Although human diseases of retrotransposition-derived etiology have been documented, retrotransposon RNA expression and the occurrence of retrotransposition events in the human oocyte are not studied. We investigated the RNA expression of L1 and HERV-K10 retrotransposons in human oocytes by RT-PCR analysis with designed primers. Using denucleated germinal vesicles (GVs), we detected RT-PCR products of expressed L1, HERV-K10 and, unexpectedly, SINE-R, VNTR and Alu (SVA) retrotransposons. Their transcript specificities were identified as such following RNA-FISH and their origin by cloning and sequence alignment analyses. Assessing the expression level in comparison with somatic cells by densitometry analysis, we found that although in normal lymphocytes and transformed HeLa cells their profile was in an order of L1 > HERV-K10 > SVA, remarkably this was reversed in oocytes. To investigate whether de novo retrotransposition events occur and reverse transcriptases are expressed in the human oocyte, we introduced in GVs either a retrotransposition active human L1 or mouse reverse transcriptase deficient-VL30 retrotransposon tagged with an EGFP-based retrotransposition cassette. Interestingly, in both the cases, we observed EGFP-positive oocytes, associated with an abnormal morphology for L1 and granulation for VL30, and the retrotransposition events were confirmed by PCR. Our results: (i) show that L1, HERV-K10 and SVA retrotransposons are transcriptionally expressed and (ii) provide evidence, for the first time, for retrotransposition events occurring in the human oocyte. These findings suggest that both, network of retrotransposon transcripts and controlled retrotranspositions, might serve important functions required for oocyte development and fertilization while the uncontrolled ones might explain the onset of genetic disorders.
The presence of long SHBG(TAAAA)n alleles is associated with increased risk for PCOS and in combination with short AR(CAG)n alleles may influence the hyperandrogenic phenotype of PCOS. This combined genotype may contribute to 'fetal programming' of PCOS.
The role of estrogen receptor a (ERa) and estrogen receptor b (ERb) gene polymorphisms on semen quality is the aim of our study. One hundred fourteen men were examined in the In Vitro Fertilization Unit of Ioannina Medical School, and it was found that 85 men had normal sperm count and 29 were oligozoospermic. The genotype analysis, on DNA extracted from spermatozoa, revealed that in men with oligozoospermia (sperm concentration ,20 6 10 6 spermatozoa/mL), those with ERa 397T/C and 397C/C genotypes had higher sperm motility whereas those with 397T/T genotype had lower sperm motility (P 5 .003). In addition, men with ERa 351A/ A genotype had lower sperm motility compared with 351A/G and 351 G/G genotypes (P 5 .013). Furthermore, normal-sperm-count men with ERa 397T/T genotype had higher sperm concentration compared with 397T/C and 397C/C genotypes (P 5 .016), whereas men with ERa 351A/A genotype had higher sperm concentration than those with 351A/G and 351G/G genotypes (P 5 .05). In contrast, no significant associations were found between ERb (1082GRA and 1730ARG) polymorphisms and sperm concentration or motility. In conclusion, ERa polymorphisms were found to be associated with sperm motility and concentration. supporting the significance of this gene in spermatogenesis and semen quality.
Severe obesity constitutes the main public health crisis of the industrialised world. Bariatric surgery has been proposed as the most efficient treatment of obesity. In this study, we report the potential effects of bariatric surgery on semen parameters in male partners of couples undergoing assisted reproduction. These patients had been tested in the context of infertility treatment in two consecutive cycles before and after bariatric surgery. A marked reduction in sperm parameters was observed in a period of twelve to eighteen months after surgery. This unfavourable effect had also remarkable effects on the assisted reproduction outcome, necessitating the counselling of patients before bariatric surgery.
The roles of androgen receptor AR(CAG)n gene polymorphisms and sex hormone-binding globulin SHBG(TAAAA)n gene polymorphisms on semen quality were studied. One hundred fourteen men were included in the study: 85 with normal sperm count and 29 oligospermic. The genotype analysis, on DNA extracted from spermatozoa, revealed five SHBG(TAAAA)n alleles with 6-10 repeats and 18 AR(CAG)n alleles with 12-32 repeats. The SHBG allelic distribution showed that in men with normal sperm count and motility, those with short SHBG alleles had higher sperm concentration than men with long SHBG alleles (P = 0.039). As concerns AR(CAG)n polymorphisms, men with short AR alleles had lower sperm motility compared to those with long AR alleles (P < 0.001) in both total study population and normal sperm count men. The synergistic effect analysis of the two polymorphisms revealed an association between sperm motility (P = 0.036), because of the effect of AR(CAG)n polymorphism on sperm motility. In conclusion, long AR alleles were found to be associated with higher sperm motility, while short SHBG alleles were associated with higher sperm concentration, supporting the significance of these genes in spermatogenesis and semen quality.
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