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Simple Summary: In the present study, we tested whether, when given the choice to ascend or descend, rodents would favor traveling downwards or upwards on identical inclinations and sought to explain the underlying mechanism of such a preference. Our test incorporated different rodent species that dwell in different habitats and display different life and motor styles. We found that all the tested rodent species displayed a general preference to descend, with rodents from complex habitats being less affected by inclination compared with rodents from flatlands. Overall, when given the choice to ascend or descend, all the tested species displayed a preference to descend, perhaps as attraction to the ground (a behavior termed gravitaxis), where they usually have their burrows. Gravity polarizes the vertical axis and many animals can sense whether they are moving with gravity or against gravity. Gravitaxis, which is a movement in reference to a gradient, could therefore be a property involved in spatial behavior, a fundamental means of facilitating navigation, as manifested here in the rodents' general preference to descend rather than ascend. We directly tested whether, when given the choice to ascend or descend, rodents would favor traveling downwards or upwards. The test incorporated different rodent species that dwell in different habitats and display different life and motor styles. Testing was performed in a three-dimensional Y-maze in which the basis was horizontal and, by rotating it, one arm of the maze could be pointing upwards at a certain angle and the other arm pointed downwards at the same angle. All the tested species displayed a general preference for descent, with rodents from complex habitats being less affected by inclination compared with rodents from flatlands. Unlike laboratory rats, wild species traveled greater distances along the lower compared to the upper maze arm. All the rodents initially tended to travel the entire length of the inclined maze arms, but such complete trips decreased with the increase in inclination. When introduced into the maze from top or bottom, flatland dwellers traveled mainly in the entry arm. Overall, when given the choice to ascend or descend, all the tested species displayed a preference to descend, perhaps as attraction to the ground, where they usually have their burrows. [ABSTRACT FROM AUTHOR]

We directly tested whether, when given the choice to ascend or descend, rodents would favor traveling downwards or upwards. The test incorporated different rodent species that dwell in different habitats and display different life and motor styles. Testing was performed in a three-dimensional Y-maze in which the basis was horizontal and, by rotating it, one arm of the maze could be pointing upwards at a certain angle and the other arm pointed downwards at the same angle. All the tested species displayed a general preference for descent, with rodents from complex habitats being less affected by inclination compared with rodents from flatlands. Unlike laboratory rats, wild species traveled greater distances along the lower compared to the upper maze arm. All the rodents initially tended to travel the entire length of the inclined maze arms, but such complete trips decreased with the increase in inclination. When introduced into the maze from top or bottom, flatland dwellers traveled mainly in the entry arm. Overall, when given the choice to ascend or descend, all the tested species displayed a preference to descend, perhaps as attraction to the ground, where they usually have their burrows.

The karyotypes of four species of jirds of the genus Meriones Illiger, 1811 from Turkey and Iran (M. tristrami, M. persicus, M. vinogradovi and M. libycus) were studied using C-banding and AgNOR staining. The obtained basic karyotype characteristics of the studied species are in agreement with previously published data. Intra-specific variation in the number of autosomal arms was recorded in M. tristrami. Extensive variations were recorded in the number or localisation of active NOR sites between species and within species. The cytogenetic markers, such as the positive C-bands or NORs, seem to have only limited importance in inter-specific differentiation but they may be applied in studies of the relationships between geographic populations within species. [ABSTRACT FROM AUTHOR]

River blindness and lymphatic filariasis are two filarial diseases that globally affect millions of people mostly in impoverished countries. Current mass drug administration programs rely on drugs that primarily target the microfilariae, which are released from adult female worms. The female worms can live for several years, releasing millions of microfilariae throughout the course of infection. Thus, to stop transmission of infection and shorten the time to elimination of these diseases, a safe and effective drug that kills the adult stage is needed. The benzimidazole anthelmintic flubendazole (FBZ) is 100% efficacious as a macrofilaricide in experimental filarial rodent models but it must be administered subcutaneously (SC) due to its low oral bioavailability. Studies were undertaken to assess the efficacy of a new oral amorphous solid dispersion (ASD) formulation of FBZ on Brugia pahangi infected jirds (Meriones unguiculatus) and compare it to a single or multiple doses of FBZ given subcutaneously. Results showed that worm burden was not significantly decreased in animals given oral doses of ASD FBZ (0.2–15 mg/kg). Regardless, doses as low as 1.5 mg/kg caused extensive ultrastructural damage to developing embryos and microfilariae (mf). SC injections of FBZ in suspension (10 mg/kg) given for 5 days however, eliminated all worms in all animals, and a single SC injection reduced worm burden by 63% compared to the control group. In summary, oral doses of ASD formulated FBZ did not significantly reduce total worm burden but longer treatments, extended takedown times or a second dosing regimen, may decrease female fecundity and the number of mf shed by female worms. [ABSTRACT FROM AUTHOR]

