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201.
Mark A. Batzer Santosh S. Arcot Joshua W. Phinney Michelle Alegria-Hartman David H. Kass Stephen M. Milligan Colin Kimpton Peter Gill Manfred Hochmeister Panayiotis A. Ioannou Rene J. Herrera Donald A. Boudreau W. Douglas Scheer Bronya J. B. Keats Prescott L. Deininger Mark Stoneking 《Journal of molecular evolution》1996,42(1):22-29
The Alu family of intersperesed repeats is comprised of ovr 500,000 members which may be divided into discrete subfamilies based upon mutations held in common between members. Distinct subfamilies of Alu sequences have amplified within the human genome in recent evolutionary history. Several individual Alu family members have amplified so recently in human evolution that they are variable as to presence and absence at specific loci within different human populations. Here, we report on the distribution of six polymorphic Alu insetions in a survey of 563 individuals from 14 human population groups across several continents. Our results indicate that these polymorphic Alu insertions probably have an African origin and that there is a much smaller amount of genetic variation between European populations than that found between other populations groups.
Present address: Department of Pathology, Stanley S. Scott Cancer Center, Louisiana State University Medical Center, 1901 Perdido St., New Orleans, LA 70112
Correspondence to: M.A. Batzer 相似文献
202.
203.
Ryousuke Takahashi Katsumi Kawamura Jianguo Hu †Michiyuki Hayashi Takeo Deguchi 《Journal of neurochemistry》1996,67(2):525-529
Abstract: To study the level of ciliary neurotrophic factor (CNTF) in human nervous tissues, we developed a sensitive enzyme-linked immunoassay using a specific antibody against human CNTF. This method allowed us to detect as little as 0.3 ng/ml of human CNTF with good linearity and accuracy. Using this method, CNTF levels were determined in human sciatic nerves obtained at autopsy from 21 amyotrophic lateral sclerosis (ALS) patients and 48 subjects who had died of other neurological diseases. CNTF genotypes were also determined. The results indicated that CNTF levels were high in the normal homozygotes and approximately halved in the heterozygote subjects. There was, however, no significant difference in CNTF levels in the sciatic nerves between ALS and other neurological disease patients, indicating that the CNTF level was mainly determined by its genotypes and that the level in the sciatic nerves was not reduced in ALS patients. 相似文献
204.
Thea mating type locus ofUstilago maydis contains the structural genes for a pheromone-based cell recognition system that governs fusion of haploid cells. The locus exists in two alleles, termeda1 anda2. We have completed the analysis of the nucleotide sequences unique toa1 anda2. Within these dissimilar regions we find two short patches of DNA sequence similarity. Interestingly, one of these segments corresponds to the transcribed region of thea1 pheromone precursor. As a result of multiple nucleotide exchanges this sequence does not code for a functional product. The existence of a second pheromone gene in thea2 allele suggests that the present locus had a multiallelic ancestor. In addition, we describe the presence of two additional genes in thea2 allele. We have investigated the role of these genes during mating and pathogenic development and speculate that they might affect mitochondrial inheritance. 相似文献
205.
Tetrapolar fungal mating types: Sexes by the thousands 总被引:6,自引:1,他引:5
Erika Kothe 《FEMS microbiology reviews》1996,18(1):65-87
206.
The presence of species and their cover values together with soil and topographic characteristics were recorded at 40 sites along an altitudinal gradient of the Puna Belt at Pozuelos, in the High Andes in northwest Argentina. Classification and ordination of plant assemblages showed that soil and topography were the best predictors of the variation in species distribution. The different plant assemblages which occur along the topographic gradient follow the geographic variation in rainfall in this Andean region. Perennial bushes and grasses colonize the plains and slopes with fine textured soils which retain their water content. In contrast, deciduous bushes and cactuses grow on steep, rocky, dry slopes. Open woods also occur on east-facing steep, rocky slopes which are sheltered from winds. 相似文献
207.
Energy equivalence assumes equal contribution of large and small species to production and energy flow in communities. As in a double logarithmic plot, physiological rates decline with body weight by –0.25, log biomass should increase by 0.25 and log abundance decline by –0.75 with log species weight, when this concept is valid. This was tested with annual data sets of the macrobenthos of 4 intertidal sites in the German Wadden Sea (Königshafen) and 3 sites in a south Portuguese lagoon (Ria Formosa). Only abundance data from two of these sites displayed significantly negative slopes with mean body size of the species. Biomass and secondary production data were significantly positively correlated with mean body size for all Ria Formosa sites and also for the biomass of a mussel bed in Königshafen. However, high variation in body size of the individuals of a species limits interpretation of these plots.It is preferable to test this concept by body weight classes regardless of its species composition. At Königshafen, biomass and production displayed two distinct peaks. One peak at small body size was caused by browsing species. The other peak at larger body size was caused by animals which potentially extract their food from the water column. This bimodality was only vaguely reflected at one station in the Ria Formosa, possibly because of a dominance of detritus feeding species. In a normalized form (log biomass or production / width of size classvs. log size class), these spectra imply a dominance of small individuals in biomass and production at all sites (except for a mussel bank at Königshafen). This is interpreted as a consequence of permanent disturbances. 相似文献
208.
Ariela Baruch Moshe Shani David R. Hurwitz Itamar Barash 《Genesis (New York, N.Y. : 2000)》1995,16(3):241-252
209.
以IL-8免疫的BALB/C小鼠脾细胞与Sp2/0或653小鼠骨髓瘤细胞融合构建了淋巴细胞杂交瘤克隆I8-S2和I8-63。ELISA叠加试验(ELISA Additivity Test)表明这两杂交瘤克隆分泌的单抗分别识别IL-8分子的不同表位。IL-8能激活人颗粒细胞,引起细胞内Ca~(2 )浓度([Ca~(2 )]_i)上升。通过流式细胞仪分析[Ca~(2 )]_i的变化,发现两个克隆单抗对IL8激活细胞的活力具有不同的中和作用。克隆I8-S2具有很强的中和作用,而克隆18-63则不然。上述结果提示IL-8的激活细胞活力局限于该分子的某表位。 相似文献
210.
纳西族和普米族的红细胞血型分布 总被引:2,自引:0,他引:2
调查了云南纳西族和普米族各104人的ABO、NMSs、Rh和P血型系统。结果表明,ABO血型系统中,纳西族和普米族有较高的基因频率r,分别为0.6082和0.6882,且基因频率p=q,纳西族均为0.1959,普米族均为0.1559。MNSw系统中两个民族都表现m〉n、s〉s,Ms〉Ns、MS〉NS,其中纳西族的基因频率在国内报道的相应值中是比较高的,且NS为零。 相似文献