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41.
Alan M. Nevill Roger Ramsbottom Clyde Williams 《European journal of applied physiology and occupational physiology》1992,65(2):110-117
This paper examines how selected physiological performance variables, such as maximal oxygen uptake, strength and power, might best be scaled for subject differences in body size. The apparent dilemma between using either ratio standards or a linear adjustment method to scale was investigated by considering how maximal oxygen uptake (l.min-1), peak and mean power output (W) might best be adjusted for differences in body mass (kg). A curvilinear power function model was shown to be theoretically, physiologically and empirically superior to the linear models. Based on the fitted power functions, the best method of scaling maximum oxygen uptake, peak and mean power output, required these variables to be divided by body mass, recorded in the units kg 2/3. Hence, the power function ratio standards (ml.kg-2/3.min-1) and (W.kg-2/3) were best able to describe a wide range of subjects in terms of their physiological capacity, i.e. their ability to utilise oxygen or record power maximally, independent of body size. The simple ratio standards (ml.kg-1.min-1) and (W.kg-1) were found to best describe the same subjects according to their performance capacities or ability to run which are highly dependent on body size. The appropriate model to explain the experimental design effects on such ratio standards was shown to be log-normal rather than normal. Simply by taking logarithms of the power function ratio standard, identical solutions for the design effects are obtained using either ANOVA or, by taking the unscaled physiological variable as the dependent variable and the body size variable as the covariate, ANCOVA methods. 相似文献
42.
Summary We studied the influence of diet composition and breadth on the subsequent acceptability of three novel plants to sixth instarSchistocerca americana. Rearing diets of equal breadth differing in composition, and diets differing in breadth, significantly altered first meal length on some but not all of the test plants. These effects on palatability altered and at times reversed the palatability hierarchy of insects reared on different diets. The effects of rearing insects on broad diets were not produced by exposure to the plant odors alone, but apparently required contact with a diversity of plants while feeding. Switching diets for 24 h prior to testing did not alter preferences induced by rearing diets. The relationship of these patterns to induced preferences in other insects, and some possible mechanisms for generating induced preferences, are discussed. 相似文献
43.
DDT resistance in Anopheles gambiae declines with mosquito age 总被引:1,自引:1,他引:0
Adult Anopheles gambiae Giles mosquitoes from Zanzibar were tested on a standard discriminating dose of DDT which reliably kills susceptible mosquitoes. Adults from wild-caught larvae reared in the laboratory, and from the F1 progeny of wild-caught adults, showed less than 5% test mortality when newly-emerged, but mortality rose with age to over 90% when they were 12-14 days old. Wild-caught mixed-age adults showed an intermediate mortality rate of 25%, close to the rate predicted from laboratory results for a fully resistant population with an age-structure typical of this species in natural conditions. It is inferred that older, genetically resistant insects may be scored as susceptible, so that routine susceptibility tests with wild-caught adults underestimate the frequency of resistance. In Zanzibar, such tests probably helped to persuade spraying authorities to continue spraying DDT in spite of resistance. Resistance which is restricted to younger insects may nonetheless reduce the effectiveness of spraying. 相似文献
44.
The effects of solar and artifical ultraviolet radiation on the marine cryptoflagellate, Cryptomonas maculata, were studied. Even after short exposure to UV the accessory photosynthetic pigment phycoerythrin is bleached; likewise the fluorescence undergoes significant changes both in amplitude and in the maximal peak wavelength. In parallel, the photosynthetic oxygen production decreases rapidly during exposure. Gel electrophoresis and FPLC of membrane proteins show a significant decrease in chromoproteins after 2 h UV, which is confirmed by fluorescence excitation and emission spectra of the FPLC fractions.Abbreviations APS
ammonium persulfate
- DCMU
3-(3,4dichlorophenyl)1,1-dimethylurea; Emulphogen, polyoxyethylene 10 tridecyl ether
- FPLC
fast protein liquid chromatography
- PMSF
phenylmethylsulfonyl fluoride
- SDS
sodium dodecylsulfate
- SDS PAGE
sodium dodecylsulfate polyacrylamide gel electrophoresis
- TEMED
NN NNtetramethylethylene diamine
- UV-A
wavelength range between 320 nm and 400 nm
- UV-B
wavelength range between 280 nm and 320 nm
Dedicated to the 60th birthday of Professor Dr. W. Wehrmeyer 相似文献
45.
46.
Dramatic founder effects in Amerindian mitochondrial DNAs 总被引:33,自引:0,他引:33
Southwestern American Indian (Amerindian) mitochondrial DNAs (mtDNAs) were analyzed with restriction endonucleases and found to contain Asian restriction fragment length polymorphisms (RFLPs) but at frequencies very different from those found in Asia. One rare Asian HincII RFLP was found in 40% of the Amerindians. Several mtDNAs were discovered which have not yet been observed on other continents and different tribes were found to have distinctive mtDNAs. Since the mtDNA is inherited exclusively through the maternal lineage, these results suggest that Amerindian tribes were founded by small numbers of female lineages and that new mutations have been fixed in these lineages since their separation from Asia. 相似文献
47.
