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Oxidative folding of extracellular proteins is pivotal for the biogenesis of bacterial virulence factors. Escherichia coli DsbA catalyzes disulfide bond formation in extracellular proteins and in multicomponent architectures on the cell surface. The present study assessed the significance of the redox properties of DsbA by exploiting the plaque-forming ability of bacteriophage M13, which specifically recognizes F-pili during infection of the host cell. A library of mutant dsbA genes was constructed by randomizing the dipeptide XX sequence in the active-site redox motif CXXC and then screened for mutants that altered plaque yield and appearance. In total, 24 dsbA mutant alleles produced substantially different degrees of complementation, and one mutant dsbA gene that encodes a CDIC sequence produced over 40-fold more clear plaques than wild type dsbA. The redox potential of purified DsbA [CDIC] was −172 mV, representing a less-oxidizing catalysis than the wild type DsbA (−122 mV), but one that is closer to yeast protein disulfide isomerase (−175 mV). DsbA [CDIC] exhibited a greater ability to refold fully denatured glutathionylated ribonuclease A than the wild type enzyme and a DsbA [CRIC] mutant, which has the same redox potential of −172 mV. Homology modeling and molecular dynamics simulation suggest that the CDIC mutant may have an enlarged substrate-binding cleft near the redox center, which confers kinetic advantages when acting on protein substrates.

Streptomyces incarnatus NRRL8089 produces the antiviral, antifungal, antiprotozoal nucleoside antibiotic sinefungin. To enhance sinefungin production, multiple mutations were introduced to the rpoB gene encoding RNA polymerase (RNAP) β-subunit at the target residues, D447, S453, H457, and R460. Sparse regression analysis using elastic-net lasso-ridge penalties on previously reported H457X mutations identified a numeric parameter set, which suggested that H457R/Y/F may cause production enhancement. H457R/R460C mutation successfully enhanced the sinefungin production by 3-fold, while other groups of mutations, such as D447G/R460C or D447G/H457Y, made moderate or even negative effects. To identify why the rif cluster residues have diverse effects on sinefungin production, an RNAP/DNA/mRNA complex model was constructed by homology modeling and molecular dynamics simulation. The 4 residues were located near the mRNA strand. Density functional theory–based calculation suggested that D447, H457, and R460 are in direct contact with ribonucleotide, and partially positive charges are induced by negatively charged chain of mRNA.

In mouse testes, spermatogonial stem cells (SSCs), a subpopulation of GFRα1 (GDNF family receptor-α1)-positive spermatogonia, are widely distributed along the convoluted seminiferous tubules. The proliferation and differentiation of the SSCs are regulated in part by local expression of GDNF (glial cell-derived neurotorphic factor), one of major niche factors for SSCs. However, the in vivo dynamics of the GDNF-stimulated GFRα1-positive spermatogonia remains unclear. Here, we developed a simple method for transplanting DiI-labeled and GDNF-soaked beads into the mouse testicular interstitium. By using this method, we examined the dynamics of GFRα1-positive spermatogonia in the tubular walls close to the transplanted GDNF-soaked beads. The bead-derived GDNF signals were able to induce the stratified aggregate formation of GFRα1-positive undifferentiated spermatogonia by day 3 post-transplantation. Each aggregate consisted of tightly compacted Asingle and marginal Apaired-Aaligned GFRα1-positive spermatogonia and was surrounded by Aaligned GFRα1-negative spermatogonia at more advanced stages. These data not only provide in vivo evidence for the inductive roles of GDNF in forming a rapid aggregation of GFRα1-positive spermatogonia but also indicate the usefulness of this in vivo assay system of various growth factors for the stem/progenitor spermatogonia in mammalian spermatogenesis.

