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At least 19 recordsLinked to original sources
PubMed1992

Monoclonal antibody AG7 inhibits fertilization post sperm-zona binding.

Monoclonal antibodies (mAbs) against sperm cells are currently being used in an effort to define spermatozoal antigens involved in the fertilization process. We have produced a number of anti-human sperm mAbs by immunization of female mice with the 100,000 x g supernatant of octylglycoside-solubilized washed human sperm. From a panel of mAbs, 1 antibody, AG7, was selected and characterized due to its fertilization-inhibiting characteristics. MAb AG7 defines a sperm acrosome antigen-1 (SAA-1) located in the acrosomal region of human sperm as evaluated by indirect immunofluorescence. Staining of life sperm cells indicated that the antigen is present on the sperm surface. SAA-1 was also found on sperm of several other mammalian species, implying evolutionary conservation of the antigen. SAA-1 was first observed on testicular sperm and can be followed through epididymal transit, ejaculation, and capacitation. When applied in a mouse in vitro fertilization assay, mAb AG7 inhibits fertilization by greater than 95%, and inhibition is dose dependent, with half-maximal inhibition at 0.8 micrograms/ml. The block to fertilization could not be attributed to sperm agglutination, inhibition of motility, interference with adhesion to the zona pellucida, or inhibition of fusion with the oocyte membrane. MAb AG7 was demonstrated to inhibit calcium influx in spermatozoa in vitro (measured using the fluorescent indicator fura 2), a prerequisite for the acrosome reaction. Initial biochemical characterization of the antigen suggests it is proteinlike in nature, with a molecular weight of approximately 220 kD. The results suggest that SAA-1, identified by mAb AG7, is a sperm antigen crucially involved in the fertilization process, possibly an atypical steroid receptor or ion channel located within the sperm plasma membrane.

Acrosome↗
PubMedDate not supplied

Fertility inhibiting effects of the intermediate fertility variables in two Nigerian sub-groups.

"In this paper, the fertility-inhibiting effects of the intermediate fertility variables among the Ikale-Yoruba are contrasted against those of the Ekiti, another Yoruba group for which more conventional family building practices have been reported. The objectives of the comparative approach are as follows: (a) to show that abstinence is not a factor in the reduction of marital fertility among the Ikale-Yoruba, as it is in other sub-groups studied so far; (b) that alternative outlets of fertility reduction, such as reliance on the protection offered by post-partum amenorrhoea, and some practice of folk and modern methods of contraception, are employed." The data, which were collected in Nigeria in 1977, concern 460 currently married Ikale-Yoruba women and some of their husbands, and 535 eligible Ekiti-Yoruba women. The results show that although total fertility rates between the two groups were similar, there were significant differences concerning the relative reliance by each group on postpartum abstinence and contraception. (summary in FRE, ITA)

Africa↗
PubMed1978

Fertility inhibition in Rhizobium lupini by the resistance plasmid RP4.

R plasmid RP4 inhibits the fertility of R. lupini. An RP4 carrying R. lupini donor strain is no longer capable of transferring chromosomal genes. After loss of RP4 the R. lupini fertility reappears. Plasmid RP4 spontaneously mutates at high frequency in R. lupini. RP4 mutants which do not inbibit fertility were isolated. These mutants were always transfer-defective, too. It is postulated that the genetic information for fertility inhibition in R. lupini is a substantial part of the transfer unit of the RP4 plasmid.

Ampicillin↗
PubMed1984

Location of a function on RP1 that fertility inhibits Inc W plasmids.

Two fertility inhibition (Fi+) functions which reduce R388 (Inc W) transfer were detected on RP1 (Inc P). Neither function affected R388 -mediated surface exclusion but they could be distinguished by their effect on pilus production. One of the functions was located in the 6.5-kb Pst1 -C region of RP1, part or all of which also occurs on six Fi+ but not two Fi- Inc P plasmids studied.

Conjugation, Genetic↗
PubMed1975

RP1 properties and fertility inhibition among P, N, W, and X incompatibility group plasmids.

