Search results for "Gill"
showing 10 items of 496 documents
Rich resource environment of fish farms facilitates phenotypic variation and virulence in an opportunistic fish pathogen
2020
Phenotypic variation is suggested to facilitate the persistence of environmentally growing pathogens under environmental change. Here, we hypothesized that the intensive farming environment induces higher phenotypic variation in microbial pathogens than natural environment, because of high stochasticity for growth and stronger survival selection compared to the natural environment. We tested the hypothesis with an opportunistic fish pathogen Flavobacterium columnare isolated either from fish farms or from natural waters. We measured growth parameters of two morphotypes from all isolates in different resource concentrations and two temperatures relevant for the occurrence of disease epidemic…
Morphological and attachment changes of Lamellodiscus theroni (Monogenea: Diplectanidae) during its post-larval development on fish.
2014
Species of the genus Lamellodiscus Johnston et Tiegs, 1922 (Monogenea: Diplectanidae) are characterised by a complex haptor bearing many different attachment elements: two pairs of main hooks joined by medial bars, 14 peripheral marginal hooks and one or two lamellodiscs, formed by several overlapping sclerotised plates (lamellae). These haptoral structures appear gradually during parasite development and, therefore, attachment strategies vary with developmental stage. The main aim of this work was to study the developmental changes of Lamellodiscus theroni Amine, Euzet et Kechemir-Issad, 2007 under experimental conditions, with special attention to the gradual variations in attachment stra…
Accacoelium contortum (Trematoda: Accacoeliidae) a trematode living as a monogenean: morphological and pathological implications
2015
Background Accacoelium contortum (Rudolphi, 1819) Monticelli, 1893 is a frequent but poorly known trematode found on gills, pharynx and digestive tract of the ocean sunfish Mola mola (L.). Although the morphology of A. contortum agrees with that of a typical endoparasitic trematode, with two relatively small suckers and no large holdfasts, this parasite is normally ectoparasitic. The main objective of this paper is to explore this peculiar host-parasite relationship. Methods A total of 106 ocean sunfish were examined for the presence of A. contortum. The oropharyngeal chamber (gills and pharynx) and the digestive tract were analysed. As the previous descriptions of this species seem to be b…
Fenitrothion uptake and bioconcentration in the European eel(Anguilla anguilla)
1994
Eels (Anguilla anguilla) were exposed to 0.02 mg/L of the organophosphorus pesticide fenitrothion during 144 hours in semi‐static conditions. BCF, intBCF, uptake rate constants (Ku) and elimination rate constants (Kd) of fenitrothion were determined in brain, gills, blood and muscle tissues of the eel. A simple one‐compartment model fitted the uptake and elimination characteristics. Plateau were reached at different times in the different tissues: at 24 hr in gills, 72 hr in brain and blood and 120 hr in muscle tissue. BCF were ranged from 117 for blood to 658 for muscle. Muscle tissue showed the highest BCF, intBCF, Ku and the lowest Kd .
Thiobencarb-Induced Changes in Acetylcholinesterase Activity of the Fish Anguilla anguilla
2002
Abstract European eels (Anguilla anguilla) were exposed to sublethal thiobencarb concentrations in a continuous flow-through system for 4 days. Brain, muscle, and gill acetylcholinesterase (AChE) activities were evaluated after 2, 12, 24, 48, 72, and 96 h herbicide exposure. Thiobencarb induced significant inhibitory effects on the total and specific AChE activity of A. anguilla, ranging from >30–40% inhibition in eel brain and gills to >50% inhibition in muscle tissue 2 h after the initial exposure. In a second experiment, eels were exposed to thiobencarb for 96 h and then allowed a period of recovery in pesticide-free water. Following 1 week of recovery, the AChE activity of affected eels…
Gill anomalies of perch and roach from four lakes differing in water quality
1997
This study examined gill anomalies of two common freshwater fish species, roach Rutilus rutilus and perch Perca fluviatilis, collected over five seasons in 1989–1990 from four lakes in central Finland. The lakes differed both in water quality and in fish parasite species composition. Particular attention was paid to the differences in chloride cell proliferation. Gill anomalies were generally more common and abundant in roach than in perch. Chloride cell proliferation was the most frequent histological change in roach but was that least often found in perch. Most of the changes were systemic and light in severity. In perch an unidentified lesion of noncellular eosinophilic inclusions in an …
Seasonal studies of the biology ofAchtheres percarumin perch,Perca fluviatilis, from four Finnish lakes over a 3-year period
1993
Achtheres percarum infection on the gills of perch Perca fluviatilis was studied from four lakes in central Finland in monthly or bimonthly samples of fish during a 3-year period. The highest prevalence and intensity of infection (30%, 0.7 copepods/fish) were found in the oligotrophic, unpolluted Lake Peurunka and the lowest (6%, 0.1 copepods/fish) in the eutrophic and polluted Lake Vatia. According to hierarchical loglinear models the prevalence of A. percarum infection was related to the lake, but not to the year. However, when logit models were constructed such that two ‘seasons’ (‘cold’ and ‘warm’ periods) were included, it was apparent that the year also influenced the prevalence of A.…
Histological and electron microscopical observations on the effects of lead on gills and midgut gland ofProcambarus clarkii
1991
Adult intermolt specimen of Procambarus clarkii (Crustacea, Decapoda) have been treated for 96 hours in aquaria with 100mg/l of lead. The gills and midgut gland were processed and studied in the electron microscope. The gill filament shows important changes in the ultrastructure of the epithelial cells and the cuticle. The hepatopancreatic cells studied (i.e. the vacuolated and dark cells) do not show noticeable structural changes but accumulate lead (electrondense precipitates) mainly in lysosomes.
Determination of lead in treated crayfish Procambarus clarkii: accumulation in different tissues.
1988
The continual loading of trace metals into our environment represents a water pollution problem due to their toxic effects on aquatic biota. In addition, metal ions can be incorporated into food chains and concentrated by aquatic organisms to a level that affects their physiological state. There are several investigations on the toxic effects and bioaccumulation of lead in fishes, molluscs, and crustaceans. Lake Albufera (Valencia, Spain) and the surrounding rice-field waters are subjected to large loads of sewage and toxic industrial residues (including heavy metals) from many urban wastewaters in the area. In 1978, the American red crayfish Procambarus clarkii (Girard) appeared in Lake Al…
A comparative epizootiologic study of the two fish-pathogenic serovars ofVibrio vulnificusbiotype 2
2010
Vibrio vulnificus biotype 2 is subdivided into two main serovars, serovar E, able to infect fish and humans, and serovar A, only virulent for fish. Serovar E emerged in 1976 as the causative agent of a haemorrhagic septicaemia (warm-water vibriosis) affecting eels cultured in brackish water. Serovar A emerged in 2000 in freshwater-cultured eels vaccinated against serovar E, causing warm-water vibriosis with fish showing a haemorrhagic intestine as the main differential sign. The aim of the present work was to compare the disease caused by both serovars in terms of transmission routes, portals of entry and host range. Results of bath, patch-contact and oral-anal challenges demonstrated that …