dl-Penicillamine, a copper-specific metal chelator, remarkably suppressed the growth of Bacillus subtilis 168 when added to a synthetic medium under Cu2+ limitation. DNA microarray and screening of 2,602 knockout mutants showed that the zosA gene was de-repressed in the presence of 0.1% dl-penicillamine, and that the zosA mutant was sensitive to dl-penicillamine medium. The zosA mutant delayed the growth under Cu-limitation even without the chelator, and the sensitivity to dl-penicillamine was reversed by induction using 0.3 mM IPTG and the Pspac promoter inserted directly upstream of the zosA gene. Furthermore, the zosA mutant showed elevated tolerance of excessive Cu2+ but not of excessive Zn2+ added to LB and synthetic media. Homology modeling of the ZosA protein suggested that the protein can fold itself into essential domains for constituting a metal transporting ATPase. Our study suggests that zosA is a candidate gene involved in copper uptake.

To explore possible roles of heparanase in cancer-host crosstalk, we examined whether heparanase influences expression of inflammatory chemokines in colorectal cancer cells. Murine colorectal carcinoma cells incubated with heparanase upregulated MCP-1, KC, and RANTES genes and released MCP-1 and KC proteins. Heparanase-dependent production of IL-8 was detected in two human colorectal carcinoma cell lines. Addition of a heparanase inhibitor Heparastatin (SF4) did not influence MCP-1 production, while both latent and mature forms of heparanase augmented MCP-1 release, suggesting that heparanase catalytic activity was dispensable for MCP-1 production. In contrast, addition of heparin to the medium suppressed MCP-1 release in a dose-dependent manner. Similarly, targeted suppression of Ext1 by RNAi significantly suppressed cell surface expression of heparan sulfate and MCP-1 production in colon 26 cells. Taken together, it is concluded that colon 26 cells transduce the heparanase-mediated signal through heparan sulfate binding. We propose a novel function for heparanase independent of its endoglycosidase activity, namely as a stimulant for chemokine production.

The sodium pump (Na,K-ATPase) in animal cells is vital for actively maintaining ATP hydrolysis-powered Na- and K+ electrochemical gradients across the cell membrane. These ion gradients drive co-And countertransport and are critical for establishing the membrane potential. It has been an enigma how Na,K-ATPase discriminates between Na- and K+, despite the pumped ion on each side being at a lower concentration than the other ion. Recent crystal structures of analogs of the intermediate conformations E2-Pi-2K+ and Na-bound E1-P-ADP suggest that the dimensions of the respective binding sites in Na,KATPase are crucial in determining its selectivity. Here, we found that the selectivity at each membrane face is pH-dependent and that this dependence is unique for each face. Most notable was a strong increase in the specific affinity for K+ at the extracellular face (i.e. E2 conformation) as thepHis lowered from 7.5 to 5.We also observed a smaller increase in affinity for K+ on the cytoplasmic side (E1 conformation), which reduced the selectivity for Na-. Theoretical analysis of the pKa values of ion-coordinating acidic amino acid residues suggested that the face-specific pH dependences and Na-/K+ selectivities may arise from the protonation or ionization of key residues. The increase in K+ selectivity at low pH on the cytoplasmic face, for instance, appeared to be associated with Asp808 protonation. We conclude that changes in the ionization state of coordinating residues in Na,K-ATPase could contribute to altering face-specific ion selectivity.

Great variations in the size, shape, color, feather structure and behavior are observed among fowl breeds. Because many types of domestic fowls have been bred for various purposes, they are ideal to assess the relationship between brain morphology and avian biology. However, little is known about changes in brain shape that may have occurred during fowl domestication. We analyzed the brains of red jungle fowl and domestic fowl to clarify differences in the brain shape between these breeds, as well as the shape changes associated with size enlargement using three-dimensional geometric morphometrics. Principal component and multivariate regression analyses showed that ventrodorsal bending, anteroposterior elongation and width reduction were significantly correlated with brain size. According to the size-dependent analysis, the red jungle fowl brain has an intermediate shape between the brain of young broilers and that of large domestic fowl and adult broilers. After the size effect is removed, geometric morphometric analyses show that the brain of red jungle fowl is different from that of domestic fowl, with large round cerebral hemispheres. Significant correlations exist between the skull length and brain volume among fowl, while the brain volume relative to the skull length is distinctly larger in red jungle fowl compared with domestic fowl. The distinct brain shape and increased relative brain size of red jungle fowl may be driven by the presence of large, rounded cerebral hemispheres.

