Yi chuan xue bao = Acta genetica Sinica最新文献

SMAD3 is one of the receptor-activated SMADs which are important in TGF-beta signal transduction. Smad3-null mice show accelerated cutaneous wound healing compared with wild-type mice. In this work, we investigated the functions and the mechanism of Smad3-mediated TGF-beta signal on matrix metaloproteinase-2 (MMP-2) in mouse fibroblast. We found that MMP-2 at wound bed was expressed earlier in Smad3-null mice than that in wild type and heterozygotes. In the sera of wounding mice, the activity of MMP-2 was also remarkably higher in Smad3-null mice than that in the other two. The embryonic fibroblasts were separated from Smad3 knockout mice to test the function of Smad3 in modulating the expression of MMP-2. The results showed that the expression and activity of MMP-2 in Smad3-null fibroblasts were higher than those in wild type cells. TGF-beta1 could increase the MMP-2 activities in both Smad3 mutant and wild type fibroblasts. The expression and activity of MMP-2 were inhibited by over expression of SMAD3 in Smad3-null fibroblasts, while the expression and activity of MMP-2 were increased by over expression of anti-sense Smad3 in wild type cells. All these results showed that SMAD3 inhibited the expression of MMP-2 in mouse embryonic fibroblasts.

The embryo-derived calli from four types of tall fescues (Festuca arundinacea Schreb) were transformed with two Agrobactrium tumefaciens strains AGL1 and GV3101. AGL1 harbors an intron-AtNHX1 expression vector pROK2U containing ubiqutin promoter and npt II marker gene. GV3101 harbors an intron-AtNHX1 expression vector pROK2 containing 35S promoter and npt II gene. After infection and co-culture with AGL1 or GV3101, the embyogenic calli were selected with 50-150 mg/L paromomycine and 1126 resistant plants regenerated from the resistant calli. All plants were selected further with 10-20 mg/L Kanamycin and 525 of them remained green. Genome DNA of the resistant plants was checked with specific primers and probe from AtNHX1 gene. The results of PCR assay and Southern blot analysis indicted that exogenous target gene (AtNHX1 gene) had been transferred into different cultivars of Festuca arundinacea. Different transformation frequencies among the four cultivars were obtained.

We analyzed the electrophoritic patterns of 16 kinds of isozyme and three kinds of storage protein in Agropyron elongatum 2x and Ag. elongatum 4x by isoelectric focusing (IEF) and SDS-PAGE, respectively. The results showed three types of electrophoritic patterns. In the first type, the zymogram phenotypes are identical between Ag. elongatum 2x and Ag. elongatum 4x. Two kinds of isozyme belong to this type, which accounts for 10.5% of all the biochemical markers analyzed. In the second type, Ag. elongatum 4x showed a phenotype which is made up of combinations of the all of Ag. elongatum 2x bands and the specific bands. Ten kinds of isozyme and three kinds of storage protein fall into this class, which is the most part and accounts for 63.2% of all the markers analyzed. In the third type, Ag. elongatum 2x and Ag. elongatum 4x showed some identical bands and their own specific bands. Five kinds of isozyme were classified to this group,which accounts for 26.3% of all the markers analyzed. The results above suggested that Ag. elongatum 4x is a allotetraploid composed of one genome originated from Ag. elongatum 2x and another unknown genome which is apparently distinct from the St, J and N genomes of relative species. Otherwise, SSR primers were used to analyze the relation of Ag. elongatum 2x and Ag. elongatum 4x. The amplification results of most primers showed that Ag. elongatum 2x and Ag. elongatum 4x have some identical bands and Ag. elongatum 4x have some specific bands. This result validated the conclusion from biochemical marker analyses that Ag. elongatum 4x is a allotetraploid.

