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Sperm plasma membrane

About: Sperm plasma membrane is a research topic. Over the lifetime, 1016 publications have been published within this topic receiving 49964 citations.


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Journal Article
TL;DR: The type of modification in the GPI anchor, special environment on membranes, and relative charge of host plasma membrane to the charge of PLC may be the factors that are responsible for the differential action of two enzymes.
Abstract: Phospholipase C (PLC) was purified to homogeneity from the culture filtrate of Bacillus cereus (65-fold, 540 U/mg protein) and B. thuringiensis (76-fold, 306 U/mg protein) by conventional techniques of enzyme purification. The purified enzymes have the molecular mass of 34 kDa and 38 kDa respectively, as determined by SDS-PAGE. Both the PLCs exhibited identical sensitivity to pH, temperature, cations, anions and inhibitors like glutathione and p-chloromercuribenzoate. PLC-Bc showed a preference for phosphatidylinositol, while PLC-Bt favoured phosphatidylcholine as the substrate. Although both the enzymes were able to hydrolyze pure phosphatidylinositol, distinct differences were observed in their activity on phosphatidylinositol-anchored membrane proteins. PLC-Bc cleaved and released alkaline phosphatase, a GPI-anchored marker enzyme from microsomal membranes to a greater extent, than PLC-Bt. Experiments with sperm membranes, followed by SDS-PAGE revealed that the pattern of proteins released from their GPI-anchors by PLC-Bc and PLC-Bt were dissimilar. Although some proteins were cleaved in common by both PLCs, some others including a prominent 57 kDa protein were resistant to PLC-Bt, but sensitive to cleavage by PLC-Bc. The type of modification in the GPI anchor, special environment on membranes, and relative charge of host plasma membrane to the charge of PLC may be the factors that are responsible for the differential action of two enzymes.

2 citations

Patent
02 May 2008
TL;DR: In this article, the authors provided methods and compositions for the generation of transgenic animals by intracytoplasmic sperm injection (ICSI) by treating isolated spermatozoa with one of the group consisting of: lysolecithin, digitonin, sonication, and piezo pulses to disrupt or remove the sperm plasma membrane.
Abstract: Methods and compositions for the generation of transgenic animals by intracytoplasmic sperm injection (ICSI) are provided herein In some embodiments, such methods can include: treating isolated spermatozoa with one of the group consisting of: lysolecithin, digitonin, sonication, and piezo pulses to disrupt or remove the sperm plasma membrane; contacting a sperm thus treated with a nucleic acid mixture that includes a nucleic acid containing a transgene to form a composition; and introducing the composition into an unfertilized oocyte of the same species to form a transgenic embryo In some embodiments, the nucleic acid mixture includes a nucleic acid containing a transgene flanked by two terminal repeats and one of the group consisting of: a transposase polypeptide and a nucleotide sequence encoding a transposase In some embodiments, the transposase is a piggyBac transposase

