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61.
DNA excision repair and DNA damage-induced apoptosis are linked to Poly(ADP-ribosyl)ation but have different requirements for p53 总被引:10,自引:0,他引:10 下载免费PDF全文
Beneke R Geisen C Zevnik B Bauch T Müller WU Küpper JH Möröy T 《Molecular and cellular biology》2000,20(18):6695-6703
Poly(ADP-ribose) polymerase (PARP) is a DNA binding zinc finger protein that catalyzes the transfer of ADP-ribose residues from NAD(+) to itself and different chromatin constituents, forming branched ADP-ribose polymers. The enzymatic activity of PARP is induced upon DNA damage and the PARP protein is cleaved during apoptosis, which suggested a role of PARP in DNA repair and DNA damage-induced cell death. We have generated transgenic mice that lack PARP activity in thymocytes owing to the targeted expression of a dominant negative form of PARP. In the presence of single-strand DNA breaks, the absence of PARP activity correlated with a strongly increased rate of apoptosis compared to cells with intact PARP activity. We found that blockage of PARP activity leads to a drastic increase of p53 expression and activity after DNA damage and correlates with an accelerated onset of Bax expression. DNA repair is almost completely blocked in PARP-deficient thymocytes regardless of p53 status. We found the same increased susceptibility to apoptosis in PARP null mice, a similar inhibition of DNA repair kinetics, and the same upregulation of p53 in response to DNA damage. Thus, based on two different experimental in vivo models, we identify a direct, p53-independent, functional connection between poly(ADP-ribosyl)ation and the DNA excision repair machinery. Furthermore, we propose a p53-dependent link between PARP activity and DNA damage-induced cell death. 相似文献
62.
Zhang F Zhang W Liu L Fisher CL Hui D Childs S Dorovini-Zis K Ling V 《The Journal of biological chemistry》2000,275(30):23287-23294
We have cloned full-length human and mouse cDNAs of ABCB9, which encodes a predicted multiple-spanning transmembrane domain and a nucleotide-binding domain with Walker motifs. It is therefore designated as a "half" ATP binding cassette (ABC) transporter. Northern analysis shows that the ABCB9 mRNA is expressed at a high level in testes and moderate levels in brain and spinal cord. A splice variant mRNA deleted in the last pair of predicted transmembrane segments was shown to be expressed in human tissues. Phylogenetic analysis indicates that ABCB9 is closely related to TAP1 and TAP2, two "half" ABC proteins found in endoplasmic reticulum. ABCB9 protein colocalized with the lysosomal markers, LAMP1 and LAMP2, in transfected cells. ABCB9 protein appears to be most highly expressed in the Sertoli cells of the seminiferous tubules in mouse and rat testes. These cells have high levels of phagocytosis and secretory activities. These findings pave the way for further investigation into the potential novel function of ABCB9 in lysosomes. 相似文献
63.
陆地棉枯萎病抗性基因的等位性测定及连锁分析 总被引:5,自引:0,他引:5
冯纯大 张金发 刘金兰 郭介华 吴征彬 孙济中FENG Chun-Da ZHANG Jin-Fa LIU Jin-Lan GUO Jie-Hua WU Zheng-Bin SUN Ji-Zhong 《遗传》1998,20(1):33-36
1995-1996年,对我国育成的有代表性的5个抗病品种进行抗枯萎病基因的等位性测定。结果表明:在所选用的5个抗病品种中至少存在两个不同的抗病基因(暂定名为Fwl和Fw2)。连锁分析显示:Fwl与T586的8个标志性状间、Fw2与T582、T586的13个标志性状间无连锁关系。
Abstract:Allelism in vestigation of genes resistante to Fusarium wilt in cotton suggested that there were 2 genes(assigned symbols Fw1 and Fw2)in 5 cultivars used.No linkage was found between Fw1 and the marker genes in T586 and between Fw2 and those marker genes in T582 and T586. 相似文献
64.
Because to defect is the evolutionary stable strategy in the prisoner’s dilemma game (PDG), understanding the mechanism generating
and maintaining cooperation in PDG, i.e. the paradox of cooperation, has intrinsic significance for understanding social altruism
behaviors. Spatial structure serves as the key to this dilemma. Here, we build the model of spatial PDG under a metapopulation
framework: the sub-populations of cooperators and defectors obey the rules in spatial PDG as well as the colonization–extinction
process of metapopulations. Using the mean-field approximation and the pair approximation, we obtain the differential equations
for the dynamics of occupancy and spatial correlation. Cellular automaton is also built to simulate the spatiotemporal dynamics
of the spatial PDG in metapopulations. Join-count statistics are used to measure the spatial correlation as well as the spatial
association of the metapopulation. Simulation results show that the distribution is self-organized and that it converges to
a static boundary due to the boycotting of cooperators to defectors. Metapopulations can survive even when the colonization
rate is lower than the extinction rate due to the compensation of cooperation rewards for extinction debt. With a change of
parameters in the model, a metapopulation can consist of pure cooperators, pure defectors, or cooperator–defector coexistence.
The necessary condition of cooperation evolution is the local colonization of a metapopulation. The spatial correlation between
the cooperators tends to be weaker with the increase in the temptation to defect and the habitat connectivity; yet the spatial
correlation between defectors becomes stronger. The relationship between spatial structure and the colonization rate is complicated,
especially for cooperators. The metapopulation may undergo a temporary period of prosperity just before the extinction, even
while the colonization rate is declining.
An erratum to this article can be found at 相似文献
65.
