Search results for "HOST-PARASITE"
showing 10 items of 355 documents
Spatiotemporal and gender-specific parasitism in two species of gobiid fish
2018
Parasitism is considered a major selective force in natural host populations. Infections can decrease host condition and vigour, and potentially influence, for example, host population dynamics and behavior such as mate choice. We studied parasite infections of two common marine fish species, the sand goby (Pomatoschistus minutus) and the common goby (Pomatoschistus microps), in the brackish water Northern Baltic Sea. We were particularly interested in the occurrence of parasite taxa located in central sensory organs, such as eyes, potentially affecting fish behavior and mate choice. We found that both fish species harbored parasite communities dominated by taxa transmitted to fish through …
Infection dynamics of two renal myxozoans in hatchery reared fry and juvenile Atlantic cod Gadus morhua L.
2010
SUMMARYIn order to study the infection dynamics of 2 renal myxozoans, Zschokkella hildae Auerbach, 1910 and Gadimyxa atlanticaKøie, Karlsbakk and Nylund, 2007 in cultured Atlantic cod, Gadus morhua L. aged 3–19 months, a specific single-round PCR assay and a double-label in situ hybridization protocol were developed. The results demonstrated that the 2 myxozoans show spatial separation of their development with regard to spore formation inside the renal tubules versus the collecting ducts and ureters, as well as temporal separation with Z. hildae proliferating and developing spores only once the G. atlantica infection decreases, despite the presence of both myxozoans in the smallest fry stu…
Phage-borne factors and host LexA regulate the lytic switch in phage GIL01.
2011
ABSTRACT The Bacillus thuringiensis temperate phage GIL01 does not integrate into the host chromosome but exists stably as an independent linear replicon within the cell. Similar to that of the lambdoid prophages, the lytic cycle of GIL01 is induced as part of the cellular SOS response to DNA damage. However, no CI-like maintenance repressor has been detected in the phage genome, suggesting that GIL01 uses a novel mechanism to maintain lysogeny. To gain insights into the GIL01 regulatory circuit, we isolated and characterized a set of 17 clear plaque ( cp ) mutants that are unable to lysogenize. Two phage-encoded proteins, gp1 and gp7, are required for stable lysogen formation. Analysis of …
Is the population genetic structure of complex life cycle parasites determined by the geographic range of the most motile host?
2010
Due to their particular way of life, dispersal of parasites is often mediated by their host's biology. Dispersal distance is relevant for parasites because high degree of dispersal leads to high gene flow, which counters the rate of parasite local adaptation in the host populations. Parasites with complex life cycles need to exploit sequentially more than one host species to complete their life cycle. Most trematode parasites have such complex life cycles involving invertebrate and vertebrate hosts. The spatial scales of invertebrate and vertebrate host populations are often different, which may decrease the probability that the parasite cycles locally in the intermediate host population. W…
Divergent Macroparasite Infections in Parapatric Swiss Lake-Stream Pairs of Threespine Stickleback (Gasterosteus aculeatus)
2015
Spatial heterogeneity in diversity and intensity of parasitism is a typical feature of most hostparasite interactions, but understanding of the evolutionary implications of such variation is limited. One possible outcome of infection heterogeneities is parasite-mediated divergent selection between host populations, ecotypes or species which may facilitate the process of ecological speciation. However, very few studies have described infections in populationpairs along the speciation continuum from low to moderate or high degree of genetic differentiation that would address the possibility of parasite-mediated divergent selection in the early stages of the speciation process. Here we provide…
Horizontally transmitted parasitoid killing factor shapes insect defense to parasitoids
2021
Protection from parasitism by a virus Parasitoid wasps have developed myriad systems to overcome the defense mechanisms of their hosts as they lay their eggs in the bodies and eggs of targeted species. Gasmi et al . report how the host can fight back when infected by a virus that expresses a protein conferring resistance to the parasitoid. When members of the butterfly and moth family are targeted by wasps, a protein family has evolved that is horizontally carried by viruses—and sometimes is incorporated into the host genome—and impairs the ability of parasitoid offspring to fully develop and emerge. Characterizing the ability of this protein to protect hosts against specific parasites, the…
Larval morphology, genetic divergence, and contrasting levels of host manipulation between forms of Pomphorhynchus laevis (Acanthocephala)
2004
Studies on parasite species with a wide geographic and ecological range may be confounded by still equivocal taxonomic identification. Here, we investigated genetic polymorphism and behavioural changes induced in a common intermediate host, in two different forms of Pomphorhynchus laevis based on the morphology of the larval infective stage (cystacanth). A 'smooth type' (S) and a 'wrinkled type' (W) of cystacanth were distinguished based on their surface and shape. We analysed sequence divergence at both nuclear (ribosomal gene 18S rDNA, and ribosomal internal transcribed spacers, ITS1/ITS2) and mitochondrial (cytochrome c oxidase subunit 1) genes of P. laevis cystacanths and adults at vari…
Endoparasites of the blue whiting, Micromesistius poutassou from north-west Spain.
2005
AbstractThe communities of metazoan endoparasites of blue whiting, Micromesistius poutassou, in waters of north-west Spain were analysed and a geographical comparison made with other localities. Four hundred blue whiting collected in July 1999 and September 2000 were examined for parasites, excluding the head and gills. Six species were found: Anisakis simplex s.l. (L3), A. physeteris (L3), Hysterothylacium aduncum (L2 and L3), Stephanostomum lophii (metacercaria), S. pristis (adult), and Prosorhynchus crucibulum (metacercaria). The latter is a new host record, and A. physeteris is reported for the first time in blue whiting from the north-east Atlantic. Host gender was not a significant pr…
Diclidophora merlangi (Monogenea: Diclidophoridae) on Atlantic cod, Gadus morhua.
2006
Diclidophora merlangi (Kuhn, in Nordmann, 1832), as species specific to whiting, Merlangius merlangus (Linnaeus, 1758), is reported and described for the first time on the gills of Atlantic cod Gadus morhua (Linnaeus, 1758). Of the about 1,200 cod examined in this article, only 2 specimens of D. merlangi occurred on 2 fish, suggesting that they represented accidental infections. The 2 specimens showed specific traits of D. merlangi, but their size was considerably smaller than that of D. merlangi on whiting. Principal-component analyses showed that the morphology of the specimens on cod was more similar to that of D. merlangi than those of other congeneric species from the North Atlantic, a…
Skoulekia meningialis n. gen., n. sp. (Digenea: Aporocotylidae Odhner, 1912) a parasite surrounding the brain of the Mediterranean common two-banded …
2010
This study describes a new aporocotylid genus and species, Skoulekia meningialis n. gen., n. sp. which was detected in the ectomeningeal veins surrounding the optic lobes of the brain of the common two-banded seabream Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817) from the Gulf of Valencia (Mediterranean Sea). A detailed morphological description of S. meningialis is provided, including drawings, measurements and scanning electron microscopy images as well as a phylogenetic study of S. meningialis and closely related taxa using DNA sequence data obtained from whole ITS2 and partial 18S and 28S rDNA regions. Morphology as well as molecular phylogeny strongly support the erection of a new g…