Systemic herpes-like virus in catfish Ictalurus melas (Italy) differs from Ictalurid herpesvirus 1 (North America)

A herpesvirus was isolated during 2 occurrences of mass mortality among adult catfish Ictalurus melas raised in different farms in northern Italy. The agent replicated in the channel catfish ovary (CCO) cell line from channel catfish I. punctatus, inducing a cytopathic effect similar to that caused by Ictalurid herpesvirus 1 (also referred to as channel catfish herpesvirus, CCV). The new herpesvirus, designated I. melas herpesvirus (IcmHV) did not react with polyclonal rabbit or monoclonal antibodies directed to CCV in either neutralization or indirect immunofluorescence assays. The virions of IcmHV possessed a hexagonal nucleocapsid of 107 nm in diameter surrounded by an envelope with a diameter of 227 nm (n = 20) typical for members of the family Herpesviridae. Virions of IcmHV purified from infected CCO cells contained 17 polypeptides ranging in size from 17.5 to 175 kDa and most differed in molecular weight from those found for CCV. The IcmHV was also distinct from CCV when compared by restriction fragment length polymorphisms (RFLP) of genomic DNA following digestions with the endonucleases Kpn I and Sac I. Lastly, the virulence of IcmHV for channel catfish fry and juveniles, respectively, was demonstrated by experimental infections induced by bath exposure or intraperitoneal injection that resulted in 78 to 96% cumulative mortality in groups of exposed fish. Preventing the introduction of this agent into geographic regions where significant channel catfish production occurs should be a high priority.     

A study of the peripheral innervation and muscle fibre types of Ictalurus nebulosus (Lesueur) and Ictalurus punctatus (Rafinesque)

The innervation pattern and fibre types of the axial musculature of two closely related catfish species with differing lifestyles, Ictalurus nebulosus (Lesueur) and I. punctatus (Rafinesque) were investigated. Both fish displayed the multiple innervation pattern in the red muscle. However, the white muscle of I. nebulosus demonstrated terminal innervation while I. puncrurus displayed multiply innervated white muscle fibres. Fibre typing utilizing histochemical techniques for glyco-gen, lipid, succinic dehydrogenase and glucose-6-phosphate dehydrogenase revealed the typical teleostean distribution of red, intermediate and white muscle fibres in both fish. Staining was greatest in the red muscle fibres and least in the white muscle fibres. The white muscle fibres of I. punctatus stained slightly more for lipid than the white fibres of I. nebulosus which may be correlated with a greater aerobic capacity related to lifestyle and possibly innervation.     

The non-indigenous freshwater fishes of Flanders (Belgium): review, status and trends over the last decade

Fourteen non-indigenous fish species have been successfully introduced to the wild within the territory of Flanders; nine are considered naturalized. Most of the introductions occurred prior to 1950, with six species introduced since then. This paper reviews the available, hitherto scattered, information (including 'grey literature') on these 14 non-indigenous fish species introductions, and evaluates a decade of data from fisheries surveys to assess the recent development of these non-indigenous populations. Gibel carp Carassius gibelio and topmouth gudgeon Pseudorasbora parva are the most widespread of the non-indigenous species in Flemish waters, and both continue to expand their ranges. A reduction in range has been observed in brown bullhead Ameiurus nebulosus only. A case is presented for not including European catfish Silurus glanis , sunbleak Leucaspius delineatus and European bullhead Cottus gobio on the list of non-indigenous freshwater fishes in Flanders. Also discussed are non-indigenous fish species that are likely to colonize Flanders inland waters in the near future.     

Electrophoretic and isoelectrophoretic characteristics of hemoglobins of Italian Ictalurids

Electrophoretic and isoelectrophoretic behaviour of the hemoglobins of Italian freshwater Ictalurids was analysed. Multiple and polymorphic hemoglobin patterns were found in Ictalurus sp. (I. nebulosus nebulosus?, I. melas?); multiple and monomorphic patterns in I. n. marmoratus and I. punctatus. Hypotheses are advanced for further investigation of the question.     

Iridoviruses associated with epizootic haematopoietic necrosis (EHN) in aquaculture

Systemic infections of teleost fishes caused by iridoviruses have recently been recognized in Australia, Asia, Europe and the USA. These iridoviruses are different from those of the established genera Lymphocystivirus and Goldfish Virus 1-like Viruses of the family Iridoviridae. The agents exhibit similar physicochemical properties, are antigenically related and prove to be of high virulence to different teleost fishes in aquaculture. The first iridovirus, epizootic haematopoietic necrosis virus, responsible for an epizootic outbreak of haematopoietic necrosis in redfin perch, was reported in Australia. Some years later, similar iridovirus epizootics occurred in sheatfish and catfish in Europe. The Australian and the European isolates proved to be antigenically related and showed properties in common with frog virus 3, the type species of the genus Ranavirus of the Iridoviridae. Further iridovirus isolates from fish, amphibians and reptiles exhibited a close relationship with each other and with frog virus 3. It is important to note that the Australian amphibian iridovirus, Bohle iridovirus, was experimentally transmitted to teleost fish inducing high mortalities. The occurrence of similar viruses in different host species in the aquatic environment and their inter-species transmission emphasize the importance of health control in aquaculture.     

