不同低温胁迫下粳稻耐冷种质的孕穗期耐冷性比较

为粳稻孕穗期耐冷标准品种的建立和耐冷遗传育种研究提供优异基因资源,利用人工低温气候室,采用15℃、17℃、19℃3种胁迫温度,4d和6d两种胁迫时间,3×2交互式设计的方法,对来自黑龙江、吉林、辽宁和云南的12份粳稻种质进行了孕穗期耐冷性强度的研究。结果表明,随着低温胁迫的增强,各水稻品种的平均空壳率都随之增加;在15℃/6d胁迫下,供试品种平均空壳率的方差和变异系数达到最大,该胁迫强度可被选用于孕穗期强耐冷种质的筛选。依据15℃/6d胁迫下供试品种平均空壳率的方差分析及多重比较结果,空育131和龙稻3号具有极强的孕穗期耐冷性。不同地区可根据参试品种在本试验中的耐冷表现,并结合当地水稻种植区的光温条件选择相应的耐冷标准品种。     

北京夏植黄瓜内生真菌区系研究

为了解黄瓜植株内生真菌的区系组成及其变化,从而为进一步研究黄瓜内生真菌的生态和功能奠定基础,对采自北京延庆的不同品种和不同生育期的40株黄瓜进行了内生真菌的分离培养。经形态学鉴定和18S rDNA序列分析,分离到的1,024株内生真菌属于18属,其中Exserohilum和Neocosmospora尚未见内生真菌的报道。Alternaria、Aspergillus、Chaetomium、Cladosporium和Fusarium在各生育期和各器官普遍存在。其中,Alternaria在叶中的定殖率达47.0%,远高于在其他器官中的定殖率;Fusarium在根中的定殖率达32.5%,远高于在其他器官中的定殖率。多数真菌类群表现出不同程度的器官偏好性,有些真菌类群则只出现在特定器官中。叶和根的内生真菌类群数量和总定殖率均高于茎和果实。随着黄瓜的生长,各器官内生真菌的类群数在增加,部分真菌的定殖率也呈上升趋势,但Neocosmospora和Chaetomium在各器官中的定殖率则随植株生长呈下降趋势。     

L-FABP is a critical host factor for successful malaria liver stage development

The malaria parasite liver stage produces tens of thousands of red cell-infectious forms within its host hepatocyte. It is thought that the vacuole-enclosed parasite completely depends on the host cell for successful development but the molecular parasite-host cell interactions underlying this remarkable growth have remained elusive. Using a yeast two-hybrid screen and a yeast overexpression system we show that UIS3, a parasite protein essential for liver stage development, interacts directly with liver-fatty acid binding protein, L-FABP. Down-regulation of L-FABP expression in hepatocytes severely impairs parasite growth and overexpression of L-FABP promotes growth. This is the first identified direct liver stage-host cell protein interaction, providing a possible explanation for the importance of UIS3 in liver infection.     

Human disturbance and environmental factors as drivers of long‐term post‐fire regeneration patterns in Mediterranean forests

Question: What are the main forces driving natural regeneration in burned mature Mediterranean forests in the medium‐long term and what are the likely successional trajectories of unmanaged vegetation? Location: Valencia Region, eastern Spain. Methods: A wildfire burned 33 000 ha of Pinus halepensis and P. pinaster forest in 1979, and subsequent smaller wildfires took place between 1984 and 1996. The study was designed to sample the range of environmental and disturbance (fire recurrence and land use) conditions. The territory was classified into 17 different geomorphological and fire‐recurrence units. Vegetation cover and floristic composition were measured on a total of 113 plots (1000 m² each) randomly selected within these units. Results: The results show that 23 years after the fire the regenerated vegetation consists of successional shrublands, and that forest ecosystem resilience can be very low. The vegetation presents a strong correlation with most of the environmental variables, but fire (one or two fires), soil type and land use (in that order) are the main drivers of vegetation composition. Quercus coccifera shrublands persist on limestone soils while diverse types of other shrublands (dominated by seeder species) are found on marl soils. Conclusions: The results of this study indicate that disturbance factors strongly coupled to human activities, such as land use and fire, play a critical role in the current state of vegetation. Fire creates vegetation patches in different successional states while land use and soil type define the different types of shrubland in terms of their specific composition.     

