昆虫

五大连池老黑山和火烧山两座新期火山被计划为猎奇目标。进入老黑山脚下,对山下零星的植物与地面进行仔细搜索没有找到什么新奇的昆虫。裸露的熔岩上几只直翅目蝗虫蹦蹦跳跳地活动着．大致能看到它们的落点却又不见踪影。仔细寻找,原来它们有很好的保护色．周身深灰黑色．与熔岩石极其相似真的让人很难想象．它们是通过什么样     

Insects in hypoxia

Insects exhibit a remarkable array of adaptations that allow them to handle more or less severe hypoxia associated with numerous aquatic and terrestrial habitats. We consider these habitats and then discuss physiological, behavioral and morphological mechanisms that facilitate insect life under oxygen deprivation. Actually or potentially hypoxic habitats include aquatic systems, flood-prone soils and burrows, intertidal zones, ice encasement and high altitudes. Some microhabitats, including dung, carrion, mammalian alimentary canals, grain and wood, also are subject to hypoxia. Adaptations to hypoxia include the ability to switch from aerobic to anaerobic metabolic pathways (with attendant generation of end products), the ability to drastically attenuate basal metabolic rates, altered behaviors and enlarged tracheal system volumes. Research into the biology of hypoxia seems to be progressing from early observations of the abilities of some insects to withstand exposure to hypoxia or anoxia through studies of organismal mechanisms operating in hypoxia to detailed investigations of cellular and intracellular signaling processes. Our hope is this essay will help crystallize the emergent picture of this area for those interested in contributing to future research.     

Enterococci in Insects

Enterococci were obtained from 213 of 403 insects cultured during a 14-month period, in numbers from 10³ to 3 × 10⁷/g of insect. Insects were taken only from nonurban, wild, and cultivated fields and woods. In species of insects carrying them, enterococci were not always present in every individual cultured, and often more than one species of enterococcus occurred within a species. Enterococci were obtained from certain insects taken in the field during the dormant season, suggesting their role as overwintering agents. They were generally present in species feeding on nectar, succulent plant parts, and on and ir forest litter, but not from insects feeding on less succulent leaves and stems. Streptococcus faecalis was recovered from 32%, Streptococcus faecium from 22.4%, and Streptococcus faecium var. casseliflavus from 43.5% of members of the 37 taxa of insects. S. faecalis and S. faecium var. casseliflavus exhibit a high percent of conformity to the properties published for them. The heterogeneity in properties of S. faecium is similar to that found for the species taken from plants. Many fail to grow in broth at 45 C or in broth containing 6.5% NaCl; 50% of the cultures ferment both melezitose and melibiose, and a few ferment neither sugar. The remainder ferment melibiose only. Failure to reduce methylene blue in milk by S. faecalis and S. faecium is correlated with the inability to ferment lactose. More than 93% of the cultures of S. faecalis digest casein in milk from the top downward, following the production of a soft, flowing curd. Because this property is not characteristic of S. faecalis taken from humans, the reaction in litmus milk is suggested as a means of differentiation between cultures of remote and innocent origin in nature and recent, human pollution.     

Enterococci in Insects

Enterococci were obtained from 213 of 403 insects cultured during a 14-month period, in numbers from 10(3) to 3 x 10(7)/g of insect. Insects were taken only from nonurban, wild, and cultivated fields and woods. In species of insects carrying them, enterococci were not always present in every individual cultured, and often more than one species of enterococcus occurred within a species. Enterococci were obtained from certain insects taken in the field during the dormant season, suggesting their role as overwintering agents. They were generally present in species feeding on nectar, succulent plant parts, and on and ir forest litter, but not from insects feeding on less succulent leaves and stems. Streptococcus faecalis was recovered from 32%, Streptococcus faecium from 22.4%, and Streptococcus faecium var. casseliflavus from 43.5% of members of the 37 taxa of insects. S. faecalis and S. faecium var. casseliflavus exhibit a high percent of conformity to the properties published for them. The heterogeneity in properties of S. faecium is similar to that found for the species taken from plants. Many fail to grow in broth at 45 C or in broth containing 6.5% NaCl; 50% of the cultures ferment both melezitose and melibiose, and a few ferment neither sugar. The remainder ferment melibiose only. Failure to reduce methylene blue in milk by S. faecalis and S. faecium is correlated with the inability to ferment lactose. More than 93% of the cultures of S. faecalis digest casein in milk from the top downward, following the production of a soft, flowing curd. Because this property is not characteristic of S. faecalis taken from humans, the reaction in litmus milk is suggested as a means of differentiation between cultures of remote and innocent origin in nature and recent, human pollution.     