Flubendazole (FBZ) is highly efficacious against filarial nematodes after parenteral administration and presents a promising macrofilaricidal drug candidate for the elimination of onchocerciasis and other filariae. In the present study the efficacy of a newly developed bioavailable amorphous solid dispersion (ASD) oral formulation of FBZ was investigated in the Litomosoides sigmodontis jird model. FBZ was administered to chronically infected, microfilariae-positive jirds by single (40mg/kg), repeated (2, 6 or 15mg/kg for 5 or 10 days) oral (OR) doses or single subcutaneous (SC) injections (2 or 10mg/kg). Jirds treated with 5 SC injections at 10mg/kg served as positive controls, with untreated animals used as negative controls. After OR doses, FBZ is rapidly absorbed and cleared and the exposures increased dose proportionally. SC administered FBZ was slowly released from the injection site and plasma levels remained constant up to necropsy eight weeks after treatment end. Increasing single SC doses caused less than dose-proportional exposures. At necropsy, all animals receiving 1x or 5x 10mg/kg SC FBZ had cleared all adult worms and the 1x 2mg/kg SC treatment had reduced the adult worm burden by 98%. 10x 15mg/kg OR FBZ reduced the adult worm burden by 95%, whereas 1x 40mg/kg and 5x 15mg/kg OR reduced the worm burden by 85 and 84%, respectively. Microfilaremia was completely cleared at necropsy in all animals of the SC treatment regimens, while all oral FBZ treatment regimens reduced the microfilaremia by >90% in a dose and duration dependent manner. In accordance, embryograms from female worms revealed a FBZ dose and duration dependent inhibition of embryogenesis. Histological analysis of the remaining female adult worms showed that FBZ had damaged the body wall, intestine and most prominently the uterus and uterine content. Results of this study demonstrate that single and repeated SC injections and repeated oral administrations of FBZ have an excellent macrofilaricidal effect. [ABSTRACT FROM AUTHOR]

Study on Common Raven's diet is conducted in two regions in Algeria, region of Djelfa in the middle part of Algerian Highlands and region of Laghouat occupying a large part of Northern Algerian Sahara. Analysis of Corvus corax's regurgitation allowed us to count 2.726 individual-preys spread into 7 classes, 89 families, 26 orders and 232 preys-species. In term of F insects are the most ingested by Corvus corax. Rate of this class is of 81.1 % at level of El Guelta to reach 95.6 % in station of Sidi Mekhlouf. In term of biomass, Meriones shawii is the species the most profitable in weight in station of Sidi Mekhlouf (44.4 %), of Rocher des Pigeons (Pigeons Rock) (35.6 %) and even in station of El Guelta (14.3 %). However, in station of Dayet Zoujten, the highest biomass is presented by Gallus domesticus (42.1). This same observation is noted for species Gallus sp. (B % = 42.0 %) at level of El Mesrane. [ABSTRACT FROM AUTHOR]

The Mongolian squirrel is a murine rodent widely used as an experimental model and kept as a pet. With respect to the significance of the brachial plexus, we aimed to describe the origin and the nerves that constitute it, providing new information about the neuroanatomy of this species. Twenty adult animals were used, which were fixed in a 10% formaldehyde solution at the Applied Animal Morphophysiology Laboratory of the Brazilian Federal University of the Semi-Arid Region (UFERSA). The animals were medially incised with an opening of the thoracic cavity, and then bilateral dissection was carried out. Once the nerves were identified, cotton wool soaked with a 2% hydrogen peroxide solution was added for bleaching and better visualisation of structures. The gerbil brachial plexus derived from ventral roots of the fourth, fifth, sixth, seventh and eighth cervical nerves (C4-C8) and the first thoracic root (T1). The suprascapular nerve was formed from the nerve roots C4 and C5; the subscapular and cranial pectoral nerves from C5 and C6; the musculocutaneous and axillary nerves from C5, C6 and C7; and the caudal pectoral, radial, median, ulnar, thoracodorsal, lateral thoracic and long thoracic nerves from C7, C8 and T1. This resembles what is described in other rodents, such as the rat and capybara. The gerbil has a pre-fixed plexus conformation. [ABSTRACT FROM AUTHOR]

Jirds (Meriones) are a mostly desert-adapted genus of gerbils, with a wide geographic range, through which it encounters various climatic conditions, which may influence their morphology. In this study, we quantified cranial morphometric variation both within and among seven jird species (M. meridianus, M. hurrianae, M. crassus, M. tristrami, M. persicus, M. libycus and M. vinogradovi), based on a two-dimensional landmark-based geometric morphometric analysis of 972 specimens, covering their entire geographic distribution. The aforementioned analysis was used to compare sexual dimorphism in size and shape within each species, as well as the relationship between size and shape (i.e. allometry) for each species. Despite greatly overlapping in morphospace (when examined visually), statistical analysis indicates significant differences in both size and shape among the seven examined jird species. UPGMA and CVA both show two main species clusters. Deformation grids indicate that these two clusters differ mostly in the relative size of the tympanic bulla, along with differences in the extent of nasal elongation, and the broadness of the zygomatic arch. Allometric changes in shape were analyzed in all species that show an allometric relationship. Sexual dimorphism in shape and size was detected in only three of the seven jird species. A visual inspection of the data indicates high overlap in shape space, and that male skulls are significantly larger than female skulls. When specimens were divided by sex, we found significant allometry in six of the seven species (for both sexes). A factorial multivariate analysis of covariance (MANCOVA) indicated that even when taking size variation into account, the residual shape variation was also significantly different among the sexes of the examined species. The outcome of this study confirms the presence of cranial variation in the examined jirds, and that the patterns of sexual dimorphism and allometry vary considerably among jird species. [ABSTRACT FROM AUTHOR]

