共查询到20条相似文献，搜索用时 85 毫秒
1.
2.
核糖体是细胞生长所需的蛋白质合成的动力工厂,每一个核糖体的大小为4兆而顿,有18S、5.8S、28S和5S四种RNA及80S等蛋白质组成,细胞中约有50%的RNA是核糖体RNA,这些RNA直接或间接地参与形成数百万的核糖体,因此,核糖体RNA基因的转录调控机制一直是细胞生长和细胞周期调控研究的热点,细胞通过进化已经形成一套完整的配合RNA聚合酶共同完成的核糖体RNA转录调控机制。本文从核糖体RNA基因结构出发,就染色质重塑、组蛋白乙酰化及细胞周期三个方面探讨核糖体RNA转录调控机制。 相似文献
3.
M K Chattopadhyay 《Resonance》2002,7(11):59-63
Cold-adapted organisms are known to accumulate cryoprotective substances inside their cells. Glycine betaine is a bacterial
cryoprotectant. It is believed to act by stabilizing cellular proteins and membranes at low temperature.
M K Chattopadhyay is working as a Scientist at the Centre for Cellular and Molecular Biology, Hyderabad, on cold adaptation
in Antarctic bacteria.
“There is for me powerful evidence that there is something going on behind it all… It seems as though somebody has fine-tuned
nature’s numbers to make the Universe… The impression of design is overwhelming.” 相似文献
4.
5.
Thyagaraju K. Hemavathi B. Vasundhara K. Rao A. D. Devi K. N. 《Journal of Zhejiang University. Science. B》2005,6(8):759-769
A comparative study was made on the tissue specific expression of glutathione transferases (GST) in brain and testis after
exposure of rat to phenobarbitol (PB) and β-methylcholanthrene (MC). Glutathione transferases, a family of multifunctional
proteins are involved in intracellular transport processes and in detoxication of electrophilic xenobiotics by catalyzing
reactions such as conjugation, isomerization, reduction and thiolysis. On purification, the yield of GST proteins by affinity
chromatography was 39% in testis and 32% in brain. The affinity purified testis GSTs were resolved by chromatofocusing into
six anionic and four cationic isozymes, and in brain glutathione transferases were resolved into four anionic and three cationic
isozymes, suggesting the presence of multiple isozymes with Yc, Yb, Yβ and Yδ in both of them. In testis and brain, these
isozymes at identical pI values showed variable functions with a battery of substrates and the cationic isozymes of brain
and testis showed identical properties in CHP (cumene hydroperoxide) at pH values of above 7.0. Substrate specificity studies
and immunoblot analysis of testis and brain proteins revealed that they play a predominant role in the detoxication of phenobarbitol
or β-methylcholanthrene. Expression of the isozymes in testis and brain on exposure to PB and MC indicated elevated subunit
variation. In both testis and brain, Yδ of π class was expressed on PB treatment and Yc of α class and Yβ of μ class was expressed
in MC treated testis and only Yc was predominantly expressed in MC treated brain. Thus these subunits expression is considered
as markers for carcinogenesis and specific to chemical toxicity under phenobarbitol and β-methylcholanthrene stress.
Project supported by Department of Science and Technology and Council for Scientific and Industrial Research, New Delhi 相似文献
6.
