717 research outputs found
Male sterile mutant casanova gives clues to mechanisms of sperm-egg interactions in Drosophila melanogaster.
No full textThe plasma membrane of the spermatozoa of Drosophila melanogaster contains two integral proteins with glycosidase activity, beta -N-acetylglucosaminidase and alpha -D-mannosidase. Biochemical analysis and ultrastructural cytochemistry of spermatozoa of the autosomal male sterile mutant casanova reveal that at least one of these enzymes, beta -N-acetylglucosaminidase, is crucial for sperm-egg interactions. casanova sperm are motile, morphologically normal, are transferred to the female at mating, but are unable to fertilize the eggs. The mutation was localised by deficiency mapping to the chromosomal region 95E8-F7. Fluorimetric assays showed that the mutant's sperm have the same level Of alpha -D-mannosidase activity as wild-type sperm, whereas beta -N-acetylglucosaminidase activity reaches only 51% of the wild-type level. The biochemical characteristics of alpha -D-mannosidase and of the residual beta -N-acetylglucosaminidase are the same as in wild-type males. Ultrastructural localization of the enzymes indicated that casanova spermatozoa lacks beta -N-acetylglucosaminidase on the plasma membrane covering the acrosome, whereas the location of this glycosidase at the terminal part of the sperm tail is indistinguishable from the wild-type situation. The results strongly suggest that in Drosophila the beta -N-acetylglucosaminidase of the plasma membrane covering the acrosome functions as a receptor for the glycoconjugates on the egg surface. We named the putative egg receptor EROS. This is the first evidence for an egg/sperm recognition system in insects. The mechanism is similar to those known from higher animals
Suppression of non-prompt J/ψ, prompt J/ψ, and Y(1S) in PbPb collisions at √s NN = 2.76 TeV
No full textThis is the Pre-print verison of the Article. The official published version can be accessed from the link below - Copyright @ 2012 Springer VerlagYields of prompt and non-prompt J/ψ, as well as U (1S) mesons, are measured by the CMS experiment via their μ + μ − decays in PbPb and pp collisions at Ö{s\textNN} = 2.76 sNN=276 TeV for quarkonium rapidity |y| < 2.4. Differential cross sections and nuclear modification factors are reported as functions of y and transverse momentum p T, as well as collision centrality. For prompt J/ψ with relatively high p T (6.5 < p T < 30 GeV/c), a strong, centrality-dependent suppression is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. In the same kinematic range, a suppression of non-prompt J/ψ, which is sensitive to the in-medium b-quark energy loss, is measured for the first time. Also the low-p T U (1S) mesons are suppressed in PbPb collisions.This work was supported by the Austrian Federal Ministry of Science and Research; the Belgium Fonds de la Recherche Scientifique, and Fonds voor Wetenschappelijk
Onderzoek; the Brazilian Funding Agencies (CNPq, CAPES, FAPERJ, and FAPESP); the Bulgarian Ministry of Education and Science; CERN; the Chinese Academy of Sciences, Ministry of Science and Technology, and National Natural Science Foundation of China; the Colombian Funding Agency (COLCIENCIAS); the Croatian Ministry of Science, Education and Sport; the Research Promotion Foundation, Cyprus; the Estonian Academy of Sciences and NICPB; the Academy of Finland, Finnish Ministry of Education and Culture, and Helsinki Institute of
Physics; the Institut National de Physique Nucl´eaire et de Physique des Particules / CNRS, and Commissariat a l’Energie Atomique et aux Energies Alternatives / CEA, France; the Bundesministerium fur Bildung und Forschung, Deutsche Forschungsgemeinschaft, and Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany; the General Secretariat for Research and Technology, Greece; the National Scientific Research Foundation, and National Office for
Research and Technology, Hungary; the Department of Atomic Energy and the Department of Science and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics, Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy; the Korean