Heparanase cleaves macromolecular heparin in the secretory granules of connective tissue-type mast cells. We investigated roles of the cleavage under a microenvironment mimicking where the mast cells physiologically reside. A connective tissue-type mast cell line MST and mouse peritoneal cell-derived mast cells stored macromolecular heparin in the secretory granules. The cells expressing heparanase stored fragmented heparin (~10 kDa) due to heparanase-dependent cleavage of the heparin. We produced an artificial collagen-based extracellular matrix and placed the live cells or glycosaminoglycans purified from the cells in the matrix to measure the release of sulfated macromolecules into the medium. The sulfate-radiolabelled molecules from the degranulating heparanase-expressing cells and the purified glycosaminoglycans showed significantly greater release into the medium than those derived from mock cells, which was not the case in suspension culture. The mast cell granular enzyme chymase, but not β-hexosaminidase, showed significantly greater release from the degranulating heparanase-expressing cells than from mock cells. Purified chymase mixed with fragmented heparin derived from heparanase-expressing cells showed greater release from collagen gels than the enzyme alone or mixed with macromolecular heparin derived from mock cells. We propose that the cleavage of macromolecular heparin by heparanase accelerates the release of heparin and chymase from extracellular matrices.

The gallbladder excretes cytotoxic bile acids to the duodenum through the cystic duct and common bile duct system. Sox17 haploinsufficiency causes the biliary atresia-like phenotypes and hepatitis in late organogenesis mouse embryos. However, the molecular and cellular mechanisms in the Sox17-haploinsufficient gallbladder and liver in the etiology of biliary atresia remain unclear. In this study, transcriptomic analyses revealed the early onset of cholecystitis in the Sox17+/- embryos, together with the appearance of ectopic cystic duct-like epithelia in their gallbladders. The embryonic hepatitis showed positive correlations with the severities of cholecystitis in individual Sox17+/- embryos, in addition that the embryonic hepatitis could be induced by conditional deletion of Sox17 in the primordial gallbladder epithelia, but not in the fetal liver hepatoblasts. The Sox17+/- gallbladder also showed the drastic reduction in Sonic hedgehog expression, leading to aberrant smooth muscle formation and defective contraction of the fetal gallbladder. The defective gallbladder contraction positively correlated with the severity of embryonic hepatitis in Sox17+/- embryos, suggesting the potential contribution of embryonic cholecystitis and fetal gallbladder contraction in the early pathogenesis of congenital biliary atresia.

Congenital biliary atresia is an incurable disease of newborn infants, of unknown genetic causes, that results in congenital deformation of the gallbladder and biliary duct system. Here, we show that during mouse organogenesis, insufficient SOX17 expression in the gallbladder and bile duct epithelia results in congenital biliary atresia and subsequent acute ‘embryonic hepatitis’, leading to perinatal death in ~95% of the Sox17 heterozygote neonates in C57BL/6 (B6) background mice. During gallbladder and bile duct development, Sox17 was expressed at the distal edge of the gallbladder primordium. In the Sox17+/− B6 embryos, gallbladder epithelia were hypoplastic, and some were detached from the luminal wall, leading to bile duct stenosis or atresia. The shredding of the gallbladder epithelia is probably caused by cell-autonomous defects in proliferation and maintenance of the Sox17+/− gallbladder/bile duct epithelia. Our results suggest that Sox17 plays a dosage-dependent function in the morphogenesis and maturation of gallbladder and bile duct epithelia during the late-organogenic stages, highlighting a novel entry point to the understanding of the etiology and pathogenesis of human congenital biliary atresia.

