真菌传杆状病毒组（Furovirus）内四种病毒的细胞病理学比较研究

本文研究丁真菌传杆状病毒组（Ｆｕｒｏｖｉｒｕｓ）四个病毒成员,即甜菜坏死黄脉病毒（ＢＮＹＶＶ）、甜菜土传病毒（ＢＳＢＶ）、花生丛生病毒印度株系（ＰＣＡ－Ｉ）以及非洲株系（ＰＣＡ－Ａ）和小麦土传花叶病毒（ＳＢＷＭＶ）所引起的细胞病理变化。这四种病毒在病毒粒子聚集的结构,是否引起细胞膜聚集及聚集的结构,过氧化物酶体泡状物的形成与否及结构均有差异。另外,同一种病毒的不同株系或分离物所引起的细胞病理变化也不相同。     

Efficient expression and purification of recombinant alcohol oxidase in Pichia pastoris

In order to improve the production of alcohol oxidase (AOX), a recombinant Pichia pastoris (P. pastoris) system was constructed by transformation of the plasmid pPIC9K-AOX into P. pastoris GS115. The effects of different expression conditions on alcohol oxidase activity in the culture supernatant were investigated in the shake flask scale. The results showed that the highest extracellular activity (562 U/L) of alcohol oxidase was obtained after 56 h induction with 4% methanol at OD₆₀₀ 1.0 in the medium containing 50 g/L maltose, which is about 4.2 folds higher than previously reported. High-purity functional recombinant AOX (>90%) was purified from the culture with the Ni-NTA affinity column and Sephadex G-100 chromatographical methods, with a total recovery rate of 68.9%. Further studies showed that the purified rAOX had similar enzymatic characteristics as the native enzyme, except that the thermal stability and resistance to H₂O₂ inhibition of rAOX were significantly greater compared to the previous report. The purified rAOX was well tolerant to various water-miscible organic solvents. This efficient expression and purification process will be promising for large-scale production of rAOX as an important diagnostic enzyme for alcohol detection in many areas.     

紫花苜蓿赤霉素受体基因的克隆及表达分析

赤霉素受体(GID)是赤霉素信号转导途径的重要成员,直接影响着赤霉素对植物体效应的发挥。该研究利用同源克隆的方法,首次从紫花苜蓿中克隆得到1个赤霉素受体基因,命名为MsGID1b。序列分析发现,MsGID1b基因开放阅读框长度为1 053bp,编码350个氨基酸,推测其蛋白质分子量为39.839kD,是一个无信号肽和跨膜结构的亲水性蛋白。序列比对结果表明,MsGID1b基因与蒺藜苜蓿MtGID1b基因的核苷酸序列相似性为98%,氨基酸序列相似性为99%,且具有HSL家族典型的HGG和GXSXG保守结构域及GA、DELLA蛋白结合位点。荧光定量PCR分析表明,MsGID1b基因在紫花苜蓿各组织中的表达丰度依次为:根盛花初花茎叶荚果;经GA3、ABA、NaCl、PEG和黑暗诱导后该基因表达上调,尤其是在GA3诱导下,MsGID1b基因的表达量一直维持在较高水平,表明MsGID1b基因可能参与紫花苜蓿的抗逆调控。     

蕉类的细胞遗传学研究

本文对芭蕉属正蕉组内的一些有代表性的野生种和包括香蕉,大蕉在内的二倍体和三倍体食用栽培蕉,共１８个材料进行了核型比较分析,对其中５个重要的栽培蕉品种的花粉母细胞减数分裂进行了观察,从核型、染色体配对以及染色体 特殊分离行为等３个方面得到的证据表明,并非所有香蕉才同源三倍体,有一些香蕉品种的３个染色体组之间同源程度很低, 通过对一些特征染色体的分析,推测这种香蕉的单染色体组很可能来自ＢＢ野生蕉、大蕉     

A PagP fusion protein system for the expression of intrinsically disordered proteins in Escherichia coli

PagP, a beta-barrel membrane protein found in Gram-negative bacteria, expresses robustly in inclusion bodies when its signal sequence is removed. We have developed a new fusion protein expression system based on PagP and demonstrated its utility in the expression of the unstructured N-terminal region of human cardiac troponin I (residues 1-71). A yield of 100mg fusion protein per liter M9 minimal media was obtained. The troponin I fragment was removed from PagP using cyanogen bromide cleavage at methionine residues followed by nickel affinity chromatography. We further demonstrate that optimal cleavage requires complete reduction of methionine residues prior to cyanogen bromide treatment, and this is effectively accomplished using potassium iodide under acidic conditions. The PagP-based fusion protein system is more effective at targeting proteins into inclusion bodies than a commercially available system that uses ketosteroid isomerase; it thus represents an important advance for producing large quantities of unfolded peptides or proteins in Escherichia coli.     

Century-Scale Responses of Ecosystem Carbon Storage and Flux to Multiple Environmental Changes in the Southern United States

Terrestrial ecosystems in the southern United States (SUS) have experienced a complex set of changes in climate, atmospheric CO₂ concentration, tropospheric ozone (O₃), nitrogen (N) deposition, and land-use and land-cover change (LULCC) during the past century. Although each of these factors has received attention for its alterations on ecosystem carbon (C) dynamics, their combined effects and relative contributions are still not well understood. By using the Dynamic Land Ecosystem Model (DLEM) in combination with spatially explicit, long-term historical data series on multiple environmental factors, we examined the century-scale responses of ecosystem C storage and flux to multiple environmental changes in the SUS. The results indicated that multiple environmental changes shifted SUS ecosystems from a C source of 1.20?±?0.56?Pg (1?Pg?=?10¹⁵?g) during the period 1895 to 1950, to a C sink of 2.00?±?0.94?Pg during the period 1951 to 2007. Over the entire period spanning 1895–2007, SUS ecosystems were a net C sink of 0.80?±?0.38?Pg. The C sink was primarily due to an increase in the vegetation C pool, whereas the soil C pool decreased during the study period. The spatiotemporal changes of C storage were caused by changes in multiple environmental factors. Among the five factors examined (climate, LULCC, N deposition, atmospheric CO₂, and tropospheric O₃), elevated atmospheric CO₂ concentration was the largest contributor to C sequestration, followed by N deposition. LULCC, climate, and tropospheric O₃ concentration contributed to C losses during the study period. The SUS ecosystem C sink was largely the result of interactive effects among multiple environmental factors, particularly atmospheric N input and atmospheric CO_2.     

