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Nicotine, the most important neuroteratogen of tobacco smoke, can reproduce brain and cognitive disturbances per se when administered prenatally. However, it is still unknown if paracrine signaling among brain cells participates in prenatal nicotine-induced brain impairment of adult offspring. Paracrine signaling is partly mediated by unopposed channels formed by connexins hemichannels (HCs) and pannexins serving as aqueous pores permeable to ions and small signaling molecules, allowing exchange between the intra- and extracellular milieus. Our aim was to address whether prenatal nicotine exposure changes the activity of those channels in adult mice offspring under control conditions or subjected to a second challenge during young ages: high-fat/cholesterol (HFC) diet. To induce prenatal exposure to nicotine, osmotic minipumps were implanted in CF1 pregnant mice at gestational day 5 to deliver nicotine bitartrate or saline (control) solutions. After weaning, offspring of nicotine-treated or untreated pregnant mice were fed ad libitum with chow or HFC diets for 8 weeks. The functional state of connexin 43 (Cx43) and pannexin 1 (Panx1) unopposed channels was evaluated by dye uptake experiments in hippocampal slices from 11-week-old mice. We found that prenatal nicotine increased the opening of Cx43 HCs in astrocytes, and Panx1 channels in microglia and neurons only if offspring mice were fed with HFC diet. Blockade of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2) and prostaglandin E receptor 1 (EP1), ionotropic ATP receptor type 7 (P2X7) and NMDA receptors, showed differential inhibition of prenatal nicotine-induced channel opening in glial cells and neurons. Importantly, inhibition of the above mentioned enzymes and receptors, or blockade of Cx43 and Panx1 unopposed channels greatly reduced adenosine triphosphate (ATP) and glutamate release from hippocampal slices of prenatally nicotine-exposed offspring. We propose that unregulated gliotransmitter release through Cx43 and Panx1 unopposed channels may participate in brain alterations observed in offspring of mothers exposed to tobacco smoke during pregnancy.

The cholesterol content of the sperm membrane is regulated during both maturation in the epididymis and capacitation in the female tract, two processes required for the spermatozoa to acquire their fertilising ability. Because Niemann-Pick disease, type C2 (NPC2) protein is one of the most abundant components of the epididymal fluid and contains a functional cholesterol-binding site that can transfer cholesterol between membranes, it has been suggested for yearsthat NPC2couldbeinvolvedintheregulationofcholesterollevels inspermatozoa duringepididymalmaturation. In the presentstudy,westernblotandimmunohistochemistryanalysesdemonstrated significant levelsof NPC2inthemouse epididymal epithelium. Epididymal spermatozoa obtained from NPC2 � /� mice were morphologically normal and had normal motility parameters, but had a reduced cholesterol content compared with that of wild-type (WT) spermatozoa, as determined by both biochemical and by flow cytometry analyses. These results suggest that NPC2 could be involved in regulating cholesterol levels in spermatozoa during epididymal maturation. To understand the relevance of epididymal NPC2 for sperm function, the ability of spermatozoa to undergo events influenced by epididymal maturation, such as capacitation and fertilisation, were compared between WT and NPC2 � /� mice. Capacitated NPC2 � /� spermatozoa exhibited defective tyrosine phosphorylation patterns and a reduced ability to fertilise cumulus-oocyte complexes compared with WT spermatozoa, supporting the relevance of mouse epididymal NPC2 for male fertility. Additional keywords: epididymis, fertilisation.

Cholesterol has evolved to fulfill sophisticated biophysical, cell signaling and endocrine requirements of animal systems. At a cellular level, cholesterol is found in membranes, where it increases both bilayer stiffness and impermeability to water and ions. Furthermore, cholesterol is integrated into specialized lipid-protein membrane microdomains with critical topographical and signaling functions. At an organismal level, cholesterol is the precursor for all steroid hormones, including gluco- and mineralo-corticoids, sex hormones and vitamin D, all of which regulate carbohydrate, sodium, reproductive and bone homeostasis, respectively. This sterol is also the precursor for bile acids, which are important for intestinal absorption of dietary lipids as well as energy and glucose metabolic regulation. Importantly, complex mechanisms maintain cholesterol within physiological ranges and the disregulation of these mechanisms results in embryonic or adult diseases, caused by either excessive or reduced tissue cholesterol levels. The causative role of cholesterol in these diseases has been demonstrated by diverse genetic and pharmacologic animal models that are commented in this review.

