Yi chuan xue bao = Acta genetica Sinica最新文献

As a new resource of mutagens,low-energy ion beam implantation is characterized as limited physiological damages,wide mutation spectrum, and high mutation frequency in comparison with the mutations from other inducing methods. We treated a wheat doubled haploid line Yi4212 with this technique by nitrogen ion and established a mutant population with 60 lines in our lab. The mutant lines were systematically investigated about their -developmental periods,agronomical performances, gliadin contents and microsatellite variations in M4 generation. The results revealed that in addition to extensive changes of the developmental, agronomical and economical traits of the mutants,the moblities in acid-PAGE of 7 omega-gliadin subunits were also showed changes as some gliadins lacked and novel gliadins obtained. Deletion, expansion and contraction of SSR amplification products occured frequently in 25 SSR loci in the mutants. Combined with our results and other reports,the application prospects of those wheat mutants and the mutation mechanism by ion beam implantation are discussed.

Genetic variation within exon 2 of chicken major histocompatibility complex B-LB // genes was investigated by PCR amplification, cloning and sequencing of a 374 bp fragment of the indigenous Tibetan chicken genomic DNA. Fifteen novel B-LB // alleles were found. Alignment and comparison of 18 allelic sequences from the individuals sampled revealed a total of 62 variable sites (total of 80 mutations) in exon 2, of which 41 were parsimony informative sites. The nucleotide diversity (pi) within the sequence of exon 2 was calculated to be 0.0718. Analysis of nucleotide variation confirmed a lower level of divergence (0.056 +/- 0.008) as estimated by average pairwise distance within the Tibetan chicken population than the five exotic breeds detected. The relative frequencies of synonymous and non-synonymous nucleotide substitutions within the region were 3.25 +/- 0.94% and 15.61 +/- 2.69% , respectively. These results indicated that the genetic variation within exon 2 seemed to have arisen largely by gene recombination and balancing selection. Alignment of the deduced amino acid sequences of beta1 domain coded by exon 2 revealed 11 synonymous mutations and 27 non-synonymous substitutions at the 38 separate sites. Fifty percent (12/24) of the proposed peptide-binding sites were variable within beta1 domain of chicken MHC B-LB // molecules, of which 11 were unique non-synonymous amino acid substitutions. These particular non-synonymous substitutions are considered to be associated with immunological specificity of MHC B-LB // molecule in Tibetan chicken, and they can provide a molecular biological basis for the study of disease resistance in chicken.

We identified and isolated a dual-specificity kinase gene,OsSTY kinase (O. sative serine/threonine/tyrosine kinase) gene, from rice. OsSTY kinase gene encoded a protein of 417 amino acids with calculated molecular weight 45926 Da and isoelectric point 7.689. OsSTY kinase is involved in the multiple stresses signaling pathway. Low- and high-temperature (4 degrees C and 37 degrees C) stresses significantly induce the expression of OsSTY kinase. The kinase is also up-regulated upon wounding (by cut), salicylic acid (SA) and ethophon (ET). Moreover,ectopic expression of OsSTY kinase gene in yeast Saccharomyces cerevisiae ste7/ste7 mutant partially suppressed the pseudohyphal development defect of the strain under the condition of nitrogen starvation. Ste7 is a serine/threonine/tyrosine kinase of Saccharomyces cerevisiae, which shares 32% identity and 50% similarity with OsSTY kinase in the kinase domains. This finding suggested that OsSTY kinase could correct, at least partially, the defect of ste7/ste7 mutant.

