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381.
Apart from controlling energy balance, leptin, a peptide hormone secreted by white adipose tissue, is also involved in the regulation of cardiovascular function. Previous studies have documented that leptin stimulates natriuresis and nitric oxide (NO) production, but the mechanism of these effects is incompletely elucidated. We examined whether phosphoinositide 3-kinase (PI3K) and its downstream effector, protein kinase B/Akt are involved in acute natriuretic and NO-mimetic effects of leptin in anaesthetized rats. Leptin (1 mg/kg i.v.) induced a marked increase in natriuresis and this effect was abolished by pretreatment with either wortmannin (15 μg/kg) or LY294002 (0.6 mg/kg), two structurally different PI3K inhibitors. Moreover, leptin increased plasma concentration and urinary excretion of NO metabolites, nitrites + nitrates (NOx), and of NO second messenger, cyclic GMP. In addition, leptin increased NOx and cGMP in aortic tissue. The stimulatory effect of leptin on NOx and cGMP was prevented by PKB/Akt inhibitor, triciribine, but not by either wortmannin or LY294002. Triciribine had no effect on leptin-induced natriuresis. Leptin stimulated Akt phosphorylation at Ser473 in aortic tissue but not in the kidney. These results suggest that leptin-induced natriuresis is mediated by PI3K but not Akt, whereas NO-mimetic effect of leptin results from PI3K-independent stimulation of Akt. 相似文献
382.
It has been recently well documented that metal transport systems play a crucial role in the uptake, distribution and detoxification of heavy metals throughout the plant. A range of gene families that are likely to be involved in essential and non-essential metal transport has been now identified and their plasma membrane and/or tonoplast localization in plant cells has been recently confirmed. These include the primary metal transporters, using ATP as the source of energy and H(+)-coupling transporters, utilizing the electrochemical gradient previously generated by plasma membrane and tonoplast proton pumps. As the presence of nucleotide binding domains in the protein sequence may indicate its ATP-hydrolytic activity, it is more difficult to determine the H(+)-coupling activity of protein on the base of its structure. Thus, the H(+)-coupling activity of protein may be only proved by functional analysis of the protein. In this work, we briefly review the structure, regulation and function of the metal transporters operating as H(+)/metal cotransporters. 相似文献
383.
384.
Młynarczyk G Młynarczyk A Szymanek K Bilewska A Luczak M 《Medycyna do?wiadczalna i mikrobiologia》2007,59(1):17-25
For 31 clinical strains of S. aureus the correlation between phenotype and genotype of resistance to macrolides, lincosamides and streptogramins B (MLSB) was established.. Phenotypes were determined on the basis of: susceptibility to erythromycin and clindamycin and the ability to an induction of the resistance (phenotypes S, susceptible; R , constitutive resistant, D, resistant after induction with erythromycin, D+, resistant after induction with erythromycin and with a presence of the small colonies inside inhibition zone between erythromycin and clindamycin discs), and on the basis of the resistance to spectinomycin (spR, resistant, spS, susceptible). Among examined S. aureus strains eight phenotypes of resistance to MLSB were recognized (the corresponding genotypes are given in brackets). Six phenotypes were typical: SspS (lack of MLS-B resistance genes), NEGspS (msrA/B, 1 strain), D+spS (ermCi, 4 strains),. DspR (ermAi, 11 strains and ermAi + msrA/B, 2 strains), RspR (ermAc, 4 strains and ermA + msrA/B,1 strain and ermA + ermC, 1 strain) and RspS (ermCc, 6 strains and ermB, 1 strain). Two rare phenotypes in two single strains were observed: SspR (ermAi, the strain with altered inducibility, inductor other than erythromycin) and DspS (ermAi, presumably mutation or lack of spc in Tn554). 相似文献
385.
386.
387.
