Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Dynamic localization of SPE-9 in sperm: a protein required for sperm-oocyte interactions in Caenorhabditis elegans
Sonia Zannoni, Steven W L'Hernault, Andrew W Singson
BMC Developmental Biology , 2003, DOI: 10.1186/1471-213x-3-10
Abstract: We obtained specific antisera directed against different regions of SPE-9 in order to determine its subcellular localization. SPE-9 is segregated to spermatids with a pattern that is consistent with localization to the plasma membrane. During spermiogenesis, SPE-9 becomes localized to spiky projections that coalesce to form a pseudopod. This leads to an accumulation of SPE-9 on the pseudopod of mature sperm.The wild type localization patterns of SPE-9 provide further evidence that like the sperm of other species, C. elegans sperm have molecularly mosaic and dynamic regions. SPE-9 is redistributed by what is likely to be a novel mechanism that is very fast (~5 minutes) and is coincident with dramatic rearrangements in the major sperm protein cytoskeleton. We conclude that SPE-9 ends up in a location on mature sperm where it can function during fertilization and this localization defines the sperm region required for these interactions.Successful fertilization requires a precise series of cell-cell interactions between gametes [reviewed by [1-6]]. The molecules that mediate these cell-cell interactions need to be present in sperm and oocytes at the right time and place to carry out their functions. Changes in the cellular distribution of gamete proteins could also regulate activity and access to other interacting molecules. Sperm in particular are highly polarized cells with functionally and morphologically distinct surface domains [7,8]. These domains represent the compartmentalization of functions such as motility, energy production and sperm-egg cell surface interacting regions [9]. Many sperm molecules display a restricted distribution that corresponds to various sperm regions and this distribution is likely to be critical for their function [10,11].The nematode Caenorhabditis elegans is an excellent model system for the study of the molecular mechanisms of fertilization [12,13]. Nematode sperm, like sperm from most species, are highly polarized cells. Unlike flag
Seminal Fluid Affects Sperm Viability in a Cricket  [PDF]
Leigh W. Simmons,Maxine Beveridge
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017975
Abstract: Recent studies have suggested that males may vary the quality of their ejaculates in response to sperm competition, although the mechanisms by which they do so remain unclear. The viability of sperm is an important aspect of ejaculate quality that determines competitive fertilization success in the field cricket Teleogryllus oceanicus. Using in vitro mixtures of sperm and seminal fluid from pairs of male crickets, we show that seminal fluid can affect the viability of sperm in this species. We found that males who invest greatly in the viability of their own sperm can enhance the viability of rival sperm, providing the opportunity for males to exploit the investments in sperm competition made by their rivals. Transitive effects of seminal fluids across the ejaculates of different males are expected to have important implications for the dynamics of male investments in sperm competition.
A Heterogeneous Mixture of F-Series Prostaglandins Promotes Sperm Guidance in the Caenorhabditis elegans Reproductive Tract  [PDF]
Hieu D. Hoang,Jeevan K. Prasain,Dixon Dorand,Michael A. Miller
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003271
Abstract: The mechanisms that guide motile sperm through the female reproductive tract to oocytes are not well understood. We have shown that Caenorhabditis elegans oocytes synthesize sperm guiding F-series prostaglandins from polyunsaturated fatty acid (PUFA) precursors provided in yolk lipoprotein complexes. Here we use genetics and electrospray ionization tandem mass spectrometry to partially delineate F-series prostaglandin metabolism pathways. We show that omega-6 and omega-3 PUFAs, including arachidonic and eicosapentaenoic acids, are converted into more than 10 structurally related F-series prostaglandins, which function collectively and largely redundantly to promote sperm guidance. Disruption of omega-3 PUFA synthesis triggers compensatory up-regulation of prostaglandins derived from omega-6 PUFAs. C. elegans F-series prostaglandin synthesis involves biochemical mechanisms distinct from those in mammalian cyclooxygenase-dependent pathways, yet PGF2α stereoisomers are still synthesized. A comparison of F-series prostaglandins in C. elegans and mouse tissues reveals shared features. Finally, we show that a conserved cytochrome P450 enzyme, whose human homolog is implicated in Bietti's Crystalline Dystrophy, negatively regulates prostaglandin synthesis. These results support the model that multiple cyclooxygenase-independent prostaglandins function together to promote sperm motility important for fertilization. This cyclooxygenase-independent pathway for F-series synthesis may be conserved.
