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121.
Syntaxin and VAMP association with lipid rafts depends on cholesterol depletion in capacitating sperm cells 总被引:1,自引:0,他引:1
Tsai PS De Vries KJ De Boer-Brouwer M Garcia-Gil N Van Gestel RA Colenbrander B Gadella BM Van Haeften T 《Molecular membrane biology》2007,24(4):313-324
Sperm cells represent a special exocytotic system since mature sperm cells contain only one large secretory vesicle, the acrosome, which fuses with the overlying plasma membrane during the fertilization process. Acrosomal exocytosis is believed to be regulated by activation of SNARE proteins. In this paper, we identified specific members of the SNARE protein family, i.e., the t-SNAREs syntaxin1 and 2, and the v-SNARE VAMP, present in boar sperm cells. Both syntaxins were predominantly found in the plasma membrane whereas v-SNAREs are mainly located in the outer acrosomal membrane of these cells. Under non-capacitating conditions both syntaxins and VAMP are scattered in well-defined punctate structures over the entire sperm head. Bicarbonate-induced in vitro activation in the presence of BSA causes a relocalization of these SNAREs to a more homogeneous distribution restricted to the apical ridge area of the sperm head, exactly matching the site of sperm zona binding and subsequent induced acrosomal exocytosis. This redistribution of syntaxin and VAMP depends on cholesterol depletion and closely resembles the previously reported redistribution of lipid raft marker proteins. Detergent-resistant membrane isolation and subsequent analysis shows that a significant proportion of syntaxin emerges in the detergent-resistant membrane (raft) fraction under such conditions, which is not the case under those conditions where cholesterol depletion is blocked. The v-SNARE VAMP displays a similar cholesterol depletion-dependent lateral and raft redistribution. Taken together, our results indicate that redistribution of syntaxin and VAMP during capacitation depends on association of these SNAREs with lipid rafts and that such a SNARE-raft association may be essential for spatial control of exocytosis and/or regulation of SNARE functioning. 相似文献
122.
Willems NM Mulder L Langenbach GE Grünheid T Zentner A van Eijden TM 《Journal of structural biology》2007,158(3):421-427
The mandibular condyle is considered a good model for developing cancellous bone because of its rapid growth and high rate of remodeling. The aim of the present study was to analyze the simultaneous changes in microarchitecture and mineralization of cancellous bone during development in a three-dimensional fashion. Eight mandibular condyles of pigs aged 8 weeks prepartum to 108 weeks postpartum were scanned using microCT with an isotropic spatial resolution of 10 microm. The number of trabeculae decreased during development, whereas both the trabecular thickness and the distance between the trabeculae increased. The bone surface to volume ratio decreased during development, possibly limiting the amount of (re)modeling. Both the mean degree of mineralization and intratrabecular differences in mineralization between the surfaces and cores of trabecular elements increased during development. The trabecular surfaces were more highly mineralized in the older condyles compared to the younger ones. Together with the observed decrease in the relative size of trabecular surface, this finding suggests a decrease in (re)modeling activity during development. In accordance with the general growth and development of the pig, it was concluded that most developmental changes in cancellous bone occur until the age of 40 weeks postpartum. 相似文献
123.
Preferences for grouping with familiar individuals are shown in many animal species, including the three-spined stickleback (Gasterosteus aculeatus). Shoaling with familiars is advantageous because of more precise anti-predator behaviours or more stable dominance hierarchies. Additionally, associations with familiar individuals facilitate the evolution of altruistic behaviour. Thus, in situations of increased competition one might expect an increased preference for familiar fish. We gave single juvenile sticklebacks of different nutritional state the choice between shoals composed either of familiar or unfamiliar individuals. Satiated fish preferred to shoal with familiar individuals. A comparative analysis of 8 stickleback studies with 15 different tests using familiars showed that all tests gave similar results, i.e. sticklebacks of all age classes preferred to shoal with familiars in a non-sexual context. In contrast, hungry test fish did not prefer to shoal with familiar fish, but even showed a preference for the unfamiliar group. Because sticklebacks use early-life familiarity to recognize kin, the results suggest the avoidance of competition with relatives. To our knowledge, this is the first study showing an impact of nutritional state on social interactions with familiar individuals. 相似文献
124.
Molecular diagnosis of medical viruses 总被引:1,自引:0,他引:1
The diagnosis of infectious diseases has been revolutionized by the development of molecular techniques, foremost with the applications of the polymerase chain reaction (PCR). The achievable high sensitivity and ease with which the method can be used to detect any known genetic sequence have led to its wide application in the life sciences. More recently, real-time PCR assays have provided additional major contributions, with the inclusion of an additional fluorescent probe detection system resulting in an increase in sensitivity over conventional PCR, the ability to confirm the amplification product and to quantitate the target concentration. Further, nucleotide sequence analysis of the amplification products has facilitated epidemiological studies of infectious disease outbreaks, and the monitoring of treatment outcomes for infections, in particular with viruses which mutate at high frequency. This review discusses the applications of qualitative and quantitative real-time PCR, nested PCR, multiplex PCR, nucleotide sequence analysis of amplified products and quality assurance with nucleic acid testing (NAT) in diagnostic laboratories. 相似文献
125.
