Mutant Females Research Articles

Cytological Observation and Candidate Gene Identification of a Female Semi-Sterile Rice Mutant

Rice is an important staple crop, and fertilization has a very important role in the production of high-yield and well-quality hybrid of rice. The abnormal development of female gametes will lead to a significant decrease in rice yields. Due to the complex mechanism of female gamete development, the molecular mechanism of female sterility has not made a breakthrough. In this study, one semi-sterile mutant m21 and its fifth generation of backcross material (WZN58 and WZN68) were used as materials, and the phenotypic observation and cytological observation of embryo sac development were performed. Moreover, the pollen viability was evaluated by iodine potassium iodide (I2-KI) staining. Bulked-segregant analysis (BSA) re-sequencing and transgenic analysis were further applied to investigate the molecular mechanism of semi-sterile phenotype. These results demonstrated that male gamete development was normal, while the abnormality of the mutant was caused by the abnormal development of female gamete. Among 112 candidate genes detected by BSA, one gene Os10g0506000 was identified responsible for the semi-sterile phenotype of m21 mutant. This study provides an ideal material and candidate gene for rice female fertility analysis.

BmPMFBP1 regulates the development of eupyrene sperm in the silkworm, Bombyx mori.

Sperm deliver the male complement of DNA to the ovum, and thus play a key role in sexual reproduction. Accordingly, spermatogenesis has outstanding significance in fields as disparate as infertility treatments and pest-control, making it a broadly interesting and important focus for molecular genetics research in a wide range of species. Here we investigate spermatogenesis in the model lepidopteran insect Bombyx mori (silkworm moth), with particular focus on the gene PMFBP1 (polyamine modulated factor 1 binding protein 1). In humans and mouse, PMFBP1 is essential for spermatogenesis, and mutations of this gene are associated with acephalic spermatozoa, which cause infertility. We identified a B. mori gene labeled as “PMFBP1” in GenBank’s RefSeq database and sought to assess its role in spermatogenesis. Like in mammals, the silkworm version of this gene (BmPMFBP1) is specifically expressed in testes. We subsequently generated BmPMFBP1 mutants using a transgenic CRISPR/Cas9 system. Mutant males were sterile while the fertility of mutant females was comparable to wildtype females. In B. mori, spermatogenesis yields two types of sperm, the nucleated fertile eupyrene sperm, and anucleated unfertile apyrene sperm. Mutant males produced abnormal eupyrene sperm bundles but normal apyrene sperm bundles. For eupyrene sperm, nuclei were mislocated and disordered inside the bundles. We also found the BmPMFBP1 deficiency blocked the release of eupyrene sperm bundles from testes to ejaculatory seminalis. We found no obvious abnormalities in the production of apyrene sperm in mutant males, and double-matings with apyrene-deficient sex-lethal mutants rescued the ΔBmPMFBP1 infertility phenotype. These results indicate BmPMFBP1 functions only in eupyrene spermatogenesis, and highlight that distinct genes underlie the development of the two sperm morphs commonly found in Lepidoptera. Bioinformatic analyses suggest PMFBP1 may have evolved independently in lepidoptera and mammals, and that despite the shared name, are likely not homologous genes.

Predation Stress Causes Excessive Aggression in Female Mice with Partial Genetic Inactivation of Tryptophan Hydroxylase-2: Evidence for Altered Myelination-Related Processes.

The interaction between brain serotonin (5-HT) deficiency and environmental adversity may predispose females to excessive aggression. Specifically, complete inactivation of the gene encoding tryptophan hydroxylase-2 (Tph2) results in the absence of neuronal 5-HT synthesis and excessive aggressiveness in both male and female null mutant (Tph2−/−) mice. In heterozygous male mice (Tph2+/−), there is a moderate reduction in brain 5-HT levels, and when they are exposed to stress, they exhibit increased aggression. Here, we exposed female Tph2+/− mice to a five-day rat predation stress paradigm and assessed their emotionality and social interaction/aggression-like behaviors. Tph2+/− females exhibited excessive aggression and increased dominant behavior. Stressed mutants displayed altered gene expression of the 5-HT receptors Htr1a and Htr2a, glycogen synthase kinase-3 β (GSK-3β), and c-fos as well as myelination-related transcripts in the prefrontal cortex: myelin basic protein (Mbp), proteolipid protein 1 (Plp1), myelin-associated glycoprotein (Mag), and myelin oligodendrocyte glycoprotein (Mog). The expression of the plasticity markers synaptophysin (Syp) and cAMP response element binding protein (Creb), but not AMPA receptor subunit A2 (GluA2), were affected by genotype. Moreover, in a separate experiment, naïve female Tph2+/− mice showed signs of enhanced stress resilience in the modified swim test with repeated swimming sessions. Taken together, the combination of a moderate reduction in brain 5-HT with environmental challenges results in behavioral changes in female mice that resemble the aggression-related behavior and resilience seen in stressed male mutants; additionally, the combination is comparable to the phenotype of null mutants lacking neuronal 5-HT. Changes in myelination-associated processes are suspected to underpin the molecular mechanisms leading to aggressive behavior.