Functional implications of caspase-mediated RhoGDI2 processing during apoptosis of HL60 and K562 leukemia cells

RhoGDI2, a cytosolic regulator of Rho GTPase, is cleaved during apoptosis in a caspase-3 dependent fashion. By using 2D-gel electrophoresis, mass spectrometry and Western blotting we investigate in this paper the functional consequences of RhoGDI2 processing. We can show that loss of the N-terminal 19 amino acids results in a shift of the isoelectric point of the truncated RhoGDI2 (NΔ19) to a more basic value due to the removal of 9 acidic amino acids from the N-terminus, which may be responsible for enhanced retention of the N-terminally truncated protein within the nuclear compartment. Fusion of the p53 nuclear export signaling sequence MFRELNEALELK to NΔ19 (NΔ19NES) abolished its apoptosis promoting properties, while overexpression of NΔ19 significantly increased the susceptibility to apoptosis induction by the proteasome inhibitor PSI and by staurosporine. These results suggest that cleavage of RhoGDI2 by caspase-3 is not a functionally irrelevant bystander effect of caspase activation during apoptosis, but rather expedites progression of the apoptotic process.     

Spatiotemporal localization of germ plasm RNAs during zebrafish oogenesis

In zebrafish, primordial germ cells (PGCs) are determined by a specialized maternal cytoplasm, the germ plasm, which forms at the distal ends of the cleavage furrows in 4-cell embryos. The germ plasm includes maternal mRNAs from the germline-specific genes such as vasa and nanos1, and vegetally localized dazl RNA is also incorporated into the germ plasm. However, little is known about the distributions and assembly mechanisms of germ plasm components, especially during oogenesis. Here we report that the germ plasm RNAs vasa, nanos1, and dazl co-localize with the mitochondrial cloud (MC) and are transported to the vegetal cortex during early oogenesis. We found that a mitochondrial cloud localization element (MCLE) previously identified in the 3' untranslated region (3'UTR) of Xenopus Xcat2 gene can direct RNA localization to the vegetal cortex via the MC in zebrafish oocytes. In addition, the RNA-binding protein Hermes is a component of the MC in zebrafish oocytes, as is the case in Xenopus. Moreover, we provide evidence that the dazl 3'UTR possesses at least three types of cis-acting elements that direct multiple steps in the localization process: MC localization, anchorage at the vegetal cortex, and localization at the cleavage furrows. Taken together, the data show that the MC functions as a conserved feature that participates in transport of the germ plasm RNAs in Xenopus and zebrafish oocytes. Furthermore, we propose that the germ plasm components are assembled in a stepwise and spatiotemporally-regulated manner during oogenesis and early embryogenesis in zebrafish.     

Sources of Nitrogen in Combination with Systems of Irrigation Influence the Productivity of Modern Rice (<i>Oryza sativa</i> L.) Cultivars during Dry Season in Sub-Tropical Environment

In irrigated agricultural systems, nitrogen (N) and water are the vital resources for sustainability of the crop production in the modern era of climate change. The current study aimed to assess the impact of water and N management on the productivity of irrigated rice cultivars. In the context, a field observation was done at the research farm of Bangladesh Agricultural University, Mymensingh, during dry seasons in consecutive two years (2018–2019 and 2019–2020). The experiments were set up following split-plot design assigning water management in the main plots, nitrogen management in the sub-plots, and the cultivars were approved in the split-split plot with three replications. After two years observation, it was revealed that rice cultivar Binadhan-8 gave the maximum value of leaf area index, number effective tillers hill^-1 and grains panicle^-1 which lead to the higher grain yield (GY). Substantial relationships were observed among the concentration of N, growth, total dry matter (TDM) and N content, N uptake, N utilization effectiveness, and GY. However, with little exception, the Combined effect of water and N, cultivars and water management were varied significantly for all parameters. Finally, the results of the current study concluded that application of irrigation at 8 days after the disappearance of ponded water and source of 105 kg N ha^-1 from PU + Poultry manure are the best management approach for the excellent performance of rice cultivar Binadhan-8.     

