Acta Genetica Sinica最新文献

A genetic linkage map comprising 148 SSR markers loci was constructed using an F₂ population consisting of 90 lines derived from a sub-specific cross between a japonica variety Nipponbare and an indica variety Guangluai-4. The F₂ population showed high significantly distorted segregations. Among these SSR markers, 49 markers (33.11%) showed the genetics distortion(P<0.05). Of them, 36 markers deviated toward male parent indica GuangLuAi-4 and 13 markers toward heterozygote, but none toward the female parent Nipponbare. It was found that the segregation distortion might be caused by gametophyte and zygote. Since most gametophyte loci and sterility loci were mapped in segregation distortion regions, it indicated that the segregation distortion may be caused by these gametophyte loci and sterility loci. Finally, this research also analyzed the skewed segregation of some markers, which had not been mapped on chromosome.

We used gene trapping vector PU8 to search some interesting genes which play important roles in mouse development from murine ES cells. One positive ES colony termed Ayu17–449 was trapped. Its partial cDNA was obtained by using 5′ RACE method. It is homologous to a 5523 bp cDNA fragment (GI: 20879412) in EST database. Further analysis of the 5523 bp cDNA sequence in Celera mouse gene database showed that it overlaps two genes. We designed serials of DNA primers according to the mRNAs of these two genes for RT-PCR and Northern blotting analysis, and identified a novel RNA about 9 kb (we named it as Ayu17-449) encoding 1920 aa. This gene is expressed highly in the brain, kidney, heart, lung, muscle and stomach. The expressed protein contains a Granin motif on its N-terminus, showing that this gene may be involved in hormone secretion.

The complete sequences of mitochondrial DNA D-loop of 128 individuals in nine Chinese goat (Capra hircu) breeds were analyzed by DNA sequencing technology. The results show that the length of mtDNA D-loop in Chinese goats is 1 212-1 213 bp. There are 102 polymorphic sites, accounting for 8.42% of 1 212 bp sequence. Ninety-two mtDNA haplotypes were determined. The haplotype diversity and nucleotide diversity are 0.9333-1 .0000 and 0.7062%-1.8265%, respectively. The results indicate that the genetic diversity of Chinese goats is very abundant. The NJ tree indicates that Chinese goats have two types of maternal origins from lineage A and lineage B. The possibility of lineage B originating from China is also discussed.

Using Affymetrix U133A oligonucleotide microarrays, screening was done for genes that were differentially expressed in gastric cancer (T) and normal gastric mucosa (C), and their chromosome location was characterized by bioinformatics. A total of 270 genes were found to have a difference in expression levels of more than eight times. Of them 157 were up-regulated (Signal Log Ratio [SLR]≥3), and 113 were down-regulated (SLR≤-3). Except for, four genes with unknown localization, a vast majority of the genes were sporadically distributed over every chromosome. However, chromosome 1 contained the most differentially expressed genes (26 genes, or 9.8%), followed by chromosomes 11 and 19 (both 24 genes, or 9.1%). These genes were also more likely to be on the short-arm of the chromosome (q), which had 173 (65%). When these genes were classified according to their functions, it was found that most (67 genes, 24.8%) belonged to the enzymes and their regulators groups. The next group was the signal transduction genes group (43 genes, 15.9%). The rest of the top three groups were nucleic acid binding genes (17, 6.3%), transporter genes (15, 5.5%), and protein binding genes (12, 4.4%). These made up 56.9% of all the differentially expressed genes. There were also 50 genes of unknown function (18.5%). Therefore it was concluded that differentially expressed genes in gastric cancer seemed to be sporadically distributed across the genome, but most were found on chromosomes 1, 11 and 19. The five groups associated genes abnormality were important genes for further study on gastric cancer.

Diploid gynogenesis was induced in Japanese crucian carp (Carassius cuvieri) eggs using UV-irradiated genetically inactive spermatozoa from mirror carp (Cyprinus carpio L.) or blunt snout bream (Megalobrama amblycephala), with or without cold shock. The optimal radiation dosage was 4200 mJ/cm² and 3600 mJ/cm² for mirror carp and blunt snout bream sperm, respectively. At this dosage and without cold shock, the yields were (32.4±3.3)% vs. (33.8±1.4)% gynogenetic haploids and (0.7±0.3)% vs. (0.5±0.3)% hybrid diploids, respectively. At the optimal UV dosage but with cold shock (2 min after fertilization, 0–4°C for 40 min), the hatching rates were (27.8±2.1)% and (29.4±3.3)%, respectively. From hatching to feeding, (15.7±3.4)% and (23.6±4.1)% normal gynogenetic diploids were recorded, respectively. Survival of normal gynogenetic diploids was 56% out of the hatched fry when using irradiated spermatozoa of mirror carp, which was lower than that (up to 80%) when using irradiated spermatozoa of blunt snout bream. This indicated that the sperm of blunt snout bream, with distant genetic relation to the maternal Japanese crucian carp, was more effective than that of mirror carp to induce diploid gynogenesis. The nature of the gynogenetic progeny was identified with external appearance, chromosome number and gonad structure. The presence of only females in gynogenetic progeny probably suggested XX genotype in the female Japanese crucian carp. The gynogenetic diploids have potential values such as faster growth and stronger disease resistance than the normal Japanese crucian carp. All gynogenetic progeny possessed 100 chromosomes whereas all J x B crosses were triploid with 124 chromosomes. The formation of the new triploid hybrids in J x B crosses may be useful in aquaculture.

