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Knowing the genes involved in quantitative traits provides an entry point to understanding the biological bases of behavior, but there are very few examples where the pathway from genetic locus to behavioral change is known. To explore the role of specific genes in fear behavior, we mapped three fear-related traits, tested fourteen genes at six quantitative trait loci (QTLs) by quantitative complementation, and identified six genes. Four genes, Lamp, Ptprd, Nptx2, and Sh3gl, have known roles in synapse function; the fifth, Psip1, was not previously implicated in behavior; and the sixth is a long non-coding RNA, 4933413L06Rik, of unknown function. Variation in transcriptome and epigenetic modalities occurred preferentially in excitatory neurons, suggesting that genetic variation is more permissible in excitatory than inhibitory neuronal circuits. Our results relieve a bottleneck in using genetic mapping of QTLs to uncover biology underlying behavior and prompt a reconsideration of expected relationships between genetic and functional variation.

Relating genetic variants to behavior remains a fundamental challenge. To assess the utility of DNA methylation marks in discovering causative variants, we examined their relationship to genetic variation by generating single-nucleus methylomes from the hippocampus of eight inbred mouse strains. At CpG sequence densities under 40 CpG/Kb, cells compensate for loss of methylated sites by methylating additional sites to maintain methylation levels. At higher CpG sequence densities, the exact location of a methylated site becomes more important, suggesting that variants affecting methylation will have a greater effect when occurring in higher CpG densities than in lower. We found this to be true for a variant's effect on transcript abundance, indicating that candidate variants can be prioritized based on CpG sequence density. Our findings imply that DNA methylation influences the likelihood that mutations occur at specific sites in the genome, supporting the view that the distribution of mutations is not random.

Inbred mouse strains KK.Cg-a/a and KK.Cg-Ay/a known as genetic models of type 2 diabetes mellitus significantly surpassed the control strain C57BL/6J in the body weight, relative weight of extractable fat, and basal blood glucose levels. Real-timePCR of fecal samples from KK.Cg-a/a and KK.Cg-Ay/a mice revealed dysbiosis typical of type 2 diabetes mellitus in humans and animals. Long-term intragastric administration of a suspension of Hafnia alvei bacteria had no effect on the above morphometric and biochemical parameters. At the same time, recovery of the Bacteroides spp. population in KK.Cg-Ay/a mice and a decrease in the number of Bifidobacterium spp. in KK.Cg-a/a mice were observed. The possibility of therapeutic use of the probiotic based on H. alvei is discussed. [ABSTRACT FROM AUTHOR]

A major challenge in neuroscience is to pinpoint neurobiological correlates of specific cognitive and neuropsychiatric traits. At the mesoscopic level, promising candidates for establishing such connections are brain oscillations that can be robustly recorded as local field potentials with varying frequencies in the hippocampus in vivo and in vitro. Inbred mouse strains show natural variation in hippocampal synaptic plasticity (e.g. long‐term potentiation), a cellular correlate of learning and memory. However, their diversity in expression of different types of hippocampal network oscillations has not been fully explored. Here, we investigated hippocampal network oscillations in three widely used inbred mouse strains: C57BL/6J (B6J), C57BL/6NCrl (B6N) and 129S2/SvPasCrl (129) with the aim to identify common oscillatory characteristics in inbred mouse strains that show aberrant emotional/cognitive behaviour (B6N and 129) and compare them to "control" B6J strain. First, we detected higher gamma oscillation power in the hippocampal CA3 of both B6N and 129 strains. Second, higher incidence of hippocampal sharp wave‐ripple (SPW‐R) transients was evident in these strains. Third, we observed prominent differences in the densities of distinct interneuron types and CA3 associative network activity, which are indispensable for sustainment of mesoscopic network oscillations. Together, these results add further evidence to profound physiological differences among inbred mouse strains commonly used in neuroscience research. [ABSTRACT FROM AUTHOR]

It is known that the ability of an animal to exert social dominance in the community depends on a complex of behavioral and physiological peculiarities that can be predetermined by the genotype. However, the significance of each of these peculiarities of dominant rank remains unclear, especially when the environmental conditions for the formation of a hierarchy change. The degree of development of the habitat and the presence of a sexual partner are the most important factors determining the patterns of male behavior during the formation of social hierarchy. When using a "resident–intruder" paradigm, the peculiarities of olfactory contacts and agonistic and marking behavior were studied with a pairwise placement of male laboratory mice of two inbred strains in the experimental model of the formation of the social hierarchy. Sexually mature (age 90 days) male mice of the PT and CBA/Lac inbred strains and females of the DD/He inbred strain without preliminary sexual experience were used in this work. A male intruder of another strain was seated next to a resident male, which was preliminarily placed with a female of DD/He strain in the experimental cage for two days for the development of the territory. After this, the agonistic behavior of males was observed for the first 30 min after the group formation. In addition, the marking activity of males was estimated before the formation of the social group and in the period of the establishment of dominant–subordinate relations. Preliminary development of the territory by the male increased the aggression and the probability of dominance in animals of both genotypes. However, regardless of the degree of development of the territory, PT strain males demonstrated more offensive attacks and became dominant more often than CBA/Lac strain males. Genetic differences in the marking activity of males were not associated with those by social dominance. The results of this study indicate that a genetically determined ability to exert social dominance in males of inbred mouse strains is first of all associated with genetic differences in agonistic behavior, but not with the level of marking behavior, regardless of the degree of development of the territory. [ABSTRACT FROM AUTHOR]

Previously the effect of the pruritogens, such as histamine and chloroquine, was tested in 11 inbred mouse strains, and this study aimed to identify resistant and sensitive strains, consistent with the observation that underlies the large variability in human populations. In the present study, we used the low responder C3H/HeJ (C3H) and the more sensitive C57BL/6J (C57) strain to find out if resistance and sensitivity to develop pruritus is restricted to only histamine and chloroquine or extends to other known pruritogens as well. We tested five additional commonly known pruritogens. We established dose- response relationships by injecting four concentrations of the pruritogens in the range of 0.3, 1, 3, and ten-fold in the nuchal fold. Then we assessed the scratching behavior for 30min after injection with an automated custom- designed device based on the bilateral implantation of mini-magnets in the hind paws and on single cages placed within a magnetic coil. We found that the resistance to pruritogens is a general phenotype of the C3H strain and extends to all pruritogens tested, including not only histamine and chloroquine, but also endothelin, trypsin, 5-HT (serotonin), the short peptide SLIGRL, and Lysophosphatidic acid (LPA). C57 was more sensitive to all pruritogens and, in contrast to C3H, dose-response relationships were evident for some of the pruritogens. In general, comparable peak scratch responses were observed for the 0.3-fold concentrations of the pruritogens in C57 whereas C3H required at least the ten-fold concentration and still displayed only between 5 and 33% of the scratch responses observed in C57 for the respective pruritogen. The general resistance to pruritogens and the low level of scratching behavior found in the C3H strain is an interesting trait and represents a model for the study of the heritability of itch. It is accompanied in C3H with a higher sensitivity in assays of nociception. [ABSTRACT FROM AUTHOR]

