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排序方式: 共有193条查询结果,搜索用时 468 毫秒
1.
P D Van Helden L Van Lill A J Bester E Hoal-Van Helden 《Biochimica et biophysica acta》1989,1009(2):137-142
Sera reacting positively for anti-DNA antibodies from systemic lupus erythematosus (SLE) patients were tested for their effect on DNA and RNA synthesis in permeabilized cultured cells and isolated nuclei. The immunoglobulin fraction obtained by ammonium sulfate precipitation of serum was shown to exert considerable influence on DNA and RNA synthesis in cultured cells and nuclei. A component of this antibody population is anti-DNA. These antibodies exert different effects on DNA template activity which is a function of their conformational specificity. Intracellular penetration of autoantibodies as noted in SLE may be one of the reasons for clinical manifestations of disease in these patients. 相似文献
2.
3.
Detection of a high frequency RsaI polymorphism in the human pro alpha 2(I) collagen gene which is linked to an autosomal dominant form of osteogenesis imperfecta. 总被引:12,自引:0,他引:12 下载免费PDF全文
A F Grobler-Rabie G Wallis D K Brebner P Beighton A J Bester C G Mathew 《The EMBO journal》1985,4(7):1745-1748
Screening of the pro alpha 2(I) collagen genes of Southern African populations for restriction fragment length polymorphisms (RFLPs) has revealed a locus polymorphic for the restriction enzyme RsaI. The frequency of the RFLP was 0.38 in Afrikaners, but much lower in indigenous Southern African populations, which suggests that it is of European origin. The polymorphism was used to study 19 affected and non-affected individuals in a four generation family with the autosomal dominant disorder, osteogenesis imperfecta (OI) type I. Co-inheritance of the loss of the RsaI site and the OI phenotype was observed with a lod score of 3.91 at a recombination fraction (theta) of zero, indicating strong linkage. This suggests that the defect in this family is caused by a structural mutation within or close to the pro alpha 2(I) collagen gene. The use of this high frequency RFLP together with other recently described polymorphisms at this locus will facilitate the analysis of the role of this gene in OI and other inherited disorders of connective tissue. 相似文献
4.
MOVEMENTS OF SOUTHERN ELEPHANT SEALS AND SUBANTARCTIC FUR SEALS IN RELATION TO MARION ISLAND 总被引:2,自引:0,他引:2
Based primarily on an intensive marking/resighting program conducted at Marion Island (46°54'S, 37°45'E) in the Southern Ocean, the inter-island movements of southern elephant seals, Mirounga leonina , and fur seals Arctocephalus spp., were investigated to elucidate their little known pelagic phase. Southern elephant seals, in particular immature animals, readily move between the proximate Marion and Prince Edward islands. Some range as far afield as Iles Crozet, approximately 1,000 km distant where they haul out for the summer molt or during an autumn resting phase. The exchange of individuals between Marion Island and Iles Crozet during the return of immatures for the molt after a winter at sea, suggests overlapping of the foraging ranges of the two populations. Despite their wanderings, the majority of M. leonina from Marion Island probably feed in the proximity of the island, and relocate onto the island for breeding, molting and resting. Of the fur seals, only a few A. tropicalis were seen away from their natal island, in some cases covering distances in excess of 2,000 km. displaying a remarkable dispersal capacity. 相似文献
5.
Increased intracellular Ca2+ is necessary for maximal expression of the proto-oncogene c-jun in the Jurkat T-cell line. 下载免费PDF全文
M L Vandenplas W L Mouton S Vandenplas A J Bester M H Ricketts 《The Biochemical journal》1990,267(2):349-351
The time course and signal-transduction requirements for proto-oncogene c-jun expression in T-cells were investigated. Expression of c-jun mRNA was evident at 30 min after stimulation. Both the activation of Ca2+/phospholipid-dependent kinase as well as an increased intracellular free Ca2+ concentration were necessary for the maximal induction of c-jun mRNA and synthesis of Jun protein 1 h after stimulation. 相似文献
6.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
7.
