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31.
Previous studies with rainbow trout (Oncorhynchus mykiss) have shown that allozymic heterozygotes have increased developmental stability, as measured by reduced fluctuating bilateral
asymmetry. In this paper, we examine the phenotypic effects of null alleles at two lactate dehydrogenase (LDH) loci. If the
association between allozymic heterozygosity and developmental stability is due largely to linked chromosomal segments, then
we would expect null allele heterozygotes to have increased developmental stability. In contrast, heterozygotes for LDH null
alleles in three populations have reduced developmental stability. This suggests that the reduction in enzyme activity at
these loci is having a deleterious effect on development that is strong enough to mask any beneficial effects that may be
associated with heterozygosity for these chromosomal segments. The LDH loci examined in this study are members of two different
paralogous pairs of duplicate genes produced by the polyploidization of the ancestral salmonid genome. The apparent deleterious
effects of these null alleles in heterozygotes could retard the possible loss of duplicate gene expression. 相似文献
32.
David W. Kikuchi William L. Allen Kevin Arbuckle Thomas G. Aubier Emmanuelle S. Briolat Emily R. Burdfield-Steel Karen L. Cheney Klára Daňková Marianne Elias Liisa Hämäläinen Marie E. Herberstein Thomas J. Hossie Mathieu Joron Krushnamegh Kunte Brian C. Leavell Carita Lindstedt Ugo Lorioux-Chevalier Melanie McClure Callum F. McLellan Iliana Medina Viraj Nawge Erika Páez Arka Pal Stano Pekár Olivier Penacchio Jan Raška Tom Reader Bibiana Rojas Katja H. Rönkä Daniela C. Rößler Candy Rowe Hannah M. Rowland Arlety Roy Kaitlin A. Schaal Thomas N. Sherratt John Skelhorn Hannah R. Smart Ted Stankowich Amanda M. Stefan Kyle Summers Christopher H. Taylor Rose Thorogood Kate Umbers Anne E. Winters Justin Yeager Alice Exnerová 《Journal of evolutionary biology》2023,36(7):975-991
Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strategies. 相似文献
33.
Jan Raška Kateřina Chalušová Jan Krajiček Radomír Čabala Zuzana Bosáková Pavel Štys Alice Exnerová 《Journal of evolutionary biology》2023,36(7):1050-1064
Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators. 相似文献
34.
Julia L. Riley Tonya M. Haff Julia Ryeland Eleanor Drinkwater Kate D. L. Umbers 《Journal of evolutionary biology》2023,36(7):992-1002
Deimatic behaviour is performed by prey when attacked by predators as part of an antipredator strategy. The behaviour is part of a sequence that consists of several defences, for example they can be preceded by camouflage and followed by a hidden putatively aposematic signal that is only revealed when the deimatic behaviour is performed. When displaying their hidden signal, mountain katydids (Acripeza reticulata) hold their wings vertically, exposing striking red and black stripes with blue spots and oozing an alkaloid-rich chemical defence derived from its Senecio diet. Understanding differences and interactions between deimatism and aposematism has proven problematic, so in this study we isolated the putative aposematic signal of the mountain katydid's antipredator strategy to measure its survival value in the absence of their deimatic behaviour. We manipulated two aspects of the mountain katydid's signal, colour pattern and whole body shape during display. We deployed five kinds of clay models, one negative control and four katydid-like treatments, in 15 grids across part of the mountain katydid's distribution to test the hypothesis that their hidden signal is aposematic. If this hypothesis holds true, we expected that the models, which most closely resembled real katydids would be attacked the least. Instead, we found that models that most closely resembled real katydids were the most likely to be attacked. We suggest several ideas to explain these results, including that the deimatic phase of the katydid's display, the change from a camouflaged state to exposing its hidden signal, may have important protective value. 相似文献
35.
Octopamine receptor subclasses were first proposed to explain differences in the pharmacological profiles of a range of physiological responses to octopamine obtained in the extensor-tibiae neuromuscular preparation of the locust. Thus, OCTOPAMINE1 receptors which inhibit an endogenous myogenic rhythm, increase intracellular calcium levels. Also OCTOPAMINE2 receptors which modulate neuromuscular transmission in this preparation, increase the level of adenylate cyclase activity. The current status of this classification is reviewed by examining the pharmacology of responses to octopamine in a range of preparations. It is concluded that the distinction between OCTOPAMINE1 and OCTOPAMINE2 receptor types is still valid, but that OCTOPAMINE2 receptors exhibit some tissue specific variations. Studies on a clonedDrosophila octopamine/tyramine (phenolamine) receptor are discussed and illustrate many of the difficulties presently encountered in making a definitive classification of octopamine receptors. These include the possibilities that single receptors may activate multiple second messenger systems and that different agonists may differentially couple the same receptor to different second messenger systems. 相似文献
36.