Abstract Background Genetic variation in a population has an influence on the manifestation of monogenic as well as multifactorial disorders, with the underlying genetic contribution dependent on several interacting variants. Common laboratory mouse strains used for modelling human disease lack the genetic variability of the human population. Therefore, outcomes of rodent studies show limited relevance to human disease. The functionality of brain vasculature is an important modifier of brain diseases. Importantly, the restrictive interface between blood and brain—the blood–brain barrier (BBB) serves as a major obstacle for the drug delivery into the central nervous system (CNS). Using genetically diverse mouse strains, we aimed to investigate the phenotypic and transcriptomic variation of the healthy BBB in different inbred mouse strains. Methods We investigated the heterogeneity of brain vasculature in recently wild-derived mouse strains (CAST/EiJ, WSB/EiJ, PWK/PhJ) and long-inbred mouse strains (129S1/SvImJ, A/J, C57BL/6J, DBA/2J, NOD/ShiLtJ) using different phenotypic arms. We used immunohistochemistry and confocal laser microscopy followed by quantitative image analysis to determine vascular density and pericyte coverage in two brain regions—cortex and hippocampus. Using a low molecular weight fluorescence tracer, sodium fluorescein and spectrophotometry analysis, we assessed BBB permeability in young and aged mice of selected strains. For further phenotypic characterization of endothelial cells in inbred mouse strains, we performed bulk RNA sequencing of sorted endothelial cells isolated from cortex and hippocampus. Results Cortical vessel density and pericyte coverage did not differ among the investigated strains, except in the cortex, where PWK/PhJ showed lower vessel density compared to NOD/ShiLtJ, and a higher pericyte coverage than DBA/2J. The vascular density in the hippocampus differed among analyzed strains but not the pericyte coverage. The staining patterns of endothelial arteriovenous zonation markers were similar in different strains. BBB permeability to a small fluorescent tracer, sodium fluorescein, was also similar in different strains, except in the hippocampus where the CAST/EiJ showed higher permeability than NOD/ShiLtJ. Transcriptomic analysis of endothelial cells revealed that sex of the animal was a major determinant of gene expression differences. In addition, the expression level of several genes implicated in endothelial function and BBB biology differed between wild-derived and long-inbred mouse strains. In aged mice of three investigated strains (DBA/2J, A/J, C57BL/6J) vascular density and pericyte coverage did not change—expect for DBA/2J, whereas vascular permeability to sodium fluorescein increased in all three strains. Conclusions Our analysis shows that although there were no major differences in parenchymal vascular morphology and paracellular BBB permeability for small molecular weight tracer between investigated mouse strains or sexes, transcriptomic differences of brain endothelial cells point to variation in gene expression of the intact BBB. These baseline variances might be confounding factors in pathological conditions that may lead to a differential functional outcome dependent on the sex or genetic polymorphism.

Background: Genetic variation in a population has an influence on the manifestation of monogenic as well as multifactorial disorders, with the underlying genetic contribution dependent on several interacting variants. Common laboratory mouse strains used for modelling human disease lack the genetic variability of the human population. Therefore, outcomes of rodent studies show limited relevance to human disease. The functionality of brain vasculature is an important modifier of brain diseases. Importantly, the restrictive interface between blood and brain—the blood–brain barrier (BBB) serves as a major obstacle for the drug delivery into the central nervous system (CNS). Using genetically diverse mouse strains, we aimed to investigate the phenotypic and transcriptomic variation of the healthy BBB in different inbred mouse strains. Methods: We investigated the heterogeneity of brain vasculature in recently wild-derived mouse strains (CAST/EiJ, WSB/EiJ, PWK/PhJ) and long-inbred mouse strains (129S1/SvImJ, A/J, C57BL/6J, DBA/2J, NOD/ShiLtJ) using different phenotypic arms. We used immunohistochemistry and confocal laser microscopy followed by quantitative image analysis to determine vascular density and pericyte coverage in two brain regions—cortex and hippocampus. Using a low molecular weight fluorescence tracer, sodium fluorescein and spectrophotometry analysis, we assessed BBB permeability in young and aged mice of selected strains. For further phenotypic characterization of endothelial cells in inbred mouse strains, we performed bulk RNA sequencing of sorted endothelial cells isolated from cortex and hippocampus. Results: Cortical vessel density and pericyte coverage did not differ among the investigated strains, except in the cortex, where PWK/PhJ showed lower vessel density compared to NOD/ShiLtJ, and a higher pericyte coverage than DBA/2J. The vascular density in the hippocampus differed among analyzed strains but not the pericyte coverage. The staining patterns of endothelial arteriovenous zonation markers were similar in different strains. BBB permeability to a small fluorescent tracer, sodium fluorescein, was also similar in different strains, except in the hippocampus where the CAST/EiJ showed higher permeability than NOD/ShiLtJ. Transcriptomic analysis of endothelial cells revealed that sex of the animal was a major determinant of gene expression differences. In addition, the expression level of several genes implicated in endothelial function and BBB biology differed between wild-derived and long-inbred mouse strains. In aged mice of three investigated strains (DBA/2J, A/J, C57BL/6J) vascular density and pericyte coverage did not change—expect for DBA/2J, whereas vascular permeability to sodium fluorescein increased in all three strains. Conclusions: Our analysis shows that although there were no major differences in parenchymal vascular morphology and paracellular BBB permeability for small molecular weight tracer between investigated mouse strains or sexes, transcriptomic differences of brain endothelial cells point to variation in gene expression of the intact BBB. These baseline variances might be confounding factors in pathological conditions that may lead to a differential functional outcome dependent on the sex or genetic polymorphism. [ABSTRACT FROM AUTHOR]

Regulatory T lymphocytes (Treg) play a vital role in the protection of the organism against autoimmune pathology. It is therefore paradoxical that comparatively large numbers of Treg were found in the thymus of type I diabetes‐prone NOD mice. The Treg population in the thymus is composed of newly developing cells and cells that had recirculated from the periphery back to the thymus. We here demonstrate that exceptionally large numbers of Treg develop in the thymus of young, but not adult, NOD mice. Once emigrated from the thymus, an unusually large proportion of these Treg is activated in the periphery, which causes a particularly abundant accumulation of recirculating Treg in the thymus. These cells then rapidly inhibit de novo development of Treg. The proportions of developing Treg thus reach levels similar to or lower than those found in most other, type 1 diabetes‐resistant, inbred mouse strains. Thus, in adult NOD mice the particularly large Treg‐niche is actually composed of mostly recirculating cells and only few newly developing Treg. [ABSTRACT FROM AUTHOR]

The glutaric acidurias are a group of inborn errors of metabolism with different etiologies. Glutaric aciduria type 3 (GA3) is a biochemical phenotype with uncertain clinical relevance caused by a deficiency of succinyl-CoA:glutarate-CoA transferase (SUGCT). SUGCT catalyzes the succinyl-CoA-dependent conversion of glutaric acid into glutaryl-CoA preventing urinary loss of the organic acid. Here, we describe the presence of a GA3 trait in mice of 129 substrains due to SUGCT deficiency, which was identified by screening of urine organic acid profiles obtained from different inbred mouse strains including 129S2/SvPasCrl. Molecular and biochemical analyses in an F2 population of the parental C57BL/6J and 129S2/SvPasCrl strains (B6129F2) confirmed that the GA3 trait occurred in Sugct 129/129 animals. We evaluated the impact of SUGCT deficiency on metabolite accumulation in the glutaric aciduria type 1 (GA1) mouse model. We found that GA1 mice with SUGCT deficiency have decreased excretion of urine 3-hydroxyglutaric acid and decreased levels glutarylcarnitine in urine, plasma and kidney. Our work demonstrates that SUGCT contributes to the production of glutaryl-CoA under conditions of low and pathologically high glutaric acid levels. Our work also highlights the notion that unexpected biochemical phenotypes can occur in widely used inbred animal lines. [ABSTRACT FROM AUTHOR]

We measured indirect calorimetry and activity parameters, VO2 and VCO2 to extract respiratory exchange ratio (RER) and energy expenditure in both sexes of 30 inbred mouse strains of 6 genetic families at 9–13 weeks during one photophase and the subsequent scotophase. We observed a continuous distribution of all traits. While males had higher body weights than females, we observed no sex difference for food and water intake. All strains drank and fed more during the night even if they displayed no day–night difference in activity traits. Several strains showed absent or weak day–night variation in one or more activity traits and these included FVB and 129X1, males of 129S1, SWR, NZW, and SM, and females of SJL. In general females showed higher rearing and ambulatory activity with 6 and 9 strains, respectively, showing a sex difference. Fine motor movements, like grooming, showed less sex differences. RER underlied a strong day–night difference and no sex effect. Only FVB females and males of the RIIIS and SM strain had no day–night variation. Energy expenditure underlies a large day–night variation which was absent in SWR and in FVB females and RIIIS males. In general, female bodies had a tendency to higher energy expenditure values, which became a significant difference in C3H, MAMy, SM, DBA1, and BUB. Our data illustrate the diversity of these traits in male and female inbred mice and provide a resource in the selection of strains for future studies.

