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排序方式: 共有162条查询结果,搜索用时 15 毫秒
1.
Summary In the present study, the topographical distribution of carbohydrate binding sites on the plasma membrane of bovine epididymal spermatozoa was investigated using 15 different fluorescent neoglycoproteins and asialoglycoproteins. With mannose-bovine serum albumin (BSA)-fluoresceinthiocarbamyl (FTC), mannose-6-phosphate-BSA-FTC, lactose-BSA-FTC, maltose-BSA-FTC, asialolactoferrin-FTC and asialotransferrin-FTC a marked fluorescence was observed in the postacrosomal area. These results further substantiate the concept that carbohydrate binding sites of the spermatozoan plasma membrane and corresponding carbohydrates of the zona pellucida play a significant role in gamete interactions.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday. 相似文献
2.
Sabine Kölle Fred Sinowatz Gudrun Boie Ines Totzauer Werner Amselgruber Johnna Plendl 《The Histochemical journal》1996,28(6):441-447
Summary The mRNA of the zona pellucida glycoprotein ZP3 was localized in frozen sections of pig ovaries, isolated oocytes and early embryos byin situ hybridization using biotinylated oligonucleotide probes. In follicles, the distribution of mRNA for ZP3 was correlated with the developmental stage: in primordial and primary follicles, the mRNA was shown to be predominantly localized in the oocyte. In secondary follicles, mRNA was found in both the oocyte and follicle cells. In tertiary and preovulatory follicles, the follicle cells showed distinct staining, whereas the oocyte was labelled weakly. In the early embryo, i.e. 2 days after fertilization, mRNA for ZP3 could not be demonstrated. Our results suggest that, in the pig, the zona pellucida protein ZP3 is synthesized by the oocyte and the follicle cells in sequence. After fertilization, synthesis of ZP3 is terminated. 相似文献
3.
We have analyzed a total of 12 different global and local multiple
protein-sequence alignment methods. The purpose of this study is to
evaluate each method's ability to correctly identify the ordered series of
motifs found among all members of a given protein family. Four
phylogenetically distributed sets of sequences from the hemoglobin, kinase,
aspartic acid protease, and ribonuclease H protein families were used to
test the methods. The performance of all 12 methods was affected by (1) the
number of sequences in the test sets, (2) the degree of similarity among
the sequences, and (3) the number of indels required to produce a multiple
alignment. Global methods generally performed better than local methods in
the detection of motif patterns.
相似文献
4.
In vitro stimulation of alkaline phosphatase activity in immature embryonic chick pelvic cartilage by adenosine 下载免费PDF全文
Cyclic AMP content in embryonic chick pelvic cartilage increases significantly as the embryo ages from 8 to 10 d. This in ovo elevation in cyclic AMP content precedes maximal cartilage alkaline phosphatase activity by some 24 h. We studied whether this temporal relationship may be causally related, using an in vitro organ culture. Incubation of pelvic cartilage from 9- and 10-d embryos in medium containing monobutyryl cyclic AMP (BtcAMP) resulted in significant increases in alkaline phosphatase activity (220 and 66 percent, respectively) as compared to that of cartilages incubated in medium alone. This stimulation was both concentration- and time-dependent with maximal response at 0.5 mM BtcAMP and 4-h incubation, respectively. Similar incubations of cartilage in medium containing 1-methyl-3-isobutyl xanthine (MIX), 0.25 mM, also resulted in increased alkaline phosphatase activity (114 percent). However, pelvic cartilage from 11-d embryos incubated in medium containing BtcAMP or MIX showed no increase in alkaline phosphatase activity. We postulated that developmental age was the factor responsible for this difference in response and that immature cartilage (that with little or no alkaline phosphatase activity) would respond to BtcAMP whereas mature cartilage (that with significant alkaline phosphatase activity) would not. This was tested by incubating end sections of 11-d cartilage, which have little alkaline phosphatase activity, and center sections, which have significantly alkaline phosphatase activity, with both BtcAMP and MIX. Alkaline phosphatase activity in end sections (immature cartilage) was stimulated by BtcAMP and MIX, whereas it was not stimulated in the center sections. Actinomycin D and cycloheximide inhibited BtcAMP and MIX stimulation of alkaline phosphatase activity. Thus, the in vitro data suggest that cyclic AMP is a mediator for the stimulation of alkaline phosphatase activity in embryonic cartilage. 相似文献
5.
