نتایج جستجو برای: gyrodactylus sp
تعداد نتایج: 120406 فیلتر نتایج به سال:
Question: How does sexual ornamentation relate to parasite infection, host immune response and somatic condition status in male fish? Hypotheses: Zahavi’s (1975) handicap hypothesis proposes that producing secondary sexual traits represents a considerable handicap for males. Additionally, Hamilton and Zuk (1982) proposed that the expression of secondary sexual traits reveals a genetic resistanc...
In order to disentangle the contribution of host and parasite biology to host specificity, we compared the structure and population dynamics of the Gyrodactylus (von Nordmann, 1832) flatworm community living on sympatric three-spined Gasterosteus aculeatus L. and nine-spined Pungitius pungitius (L.) stickleback. Between April 2002 and March 2003, a small lowland creek was sampled monthly. Speci...
Parasitic diseases are harmful and limiting factors in breeding and rearing ornamental fish industry. In this study, 400 apparently healthy ornamental fishes from five species (each species 80 specimens) including: Goldfish (Carassius auratus), guppy (Poecilia reticulate), angelfish (Pterophyllum scalare), discus (Symphsodon discus) and sailfin molli...
Theory predicts that sexual reproduction promotes disease invasion by increasing the evolutionary potential of the parasite, whereas asexual reproduction tends to enhance establishment success and population growth rate. Gyrodactylid monogeneans are ubiquitous ectoparasites of teleost fish, and the evolutionary success of the specious Gyrodactylus genus is thought to be partly due to their use ...
رودخانه‌ی دائمی و پر آب گاماسیاب مهم‌ترین رودخانه‌ی دشت نهاوند در استان همدان و یکی از طویل‌ترین رودخانه‌های ایران به شمار می‌رود. به منظور بررسی پتانسیل آبزی‌پروری در این منطقه، طی دو فصل تابستان و پائیز سال 87 در مجموع 169 قطعه از 7 گونه ماهی که همگی متعلق به خانواده‌ی کپورماهیان (Cyprinidae) بودند، صید و مورد بررسی انگل‌شناسی قرار گرفتند. از آبشش و پوست این ماهیان پنج گونه مونوژن جدا...
Assessment of contaminant impacts to federally identified endangered, threatened and candidate, and state-identified endangered species (collectively referred to as "listed" species) requires understanding of a species' sensitivities to particular chemicals. The most direct approach would be to determine the sensitivity of a listed species to a particular contaminant or perturbation. An indirec...
Vitellogenin (VTG) is a precursor of egg-yolk protein and is therefore present at high concentrations in the plasma of female fish. In male fish, VTG concentrations are usually undetectable or low, but can be induced upon exposure to oestrogenic substances either via the water or the diet. This work was carried out to determine the reason for apparently elevated VTG concentrations in unexposed ...
Most quantitative structure-activity relationship (QSAR) models are linear relationships and significant for only a limited domain of compounds. Here we propose a data-driven approach with a flexible combination of unsupervised and supervised neural networks able to predict the toxicity of a large set of different chemicals while still respecting the QSAR postulates. Since QSAR is applicable on...
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