We measured indirect calorimetry and activity parameters, VO2 and VCO2 to extract respiratory exchange ratio (RER) and energy expenditure in both sexes of 30 inbred mouse strains of 6 genetic families at 9–13 weeks during one photophase and the subsequent scotophase. We observed a continuous distribution of all traits. While males had higher body weights than females, we observed no sex difference for food and water intake. All strains drank and fed more during the night even if they displayed no day–night difference in activity traits. Several strains showed absent or weak day–night variation in one or more activity traits and these included FVB and 129X1, males of 129S1, SWR, NZW, and SM, and females of SJL. In general females showed higher rearing and ambulatory activity with 6 and 9 strains, respectively, showing a sex difference. Fine motor movements, like grooming, showed less sex differences. RER underlied a strong day–night difference and no sex effect. Only FVB females and males of the RIIIS and SM strain had no day–night variation. Energy expenditure underlies a large day–night variation which was absent in SWR and in FVB females and RIIIS males. In general, female bodies had a tendency to higher energy expenditure values, which became a significant difference in C3H, MAMy, SM, DBA1, and BUB. Our data illustrate the diversity of these traits in male and female inbred mice and provide a resource in the selection of strains for future studies. [ABSTRACT FROM AUTHOR]

TFPR1 is a novel adjuvant for protein and peptide antigens, which has been demonstrated in BALB/c mice in our previous studies; however, its adjuvanticity in mice with different genetic backgrounds remains unknown, and its adjuvanticity needs to be improved to fit the requirements for various vaccines. In this study, we first compared the adjuvanticity of TFPR1 in two commonly used inbred mouse strains, BALB/c and C57BL/6 mice, in vitro and in vivo, and demonstrated that TFPR1 activated TLR2 to exert its immune activity in vivo. Next, to prove the feasibility of TFPR1 acting as a major component of combined adjuvants, we prepared a combined adjuvant, TF–Al, by formulating TFPR1 and alum at a certain ratio and compared its adjuvanticity with that of TFPR1 and alum alone using OVA and recombinant HBsAg as model antigens in both BALB/c and C57BL/6 mice. Results showed that TFPR1 acts as an effective vaccine adjuvant in both BALB/c mice and C57BL/6 mice, and further demonstrated the role of TLR2 in the adjuvanticity of TFPR1 in vivo. In addition, we obtained a novel combined adjuvant, TF–Al, based on TFPR1, which can augment antibody and cellular immune responses in mice with different genetic backgrounds, suggesting its promise for vaccine development in the future.

The interfrontal bone (IF) is a minor skeletal trait residing between the frontal bones. IF is considered a quasi-continuous trait. Genetic and environmental factors appear to play roles in its development. The mechanism(s) underlying IF bone development are poorly understood. We sought to survey inbred strains of mice for the prevalence of IF and to perform QTL mapping studies. Archived mouse skulls from a mouse phenome project (MPP) were available for this study. 27 inbred strains were investigated with 6–20 mice examined for each strain. Skulls were viewed dorsally and the IF measured using a zoom stereomicroscope equipped with a calibrated reticle. A two generation cross between C3H/HeJ and C57BL/6J mice was performed to generate a panel of 468 F2 mice. F2 mice were phenotyped for presence or absence of IF bone and among mice with the IF bone maximum widths and lengths were measured. F2 mice were genotyped for 573 SNP markers informative between the two strains and subjected to linkage map construction and interval QTL mapping. Results: Strain dependent differences in the prevalence of IF bones were observed. Overall, 77.8% or 21/27, of the inbred strains examined had IF bones. Six strains (C3H/HeJ, MOLF/EiJ, NZW/LacJ, SPRET/EiJ, SWR/J, and WSB/EiJ) lack IF bones. Among the strains with IF bones, the prevalence ranged from 100% for C57BL/6J, C57/LJ, CBA/J, and NZB/B1NJ and down to 5% for strains such as CAST/Ei. QTL mapping for IF bone length and widths identifies for each trait one strong QTL detected on chromosome 14 along with several other significant QTLs on chromosomes 3, 4, 7, and 11. Strain dependent differences in IF will facilitate investigation of genetic factors contributing to IF development. IF bone formation may be a model to understand intrasutural bone formation.

Chemocommunication plays an important role in establishing and maintaining the spatial ethological structure of the population. Previously, we demonstrated that the propensity to social dominance in male laboratory mice is mainly determined by an individual's genotype. However, it remains unclear whether genotypic peculiarities of mouse olfactory communication, the most important links of which are marking behavior and olfactory contacts, are associated with the ability to occupy a high social rank in the hierarchical structure of the community? The aim of the present work was to establish the effect of genotype on the intensity of marking behavior and olfactory contacts in male laboratory mice in a social competition model and to study the association of these types of social behavior with a hereditary predisposition to dominance. This study was conducted on adult males of inbred mice strains BALB/cLac, CBA/Lac, and PT differing in the propensity to dominate: BALB/cLac and PT males mainly dominated CBA/Lac males. The experimental groups were formed out of two males of different genotypes in three possible pairwise combinations. The intensity of urine marking the territory was estimated for each male in conditions of social isolation and after pair keeping during the period of stable dominant–subordinate relations. Olfactory contacts that were naso-nasal and naso-anogenital sniffing were used as an additional indicator of the propensity of mice to olfactory communication in conditions of social competition. Hereditary differences in the intensity of urine marking and in the frequency of olfactory contacts were established in male laboratory mice in the social competition model: dominant males of the CBA/Lac strain marked the territory and sniffed the opponent more frequently than dominants of the BALB/cLac and PT strains, while a decrease in urine marking and olfactory activity was observed in subordinate males of these strains. During social isolation, males of the CBA/Lac strain also marked the territory more frequently than males of the two other strains. Thus, the male mice of different inbred strains differ in the intensity of urine marking and olfactory behavior, which can be modified by external conditions, for example, social rank of an individual, and the intensity of urine marking and olfactory activity does not predict the social rank of an individual. [ABSTRACT FROM AUTHOR]

Respiratory syncytial virus (RSV) causes severe lower respiratory tract disease in infants, young children, and susceptible adults. The pathogenesis of RSV disease is not fully understood, although toll-like receptor 4 (TLR4)-related innate immune response is known to play a role. The present study was designed to determine TLR4-mediated disease phenotypes and lung transcriptomics and to elucidate transcriptional mechanisms underlying differential RSV susceptibility in inbred strains of mice. Dominant negative Tlr4 mutant (C3H/HeJ, HeJ, Tlr4Lps-d) and its wild-type (C3H/HeOuJ, OuJ, Tlr4Lps-n) mice and five genetically diverse, differentially responsive strains bearing the wild-type Tlr4Lps-n allele were infected with RSV. Bronchoalveolar lavage, histopathology, and genome-wide transcriptomics were used to characterize the pulmonary response to RSV. RSV-induced lung neutrophilia [1 day postinfection (pi)], epithelial proliferation (1 day pi), and lymphocytic infiltration (5 days pi) were significantly lower in HeJ compared with OuJ mice. Pulmonary RSV expression was also significantly suppressed in HeJ than in OuJ. Upregulation of immune/inflammatory (Cxcl3, Saa1) and heat shock protein (Hspa1a, Hsph1) genes was characteristic of OuJ mice, while cell cycle and cell death/survival genes were modulated in HeJ mice following RSV infection. Strain-specific transcriptomics suggested virus-responsive (Oasl1, Irg1, Mx1) and epidermal differentiation complex (Krt4, Lce3a) genes may contribute to TLR4-independent defense against RSV in resistant strains including C57BL/6J. The data indicate that TLR4 contributes to pulmonary RSV pathogenesis and activation of cellular immunity, the inflammasome complex, and vascular damage underlies it. Distinct transcriptomics in differentially responsive Tlr4- wild-type strains provide new insights into the mechanism of RSV disease and potential therapeutic targets. [ABSTRACT FROM AUTHOR]