Molecular signature of cardiac remodeling associated with Polymerase Gamma mutation

AimsMetabolic function/dysfunction is central to aging biology. This is well illustrated by the Polymerase Gamma (POLG) mutant mouse where a key residue of the mitochondrial DNA polymerase is mutated (D257A), causing loss of mitochondrial DNA stability and dramatically accelerated aging processes. Given known cardiac phenotypes in the POLG mutant, we sought to characterize the course of cardiac dysfunction in the POLG mutant to guide future intervention studies. Materials and methodsCardiac echocardiography and terminal hemodynamic analyses were used to define the course of dysfunction in the right and left cardiac ventricles in the POLG mutant. We also conducted RNA-seq analysis on cardiac right ventricles to identify mechanisms engaged by severe metabolic dysfunction and compared this analysis to several publically available datasets. Key findingsInteresting sex differences were noted as female POLG mutants died earlier than male POLG mutants and LV chamber diameters were impacted earlier in females than males. Moreover, male mutants showed LV wall thinning while female mutant LV walls were thicker. Both males and females displayed significant RV hypertrophy. POLG mutants displayed a gene expression pattern associated with inflammation, fibrosis, and heart failure. Finally, comparative omics analyses of publically available data provide additional mechanistic and therapeutic insights. SignificanceAging-associated cardiac dysfunction is a growing clinical problem. This work uncovers sex-specific cardiac responses to severe metabolic dysfunction that are reminiscent of patterns seen in human heart failure and provides insights to the molecular mechanisms engaged downstream of severe metabolic dysfunction that warrant further investigation.

The impact of the Hsp67Bc gene product on Drosophila melanogaster longevity, fecundity, and acute heat stress tolerance.

Drosophila melanogaster Hsp67Bc is a heat- and cold-inducible small heat shock protein that participates in the prevention of aggregation of misfolded proteins and in macroautophagy regulation. Overexpression of the Hsp67Bc gene has been shown to enhance macroautophagy in Drosophila S2 cells, and the deletion of this gene leads to the formation of a slightly increased number of autophagic vacuoles in the fruit f ly brain neurons. Recently, we found that Hsp67Bc-null D. melanogaster f lies have poor tolerance to cold stress (0 °C) of various durations. In the present work, we investigated how the Hsp67Bc gene deletion affects the f itness of fruit f lies under normal conditions and their tolerance to elevated temperatures at different developmental stages. Larvae and pupae were not adversely affected by the Hsp67Bc gene deletion, and adult Hsp67Bc-null f lies showed an extended lifespan in comparison with the control at normal (24–25 °C) and elevated temperature (29 °C), and after acute heat stress (37 °C, 2 h). At the same time, the fecundity of the mutant females was lower by 6–13 % in all tested environments, except for permanent maintenance at 29 °C, where the mean numbers of eggs laid by the mutant and control f lies were equal. We explain this phenomenon by a reduced number of ovarioles in Hsp67Bc-null females and enhanced macroautophagy in their germaria, which promotes the death of forming egg chambers. In addition, short heat stress (37 °C, 2 h), which increased the control line’s longevity (an effect common for a wide range of organisms), had a negative impact on the lifespan of Hsp67Bc-null f lies. Therefore, Hsp67Bc-null D. melanogaster have an extended lifespan under normal and elevated temperature conditions, and reduced fecundity and thermal stress tolerance.

