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Fertilin is a protein initially identified in guinea pig spermatozoa; it is the prototype of a larger family of conserved proteins designated as a disintegrin and a metalloproteinase (ADAM). These heterodimers which consist of α and β subunits, containing metalloproteinase-like and disintegrin-like domains, appear to play a role in mammalian fertilization. Peptides derived from the disintegrin domains of two ADAMs, fertilin and cyritestin, interfere with gamete adhesion and sperm-egg membrane fusion in non-human species. It has been suggested that fertilin-β binds to an oolemmal integrin, and it is proposed that the tripeptide FEE (Phe-Glu-Glu) is the integrin recognition sequence in human fertilin-β. We evaluated whether fertilin β plays a role in human fertilization by studying the effects of a linear octapeptide containing the FEE sequence, SFEECDLP, and a scrambled octapeptide with the same amino acids, SFPCEDEL, on the incorporation of human spermatozoa by human zona-free eggs. The effects of G4120, a potent RGD-containing (Arg-Gly-Asp) thioether-bridged cyclic peptide which blocks both fibronectin and vitronectin receptors, and the relationship between FEE- and RGD-receptor interactions on sperm-egg interactions were also studied. The FEE-containing peptide, but not the scrampled peptide, inhibited sperm adhesion to oocytes and their penetration, over the range 1-5 μM. The inhibition induced by SFEECDLP was reversible and occurred only in the presence of peptide itself. The G4120 peptide exhibited 10-fold less inhibitory effects on sperm adhesion and penetration than did SFEECDLP. When combined, SFEECDLP and G4120 exhibited strong inhibition of both adhesion and penetration at concentrations that individually had been ineffective, suggesting co-operation between the two receptor-ligand interactions during fertilization. We propose that a fertilin-like molecule is functionally active on human spermatozoa and that its inter... [ABSTRACT FROM AUTHOR]

It has been suggested that first polar body (PBI) morphology reflects oocyte competence. Oocytes with an intact normal-sized PBI have been described as generating better day 2 embryos, higher blastocyst yield, and increased pregnancy and implantation rates. In other studies, PBI morphology was found to be unrelated to fertilization rate, embryo quality, and blastocyst formation. In a prospective analysis, the predictive value of the PBI was investigated by comparing the development of oocytes retrieved from intracytoplasmic sperm injection patients and displaying different PBI morphology, classified according to the following characteristics: normal size and smooth surface (I), fragmented (II), rough surface (III), or large size (IV). Fertilization rates were 59, 57, 64 and 60% respectively. No significant differences were found between the various groups. The proportions of high quality (grade A) day 2 embryos were also comparable among groups I-III (14, 12 and 17% respectively), while the low number of grade A embryos in group IV (two embryos) did not allow comparison with the other classes. These data do not suggest that PBI selection can contribute to identification of embryos with high developmental ability. In order to establish alternative criteria for oocyte selection, a metaphase II (MII) spindle analysis was also conducted via Polscope. In oocytes of patients of different age, spindle retardance (which reflects the high order and density of microtubules) was compared with parameters of embryo development. In aged patients, a trend was observed between low retardance and poor embryo quality, although in general the association between retardance and oocyte developmental performance did not reach statistical significance.