In mouse embryogenesis, Sry is transiently activated in a center-to-pole wavelike manner along the anteroposterior (AP) axis of developing XY gonads. However, the mechanism and significance of the center-to-pole expansion of testis initiation pathways downstream of Sry expression remain unclear. Here we demonstrate that FGF9 can act as a diffusible conductor for a poleward expansion of tubulogenic programs at early phases of testis differentiation. In XY genital ridge cultures of anterior, middle and posterior segments at 11.0-11.25 days post-coitum, male-specific activation of Sry and its target gene, Sox9, was still observed in both anterior and posterior pole segments despite their isolation from the central domain. However, high-level Sox9 expression was not maintained, resulting in the failure of testis cord organization in most pole segments. A reconstruction experiment using ROSA:lacZ middle segments showed rescue of the tubulogenic defect in the poles without any appreciable contribution of lacZ-positive gonadal parenchyma cells. A partition culture assay also showed a possible contribution of soluble/diffusible factors secreted from the gonadal center domain to proper tubulogenesis in the poles. Among various signaling factors, Fgf9 expression was significantly lower in both anterior and posterior pole segments than in the central domain. The supportive role of the central domain could be substituted by exogenous FGF9 supply, whereas reduction of Wnt4 activity did not rescue the tubulogenesis defect in the pole segments. These observations imply that center-to-pole FGF9 diffusion directs a poleward expansion of testiculogenic programs along the AP axis of developing XY gonads.

In early-organogenesis-stage mouse embryos, the posteroventral foregut endoderm adjacent to the heart tube gives rise to liver, ventral pancreas and gallbladder. Hepatic and pancreatic primordia become specified in the posterior segment of the ventral foregut endoderm at early somite stages. The mechanisms for demarcating gallbladder and bile duct primordium, however, are poorly understood. Here, we demonstrate that the gallbladder and bile duct progenitors are specified in the paired lateral endoderm domains outside the heart field at almost the same timing as hepatic and pancreatic induction. In the anterior definitive endoderm, Sox17 reactivation occurs in a certain population within the most lateral domains posterolateral to the anterior intestinal portal (AIP) lip on both the left and right sides. During foregut formation, the paired Sox17-positive domains expand ventromedially to merge in the midline of the AIP lip and become localized between the liver and pancreatic primordia. In Sox17-null embryos, these lateral domains are missing, resulting in a complete loss of the gallbladder/bile-duct structure. Chimera analyses revealed that Sox17-null endoderm cells in the posteroventral foregut do not display any gallbladder/bile-duct molecular characters. Our findings show that Sox17 functions cell-autonomously to specify gallbladder/bile-duct in the mouse embryo.

During mouse gastrulation, primordial germ cells (PGCs) become clustered at the base of the allantois and move caudally into the hindgut endoderm before entering the genital ridges. The precise roles of endoderm tissues in PGC migration, however, remain unclear. By using Sox17 mutants with a specific endoderm deficiency, we provide direct evidence for the crucial role of hindgut expansion in directing proper PGC migration. In Sox17-null embryos, PGCs normally colonize in the allantois and then a small front-row population of PGCs moves properly into the most posterior gut endoderm. Defective hindgut expansion, however, causes the failure of further lateral PGC movement, resulting in the immobilization of PGCs in the hindgut entrance at the later stages. In contrast, the majority of the remaining PGCs moves into the visceral endoderm layer, but relocate outside of the embryonic gut domain. This leads to a scattering of PGCs in the extraembryonic yolk sac endoderm. This aberrant migration of Sox17-null PGCs can be rescued by the supply of wildtype hindgut cells in chimeric embryos. Therefore, these data indicate that hindgut morphogenic movement is crucial for directing PGC movement toward the embryonic gut side, but not for their relocation from the mesoderm into the endoderm.