A parasitological survey of 107 jirds, belonging to two species, Meriones shawi and M. libycus, was carried out. Rodents were trapped in three separate desert regions of Tunisia: Bouhedma (in the centre), Dghoumes (in the southwest) and Sidi Toui (in the southeast). The survey revealed infection with nine helminth species – six cestodes: Raillietina sp., Meggittina numida, Meggittina gerbilli and Inermicapsifer madagascariensis, and two Taeniidae species: Taenia endothoracicus and Taenia sp.; and three nematodes: Gongylonema neoplasticum, Physaloptera sp. and Trichuris gerbilli. The overall prevalence of helminth infection was 68.22% (73/107); the highest rate was in M. shawi (80.82%, 59 cases), whereas it was 41.17% (14 cases) in M. libycus. The most frequent helminth was Raillietina sp. (53.27%) followed by Meggittina numida (21.5%). Merionesshawi showed the highest helminth diversity with eight parasite species, with synchronous infections of two, three and four species of helminths in one rodent, compared to M. libycus in which only two cestode species were found, without synchronous infection. Moreover, significant differences in the overall infection prevalence between sexes (60.27 and 39.73% for males and females, respectively) and age were detected; only one juvenile specimen of M. shawi was found infected. Prevalence depended also on habitat: the highest infection rate was in Bouhedma (80%), followed by Dghoumes (58.33%), and the lowest was in Sidi Toui (47.82%). [ABSTRACT FROM AUTHOR]

Background: Rodents have important role as reservoirs of different parasites. The aim of this study was to determine helminth parasites of abundant rodents in Meshkin-Shahr, Ardabil Province northwest Iran. Methods: From April 2014 to March 2015; 205 rodents including 118 Meriones persicus, 63 Mus musculus and 24 Cricetulus migratorius were collected, using live traps. All rodents were dissected and their different tissues examined for infectivity with helminth parasites. Results: Overall, 74.2% of rodents were infected with helminth parasites. The rate of infectivity in M. persicus, M. musculus and C. migratorius was 82.2%, 61.9%, 66.7%, respectively. In general, among all 205 rodents, the species and infection rates of helminthes were as follows: Nematoda: Trichuris sp. (46.8%), Capillaria hepatica (18.1%), Syphacia frederici (14.2%), Aspicularis tetraptera (3.4%), Trichuris rhombomidis (2%), Heligmosomom sp. (2%), Streptopharagus kuntzi (0.5%), Spiruridae gen. sp. (0.5%); Cestoda: Hymenolepis nana fraterna (16.6%) Hymenolepis diminuta (7.3%) tetratiridium of Mesocestoides sp. (1%), Paranoplocephala sp. (0.5%), Cysticercus fasciolaris (0.5%), Taenia endothoracicus larva (0.5%), and Acanthocephala: Moniliformis moniliformis (18.5%). Conclusions: Variable species of helminthes circulate in the rodents of the study area. Presence of several zoonotic species highlights the potential risk of infections for public health. [ABSTRACT FROM AUTHOR]

Eighteen jirds were equally distributed in two treated and one control groups. The commercial products to the fenbendazole base (10mg) and the association of febantel (1.5mg), pirantel (1.44mg) and praziquantel (0.5mg) were orally administred in the concentration of 0.1ml in each group. The effectiveness of febendazole against oxiurids was 81.8%, 65.0 and 38.7% and for the association of febantel, pirantel and praziquantel was 72.7%, 73.8% and 51.0% on days 7, 14 and 21, respectively. Three applications of that dose of the tested medications, within intervals of 10 days, associated to hygiene, are recommended.

The article discusses the problem concerning the increasing diversity of the Meriones libycus or also known as the Libyan jird. Topics covered include the prevalence of the subspecies of the Libyan jird in the Mongolian plateau and in Morocco as well as the examination of the genetic diversity of the jird which could be found in Tunisia and China. Also mentioned is the genetic differences between the samples of Meriones libycus from China and those from Saudi Arabia.

Rodents affect soil microbial communities by burrow architecture, diet composition, and foraging behavior. We examined the effect of desert rodents on nitrogen-fixing bacteria (NFB) communities by identifying bacteria colony-forming units (CFU) and measuring nitrogen fixation rates (ARA), denitrification (DA), and CO emission in soil from burrows of three gerbil species differing in diets. Psammomys obesus is folivorous, Meriones crassus is omnivorous, consuming green vegetation and seeds, and Dipodillus dasyurus is predominantly granivorous. We also identified NFB in the digestive tract of each rodent species and in Atriplex halimus and Anabasis articulata, dominant plants at the study site. ARA rates of soil from burrows of the rodent species were similar, and substantially lower than control soil, but rates of DA and CO emission differed significantly among burrows. Highest rates of DA and CO emission were measured in D. dasyurus burrows and lowest in P. obesus. CFU differed among bacteria isolates, which reflected dietary selection. Strains of cellulolytic representatives of the family Myxococcaceae and the genus Cytophaga dominated burrows of P. obesus, while enteric Bacteroides dominated burrows of D. dasyurus. Burrows of M. crassus contained both cellulolytic and enteric bacteria. Using discriminant function analysis, differences were revealed among burrow soils of all rodent species and control soil, and the two axes accounted for 91 % of the variance in bacterial occurrences. Differences in digestive tract bacterial occurrences were found among these rodent species. Bacterial colonies in P. obesus and M. crassus burrows were related to bacteria of A. articulata, the main plant consumed by both species. In contrast, bacteria colonies in the burrow soil of D. dasyurus were related to bacteria in its digestive tract. We concluded that gerbils play an important role as ecosystem engineers within their burrow environment and affect the microbial complex of the nitrogen-fixing organisms in soils. [ABSTRACT FROM AUTHOR]