2 citations

Journal ArticleDOI
TL;DR: This month, JARG features a series of papers pertaining to male infertility and sperm physiology and alerts readership generally, and those fertilization aficionados here and beyond, to the demonstration of plausible functional cooperativity for the fusion of human sperm and eggs.
Abstract: Two year ago, an article appeared in JARG documenting and confirming for the first time a fast block to polyspermy in the human (Mio et al., Possible mechanism of polyspermy block in human oocytes observed by time-lapse cinematography, 2012 J Assist Reprod Genet, 29:951–956, DOI 10.1007/s10815-012-9815). That the fusion of sperm and egg plasma membranes launches the program of development from which organisms arise remains a central tenet in plant and animal biology. And, as has been appreciated for many years, the ability of the oocyte to fend off supernumerary sperm and assure a diploid composition of chromosomes in the resulting zygote relies on the establishment of a block to polyspermy through mechanisms that we now understand to be of both fast and slow varieties. While the existence of fast and slow blocks to polyspermy has been well documented in divergent metazoan organisms, controversy remained as to the presence of a fast block in the human oocyte—that is, until the publication of Mio and colleagues—mainly because of the lack of imaging strategies permitting the tracking multiple sperm during the process of in vitro fertilization (IVF). Even though the problems associated with polyspermy persist in the practice of human ARTs, and the introduction of ICSI in the 1990s has greatly reduced the incidence of this type of genetic imbalance during the generation of human embryos, it remains a serious problem for clinics that continue to use IVF in their daily practices. Most scientists and clinicians would argue for the continuation of investigations into the basic mechanisms underscoring human fertilization even in the face of opposition from governments and societies uncomfortable with such lines of research. At the heart of all such studies has been the lingering fascination with the various fissions and fusions featured at the level of the plasma membrane of gametes. Whether your fancy be the acrosome reaction, intermingling of sperm and egg membranes, or the burst of exocytosis of cortical granules that stages the so-called slow block to polyspermy, the precision and celerity of membrane dynamics that defines successful fertilization stands alone as one of the most spectacular biological phenomena with which we remain obsessed—and for good reason! So important was the discovery of the molecular machinery that guides membranes to and through their appointments with fission and fusion that it was recognized as worthy of the 2013 Nobel Prize in Physiology and Medicine. It turns out, and not so surprisingly, that proteins have evolved for the expressed purpose of consummating the intimate contacts made between a variety of apposed membranes (be they of cells or their internal organelles) effecting true fusion. Viruses have been known for years to deploy such molecules, also known as fusogens, to invade cells and more in line with the world of reproductive medicine are fusogens believed to participate in the formation of syncytial trophoblast. A central candidate by the name of SYNCYTIN 1 is the gene product now widely suspected to mediate this aspect of placental development in the human and other species. This month, JARG features a series of papers pertaining to male infertility and sperm physiology. At the top of our list is the paper by Bjerregaard and colleagues from Copenhagen entitled “Syncytin-1 and its receptor is present in human gametes” (10.1007/s10815-014-0224-1). This work alerts our readership generally, and those fertilization aficionados here and beyond, to the demonstration of plausible functional cooperativity for the fusion of human sperm and eggs. Drawing upon the sensitivity qRT-PCR, both sperm specific expression of SYNCYTIN 1 and oocyte-specific expression of the syncytin receptor ASCT-2 mRNAs are documented, positioning these candidate fusion partners in a gender-specific context with clear implications for human ARTs. Moreover, the paper goes on to show a SYNCYTIN 1 pattern of protein expression in the equatorial segment of acrosome reacted sperm, the specialized domain of the sperm plasma membrane long recognized to be the site of sperm–egg fusion (see this month’s cover). What findings like this will mean to the daily practice of human ARTs and our understanding of failures in fertilization will require further experimentation and analysis. And, lest we forget, the identification of molecules mediating sperm–egg fusion may spark a new wave of contraceptive development research upon which even larger problems in reproductive health could be confronted for the overall benefit of humankind. Besides focusing on issues of male reproductive health this month, we are offering a template for discourse on the importance of reproductive science and medicine in the larger arena of scientific publishing. A study conducted by Duncan, Woodruff, and colleagues at Northwestern University prompts this topic with the following question: why is it that important papers in the field of reproduction rarely appear in the pages of the top journals? (Duncan et al., A small field for fertile science: the low visibility of reproductive science in high impact journals, 10.1007/s10815-014-0205-4 ). It comes as no great surprise that part of the answer derives from our small stature relative to other disciplines. And who could ignore the vestigial Victorian undercurrents that some societies have retained effectively thwarting advances in the fields of embryonic stem cells and regenerative medicine, as we have recognized in past issues of JARG. This paper, and the accompanying editorial (Woodruff et al., Keeping reproductive science visible, viable, and valuable—a call to rethink how we publish, 10.1007/s10815-014-0206-3), are timely contributions that we hope will prompt debate in the coming months, and we welcome your comments and insights into this matter. Along these lines, it is important to keep in mind what leaders in the scientific enterprise globally are perceiving for the future of scientific publishing. It is therefore of interest to note that last December, the day before accepting the 2013 Nobel prize in Physiology and Medicine, Randy Schekman from the University of California San Francisco aired his sentiments regarding the influence of high impact journals on the perceptions and practice of science. His commentary, entitled “How journals like Nature, Cell and Science are damaging science,” draws parallels between the dark side of incentivizing on the banking and finance industries and the practices top journals commonly deploy to advance themselves and the authors whose work bears their trademarks (www.theguardian.com/commentisfree/2013/dec/09/how-journals-nature-science-cell-damage-science). Schekman’s message draws upon what he believes has transformed the foundations of scientific integrity accorded to “discovery” into a business model rife with spurious and misleading commercial interests. From their lofty perch, he notes that these journals use the impact factor as more of a “gimmick” than a metric worthy of adoption in achieving academic rank or obtaining grants, a reliance that far too many promotion committees and funding agencies have become reliant upon for making big decisions for forging ahead within the purview of the biomedical research enterprise. He argues further that more and more of the very best publications are finding their way into open access journals and that this medium may return the field of scientific publication to a level of legitimacy it so deserves. Maybe our shared fascinations with the building blocks of human reproduction need a little more interdisciplinary fission, fusion, and recycling before moving discovery into the arena of translational medicine. Journals continue to influence funding agendas, academic advancement, and therapeutic direction for better or worse. The time has arrived for reproductive science to assume a larger identity that separates impact blurred by commercial interests or egos from the laudable goal of improving reproductive health for everyone.

