The influence of animals on phosphorus cycling in lake ecosystems

Aquatic animals directly influence the cycling of phosphorus in lakes through feeding and excretion. Traditionally, animals (zooplankton, benthic invertebrates and fish) have been assigned only minor roles in the process of freshwater phosphorus cycling. They were regarded as consumers without much regulating influence. Today there is growing evidence that animals, predators and herbivores, directly or indirectly can control biomass of primary producers and internal cycling of phosphorus.This paper summarizes different mechanisms of transformation and translocation of phosphorus via different groups of organisms.     

Ornithine decarboxylase activity in embryos depends on temperature of development rather than on the stage of development. Molecular adaptation to temperature changes in poikilothermic animals.

An unknown amino sugar, U-7, which had been detected in the hydrolysate of the polysaccharide fraction (F-A) of Pseudomonas aeruginosa P14 lipopolysaccharide, was isolated from the hydrolysate of whole cells of this micro-organism and converted into the N-acetyl derivative (U-7NAc). On the basis of i.r.-absorption spectrometry, 13C-n.m.r. and 1H-n.m.r. spectroscopy and mass spectrometry, the structure of compound U-7NAc was identified as 2-acetamido-3-amino-2,3-dideoxyhexofuranurono-6,3-lactam. The configuration of compound U-7NAc was then unequivocally identified as 2-acetamido-3-amino-2,3-dideoxy-D-glucofuranurono-6,3-lactam by comparing the synthetic and natural compounds. Compound U-7 and synthetic 2,3-diamino-2,3-dideoxy-D-glucofuranurono-6,3-lactam showed the same behaviour on chromatography. G.l.c.--mass-spectral analyses of fraction F-A and synthetic 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid after methanolyses and trimethylsilylations showed the presence of the same derivative. It was concluded that the amino sugar U-7 was produced from the 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid residue present in fraction F-A.     

The central role of the haemolymph in the regulation of nutrient intake in insects

Abstract. A synthesis is presented for the control of nutrient intake in insects. The haemolymph plays a central role and provides a constantly updated summary of nutritional state. Various ways are discussed in which haemolymph parameters are directly and indirectly linked to the three key aspects of feeding behaviour: food location, food selection and ingestion.     

高温对家蚕三品系血淋巴中糖水平的影响（英文）

家蚕Bombyx mori的两个二化性品系热耐受型NB4D2和热敏感型CSR2均适合于温带气候,而多化性的PM（Pure Mysore) 品系适合于热带气候,将这3种品系5龄幼虫分别置于32℃和36℃的高温下,观察高温对其5龄幼虫至蛹期血淋巴中糖含量及海藻糖酶活性的影响。结果表明： PM幼虫和蛹的死亡率均小于NB4D2和CSR2。在蜕皮期间血淋巴海藻糖水平较高,而葡萄糖水平及海藻糖酶活性较低。32℃和36℃的高温下,幼虫蜕皮期间血淋巴中糖含量及海藻糖酶活性仅在其各自的水平上表现为小幅度的增加。蜕皮后幼虫血淋巴中海藻糖含量显著下降,而葡萄糖含量和海藻糖酶活性显著上升。在较高温度下,蜕皮后幼虫血淋巴中海藻糖含量下降幅度更大,而葡萄糖含量及海藻糖酶活性上升水平也更加显著。25±1℃下取食幼虫血淋巴中葡萄糖含量显著下降,海藻糖含量显著上升;3℃和36℃下PM 和NB4D2取食幼虫血淋巴葡萄糖和海藻糖含量以及海藻糖酶活性增加,而CSR2均减少或降低。吐丝幼虫血淋巴中葡萄糖含量及海藻糖酶活性显著下降,海藻糖小幅度下降。而在较高温度下,耐热型PM 和NB4D2吐丝家蚕血淋巴糖含量含量和海藻糖酶活性明显增加,而热敏感型CSR2的则明显下降。这3种品系蛹发育期的血淋巴糖含量及海藻糖酶活性均下降。在两较高温度下,PM蛹期血淋巴糖和海藻糖酶活性增加,而NB4D2 36℃时增加幅度小于32℃时。对于CSR2,32℃时观察到其血淋巴葡萄糖含量增加,但当环境温度增加到36℃时其血淋巴葡萄糖含量降至正常水平下。然而,当CSR2的蛹置于32℃和36℃时血淋巴海藻糖含量及其酶活性下降,且36℃时下降幅度更大。因此,桑蚕对高温的适应取决于家蚕的品系及发育阶段,并可通过其血淋巴糖及海藻糖酶活性水平进行验证。     

变温对两种昆虫发育速率的影响

报道了松毛虫赤眼蜂和瓜螟在多组恒温、交替变温下的发育历期。对结果的分析表明,温度交替对这两种昆虫在任一温度下的瞬时发育率无明显影响,恒温下和变温下完成发育所需的热量无显著差异或基本相似。     

Tendon fibril rotation under the influence of hydration and temperature changes

Hydration of an isolated rat tail tendon fibril induces its rotation. A similar effect is observed under the influence of temperature changes in the range of 12-38 degrees C. The direction and intensity of the rotation do not depend on the length of a tendon fibril in the range of 12-80 mm. A probabilistic character of the distribution of right- and left-rotating collagen molecules in the tendon was revealed. The direction and intensity of fibril rotation depends on the predominance of the amount of right- and left-rotating collagen molecules. The role of the rotation of collagen bundles in the mechanism of excitation of mechanoreceptors by the action of temperature is discussed.     

The notion of ecological optimum and the determination of this optimum in freshwater poikilothermic animals

The notion of ecological optimum is discussed as related to aquatic poikilothermic animals. Publications on the analysis of the influence of thermal factor on vital functions of invertebrates with the subsequent statement of the general pattern of optimal environmental factors are reviewed. It is concluded that the optimum includes not simply the range of the factor's values on the tolerance curve or the dose of the factor providing for the most favourable life conditions, but the oscillations of the factor within the optimum range, i.e., the astatic optimum, as termed by Prof. A.S. Konstantinov. It is shown, by the example of the influence on organisms and populations of zooplankton of stepwise changes of temperature, increased doses of mineral phosphorus, and low-power laser radiation, that to determine the optimum of an environmental factor it is important to use not only its absolute values and the parameters of cyclic changes, but also the presence or absence of stepwise changes, also determining the direction of the dynamics and the duration of influence of the "dose", as well as the presence and character of the after-effects (inertial action) of the factor on organisms. It is suggested to introduce more detailed and concrete definitions to distinguish between the "static" and then "dynamic" optimum. The former includes the range of optimum values of the factor on the tolerance scale and the "dose" of every factor matching the organism's requirements and providing for the maximum favourable life conditions. The latter includes optimum parameters of cyclic changes (frequency and amplitude) of the factor, along with determining their position in the range of optimum values (at its lower, middle, or upper part), the presence or absence of stimulating effects of stepwise changes of the factor, including the duration of influence of some "dose" of the factor and the order of alteration of the higher and the lower values (dynamics direction), as well as the presence or absence and the character of after-effects (inertial action) of the factor on the organism.     

The influence of various physiological challenges on permanent changes to the cardiovascular system

The concept of fetal programming provides an intellectual framework that links physiological adaptations that occur during development to permanent changes in postnatal regulatory systems. Recent research in the area of cardiovascular programming has highlighted the mechanisms by which these changes exert their effects. The aim of this review is to integrate some of the literature on nutritional changes, exposure to excess glucocorticoids and other challenges during development as they provide support for various mechanisms of programming of the cardiovascular system.