High lead level in the Alps in XIXth century, learning from the analysis of 138 historical hair stands

Analysis of hair is known to provide useful information about environmental and toxic exposures. Very little historical use has been made of this type of investigation. Here we study 138 human hair samples from 19th century in France. In order to examine the potential association between contamination and historical health impacts, we characterized contamination by 33 elements in a set of hair strands sampled during the last quarter of the 19th century in the Savoy region of France. After a selected washing step on 138 hair strands conserved at the Museum National d'Histoire Naturelle in Paris (France), we assessed the presence of inorganics by ICP/MS, and lead level was higher than values reported in literature. We then compared concentrations and distributions between women and men, sampling locations and crossing gender and geographical origin. Hair lead level was high throughout Savoy at the end of the 19th century: significantly higher for people living in towns or industrial valleys, and lower for those of countryside and mountains areas. Environmental and economic changes (industrialization and urbanization with water adduction and leaded paints), living habits (kitchenware, cosmetics, wine, and tobacco), and local features (mines exploitation, railroad development, and industrialized narrow valleys) could be envisaged for explaining the level of lead contamination. In the same period, the two main industrial valleys of Savoy (Maurienne and Tarentaise) had high rates of endemic goiter and cretinism and among the highest hair lead levels. Other lines of evidence will need to be explore to investigate a possible link between historical Pb exposure and goiter in the study area.

P–055 Methylation dynamics of the sperm epigenome after chemotherapy: a case study

Study question

What is the evolution of the sperm epigenome after chemotherapy in a patient with testicular cancer (TC)?

Summary answer

These new data on epigenetic recovery profil after TC are useful tools for counseling and reassuring these patients.

What is known already

An important issue for young men affected TC is how TC and its treatment will affect, transiently or permanently, their future reproductive health. The consequences of cancer treatment on the sperm epigenome during the recovery periods are topical issues of ascendant significance as epigenetic modifications to the paternal genome may have deleterious effects on the offspring.

Study design, size, duration

Here we report the epigenomic profiling of frozen sperm from a TC patient before and after the treatment at different time points (6, 9, 12 and 24 months) by using RRBS analysis (Reduced representation bisulfite sequencing method).

Participants/materials, setting, methods

A testicular tumor (testicular germ cell tumor) was diagnosed in a 30 years old patient. A cryopreservation of spermatozoa was proposed before treatment.Semen samples were obtained 2 times before treatment and 4 times after treatment (6, 9, 12 and 24 months following the initiation of treatment).

Main results and the role of chance

Upon collection, sampling after chemotherapy ranged from 0,6 to 4,2 million per sperm straw between 6 and 24 months after the treatment, always increasing.

In order to capture the direct effect of the treatment on the methylation changes, the DMR detection has been operated between pre-chemotherapy samples (pair-wise) and the time point of 6 months. Among the 179 hqDMRs, 74 are differentially methylated between the PreCT and PostCT6m samples (16 hyper- and 68 hypo-methylated) associated with 49 DMGs (15 hyper- and 34 hypo-methylated).

We further sub-clustered the 74 hqDMRs between PreCT and PostCT6m into 6 patterns, 3 hyper- and 3 hypo-methylated. Briefly, patterns P1 and P4 include hqDMRs that quickly get back to their pre-treatment methylation status just after 9th months onwards. Patterns P2 and P5 include hqDMRs that slowly get back to their pre-treatment methylation status between 12 and 24 months after treatment. Patterns P3 and P6 include hqDMRs that remain hyper- or hypo-methylated even after 24 months.

We have intersected the genes (DMGs) associated with the detected hqDMRs with those known to be important or expressed during embryogenesis. We thus detected that 7 hyper-methylated and 6 hypomethylated DMGs were involved (or expressed) during embryonic / fetal development.

Limitations, reasons for caution

This study involves a single patient. As the patient made no major changes in his personal way of life, we hypothesized that sperm parameter variations may be attributable to the BEP treatment.

Wider implications of the findings: The altered methylated status of those DMGs important for early development might modify their expression pattern and thus affect their function during key stages of embryogenesis leading to potential developmental disorders. It is important to notice that among the 110 DMGs none of them correspond to known imprinted genes.

Trial registration number

Not applicable

Granulosa cells provide elimination of apoptotic oocytes through unconventional autophagy-assisted phagocytosis

STUDY QUESTION

Do human granulosa cells (GCs) ingest and destroy apoptotic oocytes?

SUMMARY ANSWER

Somatic GCs ingest and destroy apoptotic oocytes and other apoptotic substrates through unconventional autophagy-assisted phagocytosis.

WHAT IS KNOWN ALREADY

Most (99%) ovarian germ cells undergo apoptosis through follicular atresia. The mode of cleaning of atretic follicles from the ovary is unclear. Ovarian GCs share striking similarities with testicular Sertoli cells with respect to their origin and function. Somatic Sertoli cells are responsible for the elimination of apoptotic spermatogenic cells through unconventional autophagy-assisted phagocytosis.

STUDY DESIGN, SIZE, DURATION

Human GCs were tested for the ability to ingest and destroy the apoptotic oocytes and other apoptotic substrates. A systemic study of the main phagocytosis steps has been performed at different time points after loading of apoptotic substrates into the GC.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary cultures of GC retrieved following controlled ovarian stimulation of five women for IVF/ICSI and a human granulosa KGN cell line were incubated with different apoptotic substrates: oocytes which underwent spontaneous apoptosis during the cultivation of immature germ cells for IVF/ICSI; apoptotic KGN cells; and apoptotic membranes from rat retinas. Cultured GC were analyzed for the presence of specific molecular markers characteristic of different steps of phagocytic and autophagy machineries by immunocytochemistry, confocal microscopy, transmission electron microscopy and western blotting, before and after loading with apoptotic substrates.

MAIN RESULTS AND THE ROLE OF CHANCE

Incubation of human GC with apoptotic substrates resulted in their translocation in cell cytoplasm, concomitant with activation of the phagocytosis receptor c-mer proto-oncogene tyrosine kinase MERTK (P < 0.001), clumping of motor molecule myosin II, recruitment of autophagy proteins: autophagy-related protein 5 (ATG5), autophagy-related protein 6 (Beclin1) and the rise of a membrane form of microtubule-associated protein 1 light chain 3 (LC3-II) protein. Ingestion of apoptotic substrates was accompanied by increased expression of the lysosomal protease Cathepsin D (P < 0.001), and a rise of lysosomes in the GCs, as assessed by different techniques. The level of autophagy adaptor, sequestosome 1/p62 (p62) protein remained unchanged.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The number of patients described here is limited. Also the dependence of phagocytosis on reproductive hormone status of patients should be analyzed.

WIDER IMPLICATIONS OF THE FINDINGS

Removal of apoptotic oocytes by surrounding GC seems likely to be a physiological mechanism involved in follicular atresia. Proper functioning of this mechanism may be a new strategy for the treatment of ovarian dysfunctions associated with an imbalance in content of germ cells in the ovaries, such as premature ovarian failure and polycystic ovary syndrome.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by Rennes Metropole (AIS 2015) and Agence de BioMédecine. This work was supported by funding from Université de Rennes1, Institut National de la Santé et de la Recherche Médicale (INSERM) and CHU de Rennes. A.B. is funded in part by the program Actions Concertées Interpasteuriennes (ACIP) and a research grant from the European Society of Pediatric Endocrinology. This work is supported by the Agence Nationale de la Recherche Grants ANR-17-CE14-0038 and ANR-10-LABX-73. The authors declare no competing interests.