2 citations

Journal ArticleDOI
TL;DR: It was concluded that the freezing–thawing procedure for human spermatozoa does not affect the expression of mannose‐ligand receptors and the dynamics of sperm pre‐fertilization processes.
Abstract: The aim of this study was to evaluate the change in the expression of mannose-ligand receptors following a freezing-thawing procedure, in order to assess its impact on sperm capacitation and acrosome reaction. Twenty semen samples were obtained from fertile donors. Sperm samples were divided into two equal volumes. One aliquot was cryopreserved and the other aliquot was incubated at 32°C. After 2 h the frozen sample was thawed and both samples were further incubated at 32°C to allow capacitation. Mannose receptors were examined following 4 and 22 h of incubation using a mannosylated-BSA-FITC probe. The expression of mannose-ligand receptors on the sperm plasma membrane was determined according to the fluorescence pattern: pattern I represents pre-capacitation, pattern II represents capacitated spermatozoa and pattern III represents acrosome-reacted spermatozoa. After 4 h incubation in capacitating medium, the percentages of patterns I, II and III were 90, 7 and 3% for fresh spermatozoa and 89, 8 and 3% for frozen-thawed spermatozoa, respectively (P > 0.05). Following 22 h of incubation, the percentages of patterns I, II and III were 84, 11 and 5 for fresh spermatozoa and 83, 11 and 6% for frozen-thawed spermatozoa, respectively (not significant at P > 0.05). The percentages of patterns II and III in fresh and frozen-thawed spermatozoa were increased by the same magnitude with longer incubation in the capacitating conditions. It was concluded that the freezing-thawing procedure for human spermatozoa does not affect the expression of mannose-ligand receptors and the dynamics of sperm pre-fertilization processes.

2 citations

Journal ArticleDOI
01 May 1998-Zygote
TL;DR: It is demonstrated that solubilised sperm PM protein inhibits the interaction of intact gametes as one might expect for receptor-ligand interactions, and the complement of sperm PM proteins appeared maximally effective at a calculated concentration of 690 microns/ml, providing a foundation for further studies with individual proteins.
Abstract: In vitro fertilisation (IVF) was used to assess the ability of solubilised sperm plasma membrane (PM) proteins to inhibit the interaction of intact gametes. This is a first step before evaluating the ability of individual isolated proteins to competitively inhibit sperm-oocyte interaction as part of the process of studying the molecular events of fertilisation. Porcine oocytes were aspirated from ovaries, matured for 48 h in Medium 199, and the zona pellucida (ZP) was removed by exposure to acid Tyrode's solution. ZP-free matured oocytes were exposed to 200-800 micrograms/ml sperm PM protein for 1 h prior to insemination and during gamete co-incubation. Twenty-four hours after insemination with 5 x 10(5) capacitated sperm/ml, the oocytes were fixed, stained and examined. Sperm PM protein clearly inhibited IVF in a concentration-dependent manner (r = -0.87). The inhibition index (I50%), representing the sperm PM protein concentration necessary to inhibit IVF to 50% of the control value, was 310 micrograms/ml. These results demonstrate that solubilised sperm PM protein inhibits the interaction of intact gametes as one might expect for receptor-ligand interactions. Furthermore, the complement of sperm PM proteins appeared maximally effective at a calculated concentration of 690 microns/ml, providing a foundation for further studies with individual proteins.

2 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
202121
202029
201920
201827
201726