Jonathan D. G. Jones David A. Jones Gerard J. Bishop Kate Harrison Bernard J. Carroll Steven R. Scofield 《Transgenic research》1993,2(2):63-78
Cell-autonomous genes have been used to monitor the excision of both endogenous transposons in maize andAntirrhinum, and transposons introduced into transgenic plants. In tobacco andArabidopsis, the streptomycin phosphotransferase (SPT) gene reveals somatic excision of the maize transposonActivator (Ac) as green sectors on a white background in cotyledons of seedlings germinated in the presence of streptomycin. Cotyledons of tomato seedlings germinated on streptomycin-containing medium do not bleach, suggesting that a different assay for transposon excision in tomato is desirable. We have tested the use of the spectinomycin resistance (SPEC) gene (aadA) and a Basta resistance (BAR) gene (phosphinothricin acetyltransferase, or PAT) for monitoring somatic excision ofAc in tobacco and tomato. Both genetic and molecular studies demonstrate that genotypically variegated individuals that carry clones of cells from whichAc orDs have excised from either SPEC or BAR genes, can be phenotypically completely resistant to the corresponding antibiotic. This demonstrates that these genes act non-cell-autonomously, in contrast to the SPT gene in tobacco. Possible reasons for this difference are discussed. 相似文献
37.
Anthony G. Lee Kate A. Dalton Richard C. Duggleby J. Malcolm East Anthony P. Starling 《Bioscience reports》1995,15(5):289-298
Effects of lipid structure on the function of the Ca2+-ATPase of skeletal muscle of sarcoplasmic reticulum are reviewed. Binding of phospholipids to the ATPase shows little specificity. Phosphatidylcholines with short (C14) or long (C24) fatty acyl chains have marked effects on the activity of the ATPase, including a change in the stoichiometry of Ca binding. Low ATPase activity in gel phase lipid follows from low rate of phosphorylation. Phosphatidylinositol 4-phosphate increases ATPase activity by increasing the rate of dephosphorylation of the phosphorylated ATPase. Stimulation is not seen with other anionic phospholipids; phosphatidic acid decreases ATPase activity in a Mg2+-dependent manner.Abbreviations di(C141)PC
dimyristoleoylphosphatidycholine
- di(C160)PC
dipalmitoylphosphatidylcholine
- di(C181)PC
dioleoylphosphatidylcholine
- di(Br2C180)PC
dibromostearoylphosphatidylcholine
- di(C241)PC
dinervonylphosphatidylcholine
- di(C181)PA
dioleoylphosphatidic acid
- di(C181)PE
dioleoylphosphatidylethanolamine
- Ptdlns
phosphatidylinositol
- PtdIns-4P
phos-phatidylinositol 4-phosphate 相似文献
38.
Human medulloblastoma gangliosides 总被引:2,自引:0,他引:2
To establish a model system for the study of ganglioside metabolismof the human brain tumor, medulloblastoma, we have chemicallycharacterized the gangliosides of the Daoy cell line. Thesecells contain a high concentration of gangliosides (143 ±13 nmol LBSA/108 cells). The major species have been structurallyconfirmed to be GM2 (65.9%), GM3 (13.0%), and GDla (10.3%).Isolation of individual gangliosides homogeneous in both carbohydrateand ceramide moieties by reversed-phase HPLC and analysis bynegative-ion fast atom bombardment collisionally activated dissociationtandem mass spectrometry have allowed us to unequivocally characterizeceramide structures. In the case of GM2, 10 major ceramide subspecieswere identified: d18:1-hC16:0, d18:1-C16:0, d18:0-C16:0, d18:1-C18:0,d18:1-C20:0, d18:1-C22:0, d18:2-C24:1, d18: 1-C23:1, d18:1-C24:1,and d18:1-C24:0. Taken together with previous studies, thesefindings in human medullo-blastoma cells support the view thathigh expression and marked heterogeneity of ceramide structureare general characteristics of tumor gangliosides, moleculeswhich are shed by the tumor cells and which are biologicallyactive in vivo. medulloblastoma gangliosides ceramide structure HPLC mass spectrometry 相似文献
39.
40.
Anesthetists are at special risk for becoming addicted to some of the drugs they work with. The problem was highlighted by the recent death of a physician in Comox, BC, and a doctor''s brush with death at a hospital near Ottawa. The University of Ottawa has responded with a program, the professional Assistance Program for the Impaired or Disabled Physician, that is in the final stages of approval. Although it will be aimed initially at anesthetists and anesthesia residents in the university''s teaching hospitals, there are hopes the program will spread eventually to other medical departments. 相似文献