家蚕微孢子虫孢壁蛋白与其发芽的相关性

为了研究孢壁蛋白与家蚕微孢子虫发芽（孢原质弹出）的相关性,我们采用碳酸钾诱导微孢子虫体外发芽结合密度梯度离心的方法（简称GDGC法）,收集纯化发芽后的孢子空壳（简称孢壳）,对发芽液、纯化的孢壳及成熟孢子的孢壁蛋白组分进行了分析。结果表明：GDGC法可以获得高纯度孢壳,计算出其密度为1．130g/cm^3;与发芽前成熟孢子提取的孢壁蛋白相比,空孢壳可以提取到主要孢壁蛋白SWP32、SWP30、SWP25,同时发现SWP32、SWP25丰度有所降低;结合碳酸钾发芽液的蛋白电泳分析,发现孢壳上丰度降低的SWP32在发芽液蛋白样品中存在,LC—MS／MS数据分析也发现SWP32、SWP30、SWP25在碳酸钾处理液中都有存在;而用碳酸钾溶液处理冷冻孢子时,未观察到发芽现象,电泳结果显示此时K2CO,溶液中只有SWP30条带,说明在碳酸钾溶液诱导的发芽过程中SWP32和SWP25从孢壳上脱落可能与发芽相关而不是被碱性的碳酸钾溶解下来的[动物学报54（6）：1068—1074,2008]。     

Effect of storage, photoperiod and mechanical scarification on seed germination in Ocimum americanum

Seeds of Ocimum americanum L. display an absolute light requirement for germination. The minimal length of the daily photoperiod required to induce a high germination decreased with increasing seed age, but the length of the photoperiod under potential control of terminal far-red light inhibition remained unchanged. There was a gradual escape from the far-red inhibition with increase in the length of the photoperiod. Seeds developed flash photosensitivity after the first 13 h photoperiod. Scarification treatment did not allow the seeds to bypass the light requirement, but it enhanced the germination considerably. Under conditions of natural day length in the field, weakening of the testa by sand may abolish the need for a second exposure to light for most of the seed population, thus rendering them non-photoperiodic.     

Rice stripe virus coat protein induces the accumulation of jasmonic acid,activating plant defence against the virus while also attracting its vector to feed

The jasmonic acid (JA) pathway plays crucial roles in plant defence against pathogens and herbivores. Rice stripe virus (RSV) is the type member of the genus Tenuivirus. It is transmitted by the small brown planthopper (SBPH) and causes damaging epidemics in East Asia. The role(s) that JA may play in the tripartite interaction against RSV, its host, and vector are poorly understood. Here, we found that the JA pathway was induced by RSV infection and played a defence role against RSV. The coat protein (CP) was the major viral component responsible for inducing the JA pathway. Methyl jasmonate treatment attracted SBPHs to feed on rice plants while a JA-deficient mutant was less attractive than wild-type rice. SBPHs showed an obvious preference for feeding on transgenic rice lines expressing RSV CP. Our results demonstrate that CP is an inducer of the JA pathway that activates plant defence against RSV while also attracting SBPHs to feed and benefitting viral transmission. This is the first report of the function of JA in the tripartite interaction between RSV, its host, and its vector.     

Mammalian egg coat modifications and the block to polyspermy

Fertilization by more than one sperm causes polyploidy, a condition that is generally lethal to the embryo in the majority of animal species. To prevent this occurrence, eggs have developed a series of mechanisms that block polyspermy at the level of the plasma membrane or their extracellular coat. In this review, we first introduce the mammalian egg coat, the zona pellucida (ZP), and summarize what is currently known about its composition, structure, and biological functions. We then describe how this specialized extracellular matrix is modified by the contents of cortical granules (CG), secretory organelles that are exocytosed by the egg after gamete fusion. This process releases proteases, glycosidases, lectins and zinc onto the ZP, resulting in a series of changes in the properties of the egg coat that are collectively referred to as hardening. By drawing parallels with comparable modifications of the vitelline envelope of nonmammalian eggs, we discuss how CG‐dependent modifications of the ZP are thought to contribute to the block to polyspermy. Moreover, we argue for the importance of obtaining more information on the architecture of the ZP, as well as systematically investigating the many facets of ZP hardening.     

A rapid double-staining technique to improve seed viability testing in terrestrial orchids

Abstract

The need to optimize seed banking efforts has stimulated research for rapid methods to estimate quality in seed-lots. For terrestrial orchids, viability testing using tetrazolium (TTC) staining requires chemical scarification, as seeds have an impermeable testa. Different seed-coat permeability may affect TTC staining, thus affecting the results. The aim of this study was to perform a permeability test to assess the effectiveness of the used scarification method and its usefulness to correct TTC viability results. Mature seeds of Anacamptis laxiflora were subjected to eight scarification treatments with sodium hypochlorite solutions with different concentration and duration. Viability tests were performed using the basic TTC methodology, followed by a permeability test performed by means of trypan blue dye. The different scarification methods resulted in estimated TTC viability ranging from 0% and 94% for the same seed lot of A. laxiflora seeds. Our results proved that the used scarification protocol significantly affects both seed coat permeability and subsequent TTC staining (two-way ANOVA, p?< 0.0001). We describe a new rapid protocol that can be used to test terrestrial orchid seed viability. This double-staining method, providing rapid information on seed coat permeability, can be useful to avoid under-estimation of TTC results.     

