水稻中介体亚基OsMed6的表达及进化分析

中介体复合物是真核生物RNA聚合酶Ⅱ(PolⅡ)通用转录装置的重要组成部分,是基因特异性转录因子与启动子信息传递的桥梁.本研究对水稻(Oryza sativa)中一个假定的中介体亚基OsMed6的表达和进化进行了分析.通过整合分析不同来源的基因芯片数据,发现OsMed6在各个组织(器官)里都有表达.构建了OsMed6与...     

Identification of a gene located at chromosome 5q21 that is mutated in colorectal cancers.

Recent studies have suggested the existence of a tumor suppressor gene located at chromosome region 5q21. DNA probes from this region were used to study a panel of sporadic colorectal carcinomas. One of these probes, cosmid 5.71, detected a somatically rearranged restriction fragment in the DNA from a single tumor. Further analysis of the 5.71 cosmid revealed two regions that were highly conserved in rodent DNA. These sequences were used to identify a gene, MCC (mutated in colorectal cancer), which encodes an 829-amino acid protein with a short region of similarity to the G protein-coupled m3 muscarinic acetylcholine receptor. The rearrangement in the tumor disrupted the coding region of the MCC gene. Moreover, two colorectal tumors were found with somatically acquired point mutations in MCC that resulted in amino acid substitutions. MCC is thus a candidate for the putative colorectal tumor suppressor gene located at 5q21. Further studies will be required to determine whether the gene is mutated in other sporadic tumors or in the germ line of patients with an inherited predisposition to colonic tumorigenesis.     

HSPC117 is the essential subunit of a human tRNA splicing ligase complex

Splicing of mammalian precursor transfer RNA (tRNA) molecules involves two enzymatic steps. First, intron removal by the tRNA splicing endonuclease generates separate 5' and 3' exons. In animals, the second step predominantly entails direct exon ligation by an elusive RNA ligase. Using activity-guided purification of tRNA ligase from HeLa cell extracts, we identified HSPC117, a member of the UPF0027 (RtcB) family, as the essential subunit of a tRNA ligase complex. RNA interference-mediated depletion of HSPC117 inhibited maturation of intron-containing pre-tRNA both in vitro and in living cells. The high sequence conservation of HSPC117/RtcB proteins is suggestive of RNA ligase roles of this protein family in various organisms.     

高分子量麦谷蛋白亚基基因Dx5的PCR检测

为 Dx5基因设计了 1对特异引物 ,选用 HMW- GS在 Glu Dx1位点已知的 2 2个材料对其进行了验证。结果表明 ,该引物的准确率达到 10 0 %,完全可以作为 Dx5基因的检测引物。利用这 1对引物 ,通过 PCR技术对 4 0种材料的 Dx5基因进行了检测 ,发现仅有 986 0 5 ,陕 2 5 3,郑州 891,97- 2 14 3,绵阳 96 171- 10 ,绵阳 19,中 1813- 1和绵阳 11等 8个品种 (系 )携带 Dx5基因 ,占待测材料总数的 2 0 .0 %,远远低于北美小麦品种中 Dx5基因的携带率。研究中还发现 ,对检测优质面包烘烤品质基因而言 ,PCR方法是最简便、快速、准确的方法之一。     

龙眼体细胞胚胎的高频率萌发与植株再生

以龙眼胚性愈伤组织诱导产生子叶形胚状体为试验材料，比较了蔗糖、活性炭的质量浓度，椰乳的体积分数，光照度和成熟时间等因素对体胚“成熟”的影响以及不同成熟过程、成熟时间、胚状体形态、品种（基因型）等因素对龙眼体细胞胚胎萌发的影响．结果表明，龙眼体胚在含５０ｇＬ－１蔗糖、体积分数为０．０５的椰乳、１００ｍｇＬ－１肌醇的ＭＳ固体培养基上，在黑暗或弱光条件下，不论白色还是透明化（玻璃化）子叶形小胚状体，都可完成“成熟”过程．体胚对成熟培养的蔗糖质量浓度和成熟时间有特定的要求．经过成熟培养的体细胞胚胎，可高频率萌发成苗     