Sylvain Legrand Theo Hendriks Jean-Louis Hilbert Marie-Christine Quillet 《BMC plant biology》2007,7(1):27
Background
Somatic embryogenesis (SE) is an asexual propagation pathway requiring a somatic-to-embryonic transition of differentiated somatic cells toward embryogenic cells capable of producing embryos in a process resembling zygotic embryogenesis. In chicory, genetic variability with respect to the formation of somatic embryos was detected between plants from a population of Cichorium intybus L. landrace Koospol. Though all plants from this population were self incompatible, we managed by repeated selfing to obtain a few seeds from one highly embryogenic (E) plant, K59. Among the plants grown from these seeds, one plant, C15, was found to be non-embryogenic (NE) under our SE-inducing conditions. Being closely related, we decided to exploit the difference in SE capacity between K59 and its descendant C15 to study gene expression during the early stages of SE in chicory. 相似文献126.
Anna Hultberg Denise M Tremblay Hans de Haard Theo Verrips Sylvain Moineau Lennart Hammarström Harold Marcotte 《BMC biotechnology》2007,7(1):58
Background
Bacteriophages infecting lactic acid bacteria (LAB) are widely acknowledged as the main cause of milk fermentation failures. In this study, we describe the surface-expression as well as the secretion of two functional llama heavy-chain antibody fragments, one binding to the major capsid protein (MCP) and the other to the receptor-binding proteins (RBP) of the lactococcal bacteriophage p2, by lactobacilli in order to neutralise lactococcal phages. 相似文献127.
Jan M de Boer Erwin Datema Xiaomin Tang Theo J A Borm Erin H Bakker Herman J van Eck Roeland C H J van Ham Hans de Jong Richard G F Visser Christian W B Bachem 《BMC genomics》2015,16(1)
Background
In flowering plants it has been shown that de novo genome assemblies of different species and genera show a significant drop in the proportion of alignable sequence. Within a plant species, however, it is assumed that different haplotypes of the same chromosome align well. In this paper we have compared three de novo assemblies of potato chromosome 5 and report on the sequence variation and the proportion of sequence that can be aligned.Results
For the diploid potato clone RH89-039-16 (RH) we produced two linkage phase controlled and haplotype-specific assemblies of chromosome 5 based on BAC-by-BAC sequencing, which were aligned to each other and compared to the 52 Mb chromosome 5 reference sequence of the doubled monoploid clone DM 1–3 516 R44 (DM). We identified 17.0 Mb of non-redundant sequence scaffolds derived from euchromatic regions of RH and 38.4 Mb from the pericentromeric heterochromatin. For 32.7 Mb of the RH sequences the correct position and order on chromosome 5 was determined, using genetic markers, fluorescence in situ hybridisation and alignment to the DM reference genome. This ordered fraction of the RH sequences is situated in the euchromatic arms and in the heterochromatin borders. In the euchromatic regions, the sequence collinearity between the three chromosomal homologs is good, but interruption of collinearity occurs at nine gene clusters. Towards and into the heterochromatin borders, absence of collinearity due to structural variation was more extensive and was caused by hemizygous and poorly aligning regions of up to 450 kb in length. In the most central heterochromatin, a total of 22.7 Mb sequence from both RH haplotypes remained unordered. These RH sequences have very few syntenic regions and represent a non-alignable region between the RH and DM heterochromatin haplotypes of chromosome 5.Conclusions
Our results show that among homologous potato chromosomes large regions are present with dramatic loss of sequence collinearity. This stresses the need for more de novo reference assemblies in order to capture genome diversity in this crop. The discovery of three highly diverged pericentric heterochromatin haplotypes within one species is a novelty in plant genome analysis. The possible origin and cytogenetic implication of this heterochromatin haplotype diversity are discussed.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1578-1) contains supplementary material, which is available to authorized users. 相似文献128.
The pleiotropic effects of creatine (Cr) are based mostly on the functions of the enzyme creatine kinase (CK) and its high-energy
product phosphocreatine (PCr). Multidisciplinary studies have established molecular, cellular, organ and somatic functions
of the CK/PCr system, in particular for cells and tissues with high and intermittent energy fluctuations. These studies include
tissue-specific expression and subcellular localization of CK isoforms, high-resolution molecular structures and structure–function
relationships, transgenic CK abrogation and reverse genetic approaches. Three energy-related physiological principles emerge,
namely that the CK/PCr systems functions as (a) an immediately available temporal energy buffer, (b) a spatial energy buffer
or intracellular energy transport system (the CK/PCr energy shuttle or circuit) and (c) a metabolic regulator. The CK/PCr
energy shuttle connects sites of ATP production (glycolysis and mitochondrial oxidative phosphorylation) with subcellular
sites of ATP utilization (ATPases). Thus, diffusion limitations of ADP and ATP are overcome by PCr/Cr shuttling, as most clearly
seen in polar cells such as spermatozoa, retina photoreceptor cells and sensory hair bundles of the inner ear. The CK/PCr
system relies on the close exchange of substrates and products between CK isoforms and ATP-generating or -consuming processes.
