食虫沟瘤蛛的饥饿耐受性

对我国多数稻区共享的优势种蜘蛛食虫沟瘤蛛进行饥饿耐受性测定,结果显示食虫沟瘤蛛的耐饥时间以及组内个体耐饥力的变异幅度与温度高低呈负相关。在35、25℃和15℃3种试验温度下,食虫沟瘤蛛的耐饥时间及变异幅度均与龄期呈正相关;在5℃时,耐饥时间极大延长,组内变异系幅度亦急剧增大,但此时耐饥时间和变异幅度均与龄期呈负相关。在高温35℃和低温5℃下,3个龄期组的耐饥时间差异不显著(p>0.05);但在适宜温度25℃和15℃时,3个龄期组之间的耐饥时间差异显著(p<0.05)。同一龄期组的食虫沟瘤蛛在任意两种不同的温度条件下,其耐饥时间的差异性均达到极显著水平(p<0.01)。4种试验温度条件下,处于饥饿状态的食虫沟瘤蛛各龄期组的阶段死亡率均具有正态分布特点,可用正态分布模型M=1σ2π.e-(T2-σ2μ)2进行拟合;并可根据正态分布的特点得出食虫沟瘤蛛的饥饿半致死时间(T50)和致死时间(T95)。     

Production and fate of faecal pellets during summer in an East Antarctic fjord

The abundance of small faecal pellets is high in marine waters. Little is known, however, about the processes governing their production and fate in the water column. We investigated faecal pellet production and flux in relation to the phytoplankton and copepod assemblages present in Ellis Fjord, Antarctica. Results show that the phytoplankton community shifted from a dominance of diatoms to that of a cryptomonad species during late January. This coincided with an increase in abundance of the small copepods Paralabidocera antarctica and Oithona similis, although Oncaea curvata was still the dominant species. The mean faecal pellet flux was 9943 pellets m^–2 d^–1. Only 37% of the faecal pellet flux at 5 m sedimented to 10 m depth, 15% to 20 m, and 12% to 40 m depth. Our results suggest that recycling of faecal pellets by copepods contributes to this decreased flux with increasing depth, which concurs with results from large scale oceanic studies. Additionally, we propose that the summer ice melt changes the physical characteristics of the water column and the phytoplankton species abundance and distribution; both of which potentially impact on the distribution and abundance of copepods, thereby regulating faecal pellet flux.     

Faecal pellets in streams: their binding, breakdown and utilization

1. Faecal pellets of Gammarus (shredders) and Simulium larvae (suspension feeders) are bound by exopolymers. Immediately after egestion, Gammarus pellets are covered by a peritrophic membrane that breaks up within hours, although pellets remain intact because of internal binding materials. 2. Although they expand soon after egestion, the faecal pellets of Gammarus and Simulium remain intact for more than 30 days. Their internal structure is altered and the main agents of this change are bacteria that have survived passage through the gut (and become bound within pellets). 3. When disrupted physically, freshly egested (1‐ to 2‐day old) Simulium faecal pellets break up into relatively large pieces whereas freshly egested Gammarus faecal pellets break apart into much smaller pieces. Disruption of 30‐day old Simulium faecal pellets results in similar sized pieces to those from freshly egested pellets, but disruption of 30‐day old Gammarus pellets produces pieces that are two orders of magnitude larger than those resulting from disruption of freshly egested pellets. 4. Faecal pellets of Gammarus and Simulium are eaten by stream invertebrates and are sites of microbial breakdown. Faecal pellets are a source of organic matter for benthic invertebrates, bacteria and, indirectly, for plants.     

Low-level microwave irradiation and central cholinergic activity: a dose-response study

Rats were irradiated with circularly polarized, 2,450-MHz pulsed microwaves (2-microseconds pulses, 500 pulses per second [pps]) for 45 min in the cylindrical waveguide system of Guy et al:(Radio Sci 14:63-74, 1979). Immediately after exposure, sodium-dependent high-affinity choline uptake, an indicator of cholinergic activity in neural tissue, was measured in the striatum, frontal cortex, hippocampus, and hypothalamus. The power density was set to give average whole-body specific absorption rates (SAR) of 0.3, 0.45, 0.6, 0.75, 0.9, or 1.2 W/kg to study the dose-response relationship between the rate of microwave energy absorption and cholinergic activity in the different areas of the brain. Decrease in choline uptake was observed in the striatum at a SAR of 0.75 W/kg and above, whereas for the frontal cortex and hippocampus, decreases in choline uptake were observed at a SAR of 0.45 W/kg and above. No significant effect was observed in the hypothalamus at the irradiation power densities studied. The probit analysis was used to determine the SAR50 in each brain area, i.e., the SAR at which 50% of maximum response was elicited. SAR50 values for the striatum, frontal cortex, and hippocampus were 0.65, 0.38, and 0.44 W/kg, respectively.     

