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191.
Forbes SH; Hogg JT; Buchanan FC; Crawford AM; Allendorf FW 《Molecular biology and evolution》1995,12(6):1106-1113
We compared genotypes at eight (AC)n microsatellite loci in domestic sheep
(Ovis aries) and wild Rocky Mountain bighorn sheep (O. canadensis). The
domestic sheep had greater genetic variation, higher allele-size variances,
and larger allele sizes than the wild sheep. Accumulating evidence from
higher taxonomic comparisons shows that these parameters are biased if
microsatellite loci are selected in one taxon and used in another. Our
results demonstrate similar biases between congeneric species. We compared
standard measures of genetic variation, differentiation, and distance
within and between species (H, D, FST) to newer measures based on
allele-size variance (SW, SB, RST). The size-based distances better
detected species-level divergence, but standard measures better
distinguished allopatric populations. Empirical calibration of these
measures at the subspecies level is needed to establish their useful
ranges.
相似文献
192.
A plasmid library of Acinetobacter calcoaceticus HindIII fragments was
constructed, and clones that complemented an Escherichia coli pabA mutant
were selected. Plasmids containing a 3.9-kb fragment of A. calcoaceticus
DNA that also complemented E. coli trpD and trpC-(trpF+) mutants were
obtained. We infer that complementation of E. coli pabA mutants was the
result of the expression of the amphibolic anthranilate-
synthase/p-aminobenzoate-synthase glutamine-amidotransferase gene and that
the plasmid insert carried the entire trpGDC gene cluster. In E. coli
minicells, the plasmid insert directed the synthesis of polypeptides of
44,000, 33,000, and 20,000 daltons, molecular masses that are consistent
with the reported molecular masses of phosphoribosylanthranilate
transferase, indoleglycerol-phosphate synthase, and anthranilate-synthase
component II, respectively. A 3,105- bp nucleotide sequence was determined.
Comparison of the A. calcoaceticus trpGDC sequences with other known trp
gene sequences has allowed insight into (1) the evolution of the amphibolic
trpG gene, (2) varied strategies for coordinate expression of trp genes,
and (3) mechanisms of gene fusions in the trp operon.
相似文献
193.
F. F. Duque M. C. P. Neves A. A. Franco R. L. Victoria R. M. Boddey 《Plant and Soil》1985,88(3):333-343
Summary A field experiment was performed to assess the effects of Rhizobium inoculation and nitrogen fertilizer (100 kg N ha–1) on four cultivars of Phaseolus beans; Carioca, Negro Argel, Venezuela 350 and Rio Tibagi. In the inoculated treatment 2.5 kg N ha–1 of15N labelled fertilizer was added in order to apply the isotope dilution technique to quantify the contribution of N2 fixation to the nutrition of these cultivars.Nodulation of all cultivars in the uninoculated treatments was poor, but the cultivars Carioca and Negro Argel were well nodulated when inoculated. Even when inoculated, nodulation of the cultivars Venezuela 350 and Rio Tibagi was poor and these cultivars showed little response to inoculation in terms of nitrogen accumulation or grain yield. The estimates of the contribution of N2 fixation estimated using the isotope dilution technique, for the Carioca and Negro Argel cultivars, amounted to 31.7 and 18.4 kg N ha–1 respectively. These two cultivars produced 991 and 883 kg ha–1 of grain, respectively, when inoculated and 663 and 620 kg ha–1 with the addition of 100 kg N ha–1 of N fertilizer. The response to nitrogen was particularly poor due to high leaching losses in the very sandy soil at the experimental site.The Venezuela 350 and Rio Tibagi cultivars only responded to N fertilizer and not to inoculation with Rhizobium which stresses the great importance of selecting plant cultivars for nitrogen fixation in the field. 相似文献
194.
Bellis M; Jubier-Maurin V; Dod B; Vanlerberghe F; Laurent AM; Senglat C; Bonhomme F; Roizes G 《Molecular biology and evolution》1987,4(4):351-363
The presence of the L1 sequences, L1Md4 next to the pseudogene beta h3 and
I12 found in the twelfth intron of the albumin gene, in certain strains of
laboratory mice but not of others has led to the suggestion that these
sequences were recent insertions into the Mus mus domesticus genome. To be
sure that they are really recent insertions and not relics of an ancestral
chromosome, we investigated the presence or absence of these sequences in
populations of wild mice belonging to the semispecies M. m. domesticus and
M. m. musculus as well as in other species of the genus Mus and in related
murids. The sequence I12 in the albumin gene was found in 34% of the
chromosomes of the wild mice belonging to M. m. domesticus and to a lesser
extent (6%) in M. m. musculus. Of 114 M. m. domesticus chromosomes, L1Md4
was found in only nine, seven of which came from the same locality. Its
presence was associated with the haplotype Hbbp, which is relatively rare
in European populations of M. musculus. Since there was no evidence for the
presence of these two L1 sequences in more distantly related species, we
conclude that they are recent insertions in the M. musculus genome.
相似文献
195.
B Chevassus JM Blanc P Bergot L Casenave AM Escaffre F Hérioux N Kaushik R Lanneberre 《遗传、选种与进化》1979,11(1):79-92
196.