Infants born from overweight and obese mothers with glucose-controlled gestational diabetes (GDM) tend to be large-for-gestational age (LGA). It is hypothesized that this is due to an excessive rise in maternal triglyceride levels.Two-hundred and seventy nine singleton GDM pregnancies were divided into three groups according to prepregnancy BMI: normal weight (BMI = 20-24.9; n = 128), overweight (BMI = 25-29.9; n = 105), and obese (BMI ≥ 30; n = 46). Individual z-scores (ZS) of maternal triglycerides and of newborn weight (NWZS) were calculated as deviations from published 50th percentiles. Mean z-scores (MZS) were the average of triglyceride ZSs. MZS of triglycerides, HbA1c and NWZS were compared. Variables are expressed as mean ± SD.In the three groups respectively: LGA (%) = 10.1%, 19.0% and 30.4% (P = 0.015). Birth weight (g) = 3274.2 ± 501.3, 3342.4 ± 620.2 and 3366.3±644.7 (RSPEARMAN = 0.111, P = 0.027). HbA1c (%) = 5.2 ± 0.39, 5.3 ± 0.50 and 5.4 ± 0.47 (P = NS). Triglyceride MZS = 1.20 ± 1.13, 1.52 ± 1.37 and 1.62 ± 1.42 (RSPEARMAN = 0.116, P = 0.024). Correlations between triglyceride MZS and NWZS were, respectively: r = 0.12 (P = NS), r = 0.42 (P0.001), and r = 0.47 (P 0.001).In overweight and obese GDM mothers, maternal triglycerides are partially responsible for LGA infants despite good maternal glucose control during pregnancy.

High density lipoproteins (HDL) are responsible of reverse cholesterol transport and play an important antiatherogenic role. In recent years, several studies suggest that HDL have additional functions, including a possible anti-inflammatory activity in infectious conditions. Furthermore, available evidence indicates that the presence of lipopolysaccharide (LPS) within the circulation during infectious states induced by gram-negative bacteria may be involved in the decrease in HDL cholesterol levels and changes in lipoprotein composition, which have been associated with a higher mortality due to sepsis in animal models and in humans. In this article, we review this subject and also discuss possible mechanisms that explain the positive impact achieved by native HDL, reconstituted HDL, or HDL apolipoprotein peptides on the inflammatory response and mortality in models of endotoxemia. In this regard, it has been proposed that one of the mechanisms by which HDL protect against sepsis may be mediated by its binding ability and/or neutralizing capacity on LPS, avoiding an excessive response of the immune system. Thus, increasing blood levels of HDL and/or parenteral HDL administration may represent a new anti-inflammatory tool for managing septic states in humans.

The srbi gene encodes a lipoprotein receptor with high affinity for high density lipoprotein that is mainly expressed in the liver and in steroidogenic tissues. Disruption of this gene in mice and mutations in humans lead to alterations in lipoprotein metabolism and/or fertility. During murine development, scavenger receptor class B member I (SR-BI) is present in the yolk sac and the placenta and is only expressed in the embryo itself late in gestation. In humans, it has been detected in trophoblast cells and placenta. Although the proportion of mice carrying a null mutation in SR-BI obtained from heterozygous intercrosses is lower than the expected by the Mendelian ratio, suggesting the involvement of this receptor in intrauterine development, the cause of this demise has remained unknown. In this work, we show that embryos lacking SR-BI exhibit a high prevalence of exencephaly with a sex bias toward females. Immunolocalization studies confirmed that SR-BI is not expressed in the embryo at early stages of development and allowed a more detailed description of its localization in the cells that mediate maternal–fetal transport of nutrients. SR-BI-null embryos contain less cholesterol than their wild-type littermates, suggesting the involvement of SR-BI in materno-fetal cholesterol transport. Newborn SR-BI-deficient pups exhibit intrauterine growth restriction, suggesting that this receptor is also important for fetal growth. Altogether, the results of our work suggest that the presence of SR-BI in extraembryonic tissues is involved in the maternal–fetal transport of cholesterol and/or other lipids with a role during neural tube closure and fetal growth.