Insects on the rise

The Insect Genomics Workshop was held in Arlington, Virginia, from 28 to 30 October 2001.     

昆虫私生活

大象、老鼠以及我们人类均属脊椎动物。主要依靠巧妙的内骨架支持身体任意自由的活动，而节肢动物有个共同的特性，具有外骨骼，起着保护内脏，支持身体，着生肌肉等作用。无论哪一种动物都是经过胚胎发育等一系列过程而走向成熟，也就是说，从小到大由不完全趋于完全，但脊椎动物看似在渐渐长大，外观上并没有很大的变化，其实质是细胞分裂增值的结果，老的细胞死去，新的细胞诞生。     

Ecdysone Metabolism in Insects

The current status of the pathway of ecdysone biosynthesis andinactivation in insects is discussed. Evidence is presenteddemonstrating that rß-ecdysone is generated from -ecdysoneby fat body, Malpighian tubules, gut, and body wall, but notby blood, oenocytes, muscle, salivary gland, or the prothoracicgland itself (in vitro experiments with prepupal Manduca sextatissues). Since -ecdysone does not appear to have demonstrablehormonal activity at physiological concentrations in in vitrotissue systems which cannot metabolize it to rß-ecdysone,it is suggested that -ecdysone serves as a prohormone ratherthan as a hormone. The role of the prothoracic gland in theproduction of -ecdysone remains to be defined.     

Ecdysteroid Metabolism in Insects

SYNOPSIS. Remarkable development in ecdysone research has beenachieved during this decade in terms of organic chemistry, biochemistryand physiology, although the problems concerning the actionand behavior of ecdysteroids in target cells still remain tobe solved. To elucidate the dynamics of secretion, action andinactivation of ecdysone, the metabolic pathways for ecdysteroidshave been examined in several insect species and are summarizedhere. There may be at least three major inactivation processesfor ecdysone, namely, (i) catabolic degradation, (ii) conjugateformation and (iii) epimerization to 3-epi-ecdysteroids through3-dehydro compounds. Two means of regulation of the ecdysonetiter to ensure normal development of insects are seen in Sarcophaga:(1) Enhanced epimerization of 20-hydroxyecdysone at the prepupalstage resulting in a decreasing titer of biologically activeecdysteroids. (2) Reactivation of a conjugate at the onset ofadult development (a stage with an increasing titer of biologicallyactive ecdysteroids).     

Wound Responses in Insects

For over a century, the study of specific antipathogenic strategiesin insects has been confounded by non-specific responses tointegumental invasion. Experimental injury to diapausing Hyalophoracecropia silkmoth pupae elucidated some of the events inherentin this response—increased oxygen consumption and DNAand RNA synthesis leading to de novo synthesis of proteins,some of which are constituents of the adult protein cohort aswell as some injury-specific ones. The mechanism which enforcesdiapause is apparently released by integumental injury as wellas by normal developmental stimuli. Recent work has concentratedon purification of antipathogenic and injury-specific proteins,the possible involvement of lectins in the immune response,and localization of synthesis of these proteins in hemocytesand fat body cells. At least ten different hemolymph proteinswhich are synthesized by fat body cells in response to inoculationof lepidopteran species with bacteria currently are being isolated.The hemolymph of H. cecropia contains lectins which are synthesizedby hemocytes. Analysis of in vitro incorporation of ['H]leucineby hemocytes into proteins reveals that these lectins apparentlyare not constituents of the secreted injury response proteincomplex in fifth instar caterpillars or diapausing pupae, norare hemolymph lectin titers significantly different in healthyversus diseased or injured animals. However, intracellular lectinconcentrations may increase upon injury. Increased lectin titerand induction of bactericidal activity coincide in another holometabolousspecies, the fleshfly Sarcophaga peregrina. Pursuit of thesestudies may elaborate our knowledge of insect cellular immunity.