The interfrontal bone (IF) is a minor skeletal trait residing between the frontal bones. IF is considered a quasi-continuous trait. Genetic and environmental factors appear to play roles in its development. The mechanism(s) underlying IF bone development are poorly understood. We sought to survey inbred strains of mice for the prevalence of IF and to perform QTL mapping studies. Archived mouse skulls from a mouse phenome project (MPP) were available for this study. 27 inbred strains were investigated with 6–20 mice examined for each strain. Skulls were viewed dorsally and the IF measured using a zoom stereomicroscope equipped with a calibrated reticle. A two generation cross between C3H/HeJ and C57BL/6J mice was performed to generate a panel of 468 F2 mice. F2 mice were phenotyped for presence or absence of IF bone and among mice with the IF bone maximum widths and lengths were measured. F2 mice were genotyped for 573 SNP markers informative between the two strains and subjected to linkage map construction and interval QTL mapping. Results: Strain dependent differences in the prevalence of IF bones were observed. Overall, 77.8% or 21/27, of the inbred strains examined had IF bones. Six strains (C3H/HeJ, MOLF/EiJ, NZW/LacJ, SPRET/EiJ, SWR/J, and WSB/EiJ) lack IF bones. Among the strains with IF bones, the prevalence ranged from 100% for C57BL/6J, C57/LJ, CBA/J, and NZB/B1NJ and down to 5% for strains such as CAST/Ei. QTL mapping for IF bone length and widths identifies for each trait one strong QTL detected on chromosome 14 along with several other significant QTLs on chromosomes 3, 4, 7, and 11. Strain dependent differences in IF will facilitate investigation of genetic factors contributing to IF development. IF bone formation may be a model to understand intrasutural bone formation. [ABSTRACT FROM AUTHOR]

Inbred mouse strains are a cornerstone of translational research but paradoxically many strains carry mild inborn errors of metabolism. For example, α-aminoadipic acidemia and branched-chain ketoacid dehydrogenase deficiency are known in C57BL/6J mice. Using RNA sequencing, we now reveal the causal variants in Dhtkd1 and Bckdhb, and the molecular mechanism underlying these metabolic defects. C57BL/6J mice have decreased Dhtkd1 mRNA expression due to a solitary long terminal repeat (LTR) in intron 4 of Dhtkd1. This LTR harbors an alternate splice donor site leading to a partial splicing defect and as a consequence decreased total and functional Dhtkd1 mRNA, decreased DHTKD1 protein and α-aminoadipic acidemia. Similarly, C57BL/6J mice have decreased Bckdhb mRNA expression due to an LTR retrotransposon in intron 1 of Bckdhb. This transposable element encodes an alternative exon 1 causing aberrant splicing, decreased total and functional Bckdhb mRNA and decreased BCKDHB protein. Using a targeted metabolomics screen, we also reveal elevated plasma C5-carnitine in 129 substrains. This biochemical phenotype resembles isovaleric acidemia and is caused by an exonic splice mutation in Ivd leading to partial skipping of exon 10 and IVD protein deficiency. In summary, this study identifies three causal variants underlying mild inborn errors of metabolism in commonly used inbred mouse strains. [ABSTRACT FROM AUTHOR]

GABA type-A (GABA-A) receptors containing the α2 subunit (GABRA2) are expressed in most brain regions and are critical in modulating inhibitory synaptic function. Genetic variation at the GABRA2 locus has been implicated in epilepsy, affective and psychiatric disorders, alcoholism and drug abuse. Gabra2 expression varies as a function of genotype and is modulated by sequence variants in several brain structures and populations, including F2 crosses originating from C57BL/6J (B6J) and the BXD recombinant inbred family derived from B6J and DBA/2J. Here we demonstrate a global reduction of GABRA2 brain protein and mRNA in the B6J strain relative to other inbred strains, and identify and validate the causal mutation in B6J. The mutation is a single base pair deletion located in an intron adjacent to a splice acceptor site that only occurs in the B6J reference genome. The deletion became fixed in B6J between 1976 and 1991 and is now pervasive in many engineered lines, BXD strains generated after 1991, the Collaborative Cross, and the majority of consomic lines. Repair of the deletion using CRISPR- Cas9 -mediated gene editing on a B6J genetic background completely restored brain levels of GABRA2 protein and mRNA. Comparison of transcript expression in hippocampus, cortex, and striatum between B6J and repaired genotypes revealed alterations in GABA-A receptor subunit expression, especially in striatum. These results suggest that naturally occurring variation in GABRA2 levels between B6J and other substrains or inbred strains may also explain strain differences in anxiety-like or alcohol and drug response traits related to striatal function. Characterization of the B6J private mutation in the Gabra2 gene is of critical importance to molecular genetic studies in neurobiological research because this strain is widely used to generate genetically engineered mice and murine genetic populations, and is the most widely utilized strain for evaluation of anxiety-like, depression-like, pain, epilepsy, and drug response traits that may be partly modulated by GABRA2 function. [ABSTRACT FROM AUTHOR]

Wild-derived mouse inbred strains are becoming increasingly popular for complex traits analysis, evolutionary studies, and systems genetics. Here, we report the whole-genome sequencing of two wild-derived mouse inbred strains, LEWES/EiJ and ZALENDE/EiJ, of Mus musculus domesticus origin. These two inbred strains were selected based on their geographic origin, karyotype, and use in ongoing research. We generated 14× and 18× coverage sequence, respectively, and discovered over 1.1 million novel variants, most of which are private to one of these strains. This report expands the number of wild-derived inbred genomes in the Mus genus from six to eight. The sequence variation can be accessed via an online query tool; variant calls (VCF format) and alignments (BAM format) are available for download from a dedicated ftp site. Finally, the sequencing data have also been stored in a lossless, compressed, and indexed format using the multi-string Burrows-Wheeler transform. All data can be used without restriction.

Highlights • Neuropathic pain and DRG/spinal immune responses were compared in 4 mouse strains. • The resistant strain showed anti-inflammatory DRG macrophage and low microglial responses. • Microglia in the resistant strain showed poor responsiveness against CX3CL1. • BM chimeric mice revealed strain-specific temporal role of macrophage and microglia. • Strain-specific immune response is involved in the susceptibility to neuropathic pain. Abstract The present study was designed to investigate the correlation between the spatial and temporal aspects of immune responses and genetic heterogeneity in the progression of peripheral neuropathic pain. To address this issue, we first screened four inbred mouse strains (C57BL/6J, C3H/He, DBA/2, and A/J mice) to identify high- and low-responder strains to mechanical hypersensitivity induced by partial sciatic nerve ligation (pSNL). Among these strains, the C57BL/6J strain showed the highest vulnerability to pSNL-induced mechanical hypersensitivity, whereas the C3H/HeSlc strain was most resistant. C3H/HeSlc mice exhibited a significant increase in CD206-immunoreactivity (anti-inflammatory macrophages) in the dorsal root ganglia (DRG) at 3 and 7 days, and lower Iba1-immunoreactivity (microglia) in the spinal cord from 3 to 14 days after pSNL than C57BL/6J mice. These phenomena might be associated with a decrease in the production of inflammatory factors (interleukin-1β, interleukin-6, and CX3CL1) in the DRG and the poor responsiveness of spinal microglia (i.e. microglial production of IL1β, CCL2, and TNFα) against CX3CL1 in C3H/HeSlc mice. Behavioral experiments using bone marrow (BM) chimeric mice derived by crossing C3H/HeSlc and C57BL/6J strains showed that the strength of mechanical hypersensitivity 3 days following pSNL was inversely correlated with the increase in the ratio of anti-inflammatory/pro-inflammatory DRG macrophages, which was based on the BM-derived hematopoietic cells from donor mice. By contrast, the intensity of Iba1-immunoreactivity (microglia) in the spinal cord was dependent on the phenotypes of recipient mice, but not affected by the phenotypes of BM-derived donor hematopoietic cells. These findings suggest that the strain-specific aspects of DRG macrophages and spinal microglia might be related to the early and late phases of pSNL-induced mechanical hypersensitivity, respectively. This study presents a greater understanding of the differences in neuropathic pain among genetically heterogeneous inbred mouse strains, and provides further insights into the spatial and temporal roles of the immune system in the pathogenesis of neuropathic pain. [ABSTRACT FROM AUTHOR]