Genotype dependent variation in mycorrhizal colonization and response to inoculation of pearl millet
Summary Genotypes of pearl millet (Pennisetum americanum L. Leeke) were examined for differences in vesicular-arbuscular mycorrhizal (VAM) colonization and response to inoculation. For thirty genotypes tested across three field locations there was a range of mycorrhizal colonization intensity between 25 and 56%. In another experiment with two male-sterile lines, restorer lines and their derived crosses, grown in pots filled with non-sterilized soil there were significant differences between genotypes for colonization by mycorrhiza. This showed hostgenotype dependence for mycorrhizal colonization.Root growth rates, mycorrhizal root length, percentage root colonization and plant growth and P uptake were studied in ten genotypes. A set of 3 genotypes with similar root lengths varied significantly with regard to mycorrhizal root length and the percentage colonization. This supports the suggestion that VAM colonization and spread is dependent on the host genotype. The growth responses differed significantly between the genotypes and they also differed in their responses to P uptake and VAM inoculation. The utility of host-genotype dependent differences in VAM symbiosis in plant breeding is discussed.Journal Article No. 453 相似文献
48.
Wolfgang Löscher Gerhard Böhme Frank Müller Sonia Pagliusi 《Journal of neurochemistry》1985,45(3):879-889
A procedure is described for the rapid preparation of nerve ending particles (synaptosomes) from 11 regions of one rat brain. The synaptosomal fractions have been characterized by electron microscopy and determination of four marker enzymes, i.e., glutamate decarboxylase (GAD), acetylcholinesterase, succinate dehydrogenase, and glycerol 3-phosphate dehydrogenase. Comparison with a much lengthier standard (Ficoll-sucrose) preparation showed that the synaptosomal yield of the new procedure was substantially better as judged by both morphological evaluation and protein recovery. The improved synaptosome preparation was used for determination of regional gamma-aminobutyric acid (GABA) levels in synaptosomal fractions. The postmortem increase in GABA level during removal and dissection of brain tissue and homogenization and fractionation procedures could be minimized by rapid processing of the tissue at low temperatures and inclusion of the GAD inhibitor 3-mercaptopropionic acid (3-MP; 1 mM) in the homogenizing medium. The addition of GABA (0.2 mM) to the homogenizing medium did not alter the GABA levels in the synaptosomes, indicating that no significant redistribution of GABA occurred during subcellular fractionation in sodium-free media. Synaptosomal GABA levels determined in the 11 rat brain areas showed the same regional distribution as the GABA-synthesizing enzyme GAD. On the basis of these findings, it was suggested that the synaptosome preparation could be used to evaluate the in vivo effects of drugs on nerve terminal GABA. Treatment of rats with a convulsant dose of 3-MP (50 mg/kg i.p.) 3 min before decapitation significantly lowered synaptosomal GABA levels in olfactory bulb, hippocampus, thalamus, tectum, and cerebellum. The 3-MP-induced seizures and reduction of GABA levels could be prevented by administration of valproic acid (200 mg/kg i.p.) 15 min before the 3-MP injection. The data indicate that the improved synaptosome preparation offers a convenient method of preparing highly purified synaptosomes from a large number of small tissue samples and can provide useful information on the in vivo effects of drugs on regional GABA levels in nerve terminals. 相似文献
49.
Y. Heslop-Harrison B. J. Reger J. Heslop-Harrison 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(3):252-258
Summary Foreign pollen tubes in the stigma of Zea mays can be prevented from reaching the ovary cavity by the unusual length of the pollen tube pathway. A simple and rapid procedure is described for overcoming this difficulty by pollinating the basal parts of the stigmas without removing the ensheathing bracts (husks). The method maintains high humidity in the vicinity of the ovaries, and by conserving photosynthetic tissues probably also ensures a more normal O2 /CO2 balance in the neighbourhood of the stigmas than do bagging procedures. It is shown that Sorghum pollen tubes readily reach the ovary after pollination by the method. Their presence induces some of the characteristic post-pollination effects caused by Zea pollen tubes, but they frequently also stimulate premature enlargement of the nucellus and lysis of nucellar cells. Although Sorghum tubes have been traced across the inner ovary wall, they have not been seen to enter the micropyle, and hybrid embryos have not yet been obtained. 相似文献
50.
C. Hagger 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(5):555-560
Summary Seven highly inbred lines of White Leghorn chickens were used in a near complete diallel mating plan during eight years. The lines originated from three different base populations selected for egg weight. Average inbreeding coefficients of parents of chicks hatching in successive years were 0.75, 0.80, 0.84, 0.86, 0.89, 0.91, 0.93 and 0.94. The composition of line, specific combining ability and reciprocal effects and their estimated values are given. These effects were estimated for age at first egg (AFE), average weight of all eggs laid to 40 weeks (EW40), body weight at 40 weeks (BW40), number of eggs to 40 weeks (EP40) and number of eggs between 41 and 60 weeks (EP60). Records of 3247 hens surviving to 40 weeks and of 3133 birds to 60 weeks could be used. Large differences between line effects could be found in all traits. They were only partly due to the preceding selection in the base populations. All specific combining effects were in the expected direction, negative for AFE and positive for EW40, BW40, EP40 and EP60. Recovery of inbreeding depression inflated these effects rather substancially. Average heterosis, defined as the relative superiority of a line combination over the mid parent value, was –11.3%, 5.8%, 7.8%, 45.1% and 35.8% for AFE, EW40, BW40, EP40 and EP60 respectively. One line showed a relative superiority in AFE of -19.3% compared to about –7.9% for all other combinations. Reciprocal or sex-linked effects were generally smaller in all traits than specific combining effects, they were considerably smaller in AFE, EP40 and EP60. General reciprocal effects could be found for several lines in one or more traits. Offspring of two lines, when used as sire lines, showed a negative correlation between reciprocal effects of egg weight and body weight. 相似文献