小偃6号HMW-GS表达动态研究

以小偃 6号为试验材料 ,在其开花至成熟期 ,每隔 2～ 4d采收 1次籽粒 ,提取籽粒中的麦谷蛋白 ,通过十二烷基硫酸钠 -聚丙烯酰胺凝胶电泳 (SDS- PAGE)对高分子质量的麦谷蛋白亚基 (HMW- GS)进行分离。结果表明 :高分子质量麦谷蛋白在籽粒成熟过程中 ,各个亚基大约在花后 12 d开始表达 ,但不同亚基开始表达时期稍有差异 ;在花后 16 d之前 ,各个亚基蛋白的绝对量增长缓慢 ;花后 16 d之后 ,各个亚基蛋白绝对量迅速增加至一稳定值 ,且花后 2 0 d之后各个亚基蛋白的相对含量基本保持不变。     

小麦优质亚基和抗白粉病基因聚合体的标记辅助选择研究

本研究采用SDS-PAGE半粒电泳法和SCAR分子标记技术,分别对小麦抗病优质杂交组合(GN2003×龙96-6239)F2所含的优质亚基和抗白粉病基因进行了标记辅助选择.结果表明,在50个F2单株的Glu-D1位点上,有21株含5+10优质亚基,另有1株含有5+12优质亚基;运用与抗白粉病基因相连锁的SCAR140标记初步筛选出具有抗白粉病基因标记的38株,并经田间白粉病抗性鉴定,50个F2单株中有37株表现抗病,其余13株表现感病,仅有1株的田间抗白粉病表现与SCAR标记检测结果不相符.鉴定出同时具有抗白粉病基因标记和5+10优质亚基的聚合体14株,以及1株具有抗白粉病基因标记和5+12亚基,以供小麦优质抗病育种利用.本研究表明采用SDS-PAGE半粒电泳法与SCAR分子标记技术结合可对育种早代的优异单株进行有效鉴定和选择.     

高世代转PSAG12-IPT基因水稻生育后期的延衰性

以转PASG12-IPT基因水稻东南201自交高世代（T8）株系为材料,对始穗期和蜡熟期剑叶的衰老相关指标测定表明,蜡熟期高世代转PSAG12-IPT基因水稻株系的细胞分裂素含量、叶绿素含量、净光合速率值、CAT活性、SOD活性均显著高于受体品种,部分株系达到极显著水平,而转化株系的MDA含量则明显低于受体品种,POD活性呈无规律变化.由上可见,抑制衰老嵌合基因PSAG12-IPT对水稻叶片的衰老有一定的延缓效应,并能在高世代中稳定表达.     

小麦优质亚基和抗白粉病Pm4a基因聚合体的PCR鉴定

为选育优质、高产、抗病的小麦品系（种）,以含1Dx5+1Dy10亚基的宁春4号和含Pm4a抗白粉病基因的扬麦19为亲本,从其杂交F2后代 1/3～1/2粒种子提取DNA,并利用1Dx5亚基和Pm4a基因的特异标记对其进行PCR鉴定。结果表明：在100粒F2代种子中,有51粒种子被鉴定为1Dx5亚基和Pm4a基因聚合体。该试验采用的PCR鉴定,克服了SDS PAGE电泳耗时多、容易对迁移率相近亚基做出误判的缺点,同时也摆脱了白粉病大田和温室鉴定时受气候条件和农时的限制,大大提高了鉴定的效率和准确性。对中选的聚合体做进一步鉴定,有望选出农艺性状好、产量高、品质优、抗白粉病的小麦品系。     

High frequency of horizontal gene transfer in the oceans

Oceanic bacteria perform many environmental functions, including biogeochemical cycling of many elements, metabolizing of greenhouse gases, functioning in oceanic food webs (microbial loop), and producing valuable natural products and viruses. We demonstrate that the widespread capability of marine bacteria to participate in horizontal gene transfer (HGT) in coastal and oceanic environments may be the result of gene transfer agents (GTAs), viral-like particles produced by α-Proteobacteria. We documented GTA-mediated gene transfer frequencies a thousand to a hundred million times higher than prior estimates of HGT in the oceans, with as high as 47% of the culturable natural microbial community confirmed as gene recipients. These findings suggest a plausible mechanism by which marine bacteria acquire novel traits, thus ensuring resilience in the face of environmental change.     