Incompatibility group P plasmids demonstrate strong entry exclusion properties. Stringent incompatibility is also observed in the absence of entry exclusion. These observations have been facilitated by the study of a nontransmissible plasmid, RP1-S2, derived from RP1 by transductional shortening. RP1-S2 retains carbenicillin and tetracycline resistances as well as loci that cause either the loss of P plasmids (incp) or a locus specifying susceptibility to curing (sinp) in the presence of a P plasmid. RP1-S2 can be mobilized by an incompatibility group W plasmid, R388, and also freely forms recombinants with R388. P, N, and W incompatibility group plasmids all encode information for the receptor of the cell wall-adsorbing phage PRD1. Based on the premise that the location of this receptor is analogous to entry exclusion factors for F-like plasmids and hence a regulated transfer region determinant, we tested fertility inhibition relationships among these plasmid groups. We detected both reciprocal and nonreciprocal fertility inhibition relationships for bacteria containing various combinations of W, N, and P group plasmids. The nonreciprocal nature of some combinations, we believe, reflects the identity of the point mutation reading to derepression of the plasmid in question. Reciprocal fertility inhibition, on the other hand, may reflect the reconstruction of a fertility inhibition system through complementation. An X incompatibility group plasmid, known to affect the fertility of an N group plasmid, was also shown to inhibit P plasmid fertility. These observations may indicate a possible evolutionary relationship(s) of plasmids unrelated by the criteria of incompatibility, pilus phage specificity, or plasmid host range.

Biological Evolution↗
PubMedDate not supplied

The fertility-inhibiting effects of the intermediate fertility variables.

Based on the application of an aggregate reproductive model, this study demonstrates that a small number of intermediate fertility variables are responsible for most of the variation in fertility levels of populations. Four variables--proportion married, contraception, induced abortion, and postpartum infecundability--are generally the most important determinants of fertility; the other intermediate factors are of less interest except in unusual circumstances. These four factors explain 96 percent of the variance in the total fertility rate in a sample of 41 populations that include developing and developed countries as well as historical populations. In the last section, the average fertility effect of the principal intermediate fertility variables is estimated for groups of contemporary populations with different total fertility rates.

Abortion, Induced↗
PubMed1998

Analysis of the major domains of the F fertility inhibition protein, FinO.

The mechanism of fertility inhibition of conjugation by the F plasmid depends on the presence of both the FinO protein and an antisense RNA, FinP, which together control the expression of the positive regulator of the transfer operon TraJ. FinO both prevents the degradation of FinP, allowing its intracellular concentration to rise, and promotes duplex formation with its target, the traJ mRNA. In this study, deletions in finO were constructed and fused to gst, encoded by the pGEX-2T expression vector, to give GST-FinO fusions of varying lengths. These fusions were then tested for their ability to bind FinP and traJ mRNA, and to promote duplex formation. Our results suggest that the predicted basic N-terminal alpha-helix is involved in RNA binding, while the central domain is involved in duplex formation. The presence of the acidic C-terminal domain protects FinP from ribonucleolase degradation and might enhance binding of the N-terminal alpha-helical domain in a manner reminiscent of the Rom protein of ColE1.

Amino Acid Sequence↗
PubMed2003

Characterizing the structural features of RNA/RNA interactions of the F-plasmid FinOP fertility inhibition system.

F-like plasmid transfer is mediated by the FinOP fertility inhibition system. Expression of the F positive regulatory protein, TraJ, is controlled by the action of the antisense RNA, FinP, and the RNA-binding protein FinO. FinO binds to and protects FinP from degradation and promotes duplex formation between FinP and traJ mRNA, leading to repression of both traJ expression and conjugative F transfer. FinP antisense RNA secondary structure is composed of two stem-loops separated by a 4-base single-stranded spacer and flanked on each side by single-stranded tails. Here we show that disruption of the expected Watson-Crick base pairing between the loops of FinP stem-loop I and its cognate RNA binding partner, traJ mRNA stem-loop Ic, led to a moderate reduction in the rate of duplex formation in vitro. In vivo, alterations of the anti-ribosome binding site region in the loop of FinP stem-loop I reduced the ability of the mutant FinP to mediate fertility inhibition and to inhibit TraJ expression when expressed in trans at an elevated copy number. Alterations of intermolecular complementarity between the stems of these RNAs reduced the rate of duplex formation. Our results suggest that successful interaction between stem-loop I of FinP and stem-loop Ic of traJ mRNA requires that base pairing must proceed from an initial loop-loop interaction through the top portion of the stems for stable duplex formation to occur.