Expression vector pBAC128F, which carries DREB transcriptional factor gene driven by drought inducing promoter rd29B and bar gene driven by CaMV 35S promoter and maize Adh1 gene first intron, was transferred into the explants of immature inflorescence and immature embryos of hexaploid winter wheat cv. 8901, 5–98, 99–92 and 104 by particle bombardment. More than 70 resistant transgenic plants were obtained. Genomic PCR and RNA dot blotting analyses showed that DREB gene had been integrated into wheat genome of the transgenic plants (T₀ and T₁) and was well expressed in offspring seed of different transgenic lines. The content of proline in leaves and seeds of T₂ transgenic lines was analyzed. Among 16 tested transgenic lines, 10 transgenic lines exhibited more than two fold of proline level in leaves as compared with CK plants. Under drought condition, after stopping water for 15 days the leaves of transgenic lines were still green, while CK were faded. After rewatering for 10 days, the leaves of transgenic lines maintained their green, while all CK plants were dead. Our research suggested that introducing a novel DREB transcriptional factor into wheat is an effective way to improve its drought-tolerance ability.

Genomic DNA is under constant attack from both endogenous and exogenous sources of DNA damaging agents. Without proper care, the ensuing DNA damages would lead to alteration of genomic structure thus affecting the faithful transmission of genetic information. During the process of evolution, organisms have acquired a series of mechanisms responding to and repairing DNA damage, thus assuring the maintenance of genome stability and faithful transmission of genetic information. DNA damage checkpoint is one such important mechanism by which, in the face of DNA damage, a cell can respond to amplified damage signals, either by actively halting the cell cycle until it ensures that critical processes such as DNA replication or mitosis are complete or by initiating apoptosis as a last resort. Over the last decade, complex hierarchical interactions between the key components like ATM/ATR in the checkpoint pathway and various other mediators, effectors including DNA damage repair proteins have begun to emerge. In the meantime, an intimate relationship between mechanisms of damage checkpoint pathway, DNA damage repair, and genome stability was also uncovered. Reviewed hereinare the recent findings on both the mechanisms of activation of checkpoint pathways and their coordination with DNA damage repair machinery as well as their effect on genomic integrity.

A method was developed to model and optimize selection on multiple identified quantitative trait loci (QTLs) and polygenic estimated breeding value, in order to maximize a weighted sum of cumulative response to selection over multiple years in a population with overlapping generations. The model allows for a population with multiple sex-age classes, different number of age class between sires and dams, and varied genetic contribution of the age class. The optimization problem was formulated as a multiple-stage optimal control problem and solved by a forward and backward iteration loop. The practical utility of this method was illustrated in an example of pig breeding population with overlapping generations. The selection response of this method was compared with standard QTL selection and conventional best linear unbiased prediction (BLUP) selection. Simulation results show that optimal selection achieved greater selection response than either standard QTL or conventional BLUP selections. The influence of population structure on optimal selection was significant. Optimal QTL selection and standard QTL selection were more favorable in a population with overlapping generations than discrete generations, and obtained more benefits relative to conventional BLUP selection in a population with overlapping generations. Optimal QTL selection relative to conventional BLUP selection is also more favorable following increase of genetic contribution of two-year-old boars and sows in a population with overlapping generations.

Glucose-6-phosphate dehydrogenase is a rate-limiting enzyme of pentose phosphate pathway, existing in cytosolic and plastidic compartments of higher plants. A novel gene encoding plastidic glucose-6-phosphate dehydrogenase was isolated from rice (Oryza sativa L.) and designated OsG6PDH2 in this article. Through semiquantitative RT-PCR approach it was found that OsG6PDH2 mRNA was weakly expressed in rice leaves, stems, immature spikes or flowered spikes, and a little higher in roots. However, the expression of OsG6PDH2 in rice seedlings was significantly induced by dark treatment. The complete opening reading frame (ORF) of OsG6PDH2 was inserted into pET30a (+), and expressed in Escherichia coli strain BL21 (DE3). The enzyme activity assay of transformed bacterial cells indicated that OsG6PDH2 encoding product had a typical function of glucose-6-phosphate dehydrogenase.

According to the conserved sequences flanking the 3′ end of the 16S and the 5′ end of the 23S rDNAs, PCR primers were designed, and the 16S-23S rDNA intergenic spacers (IGSs) of two strains of Vibrio vulnificus were amplified by PCR and cloned into pGEM-T vector. Different clones were selected to be sequenced and the sequences were analyzed with BLAST and the software DNAstar. Analyses of the IGS sequences suggested that the strain ZSU006 contains five types of polymorphic 16S-23S rDNA intergenic spacers, namely, IGS^GLAV, IGS^GLV, IGS^lA, IGS^G and IGS^A; while the strain CG021 has the same types of IGSs except lacking IGS^A. Among these five IGS types, IGS^GLAV is the biggest type, including the gene cluster of tRNA^Glu - tRNA^Lys - tRNA^Ala - tRNA^Val; IGS^GLV includes that of tRNA^Glu-tRNA^Lys-tRNA^Val; IGS^AG, tRNA^Ala-tRNA^Glu; IGS^IA, tRNA^Ile-tRNA^Ala; IGS^G, tRNA^Glu and IGS^A, tRNA^Ala. Intraspecies multiple alignment of all the IGS sequences of these two strains with those of V. vulnificus ATCC27562 available at GenBank revealed several highly conserved sequence blocks in the non-coding regions flanking the tRNA genes within all of strains, most notably the first 40 and last 200 nucleotides, which can be targeted to design species-specific PCR primers or detection probes. The structural variations of the 16S-23S rDNA intergenic spacers lay a foundation for developing diagnostic methods for V. vulnificus.