RNA profiling of human testicular cells identifies syntenic lncRNAs associated with spermatogenesis

STUDY QUESTION

Is the noncoding transcriptional landscape during spermatogenesis conserved between human and rodents?

SUMMARY ANSWER

We identified a core group of 113 long noncoding RNAs (lncRNAs) and 20 novel genes dynamically and syntenically transcribed during spermatogenesis.

WHAT IS KNOWN ALREADY

Spermatogenesis is a complex differentiation process driven by a tightly regulated and highly specific gene expression program. Recently, several studies in various species have established that a large proportion of known lncRNAs are preferentially expressed during meiosis and spermiogenesis in a testis-specific manner.

STUDY DESIGN, SIZE, DURATION

To further investigate lncRNA expression in human spermatogenesis, we carried out a cross-species RNA profiling study using isolated testicular cells.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human testes were obtained from post-mortem donors (N = 8, 51 years old on average) or from prostate cancer patients with no hormonal treatment (N = 9, 80 years old on average) and only patients with full spermatogenesis were used to prepare enriched populations of spermatocytes, spermatids, Leydig cells, peritubular cells and Sertoli cells. To minimize potential biases linked to inter-patient variations, RNAs from two or three donors were pooled prior to RNA-sequencing (paired-end, strand-specific). Resulting reads were mapped to the human genome, allowing for assembly and quantification of corresponding transcripts.

MAIN RESULTS AND THE ROLE OF CHANCE

Our RNA-sequencing analysis of pools of isolated human testicular cells enabled us to reconstruct over 25 000 transcripts. Among them we identified thousands of lncRNAs, as well as many previously unidentified genes (novel unannotated transcripts) that share many properties of lncRNAs. Of note is that although noncoding genes showed much lower synteny than protein-coding ones, a significant fraction of syntenic lncRNAs displayed conserved expression during spermatogenesis.

LARGE SCALE DATA

Raw data files (fastq) and a searchable table (.xlss) containing information on genomic features and expression data for all refined transcripts have been submitted to the NCBI Gene Expression Omnibus under accession number GSE74896.

LIMITATIONS, REASONS FOR CAUTION

Isolation procedures may alter the physiological state of testicular cells, especially for somatic cells, leading to substantial changes at the transcriptome level. We therefore cross-validated our findings with three previously published transcriptomic analyses of human spermatogenesis. Despite the use of stringent filtration criteria, i.e. expression cut-off of at least three fragments per kilobase of exon model per million reads mapped, fold-change of at least three and false discovery rate adjusted P-values of less than <1%, the possibility of assembly artifacts and false-positive transcripts cannot be fully ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

For the first time, this study has led to the identification of a large number of conserved germline-associated lncRNAs that are potentially important for spermatogenesis and sexual reproduction. In addition to further substantiating the basis of the human testicular physiology, our study provides new candidate genes for male infertility of genetic origin. This is likely to be relevant for identifying interesting diagnostic and prognostic biomarkers and also potential novel therapeutic targets for male contraception.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by l'Institut national de la santé et de la recherche médicale (Inserm); l'Université de Rennes 1; l'Ecole des hautes études en santé publique (EHESP); INERIS-STORM to B.J. [N 10028NN]; Rennes Métropole 'Défis scientifiques émergents' to F.C (2011) and A.D.R (2013). The authors have no competing financial interests.

Update on the cellular and molecular aspects of cystic fibrosis transmembrane conductance regulator (CFTR) and male fertility

CFTR protein regulates electrolyte and fluid transport in almost all tissues with exocrine function, including male reproductive tract. Mutation of CFTR gene causes cystic fibrosis (CF), which affects the function of several organs, and impairs male fertility. The role of CFTR protein in different compartments of male reproductive tract (testis, epididymis, sperm) as well as an impact of CFTR mutation(s) on male fertility phenotype is discussed in relation with the choice of optimal technique for Assisted Reproductive Techniques (ART) management.

Parallel assessment of the effects of bisphenol A and several of its analogs on the adult human testis

STUDY QUESTION

Are bisphenol A (BPA) and BPA analogs (BPA-A) safe for male human reproductive function?

SUMMARY ANSWER

The endocrine function of human testes explants [assessed by measuring testosterone and insulin-like factor 3 (INSL3)] was impacted by exposure of the human adult testis explants to BPA/BPA-A.

WHAT IS KNOWN ALREADY

The few epidemiologic studies performed suggest that bisphenols have potential endocrine disruptive properties, but they did not identify clear and direct patterns of endocrine disruption.

STUDY DESIGN, SIZE, DURATION

Adult human testis explants in culture were exposed to BPA and the analogs bisphenol F (BPF), bisphenol S (BPS), bisphenol E (BPE), bisphenol B (BPB) and bisphenol A diglycidyl ether (BADGE) at 10-9-10-5 M for 24 or 48 h.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Human adult testes were obtained from prostate cancer patients who had no hormone therapy, or from multiorgan donors. After ex vivo exposure to the investigated bisphenols, the measured outcomes were related to histopathology (gross morphology and germ cell viability determined by anti-caspase three immunohistochemistry), and the levels of testosterone, INSL3 and inhibin B were measured using immunoassays. The levels of mRNA encoding key enzymes of bisphenol biotransformation were investigated by quantitative PCR: UGT2B15 UDP (glucuronosyltransferase two family, polypeptide B15), GUSB (glucuronidase beta), SULT1A1 and 3 (sulfotransferase family 1 A member 1 and 3) and STS (steroid sulfatase).

MAIN RESULTS AND THE ROLE OF CHANCE

A significant dose-dependent inhibition was found between testosterone levels measured in the culture medium and concentrations of BPA (P = 0.00778 at 24 h and P = 0.0291 at 48 h), BPE (P = 0.039) and BPF (P = 0.00663). The observed BPA and BPA-A-induced inhibition of testosterone production varied according to duration of exposure and BPA/BPA-A concentrations. BPA (10-9 M; P < 0.05), BPB (10-9 M; P < 0.05), BPS (10-9 and 10-8 M; P < 0.05) and BADGE (10-5 M; P < 0.05) increased Leydig cell INSL3 production. By contrast, BPE dose dependently inhibited INSL3 (P = 0.0372). Conversely, Sertoli cell function (inhibin B) and germ cell viability were not significantly affected by either bisphenols.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Environmental compounds cannot be deliberately administered to men, justifying the use of an ex vivo approach. A relatively low number of testes samples were available for analysis (n = 3, except for testosterone secretion with n = 5). The active concentrations of BPA and BPA-A used in the study were higher than those found in human biological fluids.

WIDER IMPLICATIONS OF THE FINDINGS

Under our experimental conditions, direct exposure to BPA or BPA-A can result in endocrine disturbance in the adult human testis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Inserm (Institut National de la Santé et de la Recherche Médicale), EHESP-School of Public Health, University of Rennes1, by grants from the Agence Nationale de la Recherche (ANR; grant#ANR-13-CESA-0012-03 NEWPLAST) and Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail (ANSES; grant#EST-2010/2/046 (BPATESTIS)). All authors declare they have no current or potential competing financial interests.

