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31.
32.
On the phospholipids of Bacillus megaterium 总被引:12,自引:0,他引:12
33.
Bob?JA?Schijvenaars Barend?Mons Marc?Weeber Martijn?J?Schuemie Erik?M?van Mulligen Hester?M?Wain Jan?A?KorsEmail author 《BMC bioinformatics》2005,6(1):149
Background
Massive text mining of the biological literature holds great promise of relating disparate information and discovering new knowledge. However, disambiguation of gene symbols is a major bottleneck. 相似文献34.
A. C. Ramalhinho J. Marques JA Fonseca-Moutinho L. Breitenfeld 《Molecular biology reports》2013,40(8):5093-5103
Estrogen receptor alpha (ERα), that mediates the biologic effects of estrogen in estrogen-sensitive tissues like breast, is genetically polymorphic. To evaluate the association between ?397 PvuII (T>C) and ?351 XbaI (A>G) restriction fragment length polymorphisms (RFLPs) in intron 1 of ERα gene and susceptibility of breast cancer, we undertook a case–control study in BRCA1 185delAG and 5382insC/BRCA2 6174delT negative Portuguese women. The study population consisted of 107 patients with histological diagnosis of breast cancer and 121 women with no history of breast cancer. Genomic DNA was extracted from blood samples and genotyping analyses were performed by PCR–RFLP. XbaI polymorphism was associated with a significant reduced risk of breast cancer for carriers of the x allele in homozygozity (OR 0.178; 95 % CI 0.070–0.456; P < 0.001) or heterozigozity (OR 0.223; 95 % CI 0.089–0.561; P = 0.001). The PvuII polymorphism was associated with a non-significantly reduced risk. The combined analysis of PvuII and XbaI polymorphisms revealed none synergistic effect of the two genotypes, except for simultaneous carriers of pp and xx genotypes, that have a reduced risk of breast cancer (OR 0.226; 95 % CI 0.049–1.035; P = 0.044). The combination of PvuII and XbaI genotypes into haplotypes showed that carriers of two copies of the px (ppxx) haplotype had a reduced risk of breast cancer (OR 0.405; 95 % CI 0.194–0.843; P = 0.014), compared with PX (PPXX + PPXx + PpXX + PpXx) haplotypes. PvuII and XbaI polymorphisms were in linkage disequilibrium both in cases (D = 0.044, r2 = 0.049, X2 = 5.216, P = 0.022) and controls (D = 0.090, r2 = 0.139, X2 = 16.819, P < 0.001), but not in the entire sample population analyzed as a whole (D = 0.087, r2 = 0.0076, X2 = 1.733, P = 0.188). In conclusion, in this case–control study we found that ERα gene XbaI polymorphism may modify individual susceptibility for breast cancer in this population. 相似文献
35.
Phylogenetic screening of the human genome: identification of differentially hybridizing repetitive sequence families 总被引:1,自引:0,他引:1
The phi-screen, a method of phylogenetic screening, can be employed to
detect repetitive sequence families that differentially hybridize between
closely related species. Such differences may involve sequence divergence
or variations in copy number, including total presence versus absence of a
family of repeated DNA. We present the results of a phi-screen comparing
the human genome to that of the prosimian, Galago crassicaudatus. Three
human repetitive families that are divergent or not present in galago have
been detected. One of these families is described in detail; it is similar
among the anthropoids but is present in a lower copy number and/or
divergent form in prosimians. The family is clearly related to the
transposon-like human element (THE) described by Paulson et al. (1985).
THEs have long terminal repeats reminiscent of retroviruses but are unique
in that they have no sequence similarity to known mammalian retroviruses.
The sequence of a solo long terminal repeat, found unassociated with THE
internal sequence, is presented. This family member, THE p2, is bordered by
a 5-bp target-site repeat and is interrupted by the insertion of an Alu
element. A solo THE element sequenced by Wiginton et al. (1986) contains an
insertion of Alu at precisely the same position as does THE p2.
相似文献
36.
