133 research outputs found
Analysis of factors decreasing testis weight in MRL mice
No full textMRL/MpJ (MRL) mouse testes have several unique characteristics, including the appearance of oocytes, the occurrence of metaphase-specific apoptosis of meiotic spermatocytes, and the presence of heat-shock-resistant spermatocytes. In the present study, we used chromosomal mapping to determine the genomic background associated with small testis size in MRL mice. We prepared and analyzed C57BL/6-based congenic mice carrying MRL mouse loci. Quantitative trait loci (QTL) analysis revealed susceptibility loci for small testis size at 100 cM on chromosome (Chr) 1 and at around 80 cM on Chr 2. Analysis with B6.MRLc1 and B6.MRLc2 congenic mice, and double congenic mice, confirmed the QTL data and showed that low testis weight in MRL mice was caused by germ cell apoptosis. Through histological examinations, we found that B6.MRLc1 and B6.MRLc2 mice showed stage-specific apoptosis in their testes, the former at metaphase stage XII and the later at pachytene stage IV. Metaphase-specific apoptosis of spermatocytes occurs due to mutation of the exonuclease 1 (Exo1) gene located at 100 cM on Chr 1. Thus the mutation of the Exo1 gene is also responsible for low testis weight caused by metaphase-specific apoptosis. In conclusion, testis weight is reduced in MRL mice due to apoptosis of germ cells caused by mutations in loci on Chrs 1 and 2
Genomic analysis of the appearance of testicular oocytes in MRL/MpJ mice
No full textMammals produce sperm or oocytes depending on their sex; however, newborn MRL/MpJ (MRL) male mice produce oocytes within their testes. We previously reported that one of the genes responsible for this phenotype is present on the MRL-type Y chromosome (Y^[MRL]), and that multiple genes, probably autosomal, are also required for the development of this phenotype. In this study, we focused on the autosomal genes and examined their relationship with this phenotype by analyzing the progeny from crosses between MRL mice and other strains. We first observed the male F1 progeny from the crosses between female A/J, C57BL/6 (B6), BALB/c, C3H/He, or DBA/2 mice and male MRL mice, and 2 consomic strains, male B6-Y^[MRL] and MRL-Y^[B6]. Testicular oocytes that were morphologically similar to those of MRL mice were detected in all mouse strains except BALBMRLF1; however, the incidence of testicular oocytes was significantly lower than that in MRL mice. The appearance of testicular oocytes in MRL-Y^[B6] mice indicates that this phenotype is strongly affected by genomic factors present on autosomes, and that there is at least 1 other causative gene on the MRL-type autosomes (MRL testicular oocyte production; mtop) other than that on Y^[MRL]. Furthermore, a quantitative trait locus (QTL) analysis using N2 backcross progeny from crosses between female MRLB6F1 and male MRL mice revealed the presence of susceptibility loci for the appearance of testicular oocytes at 8-17cM on Chr 15. These findings demonstrate that the appearance of testicular oocytes is regulated by the genetic factors on Chr 15 and on Y^[MRL]
Diagnosis and early detection of CNS-SLE in MRL/Ipr mice using peptide microarrays
No full textabstract: Background
An accurate method that can diagnose and predict lupus and its neuropsychiatric manifestations is essential since currently there are no reliable methods. Autoantibodies to a varied panel of antigens in the body are characteristic of lupus. In this study we investigated whether serum autoantibody binding patterns on random-sequence peptide microarrays (immunosignaturing) can be used for diagnosing and predicting the onset of lupus and its central nervous system (CNS) manifestations. We also tested the techniques for identifying potentially pathogenic autoantibodies in CNS-Lupus. We used the well-characterized MRL/lpr lupus animal model in two studies as a first step to develop and evaluate future studies in humans.
Results
In study one we identified possible diagnostic peptides for both lupus and altered behavior in the forced swim test. When comparing the results of study one to that of study two (carried out in a similar manner), we further identified potential peptides that may be diagnostic and predictive of both lupus and altered behavior in the forced swim test. We also characterized five potentially pathogenic brain-reactive autoantibodies, as well as suggested possible brain targets.
