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1.
Isolation and characterization of plasma membrane-associated cortical granules from sea urchin eggs 总被引:9,自引:6,他引:3
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Cortical granules, which are specialized secretory organelles found in ova of many organisms, have been isolated from the eggs of the sea urchins Arbacia punctulata and Strongylocentrtus pupuratus by a simple, rapid procedure. Electron micropscope examination of cortical granules prepared by this procedure reveals that they are tightly attached to large segments of the plasma membrane and its associated vitelline layer. Further evidence that he cortical granules were associated with these cell surface layers was obtained by (125)I-labeling techniques. The cortical granule preparations were found to be rich in proteoesterase, which was purified 32-fold over that detected in a crude homogenate. Similarly, the specific radioactivity of a (125)I-labeled, surface glycoprotein was increased 40-fold. These facts, coupled with electron microscope observations, indicate the isolation procedure yields a preparation in which both the cortical granules and the plasma membrane-vitelline layer are purified to the same extent. Gel electrophoresis of the membrane-associated cortical granule preparation reveals the presence of at least eight polypeptides. The major polypeptide, which is a glycotprotein of apparent mol wt of 100,000, contains most of the radioactivity introduced by (125)I-labeling of the intact eggs. Lysis of the cortical granules is observed under hypotonic conditions, or under isotonic conditions if Ca(2+) ion is present. When lysis is under isotonic conditions is induced by addition of Ca(2+) ion, the electron-dense contents of the granules remain insoluble. In contrast, hypotonic lysis results in release of the contents of the granule in a soluble form. However, in both cases the (125)I-labeled glycoprotein remains insoluble, presumably because it is a component of either the plasma membrane or the vitelline layer. All these findings indicate that, using this purified preparation, it should be possible to carry out in vitro studies to better define some of the initial, surface-related events observed in vivo upon fertilization. 相似文献
2.
The data requirements and resources needed to develop multispecies indicators of fishing impacts are often lacking and this is particularly true for coral reef fisheries. Size-spectra, relationships between abundance and body-size class, regardless of taxonomy, can be calculated from simple sizeabundance data. Both the slope and the mid-point height of the relationship can be compared at different fishing intensities. Here, we develop size-spectra for reef fish assemblages using body size- abundance data collected by underwater visual census in each of ten fishing grounds across a known gradient of fishing intensity in the Kadavu Island group, Fiji. Slopes of the size-spectra became steeper (F9,69=3.20, p<0.01) and the height declined (F9,69=15.78, p<0.001) with increasing fishing intensity. Regressions of numbers of individuals per size class across grounds were negative for all size classes, although the slope was almost zero for the smallest size class. Response to exploitation of each size class category was greatest for larger fish. Steepening of the slope with increasing fishing intensity largely resulted from reductions in the relative abundance of large fish and not from the ecological release of small fish following depletion of their predators. The slope and height of the size-spectrum appear to be good indicators of fishing effects on reef fish assemblages. 相似文献
3.
Introduction
Bone morphogenetic proteins (BMPs) are critical growth factors in the osteogenic differentiation of progenitor cells during development in embryos and fracture repair in adults. Although recombinant BMPs are in use clinically, their clinical efficiency needs to be improved. The biological activities of BMPs are naturally regulated by extracellular binding proteins. The specific hypotheses tested in this study were as follows: the BMP inhibitor chordin is produced endogenously during the osteogenic differentiation of human mesenchymal stem cells (MSCs); and blockade of the activity of the BMP inhibitor increases the rate of osteogenic differentiation of human MSCs in vitro.Methods
Human MSCs were derived from bone marrow from an iliac crest aspirate and from patients undergoing hip hemiarthroplasty. The MSCs were induced down the osteogenic pathway using standard osteogenic differentiation media, and expressions of BMP-2 and chordin were determined by gene expression analysis. During osteogenic differentiation, chordin knockdown was induced using RNA interference. Osteogenic differentiation was assessed by measuring the expression of alkaline phosphatase and calcium deposition. The differences in expression of osteogenic makers between groups were compared by analysis of variance, followed by Gabriel post hoc test.Results
We demonstrate the expression of BMP-2 and chordin in human MSCs during osteogenic differentiation. Knockdown of chordin by RNA interference in vitro resulted in a significant increase in the expression of the osteogenic marker alkaline phosphatase and the deposition of extracellular mineral, in response to osteogenic stimulation.Conclusion
We conclude that endogenously produced chordin constrains the osteogenic differentiation of human MSCs. The targeting of BMP inhibitors, such as chordin, may provide a novel strategy for enhancing bone regeneration. 相似文献4.