Ministry of Education, Science and Technology and the World Class University program of NRF, Korea; the Lithuanian Academy of Sciences; the Mexican Funding Agencies (CINVESTAV, CONACYT, SEP, and UASLP-FAI); the Ministry of Science and Innovation, New Zealand; the Pakistan Atomic Energy Commission; the Ministry of Science and Higher Education and the National Science Centre, Poland; the Fundac¸ ao para a Ciencia e a Tecnologia, Portugal; JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); the Ministry of Education and Science of the Russian Federation, the Federal Agency of Atomic Energy of the Russian Federation, Russian Academy of Sciences, and the Russian Foundation for Basic Research; the Ministry of Science and Technological Development of Serbia; the Ministerio de Ciencia e Innovacion, and Programa Consolider-Ingenio 2010, Spain; the Swiss Funding Agencies (ETH Board, ETH Zurich, PSI, SNF, UniZH, Canton Zurich, and SER); the National Science Council, Taipei; the Scientific and Technical Research Council of Turkey, and Turkish Atomic Energy Authority; the Science and Technology Facilities Council, UK; the US Department of Energy, and the US National Science Foundation
The first metazoa living in permanently anoxic conditions
No full textAbstract Background Several unicellular organisms (prokaryotes and protozoa) can live under permanently anoxic conditions. Although a few metazoans can survive temporarily in the absence of oxygen, it is believed that multi-cellular organisms cannot spend their entire life cycle without free oxygen. Deep seas include some of the most extreme ecosystems on Earth, such as the deep hypersaline anoxic basins of the Mediterranean Sea. These are permanently anoxic systems inhabited by a huge and partly unexplored microbial biodiversity. Results During the last ten years three oceanographic expeditions were conducted to search for the presence of living fauna in the sediments of the deep anoxic hypersaline L'Atalante basin (Mediterranean Sea). We report here that the sediments of the L'Atalante basin are inhabited by three species of the animal phylum Loricifera (Spinoloricus nov. sp., Rugiloricus nov. sp. and Pliciloricus nov. sp.) new to science. Using radioactive tracers, biochemical analyses, quantitative X-ray microanalysis and infrared spectroscopy, scanning and transmission electron microscopy observations on ultra-sections, we provide evidence that these organisms are metabolically active and show specific adaptations to the extreme conditions of the deep basin, such as the lack of mitochondria, and a large number of hydrogenosome-like organelles, associated with endosymbiotic prokaryotes. Conclusions This is the first evidence of a metazoan life cycle that is spent entirely in permanently anoxic sediments. Our findings allow us also to conclude that these metazoans live under anoxic conditions through an obligate anaerobic metabolism that is similar to that demonstrated so far only for unicellular eukaryotes. The discovery of these life forms opens new perspectives for the study of metazoan life in habitats lacking molecular oxygen.</p
Sperm and egg surface components potentially involved in gamete interactions in Drosophila melanogaster.
No full textFree-Living Protozoa with Endosymbiotic Methanogens
No full textMethanogenic bacteria occur in many, but not all, free-living obligate anaerobic protozoa. This sort of symbiosis is especially common among anaerobic ciliates but is also found in a few species of amoebae and flagellates. Protozoa harbouring methanogens have a clostridium-type fermentative metabolism with H2 as metabolite, the hydrogen generation taking place in special organelles, so-called hydrogenosomes. The relation between the host cells and their endosymbiotic methanogens is syntrophic hydrogen transfer. By removing the generated H2, the methanogens stimulate host H2 production, thus increasing the energetic yield of the energy metabolism. This sort of symbiosis has evolved independently in many cases and involves representatives of several major groups of methanogenic bacteria. Symbiotic methanogenesis of free-living anaerobic protozoa plays only a modest quantitative role in terms of CH4 production in most habitats
Componenti della superficie di uovo e spermatozoo potenzialmente coinvolti nelle interazioni tra gameti in Drosophila melanogaster
No full textWe investigated the presence of
enzymes on the surface of Drosophila melanogaster
spermatozoa that might bind to the carbohydrate
residues of the egg shell. Spectrophotometric and
fluorimetric studies were used on whole spermatozoa
to assay galactosyltransferase and glycosidase activities.
No galactosyltransferase is present on the sperm
surface, whereas two glycosidases, b-N-acetylglucosaminidase
(GlcNAc8ase) and a-mannosidase (Man8ase),
have been evidenced. They have an optimal pH of
6–6.5 and 4, respectively. The same glycosidases
were detected as soluble forms probably secreted by
the seminal vesicle epithelium. We suggest that these
enzymes might be involved in the recognition of a-mannose
and b-N-acetylglucosamine residues present on
the egg shell at the site of sperm entry
- …
