Acta Genetica Sinica最新文献

Mutator (Mu) is by far the most mutagenic plant transposon. The high frequency of transposition and the tendency to insert into low copy sequences for such transposon have made it the primary means by which genes are mutagenized in maize (Zea mays L.). Mus like elements (MULEs) are widespread among angiosperms and multiple-diverged functional variants can be present in a single genome. MULEs often capture genetic sequences. These Pack-MuLEs can mobilize thousands of gene fragments, which may have had a significant impact on host genome evolution. There is also evidence that MULEs can move between reproductively isolated species. Here we present an overview of the discovery, features and utility of Mu transposon. Classification of Mu elements and future directions of related research are also discussed. Understanding Mu will help us elucidate the dynamic genome.

Malate dehydrogenase (MD) is a key enzyme that plays an important role in energy metabolism. It catalyzes the oxidative decarboxylation of L-malate to yield CO₂ and pyruvate, while simultaneously generating NADPH from NADP⁺. The NADPH generated can be utilized in de novo synthesis of palmitate, which is the precursor molecule for the formation of other long-chain fatty acids. And high levels of MD will also activate muscle development. The current study was designed to investigate the effects of MD gene on growth and body-composition traits in chicken. The eighth generation population of Northeast Agricultural University broiler lines divergently selected for its abdominal fat and Northeast Agricultural University F₂ resource population were used in the research. Polymorphisms were detected by DNA sequencing and PCR-RFLP method was then developed to screen the population. A single mutation at the position of the 235 bp (Accession No. U49693) of MD 5′-flanking region was found. The correlation analysis between the polymorphism of the MD gene and growth and body composition traits was carried out using the appropriate statistic model. Least-square analysis showed that the BB genotype birds had much higher pectoralis major weight and percentage of pectoralis major than AA genotype birds (P<0.05). The abdominal fat weight, percentage of abdominal fat, the liver weight and percentage of liver weight of the AA genotype birds were much higher than those of BB genotype birds (P<0.05). These results indicate that MD gene is the major gene or is linked to the major gene that affects the growth and body composition traits in chicken.

Male Kazak sheep and Xinjiang fine wool sheep of different ages were selected to investigate the developmental changes and effect on intramuscular fat (IMF) content of heart fatty acid-binding protein (H-FABP) and peroxisome proliferator-activated receptor γ (PPARγ) mRNA expression in muscle. Longissimus dorsal muscle was sampled to measure IMF content; and total RNA was extracted to determine H-FABP and PPARγ mRNA expression levels by real-time PCR. The results showed that: (1) The IMF content increased continuously with growing and showed significant differences (P<0.05) between ages in male Kazak sheep, but no such differences (P>0.05) existed in Xinjiang fine wool sheep. Furthermore, the IMF content in Kazak sheep was very much higher (P<0.01) than that of the other breed from day 30 to 90; (2) H-FABP mRNA expression level was the highest on day 2 and showed significant differences (P<0.05) between ages in male Kazak sheep as well as in Xinjiang fine wool sheep. In the former breed, the expression reached the lowest point at day 30, and then rose continuously. But in the latter breed, it declined continuously from day 2 to 90, and then increased; (3) Significant differences (P<0.05) of PPARγ mRNA expression between ages occurred in both breeds. In male Kazak sheep, PPARγ mRNA expression declined from day 2 to 90, while in the other breed it increased continuously from day 2 to 60, but reached the lowest level at day 90, then increased; (4) In male Kazak sheep, the mRNA expression level of H-FABP was highly positively correlated (r=0.737, P<0.01) with IMF content from day 30 to 90, but that of PPARγ was highly negatively correlated (r=−0.835, P<0.01) with IMF content from day 2 to 90.

Catechol-O-methyl transferase (COMT) plays an important role in the metabolism of neurotransmitters. Two alleles of the COMT gene as a result of a G/A transition in the exon 4 can lead to different COMT enzymatic activities. Much genetic research has revealed that this COMT functional polymorphism was related to human psychiatric disorders. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods were used to discern the relationships among the functional polymorphism of COMT, mental retardation (MR), and general cognitive ability of children. The results of the case-control analysis showed that there was no association between the frequencies of genotypes of COMT and MR (x²=0.776, P>0.05) or between the frequency of COMT alleles and MR (x²=0.335, P>0.05). COMT polymorphism was found in children whose intelligence quotient (IQ) was above 55. In normal children (IQ≥85), the frequencies of high-activity allele COMT^H and the homozygote genotype COMT^HH were 60.98% and 79.28%, respectively. Both were higher than those of the borderline group (46.67% and 70.67%, 0.10 > P>0.05). Therefore, the result of this study suggests that this functional polymorphism is not an important risk factor for MR, but the COMT^HH genotype may have a positive effect on cognitive performance in normal children in the Qinba area.

Four flowering related traits, spikelet number per panicle (SNP), percentage of single exserted stigma (PSES), dual exserted stigma (PDES) and total exserted stigma (PES) of a RI population with 185 lines under water stress and non-stress conditions for 2 years, were investigated in a drought tolerance screening facility. ANOVA results showed high significance between years, lines, and water stress treatments, together with interactions among them in pairs. Highest phenotypic correlation was found between PSES and PES (r = 0.9752^***), followed by PDES and PES (r = 0.7150^***), and PSES and PDES (r = 0.5424^***). Based on a linkage map of 203 SSR markers, six main effect QTLs were detected for SNP and three or four main effect QTLs were associated with PSES, PDES and PES under stress or non-stress conditions. There were one to nine pairs of epistatic QTLs influencing SNP and stigma exsertion. The contribution rates of additive and epistatic effects seemed to be in a low magnitude for most cases (0.76%–9.92%) while a few QTLs or QTL pairs explained more than 10% of total variance. Some main effect QTL and epistasis were commonly detected among PSES, PDES and PES, explaining the high positive correlation between them. Few QTLs were detected under both water stress and non-stress condition, implying that drought had severe impact on the genetic behaviors of both spikelet number and stigma exsertion.