Base Sequence↗
PubMed1983

Monoclonal antibodies to the sea urchin egg vitelline layer inhibit fertilization by blocking sperm adhesion.

Thirty-one mouse hybridomas were produced against the vitelline layer (VL) of the egg of the sea urchin S. purpuratus. Ascites fluids of eight of the 31 bound to the VL surface in the high ionic strength conditions of sea water. Binding was specific to the VL, since immunofluorescence showed that the antibodies elevated from the egg surface with the fertilization envelope after activation with ionophore A23187. Antibody binding was strictly species-specific, the eggs of L. pictus showing no reaction. An immunoperoxidase surface-binding assay showed a wide range in the amount of each monoclonal antibody binding to the VL surface at saturation. All eight monoclonals inhibit fertilization by inhibiting the binding of sperm to the VL. None of the eight ascites fluids reacted with egg jelly. The inhibition of fertilization correlates positively with amount of antibody binding the egg surface. In contrast to the effects of polyclonal rabbit antisera raised against whole eggs or egg cortices, these eight monoclonal antibodies to the VL do not induce the wrinkling of the egg, the cortical granule reaction, the centering of pronuclei, or any other visual indication of metabolic activation.

Animals↗
PubMed1976

Transfer gene expression during fertility inhibition of the Escherichia coli K12 sex factor F by the I-like plasmid R62.

Further understanding of how the FinQ fertility inhibition system of the I-like plasmid R62 inhibits transfer of the sex factor F has been gained by the use of a genetic assay for individual transfer gene products. The technique involved construction of a series of Flac plasmids carrying suppressible mutations in individual transfer genes together with a FinQ inhibitor-insensitive traQ mutation. The transfer of the Flac double mutants from a strain carrying wild-type Fhis and R62 then indicated the effect of R62-encoded transfer inhibition on the expression of individual F transfer genes. During such inhibition the products of genes traJ, traA, traE, traB and traC were present in quantities sufficient to permit efficient F transfer, whereas the levels of the traF, traH, traG and traD gene products were so reduced as to limit F transfer. These findings and a failure to obtain recombination between traC and traQ mutations suggest that the R62 fertility inhibition system terminates transcription of the transfer operon between traC and traF.

Coliphages↗
PubMed1977

Further characterization of the F fertility inhibition systems of "unusual" Fin+ plasmids.

Flac mutants insensitive to transfer inhibition by R factors. JR66a and R485 were isolated and characterized. Representative mutations were cis dominant and are therefore presumed to be at the sites of action, fisU and fisV, respectively, of the FinU and FinV transfer inhibition systems encoded by JR66a and R485. The mutants were used to confirm that the FinU and FinV fertility inhibition systems are different from each other and from the FinOP, FinQ, and FinW systems of R100, R62, and R455, respectively. Together with traO and fisQ mutants of Flac, the new mutants were also used to investigate the nature of the F fertility inhibition systems encoded by a further group of "unusual" Fin+ plasmids. Of these, two incompatibility group X plasmids were found to carry finO+ genes, and of five incompatibility group I plasmids, three encoded FinQ systems, one the FinU system, and one a new system (FinR). Transfer of a variety of derepressed F-like plasmids was inhibited by the FinQ, FinU, and FinV systems, but a quantitatively very different levels; this emphasizes the differences as well as the similarities between the conjugation systems of F-like plasmids.

Coliphages↗
PubMed1992

Differential levels of fertility inhibition among F-like plasmids are related to the cellular concentration of finO mRNA.

