A new acute transforming feline retrovirus and relationship of its oncogene v-kit with the protein kinase gene family

A new acute transforming feline retrovirus, the Hardy-Zuckerman 4 feline sarcoma virus (HZ4-FeSV), has been isolated from a feline fibrosarcoma. The viral genome of HZ4-FeSV contains a new oncogene designated v-kit, has the structure 5' delta gag-kit-delta pol-delta env 3' and specifies a gag-kit polyprotein of relative molecular mass 80,000. The predicted kit amino-acid sequence displays partial homology with tyrosine-specific protein kinase oncogenes. HZ4-FeSV appears to have been generated by transduction of feline c-kit sequences with feline leukaemia virus.     

一个水稻蛋白激酶的过表达分析及表达调控

对一个预测的具有光反应活性的丝氨酸/苏氨酸蛋白激酶STK进行过表达研究,构建了STK过表达载体,并用农杆菌介导的方法进行遗传转化,获得T0代转基因植株.对转基因阳性植株进行表达分析的结果表明,转基因植株STK基因的表达量显著高于对照,说明目的基因得到了过表达.另外,利用获得的过表达转基因植株对STK调控水稻中光周期相关的开花基因Hd1和Hd3a的表达进行分析,结果表明,Hd1及Hd3a的表达在转基因植株中明显上调,表明该蛋白激酶的基因可能位于Hd1和Hd3a上游,对于Hd1和Hd3a的表达具有重要的调控作用.     

Insulin gene enhancer binding protein Isl-1 is a member of a novel class of proteins containing both a homeo- and a Cys-His domain.

The activity of the rat insulin I gene enhancer is mainly dependent on two cis-acting protein-binding domains. Here we report the isolation of a complementary DNA encoding a protein, Isl-1, that binds to one of these domains. Isl-1 contains a homeodomain with greatest similarity to those of the Caenorhabditis elegans proteins encoded by mec-3 and lin-11. In addition, Isl-1, like the lin-11 and mec-3 gene products, contains a novel Cys-His domain which is reminiscent of known metal-binding regions. Together these proteins define a novel class of proteins containing both a homeo- and a Cys His-domain. Isl-1 is preferentially expressed in cells of pancreatic endocrine origin. If the structural homologies between Isl-1 and the C. elegans gene products reflect functional similarities, a role for Isl-1 in the development of pancreatic endocrine cells could be envisaged.     

A new A4 amyloid mRNA contains a domain homologous to serine proteinase inhibitors

The amyloid proteins isolated from neuritic plaques and the cerebrovasculature of Alzheimer's disease are self-aggregating moieties termed A4 protein and beta-protein, respectively. A putative A4 amyloid precursor (herein termed A4(695] has been characterized by analysis of a human brain complementary DNA. We report here the sequence of a closely related amyloid cDNA, A4(751), distinguished from A4(695) by the presence of a 168 base-pair (bp) sequence which adds 57 amino acids to, and removes one residue from, the predicted A4(695) protein. The peptide predicted from this insert is very similar to the Kunitz family of serine proteinase inhibitors. The two A4-specific messenger RNAs are differentially expressed: in a limited survey, A4(751) mRNA appears to be ubiquitous, whereas A4(695) mRNA has a restricted pattern of expression which includes cells from neuronal tissue. These data may have significant implications for understanding amyloid deposition in Alzheimer's disease.     

Cloning and expression of catalytic domain of Abl protein tyrosine kinase gene in E. coli

Protein tyrosine kinases (PTKs) regulate cell proliferation, differentiation and are involved in signal transduction. Uncontrolled signaling from receptor tyrosine kinases to intracellular tyrosine kinases can lead to inflammatory responses and diseases such as cancer and atherosclerosis. Thus, inhibitors that block the activity of tyrosine kinases or the signaling pathways of PTKs activation could be assumed as the potential candidate for drug development. On this assumption, we cloned and expressed the Abl PTK gene in E. coli, and purified the PTK, which was used to screen the PTK inhibitors from the extracts of Chinese herbs. The catalytic domain sequence of PTK gene was amplified by PCR using the cDNA of abl from Abelson murine leukemia virus as template. The amplified fragment was then cloned into the GST-tagged expression vector pGEX2T. The recombinant plasmid was transformed into host cell E. coli DH5α and was induced to express PTK protein. The expression of the protein was detected using SDS-PAGE. The result showed that a specific protein was induced to express after 12 min induction, and reached peak level about 40% of the host total protein after 4 h induction. The molecular weight of the fusion protein was about 58 kD. The purified GST-PTK fusion protein presented higher activity for tyrosine phosphorylation.     