In mammals, the Y-linked sex-determining gene Srycell-autonomously promotes Sertoli cell differentiation from bipotential supporting cell precursors through SRY-box containing gene 9 (Sox9),leading to testis formation. Without Sry action, the supporting cells differentiate into granulosa cells, resulting in ovarian development. However,how Sry acts spatiotemporally to switch supporting cells from the female to the male pathway is poorly understood. We created a novel transgenic mouse line bearing an inducible Sry transgene under the control of the Hsp70.3 promoter. Analysis of these mice demonstrated that the ability of Sry to induce testis development is limited to approximately 11.0-11.25 dpc, corresponding to a time window of only 6 hours after the normal onset of Sry expression in XY gonads. If Sry was activated after 11.3 dpc, Sox9 activation was not maintained, resulting in ovarian development. This time window is delimited by the ability to engage the high-FGF9/low-WNT4 signaling states required for Sertoli cell establishment and cord organization. Our results indicate the overarching importance of Sry action in the initial 6-hour phase for the female-to-male switching of FGF9/WNT4 signaling patterns.

In studies of male reproductive toxicity, measuring daily sperm production is a quite important criterion. However, the accuracy of the values measured by the basic protocol is still controversial. In order to enhance the homogeneity of countable testicular sperm/spermatid heads, this report introduces a new enzymatic method with a subsequent detergent treatment. The testis of rat was firstly homogenized in phosphate-buffered saline. The homogenate (buffer mix) was then treated with collagenase and trypsin, and then sodium dodecyl sulfate (SDS) was added to produce detergent-resistant sperm/spermatid heads (detergent mix). After examination by hemocytometer, the coefficient of variation (CV) of the number of sperm/spermatid heads was compared with that obtained from the buffer mix. In addition, a MicroCell chamber was applied to the examination, and the CV was compared with other cases. In both examinations, homogeneity was improved by the detergent mix preparation. Counting with the hemocytometer showed an increased number of sperm/spermatid heads compared with that of the buffer mix (P

The effects of mono(2-ethylhexyl) phthalate (MEHP) on 21-day-old C57Bl/6N mice and their Sertoli cell cultures were studied. Mice were given a single dose of 800 mg/kg MEHP by oral gavage and sacrificed 24 h later. At the same time, testes were harvested from another batch of mice for Sertoli cell cultures. Cultures were subsequently exposed to 0, 1, and 100 nmol/ml MEHP for 0, 3, 6, 12, and 24 h. An antivimentin antibody was used to detect intermediate filament changes in Sertoli cells. Meanwhile, detection of preapoptotic signals and presence of apoptotic cells were done using annexin V–FITC (fluorescein isothiocyanate) and TUNEL (deoxynucleotidyltransferase-mediated dUTP nick end labeling) analyses, respectively. In vivo results showed a correlation between the increase in TUNEL-positive cells and the vimentin disruption in treated mice. Toluidine blue staining of the Sertoli cell cultures showed the increased number and size of vacuoles in Sertoli cell cytoplasm. Vimentin immunohistochemistry showed gradual disappearance of vimentin in Sertoli cell cultures as time and dose increased. Some Sertoli cells were found to be annexin V–FITC positive, but no TUNEL-positive cells were found. Taken together, these results show that the appearance of vacuoles and the vimentin disappearance caused by MEHP in the Sertoli cells are related with each other and can be observed in relation to time. This can be used as an indicator of the loss of mechanical support for spermatogenic cells, which in the end causes apoptosis of spermatogenic cells.

Knock-in embryonic stem (ES) cells, in which GFP or lacZ was expressed from the endogenous mouse vasa homolog ( Mvh ), which is specifically expressed in differentiating germ cells, were used to visualize germ cell production during in vitro differentiation. The appearance of MVH-positive germ cells depended on embryoid body formation and was greatly enhanced by the inductive effects of bone morphogenic protein 4-producing cells. The ES-derived MVH-positive cells could participate in spermatogenesis when transplanted into reconstituted testicular tubules, demonstrating that ES cells can produce functional germ cells in vitro . In vitro germ cell differentiation provides a paradigm for studying the molecular basis of germ line establishment, as well as for developing new approaches to reproductive engineering.

