重组人MASP2蛋白在大肠杆菌中的表达和纯化

目的:获得酶原形式的重组人甘露聚糖结合凝集素相关丝氨酸蛋白酶2(MASP2)。方法:在大肠杆菌中诱导表达重组人MASP2全长蛋白,包涵体裂解后,经复性、透析、浓缩、考马斯亮蓝染色、SDS-PAGE及Western印迹,鉴定纯化结果及酶活性。结果:复性后的MASP2蛋白经考马斯亮蓝染色未见杂带。自激活实验表明,当MASP2浓度在1μmool/L以下时,无论在4℃还是37℃,都能较稳定地保持酶原形式;蛋白浓度为3.5μmool/L时只能在4℃保持稳定,37℃发生自激活;蛋白浓度达到12μmool/L后,在4℃时已不能稳定存在。结论:获得了较纯的重组人MASP2蛋白,且具有自激活活性。     

Origin and spread of the glucose-6-phosphate dehydrogenase variant (G6PD-Mediterranean) in the Middle East.

A common glucose-6-phosphate dehydrogenase (G6PD) variant characterized by severe enzyme deficiency and B-like electrophoretic mobility is called "G6PD-Mediterranean" because it is found in different populations around the Mediterranean Sea. Sequence analysis of Italian subjects has revealed that the molecular basis of G6PD-Mediterranean is a single C-T transition at nucleotide position 563, causing a serine phenylalanine replacement at amino acid position 188. Most G6PD-Mediterranean subjects also have a silent C-T transition (without amino acid replacement) at nucleotide position 1311. Twenty-one unrelated individuals from Saudi Arabia, Iraq, Iran, Jordan, Lebanon, and Israel with both severe G6PD deficiency and B-like electrophoretic mobility were tested for both mutations by using amplification followed by digestion with appropriate restriction enzymes. All but one had the 563 mutation, and, of these, all but one had the 1311 mutation. Another 24 unrelated Middle Eastern individuals with normal G6PD activity or not known to be G6PD deficient were similarly tested. Four had the silent mutation at position 1311 in the absence of the deficiency mutation at position 563. We conclude that (1) the large majority of Middle Eastern subjects with the G6PD-Mediterranean phenotype have the same mutation found in Italy, (2) the silent mutation is an independent polymorphism in the Middle East, with a frequency of about .13, and (3) the mutation leading to the G6PD-Mediterranean deficiency has probably arisen on a chromosome that already carried the silent mutation.     

Prevalence of keds on city dogs in central Poland

The aim of this study was to identify the species of ked infesting dogs in the cities of central Poland. A total of 510 dogs were observed between June and September 2015. The presence of keds was noted in 182 (35.7%) animals. Keds were more prevalent in female (38.0%) than in male (33.2%) dogs, and were more frequently found in animals younger than 1 year (46.2%) and in long‐haired dogs (36.6%). The body areas most heavily colonized by keds were the groin (35.4%) and neck (21.4%). A total of 904 keds were isolated from dogs, including Hippobosca equina (Diptera: Hippoboscidae) (17.2%), Lipoptena cervi (Diptera: Hippoboscidae) (32.0%), and two species not previously encountered in Poland: Hippobosca longipennis (45.0%) and Lipoptena fortisetosa (5.9%). Hippoboscidae may act as vectors of pathogens and any shifts in their geographic range may lead to the spread of new diseases affecting animals.     

脂多糖通过补体途径诱导小鼠产生白三烯B4

目的:研究脂多糖(LPS)对人血清中补体系统的激活及在小鼠模型中诱导产生白三烯B4(LTB4)。方法:LPS包被ELISA板,利用血清中补体C4、C3沉积实验检测补体成分被LPS活化的情况,通过尾静脉注射小鼠LPS后不同时间点ELISA定量检测LTB4,评价补体系统的活化和炎症因子的产生。结果与结论:血清系统ELISA检测发现LPS可以激活补体系统,且以凝集素途径为主;动物实验中LTB4被LPS诱导后1～3 h达到峰值,之后回落。C1INH对血清补体活化和动物模型中LTB4的产生均有显著抑制。     

