 mg kg−1) were resolved for male and female S. macroura, respectively. The difference between median lethal dose estimates for males and females may have been influenced by the older ages of two female dunnarts. Consequently, further modelling of female responses to fipronil doses used the following assumptions: (a) death at 2000 mg kg−1, (b) survival at 500 mg kg−1 and (c) a differential response (both survival and death) at 990 mg kg−1. This modelling revealed median lethal dose estimates for female S. macroura of 669.1 mg kg−1 (95% CI = 550–990 mg kg−1; assuming death at 990 mg kg−1) and 990 mg kg−1 (95% CI = 544.7–1470 mg kg−1; assuming survival at 990 mg kg−1). These median lethal dose estimates are 3–10-fold higher than available LD50 values of 94 mg kg−1 for a similarly sized eutherian mammal, Mus musculus (L. 1758) and 97 mg kg−1 for Rattus norvegicus (Birkenhout 1769). Implications for pesticide risk assessments in Australia are discussed. [ABSTRACT FROM AUTHOR]

Application of mass spectrometry enables the detection of metabolic differences between organisms with different nutritional settings. Divergence in the metabolic fingerprints of rat pancreatic INS-1 β-cells were systematically captured with regard to ten individual essential amino acid (EAA) availability. A high-resolution tandem mass spectrometry system coupled to liquid chromatography produced a horizontal comparison of metabolic profilings of β-cells with individual EAA elevated to 10 mmol/L by turn or removal individual EAA from the medium one by one. Quality control samples were injected at regular intervals throughout the analytical run to monitor and evaluate the stability of the system. The raw data of samples and reference compounds including study protocols have been deposited in the open metabolomics database MetaboLights to enable efficient reuse of the datasets, such as investigating the difference in metabolic process between diverse EAAs as well as screening and verifying potential metabolites affecting insulin secretion and β-cell function. Measurement(s) metabolomic profiling Technology Type(s) Ultra High-performance Liquid Chromatography/Tandem Mass Spectrometry Factor Type(s) arginine • histidine • isoleucine • leucine • lysine • methionine • phenylalanine • threonine • tryptophan • valine Sample Characteristic - Organism Rattus norvegicus [ABSTRACT FROM AUTHOR]

Rat is one of the most widely-used models in chemical safety evaluation and biomedical research. However, the knowledge about its microRNA (miRNA) expression patterns across multiple organs and various developmental stages is still limited. Here, we constructed a comprehensive rat miRNA expression BodyMap using a diverse collection of 320 RNA samples from 11 organs of both sexes of juvenile, adolescent, adult and aged Fischer 344 rats with four biological replicates per group. Following the Illumina TruSeq Small RNA protocol, an average of 5.1 million 50 bp single-end reads was generated per sample, yielding a total of 1.6 billion reads. The quality of the resulting miRNA-seq data was deemed to be high from raw sequences, mapped sequences, and biological reproducibility. Importantly, aliquots of the same RNA samples have previously been used to construct the mRNA BodyMap. The currently presented miRNA-seq dataset along with the existing mRNA-seq dataset from the same RNA samples provides a unique resource for studying the expression characteristics of existing and novel miRNAs, and for integrative analysis of miRNA-mRNA interactions, thereby facilitating better utilization of rats for biomarker discovery. Measurement(s) miRNA expression profiling Technology Type(s) Next Generation Sequencing Factor Type(s) organ • age • sex Sample Characteristic - Organism Rattus norvegicus [ABSTRACT FROM AUTHOR]