Meiotic Genes Are Enriched in Regions of Reduced Archaic Ancestry

About 1-6% of the genetic ancestry of modern humans today originates from admixture with archaic humans. It has recently been shown that autosomal genomic regions with a reduced proportion of Neanderthal and Denisovan ancestries (NA and DA) are significantly enriched in genes that are more expressed in testis than in other tissues. To determine whether a cellular segregation pattern would exist, we combined maps of archaic introgression with a cross-analysis of three transcriptomic datasets deciphering the transcriptional landscape of human gonadal cell types. We reveal that the regions deficient in both NA and DA contain a significant enrichment of genes transcribed in meiotic germ cells. The interbreeding of anatomically modern humans with archaic humans may have introduced archaic-derived alleles that contributed to genetic incompatibilities affecting meiosis that were subsequently purged by natural selection.

Genome-wide identification of Sox8-, and Sox9-dependent genes during early post-natal testis development in the mouse

The SOX8 and SOX9 transcription factors are involved in, among others, sex differentiation, male gonad development and adult maintenance of spermatogenesis. Sox8(-/-) mice lacking Sox9 in Sertoli cells fail to form testis cords and cannot establish spermatogenesis. Although genetic and histological data show an important role for these transcription factors in regulating spermatogenesis, it is not clear which genes depend upon them at a genome-wide level. To identify transcripts that respond to the absence of Sox8 in all cells and Sox9 in Sertoli cells we measured mRNA concentrations in testicular samples from mice at 0, 6 and 18 days post-partum. In total, 621 and 629 transcripts were found at decreased or increased levels, respectively, at different time points in the mutant as compared to the control samples. These mRNAs were categorized as preferentially expressed in Sertoli cells or germ cells using data obtained with male and female gonad samples and enriched testicular cell populations. Five candidate genes were validated at the protein level. Furthermore, we identified putative direct SOX8 and SOX9 target genes by integrating predicted SOX-binding sites present in potential regulatory regions upstream of the transcription start site. Finally, we used protein network data to gain insight into the effects on regulatory interactions that occur when Sox8 and Sox9 are absent in developing Sertoli cells. The integration of testicular samples with enriched Sertoli cells, germ cells and female gonads enabled us to broadly distinguish transcripts directly affected in Sertoli cells from others that respond to secondary events in testicular cell types. Thus, combined RNA profiling signals, motif predictions and network data identified putative SOX8/SOX9 target genes in Sertoli cells and yielded insight into regulatory interactions that depend upon these transcription factors. In addition, our results will facilitate the interpretation of genome-wide in vivo SOX8 and SOX9 DNA binding data.

Proteome analysis and genome-wide regulatory motif prediction identify novel potentially sex-hormone regulated proteins in rat efferent ducts

The efferent ducts are a series of tubules that conduct sperm from the rete testis to the epididymis. They absorb most fluid and proteins originating from the rete testis during concentration of spermatozoa prior to their entry into the epididymis. Proteome analysis of micro-dissected efferent duct samples from adult rats was combined with genome-wide computational prediction of conserved hormone response elements to identify factors likely regulated by oestrogens and androgens. We identified 165 proteins and found subsets of the promoters controlling their corresponding genes to contain androgen- and oestrogen response elements (ARE/EREs) at similar frequencies. Moreover, EREs were significantly enriched among the loci identified compared with their genome-wide occurrence. The expression and localization of Anxa6, Ckb, Krt19, Park7, Pdzk1 and Tpt1 in the efferent ducts and other related hormone controlled tissues was further validated at the RNA or protein level. This study identifies many novel proteins predicted to play roles in sperm maturation and male fertility and provides significant computational evidence that the efferent ducts express genes transcriptionally controlled by sex hormones.

Antiviral responses of human Leydig cells to mumps virus infection or poly I:C stimulation

BACKGROUND

The immuno-privileged status of the testis is essential to the maintenance of its functions, and innate immunity is likely to play a key role in limiting harmful viral infections, as demonstrated in the rat. In men mumps virus infects Leydig cells and has deleterious effects on testosterone production and spermatogenesis. The aim of this study was to test whether mumps virus infection of isolated human Leydig cells was associated with an inhibition of their innate antiviral defences.

METHODS

Leydig cell production of mRNA and protein for interferons (IFNs) and of three antiviral proteins—2′5′ oligoadenylate synthetase (2′5′OAS), double-stranded RNA-activated protein kinase (PKR) and MxA—was investigated, in the absence or presence of mumps virus or viral stimuli including poly I:C, a mimetic of RNA viruses replication product.

RESULTS

Stimulated or not, human Leydig cells appeared unable to produce routinely detectable IFNs α, β and γ. Although the level of PKR remained unchanged after stimulation, the expression of 2′5′OAS and MxA was enhanced following either mumps virus or poly I:C exposure (P < 0.05 versus control).

CONCLUSIONS

Overall, our results demonstrate that mumps virus replication in human Leydig cells is not associated with a specific inhibition of IFNs or 2′5′OAS, MxA and PKR production and that these cells display relatively weak endogenous antiviral abilities, as opposed to their rat counterparts.

Nouvelles avancées dans l’étude de l’influence de l’environnement sur la santé reproductive masculine

BACKGROUND

An important part of the research effort on male reproductive health focus on two important questions: on the one side, that of the temporal deterioration of male reproductive health and, on the other head, that of the influence of exposure to environmental chemicals during intra-uterine life on health during childhood and adulthood. The concepts on endocrine disruption and testicular dysgenesis syndrome make a link between these two questions.

METHODS

This work examines knowledge cumulated over the last couple of years concerning geographical and temporal variations in male reproductive health and the testicular dysgenesis syndrome. Recent results concerning the concept of endocrine disruption and on the environmental influences on male reproduction are presented, as well as on the transgenerational effects on environmental factors on the health of male children.

CONCLUSIONS

Based on clinical and epidemiological data, and with the use of in vitro animal models as well as observations in wildlife, research in this field has enabled progress in the elucidation of mechanisms of action and characterization of environmental influences on male reproductive health.

Human testis in organotypic culture: application for basic or clinical research

BACKGROUND

Over recent decades, recurring efforts have been devoted to developing testicular cell or tissue cultures for basic and clinical research. However, there remains much confusion, particularly concerning the fate of human germ cells in culture.

OBJECTIVE

To reassess the status of human testicular cell types as well as the ability of germ cells to divide and differentiate in organotypic culture.

METHODS

Human testicular fragments were maintained for 2 weeks in culture. The viability and functionality of testicular cells were assessed using light and electronic microscopy, apoptotic cell labelling, 5-bromo-2'-deoxyuridine (BrdU) incorporation, immunohistochemistry and quantitative PCR against specific cell markers.

RESULTS

A gradual loss of meiotic and post-meiotic germ cells occurred throughout the culture period, irrespective of the presence of gonadotrophins. However, all germ cell types remained traceable for up to 16 days, some still dividing and differentiating at a rate compatible with the in vivo situation. Good maintenance of the general architecture of the explants associated with clearly quantifiable levels of several somatic cell markers was observed.

CONCLUSION

Although this culture model is clearly unsuitable for preparing germ cells for therapeutic purposes, it does represent a most valuable tool for testing the effects of biological and chemical agents on testicular tissue.