Letizia Nicoloso Lorenzo Bomba Licia Colli Riccardo Negrini Marco Milanesi Raffaele Mazza Tiziana Sechi Stefano Frattini Andrea Talenti Beatrice Coizet Stefania Chessa Donata Marletta Mariasilvia D’Andrea Salvatore Bordonaro Grazyna Ptak Antonello Carta Giulio Pagnacco Alessio Valentini Fabio Pilla Paolo Ajmone-Marsan Paola Crepaldi the Italian Goat Consortium 《遗传、选种与进化》2015,47(1)
Background
Among the European countries, Italy counts the largest number of local goat breeds. Thanks to the recent availability of a medium-density SNP (single nucleotide polymorphism) chip for goat, the genetic diversity of Italian goat populations was characterized by genotyping samples from 14 Italian goat breeds that originate from different geographical areas with more than 50 000 SNPs evenly distributed on the genome.Results
Analysis of the genotyping data revealed high levels of genetic polymorphism and an underlying North–south geographic pattern of genetic diversity that was highlighted by both the first dimension of the multi-dimensional scaling plot and the Neighbour network reconstruction. We observed a moderate and weak population structure in Northern and Central-Southern breeds, respectively, with pairwise FST values between breeds ranging from 0.013 to 0.164 and 7.49 % of the total variance assigned to the between-breed level. Only 2.11 % of the variance explained the clustering of breeds into geographical groups (Northern, Central and Southern Italy and Islands).Conclusions
Our results indicate that the present-day genetic diversity of Italian goat populations was shaped by the combined effects of drift, presence or lack of gene flow and, to some extent, by the consequences of traditional management systems and recent demographic history. Our findings may constitute the starting point for the development of marker-assisted approaches, to better address future breeding and management policies in a species that is particularly relevant for the medium- and long-term sustainability of marginal regions.Electronic supplementary material
The online version of this article (doi:10.1186/s12711-015-0140-6) contains supplementary material, which is available to authorized users. 相似文献388.
Grazyna Barbacka-Surowiak 《Biological Rhythm Research》2000,31(5):531-544
The phase-response curves (PRC) for light pulses in continuous darkness (DD) have been described in many mammals, especially in nocturnal rodents. The PRC for dark pulses in continuous light (LL), however, has been described in a few mammals only, in nocturnal for bat and for hamster and in diurnal for Octodon degus, suggesting that this PRC is mirror imaging the PRC for light pulses. Therefore, the effect of 1-h and 3-h lasting dark pulses on the circadian wheel-running activity rhythm of mice in continuous light was investigated and then the PRC for dark pulses in LL was drawn up. For comparison, the effect of 1-h lasting light pulses on the circadian wheel-running activity rhythm of mice in DD was examined and the PRC for light pulses in DD was constructed. It appeared that the PRC for dark pulses, to a certain degree, represents a mirror image of the PRC for light pulses in mice. However, the advance region of this PRC is longer than that of delay. The mechanism of dark pulses action is discussed. 相似文献
389.
Jadwiga Chmielnicka Elzbieta Komsta-Szumska Grazyna Zaręba 《Biological trace element research》1988,17(1):285-292
Distribution and retention of zinc in the presence of cadmium and copper was studied in rats exposed repeatedly to these metals.
The experiment was performed on white rats of the Wistar strain. The animals were divided into four groups/five rats each:
1)65ZnCl2; 2)65ZnCl2+CdCl2; 3)65ZnCl2+CuCl2; and 4) control group. Rats were administered sc every other day for two weeks:65ZnCl2−5 mg Zn/kg; CdCl2−0,3 Cd/kg; and CuCl2−2 mg Cu/kg. The zinc content was measured in rat tissues by γ-counting. Effect of Cd and Cu on subcellular distribution of
zinc in the kidney and liver and on the level of metallothionein were also examined.
Whole body retention of zinc under the influence of cadmium was lower than that observed in animals treated with zinc alone.
However, copper increased twofold the whole body retention of zinc. Cadmium elevated the accumulation of zinc only in the
kidneys nuclear fraction and liver soluble fraction.
In the kidneys and liver, copper elevated the accumulation of zinc, in the nuclear, mitochondrial, and soluble fractions.
The level of metallothionein-like proteins (MT) in the kidneys after a combined supply of zinc and copper was significantly
increased with respect to the group of animals treated with zinc alone.
These results indicated complex interactions between cadmium, copper, and zinc that can affect the metabolism of each of the
metals. 相似文献
390.
The experiment was performed on female rabbits that receivedper os equimolar doses (17 μM Me/kg) of SnCl2×2H2O or Pb (CH3 COO)2 every day for 5 d. The activity of δ-aminolevulinic acid dehydratase (ALA-D) in the whole blood, liver, kidneys, brain, spleen,
and bone marrow, concentration of free erythrocyte protoporphyrins (FEP), activity of δ-aminolevulinic acid synthetase (ALA-S)
in the liver and bone marrow, urine δ-aminolevulinic acid (ALA-U), and coproporphyrins (CP-U) were determined. Lead and tin
concentrations in the blood were estimated.
Lead caused a significant inhibition of ALA-D in the blood, increased FEP concentration, and ALA and CP excretion in urine
of rabbits. Lead also decreased ALA-D activity in the bone marrow and in the liver, and did not change ALA-2 activity in the
liver and bone marrow.
Tin did not change any of the examined indices. Tin doses applied in the present study, maintained within the limits of permissible
standards of metal levels in human diet, did not affect the process of heme biosynthesis in rabbits. 相似文献