Biomedical subjects

Zhong-Huai Xiang

Publications and source records attributed to Zhong-Huai Xiang.

9 recordsLinked to original sources

PubMed2006

High-level expression of basic fibroblast growth factor in transgenic soybean seeds and characterization of its biological activity.

The glycinin G1 gene encodes a soybean seed storage protein accumulating at a high level. We have used the G1 promoter to confer seed-specific expression of human basic fibroblast growth factor (bFGF) in transgenic soybeans. The coding region of 18 kDa bFGF was fused to the promoter or promoter-signal peptide sequence of G1 gene, and transferred into soybean. Analysis of transgenic plants demonstrated that bFGF transcript or protein was confined to the seeds. The highest level of bFGF accumulation in the seeds reached up to 2.3% of total soluble protein. The soybean-derived bFGF was biologically active as confirmed by its mitogenic activity on Balb/c 3T3 cells, and exhibited other properties identical to native bFGF. We also observed a seed-specific expression of beta-glucuronidase driven by the G1 promoter. These results indicated that the G1 promoter contains essential cis-elements for seed-specific expression, and thus can be used for expression of pharmaceutical proteins in soybean seeds.

Animals↗

PubMed2006

EST-based profiling and comparison of gene expression in the silkworm fat body during metamorphosis.

The fat body plays key roles in metabolism and sustenance of growth throughout the life of a silkworm, and thus represents a model tissue for studying development and metamorphosis. Analysis of 18,480 ESTs derived from larval and pupal fat body cDNA libraries allowed characterization of gene expression patterns in the fat body during metamorphosis. By Phrap assembling, 6,814 estimated transcription units (TUs) were generated, 2,673 of which contained 60% of the total ESTs and represented 1,366 distinctive known genes. These genes were classified into 14 categories based on their known or putative functions, and most were found to be involved in metabolism and cell defense. Further comparative analysis of the expression profiles revealed that the gene expression patterns in the larval fat body strikingly differed from those in the pupal fat body. From this, we identified a subset of genes potentially associated with metamorphic events such as the formation or destruction of specific tissues, and simultaneously confirmed the stage-specific expression patterns of several identified genes using RT-PCR examination. This work will provide a valuable resource for studying regulatory mechanisms associated with fat body developmental changes and silkworm metamorphosis.

Animals↗

PubMed2005

Simple sequence repeat-based consensus linkage map of Bombyx mori.

We established a genetic linkage map employing 518 simple sequence repeat (SSR, or microsatellite) markers for Bombyx mori (silkworm), the economically and culturally important lepidopteran insect, as part of an international genomics program. A survey of six representative silkworm strains using 2,500 (CA)n- and (CT)n-based SSR markers revealed 17-24% polymorphism, indicating a high degree of homozygosity resulting from a long history of inbreeding. Twenty-nine SSR linkage groups were established in well characterized Dazao and C108 strains based on genotyping of 189 backcross progeny derived from an F(1) male mated with a C108 female. The clustering was further focused to 28 groups by genotyping 22 backcross progeny derived from an F(1) female mated with a C108 male. This set of SSR linkage groups was further assigned to the 28 chromosomes (established linkage groups) of silkworm aided by visible mutations and cleaved amplified polymorphic sequence markers developed from previously mapped genes, cDNA sequences, and cloned random amplified polymorphic DNAs. By integrating a visible mutation p (plain, larval marking) and 29 well conserved genes of insects onto this SSR-based linkage map, a second generation consensus silkworm genetic map with a range of 7-40 markers per linkage group and a total map length of approximately 3431.9 cM was constructed and its high efficiency for genotyping and potential application for synteny studies of Lepidoptera and other insects was demonstrated.

Animals↗

PubMed2005

Identification and expression pattern of Bmlark, a homolog of the Drosophila gene lark in Bombyx mori.

Two Bombyx mori isoforms of the gene lark, which is shown to play an important role in Drosophila circadian rhythms, were identified and named Bmlark-PA and Bmlark-PB, respectively. Bmlark-PA consists of 5 exons and encodes a protein of 343 amino acid residues which contains 3 functional domains: two RRM (RNA recognization motif) domains and an RTZF (retroviral-type zinc finger) and shares 72% identity with the Drosophila gene lark at the amino acid level. Bmlark-PB lacks the sequence between 118 and 791 nt of Bmlark-PA and codes for a protein of 68 amino acid residues, which contains no distinct functional domains. Alignments of the cDNAs of Bmlark to the genomic draft sequence of B. mori showed that the gene Bmlark had a single copy in the genome, suggesting that an alternative splicing mechanism occurs in the gene Bmlark. RT-PCR analysis indicated that Bmlark-PA was expressed only in late pupae and adult but Bmlark-PB was broadly expressed in many tissues and throughout the developmental stages from embryo to adult.

Alternative Splicing↗

PubMed2005

[Pridiction of the Sex-effects of the Cocoon Quality Characters in Silkworm.].

In this paper , the sex-effects of the cocoon quality characters in silkworm was predicted with Mixed linear model úThe fact that the probability of effect variance and predictability of random gender of whole cocoon weight, cocoon shell weight, ratio of cocoon shell and pupa weight reached a level of extreme significance showed that the gender effect of the four traits was extremely significant, which matched with the reality completely. The predictive values of gender effect of the four traits of female(male) were 0.248g (-0.247g), 2.423cg(-2.394)cg, -1.976%(1.992%) and 0.224g(-0.223g) respectively. Each trait showed single peak distribution after adjusting by sex-effects, which fitted for the request that quantitative traits should show continuously normal standard distribution if QTL analysis was taken.