Harsh Raman Rosy Raman Andrzej Kilian Frank Detering Jason Carling Neil Coombes Simon Diffey Gururaj Kadkol David Edwards Margaret McCully Pradeep Ruperao Isobel A. P. Parkin Jacqueline Batley David J. Luckett Neil Wratten 《PloS one》2014,9(7)
Resistance to pod shattering (shatter resistance) is a target trait for global rapeseed (canola, Brassica napus L.), improvement programs to minimise grain loss in the mature standing crop, and during windrowing and mechanical harvest. We describe the genetic basis of natural variation for shatter resistance in B. napus and show that several quantitative trait loci (QTL) control this trait. To identify loci underlying shatter resistance, we used a novel genotyping-by-sequencing approach DArT-Seq. QTL analysis detected a total of 12 significant QTL on chromosomes A03, A07, A09, C03, C04, C06, and C08; which jointly account for approximately 57% of the genotypic variation in shatter resistance. Through Genome-Wide Association Studies, we show that a large number of loci, including those that are involved in shattering in Arabidopsis, account for variation in shatter resistance in diverse B. napus germplasm. Our results indicate that genetic diversity for shatter resistance genes in B. napus is limited; many of the genes that might control this trait were not included during the natural creation of this species, or were not retained during the domestication and selection process. We speculate that valuable diversity for this trait was lost during the natural creation of B. napus. To improve shatter resistance, breeders will need to target the introduction of useful alleles especially from genotypes of other related species of Brassica, such as those that we have identified. 相似文献
5.
6.
Mohammad Raish Varinderpal S Dhillon Arif Ahmad Mushtaq Ahmad Ansari Shahid Mudassar Mohammad Shahid Vineeta Batra Pawan Gupta Bhudev Chandra Das NK Shukla Syed Akhtar Husain 《Translational oncology》2009,2(4):264-270
BACKGROUND: Aberrant DNA methylation has been recognized in human breast carcinogenesis as a common molecular alteration associated with the loss of expression of a number of key regulatory genes. The present study was undertaken to determine whether methylation and expression of p16 and FHIT genes would correlate with the estrogen receptor (ER) and progesterone receptor (PR) status. METHODS: Methylation-specific polymerase chain reaction, messenger RNA (mRNA) expression analysis, immunohistochemistry, and Western blot analysis were performed to study the methylation of p16 and FHIT genes in 351 pairs of malignant/normal breast tissues. We examined the expression of ER and PR in those specimens by immunohistochemistry. Mutations of p16 and FHIT genes in tumors were detected by direct sequencing. RESULTS: The frequency of hypermethylation was 31.9% and 36.8% in p16 and FHIT genes, respectively, and showed significant harmony in concordant hypermethylation (P < .0001). In postmenopausal patients, methylation frequency in both genes is significantly higher in poorly and moderately differentiated tumors. Loss of protein expression of p16 and FHIT in 77 and 74 tumors, respectively, is associated with their methylation status in premenopausal women. CONCLUSION: We did not find any significant differences in tumor-related gene methylation patterns relevant to both ER and PR status of breast tumors. 相似文献
7.