Germ cell-specific ATP-dependent RNA helicase, the product of the mouse vasa homolog (Mvh), has been shown to play an essential role in the development of the male germ cell. In male Mvh knockout mice, premeiotic germ cells arrest at the zygotene stage. To investigate the role of MVH protein in the progression of meiosis, we searched for genes encoding partners that interact with MVH in testicular germ cells. Using the yeast two-hybrid system, we found that MVH interacts with mouse RanBPM, a Ran-GTP binding protein involved in microtubule nucleation. RanBPM is predominantly expressed in the testis, especially in maturating spermatocytes. Within the cell, RanBPM and MVH are closely associated with perinuclear RNA-protein complexes and chromatoid bodies. The interaction of MVH with RanBPM points to a functional relationship between translational regulation and the microtubule nucleation during meiosis. Mol. Reprod. Dev. 66: 1-7, 2004.

Many vasa homologue genes to Drosophila vasa have been isolated in various animal species. They provide specific molecular probes to analyze the establishment and the differentiation of germ cell lineage. In mammals, the expression of VASA protein becomes detectable in PGCs at the late migrating stage. Interestingly, during spermatogenesis the intracellular localization of VASA protein is closely associated with the chromatoid body.

To demonstrate the cellular and subcellular localization of mouse vasa homologue protein during germ cell development, specific antibody was raised against the full-length MVH protein. The immunohistochemical analyses demonstrated that MVH protein was exclusively expressed in primordial germ cells just after their colonization of embryonic gonads and in germ cells undergoing gametogenic processes until the post-meiotic stage in both males and females. The co-culture of EG cells with gonadal somatic cells indicated inductive MVH expression caused by an intercellular interaction with gonadal somatic cells. In adult testis, MVH protein was localized in the cytoplasm of spermatogenic cells, including chromatoid bodies in spermatids, known to be a perinuclear nuage structure which includes polar granules that contain VASA protein in Drosophila.

Hsc70t is a member of the Hsp70 family of genes and is constitutively expressed after meiosis in mouse spermatogenesis. Immunohistochemistry and in situ hybridization techniques were used to examine the precise localization of the Hsc70t product during the various stages of spermatogenesis. A rabbit antiserum raised againstthe mouse Hsc70t-lacZ fusion protein detected the Hsc70t protein in the late spermatid-enriched fraction after two-dimensional Western blot analyses. On histological sections, the protein appears in the cytoplasm of spermatids as they progress from step 9 to the final step of spermatogenesis. An antisense RNA probe generated from the 3' untranslated region of Hsc70t cDNA detected Hsc70t mRNA in late round spermatids from step 7 onward with the signal disappearing in spermatids at step 15. Thus, Hsc70t mRNA first appears after meiosis in haploid cells but is not translated effectively until these cells progress to the transcriptionally inactive stage which coincides with chromatin condensation. These results establish that the synthesis of Hsc70t protein is under strict translational control.

In mammalian sex determination, SRY directly upregulates the expression of SOX9, the master regulatory transcription factor in Sertoli cell differentiation, leading to testis formation. Without SRY action, the bipotential gonadal cells become pre-granulosa cells, which results in ovarian follicle development. When, where and how pre-granulosa cells are determined to differentiate into developing ovaries, however, remains unclear. By monitoring SRY-dependent SOX9 inducibility (SDSI) in an Sry -inducible mouse system, we were able to identify spatiotemporal changes in the sexual bipotentiality/plasticity of ovarian somatic cells throughout life. The early pre-granulosa cells maintain the SDSI until 11.5 d.p.c., after which most pre-granulosa cells rapidly lose this ability by 12.0 d.p.c. Unexpectedly, we found a subpopulation of the pre-granulosa cells near the mesonephric tissue that continuously retains SDSI throughout fetal and early postnatal stages. After birth, these SDSI-positive pre-granulosa cells contribute to the initial round of folliculogenesis by the secondary follicle stage. In experimental sex reversal of 13.5-d.p.c. ovaries grafted into adult male nude mice, the differentiated granulosa cells re-acquire the SDSI before other signs of masculinization. Our data provide direct evidence of an unexpectedly high sexual heterogeneity of granulosa cells in developing mouse ovaries in a stage- and region-specific manner. Discovery of such sexually bipotential granulosa cells provides a novel entry point to the understanding of masculinization in various cases of XX disorders of sexual development in mammalian ovaries.