Our study aimed to investigate seasonal variation in the activity of arboreal and semi-arboreal mammals and investigate their overlap in temporal activity, as well temporal shifts in activity because of behavioural interference. In our camera trapping study in a fragmented landscape in south-eastern Australia, a total of ten arboreal and semi-arboreal species were found, with 35,671 independent observations recorded over 6517 camera trap nights. All species were found to be nocturnal; however, a notable number of daytime observations were made for several species (i.e. brown antechinus, Antechinus stuartii; sugar glider, Petaurus breviceps; bush rat, Rattus fuscipes; brown rat, Rattus norvegicus). Seasonal variations in diel activity were observed through an increase in crepuscular activity in spring and summer for antechinus, sugar gliders, brown rats, brushtail possums, Trichosurus vulpecula and ringtail possums, Pseudocheirus peregrinus. Diel activity overlap between species was high, that is 26/28 species comparisons had overlap coefficients (Δ) > 0.75. The species pair with the least amount of overlap was between southern bobucks, Trichosurus cunninghami and brown antechinus (Δ4 = 0.66). The species pair with the most overlap was between the native sugar glider and introduced brown rat (Δ4 = 0.93). When comparing the activity of sugar gliders in sites with low and high abundance of brown rats, sugar gliders appear to shift their activity relative to the brown rats. Similarly, behavioural interference was also observed between antechinus and sugar gliders, and when comparing sites of low and high abundance of sugar glider, antechinus had a shift in activity. Our work provides some of the first quantification of temporal patterns for several of the species in this study, and the first for a community of arboreal and semi-arboreal mammals. Our results indicate that some shifts in behaviour are potentially occurring in response to behavioural interference, allowing for coexistence by means of temporal partitioning. [ABSTRACT FROM AUTHOR]

Seaports are introduction hotspots for invasive alien species (IAS). This is especially true for rodents, which have accompanied humans around the globe since the earliest days of ocean-going voyages. The rapid spread of IAS soon after arrival in a new environment is facilitated by further human-mediated transport or landscape features, like roads. By measuring genetic diversity and structure to investigate dispersal pathways, we gained insight into the transport, spread and establishment stages of a biological invasion, leveraging the most common rodent species (R. norvegicus) in this setting. We characterized the genetic structure of three Norway rat populations along a busy industrial road used by trucks to access the Port area in Paranaguá city (Brazil). A total of 71 rats were genotyped using 11 microsatellite markers. The results revealed a pattern of gene flow contrary to the expected stepping-stone model along the linear transect, with the two furthest apart populations being clustered together. We hypothesize that the observed outcome is explained by natural dispersal along the corridor being lower than human-mediated transport. The sampled area furthest from the port is a gas station frequented by trucks which are considered the most likely mode of transportation. In terms of management strategies, we suggest more emphasis should be put on cargo surveillance to lower the risk of Norway rat dispersal, not only for biosecurity, but also for sanitary reasons, as this port is a major grain trading point. [ABSTRACT FROM AUTHOR]

This three-dimensional structured illumination microscopy (3DSIM) dataset was generated to highlight the suitability of 3DSIM to investigate mitochondria-derived vesicles (MDVs) in H9c2 cardiomyoblasts in living or fixed cells. MDVs act as a mitochondria quality control mechanism. The cells were stably expressing the tandem-tag eGFP-mCherry-OMP25-TM (outer mitochondrial membrane) which can be used as a sensor for acidity. A part of the dataset is showing correlative imaging of lysosomes labeled using LysoTracker in fixed and living cells. The cells were cultivated in either normal or glucose-deprived medium containing galactose. The resulting 3DSIM data were of high quality and can be used to undertake a variety of studies. Interestingly, many dynamic tubules derived from mitochondria are visible in the 3DSIM videos under both glucose and galactose-adapted growth conditions. As the raw 3DSIM data, optical parameters, and reconstructed 3DSIM images are provided, the data is especially suitable for use in the development of SIM reconstruction algorithms, bioimage analysis methods, and for biological studies of mitochondria. Measurement(s) fluorescence microscopy images of mitochondria Technology Type(s) three dimensional structured illumination microscopy Sample Characteristic - Organism Rattus norvegicus • H9c2 cardiomyoblast cell-line [ABSTRACT FROM AUTHOR]