一个水稻富亮氨酸重复类受体蛋白激酶的RNAi及表达分析

为了揭示富亮氨酸重复类受体蛋白激酶(LRR-RLKs)家族成员OsLPR1在水稻生长发育与抗逆性中的功能,利用反向遗传学方法构建了OsLPR1的RNAi载体,将其导入野生型水稻中获得转基因植株,观察表型并且分析OsLPR1基因在野生型和转基因植株中的表达情况.在表型观察中发现RNAi转基因植株出现白化苗.进一步的RT-PCR分析发现,白化苗中目的基因OsLPR1的表达量明显偏低,野生型中的表达量则较高,这表明OsLPR1基因表达异常会导致水稻出现白化现象.另外,还分析了OsLPR1的组织特异性表达,结果表明,OsLPR1在不同的组织器官中均有表达,但在叶片及叶鞘中高表达,这说明该基因可能与水稻叶片的生长发育有关.     

Analysis of a human DNA excision repair gene involved in group A xeroderma pigmentosum and containing a zinc-finger domain

Xeroderma pigmentosum (XP) is an autosomal recessive disease, characterized by a high incidence of sunlight-induced skin cancer. Cells from people with this condition are hypersensitive to ultraviolet because of a defect in DNA repair. There are nine genetic complementation groups of XP, groups A-H and a variant. We have cloned the mouse DNA repair gene that complements the defect of group A, the XPAC gene. Here we report molecular cloning of human and mouse XPAC complementary DNAs. Expression of XPAC cDNA confers ultraviolet-resistance on several group A cell lines, but not on lines of other XP groups. Almost all group A lines tested showed abnormality or absence of XPAC messenger RNAs. These results indicate that a defective XPAC gene causes group A XP. The human and mouse XPAC genes are located on chromosome 9q34.1 and chromosome 4C2, respectively. Human XPAC cDNA encodes a protein of 273 amino acids with a zinc-finger motif.     

Southern rice black-streaked dwarf virus:A new proposed Fijivirus species in the family Reoviridae

For the past several years, a novel dwarf disease has been observed on rice (Oryza sativa) in some regions of Guangdong Province and Hainan Province, southern China. Infected plants showed stunting, dark leaf and small enations on stem and leaf back. Typical Fijivirus viroplasma containing crystalline arrayed spherical virons approximately 70―75 nm in diameter and tubular structures were detected in ultrathin sections by an electron microscope in parenchyma phloem cells of the infected plants. The virus was transmitted to rice seedlings by white-backed planthoppers, Sogatella furcifera (Hemiptera: Delphacidae), collected in the diseased fields. Analysis of dsRNA extracts from infected plants revealed ten linear segments, which were similar to the electrophoretic profile of Rice black-streaked dwarf virus (RBSDV). RT-PCR with a single primer which matched to a linker sequence ligated to both 3′ ends of the viral genomic dsRNAs resulted in amplification of genome segments 9 (S9) and 10 (S10) cDNA products. The complete nucleotide sequences of S9 and S10 were obtained from clones of the RT-PCR amplicon exhibited characteristic properties of Fijivirus including low GC content (34.5% and 35.6%), genus conserved 5′ and 3′ termini sequences and similar genome organization. Blast searches indicated that the sequences of S9 and S10 shared 68.8%―74.9% and 67.1%―77.4% nucleotide identities with those of viruses in the Fijivirus group 2, respectively. These values were similar to those among other viruses in the Fijivirus group 2 and considerably lower than those among RBSDV isolates. Phylogenetic trees based on S9 and S10 nucleotide sequences and their putative amino acid sequences showed that this virus represented a separate branch among other Fijiviruses. The virus was also detected by a nested RT-PCR assay in corn (Zea mays), barnyard grass (Echinochloa crusgalli), Juncellus serotinus and flaccidgrass (Pennisetum flaccidum) in and/or adjacent to the infected rice fields. It is proposed that this virus be considered as a new species, Southern rice black-streaked dwarf virus, in the group 2 of the genus Fijivirus in the family Reoviridae.     