Impaired leptin signaling causes subfertility in female zebrafish

Reproduction is an energetically costly event across vertebrates and tightly linked to nutritional status and energy reserves. In mammals, the hormone leptin is considered as a link between energy homeostasis and reproduction. However, its role in fish reproduction is still unclear. In this study, we investigated the possible role of leptin in the regulation of reproduction in zebrafish, using a loss of function leptin receptor (lepr) strain. Impaired leptin signaling resulted in severe reproductive deficiencies in female zebrafish. lepr mutant females laid significantly fewer eggs, with low fertilization rates compared to wild-type females. Folliculogenesis was not affected, but oocyte maturation and ovulation were disrupted in lepr mutants. Interestingly, the expression of luteinizing hormone beta (lhb) in the pituitary was significantly lower in mutant females. Analysis of candidate genes in the ovaries and isolated fully grown follicles revealed differential expression of genes involved in steroidogenesis, oocyte maturation and ovulation in the mutants, which are known to be regulated by LH signaling. Moreover, subfertility in lepr mutants could be partially restored by administration of human chorionic gonadotropin. In conclusion, our results show that leptin deficiency does not affect early stages of follicular development, but leptin might be essential in later steps, such as in oocyte maturation and ovulation. To our knowledge, this is the first time that leptin is associated to reproductive deficiencies in zebrafish.

PiggyBac-based transgenic RNAi of serine protease 2 results in male sterility in Hyphantria cunea

Fall webworm, Hyphantria cunea, is a global invasive forest pest that causes serious damage to the economy and ecosystem of agriculture and forestry. Due to the extent of the problem and the difficulty of conventional chemical control, new technologies must be pursued, such as genetic-based inheritable insect sterile technology (gSIT), which exhibits promise for pest control. In the present study, we established a piggyBac-based transgenic system in fall webworm and generated a dominant male-sterile strain by targeting the seminal fluid protein serine protease 2 (Hcser2), displaying an outstanding trait of gSIT. First, an RNA polymerase type III (Pol III) promoter, the HcU62 small nuclear RNA (snRNA) gene promoter, was identified and characterized through direct injection of RNAi plasmids in vivo. Quantitative real-time PCR revealed that HcU62 had the greatest knockdown efficiency of the Hcyellow gene among five short hairpin RNA (shRNA) plasmids tested, designated HcU61–HcU65. Second, subsequent application of piggyBac-based transgenic RNAi (HcU62: shHcyellow, Ysh2) significantly reduced the expression level of the Hcyellow gene, resulting in a stable yellow observable phenotype from the larval to pupal stages in Ysh2 transgenic mutants. Finally, an HcU62-driven transgenic RNAi strain targeting the Hcser2 gene was obtained, resulting in a dominant male-sterile phenotype. Significantly, this process did not affect the growth, development, mating behavior or egg laying of the mutants, and the dominant sterile trait could be inherited in the next generation through female Hcser2 mutants. Furthermore, CRISPR/Cas9-mediated disruption of the Hcser2 gene further confirmed the dominant sterile phenotype, supporting it as a generalized target for genetic control of H. cunea. This study reports the first piggyBac-mediated transgenic system in H. cunea, providing a promising genetic method for controlling this pest by targeting Hcser2 gene.

The SSLepR mutant rat represents a novel model to study obesity-induced renal injury before puberty.

Prepubertal obesity (PPO) has emerged as a major health problem over the past few decades and is a risk factor for the development of proteinuria. The current study investigated whether the development of renal injury in the obese SSLepR mutant strain occurs before puberty. When determining the temporal changes in serum sex hormones in female and male SS and SSLepR mutant rats between 4 and 10 wk of age, we only observed significant increases in estradiol and testosterone levels in female and male SS rats at 10 wk of age than at 4 wk of age. The results suggest that studying both strains between 4 and 8 wk of age is appropriate to study the effects of PPO on renal injury in this model. Proteinuria was significantly higher in SSLepR mutant rats as opposed to the values observed in SS rats at 8 wk of age, and we did not observe any sex differences in proteinuria in either strain. The kidneys from the SSLepR mutant rats displayed significant glomerular and tubular injury and renal fibrosis versus the values measured in SS rats without any sex differences. Overall, we observed increased immune cell infiltration in the kidneys from SSLepR mutant rats compared with SS rats. Interestingly, female SSLepR mutant rats displayed significant increases in not only M1 macrophages (proinflammatory) but also M2 macrophages (anti-inflammatory) versus male SSLepR mutant rats. These results suggest the SSLepR mutant rat may be a useful model to study early progression of obesity-related renal injury before the onset of puberty.