A reliable disease model mimicking Enterovirus 71 (EV71) infection in humans is essential for understanding pathogenesis and for developing a safe and effective vaccine. Commonly used rodent models including mouse or rat models are not suitable for vaccine evaluation because the rodents are resistant to EV71 infection after they reach the age of 6 days. In this study, 21-day-old gerbils inoculated intraperitoneally (IP) with a non mouse-adapted EV71 strain developed neurological lesion-related signs including hind limb paralysis, slowness, ataxia and lethargy similar to those of central nervous system (CNS) infection of EV71 in humans. The infected gerbils eventually died of the neurological lesions and EV71 could be isolated from lung, liver, spleen, kidney, heart, spinal cord, brain cortex, brainstem and skeletal muscle. Significantly high virus replication was detected in spinal cord, brainstem and skeletal muscle by cellular analysis, real-time quantitative PCR (RT-PCR) and immunohistochemical staining. Histopathologic changes such as neuronal degeneration, neuronal loss and neuronophagia were observed in spinal cord, brain cortex, brainstem, and skeletal muscle along with necrotizing myositis and splenic atrophy. Gerbils that received two doses of inactive whole-virus vaccine showed no EV71-specific symptoms after challenged with EV71. In contrast, gerbils that received mock vaccination died of EV71-induced neuropathology after challenged with EV71. The result indicates that gerbils can serve as a reliable disease model for evaluating safety and efficacy of EV71 vaccine. [ABSTRACT FROM AUTHOR]

Abstract: In the present work we determined effects of a sub-chronic exposure to cadmium on some parameters of calcium and iodine metabolisms in Meriones shawi, a desert rodent species occupying the arid steppes of Tunisia and other countries. Fourteen jirds of both sex were equally divided into a control group receiving diet without cadmium and a treated group receiving cadmium in the diet during 30, 45, 60 and 90 days. At the end of each period, 5 jirds from each group were sacrificed. In cadmium-treated group, cadmium accumulation and total metallothioneins synthesis in the liver and kidneys were high and dependant on the duration of treatment. Cadmium caused significant modifications in the body weight and in the relative weights of the liver, femur and thyroids, in parallel to a decrease in calcium content in serum and in femur. Cadmium also decreased iodine content in serum and in the thyroids. Several impairments were dependant on the duration of exposure and were more pronounced at the end of the experiment. In conclusion, a sub-chronic exposure to cadmium induces perturbations in calcium and iodine metabolisms in Meriones shawi. However, effects on calcium seem to be more evident. We can conclude also that Meriones shawi is an indicator of cadmium presence in arid environments. [Copyright &y& Elsevier]

Background: The trehalose metabolic enzymes have been considered as potential targets for drug or vaccine in several organisms such as Mycobacterium, plant nematodes, insects and fungi due to crucial role of sugar trehalose in embryogenesis, glucose uptake and protection from stress. Trehalose-6-phosphate phosphatase (TPP) is one of the enzymes of trehalose biosynthesis that has not been reported in mammals. Silencing of tpp gene in Caenorhabditis elegans revealed an indispensable functional role of TPP in nematodes. Methodology and Principal Findings: In the present study, functional role of B. malayi tpp gene was investigated by siRNA mediated silencing which further validated this enzyme to be a putative antifilarial drug target. The silencing of tpp gene in adult female B. malayi brought about severe phenotypic deformities in the intrauterine stages such as distortion and embryonic development arrest. The motility of the parasites was significantly reduced and the microfilarial production as well as their in vitro release from the female worms was also drastically abridged. A majority of the microfilariae released in to the culture medium were found dead. B. malayi infective larvae which underwent tpp gene silencing showed 84.9% reduced adult worm establishment after inoculation into the peritoneal cavity of naïve jirds. Conclusions/Significance: The present findings suggest that B. malayi TPP plays an important role in the female worm embryogenesis, infectivity of the larvae and parasite viability. TPP enzyme of B. malayi therefore has the potential to be exploited as an antifilarial drug target. [ABSTRACT FROM AUTHOR]

Abstract: Dehydration is a powerful stimulus causing disequilibrium in homeostasis of water and electrolytes resulting from depletion in total body water. Most studies have focused on domestic and laboratory animals; however, the study of desert animals allows improved understanding about water balance and resistance to dehydration and associated behavioral changes, including those related to voluntary movements. Meriones shawi (Shaw''s Jird) is a desert rodent characterized by its resistance to long periods of thirst that can extend for several months. In the present study, M. shawi were subjected to water deprivation for 1month. We used tyrosine hydroxylase immunohistochemistry (TH: the key enzyme of catecholamine biosynthesis) to evaluate the effects of prolonged dehydration on the dopaminergic system in both substancia nigra pars compacta and ventral tegmental area (SNpc and VTA), which are the main sources of dopamine input to several brain areas; the immunolabelling was performed also in both the medial forebrain bundle and the caudate putamen (striatum). In addition, the open-field test was used to evaluate the effect of dehydration on locomotor activity in M. shawi. The results showed an increase in TH immunolabelling in both SNpc and VTA following 1month of dehydration compared to control levels. The same results were obtained with fibers in both MFB and striatum. This augmentation of TH immunoreactivity was accompanied by noticeable changes in locomotor activity behavior of Meriones, the recording test shows the hyperactivity of animals which is probably caused by dehydration. Overall, the results indicate that dehydration is able to increase dopaminergic neurotransmission, which might be involved in generating hyperactivity in this desert animal. [Copyright &y& Elsevier]

The article presents a study focusing on how transplantation of human neural stem or progenitor cells overexpressing galectin-1 improves functional recovery from focal brain ischemia in the mongolian gerbil. The findings of the study suggest the use of hGal1 in combination with transplantation of hNSPCs in the treatment of brain ischemia. It states that hNSPCs can generate all principle cell types such as neurons, astrocytes and oligodendrocytes in the brain and thus have great therapeutic potential in severe neurological diseases. The study offers an alternative method to apply hGal1 in the treatment of brain ischemia with transplantation of hNSPCs such as nestin-expressing hair follicle stem cells.