Organic matter processing by chironomid larvae (Diptera: Chironomidae)

In laboratory experiments, we used fluorescent dye markers to investigate processing of organic matter by larvae of Psectrocladius limbatellus (Holm.) (Diptera: Chironomidae). 59% of the organic matter used was incorporated into tubes, 39% was present in faecal pellets (both after 24 h), and 2% was found in the larval gut at the end of experiments. Ingested matter passed through the gut rapidly, resulting in the gut being emptied more than 20 times each day. Further 24-h experiments using dye-marked faecal pellets showed that 6% of pellets produced were re-ingested and 12% were incorporated into tubes. There was no preference for conditioned faecal pellets as food over those that had recently been egested and tubes also provided a food reserve on which larvae feed. Chironomid larvae recycle organic matter resulting in its mineralization and their ‘engineering’ has a dramatic effect on the substratum. This revised version was published online in July 2006 with corrections to the Cover Date.     

Faecal pellet production by Arctic under-ice amphipods – transfer of organic matter through the ice/water interface

The underside of Arctic sea ice is inhabited by several autochthonous amphipod species (Apherusa glacialis, Onisimus spp., Gammarus wilkitzkii). The amphipods graze on ice-bound organic matter, such as ice algae, detritus and ice fauna, and release faecal pellets into the underlying water column, thus forming a direct link between the sea ice and the pelagic ecosystems. Experiments on faecal pellet production rates showed species-specific differences, which were related to size of the animals. The smallest species, A. glacialis, produced the highest mean number of pellets (15.4 pellets ind.^-1 d^-1), followed by Onisimus spp. (2.7 pellets ind.^-1 d^-1) and the largest species, G. wilkitzkii (1.1 pellets ind.^-1 d^-1). Relative carbon content of the pellets was very similar in all species (21.2–22.6% dry mass). Juvenile amphipods (Onisimus spp., G. wilkitzkii) produced more pellets with less POC than adults. Based on field determinations of the POC concentration in the lowermost 2 cm of the sea ice (mean: 36.4 mg C m^-2) and mean amphipod abundances (A. glacialis: 33.8 ind. m^-2, Onisimus spp.: 0.5 ind. m^-2, G. wilkitzkii: 9.4 ind. m^-2) in the Greenland Sea in summer 1994, the amount of POC transferred from the ice to the water by faecal pellet production was estimated (0.7 mg C m^-2 d^-1 or almost 2% of ice-bound carbon). Since this process probably takes place in all ice-covered Arctic regions as well as during all seasons, grazing and pellet production by under-ice amphipods contributes significantly to matter flux across the ice/water interface.     

从弹尾纲和原尾纲的亲缘关系质疑缺尾纲（=近昆虫纲）的有效性

鉴于弹尾目（跳虫）和原尾目的尾部都没有尾须（cerci）,Brner于1910年就把这两类归并为一个类群缺尾纲（Ellipura）,这一分类阶元长期被许多昆虫学家沿用至今。Kukalová-Peck(1987 )在讨论化石双尾虫（?）附肢的总体结构（ground plan）时,认为跳虫和原尾虫的腹部侧板更原始,附肢无转节,将二者归纳成近昆虫纲（Parainsecta）。但是从形态特征、内部结构、比较精子学、变态类型和胚后发育等的特点以及线粒体DNA和核糖体DNA的测序分析结果,显示弹尾纲与原尾纲之间存在诸多重要差异,不具备较为密切的亲缘关系,我们不支持（弹尾纲+原尾纲）组成缺尾纲或近昆虫纲。据此建议取消缺尾纲（=近昆虫纲）这一分类阶元。     

Good housekeeping: why do shelter‐dwelling caterpillars fling their frass?

Although both feeding and elimination of waste are imperatives for all animals, ecologists and evolutionary biologists have devoted considerable attention to foraging, while largely ignoring defecation. Many organisms, however, exhibit defecation behaviours that appear to have been shaped by natural selection in a range of ecological contexts. Accumulation of waste may pose particular challenges for animals that exhibit high site fidelity or live within enclosed spaces. In a taxonomically widespread but largely unexamined behaviour, many caterpillars that construct and inhabit leaf shelters ballistically eject their individual faecal pellets (frass) great distances at great speeds. Here, I show that elimination of chemical cues for natural enemies is likely to have been a driving force behind the evolution of frass ejection behaviour in skipper caterpillars; hygiene and crowding are less important in this system.     

