PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Esocidae”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2006

Gyrodactylus neili n. sp. (Monogenea: Gyrodactylidae), a parasite of chain pickerel Esox niger Lesueur (Esocidae) from freshwaters of New Brunswick, Canada.

Gyrodactylus neili n. sp. (Monogenea: Gyrodactylidae) is described from the fins and body surface of Esox niger Lesueur (chain pickerel) (Esocidae) from the St. Croix River drainage, New Brunswick, Canada. G. neili n. sp. resembles most closely G. fryi Cone & Dechtiar, 1984, a parasite of E. masquinongy in North America, in having relatively large thin hamuli, well-developed marginal hook sickles with a relatively long, wide blade and short handle, a ventral bar with small antero-lateral processes and tongue-shaped membrane, and a cirrus with many small spines in two rows. The new species is easily separated from G. fryi by the length of the hamuli (70-76 microm versus 92 microm, respectively), by the distal width of the sickle (7-9 versus 14-16 microm, respectively) and by subtle differences in the shape of the toe and heel of the marginal hook sickle. Sequence data (922 bp) of rDNA (internal transcribed spacers 1 and 2 and 5.8S) of G. neili n. sp. returned no identical matches in GenBank. The 5.8 sequence alone, however, was identical to morphologically similar gyrodactylids of the subgenus Gyrodactylus from cyprinid fishes in Eurasia. The discovery of G. neili n. sp. and features of its genetic makeup support the idea that this lineage parasitised ancestral cyprinids and that it radiated, possibly through predator/prey interactions, to an ancestor of contemporary Esox. It is concluded that DNA comparison of monogeneans on Holarctic freshwater hosts, such as E. lucius, may shed light on the nature of speciation of these parasites.

Animals↗
PubMed1979

Polymorphic tetrameric superoxide dismutase in the pike Esox lucius L. (Pisces; Esocidae).

1. Heart muscle extracts of northern pike from Lake Malaren in Sweden exhibited two electophoretic types of superoxide dismutase, one of which was identified as the cytoplasmic enzyme (s-SOD) and the other as the mitochondrial form (m-SOD). 2. Individual analysis of 51 pike indicated that s-SOD was invariant while m-SOD displayed a pattern of variation which was explicable by a single-locus polymorphism. 3. The observed m-SOD phenotype patterns suggested that the enzyme is a tetramer. This interpretation is supported by in vitro molecular hybridization studies.

Animals↗
PubMed2003

Acetylcholinesterase and butyrylcholinesterase activities in brain and plasma of freshwater teleosts: cross-species and cross-family differences.

Brain and plasma acetylcholinesterase (AChE; EC 3.1.1.7) and plasma butyrylcholinesterase (BChE; EC 3.1.1.8) specific activities were assayed in 16 freshwater teleosts belonging to four families: Cyprinidae, Percidae, Esocidae and Lotidae. Brain AChE activity varied among fish species approximately 15-fold, ranging from 138 to 2011 micromol/g per h. All cyprinids had higher brain AChE activity than other fish families. Plasma AChE activity was on average 100-fold lower than that in brain, varying from 1.2 to 18.6 micromol/ml per h. Plasma BChE activity was found only in cyprinids with the exception of the common and crucian carp, and sabrefish. It varied from 26 to 1083 micromol/ml per h. In bream (Abramis brama) only 30% of specimens studied had BChE activity. The correlation coefficient values between activities of brain and plasma AChE, brain AChE and plasma BChE, plasma AChE and BChE were 0.67, 0.68 and 0.84, respectively. Cross-species and also cross-family differences in AChE and BChE activities among fish were demonstrated. Possible reasons for the differences are discussed.

Acetylcholinesterase↗
PubMed1998

On the evolution within the family Gyrodactylidae (Monogenea).

On the basis of six main types of protonephridial systems in the genus Gyrodactylus and results from further studies of the protonephridial systems in other gyrodactylid genera and other monogenean families, evolutionary lines within the Gyrodactylidae and the origin of the genera Ooegyrodactylus, Swingleus, Gyrdicotylus and Polyclithrum are discussed. An excretory bladder (on both sides of the body) with separate openings for the main canals of the anterior and the posterior systems, a median junction between the two anterior systems and likewise a junction between the two posterior systems, many flame bulbs and an absence of lateral flames in the main canals were found to be primitive monogenean characters. A system similar to that in the acanthocotylid larva but with secondarily evolved lateral flames in the posterior systems may have given rise to a first protogyrodactylid system, in turn giving rise to the system of Macrogyrodactylus. In a second protogyrodactylid line, the main canal of the anterior system (on both sides of the body) was connected to that of the posterior system and lateral flames were developed also in the anterior system. From this system all other described gyrodactylid systems may arise: one main line gave rise to the system of the G. (Gyrodactylus) and another to a system of G. (Mesonephrothus) type. The systems of Swingleus and Gyrdicotylus are of the latter type. Through loss of all lateral flames, the system of G. (Metanephrotus) may have evolved. Isancistrum has a system of the G. (Metanephrotus) type. From this type of system, those of Polyclithrum, G. (Neonephrotus), G. (Paranephrotus) and G. (Limnonephrotus) can be derived. The fact that the system of Ooegyrodactylus is more closely related to that of G. (Gyrodactylus) than to that of Macrogyrodactylus prompts discussion regarding the evolution of the viviparity of the family Gyrodactylidae. According to the evolutionary system presented, primitive gyrodactylids parasitise primitive fish species and the most advanced gyrodactylids parasitise the most advanced fish species. However, Anguillidae and Clupeidae may have been secondarily infected by members of G. (Metanephrotus) and G. (Neonephrotus) respectively, and Cyprinidae, Salmonidae and Esocidae may similarly have been secondarily infected by members of G. (Limnonephrotus). Isancistrum may have infected squids (Loligidae) at a medium level in the evolution within the Gyrodactylidae, while progenitors of Gyrdicotylus may have been adapted to clawed toads (Xenopidae) earlier in evolution.

Animals↗
PubMed2000

Comparative study of acetylcholinesterase and butyrylcholinesterase in brain and serum of several freshwater fish: specific activities and in vitro inhibition by DDVP, an organophosphorus pesticide.

A comparative study of specific activities and in vitro inhibition of brain and serum acetylcholinesterase (AChE; EC 3.1.1.7) and serum butyrylcholinesterase (BChE; EC 3.1.1.8) by DDVP, an organophosphorus pesticide, was conducted in 11 freshwater teleost species belonging to four families (Cyprinidae; common carp Cyprinus carpio, bream Abramis brama, blue bream A. ballerus, white bream Blicca bjoerkna, roach Rutilus rutilus, bleak Alburnus alburnus, ide Leuciscus idus; Percidae: perch Perca fluviatilis, pikeperch Stizostedion lucioperca; Esocidae: pike Esox lucius and Coregonidae: whitefish Coregonus albula). Specific AChE and BChE activities in brain and serum of fish were determined. Brain AChE activity varied among fish species approximately 10-fold, ranging from 192.6 to 1353.2 micromol g(-1) h(-1), respectively in perch and whitefish. All cyprinids had higher brain AChE activity than those of other fish families. Serum AChE activity was 100-fold lower than in brain. Serum BChE activity was found only in cyprinids with the exception of the common carp. It varied from 163.8 to 970.3 micromol g(-1) h(-1), respectively in roach and bleak. The bimolecular enzyme inhibition rate constants (kIIs) and pI50) values for DDVP were calculated. Sensitivity of fish AChEs both in brain and serum is similar to those of typical AChEs in mammals. The range of kIIs was 3.4-51.7 x 10(3) mol(-1) 1 min(-1) (pI50s were 5.3-6.5), respectively in white bream and ide. In contrast, fish serum BChE was more sensitive to inhibition than typical BChE and AChE in mammals. Values of kII for BChE were 1.0-2.5 x 10(7) mol(-1) 1 min(-1) (pI50 was 8.8-9.2), respectively in ide and bleak.

Acetylcholinesterase↗
PubMed2002

Speciation by host switch and adaptive radiation in a fish parasite genus Gyrodactylus (Monogenea, Gyrodactylidae).

Four hundred Gyrodactylus species have been formally described, but the estimated number of species in this fish ectoparasite genus of Monogenean Platyhelminthes is more than 20,000. The unusually high species richness has lead to the hypotheses of speciation and adaptive radiation via host switching. These hypotheses were tested by reconstructing a molecular phylogeny for the subgenus G. (Limnonephrotus) which is a group of freshwater parasites, including five species infecting wild and farmed salmonids. The highly variable ITS1 and ITS2 segments and the conservative 5.8S ribosomal gene were sequenced in 22 species plus two species representing the subgenus G. (Paranephrotus) as an outgroup. The phylogeny was compared with host systematics: the species were collected from six fish families (Cyprinidae, Salmonidae, Percidae, Esocidae, Gasterosteidae, and Gobitidae). The phylogenetic analysis demonstrated that G. (Limnonephrotus) is a monophyletic group that was originally hosted by cyprinids. The speciation has occurred in two episodes, the older one manifested in genetic distances 25-33% (4-6 Myr BP). The latter speciation burst occurred in one clade only, perhaps one million years ago. This clade has been morphologically identified as a wageneri species group. It is a monophyletic group of 18 species [studied here] and contains all five salmonid parasites, but also parasites, on cyprinids, percids, esocids, and gasterosteids. In G. (Limnonephrotus), eight host switches crossing the host family barrier were observed, and at least three of them were followed by repetitive speciation. Seven host-switch events were statistically confirmed by bootstrapping. The suggested model of speciation by host switch was accepted, and interestingly the adaptive radiation seems to be a consequence of host switch to a new family (key innovation model). The molecular and ecological evolution rate of Gyrodactylus parasites is manyfold in comparison to host species, and the phylogenies are largely independent and disconnected.

Animals↗
PubMed1993

Fluoride and iron concentrations in the enameloid of lower teleostean fish.

Our quantitative elemental analyses with the electron microprobe indicated that the fluoride and iron concentrations in the enameloid of bony fish are related to the phylogeny of fish. The enameloid of some bony fish with high F also contained high Fe. In order to clarify the phylogenetic significance of such a peculiar dual deposition of F and Fe into developing enameloid, quantitative electron microprobe analyses of these elements were made on the teeth of taxonomically lower teleosts. There were significantly different trends of F and Fe concentrations in the enameloid among various forms of lower teleosts. In the Osteoglossiformes, the enameloid of the osteoglossid species contained very low levels of F and Fe, whereas in the single representative of the Mormyroidei, the F was very low but Fe was very high. In the Elopomorpha, the enameloid of the elopiform species contained a medium level of F and high Fe, and that of the anguilliform high levels of F and Fe. In the Salmoiformes, the salmonid species had medium F and high Fe, and in a species of the Esocidae, high F and high Fe levels were found. The stomiiform fish exhibited levels of medium and high F and high Fe. The results of the present study and our previous investigations made on archaic non-teleostean and various teleostean fish indicate that the mechanisms of F and Fe concentrations into developing enameloid are independent of each other, and that the mechanisms of Fe concentration appeared earlier and disappeared later than, or concurrently with, that of the F concentration, in the course of fish evolution.

Amelogenesis↗
PubMedDate not supplied

[Phylogenetic analyses of the family Tetraonchidae (Platyhelminthes: Monogenea)].

A phylogenetic reconstruction of the monogenean family Tetraonchidae was carried out by methods of parsimony-based cladistics. The analysis included 20 species of tetraonchids and two out-groups (Sundanonchus tomanorum and Dactylogyrus amphibothrium) and was based on 34 morphofunctional characters. Software PAUP 4.0 and Winclada were used for the phylogenetic reconstructions. Obtained results allow proposing a preliminary phylogenetic hypothesis of the family Tetraonchidae along with the discussion of host-parasite association. According to the current taxonomic view, the family Tetraonchidae included two genera. Cladistic analysis showed a monophyly of the family and the genus Tetraonchus Diesing, 1858. Two representative of the former genus, Tetraoncus monenteron and T. borealis, parasitize the pikes (Esocoformes: Esocidae) and the grayling (Salmonidae: Thymallinae) respectively. The genus Salmonchus Spassky et Roytman, 1958 has a complicated structure and its intrageneric relationships were not completely resolved; in general, the analysis allows to recognise several species groups: Salmonchus oncorhynchi--the parasite of the Oncorhynchus masou smolt living during the first year of life in fresh water; four species (S. variabilis, S. gussevi, S. grumosus, S. alaskensis) inhabiting specifically the whitefishes (Salmonidae: Coregoninae); all reminder of Salmonchus species occurring on the salmons (Salmonidae: Salmoninae). The bootstrap test gives a support only for the following clades: family Tetraonchidae (75%), genus Tetraonchus (88%); a group of Salmonchus species associated with the whitefishes (93%) and grouping of four species (S. huhonis, S. pseudolenoki, S. skrjabini and S. lenoki) from the lenoks (Brachymystax) and taimens (Hucho) (61%).

Animals↗
PubMed2003

[Is the parasite fauna of Poland well recognized?].

The studies of parasite fauna have in Poland a long tradition. Generally the helmint fauna of all groups of vertebrates was more or less examined and as much as over 100 species of Monogenea, almost 400 Digenea, over 250 Cestoda, about 500 Nematoda and 32 Acanthocephala have been recorded. The best recognized are the helminths of fish (especially those of Cyprinidae, Esocidae, Percidae and Salmonidae), frogs examined in various regions of Poland, some birds (especially connected with water environment: Anseriformes, Ciconiformes, Podicipediformes), most of insectivores (although examined only in few localities), European bisons, deers, foxes and wild boars (all under permanent monitoring), as well as domestic animals (cattle, horses, sheeps) and pets. Such groups like some amphibians, reptiles, bats, carniwores, some birds (especially Passeriformes, Charadriiformes, falcons and eagles) need further exploration, as some host species were not the subject of parasitological investigation. In some cases it will be rather difficult goal, as most of these animals are under strict preservation, and only dead (naturally or accidentally) specimens can be autopsied.

Animals↗
PubMed1998

Androgenesis and homozygous gynogenesis in muskellunge (Esox masquinongy): evaluation using flow cytometry.

The purpose of this work was to study the effects of ultraviolet (UV) irradiation on denucleation of eggs and investigate the heat-shock conditions for diploidization for induction of androgenesis in muskellunge, Esox masquinongy. Several egg incubation media, including saline, Ringer's solution, and Ringer's solution supplemented with bovine serum albumin (BSA), were found suitable to maintain the egg fertility as high as in muskellunge ovarian fluid. The optimal doses of UV radiation were 660-1320 J/m2, at which 100% haploid larvae were produced at a hatching rate of 22.5 +/- 2.8%. UV irradiation at low doses (165-330 J/m2) generated abnormal larvae, which were morphologically identical to haploids. Using a flow cytometry method, it was found that cellular DNA content of these larvae was close to that of diploids but significantly lower in value and had a wider distribution (expressed as coefficient of variation) than that of control fish. This suggested that a low dose of UV irradiation might cause gene mutations, alteration of chromosomal conformation and fragmentation, but did not prevent maternal DNA from participating in mitotic division. Interference of maternal DNA residues could be another reason for the poor viability of androgenetic fish. A high dose of UV radiation (1980 J/m2) caused development of severely deformed embryos, indicating that UV radiation also damaged molecules in the eggs other than the denucleation. Our results suggest that classic color and allozyme markers might not be sufficient to prove a complete androgenesis. In order to optimize time and duration of shock for induced diploidization, we investigated the heat-shock conditions for inhibiting the first mitotic cleavage through induction of homozygous gynogenesis. We found that heat-shock treatment at 31 degrees C for 9 min starting at 1.4 tau 0 (a dimensionless factor describing progress in embryo development) after fertilization produced the highest percentage of diploids at hatching.

Animals↗
PubMed2000

Induction of gynogenesis in muskellunge with irradiated sperm of yellow perch proves diploid muskellunge male homogamety.

Diploid gynogenesis was induced in muskellunge Esox masquinongy using UV-irradiated muskellunge sperm as the first step in producing monosex females. In this approach, we have to rely on negative controls as an indirect reference for sperm genetic material destruction. In the first experiment, equal proportions of gynogenetic females and males were produced. Negative controls, UV-irradiated sperm without heat shock, yielded some normal hatching larvae, described as spontaneous diploids. In the second experiment, muskellunge eggs were activated using sperm from yellow perch. Because hybrids between these species are not viable, we produced unambiguous gynogens. When UV-irradiated yellow perch sperm was used to inseminate muskellunge eggs, haploids resulted (22.5% +/- 2.8% survival to the eyed stage). To produce diploid gynogens, a heat shock of 31 degrees C was applied to inseminated eggs 20 min after activation for a duration of 6 min. This process yielded several hundreds of gynogens for rearing. Several treatments of masculinizing hormone, 17alpha-methyltestosterone (MT), were carried out. Fish were dissected and gonads examined histologically for sex determination. Gynogens produced using yellow-perch sperm confirmed the presence of males in the control group, whereas the MT bath treatment (400 microg/liter) resulted in the production of fish with ovotestis. These results provide evidence for male homogamety in muskellunge and imply that a change of strategy is needed to produce monosex populations.

Animals↗
PubMed1979

Synaptic connections linking cones and horizontal cells in the retina of the pikeperch (Stizostedion vitreum).

Cones and horizontal cells of the pikeperch retina were studied with morphological and physiological techniques. Gap junctions were observed between cone pedicles and basal processes emitted by neighboring cones. Intracellular recordings showed that the light-evoked hyperpolarizing cone response was enhanced by light falling upon neighboring receptors within a radius of 50 microns. We suggest that the network of gap junctions between cones mediates the summative lateral interaction described. Three sub-classes of horizontal cells (H1, H2, H3) send dendrites to cones; H1 and H2 cells appear to contact twin cones, exclusively or preferentially, whereas H3 cells appear to synapse only with single cones. Horizontal cells of the same sub-class are joined by gap junctions between dendrites or at the lateral faces of perikarya. These unions extend over several micron 2 and as seen in transmission electron microscopy consist of patches of close apposition alternating with areas of membrane separation, folding and occasional zonulae adherents. Freeze-fracture profiles of horizontal gap junctions show localized areas of dense particle aggregation on the P-face and pits on the E-face flanked by regions of unspecialized membrane. These morphological findings provide support for the known spatial and color-coding properties of pikeperch horizontal cells.

Animals↗
PubMed1994

Immunocytochemical localisation of hydroxyindole-O-methyltransferase in pineal photoreceptor cells of several fish species.

Melatonin is an internal "Zeitgeber," involved in the timing and control of a number of rhythmic functions and behaviours. Its synthesising cells remain to be identified in the fish pineal. The last step in the melatonin biosynthetic pathway is catalysed by the enzyme hydroxyindole-O-methyltransferase. An affinity-purified antibody, directed against chicken pineal hydroxyindole-O-methyltransferase, was used in the present study to identify the melatonin synthesising cells in four fish species: a primitive chondrostean (sturgeon), a saltwater teleost (dorado), and two freshwater teleosts (pike, trout). Western blot immunolabeling of pike and trout pineal proteins revealed a single band at 38 KDa, which corresponds to the known molecular weight of the enzyme in bovine, rat, and chicken pineal. Regardless of the species, a specific immunocytochemical labeling, visualised by means of the peroxidase-antiperoxidase method, was exclusively associated with the photoreceptor cells. These results provide evidence that photoreceptors of the fish pineal are responsible for the biosynthesis of 5-methoxyindoles, including melatonin. In the pike, reactions were less intense in the distal portion of the pineal vesicle than in the other regions of the organ. It is questioned whether this might be related to the existence of a germinative zone, generating new photoreceptor cells in this distal portion. Hydroxyindole-O-methyltransferase has been previously demonstrated in mammalian pinealocytes, and modified photoreceptors of the avian pineal. It is now demonstrated in pineal photoreceptors of a primitive fish and of more evolved saltwater and freshwater fish. The results strengthen the view that these cells are related through phylogeny and that their well conserved melatoninergic function appears early in the course of evolution.

Acetylserotonin O-Methyltransferase↗