Cysteine-rich secretory protein 2 (CRISP2) is a testicular sperm protein proposed to be involved in fertilization. With the aim of examining the relevance of CRISP2 for fertility and its potential use as a target for contraception, in the present work, male and female rats were immunized with recombinant CRISP2 coupled to maltose-binding protein (MBP) and evaluated for their subsequent fertility. As controls, animals were injected with either MBP or recombinant CRISP1. Enzyme-linked immunosorbent assay of sera collected at different intervals after immunization indicated that CRISP2 immunization raised specific antibodies in both sexes, with levels that increased as a function of time. Western blot studies revealed that anti-CRISP2 sera were capable of recognizing CRISP2 in testicular, epididymal, and sperm extracts, whereas histological studies showed no evidence of autoimmune orchitis or epididymitis. Indirect immunofluorescence experiments revealed the ability of anti-CRISP2 sera to recognize the native sperm protein in fresh, capacitated, and ionophore-induced acrosome-reacted cells. Moreover, anti-CRISP2 sera significantly inhibited the sperm ability to penetrate zona-free eggs, confirming the role of CRISP2 in rat gamete fusion. In spite of the presence of circulating anti-CRISP2 antibodies capable of inhibiting the sperm fertilizing ability, mating studies revealed no effects of CRISP2 immunization on male or female fertility, in contrast to the significant inhibition observed in both sexes in animals injected with CRISP1. Together, these observations indicated the immunogenic properties of testicular CRISP2 but do not support CRISP2 as a target for immunocontraception or as a molecule responsible for generating autoimmune orchitis or immunoinfertility. Fil: Weigel Muñoz, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Ernesto, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Bluguermann, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cohen, Debora Juana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Busso, Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Battistone, Maria Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina

Since 1964, the hypothesis of Pedersen has been used to explain fetal macrosomia observed in gestational diabetes mellitus (GDM), by a mechanism involving maternal hyperglycemia--fetal hyperglycemia--fetal hyperinsulinemia. However, since the 1980-89 decade, it is known that pregnant women with pre-gestational overweight not suffering from GDM still have a higher frequency of fetal macrosomia. Furthermore, pregnant women with GDM, despite being subjected to optimal glycemic control, still show unacceptably high frequencies of fetal macrosomia, a phenomenon that is concentrated in pregnancies with overweight or obesity prior to pregnancy. If glucose is not the single nutrient responsible for fetal macrosomia in pregnant women with gestational diabetes that undergo strict glycemic control, other nutrients may cause excessive fetal growth in pre-pregnancy overweight mothers. In this review, we propose that triglycerides (TG) could be responsible for this accelerated fetal growth. If this hypothesis is validated in animal models and clinical studies, then normal and pathological ranges of TG should be defined, and monitoring of triglyceride levels during pregnancy should be advised as a possible new alternative, besides a good glycemic control, for the management of fetal macrosomia in GDM women with overweight prior to pregnancy.

Apolipoprotein A-I (apo A-I) is the main protein component of plasma high-density lipoproteins (HDL) and a key determinant of HDL cholesterol levels and metabolism. The relevance of HDL in controlling the traffic of cholesterol from plasma into bile has been partially addressed. The aim of this study was to evaluate the role of apo A-I expression in controlling the secretion of biliary lipids as well as the risk of gallstone disease in vivo.We evaluated biliary lipid secretion and bile acid homeostasis in mice deficient for apo A-I compared with wild-type animals when fed with low- or high-cholesterol diets. In addition, we assessed the importance of murine apoA-I expression for gallstone formation after feeding a lithogenic diet.Bile acid pool size and faecal excretion were within the normal range in chow- and cholesterol-fed apo A-I knockout (KO) mice. Basal biliary cholesterol secretion was comparable and increased similarly in both murine strains after cholesterol feeding. Lithogenic diet-fed apo A-I KO mice exhibited an impaired hypercholesterolaemic response owing to a lower increase in cholesterol levels transported in large lipoproteins. However, the lack of apo A-I expression did not affect biliary cholesterol precipitation or gallstone formation in lithogenic diet-fed mice.These findings indicate that biliary lipid secretion, bile acid metabolism and gallstone formation are independent of apo A-I expression and plasma HDL cholesterol levels in mice.

Niemann Pick C2 (NPC2) and NPC1 proteins function cooperatively to catalyze cholesterol efflux from lysosomes. NPC1 is expressed in ovarian cells and female NPC1 mice are infertile. This work addressed for the first time the localization and function of murine NPC2 protein in the ovary. Ovarian NPC2 was localized to theca and luteal cells, which use cholesterol as a substrate to produce estradiol and progesterone, respectively. NPC2 deficient (NPC2-/-) females had abnormal estrous cycles and were infertile, with normal folliculogenesis until the antral stage, but a complete absence of corpora lutea and many zonae pellucidae remnants, indicative of anovulation. Serum estradiol was reduced and ovarian cholesterol was accumulated in NPC2-/- mice, suggesting a defect in cholesterol export from intracellular stores. After superovulation, NPC2-/- mice ovulated less eggs than their wild type littermates, showed ovaries with less corpora lutea and numerous unruptured follicles, and lower serum progesterone concentration. Together, these results suggest that NPC2 participates in the traffic of ovarian cholesterol required to provide the substrate for steroid synthesis and support follicle maturation, ovulation and luteinization.

