Thyroid hormone controls carnitine status through modifications of γ-butyrobetaine hydroxylase activity and gene expression

The carnitine system plays a key role in β-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on γ-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased in the hypothyroid state and increased in hyperthyroid animals. The modifications in BBH activity correlated with changes in the enzyme Vmax values. These changes were shown to be related to hepatic BBH mRNA abundance. Thyroid hormones are known to interact with lipid metabolism, in particular by increasing long-chain fatty acid oxidation through activation of carnitine-dependent fatty acid import into mitochondria. Our study showed that thyroid hormones also increased carnitine bioavailability. Received 23 October 2001; received after revision 11 January 2002; accepted 15 January 2002     

Porcine factor V: cDNA cloning, gene mapping, three-dimensional protein modeling of membrane binding sites and comparative anatomy of domains

Factor V is a plasma protein essential for blood coagulation. This protein is involved in activated protein C resistance, the most common inherited thrombotic disorder known. We utilized the polymerase chain reaction to clone the porcine factor V gene by generating overlapping clones amplified with primers chosen by comparison with known nucleotide sequences. The porcine factor V cDNA contig encodes a predicted 2258-amino acid protein, making it the largest in comparison to the bovine, human, and murine proteins. Porcine factor V has the highest level of homology with bovine factor V, but also has high levels of conservation of important residues with all the species. Radiation hybrid mapping assigned the porcine factor V gene to chromosome 4. Three-dimensional models of factor V were generated and used to analyze membrane-binding sites in terms of conserved, and therefore likely important residues. Received 3 October 2000; revised 23 November 2000; accepted 6 December 2000     

Transformation: a tool for studying fungal pathogens of plants

Plant diseases caused by plant pathogenic fungi continuously threaten the sustainability of global crop production. An effective way to study the disease-causing mechanisms of these organisms is to disrupt their genes, in both a targeted and random manner, so as to isolate mutants exhibiting altered virulence. Although a number of techniques have been employed for such an analysis, those based on transformation are by far the most commonly used. In filamentous fungi, the introduction of DNA by transformation typically results in either the heterologous (illegitimate) integration or the homologous integration of the transforming DNA into the target genome. Homologous integration permits a targeted gene disruption by replacing the wild-type allele on the genome with a mutant allele on transforming DNA. This process has been widely used to determine the role of newly isolated fungal genes in pathogenicity. The heterologous integration of transforming DNA causes a random process of gene disruption (insertional mutagenesis) and has led to the isolation of many fungal mutants defective in pathogenicity. A big advantage of insertional mutagenesis over the more traditional chemical or radiation mutagenesis procedures is that the mutated gene is tagged by transforming DNA and can subsequently be cloned using the transforming DNA. The application of various transformation-based techniques for fungal gene manipulation and how they have increased our understanding and appreciation of some of the most serious plant pathogenic fungi are discussed. Received 9 May 2001; received after revision 2 July 2001; accepted 3 July 2001     

Polyamine-dependent gene expression

The polyamines spermidine and spermine along with the diamine putrescine are involved in many cellular processes, including chromatin condensation, maintenance of DNA structure, RNA processing, translation and protein activation. The polyamines influence the formation of compacted chromatin and have a well-established role in DNA aggregation. Polyamines are used in the posttranslational modification of eukaryotic initiation factor 5A, which regulates the transport and processing of specific RNA. The polyamines also participate in a novel RNA-decoding mechanism, a translational frameshift, of at least two known genes, the TY1 transposon and mammalian antizyme. Polyamines are crucial for their own regulation and are involved in feedback mechanisms affecting both polyamine synthesis and catabolism. Recently, it has become apparent that the polyamines are able to influence the action of the protein kinase casein kinase 2. Here we address several roles of polyamines in gene expression.Received 27 November 2002; received after revision 9 January 2003; accepted 31 January 2003     

Construction of ice nucleation active <Emphasis Type="Italic">Enterobacter cloacae</Emphasis> for control of insect pests

