Hox genes from the parasitic flatworm Schistosoma japonicum

Hox genes are characterized by a highly conserved peptide domain and contribute to antero-posterior axis patterning during embryogenesis. These genes have been widely studied in a variety of animal species due to their central role in evolutionary developmental biology. Based on the published genome assembly and unpublished re-sequencing project data, we present the first genome-wide characterization and comparative genomic analysis of the Hox gene family within Schistosoma japonicum. Eight Hox genes were identified and validated in our investigation. Phylogenetic analysis revealed that these genes are distributed among seven orthology groups of the Hox gene family. Our study further suggested that differences in the Lox5 gene copy number existed between the two closely related species, S. japonicum and Schistosoma mansoni. Semi-quantitative real-time polymerase chain reaction experiments revealed that Lox5 and Hox4 gene expression was high in the schistosomulum stage, and all four genes investigated showed highest expression within the eggs.     

Expression of organophosphorus hydrolase OPHC2 in Pichia pastoris: purification and characterization

Organophosphorus hydrolase is able to hydrolyze phosphoester bonds and reduce the toxicity of organophosphorus compounds. In this work, recombinant organophosphorus hydrolase OPHC2 was successfully produced by Pichia pastoris at a high expression level (approximately 5.5 g/L) using 3 L high-cell-density fermentation. The expression level is higher than those produced in other expression systems. The results of the SDS-PAGE and the Western blot analyses showed a major 36 kDa polypeptide band, which was the same size as that from the original bacteria, Pseudomonas pseudoalcaligenes C2-1. The expressed enzyme was recovered from the culture supernatant and purified by a single-step purification procedure with a recovery rate of 72.78%. The main physiochemical features of the recombinant OPHC2, including its optimum temperature and pH for the reaction, its temperature and pH stability, and its sensitivity to some metal ions and chemical reagents, were also characterized. With methyl parathion as a substrate, the optimum temperature and pH for enzyme activity are 65 degrees C and pH 9.0, respectively. It also shows good thermal and pH stability.     

放牧对草地生态系统服务和功能权衡关系的影响

内蒙古草原是我国北方的重要生态屏障和绿色畜牧业基地, 放牧是草原生态系统的主要利用和管理方式, 在放牧管理中充分发挥生态系统某一项或几项服务和功能最大利用价值时, 往往会与其他服务(功能)发生冲突, 需要权衡多项生态系统服务和功能, 制定合理的放牧管理制度。该研究以内蒙古锡林郭勒典型草原为例, 通过设置不放牧、轻度放牧、中度放牧以及重度放牧的放牧梯度, 从多项生态系统服务和功能权衡的角度比较了最适放牧管理强度。结果显示, 在放牧管理的草地生态系统服务和功能的权衡中, 权衡、协同、不相关关系同时存在, 如土壤呼吸速率与植物群落净生长量、生物多样性与植物群落净光合速率表现为权衡关系, 植物群落净生长量分别与土壤含水量、植物群落净光合速率及草地蒸散速率存在协同关系, 土壤有机碳含量与其他服务或功能间呈不相关关系; 放牧能不同程度地削弱多项生态系统服务及功能间的权衡关系(冲突对立关系); 中度放牧条件下的多项生态系统服务及功能的协同性最佳。     

Pepsinogens and pepsins from Japanese seabass (Lateolabrax japonicus)

Three pepsinogens (PG1, PG2, PG3) were highly purified from the stomach of Japanese seabass (Lateolabrax japonicus) by ammonium sulfate fractionation, DEAE-Sephacel anion exchange column chromatography and Sephacryl S-200 gel-filtration. Two dimensional polyacrylamide gel electrophoresis (2D-PAGE) analysis revealed that the molecular masses of the three PGs were 35, 37, and 34kDa, and their isoelectric points were 5.3, 5.1, and 4.7, respectively. Zymography analysis showed that the three pepsinogens had different mobilities and enzymatic activities under native conditions. Pepsinogens converted into their active form pepsins under pH 2.0 by one-step pathway or stepwise pathway. All three pepsins were completely inhibited by pepstatin A, a typical aspartic proteinase inhibitor. The N-terminal amino acid sequences of the three pepsinogens were determined to the 30th, 30th and 28th amino acid residue and those of their corresponding active form pepsins were also determined to the 19th, 18th and 20th amino acid residue, respectively. All amino acid sequences of Japanese seabass PGs revealed high identities to reported fish and mammalian pepsinogens. The effective digestion of fish and shrimp muscular proteins by pepsins indicated their physiological function in the degradation of food proteins.     

Roles of carbohydrate supply and ethylene, polyamines in maize kernel set

Glucose appears to have an antagonistic relationship with ethylene and ethylene and polyamines appear to play antagonistic roles in the abortion of seeds and fruits. Moreover, ethylene, spermidine, and spermine share a common biosynthetic precursor. The synchronous changes of them and the relationships with kernel set are currently unclear. Here, we stimulated maize (Zea mays L.) apical kernel set and studied their changes at 4, 8, 12, and 16 d after pollination (DAP). The status of the apical kernels changed from abortion to set, showing a pattern similar to that of the middle kernels, with slow decrease in glucose and rapid decline in ethylene production, and a sharp increase in spermidine and spermine after four DAP. Synchronous changes in ethylene and spermidine were also observed. However, the ethylene production decreased slowly in the aborted apical kernels, the glucose and polyamines concentrations were lower. Ethephon application did not block the change from abortion to set for the setting apical kernels. These data indicate that the developmental change may be accompanied by an inhibition of adequate glucose to ethylene synthesis and subsequent promotion of spermidine and spermine synthesis, and adequate carbohydrate supply may play a key role in the developmental process.     

生化工程双语教学改革探索

“生化工程”是高等院校生物工程专业的一门重要的专业课。为了与国际生物技术的快速发展接轨, 目前我国高校“生化工程”普遍采用双语教学模式。主要从教学方式、教学内容、实验环节及考试方式等方面分析了生化工程双语教学中存在的问题, 提出了一系列改革措施, 为取得良好教学效果进行了探讨。     

Efficient production, purification, and application of egg yolk antibodies against human HLA-A*0201 heavy chain and light chain (beta2m)

The importance of eggs as a source of specific antibodies is well recognized. Egg yolk contains 8--20mg immunoglobulins (IgY) per milliliter. However, the major problem in separating IgY is to remove the high concentrations of lipids in egg yolk. We first used water dilution method to get the supernatant containing IgY, then purified the antibody by caprylic acid-ammonium sulfate method, and obtained specific antibody with satisfactory purity and activity. By comparison of these several methods, each has its advantages, one can be chosen to purify IgY according to practical need. The purified IgY produced by the immunized chickens can stain the human peripheral blood mononuclear cell effectively when labeled with fluorescent FITC.     

High production of xanthan gum by a glycerol-tolerant strain Xanthomonas campestris WXLB-006

The superior properties of xanthan gum make it an industrial aginomoto used in many industries, especially in oil recovery. In the present work, xanthan production from glycerol by a mutant strain Xanthomonas campestris WXLB-006 reached as high as 17.8?g/L in flask culture. With the adoption of pH control, varied aeration and agitation, and varied glycerol feeding strategy, xanthan production reached 33.9?g/L in a 7-L fermenter and fermentation time decreased to 60?hr. Instead of difficultly and costly purifying glycerol, this research provides a very good case for glycerol utilization. At the same time, this is the first report on a high glycerol-tolerant strain for microbial polysaccharide production and 33.9?g/L is the highest production of xanthan gum produced from glycerol so far.