Transferrin overexpression alters testicular function in aged mice

Many studies have shown a correlation between transferrin (Tf) concentration and sperm yield in several mammalian species. We have used transgenic mice expressing human Tf (hTf) to investigate if overexpression of Tf increases the efficiency of mouse spermatogenesis. We demonstrated that a 36% increase of Tf does not ameliorate the efficiency of mouse spermatogenesis but on the contrary resulted in a 36% decrease of testis sperm reserves. Tf overexpression had no effect on testicular determination and development, however testicular function of these transgenic mice was affected in an age-dependent manner. At 16 months of age, testicular and epididymal weights were significantly reduced. While spermatogenesis was qualitatively normal, testicular functions were perturbed. In fact, testosterone rate after human chorionic gonadotropin (hCG) stimulation was lower in Tf overexpressing mice. Intratesticular concentration of estradiol-17beta was increased and fluid accumulation after ligation of rete testis was more abundant in these transgenic mice. Surprisingly, we found that endogenous Tf levels were also increased in Tf overexpressing mice and we demonstrated for the first time that Tf may serve to upregulate its own expression in testis. Collectively, our data show that Tf overexpression has negative effects on testicular function and that Tf levels require strict regulation in the testis.

Expression, Regulation, and Immunolocalization of Putative Homeodomain Transcription Factor 1 (PHTF1) in Rodent Epididymis: Evidence for a Novel Form Resulting from Proteolytic Cleavage1

PHTF1 is an 84-86-kDa membrane protein found in the endoplasmic reticulum of male germ cells in rodents. There are no evident signs of PHTF1 in the spermatozoa released into the lumen of the seminiferous tubules but PHTF1 is present in the epididymal epithelium. Characterization of the epididymal Phtf1 messenger by Northern blot and reverse transcription-PCR identified a 3-kilobase transcript in the epididymis, similar to that previously reported in the testis. The transcript is present in the proximal part of the epididymis and it appears when the rats reach 4 wk of age. Through immunofluorescence analysis, PHTF1 was localized in the principal cells of the initial segment and the caput epididymis. Colocalization with different markers indicated PHTF1 is in the endoplasmic reticulum saccules applied to the trans face of the Golgi system. Western blot analyses revealed a shorter form of the protein--about 56-kDa versus the 84-kDa form found in the testis. Using the canine epididymal cell line CIM 20, transfected by N- and C-terminal myc-tagged PHTF1, we demonstrated that the 56-kDa epididymal form could result from proteolytical processing.

Viruses in Semen and Male Genital Tissues - Consequences for the Reproductive System and Therapeutic Perspectives

Sexually transmissible diseases such as AIDS have renewed the attention paid to viruses capable of infecting the male genital tract. The presence of viruses at this level may not only lead to their transmission and spread via semen but may also impact on male fertility and/or represent a potential cause of genital organ cancers. This review summarizes the currently available data on the various viruses identified in the human semen and male reproductive tract, their distribution in tissues and fluids, their possible cell targets and the functional consequences of their infectivity on the reproductive and endocrine systems. The use of medically assisted reproduction as a therapeutic tool in serodiscordant couples, as well as treatment strategies that need to be developed in order to eradicate these viruses from the male genital tract, are discussed.

GermOnline, a cross-species community knowledgebase on germ cell differentiation

GermOnline provides information and microarray expression data for genes involved in mitosis and meiosis, gamete formation and germ line development across species. The database has been developed, and is being curated and updated, by life scientists in cooperation with bioinformaticists. Information is contributed through an online form using free text, images and the controlled vocabulary developed by the GeneOntology Consortium. Authors provide up to three references in support of their contribution. The database is governed by an international board of scientists to ensure a standardized data format and the highest quality of GermOnline's information content. Release 2.0 provides exclusive access to microarray expression data from Saccharomyces cerevisiae and Rattus norvegicus, as well as curated information on approximately 700 genes from various organisms. The locus report pages include links to external databases that contain relevant annotation, microarray expression and proteome data. Conversely, the Saccharomyces Genome Database (SGD), S.cerevisiae GeneDB and Swiss-Prot link to the budding yeast section of GermOnline from their respective locus pages. GermOnline, a fully operational prototype subject-oriented knowledgebase designed for community annotation and array data visualization, is accessible at http://www.germonline.org. The target audience includes researchers who work on mitotic cell division, meiosis, gametogenesis, germ line development, human reproductive health and comparative genomics.

Experimental inoculation of the adult rat testis with Sendai virus: effect on testicular morphology and leukocyte population

BACKGROUND

Surprisingly little is known about the interactions between viruses and the male uro-genital tract. These are important, as viral testicular orchitis, induced by mumps or human immunodeficiency virus (HIV) infection for example, can lead to sterility. Moreover, semen is an essential vector in the propagation of sexually transmissible viral diseases. Here, we studied the effects of testicular infection with Sendai virus, a virus related to mumps virus, on the cellular distribution of viral particles and on testicular morphology, with particular attention to the testicular leukocyte population.

METHODS

At 5, 9, 11 or 24 h post-injection of Sendai virus through the scrotum, the testes were fixed for morphological and immunohistological studies. Localization of virus particles and numeration of leukocytes were performed using specific antibodies and morphological criteria.

RESULTS

As early as 5 h post-injection, a rapid and massive infiltration of leukocytes was observed in the interstitial tissue. The peritubular cell layer and the most external part of the basal portion of the seminiferous tubules were altered. The virus was diffusely located within the interstitial tissue 9 h following the injection whereas, after 24 h, viral proteins were restricted to the cytoplasm of infiltrated leukocytes. The number of leukocytes increased with time post-injection. Thus, 24 h post-injection, CD3+ T-cell number was 3-fold higher, ED1+ monocyte number was 4-fold higher and polynuclear cell number was 600-fold higher than in the control testes (P<0.001 all observations). In contrast, the population of resident macrophages was unaffected by Sendai virus.

CONCLUSIONS

Testicular viral infection causes inflammation including rapid recruitment of leukocytes. The experiments presented here provide a model for further studies on the etiopathology of viral orchitis, in particular that caused by mumps virus.

Phtf1 is an integral membrane protein localized in an endoplasmic reticulum domain in maturing male germ cells

Phtf1 is a gene evolutionarily conserved from Drosophila to human that is abundantly expressed in testis. In adult rat, transcripts were abundant in germinal meiotic and postmeiotic cells. Phtf1-specific antibodies revealed weak activity in a juxtanuclear region of early pachytene spermatocytes. Labeling progressively extended to the entire cytoplasm of step 2-3 spermatids, became intense from step 4, and persisted until the end of spermiogenesis, when it was eliminated in the residual bodies. Phtf1 displayed the properties of an integral membrane protein. In transfected cells and haploid cells of rat seminiferous epithelium, it colocalized with ER markers (calnexin and calmegin, respectively). By using both ER and Golgi markers (TGN-38, p58), we were able to show that, in pachytene spermatocytes and in Golgi phase spermatids, phtf1 labeled a region neighboring the cis-Golgi that probably corresponded to the peripheral Golgi region. Phtf1 staining was not related to beta-COP, AP1, or AP2 aptamers, indicating that it was not transported between Golgi saccules or between the Golgi complex and plasma membrane. However, aptamer labeling showed that chlatrin vesicles could be engaged in a new traffic route, raising the possibility of a meiotic proacrosomal vesicle origin. Colocalization between phtf1 and calmegin decreased during the acrosomal phase. During the maturation phase, phtf1 was able to identify different ER domains, as described previously for the peripheral Golgi region. Phtf1 provides a potential new marker for Golgi modifications as well as for many of the obscure transformations undergone by the endoplasmic reticulum. It could help to elucidate the morphogenic events connected with the transformation of spermatogenic cells.