DNA-damage response network at the crossroads of cell-cycle checkpoints,cellular senescence and apoptosis 总被引：2，自引：0，他引：2
Schmitt E Paquet C Beauchemin M Bertrand R 《Journal of Zhejiang University. Science. B》2007,8(6):377-397
Tissue homeostasis requires a carefully-orchestrated balance between cell proliferation, cellular senescence and cell death. Cells proliferate through a cell cycle that is tightly regulated by cyclin-dependent kinase activities. Cellular senescence is a safeguard program limiting the proliferative competence of cells in living organisms. Apoptosis eliminates unwanted cells by the coordinated activity of gene products that regulate and effect cell death. The intimate link between the cell cycle, cellular senescence, apoptosis regulation, cancer development and tumor responses to cancer treatment has become eminently apparent. Extensive research on tumor suppressor genes, oncogenes, the cell cycle and apoptosis regulatory genes has revealed how the DNA damage-sensing and -signaling pathways, referred to as the DNA-damage response network, are tied to cell proliferation, cell-cycle arrest, cellular senescence and apoptosis. DNA-damage responses are complex, involving ＂sensor＂ proteins that sense the damage, and transmit signals to ＂transducer＂ proteins, which, in turn, convey the signals to numerous ＂effector＂ proteins implicated in specific cellular pathways, including DNA repair mechanisms, cell-cycle checkpoints, cellular senescence and apoptosis. The Bcl-2 family of proteins stands among ＂the mos＂t crucial regula＂tors of apop＂tosis and performs vi＂tal func＂tions in deciding whether a cell will live or die after cancer chemotherapy and irradiation. In addition, several studies have now revealed that members of the Bcl-2 family also interface with the cell cycle, DNA repair/recombination and cellular senescence, effects that are generally distinct from their function in apoptosis. In this review, we report progress in understanding the molecular networks that regulate cell-cycle checkpoints, cellular senescence and apoptosis after DNA damage, and discuss the influence of some Bcl-2 family members on cell-cycle checkpoint regulation. 相似文献
7.
核糖体是细胞生长所需的蛋白质合成的动力工厂,每一个核糖体的大小为4兆而顿,有18S、5．8S、28S和5S四种RNA及80S等蛋白质组成,细胞中约有50％的RNA是核糖体RNA,这些RNA直接或间接地参与形成数百万的核糖体,因此,核糖体RNA基因的转录调控机制一直是细胞生长和细胞周期调控研究的热点,细胞通过进化已经形成一套完整的配合RNA聚合酶共同完成的核糖体RNA转录调控机制。本文从核糖体RNA基因结构出发,就染色质重塑、组蛋白乙酰化及细胞周期三个方面探讨核糖体RNA转录调控机制。 相似文献
8.
Michel Morange 《Resonance》2009,14(3):236-247
The Central Dogma of molecular biology was enunciated more than 50 years ago by Francis Crick to define the relations between
the main informational macromolecules: DNA, RNA and proteins. Since that time, many disciplines have mimicked biology, and
introduced their own ‘Central Dogma’. This article is an attempt to review the status of the Central Dogma in the context
of the new discoveries that were made during the past fifty years. 相似文献
9.
Muhammad Abubakkar Azmat Iqrar Ahmad Khan Hafiza Masooma Naseer Cheema Ishtiaq Ahmad Rajwana Ahmad Sattar Khan Asif Ali Khan 《Journal of Zhejiang University. Science. B》2012,13(4):239-243
Good quality deoxyribonucleic acid (DNA) is the pre-requisite for its downstream applications. The presence of high concentrations of polysaccharides, polyphenols, proteins, and other secondary me- tabolites in mango leaves poses problem in getting good quality DNA fit for polymerase chain reaction (PCR) applications. The problem is exacerbated when DNA is extracted from mature mango leaves. A reliable and modified protocol based on the cetyl- trimethylammonium bromide (CTAB) method for DNA extraction from mature mango leaves is described here. High concentrations of inert salt were used to remove polysaccharides; Polyvinylpyrrolidone (PVP) and β-mercaptoethanol were employed to manage phenolic compounds. Extended chloroform-isoamyl alcohol treatment followed by RNase treatment yielded 950?1050 μg of good quality DNA, free of protein and RNA. The problems of DNA degradation,contamination, and low yield due to irreversible binding of phenolic compounds and coprecipitation of polysaccharides with DNA were avoided by this method. The DNA isolated by the modified method showed good PCR amplification using simple se- quence repeat (SSR) primers. This modified protocol can also be used to extract DNA from other woody plants having similar problems. 相似文献
10.
Alzheimer’s disease is one of the most common neurodegenerative disorders amongst the elderly, leading to dementia. Current
studies of its molecular basis reveal various factors culminating in the cytotoxic cascade associated with the disease. Progress
in understanding these events has led to the identification of novel therapeutic targets. This article is an attempt to understand
the global scientific efforts in deciphering the mystery of this disease for a possible cure.
All are postgraduate students at School of Biotechnology, Madurai Kamaraj University, Madurai.
Sovan Sarkar’s research interests are gene therapy, apoptosis in cancer treatment and therapeutic approaches for neurodegenerative
disorders.