This paper describes the characterization of novel wheat lines NR98116-9-2 and NR98116-9-3 derived from crosses of wheat with hexaploid triticale and expressing seven different high molecular weight glutenin subunits by SDS-PAGE analysis. The results suggested that the two lines were similar to wheat in morphological characters and were stable genetically. The chromosome number of root tip cells of the two lines were 2n=42 and 2n=44 and the configuration of the pollen mother cells at metaphase I were 21 // and 22 //, respectively. The analysis of chromosome constitution by in situ hybridization and C-banding led to the conclusion that NR98116-9-2 was a 3R (3D) disomic substitution line and NR98116-9-3 was a 3R disomic addition line. The HMW-GS compositions were 1, 14 + 15, 6r + 8, 4 + 12 and 1, 14 + 15, 6r + 8, 5 + 10, respectively. It is very interesting that both lines may contain two Glu-B1 sites. The potential usefulness of the two germplasm that expressed seven different high molecular weight glutenin subunits in wheat quality improvement was discussed.

Methodology of QTL mapping for ordinal traits of disease resistance based on the framework of a generalized linear model (GLM) was presented. The location and effect parameters of putative QTL were estimated using maximum likelihood method. The efficiency and power were compared with the linear model (LM). The factors influencing QTL detection efficiency (e.g. QTL effect and heritability) were simulated in our study too. Daughter design with multiple families was applied,and the number of segregating population was 500. Results showed that the threshold model has a certain advantage in location estimation and power of QTL mapping, and has efficiency and accuracy for ordinal traits. In addition,the accuracy of QTL mapping depends on the effect of putative quantitative trait loci and the value of heritability. With the increase of QTL effect and heritability, the accuracy of QTL mapping improves slightly.

Whether DNA methyltransferase 3B (DNMT3B) is deregulated in hepatocellular carcinoma cell lines is still unclear. The expression levels of DNMT3B protein in normal liver cell line, pericacinoma cell line and hepatocellular carcinoma cell lines were compared by both Western blotting and immunocytochemistry. Long-term downregulated DNMT3B in a hepatocellular carcinoma cell line SMMC-7721 was achieved using a RNAi recombinant plasmid. The suppression of DNMT3B induced by RNA interference was confirmed using semi-quantitative RT-PCR and Western blotting. High throughput cDNA microarray was used to analyze the expression profiling of downstream genes of DNMT3B displayed in the treated cell lines and control. In the result,DNMT3B in hepatocellular carcinoma cell lines was expressed at a significantly higher level compared to those in pericacinoma cell line and normal liver cell line. A specific DNMT3B siRNA stably expressed from a plasmid vector effectively suppressed the expression of DNMT3B in SMMC-7721 cell line. By microarray analysis,26 downregulated genes and 115 upregulated genes have been identified in the DNMT3B knockdown cell line,including some important developmental genes and tumor-related genes such as SNCG, NOTCH1, MBD3, WNT11, MAOA and FACL4. The discovery showed DNMT3B was over-expressed in most hepatocellular carcinoma cell lines examined and may be linked to the carcinogenesis of hepatocytes. An array of candidate genes that are involved in the action of DNMT3B have been identified,including those related to development.

The genetic effects of seed traits in soybean, including 100-seed weight, seed length, seed width, seed thickness, length/width, length/thickness and width/thickness, were analyzed using an incomplete diallel cross of eight varieties with its F1 and F2 populations. The results showed that the above seven traits were controlled by direct genetic effects of seed and affected to different extent of maternal and cytoplasmic effects simultaneously. Among the traits, the inheritance of 100-seed weight, seed length, length/width, length/thickness, and width/thickness were mainly controlled by cytoplasmic effects, while those of seed width and thickness were mainly by maternal effects. Both the seed direct heritabilities and the cytoplsmic heritabilities of 100-seed weight, seed length, length/width and width/thickness were medium-sized. The individual selection and seed selection of above four traits at late generation may create good results. The maternal heritabilities of seed width and thickness were pretty high. To increase these two traits, an individual maternal selection should be done at early generation. Our results showed that varieties P2 and P7 could be used as ideal parents for improvements of 100-seed weight, seed length/width, length/thickness and width/thickness, while varieties P1, P4 and P6 are the ideal parents for increasing seed length, width and thickness respectively.

