基于通量塔净生态系统碳交换数据的植被物候遥感识别方法评价

选择北美洲72座通量塔观测的净生态系统碳交换（NEE）数据来计算植被物候,并以此作为参考数据,从可行性和准确性两方面对阈值法、移动平均法和函数拟合法三大类常用的植被物候遥感识别方法进行了综合评价.结果表明： 基于局部中值的阈值法对植被物候识别的可行性和准确性均最优;其次为Logistic函数拟合法中的一阶导数方法;移动平均法对植被物候识别的可行性和准确性与移动窗口的大小有关,对于16 d合成的归一化差值植被指数（NDVI）时间序列数据来说,移动窗口大小为15时能获得较优的结果;而全局阈值法对植被物候识别的可行性和准确性均最差;Logistic函数拟合法中的曲率变化率方法在识别植被物候时虽然与基于NEE数据得到的植被物候在数值上存在较大偏差,但二者之间具有较高的相关性,说明基于曲率变化率方法识别出的植被物候能较真实地反映植被物候在时空上的变化趋势.     

中国分类学文献中Swietenia mahagoni之订正

通过调查,对Swietenia mahagoni的后选模式、S.macrophylla的主模式与中国分类学文献(如《植物分类学报》、《广州植物志》、《中国高等植物图鉴》、《云南植物志》、《广东植物志》、《中国植物志》和《中国高等植物》)的S.mahagoni作比较,证实中国分类学文献将S.mahagoni和S.macrophylla相混,上述分类学文献中的S.mahagon是S.macrophylla King。桃花心木(S.mahagoni(L.)Jacq.)的羽状复叶及小叶较短,小叶长度绝不超过10 cm,果卵球形,长度绝不超过15 cm;而大叶桃花心木(S.macrophylla King)的羽状复叶及小叶较长,总有一部分小叶的长度超过10 cm,果长卵球形,长12~22 cm。     

基于CTGC试验系统下面包小麦主要品质性状的研究

 当前,全球气候变化背景下,CO2浓度升高和气候变暖可能已经并将持续对小麦（Triticum aestivum）品质产生影响。为此依据自行设计的模拟气候变化的试验装置系统 （CTGC）,研究大田条件下CO2浓度和温度增加对面包小麦主要品质性状的交互作用。 结果表明：在433.3～610.2μmol•mol-1范围内,CO2浓度增加对面包小麦的籽粒蛋白质含量、湿面筋含量和沉降值的影响不利;增温（+2 ℃多）表现为有利。当CO2浓度从433.3 mol•mol-1逐渐增加到551.5 mol•mol-1且温度增幅逐渐为+2 ℃时,CO2和温度对面包小麦的籽粒蛋白质含量、湿面筋含量和沉降值的交互作用表现为增加;而当CO2浓度增幅较大（达到610.2 mol•mol-1）,温度增幅不大（白天平均温度仅增加2℃多）时,交互作用则 表现为减少。此外,CO2浓度增加使面包小麦的醎淀粉酶活性降低,温度上升则使之提高,两因素的交互作用则表现为醎淀粉酶活性提高。     

草莓开花期发生霜害的温度

用人工霜箱对草莓(Fragaria ananassa)叶片和花托进行模拟春霜实验。结果表明草莓叶片有忍耐胞间结冰的能力, 最低叶温-6.4 ℃以上, 结冰持续90分钟以内的叶片解冻后还能存活。花托不能忍耐胞间结冰, 是通过保持过冷却状态以回避结冰伤害。花托温度越低, 发生霜害的累积百分率越大, 半开花的花托温度降到-5.4 ℃时累计有50%发生结冰而造成霜害。盛开的花及鲜重大的花发生霜害的温度较高。     

Regeneration of the secondary vascular system in poplar as a novel system to investigate gene expression by a proteomic approach

Wood formation is a complex process composing many biological events. To access its key developmental stages, we have established a regeneration system that can mimic the initiation and differentiation of cambium cells for Chinese white poplar. Anatomical studies showed that new cambium and xylem re-appeared in sequence within a few weeks after being debarked. This provides the opportunity to follow key stages of wood formation by sampling clonal trees at different regeneration times. We used this system in combination with a proteomic approach to analyze proteins expressed in different regeneration stages. PMFs for 244 proteins differentially displayed were obtained and queried against public databases. Putative functions of 199 of these proteins were assigned and classified. Regulatory genes for cell cycle progression, differentiation and cell fate were expressed in the formation of cambial tissue, while 27 genes involved in secondary wall formation were predominantly found in the xylem developing stage. This indicates that the change of gene expression pattern is corresponding to the progression of second vascular system regeneration when and where the key events of wood development occur. Further exploration of these interesting genes may provide insight into the molecular mechanisms of wood formation.     

Functional gene-mining for salt-tolerance genes with the power of Arabidopsis

Here we report on a functional gene-mining method developed to isolate stress tolerance genes without any prior knowledge of the genome or genetic mapping of the source germplasms. The feasibility of this approach was demonstrated by isolating novel salt stress tolerance genes from salt cress (Thellungiella halophila), an extremophile that is adapted to a harsh saline environment and a close relative of the model plant Arabidopsis thaliana. This gene-mining method is based on the expression of salt cress cDNA libraries in Arabidopsis. A cDNA expression library of the source germplasm, salt cress, was constructed and used to transform Arabidopsis via Agrobacterium-mediated gene transfer. A transgenic seed library consisting of >125,000 independent lines was generated and screened for salt-tolerant lines via a high-throughput genetic screen. A number of salt-tolerant lines were isolated, and the salt cress cDNAs were identified by PCR amplification and sequencing. Among the genes isolated, several novel small protein-encoding genes were discovered. The homologs of these genes in Arabidopsis have not been experimentally analyzed, and their functions remain unknown. The function of two genes isolated by this method, ST6-66 and ST225, and their Arabidopsis homologs, were investigated in Arabidopsis using gain- and loss-of-function analyses, and their importance in salt tolerance was demonstrated. Thus, our functional gene-mining method was validated by these results. Our method should be applicable for the functional mining of stress tolerance genes from various germplasms. Future improvements of the method are also discussed.     

