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41.
C. Gutierrez G. Garcia-Casado R. Snchez-Monge L. Gomez P. Castaera G. Salcedo 《Entomologia Experimentalis et Applicata》1993,66(1):47-52
Crude α-amylase preparations from seven Lepidoptera pests were susceptible to inhibition by salt-soluble proteins of bread
wheat (Triticum aestivum L.) endosperm. Protein fractions that corresponded to tetrameric, dimeric, and monomeric wheat α-amylase inhibitors, were
decreasingly effective against the insect α-amylase activity. To further confirm these results, purified inhibitors were tested
against an α-amylase preparation fromEphestia kuehniella (Zeller). This preparation showed decreased activity when increasing amounts of an heterotetrameric inhibitor (reconstituted
from its isolated subunits WTAI-CM2, -CM3 and -CM16) were assayed. Activity was only partially inhibited by homodimeric (WDAI-1,
synonym 0.53; WDAI-2, synonym 0.19) and monomeric (WMAI-1, synonym 0.28) inhibitors. 相似文献
42.
43.
Gustavo A. Londoño Juan Pablo Gomez Manuel A. Sánchez-Martínez Douglas J. Levey Scott K. Robinson 《Ecology letters》2023,26(4):609-620
Tropical montane communities host the world's highest beta diversity of birds, a phenomenon usually attributed to community turnover caused by changes in biotic and abiotic factors along elevation gradients. Yet, empirical data on most biotic factors are lacking. Nest predation is thought to be especially important because it appears to be common and can change selective pressures underlying life history traits, which can alter competitive interactions. We monitored 2538 nests, 338 of which had known nest predators, to evaluate if nest predation changes along a tropical elevational gradient. We found that nest predation decreased with elevation, reflecting the loss of lowland predators that do not tolerate colder climates. We found different “super” nest predators at each elevation that accounted for a high percentage of events, suggesting that selection pressures exerted by nest predator communities may be less diffuse than has been hypothesized, at least for birds nesting in the understory. 相似文献
44.
Daniel E. Gomez Jacqueline L. Hartzler Robert H. Corbitt Alexander M. Nason Unnur P. Thorgeirsson 《In vitro cellular & developmental biology. Animal》1993,29(6):451-455
Summary We describe a fast and reproducible method that can be used as a final step in obtaining pure populations of liver endothelial
cells. This method employs endothelial cell specific lectin covalently bound to magnetic polystyrene beads (Dynabeads). Evonymus
europaeus agglutinin (EEA)-coated Dynabeads were used to purify monkey liver endothelium from Percoll gradient separated nonparenchymal
cells. EEA-coated beads were also successfully used to purify monkey aortic endothelial cells. The endothelial cells grew
to confluence as a cobblestonelike monolayer, expressed Factor VIII related antigen, and incorporated acetylated-low density
lipoprotein. The magnetic beads seemed not to modify the normal properties of the isolated endothelium, thus facilitating
their use in experimental studies. This immunomagnetic separation technique may be applicable for purification of endothelial
cells from a wide variety of tissue sources. 相似文献
45.
46.
Small individuals (<15 cm long) of the clingfish Sicyases sanguineus consume as many as 18 seaweed species in Central Chile. Enteromorpha sp. was the only species able to survive digestion by fish recently collected from the field. Enteromorpha compressa and Gelidium chilense also survived by tissue regeneration when offered as food in the laboratory, but only E. compressa showed stimulation of swarmer production. In general, our results on a vertebrate species reproduce previous findings on diverse invertebrate species. Since fish are highly motile, their capacity to disperse algal species by defecation might be of great ecological importance. 相似文献
47.
Benthic algae survive passage through the digestive tract of different types of grazers, either regenerating new tissues or releasing protoplasts and swarmers which act as accessory means of reproduction to generate new individuals. The ecological importance of this phenomenon is evaluated here by studying spores and fecal pellets. Alga fragments egested alive inside fecal pellets have some ecological advantages over free propagules. In intertidal habitats, the sticky nature of the pellets permits attachment to the substratum while protecting the contained algae from desiccation. In subtidal habitats, the pellets sink 8–22 times faster than the fastest sinking algal propagule. Quantification of swarmers and protoplasts released from algal fragments in the fecal pellets indicates densities of about 217 germlings·cm?2 and values of 300–700 propagules per pellet. Extrapolation of these results to field conditions based on number of grazers and pellets suggest production figures varying from 0.5–3.5 × 105to 1.3–1.5 × 106 propagules·m?2·12 h?1. These values are within known density ranges of settling spores in the field. The ecological significance of the phenomenon may be especially important at seasons when the density of grazers increases and the normal reproductive activity of the algae being consumed decreases. 相似文献
48.
49.
Antonio del Castillo-Olivares Alicia Esteban del Valle Javier Márquez Ignacio NÚñez de Castro Miguel ángel Medina 《Journal of bioenergetics and biomembranes》1995,27(6):605-611
Ehrlich cell plasma membrane ferricyanide reductase activity increased in the presence of mastoparan, a generic activator of G proteins, using either whole cells or isolated plasma membrane fractions. Agents that increase intracellularcAMP also increased the rate of ferricyanide reduction by Ehrlich cells. For the first time, evidence is shown on a modulation of plasma membrane redox system bycGMP. In fact, permeant analogs ofcGMP, dibutyrylcGMP, and 8-bromo-cGMP increased the rate of ferricyanide reduction by the Ehrlich cell plasma membrane redox system. Furthermore, specific inhibition ofcGMP-phosphodiesterases by dipyridamole was also accompanied by an enhancement in the rate of ferricyanide reduction. On the other hand, treatments expected to increase cytoplasmic Ca2+ concentrations were accompanied by a remarkable stimulation of the reductase activity. Taking all these data together, it seems that the Ehrlich cell plasma membrane redox system is under a multiple and complex regulation by different signal transduction pathways involving G proteins, cyclic nucleotides, and Ca2+ ions. 相似文献
50.
Ignacio E. Maldonado-Mendoza Victor M. Loyola-Vargas 《Plant Cell, Tissue and Organ Culture》1995,40(3):197-208
Twelve different lines of Datura stramonium (normal and hairy) root cultures were subjected to conditions which induce photoautotrophy. Two of the hairy root lines responded to induction, showing clearly a diminished growth rate when compared to heterotrophic cultures, an increase in chlorophyll, a net O2 evolution, CO2 fixation, and de novo synthesis of the ribulose 1,5 biphosphate carboxylase enzyme. A time course of growth and tropane alkaloid levels in the tissue and medium, revealed a correlation between the development of the photosynthetic apparatus and the increase in scopolamine. Although normal cultures did not grow photosynthetically, they showed some greening response under the first step of the induction. The correlation between development of photosynthesis and increase in scopolamine synthesis were corroborated with normal root cultures. This experimental model is used for the basic study of the regulatory enzymes involved in the biosynthesis of tropane alkaloids, as well as for the study of their mechanisms of transport. 相似文献