Halocnemum M. Bieb. vegetation in the Mediterranean Basin

The aim of the article is the syntaxonomic interpretation of hyperhalophilous woody or semi-woody vegetation with Halocnemum M. Bieb. along the coasts of the Mediterranean Basin. For this area, the two species of Halocnemum, H. strobilaceum (Pall.) M. Bieb. and H. cruciatum (Forssk.) Tod. are identified; their morphological characteristics, synonymy and distribution are here described. The study carried out of particular aspects of the plant morphology and the micromorphological characteristics of the seeds collected from different places in the Mediterranean allows to better differentiate the two species. Vegetation studies already done in many communities of the Mediterranean by several authors threw into great confusion because only H. strobilacem has been recognized as a dominant species. As regards the syntaxonomic analyses of the vegetation, the authors refer to the proposals already made by various scientists for the vegetation of inland salt basins of Eurasia and the Irano-Anatolian area, who suggested the classes Kalidietea foliate and Halocnemetea strobilaceiirano-anatolica, respectively. Conversely, in the Mediterranean Basin, the vegetation study is present only in coastal areas where it is considerably impoverished in the number of species. Therefore, the authors propose to include hyperhalophilous, woody and fruticose vegetation in the class Sarcocornietea fruticosae. However, the phytosociological and ecological diversity is highlighted proposing the order Halocnemetalia cruciati in which both the alliance Halocnemion strobilacei, for middle Eastern Europe, and the alliance Halocnemion cruciati, for North Africa with penetrations in the Western and Eastern Europe up to the Middle East coast, are included. This new interpretation has required the correction of the names of two associations (Frankenio corymbosae–Halocnemetum cruciati and Zygophylloalbi–Halocnemetumcruciati) and the proposal of two new associations Arthrocnemo machrostachyi–Halocnemetum cruciati and Halocnemo cruciati–Sarcocornietum fruticosae. A further proposal concerns the addition of the alliance Limoniastrion monopetali, previously included in the order Limonietalia, in the order Halocnemetalia cruciati.     

The short‐ and long‐term fitness consequences of natal dispersal in a wild bird population

Dispersal is a key process in population and evolutionary ecology. Individual decisions are affected by fitness consequences of dispersal, but these are difficult to measure in wild populations. A long‐term dataset on a geographically closed bird population, the Mauritius kestrel, offers a rare opportunity to explore fitness consequences. Females dispersed further when the availability of local breeding sites was limited, whereas male dispersal correlated with phenotypic traits. Female but not male fitness was lower when they dispersed longer distances compared to settling close to home. These results suggest a cost of dispersal in females. We found evidence of both short‐ and long‐term fitness consequences of natal dispersal in females, including reduced fecundity in early life and more rapid aging in later life. Taken together, our results indicate that dispersal in early life might shape life history strategies in wild populations.     

Dramatic changes in the return date of Guillemots Uria aalge to colonies in Shetland, 1962–2005

Capsule Changes in return date coincided with marked changes in population size that probably resulted in fluctuating competition for nest-sites.

Aims To document the changes in return dates over a 44-year period and to identify the factors associated with these changes.

Methods We compared changes in return date at Shetland colonies with those for the Isle of May, southeast Scotland, and with the available information on population size, the abundance of some fish species eaten by Common Guillemots and large-scale changes in the oceanography and climate of the eastern Atlantic as reflected by the winter index of the North Atlantic Oscillation (NAO).

Results Common Guillemots normally return to colonies in Shetland in late winter. However, during the 1960s return dates became gradually earlier with birds present from early October. Autumn return remained the norm for about ten years after which return dates gradually reverted back to late winter. In contrast, Common Guillemots on the Isle of May, 400 km south of Shetland, showed no marked shift, returning in October each year. There was a strong negative correlation between date of return of Shetland birds and population size, whereas on the Isle of May birds came back earlier when there was a large positive winter NAO index. There was no convincing evidence that changes in wintering areas or fish abundance influenced when birds returned to the colonies, although the fish data may not have been collected on the correct spatial scale.

Conclusion Competition for high quality nest-sites is the most likely reason for Common Guillemots returning to the colonies during the autumn and winter.     

Physical aspects of COPI vesicle formation

Abstract

Coat proteins orchestrate membrane budding and molecular sorting during the formation of transport intermediates. Coat protein complex I (COPI) vesicles shuttle between the Golgi apparatus and the endoplasmic reticulum and between Golgi stacks. The formation of a COPI vesicle proceeds in four steps: coat self-assembly, membrane deformation into a bud, fission of the coated vesicle and final disassembly of the coat to ensure recycling of coat components. Although some issues are still actively debated, the molecular mechanisms of COPI vesicle formation are now fairly well understood. In this review, we argue that physical parameters are critical regulators of COPI vesicle formation. We focus on recent real-time in vitro assays highlighting the role of membrane tension, membrane composition, membrane curvature and lipid packing in membrane remodelling and fission by the COPI coat.