Background: In order to verify the infectivity of rodents with endoparasites in Germi (Dashte-Mogan, Ardabil Province) the current study was undertaken. Methods: Using live traps, 177 rodents were trapped during 2005-2007. In field laboratory, all rodents were bled prior to autopsy, frozen at -20°C, and shipped to the School of Public Health, Tehran University of Medical Sciences, Iran. In parasitological laboratory, every rodent was dissected and its different organs were examined for the presence of any parasite. Blood thick and thin smears as well as impression smears of liver and spleen were stained with Geimsa and examined microscopically. Results: Two species of rodents were trapped; Meriones persicus (90.4%) and Microtus socialis (9.6%). The species of parasites found in M. persicus and their prevalences were as follows: Hymenolepis diminuta (38.8%), Hymenolepis nana (2.5%), Trichuris sp.(40.6), Mesocestoides larva (=tetrathyridium) (3.1%), Capillaria hepatica (6.9%), Moniliformis moniliformis (11.3%), Syphacia obvelata (2.5%), Taenia endothoracicus larva (0.6%), Physaloptera sp. (0.6%), Dentostomella translucida (0.6%), Heligmosomum mixtum (0.6%), Strobilocercus fasciolaris (0.6%),and Aspiculuris tetraptera (0.6%). The species of parasites found in M. socialis and their prevalences were as follows: H. diminuta (17.6%), Trichuris sp. (5.9%), Mesocestoides larva (5.9%), S. obvelata (11.8%), S. syphacia (11.8%), H. mixtum (17.6%), and Aspiculuris tetraptera (11.8%). There were no statistical differences between male and female for infectivity with parasites in either M. persicus or M. socialis. No blood or tissue protozoan parasite was found in any of the rodents examined. Conclusion: Among different species identified, some had zoonotic importance. Therefore, the potential health hazard of these species needs to be considered to prevent infectivity of humans. [ABSTRACT FROM AUTHOR]

It has become difficult in recent years to conduct the direct feeding of mosquitoes on animals because of ethical considerations related to animal experimentation. Thus, the artificial feeding of mosquitoes on blood meals is an important technique in studies on the oral infection of mosquitoes to agents. Since Rutledge et al. (1964) devised the artificial membrane-feeding technique, several artificial membrane-feeding methods have been developed to increase the feeding rates of mosquitoes on blood meals. The purpose of the present study is to develop a simple and convenient device for the artificial feeding of mosquitoes.We designed a device using Kimwipe®, a coverglass, the lid of a plastic dish and a 50 ml Erlenmeyer flask. The efficacy was assessed by the infection rate of mosquitoes to Brugia pahangi microfilariae (MF) derived from the peritoneal cavity of Mongolian jirds. Immediately after the feeding of mosquitoes on MF by the new device, the MF infection rate of mosquitoes was 50 - 81%. On day 14 post-feeding, 51 - 94% of mosquitoes harbored third-stage infective larvae. The components needed to construct the device for artificial feeding of mosquitoes are generally available in laboratories. Furthermore, no elaborate modification of materials is necessary in making the feeding device. Therefore, this simple and convenient artificial feeding device promises to be applicable for experimental infection of mosquitoes not only with B. pahangi MF but also with other agents such as malaria and viruses. [ABSTRACT FROM AUTHOR]

The distribution of nucleolar organizer regions (NORs) in Cricetulus migratorius and Meriones tristrami from Central Anatolia was determined. In the karyotype of Cricetulus migratorius the diploid number, fundamental number, and fundamental autosomal number are 22, 44, and 40, respectively. The diploid number, fundamental number, and fundamental autosomal number of Meriones tristrami are 72, 84, and 80, respectively. In Cricetulus migratorius, NORs occur in the telomeric regions of metacentric and subtelocentric autosome pairs. Furthermore, terminally located NORs in metacentric and acrocentric autosomes of Meriones tristrami are presented in this present paper. [ABSTRACT FROM AUTHOR]

Abstract: The effect of in vivo administered hexachlorobenzene (HCB) on liver and thyroid was studied on Meriones unguiculatus. HCB (1.6, 4, and 16 mg/kg of body weight) has been administered orally to meriones for 30 days. At the end of the experiment, the body weight of the animals did not show significant change. However, the higher dose of HCB treatment led to a pronounced hepatic hypertrophy comparatively to controls. Histological observations revealed many cytomorphological alterations. Cellular necrosis, periportal, and centrolobular vein congestion and cytoplasmic vacuolisation were noted and correlated with the administered doses of HCB. The higher dose of HCB induced modifications in the activities of hepatic transaminases and on thyroid hormones levels: ALAT activity level was more pronounced in males ( vs. in controls) than in females ( vs. in controls). However, ASAT activity increased significantly only in females ( vs. in controls). Plasma total triiodothyronine (TT3) and total thyroxine (TT4) levels seemed to be sex-dependent in intoxicated animals, since TT4 decreased significantly in males ( vs. in controls) and TT3 in females ( vs. in controls). To cite this article: L. Bitri et al., C. R. Biologies 330 (2007). [Copyright &y& Elsevier]

