Nucleotide Sequence of Polyhedrin Gene of LsNPV and Analysis of Baculovirus Polyhedron Proteins

The intact 741 hp polyhedrin gene of LsNPV was sequenced by Silver Sequencing System, and shares 90.6% and 97.0% nucleotide identity, 97.2% and 97. 6% amino acid identity with PfNPV and MdNPV polh genes respectively. The 14 hp conservative sequence with the core element GTAAG,is located in the 5'untranslated region of the gene. The polh gene was predicted to encodes a 246 amino sold residures with molecular weight of 29.0 kd, in which the number of acidic amino acids and alkaline amino acids was roughly equal resulting in almost no charges in polyhedrin protein molecule and hence occlusion body. It gives a valuable implication that ionic bonds as well as hydrophobic bonds and hydrogen bond may Play an important role in the crystallization or polyhedrin, by comparing amino acid variation of twenty-one polyhedrin. The comparison of promoter regions of polyhedrin gene and class Ⅲ gene shown that they are very similar, but also have differences in GC content.This could explain that both categories of gene are highly expressed, and polyhedrin genes are expressed more higher than class Ⅲ gene.

Identification and preliminary characterization of novel B3-type metallo-β-lactamases

Antibiotic resistance has emerged as a major global threat to human health. Among the strategies employed by pathogens to acquire resistance the use of metallo-β-lactamases (MBLs), a family of dinuclear metalloenzymes, is among the most potent. MBLs are subdivided into three groups (i.e. B1, B2 and B3) with most of the virulence factors belonging to the B1 group. The recent discovery of AIM-1, a B3-type MBL, however, has illustrated the potential health threat of this group of MBLs. Here, we employed a bioinformatics approach to identify and characterize novel B3-type MBLs from Novosphingobium pentaromativorans and Simiduia agarivorans. These enzymes may not yet pose a direct risk to human health, but their structures and function may provide important insight into the design and synthesis of a still elusive universal MBL inhibitor.

Unusual metallo-β-lactamases may constitute a new subgroup in this family of enzymes

Metallo-β-lactamases (MBLs) are a family of Zn2+-dependent enzymes that have contributed strongly to the emergence and spread of antibiotic resistance. Novel members as well as variants of existing members of this family are discovered continuously, compounding their threat to global health care. MBLs are divided into three subgroups, i.e. B1, B2 and B3. The recent discovery of an unusual MBL from Serratia proteamaculans (SPR-1) suggests the presence of an additional subgroup, i.e. B4. A database search reveals that SPR-1 has only one homologue from Cronobacter sakazakii, CSA-1.These two MBLs have a unique active site and may employ a mechanism distinct from other MBLs, but reminiscent of some organophosphate-degrading hydrolases.

Efects on the Early Development of the Pearl Sac by Cytochrome c,Yolk Lecithin and Polyvinyplyrro

A 1500 bp DNA fragment of LsNPV genome was sequenced by silver sequencing system. A whole coding region of ORF1 and an incomplete ORF2 were found. ORF1 was 345 bp long and was predicted to encode a protein with 115 amino acid residues, the 5'regulatory region of ORF1 contained early transcriptional consensus sequence such as AT/ACGTGT,CGTGC and a stem loop structure. On the 3'terminus of ORF1, a poly(A) tail signal was found. Incomplete ORF2 was 354 bp long and predicted to encode 118 amino acid residues, the 5'regulatory region of ORF2 contained two conserved late transcriptional motif ATAAG. Compared with all the genes from AcNPV, incomplete ORF2 showed 56.5% nucleotide sequence homology and 44.9% amino acid sequence homology with AcNPV PDV E66 gene. Two conserved ATAAG motif on 5'regulatory region of ORF2 was similar to those in AcNPV PDV E66 gene. ORF1 showed no high identity with AcNPV and other baculoviruses.

Recent advances in the culture-independent discovery of natural products using metagenomic approaches

Natural products derived from bacterial sources have long been pivotal in the discovery of drug leads.However,the cultivation of only about 1%of bacteria in laboratory settings has left a significant portion of biosynthetic diversity hidden within the genomes of uncultured bacteria.Advances in sequencing technologies now enable the exploration of genetic material from these metagenomes through culture-independent methods.This approach involves extracting genetic sequences from environmental DNA and applying a hybrid methodology that combines functional screening,sequence tag-based homology screening,and bioinformatic-assisted chemical synthesis.Through this process,numerous valuable natural products have been identified and synthesized from previously uncharted metagenomic territories.This paper provides an overview of the recent advancements in the utilization of culture-independent techniques for the discovery of novel biosynthetic gene clusters and bioactive small molecules within metagenomic libraries.

The Stripe Rust Resistance Gene Yr10 Encodes an Evolutionary-Conserved and Unique CC-NBS-LRR Sequence in Wheat

The first seedling or all-stage resistance （R） R gene against stripe rust isolated from Moro wheat （Triticum aes- tivum L.） using a map-based cloning approach was identified as Yr10. Clone 4B of this gene encodes a highly evolutionary- conserved and unique CC-NBS-LRR sequence. Clone 4E, a homolog of Yr10, but lacking transcription start site （TSS） and putative TATA-box and CAAT-box, is likely a non-expressed pseudogene. Clones 4B and 4E are 84% identical and divergent in the intron and the LRR domain. Gene silencing and transgenesis were used in conjunction with inoculation with differen- tially avirulent and virulent stripe rust strains to demonstrate Yr10 functionality. The Yr10 CC-NBS-LRR sequence is unique among known CC-NBS-LRR R genes in wheat but highly conserved homologs （E = 0.0） were identified in Aegilops tauschii and other monocots including Hordeum vulgare and Brachypodium distachyon. Related sequences were also identified in genomic databases of maize, rice, and in sorghum. This is the first report of a CC-NBS-LRR resistance gene in plants with limited homologies in its native host, but with numerous homologous R genes in related monocots that are either host or non-hosts for stripe rust. These results represent a unique example of gene evolution and dispersion across species.

NBS-LRR resistance gene homologues in rice

Twenty three DNA fragments with a size of about 520 bp have been cloned from rice genome by PCR amplification using primers designed according to the conserved region of most plant resistance (R) genes which have Nucleotide Binding Site (NBS) and Leucine-Rich Repeat (LRR) domains. Homologous comparison showed that these fragments contained typical motifs of the NBS-LRR resistance gene class, kinase 1a, kinase 2a, kinase 3a and domain 2. Thus they were named R gene homologous sequences (RS). These RS were divided into 4 groups by clustering analysis and mapped onto chromosomes 1, 3, 4, 7, 8, 9, 10 and 11, respectively, by genetic mapping. Ten RS were located in the chromosomal intervals where known R genes had been mapped. Further RFLP analysis of an RS, RS13, near the bacterial blight resistance gene Xa4 locus on chromosome 11 among near isogenic lines and pyramiding lines of Xa4 showed that RS13 was possibly amplified from the gene family of Xa4.