一个侵染山东大葱的胡葱黄条病毒分离物的鉴定

在山东章丘大葱上发现了一种引起畸形黄条症状的线状病毒。该病毒容易摩擦接种侵染大葱和胡葱,但不侵染其它22种测试植物,能经由豌豆蚜传播。病毒粒子形态和细胞病理特征具有马铃薯Y病毒科成员的典型特征。Western blot分析表明,提纯病毒制备的抗血清能与病毒自身外壳蛋白起特异性的强反应,与薤花叶病毒、晚香玉轻斑驳病毒、小西葫芦黄花叶病毒和芋花叶病毒外壳蛋白有较弱的反应。采用马铃薯Y病毒科简并引物PCR技术扩增了该病毒的基因组3′-末端部分序列,序列比较表明它为胡葱黄条病毒(SYSV),系统进化树分析表明世界范围内的SYSV分离物可以区分为4个主要群体,在一定程度上与寄主植物种类及地理分布相关。     

小麦TaLSDl锌指蛋白基因的电子克隆及序列分析

采用电子克隆与RT-PCR相结合的技术,在条锈菌（Pucciniastriiformis f．sp．tritici）侵染的小麦中克隆了一个LSDl型锌指蛋白基因,命名为TaLSDl（GenBank登录号为EF553327）。序列分析表明,该基因全长1024bp,编码生成1个包含3个保守LSDl型锌指结构（CxxCxRxxLMYxxGASxVxCxxC）且长度为146个氨基酸的多肽。进化树分析表明,TaLSDl与水稻（Oryzasativa）、拟南芥（Arabidopsisthaliana）和芜菁（Brassicarapa）中部分含有3个保守LSDl型锌指结构的同源基因亲缘关系较近,而与其它包含不同数目的LSDl型锌指结构基因亲缘关系较远。推测TaLSDl在进化中丢失了部分序列,进而执行新的功能。半定量RT-PCR结果显示,该基因在亲和以及非亲和组合中的表达模式很相似,均表现在前期基因表达被抑制而后期恢复正常。初步推测TaLSDl在转录水平上的表达受光诱导,同时,作为一个细胞程序性死亡的负调控因子在小麦与条锈菌互作过程中起作用。     

Folivory by a tropical tanager: species of plants used and the relationship between leaf consumption and fruit abundance

ABSTRACT Folivory, or eating leaves, is unusual for small passerines. Puerto Rican Spindalises (Spindalis portoricensis, Thraupidae), tanagers endemic to the island of Puerto Rico, are known to feed on leaves, but little is known about the possible importance of leaves in their diet. Our objectives were to determine the different species of leaves eaten, the percentage of their diet consisting of leaves, and the relationship between leaf consumption and fruit abundance. We used data from previous studies where the foraging activity of Puerto Rican Spindalises was systematically sampled, and from additional observations made throughout the island. We documented 160 records of folivory, with spindalises feeding on 44 plant species in 25 plant families, including monocots, dicots, gymnosperms, and pteridophytes. Spindalises fed on young leaves of 26 plant species, and mature leaves of 19 plant species. Spindalises were primarly frugivorous (83.9% of diet), but leaves were the second most frequent food item in their diets (8.9% of diet). We also found that leaf consumption was negatively correlated with the abundance of ripe fruit, suggesting that leaves were particularly important food items when less fruit was available. The frequency of folivory by spindalises in our study was less than reported for other folivorous passerines such as plantcutters (Phytotoma spp.) and saltators (Saltator spp.). Nonetheless, folivory may help spindalises cope with human‐dominated landscapes and other environmental changes on small islands.     

Engineering Tobacco Mosaic Virus and Its Virus-Like-Particles for Synthesis of Biotemplated Nanomaterials

Biomolecules are increasingly attractive templates for the synthesis of functional nanomaterials. Chief among them is the plant tobacco mosaic virus (TMV) due to its high aspect ratio, narrow size distribution, diverse biochemical functionalities presented on the surface, and compatibility with a number of chemical conjugations. These properties are also easily manipulated by genetic modification to enable the synthesis of a range of metallic and non-metallic nanomaterials for diverse applications. This article reviews the characteristics of TMV and related viruses, and their virus-like particle (VLP) derivatives, and how these may be manipulated to extend their use and function. A focus of recent efforts has been on greater understanding and control of the self-assembly processes that drive biotemplate formation. How these features have been exploited in engineering applications such as, sensing, catalysis, and energy storage are briefly outlined. While control of VLP surface features is well-established, fewer tools exist to control VLP self-assembly, which limits efforts to control template uniformity and synthesis of certain templated nanomaterials. However, emerging advances in synthetic biology, machine learning, and other fields promise to accelerate efforts to control template uniformity and nanomaterial synthesis enabling more widescale industrial use of VLP-based biotemplates.     