Physical activity has multiple beneficial effects in the physiology and pathology of the organism. In particular, we and other groups have shown that running counteracts cancer cachexia in both humans and rodents. The latter are prone to exercise in wheel-equipped cages even at advanced stages of cachexia. However, when we wanted to replicate the experimental model routinely used at the University of Rome in a different laboratory (i.e. at Paris 6 University), we had to struggle with puzzling results due to unpredicted mouse behavior. Here we report the experience and offer the explanation underlying these apparently irreproducible results. The original data are currently used for teaching purposes in undergraduate student classes of biological sciences.

Background and aims In a previous work, a female-specific atherosclerosis risk locus on chromosome (Chr) 3 was identified in an intercross of atherosclerosis-resistant FVB and atherosclerosis-susceptible C57BL/6 (B6) mice on the LDL-receptor deficient ( Ldlr −/− ) background. It was the aim of the current study to identify causative genes at this locus. Methods We established a congenic mouse model, where FVB.Chr3 B6/B6 mice carried an 80 Mb interval of distal Chr3 on an otherwise FVB. Ldlr −/− background, to validate the Chr3 locus. Candidate genes were identified using genome-wide expression analyses. Differentially expressed genes were validated using quantitative PCRs in F0 and F2 mice and their functions were investigated in pathophysiologically relevant cells. Results Fine-mapping of the Chr3 locus revealed two overlapping, yet independent subloci for female atherosclerosis susceptibility: when transmitted by grandfathers to granddaughters, the B6 risk allele increased atherosclerosis and downregulated the expression of the secreted phospholipase Pla2g12a (2.6 and 2.2 fold, respectively); when inherited by grandmothers, the B6 risk allele induced vascular cell adhesion molecule 1 ( Vcam1 ). Down-regulation of Pla2g12a and up-regulation of Vcam1 were validated in female FVB.Chr3 B6/B6 congenic mice, which developed 2.5 greater atherosclerotic lesions compared to littermate controls ( p =0.039). Pla2g12a was highly expressed in aortic endothelial cells in vivo , and knocking-down Pla2g12a expression by RNAi in cultured vascular endothelial cells or macrophages increased their adhesion to ECs in vitro . Conclusions Our data establish Pla2g12a as an atheroprotective candidate gene in mice, where high expression levels in ECs and macrophages may limit the recruitment and accumulation of these cells in nascent atherosclerotic lesions. [ABSTRACT FROM AUTHOR]

Mice and humans branched from a common ancestor approximately 80 million years ago. Despite this, mice are routinely utilized as animal models of human disease and in drug development because they are inexpensive, easy to handle, and relatively straightforward to genetically manipulate. While this has led to breakthroughs in the understanding of genotype–phenotype relationships and in the identification of therapeutic targets, translation of beneficial responses to therapeutics from mice to humans has not always been successful. In a large part, these differences may be attributed to variations in the alignment of protein expression and signaling in the immune systems between mice and humans. Well-established inbred strains of “The Laboratory Mouse” vary in their immune response patterns as a result of genetic mutations and polymorphisms arising from intentional selection for research relevant traits, and even closely related substrains vary in their immune response patterns as a result of genetic mutations and polymorphisms arising from genetic drift. This article reviews some of the differences between the mouse and human immune system and between inbred mouse strains and shares examples of how these differences can impact the usefulness of mouse models of disease. [ABSTRACT FROM AUTHOR]

Women are at an increased risk for developing affective disorders during times of hormonal flux, including menopause when the ovaries cease production of estrogen. However, while all women undergo menopause, not all develop an affective disorder. Increased vulnerability can result from genetic predisposition, environmental factors and gene by environment interactions. In order to investigate interactions between genetic background and estrogen depletion, we performed bilateral ovariectomy, a surgical procedure that results in estrogen depletion and is thought to model the post-menopausal state, in a genetically defined panel of 37 inbred mouse strains. Seventeen days post-ovariectomy, we assessed behavior in two standard rodent assays of anxiety- and depressive-like behavior, the open field and forced swim tests. We detected a significant interaction between ovariectomy and genetic background on anxiety-like behavior in the open field. No strain specific effects of ovariectomy were observed in the forced swim assay. However, we did observe significant strain effects for all behaviors in both the open field and forced swim tests. This study is the largest to date to look at the effects of ovariectomy on behavior and provides evidence that ovariectomy interacts with genetic background to alter anxiety-like behavior in an animal model of menopause. [ABSTRACT FROM AUTHOR]

Understanding the genetic influence on vascular reactivity is important for identifying genes underlying impaired vascular function. The purpose of this study was to characterize the genetic contribution to intrinsic vascular function and to identify loci associated with phenotypic variation in vascular reactivity in mice. Concentration response curves to phenylephrine (PE), potassium chloride (KCl), acetylcholine (ACh), and sodium nitroprusside (SNP) were generated in aortic rings from male mice (12 wk old) from 27 inbred mouse strains. Significant strain-dependent differences were found for both maximal responses and sensitivity for each agent, except for SNP Max (%). Strain differences for maximal responses to ACh, PE, and KCl varied by two- to fivefold. On the basis of these large strain differences, we performed genome-wide association mapping (GWAS) to identify loci associated with variation in responses to these agents. GWAS for responses to ACh identified four significant and 19 suggestive loci. Several suggestive loci for responses to SNP, PE, and KCl (including one significant locus for KCl EC50) were also identified. These results demonstrate that intrinsic endothelial function, and more generally vascular function, is genetically determined and associated with multiple genomic loci. Furthermore, these results are supported by the finding that several genes residing in significant and suggestive loci for responses to ACh were previously identified in rat and/or human quantitative trait loci/GWAS for cardiovascular disease. This study represents the first step toward the unbiased comprehensive discovery of genetic determinants that regulate intrinsic vascular function, particularly endothelial function. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N 2 O)-induced antinociception in mice is dependent on the neuromodulator nitric oxide (NO). In contrast to C57BL/6J (B6) mice, DBA/2J (D2) mice fail to respond to N 2 O with a robust antinociceptive response or with an increase in brain nitric oxide synthase (NOS) enzyme activity, suggesting that failure of D2 mice to respond to N 2 O might result from a deficit of NO function. Therefore, it was of interest to determine whether increasing the availability of NO might increase sensitivity of D2 mice to N 2 O. Male D2 mice were pretreated with sub-antinociceptive intracerebroventricular doses of the NO donor 3-morpholinosydnoimine or the NO precursor l -arginine then assessed for responsiveness to N 2 O-induced antinociception using the acetic acid abdominal constriction test. Both pretreatments increased the antinociceptive responsiveness of D2 mice to N 2 O. These results indicate that the NOS enzyme in D2 mice is functional and that the deficit in NO function that obstructs sensitivity to N 2 O-induced antinociception may lie in availability or utilization of l -arginine. [ABSTRACT FROM AUTHOR]

