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Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M
0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M
0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M
1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (L
f+t; mm) of the femur and tibia of the hind leg, L
f+t = 34.9M
0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur''s cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur''s cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight. 相似文献
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A method is described for isolating bovine fibrinopeptide B (bFPB) in a highly purified form from crude bovine fibrinogen, using ion-exchange chromatography on DEAE cellulose. Desulphated bFPB (designated DSbFPB) was prepared by treatment of the product with acid. After incubating DSbFPB with [35S]PAPS, in the presence of a particulate preparation from neuroblastoma-glioma hybrid cells, radioactivity was incorporated into a product identified as [35S]bFPB from its position of elution on reverse-phase HPLC. The possible significance of this observation is discussed. 相似文献
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Two strains of Drosophila melanogaster represent the extremes in resistance and sensitivity to the lethal effects of CdCl2. The strain containing the mutations vermilion and brown (v; bw) and the strain Austin had LC50's of 3.3 and 1.3mm CdCl2, respectively. The three major chromosomes from these two strains were assorted genetically into the six possible combinations. The measured LC50's for CdCl2 for these six genotypes fell into two groups according to the X chromosome; those containing the X chromosome from v; bw had LC50's 0.5–1.0mm greater than those in which the X chromosome was from Austin. Since the parent strains differed by 2mm, we suggest that the X chromosome is a major, but not the sole, site of genes to produce resistance to CdCl2. When 109Cd was in the diet the uptake by v; bw and Austin over 2 days was the same. After 4 days of uptake, the Austin strain excreted the 109Cd five times faster than v; bw but the six genotypes did not differ appreciably in excretion rate from one another and resembled the sensitive parent Austin more than the resistant one. Thus a second process is indicated that distinguishes resistance to CdCl2 that apparently is not associated with the X chromosome.This research was sponsored by the Office of Health and Environmental Research, U.S. Department of Energy, under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems, Inc. 相似文献
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A. B. Christie 《BMJ (Clinical research ed.)》1969,1(5647):833-834
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George A. Christie 《Histochemistry and cell biology》1967,10(3):272-277
Summary The distribution of an enzyme, or enzymes hydrolysing l-leucyl--naphthylamide is studied in the placentae, foetal membranes, and uterine structures of the horse, sheep, cat, dog, ferret, rat, rabbit, guinea-pig, and human. Activity is seen mainly in the trophoblast (except that of the cat, dog, and guinea-pig), in the rodent yolk-sac endoderm (except that of the rat), or in the uterine epithelium — surface (sheep and guinea-pig) or glandular (dog). The presence of the enzyme or enzymes is correlated with possible functions in absorption and transport of materials, or in elaboration and release of complex molecules. 相似文献