Mutations in SDHD, a mitochondrial complex II gene, in hereditary paraganglioma

Hereditary paraganglioma (PGL) is characterized by the development of benign, vascularized tumors in the head and neck. The most common tumor site is the carotid body (CB), a chemoreceptive organ that senses oxygen levels in the blood. Analysis of families carrying the PGL1 gene, described here, revealed germ line mutations in the SDHD gene on chromosome 11q23. SDHD encodes a mitochondrial respiratory chain protein-the small subunit of cytochrome b in succinate-ubiquinone oxidoreductase (cybS). In contrast to expectations based on the inheritance pattern of PGL, the SDHD gene showed no evidence of imprinting. These findings indicate that mitochondria play an important role in the pathogenesis of certain tumors and that cybS plays a role in normal CB physiology.     

Life at high temperatures. Evolutionary, ecological, and biochemical significance of organisms living in hot springs is discussed

The time is now ripe for a concerted attack on the evolutionary, ecological, and molecular aspects of life at high temperatures. Hot springs provide nearly ideal ecosystems for such study, since they are natural environments of great antiquity and relative constancy, where organisms have evolved to meet the environmental challenges of high temperatures. Even from our present limited knowledge, we can draw a number of conclusions.     

Receptor-estrogen complex in the nuclear fraction of rat uterine cells during the estrous cycle

A quantitative method was used to determine the concentration of receptor-estrogen complex in the nuclear fraction of rat uterine cells throughout the estrous cycle. The concentrations of nuclear receptor-estrogen complex were: metestrus, 0.22; diestrus, 0.75; proestrus, 1.29; and estrus, 0.31 picomoles per milligram of DNA. This cyclic fluctuation in the nuclear complex closely parallels the secretion of ovarian estrogen during the estrous cycle, an indication that the accumulation of receptor-estrogen complex by the nuclear fraction of uterine cells may be of physiological significance, and under the control of endogenous estrogen.     

高世代转P_(SAG12)-IPT基因水稻生育后期的延衰性

以转PASG12-IPT基因水稻东南201自交高世代(T8)株系为材料,对始穗期和蜡熟期剑叶的衰老相关指标测定表明,蜡熟期高世代转PSAG12-IPT基因水稻株系的细胞分裂素含量、叶绿素含量、净光合速率值、CAT活性、SOD活性均显著高于受体品种,部分株系达到极显著水平,而转化株系的MDA含量则明显低于受体品种,POD活性呈无规律变化.由上可见,抑制衰老嵌合基因PSAG12-IPT对水稻叶片的衰老有一定的延缓效应,并能在高世代中稳定表达.     

The human gene for the beta subunit of nerve growth factor is located on the proximal short arm of chromosome 1

Fragments of the recently cloned human gene for the beta subunit of nerve growth factor (beta-NGF) were used as hybridization probes in analyzing two sets of rodent-human somatic cell hybrids for the presence of human beta-NGF sequences. Results from the first set of hybrids assigned the human beta-NGF gene to chromosome 1 and ruled out the presence of sequences of comparable homology on any other chromosome. With the second set of hybrids, which contained seven different, but overlapping, regions of chromosome 1, the NGF locus was mapped to band 1p22.     

The human gene encoding GM-CSF is at 5q21-q32, the chromosome region deleted in the 5q- anomaly

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a 22,000-dalton glycoprotein that stimulates the growth of myeloid progenitor cells and acts directly on mature neutrophils. A full-length complementary DNA clone encoding human GM-CSF was used as a probe to screen a human genomic library and isolate the gene encoding human GM-CSF. The human GM-CSF gene is approximately 2.5 kilobase pairs in length with at least three intervening sequences. The GM-CSF gene was localized by somatic cell hybrid analysis and in situ hybridization to human chromosome region 5q21-5q32, which is involved in interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. An established, human promyelocytic leukemia cell line, HL60, contains a rearranged, partially deleted GM-CSF allele and a candidate 5q- marker chromosome, indicating that the truncated GM-CSF allele may reside at the rejoining point for the interstitial deletion on the HL60 marker chromosome.     

Location of gene for beta subunit of human T-cell receptor at band 7q35, a region prone to rearrangements in T cells

The T-cell receptor is formed by two chains, alpha and beta, for which specific clones were recently obtained. In this report the gene for the beta chain of the human T-cell receptor was located on the long arm of chromosome 7, band q35, by means of in situ hybridization. This chromosome region in T cells is unusually prone to develop breaks in vivo, perhaps reflecting instability generated by somatic rearrangement of T-cell receptor genes during normal differentiation in this cell lineage.