Adenovirus-mediated gene delivery and in vitro microinsemination produce offspring from infertile male mice.
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Sertoli cells play a pivotal role in spermatogenesis through their interactions with germ cells. To set up a strategy for treating male infertility caused by Sertoli cell dysfunction, we developed a Sertoli cell gene transfer system by using an adenovirus vector, which maintained long-term transgene expression in the testes of infertile mice. Introduction of an adenovirus carrying the mouse Steel (Sl) gene into Sertoli cells restored partial spermatogenesis in infertile Steel/Steel(dickie) (Sl/Sl(d)) mutant mouse testes. Although these males remained infertile, round spermatids and spermatozoa from the testes produced normal fertile offspring after intracytoplasmic injection into oocytes. None of the offspring showed evidence of germ line transmission of adenoviral DNA. Thus, we demonstrate a successful treatment for infertility by using a gene therapy vector. Therefore, adenovirus-mediated gene delivery into Sertoli cells not only provides an efficient and convenient means for studying germ cell-Sertoli cell interactions through manipulation of the germ cell microenvironment in vivo, but also is a useful method to treat male infertility resulting from a Sertoli cell defect. (+info)
Restoration of spermatogenesis by lentiviral gene transfer: offspring from infertile mice.
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Disruption of spermatogenesis found in azoospermia and oligozoospermia is thought to be of primarily genetic origin. Sl/Sl(d) mutant mice offer a model system in which lack of transmembrane type c-kit ligand (KL2) expression on the somatic Sertoli cell surface results in disruption of spermatogenesis. We investigated the ability of adeno-, adeno-associated-, retro-, and lentiviral vectors to transduce Sertoli cells and found that transduction with either adeno- or lentiviral vectors led to reporter gene expression for more than 2 mo after testicular tubule injection. Because adenoviral vectors showed toxicity, lentiviral vectors were used to express the c-kit ligand in Sl/Sl(d) Sertoli cells. Restoration of spermatogenesis was observed in all recipient testes. Furthermore, the sperm collected from recipient testes were able to generate normal pups after intracytoplasmic sperm injection. None of the offspring carried the transgene, suggesting the inability of lentiviral vectors to infect spermatogenic cells in vivo. We propose that lentiviral vectors can be used for gene therapy of male infertility without the risk of germ-line transmission. (+info)
Male phenotype predicts insemination success in guppies.
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Theory predicts that mate choice can lead to an increase in female fecundity if the secondary sexual traits used by females to assess male quality covary with the number of sperm transferred during copulation. Where females mate multiply, such a relationship between male attractiveness and ejaculate size may, additionally (or alternatively), serve to augment the effect of indirect selection by biasing paternity in favour of preferred males. In either case, a positive correlation between male attractiveness and the size of ejaculates delivered at copulation is predicted. To date, some of the most convincing (indirect) evidence for this prediction comes from the guppy, a species of fish exhibiting a resource-free mating system in which attractive males tend to have larger sperm reserves. We show that, during solicited copulations, male guppies with preferred phenotypes actually transfer more sperm to females than their less-ornamented counterparts, irrespective of the size of their initial sperm stores. Our results also reveal that, during coercive copulations, the relationship between ejaculate size and the male's phenotype breaks down. This latter result, in conjunction with our finding that mating speed--a factor under the female's control-is a significant predictor of ejaculate size, leads us to speculate that females may exert at least partial control over the number of sperm inseminated during cooperative matings. (+info)
Frequency of multiple inseminations in field-collected Anopheles gambiae females revealed by DNA analysis of transferred sperm.
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We investigated the frequencies of single and multiple matings in field-collected female Anopheles gambiae by conducting microsatellite DNA analyses on the sperm contained within their spermatheca. Amplifcation by a polymerase chain reaction (PCR) at four loci allowed the detection of sperm extracts exhibiting more than two alleles per locus, thereby revealing the occurrence of multiple inseminations. Polyandry was found in six of 239 females examined, or 2.5% of the samples. Previous analyses of the molecular form of the sperm and female extracts using a PCR-based diagnostic procedure showed that two of these multiple inseminations involved cross-mating between two chromosomal/molecular forms of An. gambiae s.s. Thus polyandry occurred within-form in 1.7% of examined females while other multiple inseminations may be linked to processes of reproductive isolation between forms of An. gambiae. (+info)
Repeated inseminations required for natural fertility in a wild bird population.