During a field excursion in eastern Turkey and the Zanjan province of Iran, 9 rodent species were captured, and the diploid number of chromosomes (2n), the number of autosomal arms (FNa) and the fundamental number (FN) were determined for these species. Microtus schidlovskiiwith 2n = 60 and FNa = 58 was recorded for the first time from Özalp (Van) and Yüksekova (Hakkari). The karyological record of Meriones vinogradovi in Turkey was also given for the first time. The karyological results were determined as follows: Spermophilus xanthophrymnus (2n = 42, FNa = 78, FN = 82 in Turkey), Mesocricetus brandti (2n = 42, FNa = 78, FN = 82 in Iran), Microtus socialis(2n = 62, FNa = 60 FN = 62 in Iran, 2n = 60, FNa = 58 FN = 60 in Turkey), Meriones tristrami (2n = 72, FNa = 78, FN = 80 in Iran, 2n = 72, FNa = 82, FN = 84 in Turkey), M. vinogradovi (2n = 44, FNa = 74, FN = 77 in Turkey), Meriones libycus(2n = 44, FNa = 76, FN = 80 in Iran), Apodemus iconicus(2n = 48, FNa = 46, FN = 48 in Iran), and Mus domesticus(2n = 40, FNa = 38, FN = 40 in Iran and Turkey). [ABSTRACT FROM AUTHOR]

In 167 cases of granulosa cell tumour (GCT) in the gerbil, Meriones unguiculatus, 42.5% (71 cases) were in the ovaries, with no evidence of macroscopic lesion. In this paper, we describe the common findings in the incipient – microscopic – type of this spontaneous ovarian tumour occurring in gerbils younger than two years of age. [ABSTRACT FROM AUTHOR]

We investigated seasonality of gender differences in the patterns of flea infestation in nine rodent species to test if sex-biased parasitism in terms of mean abundance, species richness, prevalence and the level of aggregation (a) varies among hosts and between seasons, and (b) is linked to sexual size dimorphism. Sexual size differences were significant in both summer and winter in Acomys cahirinus, Gerbillus pyramidum and Meriones crassus, and in winter only in Acomys russatus, Gerbillus dasyurus, Gerbillus nanus and Sekeetamys calurus. Sexual size dimorphism was male biased except for A. russatus in which it was female biased. Manifestation of sexual differences in flea infestation was different among hosts between seasons. A significant effect of sex on mean flea abundance was found in six hosts, on mean flea species richness in five hosts and on prevalence in two hosts. Male-biased parasitism was found in summer in one host only and in winter in five hosts. Female-biased parasitism occurred in winter in A. russatus. Gender differences in the slopes of the regressions of log-transformed variances against log-transformed mean abundances occurred in three hosts. No relationship was found between sexual size dimorphism and any parasitological parameter in any season using both conventional regressions and the method of independent contrasts. Our results suggest that sex-biased parasitism is a complicated phenomenon that involves several different mechanisms. [ABSTRACT FROM AUTHOR]

The present study measured the head-related transfer functions (HRTFs) of the Mongolian gerbil for various sound-source directions, and explored acoustical cues for sound localization that could be available to the animals. The HRTF exhibited spectral notches for frequencies above 25 kHz. The notch frequency varied systematically with source direction, and thereby characterized the source directions well. The frequency dependence of the acoustical axis, the direction for which the HRTF amplitude was maximal, was relatively irregular and inconsistent between ears and animals. The frequency-by-frequency plot of the interaural level difference (ILD) exhibited positive and negative peaks, with maximum values of 30 dB at around 30 kHz. The ILD peak frequency had a relatively irregular spatial distribution, implying a poor sound localization cue. The binaural acoustical axis (the direction with the maximum ILD magnitude) showed relatively orderly clustering around certain frequencies, the pattern being fairly consistent among animals. The interaural time differences (ITDs) were also measured and fell in a ±120 μs range. When two different animal postures were compared (i.e., the animal was standing on its hind legs and prone), small but consistent differences were found for the lower rear directions on the HRTF amplitudes, the ILDs, and the ITDs. [ABSTRACT FROM AUTHOR]

The Mongolian gerbil is an excellent animal model for Helicobacter pylori-induced gastritis in humans. In this study, initially low colonization rates of the H. pylori strains ATCC 43504, SS1, or HP87 inoculated into gerbils caused difficulties in establishing this model. In order to increase the colonization ability and pathogenicity, the clinical HP87 isolate was selected for adaptation to the gerbil stomach by multiple in vivo passages through gerbils. Development of gastritis was examined histologically at 452 weeks after infection. The proportion of gerbils which tested positive for H. pylori by culture at four weeks after inoculation gradually increased from 11.1% of gerbils inoculated with HP87 without prior in vivo passage (P0) to 100% of gerbils inoculated with HP87 with seven in vivo passages (P7). In addition, adaptation of HP87 resulted in more severe histopathological changes. Gerbils infected with adapted HP87 (P7) exhibited severe infiltration by monomorphonuclear and polymorphonuclear leukocytes in the mucosa, submucosa, and subserosa of the gastric antrum, as well as epithelial changes consisting of hyperplasia, erosion, and ulceration. Histopathological changes increased in severity from four to 52 weeks after infection. Adaptation of HP87 during its passages through gerbils could be due to genetic changes in bacterial colonization factors. Identification of these changes might be useful to understand the underlying mechanism of gastric adaptation and pathogenesis of H. pylori. [ABSTRACT FROM AUTHOR]