Molecular characterization of avian-like H1N1 swine influenza a viruses isolated in Eastern China, 2011

Currently, three predominant subtypes of influenza virus are prevalent in pig populations worldwide: H1N1, H3N2, and H1N2. European avian-like H1N1 viruses, which were initially detected in European pig populations in 1979, have been circulating in pigs in eastern China since 2007. In this study, six influenza A viruses were isolated from 60 swine lung samples collected from January to April 2011 in eastern China. Based on whole genome sequencing, molecular characteristics of two isolates were determined. Phylogenetic analysis showed the eight genes of the two isolates were closely related to those of the avian-like H1N1 viruses circulating in pig populations, especially similar to those found in China. Four potential glycosylation sites were observed at positions 13, 26, 198, 277 in the HA1 proteins of the two isolates. Due to the presence of a stop codon at codon 12, the isolates contained truncated PB1-F2 proteins. In this study, the isolates contained 591Q, 627E and 701N in the polymerase subunit PB2, which had been shown to be determinants of virulence and host adaptation. The isolates also had a D rather than E at position 92 of the NS1, a marker of mammalian adaptation. Both isolates contained the GPKV motif at the PDZ ligand domain of the 3′ end of the NS1, a characteristic marker of the European avian-like swine viruses since about 1999, which is distinct from those of avian, human and classical swine viruses. The M2 proteins of the isolates have the mutation (S31N), a characteristic marker of the European avian-like swine viruses since about 1987, which may confer resistance to amantadine and rimantadine antivirals. Our findings further emphasize the importance of surveillance on the genetic diversity of influenza A viruses in pigs, and raise more concerns about the occurrence of cross-species transmission events.     

Biochar’s effect on crop productivity and the dependence on experimental conditions—a meta-analysis of literature data

Background and aims

For the last decade, there has been an increasing global interest in using biochar to mitigate climate change by storing carbon in soil. However, there is a lack of detailed knowledge on the impact of biochar on the crop productivity in different agricultural systems. The objective of this study was to quantify the effect of biochar soil amendment (BSA) on crop productivity and to analyze the dependence of responses on experimental conditions.

Methods

A weighted meta-analysis was conducted based on data from 103 studies published up to April, 2013. The effect of BSA on crop productivity was quantified by characterizing experimental conditions.

Results

In the published experiments, with biochar amendment rates generally <30 t ha^?1, BSA increased crop productivity by 11.0 % on average, while the responses varied with experimental conditions. Greater responses were found in pot experiments than in field, in acid than in neutral soils, in sandy textured than in loam and silt soils. Crop response in field experiments was greater for dry land crops (10.6 % on average) than for paddy rice (5.6 % on average). This result, associated with the higher response in acid and sandy textured soils, suggests both a liming and an aggregating/moistening effect of BSA.

Conclusions

The analysis suggests a promising role for BSA in improving crop productivity especially for dry land crops, and in acid, poor-structured soils though there was wide variation with soil, crop and biochar properties. Long-term field studies are needed to elucidate the persistence of BSA’s effect and the mechanisms for improving crop production in a wide range of agricultural conditions. At current prices and C-trading schemes, however, BSA would not be cost-effective unless persistent soil improvement and crop response can be demonstrated.     

大树蛙与斑腿树蛙的繁殖与驯养

1997～2000年,在广州动物园生态蛙蟾馆观察与研究了笼养条件下大树蛙和斑腿树蛙的繁殖行为和驯养过程,比较了两种树蛙繁殖生态的差别。     

施肥对盆栽香樟幼苗不同根序细根养分的影响

以盆栽的1年生香樟实生苗为研究对象,采用指数施肥的方式,测定1~5级细根的C、N、P、K含量,并探讨施肥对香樟幼苗细根养分浓度的影响。结果表明:(1)不同根序细根的全C浓度差异不显著,施肥对细根全C浓度影响不显著(P0.05);(2)在所有根序中,N、P浓度最高的是1级根,但其K浓度却最低;N、P含量最低的是5级根;(3)细根的N、P含量随着根序的增加呈显著的下降趋势(P0.05);(4)施N肥能显著增加1~2级细根的N含量,施P肥能显著增加1级根的P含量,N+P肥较之P肥更能提高1级根对P的吸收;(5)C∶N∶P受根序的影响非常明显,1级根平均为366∶16∶1,5级根则为807∶12∶1,而且C∶N∶P随着根序增加而显著升高,但N∶P无显著影响;(6)虽然施肥对细根C含量无影响,但施N肥或N+P肥对1~2级细根中N的含量有显著性增加。综合分析可知,处理9对香樟苗期养分浓度指标影响最为显著,即施肥量为氮素4g·株-1、磷素4g·株-1、钾素2g·株-1时,对香樟幼苗细根的生长发育有较好地促进作用。研究结果可为香樟的速生丰产及资源的高效利用提供理论依据。