Conclusions
These results indicate that immunosignaturing could predict and diagnose lupus and its CNS manifestations. It can also be used to characterize pathogenic autoantibodies, which may help to better understand the underlying mechanisms of CNS-Lupus.Study 1- Behavioral Dysfunction (Forced Swim Test). A significant difference in float time was detected (F = 12.068, p < 0.008) and post-hoc analysis at p < 0.007 revealed that the 4 month MRL/lpr had significantly greater float times compared to the MRL/mp and C3H/HeJ.Study 1 – Group Separation within MRL/lpr by Anti-DNA Autoantibody Levels. The 4 M MRL/lpr mice were also split based on their anti-DNA antibody levels (grouping was similar to Figure 3). There was a significant difference between the groups (F = 91.176, p < 0.001). Utilizing post-hoc analysis at p < 0.004 there was a significant difference between the 4 month MRL/lpr with greater anti-DNA autoantibody levels and the 4 month MRL/lpr with lower anti-DNA autoantibody levels, the MRL/mp and the C3H/HeJ. There was also a significant difference between the MRL/lpr with lower anti-DNA autoantibody levels and the MRL/mp and the C3H/HeJ.Study 2 - Behavioral Dysfunction (Forced Swim Test). There was an overall significant difference between the groups (F = 11.057, p < 0.001) and post-hoc analysis at p < 0.05 revealed that the 4 M MRL/lpr floated significantly longer than the 1.5 M MRL/lpr, 1.5 M MRL/mp and 4 M MRL/mp. The 1.5 M MRL/mp was significantly different from the 4 M MRL/mp.Sample peptide binding intensities across pooled samples. This figure demonstrated the intensity pattern across individual mice of different strains. Each green dot is the binding of the serum to an individual peptide. (A) Secondary Only Control (only secondary and tertiary antibodies added). (B) C3H/HeJ. (C) MRL/lpr strain. (D) MRL/mp.Immunohistochemistry Control Slides. The above (orange-yellow) fluorescence is from propidium iodide binding to the cell nuclei. (A), (B), (C) and (D) showed that there was no binding in most of the brain section, the hippocampus, cortex and amygdala for the secondary only control. (E), (F), (G) and (H) showed that there was no binding in the whole brain, hippocampus, cortex and amygdala for the auto-fluorescence control
MRL/MpJ mice produce more oocytes and exhibit impaired fertilisation and accelerated luteinisation after superovulation treatment
No full textMRL/MpJ mice exhibit distinct phenotypes in several biological processes, including wound healing. Herein we report two unique phenotypes in the female reproductive system of MRL/MpJ mice that affect ovulation and luteinisation. We found that superovulation treatment resulted in the production of significantly more oocytes in MRL/MpJ than C57BL/6 mice (71.0 +/- 13.4 vs 26.8 +/- 2.8 respectively). However, no exon mutations were detected in genes coding for female reproductive hormones or their receptors in MRL/MpJ mice. In addition, the fertilisation rate was lower for ovulated oocytes from MRL/MpJ than C57BL/6 mice, with most of the fertilised oocytes showing abnormal morphology, characterised by deformation and cytolysis. Histological tracing of luteinisation showed that MRL/MpJ mice formed corpora lutea within 36h after ovulation, whereas C57BL/6 mice were still at the corpora haemorrhagica formation stage after 36h. The balance between the expression of matrix metalloproteinases and their tissue inhibitors shifted towards the former earlier after ovulation in MRL/MpJ than C57BL/6 mice. This result indicates a possible link between accelerated extracellular matrix remodelling in the ovulated or ruptured follicles and luteinisation in MRL/MpJ mice. Together, these findings reveal novel phenotypes in MRL/MpJ mice that provide novel insights into reproductive biology
MRL/MpJ-Fas(lpr) mice show abnormalities in ovarian function and morphology with the progression of autoimmune disease
