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Energy storage in arthropods has important implications for survival and reproduction. The lipid content of 276 species of adult arthropods with wet mass in the range 0.2–6.13 g is determined to assess how lipid mass scales with body mass. The relative contribution of lipids to total body mass is investigated with respect to phylogeny, ontogeny and sex. The lipid content of adult insects, arachnids, and arthropods in general shows an isometric scaling relationship with respect to body mass (M) (Marthropod lipid = ?1.09 ×Mdry1.01 and Marthropod lipid = ?1.00 ×Mlean0.98). However, lipid allocation varies between arthropod taxa, as well as with sex and developmental stage within arthropod taxa. Female insects and arachnids generally have higher lipid contents than males, and larval holometabolous insects and juvenile arachnids have higher lipid contents than adults. 相似文献
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ANN H. SZYSZKO BESSEMARIE L. PRAZAK CHARLES F. EHRET WILLIAM J. EISLER JOHN J. WILLE 《The Journal of eukaryotic microbiology》1968,15(4):781-785
SYNOPSIS. A multi-unit automatic sampling device for investigation of microbial growth under a wide variety of conditions is described. The kinetics of asynchronous population growth for batch cultures of Tetrahymena pyriformis (W) at several temperatures show that there are 2 distinct growth phases: an exponential ultradian growth phase that is strongly temperature dependent and a non-stationary growth phase, the infradian phase, that shows little or no temperature dependence over the range from 15–27 C. 相似文献
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Abstract. Anopheles stephensi mosquitoes which had fed upon mice infected with Plasmodium yoelii nigeriensis malaria parasites produced significantly fewer eggs than mosquitoes fed on an uninfected mouse. Fecundity reduction was more pronounced when the bloodmeal contained malaria gametocytes and the mosquitoes developed oocysts. Egg production and haematin excretion were correlated for uninfected bloodfed mosquitoes; the presence of P.y. nigeriensis in the blood affected this relationship. Reduced fecundity was associated with a significant reduction of bloodmeal size (measured by haematin excretion) in mosquitoes which ingested gametocytaemic blood. The bloodmeal size in mosquitoes fed on parasitaemic blood without gametocytes was not significantly reduced. The use of haematin assays for determination of bloodmeal size in mosquitoes is discussed. 相似文献
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Spinal Mechanisms in the Control of Lamprey Swimming 总被引:1,自引:0,他引:1
SYNOPSIS. The lamprey, an anguilliform fish, swims using lateralundulatory movement; a transverse wave passes backward, fromhead to tail, the amplitude of the wave increasing as it movestailward. The wave of muscle activity producing this movementtravels down the body faster than the mechanical wave. The wayin which certain features of anguilliform movement contributeto its efficiency have been described. The neural activity underlyingswimming is characterized by: 1) rhythmical alternation betweenthe two sides of a single segment; 2) a burst duration thatremains a constant proportion of the cycle time and is independentof the cycle frequency; 3) rostrocaudal phase lag that is constantand also independent of the cycle frequency. Local circuitsin the lamprey spinal cord can generate this locomotory patternin the absence of sensory feedback following activation of excitatoryamino acid receptors; the pattern is centrally generated. Ithas been hypothesized that the spinal central pattern generatorfor locomotion consists of a series of segmental burst generatorscoupled together by an intersegmental coordinating system. Theintersegmental coordinating system functions to keep the frequenciesof the oscillators along the cord constant and to provide theappropriate rostrocaudal phase lag. Mechanosensitive units withinthe spinal cord are sensitive to movement of the spinal cord\notochordand movement of the spinal cord/notochord can entrain the burstpattern. Entrainment occurs through movement-related feedbackonto neurons at the local level. The possible roles this movement-relatedfeedback plays during locomotion are discussed. 相似文献
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Nucleoside diphosphate kinase (NDP kinase) from Paramecium was purified to homogeneity. The native enzyme was 80 kDa (by gel filtration), with subunits of 18 and 20 kDa. Near the amino terminus, 15 of 20 residues were identical with those in human NDP kinase, and 17 of 20 with the awd gene product from Drosophila. NDP kinase bound α-labeled ATP and GTP, and a photoreactive GTP analog labeled both subunits. Purified NDP kinase underwent autophosphorylation on a histidine and a serine residue using either ATP or GTP as a substrate. The enzyme also catalyzed acid-stable phosphorylation of casein and phosvitin. This protein kinase activity is distinct from the histidine phosphorylation that is part of the NDP kinase catalytic cycle. Antiserum against the purified protein from Paramecium cross-reacted with 16- to 20-kDa proteins in most species tested, and with a larger protein (44 kDa) in Paramecium, Xenopus, and two human lines. The multiple forms (20 and 44 kDa) of the NDP kinase in Paramecium and its protein kinase activity, suggest that the protein is more than a housekeeping enzyme; it may have regulatory roles such as those of the NDP kinase-like awd protein of Drosophila and Nm23 protein of humans. 相似文献
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Microsporidian Spore Discharge and the Transfer of Polaroplast Organelle Membrane into Plasma Membrane 总被引:3,自引:0,他引:3
EARL WEIDNER WILLIAM BYRD ANN SCARBOROUGH JOHN PLESHINGER DAVID SIBLEY 《The Journal of eukaryotic microbiology》1984,31(2):195-198
Electron microscopic examinations of Glugea hertwigi and Spraguea lophii spores indicated the presence of a single plasma membrane; however, this membrane remained in the spore during the discharge of the sporoplasm from the spore. Although discharged spores retained the old plasma membrane, the extruded sporoplasms acquired a new plasma membrane. In order to determine where the new plasma membrane came from, we used two fluorescent probes with membrane affinities. The markers were tested on unfired and discharged spores. The probe, N-phenyl-1-naphthylamine (NPN), labeled the polaroplast membrane in addition to the apolar groups in the posterior vacuoles of unfired spores. After spore discharge, NPN label disappeared from the spore ghosts except for a slight fluorescence on residual plasma membranes. Much of the NPN-labeled membrane reappeared after spore discharge on the outer envelope of discharged sporoplasms. The probe chlorotetracycline (CTC) labeled calcium-associated membranes of spore polaroplasts. During spore discharge, the CTC fluorescence shifted from the polaroplast organelle of unfired spores to the outer envelope of discharged sporoplasms. These results indicate that the polaroplast organelle may provide the new plasma membrane for discharged microsporidian sporoplasms. 相似文献