农田-荒地边缘地带中蝗虫边缘反应分析

探讨了中华蚱蜢等10种蝗总科昆虫对农田－荒地的边缘反应。研究发现,就同一边缘而言,有些物种的多度在靠近边缘时上升,而有些物种则下降。从科的水平上分析的结果与物种水平上的分析有差异。为了更精确地了解边缘对蝗虫的分布格局的影响,从物种水平上对其进行分析是 很有必要的。     

植物对开放式CO2 浓度增高(FACE)的响应与适应研究进展

开放式CO2浓度增高(FACE)系统是近年研究植物对高CO2浓度响应和适应的新手段,它比以往密闭和半密闭系统对实验植物生长环境的干扰少.利用FACE系统进行研究更有助于正确地预测未来大气CO2浓度增高对植物的影响.该文结合作者的研究工作简要评介了FACE系统与以往密闭和半密闭式CO2浓度增高实验系统的不同之处以及近年来利用FACE系统所作的最新研究进展.     

刺激大鼠杏仁外侧核对皮层AⅠ区ON-OFF神经元反应及调谐曲线的影响

在30只氨基甲酸乙酯麻醉的SD大鼠上记录神经元单位放电,观察短纯音诱发的皮层AI区神经元ON－OFF反应的特性及电刺激杏仁外侧核（lateral amygdaloid nucleus,LA)对ON－OFF反应以及调谐曲线的影响。实验证实,AI区神经元ON－OFF反应的模式与纯音刺激的强度、频率及作用时程有关;刺激LA可以抑制ON－OFF反应的放电频数,使反应的阈值升高,或使反应放电构型发生变化;此外,刺激LA能使ON－OFF神经元的调谐曲线变窄,Q10数值增大。研究结果不仅表明ON－OFF神经元能对纯音刺激的时程、强度和频率等多种信息进行编码,而且还证明杏仁外侧核可以在皮层水平参与听觉信息的调制,削弱或衰减某些听觉信息,导致整个调谐曲线上移变窄,从而提高AI区ON－OFF神经元的频率选择性能,有利于检测外界嘈杂环境中特定的听觉信息。     

口服型HCV融合抗原DNA疫苗在小鼠诱导免疫应答

将编码一个外源信号肽、一个通用型辅助性T淋巴细胞抗原表位和HCV核心 包膜蛋白E2融合抗原基因的真核表达质粒pST CE2t(DNA疫苗 )转化到减毒鼠伤寒沙门菌SL72 0 7.将该重组菌口服接种BALB c小鼠 3次 .小鼠的抗HCV核心和E2抗体阳转率分别达 6 0 %和 70 % .体外以重组HCV核心或E2抗原刺激小鼠脾细胞 ,均使之发生明显的增殖反应 ,且小鼠脾细胞能有效杀伤表达HCV核心抗原的同系骨髓瘤细胞SP2 0 .这为研制高效免疫、成本低廉、接种方便的HCV疫苗提供了一个新的可行途径     

阿尔茨海默病核酸疫苗的构建及诱导体液免疫反应的初步研究

近年,内源性蛋白主动免疫预防和治疗阿尔茨海默病(AD)的策略成为AD研究领域的热点,并获得迅猛发展。构建了以β-片层结构的淀粉样蛋白(AB)及其可溶性与病理性突变体为抗原基因的DNA疫苗用于免疫小鼠,经过对免疫方案的探索和调整,结果能够打破其自身耐受,在外周血中诱发出较高滴度的抗-AB抗体。初步探讨了诱导体液免疫学效应的规律。并在原代培养的海马神经元AB毒性模型中验证了免疫后血清的生物学活性。     

Non-equilibrium succession dynamics indicate continued northern migration of lodgepole pine

Because species affect ecosystem functioning, understanding migration processes is a key component of predicting future ecosystem responses to climate change. This study provides evidence of range expansion under current climatic conditions of an indigenous species with strong ecosystem effects. Surveys of stands along the northern distribution limit of lodgepole pine (Pinus contorta var. latifolia) in central Yukon Territory, Canada showed consistent increases in pine dominance following fire. These patterns differed strongly from those observed at sites where pine has been present for several thousand years. Differences in species thinning rates are unlikely to account for the observed increases in pine dominance. Rates of pine regeneration at its range limits were equivalent to those of spruce, indicating a capacity for rapid local population expansion. The study also found no evidence of strong climatic limitation of pine population growth at the northern distribution limit. We interpret these data as evidence of current pine expansion at its range limits and conclude that the northern distribution of lodgepole pine is not in equilibrium with current climate. This study has implications for our ability to predict vegetation response to climate change when populations may lag in their response to climate.     