Telemetric investigations of various parameters are widely used to estimate an animal's state. However, the implantation of the transmitters includes anaesthesia and surgery and has short and longer lasting impacts on the studied object. The aim of the present paper was to evaluate these effects in Mongolian gerbils, namely the hypothermia caused by the anaesthetic and the enduring disturbance of daily rhythmicity until complete recovery. The surgery associated with the implantation of the transmitters differed both in severity and type of anaesthesia. Whereas normal values of body temperature were restored within hours, restoration of daily rhythm required several days, depending on the severity of the surgical procedure. Also, the sensitivity of the body temperature to activity changes was different until the rhythms were re-established. A method based on the rhythm magnitude and shape was proposed to estimate the time until complete recovery of the animals. [ABSTRACT FROM AUTHOR]

1. Fleas Xenopsylla conformis and Xenopsylla ramesis parasitize the rodents Meriones crassus and Gerbillus dasyurus. Previously reported isodar analysis of host selection suggested that at low density, X. conformis parasitizes M. crassus only, but with an increase in flea density, G. dasyurus is also parasitized. Xenopsylla ramesis at low density parasitizes both hosts equally, whereas at high density prefers M. crassus. The ultimate cause of underlying these patterns was suggested to be differential fitness reward of parasitism on a particular host species, while the mechanism can be adaptive host selection by fleas. 2. To justify the suggested fitness–density relations, we studied reproductive success in X. conformis and X. ramesis feeding on either M. crassus or G. dasyurus. We hypothesized that reproductive success would differ between two host species for each flea species. 3. Xenopsylla conformis parasitizing M. crassus produced more eggs than when parasitizing G. dasyurus, whereas time of oviposition and larval hatching did not depend on host species. In contrast, egg production in X. ramesis did not differ between host species. However, fleas fed on M. crassus needed fewer bloodmeals, oviposited earlier and hatching of their larvae took less time than those of fleas fed on G. dasyurus. 4. Patterns of egg production and development time in both fleas were consistent with the hypothesis that their between-host distribution arose from adaptive host selection strategy. Journal of Animal Ecology (2004) 73, 815 –820 [ABSTRACT FROM AUTHOR]

Gap detection using broadband noise was characterized in a group of young gerbils from the breeding colony of the University of Regensburg (RB gerbils), old RB gerbils, and old gerbils from the breeding colony of the University of South Carolina (SC gerbils). Data from old RB and old SC gerbils were not significantly different and were subsequently combined for a comparison with data from the group of young RB gerbils. Level dependence of gap-detection thresholds in young and old domesticated gerbils resembled the typical mammalian pattern of level dependence. Gap-detection thresholds of old gerbils were significantly elevated at 30 dB SL and 50 dB SPL as compared with young gerbils. Compared with young gerbils tested at 30 dB SL and 50 dB SPL, the distribution of gap-detection thresholds in old gerbils was broader with a spread to higher gap-detection thresholds. Some old animals retained excellent temporal resolution, while some showed impaired gap detection. The gap-detection data collected in young and old gerbils resemble previously published data from humans of different age and confirm that gerbils are a useful model to study age-dependent changes in temporal processing. [ABSTRACT FROM AUTHOR]

Summary 1. Non-reproducing Sundevall Jird (Meriones crassus ) females (body mass = 84 g; n = 51), with a mean average daily metabolic rate (ADMR) of 88 kJ day-1 , were divided into three groups: high (H), medium (M) and low (L) ADMR. It was hypothesized that ADMR is related to reproductive rate and predicted that the H group could support a higher reproductive rate than the L group. It was also hypothesized that allocation of energy differs with ADMR level and predicted that the H group would use mainly the reallocation of metabolizable energy to compensate for an increased energy demand for reproduction whereas the L group would increase their metabolizable energy intake markedly. To test the hypotheses, the females were mated and, in those that had litters (n = 32), changes in body mass and metabolizable energy intake were determined and milk production was estimated during 15 days of lactation. Litter size, offspring mass and growth rate were determined for pups. 2. Body mass of dams, litter size and body mass of young at birth were similar among ADMR groups. However, milk production was 42% higher and litter mass at 15 days was significantly greater in the H than in L group, supporting our first hypothesis. All females were in negative energy balance during lactation. Mobilization of body energy reserves increased with litter size but was similar among ADMR groups. In addition, the increase in metabolizable energy intake of lactating females above that of non-reproducing females was similar among ADMR groups and therefore the second hypothesis was rejected. 3. ADMR was reduced by 23% during lactation and milk energy was only 30% of total metabolizable energy invested in milk production in all females. It is concluded that lactating M. crassus used a combination of reallocation of energy and increased metabolizable energy intake during lactation. The efficiency of offspring production did not differ among ADMR groups and therefore a high ADMR has an advantage when food is abundant, whereas a low ADMR has an advantage when food is sparse. [ABSTRACT FROM AUTHOR]

Presents information on a study which assessed the role of photoperiod in adult testicular maintenance and body weight and juvenile development in male Mongolian gerbils. Materials and methods used in the study; Results and discussion.

