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排序方式: 共有259条查询结果,搜索用时 15 毫秒
1.
L V Filev S F Enokhin N N Kotsiubinski? D I Korotkov B G Liparteliani 《Tsitologiia》1988,30(4):466-470
10 healthy men underwent a 48 hour acute hypobaric hypoxia in the "Taba?" climate chamber imitating conditions of an altitude of 4.00 m. above s.l. The "ascent" and "descent" took 30 minutes each. Blood and bone marrow samples were taken before entering the chamber and immediately after leaving it. A decrease in colony-forming capacity of granulo- and monocyte and fibroblast precursors was shown, along with an increase in functional activity of circulating monocytes and monocyte precursors in bone marrow. A possible role of changes in granulo- and monocytopoiesis and in stromal cells is discussed in relation to the increased morbidity and decreased cicatricial and bone tissue reparation in the mountains. 相似文献
2.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
3.
The concept of nucleic acid sequence base alternations is presented.The number of base alterations for the sequences of differentlength is established. The definition of "enlarged similarity"of nucleic acids sequences on the basis of sequence base alterationsis introduced. Mutual information between sequences is usedas a quantitative measure of enlarged similarity for two comparedsequences. The method of mutual information calculation is developedconsidering the correlation of bases in compared sequences.The definitions of correlated similarity and evolution similaritybetween compared sequences are given. Results of the use ofenlarged similarity approach for DNA sequences analysis arediscussed. 相似文献
4.
Evolutionary origin of human and primate malarias: evidence from the circumsporozoite protein gene 总被引:8,自引:1,他引:7
We have analyzed the conserved regions of the gene coding for the
circumsporozoite protein (CSP) in 12 species of Plasmodium, the malaria
parasite. The closest evolutionary relative of P. falciparum, the agent of
malignant human malaria, is P. reichenowi, a chimpanzee parasite. This is
consistent with the hypothesis that P. falciparum is an ancient human
parasite, associated with humans since the divergence of the hominids from
their closest hominoid relatives. Three other human Plasmodium species are
each genetically indistinguishable from species parasitic to nonhuman
primates; that is, for the DNA sequences included in our analysis, the
differences between species are not greater than the differences between
strains of the human species. The human P. malariae is indistinguishable
from P. brasilianum, and P. vivax is indistinguishable from P. simium; P.
brasilianum and P. simium are parasitic to New World monkeys. The human P.
vivax-like is indistinguishable from P. simiovale, a parasite of Old World
macaques. We conjecture that P. malariae, P. vivax, and P. vivax-like are
evolutionarily recent human parasites, the first two at least acquired only
within the last several thousand years, and perhaps within the last few
hundred years, after the expansion of human populations in South America
following the European colonizations. We estimate the rate of evolution of
the conserved regions of the CSP gene as 2.46 x 10(-9) per site per year.
The divergence between the P. falciparum and P. reichenowi lineages is
accordingly dated 8.9 Myr ago. The divergence between the three lineages
leading to the human parasites is very ancient, about 100 Myr old between
P. malariae and P. vivax (and P. vivax-like) and about 165 Myr old between
P. falciparum and the other two.
相似文献
5.
Photosynthetic enhancement studies performed at 619 nm (excitation of Systems I and II) and at 446 nm (mainly excitation of System I) revealed an 18% photosynthetic enhancement simultaneously with a 31% reduction in glycolate excretion. This observation supports the hypothesis that some glycolate may be consumed in an oxidation process associated with System I when System II is poorly excited and the supply of electrons from the water splitting process of photosynthesis is low. 相似文献
6.
7.
