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61.
62.
Tempo and mode of concerted evolution in the L1 repeat family of mice 总被引:10,自引:0,他引:10
Martin SL; Voliva CF; Hardies SC; Edgell MH; Hutchison CA d 《Molecular biology and evolution》1985,2(2):127-140
A 300-bp DNA sequence has been determined for 30 (10 from each of three
species of mice) random isolates of a subset of the long interspersed
repeat family L1. From these data we conclude that members of the L1 family
are evolving in concert at the DNA sequence level in Mus domesticus, Mus
caroli, and Mus platythrix. The mechanism responsible for this phenomenon
may be either duplicative transposition, gene conversion, or a combination
of the two. The amount of intraspecies divergence averages 4.4%, although
between species base substitutions accumulate at the rate of approximately
0.85%/Myr to a maximum divergence of 9.1% between M. platythrix and both M.
domesticus and M. caroli. Parsimony analysis reveals that the M. platythrix
L1 family has evolved into a distinct clade in the 10-12 Myr since M.
platythrix last shared a common ancestor with M. domesticus and M. caroli.
The parsimony tree also provides a means to derive the average half-life of
L1 sequences in the genome. The rates of gain and loss of individual copies
of L1 were estimated to be approximately equal, such that approximately
one-half of them turn over every 3.3 Myr.
相似文献
63.
Hierarchical folding and reorganization of chromosomes are linked to transcriptional changes in cellular differentiation 下载免费PDF全文
Mariano Barbieri Benjamin L Moore Dorothee CA Kraemer Stuart Aitken Sheila Q Xie Kelly J Morris Masayoshi Itoh Hideya Kawaji Ines Jaeger Yoshihide Hayashizaki Piero Carninci Alistair RR Forrest The FANTOM Consortium Colin A Semple Josée Dostie Ana Pombo Mario Nicodemi 《Molecular systems biology》2015,11(12)
64.
Carl?Shooner Pierre-Luc?Caron Guylaine?Fréchette-Frigon Valérie?Leblanc Marie-Claude?Déry Eric?AsselinEmail author 《Reproductive biology and endocrinology : RB&E》2005,3(1):20
Background
During early rat pregnancy, trophoblast of the tiny embryo joins with the endometrium and epithelial cells undergo apoptosis. Near the end of pregnancy, regression of the decidua basalis (DB) is also observed (from day 14 to 20). However, little is known about the intra-cellular and molecular mechanisms involved in apoptosis regulation in the uterus during pregnancy. The objective of the present study was to investigate the presence and the developmental expression of transforming growth factor-beta isoforms (TGF-beta well known differentiation factor) in the rat endometrium throughout pregnancy and its action in vitro using cultured endometrial stromal cells. 相似文献65.
将化学合成的单链猪胰岛素前体(PIP)基因和用聚合酶链反应得到的α交配因子前导顺序(αMFL)基因插入质粒pVT102-U的醇脱氢酶基因ADH1的启动子和3’终止顺序之间而生成质粒pVT102-U/αMFL-PIP.被pVT102-U/αMFL-PIP转化的酵母(Saccharomyces cerevistae)可表达单链前体并分泌到培养基中.前体在纯化后可通过胰蛋白酶的转肽作用转变成人胰岛素.纯化的人胰岛素具有全部活力并可结晶.人胰岛素的总收率为每升培养液25mg. 相似文献
66.
The phylogenetic position of the Pedetidae, represented by a single species
Pedetes capensis, is controversial, reflecting in part the retention of
both Hystricomorphous and Sciurognathous characteristics in this rodent. In
an attempt to clarify the species evolutionary relationships, mtDNA gene
sequences from 10 rodent species (representing seven families) were
analyzed using phenetic, parsimony, and maximum-likelihood methods of
phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order
Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as
outgroups. Investigation of 714 base pairs of the protein-coding cytochrome
b gene indicate strong base bias at the third codon position with
significant rate heterogeneity evident between the three structural domains
of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA
gene revealed a transversion bias in the loop sections of all taxa. The
cytochrome b gene sequences proved useful in resolving associations between
closely related species but failed to produce consistent tree topologies at
the family level. In contrast, phylogenetic analysis of the 12S rRNA gene
resulted in strong support for the clustering of
Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion
of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is
concordant with studies of rodent fetal membranes as well as reproductive
and other anatomical features.
相似文献
67.
