Testis Development and Ultrastructural Features During Spermatogenesis in Cultured Small Yellow Croaker,Larimichthys polyactis

The small yellow croaker Larimichthys polyactis is an economically important marine fish in Northeast Asia.Currently,its natural resources are threatened by overfishing and environmental pollution.Therefore,research on the reproductive system of the fish is crucial.Here,we studied the testis development and ultrastructural features of spermatogenesis in cultured L.polyactis using anatomical,histological,and ultrastructural techniques.A pair of testes,consisting of a central sperm duct and radial seminiferous lobules,were observed.The reproduction cycle of testes can be divided into stages I–VI.March to May was confirmed as the breeding season for male L.polyactis,while April is the ideal period for artificial breeding.The male L.polyactis can attain sexual maturity within 1 year.The spermatogenesis of L.polyactis comprised spermatogonium,spermatocyte,spermatid,and mature spermatozoon.The morphology of spermatogenic cells changed obviously during spermiogenesis,including nuclear shaping,midpiece and flagellum formation.The mature sperms consist of an ellipsoidal head,a short midpiece,and a long flagellum.The anterior of the head with a kidney-shaped nucleus can be distinguished.The midpiece is located posterior to the head and includes four to six spherical mitochondria.The flagellum has irregular lateral fins.The testis of L.polyactis is an unrestricted lobular type,with cystic spermatogenesis,type II spermiogenesis,and type II spermatozoa.These features are highly similar to those of other Sciaenid species.Our findings provide useful insights into the mechanism underlying testis development and spermatogenesis of L.polyactis,which can facilitate the artificial breeding of this species.

Pitx2 suppression at meiotic stages associates with seasonal inhibition of testis development in Rattus norvegicus caraco

The bicoid-related transcription factor 2(Pitx2)plays a crucial role in the development of many organs and tissues by affecting the mitotic cell cycle.Postnatal testis development is related to mitosis and meiosis in mul-tiple cell types,but the role of Pitx2 gene in seasonal inhibition of testicular development remains unknown in rodents.We analyzed PITX2 protein and Pitx2 mRNA expression features using both laboratory and wild male Rattus norvegicus caraco.In postnatal testicle of laboratory colony,we found that PITX2 was expressed in Leydig cells,pachytene spermatocytes,round spermatids,and elongating spermatids rather than spermatogonia and lep-totene/zygotene spermatocytes.Pitx2b expression significantly increased along with the occurrence of pachytene spermatocytes and round spermatids,while decreased along with the processes of elongated spermatids.In wild male rats with similar testes weight,a significantly suppressed Pitx2b expression occurred with an active meiotic stage in the inhibited testes in autumn and winter,compared with the normally developing testes in spring and summer.These results indicate that Pitx2b expression suppression plays a crucial role in the seasonal inhibition of testis development.

Tetrabromobisphenol A‑bis(2,3-dibromopropyl ether)impairs Postnatal Testis Development in Mice:The Microtubule Cytoskeleton as a Sensitive Target

Tetrabromobisphenol A-bis(2,3-dibromopropyl ether)(TBBPA-BDBPE),a widely used flame retardant,has been frequently detected in various environmental compartments,but its health hazard remains largely unknown.Here,we investigated the adverse effects of TBBPA-BDBPE(50 and 1000μg/kg/day)on postnatal testis development in CD-1 mice and the underlying mechanism.Following the first week of maternal exposure,neonatal mice in the high-dose group exhibited reduced seminiferous tubule area,fewer Sertoli cells and germ cells,and damaged microtubules in Sertoli cells;even microtubule damage was also observed in the low-dose group.When exposure extended to adulthood,male offspring in the high-dose group presented more remarkable alterations in reproductive parameters,including reduced sperm count;in the low-dose group,microtubule damage was also observable,along with blood−testis barrier impairment.Further molecular docking analysis and tubulin polymerization assay indicated that TBBPA-BDBPE could interact with tubulin and disrupt its polymerization.Moreover,we observed attenuated microtubules in mouse Sertoli cells in vitro(TM4)following TBBPABDBPE treatment,suggesting that TBBPA-BDBPE impaired testis development possibly by interfering with tubulin dynamics.This study not only highlights the male reproductive hazard of TBBPA-BDBPE but also greatly improved the understanding of the molecular mechanism for male reproductive toxicity of chemicals.

Dynamic transcriptome profiles and novel markers in bovine spermatogenesis revealed by single-cell sequencing

Testicular development is an important biological process in male and requires interaction between the male germ cells and somatic cells.However,the mechanisms of testicular development in livestock,particularly in cattle,are poorly understood.Furthermore,cellular heterogeneity hinders the profiling of different cell types at different developmental stages.In this study,we first performed a single-cell transcriptomic study of the bovine testis development during puberty by using 10×genomics single-cell RNA sequencing(scRNA-seq).By collecting the scRNA-seq data from 11,083 cells from prepubertal and pubertal bovine testes,a high-resolution scRNA-seq atlas was described,identifying 9 somatic and 13 spermatogenic clusters.We also distinguished several stage-specific marker genes for bovine germ cells and somatic cells,such as GRAF2 and MORC1 for SSC(spermatogonial stem cells),HJURP and TCF19 for differentiating spermatogonia,ARSE for immature Sertoli,CLEC12B for mature Sertoli,LOC112441470 for Leydig.In conclusion,we have examined the transcription levels and constructed the single-cell developmental maps of germ cells and somatic cells during testicular development in Angus cattle.The datasets provided new insights into spermatogenesis and testicular somatic cell development in cattle.

Expression of a novel alternative transcript of the novel retinal pigment epithelial cell gene NORPEG in human testes

Aim： To identify a novel alternative transcript of the novel retinal pigment epithelial cell gene （NORPEG） expressed in the human testis. Methods： A human testis cDNA microarray was established and hybridized with cDNA probes from human fetal testes, adult testes and human spermatozoa. Differentially expressed clones were sequenced and analyzed. One of these clones was a short transcript of NORPEG which we proceeded to analyze by RT-PCR. Results： The novel short alternative transcript of NORPEG was isolated and named sNORPEG. It was 3486 bp in length and contained a 2952-bp open reading frame, encoding a 110.4-kDa protein of 983 amino acids. Amino acid sequence analysis showed that the sNORPEG protein contains six ankyrin repeats and two coiled-coil domains. It shares a high homology with the NORPEG and ankycorbin proteins in both its sequence and motifs. Blasting the human genome database localized sNORPEG to human chromosome 5pl 3.2-13.3. Expression profiles showed that sNORPEG was expressed in human fetal testes, adult testes and spermatozoa. Moreover, sNORPEG was found to be ubiquitously expressed in human tissues. Conclusion： sNORPEG is expressed in different developmental stages of the testis and encodes a protein that may have roles in human testis development and spermatogenesis. （Asian J Androl 2005 Sep; 7： 277-288）