Ice nucleation active(INA)bacteria are the most potent heterogeneous ice nuclei in nature,which have become an important biological resource for diverse applications.Many researches have proved that INA bacteria can raise the supercooling points(SCPs)of insect pests,then reduce their cold hardiness.However,INA bacteria‘s inefficient colonization on the surface or in the guts of insects,and the high incidence of frost injury induced by their release hampered the application of INA bacteria in controlling insect pests in agricultural fields.In this study,we constructed a recombinant plasmid mob-Tn5-iceA with the ability of broad-host-range conjugal mobilization and integration of the ina gene of icaA into chromosomal DNA of many gram-negative bacteria by Tn5 transposition.In addition,Ent.cloacae strains stably carrying iceA and expressing high ice nucleation activity(INA),even in the absence of antibiotic pressure,were constructed through conjugal mobilization and Tn5 transposition.Ent,cloacae strains have benn reported to be able to efficently colonize in the guts of insects,but have weak plant epiphytic ability.Therefore,these transgenic Ent.Cloacae may be promising candidates for control of insect pests in agricultural fields.     

中华绒螯蟹卵巢新基因EJO6的全长cDNA克隆和序列分析

利用RACE技术从中华绒螫蟹卵巢获得了新基因EJO6(Eriocheir japonica ovary gene 6,EJO6)的全长cDNA序列(GenBarnk 检索号：AYl85922)。该cDNA序列长度为1250bp,开放阅读框为690bp,编码229个氨基酸。根据氨基酸序列计算的相对分子质量和等电点分别为24270和11．9。同时用生物信息学的方法对该基因的结构和功能进行了初步分析。     

Phylogenetic position of Schnabelia, a genus endemic to China： Evidence from sequences of cpDNA matK gene and nrDNA ITS regions

The chloroplast gene matK and the internal transcribed spacers (ITS) of the nuclear ribosomal DNA from Schnabelia, a genus endemic to China, and 6 genera of Verbenaceae and 13 genera of Lamiaceae were sequenced. The phylogenetic signal and validity outgroups were measured and evaluated by means of the relatively apparent synapomorphy analysis (RASA). Independent and combined phylogenetic analyses for the matK and ITS sequences were performed using the maximum parsimony (MP), neighbor-joining (NJ) and maximum likelihood (ML) methods, indicating that Schnabelia oligophylla and Caryopteris terniflora form a sister-group relationship. The Caryopteris complex is not shown to be a monophyly because Trichostema, C. paniculata and C. forrestii are paraphyletic to the clade containing the remaining members of the complex. A monophyly of Ajugoideae proposed by Cantino et al., including 8 genera in this study, is strongly supported and the closest relatives of Schnabelia are in the Ajugoideae (Lamiaceae), especially near Caryopteris terniflora. The polygenetic analyses also showed that the genera of Lamiaceae and Verbenaceae sampled in this tudy are phylogenetically mixed and the genus Avicennia is distant to other genera of Verbenaceae. RASA and combined analysis can be used as effective approaches to determining the relationships among phylogenetically complex groups.     

Recombinant PsbF from Synechococcus sp. PCC 7002 forms β:β homodimeric cytochrome b559

All organisms with oxygenic photosynthesis contain two photosystems:photosystem Ⅰ(PSⅠ)and photo-systemⅡ(PSⅡ),The minimal photosystem Ⅱ particles which are photochemically active contain three subunits:D1,D2 and cytochrome b559 (Cyt b559),The function of Cyt b559 remains unclear,We have successfully overxpressed the psbF gene,encoding the β subunit of Cyt b559,from a marine cyanobacterium Synechoccous sp.PCC 7002 as a fusion gene and obtained a redox-active from of Cyt b559,When the N-terminal GST protein of the fusion gene product was removed with thrombin ,the PsbF protein was still redox-active,suggesting that the recombinant PsbF can form dimer in Escherichia coli.The absorption spectra of either the oxidized from or the reduced form of both GST fusion protein and the purified PsbF dimer and the difference Spectra between the two forms are the same as that of the Cyt b559 isolated from the higher plants .Redox titration analysis of recombinant PsbF showed that the mid-point redox potential of the recombinant Cyt b559 was approximately 50 mV, which is close to the low potential of Cyt b559 ,The results are helpful to the understanding of locatlization and function of Cyt b559 on thylakoid membranes.Ⅰ