Clustered spikelets 4, encoding a putative cytochrome P450 protein CYP724B1, is essential for rice panicle development

Rice （Oryza sativa L.） inflorescence （panicle） architecture is an important agronomic trait, serving as one of the determinants of rice yield. A number of genes related to panicle development have been cloned and functionally characterized so far. However, more information is needed for fully understanding of the mechanism underlying the panicle development. In the present study, we identified a clustered spikelets 4 （cl4） mutant in the 93-11 genetic background. Compared to its wild-type 93-11, cl4 mutant has a typical clustered spikelets phenotype with all primary branches clustered on the base of the main rachis and 2-3 abnormal spikelets clustered on the primary branches. Moreover, cl4 mutant also shows shorter plant height than that of the wild type. Map-based cloning strategy is per- formed to clone the CL4 gene. As a result, CL4 is demonstrated to encode a putative cytochrome P450 protein CYP724B1, which is involved in brassinosteroid biosynthesis. To confirm our mapping result, the CL4 RNAi transgenic plants are generated. And the transgenic plants also show similar phenotype as the cl4 mutant. These results provide strong evidence that CL4 plays an important role in rice panicle development as well as plant height regulation.     

Relationships between D1 protein, xanthophyll cycle and photodamage-resistant capacity in rice (Orysa sativa L.)

Relationships between D1 protein, xanthophyll cycle and subspecific difference of photodamage-resistant capacity have been studied in O. japonica rice varieties 02428 and 029 (photoinhibition-tolerance) and O. indica rice varieties 3037 and Palghar (photoinhibition-sensitivity) and their reciprocal cross F1 hybrids after photoinhibitory treatment. It was shown that PSⅡ photochemical efficiency (Fv /Fm) decreased, and xanthophyll cycle from violaxanthin (V), via anaxanthin (A), to zeaxanthin (Z) was enhanced and non-photochemical quenching (qN) increased accordingly in SM-pretreated leaves of rice when the synthesis of D1 protein was inhibited, and that there was a decrease in qN and, as a result, more loss of D1 protein and a big decrease in Fv /Fm in DTT-pretreated leaves when xanthophyll cycle was inhibited. O. japonica subspecies had a higher maintaining capacity of D1 protein and a decrease of Fv /Fm in a more narrow range, and exhibited more resistance against photodamage, as compared with O. indica subspecies. The above physiological indexes in reciprocal cross F1 hybrids, though between the values of their parents, were closer to maternal lines than to paternal lines. Experimental results support the concept that the turnover capacity for D1 protein is an important physiological basis of photoinhibition-tolerance, and will provide the physiological basis for selection of the photoinhibition-tolerant parents and develop a new approach to breed hybrids with high photosynthetic efficiency.     

Banach空间中有限族渐近非扩张映象的新隐迭代程序

本文在Banach空间中引入了一种新的隐迭代程序并研究了其强收敛于有限族渐近非扩张映象的公共不动点问题,从而推广了最新的相关结果。     

A potential fusion peptide and an integrin ligand domain in a protein active in sperm-egg fusion.

The union of sperm and egg is a special membrane fusion event that gives a signal to begin development. We have hypothesized that proteins mediating cell-cell fusion events resemble viral fusion proteins and have shown that PH-30, a sperm surface protein involved in sperm-egg fusion, shares biochemical characteristics with viral fusion proteins. We report here the complementary DNA and deduced amino-acid sequences of the mature alpha and beta subunits of PH-30. Both are type-I integral membrane glycoproteins. The alpha subunit contains a putative fusion peptide typical of viral fusion proteins and the beta subunit contains a domain related to a family of soluble integrin ligands found in snake venoms. Thus, the PH-30 alpha/beta complex resembles many viral fusion proteins in both its membrane topology and its predicted binding and fusion functions.