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991.
Myrmecophilous butterflies utilise ant–treehopper associations as visual cues for oviposition 下载免费PDF全文
1. Selection of a safe oviposition site is important for herbivorous insects whose immature stages have limited mobility. Female herbivores rely on environmental cues for this choice, and presence of natural enemies or mutualistic partners may be important in this process. 2. Some butterflies have mutualistic interactions with ants (myrmecophily), in which caterpillars offer a nutritional liquid and gain protection against natural enemies. Participants in butterfly–ant mutualisms may utilise signals to initiate interactions, but the use of visual cues by ovipositing myrmecophilous butterflies remains uncertain. 3. Larvae of facultatively myrmecophilous Parrhasius polibetes (Lycaenidae) feed on Schefflera vinosa, and females prefer to oviposit near aggregations of the ant‐tended treehopper Guayaquila xiphias, where caterpillars survive better due to increased ant attendance. Given the conspicuousness of ant–treehopper associations, it was investigated whether butterflies use them as visual cues for oviposition and, if so, which participants of the association are used as cues: ants, treehoppers, or both. 4. Experiments using dried insects on paired branches revealed that females visually recognise ants and ant–treehopper associations, using them for egg‐laying decisions. However, presence of a treehopper aggregation alone had no effect on oviposition choices. 5. This is a first insight into the importance of visual discrimination for ovipositing myrmecophilous butterflies. The results show that facultative mutualisms can be important enough to promote a behavioural adaptation (visual detection of ants) reinforcing the interaction. Our research highlights the importance of the behavioural interface within complex multispecies systems. 相似文献
992.
海洋浮游藻类除通过吸收和释放分子与离子来改变其环境的化学成分外,还可通过细胞外表面一些酶的作用引起质膜外化学物质变化。在这方面,海洋浮游藻类一个主要的细胞外表面酶-碳酸酐酶(CA),在经胰蛋白酶处理从细胞质膜上释放出来后,仍保留其催化活性。当细胞外表面CA(简称细胞外CA)具活性时,可催化质膜外HCO_3~-与CO_2的相互转化,为Rubisco(磷酸核酮糖羧化酶)提供一稳定的CO_2流量环境,以维持正常的光合作用。 相似文献
993.
Lahjouji K Storms R Xiao Z Joung KB Zheng Y Powlowski J Tsang A Varin L 《Applied microbiology and biotechnology》2007,75(2):337-346
A cellobiohydrolase-encoding cDNA, Tvcel7a, from Trametes versicolor has been cloned and expressed in Aspergillus niger. The deduced amino acid sequence shows that Tvcel7a encodes a 456-amino acid polypeptide belonging to glycosyl hydrolase family 7. TvCel7a possesses a 19-amino acid secretion
signal but does not possess a linker region nor a carbohydrate-binding domain. Two peaks of activity were obtained after TvCel7a
was purified to apparent homogeneity by gel-filtration followed by anion-exchange chromatography. Mass spectrometry performed
on the purified proteins confirmed that both peaks corresponded to the predicted sequence of the T. versicolor cellulase. The biochemical properties of the purified TvCel7a obtained from both peaks were studied in detail. The pH and
temperature optima were 5.0 and 40°C, respectively. The enzyme was stable over a pH range extending from pH 3.0 to 9.0 and
at temperatures lower than 50°C. The kinetic parameters with the substrate p-nitrophenyl β-d-cellobioside (pNPC) were 0.58 mM and 1.0 μmol/min/mg protein for the purified TvCel7a found in both peaks 1 and 2. TvCel7a
catalyzes the hydrolysis of pNPC, filter paper, β-glucan, and avicel to varying extents, but no detectable hydrolysis was
observed when using the substrates carboxymethylcellulose, laminarin and pNPG. 相似文献
994.