Relationship between seminal malondialdehyde levels and sperm quality in fertile and infertile men
Colagar, Abasalt Hosseinzadeh;Pouramir, Mehdi;Marzony, Eisa Tahmasbpour;Jorsaraei, Sayed Gholam Ali;
Brazilian Archives of Biology and Technology , 2009, DOI: 10.1590/S1516-89132009000600010
Abstract: the aim of this study was to determine the level of malondialdehyde in seminal plasma of fertile and infertile men and investigate its relationship with sperm quality. results showed that the mean of ± s.d. mda concentration in seminal plasma of infertile men (0.94 ± 0.28 nmol/ml) was significantly higher than fertile men (0.65 ± 0.17 nmol/ml) (p value< 0.001), and had negative relationship with sperm count, motility and morphology. therefore it could be concluded that increase in lipid peroxidation was associated with sperm membrane destructed and high level of mda.
Sperm Bundles in the Seminal Vesicles of Sexually Mature Lasius Ant Males  [PDF]
William E. Burnett, Jürgen Heinze
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093383
Abstract: In many insects, sperm cells are produced in bundles with their heads being held together by a glycoprotein matrix secreted by a cyst cell. Mature sperm cells in the seminal vesicles are usually free, but in sawflies and several other insects, such structures (spermatodesmata) remain intact and sperm cells may be ejaculated as bundles. Here we report the occurrence of spermatodesmata in mature males of the ant Lasius pallitarsis. Microscopic investigations of the abdominal contents of males immediately prior to their nuptial flights showed that the anterior ends of numerous sperm cells were embedded in an oval-shaped 20 by 30 micrometer extracellular fibrous cap. Individual sperm ranged in length from 55 to 75 micrometers with an average overall length of 65 micrometers. The bulb-shaped heads of the sperm were relatively small, only about 1.5 micrometers in length and about 1.1 micrometers in diameter. The diameter of the sperm tails was approximately 1 micrometer. Observations of live preparations of the spermatodesmata showed increasingly active undulating wave-like movement of the sperm tails as the slide preparations aged. This appears to be the first case of sperm bundles being present in the seminal vesicles of mature ant males – males that are immediately poised to complete their nuptial mating flight.
Effect of Seminal Vesicles and Dithiotritol (Dtt) on Stability of Sperm Chromatin
M Mardani,MH Nasr-Esfahani,SH Razavi,I Shamayely-Yeganeh
Journal of Shahid Sadoughi University of Medical Sciences , 2005,
Abstract: Introduction: Different studies have shown that there is no relation between sperm chromatin stability and fertilization rate in both IVF and ICSI patients. However, the relation between SDS tests, as a detergent, along with DTT as reducer of disulphide bridges has not been studied so far in ICSI patients. Since different concentrations of DTT can induce different degrees of sperm chromatin decondensation, the aim of this study was to evaluate the effect of different concentrations of DTT on sperm chromatin decondensation in IVF and ICSI cases. Methods: During this study, 85 patients were divided into two groups according to their treatment procedure (IVF or ICSI).Semen samples of each patient was evaluated for sperm chromatin tests including SDS, SDS+EDTA & SDS+DTT for assessment of free thiole groups level (-SH), amount of non covalent bond between Zn and thioles(-SH Zn SH-) and levels of disulfide bond (-S-S-) in sperm chromatin, respectively. In this study, seminal fructose concentration, corrected seminal fructose level and true corrected fructose level as indicators of seminal vesicle function on sperm chromatin stability were assessed. Results: No correlation was observed between any of the above tests and rate of fertilization, both in IVF and ICSI cases. However, in IVF patients, a significant correlation was observed between SDS, SDS+DTT test and seminal fructose level, while in ICSI patients, only a significant correlation was observed between SDS+DTT and corrected or true fructose concentration. Conclusion: Since no correlation was observed between sperm chromatin test and fertilization rate, it is suggested that the chromatin status of these samples are adequate for fertilization to take place and extent of disulphide bridges has no effect on fertilization rate. However, the amount of disulphide bound present in sperms of ICSI and IVF patients are different, and this difference is related to seminal vesicle performance in these patients.