MAGE-A4, a germ cell specific marker, is expressed differentially in testicular tumors

BACKGROUND

Testicular germ cell tumors are the most common malignancy in young males, and the frequency of these tumors has risen dramatically over the last century. Because it is known that the MAGE genes are expressed in a wide variety of tumors but are expressed only in the mitotic spermatogonia (germ cells) and in the primary spermatocytes in the normal testis, the authors screened the expression of MAGE-A4 in a panel of testicular germ cell tumors.

METHODS

Monoclonal antibody 57B raised against MAGE-A4 was tested immunohistochemically on 12 classical seminomas, 5 anaplastic seminomas, 10 various specimens of nonseminomatous germ cell tumors (NSGCTs), 2 combined tumors containing seminoma components, 1 Sertoli cell tumor, 2 Leydig cell tumors, and 15 carcinomas in situ (CIS). In addition, monoclonal antibody 57B was tested on embryonic gonad (age 8 weeks) and fetal gonads (ages 15 weeks, 17 weeks, and 28 weeks).

RESULTS

Classical seminomas uniformly and specifically expressed MAGE-A4 compared with anaplastic seminomas and NSGCTs, which were negative for this antigen. Specific expression of MAGE-A4 also was seen in subpopulations of CIS cells, providing additional evidence for heterogeneity of the phenotype of these cells, in which it is believed that differentiation and proliferation generate seminomas and NSGCTs. Finally, MAGE-A4 was expressed in the fetal precursors of the stem germ cells from 17 weeks of gestation onward, in accordance the fact that CIS can arise from prespermatogonia in the fetus.

CONCLUSIONS

MAGE-A4 can be considered a potential specific marker for normal premeiotic germ cells and germ cell tumors and can be used to characterize classical seminomas.

Proteome analysis of rat spermatogonia: reinvestigation of stathmin spatio-temporal expression within the testis

Stathmin is a protein known to be involved in various cell processes including cell proliferation and differentiation. It has already been described in the testis but its recent identification using a proteomic approach in mitotic spermatogenetic stem cells named spermatogonia (Guillaume et al., 2000) has lead us to reinvestigate its expression within the testis. Stathmin and its mRNAs were studied in isolated cells by Western and Northern blots and in situ using immunohistochemistry. We demonstrated that stathmin is indeed expressed in spermatogonia, and that it is also intensively expressed in the meiotic spermatocytes and in the first generations of spermatids. Furthermore, we showed aggregations of the protein in the cytoplasm of the later generations of spermatids preceding its elimination at the time of spermiation. Our Northern blots reveal the presence of two stathmin transcripts of 1.1 and 3.2 kb within the testis from the fetal stage onwards, in spermatogonia, spermatocytes, and spermatids. However, the 3.2 kb RNA transcript was barely detectable in the spermatids. Stathmin expression is known to be associated with microtubule dynamics. Therefore, its expression in the germ line is most probably related to the extremely complex structural cellular rearrangements occurring in germ cells during spermatogenesis. However, the exact role of stathmin and the reason of the existence of two transcripts in the male germ lineage awaits further investigation.

Cellular distribution of translationally controlled tumor protein in rat and human testes

In a recent proteomic study we identified 53 spermatogonial proteins among which was the translationally controlled tumor protein (TCTP). This is a protein previously reported as being implicated in proliferation events in normal and tumoral tissues that had never previously been seen in the testis. The present study was aimed at establishing the complete cellular distribution of TCTP and its transcript and the ontogenetic expression of this gene within the testis. Using an immunohistochemistry technique, an intense TCTP signal was detected in gonocytes (the prespermatogonia) in the fetal rat testis and in spermatogonia within adult human and neonatal and adult rat testes. Meiotic spermatocytes and postmeiotic haploid spermatids were also strongly immunostained in a stage-dependent manner in human and rat testes. In addition, different levels of TCTP expression were also observed in the testicular somatic cells, with strong expression in Leydig cells and peritubular cells, and weak expression in Sertoli cells. Western and Northern blot analyses confirmed the presence of TCTP at all ages studied, with higher levels of RNA expression at 9 and 20 d postpartum, when spermatogonia and primary spermatocytes represent the highest proportion of germ cells: it was also confirmed that TCTP is present in all populations of isolated testicular cells. A transcript of 0.85 kb corresponding to TCTP, was expressed at all ages studied. This transcript was found to be expressed strongly in spermatogonia, somewhat less in isolated Leydig, resident macrophage, peritubular and Sertoli cells, weakly in the primary spermatocytes but not at all in spermatids. Interestingly, in the latter, a different transcript of 1.1 kb was present. The same 1.1 kb transcript appeared in testis extracts from 35 days postpartum onwards, corresponding to an age when spermatids accumulate within the tubules. Of note is that resident macrophages were found to express both the 0.85 and the 1.1 kb transcripts. We conclude that the strong expression of TCTP in spermatogonia makes it highly likely that the protein plays a significant role in spermatogenesis.

Viruses in the mammalian male genital tract and their effects on the reproductive system

This review describes the various viruses identified in the semen and reproductive tracts of mammals (including humans), their distribution in tissues and fluids, their possible cell targets, and the functional consequences of their infectivity on the reproductive and endocrine systems. The consequences of these viral infections on the reproductive tract and semen can be extremely serious in terms of organ integrity, development of pathological and cancerous processes, and transmission of diseases. Furthermore, of essential importance is the fact that viral infection of the testicular cells may result not only in changes in testicular function, a serious risk for the fertility and general health of the individual (such as a fall in testosteronemia leading to cachexia), but also in the possible transmission of virus-induced mutations to subsequent generations. In addition to providing an exhaustive account of the data available in these domains, this review focuses attention on the fact that the interface between endocrinology and virology has so far been poorly explored, particularly when major health, social and economical problems are posed. Our conclusions highlight the research strategies that need to be developed. Progress in all these domains is essential for the development of new treatment strategies to eradicate viruses and to correct the virus-induced dysfunction of the endocrine system.

Testis hormone-sensitive lipase expression in spermatids is governed by a short promoter in transgenic mice

A testicular form of hormone-sensitive lipase (HSL(tes)), a triacylglycerol lipase, and cholesterol esterase, is expressed in male germ cells. Northern blot analysis showed HSL(tes) mRNA expression in early spermatids. Immunolocalization of the protein in human and rodent seminiferous tubules indicated that the highest level of expression occurred in elongated spermatids. We have previously shown that 0.5 kilobase pairs of the human HSL(tes) promoter directs testis-specific expression of a chloramphenicol acetyltransferase reporter gene in transgenic mice and determined regions binding nuclear proteins expressed in testis but not in liver (Blaise, R., Grober, J., Rouet, P., Tavernier, G., Daegelen, D., and Langin, D. (1999) J. Biol. Chem. 274, 9327-9334). Mutation of a SRY/Sox-binding site in one of the regions did not impair in vivo testis-specific expression of the reporter gene. Further transgenic analyses established that 95 base pairs upstream of the transcription start site were sufficient for correct testis expression. In gel retardation assays using early spermatid nuclear extracts, a germ cell-specific DNA-protein interaction was mapped between -46 and -29 base pairs. The DNA binding nuclear protein showed properties of zinc finger transcription factors. Mutation of the region abolished reporter gene activity in transgenic mice, showing that it is necessary for testis expression of HSL(tes).

