Habitat Preference, Reproduction and Diet of the Earthworm Eel, Chendol keelini (Teleostei: Chaudhuriidae)

The ecology of the earthworm eel, Chendol keelini, was studied in the field over a period of nine months. In addition this information was supplemented by aquarium observations. The species was most abundant in pools where it was associated with leaf litter and mats of fine tree roots along the banks. It fed on benthic invertebrates, especially chironomid and ephemeropteran larvae. C. keelini is sexually dimorphic; adult males develop a headhump and grow to a larger size than females. Reproduction was seasonal; the reproductive phase coincided with the wet season and lasted for several months. Fecundity was around 40 eggs per clutch. The eggs were spherical, between 1.2 and 1.5mm in diameter, and possessed a pair of long filaments for adhesion to the substrate. Females probably spawned more than once during the breeding season. The length frequency distributions and juvenile growth suggest that C. keelini is a short-lived species that matures during the first year with few individuals surviving to the second breeding season.     

薇甘菊提取物对红脉穗螟的产卵忌避及杀卵作用

【目的】探讨入侵杂草薇甘菊Mikania micrantha对棕榈害虫红脉穗螟Tirathaba rufivena的产卵忌避活性。【方法】采用室内生物测定法,研究薇甘菊不同溶剂提取物对红脉穗螟的产卵忌避作用和杀卵活性。【结果】产卵忌避试验结果表明,薇甘菊各提取物中,以正己烷和三氯甲烷提取物对红脉穗螟的产卵忌避效果最好,两者的选择性忌避率分别为43.64%和44.20%,非选择性忌避率分别为51.60%和59.20%。对卵孵化率的影响显示,各溶剂提取物均对红脉穗螟具有一定的杀卵活性,其中三氯甲烷提取物对卵孵化率的影响最大,校正孵化率最低,仅为53.39%,而且三氯甲烷提取物引起的1龄幼虫的死亡率最高,可达42.64%。在薇甘菊三氯甲烷提取物的不同溶剂萃取物中,正丁醇萃取物对红脉穗螟的产卵忌避和杀卵活性均显著高于其他溶剂萃取物。【结论】薇甘菊提取物具有一定的产卵忌避和杀卵活性,具有用于红脉穗螟的生态防控的潜力。     

Adhesiveness and surface patterns of eggs in neotropical freshwater teleosts

Eggs of 23 Characiformes and eight Siluriformes, belonging to nine families with diverse reproductive behaviour, were ultrastructurally analysed. The migratory species exhibited non-adhesive eggs, whereas, most of the sedentary species presented some degree of egg adhesiveness. Among the Characiformes, non-adhesive eggs showed zona radiata with pore-canals or a fibrillar net at the surface; weakly adhesive eggs presented only zona radiata with pore-canals while adhesive eggs exhibited zona radiata with apparatus like globules, filaments, villi or honeycomb-like pores depending on the systematic group. The 'jelly' coat is strongly related to the Siluriformes eggs apparently without relationship with adhesiveness. A micropylar disc was present in adhesive eggs of a few species of both Characiformes and Siluriformes. Some patterns were characteristic of the animal pole, others of the vegetal pole, and others were common to both poles. The radial ridges converging to the micropyle in Astyanax bimaculatus lacustris appear to be related to fertilization. In general, egg surface structures in the Characiformes varied according to the genus, whereas all Siluriformes showed a similar egg surface pattern, regardless of the group analysed. Multivariate analysis allowed the identification of eight clusters among the Characiformes and three among the Siluriformes showing relationships between reproductive style and egg characteristics. It is suggested that egg surface and adhesiveness may be related to reproductive patterns and to phylogenesis.     

热环境对虎斑颈槽蛇卵孵化期、孵化成功率和孵出幼体特征的影响

用恒温（２４、２７、３０和３３Ｃ）和波动温度（平均２６．１Ｃ,范围２０．１—３２．７Ｃ）孵化虎斑颈槽蛇（Ｒｈａｂｄｏｐｈｉｓ　ｔｉｇｒｉｎｕｓ　ｌａｔｅｒａｌｉｓ）卵,检测热环境对孵化期、孵化成功率和孵出幼体的影响。孵化热环境显著影响孵化期、孵化成功率和胚胎畸形率,对孵出幼体性别无显著影响。孵化期随孵化温度升高而缩短,２４、２７、３０和３３Ｃ的平均孵化期分别为４５．０、３２．７、２７．３和２６．０ｄ,波动温度的平均孵化期为３７．９ｄ。３３Ｃ孵化成功率最低（１６．７％）,胚胎畸形率最高（１００％）。孵出幼体总性比（雌性／雄性＝０．６）不显著偏离１：１。孵出幼体的尾长显示两性异形,雄性尾长大于雌性;其它被检幼体特征无显著的两性差异。２４、２７和３０Ｃ以及波动温度孵出幼体的所有被检指标均无显著差异。３３Ｃ孵出幼体的体重和个体大小小于其它热环境中孵出的幼体,并特征性地具有较小的躯干、较大的剩余卵黄。３３Ｃ中胚胎发育的能耗显著大于其它热环境中胚胎发育的能耗。３３（‘孵出幼体的灰分含量较低,但孵出卵卵壳较重。３３Ｃ孵出幼体不能运动;其它热环境中孵出的幼体在跑道上表现良好,这些幼体的不问断运动的最大距离、每分钟运动距离和每分钟停顿次数无显著的差异。结果表明,持续将虎斑颈槽蛇卵暴露在３３Ｃ条件下不利于该种胚胎发育并可能对胚胎具有致死性影响,波动温度孵卵有利于拓宽存活孵化温度范围。     