不同饵料对匙吻鲟仔鱼生长发育和消化酶活性的影响

本文研究了不同强化饵料对匙吻鲟(Polyodon spathala)仔鱼生长和发育的影响,实验采用蛋黄或鱼油强化卤虫无节幼体或桡足幼体为饵料的共6个实验组,即未强化卤虫组、蛋黄强化卤虫组、鱼油强化卤虫组和未强化桡足幼体组、蛋黄强化桡足幼体组、鱼油强化桡足幼体组,对匙吻鲟仔鱼开口驯化14 d,动态监测和统计不同饵料组匙吻鲟仔鱼的生长和存活情况,并对消化酶活性进行相关性分析。体重、体长、日增重和存活率4个指标,均为桡足幼体组显著高于卤虫组(P0.05),尤其在存活率方面,鱼油强化卤虫组不足50%,而未强化桡足幼体组最高可达86.59%;不同饵料组生长模式方程都获得较好的拟合,从体重和体长生长曲线看,桡足幼体组从饲喂8天起体长和体重进入快速生长期,而卤虫组生长一直相对缓慢;胃蛋白酶活性在未强化桡足幼体组显著高于其他组(P0.05),不同饵料组对仔鱼的淀粉酶活性无显著性影响。结果表明,在匙吻鲟仔鱼开口期以桡足幼体开口饵料驯化效果较好,特别是未强化桡足幼体组仔鱼的存活率高,鱼油强化桡足幼体组仔鱼生长速度较快,而以卤虫饲喂效果相对较差。     

冷藏对美洲斑潜蝇蛹期发育和生存的影响

【目的】美洲斑潜蝇Liriomyza sativae Blanchard自20世纪90年代入侵我国后已经成为蔬菜和观赏植物的重要害虫。然而,近些年该昆虫已经逐渐成为研究植物和昆虫、昆虫抗寒性和寄主适应性等热点课题的模式种类。因此,为了实验室条件下更好保藏该虫的种群,本文研究了冷藏(世代发育起点温度8℃)对该斑潜蝇蛹发育和生存的影响。【方法】以化蛹后第3天的蛹为实验对象,8℃低温冷藏,并以冷藏时间(0、7、14、21、28和35 d)为参试因子研究了冷藏时间对美洲斑潜蝇蛹羽化率的影响;化蛹后每24 h解剖观察一次蛹并对蛹期发育阶段进行划分;根据划分的蛹期阶段,对处理中未羽化的蛹进行解剖比对,得到对低温最敏感的蛹期。【结果】随着冷藏时间的增长,美洲斑潜蝇的蛹羽化率逐渐降低。超过14 d后,羽化率明显下降。冷藏至35 d时羽化率为零。解剖正常发育的美洲斑潜蝇的蛹,将蛹期分为预蛹期、隐头蛹期、显头蛹初期、半透明眼期、浅黄色到琥珀色眼期、红褐色眼期、鬃毛蛹期。不同冷藏时间条件下,未羽化的蛹死亡时间主要为鬃毛蛹期,且鬃毛蛹期死亡的蛹的数量与贮藏时间呈正比例关系。【结论】在室内冷藏美洲斑潜蝇时,3日龄蛹8℃贮藏少于14 d为宜;鬃毛蛹期(10~11日龄蛹)对低温比较敏感,冷藏过程中,应避免鬃毛蛹期的蛹。