By using genome in situ hybridization (GISH) on root somatic chromosomes of allotetraploid derived from the cross Gossypium arboreum × G. bickii with genomic DNA (gDNA) of G. bickii as a probe, two sets of chromosomes, consisting of 26 chromosomes each, were easily distinguished from each other by their distinctive hybridization signals. GISH analysis directly proved that the hybrid GarboreumxG. bickii is an allotetraploid amphiploid. The karyotype formula of the species was 2n = 4x = 52 = 46m (4sat) + 6sm (4sat). We identified four pairs of satellites with two pairs in each sub-genome. FISH analysis using 45S rDNA as a probe showed that the cross G. arboreumxG. bickii contained 14 NORs. At least five pairs of chromosomes in the G sub-genome showed double hybridization (red and blue) in their long arms, which indicates that chromatin introgression from the A sub-genome had occurred.

Reciprocal crosses between red and achromatic rice revealed that the seed color of F₁ was determined by its female parent. According to the seed color and plant segregation ratio of F₁, F₂, and F₃ generations, the red phenotype of red double-haploid seed was determined by a dominant, monogene with maternal effect. Histological study showed that the red pigments accumulated in the pericarp layer only. The assay of developmental timing of pigment accumulation showed that the red color accumulated from desiccation stage to perfectly maturation stage of the seeds.

H-FABP (Heart fatty acid-binding protein), a member of FABP family, plays an essential role in long-chain fatty acid uptake and metabolic homeostasis. Its role in pig intramuscular fat content remains poorly understood, especially in local pig breeds in western China. In this study, the genetic variations of 5′-upstream region and the second intron in porcine H-FABP gene were investigated by PCR-RFLP in 256 pigs including Duroc, Large White, Landrace, Neijiang, Rongchang, Bamei pig, Hanjiang Black, Hanzhong White, and the wild ones. The effect of H-FABP gene on the IMF content was analyzed by the least square method. Lipid droplet morphology and content in adipocytes cultured from pigs with different H-FABP genotypes, were studied by oil red O staining and a triglyceride assay kit. Results showed a Hinf I -RFLP in these eight pig breeds and wild pigs, among which Large white, Bamei pig, Hanjiang Black, Hanzhong White, and wild pigs presented with low polymorphism while the other breeds had intermediate polymorphism. There was no Hae III or Msp I -RFLPs in the four Chinese local pig breeds tested, but Duroc, Landrace, Large White, Hanzhong White and wild pig had polymorphism. Landrace, Large White and wild pigs had low levels of Hae III-and Msp I -RFLP, whereas others had intermediate polymorphism. H-FABP genotypes significantly affected the IMF content (P<0.05). The IMF content ordered by H-FABP genotypes were HH>Hh>hh, DD<Dd<dd, and AA<Aa<aa. The genetic effect values were 3.89, 3.42, 3.17, 2.27, 2.49, 2.91, 2.28, 2.70, and 2.95, respectively. Fat deposition in adipocytes was stronger in the HH, dd and aa genotypes than in others. The results suggest that porcine meat quality may be improved by increasing the frequency of genotype aa-dd-HH in pig breeds.

QTL underlying related traits at the late developmental stage under two different nitrogen levels were investigated in rice using a population of chromosome segment substitution lines (CSSL) derived from a cross between Teqing and Lemont. A total of 31 QTLs referring 5 traits, that is, plant height (PH), panicle number per plant (PN), chlorophyll content (CC), shoot dry weight (SDW) and grain yield per plant (YD), were detected. Under normal N level, 3 QTLs were detected for each trait, while under low N level, 5,4, 5 and 2 QTLs were detected for PH, PN, CC and SDW respectively. Most of the QTLs were located on chromosome 2, 3, 7, 11 and 12. QTLs controlling different traits or the same trait under different N levels were mapped on the same or adjacent intervals, forming several clusters in rice chromosomes. More than two traits were controlled by QTLs on one of four intervals (RM30-RM439, RM18-RM478, RM309-RM270, and RM235-RM17), suggesting that there were some pleiotropic effects. It was supposed that some QTLs only detected at low N level might be associated with the ability to tolerate the low N stress in rice.

Methotrexate(MTX) is one of the most important and frequently used drugs in cancer therapy, but the efficacy of this drug is often compromised by the development of resistance in cancer cells. To seek and identify differentially expressed proteins related to MTX resistance and provide clues for the mechanism of MTX resistance, proteins from cell line MTX300 (resistant to 300 μmol/L MTX) and its control cell line 3T3R500 were separated by two-dimensional electrophoresis (2-DE). The colloidal Coomassie brilliant blue-stained 2-DE gels were subjected to image analysis, which revealed several spots with high levels of differential expression between MTX300 and 3T3R500. The protein spot with highest differential expression was submitted for tryptic peptide mass fingerprinting(PMF) for identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). MS analysis and database searches revealed it to be dihydrofolate reductase (DHFR), which was subsequently confirmed by Western blot. The result suggested that DHFR might play an important role in the MTX resistance.