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991.
The behavioural response of Tetranychus urticae to chemical cues from specialist predatory mites, Phytoseiulus persimilis, or generalist predatory bugs, Orius majusculus, on either bean or strawberry was studied in experimental arenas. Predators were placed on the leaf disc for 24 h and removed before T. urticae females were introduced. After 24 h, prey fecundity (number of eggs laid) and dispersal (number of prey drowned in the water barrier) were assessed. Chemical cues from the specialist predator resulted in reduced prey fecundity, significantly different from the generalist predator and control treatments. No interaction effect was found between plant species and prey fecundity, while significantly more eggs were laid on bean than on strawberry. Predator cues irrespective of predator specialization resulted in more prey dispersal than in the control. Findings emphasize the importance of specialization in the predator species complex for the degree and type of antipredator responses and resulting biological control. 相似文献
992.
Folding recombinant spider‐silk in H2O: Effect of osmolytes on the solution conformation of a 15‐repeat spider‐silk mimetic 下载免费PDF全文
Glendon D. McLachlan Babak Gandjian Hind Alhumaidan 《Protein science : a publication of the Protein Society》2016,25(10):1853-1862
The folding of a recombinant spider silk protein‐polymer in the presence of the tri‐methylamine osmolytes TMANO and Betaine in 80% H2O is reported. Circular dichroism measurements (CD) reveal an increase in α‐helical secondary structure with increasing osmolyte concentrations, as determined by an increase in ellipticity at 222 nm. Consistent with this observation, the signal for random coil sampling, observed at 205 nm, is greatly reduced with increasing trimethylamine. Fluorescence spectra of a single tyrosine positioned within the conserved 33‐amino acid repeat primary sequence (of the spider‐silk mimetic) complements the conformational changes observed by CD. Importantly, there is a correlation between the number of Alkyl‐groups (CH3‐) on the amine of the osmolyte and enhanced helicity of the 15‐repeat silk‐mimetic for the osmolytes tested, ie TMANO, Betaine, Sarcosine and Glycine. These preliminary results are applicable to storing and processing recombinant silk sequences in H2O, an important mile‐stone for widespread use of recombinant silk polymers. 相似文献
993.
994.
Two species previously known from East Kazakhstan, Acantholycosa
katunensis Marusik, Azarkina & Koponen, 2004, known from the holotype male, and Acantholycosa
kurchumensis Marusik, Azarkina & Koponen, 2004, syn. n. known from females, are synonymized, and priority is given to Acantholycosa
katunensis. Acantholycosa
katunensis is reported for the first time in the Russian Altai. Both sexes of this species are illustrated, and a distribution map is provided. 相似文献
995.
Thomas E. White Darrell J. Kemp 《Evolution; international journal of organic evolution》2016,70(6):1398-1408
Selection for signal efficacy in variable environments may favor color polymorphism, but little is known about this possibility outside of sexual systems. Here we used the color polymorphic orb‐web spider Gasteracantha fornicata, whose yellow‐ or white‐banded dorsal signal attracts dipteran prey, to test the hypothesis that morphs may be tuned to optimize either chromatic or achromatic conspicuousness in their visually noisy forest environments. We used data from extensive observations of naturally existing spiders and precise assessments of visual environments to model signal conspicuousness according to dipteran vision. Modeling supported a distinct bias in the chromatic (yellow morph) or achromatic (white morph) contrast presented by spiders at the times when they caught prey, as opposed to all other times at which they may be viewed. Hence, yellow spiders were most successful when their signal produced maximum color contrast against viewing backgrounds, whereas white spiders were most successful when they presented relatively greatest luminance contrast. Further modeling across a hypothetical range of lure variation confirmed that yellow versus white signals should, respectively, enhance chromatic versus achromatic conspicuousness to flies, in G. fornicata's visual environments. These findings suggest that color polymorphism may be adaptively maintained by selection for conspicuousness within different visual channels in receivers. 相似文献
996.
997.
【目的】为了进一步明确光照时间对双尾新小绥螨Neoseiulus bicaudus Wainstein生长发育的影响。【方法】在实验室恒温条件下,采用生命表研究方法,研究在不同光照时间下,双尾新小绥螨捕食土耳其斯坦叶螨的生长发育情况。【结果】双尾新小绥螨在不同光照时间段下均能完成世代周期。在光照时数小于12 h时,从卵发育至成螨的各个发育阶段所需时间均呈缩短趋势,当光照时数大于16 h后各个发育阶段所需的时间又呈增长趋势。产卵期在12L︰12D光照时数下最长为20.74 d,且同其他光照条件均存在显著性差异(P<0.05)。产卵后期、寿命、总产卵量均表现在16L︰8D光照时数下最长,分别为11.93 d、31.05 d和42.4粒。双尾新小绥螨种群的净增值率(R_0)在16L︰8D时达到最大值33.88,在8L︰16D时最低为14.97。【结论】光照时间在12~16 h范围内最适合双尾新小绥螨生长发育。 相似文献
998.
Functionalized silk assembled from a recombinant spider silk fusion protein
(Z‐4RepCT) produced in the methylotrophic yeast Pichia pastoris
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Ronnie Jansson Cheuk H Lau Takuya Ishida Margareta Ramström Mats Sandgren My Hedhammar 《Biotechnology journal》2016,11(5):687-699
Functional biological materials are a growing research area with potential applicability in medicine and biotechnology. Using genetic engineering, the possibility to introduce additional functions into spider silk‐based materials has been realized. Recently, a recombinant spider silk fusion protein, Z‐4RepCT, was produced intracellularly in Escherichia coli and could after purification self‐assemble into silk‐like fibers with ability to bind antibodies via the IgG‐binding Z domain. In this study, the use of the methylotrophic yeast Pichia pastoris for production of Z‐4RepCT has been investigated. Temperature, pH and production time were influencing the amount of soluble Z‐4RepCT retrieved from the extracellular fraction. Purification of secreted Z‐4RepCT resulted in a mixture of full‐length and degraded silk proteins that failed to self‐assemble into fibers. A position in the C‐terminal domain of 4RepCT was identified as being subjected to proteolytic cleavage by proteases in the Pichia culture supernatant. Moreover, the C‐terminal domain was subjected to glycosylation during production in P. pastoris. These observed alterations of the CT domain are suggested to contribute to the failure in fiber assembly. As alternative approach, Z‐4RepCT retrieved from the intracellular fraction, which was less degraded, was used and shown to retain ability to assemble into silk‐like fibers after enzymatic deglycosylation. 相似文献
999.
1000.
Fumiki Takahashi 《Population Ecology》1968,10(1):54-68
- The functional response to, and preference for, the host density in a parasite were examined experimentally using an icheumon wasp, Exidechthis canescens, and its host Cadra cautella under controlled conditions.
- Wasps were more active in host-searching at higher than lower host densities. Percent parasitism increased rapidly with initial increments in host density and then tended to increase more slowly at higher host densities. A sigmoid functional response curve is indicated, which implies that the parasite is able to control its host even at low densities.
- Wasps actively selected areas of high host density in which to concentrate host-searching behavior.
- Host-searching by E. canescens is stimulated by the odor of the host when present, and by food in which hosts have developed but have been removed.
- Both the functional response and the host-density preference of the parasite are mediated by its host-searching behavior. This relationship is discussed in the context of population regulation.