Ponnusamy Kalaiarasan Naidu Subbarao Rameshwar NK Bamezai 《Journal of molecular modeling》2014,20(9):1-12
Microstructure of dibenzo-18-crown-6 (DB18C6) and DB18C6/Li+ complex in different solvents (water, methanol, chloroform, and nitrobenzene) have been analyzed using radial distribution function (RDF), coordination number (CN), and orientation profiles, in order to identify the role of solvents on complexation of DB18C6 with Li+, using molecular dynamics (MD) simulations. In contrast to aqueous solution of LiCl, no clear solvation pattern is found around Li+ in the presence of DB18C6. The effect of DB18C6 has been visualized in terms of reduction in peak height and shift in peak positions of gLi-Ow. The appearance of damped oscillations in velocity autocorrelation function (VACF) of complexed Li+ described the high frequency motion to a “rattling” of the ion in the cage of DB18C6. The solvent-complex interaction is found to be higher for water and methanol due to hydrogen bond (HB) interactions with DB18C6. However, the stability of DB18C6/Li+ complex is found to be almost similar for each solvent due to weak complex-solvent interactions. Further, Li+ complex of DB18C6 at the liquid/liquid interface of two immiscible solvents confirm the high interfacial activity of DB18C6 and DB18C6/Li+ complex. The complexed Li+ shows higher affinity for water than organic solvents; still they remain at the interface rather than migrating toward water due to higher surface tension of water as compared to organic solvents. These simulation results shed light on the role of counter-ions and spatial orientation of species in pure and hybrid solvents in the complexation of DB18C6 with Li+. Graphical Abstract
DB18C6/Li+ complex in pure solvents (water, methanol, chloroform, and nitrobenzene) and water/nitrobenzene interface 相似文献
8.
Comparative Effects of Ethanol and Malnutrition on the Development of Catecholamine Neurons: Changes in Neurotransmitter Levels 总被引:4,自引:4,他引:0
N. Detering R. M. Collins Jr. R. L. Hawkins P. T. Ozand A. Karahasan 《Journal of neurochemistry》1980,34(6):1587-1593
Abstract: The comparative effects of exposure to ethanol and malnutrition on the concentrations of tyrosine and catecholamines in whole brain and selected regions of brain have been studied in the developing rat. These animals were the offspring of optimally nourished rats (control pups), of rats fed a diet with 35% of the calories supplied by ethanol (ETOH pups), or of animals fed a diet calorically equivalent to the latter but lacking ethanol (iso-caloric, 1C pups). These diets were administered to dams either during the last week of gestation (prenatal) or during lactation (postnatal). Tyrosine levels were elevated prior to birth in the prenatal ETOH or IC pups or at 1 and 2 weeks of age in postnatal ETOH or 1C pups as compared with values found in the control offspring. Dopamine concentration in whole brain was significantly lower in prenatal ETOH pups than in prenatal IC pups at 3 weeks of age. Levels in the brains of postnatal ETOH pups were lower than control values, but not relative to animals exposed to 1C diet. Investigation of corpus striatum showed a significant decrease in dopamine concentration compared with control or IC pup values as a result of postnatal exposure to ethanol. Norepinephrine levels in the whole brain of prenatal ETOH pups were consistently 30–40% lower than either control or matched 1C pups during development. At 3 weeks of age, the norepinephrine levels in the hypothalamus of animals exposed to ethanol pre or postnatally were 30–60% lower than values in the corresponding region in either control or 1C pups. In the rat model described, ethanol caused a decrease in catecholamine levels, perhaps solely by affecting the norepinephrine neurons. 相似文献
9.