Zfp57 Exerts Maternal and Sexually Dimorphic Effects on Genomic Imprinting.

Zfp57 has both maternal and zygotic functions in mouse. It maintains genomic imprinting at most known imprinted regions and controls allelic expression of the target imprinted genes in mouse embryos. The DNA methylation imprint at many imprinting control regions (ICRs) is lost when both maternal and zygotic Zfp57 are absent in Zfp57 maternal–zygotic mutant mouse embryos. Interestingly, we found that DNA methylation at a few ICRs was partially lost without maternal Zfp57 in Zfp57 heterozygous mouse embryos derived from Zfp57 homozygous female mice. This suggests that maternal Zfp57 is essential for the maintenance of DNA methylation at a small subset of imprinted regions in mouse embryos. This maternal effect of Zfp57 was applied to allelic expression switch as well as expression levels of the corresponding imprinted genes. It is rather surprising that DNA methylation imprint was affected differently at Rasgrf1 and AK008011 imprinted regions in the female or male Zfp57 maternal–zygotic mutant embryos, with more significant loss of DNA methylation observed in the male mutant embryos. Loss of ZFP57 resulted in gender-specific differences in allelic expression switch and expression level changes of some imprinted genes in female or male mutant embryos. These results indicate maternal and sexually dimorphic effects of ZFP57 on genomic imprinting in mouse.

Sex-Dependent Social and Repetitive Behavior and Neurochemical Profile in Mouse Model of Autism Spectrum Disorder.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficits in social interaction, impaired communication, and repetitive behaviors. ASD presents a 3:1 ratio of diagnosed boys and girls, raising the question regarding sexual dimorphic mechanisms underlying ASD symptoms, and their molecular basis. Here, we performed in vivo proton magnetic resonance spectroscopy in juvenile male and female Tsc2+/− mice (an established genetic animal model of ASD). Moreover, behavior and ultrasonic vocalizations during social and repetitive tasks were analyzed. We found significant sexual dimorphisms in the levels of metabolites in the hippocampus and prefrontal cortex. Further, we observed that female mutant animals had a differential social behavior and presented an increase in repetitive behavior. Importantly, while mutant females displayed a more simplified communication during social tasks, mutant males exhibited a similar less complex vocal repertoire but during repetitive tasks. These results hint toward sex-dependent alterations in molecular and metabolic pathways, which can lead to the sexual dimorphic behaviors and communication observed in social and repetitive environments.

Circumventing Zygotic Lethality to Generate Maternal Mutants in Zebrafish.

Simple SummaryMaternal gene products accumulated during oogenesis as mRNAs and proteins, which are referred to as maternal contributions, play essential roles in proper development before and after the transcription of the zygotic genome. Zebrafish represent an attractive model for the systematic characterization of genetic mutants using the CRISPR/Cas9 genome editing technology. The traditional approach for generating maternal mutants to study the functions of maternal gene products consists of creating founder fish with germ-line transmission of mutated genes, followed by successive crossing to obtain zygotic homozygous mutant females, which can produce offspring lacking the corresponding maternal gene products. This is time-consuming and normally requires three generations. Nevertheless, zygotic mutations of many genes often lead to embryonic lethality or adult sterility, making it impossible to study their maternal functions. Different approaches were used to overcome this difficulty and allowed for the characterization of several important maternal-effect genes. However, they are often technically challenging or lack versatile applications. Recently, an oocyte-specific knockout strategy has been developed, which inactivates genes of interest in the developing oocytes. It is particularly accessible, generating maternal mutants in one fish generation. By further improving its efficiency, this method can be used for the large-scale analysis of maternal gene functions.Maternal gene products accumulated during oogenesis are essential for supporting early developmental processes in both invertebrates and vertebrates. Therefore, understanding their regulatory functions should provide insights into the maternal control of embryogenesis. The CRISPR/Cas9 genome editing technology has provided a powerful tool for creating genetic mutations to study gene functions and developing disease models to identify new therapeutics. However, many maternal genes are also essential after zygotic genome activation; as a result, loss of their zygotic functions often leads to lethality or sterility, thus preventing the generation of maternal mutants by classical crossing between zygotic homozygous mutant adult animals. Although several approaches, such as the rescue of mutant phenotypes through an injection of the wild-type mRNA, germ-line replacement, and the generation of genetically mosaic females, have been developed to overcome this difficulty, they are often technically challenging and time-consuming or inappropriate for many genes that are essential for late developmental events or for germ-line formation. Recently, a method based on the oocyte transgenic expression of CRISPR/Cas9 and guide RNAs has been designed to eliminate maternal gene products in zebrafish. This approach introduces several tandem guide RNA expression cassettes and a GFP reporter into transgenic embryos expressing Cas9 to create biallelic mutations and inactivate genes of interest specifically in the developing oocytes. It is particularly accessible and allows for the elimination of maternal gene products in one fish generation. By further improving its efficiency, this method can be used for the systematic characterization of maternal-effect genes.