Caspases, cystein proteases traditionally related to programmed cell death, have recently been found to be involved in vital processes such as cell proliferation, adhesion and differentiation. Although caspases are expressed in mouse embryos before the blastocyst stage, their role is unclear, since apoptosis does not occur significantly before implantation. In this work, we have used mouse preimplantation development as a model to evaluate the existence of non-lethal caspase activities. The use of specific caspase inhibitors during in vitro embryo culture showed that caspase 8 activity, but not caspase 2 or 9, was relevant for development. The inhibition of caspase 8 affected the compaction of morulae and the progression to the blastocyst stage. In agreement with these results, caspase 8 was expressed in mouse embryos, as shown by indirect immunofluorescence and RT-PCR. An in silico approach was used to find putative caspase targets expressed in mouse preimplantation embryos. Large-scale management of sequence data from mouse embryos was used to predict caspase substrates by tools matrix-based on known cleavage sites. A total of 510 potential caspase targets expressed in mouse embryos were identified by this procedure. The functional characterization of these proteins by Gene Onthology associations showed that many of these putative caspase targets were previously related to non-apoptotic functions and only 63 had been previously reported to be actually cleaved by caspases. Interestingly, eleven knockout mice models for caspase substrates identified in our work, i.e. catenin alpha and beta, geminin, pescadillo, calpain-2, have preimplantation lethal phenotypes. This work supports the involvement of caspases in vital functions during mouse preimplantation development and proposes a model in which the regulated cleavage of caspase substrates could account for this role.

Epididymal protein CRISP1 participates in rat and mouse gamete fusion through its interaction with complementary sites on the egg surface. Based on in vivo observations, in the present study we investigated the possibility that CRISP1 plays an additional role in the sperm-zona pellucida (ZP) interaction that precedes gamete fusion. In vitro fertilization experiments using zona-intact rat and mouse eggs indicated that the presence of either an antibody against rat CRISP1 (anti-CRISP1) or rat native CRISP1 (rCRISP1) during gamete co-incubation produced a significant decrease in the percentage of fertilized eggs. However, differently to that expected for a protein involved in gamete fusion, no accumulation of perivitelline sperm was observed, suggesting that the inhibitions occurred at the sperm-ZP interaction level. Bacterially expressed recombinant CRISP1 (recCRISP1) also significantly inhibited egg fertilization. In this case, however, an increase in the number of perivitelline sperm was observed. Subsequent experiments evaluating the effect of anti-CRISP1 or rCRISP1 on the number of sperm bound per egg indicated that the protein is involved in the initial step of sperm-ZP binding. In agreement with these functional studies, indirect immunofluorescence experiments revealed that although rCRISP1 is capable of binding to both the ZP and the oolema, recCRISP1 only binds to the egg surface. The finding that deglycosylated rCRISP1 behaves as the untreated protein, whereas the heat-denatured rCRISP1 associated only with the oolema, indicates that the protein ZP-binding ability resides in the conformation rather than in the glycosydic portion of the molecule. The interaction between rCRISP1 and the ZP reproduces the sperm-ZP-binding behavior, as judged by the failure of the protein to interact with the ZP of fertilized eggs. Together, these results support the idea that CRISP1 participates not only in sperm-egg fusion but also in the prior stage of sperm-ZP interaction.