Mitochondrial CK in the mitochondrial outer compartment, for example, is tightly coupled to ATP export via adenine nucleotide
transporter or carrier (ANT) and thus ATP-synthesis and respiratory chain activity, releasing PCr into the cytosol. This coupling
also reduces formation of reactive oxygen species (ROS) and inhibits mitochondrial permeability transition, an early event
in apoptosis. Cr itself may also act as a direct and/or indirect anti-oxidant, while PCr can interact with and protect cellular
membranes. Collectively, these factors may well explain the beneficial effects of Cr supplementation. The stimulating effects
of Cr for muscle and bone growth and maintenance, and especially in neuroprotection, are now recognized and the first clinical
studies are underway. Novel socio-economically relevant applications of Cr supplementation are emerging, e.g. for senior people,
intensive care units and dialysis patients, who are notoriously Cr-depleted. Also, Cr will likely be beneficial for the healthy
development of premature infants, who after separation from the placenta depend on external Cr. Cr supplementation of pregnant
and lactating women, as well as of babies and infants are likely to be of benefit for child development. Last but not least,
Cr harbours a global ecological potential as an additive for animal feed, replacing meat- and fish meal for animal (poultry
and swine) and fish aqua farming. This may help to alleviate human starvation and at the same time prevent over-fishing of
oceans. 相似文献
129.
The high similarity between pigs and humans makes pigs a good gastrointestinal (GI) model for humans. Recently an epithelial cell line originating from the jejunum of pig (IPEC-J2) became available. Once validated, this model can be used to investigate the complex interactions occurring in the intestine. The advantages of using IPEC-J2 as in vitro model of the GI tract are the high resemblance between humans and pigs, and the ease of extrapolating in vitro to in vivo characteristics. In this study, the IPEC-J2 cells were functionally characterized by measuring the trans-epithelial electrical resistance (TEER), and by histological and ultrastructural studies. IPEC-J2 cells grown on six different permeable support systems, were investigated. The Transwell®-COL collagen-coated membrane (1.12 cm2) showed the best results concerning time efficiency and TEER values. The optimum seeding density of 12 × 105 cells/mL ensured that after 9 days of differentiation a confluent monolayer was formed. The decrease in TEER values after a maximum had been reached, coincided with the ultrastructural development of apical microvilli. We conclude that IPEC-J2 cells grown on collagen-coated membranes represent a valuable in vitro model system for the small intestinal epithelium which can be of great interest for intestinal research. 相似文献
130.
A freshwater cyanophage whose genome indicates close relationships to photosynthetic marine cyanomyophages 总被引:1,自引:0,他引:1
Dreher TW Brown N Bozarth CS Schwartz AD Riscoe E Thrash C Bennett SE Tzeng SC Maier CS 《Environmental microbiology》2011,13(7):1858-1874
Bacteriophage S-CRM01 has been isolated from a freshwater strain of Synechococcus and shown to be present in the upper Klamath River valley in northern California and Oregon. The genome of this lytic T4-like phage has a 178,563 bp circular genetic map with 297 predicted protein-coding genes and 33 tRNA genes that represent all 20-amino-acid specificities. Analyses based on gene sequence and gene content indicate a close phylogenetic relationship to the 'photosynthetic' marine cyanomyophages infecting Synechococcus and Prochlorococcus. Such relatedness suggests that freshwater and marine phages can draw on a common gene pool. The genome can be considered as being comprised of three regions. Region 1 is populated predominantly with structural genes, recognized as such by homology to other T4-like phages and by identification in a proteomic analysis of purified virions. Region 2 contains most of the genes with roles in replication, recombination, nucleotide metabolism and regulation of gene expression, as well as 5 of the 6 signature genes of the photosynthetic cyanomyophages (hli03, hsp20, mazG, phoH and psbA; cobS is present in Region 3). Much of Regions 1 and 2 are syntenic with marine cyanomyophage genomes, except that a segment encompassing Region 2 is inverted. Region 3 contains a high proportion (85%) of genes that are unique to S-CRM01, as well as most of the tRNA genes. Regions 1 and 2 contain many predicted late promoters, with a combination of CTAAATA and ATAAATA core sequences. Two predicted genes that are unusual in phage genomes are homologues of cellular spoT and nusG. 相似文献