Central nervous system disorders such as autism as well as the range of neurodegenerative diseases such as Huntington’s disease are commonly investigated using genetically altered mouse models. The current system for characterizing these mice usually involves removing the animals from their home-cage environment and placing them into novel environments where they undergo a battery of tests measuring a range of behavioral and physical phenotypes. These tests are often only conducted for short periods of times in social isolation. However, human manifestations of such disorders are often characterized by multiple phenotypes, presented over long periods of time and leading to significant social impacts. Here, we have developed a system which will allow the automated monitoring of individual mice housed socially in the cage they are reared and housed in, within established social groups and over long periods of time. We demonstrate that the system accurately reports individual locomotor behavior within the group and that the measurements taken can provide unique insights into the effects of genetic background on individual and group behavior not previously recognized. [ABSTRACT FROM AUTHOR]

Mammalian physiological processes can distinguish between dietary cholesterol and non-cholesterol, retaining very little of the non-cholesterol in their bodies. We have recently identified two genes, ABCG5 and ABCG8, encoding sterolin-1 and -2 respectively, mutations of which cause the human disease sitosterolemia. We report here the mouse cDNAs and genomic organization of Abcg5 and Abcg8. Both genes are arranged in an unusual head-to-head configuration, and only 140 bases separate their two respective start-transcription sites. A single TATA motif was identified, with no canonical CCAT box present between the two genes. The genes are located on mouse chromosome 17 and this complex spans no more than 40 kb. Expression of both genes is confined to the liver and intestine. For both genes, two different sizes of transcripts were identified which differ in the lengths of their 3′ UTRs. Additionally, alternatively spliced forms for Abcg8 were identified, resulting from a CAG repeat at the intron 1 splice-acceptor site, causing a deletion of a glutamine. We screened 20 different mouse strains for polymorphic variants. Although a large number of polymorphic variants were identified, strains reported to show significant differences in cholesterol absorption rates did not show significant genomic variations in Abcg5 or Abcg8.—Lu, K., M-H. Lee, H. Yu, Y. Zhou, S. A. Sandell, G. Salen, and S. B. Patel. Molecular cloning, genomic organization, genetic variations, and characterization of murine sterolin genes Abcg5 and Abcg8. J. Lipid Res. 2002. 43: 565–578.

Maladaptive fear, such as fear that is persistent or easily generalized to a nonthreatening stimuli, is associated with anxiety-related disorders in humans. In the laboratory, maladaptive fear can be modeled in rodents using Pavlovian fear conditioning. Recently, an inbred mouse strain known as 129S1/SvImJ, or 129S1 have been reported as exhibiting impairments in fear extinction and enhanced fear generalization. With a long-term goal of identifying segregating genetic markers of maladaptive fear, we used Pavlovian fear conditioning to characterize a closely related substrain designated as 129S6/SvEvTac, or 129S6. Here we report that, like 129S1 animals, 129S6 mice exhibit appropriate levels of fear upon conditioning, but are unable to extinguish fear memories once they are consolidated. Importantly, the maladaptive fear phenotype in this inbred stain can be segregated by sub-strain when probed using conditioning protocols designed to assess generalized fear. We find that unlike the 129S1 substrain, mice from the 129S6 sub-strain do not generalize conditioned fear to previously novel contexts and can learn to discriminate between two similar contexts when trained using a discrimination protocol. These results suggest that at least two forms of maladaptive fear (deficits in fear extinction and fear generalization) can be can be functionally segregated, further suggesting that the underlying neurobiology is heritable. Given the observation that two closely related sub-strains can exhibit different constellations of maladaptive fear suggests that these findings could be exploited to facilitate the identification of candidate genes for anxiety-related disorders.

An elevated plasma apolipoprotein B (apoB) level is a strong predictor of atherosclerosis and coronary heart disease. Epidemiologic and family linkage studies have suggested a genetic basis for the wide variations of plasma apoB levels in the general population. Using a human apoB transgenic (HuBTg) mouse model, we have previously shown that hepatic apoB-100 secretion is a major determinant of the high and low plasma human apoB levels in HuBTg mice of the C57BL/6 (B6) and 129/Sv (129) strains, respectively. In the present article, we present the identification of two novel quantitative trait loci (QTL) as major regulators of plasma human apoB levels in the F2 and N2 (backcrossed) offspring (n = 572) derived from crosses between the B6 and 129 mouse strains. These loci were designated ApoB regulator genes (Abrg), because the gene products are likely to be involved in the regulation of plasma apoB levels either directly or indirectly. The first locus, designated Abrg1, was mapped to chromosome 6 in 8-week-old male and female mice with a combined logarithm of odds ratio (LOD) score of 14 at the D6Mit55 marker (~45.9 cM). Abrg1 contributed approximately 35% of the genetic variance. The second locus, designated Abrg2, was mapped to chromosome 4 with an LOD score of 8.6 in 8-week-old male mice but an LOD score of only 2.0 in 8-week-old female mice at the D4Mit27 marker (~35 cM). Abrg2 contributed approximately 26% of the genetic variance. Epistasis between Abrg1 and Abrg2 was detected and accounted for approximately 12% of the genetic variance. The combination of these two QTL has major effects (>70%) on the regulation of plasma human apoB levels in the tested population.In summary, we have identified two novel loci that have a major role in the regulation of plasma apoB levels and are likely to regulate the secretory pathway of apoB. The human orthologs for the Abrg loci are strong candidates for human disorders characterized by altered plasma apoB levels, such as FCHL and familial hypobetalipoproteinemia.

The study objective was to investigate the effects of fluoride on intact parathyroid hormone (iPTH) secretion. Thyro-parathyroid complexes (TPC) from C3H (n = 18) and B6 (n = 18) mice were cultured in Ca2+-optimized medium. TPC were treated with 0, 250, or 500 µM NaF for 24 h and secreted iPTH assayed by ELISA. C3H (n = 78) and B6 (n = 78) mice were gavaged once with distilled or fluoride (0.001 mg [F-]/g of body weight) water. At serial time points (0.5-96 h) serum iPTH, fluoride, total calcium, phosphorus, and magnesium levels were determined. Expression of genes involved in mineral regulation via the bone-parathyroid-kidney (BPK) axis, such as parathyroid hormone (Pth), calcium-sensing receptor (Casr), vitamin D receptor (Vdr), parathyroid hormone-like hormone (Pthlh), fibroblast growth factor 23 (Fgf23), α-Klotho (αKlotho), fibroblast growth factor receptor 1c (Fgf1rc), tumor necrosis factor 11 (Tnfs11), parathyroid hormone receptor 1 (Pth1r), solute carrier family 34 member 1 (Slc34a1), solute carrier 9 member 3 regulator 1 (Slc9a3r1), chloride channel 5 (Clcn5), and PDZ domain-containing 1 (Pdzk1), was determined in TPC, humeri, and kidneys at 24 h. An in vitro decrease in iPTH was seen in C3H and B6 TPC at 500 µM (p < 0.001). In vivo levels of serum fluoride peaked at 0.5 h in both C3H (p = 0.002) and B6 (p = 0.01). In C3H, iPTH decreased at 24 h (p < 0.0001), returning to baseline at 48 h. In B6, iPTH increased at 12 h (p < 0.001), returning to baseline at 24 h. Serum total calcium, phosphorus, and magnesium levels did not change significantly. Pth, Casr,αKlotho,Fgf1rc,Vdr, and Pthlh were significantly upregulated in C3H TPC compared to B6. In conclusion, the effects of fluoride on TPC in vitro were equivalent between the 2 mouse strains. However, fluoride demonstrated an early strain-dependent effect on iPTH secretion in vivo. Both strains demonstrated differences in the expression of genes involved in the BPK axis, suggesting a possible role in the physiologic handling of fluoride. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Purpose: Radiation exposure can result in DNA damage but whether the extent of DNA damage correlates with the radiation-induced tissue injury in the lung is not known. We aimed to determine whether numbers of γH2AX foci, representing histone H2AX phosphorylation a marker of DNA damage, measured within days of radiation exposure, correlated with known later lung injury responses in eight inbred mouse strains. Materials and methods: Mice received 18 Gy pulmonary irradiation and numbers of γH2AX positive nuclei in the lung were immunohistochemically determined. Results: Numbers of γH2AX foci, assessed up to seven days post irradiation did not correlate with pulmonary fibrosis. γH2AX counts from mice in respiratory distress, however, significantly correlated with fibrosis and lungs from mice treated with a fibrosis-reducing antagonist had fewer γH2AX foci. Conclusions: Acute response measures of pulmonary DNA damage did not predict for pathology, but levels of this marker in distressed mice were correlative of fibrosis. [ABSTRACT FROM AUTHOR]

