中华绒螯蟹（Eriocheir sinensis）肌肉中粗脂肪含量与死亡,产 …

本文报道了中华螯蟹越冬时,越冬后不同性别、不同生活状况肌肉中粗脂肪含量及变化。越冬时、越冬后死亡的♂♀河蟹肌肉中粗脂肪的含量均不到８％,而同时越冬成活的♂♀蟹肌肉中粗脂肪含量均高于１０％。顺利越冬并能产卵的雌蟹肌肉中粗脂肪含量为４．９６％,顺利越冬并交配的♂性肌肉中粗脂肪含量为４．１８％。产卵并抱卵孵化的♀蟹肌肉中粗脂肪含量为５．８５％,产卵但♀蟹中途死亡的其肌肉中粗脂肪的含量为５．４７％。交配不     

Egg-hatching synchrony and larval cannibalism in the dock leaf beetle Gastrophysa viridula (Coleoptera: Chrysomelidae)

Females of leaf beetles and many other herbivorous insects lay eggs in coherent batches. Hatchlings emerge more or less simultaneously and often prey on their late-hatching clutchmates. It is not certain, however, whether this synchrony of hatching is a mere by-product of cannibalism or whether an additional synchronizing factor exists. The following simple experiment was aimed at determining the causal relationship between cannibalism and simultaneous larval emergence. Egg clutches of the dock leaf beetle Gastrophysa viridula were split into two halves. These halves were either kept as coherent groups in two separate dishes or, alternatively, only one half remained whole, whereas the other one was divided into single eggs, each of which was incubated in a separate dish. Halving of a clutch into coherent groups only slightly disrupted the synchrony of emergence. The consequence of individual isolation was more dramatic. Half-clutches consisting of disconnected solitary eggs required almost twice as much time for complete emergence of all larvae, which was significantly more than cannibalism as a sole synchronizing factor might explain. Moreover, survival rates were the same in coherent half-clutches (in the presence of cannibalism) and among isolated individuals. This group effect and the small contribution of cannibalism suggest the existence of an additional synchronizing factor. Possible mechanisms underpinning this phenomenon are discussed.     

于家沟遗址鸵鸟蛋皮的人类利用特征

鸵鸟蛋皮是中国北方旧石器时代遗址中最常见的鸟类遗存。目前,限于蛋皮的样本量与保存状况,很少有研讨古人类是否能够食用鸵鸟蛋液或者利用鸵鸟蛋作为盛煮容器问题。本文以于家沟遗址第3b和4层出土的鸵鸟蛋皮为材料,从其 ¹⁴C年代、孵化状况、燃烧导致的颜色变化等方面,分析了古人类获取、消费和利用鸵鸟蛋的方式。结果显示,于家沟人既采集了鸵鸟蛋皮作为制作装饰品的原料,也可能获取了完整鸵鸟蛋,食其蛋液,用其蛋壳,并将整蛋作为容器进行了加热。     

菲牛蛭交配及卵茧人工孵化初步研究

人工饲养条件下,比较观察了不同养殖模式(水体、土壤)和不同温度(24℃、26℃、28℃、30℃、32℃和34℃)对菲牛蛭(Hirudinaria manillensis)交配率的影响,并进行了不同卵茧质量(＜0.6 g、0.6～1.0 g、1.0～1.5g、1.5～2.0 g、＞2.0 g)及不同温度(22℃、24℃、...     

Phenotypically plastic responses of green frog embryos to conflicting predation risk

Predators have been shown to alter the timing of switch points between life history stages, but few studies have addressed switch point plasticity in prey exposed simultaneously to conflicting predation pressure. We tested hatching responses of green frog (Rana clamitans) embryos subject to perceived predation risk from chemical cues released by two stage-specific predators, predicting that these predators would elicit: (1) directional hatching responses when presented independently, and (2) intermediate phenotypic responses when presented simultaneously. R. clamitans embryos in outdoor exclosures were exposed to cues from an egg predator (freshwater leeches; Nephelopsis obscura), a larval predator (dragonfly nymphs, Aeschna canadensis), and both predators in a 2 × 2 factorial experiment, and changes in hatchling size, hatchling developmental stage, and hatching time were compared to those for control embryos. Leeches alone induced embryos to hatch at a smaller size and an earlier developmental stage than controls, while dragonfly nymphs elicited a delay in egg hatching time that was associated with larger size and later developmental stage at hatching. Embryos failed to respond to simultaneous exposure to both predators, implying that responses to each occurred concurrently and were therefore dampened. Our results indicate that prey under threat from conflicting predators may manifest intermediate defensive phenotypes. Such intermediate responses may result in elevated rates of prey mortality with possible consequences at the population level.     

