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41.
Lawrence G. Harshman Ary A. Hoffmann Timothy Prout 《Evolution; international journal of organic evolution》1988,42(2):312-321
The effects of density and food on remating were investigated using Drosophila melanogaster. The frequency of remating was unaffected by density for some combinations of fly strains but was reduced at low relative densities for other combinations. Until females had used most of their stored sperm, remating was less likely when food was absent or contact with food was prevented. Food availability had little effect on the incidence of remating once stored sperm were depleted and had no effect on initial virgin mating frequency. This study indicates that environmental factors can have a substantial direct influence on the frequency of remating in populations of Drosophila melanogaster. 相似文献
42.
Regulation of juvenile hormone esterase gene expression in the tobacco budworm (Heliothis virescens)
V J Wroblewski L G Harshman T N Hanzlik B D Hammock 《Archives of biochemistry and biophysics》1990,278(2):461-466
The tissue distribution, developmental control, and induction of juvenile hormone esterase (JHE) mRNA was examined in Heliothis virescens using an 800-base pair fragment of a JHE cDNA clone. Northern hybridization analysis of poly(A)+RNA from fat body and integument of fifth stadium larvae indicated the presence of a single JHE mRNA species having an estimated length of 3 kilobases. On Day 2 of the fifth stadium (L5D2), basal JHE mRNA levels were 3-fold higher in the integument than the fat body, which correlated with the higher specific activity of the enzyme in the integument at this time. However, JHE mRNA levels in the fat body on Day 4 of the fifth stadium were 9-fold higher than on Day 2, while mRNA levels in the integument remained the same. This endogenous increase in JHE mRNA and activity in the fat body occurred at the time of peak hemolymph JHE activity. JHE mRNA was not detected in third stadium larvae which have very low levels of JHE activity. Treatment of L5D2 larvae with the juvenile hormone mimic epofenonane resulted in a 7- and 14-fold increase in the level of JHE mRNA in the integument and fat body, respectively. The mRNA induced in both tissues was of the same estimated length as the constitutively expressed message. The data indicate that the developmental regulation and induction of JHE can occur at the level of mRNA. There is evidence that the fat body secretes more JHE than does the integument and could be the major source of hemolymph JHE. 相似文献
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T N Hanzlik Y A Abdel-Aal L G Harshman B D Hammock 《The Journal of biological chemistry》1989,264(21):12419-12425
48.
Salmon AB Marx DB Harshman LG 《Evolution; international journal of organic evolution》2001,55(8):1600-1608
Little is known about physiological mechanisms that underlie the cost of reproduction. We tested the hypothesis that stress susceptibility is a cost of reproduction. In one test of our hypothesis, Drosophila melanogaster females were exposed to a juvenile hormone analog (methoprene) to stimulate egg production followed by stress assays. A sterile stock of D. melanogaster was employed as a control for reproduction. Exposure of fertile females to methoprene resulted in an increase in female reproduction and increased susceptibility to oxidative stress and starvation (compared to solvent controls). Sterile females did not exhibit a decrease in stress resistance. Mating also stimulated egg production. As a second test of our hypothesis, mated females were compared to virgin females. Mated fertile females were relatively susceptible to oxidative stress, but this relationship was not evident when mated and virgin sterile females were compared. The results of the present study support the hypothesis that stress susceptibility is a cost of reproduction. 相似文献
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Luca Santuari Sylvain Pradervand Amelia-Maria Amiguet-Vercher Jerôme Thomas Eavan Dorcey Keith Harshman Ioannis Xenarios Thomas E Juenger Christian S Hardtke 《Genome biology》2010,11(1):R4
Identification of small polymorphisms from next generation sequencing short read data is relatively easy, but detection of
larger deletions is less straightforward. Here, we analyzed four divergent Arabidopsis accessions and found that intersection of absent short read coverage with weak tiling array hybridization signal reliably
flags deletions. Interestingly, individual deletions were frequently observed in two or more of the accessions examined, suggesting
that variation in gene content partly reflects a common history of deletion events. 相似文献