Bassi AM Romano P Mangini S Colombo M Canepa C Nanni G Casu A 《Journal of biomedical science》2005,12(3):457-466
Summary We analysed the action, in rats in vivo, of the protein isoprenylation inhibitor perillyl alcohol (POH) and that of vitamin A, alone or in association, on m-RNA and protein expression of farnesyltransferases (FTases α and β subunits) and their protein substrates RhoA and RhoB, in isolated hepatocytes. Combined administration of POH and vitamin A induced a sharp decrease in FTase α protein after 96 h, suggesting an involvement not only of farnesyltransferases but also of geranylgeranyltransferases, which share the FTase α protein. FTase β protein did not decrease. POH plus vitamin A, in contrast with POH or vitamin A alone, induced a decrease in RhoB protein, probably because of different cleavages. No modification was observed in RhoA protein. Vitamin A alone increased RhoB m-RNA and protein expression. As one of the functions of RhoB is cell polarisation, these data support our previous hypothesis of a polarised transport of vitamin A from hepatocytes to hepatic stellate cells. As the behaviours of m-RNAs and proteins in this study were often different, cytoplasmic metabolic pathways must be considered for the parameters studied. The behaviour of Rho B, which is thought to have an antioncogene function, is discussed in view of its isoprenylated forms in the membranes. These preliminary findings stress the need, when studying the association of two isoprenoids in cancer therapy, to consider normal as well as tumour-bearing animals. 相似文献
197.
Bovine oocyte vitrification before or after meiotic arrest: effects on ultrastructure and developmental ability 总被引:3,自引:0,他引:3
Diez C Duque P Gómez E Hidalgo CO Tamargo C Rodríguez A Fernández L de la Varga S Fernández A Facal N Carbajo M 《Theriogenology》2005,64(2):317-333
The nuclear stage at which oocytes are cryopreserved influences further development ability and cryopreservation affects ultrastructure of both cumulus cells and the oocyte. In this work, we analyze the effects of vitrification at different nuclear and cytoplasmic maturation stages on the oocyte ultrastructure and developmental ability. Culture in TCM199 + PVA with roscovitine 25 M during 24h led to meiotic arrest (MA) in cumulus-oocyte complexes (COCs), while permissive in vitro maturation (IVM) was performed in TCM199, 10% FCS, FSH-LH and 17beta-estradiol for 24 h. Oocytes were vitrified using the open pulled straw method (OPS) with minor modifications. Fresh and vitrified/warmed COCs were fixed as immature, after IVM, after meiotic arrest (MA) and after MA + IVM. Vitrification combined with MA followed by IVM produced the highest rates of degeneration, regardless of the vitrification time. As a consequence, lower proportions of embryos cleaved in these groups, although differences were eliminated at the five-eight cell stage. Development rates up to day 8 were similar in all experimental groups, being significantly lower than those in fresh controls. Only oocytes vitrified after IVM were able to give blastociysts. The morphological alterations observed can be responsible for compromised development. More research is needed to explain the low survival rates of the bovine oocyte after vitrification and warming. 相似文献
198.
199.
Transcriptional phase variation at the flhB gene of Pseudomonas putida DOT-T1E is involved in response to environmental changes and suggests the participation of the flagellar export system in solvent tolerance
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Frameshift mutations in a poly(G) track at the flhB gene of Pseudomonas putida DOT-T1E are responsible for the diminished swimming of this strain on semisolid medium, which contrasts with the high swimming ability of P. putida KT2440, which does not exhibit a poly(G) track at the flhB gene. We previously showed that a mutant lacking FlhB was more sensitive to solvents than the wild-type strain (Segura et al., J. Bacteriol., 183:4127-4133, 2001). In this study, we show that swimming ability correlates with solvent tolerance in P. putida DOT-T1E, so that growth conditions favoring a functional flhB gene (growth on semisolid medium) resulted in increased innate tolerance to a sudden toluene shock. 相似文献
200.
Hidalgo CO Gómez E Prieto L Duque P Goyache F Fernández L Fernández I Facal N Díez C 《Theriogenology》2004,62(3-4):664-676
The objective of this study was to determine the effect of a sustained propylene glycol administration to recipients of frozen/thawed in vivo derived bovine embryos. Heifers were treated with oral propylene glycol for the last 20 days before embryo transfer (n = 142), and untreated as controls (n = 133). Progesterone, insulin, insulin-like growth factor-I, glucose, urea and triglyceride were analysed in blood on Day 0 and Day 7 of the estrous cycle corresponding to embryo transfer. The heifers were selected as recipients when showing progesterone levels <2.0 ng/ml (Day 0) and >2.5 ng/ml (Day 7), according to corpus luteum quality on Day 7 by technicians unaware of animals treated. Within treated animals, significantly more recipients were selected, and increased progesterone, corpus luteum quality, pregnancy and calving rates were recorded. Day 7 progesterone concentrations were higher in heifers treated and transferred. Propylene glycol increased insulin and insulin-like-growth factor-I, but glucose, urea and triglyceride did not vary. Furthermore, insulin-like-growth factor-I, glucose and triglyceride increased at estrous time, but urea decreased and insulin remained unaltered. Together with the sustained gain in pregnancy rates throughout the experiment (2 years), other evidences suggested that the observed effects did not rely on nutritional deficiency. Thus, propylene glycol improved pregnancy rates after embryo-transfer, and progesterone, insulin and insulin-like-growth factor-I are probably involved in this effect. 相似文献