Both antigen specific and non-specific immunoregulation by cells have been described in jirds infected with Brugia pahangi, but the contribution of serum factors to immunoregulatory phenomena in this infection has not been examined. The present study determined the effect of serum from normal or B. pahangi infected jirds on the mitogen responsiveness of spleen cells from uninfected animals and on the antigen responsiveness of lymph node cells (LNC) from infected jirds. Addition of heat-inactivated jird serum to cultures of cells supplemented with 1% fetal bovine serum demonstrated that serum from chronically infected (⩾ 20 weeks post-infection), but not normal jirds consistently suppressed responsiveness of LNC from infected jirds to B. pahangi extracts in a dose-dependent manner (0.25%-1% concentration). A comparison of sera from jirds at different times post-infection demonstrated that sera (1%) from chronically infected (30 weeks; 100% suppression), but not acutely infected (4 weeks; 0% suppression) or recently microfilaremic (10 weeks; 11% suppression) animals were capable of suppressing antigen reactivity of LNC. In contrast, the inhibitory effect of serum on lymphocyte reactivity to the mitogens, PHA and PWM, was observed intermittently throughout the course of the infection and was less than the effect of chronic serum on antigen responsiveness. The B. palangi antigen response of spleen cells from infected jirds depleted of suppressor cells by fractionation over nylon wool was also inhibited by chronic sera. Following fractionation of chronic sera by Sephadex G-200 chromatography, suppressor activity was observed in the void volume and IgG peaks. Suppressor activity was not associated with protein A, anti-jird Ig, or B. pahangi antigen bound fractions, nor with polyethylene glycol precipitable material. [ABSTRACT FROM AUTHOR]

Histamine is known to mediate potent immunosuppressive effects on lymphocyte function. In jirds infected with Brugia pahangi decreased mitogen and parasite antigen responsiveness are associated with the presence of histamine binding regulatory cells. The present study was thus designed to investigate the immunoregulatory role of histamine in experimental filariasis. Spleen cells from normal or B. pahangi infected jirds were incubated with BSA or histamine coupled Sepharose beads and the degree of cell-bead binding was quantitated. Cells from infected jirds demonstrated increased levels of histamine, but not BSA binding relative to normal cells, and this binding was blocked by soluble histamine or by the histamine receptor antagonist cimetidine. Cimetidine failed to restore the in vitro responsiveness of spleen cells from infected jirds to phytohemagglutinin or to a soluble extract of B. pahangi. Cimetidine did, however, reverse histamine-induced suppression of normal spleen cell responses to PHA. The present results suggest that histamine does not play a major role in the immunoregulatory alterations induced by B. pahangi infection. [ABSTRACT FROM AUTHOR]

Mongolian gerbils were observed over seasonal changes in day length and temperature in an outdoor enclosure containing an extensive burrow system. Animals could choose between the stable environment of their burrow and the daily and seasonal fluctuations aboveground. Surgically implanted radio transmitters provided body temperature and location of animals. Gerbils avoided temperature extremes by emerging from their burrow when ambient temperature fell below burrow temperature in hot weather and rose above burrow temperature in cold weather. They delayed emergence in the winter until several hours after sunrise and emerged before or after sunset in summer (Fig. 1). Circadian changes in core-body temperature corresponded to increases and decreases in behavioral activity. Emergence from the burrow was predictable by an increase in body temperature, as a 'warm-up' period preceded emergence (Fig. 3). We conclude that gerbils, when subjected to extreme temperatures in the wild, probably time their activity to correspond to preferred ambient temperatures and thus shift from diurnal activity in the winter to nocturnal activity in the summer (Fig. 2). This desert rodent's exceptional thermoregulatory capacity adapts it for synchronizing its daily activity to temperature. [ABSTRACT FROM AUTHOR]

The article focuses on an epidemiological study in Metlaoui province in Southwestern Tunisia with the objective of detecting and characterizing Leishmania killicki infection in wild rodents. In 2009, wild rodents including Psammomys obesus, Ctenodactylus gundi, Meriones shawi and Mus musculus were trapped alive. They were examined for the existence of skin lesions. The detection of Leishmania killicki in Ctenodactylus gundi by both direct examination and polymerase chain reaction (PCR) method is the first proof of the role of the rodent as a natural host of the parasite.

The Mongolian gerbil is commonly used in medical research. Intravenous administration of compounds in gerbils is difficult as tail vein injection sites are not visible. The present study describes a method for intravenous administration into the jugular vein in Mongolian gerbil by using an 'over-the-needle' catheter under anaesthesia. The catheter penetrates the pectoral muscle and is easily inserted into the vein. The method is simple and avoids extensive surgery in the animals. [ABSTRACT FROM AUTHOR]

The article discusses a study, conducted by a team of researchers, including Inbal Brickner-Braun, Daniel Zucker-Milwerger, and colleagues, from Ben-Gurion University of the Negev, Israel and the State University of New York College of Environmental Science and Forestry (ESF-SUNY), which focuses on the ventilation of burrows of Sundevall's jird, a small species of rodent. The researchers found that the carbon dioxide levels in the burrows of rodent species were same as those on the surface.

This article cites a study conducted to examine the effects of long term Helicobacter pylori infection in the Mongolian gerbil on gastric expression of the tyrosine kinase receptors EGFR and c-Met, and of membrane metalloprotease ADAM 17 and COX-2. Results of the study suggests that long term Helicobacter pylori infection in gerbils results in increased gastric expression of EGFR and c-Met receptors which are known to be activated by Helicobacter pylon in vitro. In addition, ADAM 17 and COX-2 transcripts are significantly increased.

Discusses research on interaural time difference (ITD) among the Mongolian gerbil. Reference to a study by A. Brand and colleagues published in "Nature" journal; Model for calculating position from ITD; Information on the neuronal activity in the medial superior olive of the gerbil brain.