Regulatory influence of germ cells on sertoli cell function in the pre-pubertal rat after acute irradiation of the testis

While germ cell regulation of Sertoli cells has been extensively explored in adult rats in vivo, in contrast, very little is known about germ cell influence on Sertoli cell function at the time when spermatogenesis begins and develops. In the present study various Sertoli cell parameters (number, testicular androgen binding protein (ABP) and testin, serum inhibin-B and, indirectly, follicle-stimulating hormone (FSH)) were investigated after the exposure of 19-day-old rats to a low dose of 3 Grays of gamma-rays. Differentiated spermatogonia were the primary testicular targets of the gamma-rays, which resulted in progressive maturation depletion, sequentially and reversibly affecting all germ cell classes. Testicular weight declined to a nadir when pachytene spermatocytes and spermatids were depleted from the seminiferous epithelium and complete or near complete recovery of spermatogenesis and testicular weight was observed at the end of the experiment. Blood levels of FSH and ABP were normal during the first 11 days after irradiation, when spermatogonia and early spermatocytes were depleted. While the number of Sertoli cells was not significantly affected by the irradiation, from days 11-66 after gamma-irradiation, ABP production declined and FSH levels increased when pachytene spermatocytes and spermatids were depleted and the recovery of these parameters was only observed when spermatogenesis was fully restored. Comparison of the pattern of change in serum levels of inhibin-B and testicular levels of testin and of germ cell numbers strongly suggest a relationship between the disappearance of spermatocytes and spermatids from the seminiferous epithelium and the decrease in levels of inhibin-B and increase in levels of testin from 7 to 36 days post-irradiation. Levels of testin and inhibin-B were restored before spermatogenesis had totally returned to normal. In conclusion, this in vivo study shows that pre-pubertal Sertoli cell function is under the complex control of various germ cell classes. This control presents clear differences when compared with that previously observed in adult animals and depends on the Sertoli cell parameter of interest, as well as on the germ cell type.

Expression and regulation of the CXC-chemokines, GRO/KC and IP-10/mob-1 in rat seminiferous tubules

Testicular inflammation is classically observed in the pathogenesis of viral and bacterial infection or tumoral invasion. In these situations, leukocyte infiltration is generally encountered. GRO/KC (growth-related oncogene) and IP-10/mob-1 (IFN-gamma-inducible protein) are two CXC-chemokines which attract neutrophils and activated T lymphocytes, respectively, have been studied for their ability to participate to testicular inflammation (orchitis). In the present work, using Northern blot and immunocytochemistry, we aimed to investigate whether GRO/KC and IP-10/mob-1 are produced within the seminiferous tubules of the testis and if these chemokines are induced by a number of pro-inflammatory cytokines and lipopolysaccharides (LPS). Our results show that GRO/KC and IP-10/mob-1 mRNAs were never found in germ cells, whether they were stimulated or not. In contrast, GRO/KC mRNA was expressed by isolated peritubular cells when stimulated by interleukin-1 alpha and beta (IL-1 alpha and IL-1 beta) or LPS and to a lesser extent by tumor necrosis factor-alpha (TNF-alpha) and by Sertoli cells when the latter were stimulated by rIL-alpha and rIL-1 beta and to a lesser extent by TNF-alpha and LPS. Moreover, IP10/mob-1 transcripts were strongly induced in peritubular cells by interferon-alpha (IFN-alpha) and IFN-gamma, whereas, in isolated Sertoli cells, INF-alpha and TNF-alpha were the only potent inducers. The kinetics of GRO/KC and IP-10/mob-1 mRNA expression by peritubular and Sertoli cells (significant stimulation as early as 1 hour and 4 hours post-exposure to the stimuli, respectively) are compatible with the hypothesis of a rapid mobilisation of these cells in an inflammatory process. Moreover, the dose-dependent effects of pro-inflammatory cytokines to induce a chemokine response were compatible with a high sensitivity of peritubular and Sertoli cells in orchitis. In conclusion, this present study shows that 2 CXC-chemokines, GRO/KC and IP10/mob-1, are produced by testicular somatic cells of seminiferous tubules, strongly indicating a likely role of these chemokines in the accumulation of neutrophils and T lymphocytes during orchitis of various origins.

Involvement of Bcl-2 family proteins in germ cell apoptosis during testicular development in the rat and pro-survival effect of stem cell factor on germ cells in vitro

A large part of germ cells die apoptotically during testicular development in rodents. In the present study, a wave of germ cell apoptosis was observed between days 10 and 30 of postnatal life by in situ 3'-end labeling and DNA fragmentation analysis. To explore the potential involvement of Bcl-2 family members in this process, the expression and localization of some Bcl-2 family proteins (Bcl-2, Bcl-xL, Bcl-w, Bak, Bax, and Bad) and p53 were analyzed during testicular development in the rat by Western blotting and immunohistochemistry. The dynamic changes in the expression profiles of Bcl-2 family proteins are consistent with a model in which germ cells are primed for apoptosis during the first cycle of spermatogenesis by de novo expression of the death effectors Bax and Bad in a p53-dependent manner and these proteins are prevented from triggering further apoptosis after the first spermatogenic cycle has been set up by anti-apoptotic Bcl-2 family proteins Bcl-xL and Bcl-w. To examine whether the pro-survival effect of stem cell factor (SCF) on germ cells in vitro is mediated by Bcl-2 family proteins, the correlation between the pro-survival effect of SCF on germ cells and the expression of the above-mentioned apoptosis-related gene products in the seminiferous tubules at stage XII of the epithelial cycle were also investigated using a tubular culture system. The data suggest that SCF supports germ cell survival during spermatogenesis by up-regulating pro-survival Bcl-2 family proteins, Bcl-w and Bcl-xL, and down-regulating pro-apoptosis Bcl-2 family proteins, e.g. Bax.

GATA-1 is a potential repressor of anti-Müllerian hormone expression during the establishment of puberty in the mouse

Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance (MIS), is one of the earliest and best-known markers of Sertoli cell differentiation and is expressed until around puberty. The present study is aimed at the better understanding of the molecular pathways involved in testicular development and establishment of adult functions with regards to AMH regulation. We found, within the mouse AMH promoter, putative GATA motifs (A/T)GATA(A/G), known to be specifically bound by members of the GATA transcription factor family. We then carried out RNase protection assays and immunohistochemical techniques aimed at comparing precisely the chronological expression patterns of AMH and GATA-1, this latter being expressed in the testis after birth. Using both approaches we found an inverse and close relationship between AMH and GATA-1 mRNA and protein expression during the pre-pubertal period. These results allowed us to define a transitory 4-5-day period, starting from 3 dpp when both proteins are heterogeneously expressed in Sertoli cells and showed that the appearance of GATA-1 is associated with the decrease of AMH expression in these cells. Furthermore DNA-protein interaction in in vitro studies showed first that GATA-1 binds with various affinities on sites found in the AMH promoter and second that the proximity of the two strongest affinity sites leads to a synergistic binding effect. Altogether, the present study suggests that GATA-1 participates in AMH gene repression during the pre-pubertal period.