S-Adenosylmethionine (SAMe) is the methyl donor to numerous acceptor molecules. We used cycloleucine (CL), which prevents the conversion of methionine to SAMe by inhibiting ATP-l-methionine-adenosyltransferase (MAT), to characterize the lipid and protein changes induced in peripheral nerve and brain myelin in rats during development. We also investigated the effect of exogenous SAMe by administering SAMe-1,4-butane disulfonate (SAMe-SD4). CL was given on days 7, 8, 12, and 13 and SAMe-SD4 was given daily from day 7; the animals were killed on day 18. CL accumulates in the brain reaching a concentration within 24 h compatible with its ID(50) in vitro and interacting with methionine metabolism; brain MAT activity and SAMe levels were lower and methionine levels higher than in controls. CL significantly reduced brain and nerve weight gains, brain myelin content, proteins, phospholipids, and galactolipids. Among phospholipids in nerve and brain, only sphingomyelin was significantly increased, by 35-50%. Sciatic nerve protein analyses showed some significant changes: protein zero in sciatic nerve remained unchanged but the 14.0- and 18.5-kDa isoforms of myelin basic protein showed a dramatic increase. Among the main proteins, in purified brain myelin, the proteolipid protein and dimer-20 isoform decreased after CL. SAMe-SD4 highlights some sensitive parameters by counteracting, at least partially, some alterations of PL--particularly galactolipids and sphingomyelins--and proteins induced by CL. The partial beneficial effects might also be explained by the age-related limited bioavailability of exogenous SAMe, a finding, to our knowledge, not yet reported elsewhere. This study demonstrates that availability of methyl donors is closely related to the formation of myelin components., (Copyright 1999 Academic Press.)

Fertilin is a protein initially identified in guinea pig spermatozoa; it is the prototype of a larger family of conserved, proteins designated as a disintegrin and a metalloproteinase (ADAM). These heterodimers which consist of alpha and beta subunits, containing metalloproteinase-like and disintegrin-like domains, appear to play a role in mammalian fertilization. Peptides derived from the disintegrin domains of two ADAMs, fertilin and cyritestin, interfere with gamete adhesion and sperm-egg membrane fusion in non-human species. It has been suggested that fertilin-beta binds to an oolemmal integrin, and it is proposed that the tripeptide FEE (Phe-Glu-Glu) is the integrin recognition sequence in human fertilin-beta. We evaluated whether fertilin beta plays a role in human fertilization by studying the effects of a linear octapeptide containing the FEE sequence, SFEECDLP, and a scrambled octapeptide with the same amino acids, SFPCEDEL, on the incorporation of human spermatozoa by human zona-free eggs. The effects of G4120, a potent RGD-containing (Arg-Gly-Asp) thioether-bridged cyclic peptide which blocks both fibronectin and vitronectin receptors, and the relationship between FEE- and RGD-receptor interactions on sperm-egg interactions were also studied. The FEE-containing peptide, but not the scrampled peptide, inhibited sperm adhesion to oocytes and their penetration, over the range 1-5 microM. The inhibition induced by SFEECDLP was reversible and occurred only in the presence of peptide itself. The G4120 peptide exhibited 10-fold less inhibitory effects on sperm adhesion and penetration than did SFEECDLP. When combined, SFEECDLP and G4120 exhibited strong inhibition of both adhesion and penetration at concentrations that individually had been ineffective, suggesting co-operation between the two receptor-ligand interactions during fertilization. We propose that a fertilin-like molecule is functionally active on human spermatozoa and that its interaction with an oolemmal integrin receptor plays a role in fertilization in humans.

Objective: To determine whether human spermatozoa and oocytes share common antigenic epitopes, supporting the hypothesis that their cross-linking by antisperm antibodies present in the clinical sera of infertile couples could promote sperm adhesion to the oolemma., Design: Human and hamster eggs were studied for the presence of antigens recognized by a panel of World Health Organization Task Force monoclonal antibodies (mAbs) originally raised against human spermatozoa. A new technique was devised, using frozen sections of paraformaldehyde-fixed individual human and hamster eggs, to screen rapidly antisperm mAbs for egg reactivity. Living zona-free human and hamster eggs then were exposed to Covaspheres (Duke Scientific, Palo Alto, CA) coupled with these mAbs to document the presence of reactive epitopes on the oolemma., Setting: Academic research environment., Main Outcome Measure(s): Indirect immunofluorescence and Covasphere rosetting., Result(s): Eleven of 37 antisperm mAbs tested reacted with fixed hamster eggs and 10 reacted with human eggs. Five of 6 mAbs reactive with both fixed eggs also reacted with the oolemma of living, zona-free eggs., Conclusion(s): Common antigenic epitopes, some of which are shared with somatic tissues, exist on the oolemma of human eggs and on the plasma membrane of human spermatozoa.