Analysis of Sex-Specific Prostanoid Production Using a Mouse Model of Selective Cyclooxygenase-2 Inhibition.

Prostanoids are a family of lipid mediators formed from arachidonic acid by cyclooxygenase enzymes and serve as biomarkers of vascular function. Prostanoid production may be different in males and females indicating that different therapeutic approaches may be required during disease. We examined sex-dependent differences in COX-related metabolites in genetically modified mice that produce a cyclooxygenase-2 (COX2) enzyme containing a tyrosine 385 to phenylalanine (Y385F) mutation. This mutation renders the COX2 enzyme unable to form a key intermediate radical required for complete arachidonic acid metabolism and provides a model of selective COX2 inhibition. Mice heterozygous for the Y385F mutation in COX2 were mated to produce cohorts of wild-type, heterozygous, and COX2 mutant mice. We investigated whether the genotype distribution followed Mendelian genetics and studied whether sex-specific differences could be found in certain prostanoid levels measured in peritoneal macrophages and in urinary samples. The inheritance of the COX2 mutation displayed a significant deviation with respect to Mendel's laws of genetics, with a lower-than-expected progeny of weaned COX2 mutant pups. In macrophages, prostaglandin E2 (PGE2) production following lipopolysaccharide (LPS) and interferon gamma (IFNγ) stimulation was COX2-dependent in both males and females, and data indicated that crosstalk between the nitric oxide (NO) and COX2 pathways may be sex specific. We observed significant differences in urinary PGE2 production by male and female COX2 mutant mice, with the loss of COX2 activity in male mice decreasing their ability to produce urinary PGE2. Finally, female mice across all 3 genotypes produced similar levels of urinary thromboxane (measured as 11-dehydro TxB2) at significantly higher levels than males, indicating a sex-related difference that is likely COX1-derived. Our findings clearly demonstrate that sex-related differences in COX-derived metabolites can be observed, and that other pathways (such as the NO pathway) are affected.

Maternal EHMT2 is essential for homologous chromosome segregation by regulating Cyclin B3 transcription in oocyte meiosis.

During oocyte growth, various epigenetic modifications are gradually established, accompanied by accumulation of large amounts of mRNAs and proteins. However, little is known about the relationship between epigenetic modifications and meiotic progression. Here, by using Gdf9-Cre to achieve oocyte-specific ablation of Ehmt2 (Euchromatic-Histone-Lysine-Methyltransferase 2) from the primordial follicle stage, we found that female mutant mice were infertile. Oocyte-specific knockout of Ehmt2 caused failure of homologous chromosome separation independent of persistently activated SAC during the first meiosis. Further studies revealed that lacking maternal Ehmt2 affected the transcriptional level of Ccnb3, while microinjection of exogenous Ccnb3 mRNA could partly rescue the failure of homologous chromosome segregation. Of particular importance was that EHMT2 regulated ccnb3 transcriptions by regulating CTCF binding near ccnb3 gene body in genome in oocytes. In addition, the mRNA level of Ccnb3 significantly decreased in the follicles microinjected with Ctcf siRNA. Therefore, our findings highlight the novel function of maternal EHMT2 on the metaphase I-to-anaphase I transition in mouse oocytes: regulating the transcription of Ccnb3.

Maternal Smc3 protects the integrity of the zygotic genome through DNA replication and mitosis.