Oxidants and Anti-Oxidants in Turbot Seminal Plasma and Their Effects on Sperm Quality Oxidants and Anti-Oxidants in Turbot Seminal Plasma and Their Effects on Sperm Quality  [PDF]
HAN Mingming,DING Fuhong,MENG Zhen,LEI Jilin
- , 2015,
Abstract: In this research, the concentration and activity of oxidants and anti-oxidants in turbot semen, and their effects on sperm quality were studied. The results showed that superoxide dismutase(SOD), catalase, glutathione reductase(GR), uric acid, vitamin E(VE) and vitamin C(VC) were more abundant in seminal plasma than in spermatozoa. The variation for each of them was specific. In seminal plasma, the activity of SOD and GR increased from November 15, November 30 to December 15, and then decreased on December 30. The concentrations of both VC and uric acid decreased during the first 3 sampling times and increased on December 30. The oxidants in seminal plasma accumulated to the highest on December 30. Lactic acid(LA) and ATP levels decreased to the lowest on December 30. The correlation analysis showed that GR had the significant positive relevance to sperm motility and VSL/VCL, while ·OH had negative relevance to them
E1 Ubiquitin-Activating Enzyme UBA-1 Plays Multiple Roles throughout C. elegans Development  [PDF]
Madhura Kulkarni,Harold E. Smith
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000131
Abstract: Poly-ubiquitination of target proteins typically marks them for destruction via the proteasome and provides an essential mechanism for the dynamic control of protein levels. The E1 ubiquitin-activating enzyme lies at the apex of the ubiquitination cascade, and its activity is necessary for all subsequent steps in the reaction. We have isolated a temperature-sensitive mutation in the Caenorhabditis elegans uba-1 gene, which encodes the sole E1 enzyme in this organism. Manipulation of UBA-1 activity at different developmental stages reveals a variety of functions for ubiquitination, including novel roles in sperm fertility, control of body size, and sex-specific development. Levels of ubiquitin conjugates are substantially reduced in the mutant, consistent with reduced E1 activity. The uba-1 mutation causes delays in meiotic progression in the early embryo, a process that is known to be regulated by ubiquitin-mediated proteolysis. The uba-1 mutation also demonstrates synthetic lethal interactions with alleles of the anaphase-promoting complex, an E3 ubiquitin ligase. The uba-1 mutation provides a sensitized genetic background for identifying new in vivo functions for downstream components of the ubiquitin enzyme cascade, and it is one of the first conditional mutations reported for the essential E1 enzyme in a metazoan animal model.
Correlation between sperm characteristics and testosterone in bovine seminal plasma by direct radioimmunoassay
Souza, Luiz Waldemar de Oliveira;Andrade, André Furugen Cesar;Celeghini, Eneiva Carla Carvalho;Negr?o, Jo?o Alberto;Arruda, Rubens Paes de;
Revista Brasileira de Zootecnia , 2011, DOI: 10.1590/S1516-35982011001200015
Abstract: the objectives of this study were to validate a non-extractive ria for seminal testosterone and quantify the hormone using a solid-phase commercial kit, and study the correlation between testosterone in seminal plasma and sperm characteristics. parallelism showed a correlation index r = 0.992 (y = -5.47 + 1.073x; r2 = 0.985), indicating that the non-extractive method presented is indicated particularly for assessment of testosterone when establishing comparisons between samples. overall mean (±sd) of testosterone level was 0.60±0.65 ng/ml. correlation was only found between the seminal concentrations of testosterone and ph of the semen.
Pseudomonas aeruginosa Suppresses Host Immunity by Activating the DAF-2 Insulin-Like Signaling Pathway in Caenorhabditis elegans  [PDF]
Eric A. Evans,Trupti Kawli,Man-Wah Tan
PLOS Pathogens , 2008, DOI: 10.1371/journal.ppat.1000175
Abstract: Some pathogens have evolved mechanisms to overcome host immune defenses by inhibiting host defense signaling pathways and suppressing the expression of host defense effectors. We present evidence that Pseudomonas aeruginosa is able to suppress the expression of a subset of immune defense genes in the animal host Caenorhabditis elegans by activating the DAF-2/DAF-16 insulin-like signaling pathway. The DAF-2/DAF-16 pathway is important for the regulation of many aspects of organismal physiology, including metabolism, stress response, longevity, and immune function. We show that intestinal expression of DAF-16 is required for resistance to P. aeruginosa and that the suppression of immune defense genes is dependent on the insulin-like receptor DAF-2 and the FOXO transcription factor DAF-16. By visualizing the subcellular localization of DAF-16::GFP fusion protein in live animals during infection, we show that P. aeruginosa–mediated downregulation of a subset of immune genes is associated with the ability to translocate DAF-16 from the nuclei of intestinal cells. Suppression of DAF-16 is mediated by an insulin-like peptide, INS-7, which functions upstream of DAF-2. Both the inhibition of DAF-16 and downregulation of DAF-16–regulated genes, such as thn-2, lys-7, and spp-1, require the P. aeruginosa two-component response regulator GacA and the quorum-sensing regulators LasR and RhlR and are not observed during infection with Salmonella typhimurium or Enterococcus faecalis. Our results reveal a new mechanism by which P. aeruginosa suppresses host immune defense.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.