The FinOP system of F-like plasmids consists of an antisense RNA (FinP) and a 22 kDa protein (FinO) which act in concert to prevent the translation of TraJ, the positive regulator of the transfer operon. Earlier studies suggested that two different variants of finO were responsible for differential levels of fertility inhibition among F-like plasmids. We have shown that these variations are due to the presence of an additional open reading frame (orf286) upstream of the finO gene of conjugative plasmids that are highly repressed for transfer. When orf286 and finO are linked in cis, the level of FinO expression is increased because of a rise in the cellular concentration of finO mRNA. orf286 frameshift and deletion mutants also gave the same concentration of finO transcript, suggesting that the effect is due to mRNA stabilization. We suggest that the levels of fertility inhibition exhibited by F-like plasmids are a function of their cellular FinO concentration.

Amino Acid Sequence↗
PubMed1991

Cannabinoids inhibit fertilization in sea urchins by reducing the fertilizing capacity of sperm.

Delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) inhibit fertilization in the sea urchin Strongylocentrotus purpuratus by reducing the fertilizing capacity of the sperm. Sperm fertility depends upon their motility, and their capacity to undergo the acrosome reaction upon encountering a specific ligand derived from the egg's jelly coat. The acrosome reaction involves exocytosis of the acrosomal granule at the apex of the sperm head and elongation of the acrosomal filament. This process exposes the sperm membrane that will attach to and fuse with the egg. Pretreatment of sperm with THC prevents the triggering of the acrosome reaction by solubilized egg jelly in a dose and time dependent manner. Motility of THC-treated sperm is not reduced compared to control sperm in sea water or vehicle dissolved in sea water. The adverse effects of THC on the acrosome reaction and sperm-fertilizing capacity are reversible. Studies with ionophores suggest that THC blocks the acrosome reaction by affecting event(s) in the stimulation-secretion coupling mechanism in the sperm preceding the opening of ion channels. Ultrastructural studies show that THC, CBD and CBN block the membrane fusion reaction between the sperm's plasma membrane and the acrosomal membrane that normally is elicited in response to stimulation by egg jelly to initiate the acrosome reaction. However, lipid deposits are found in the subacrosomal and centriolar fossae of cannabinoid treated sperm. The nuclear envelope is fragmented in close proximity to the lipid deposits within the subacrosomal fossa. These morphological observations suggest that cannabinoids may activate phospholipase(s) within the sperm. Biochemical studies show that THC activates phospholipase A2 activity in sperm homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1996

Serum from women with polycystic ovary syndrome inhibits fertilization and embryonic development in the murine in vitro fertilization model.

OBJECTIVE: To study the effects of serum collected from women with polycystic ovary syndrome (PCOS) on the fertilization and early embryonic development of the murine oocyte. DESIGN: Sera from women with anovulation were used as a supplement in a murine IVF model. SETTING: Tertiary care academic medical center. PATIENTS: Four fertile, four hypothalamic amenorrheic, seven PCOS (three with elevated LH and four with elevated T), and three anovulatory women with normal hormone levels. RESULTS: When compared with serum from fertile women, serum from women with PCOS reduced fertilization rates (60% versus 42%) and subsequent early embryonic development rates (87% versus 31%). Serum from women with PCOS and elevated T levels had the lowest fertilization rates (22%). Polycystic ovary syndrome serum with elevated T or LH levels significantly decreased early embryonic development rates in comparison to fertile women (22%, 41% versus 87%). CONCLUSIONS: Serum from women with PCOS inhibited fertilization and blastocyst development. Because both T and LH caused inhibited blastocyst development, these data have implications regarding low pregnancy rates and live birth rates during ovulation induction in women with anovulation. These data also raise questions regarding the use of serum during IVF.

Amenorrhea↗
PubMed1988

Wheat germ agglutinin treatment of follicle cell-free mouse oocytes inhibits fertilization.