ABSTRACTAneuploidy is frequently observed in oocytes and early embryos, begging the question of how genome integrity is monitored and preserved during this crucial period. SMC3 is a subunit of the cohesin complex that supports genome integrity, but its role in maintaining the genome during this window of mammalian development is unknown. We discovered that, although depletion of Smc3 following meiotic S phase in mouse oocytes allowed accurate meiotic chromosome segregation, adult females were infertile. We provide evidence that DNA lesions accumulated following S phase in SMC3-deficient zygotes, followed by mitosis with lagging chromosomes, elongated spindles, micronuclei, and arrest at the two-cell stage. Remarkably, although centromeric cohesion was defective, the dosage of SMC3 was sufficient to enable embryogenesis in juvenile mutant females. Our findings suggest that, despite previous reports of aneuploidy in early embryos, chromosome missegregation in zygotes halts embryogenesis at the two-cell stage. Smc3 is a maternal gene with essential functions in the repair of spontaneous damage associated with DNA replication and subsequent chromosome segregation in zygotes, making cohesin a key protector of the zygotic genome.

Inheritance Pattern of Hereditary Angioedema Indicates Mutation-Dependent Selective Effects During Early Embryonic Development

Hereditary angioedema (HAE) may be caused by a genetic deficiency of functional C1 inhibitor (C1-INH) or linked with mutations in the F12, PLG, and other genes in combination with normal C1-INH (HAEnCI). Although the types of hereditary angioedema due to deficiency of functional C1 inhibitor and HAEnCI are autosomal dominant inherited, there is the impression that in the types of HAEnCI more females carry disease-linked mutations. The aim of this study was to analyze the passing on of the HAE-specific mutations to the next generations in families with various types of HAE. Methods comprised pedigree analysis, Sanger sequencing analysis, biochemical analysis of parameters of the kallikrein-kinin system, and statistical analysis of the results. We analyzed a total of 1494 offspring of individuals carrying an HAE-linked mutation. In HAE, less male and more female offspring of mutation carriers than expected for autosomal dominant inheritance inherited the familial mutation. In addition, there were less male offspring than expected in HAEnCI. This was independent of paternal or maternal inheritance. We conclude that there is a sex- and mutation-dependent selection during early embryogenesis, possible around the time of implantation, favoring male wild-type and female mutant embryos. It also appears that 20% to 25% of male embryos carrying the HAE mutation are lost specific in HAEnCI.These findings point out that there is a potentially important role of the kallikrein-kinin system during early embryonic development.

Queer kinship in Chris Claremont and Allen milgrom’s Kitty Pryde and Wolverine

ABSTRACT In 1984, Chris Claremont (writer) and Allen Milgrom (artist) created a six-issue miniseries that explored the relationship and mutant identity of two mutants, Wolverine and Kitty Pryde. Kitty Pryde and Wolverine (1984–85) tells the story of Katherine Pryde’s evolution into the heroine, Shadowcat, helped by a very wounded and healing, Wolverine. Set in Japan, the story isolates the two characters from the other X-Men in order for them to learn to rely on each other as they grow and heal. This miniseries showcases the queerness of mutants through the forging of queer kinship, as well as an open rejection of normative family structures. In this way, Claremont explores not only the nature of mutants, but how mutants see themselves as a community. By the end of this story, Shadowcat and Wolverine have grown considerably in their mutant identities; Wolverine has become a more open and caring mentor, while Shadowcat now recognises her power outside normative expectations of female mutants.

The Human SCN10AG1662S Point Mutation Established in Mice Impacts on Mechanical, Heat, and Cool Sensitivity.