Genetic basis of ovicidal response to whitebacked planthopper (Sogatella furcifera Horváth) in rice (Oryza sativa L.)

Rice (Oryza sativa L.) ovicidal response to the whitebacked planthopper (Sogatella furcifera Horváth) is characterized by formation of watery lesions and production of an ovicidal substance benzyl benzoate, which results in high egg mortality of whitebacked planthopper. A gene with ovicidal activity to whitebacked planthopper, designated Ovc, and four ovicidal quantitative trait loci (QTLs), qOVA-1-3, qOVA-4, qOVA-5-1 and qOVA-5-2 were identified using near isogenic lines with reciprocal genetic backgrounds of a non-ovicidal Indica variety IR24 and an ovicidal Japonica variety Asominori. Ovc and the four QTLs were mapped on chromosomes 6, 1, 4, 5 and 5, respectively. Ovc is the first gene identified that kills insect eggs in plants. The Asominori allele at Ovc was essential for increasing egg mortality and responsible for production of benzyl benzoate and formation of watery lesions. The Asominori alleles at qOVA-1-3, qOVA-5-1 and qOVA-5-2 increased egg mortality in the presence of Ovc. In contrast, the Asominori allele at qOVA-4 suppressed egg mortality, indicating that qOVA-4 caused transgressive segregation for egg mortality. It was concluded that Ovc and four ovicidal QTLs accounted for the majority of the phenotypic variance for the ovicidal response to whitebacked planthopper in Asominori.     

Note: the effect of parasite infection on the innate immune response of European flounder (Platichthys flesus L.) in the southern North Sea

In a field study, infecting European flounder (Platichthys flesus L.) subclinically with different parasite species did not result in any alteration of the innate immune response. Due to the high variability in infection status and the immune parameters measured, no relationships of biological significance were found. The data indicate that copepods, as the most abundant parasites, most probably had no major influence on immune responses measured here. Thus it might be concluded that these parameters were not sensitive to parasite infections occurring under natural conditions. The immune parameters considered here are regarded as promising indicators of chemical contaminant-induced variation in piscine immune responses, which could be implemented in pollution monitoring programmes. Communicated by H. v. Westernhagen, A. Diamant     

Variable reporting and quantitative reviews: a comparison of three meta-analytical techniques

Variable reporting of results can influence quantitative reviews by limiting the number of studies for analysis, and thereby influencing both the type of analysis and the scope of the review. We performed a Monte Carlo simulation to determine statistical errors for three meta‐analytical approaches and related how such errors were affected by numbers of constituent studies. Hedges’d and effect sizes based on item response theory (IRT) had similarly improved error rates with increasing numbers of studies when there was no true effect, but IRT was conservative when there was a true effect. Log response ratio had low precision for detecting null effects as a result of overestimation of effect sizes, but high ability to detect true effects, largely irrespective of number of studies. Traditional meta‐analysis based on Hedges’d are preferred; however, quantitative reviews should use various methods in concert to improve representation and inferences from summaries of published data.     

Leptin Response to Glucocorticoid Occurs at Physiological Doses and Is Abolished by Fasting

Objective: To examine the effects of graded doses of hydrocortisone (HC) on leptin secretion, and determine the effect of fasting. Research Methods and Procedures: This was a randomized, placebo‐controlled, crossover study, with a 1‐week “washout” period between interventions. Eight healthy subjects [age = 36 ± 2.3 years (±SE), body mass index = 31.5 ± 1.6 kg/m²] completed the dose‐response study in which an intravenous infusion of saline (placebo) or HC (30 or 100 mg) was administered for 24 hours. Four healthy subjects (age = 35.2 ± 3.0 years, body mass index = 27.1 ± 2.1 kg/m²) completed the fasting study, which entailed continuous infusion of saline, HC (300 mg/24 hours) in the fed state, or HC (300 mg/24 hours) with total caloric deprivation for 24 hours. Blood sampling was performed every 1 to 2 hours for measurement of leptin, cortisol, insulin, and glucose levels. Results: Peak hyperleptinemia occurred after 16 hours of HC infusion; peak/baseline leptin levels were 129% (placebo), 140% (30 mg of HC for 24 hours, p = 0.05), and 185% (100 mg of HC for 24 hours, p < 0.01). During infusion of HC (300 mg/24 hours or placebo), the peak/baseline plasma leptin levels were 16.1 ± 5.8/12.8 ± 5.9 ng/mL (placebo with food, 126%), 14.6 ± 6.0/12.5 ± 6.5 ng/mL (HC fasting, 117%), and 32.5 ± 12.5/12.0 ± 8.4 ng/mL (HC with food, 271%, p < 0.001). Discussion: Leptin secretory responses occur at physiological doses of HC, are obliterated by fasting, and thus may be of metabolic significance.