两种变应性接触性皮炎动物模型的建立及比较

目的比较两种动物作为变应性接触性皮炎（allergic contact dermatitis,ACD）模型各自的优势,为实际应用中恰当选择动物模型提供依据。方法利用二硝基氯苯（dinitrochlorobenzene,DNCB）作为致敏剂,以腹部致敏、背部激发的方法分别建立豚鼠（连续激发4次）和小鼠（1次激发）两种ACD动物模型,并以丙酮作为对照。激发后0～96h,对激发部位进行动态分级。激发后96h,H-E染色观察激发部位皮肤病理变化,并计算脾指数和胸腺指数。结果动态评分结果显示：豚鼠激发后72h红斑程度最强,临床分级以3级为主,并于72～96h保持不变;小鼠激发后24h红斑程度最强,临床分级以4级为主,48h后红斑程度减轻。病理结果显示：两种模型激发部位皮肤内均有大量炎症细胞浸润。脾指数和胸腺指数计算结果显示：两种动物模型的脾指数和胸腺指数均较对照组明显增加（P〈0．05）。结论通过上述方法分别成功建立了豚鼠和小鼠ACD动物模型。豚鼠红斑程度较弱,且出现较晚,持续时间较长;小鼠红斑程度较强,出现较早,持续时间较短。     

锯缘青蟹主要过敏原的纯化与鉴定

以锯缘青蟹为研究对象,从免疫鉴定、分离纯化、抗体制备和免疫学分析等方面对其主要过敏原进行研究。首先利用过敏者血清的免疫印迹法,确定锯缘青蟹的主要过敏原为分子量约38kD的蛋白。然后通过制备丙酮粉、等电点沉淀、硫酸铵沉淀及加热处理对分子量为38kD的主要过敏蛋白进行了高度纯化。该蛋白的pI约为4.5,与虾的原肌球蛋白Pena1性质相近,证实了锯缘青蟹的主要过敏原为原肌球蛋白。通过免疫新西兰大白兔,制备了原肌球蛋白的抗血清,采用Protein A Sepharose亲和层析柱对动物抗体进行了纯化。该抗血清效价高,经4×105倍稀释后仍能与抗原进行反应。该抗体与甲壳类动物及软体动物的原肌球蛋白具有较强的免疫交叉反应,可用于食品过敏原检测。       

Secretory expression and characterization of the recombinant myofibril-bound serine proteinase of crucian carp (Carassius auratus) in Pichia pastoris

The myofibril-bound serine proteinase (MBSP) is effective in the degradation of myofibrillar proteins, including myosin heavy chain (MHC), α-actinin, actin, and tropomyosin and was thus regarded as an important proteinase responsible for the metabolism of fish muscle in vivo. In order to better understand the characteristic differences between native MBSP and recombinant MBSP (rMBSP) and to obtain large quantity of MBSP for its application in protein science study, the crucian carp MBSP gene was cloned (669 bp) and expressed in Pichia pastoris (P. pastoris). The recombinant P. pastoris strain was cultured in shake flasks, and 66.85 mg rMBSP/L in the fermentation supernatant was obtained. SDS-polyacrylamide gel electrophoresis (PAGE) showed a main protein band with molecular weight of approximately 36 kDa. Substrate specificity analysis revealed that the rMBSP specifically cleaved substrates at the carboxyl side of lysine residue which differed from native MBSP that cleaved substrates at the carboxyl side of arginine and lysine residues. The optimum temperature and optimum pH range of the rMBSP were 55 °C and pH 7.5, respectively. Furthermore, similar to native MBSP, the rMBSP also revealed high thermostability and pH stability and is effective in degradation of myofibrillar proteins from the skeletal muscle of crucian carp.     

Accessing the reproducibility and specificity of pepsin and other aspartic proteases

The aspartic protease pepsin is less specific than other endoproteinases. Because aspartic proteases like pepsin are active at low pH, they are utilized in hydrogen deuterium exchange mass spectrometry (HDX MS) experiments for digestion under hydrogen exchange quench conditions. We investigated the reproducibility, both qualitatively and quantitatively, of online and offline pepsin digestion to understand the compliment of reproducible pepsin fragments that can be expected during a typical pepsin digestion. The collection of reproducible peptides was identified from > 30 replicate digestions of the same protein and it was found that the number of reproducible peptides produced during pepsin digestion becomes constant above 5–6 replicate digestions. We also investigated a new aspartic protease from the stomach of the rice field eel (Monopterus albus Zuiew) and compared digestion efficiency and specificity to porcine pepsin and aspergillopepsin. Unique cleavage specificity was found for rice field eel pepsin at arginine, asparagine, and glycine. Different peptides produced by the various proteases can enhance protein sequence coverage and improve the spatial resolution of HDX MS data. This article is part of a Special Issue entitled: Mass spectrometry in structural biology.