Female precocious puberty is caused by premature activation of the hypothalamic-pituitary-gonadal axis, exposure to exogenous sex steroid hormones, and the presence of endogenous sex steroids caused by various factors. Estrogen is the final key factor to start onset of puberty. However,in some cases of precocious puberty in girls estrogen elevation could not be detected. The raised sensitivity of estrogen receptor, which may caused by ESR1 mutation or polymorphism, has been frequently mentioned for interpreting the etiology of sporadic low estrogen type cases. But no case evidence has been found in clinical practice. For the purpose of screening possible mutations in estrogen receptor gene, leukocyte genomic DNA were collected from 16 girls with precocious puberty of sporadic low estrogen,and exons of ESR1 were amplified and analysized using PCR-SSCP/silver staining method. A single strand conformation change in exon 8 was found in one of the patients (No. 14). The suspected fragment were cloned to a T vector and sequenced for analysis. Sequencing of these clones revealed that this conformation change is caused by a C to T transition. This mutation results in the replacement of arginine by cystine at position 548 of ESR1 protein. The mutation created an extra Btsl digest site and made it can be readily identified by PCR-PFLP method. Further detection using this method, and sequencing of cloned exon8 colonies from patients proved that the patient No. 14 is Arg548/Cys548 heterozagous in genotype. This mutation increased hydrophobility of the area dramatically. The position and the conservative of this residue in vertebrates suggested Arg548 may play an important role in ESR1 function. For study the role of this mutation in the onset of precocious puberty, a firefly luciferase reporter plasmid pGL3-promoter-ERE was constructed,and a pCR3. 1-hermut pisimid expressing Cys548 ER was constructed based on wild type pCR3. 1her. Co-transfection of reporter and pCR3. 1 -hermut in CMF-7 cell strain proved that Cys548 mutant can significantly increase the transcription activity over the Arg548 wild type.

Using an estrogen-inducible expression XVE (LexA-VP16-Estragon Receptor) system, we have generated approximately 40 000 independent T-DNA insertion lines of Arabidopsis thaliana. Segregation analyses of about 18000 lines indicated that 51.6% of them contain single T-DNA insertions and that the average insertion number is 1.38 copies per line. Mutants displaying a variety of morphological alterations were identified, including those that affect development of roots,hypocotyls, leaves, floral organs and seeds as well as the flowering time.

Genetic variations at 10 microsatellite loci were surveyed to determine the evolutionary relationships and molecular characteristics of three different honeybee (Apis mellifera L.) populations from Italy and China, i. e., native Italian (Ee), Chinese-Italian (Eb) and selected high royal jelly producing bees (Ea). A total of 96 alleles,an average of 9.6 alleles per locus,were scored in Ee,Eb and Ea bees at 10 loci. Out of which 48 (5%) were different. This indicated a high degree of polymorphism and ever, some genetic differentiation among the three populations due to artificial selection and geographical isolation. The polymorphic information contents (PIC) and heterozyosity of the three populations at 10 loci were 0.57, 0.50, 0.57, and 0.60, 0.57, 0.61, for Ee, Eb, Ea populations respectively, neither of which were different. This indicated same gene diversity within the three populations. The genetic distance was shorter between Ee and Eb bees as well as between Eb and Ea bees. Whereas that between Ee and Eb bees was longer. Further analysis indicated that the allele frequency of seven alleles at six loci (159 bp at A29,100 bp and 104 bp at A24; 110 bp at A7; 126 bp at A43, 221 bp at A14 and 221 bp at A113) increased going from Ee to Eb to Ea bees. Paired tests showed significant higher allele frequency between Ea and Eb bees,as well as between Ea and Eb bees. This indicates that these seven alleles are likely molecular markers of the high royal jelly producing bees. In addition,the allele frequency of four alleles at four loci (106 bp at A24,140 bp at A43;215 bp at A113 and 219 bp at A14) decreased going from Ea bees to Eb to Ee. Paired tests indicated significant lower allele frequency between Ea and Ee bees,as well as between Ea and Eb bees. Those four alleles may be the genetic markers for low royal jelly production.