Controversy exists whether treatment of follicle cell-free oocytes with wheat germ agglutinin (WGA) prevents fertilization. Lack of inhibition in one case has led to the suggestion that acrosin may not be a zona lysin. To re-examine the effect of the WGA, the zona pellucida of follicle cell-free mouse oocytes was made more resistant to proteinase digestion by treatment with 10 or 50 micrograms/ml WGA. Such WGA-treated oocytes showed decreased fertilizability when washed to remove excess WGA and incubated with capacitated spermatozoa. Oocyte cleavage was used as an end point, because a large number of spermatozoa adhered to the eggs after WGA treatment, making observation of sperm penetration and pronucleus formation unreliable. Resistance to proteinase digestion increased, and the fertilizability decreased with the higher amount of WGA. The action of WGA was most likely not mediated by a direct effect on sperm motility, sperm acrosin activity, sperm binding to the zona pellucida, or oocyte cleavage. WGA did not affect the acrosome reaction of guinea pig spermatozoa. These data show that WGA treatment of follicle cell-free mouse oocytes results in decreased fertilizability, possibly by rendering the zona pellucida more resistant to sperm proteinase digestion.

Acrosin↗
PubMed1978

[Postcoital contraception in primates. I. Action mechanism of a potential postovulatory fertility-inhibiting substance STS 456 in the baboon (Papio hamadryas)].

With the substance STS 456, an estrogenic active steroid, a high fertility inhibition could be obtained in the pavian, when administered p. o. over a 5 day period postcoital. The effectiveness and also the side effects were dose dependent. The antifertility mechanism is based on an luteolytic effect, demonstrated by analytical hormonal investigations. The inhibition of the synthesis of steroids in the ovary affected not only progesterone but also the estrogens.

Animals↗
PubMed1976

Immunological block to mammalian fertilization: survival and organ distribution of immunoglobulin which inhibits fertilization in vivo.

Fertilization of golden hamster eggs was blocked both in vitro and in vivo by antibodies produced in rabbits against specific hamster ovarian antigens (HOA). Antibodies against HOA bound to surfaces of the hamster egg zona pellucida and prevented spermatozoa from attaching to the zona and entering eggs in vitro. Fertilization in animals could be blocked for four estrous cycles by a single intraperitoneal injection of anti-HOA immunoglobulin, but not by control immunoglobulin. The in vivo fate of anti-HOA immunoglobulin was analyzed by simultaneous injection of 125I-anti-HOA IgG and control 131I-IgG. Both anti-HOA IgG and control IgG appeared in a variety of organs (lung, kidney, spleen, liver, and uterus) shortly after injection, but disappeared rapidly with no detectable differences in organ half lives. However, in the ovary anti-HOA IgG (but not control IgG) persisted at high levels during the period of infertility. Quantitative precipitin analysis of organ homogenates indicated that a high percentage of anti-HOA IgG in the ovary (but not in the other organs tested) was immunologically indistinguishable from IgG indicating lack of radiolabel metabolism and reincorporation. The results are discussed in terms of the development of a specific immunological block to fertility.

Animals↗
PubMed2001

L-arginine, the substrate of nitric oxide synthase, inhibits fertility of male rats.

AIM: To examine the effect of L-arginine, the substrate of nitric oxide (NO) synthase, on reproductive function of male rats. METHODS: Male rats were gavaged with either L-arginine (100 or 200 mg x kg(-1) x d(-1)), D-arginine (200 mg x kg(-1) x d(-1)) or vehicle (0.9% NaCl) for seven consecutive days. Their sexual behaviour and fertility were evaluated using receptive females. RESULTS: L-arginine (200 mg/kg) had no significant effect on sexual competence (in terms of sexual arousal, libido, sexual vigour and sexual performance). In mating experiments, the higher dose of L-arginine effectively and reversibly inhibited fertility, whilst the lower dose and the inactive stereoisomer D-arginine had no significant effect. The antifertility effect caused by L-arginine was due to a profound elevation in the preimplantation loss mediated possibly by impairment in epididymal sperm maturation, hyperactivated sperm motility and sperm capacitation. CONCLUSION: Elevated NO production may be detrimental to male fertility.

Animals↗