Uncertainty in allometric exponent estimation: a case study in scaling metabolic rate with body mass
Many factors could influence the allometric scaling exponent β estimation, but have not been explored systematically. We investigated the influences of three factors on the estimate of β based on a data set of 626 species of basal metabolic rate and mass in mammals. The influence of sampling error was tested by re-sampling with different sample sizes using a Monte Carlo method. Small random errors were introduced to measured data to examine their influence on parameter estimations. The influence of analysis method was also evaluated by applying nonlinear and linear regressions to the original data. Results showed that a relative large sample size was required to lower statistical inference errors. When sample size n was 10% of the base population size (n=63), 35% of the samples supported β=2/3, 39% supported β=3/4, and 15% rejected β=0.711, even though the base population had a β=0.711. The controversy surrounding the estimation of β in the literature could be partially attributable to such small sample sizes in many studies. Measurement errors in body mass and base metabolic rate, especially in body mass, could largely increase alpha and beta errors. Analysis methods also affected parameter estimations. Nonlinear regressions provided better estimates of the scaling exponent that were significantly higher than these commonly estimated by linear regressions. This study demonstrated the importance of the quantity and quality of data as well as analysis method in power law analysis, raising caution in interpreting power law results. Meta-data synthesis using data from independent studies seems to be a proper approach in the future, but caution should be taken to make sure that such measurements are made using similar protocols. 相似文献
66.
67.
Isolation of Laribacter hongkongensis, a novel bacterium associated with gastroenteritis, from drinking water reservoirs in Hong Kong 总被引:1,自引:0,他引:1
Lau SK Woo PC Fan RY Ma SS Hui WT Au SY Chan LL Chan JY Lau AT Leung KY Pun TC She HH Wong CY Wong LL Yuen KY 《Journal of applied microbiology》2007,103(3):507-515
AIMS: Freshwater fish has been found to be the reservoir of Laribacter hongkongensis, a recently discovered bacterium associated with community-acquired gastroenteritis. However, little is known about the ecology of this bacterium in the aquatic environment. We carried out a surveillance study to investigate the presence of L. hongkongensis in water and freshwater fish from 10 drinking water reservoirs in Hong Kong. METHODS AND RESULTS: Using membrane filtration, L. hongkongensis was isolated from the waters of six reservoirs, with numbers ranging from 1 to 12 CFU l(-1). Higher recovery rates were observed in summer and during days of higher water and ambient temperatures. Of 27 freshwater fish collected from the reservoirs, L. hongkongensis was recovered from the intestines of two fish, a Goldfish and a Nile tilapia. Overall, 35 different pulsed-field gel electrophoresis patterns are found among the 59 isolates recovered from water and the two isolates from freshwater fish. CONCLUSIONS: The present report represents the first to demonstrate the presence of L. hongkongensis in natural water environments. SIGNIFICANCE AND IMPACT OF THE STUDY: Although it is unlikely that treated, drinking water is an important source of L. hongkongensis-associated gastroenteritis, one should be aware of the possibility of other contaminated water as a source of human infection. 相似文献
68.
DEAR EDITOR:Centenarians are a typical longevity model characterized by delayed onset of morbidity in age-related diseases such as cancer,cardiovascular disease,dementia,and stroke(Andersen et al,2012).Though there may be a number of underlying mechanisms behind this longevity,curiously it seems that the survival advantage persists in their offspring(Terry et al,2003),suggesting a potentially important role for genetic factors.Previous studies suggested that the heritability of human longevity may be~25%(Herskind et al,1996;Mcgue et al,1993),whicih is consistent with other studies on model 相似文献
69.
玉米初生根向水性诱导优化试验研究 总被引:2,自引:0,他引:2
为了研究湿度梯度对根系向水性反应的影响,采用Takahashi and Scott于1993年创建的方法,设置以下3个试验:1)向水性诱导物不同倾斜角试验;2)根系距向水性诱导物不同距离试验;3)根尖距底部饱和K2CO3溶液不同距离试验。同时,还研究了根长和根系延伸速率对根系向水性弯曲的影响。结果表明,用饱和K2CO3溶液控制湿度时根系的向水性弯曲度明显大于纯水。随着诱导物倾斜角的增大,向水性弯曲增强。与距诱导物3 mm和6 mm相比,根系直接接触诱导物时表现出最大的向水性反应。与根尖距底部盐溶液6 cm相比,相距4 cm时向水性弯曲度增大,这些与根尖周围的湿度梯度增大有关。当根长为1.0、1.5、2.0、2.5、3.0 cm时,短根比长根表现出更大的向水性反应,这可能与其较慢的延伸速率为根系对湿度梯度的反应提供了更充足的时间有关。为了验证这个假说,用相同长度的根系、通过控制不同温度进行试验,结果表明根系的向水性弯曲随温度升高而降低。可见,玉米初生根的向水性反应受环境和根系发育阶段两方面影响。当根系相距诱导物较近、根系周围的湿度梯度较大时,根系向水性反应更强。而且,具有较小延伸速率根系的向水性反应更大。考虑到干旱条件下根系伸长慢、且土壤中湿度梯度大,因而可以认为干旱条件下根系的向水性生长在玉米吸收水分中有重要作用。同时,对根系向水性诱导方法的优化有助于其生理机制的进一步研究。 相似文献
70.
Staios G Khan WU Chiuccariello L Sellings LH De Sousa K Wang S Lo S Elkader AK 《CMAJ》2011,183(18):2149-2150
The annual "Roll Up the Rim to Win" contest at Tim Hortons restaurants provides customers the opportunity to win prizes. This study investigated win ratios, prize types and patterns of coffee consumption. 相似文献