苎麻光合生理生态特性研究 总被引:1,自引:0,他引:1
以大田栽培的苎麻植株为材料,用TPS-2便携式光合作用测定系统测定自然条件下生长的苎麻叶片的光合气体交换参数,以及光响应曲线和CO2响应曲线,并通过回归和相关法分析探讨净光合速率与主要生理、生态因子间的关系.结果表明:(1)苎麻叶片的净光合速率(Pn)日变化曲线呈现双峰型,2个光合峰高度接近,其净光合速率具有典型的午休"现象;蒸腾速率(Tr)日变化曲线呈现单峰型,其走势与气孔导度(Gs)日变化一致.(2)苎麻叶片光合作用的光饱和点(LSP)为1 568.5μmol?m-2?s-1,光补偿点(LCP)为54.18μmol?m-2?s-1,表观量子效率(AQY)为0.025 8 mol?mol-1;而其CO2补偿点(CCP)、饱和点(CSP)和羧化效率(CE)分别为49.25、1 746.9μmol?mol-1和0.045;因此,苎麻属于喜光性阳生植物,且对强光有一定的耐受能力.(3)苎麻叶片Pn日变化的主要限制因子是胞间CO2浓度(Ci),主要决定生理因子是气孔导度(Gs). 相似文献
68.
入侵种喜旱莲子草和莲子草的营养生长和光合作用对温度的响应 总被引:2,自引:0,他引:2
比较温度对入侵种喜旱莲子草(Alternantheraphiloxeroides(Mart.)Griseb.)和其本土近缘种莲子草(A.sessilis(L.)DC.)的营养生长、叶片光合作用及叶绿素荧光的影响。实验将生长均衡的这两种植物放在不同温度(10℃、15℃、20℃、25℃、30℃)的光照培养箱中处理28d。结果表明,喜旱莲子草营养生长的速率和对温度的响应明显不同于莲子草:前者主茎生长的有效积温明显低于后者,分别是11.6d℃和27.0d℃;而新叶萌发的有效积温高于后者,分别是12.1d℃和6.7d℃。入侵种主茎和叶的发育起点温度都比本土种低,分别是10.4℃、11.0℃和12.8℃、14.9℃,表明喜旱莲子草的发育对低温反应不及莲子草敏感。对两种植物叶片的光合作用和叶绿素荧光的测定结果还表明:入侵种比本土种有较高的最大净光合速率和光饱和点,尤其在25℃时;10-30℃的温度范围内喜旱莲子草的最大光化学效率Fv/Fm没有显著变化,而莲子草在10℃低温条件下Fv/Fm值显著降低。较快的主茎生长速率、较宽的温度适应范围以及较高的光合能力可能使喜旱莲子草比本地种具有更强的竞争力,从而在其入侵过程中起了重要作用。 相似文献
69.
Simon Brooker Archie CA Clements Peter J Hotez Simon I Hay Andrew J Tatem Donald AP Bundy Robert W Snow 《Malaria journal》2006,5(1):1-8
Background
On the island of Bioko (Equatorial Guinea), insecticide-treated nets (ITNs) have been the main tool used to control malaria over the last 13 years. In 2004, started an indoor residual spraying (IRS) campaign to control malaria. The purpose of this study is to asses the impact of the two control strategies on the island of Bioko (Equatorial Guinea), with regards to Plasmodium infection and anaemia in the children under five years of age.Methods
Two transversal studies, the first one prior to the start of the IRS campaign and the second one year later. Sampling was carried out by stratified clusters. Malaria infection was measured by means of thick and thin film, and the packed cell volume (PCV) percentage. Data related to ITN use and information regarding IRS were collected. The Pearson's chi-square and logistic regression statistical tests were used to calculate odds ratios (OR)Results
In the first survey, 168 children were sampled and 433 children in the second one. The prevalence of infection was 40% in 2004, and significantly lower at 21.7% in 2005. PCV was 41% and 39%, respectively. 58% of the children surveyed in 2004 and 44.3% in 2005 had slept under an ITN. 78% of the dwellings studied in 2005 had been sprayed. In the 2005 survey, sleeping without a mosquito net meant a risk of infection 3 times greater than sleeping protected with a net hanged correctly and with no holes (p < 0.05).Conclusion
IRS and ITNs have proven to be effective control strategies on the island of Bioko. The choice of one or other strategy is, above all, a question of operational feasibility and availability of local resources. 相似文献70.
Malate dehydrogenase (MDH; EC 1.1.1.37) isozymes in long-term callus tissue culture of Cereus peruvianus were studied in starch gel electrophoresis to investigate the control of differential Mdh gene expression under sugar and temperature stress. While two cytosol MDH isozymes showed an unchanged phenotype when the callus tissues were transferred to medium maintained at 22 or 37°C and containing different concentrations of sucrose, glucose, and fructose, the different combinations of five mitochondrial MDH (mtMDH) and two microbody MDH (mbMDH) showed different MDH isozyme patterns in the callus populations. Differential expression of mtMDH isozymes seems to be modulated at the posttranslational level in callus tissues exposed to different concentrations and types of sugar and to high-temperature and low-temperature stress. An inductor effect on the expression of mbMDH isozymes was observed under stress conditions and in long-term callus tissue, and they may also present different responses. 相似文献