Genetics and biology of the sawfly,Athalia rosae (Hymenoptera)

Hymenopteran insects are a unique group of animals in which arrhenotokous reproduction (haploid males develop from unfertilized eggs) is a rule. Males produce sperm through a non-reductional maturation division. A sawfly species,Athalia rosae ruficornis Jakovlev (Tenthredinidae, Symphyta, Hymenoptera), has been introduced as a new experimental material for studies on genetics and developmental biology. Basic features relating to the potential usefulness of the species in elucidating some of the important genetic and developmental biological problems are described.     

Observations on egg-laying behaviour of the banana weevil,Cosmopolites sordidus (Germar)

Banana weevil females laid on an average 2.7 eggs/week in rhizome material and 0.7 eggs/week in pseudostem material in the laboratory. At extremely high weevil population densities the egg-laying activity declined. Under controlled field conditions 0.7 eggs/week were laid in banana suckers and 1.3 eggs/week in stumps of harvested suckers. 25% of the weevil stages found in suckers in the field were eggs of which 78% were laid in the rhizome and 22% in the pseudostem base. The majority of eggs was deposited in the crown area of the rhizome followed by the remaining surface area of the rhizome, the walls of abandoned larval tunnels in rhizome and pseudostem and the leaf sheaths. 58% of the eggs found were considered accessible to egg predators.     

Computational Design of a Protein-Based Enzyme Inhibitor

While there has been considerable progress in designing protein–protein interactions, the design of proteins that bind polar surfaces is an unmet challenge. We describe the computational design of a protein that binds the acidic active site of hen egg lysozyme and inhibits the enzyme. The design process starts with two polar amino acids that fit deep into the enzyme active site, identifies a protein scaffold that supports these residues and is complementary in shape to the lysozyme active-site region, and finally optimizes the surrounding contact surface for high-affinity binding. Following affinity maturation, a protein designed using this method bound lysozyme with low nanomolar affinity, and a combination of NMR studies, crystallography, and knockout mutagenesis confirmed the designed binding surface and orientation. Saturation mutagenesis with selection and deep sequencing demonstrated that specific designed interactions extending well beyond the centrally grafted polar residues are critical for high-affinity binding.     

用三维图象量测卵裂前蛙卵膜分子的三维运动

两栖类卵第一次卵裂前,缩时电影显示出卵表面有收缩波。由于卵的体积未变,在收缩时卵的高度必然增加。Sawai(1978)利用棱镜侧面摄取了蝾螈卵轮廓的高度变化,证实了卵裂前卵最高处的高度确有增加。但这一方法不能测知整个卵表面各处的高度变化,而且仅是二维的。在林蛙卵上,我们用荧光漂白恢复技术发现第一次卵裂前卵表面分子有规律性的流动,推测这是卵球的张弛。为了进一步     

Comparative biochemical analysis of the major yolk protein in the sea urchin egg and coelomic fluid

The major yolk protein (MYP) is localized to the egg and coelomic fluid of the adult sea urchin. While the egg‐localized MYP has been extensively studied, much less is known about the coelomic fluid‐localized protein. Therefore, we have conducted a comparative biochemical analysis of these proteins. Sucrose density gradient ultracentrifugation revealed unique elution profiles for the MYP species present in the egg, 170‐ and 240 kDa, and the coelomic fluid, 180‐ and 250 kDa. Fractionation in polyacrylamide gels revealed that under reducing conditions both species were present in each location. However, in the absence of reducing agent only one species was present in each fraction: 240 kDa in the egg and 250 kDa in the coelomic fluid. In addition, V8 peptide mapping indicated that all four species have very similar primary structures. Circular dichroic spectral analysis and endogenous tryptophan measurements of the purified 170‐ and 180 kDa species revealed distinctive secondary and tertiary structural features with notable differences in their responses to calcium: apparent Kds of 245‐ and 475 μmol/L were measured for the 170‐ and 180 kDa species, respectively. Further analysis revealed that both species have differing calcium requirements for binding to membranes as well as protein‐dependent, membrane‐membrane interaction. We discuss the functional implications arising from the structural differences which exist between the egg and coelomic fluid resident MYPs.