米曲霉（Aspergillus oryzae）果胶酸内切水解酶（PGA）在原核系统中重组表达

果胶酶具有广阔的商业用途,在食品工业上主要用于果汁和酒类的澄清、提高植物油的提取率、提高水果的硬度和植物纤维脱胶。米曲霉（Aspergillus oryzae）一直用于传统发酵食品的生产,自然条件下其果胶酶的产量较低。文献报道的果胶酶的重组表达成功的例子较少,且活性较低。通过RT-PCR 的方法,获得不含信号肽的果胶酸内切水解酶A(polygalacturonase A, PGA) 的cDNA,PGA cDNA 连入pET-28a (+)载体, 构建 pET-28a (+)-pga 质粒。pET-28a (+)-pga 转化Turner (DE3) placⅠ细胞,得到转化子pET-28a (+)-pga-Turner (DE3) placⅠ,首次实现了米曲霉PGA在大肠杆菌系统中过表达,进一步对PGA在大肠杆菌系统中表达的条件进行了研究。在37℃、220 r/min条件培养pET-28a (+)-pga-Turner (DE3) placⅠ细胞,OD₆₀₀至 0.8左右时,用500μmol/L isopropyl β-D-thiogalactogalactopyranoside (IPTG)进行诱导表达,在15℃和170r/min条件下继续培养24 h,表达效果最好,相对于每毫升培养基而言,产酶可达到70u/mL,是米曲霉自然条件产酶量的87.5倍,远优于文献报道的重组表达的PGA酶活     

Spontaneous modulation of a dynamic balance between bacterial genomic stability and mutability: roles and molecular mechanisms of the genetic switch

Bacteria need a high degree of genetic stability to maintain their species identities over long evolutionary times while retaining some mutability to adapt to the changing environment.It is a long unanswered question that how bacteria reconcile these seemingly contradictory biological properties.We hypothesized that certain mechanisms must maintain a dynamic balance between genetic stability and mutability for the survival and evolution of bacterial species.To identify such mechanisms,we analyzed bacterial genomes,focusing on the Salmonella mismatch repair(MMR)system.We found that the MMR gene mutL functions as a genetic switch through a slipped-strand mispairing mechanism,modulating and maintaining a dynamic balance between genetic stability and mutability during bacterial evolution.This mechanism allows bacteria to maintain their phylogenetic status,while also adapting to changing environments by acquiring novel traits.In this review,we outline the history of research into this genetic switch,from its discovery to the latest findings,and discuss its potential roles in the genomic evolution of bacteria.     

Paracrine signaling in stem cell renewal and in neoplastic tumor growth

Paracrine pathway activities are being increasingly recognized as instrumental regulatory mechanisms of epithelial-stromal interactions that play important roles in physiological and pathological self-renewal of stem cells and in the initiation and maintenance of neoplastic tumor development.Stromal-specific Hedgehog(Hh)responses and epithelial-associated Wnt pathway activities have been recently appreciated as important factors in stem cell self-renewal and carcinogenesis.Furthermore,Hh and Wnt pathways frequently crosstalk with each other to regulate the growth of epithelial cells in a context-dependent manner.Because small molecule modulators of Hh and Wnt pathway activities are readily available,emerging roles of Hh-Wnt pathway crosstalk in epithelial-stromal interactions will shed light on the development of regenerative and anti-cancer medicines.     

Phylogenetic Relationships of the Genus Paramesotriton （Caudata： Salamandridae） with the Description of a New Species from Qixiling Nature Reserve,Jiangxi, Southeastern China and a Key to the species

The matrilineal genealogy of the genus Paramesotriton is hypothesized based on DNA sequences from mitochondrial NADH subunit two （ND2） and its flanking tRNAs （tRN^Arp and a partial tRNA^Ala）. The genealogy identifies a highly divergent, unnamed lineage from Qixiling Nature Reserve, Jiangxi, China and places it as the sister taxon of P. chinensis. The newly discovered population differs from other congeners by several features of external morphology including having large clusters of dark brown conical warts on the dorsum of the head, lateral surface of the body and dorsolateral ridges. Its intermittent dorsal vertebral ridge is the same color as other parts of the dorsum and tail narrows gradually from the base to the tip. Further, the new population differs from all congeners by an uncorrected P-distance of more than 9.38% in ND2. Consequently, we describe the new species of Asian warty newt （Salamandridae） as Paramesotriton qixilingensis sp. nov.     

Description of a New Species of the Genus Brachytarsophrys Tian and Hu, 1983 （Amphibia： Anura： Megophryidae） from Southern China Based on Molecular and Morphological Data

A new species, Brachytarsophrys popei sp. nov., is described based on a series of specimens collected from Mount Jinggang, Jiangxi Province, Taoyuandong Nature Reserve, Hunan Province and Nanling Nature Reserve, Guangdong Province, China. The new species can be easily distinguished from other known congeners by morphology, morphometrics and molecular data of the mitochondrial 16S rRNA gene. It is characterized by its relatively small size with 86.2 mm in snout-vent length in adult female and 70.7 mm-83.5 mm in males; vomerine teeth bearing on two markedly elevated ridges, which projecting behind far beyond the posterior level of the choanae, widely separated by a distance nearly 1.5 times length of one; margin of tongue de~ply notched behind; toes about one-third to two-thirds webbed in males, at most one-third webbed in female; the webs extending as a wide fringes along either side of toes; upper eyelid with tubercles, one of which is enlarged and becoming a remarkably prominent, bluntly conical light- yellow horn; black tiny nuptial spines on the dorsal surface of the first finger and second finger base, single vocal sac in males; gravid females bear pure yellowish oocytes; tadpoles with a transverse white stripe on ventral surface and two longitudinal white stripes along the sides of body. The new species represents the fifth known Brachytarsophrys species.     