Miguel L Soares Seiki Haraguchi Maria-Elena Torres-Padilla Tibor Kalmar Lee Carpenter Graham Bell Alastair Morrison Christopher JA Ring Neil J Clarke David M Glover Magdalena Zernicka-Goetz 《BMC developmental biology》2005,5(1):1-11
Background
Studies of gene function in the mouse have relied mainly on gene targeting via homologous recombination. However, this approach is difficult to apply in specific windows of time, and to simultaneously knock-down multiple genes. Here we report an efficient method for dsRNA-mediated gene silencing in late cleavage-stage mouse embryos that permits examination of phenotypes at post-implantation stages.Results
We show that introduction of Bmp4 dsRNA into intact blastocysts by electroporation recapitulates the genetic Bmp4 null phenotype at gastrulation. It also reveals a novel role for Bmp4 in the regulation the anterior visceral endoderm specific gene expression and its positioning. We also show that RNAi can be used to simultaneously target several genes. When applied to the three murine isoforms of Dishevelled, it leads to earlier defects than previously observed in double knock-outs. These include severe delays in post-implantation development and defects in the anterior midline and neural folds at headfold stages.Conclusion
Our results indicate that the BMP4 signalling pathway contributes to the development of the anterior visceral endoderm, and reveal an early functional redundancy between the products of the murine Dishevelled genes. The proposed approach constitutes a powerful tool to screen the functions of genes that govern the development of the mouse embryo. 相似文献37.
38.
Maize (Zea mays L.) tortilla is the major staple food for the Mexican population. Nine tropical maize genotypes were evaluated. All samples had white grains, a common characteristic in tropical maize, and therefore they were appropriate for nixtamalized flour industry. Grain, flour, masa and tortilla characteristics of each maize genotype were evaluated. Length, width, thickness, weight of 1000 grains and hardness of grain were determined. Moisture content, proteins, fat, ash, mean particle size, water absorption index, enthalpy, and flour temperature were also evaluated. Adhesiveness and cohesiveness were evaluated in masa. Moisture content, protein, capacity to puff up, roll making, tension and cutting strength were determined in tortillas. There were significant differences (p≤0.05) in most of the evaluated characteristics. Grain length values varied between 9.26 and 11.02 mm for populations 23 and 22, respectively. Grain hardness oscillated between 11.17 (population 32) and 14.75 (landrace Mejen). According to the weight of 1000 grains most genotypes had small grains. The minimum and maximum moisture values of flour and tortillas were 8.33-9.99% and 46.20-50.36%, respectively. The texture of tortillas elaborated from population 32 and landrace Mejen had the lowest tension and cutting strength, resulting the best genotypes for making tortilla. 相似文献
39.
40.
Beneficial effect of fluorocarbon emulsion media on the function of neuromuscular preparations in vitro 下载免费PDF全文
The effects of liquid fluorocarbons as bathing media were determined by use of in vitro neuromuscular preparations. Rat hemidiaphragms were bathed in either oxygenated fluorocarbon (FC) emulsion or standard oxygenated Krebs solution. Contractile force in response to simple supramaximal nerve stimuli as well as to high frequency stimulation was greater, while twitch:tetanus ratio was smaller in FC emulsion. With such medium, post-tetanic potentiation of contraction was also more consistently observed. Indirectly stimulated diaphragms survived longer in FC emulsion. After cessation of oxygenation, oxygen tension (ρO(2)) of the medium declined more rapidly with Krebs than with FC emulsion; ρO(2) directly correlated with force of contraction. Similarly, in the chick biventer cervicis preparation, FC emulsion enhanced nerve-stimulated force of contraction; returning the preparation to standard Krebs solution reversed this phenomenon. Dose-resonse curves of muscle contraction in response to acetycholine and KCl administration were shifted upward during FC emulsion superfusion. Frequency of miniature endplate potentials was lower in FC emulsion than that observed in Krebs solution, measured from the same cell of the rat diaphragm. Resting membrane potentials were also greater in muscle cells sampled from FC emulsion-bathed preparations. These data suggest that FC emulsion is superior to standard Krebs solution as a bathing medium for in vitro neuromuscular preparations by virtue of the high solubility of oxygen in it. 相似文献