The voltage-gated sodium channel NAV1.8 is expressed in primary nociceptive neurons and is involved in pain transmission. Mutations in the SCN10A gene (encoding NAV1.8 channel) have been identified in patients with idiopathic painful small fiber neuropathy (SFN) including the SCN10AG1662S gain-of-function mutation. However, the role of this mutation in pain sensation remains unknown. We have generated the first mouse model for the G1662S mutation by using homologous recombination in embryonic stem cells. The corresponding Scn10aG1663S mouse line has been analyzed for Scn10a expression, intraepidermal nerve fiber density (IENFD), and nociception using behavioral tests for thermal and mechanical sensitivity. The Scn10aG1663S mutants had a similar Scn10a expression level in dorsal root ganglia (DRG) to their wild-type littermates and showed normal IENFD in hindpaw skin. Mutant mice were more sensitive to touch than wild types in the von Frey test. In addition, sexual dimorphism was observed for several pain tests, pointing to the relevance of performing the phenotypical assessment in both sexes. Female homozygous mutants tended to be more sensitive to cooling stimuli in the acetone test. For heat sensitivity, male homozygous mutants showed shorter latencies to radiant heat in the Hargreaves test while homozygous females had longer latencies in the tail flick test. In addition, mutant males displayed a shorter reaction latency on the 54°C hot plate. Collectively, Scn10aG1663S mutant mice show a moderate but consistent increased sensitivity in behavioral tests of nociception. This altered nociception found in Scn10aG1663S mice demonstrates that the corresponding G1662 mutation of SCN10A found in SFN patients with pain contributes to their pain symptoms.

Sex disparate gut microbiome and metabolome perturbations precede disease progression in a mouse model of Rett syndrome

Rett syndrome (RTT) is a regressive neurodevelopmental disorder in girls, characterized by multisystem complications including gut dysbiosis and altered metabolism. While RTT is known to be caused by mutations in the X-linked gene MECP2, the intermediate molecular pathways of progressive disease phenotypes are unknown. Mecp2 deficient rodents used to model RTT pathophysiology in most prior studies have been male. Thus, we utilized a patient-relevant mouse model of RTT to longitudinally profile the gut microbiome and metabolome across disease progression in both sexes. Fecal metabolites were altered in Mecp2e1 mutant females before onset of neuromotor phenotypes and correlated with lipid deficiencies in brain, results not observed in males. Females also displayed altered gut microbial communities and an inflammatory profile that were more consistent with RTT patients than males. These findings identify new molecular pathways of RTT disease progression and demonstrate the relevance of further study in female Mecp2 animal models.

A new allele of engrailed, enNK14, causes supernumerary spermathecae in Drosophila melanogaster.

A spontaneous mutation, enNK14, was a new allele of engrailed (en) in Drosophila melanogaster. Females of enNK14 have three spermathecae, instead of two in wild type, under a wide range of developmental temperatures, while the males show no abnormal phenotype. Spermathecae of the mutant female can accept inseminated sperms, albeit with a delay of at least an hour until full acceptance compared with wild type. The time course of decrease in the number of stored sperms was thoroughly similar between the mutant and wild type. enNK14 females produced fewer progeny than wild type females despite storing a larger number of sperms. The delay of sperm entry and lower fecundity suggested some functional defects in secretory products of the spermathecae. In addition, some spermathecae in the mutant were accompanied by a mass of brown pigments in the adipose tissue surrounding the capsule. Six contiguous amino acids, Ser340-Ala345, were replaced by one Thr in enNK14. In another mutant, enspt, Ser325 was also shown to be substituted by a Cys. These amino acid changes were located within a serine-rich region, in which Ser325, Ser340 and Thr341 were suggested as targets of Protein Kinase C by an in silico analysis. The splicing pattern of en mRNA did not differ between enNK14 and wild type in embryo, larva, pupa or adult. Our results suggest that en plays an important role in determining the number of spermathecae as well as in sperm storage function in the Drosophila female.

SWI/SNF chromatin remodeling complex is required for initiation of sex-dependent differentiation in mouse germline

Sexual reproduction involves the creation of sex-dependent gametes, oocytes and sperm. In mammals, sexually dimorphic differentiation commences in the primordial germ cells (PGCs) in embryonic gonads; PGCs in ovaries and testes differentiate into meiotic primary oocytes and mitotically quiescent prospermatogonia, respectively. Here, we show that the transition from PGCs to sex-specific germ cells was abrogated in conditional knockout mice carrying a null mutation of Smarcb1 (also known as Snf5) gene, which encodes a core subunit of the SWI/SNF chromatin remodeling complex. In female mutant mice, failure to upregulate meiosis-related genes resulted in impaired meiotic entry and progression, including defects in synapsis formation and DNA double strand break repair. Mutant male mice exhibited delayed mitotic arrest and DNA hypomethylation in retrotransposons and imprinted genes, resulting from aberrant expression of genes related to growth and de novo DNA methylation. Collectively, our results demonstrate that the SWI/SNF complex is required for transcriptional reprogramming in the initiation of sex-dependent differentiation of germ cells.