Mitotic chromosome condensation in the sperm nucleus during post fertilization maturation division in urechis eggs
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Changes in the morphology of the sperm nucleus in the egg cytoplasm are mong the immediate events in nucleocytoplasmic interactions during early embryogenesis. Soon after its entrance into the egg cytoplasm, the sperm nucleus of various organisms increases in size with the transformation of condensed chromatin to a diffuse state, resembling the chromatin of an interphase nucleus (2, 13, 15, 16). This is followed by a close association or fusion of male and female pronuclei (2, 13, 15, 16). Cytoplasmic influences on nuclear morphology have also been demonstrated clearly in nuclear transplantation and cell fusion studies (10, 11). Reactivation of the nucleus, such as the transplanted brain nucleus in Xenopus egg cytoplasm or the hen erythrocyte nucleus in interphase cytoplasm of HeLa cells, is accompanied by nuclear enlargement and chromatin dispersion (10, 11). However, premature mitotic-like chromosome condensation takes place in the nuclei of sperm or interphase cells fused with mitotic cells (9, 12). Thus, chromosome dispersion and condensation seem to depend on the state of the cytoplasm in which the nucleus is present. These observations imply that the initial morphological changes in the sperm nucleus after fertilization may very well be dependent on the state of maturation of eggs at the time of sperm entry. Unfertilized eggs of Urechis caupo, a marine echiuroid worm, are stored at the diakinesis stage. These eggs complete maturation division after insemination and this is followed by fusion of male and female pronuclei (5, 8). Therefore, Urechis caupo is a suitable organism in which to study the response of the sperm nucleus to the changing state of the egg cytoplasm during and after postfertilization maturation division. 相似文献
10.
Putting Parasemia in its phylogenetic place: a molecular analysis of the subtribe Arctiina (Lepidoptera)
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Despite being popular among amateur and professional lepidopterologists and posing great opportunities for evolutionary research, the phylogenetic relationships of tiger moths (Erebidae: Arctiinae) are not well resolved. Here we provide the first phylogenetic hypothesis for the subtribe Arctiina with the basic aim of clarifying the phylogenetic position of the Wood Tiger Moth Parasemia plantaginis Hübner, a model species in evolutionary ecology. We sampled 89 species in 52 genera within Arctiina s.l., 11 species of Callimorphina and two outgroup species. We sequenced up to seven nuclear genes (CAD, GAPDH, IDH, MDH, Ef1α, RpS5, Wingless) and one mitochondrial gene (COI) including the barcode region (a total of 5915 bp). Both maximum likelihood and Bayesian inference resulted in a well‐resolved phylogenetic hypothesis, consisting of four clades within Arctiina s.s. and a clade comprising spilosomine species in addition to Callimorphina and outgroups. Based on our results, we present a new classification, where we consider the Diacrisia clade, Chelis clade, Apantesis clade, Micrarctia Seitz and Arctia clade as valid genera within Arctiina s.s., whereas Rhyparia Hübner syn.n. and Rhyparioides Butler syn.n. are synonymized with Diacrisia Hübner; Neoarctia Neumoegen & Dyar syn.n. , Tancrea Püngeler syn.n. , Hyperborea Grum‐Grshimailo syn.n. , Palearctia Ferguson syn.n. , Holoarctia Ferguson syn.n. , Sibirarctia Dubatolov syn.n. and Centrarctia Dubatolov syn.n. are synonymized with Chelis Rambur; Grammia Rambur syn.n. , Orodemnias Wallengren syn.n. , Mimarctia Neumoegen & Dyar syn.n. , Notarctia Smith syn.n. and Holarctia Smith syn.n. are synonymized with Apantesis Walker; and Epicallia Hübner syn.n. , Eucharia Hübner syn.n. , Hyphoraia Hübner syn.n. , Parasemia Hübner syn.n. , Pericallia Hübner syn.n. , Nemeophila Stephens syn.n. , Ammobiota Wallengren syn.n. , Platarctia Packard syn.n. , Chionophila Guenée syn.n. , Eupsychoma Grote syn.n. , Gonerda Moore syn.n. , Platyprepia Dyar syn.n. , Preparctia Hampson syn.n. , Oroncus Seitz syn.n. , Acerbia Sotavalta syn.n. , Pararctia Sotavalta syn.n. , Borearctia Dubatolov syn.n. , Sinoarctia Dubatolov syn.n. and Atlantarctia Dubatolov syn.n. are synonymized with Arctia Schrank, leading to 33 new genus‐level synonymies. Our focal species Arctia plantaginis comb.n. is placed as sister to Arctia festiva comb.n. , another widespread aposematic species showing wing pattern variation. Our molecular hypothesis can be used as a basis when adding more species to the tree and tackling interesting evolutionary questions, such as the evolution of warning signalling and mimicry in tiger moths. 相似文献