Animals↗

PubMed2005

[Study on location of QTLs controlling cocoon traits in silkworm].

On the basis of the molecular linkage map, mapmaker software QTLMapper 2.0 was used to analyze the QTLs effect of the whole cocoon weight,cocoon shell weight, ratio of cocoon shell and pupa weight of domestic silkworm. For these four cocoon quantitative traits, 7, 6, 2 and 8 effective QTLs were detected and mapped to 7, 5, 2 and 7 linkage groups, respectively. Complicated epistatic effects were found involved in the genetic variation of the whole cocoon weight and cocoon shell weight. For the whole cocoon weight, there were three pairs of QTLs with significant additive by additive interactions, in which, one pair had significant additive by dominance and dominance by dominance interactions. Whereas significant dominance were detected for three QTLs and significant additive effects one QTL had. For the cocoon shell weight, significant genetic effects, including epistatic effects were found for one pair of QTLs, significant dominance by dominance interaction for another pair of QTLs; one QTL had significant dominance and another QTL had additive by additive interaction. The ratio of cocoon shell and the pupa weight were controlled mainly by additive or dominance effects. No interaction between QTL was found for the ratio of cocoon. Most QTLs, associated with the pupa weight, had negative dominance effects. Only significant additive by additive interaction was found between one pair of QTLs. The 2nd, 3rd, 4th, 11th, 13th, 24th, 34th, 37th, and 40th linkage groups are the common chromosomal regions harboring QTLs of two or more cocoon quantitative traits. There are identical QTL or chromosomal region for the whole cocoon weight and cocoon shell weight, indicating they can be simultaneously improved by utilizing epistatic effects in breeding.

Animals↗

PubMed2004

Mining single nucleotide polymorphisms from EST data of silkworm, Bombyx mori, inbred strain Dazao.

We made use of 81,635 expressed sequence tags (ESTs) derived from 12 different cDNA libraries of the silkworm, Bombyx mori, inbred strain Dazao (P50), to identify high-quality candidate single nucleotide polymorphisms (SNPs). By PHRAP assembling, 12,980 contigs containing 11,537 contigs assembled by more than one read were obtained, and 101 candidate SNPs and 27 single base insertions/deletions were identified from 117 contigs assembled from 1576 high-quality reads base-called with PHRED and screened on the basis of the neighborhood quality standard (NQS). Simultaneously, we also predicted 40 SNPs in coding regions (cSNPs), of which 26 were predicted to lead to amino acid non-synonymous variations and 14 synonymous substitutions. Also, the 1.66:1 ratio of transition/transversion is different from that of other insects. As the first SNP analysis of a Lepidoptera, B. mori, the single nucleotide polymorphic density is estimated to be 1.3 x 10(-3) by sequence diversity. This analysis shows that expressed sequences from multiple libraries may provide an abundant source of comparative reads to mine for cSNPs from the silkworm genome.

Amino Acid Substitution↗

PubMed2004

[Construction of AFLP molecular markers linkage map and localization of green cocoon gene in silkworm (Bombyx mori)].

Based on an improved method of AFLP, AFLP markers were employed for construction of a linkage map and localization of Gc gene used a set of 44 backcross lines( BC1) of silkworm ( Bombyx mori) as a mapping population. In this work, all together 3 956 bands were obtained by 28 pairs of primers and 141.3 bands each primer pair on average. Among them 2 836 bands were in good agreement with the segregation pattern. A total of 1 018 (25.7%) polymorphic AFLP markers were detected. The 693 (68.1%) of polymorphic markers with 1:1 segregation ratio ( P < or = 0.05) were obtained. Furthermore,The analytical model was based on the backcross type and the parameters were set as following: LOD = 3.0, maximum recombination value of 0. 20 and use the command ' group', 'compare', 'try', 'map' and 'ripple' to construct the linkage maps. 407 of the 693 loci were chi2 tested in agreement with 1:1 segregation were divided into 33 linkages by Mapmaker/Exp(Version 3.0), with a total map distance of 3 676.7 cM and a mean distance of 9.1 cM between markers. The morphological gene Gc was located between L-P4T6-107 and L-PT6T4-84 on linkage group 22. In addition, 286 markers were not included in the linkage groups. The efficiency of loci mapping was 58.7%. Among the 33 linkage groups, the morphological marker Gc classically localized on linkage group 15 was relocated on linkage group 22 on the map, suggesting that this molecular linkage group corresponds to linkage group 15 on the linkage map based on morphological characters. All these have laid an important base for the marker assisted breeding of the silkworm.

Animals↗

PubMed2004

[Three Bombyx mori genes, chi, gluE and fruA, encode proteins homologous to microorganism and primary analysis of horizontal gene transfer].

According to the analysis of large scale EST sequencing of silkworm, Bombyx mori, we found that chi, glue and fruA of silkworm have very high homology at amino acid level and closely phylogenetic relative with that of microorganism, but lower similarity with genes of eelworm (Caenorhabditis elegans), fruitfly (Drosophila melanogaster), mosquito (Anopheles gambiae) and other relative insects, respectively. It indicates that each of them is likely to have common ancestor with that of microorganism. Namely, microbial genes were likely transferred to silkworm by horizontal gene transfer, instead of the vertical inheritance in evolutionary manner.

Animals↗