Pamela McElwee Katherine Calvin Donovan Campbell Francesco Cherubini Giacomo Grassi Vladimir Korotkov Anh Le Hoang Shuaib Lwasa Johnson Nkem Ephraim Nkonya Nobuko Saigusa Jean‐Francois Soussana Miguel Angel Taboada Frances Manning Dorothy Nampanzira Pete Smith 《Global Change Biology》2020,26(9):4691-4721
Interlocked challenges of climate change, biodiversity loss, and land degradation require transformative interventions in the land management and food production sectors to reduce carbon emissions, strengthen adaptive capacity, and increase food security. However, deciding which interventions to pursue and understanding their relative co‐benefits with and trade‐offs against different social and environmental goals have been difficult without comparisons across a range of possible actions. This study examined 40 different options, implemented through land management, value chains, or risk management, for their relative impacts across 18 Nature's Contributions to People (NCPs) and the 17 Sustainable Development Goals (SDGs). We find that a relatively small number of interventions show positive synergies with both SDGs and NCPs with no significant adverse trade‐offs; these include improved cropland management, improved grazing land management, improved livestock management, agroforestry, integrated water management, increased soil organic carbon content, reduced soil erosion, salinization, and compaction, fire management, reduced landslides and hazards, reduced pollution, reduced post‐harvest losses, improved energy use in food systems, and disaster risk management. Several interventions show potentially significant negative impacts on both SDGs and NCPs; these include bioenergy and bioenergy with carbon capture and storage, afforestation, and some risk sharing measures, like commercial crop insurance. Our results demonstrate that a better understanding of co‐benefits and trade‐offs of different policy approaches can help decision‐makers choose the more effective, or at the very minimum, more benign interventions for implementation. 相似文献
8.
M. V. Kireev N. S. Medvedeva A. D. Korotkov Ju. I. Polyakov A. D. Anichkov S. V. Medvedev 《Human physiology》2013,39(1):54-57
In this article, the characteristics of the functional activity of the anterior cingulate cortex (ACC), a key element of the neuroanatomical error detection system of the brain in drug-resistant forms of obsessive-compulsive disorder (OCD) are discussed on the basis of both original and published data. Available data indicate the presence of a functional deficit zone in the ACC during PCD. This fact suggests that the functions of the ACC in OCD patients are partially redistributed between other brain areas. Thus, in contrast to the previously accepted ideas, the target of stereotactic surgery for OCD is a pathologically altered brain region. Probably, this explains the fact that the operation does not lead to significant changes in the patient’s psyche. The pathological reorganization of the functional activity of the brain in OCD remains unclear and requires further investigation. 相似文献
9.
S. M. Korotkov K. V. Sobol I. V. Shemarova V. V. Furaev A. R. Shumakov V. P. Nesterov 《Biophysics》2016,61(5):733-740
The inotropic effect of Pr3+ and La3+ ions on the heart muscle of frog Rana ridibunda, as well as the influence of the ions on respiration, swelling, and the potential (ΔΨmito) on the inner membrane of Ca2+- loaded rat heart mitochondria, energized by glutamate and malate or succinate in the presence of rotenone were studied. It was found that 2 mM Pr3+ in Ringer’s solution reduces the force of spontaneous contractions and those induced by electrical stimulation in the heart; it had a negative chronotropic effect, decreasing the frequency of spontaneous contractions. Pr3+ and La3+ prevented a decrease in the 2,4-dinitrophenol (DNP)- uncoupled respiration of energized rat heart mitochondria, swelling of these organelles in salt media, and a reduction in ΔΨmito on the inner mitochondrial membrane that were induced by Ca2+ ions. Retardation by Pr3+ and La3+ ions of these calcium-induced effects may suggest that in the inner mitochondrial membrane these metals inhibit the opening of the mitochondrial permeability transition pore caused by Ca2+ overload of mitochondria. The data we obtained are important for a better understanding of the mechanisms of the damaging action of rare-earth elements on Ca2+-dependent processes in the vertebrate myocardium. 相似文献
10.
The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice 下载免费PDF全文
S Gohin A Carriero C Chenu AA Pitsillides TR Arnett M Marenzana 《Cell biochemistry and function》2016,34(2):52-62
There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd. 相似文献