干旱胁迫诱导下植物基因的表达与调控

干旱胁迫能够诱导植物表达大量的基因 ,研究这些基因的表达与调控 ,为植物抗旱的定向育种创造条件。本文系统介绍了在干旱胁迫条件下 ,植物体内渗透调节物质和可溶性糖合成有关的基因、离子和水分通道及Lea蛋白基因的表达 ,以及与这些基因表达相关的调控元件和因子 ,干旱胁迫信号转导等方面的最新研究进展。     

Comparative chloroplast genomes of <Emphasis Type="Italic">Paris</Emphasis> Sect. <Emphasis Type="Italic">Marmorata</Emphasis>: insights into repeat regions and evolutionary implications

Background

Species of Paris Sect. Marmorata are valuable medicinal plants to synthesize steroidal saponins with effective pharmacological therapy. However, the wild resources of the species are threatened by plundering exploitation before the molecular genetics studies uncover the genomes and evolutionary significance. Thus, the availability of complete chloroplast genome sequences of Sect. Marmorata is necessary and crucial to the understanding the plastome evolution of this section and facilitating future population genetics studies. Here, we determined chloroplast genomes of Sect. Marmorata, and conducted the whole chloroplast genome comparison.

Results

This study presented detailed sequences and structural variations of chloroplast genomes of Sect. Marmorata. Over 40 large repeats and approximately 130 simple sequence repeats as well as a group of genomic hotspots were detected. Inverted repeat contraction of this section was inferred via comparing the chloroplast genomes with the one of P. verticillata. Additionally, almost all the plastid protein coding genes were found to prefer ending with A/U. Mutation bias and selection pressure predominately shaped the codon bias of most genes. And most of the genes underwent purifying selection, whereas photosynthetic genes experienced a relatively relaxed purifying selection.

Conclusions

Repeat sequences and hotspot regions can be scanned to detect the intraspecific and interspecific variability, and selected to infer the phylogenetic relationships of Sect. Marmorata and other species in subgenus Daiswa. Mutation and natural selection were the main forces to drive the codon bias pattern of most plastid protein coding genes. Therefore, this study enhances the understanding about evolution of Sect. Marmorata from the chloroplast genome, and provide genomic insights into genetic analyses of Sect. Marmorata.

     

Rapid start-up and performance of denitrifying granular sludge in an upflow sludge blanket (USB) reactor treating high concentration nitrite wastewater

Denitrifying granular sludge reactor holds better nitrogen removal efficiency than other kinds of denitrifying reactors, while this reactor commonly needs seeding anaerobic granular sludge and longer period for start-up in practice, which restricted the application of denitrifying granular sludge reactor. This study presented a rapid and stable start-up method for denitrifying granular sludge. An upflow sludge blanket (USB) reactor with packings was established with flocculent activated sludge for treatment of high concentration nitrite wastewater. Results showed mature denitrifying granular sludge appeared only after 15 days with highest nitrogen removal rate of 5.844 kg N/(m³ day), which was much higher than that of compared anoxic sequencing batch reactor (ASBR). No significant nitrite inhibition occurred in USB and denitrification performance was mainly influenced by hydraulic retention time, influent C/N ratio and internal reflux ratio. Hydraulic shear force created by upflow fluid, shearing of gaseous products and stable microorganisms adhesion on the packings might be the reasons for rapid achievement of granular sludge. Compared to inoculated sludge and ASBR, remarkable microbial communitiy variations were detected in USB. The dominance of Proteobacteria and Bacteroidetes and enrichment of species Pseudomonas_stutzeri should be responsible for the excellent denitrification performance, which further verified the feasibility of start-up method.     

金蛇王营养液对老龄鼠细胞因子产生的影响

本文报导了金蛇王营养液（ＧＫＳ）对老龄鼠细胞因子产生的影响。实验表明,细胞因子分泌功能下降的老龄鼠饲喂金蛇王营养液后,ＩＬ－２和ＩＦＮ－ｒ水平明显增加。进而证明金蛇王营养液是一种良好的免疫增强剂,能增强老龄机体抗肿瘤、抗感染等作用     

Studies on the Genetic Model of Nitrogen Uptake by Maize Plants at Their Seedling Stage

1IntroductionThenitIOgenuptakebymaiZeplantsd~onthegeneticCharaCteristicsofwhettesUnderthecendnenvironmentcondition.AsanimPOratstageofrnabe,seedlingstagehasthehighestrateofnitrogenuptaketothedriedmatt.['J.InOrdertOprovidethetheoriticalbasisforplanningarationalschemeofbreeding,itisne~tostUdythegeneticangelofnit~nuptakebymaizeplantsattheirablingstage.2MaterialandMethodIn1994,11inbredswerechOSenastheParentstoprepucethe~of41geno~whichincludedthe6femaleparents,5maleparentSand3ocrewaccordingt…     

Flavonoids of <Emphasis Type="Italic">Rosa roxburghii</Emphasis> Tratt exhibit radioprotection and anti-apoptosis properties via the Bcl-2(Ca<Superscript>2+</Superscript>)/Caspase-3/PARP-1 pathway

The objective of our study was to assess the radioprotective effect of flavonoids extracted from Rosa roxburghii Tratt (FRT) and investigate the role of Bcl-2(Ca²⁺)/Caspase-3/PARP-1 pathway in radiation-induced apoptosis. Cells and mice were exposed to ⁶⁰Co γ-rays at a dose of 6 Gy. The radiation treatment induced significant effects on tissue pathological changes, apoptosis, Ca²⁺, ROS, DNA damage, and expression levels of Bcl-2, Caspase-3 (C-Caspase-3), and PARP-1. The results showed that FRT acted as an antioxidant, reduced DNA damage, corrected the pathological changes of the tissue induced by radiation, promoted the formation of spleen nodules, resisted sperm aberration, and protected the thymus. FRT significantly reduced cell apoptosis compared with the irradiation group. The expression of Ca²⁺ and C-Caspase-3 was decreased after FRT treatment compared with the radiation-treated group. At the same time, expression of prototype PARP-1 and Bcl-2 increased, leading to a decrease in the percentage of apoptosis cells in FRT treatment groups. We conclude that FRT acts as a radioprotector. Apoptosis signals were activated via the Bcl-2(Ca²⁺)/Caspase-3/PARP-1 pathway in irradiated cells and FRT inhibited this pathway of apoptosis by down-regulation of C-Caspase-3 and Ca²⁺ and up-regulation of prototype PARP-1 and Bcl-2.     

High‐altitude adaptation in vertebrates as revealed by mitochondrial genome analyses

The high‐altitude environment may drive vertebrate evolution in a certain way, and vertebrates living in different altitude environments might have different energy requirements. We hypothesized that the high‐altitude environment might impose different influences on vertebrate mitochondrial genomes (mtDNA). We used selection pressure analyses and PIC (phylogenetic independent contrasts) analysis to detect the evolutionary rate of vertebrate mtDNA protein‐coding genes (PCGs) from different altitudes. The results showed that the ratio of nonsynonymous/synonymous substitutions (dN/dS) in the mtDNA PCGs was significantly higher in high‐altitude vertebrates than in low‐altitude vertebrates. The seven rapidly evolving genes were shared by the high‐altitude vertebrates, and only one positive selection gene (ND5 gene) was detected in the high‐altitude vertebrates. Our results suggest the mtDNA evolutionary rate in high‐altitude vertebrates was higher than in low‐altitude vertebrates as their evolution requires more energy in a high‐altitude environment. Our study demonstrates the high‐altitude environment (low atmospheric O₂ levels) drives vertebrate evolution in mtDNA PCGs.