Expression and regulation of the CC-chemokine monocyte chemoattractant protein-1 in rat testicular cells in primary culture

Testicular inflammation is classically observed in pathogenesis caused by infectious agents, environmental toxins, trauma, or autoimmune reactions and can lead to transitory or even permanent sterility. In these situations, a leukocyte infiltration is generally encountered. Macrophage inflammatory proteins (MIP)-1alpha and -1beta and monocyte chemoattractant protein-1 (MCP-1) are CC-chemokines involved in macrophage and lymphocyte chemoattraction. In the present study, using reverse transcription-polymerase chain reaction, Northern blot, and a specific ELISA, we investigated whether or not these chemokines are present within the testis and whether they are induced by a number of proinflammatory cytokines and lipopolysaccharides (LPS). MIP-1alpha and MIP-1beta were not detected in Sertoli cells, germ cells, peritubular cells, or Leydig cells. In contrast, MCP-1 mRNA and protein were found to be expressed by control isolated peritubular cells, and expression was markedly stimulated by interleukin-1alpha and-1beta (IL-1alpha and IL-1beta), tumor necrosis factor alpha (TNF-alpha), interferon gamma, and LPS. Leydig cells expressed MCP-1 when stimulated by IL-1beta. In contrast, MCP-1 was not found to be produced by Sertoli cells or germ cells as established by Northern blot and ELISA techniques. The kinetics of MCP-1 production by peritubular cells, as demonstrated by expression as early as 8 h poststimulation, are compatible with there being a rapid mobilization of these cells and this chemokine in an inflammatory process. Moreover, MCP-1 production by peritubular cells after half-maximal stimulation by LPS, TNF-alpha, and IL-1beta (2 pg/ml-0.9 ng/ml) is also compatible with the physiologic concentrations of the proinflammatory cytokines generally found in an inflammatory site. It is concluded that MCP-1 is produced by Leydig cells and peritubular cells and that it could be involved in the mobilization and migration of leukocytes observed during testicular inflammation.

Bcl-w forms complexes with Bax and Bak, and elevated ratios of Bax/Bcl-w and Bak/Bcl-w correspond to spermatogonial and spermatocyte apoptosis in the testis

Bcl-w, a prosurvival member of the Bcl-2 family, is essential for spermatogenesis. However, the mechanisms by which Bcl-w participates in the regulation of apoptosis in the testis are largely unknown. To explore the potential role of Bcl-w in the regulation of apoptosis in the testis, the expression of Bcl-w mRNA and protein during testicular development and spermatogenesis, the dimerization with the proapoptosis members of the Bcl-2 family, and the responses to hormonal stimulation in vitro and apoptosis-inducing signals in vivo were investigated. Both Bcl-w mRNA and protein were detected in Sertoli cells, spermatogonia, and spermatocytes, as well as in Leydig cells. The steady-state levels of Bcl-w mRNA and protein were much higher in Sertoli cells than in spermatogonia and spermatocytes. In the adult rat testis, both Bcl-w mRNA and protein in Sertoli cells displayed a stage-specific expression pattern. Bcl-w could form complexes with Bax and Bak but not with Bad. Bax and Bak were immunohistochemically localized to the same cell types as Bcl-w, but with higher expression levels in spermatocytes and spermatogonia than in Sertoli cells. FSH could up-regulate Bcl-w mRNA levels in the seminiferous tubules cultured in vitro, whereas no effect was observed when testosterone was applied. Three animal models that display spermatogonial apoptosis induced by blockade of stem cell factor/c-kit interaction by a function-blocking anti-c-kit antibody, spermatocyte apoptosis induced by methoxyacetic acid, and apoptosis of spermatogonia, spermatocytes, and spermatids induced by testosterone withdrawal after ethylene dimethane sulfonate treatment were employed to check the changes of Bcl-w, Bax, and Bak protein levels during apoptosis of specific germ cells. In all three models, the ratios of Bax/Bcl-w and Bak/Bcl-w were significantly elevated. The present study suggests that Bcl-w is an important prosurvival factor of Sertoli cells, spermatogonia, and spermatocytes and participates in the regulation of apoptosis by binding proapoptotic factors Bax and Bak. The ratios of Bax/Bcl-w and Bak/Bcl-w may be decisive for the survival of Sertoli cells, spermatogonia, and spermatocytes.

Leukemia inhibitory factor expression and regulation within the testis

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine known to control the proliferation and survival of stem cells including primordial germ cells and gonocytes. This led us to study the origin and regulation of testicular LIF. The LIF transcript was detected in the rat testis by RT-PCR from 13.5 days postcoitum until adulthood. LIF expression was investigated further in vitro in seven different highly purified testicular cell populations using RT-PCR and bioassays combined with neutralization experiments. LIF was found to be produced by peritubular cells and, to a much lesser extent, by the other testicular somatic cell types. No LIF was detected in meiotic and postmeiotic germ cell-conditioned medium, and only low levels of LIF were detected in spermatogonia-conditioned medium. Large amounts of bioactive LIF were measured in testicular lymph. While LIF production was greatly enhanced in presence of serum, lipopolysaccharide, and TNFalpha further increased this production in peritubular and Sertoli cells, and human CG enhanced Leydig cell LIF production. In conclusion, peritubular cells are the principal source of testicular LIF, probably accounting for its high concentration in the lymph. Given the proliferative effect of LIF on immature germ cells, we suggest that peritubular LIF plays an important role in the regulation of testicular function.

Source, catabolism and role of the tetrapeptide N-acetyl-ser-asp-lys-Pro within the testis

The tetrapeptide N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (AcSDKP) is a natural regulator of hematopoietic stem cell proliferation. The present study was aimed at investigating the presence and the role of AcSDKP in rat testis. Specific immunoreactivity was always observed in the interstitial tissue at all stages of testicular development and in elongated spermatids at 45 days of age and in adults. In accordance with the interstitial labeling, high AcSDKP levels were detected in Leydig cell and testicular macrophage culture media and cell extracts, as well as in the testicular interstitial fluid (TIF). Much lower concentrations were found in peritubular cells and Sertoli cells cultures, whereas very low concentrations were present in cultured spermatocytes and spermatids. In contrast to the slight degradation rate of AcSDKP observed in the spermatocyte and spermatid culture media, no catabolism of the peptide was seen in testicular somatic cell culture medium. Furthermore, the degradation rate of AcSDKP was much lower in TIF than in peripheral blood plasma. Despite the very strong evidence indicating that Leydig cells and testicular macrophages produce AcSDKP, the selective destruction of these cells did not result in any change in AcSDKP levels in TIF or in plasma. This suggests a compensatory mechanism ensuring constant levels of the peptide in TIF when interstitial cells are absent. Finally, in vitro, in the presence of AcSDKP, significantly more [(3)H]thymidine incorporation was found in A spermatogonia. In conclusion, this study establishes the presence of very high concentrations of AcSDKP in rat testis and demonstrates its Leydig cell and testicular macrophage origin. The presence of AcSDKP in the TIF and its stimulatory effect on thymidine incorporation in spermatogonia very strongly suggest its implication in the paracrine control of spermatogenesis.