Amphibian hatching gland cells: pattern and distribution in anurans

The hatching gland (HG) is a transient organ, found in most anuran embryos and early larvae, and located on the dorsal side of the head. The enzymes secreted by hatching gland cells (HGCs) aid the embryos to escape from their enveloping coats. Analysis of HG morphology and distribution in 20 anuran species from six families using scanning electron microscopy revealed small differences in the shape and pattern of the gland particularly in the length and width of the posterior mid-dorsal extension of the gland. The four species of foam-nest making leptodactylids examined had HGs of a somewhat different shape to the others, but otherwise, there was little sign of a relationship between HG shape and taxonomic position. In the single Eleutherodactylus species examined, cells with the appearance and location of HGCs were transiently present long before the active stage of hatching. No sign of HGCs was seen on the head surface of one species, Phyllomedusa trinitatis. It seems possible that in this species, hatching is achieved by a mechanical rather than an enzymatic mechanism. The microvilli characteristic of the surfaces of HGCs were quite variable in density and length from species to species, and at different stages. HGCs remained at the surface of the embryo for some time after hatching and the possibility of a post-hatching function is briefly discussed.     

Effect of some fertilizers on hatching of cereal cysts nematode,Heterodera avenae

Experiments were conducted in laboratory and pot conditions to determine the effects of urea, di-ammonium phosphate (DAP), single super phosphate (SSP), muriate of potash (MOP) and zinc sulphate (ZnSO₄) on hatching of Heterodera avenae. Two concentrations of each fertilizer were tested in lab for which 10 cysts and 5 ml of each concentration were taken in 5 cm diameter Petri plates. Observations were recorded at weekly intervals up to six weeks. Urea, DAP, SSP and MOP inhibited hatching and ZnSO₄ increased it. After six weeks, hatching was least (5.45%) in higher dose of urea and greatest (46.9%) in higher dose of ZnSO₄. In pot experiment, two doses of urea and single dose of SSP, MOP, and ZnSO₄ were applied in H. avenae-infested soil and WH-1105 wheat was sown. Observations on nematodes in roots, soil and remaining cyst contents were recorded 40 days after sowing. Among all the fertilizers, least nematodes in soil and roots were found at higher dose of urea and greatest number in ZnSO₄.     

Hatching glands in cephalopods – A comparative study

Hatching of embryos from their eggs involves either mechanical and/or chemical support. In particular enzymes are widely used in the animal kingdom to weaken the egg layers and facilitate the embryo's escape. Although numerous morphological and biochemical studies exist on the hatching glands of invertebrates (such as sea urchins, ascidians, insects) and vertebrates (teleosts, amphibians, and mammals), little is known about the morphology of the hatching glands (Hoyle organs) in cephalopod hatchlings.In this study, the internal gland structure and the external appearance of the Hoyle organ are compared among several cephalopod species (Idiosepius pygmaeus; Euprymna scolopes; Sepia officinalis; Loligo gahi; Sepioteuthis lessoniana; Architeuthis sp.; Octopus vulgaris; Tremoctopus gracilis; Argonauta hians). In almost all cases the glandular system is restricted to the posterior part of the dorsal mantle surface. Only Octopus and Argonauta lack a specific glandular structure in this body region and the animals apparently use other mechanisms to penetrate the egg layers.In all decapod species (Idiosepius; Euprymna; Sepia; Loligo; Sepioteuthis; Architeuthis) as well as in Tremoctopus only one specific cell type is present in the Hoyle organ, which synthesizes granular material. The secretory droplets are more or less uniform in electron density in Idiosepius, Euprymna and Tremoctopus but exhibit translucent inclusions in the other decapods. The time of gland development, first synthesis of secretory products and later degeneration after hatching vary between the species.The present study contributes to our knowledge of glandular systems in cephalopods and allows comparison with hatching structures in other invertebrates and vertebrates.