No full textThe immune system is known to affect reproductive function, and maternal-fetal immune tolerance is essential for a successful pregnancy. To investigate the relationship between autoimmune disease and female reproductive function, we performed a comparative analysis of the ovarian phenotypes for C57BL/6 mice, autoimmune disease-prone MRL/MpJ (MRL/+) mice and congenic MRL/MpJ-Fas(lpr) (MRL/lpr) mice harboring a mutation in the Fas gene that speeds disease onset. Both MRL-background strains showed earlier vaginal opening than C57BL/6 mice. The estrous cycle became irregular by 6 and 12 months of age in MRL/lpr mice and mice of the other two strains, respectively. Histological analysis at 3 months revealed that the number of primordial follicles was smaller in MRL-background mice than in C57BL/6 mice after 3 months. In addition, MRL/lpr and MRL/+ mice displayed lower numbers of ovarian follicles and corpora lutea at 3 and 6 months, and 6 and 12 months, respectively, than that in age-matched C57BL/6 mice. MRL/lpr and MRL/+ mice developed ovarian interstitial glands after 3 and 6 months, respectively. In particular, MRL/lpr mice showed numerous infiltrating lymphocytes within the ovarian interstitia, and partially stratified ovarian surface epithelia with more developed microvilli than that observed in C57BL/6 mice at 6 months. No significant differences in serum hormone levels were observed between the strains. In conclusion, MRL/lpr mice display altered ovarian development, morphology and function consistent with the progression of severe autoimmune disease, as these findings are less severe in MRL/+ counterparts
Quantitative trait locus analysis of ovarian cysts derived from rete ovarii in MRL/MpJ mice
No full textMRL/MpJ (MRL) is a model mouse for autoimmune diseases that shows dermatitis, vasculitis, arthritis, and glomerulonephritis. In addition to these immune-associated disorders, we found that aged MRL mice develop ovarian cysts originating from the rete ovarii, which is lined by ciliated or nonciliated epithelium and considered remnants of mesonephric tubules. Ovarian cysts, which are reported to have several sources, are associated with female infertility, but information regarding the genetic etiology of ovarian cysts originating from the rete ovarii is rare. In this study, to elucidate the genetic background of development of ovarian cysts, we performed quantitative trait-locus (QTL) analysis using 120 microsatellite markers, which cover the whole genome of murine chromosomes, and 213 backcross progenies between female MRL and male C57BL/6N mice. The quantitative trait measured was the circumferences of rete ovarii or ovarian cysts. As a result, suggestive linkages were detected on Chr 3, 4, 6, and 11, but significant linkages were located on Chr 14 by interval mapping. We thereby designated the 27.5-cM region of Chr 14 "MRL Rete Ovarian Cysts (mroc)." The peak regions of Chr 4 and 14 in particular showed a close additive interaction (p < 0.00001). From these results, we concluded that multiple loci on Chr 3, 4, 6, 11, and 14 interact to result in development of ovarian cysts in MRL mice
Ovarian cysts in MRL/MpJ mice are derived from the extraovarian rete : a developmental study
No full textMRL/MpJ (MRL) mice, commonly used as a model for autoimmune disease, have a high frequency of ovarian cysts originating from the rete ovarii. In the present study, to clarify how the rete ovarii, which are remnants of mesonephric tubules during embryogenesis, progress to cystic formation with aging, the morphology of MRL rete ovarii was analyzed and compared to that of normal C57BL/6N (B6) mice. In B6 mice, the rete ovarii consisted of a series of tubules, including the extraovarian rete (ER), the connecting rete (CR), and the intraovarian rete (IR), based on their location. Although the ER of B6 mice was composed of highly convoluted tubules lined by both ciliated and non-ciliated epithelium, the tubules in the CR and IR had only non-ciliated cells. In MRL mice, dilations of the rete ovarii initiated from the IR rather than the ER or CR. Although the histological types of cells lining the lumen of the rete ovarii were the same as those in B6 mice, the ER in MRL mice showed a variety in morphology. In particular, the connections between the ER and ovary tended to disappear with increasing age and the development of ovarian cysts. Furthermore, the epithelium lining large ovarian cysts in MRL mice had ciliated cells forming the cluster. From these findings, it was suggested that cystic changes of the rete ovarii in MRL mice were caused by the dilations of the IR with invasion of the ER and CR into the ovarian medulla. These data provide new pathological mechanisms for ovarian cyst formation
Testicular oocytes in MRL/MpJ mice possess similar morphological, genetic, and functional characteristics to ovarian oocytes
