The effect of dietary restriction on longevity,fecundity, and antioxidant responses in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Recent studies in fruit flies have imposed dietary restriction (DR) by diluting yeast and have reported increased lifespan as the yeast-to-sugar ratio decreased. In this study, the effects of DR on the lifespan of Bactrocera dorsalis were investigated using constant-feeding diets with different yeast:sugar ratios and an intermittent-feeding diet in which flies ate every sixth day. Antioxidant enzyme activities and the malondialdehyde concentration were also measured in virgin females under constant-feeding DR protocols to investigate their relationships with lifespan. The results showed that B. dorsalis lifespan was significantly extended by DR, and carbohydrate-enriched diet may be important for lifespan-extension. Female flies lived significantly longer than males at all dietary levels under both feeding regimes, indicating no interaction between diet and sex in determining lifespan. Antioxidant enzyme activities increased with the amount of yeast increased in the diets (0–4.76%) between starvation and DR treatments, indicating that the antioxidants may have influences in determining lifespan in B. dorsalis under starvation and DR treatments. However, antioxidants cannot keep up with increased oxidative damage induced by the high yeast diet (25%). These results revealed that the extension of lifespan by DR is evolutionarily conserved in B. dorsalis and that yeast:sugar ratios significantly modulate lifespan in this species.     

Notch signaling in ocular vasculature development and diseases

Ocular angiogenesis, characterized by the formation of new blood vessels in the avascular area in eyes, is a highly coordinated process involved in retinal vasculature formation and several ocular diseases such as age-related macular degeneration, proliferative diabetic retinopathy and retinopathy of prematurity. This process is orchestrated by complicated cellular interactions and vascular growth factors, during which endothelial cells acquire heterogeneous phenotypes and distinct cellular destinations. To date, while the vascular endothelial growth factor has been identified as the most critical angiogenic agent with a remarkable therapeutic value, the Notch signaling pathway appears to be a similarly important regulator in several angiogenic steps. Recent progress has highlighted the involvement, mechanisms and therapeutic potential of Notch signaling in retinal vasculature development and pathological angiogenesis-related eye disorders, which may cause irreversible blindness.     

植物的苹果酸代谢和转运

本文简要回顾了苹果酸代谢和转运的研究进展。     

关于群体遗传学一章教学改革的探讨

教学工作是培养人才的基本手段。随着社会的进步,教育理论也在不断更新。在发达国家,ＳＴＳ（ｓｃｉｅｎｃｅ－ｔｅｃｈｎｉｑｕｅ－ｓｏｃｉｅｔｙ）教育理论（即把科学、技术和社会紧密联系进来）勃然兴起。我们所做尝试,除自身专业特点所决定,就是在这一原则思想指...     

Influence of Dll4 via HIF-1α-VEGF signaling on the angiogenesis of choroidal neovascularization under hypoxic conditions

Choroidal neovascularization (CNV) is the common pathological basis of irreversible visual impairment encountered in a variety of chorioretinal diseases; the pathogenesis of its development is complicated and still imperfectly understood. Recent studies indicated that delta-like ligand 4 (Dll4), one of the Notch family ligands might participate in the HIF-1α-VEGF pathway to regulate CNV angiogenesis. But little is known about the influence and potential mechanism of Dll4/Notch signals on CNV angiogenesis. Real-time RT-PCR, Western blotting were used to analyze the expression alteration of Dll4, VEGF and HIF-1α in hypoxic RF/6A cells. Immunofluorescence staining, a laser-induced rat CNV model and intravitreal injection techniques were used to confirm the relationships among these molecules in vitro and in vivo. RPE-RF/6A cell co-culture systems were used to investigate the effects of Dll4/Notch signals on CNV angiogenesis. We found that the Dll4 was involved in hypoxia signaling in CNV angiogenesis. Results from the co-culture system showed that the enhancement of Dll4 expression in RF/6A cells led to the significantly faster proliferation and stronger tube forming ability, but inhibited cells migration and invasion across a monolayer of RPE cells in hypoxic environment, while siRNA-mediated Dll4 silencing caused the opposite effects. Pharmacological disruption of Notch signaling using gamma-secretase inhibitor (GSI) produced similar, but not identical effects, to that caused by the Dll4 siRNA. In addition, the expression of several key molecules involved in the angiogenesis of CNV was altered in RF/6A cells showing constitutively active Dll4 expression. These results suggest that Dll4 play an important role in CNV angiogenesis, which appears to be regulated by HIF-1α and VEGF during the progression of CNV under hypoxic conditions. Targeting Dll4/Notch signaling may facilitate further understanding of the mechanisms that underlie CNV angiogenesis.     

细菌素对产生菌获得生存优势及其诱导合成条件的研究进展

细菌素可以有效抑制其他细菌的生长,是产生菌获得生存优势的重要手段。细菌素使产生菌获得竞争优势基于两个方面:就产生菌自身而言,将细菌素吸附于细胞表面可能增强细胞表面疏水性,进而对定殖产生正向作用;就目标菌而言,细菌素可以自外而内抑制目标菌生物被膜、细胞壁、细胞膜的合成或破坏其结构完整性,同时还可影响其功能基因的表达。然而,伴随细菌素合成的往往是一簇基因的共同表达,需要一定的非生长相关性能量和物质消耗。因此,为实现细菌素合成的调控,细菌素表达基因的开启受制于细菌素自诱导、共培养诱导和环境因子诱导等一系列条件,以实现细菌素利用效率的最大化。根据细菌素主要的抑菌/杀菌机制,我们展望了细菌素耐受性突变菌株可能具有更强流动性细胞膜和(或)更高效小分子合成途径和(或)细菌素受体突变的特征,并提出了科学使用细菌素的建议。     

Seasonal and tissue age influences on endophytic fungi of Pinus tabulaeformis (Pinaceae) in the Dongling Mountains, Beijing

Endophytic fungi associated with Pinus tabulaeformis Carr.were investigated in the Dongling Mountains of Beijing.A total of 16200 tissue segments of P.tabulaeformis from four sample collections were processed,and 10659 fungal isolates were recovered.The overall colonization and isolation rates of endophytic fungi from high to low were spring>winter>autumn>summer and in different tissues were bark>needle>xylem,irrespective of sampling seasons.The colonization rates of endophytic fungi of needles increased with age in the four sample collections.There were no significant differences of the colonization rates of endophytic fungi among 1-,2-,and 3-year-old bark and xylem,except for significantly lower colonization rates in 1-year-old bark than in 2- and 3-year-old bark in summer.A similar trend of the isolation rates of endophytic fungi occurred.A total of 24 fungal taxa were recorded,of these five taxa Alternaria alternata,Leptostroma sp.,Pestalotiopsis besseyi,Phoma lingam,and Phomopsis archeri,were consistently isolated as the common fungi in each sample collection.Our results suggest that some fungi show a certain degree of tissue recurrence or specificity,and the composition of endophytic assemblages is not conspicuously influenced by the seasonal factor.