Rice stripe virus nonstructural protein 3 suppresses plant defence responses mediated by the MEL–SHMT1 module

Our previous study identified an evolutionarily conserved C4HC3-type E3 ligase, named microtubule-associated E3 ligase (MEL), that regulates broad-spectrum plant resistance against viral, fungal and bacterial pathogens in multiple plant species by mediating serine hydroxymethyltransferase (SHMT1) degradation via the 26S proteasome pathway. In the present study, we found that NS3 protein encoded by rice stripe virus could competitively bind to the MEL substrate recognition site, thereby inhibiting MEL interacting with and ubiquitinating SHMT1. This, in turn, leads to the accumulation of SHMT1 and the repression of downstream plant defence responses, including reactive oxygen species accumulation, mitogen-activated protein kinase pathway activation, and the up-regulation of disease-related gene expression. Our findings shed light on the ongoing arms race between pathogens and demonstrate how a plant virus can counteract the plant defence response.     

Developmental mechanisms of longitudinal stripes in the Japanese four‐lined snake

The developmental mechanisms of color patterns formation and its evolution remain unclear in reptilian sauropsids. We, therefore, studied the pigment cell mechanisms of stripe pattern formation during embryonic development of the snake Elaphe quadrivirgata. We identified 10 post‐ovipositional embryonic developmental stages based on external morphological characteristics. Examination for the temporal changes in differentiation, distribution, and density of pigment cells during embryonic development revealed that melanophores first appeared in myotome and body cavity but not in skin surface at Stage 5. Epidermal melanophores were first recognized at Stage 7, and dermal melanophores and iridophores appeared in Stage 9. Stripe pattern first appeared to establish at Stage 8 as a spatial density gradient of epidermal melanophores between the regions of future dark brown longitudinal stripes and light colored background. Our study, thus, provides a comprehensive pigment‐cell‐based understanding of stripe pattern formation during embryonic development. We briefly discuss the importance of the gene expression studies by considering the biologically relevant theoretical models with standard developmental staging for understanding reptilian color pattern evolution.     

Regional responses within the kidney to ischemia: assessment of adenine nucleotide and catabolite profiles

Renal cortex (C) has predominantly aerobic metabolism, whereas inner medulla (IM) has both aerobic and anaerobic capacities. This study was undertaken (1) to assess how well rat IM anaerobic metabolism maintains this region's ATP content during ischemia; and (2) to determine whether regional variations in adenylate pool/catabolite responses to ischemia exist, obscuring interpretation of cellular energetics in rat studies of acute renal failure (ARF). Adenine nucleotides/catabolites were measured in rat C, IM and outer medulla (OM) after 15 and 45 min of ischemia. After 15 min, all regions showed profound ATP depletion, although the IM maintained slightly higher (by 0.23 μmol/g) absolute ATP levels than C/OM tissues (normal ATP value = 8.7 μmol/g). By 45 min, significant differences in regional ATP levels did not exist. Striking regional catabolite differences were apparent at both 15 and 45 min. Most prominent were: (1) intrarenal purine base/inosine gradients, levels falling approx. 22–50% from C to IM; and (2) preferential OM AMP/IMP/adenosine accumulation. To assess whether more homogeneous results might be found in rabbit kidney, possibly making this animal preferable to rats for studies of renal ischemia, rabbit C, OM and IM adenylate pools were analyzed after 15 min of ischemia. C vs. IM ATP differences were greater (approx. 1.3 μmol/g) and large catabolite concentration differences were still apparent. Conclusions: (1) anaerobic mechanisms support IM ATP levels during ischemia but, in terms of normal concentrations, the impact is small, particularly in the rat; and (2) marked regional differences in adenylate catabolite levels exist within ischemic kidneys. These need to be recognized when analyzing adenylate pool responses in ischemic ARF.     

Electrical Penetration Graphs from Peregrinus maidis on a susceptible maize hybrid

The feeding behavior of Peregrinus maidis (Ashmead) (Homoptera: Delphacidae), vector of maize mosaic virus (MMV) and maize stripe virus (MStpV) in maize (Zea mays L.), has been studied by Electrical Penetration Graph (EPG). The different recordings collected have allowed the temporal distinction of three EPG signal classes. These class 1, class 2 and class 3 signals are correlated through histological sections to the feeding activities of probing, xylem ingestion and phloem ingestion, respectively. Although these signals are described by various statistical parameters, only the median allows significant differentiation between class 2 and class 3 signals, the others varying from one insect to the next. On the other hand, spectral analysis is used to describe the signal classes by associating a characteristic frequency spectrum to each. This study treats the importance of such analysis in characterizing and comparing the signals of various piercing and sucking insects.