Sox7, -17 and -18 constitute the Sox subgroup F (SoxF) of HMG box transcription factor genes, which all are co-expressed in developing vascular endothelial cells in mice. Here we characterized cardiovascular phenotypes of Sox17/Sox18-double and Sox17-single null embryos during early-somite stages. Whole-mount PECAM staining demonstrated the aberrant heart looping, enlarged cardinal vein and mild defects in anterior dorsal aorta formation in Sox17 single-null embryos. The Sox17/Sox18 double-null embryos showed more severe defects in formation of anterior dorsal aorta and head/cervical microvasculature, and in some cases, aberrant differentiation of endocardial cells and defective fusion of the endocardial tube. However, the posterior dorsal aorta and allantoic microvasculature was properly formed in all of the Sox17/Sox18 double-null embryos. The anomalies in both anterior dorsal aorta and head/cervical vasculature corresponded with the weak Sox7 expression sites. This suggests the region-specific redundant activities of three SoxF members along the anteroposterior axis of embryonic vascular network.

The sex-determining region of Chr Y (Sry) gene is sufficient to induce testis formation and the subsequent male development of internal and external genitalia in chromosomally female mice and humans. In XX sex-reversed males,such as XX/Sry-transgenic (XX/Sry) mice, however, testicular germ cells always disappear soon after birth because of germ cell-autonomous defects. Therefore,it remains unclear whether or not Sry alone is sufficient to induce a fully functional testicular soma capable of supporting complete spermatogenesis in the XX body. Here, we demonstrate that the testicular somatic environment of XX/Sry males is defective in supporting the later phases of spermatogenesis. Spermatogonial transplantation analyses using XX/Sry male mice revealed that donor XY spermatogonia are capable of proliferating, of entering meiosis and of differentiating to the round-spermatid stage. XY-donor-derived round spermatids, however, were frequently detached from the XX/Sry seminiferous epithelia and underwent cell death, resulting in severe deficiency of elongated spermatid stages. By contrast, immature XY seminiferous tubule segments transplanted under XX/Sry testis capsules clearly displayed proper differentiation into elongated spermatids in the transplanted XY-donor tubules. Microarray analysis of seminiferous tubules isolated from XX/Sry testes confirmed the missing expression of several Y-linked genes and the alterations in the expression profile of genes associated with spermiogenesis. Therefore, our findings indicate dysfunction of the somatic tubule components,probably Sertoli cells, of XX/Sry testes, highlighting the idea that Sry alone is insufficient to induce a fully functional Sertoli cell in XX mice.

To obtain a reliable molecular probe to trace the origin of germ cell lineages in birds, we isolated a chicken homolog (Cvh) to vasa gene (vas), which plays an essential role in germline formation in Drosophila. We demonstrate the germline-specific expression of CVH protein throughout all stages of development. Immunohistochemical analyses using specific antibody raised against CVH protein indicated that CVH protein was localized in cytoplasm of germ cells ranging from presumptive primordial germ cells (PGCs) in uterine-stage embryos to spermatids and oocytes in adult gonads. During the early cleavages, CVH protein was restrictively localized in the basal portion of the cleavage furrow. About 30 CVH-expressing cells were scattered in the central zone of the area pellucida at stage X, later 45-60 cells were found in the hypoblast layer and subsequently 200-250 positive cells were found anteriorly in the germinal crescent due to morphogenetic movement. Furthermore, in the oocytes, CVH protein was predominantly localized in granulofibrillar structures surrounding the mitochondrial cloud and spectrin protein- enriched structure, indicating that the CVH-containing cytoplasmic structure is the precursory germ plasm in the chicken. These results strongly suggest that the chicken germline is determined by maternally inherited factors in the germ plasm.