The reproductive tracts of 89 female subantarctic fur seals, taken at Gough Island between November 1977 and October 1978, were examined. Females started ovulating at age 4 yr and all 6-yr-old females were sexually mature. They are mono-ovulatory, alternating between ovaries, and only single embryos were found. Females older than 13 yr ( n = 11) showed poor follicular development and some failed to ovulate. The gestation period (first recorded ovulation to first recorded birth) was 360 d, while delayed implantation (first recorded ovulation to first recorded implantation) lasted for 139 days. Follicle numbers in the functional ovary declined sharply after ovulation while the corpus luteum increased in size until at least 1 mo prior to parturition. The number of follicles in the contralateral ovary increased after midwinter (June/July), and the mean size of the largest follicles peaked prior to ovulation in December. The mean size of the largest follicles increased in both ovaries near implantation time, after reaching a low subsequent to, ovulation. The regressing corpus albicans, conspicuous for approximately 3 mo after parturition, could not be detected macroscopically within one year postpartum. Subantarctic fur seals at Gough Island have a distinct postreproductive class of older females. The pregnancy rate for all females ≥4 yr of age was 79%, and it was 84.5% for the sexually mature group of ≥6 yr of age, while the mean age at puberty was 4.80 yr. 相似文献
8.
Lezaan Prinsloo Alex Naidoo June Serem Helena Taute Yasien Sayed Megan Bester Albert Neitz Anabella Gaspar 《Journal of peptide science》2013,19(5):325-332
Tick defensins may serve as templates for the development of multifunctional peptides. The purpose of this study was to evaluate shorter peptides derived from tick defensin isoform 2 (OsDef2) in terms of their antibacterial, antioxidant, and cytotoxic activities. We compared the structural and functional properties of a synthetic peptide derived from the carboxy‐terminal of the parent peptide (Os) to that of an analogue in which the three cysteine residues were omitted (Os–C). Here, we report that both peptides were bactericidal (MBC values ranging from 0.94–15 µg/ml) to both Gram‐positive and Gram‐negative bacteria, whereas the parent peptide only exhibited Gram‐positive antibacterial activity. The Os peptide was found to be two‐fold more active than Os–C against three of the four tested bacteria but equally active against Staphylococcus aureus. Os showed rapid killing kinetics against both Escherichia coli and Bacillus subtilis, whereas Os–C took longer, suggesting different modes of action. Scanning electron microscopy showed that in contrast to melittin for which blebbing of bacterial surfaces was observed, cells exposed to either peptide appeared flattened and empty. Circular dichroism data indicated that in a membrane‐mimicking environment, the cysteine‐containing peptide has a higher α‐helical content. Both peptides were found to be non‐toxic to mammalian cells. Moreover, the peptides displayed potent antioxidant activity and were 12 times more active than melittin. Multifunctional peptides hold potential for a wide range of clinical applications and further investigation into their mode of antibacterial and antioxidant properties is therefore warranted. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
9.
Pieter Swart Amanda C. Swart Penelope C. Meyer Rossouw Bester Kirsten J. van der Merwe 《Preparative biochemistry & biotechnology》2013,43(5):281-290
A new method for the removal of the stabilizing substrate, deoxycorticosterone, from adrenal cytochrome P-45011β, has been developed. Dextran coated charcoal is used for the adsorption of the steroid and the adsorbed steroid is separated from the cytochrome P-450-preparation by low speed centrifugation. The substrate-free enzyme, obtained in this manner, has all the characteristic spectral properties of low-spin cytochrome P-45011β, and may be converted to the high-spin form by the addition of deoxycorticosterone. The dextran coated charcoal method has the following advantages over the previously used method of substrate removal. It does not require the addition of the cofactors for cytochrome P-450-dependant hydroxyla-tion of deoxycorticosterone, small amounts of enzyme may be prepared in a short time and the enzyme preparation is not diluted to any great extent during the process. 相似文献
10.
Oliver J. D. Jewell Ryan L. Johnson Enrico Gennari Marthán N. Bester 《Environmental Biology of Fishes》2013,96(7):881-894
Previous work on white sharks indicate the species show seasonally limited movement patters, at certain aggregation sites small areas may play vital roles in the life history of a large amount of the population. Acoustic telemetry was used to estimate habitat use of white sharks, Carcharodon carcharias, while aggregating at Mossel Bay, South Africa. Total range of all shark tracks combined accumulated 782 h and covered an area of 93.5 km2 however, within this range, sharks were found to highly utilise a core habitat (50 % Kernel, K50) of just 1.05 km2 over a reef system adjacent to a river mouth. Individual tracks revealed additional core habitats, some of which were previously undocumented and one adjacent to a commercial harbor. Much was found to be dependent on the size of the shark, with larger sharks (>400 cm) occupying smaller activity areas than subadult (300–399 cm) and juvenile (<300 cm) conspecifics, while Index of Reuse (IOR) and Index of Shared Space (IOSS) were both found to increase with shark size. Such results provide evidence that larger white sharks are more selective in habitat use, which indicates they have greater experience within aggregation sites. Furthermore, the focused nature of foraging means spatially restricted management strategies would offer a powerful tool to aid enforcement of current protective legislation for the white shark in similar environments of limited resources and capacity. 相似文献