Agrobacterium-mediated transformation is probably the most widely used method to introduce genes into plants. Great progress has been made in recent years in studies on the mechanism of Agrobacterium-mediated transformation. Agrobacterium genetically transforms plants by transferring a portion of the resident Ti-plasmid, the T-DNA, to the plant. VirD2 and VirE2 accompany the T-DNA into the plant cell. Both proteins may aid in T-DNA transfer, nuclear targeting and integration into the plant genome. In recent years, some Arabidopsis rat (resistant to transformation) mutants are deficient in T-DNA integration according to some studies. These results showed that plant genes participate in the T-DNA transport and integration process. This paper discusses our current knowledge about the functions of virulence protein, namely VirD2 and VirE2, and plant genes in several aspect of Agrobacterium transformation. The paper discusses two different classes of integration patterns in detail: one is T-DNA right border being linked to genomic sequences by the VirD2 protein, the other is T-DNA integration via SDSA (synthesis-dependent strand-annealing). According to the latest studies we elaborated the T-DNA integration model based on genomic DSB (double-strand breaks) and proposed a new opinion about the mechanism of T-DNA integration.

The complete sequence of the Pseudorabies Virus (PRV) genomic DNA has not yet been determined, primarily because of the high content of G + C nucleotides of about 74%. We examined the base composition and codon usage of the 68 known PRV genes. As a result, we found a strong bias towards GC-rich codons especially NNC or NNG (N represents any one of four nucleotides) in PRV genes. This demonstrated that the usage bias of synonymous codon and amino acid is the main cause of the high G + C content of PRV. The results showed that the genome regions adjacent UL48, UL40, UL14, IE180 genes where the G + C content occurs as pronounced waves are corresponding to the replication origins. It was also found that the codon usage patterns of regulatory genes are apparently different from other PRV genes. A corresponding analysis of amino acid compositions indicated that the bias of codon usage could be related to the differences of gene function.

A new LOS2 gene was cloned from C. bursa-pastoris by rapid amplification of cDNA ends (RACE). The full-length cDNA of C. bursa-pastoris LOS2 gene (designated as Cblos2) was 1694 bp containing a 1332 bp open reading frame (ORF) encoding a 444 amino acid protein. The predicted CbLOS2 protein contained enolase-N domain, enolase domain, conserved putative DNA-binding and repression domains like LOS2 from A. thaliana. Bioinformatic analysis indicated that CbLOS2 had similarity with other enolase proteins. Cold acclimation assay revealed that Cblos2 expressed constitutively in C. bursa-pastoris and was involved in the cold acclimation process, implying CbLOS2 was a bi-functional enolase.

Growth hormone (GH) plays an important role in animal growth and development, and the growth hormone gene can be considered as a candidate gene for studying the weight in goats. The function of GH gene has been intensively studied in cattle and pigs, while in goats the study is still rare. In this paper 224 goats including LuBei White goat, Boer goat, hybrid generation 1 and backcross generation 1 of Boer goat and LuBei White goat were used. Two pairs of primers for 5' region of GH gene were designed according to the database of goat genomic sequence (Accession No. D00476) and polymorphisms were detected by PCR-SSCP. Homozygotes of the polymorphic fragment were cloned and sequenced. The result showed that there were five substitution mutations in the two fragments. Statistical analysis showed that in the fragment amplified by the first pair of primers, AA genotype had significant higher birth weight and weight of one year old than BB and AB genotypes in Boer goats (P<0.05). In hybrid generation 1 AA genotype also had higher birth weight and weight of one year old in significantly. While in LuBei White goats BB genotype had lower weight and the weaning weight was significant lower than the other two genotypes (P<0.05). In the fragment amplified by the second pair of primers there was no significant difference among different genotypes. From these results we can preliminarily draw the conclusion that GH gene may be a major gene or linked to the major gene to affect the weight traits and the polymorphic site could be used to select the goat weight in marker-assisted selection program.

