共查询到20条相似文献,搜索用时 62 毫秒
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Growth and ploidy of rat ventricular myocytes were studied during development in situ and in grafts (1 day old rat ventricle transplanted under kidney capsule of syngenic adult animals). Both in situ and in the transplants polyploidization occurred on days 4-14 of postnatal life, and the modal group of myocytes was represented by binucleate diploid (2c x 2) cells. Minor quantities of 4c, 4c x 2, 8c and 2c x 4 myocytes were detected as well. In ventricles of 14 and 28 days old rats and in the transplants of the corresponding age the portion of polyploid myocytes was 90-96% and 32-63% respectively. The intensity of postmitotic myocyte transplants was decreased as compared with in situ development, and cells that exit proliferation cycle did not grow until day 14. The data on thymidine label dilution suggest that diploid myocytes of the transplant can divide two or three times but the majority of labeled diploids divided only once. Labeled 2c x 2 myocytes originated from the first, and less frequently, the second cell generation or resulted from initial acytokinetic mitosis. Mononucleate tetraploids 4c originated from 2c x 2 and mostly from 2c cells. Octaploids were formed after 3d or 4th labeled mitosis. The conclusion about cardiac myocyte polyploidization as an intrinsic developmental program is supported, implying the programming of onset, mode, duration and termination of polyploidization and its prolongation during early postnatal life.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Wolfgang Lieb Alisa K. Manning Jose C. Florez Josée Dupuis L. Adrienne Cupples Jarred B. McAteer Ramachandran S. Vasan Udo Hoffmann Christopher J. O'Donnell James B. Meigs Caroline S. Fox 《Obesity (Silver Spring, Md.)》2009,17(4):755-760
Pharmacologic blockade of the endocannabinoid receptor 1 leads to weight loss and an improved metabolic risk profile in overweight and obese individuals. We hypothesize that common genetic variants in the CNR1 (encoding endocannabinoid receptor 1) and FAAH genes (encoding fatty acid amide hydrolase, a key enzyme hydrolyzing endocannabinoids) are associated with adiposity traits. We genotyped 18 single‐nucleotide polymorphisms (SNPs) in the CNR1 gene and 9 SNPs in the FAAH gene in 2,415 Framingham Offspring Study participants (mean age 61 ± 10 years; 52.6% women; mean BMI 28.2 ± 5.4 kg/m2; 30.3% obese) and studied them for association with cross‐sectional and longitudinal measures of adiposity (BMI, waist circumference, change over time in BMI and waist circumference, visceral and subcutaneous adipose tissue) using linear mixed‐effect models. The selected SNPs captured 85% (r2 = 0.8) of the common variation (minor allele frequency >5%) at the CNR1 locus and 96% (r2 = 0.8) of the common variation at the FAAH locus (defined as the genomic segment containing the gene +20 kb upstream and +10 kb downstream). After correction for multiple testing, none of the SNPs in the CNR1 gene or in the FAAH gene displayed statistical evidence for association with BMI, waist circumference, and visceral adipose tissue or subcutaneous adipose tissue (all P > 0.18). Despite comprehensive SNP mapping across the genes and their regulatory regions in a large unselected sample, we failed to find evidence for an association of common variants in the CNR1 and FAAH genes with measures of adiposity in our community‐based sample. 相似文献
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本文简要介绍了植物基因组领域主要的组织和计划,简单分析了国际植物基因组计划的特点和我国存在的问题,并初步提出我国的应对策略。 相似文献
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Romanov SP Aleksanian ZA Manoĭlov VV 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2002,88(10):1356-1368
With the aid of tensotremorography, a voluntary effort was recorded and characteristics of involuntary and voluntary components of the hands' isometrically recorded efforts were studied. The revealed frequency ranges of the oscillations spectral density's changes corroborate existence of two suprasegmental systems of movements control, the systems being related to voluntary control and a current control of the efforts maintaining or preserving a posture. Results of cross-correlation analysis of the hands' efforts maintained under conditions of a visual feedback are demonstrated in norm and in central disorders of the movement control system. 相似文献
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Mitochondria and ischemic reperfusion damage in the adult and in the developing brain 总被引:16,自引:0,他引:16
Blomgren K Zhu C Hallin U Hagberg H 《Biochemical and biophysical research communications》2003,304(3):551-559
The developing and the adult brain respond in similar ways to ischemia, but also display clear differences. For example, the relative contributions of necrosis and apoptosis to neuronal death may be different, such that apoptotic mechanisms would be more prevalent in the developing brain. During normal development, more than half of the neurons in some brain regions are removed through apoptosis, and effectors like caspase-3 are highly upregulated in the immature brain. Mitochondria are pivotal regulators of cell death through their role in energy production and calcium homeostasis, their capacity to release apoptogenic proteins and to produce reactive oxygen species. This review will summarize some of the current studies dealing with mitochondria-related mechanisms of ischemic brain damage, with special reference to developmental aspects. 相似文献