Anupam Choudhury is interested in the study of cytoskeleton and motor proteins, specifically kinesins.
T N Avinash is deeply interested in neuroscience, especially in learning and memory. 相似文献
11.
G. Nagendrappa 《Resonance》2011,16(7):606-618
Emil Fischer, considered as one of the greatest chemists of all times, carried out much of the fundamental work on purines,
sugars, proteins, stereochemistry and several other areas of chemistry during the late nineteenth and early twentieth century.
Because most of these are biological molecules, he is known as the ‘Father of Biochemistry’. His achievements in chemical
synthesis and analytical skills were much ahead of his times. He was the second to get the Nobel Prize in Chemistry in 1902. 相似文献
12.
Ravit Golan Duncan Hava Bresler Freidenreich Clark A. Chinn Andrew Bausch 《Research in Science Education》2011,41(2):147-167
Genetics is the cornerstone of modern biology and understanding genetics is a critical aspect of scientific literacy. Research
has shown, however, that many high school graduates lack fundamental understandings in genetics necessary to make informed
decisions or to participate in public debates over emerging technologies in molecular genetics. Currently, much of genetics
instruction occurs at the high school level. However, recent policy reports suggest that we may need to begin introducing
aspects of core concepts in earlier grades and to successively develop students’ understandings of these concepts in subsequent
grades. Given the paucity of research about genetics learning at the middle school level, we know very little about what students
in earlier grades are capable of reasoning about in this domain. In this paper, we discuss a research study aimed at fostering
deeper understandings of molecular genetics at the middle school level. As part of the research we designed a two-week model-based
inquiry unit implemented in two 7th grade classrooms (N = 135). We describe our instructional design and report results based on analysis of pre/post assessments and written artifacts
of the unit. Our findings suggest that middle school students can develop: (a) a view of genes as productive instructions
for proteins, (b) an understanding of the role of proteins in mediating genetic effects, and (c) can use this knowledge to
reason about a novel genetic phenomena. However, there were significant differences in the learning gains in both classrooms
and we provide speculative explanations of what may have caused these differences. 相似文献
13.
利用电镜细胞化学方法对食蟹猴疟原虫红内期酸性磷酸酶进行定位研究．结果发现．酸性磷酸酶广泛定位于疟原虫的食物泡、内质网、核糖体和疟色素上；而一些内含物与红细胞相似的双层膜结构内无ACP活性，不属于食物泡，而是宿主细胞的伪足伸入虫体；并认为ACP是由核糖体转运至食物泡内的；外周胞饮作用和胞口援食可能都是疟原虫红内期的营养方式．而外周胞饮作用可以起主要作用． 相似文献
14.
Insulin is a major protein hormone secreted by the β-cells of the pancreas and is important for the control of diabetes. Insulin
is usually administered to diabetic patients through subcutaneous injection. This mode of therapy has certain inherent disadvantages
such as local pain, itching and insulin lipodystrophy around the injection site. Hence, pharmaceutical scientists have been
trying to design an oral delivery system for insulin. Many challenges are associated with the oral delivery of insulin, relating
to the physical and chemical stability of the hormone, and its absorption and metabolism in the human body. Here we discuss
various strategies for the oral delivery of insulin that are being tried out, as well as methods used to improve the absorption
of orally consumed insulin and to reduce its degradation by digestive enzymes.
K Gowthamarajan is on the faculty of the Department of Pharmaceutics in JSS College of Pharmacy, Ootacamund. His research
interests are in the area of designing drug delivery systems for peptides and proteins. He is currently involved in research
on pharmaceutical applications of plant polysaccharides.
Giriraj T Kulkarni is on the faculty of the Department of Pharmaceutics in JSS College of Pharmacy, Ootacamund. Currently,
he is involved in research on pharmaceutical and biotechnological applications of plant polysaccharides. He has authored a
book ‘Biotechnology and its Applications in Pharmacy’ for undergraduate and postgraduate students of pharmacy. 相似文献
15.