Effects of umbilical cord blood stem cells on healing factors for diabetic foot injuries

The use of stem or progenitor cells from bone marrow, or peripheral or umbilical cord blood is becoming more common for treatment of diabetic foot problems. These cells promote neovascularization by angiogenic factors and they promote epithelium formation by stimulating cell replication and migration under certain pathological conditions. We investigated the role of CD34 + stem cells from human umbilical cord blood in wound healing using a rat model. Rats were randomly divided into a control group and two groups with diabetes induced by a single dose of 55 mg/kg intraperitoneal streptozocin. Scarred areas 5 mm in diameter were created on the feet of all rats. The diabetic rats constituted the diabetes control group and a diabetes + stem cell group with local injection into the wound site of 0.5 × 106 CD34 + stem cells from human umbilical cord blood. The newly formed skin in the foot wounds following CD34 + stem cell treatment showed significantly improvement by immunohistochemistry and TUNEL staining, and were closer to the wound healing of the control group than the untreated diabetic animals. The increase in FGF expression that accompanied the local injection of CD34 + stem cells indicates that FGF stimulation helped prevent apoptosis. Our findings suggest a promising new treatment approach to diabetic wound healing.     

Effects of strobilurin containing fungicides on the deoxynivalenol content in winter wheat

The effects of the strobilurin fungicides Juwel, Juwel Top and Amistar on the deoxynivalenol contamination of winter wheat was studied in field experiments. In general, the application of strobilurins during stem elongation and inflorescence emergence of wheat resulted in increased deoxynivalenol contents in kernels as compared with the untreated control. This stimulating effect can be reversed by a following azole fungicide applied within a time period of one week during the stages of flowering.     

An overview of models of stomatal conductance at the leaf level

Stomata play a key role in plant adaptation to changing environmental conditions as they control both water losses and CO₂ uptake. Particularly, in the context of global change, simulations of the consequences of drought on crop plants are needed to design more efficient and water‐saving cropping systems. However, most of the models of stomatal conductance (g_s) developed at the leaf level link g_s to environmental factors or net photosynthesis (A_net), but do not include satisfactorily the effects of drought, impairing our capacity to simulate plant functioning in conditions of limited water supply. The objective of this review was to draw an up‐to‐date picture of the g_s models, from the empirical to the process‐based ones, along with their mechanistic or deterministic bases. It focuses on models capable to account for multiple environmental influences with emphasis on drought conditions. We examine how models that have been proposed for well‐watered conditions can be combined with those specifically designed to deal with drought conditions. Ideas for future improvements of g_s models are discussed: the issue of co‐regulation of g_s and A_net; the roles of CO₂, absissic acid and H₂O₂; and finally, how to better address the new challenges arising from the issue of global change.     

Slipped-strand mispairing: a major mechanism for DNA sequence evolution

Simple repetitive DNA sequences are a widespread and abundant feature of genomic DNA. The following several features characterize such sequences: (1) they typically consist of a variety of repeated motifs of 1-10 bases--but may include much larger repeats as well; (2) larger repeat units often include shorter ones within them; (3) long polypyrimidine and poly-CA tracts are often found; and (4) tandem arrangements of closely related motifs are often found. We propose that slipped-strand mispairing events, in concert with unequal crossing- over, can readily account for all of these features. The frequent occurrence of long tandem repeats of particular motifs (polypyrimidine and poly-CA tracts) appears to result from nonrandom patterns of nucleotide substitution. We argue that the intrahelical process of slipped-strand mispairing is much more likely to be the major factor in the initial expansion of short repeated motifs and that, after initial expansion, simple tandem repeats may be predisposed to further expansion by unequal crossing-over or other interhelical events because of their propensity to mispair. Evidence is presented that single-base repeats (the shortest possible motifs) are represented by longer runs in mammalian introns than would be expected on a random basis, supporting the idea that SSM may be a ubiquitous force in the evolution of the eukaryotic genome. Simple repetitive sequences may therefore represent a natural ground state of DNA unselected for coding functions.