Rat protein DE is an androgen-dependent cysteine-rich secretory protein (CRISP) synthesized by proximal epididymal regions. DE, also known as CRISP-1, is localized on the equatorial segment of acrosome-reacted spermatozoa and participates in gamete fusion through binding to egg complementary sites. Immunization of rats with DE inhibits fertility and sperm fusion ability, suggesting that DE represents a good epididymal contraceptive target. Recombinant DE fragments and synthetic peptides revealed that DE binds to the egg via a 12-amino acid region of an evolutionarily conserved motif, Signature 2 (S2). The ability of other CRISP to bind to the rat egg was correlated with their S2 amino acid sequences. Although testicular protein Tpx-1 (CRISP-2) was capable of binding to rodent eggs, human epididymal AEG-related protein (ARP) and helothermine (from lizard saliva) were not. The S2 region presented only two substitutions in Tpx-1 and four in ARP and helothermine, compared with the DE S2, suggesting that this amino acid sequence was relevant for egg interaction. Studies with Tpx-1 and anti-Tpx-1 revealed the participation of this protein in gamete fusion through binding to complementary sites in the egg. In competition studies, DE reduced binding of Tpx-1 dose-dependently, indicating that both CRISP share the egg complementary sites. That anti-DE and anti-Tpx-1 inhibit sperm-egg fusion while recognizing only the corresponding proteins, suggests functional cooperation between these homologous CRISP to ensure fertilization success. These results increase our understanding of the molecular mechanisms of gamete fusion and contribute to the development of new and safer fertility regulating methods. Fil: Cohen, Debora Juana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Da Ros, Vanina Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Busso. Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Ellerman, Diego Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Maldera, Julieta Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Goldweic, Nadia Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina

s / Placenta 36 (2015) 469e521 498 Conclusions: These results support a role for VIP during mouse early pregnancy pointing to TGC among the major local sources of the neuropeptide. VIP deficiency is reflected by TGC expressing an altered functional and invasive phenotype with increased VPAC2 expression. PA.32. INVOLVEMENT OF HDL RECEPTOR SR-BI-MEDIATED VITAMIN E UPTAKE IN MURINE NEURAL TUBE CLOSURE N. Santander , D. P erez , G. Echeverria , C. Mendoza , K. Cautivo , A. Rigotti , D. Busso . Department of Nutrition, Diabetes and Metabolism, Chile; Center for Molecular Nutrition and Chronic Diseases, Medical School, Pontifical University of Chile, Santiago, Chile SR-BI, the main HDL receptor, mediates the cellular uptake of cholesterol and vitamin E. SR-BI is present in trophoblast giants cells (TGC) during early pregnancy and 50% SR-BI-deficient (SR-BI / ) embryos die due to defective neural tube closure (NTD). Objectives: a) to compare vitamin E content and oxidative stress markers in SR-BI+/+ and SR-BI / TGC and embryos with and without NTD, b) to evaluate whether maternal vitamin E supplementation prevents NTD in SR-BI / embryos and compare vitamin E content in SR-BI+/+ and / embryos and TGC from chowand vitamin E-supplemented dams. Methods: Pregnant dams from SR-BI +/ intercrosses were fed a standard chow diet alone or supplementedwith 2000 UI vitamin E/kg. Embryos and TGC were recovered at E9.5 and snap frozen. Tissue homogenates were used to determine vitamin E by HPLC, reactive oxygen species (ROS) using dihydrodichlorofluorescein diacetate, and oxidative stress-related genes by qPCR. Yolk sacs were used for PCR genotyping. Results: Vitamin E content in SR-BI-/embryos was 5-fold lower than in SR-BI+/+ embryos (p

Objective To evaluate the immunocontraceptive properties of recombinant DE, a sperm epididymal protein involved in fertilization, via an experimental study in rats as a critical step toward the development of a human immunocontraceptive. Design In vivo study in rats. Setting Animal care facility of an academic research center. Animal(s) Seventy-four 90-day-old Wistar male and female rats distributed into three groups. Intervention(s) Animals received five injections (intramuscular and subcutaneous) of recombinant DE (recDE), native DE (nDE), or MBP (maltose-binding protein). At various times, animals were anesthetized and bled. Main Outcome Measure(s) Anti-DE levels and tissue specificity of sera were evaluated by enzyme-linked immunosorbent assay (ELISA) and Western blot, respectively. Fertility was analyzed by natural mating. The testes and epididymides were analyzed by histology. Result(s) Recombinant DE raised an immune response with the same kinetics and higher anti-DE levels than that elicited by nDE. Sera against recDE recognized epitopes of DE that were different from those recognized by anti-nDE sera but specifically reacted with DE in epididymis and sperm without cross-reacting with other tissues tested. Male and female recDE-injected animals presented a statistically significant reduction in their fertility with no evidence of pathologic effects. Conclusion(s) Recombinant DE is able to both elicit a specific immune response and inhibit male and female fertility, supporting the use of this sperm epididymal protein for the development of an immunocontraceptive approach.