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Marc Yudkoff 《Neurochemical research》2017,42(1):10-18
Glutamatergic neurotransmission entails a tonic loss of glutamate from nerve endings into the synapse. Replacement of neuronal glutamate is essential in order to avoid depletion of the internal pool. In brain this occurs primarily via the glutamate-glutamine cycle, which invokes astrocytic synthesis of glutamine and hydrolysis of this amino acid via neuronal phosphate-dependent glutaminase. This cycle maintains constancy of internal pools, but it does not provide a mechanism for inevitable losses of glutamate N from brain. Import of glutamine or glutamate from blood does not occur to any appreciable extent. However, the branched-chain amino acids (BCAA) cross the blood–brain barrier swiftly. The brain possesses abundant branched-chain amino acid transaminase activity which replenishes brain glutamate and also generates branched-chain ketoacids. It seems probable that the branched-chain amino acids and ketoacids participate in a “glutamate-BCAA cycle” which involves shuttling of branched-chain amino acids and ketoacids between astrocytes and neurons. This mechanism not only supports the synthesis of glutamate, it also may constitute a mechanism by which high (and potentially toxic) concentrations of glutamate can be avoided by the re-amination of branched-chain ketoacids. 相似文献
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Caroline Humphrey 《American anthropologist》1997,99(1):153-155
After the USSR: Ethnicity, Nationalism, and Politics in the Commonwealth of Independent States. Anatoly M. Khazanov. Madison: University of Wisconsin Press, 1995. 311pp.
Who Gets the Past? Competition for Ancestors among Non-Russian Intellectuals in Russia. Victor A. Shnirelman. Washington, DC: Woodrow Wilson Center Press; Baltimore, MD: Johns Hopkins University Press, 1966. 98 pp.
In the Soviet House of Culture:. Century of Perestroikas. Bruce Grant. Princeton, NJ: Princeton University Press, 1995. 225 pp. 相似文献
Who Gets the Past? Competition for Ancestors among Non-Russian Intellectuals in Russia. Victor A. Shnirelman. Washington, DC: Woodrow Wilson Center Press; Baltimore, MD: Johns Hopkins University Press, 1966. 98 pp.
In the Soviet House of Culture:. Century of Perestroikas. Bruce Grant. Princeton, NJ: Princeton University Press, 1995. 225 pp. 相似文献
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Neural induction and patterning in the mouse in the absence of the node and its derivatives 总被引:2,自引:0,他引:2
The signals which induce vertebrate neural tissue and pattern it along the anterior-posterior (A-P) axis have been proposed to emanate from Spemann's organizer, which in mammals is a structure termed the node. However, mouse embryos mutant for HNF3 beta lack a morphological node and node derivatives yet undergo neural induction. Gene expression domains occur at their normal A-P axial positions along the mutant neural tubes in an apparently normal temporal manner, including the most anterior and posterior markers. This neural patterning occurs in the absence of expression of known organizer genes, including the neural inducers chordin and noggin. Other potential signaling centers in gastrulating mutant embryos appear to express their normal constellation of putative secreted factors, consistent with the possibility that neural-inducing and -patterning signals emanate from elsewhere or at an earlier time. Nevertheless, we find that the node and the anterior primitive streak, from which the node derives, are direct sources of neural-inducing signals, as judged by expression of the early midbrain marker Engrailed, in explant-recombination experiments. Similar experiments showed the neural-inducing activity in HNF3 beta mutants to be diffusely distributed. Our results indicate that the mammalian organizer is capable of neural induction and patterning of the neural plate, but that maintenance of an organizer-like signaling center is not necessary for either process. 相似文献
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Mikhail V. Chester Samuel Markolf Braden Allenby 《Journal of Industrial Ecology》2019,23(5):1006-1015
For centuries, man‐made infrastructure has been viewed as separate from natural systems. Yet in the past few centuries, as the scale and scope of human activities have dramatically increased, there is accumulating evidence that natural systems are becoming increasingly, and in some cases entirely, managed by humans. The dichotomy between infrastructure and the environment is narrowing, and natural systems are increasingly becoming human design spaces. This is already apparent with the management of hydrologic systems for urban water supply, wildlife, agriculture, forests, and even the atmosphere, and we can expect management of the environment to become more so as human activities grow. Yet our infrastructure largely remains obdurate. They are designed to last for long times even as changes in the environment and technology accelerate. As such, our current infrastructure paradigms fail at the level of the complex, integrated systems and behaviors that characterize the Anthropogenic Earth. Infrastructure in the future will need to be designed for adaptive capacity and the complexities associated with techno‐environmental systems. 相似文献