The anatomical location of testes in mammals ranges from a location close to that observed in the embryo to a lower position usually involving a pendant scrotum. In scrotal mammals, the abdominal position of the cryptorchid testis, which elevates its temperature, is detrimental to spermatogenesis and causes infertility. Spermatocytes are sensitive but late spermatids are relatively resistant to thermal stress suggesting that the latter might be protected in some way. In general, most organisms express Hsp70 proteins, which play a crucial role in the protection of cells against thermal stress. We have found previously that the Hsc70t protein, a member of the Hsp70 family of proteins, is constitutively expressed in the late spermatids of mice. Here, we have utilized immunohistochemistry with anti-mouse Hsc70t antiserum to examine the expression of the spermatid-specific Hsp70 antigen in the testes of several mammalian species with different degrees of testes migration. Our data indicate that the antigen is conserved in the mammals including marsupials. We also examined whether antigens of Hsp70-related proteins were expressed in non-mammalian vertebrates including not only homoiothermal but also poikilothermal animals. The spermatid-specific Hsp70 antigens were not detectable in the testes of the animals examined. From results of immunohistochemistry with BRM22 monoclonal antibody which reacts broadly with Hsp70 family proteins, however, we revealed constitutive expression of antigens of Hsp70-related proteins in spermatogenic cells of the vertebrates. These results suggest that the expression of spermatid-specific Hsp70 protein may be involved in the developmental pathway during spermiogenesis in mammals rather than in thermotolerance.

In mouse sex differentiation, SRY promotes Sertoli cell differentiation via SOX9 action, resulting in testis formation. SRY/SOX9 also initiates various testis-specific morphogenic events including glycogenesis in pre-Sertoli cells, suggesting the importance of glucose storage for certain SRY/SOX9-downstream events in gonadal sex determination. However, it remains unclear which cell types and what molecular/cellular events require sex-dimorphic high-energy metabolic rate. Here we show that the establishment of SOX9 activation itself is a metabolically active process with sex-dimorphic high-energy requirements in gonadal sex differentiation. The glucose-deprivation and metabolic rescue experiments using genital ridge cultures of the XY/XX-wildtype and XX/Sry transgenic embryos demonstrated that, among the various somatic cell types, pre-Sertoli cells are the most sensitive to glucose starvation despite the differences between XX/Sry and XY genotypes. Moreover, our data showed that, in developing pre-Sertoli cells, the high-glucose metabolic state is required for the establishment of SOX9 expression through an ECM (extracellular matrix)-mediated feed-forward pathway. In contrast, the expression of SRY, SF1/Ad4Bp, GATA4 and WT1, as well as initiation of early SOX9 expression, is properly maintained in the glucose-deprived condition. Therefore, our results imply the metabolic importance of the high-glucose condition for the establishment of SOX9 activation in testis differentiation.

The gonad as well as the reproductive tracts, kidney, and adrenal cortex are derived from the intermediate mesoderm. In addition, the intermediate mesoderm forms the mesonephros. Although the mesonephros is the source of certain testicular cell types, its contribution to gonad formation through expression of growth factors is largely unknown. Here, we examined the expression profiles of FGF9 in the developing mesonephros of chick embryos at sexually indifferent stages, and found that the expression domain is adjacent to the gonadal primordium. Moreover, FGFR3 (FGF receptor 3) showed a strong expression in the gonadal primordium. Next, we examined the functions of FGF signal during gonadal development with misexpressed FGF9. Interestingly, misexpression of FGF9 led to gonadal expansion through stimulation of cell proliferation. In contrast, treatment with a chemical inhibitor for FGFR decreased cell proliferation and resulted in reduction of the gonadal size. Simultaneously, the treatment resulted in reduction of gonadal marker gene expression. Our study demonstrated that FGF expressed in the developing mesonephros is involved in the development of the gonad at the sexually indifferent stages through stimulation of gonadal cell proliferation and gonadal marker gene expression.