Testicular protein Tpx-1, also known as CRISP-2, is a cysteine-rich secretory protein specifically expressed in the male reproductive tract. Since the information available on the human protein is limited to the identification and expression of its gene, in this work we have studied the presence and localization of human Tpx-1 (TPX1) in sperm, its fate after capacitation and acrosome reaction (AR), and its possible involvement in gamete interaction. Indirect immunofluorescence studies revealed the absence of significant staining in live or fixed non-permeabilized sperm, in contrast to a clear labelling in the acrosomal region of permeabilized sperm. These results, together with complementary evidence from protein extraction procedures strongly support that TPX1 would be mainly an intra-acrosomal protein in fresh sperm. After in vitro capacitation and ionophore-induced AR, TPX1 remained associated with the equatorial segment of the acrosome. The lack of differences in the electrophoretic mobility of TPX1 before and after capacitation and AR indicates that the protein would not undergo proteolytical modifications during these processes. The possible involvement of TPX1 in gamete interaction was evaluated by the hamster oocyte penetration test. The presence of anti-TPX1 during gamete co-incubation produced a significant and dose-dependent inhibition in the percentage of penetrated zona-free hamster oocytes without affecting sperm motility, the AR or sperm binding to the oolema. Together, these results indicate that human TPX1 would be a component of the sperm acrosome that remains associated with sperm after capacitation and AR, and is relevant for sperm-oocyte interaction. Fil: Busso, Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cohen, Debora Juana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Hayashi, M.. Hokkaido University Graduate School Of Medicine; Japón Fil: Kasahara, M.. Hokkaido University Graduate School Of Medicine; Japón Fil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina

Mammalian spermatozoa that leave the testis do not have the ability to recognize and fertilize an egg; they require a maturation process that takes place while they are passing through the epididymis. Transit through this organ confers on sperm the capacity for vigorous motility, and the ability to become capacitated, undergo the acrosome reaction, interact with the zona pellucida (ZP), and bind to and fuse with the egg plasma membrane (Cooper, 1986; Bedford, 1990; Yanagimachi, 1994).

Rat epididymal glycoprotein DE associates with the dorsal region of the sperm head during sperm maturation, migrates to the equatorial segment (ES) with the acrosome reaction (AR), and is involved in gamete membrane fusion. In the present study we examined the association of DE with the sperm surface and the relationship of this interaction with the behavior and function of the protein. Cloning and sequencing of DE revealed a lack of hydrophobic domains and the presence of 16 cysteine residues in the molecule. Experiments in which cauda epididymal sperm were subjected to different extraction procedures indicated that while most of the protein is removable from sperm by mild ionic strength, a low amount of DE, resistant to even 2 M NaCl, can be completely extracted by agents that remove integral proteins. However, the lack of hydrophobic domains in the molecule and the failure of DE to interact with liposomes, does not support a direct insertion of the protein into the lipid bilayer. These results, and the complete extraction of the tightly bound protein by dithiothreitol, suggest that this population would correspond to a peripheral protein bound to a membrane component by strong noncovalent interactions that involve disulfide bonds. While ELISA experiments showed that no protein could be extracted by NaCl from capacitated sperm, indirect immunofluorescence studies revealed the ability of the NaCl-resistant protein to migrate to the ES. Together, these results support the existence of two populations of DE: a major, loosely bound population that is released during capacitation, and a minor strongly bound population that remains after capacitation, migrates to the ES with the AR, and thus would correspond to the one with a role in gamete fusion Fil: Cohen, Debora Juana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Rochwerger, Leonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Ellerman, Diego Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Morgenfeld, Mauro Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Busso, Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina

Protein DE (32 kDa) associates with sperm during epididymal maturation and participates in sperm-egg fusion through its binding to complementary sites on the egg surface. In the present work we investigated the participation of DE in two mechanisms probably involved in egg activation: the ability of DE to trigger activation by its interaction with the binding sites on the egg surface (receptor model) and its ability to regulate intracellular calcium channels (sperm factor model). The incubation of eggs with DE did not promote activation parameters such as calcium oscillations or meiosis resumption. Secondly, microinjection of DE into eggs was ineffective in either eliciting calcium release or modifying oscillations induced by an activating sperm extract. Together, these results argue against the participation of DE in egg activation, restricting the activity of this protein and its egg binding sites to the sperm-egg fusion process. Fil: Busso, D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Cohen, Debora Juana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Da Ros, Vanina Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Fissore, R.. University of Massachussets; Estados Unidos Fil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina