| parasite infections in danish trout farms. | samples from 5 danish freshwater trout farms rearing rainbow trout (oncorhynchus mykiss) were examined for parasite infections from october 1993 until november 1994 and recorded parasites are listed. in addition, results from an examination of a mariculture net cage system are presented as well. a total of 10 metazoan and 10 protozoan parasites were recorded. the metazoans included gyrodactylus derjavini, gyrodactylus salaris, eubothrium crassum, triaenophorus nodulosus, proteocephalus sp., dipl ... | 1995 | 7502946 |
| species variation within the internal transcribed spacer (its) region of gyrodactylus (monogenea:gyrodactylidae) ribosomal rna genes. | the ribosomal internal transcribed spacer (its) region from individual gyrodactylus specimens was amplified by polymerase chain reaction (pcr). the reaction amplified the entire its1-5.8s-its2 region of the ribosomal rna gene cluster using primers that hybridize to the 3' terminus of the small subunit and the 5' terminus of the large subunit ribosomal rna genes. the pcr products from gyrodactylus salaris and gyrodactylus thymalli were cloned and sequenced. the gyrodactylus 5.8s gene was identifi ... | 1997 | 9105299 |
| seasonal occurrence of gyrodactylus derjavini (monogenea) on brown trout, salmo trutta, and atlantic salmon, s. salar, in the sandvikselva river, norway. | seasonal variation in prevalence and intensity of the ectoparasite gyrodactylus derjavini on brown trout parr, salmo trutta, and atlantic salmon parr, s. salar, and occurrence of g. derjavini on ascending sea trout, s. trutta m. trutta, in the sandvikselva river, southeastern norway, was recorded. in general, both prevalence and intensity increased and decreased correspondingly with the rise and fall in water temperature. however, both prevalence and intensity decreased in warm periods when repr ... | 1997 | 9406773 |
| microenvironment of gyrodactylus derjavini on rainbow trout oncorhynchus mykiss: association between mucous cell density in skin and site selection. | microhabitat selection of gyrodactylus derjavini on the body surface of rainbow trout changed markedly during a 6-week experimental infection period. pectoral fins, pelvic fins and anal fins were the most important sites (expressed in terms of parasite density) during the initial part of the infection. in the later stages of infection, the corneal surface and tail fin became increasingly more heavily infested. factors responsible for this dynamic site selection were investigated. the density of ... | 1998 | 9491421 |
| temperature dependent population growth of gyrodactylus derjavini on rainbow trout, oncorhynchus mykiss. | rainbow trout were experimentally infected with the ectoparasitic monogenean gyrodactylus derjavini at three temperatures, 5.5 degrees c, 11.6 degrees c and 18.7 degrees c. subsequently, the infection level was monitored during the following 6 weeks. the population growth was positively correlated with temperature in the initial part of the investigation. at 18.7 degrees c growth of the parasite population was fast reaching a peak abundance within 3 weeks, whereafter the infection level decrease ... | 1998 | 9639894 |
| the application of chaetotaxy in the discrimination of gyrodactylus salaris malmberg, 1957 (gyrodactylidae: monogenea) from species of the genus parasitising british salmonids. | the chaetotaxy of argentophilic structures on three species of the monogenean genus gyrodactylus was investigated in an attempt to distinguish species of this genus. maps were prepared for gyrodactylus salaris from scandinavia and compared with two native species of gyrodactylus parasitising salmonids in britain, namely gyrodactylus derjavini and gyrodactylus truttae. the maps were subsequently refined and analysed for zones of homology and differentiation. the results demonstrate that g. salari ... | 1998 | 9650061 |
| binding and lethal effect of complement from oncorhynchus mykiss on gyrodactylus derjavini (platyhelminthes: monogenea). | a lethal effect of rainbow trout oncorhynchus mykiss plasma containing intact complement factors on gyrodactylus derjavini was demonstrated. it was associated with binding of complement factor c3 to certain carbohydrate-rich parasite structures. parasites were exposed in vitro to plasma from rainbow trout. untreated plasma from infected and uninfected fish showed lethal effects on the parasites within 1 h, whereas prior heat inactivation of complement prevented any parasite killing. inhibition o ... | 1998 | 9676245 |
| histochemical characteristics of gyrodactylus derjavini parasitizing the fins of rainbow trout (oncorhynchus mykiss). | histochemical studies of enzyme activities and structural elements in gyrodactylus derjavini mikailov, 1975 parasitizing fins of oncorhynchus mykiss walbaum were conducted. marked activities of non-specific esterase, acid phosphatase, alkaline phosphatase and amino-peptidase were found in the intestinal caeca of the parasite. a strong activity of acetylcholinesterase was seen in the nervous system. extraintestinal non-specific and eserine-sulphate resistant esterase was localized in the distal p ... | 1998 | 9868792 |
| rainbow trout leucocyte activity: influence on the ectoparasitic monogenean gyrodactylus derjavini. | the ectoparasitic monogenean gyrodactylus derjavini from rainbow trout oncorhynchus mykiss was exposed in vitro to macrophages isolated as peritoneal exudate cells or as pronephros cells from the host. cells colonized the parasite especially in the mannose-rich regions in the cephalic ducts where ciliated structures were abundant. opsonization with fresh serum, in contrast to heat-inactivated serum, enhanced colonization also on other body parts. the adverse effect of the activated macrophages t ... | 1999 | 10073311 |
| partial cross protection against ichthyophthirius multifiliis in gyrodactylus derjavini immunized rainbow trout. | partial cross protection against a skin-parasitic ciliate has been recorded in rainbow trout previously immunized with an ectoparasitic platyhelminth. the susceptibility to infection by ichthyophthirius multifiliis differed significantly between naive and gyrodactylus derjavini immunized rainbow trout. fish partly immune to the ectoparasitic monogenean g. derjavini became less infected and experienced lower mortality than naive fish when exposed to i. multifiliis infections. in vitro studies on ... | 1999 | 10526411 |
| the susceptibility of atlantic salmon (salmo salar l.) x brown trout (salmo trutta l.) hybrids to gyrodactylus salaris malmberg and gyrodactylus derjavini mikailov. | salmo salar and salmo trutta co-exist in coastal river systems in europe and produce hybrids with little loss of viability or growth. this report describes the susceptibility of pure full-sibs of s. salar and s. trutta and their reciprocal half-sib hybrids to their respective gyrodactylids, gyrodactylus salaris and gyrodactylus derjavini. the pure-bred salmon and trout, and half-sib hybrids, were produced using eggs and sperm from wild anadromous s. salar (river alta stock, north norway) and wil ... | 1999 | 10599079 |
| acquired resistance in rainbow trout against gyrodactylus derjavini. | investigations were conducted on the host response in rainbow trout and the associated changes in mucous cell density during infection with the skin monogenean gyrodactylus derjavini. parasite populations increased on all naive hosts and peaked 4-5 weeks p.i. after which infection levels decreased. introduction of naive fish into responding host populations resulted in heavy infections of the naive fish, whereas parasite expulsion continued in the responding host groups showing an acquired, non- ... | 2000 | 10881287 |
| associations between epidermal thionin-positive cells and skin parasitic infections in brown trout salmo trutta. | the dynamics of the densities of epidermal thionin-positive cells (putative mast cells) in the skin of brown trout fry were investigated during experimental infections with the skin parasites ichthyophthirius multifiliis (ciliophora) and gyrodactylus derjavini (monogenea). it was shown that the metachromatic thionin-stained cells were extremely sensitive to parasite exposure, as the density of cells in the skin of trout decreased markedly after exposure to the pathogens. as early as 7 d post inf ... | 2000 | 10918981 |
| in vitro interactions between epithelial cells and gyrodactylus derjavini. | skin responses of fish to various parasites have been shown to involve various immunologically competent cells producing factors which guide the reactions of epithelial cells. however, the present study has demonstrated that a monoculture of epithelial cells has the ability to encapsulate and partially degrade ectoparasites without involvement of leukocytes. the ectoparasitic monogeneangyrodactylus derjavini was kept on a monolayer of epithelioma papulosum cyprini (epc) cells in 24-well multidis ... | 2000 | 10953219 |
| lectins in fish skin: do they play a role in host-monogenean interactions? | mucus samples from rainbow trout skin with or without infections by gyrodactylus derjavini were tested for the presence of lectins reacting with mannose, galactose and lactose. the samples inhibited the binding of biotinylated lectins (from canavalia ensiformis, artocarpus integrifolia and erythrina corallodendron, respectively) to microtitre plates with covalently bound carbohydrates (mannopyranoside, galactopyranoside and lactose, respectively). however, the inhibition of c. ensiformis and a. ... | 2001 | 11551311 |
| effect of gyrodactylus derjavini infections on cortisol production in rainbow trout fry. | cortisol production in fry of rainbow trout (367-456 mg body weight) infected with the ectoparasitic monogenean gyrodactylus derjavini (mean intensities 4.7 and 4.9 parasites per fish) was studied at two temperature levels, 4-6 degrees c and 11-12 degrees c, respectively. due to difficulties in obtaining an adequate amount of plasma from the small sized fish, the corticosteroid concentration was measured in the body fluid recovered (as supernatant) after sonication and centrifugation of whole fr ... | 2001 | 11551321 |
| interactions between ecto- and endoparasites in trout salmo trutta. | trout fry were experimentally infected with endoparasites (anisakis sp.) and/or ectoparasites (gyrodactylus derjavini). during the following 3 weeks the infection level of g. derjavini was significantly lowered in fish infected with live anisakids compared to fish injected with physiological saline, a corresponding amount of anisakis protein sonicate or to untreated fish. subsequent scanning electron microscopy (sem) of recovered nematodes from the trout showed an extensive colonization of the w ... | 2002 | 11751011 |
| increased susceptibility of atlantic salmon salmo salar to infections with gyrodactylus derjavini induced by dexamethasone bath treatment. | dexamethasone, a known immunosuppressant, was administered by bath or injection to atlantic salmon salmo salar (conon stock) to study if this treatment could affect the susceptibility of fish to infections with a danish strain of gyrodactylus derjavini (monogenea). three groups of s. salar (conon stock) were immersion treated either with 10, 60 or 240 microg dexamethasone l-1 water, respectively. in addition, one group (positive control) was treated intraperitoneally with 200 microg dexamethason ... | 2003 | 12590667 |
| gyrodactylus derjavini infection elicits il-1beta expression in rainbow trout skin. | specific gene expression of the pro-inflammatory cytokine il-1beta and the type ii il-1beta receptor (il-1rii, 'decoy receptor') was studied in skin of rainbow trout oncorhynchus mykiss (walbaum, 1792) fry during infection with the ectoparasitic monogenean gyrodactylus derjavini mikailov, 1975. cytokine expression was studied in both primary and secondary infections using a semi-quantitative rt-pcr technique. generally, low levels of specific il-1beta1, il-1beta2 and il-1rii gene transcription w ... | 2003 | 12834615 |
| concomitant exposure of rainbow trout fry to gyrodactylus derjavini and flavobacterium psychrophilum: effects on infection and mortality of host. | although rainbow trout fry mortality syndrome caused by the bacterium flavobacterium psychrophilum is widespread in fish farms it is difficult to reproduce infection of rainbow trout in the laboratory using immersion exposure with bacterial suspensions. it has therefore been speculated that ectoparasites could act as enhancers of bacterial infections under natural conditions. in the present study rainbow trout fry were exposed to infections with f. psychrophilum (immersion for 30 min or 10 h) al ... | 2003 | 14597284 |
| expression of immune response genes in rainbow trout skin induced by gyrodactylus derjavini infections. | by means of semi-quantitative rt-pcr, expression of a number of immune relevant genes was studied in skin of small rainbow trout oncorhynchus mykiss (walbaum, 1792) fry during both primary and secondary infections with the ectoparasitic monogenean gyrodactylus derjavini mikailov, 1975. the target genes studied included the cyto- and chemokines tnf-alpha1, tnf-alpha2, tgf-beta and il-8, the inducible nitric oxide synthase (inos) and cyclooxygenase (cox-2) genes and finally, two cell markers, the ... | 2004 | 14741133 |
| dexamethasone treatment affects skin mucous cell density in gyrodactylus derjavini infected salmo salar. | atlantic salmon, salmo salar, is normally rather refractive to infection with the ectoparasitic monogenean gyrodactylus derjavini but dexamethasone treatment of the host increases the susceptibility. the causative mechanisms were elucidated in this work. groups of atlantic salmon were treated by intra-peritoneal dexamethasone injections and subsequently infected with g. derjavini. it was shown that both the infection level and the mucous cell density of caudal and pelvic fins were affected by th ... | 2004 | 14972042 |
| homing of gyrodactylus salaris and g. derjavini (monogenea) on different hosts and response post-attachment. | in natural european waters, the congeneric monogeneans gyrodactylus derjavini mikailov, 1975 and g. salaris malmberg, 1957 are primarily found on brown trout salmo trutta l. and atlantic salmon salmo salar l., respectively. interestingly, rainbow trout, oncorhynchus mykiss (walbaum), originating from north america, is as susceptible as brown trout to g. derjavini. however, the mechanisms involved in this host specificity are poorly understood but may include behavioural, mechanical and chemical ... | 2004 | 15357405 |
| occurrence of gyrodactylids on wild atlantic salmon, salmo salar l., in danish rivers. | three hundred and one parr of wild salmon, salmo salar l., from three river systems in denmark were examined in december 2005 and august 2006 for gyrodactylid infections. the species determination was done by morphological analyses of the opisthaptoral hard parts and molecular analyses of the internal transcribed spacer (its) region using pcr restriction fragment length polymorphism (rflp) and sequencing. five species of the genus gyrodactylus were found: gyrodactylus derjavini, gyrodactylus teu ... | 2008 | 18234020 |
| immune responses against yersinia ruckeri have no effect on colonization of rainbow trout, oncorhynchus mykiss (walbaum), by gyrodactylus derjavini (mikailov, 1975). | | 2003 | 12962227 |
| labile resistance of atlantic salmon, salmo salar l., to infections with gyrodactylus derjavini mikailov, 1975: implications for host specificity. | | 2003 | 12962211 |
| effects of aqueous aluminium on four fish ectoparasites. | effects of aqueous aluminium on four species of fish ectoparasites were studied. fish infected by gyrodactylus derjavini, g. macronychus and anodonta anatina glochidia, and free living argulus foliaceus were exposed to acidic al-rich water (ph 5.8), acidic al-poor water (ph 5.8) and control water (ph 6.3). the results showed that aqueous aluminium had a negative effect on the ectoparasites tested, without any apparent negative effect on the fish hosts. the effect of aluminium was dependent on th ... | 2006 | 16904736 |