Responses to selection on genotypic or phenotypic values in the presence of genes with major effects

Summary Average genotypic responses were compared after selection for genotypic values and for phenotypic values on the basis of single-gene models and multigene models in simulated livestock populations. Single-gene models dealt with single gene control of the genetic differences between animals, while multigene models considered a collection of genes with various magnitudes of effects on a trait. In each case, selection lasted through discrete generations until the fixation of the gene frequencies occurred. Generations to reach fixation were used to compare various models, and the two criteria for selection, for their efficiency in selection. Implications of using these models versus using infinitesimal models for selection in practice are presented.     

The Interactive Effects of Transgenically Overexpressed 1Ax1 with Various HMW-GS Combinations on Dough Quality by Introgression of Exogenous Subunits into an Elite Chinese Wheat Variety

Seed storage proteins in wheat endosperm, particularly high-molecular-weight glutenin subunits (HMW-GS), are primary determinants of dough properties, and affect both end-use quality and grain utilization of wheat (Triticum aestivum L). In order to investigate the interactive effects between the transgenically overexpressed 1Ax1 subunit with different HMW-GS on dough quality traits, we developed a set of 8 introgression lines (ILs) overexpressing the transgenic HMW-glutenin subunit 1Ax1 by introgression of this transgene from transgenic line B102-1-2/1 into an elite Chinese wheat variety Chuanmai107 (C107), using conventional crossing and backcrossing breeding technique. The donor C107 strain lacks 1Ax1 but contains the HMW-GS pairs 1Dx2+1Dy12 and 1Bx7+1By9. The resultant ILs showed robust and stable expression of 1Ax1 even after five generations of self-pollination, and crossing/backcrossing three times. In addition, overexpression of 1Ax1 was compensated by the endogenous gluten proteins. All ILs exhibited superior agronomic performance when compared to the transgenic parent line, B102-1-2/1. Mixograph results demonstrated that overexpressed 1Ax1 significantly improved dough strength, resistance to extension and over-mixing tolerance, in the targeted wheat cultivar C107. Further, comparisons among the ILs showed the interactive effects of endogenous subunits on dough properties when 1Ax1 was overexpressed: subunit pair 17+18 contributed to increased over-mixing tolerance of the dough; expression of the Glu-D1 allele maintained an appropriate balance between x-type and y-type subunits and thereby improved dough quality. It is consistent with ILs C4 (HMW-GS are 1, 17+18, 2+12) had the highest gluten index and Zeleny sedimentation value. This study demonstrates that wheat quality could be improved by using transgenic wheat overexpressing HMW-GS and the feasibility of using such transgenic lines in wheat quality breeding programs.     

Combinatorial analysis of enzymatic bottlenecks of <Emphasis Type="SmallCaps">l</Emphasis>-tyrosine pathway by <Emphasis Type="Italic">p</Emphasis>-coumaric acid production in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Objective

To identify new enzymatic bottlenecks of l-tyrosine pathway for further improving the production of l-tyrosine and its derivatives.

Result

When ARO4 and ARO7 were deregulated by their feedback resistant derivatives in the host strains, the ARO2 and TYR1 genes, coding for chorismate synthase and prephenate dehydrogenase were further identified as new important rate-limiting steps. The yield of p-coumaric acid in the feedback-resistant strain overexpressing ARO2 or TYR1, was significantly increased from 6.4 to 16.2 and 15.3 mg l^?1, respectively. Subsequently, we improved the strain by combinatorial engineering of pathway genes increasing the yield of p-coumaric acid by 12.5-fold (from 1.7 to 21.3 mg l^?1) compared with the wild-type strain. Batch cultivations revealed that p-coumaric acid production was correlated with cell growth, and the formation of by-product acetate of the best producer NK-M6 increased to 31.1 mM whereas only 19.1 mM acetate was accumulated by the wild-type strain.

Conclusion

Combinatorial metabolic engineering provides a new strategy for further improvement of l-tyrosine or other metabolic biosynthesis pathways in S. cerevisiae.

     

Genome-Wide Analysis of the Apple (Malus domestica) Cysteine-Rich Receptor-Like Kinase (CRK) Family: Annotation,Genomic Organization,and Expression Profiles in Response to Fungal Infection

Plant Molecular Biology Reporter - Cysteine-rich receptor-like kinases (CRKs) took crucial roles in plant cell growth and development, as well as environmental adaption. Apple (Malus domestica) had...     

杏仁核点燃模型癫痫样放电传播途径研究

目的 :探讨杏仁核点燃模型癫痫样放电的传播途径。方法 :选择健康Wistar大鼠 3 0只以电刺激杏仁核的方式制作杏仁核点燃癫痫模型 ,于右侧杏仁核、左侧海马及右侧额叶皮质埋植电极记录脑电活动 ,观察电刺激杏仁核时在杏仁核、海马及额叶皮质出现癫痫样放电的潜伏期、最低刺激强度及癫痫样放电的持续时间。结果 :杏仁核出现癫痫样放电时 ,海马及皮质均未记录到癫痫样放电。而当杏仁核、海马及皮质三处出现癫痫样放电时的最低刺激强度依次增大 ,潜伏期依次延长 ,海马处癫痫样放电的持续时间最长。结论 :杏仁核点燃模型癫痫样放电可能由杏仁核经海马传至皮层 ,海马可能为癫痫样放电传播的重要结构     