Synthesis and olfactory activity of unnatural, sulfated 5β-bile acid derivatives in the sea lamprey (Petromyzon marinus)

A variety of unnatural bile acid derivatives (9a-9f) was synthesized and used to examine the specificity with which the sea lamprey (Petromyzon marinus) olfactory system detects these compounds. These compounds are analogs of petromyzonol sulfate (PS, 1), a component of the sea lamprey migratory pheromone. Both the stereochemical configuration at C5 (i.e., 5α vs. 5β) and the extent and sites of oxygenation (hydroxylation or ketonization) of the bile acid derived steroid skeleton were evaluated by screening the compounds for olfactory activity using electro-olfactogram recording. 5β-Petromyzonol sulfate (9a) elicited a considerable olfactory response at sub-nanomolar concentration. In addition, less oxygenated systems (i.e., 9b-9e) elicited olfactory responses, albeit with less potency. The sea lamprey sex pheromone mimic 9f (5β-3-ketopetromyzonol sulfate) was also examined and found to produce a much lower olfactory response. Mixture studies conducted with 9a and PS (1) suggest that stimulation is occurring via similar modes of activation, demonstrating a relative lack of specificity for recognition of the allo-configuration (i.e., 5α) in sea lamprey olfaction. This attribute could facilitate design of pheromone analogs to control this invasive species.     

Environmental cadmium exposure, adverse effects and preventive measures in Japan

In Japan the most heavily cadmium (Cd)-polluted region is the Jinzu river basin, where Itai-itai disease is endemic and the Kakehashi river basin is the second most polluted region.. The village average Cd concentrations in rice were distributed in the range between 0.02 microg/g and 1.06 microg/g in the Jinzu river basin and 0.11 microg g and 0.67 microg g in the Kakehashi river basin. Severe renal damage has occurred widely in the Jinzu river basin. Even after Cd exposure had ceased, renal dysfunction became worse. Dose-response relationships between Cd exposure and health effects were clearly demonstrated in both regions. The allowable limits (according to the present authors' assessment) of Cd concentrations in rice were estimated to be 0.08 microg g to 0.13 microg g and approximately 2 g for total Cd intake. Renal dysfunction caused by exposure to Cd was associated with an increased mortality in both regions. The increased total Cd intake and high concentration of Cd in rice also exerts an adverse influence on life prognosis.     

Effect of Breed,Cage Type,and Reproductive Phase on Fecal Corticosterone Levels in Doe Rabbits

Fecal corticosterone concentration (FCC) is increasingly being used as a noninvasive indicator of stress in assessment of nonhuman animal welfare. The aim of this study was to evaluate effects of breed, cage type, reproductive phase, and their interactions on FCC levels in doe rabbits. A total of 252 doe rabbits were randomly assigned to 2 groups. Does were individually housed in either standard dimension cages (SC) or in cages with a volume more than double that of the SC. Bigger cages (BC) were equipped with a plastic foot mat. Breed, cage type, and reproductive phase significantly affected FCC. New Zealand hybrids showed higher FCCs (p < .001) when compared witho the autochthonous breed (27.77 ± 0.47 vs. 24.61 ± 0.36 pg g^?1, respectively). Increased cage size coupled with a plastic foot mat resulted in a significant decrease in doe FCC. The highest FCCs were detected at partum (BC: 30.40 ± 0.81 pg g^?1; SC: 33.36 ± 0.86 pg g^?1; p ≤ .05), followed by postweaning (BC: 25.09 ± 0.95 pg g^?1; SC: 27.63 ± 0.95 pg g^?1; p ≤ .05). These results support the hypothesis that measurement of FCC provides a useful indicator of chronic stress in doe rabbits.     

The sexually transmitted insect virus,Hz-2V

Hz-2V is one of only a very few sexually transmitted viruses currently known in insects. Replication of this insect pathogenic virus results in sterility of infected moths rather than mortality. The sterility of the infected host is a consequence of virus directed malformation of adult reproductive tissues, which in females results in cellular proliferation and hypertrophy of these tissues. Virus replication has additional ramifications in infected females. Infected females produce more mating pheromones and attract more mates than healthy females, ultimately facilitating virus transmission and enhancing viral fitness. The molecular mechanisms used by the virus to manipulate the host to enhance its fitness are yet to be determined. Unraveling the underlying principles of these mechanisms promises to enhance our understanding of insect reproductive physiology, as well as provide molecular tools for use in novel approaches in sterile insect control programs.     

Life history strategy and egg diapause in the intertidal collembolan Anurida maritima

ABSTRACT.

• 1 In a field survey of 1 year the intertidal collembolan Anurida maritima (Guérin) was found to be a univoltine species. Every year in early May a new generation emerges from eggs that overwinter. The first animals become adult in July. Almost all eggs laid in summer do not hatch, but undergo a period of diapause. Diapause is terminated in autumn by temperatures below 5°C. However, due to the low temperatures in winter further egg development is suppressed until spring.
• 2 The adult animals die, mainly in autumn. One of the causes of mortality may be starvation. In late autumn body size decreases and glycogen and lipid content are lower.
• 3 It is argued that in autumn due to low temperatures A.maritima, which forages during low tide on the open shore and seeks refuge underground before the incoming tide, is too sluggish to find food in the limited period of low water. This probably explains why this cosmopolitan species has developed a strategy to survive the winter in the temperate zone in the egg stage.