In the present study we report on the histotopographical distribution of carbohydrate-binding proteins in the prostate and seminal vesicle of sexually mature NMRI mice using a panel of fluorescein-isothiocyanate labelled neoglycoproteins and asialoglycoproteins. Additionally, biochemical analysis using affinity chromatography and SDS-gel electrophoresis was performed to purify and characterize the respective proteins from the tissue. Our histochemical results clearly demonstrate the presence of endogenous receptors for the carbohydrate part of glycoconjugates in both glands. In the prostate a distinct staining was seen after incubation with melibiose-BSA-FTC, glucuronic acid-BSA-FTC and asialofetuin-FTC (only in the ventral prostate). In the epithelium of the seminal vesicle a weak staining occurred after incubation with asialofetuin-FTC and maltose-FTC. In the stroma of both accessory sex glands a distinct binding of several (neo)glycoproteins specific for beta-galactoside-binding proteins was observed which could be attributed to a beta-galactoside-binding lectin. Indeed biochemical analysis ascertained presence of such a histochemically detectable activity. We assume that the carbohydrate-binding proteins of the stroma, which were obviously linked to the elastic fibers, could play a role in the organisation of the extracellular matrix in the interstitium of the glands. 相似文献
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7.
Stèphan Kraai Lilly M Verhagen Enrique Valladares Joaquin Goecke Lorena Rasquin Paula Colmenares Berenice Del Nogal Peter WM Hermans Jacobus H de Waard 《Respiratory research》2013,14(1):76
Background
The International Study on Asthma and Allergies in Childhood (ISAAC) reported a prevalence of asthma symptoms in 17 centers in nine Latin American countries that was similar to prevalence rates reported in non-tropical countries. It has been proposed that the continuous exposure to infectious diseases in rural populations residing in tropical areas leads to a relatively low prevalence of asthma symptoms. As almost a quarter of Latin American people live in rural tropical areas, the encountered high prevalence of asthma symptoms is remarkable. Wood smoke exposure and environmental tobacco smoke have been identified as possible risk factors for having asthma symptoms.Methods
We performed a cross-sectional observational study from June 1, 2012 to September 30, 2012 in which we interviewed parents and guardians of Warao Amerindian children from Venezuela. Asthma symptoms were defined according to the ISAAC definition as self-reported wheezing in the last 12 months. The associations between wood smoke exposure and environmental tobacco smoke and the prevalence of asthma symptoms were calculated by means of univariate and multivariable logistic regression analyses.Results
We included 630 children between two and ten years of age. Asthma symptoms were recorded in 164 of these children (26%). The prevalence of asthma symptoms was associated with the cooking method. Children exposed to the smoke produced by cooking on open wood fires were at higher risk of having asthma symptoms compared to children exposed to cooking with gas (AOR 2.12, 95% CI 1.18 - 3.84). Four percent of the children lived in a household where more than ten cigarettes were smoked per day and they had a higher risk of having asthma symptoms compared to children who were not exposed to cigarette smoke (AOR 2.69, 95% CI 1.11 - 6.48).Conclusion
Our findings suggest that children living in rural settings in a household where wood is used for cooking or where more than ten cigarettes are smoked daily have a higher risk of having asthma symptoms. 相似文献8.
Oylum Erkus Victor CL de Jager Maciej Spus Ingrid J van Alen-Boerrigter Irma MH van Rijswijck Lucie Hazelwood Patrick WM Janssen Sacha AFT van Hijum Michiel Kleerebezem Eddy J Smid 《The ISME journal》2013,7(11):2126-2136
Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty. 相似文献
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10.
Richard S Smith Adriana Zabaleta Olga V Savinova Simon WM John 《BMC developmental biology》2001,1(1):3-14