Anticoagulant rodenticides are commonly used in rodent control because they are economical and have great deployment versatility. However, rodents with Single Nucleotide Polymorphism (SNP) mutations within the Vkorc1 gene are resistant to the effects of anticoagulant rodenticide use and this influences the effectiveness of control strategies that rely on such rodenticides. This study examined the prevalence of rat SNP mutations in Singapore to inform the effectiveness of anticoagulant rodenticide use. A total of 130 rat tail samples, comprising 83 Rattus norvegicus (63.8%) and 47 Rattus rattus complex (36.2%) were conveniently sampled from November 2016 to December 2019 from urban settings and sequenced at exon 3 of Vkorc1. Sequencing analysis revealed 4 synonymous and 1 non-synonymous mutations in Rattus rattus complex samples. A novel synonymous mutation of L108L was identified and not previously reported in other studies. Non-synonymous SNPs were not detected in the notable codons of 120, 128 and 139 in R. norvegicus, where these regions are internationally recognised to be associated with resistance from prior studies. Our findings suggest that the prevalence of anticoagulant rodenticide resistance in Singapore is low. Continued monitoring of rodenticide resistance is important for informing rodent control strategies aimed at reducing rodent-borne disease transmission. [ABSTRACT FROM AUTHOR]

Testicular impairment is a serious complication of diabetes that is mediated by oxidative stress and inflammation. Physalis has antioxidative and anti-inflammatory actions. Thus, the present study investigated the ameliorative role of Physalis juice (PJ) prepared from the fruits against testicular damages in streptozotocin (STZ)-induced diabetic rats. Adult male Wistar rats were divided randomly into five groups (n=6): control, orally administered 5 mL PJ/kg daily (PJ), injected intraperitoneally with a single dose of 55 mg STZ/kg without treatment (STZ), or treated daily with PJ (STZ+PJ) or with 500 mg metformin/kg (STZ+Met), for 28 days. The STZ group showed a marked elevation in the blood glucose level by 230%, whereas remarkable declines in the serum levels of testosterone (44%), follicle-stimulating hormone (FSH) (48%), and luteinizing hormone (LH) (36%), as compared to controls. In comparison to controls, the testis of the STZ group showed remarkable declines in the testis weight (15%), the glutathione (GSH) content (45%), mRNA and protein levels of B-cell lymphoma-2 (Bcl-2) (48 and 35%), mRNA and activities of superoxide dismutase (SOD) (63 and 40%), catalase (CAT) (56 and 31%), glutathione peroxidase (GPx) (51 and 44%), and glutathione reductase (GR) (62 and 43%), whereas marked elevations in the levels of interleukin-1 beta (IL-1β (169%), tumor necrosis factor-alfa (TNFα) (85%), nitric oxide (NO) (96%), malondialdehyde (MDA) (83%), mRNA and protein levels of Bcl-2-associated X protein (Bax) (400 and 61%), and mRNA level of caspase-3 (Cas-3) (370%). Some histopathological alterations were observed in the testicular tissue of the STZ group. In contrast, PJ markedly alleviated all the abovementioned disturbances. In conclusion, PJ at a dose of 5 mL/kg attenuated the diabetes-associated testicular impairments, which may be due to its antioxidative, anti-inflammatory, and antiapoptotic actions. [ABSTRACT FROM AUTHOR]

Aging and reduced exposure to environmental microbes can both potentiate neuroinflammatory responses. Prior studies indicate that immunization with the immunoregulatory and anti-inflammatory bacterium, Mycobacterium vaccae (M. vaccae), in aged rats limits neuroimmune activation and cognitive impairments. However, the mechanisms by which M. vaccae immunization ameliorates age-associated neuroinflammatory "priming" and whether microglia are a primary target remain unclear. Here, we investigated whether M. vaccae immunization protects against microglia morphological changes in response to aging. Adult (3 mos) and aged (24 mos) Fisher 344 × Brown Norway rats were immunized with either M. vaccae or vehicle once every week for 3 weeks. Aging led to elevated Iba1 immunoreactivity, microglial density, and deramification of microglia processes in the hippocampus and amygdala but not other brain regions. Additionally, aged rats exhibited larger microglial somas in the dorsal hippocampus, suggestive of a more activated phenotype. Notably, M. vaccae treatment ameliorated indicators of microglia activation in both the amygdala and hippocampus. While changes in morphology appeared to be region-specific, gene markers indicative of microglia activation were upregulated by age and lowered in response to M. vaccae in all brain regions evaluated. Taken together, these data suggest that peripheral immunization with M. vaccae quells markers of age-associated microglia activation. [ABSTRACT FROM AUTHOR]