Background: Social deficit is one of the core symptoms of neuropsychiatric diseases, in which immune genes play an important role. Although a few immune genes have been shown to regulate social and emotional behaviors, how immune gene network(s) may jointly regulate sociability has not been investigated so far. Methods: To decipher the potential immune-mediated mechanisms underlying social behavior, we first studied the brain microarray data of eight inbred mouse strains with known variations in social behavior and retrieved the differentially expressed immune genes. We then made a protein-protein interaction analysis of them to find the major networks and explored the potential association of these genes with the behavior and brain morphology in the mouse phenome database. To validate the expression and function of the candidate immune genes, we selected the C57BL/6 J and DBA/2 J strains among the eight inbred strains, compared their social behaviors in resident-intruder and 3-chambered social tests and the mRNA levels of these genes, and analyzed the correlations of these genes with the social behaviors. Results: A group of immune genes were differentially expressed in the brains of these mouse strains. The representative C57BL/6 J and DBA/2 J strains displayed significant differences in social behaviors, DBA/2 J mice being less active in social dominance and social interaction than C57BL/6 J mice. The mRNA levels of H2-d1 in the prefrontal cortex, hippocampus, and hypothalamus and C1qb in the hippocampus of the DBA/2 J strain were significantly down-regulated as compared to those in the C57BL/6 J strain. In contrast, Polr3b in the hippocampus and Tnfsf13b in the prefrontal cortex of the DBA/2 J strain were up-regulated. Furthermore, C1qb, Cx3cl1, H2-d1, H2-k1, Polr3b, and Tnfsf13b were predicted to be associated with various behavioral and brain morphological features across the eight inbred strains. Importantly, the C1qb mRNA level was confirmed to be significantly correlated with the sociability in DBA/2 J but not in C57BL/6 J mice. Conclusions: Our study provided evidence on the association of immune gene network(s) with the brain development and behavior in animals and revealed neurobiological functions of novel brain immune genes that may contribute to social deficiency in animal models of neuropsychiatric disorders. [ABSTRACT FROM AUTHOR]

Mounting evidence suggests the association of immune genes with complex neuropsychiatric diseases, such as schizophrenia. However, immune gene expression in the brain and their involvement in schizophrenia-related behavior in animal models have not been well studied so far. We analyzed the social (resident–intruder) and sensorimotor gating (pre-pulse inhibition (PPI) of acoustic startle) behaviors, and expression profiles of several brain immune genes in adult C57BL/6N and DBA/2J female mice. Compared to C57BL/6N mice, DBA/2J mice exhibited less social interaction in the resident–intruder test and reduced pre-pulse inhibition. The mRNA levels of Il1b and Il6 genes were significantly higher in the cortex and hypothalamus, while the mRNA level of C1qb was lower in the cortex, hippocampus and hypothalamus of DBA/2J mice compared to C57BL/6N mice. Furthermore, Tnfsf13b was up-regulated in the cortex and hippocampus, and so did Cd47 in the hippocampus, while Cx3cl1 was down-regulated in the cortex of DBA/2J mice. Our study demonstrates the differential expression of several immune genes in C57BL/6N and DBA/2J strains and more importantly provides clues on their potential importance in regulating schizophrenia-related endophenotypes in animal models. [ABSTRACT FROM AUTHOR]

Plasma apolipoprotein B (apoB) levels vary widely in the general population and elevated plasma levels of apoB are associated with higher risk for atherosclerotic coronary heart disease. Determination of genetic factors regulating population variance of plasma apoB levels is complicated by the genetic heterogeneity of human populations. Using a congenic human apoB transgenic mouse strain in the C57BL/6 background (B6 HuBTg), we assessed genetic effects on the variance of plasma apoB, and on hepatic apoB-100 secretion rates. Six inbred mouse strains were crossed with the B6 HuBTg strain. Mean plasma apoB levels in the parental B6 HuBTg strain were 95 ± 14 mg/dl. F1 human apoB transgenic offspring displayed plasma human apoB levels ranging from 60 to 105 mg/dl. In three F1 strains, the BALB/B6, C3H/B6 and 129/B6 strains, markedly lower plasma apoB levels (61 ± 11, 64 ± 5, and 67 ± 8 mg/dl) were due to lower apoB-100 secretion rates. Human apoB mRNA levels in these three F1 strains were similar to those of the parental B6 strain suggesting that the mechanism for varying apoB secretion rates is most likely not transcriptional. In summary, we have identified three inbred mouse strains possessing polymorphic alleles which, when crossed with the B6 strain, lower plasma apoB levels and apoB-100 secretion in their F1 offspring. These mouse strains provide a powerful tool for genetic analysis of factors regulating apoB-100 secretion and hence plasma apoB levels.—Voyiaziakis, E., C. Ko, S. M. O'Rourke, and L-S. Huang. Genetic control of hepatic apoB-100 secretion in human apoB transgenic mouse strains. J. Lipid Res. 1999. 40: 2004–2012.

The genetic basis of the phenotypic variability observed in patients can be studied in mice by generating disease models through genetic or chemical interventions in many genetic backgrounds where the clinical phenotypes can be assessed and used for genome-wide association studies (GWAS). This is particularly relevant for rare disorders, where patients sharing identical mutations can present with a wide variety of symptoms, but there are not enough number of patients to ensure statistical power of GWAS. Inbred strains are homozygous for each loci, and their single nucleotide polymorphisms catalogs are known and freely available, facilitating the bioinformatics and reducing the costs of the study, since it is not required to genotype every mouse. This kind of approach can be applied to pharmacogenomics studies as well. [ABSTRACT FROM AUTHOR]

Three stocks of Mycobacterium tuberculosis H37Rv were cultured in vitro under prolonged hypoxic or acidified conditions until partial or complete loss of the capacity to form colonies on agar medium was achieved. Such dormant “non-culturable” mycobacteria were assessed for the growth resuscitation after intra-tracheal injection into mice of the two inbred strains with different genetic susceptibility to M. tuberculosis -triggered disease: hyper-susceptible I/St and relatively resistant B6. The results indicate that bacteria which are able to resuscitate spontaneously in liquid medium in vitro started to multiply in organs of infected mice, and that the outcome of such infection strongly depended upon the level of genetic TB susceptibility. However, dormant bacteria required inducers for resuscitation in vitro lost the capacity to multiply even in genetically susceptible mice. The established model of dormancy/reactivation is suitable for the studying host–pathogen interactions and testing vaccine and drug candidates specifically targeting latent TB. [ABSTRACT FROM AUTHOR]