泥鳅早期胚胎发育的超微结构变化。卵裂期,有些线粒体内含有片层状类脂物,有些含有糖原颗粒,有些线粒体呈同心圆状。在胚胞中也有片层状类脂物,其中有些片层体内含有黑色颗粒,类似于次级溶酶体。在胚胞中,外包一层单位膜的卵黄颗粒起始含无定形的卵黄物质,然后卵黄中间出现空泡,不久卵黄颗粒中出现线粒体,膜性物质,核糖体样颗粒,糖原颗粒和小的卵黄颗粒。我们认为卵黄除了向胚胎细胞提供营养物质之外,还向胚胎细胞提供母体的膜性物质和核糖体等。 相似文献
16.
This article is to summarize the molecular and functional analysis of the gene “suppression of tumorigenicity 13” (ST13). ST13 is in fact the gene encoding Hsp70 interacting protein (Hip), a co-factor (co-chaperone) of the 70-kDa heat shock proteins (Hsc/Hsp70). By collaborating with other positive co-factors such as Hsp40 and the Hsp70-Hsp90 organizing protein (Hop), or competing with negative co-factors such as Bcl2-associated athanogen 1 (Bag1), Hip facilitates may facilitate the chaperone function of Hsc/Hsp70 in protein folding and repair, and in controlling the activity of regulatory proteins such as steroid receptors and regulators of proliferation or apoptosis. Although the nomenclature of ST13 implies a role in the suppression of tumorigenicity (ST), to date available experimental data are not sufficient to support its role in cancer development, except for the possible down-regulation of ST13 in gastric and colorectal cancers. Further investigation of this gene at the physiological level would benefit our understanding of diseases such as endocrinological disorders, cancer, and neurodegeneration commonly associated with protein misfolding. 相似文献
17.
Huang He-feng Xia Ya-xian Shi Yi-fu Zhou Fu-zhen Yeung Shu-biao Ho Pak-chung 《浙江大学学报(A卷英文版)》2000,1(3):342-346
The present study was undertaken to evaluate the endometrial secretion and synthesis of proteins in hamsters that were subjected
to ovarian stimulation with or without GnRH agonist (Leuprolide Acetate, LA). The results of protein resolution revealed that
the molecular weight of the proteins increased from 31D to 66D, while the intensities of photographed protein bands in the
hamsters treated with LA and pregnant mare’ s serum gonadotropin (PMSG) were less than that in those treated with PMSG alone.
The amounts of low and medium weights (31kD and 45kD) proteins newly synthesized in LA+PMSG group and saline group (control)
were significantly higher than that in PMSG group. The synthesized and secreted proteins in groups LA and control were similar.
The data suggested that a physiologic endometrial protein secretory and synthetic change with GnRH agonist regarcded as a
possible cause of the higher pregnancy rate in in vitro fertilization. The degree of endometrial secretion and synthesis varied
considerably with the type of ovarian stimulation used.
Project supported by China Medical Board of New York Inc., USA 相似文献
18.
19.
Anand K. Bachhawat 《Resonance》2006,11(8):22-40
An important hallmark of biological research is the aspect of ‘comparisons’. As the complete genome sequences of numerous
organisms have become available, the emphasis in biology has shifted to comparisons at the genome level. Indeed, the last
few years have witnessed an exponential rise in the number of organisms whose complete genome has been sequenced, and we are
still climbing up the graph. The present article, a primer, explains how one can extract a great deal of information from
such analyses that is of great value in our research. The subject of comparative genomics impinges on evolutionary biology
and phylogenetic reconstructions of the tree of life, drug discovery programs, function predictions of hypothetical proteins
and genes, regulatory motifs and other non-coding DNA motifs, and genome flux and dynamics. Finally the article describes
how the information one can extract from a comparative analysis of genomes depends to a large extent, on the specific aspect
of the genomes that is being compared and the phylogenetic distances of the organisms involved. 相似文献
20.
INTRODUCTION Telomeres are distinctive DNA-protein struc-tures that cap the ends of linear chromosomes.It is very important to keep the chromosomes stabilization.Telomerase activity is closely linked to attainment of cellular immortality,a step in carcinogenesis,while lack of such activity contributes to cellular senes-cence.Telomerase is activated in more than85%ofmalignant tumors(Hiayma et al.,1997).Human te-lomeric repeat binding factor1(TRF1)is a telomere associated with proteins a… 相似文献