Chaouachi A Manzi V Chaalali A Wong DP Chamari K Castagna C 《Journal of strength and conditioning research / National Strength & Conditioning Association》2012,26(10):2667-2676
ABSTRACT: Chaouachi, A, Manzi, V, Chaalali, A, Wong, DP, Chamari, K, and Castagna, C. Determinants analysis of change-of-direction ability in elite soccer players. J Strength Cond Res 26(10): 2667-2676, 2012-In this study, we examined the components of 2 change-of-direction (COD) ability (CODA) tests in elite-level male soccer players (n = 23, age 19 ± 1 years, height 181 ± 5.7 cm, body mass 73.2 ± 4.1 kg, % body fat 11 ± 2.4). As CODA paradigms, the T-test and 5-m shuttle run-sprint (5mSS) test assumed as describing the opposing ends of the COD complexity in soccer (i.e., general and specific tests, respectively) were considered. Results showed that the anthropometric and muscular performance variables were able to account for ~45% (p < 0.04) of the common variance of CODA. The T-test performance was explained by 8 variables (adjusted R = 0.45, p = 0.026), with 5mSS, height, knee extensors isokinetic concentric strength at 60°·per second, and right-to-left knee extensors eccentric strength deficit reaching a level of significance in the provided model (p ≤ 0.02). The best-fitting equation for 5mSS performance included 10 variables (adjusted R = 0.48, p = 0.036) of which T-test performance, height, percentage of body fat, and peak power during the countermovement jump resulted significantly affecting the common shared variance (p ≤ 0.03). This study finding showed that the affecting variables of CODA differ according to the test characteristics. Furthermore, the magnitude of the reported associations suggests that currently CODA should be regarded mainly as a task-specific fitness attribute. Further studies are warranted to detect more relevant performance variables to describe CODA. Meanwhile, soccer coaches and fitness trainers are advised to improve players' CODA using training drills that mimic crucial match actions. 相似文献
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997.
Composition of Soil Microbial Communities Enriched on a Mixture of Aromatic Hydrocarbons 总被引:2,自引:1,他引:2 下载免费PDF全文
E. Anne Greene Jason G. Kay Karim Jaber Les G. Stehmeier Gerrit Voordouw 《Applied microbiology》2000,66(12):5282-5289
Soil contaminated with C5+, which contained benzene (45%, wt/wt), dicyclopentadiene (DCPD) plus cyclopentadiene (together 20%), toluene (6%), styrene (3%), xylenes (2%), naphthalene (2%), and smaller quantities of other compounds, served as the source for isolation of 55 genomically distinct bacteria (standards). Use of benzene as a substrate by these bacteria was most widespread (31 of 44 standards tested), followed by toluene (23 of 44), xylenes (14 of 44), styrene (10 of 44), and naphthalene (10 of 44). Master filters containing denatured genomic DNAs of all 55 standards were used to analyze the community compositions of C5+ enrichment cultures by reverse sample genome probing (RSGP). The communities enriched from three contaminated soils were similar to those enriched from three uncontaminated soils from the same site. The compositions of these communities were time dependent and showed a succession of Pseudomonas and Rhodococcus spp. before convergence on a composition dominated by Alcaligenes spp. The dominant community members detected by RSGP were capable of benzene degradation at all stages of succession. The enrichments effectively degraded all C5+ components except DCPD. Overall, degradation of individual C5+ hydrocarbons followed first-order kinetics, with the highest rates of removal for benzene. 相似文献
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999.
通过构建和筛选天麻(Gastrodia elata Bl.)基因组文库,克隆了一个天麻抗真菌蛋白基因组DNA.该基因组DNA含有一个516碱基组成的编码区,没有内含子结构.其启动子区含有保守的TATA盒及CAAT盒.为研究启动子活性,构建了-1 157 bp启动子区与GUS基因的融合表达载体.并将其用农杆菌(Agrobacterium tumefaciens)介导的遗传转化方法导入烟草(Nicotiana tabacum)中,获得了稳定转化的烟草.利用荧光检测及组织化学染色法对GUS表达进行了分析.结果表明,该启动子能够启动GUS基因在转基因烟草中组织特异性地表达.GUS基因在根中的表达水平最高,茎中次之,叶中只有低水平表达.而且该启动子具有诱导表达活性,可被真菌及水杨酸、茉莉酸强烈诱导表达. 相似文献
1000.