Maladaptive fear, such as fear that is persistent or easily generalized to a nonthreatening stimuli, is associated with anxiety-related disorders in humans. In the laboratory, maladaptive fear can be modeled in rodents using Pavlovian fear conditioning. Recently, an inbred mouse strain known as 129S1/SvImJ, or 129S1 has been reported as exhibiting impairments in fear extinction and enhanced fear generalization. With a long-term goal of identifying segregating genetic markers of maladaptive fear, we used Pavlovian fear conditioning to characterize a closely related substrain designated as 129S6/SvEvTac, or 129S6. Here we report that, like 129S1 animals, 129S6 mice exhibit appropriate levels of fear upon conditioning, but are unable to extinguish fear memories once they are consolidated. Importantly, the maladaptive fear phenotype in this inbred stain can be segregated by sub-strain when probed using conditioning protocols designed to assess generalized fear. We find that unlike the 129S1 substrain, mice from the 129S6 sub-strain do not generalize conditioned fear to previously novel contexts and can learn to discriminate between two similar contexts when trained using a discrimination protocol. These results suggest that at least two forms of maladaptive fear (deficits in fear extinction and fear generalization) can be can be functionally segregated, further suggesting that the underlying neurobiology is heritable. Given the observation that two closely related sub-strains can exhibit different constellations of maladaptive fear suggests that these findings could be exploited to facilitate the identification of candidate genes for anxiety-related disorders. [ABSTRACT FROM AUTHOR]

Abstract: Animal models are widely used to gain insight into the role of genetics on bone structure and function. One of the main strategies to map the genes regulating specific traits is called quantitative trait loci (QTL) analysis, which generally requires a very large number of animals (often more than 1000) to reach statistical significance. QTL analysis for mechanical traits has been mainly based on experimental mechanical testing, which, in view of the large number of animals, is time consuming. Hence, the goal of the present work was to introduce an automated method for large-scale high-throughput quantification of the mechanical properties of murine femora. Specifically, our aims were, first, to develop and validate an automated method to quantify murine femoral bone stiffness. Second, to test its high-throughput capabilities on murine femora from a large genetic study, more specifically, femora from two growth hormone (GH) deficient inbred strains of mice (B6-lit/lit and C3.B6-lit/lit) and their first (F1) and second (F2) filial offsprings. Automated routines were developed to convert micro-computed tomography (micro-CT) images of femora into micro-finite element (micro-FE) models. The method was experimentally validated on femora from C57BL/6J and C3H/HeJ mice: for both inbred strains the micro-FE models closely matched the experimentally measured bone stiffness when using a single tissue modulus of 13.06GPa. The mechanical analysis of the entire dataset (n=1990) took approximately 44 CPU hours on a supercomputer. In conclusion, our approach, in combination with QTL analysis could help to locate genes directly involved in controlling bone mechanical competence. [Copyright &y& Elsevier]

Summary: Mice as a species are susceptible to tuberculosis infection while mouse inbred strains present wide spectrum of susceptibility/resistance to this infection. However, non-tuberculosis Mycobacterial infections usually cannot be modeled in mice of common inbred strains. Introduction of specific properties, such as gene mutations, recombinants, targeted gene knockouts significantly extended the use of mice to mimic human Mycobacterial infections, including non-tuberculosis ones. This review describes the available mouse models of tuberculosis and non-tuberculosis infections and drug therapy in these models. Mouse models of non-tuberculosis infections are significantly less developed than tuberculosis models, hampering the development of therapies. [ABSTRACT FROM AUTHOR]

Recent advances of induced pluripotent stem cells (iPSCs) has demonstrated that full development potential is closely related with the expression state of noncoding RNAs (ncRNAs) of the Dlk1- Dio3 imprinted gene cluster. However, few of them, especially the long noncoding RNAs (lncRNAs), have been characterized in detail. AK044800 is a transcript from the Dlk1- Dio3 imprinted region with little known information. This study reports original data on the expression pattern of AK044800 during embryogenesis. Expression analysis showed that AK044800 was specifically expressed in the brain at mid-gestation, E9.5 and E11.5. And at E15.5, its expression was mainly concentrated in the forebrain. In the late-gestation stage (E18.5), AK044800 expression was weaker in the brain and began to emerge in some other tissues during this period. Notably, the expression of AK044800 was biallelic in the brain, unlike other noncoding transcripts from this imprinted region. In addition, its expression was dependent on inbred mouse strains. This may be the first lncRNA that has been identified with a different expression between inbred mouse strains. This study may provide useful clues for further investigations of expression regulation and functions of lncRNAs of the Dlk1- Dio3 imprinted region. [ABSTRACT FROM AUTHOR]

Abstract: Intracerebroventricular administration of selective agonist of serotonin 5-HT7 receptor LP44 (4-[2-(methylthio)phenyl]-N-(1,2,3,4-tetrahydro-1-naphthalenyl)-1-pyperasinehexanamide hydrochloride; 10.3, 20.5 or 41.0 nmol) produced considerable hypothermic response in CBA/Lac mice. LP44-induced (20.5 nmol) hypothermia was significantly attenuated by the selective 5-HT7 receptor antagonist SB 269970 (16.1 fmol, i.c.v.) pretreatment. At the same time, intraperitoneal administration of LP44 in a wide range of doses 1.0, 2.0 or 10.0 mg/kg (2.0, 4.0, 20.0 μmol/kg) did not cause considerable hypothermic response. These findings indicate the implication of central, rather than peripheral 5-HT7 receptors in the regulation of hypothermia. The comparison of LP44-induced (20.5 nmol) hypothermic reaction in eight inbred mouse strains (DBA/2J, CBA/Lac, C57BL/6, BALB/c, ICR, AKR/J, C3H and Asn) was performed and a significant effect of genotype was found. In the same eight mouse strains, functional activity of 5-HT1A and 5-HT3 receptors was studied. The comparison of hypothermic responses produced by 5-HT7 receptor agonist LP44 (20.5 nmol, i.c.v.) and 5-HT1A receptor agonist 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg), 5-HT3 receptor agonist m-CPBG (40.0 nmol, i.c.v.) did not reveal considerable interstrain correlations between 5-HT7 and 5-HT1A or 5-HT3 receptor-induced hypothermia. The selective 5-HT7 receptor antagonist SB 269970 (16.1 fmol, i.c.v.) failed to attenuate the hypothermic effect of 8-OH-DPAT 1.0 mg/kg, i.p. (3.0 μmol/kg) and m-CPBG (40.0 nmol, i.c.v.) indicating that the brain 5-HT7 receptor is not involved in the hypothermic effects of 8-OH-DPAT or m-CPBG. The obtained results suggest that the central 5-HT7 receptor plays an essential role in the mediation of thermoregulation independent of 5-HT1A and 5-HT3 receptors. [Copyright &y& Elsevier]

Early life stress is a prominent risk factor for the development of adult psychopathology. Numerous studies have shown that early life stress leads to persistent changes in behavioral and endocrine responses to stress. However, despite recent findings of gene expression changes and structural abnormalities in neurons of the forebrain neocortex, little is known about specific cognitive deficits that can result from early life stress. Here we examined five cognitive functions in two inbred strains of mice, the stress-resilient strain C57B1/6 and the stress-susceptible strain Balb/c, which were exposed to an infant maternal separation paradigm and raised to adulthood. Between postnatal ages P60 to P90, mice underwent a series of tests examining five cognitive functions: Recognition memory, spatial working memory, associative learning, shifts of attentional sets, and reversal learning. None of these functions were impaired in IMS C57B1/6 mice. In contrast, IMS Balb/c mice exhibited deficits in spatial working memory and extradimensional shifts of attention, that is, functions governed primarily by the medial prefrontal cortex. Thus, like recently discovered changes in frontocortical gene expression, the emergence of specific cognitive deficits associated with the medial prefrontal cortex is also strain-specific. These findings illustrate that early life stress can indeed affect specific cognitive functions in adulthood, and they support the hypothesis that the genetic background and environmental factors are critical determinants in the development of adult cognitive deficits in subjects with a history of early life stress. [ABSTRACT FROM AUTHOR]