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In most bird species, pairs copulate many times before egg laying. The exact function of repeated inseminations (i.e. successful copulations) is unknown, but several suggestions have been made. We tested the hypothesis that repeated inseminations are required to ensure fertilization of eggs, by using an experimental method where free-ranging male collared flycatchers (Ficedula albicollis) were prevented from inseminating their mates. We show that egg fertility was lower when females had not copulated during the studied part of their fertile period. By counting sperm on the inner perivitelline layer of eggs, we estimated that a minimum of 86 sperm must reach the site of fertilization to ensure average fertility. Using the timing of inseminations and the numbers of sperm on successive eggs, we show that repeated copulations are necessary to achieve an average rate of fertilization of a single clutch. Our results thus provide evidence that repeated inseminations function to ensure fertilization success. We discuss possible constraints on sperm production and utilization that may have contributed to this pattern. (+info)
Japanese quail (Coturnix japonica) inseminations are more likely to fertilize eggs in a context predicting mating opportunities.
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Theoretical developments in behavioural ecology have generated increased interest in the proximate mechanisms underlying fertilization, but little is known about how fertilization success is regulated by cues from the external or social environment in males and females. Here, we use a Pavlovian conditioning paradigm to show that inseminations resulting from mating male and female Japanese quail (Coturnix japonica) are more likely to fertilize eggs when they occur in a context predicting that an opposite-sex bird will appear than when they occur in a context predicting that an opposite-sex bird will not appear. This effect occurs when either the male or the female is the target of the conditioning. Thus, processes occurring during or after mating that contribute to fertilization success are subject to the influence of distal cues, confirming control by brain-level mechanisms. Conditioning is a widespread property of the nervous system and the demonstration that context conditioning can influence male and female reproductive success, and not simply mating success, has widespread implications for the fertilization successes of different types of copulation in natural mating systems. (+info)
Estimation of second polar body retention rate after conventional insemination and intracytoplasmic sperm injection: in vitro observations from more than 5000 human oocytes.
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PURPOSE: Tripronucleate (3pn) development after conventional insemination (CONV) or ICSI was analyzed to estimate the rate of second polar body retention giving rise to 3pn formation. METHODS: Data from 453 consecutive IVF cycles were reviewed during a 6-month period. Mature oocytes were monitored in ICSI (n = 3195) and CONV (n = 2274) groups by fertilization assessment 16-18 h post-insemination. Ovulation induction protocols and in vitro culture conditions remained constant during the study interval. RESULTS: Normal (2pn) fertilization occurred in 74.2% and 70.5% for CONV and ICSI groups, respectively (p < 0.003). 1pn formation was observed in 4.5% of CONV oocytes, and 2.5% of ICSI oocytes (p < 0.001); 3pn formation was 8.1% in the CONV group, and 2.5% in the ICSI group (p < 0.0001). We observed 4pn formation in 0.4% of oocytes in the CONV group, but in only 0.04% of oocytes fertilized with ICSI (p < 0.007). Cellular degeneration occurred in 2.4% of oocytes inseminated conventionally, and in 3.5% of oocytes fertilized by ICSI (p = 0.02). Maternal age did not impact pronuclear status. CONCLUSIONS: We found the 3pn formation rate after ICSI to be approximately one-third that observed in the CONV group. Extrapolating the ICSI data to the CONV data, it may be inferred that 2.5% of 3pn development after CONV was due to second polar body retention. This suggests that 5.6% of CONV oocytes showed dispermic fertilization. Decreasing oocyte quality with increasing maternal age had no apparent influence on any of the fertilization outcomes. (+info)
Sperm-induced modification of the oviductal gene expression profile after natural insemination in mice.
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In mammals, the physiological interaction between spermatozoa and oviductal epithelia involves intimate and specific contact between the two cell types. Spermatozoa may undergo stringent selection processes within the female reproductive tract before they meet and fertilize oocytes. The physiological basis of the sperm selection process is largely unknown. Here we tested the hypothesis that the oviduct has a recognition system for spermatozoa that can detect the arrival of spermatozoa in the oviduct after insemination, resulting in alterations of the oviductal transcriptome. We initially performed a global screening of the oviductal transcriptome in mice 1) at the time of estrus (mating) and 2) 6 h after mating. Transcriptional alterations in the oviduct after mating were attributed to the presence of spermatozoa in the oviduct after mating and also to changes in the hormonal environment as female mice underwent the transition from estrus to diestrus. To distinguish these possibilities, female mice were then mated with T145H mutant mice, which because of spermatogenic arrest, produce seminal plasma but no spermatozoa. Focusing on two molecules that in the first experiment were upregulated after mating, it was found that adrenomedullin and prostaglandin endoperoxidase synthase 2 transcripts were upregulated in the oviducts of mice only after mating with fertile males; those mated with T145H infertile males showed significantly less response. These results indicate that it is the arrival of spermatozoa in the oviduct that activates one or more signal transduction pathways and leads to changes in the oviductal transcriptome profiles. (+info)