Genetic variation of seven microsatellite loci BM1818, BM1258, BM1443, BM1905, BM302, BM4505 and CYP21 which were closely linked to somatic cell score (SCS) was analyzed in 240 Beijing Holstein cows with nondenaturing polyacrylamide gel electrophoresis. Allele frequencies, heterozygosity, polymorphic information content, the effective number of alleles of seven microsatellite loci were calculated. Relationships between seven microsatellite loci and somatic cell score in Beijing Holstein cows were primarily analyzed by least squares linear model. Least squares means of SCS for BM1818 (284 bp/284 bp), BM1258 (106 bp/92 bp), BM1443 (166 bp/160 bp), BM1905 (187 bp/187 bp), BM302 (142 bp/140 bp), BM4505 (240 bp/236 bp) and CYP21 (215 bp/198 bp) were relatively lower,and their genotypes were the most favorable genotypes in respective locus for mastitis resistance. Least squares means of SCS for BM1818 (286 bp/286 bp), BM1258 (102 bp/102 bp), BM1443 (170 bp/160 bp), BM1905 (197 bp/195 bp), BM302 (154 bp/145 bp), BM4505 (240 bp/238 bp) and CYP21 (204 bp/192 bp) were relatively higher,and their genotypes were the most unfavorable genotypes in respective locus for mastitis resistance. The information found in the present study would be very important for improving mastitis resistance in dairy cattle by marker assisted selection.

To generate 1 R deletion and translocation lines, we introduced a 2C chromosome,which was derived from Aegilops cylindrica and was known to have a gametocidal function when added monosomically into common wheat cv. Chinese Spring (CS) and its derivative, into a wheat-rye 1R chromosome disomic addition line (CS-1R"). When the individuals with chromosome constitution 21" + 1R" + 2C' (2n = 45) were selfed, the 1R chromosome structural changes were found to be induced with high frequency (24.1%) among the progenies. By using C-banding and GISH analysis, we analyzed 1R structural changes in 46 F3 individuals, which came from 23 F2 plants. The rearranged 1R chromosomes could be characterized in about 85% of the F3 individuals. This included telosome 1RL (39.1%), iso-chromosome 1 RL (2.2%), whole arm translocation involving 1RL (32.6%), telosome 1RS (4.3%), iso-chromosome 1RS (4.3%), and 1R deletion mutant with break point in the long arm (2.2%). The mutant 1R lines obtained in this study will potentially be useful in mapping the chromosome locations of agronomically important genes located in 1R. This study also demonstrated that molecular markers might be used to identify wheat chromosome arm involved in translocation with 1R.

D64B, an achromatic early mutation, was discovered from indica rice preserver line D63B. D64B were crossed with inhomogeneous sterile lines, preserver lines and restorer lines, most of their F1 shared the same heading dates as D64B. The results indicated that D64B possessed the characteristic of dominant earliness. To analyze the earliness trait, positive and negative crosses F2 and BC1 from the cross of D64B and Shuhui 527 were cultivated. Their heading dates showed double apices distributing with same apex values. According to apex vale value -103 d, plants of the F2 and BC1 were separated into early plants and late plants, which were tested with Chi2 value. The results suggested that the segregation ratio of number of early to late plant fitted to 3:1 and 1:1 for positive and negative cross F2 and BC1, respectively, and that the earliness of D64B was controlled by a single dominant major gene. To map the gene, the polymorphisms between D64B and Shuhui 527 was analyzed with reported 356 SSR primers and 59 primers showed polymorphisms. The earliness-lateness near isogenic pools, early plants and late plants from F2 of Shuhui 527 x D64B were further amplified with the 59 primers. The results indicated that there were polymorphisms on both RM279 and RM71. Their results being analyzed with MAPMAKER/EXP3.0 software, the dominant major gene was located on the top arm of rice chromosome 2 and between the two SSR markers, RM279 and RM71, with genetic distance of 12.6 cM and 13.3 cM, respectively. According to reported data, the gene was first discovered and tentatively named as Ef-3(t). In breeding practice, sterile line D64A had been bred with D64B.