No full textIn general, mammalian males produce only spermatozoa in their testes and females produce only oocytes in their ovaries. However, newborn MRL/MpJ male mice produce oocytes within their testes. In this study, we examined the initiation and progression of oogenesis in fetal and neonatal MRL/MpJ mouse testes and evaluated the characteristics of testicular oocytes. Germ cells with positive reactions to oogenesis markers such as NOBOX oogenesis homeobox and synaptonemal complex protein 3 were observed in the MRL/MpJ fetal testes on embryonic day 18.5. These fetal testicular oocytes possessed maternal-specific methylation patterns of histone and DNA. The level of DNA methylation was still low in postnatal testicular oocytes at day 14 after birth. Additionally, the postnatal testicular oocytes contained both X and Y chromosomes and had the ability to fuse with sperm. These results suggest that some XY germ cells in fetal testes of MRL/MpJ mice enter meiosis prematurely, undergo oogenesis, and differentiate into oocytes. In addition, MRL/MpJ testicular oocytes have the ability to carry on oogenesis before and shortly after birth until they obtain some of the morphological, epigenetic, and functional characteristics of oocytes. (C) 2015 Elsevier Ireland Ltd. All rights reserved
Altered ciliary morphofunction in the oviductal infundibulum of systemic autoimmune disease-prone MRL/MpJ-Fas(lpr/lpr) mice
No full textAccording to our previous reports, impaired oocyte pickup was observed in the oviductal infundibulum of an autoimmune disease (AD) mouse model, suggesting a relationship between female infertility and AD. This study examines the relationship between AD and infundibulum morphofunction by focusing on the epithelial cilia. Healthy MRL/MpJ and AD-prone MRL/MpJ-Fas(lpr/lpr) mice were examined at 3 and 6 months of age, representing early and late disease stages, respectively. Oocyte pickup indices decreased with AD progression indicated by splenomegaly, autoantibody production and increased T cell counts of infundibulum mucosa in MRL/MpJ-Fas(lpr/lpr) mice. Ciliary beating frequency (CBF) and height in the infundibulum were faster and higher in MRL/MpJ-Fas(lpr/lpr) mice than in MRL/MpJ mice at the early AD stages, although the absolute CBF values were lower at the late AD stage. At the late stage, ciliary height did not differ between mouse lines but the morphological index of cilia beating direction indicated randomized patterns in MRL/MpJ-Fas(lpr/lpr) mice. The tracheal mucosa was also examined as a representative example of cilia morphology; its CBF decreased at the late AD stage in MRL/MpJ-Fas(lpr/lpr); however, there were no AD-related morphological changes. Our results demonstrate altered cilia motility in systemic and reproductive organs, with such morphological changes of the infundibulum likely impairing function, including oocyte pickup
Genetic factors derived from the MRL/MpJ mouse function to maintain the integrity of spermatogenesis after heat exposure
No full textMRL/MpJ mice possess highly heat-shock-resistant spermatocytes (HRS) in comparison with C57BL/6 mice. This resistance depends on the MRL/MpJ-type loci at the 81 cM region of Chromosome (Chr) 1 and the 40 cM region of Chr 11. To evaluate the functions of these loci in detail, we examined the histopathological changes resulting from experimental cryptorchidism or transient scrotal heat stress (SHS) in the testes of C57BL/6-based congenic strains (B6.MRLc1, B6.MRLc11, and B6.MRLc1c11) carrying the MRL/MpJ-derived loci responsible for HRS. Among cryptorchid testes from congenic strains, those in B6.MRLc1c11 mice showed the highest heat resistance, indicating that the genetic interactions between MRL/MpJ-derived HRS loci on Chrs 1 and 11 may be important for maintaining spermatogenesis under continuous testicular hyperthermia. In contrast, immediately after SHS induction, germ cell loss via apoptosis was inhibited in B6.MRLc11 and B6.MRLc1c11 mice, similar to that in MRL/MpJ mice. However, this HRS phenotype was not observed in C57BL/6 or B6.MRLc1 mice after SHS induction. Furthermore, testicular calcification owing to long-term damage by SHS induction was inhibited in all congenic strains in comparison with that in C57BL/6 mice, indicating that each MRL/MpJ-derived locus on Chrs 1 and 11 acted independently to facilitate the recovery of heat-induced testicular damage by inhibiting calcification. B6.MRLc11 and B6.MRLc1c11 mice showed greater recovery in spermatogenesis than B6.MRLc1 mice 60 days after SHS induction. Therefore, the MRL/MpJ-derived HRS locus on Chr 11 might play an important role in recovery from heat stress damage. On the basis of these results, we concluded that MRL/MpJ-derived loci on Chrs 1 and 11 cooperatively or independently regulate testicular heat sensitivity depending on the various heat stresses
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