Seasonal variations in sex steroids and male sexual characteristics in Scyliorhinus canicula

Concentrations of testosterone, progesterone, Delta4-androstenedione, dihydrotestosterone, 11-ketotestosterone, estrone, estradiol-17beta, 5alpha-androstane, 3alpha, 17beta-diol, and 17alpha-hydroxy, 20beta-dihydroprogesterone were determined by radioimmunoassays in the blood plasma and testicular homogenates of Scyliorhinus canicula. Samples were collected almost every month for 27 months. The weights and sizes of reproductive organs and sperm reserves were also measured over the same period. Quantitatively, testosterone was the principal steroid present. Testicular and epididymal weights, sperm reserves, and clasper size varied throughout the year, but not always in a synchronous fashion. Most of the testicular steroids had an annual peak, generally in February, except for progesterone. The plasma concentrations of progesterone, Delta4-androstenedione, and androgens presented various degrees of fluctuation over the year, but were not synchronized: maxima occurred during autumn-winter for androgens and progesterone, during spring for Delta4-androstenedione. Thus, various aspects of S. canicula reproductive function appear to be influenced by season, the sea temperature being, most probably, a major determinant in this respect.

Distribution of thimet oligopeptidase (E.C. 3.4.24.15) in human and rat testes

Thimet oligopeptidase (TOP:E.C. 3.4.24.15) is a thiol sensitive metalloendopeptidase which is widely distributed and active in most tissues including testis, brain and pituitary. In the median eminence it is postulated to play a role in the degradation of GnRH released from the hypothalamus and thus to modulate LH levels. In the rat and human, the testis is the richest source of TOP activity with levels 3- to 5-fold higher than that of the brain. In order to define the exact localisation of this enzyme within the rat and human testis, the distribution of TOP in the developing and adult gonad was examined in situ and in isolated cells by immunohistochemistry, western blotting and northern blotting analysis. Ontogeny studies have demonstrated that TOP is detectable by western blotting from 9 days with levels of expression increasing with the age of the animal. Immunolocalisation of the protein in the interstitium was positive from 9 days onwards but was negative within the seminiferous tubules before 35 days of age, whereas TOP mRNA was not detected within the testis until 35 days of age with subsequent stable expression levels up to 90 days. In the adult rat testis, a strong TOP immunoreactivity was observed within seminiferous tubules, in elongating and elongated spermatids and residual bodies. In the interstitial compartment, immunoreactivity was also observed in Leydig cells and throughout the interstitial space. Western blot analyses confirmed the distribution of expression observed using immunochemistry, however Leydig cells display a lower signal than expected from the immunohistochemical data. Northern hybridization showed that the transcript is present in pachytene spermatocytes, early spermatids, and residual bodies, whereas its presence was not observed in Leydig cells probably due to very low levels of expression of the message. Analyses of various human tissue extracts showed that the testis displays the highest levels of TOP mRNA, with immunohistochemical experiments revealing that, as in the rat, the protein is principally expressed in elongated spermatids/residual bodies, and in Leydig cells. It is concluded that in the human and rat testes, TOP is highly expressed, in particular in post-meiotic germ cells and Leydig cells. The possible involvement of TOP in proteolytic events associated with the process of spermiogenesis and Leydig cell function is currently under investigation.

Radiation effect on rat Sertoli cell function in vitro and in vivo

PURPOSE

To investigate the response of Sertoli cell function to 60Co gamma-rays.

MATERIALS AND METHODS

Rat Sertoli cells were exposed in vitro and in vivo to 60Co gamma-rays in the dose range 3 Gy to 48 Gy and at 3 Gy and 6 Gy respectively. Cell viability and transferrin and IL-6 production were measured at different times following irradiation.

RESULTS

This study confirms the resistance of in vitro irradiated rat Sertoli cells in the dose range 3 Gy to 48 Gy in terms of cell number. Radiation had no effect on the IL-1 activity of Sertoli cells. However, the experiments show that despite the absence of a macroscopic effect, Sertoli cells respond to ionizing radiation by increasing transferrin secretion, transferrin response to (Bu)2cAMP stimulation and IL-6 activity.

CONCLUSIONS

Transferrin is involved in the transport of iron into germ cells and in cell differentiation. IL-6 is a potent inhibitor of meiotic DNA synthesis. Radio-induced transferrin and IL-6 could play a role in the protection of germ cells and could explain, in part, the resistance of Sertoli cells to radiation.

Interferons and interferon-induced antiviral proteins in the testis

Despite the dramatic development of sexually transmissible diseases, the antiviral capabilities of testicular cells have not yet been explored. Interferons (IFNs) are proteins playing a key role in the antiviral defense system, their activity being mediated by several IFN-induced proteins. In the present study, we have investigated both the expression of IFN and of the three main IFN-induced proteins by isolated testicular cells. The highest responders to a viral stimulation in terms of IFN production are the Leydig and the Sertoli cells, followed by peritubular cells and testicular macrophages, while germ cells are devoid or virtually devoid of IFN and IFN-induced protein expression. Sertoli cells constitutively expressed the three IFN-induced proteins tested, and their levels were greatly increased after exposure to Sendai virus. Peritubular cells were also able to markedly express these three proteins after viral exposure. In conclusion, we hypothesize that, for a virus coming from the blood, the first testicular line of defence is ensured by Leydig cells and testicular macrophages, the second line being ensured by the myoid cells, lining the seminiferous tubules, and by Sertoli cells. These two barriers are probably fundamental in protecting both androgen production and spermatogenesis.

Expression of interferons-alpha and -gamma in testicular interstitial tissue and spermatogonia of the rat

The testis is divided into two compartments: the seminiferous tubules and the interstitial tissue. The latter essentially consists of the blood and lymphatic vessels, testosterone-producing Leydig cells, and testicular macrophages. In the exploration of the testicular antiviral defense system, we initially searched for interferon (IFN) production by the seminiferous tubule cells. The site of virus entry into the testis is probably the interstitial compartment; thus, it is important to know whether and how the cells in this compartment are protected against viral infection. In addition, as germ cell precursors (spermatogonia) are only partially protected by the blood-testis barrier, it was important to explore the antiviral capability of these cells. In this study we searched for IFN production by Leydig cells, testicular macrophages, and spermatogonia after exposure to Sendai virus. We also investigated the effect of viral exposure on testosterone production by Leydig cells. Our results show that spermatogonia do not constitutively express IFNs and give a very poor response to the virus. In contrast, testicular macrophages constitutively produced type I IFNs, and this production was markedly stimulated by Sendai virus. Leydig cells produced twice as much type I IFNs as testicular macrophages after viral exposure, and they were the only cells producing both IFNalpha and -gamma, with these IFNs being dramatically induced/ increased in response to exposure to the virus. Furthermore, incubation of Leydig cells with the Sendai virus stimulated testosterone production. In conclusion, this study further establishes the topography of IFN expression within the testis. This allows us to hypothesize that the potential antiviral system represented by Leydig cells and, to a lesser extent, by macrophages plays a key role in protecting both androgen production and spermatogenesis.