Gene expression profile favoring phenotypic reversion: a clue for mechanism of tumor suppression by NF-IL6 3'UTR

Transfection of cDNA in 3'untranslated region of human nuclear factor for interleukin-6 (NF-IL6 3'UTR) induced tumor suppression in a human hepatoma cell line. cDNA array analysis was used to reveal changes in gene expression profile leading to tumor suppression The results indicate that this suppression was not due to activation of dsRNA-dependent protein kinase, nor to inactivation of oncogenes; rather, all the changes in expression of known genes, induced by NF-IL6 3'UTR cDNA may be ascribed to the suppression of cellular malignancy. Therefore, our results imply that this 3'untranslated region may have played role of a regulator of gene expression profile.     

Impact of insect-resistant transgenic rice on target insect pests and non-target arthropods in China

Progress on the research and development of insect-resistant transgenic rice, especially expressing insecticidal proteins from Bacillus thuringiensis （Bt）, in China has been rapid in recent years. A number of insect-resistant transgenic rice lines/varieties have passed restricted and enlarged field testing, and several have been approved for productive testing since 2002 in China, although none was approved for commercial use until 2006. Extensive laboratory and field trials have been conducted for evaluation of the efficiency of transgenic rice on target lepidoteran pests and potential ecological risks on non-target arthropods. The efficacy of a number of transgenic rice lines currently tested in China was excellent for control of the major target insect pests, the rice stem borers （Chilo suppressalis, Scirpophaga incertulas, Sesamia inferens） and leaffolder （ Cnaphalocrocis medinalis）, and was better than most insecticides extensively used by millions of farmers at present in China. No significantly negative or unintended effects of transgenic rice on non-target arthropods were found compared with non-transgenic rice. In contrast, most of the current insecticides used for the control of rice stem borers and leaffolders proved harmful to natural enemies, and some insecticides may directly induce resurgence of rice planthoppers. Studies for developing a proactive insect resistance management of transgenic rice in the future are discussed to ensure the sustainable use of transgenic rice.     

Temporal expression of c-kit in spermatogenesis of two grasshopper species

Two species of grasshoppers, Calliptamus abbreviatus （Ikonn.） and Shirakiacris shirakii （I. Bol.）, were collected randomly in the Siping area of Jilin Province, China. By using immunohistochemical methods and statistical analysis, we observed and compared the temporal expression of c-kit protein in four representative stages of spermatogenesis of the two grasshoppers, namely： spermatogonia; primary spermatocyte; secondary spermatocyte; and mature sperm. Results showed that there was c-kit positive temporal expression at each stage of spermatogenesis, but there were different positive expression levels： （i） weak positive expression of c-kit protein appeared in spermatogonia and the positive granules were thinner; （ii） strong positive expression of c-kit protein existed in primary spermatocyte and positive granules became biggest among all developmental stages; （iii） c-kit positive expression stayed stronger in secondary spermatocyte while positive granules became thinner; （iv） there was a strong positive expression of c-kit and thinner positive granules in mature sperm, which distributed on head and tail; （v） the biggest c-kit positive granules had been found massing at the end of spermary; and （vi） significant differences of c-kit positive expression existed in spermatogenesis between two species of grasshoppers. The results indicated that c-kit protein may play a crucial role in spermatogenesis and even retain the physiological action of sperms and fertilization in grasshoppers.     

云南苗族EAP、ADA和AK1的分布及其基因频率

DistributionandGeneFrequcnciesofEAP,ADAandAK1intheMiaoEthnicGroupofYunnan,ChinaouJiongwenShenBinZhouLangpingZhaoLipingZhaoYonghe(DepartmentofForensicMedicine,KunmingMedicalCollege,Kunming650031)我们对居住于云南的苗族人红细胞EAP、ADA和AK1的分布进行了调查。138例苗族人血样采自云南省屏边苗族自治县民族小学的学生,各取措梢血少许,涂于干净纱布上自然晾干,制成血痕样品,低温干燥保存。按文献[3]所述方法对样品进行EAP－AK1同步电泳分型检测,对所得数据进行统计处理。本次调查所检测的EAP、ADA…     

QTL mapping of economically important traits in Silkworm (Bombyx mori)

The construction of linkage map is both a funda-mental research area and an important aspect of gene analyses in genetics. It provides the guidelines for breeding. A sound linkage map is also necessary for further genetic analysis. In recent years, great and rapid progress has been made in molecular biology, which enables fingerprinting of organisms at the ge-nomic level. Many molecular marker techniques have been well established. Heartening progress has been made in many organisms in the co…