多聚半乳糖醛酸内切酶的固定化及其性质研究

棉花枯萎病菌多聚半乳糖醛酸内切酶在pH大于7时不稳定,故对它进行多种化学修饰而又不影响其活性,必须在pHd小于7的体系中进行。本文报道将PGAUase在还原剂存在下,与稀酸处理的Sepharose 4B交联,获得较高活力的固定化酶。固定化酶催化动力学表明,最适pH为4,4,最适温度为55℃,在pH1至8.0范围内稳定。和溶液酶比较,对热稳定性提高,但对碱稳定性下降。以多聚半乳糖醛酸为底物,Km为0.27mmol/L,Vmax为66.67nmol/L·min,均大于溶液酶(Km=0.07mmol/L,Vmax=28.00nmol/L·min)。在pH4.8,30℃,聚半乳糖醛酸在固相酶的柱中循环水解不同的时间降解产物经圆盘电泳和等电聚焦测定,得到不同大小的寡糖片段混合物,证明固相酶和溶液酶的作用方式相同,同时使以酶解法制备一定大小的有生物活性的寡糖分子成为可能。     

NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract

Background

We have previously reported that low concentrations of cigarette smoke extract induce DNA damage without leading to apoptosis or necrosis in human bronchial epithelial cells (HBECs), and that IL-6/STAT3 signaling contributes to the cell survival. Since NF-κB is also involved in regulating apoptosis and cell survival, the current study was designed to investigate the role of NF-κB in mediating cell survival in response to cigarette smoke exposure in HBECs.

Methods

Both the pharmacologic inhibitor of NF-κB, curcumin, and RNA interference targeting p65 were used to block NF-κB signaling in HBECs. Apoptosis and cell survival were then assessed by various methods including COMET assay, LIVE/DEAD Cytotoxicity/Viability assay and colony formation assay.

Results

Cigarette smoke extract (CSE) caused DNA damage and cell cycle arrest in S phase without leading to apoptosis in HBECs as evidenced by TUNEL assay, COMET assay and DNA content assay. CSE stimulated NF-κB -DNA binding activity and up-regulated Bcl-XL protein in HBECs. Inhibition of NF-κB by the pharmacologic inhibitor curcumin (20 μM) or suppression of p65 by siRNA resulted in a significant increase in cell death in response to cigarette smoke exposure. Furthermore, cells lacking p65 were incapable of forming cellular colonies when these cells were exposed to CSE, while they behaved normally in the regular culture medium.

Conclusion

The current study demonstrates that CSE activates NF-κB and up-regulates Bcl-XL through NF-kB activation in HBECs, and that CSE induces cell death in cells lacking p65. These results suggest that activation of NF-κB regulates cell survival following DNA damage by cigarette smoke in human bronchial epithelial cells.     

Bacterial diversity in the rumen of Gayals (<Emphasis Type="Italic">Bos frontalis</Emphasis>), Swamp buffaloes (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>) and Holstein cow as revealed by cloned 16S rRNA gene sequences

Libraries of rumen bacterial 16S rRNA gene sequences of Gayals (Bos frontalis) and Swamp buffaloes (Bubalus bubalis) were cloned and sequenced in the present work to compare the bacterial diversity with the third published library of Holstein cow. Sequence similarity of 97% was used as the definition of operational taxonomic unit (OTU). The majority of the 470 sequences retrieved fell into the phyla of low G + C subdivision (329 sequences) and Cytophaga–Flexibacter–Bacteroides (CFB, 123 sequences) with the percentages of 70 and 26.2, respectively. The remaining clones belonged to the phyla of Proteobacter, high G + C gram positive bacteria (HGCGPB) and Spirochaetes, accounting for 3.8% totally. Only 73 clones (25 OTUs, 15.5%) could be closely related to cultured representatives. However, a larger fraction was related to uncultured representatives. Holstein cow may have more representatives of cultural bacteria and there were more uncultured clones for Gayals. The percentage of cultural representatives was 24, 13.3 and 9.5 for Holstein cow, Swamp buffaloes and Gayals, respectively. Twenty-three OTUs of the 236 ones appeared in more than one library, five of which were cultural. Selenomonas ruminantium, Ruminococcus flavefaciens and Butyrivibrio fibrisolvens were found in two different libraries, while Succiniclasticum ruminis and Pseudobutyrivibrio ruminis were found in all three libraries. Some of the animal-specific bacteria that had not been described previously in the ruminal ecosystem, e.g. Allisonella histaminiformans for Gayals and Staphylococcus sciuri for Swamp buffaloes were also recovered.     

Yeast mRNA cap methyltransferase is a 50-kilodalton protein encoded by an essential gene.

RNA (guanine-7-)methyltransferase, the enzyme responsible for methylating the 5' cap structure of eukaryotic mRNA, was isolated from extracts of Saccharomyces cerevisiae. The yeast enzyme catalyzed methyl group transfer from S-adenosyl-L-methionine to the guanosine base of capped, unmethylated poly(A). Cap methylation was stimulated by low concentrations of salt and was inhibited by S-adenosyl-L-homocysteine, a presumptive product of the reaction, but not by S-adenosyl-D-homocysteine. The methyltransferase sedimented in a glycerol gradient as a single discrete component of 3.2S. A likely candidate for the gene encoding yeast cap methyltransferase was singled out on phylogenetic grounds. The ABD1 gene, located on yeast chromosome II, encodes a 436-amino-acid (50-kDa) polypeptide that displays regional similarity to the catalytic domain of the vaccinia virus cap methyltransferase. That the ABD1 gene product is indeed RNA (guanine-7-)methyltransferase was established by expressing the ABD1 protein in bacteria, purifying the protein to homogeneity, and characterizing the cap methyltransferase activity intrinsic to recombinant ABD1. The physical and biochemical properties of recombinant ABD1 methyltransferase were indistinguishable from those of the cap methyltransferase isolated and partially purified from whole-cell yeast extracts. Our finding that the ABD1 gene is required for yeast growth provides the first genetic evidence that a cap methyltransferase (and, by inference, the cap methyl group) plays an essential role in cellular function in vivo.