The ecotoxicity of anticoagulants used for rodent pests' management is a major concern, particularly with second generation anticoagulants, which are more persistent in the body of rodents and therefore more likely to cause secondary exposure in their predators. One of the solutions envisaged to mitigate this risk is to use stereoisomers of these anticoagulants, each of which has particular pharmacokinetics. However, the few studies published to date have considered only one species and one sex. Here, we study the pharmacokinetics of the 4 stereoisomers of 3.4 mg/kg of difethialone in rats (Rattus norvegicus) and 3 mg/kg in mice (Mus musculus) in both sexes and propose a model to choose the optimal stereoisomer efficacy/ecotoxicity mixture for the management of all these animals. Our results show that while the most persistent stereoisomer (E3-cis) is common to both species and sexes, the pharmacokinetics of the other stereoisomers show marked differences between sexes and species. Thus, the area under curve (AUC) of E4-trans in male rats is four times lower than in females or mice, making it a priori unusable in male rats. Conversely, our modeling seems to show that the E1-trans stereoisomer seems to offer the best compromise AUC persistence. In conclusion, we highlight that studies on anticoagulants must necessarily integrate research on the effect of gender and species both on efficacy and with regard to the ecotoxicity of these molecules. [ABSTRACT FROM AUTHOR]

Individual differences in behaviors are seen across many species, and investigations have focused on traits linked to aggression, risk taking, emotionality, coping styles, and differences in cognitive systems. The current study investigated whether there were individual differences in proactive interference tasks in rats (Rattus Norvegicus), and tested hypotheses suggesting that these tasks should load onto a single factor and there should be clusters of rats who perform well or poorly on these tasks. The performance of 39 rats was tested across three learning tasks that all involved disengagement from an irrelevant previously learned stimulus to a relevant stimulus: latent inhibition (LI), partial reinforcement extinction effect (PREE), and reversal learning (RL). An exploratory factor analysis revealed the existence of one factor underlying performance. A cluster analysis revealed the existence of sets of rats displaying either weak LI and strong PREE and RL effects, or vice versa. These findings suggest that proactive interference may be based on a single underlying psychological system in rats. [ABSTRACT FROM AUTHOR]

Bocaviruses are typical zoonotic pathogens with a wide range of hosts. Here, we report the detection of human bocavirus (HBoV) in Rattus norvegicus captured in China and the results of sequencing and phylogenetic analysis based on the partial VP1 region and the entire viral genome. A total of 357 fecal samples from rats were collected in 2015-2017 and analyzed for HBoV using PCR. The detection rate of HBoV was 0.84% (3/357). Phylogenetic analysis revealed that this virus is genetically closely related to HBoV-2. R. norvegicus may be a carrier of HBoV, and its impact on public health merits attention. [ABSTRACT FROM AUTHOR]

Because rats are commensal organisms that depend on human activities for food, shifts in human behavior will have pronounced effects on local rat populations. In the spring of 2020, social distancing measures were implemented globally to curtail the spread of SARS-CoV-2. This presented a unique opportunity to obtain information regarding the immediate effects of shifts in human behavior on rat populations in a variety of countries. In response to increased sightings of rats in the USA that were reported in American media, we analyzed the changes in the number of public service calls in Tokyo, Japan. We found that the number of calls increased after the implementation of social distancing measures, suggesting that rat sightings had also increased in Tokyo. We then surveyed the changes in the business activities of pest management professionals in the USA, Canada, and Tokyo. We found that the activities were increased in 50 to 60% of the respondents from the USA and Canada. In contrast, 60 to 70% of the respondents from Tokyo answered that their activities were not changed. These results implied that, following the implementation of social distancing measures, rat infestations increased in North America, but not in Tokyo. The survey also suggested that roof rats were considered to be the predominant rodent species in Tokyo. This may account for the limited infestations in Tokyo because roof rats are more sedentary than brown rats. Taken together, our findings suggest that social distancing measures differentially affected rat populations in North America and Tokyo. [ABSTRACT FROM AUTHOR]