New records of endoparasitic helminths in alien invasive fishes from the Carpathian region

Six non-native invasive fish species from the Slovak part of the Tisa River basin, namely Carassius gibelio, Pseudorasbora parva, Ameiurus melas, A. nebulosus, Lepomis gibbosus, Perccottus glenii, and three gobiid species from the Danube River, namely Neogobius melanostomus, N. fluviatilis and N. kessleri, were investigated for endohelminth parasites. The expanding Asian cestode Nippotaenia mogurndae (syn. Amurotaenia perccotti) (Nippotaeniidea) has been introduced to Europe with its invasive host P. glenii. Pumpkinseed, Lepomis gibbosus, is a new definitive host of Proteocephalus percae and it is reported as the second intermediate host of the bothriocephalidean cestode Triaenophorus nodulosus in Slovakia.     

GEOGRAPHIC POPULATION STRUCTURE AND SPECIES DIFFERENCES IN MITOCHONDRIAL DNA OF MOUTHBROODING MARINE CATFISHES (ARIIDAE) AND DEMERSAL SPAWNING TOADFISHES (BATRACHOIDIDAE)

Restriction-fragment length polymorphisms in mitochondrial DNA (mtDNA) were used to evaluate population-genetic structure and matriarchal phylogeny in four species of marine fishes that lack a pelagic larval stage: the catfishes Arius felis and Bagre marinus, and the toadfishes Opsanus tau and O. beta. Thirteen informative restriction enzymes were used to assay mtDNAs from 134 specimens collected from Massachusetts to Louisiana. Considerable genotypic diversity was observed in each species. However, major mtDNA phylogenetic assemblages in catfish and toadfish (as identified in Wagner networks and UPGMA phenograms) exhibited contrasting patterns of geographic distribution: in catfish, distinct mtDNA clades were widespread, while such clades in toadfish tended to be geographically localized. By both the criteria of species' ranges and the geographic pattern of intraspecific mtDNA phylogeny, populations of marine catfish in the western Atlantic have had greater historical interconnectedness than have toadfish. Results are also compared to previously published mtDNA data in freshwater and other marine fishes. Although mtDNA differentiation among conspecific populations of continuously distributed marine fishes is usually lower than that among discontinuously distributed freshwater species inhabiting separate drainages, it is apparent that historical biogeographic factors can importantly influence genetic structure in marine as well as freshwater species.     

两种鮰科鱼类鳃部寄生的普氏趋鮰虫形态描述及系统发育分析

2018年9月至2019年10月,对新疆乌鲁木齐市区及巴楚县的鱼类进行寄生虫病原调查过程中,在斑点叉尾鮰(Ictalurus punctatus)和云斑(鱼回)(I. nebulosus)鳃部发现有单殖吸虫寄生,两种鱼所寄生的虫种形态基本一致,仅连接片形态稍有差异,通过形态学鉴定为锚首虫科(Ancyrocephalidae)趋(鱼回)虫属(Ligictaluridus)的普氏趋(鱼回)虫(L.pricei)。为验证形态鉴定的准确性,扩增了寄生虫的28S rDNA序列,并进行了系统发育分析。结果显示,两种鱼所寄生的单殖吸虫与普氏趋(鱼回)虫的相似度均达98%以上,在系统进化树中紧密聚为一支,置信度均为100;同时,两种虫与普氏趋(鱼回)虫间的遗传距离数值接近于零,表现出了很高的相似度和亲缘关系。因此根据形态特征和系统发育分析,确定这两种鱼感染的是同一种寄生虫。研究结果可为新疆人工养殖(鱼回)科鱼类的病害防治提供依据。     

Amphibian glucagon family peptides: potent metabolic regulators in fish hepatocytes

Peptides analogous to glucagon-like peptide-1 (GLP-1) have been isolated from amphibian pancreas and intestine, and their amino acid sequences and cDNA structures elucidated. Just like their mammalian counterpart, these peptides are potent insulinotropins in mammalian pancreatic cells. We show here that these peptides also exert strong glycogenolytic actions when applied to dispersed fish hepatocytes. We compared the potencies of three synthetic GLP-1s from Xenopus laevis and two native GLP-1s from Bufo marinus in the activation of glycogenolysis in the hepatocytes of a marine rockfish (Sebastes caurinus) and two freshwater catfish (Ameiurus nebulosus and A. melas), and demonstrated their effectiveness in increasing the degree of phosphorylation of glycogen phosphorylase. We also compared the glycogenolytic potency of the peptides with those of human GLP-1 and glucagons from human and B. marinus. Sensitivity to these peptides is species-specific, with the rockfish responding at lower concentrations to GLP-1s and the two catfish reacting better to glucagons. However, the relative potency of the amphibian GLP-1s and glucagons is similar in the three species. Xenopus GLP-1C (xGLP-1C) is consistently more potent than xGLP-1B, while xGLP-1A displays the smallest activation of glycogenolysis. Similarly, Bufo GLP-1(32)-the peptide with the highest amino acid sequence identity to xGLP-1C-always shows a higher potency than Bufo GLP-1(37), which is closely related to xGLP-1B. The relative hierarchy of these glycogenolytic GLP-1s differs from their ranking as insulinotropins in mammalian beta-cells.In the rockfish system, Bufo glucagon-36, a C-terminally extended glucagon, is more potent than the shorter bovine glucagon and Bufo glucagon-29 in the activation of glycogenolysis; when tested in A. nebulosus hepatocytes, bovine and amphibian glucagons are equipotent. Amphibian GLP-1s and glucagons activate glycogenolysis in fish hepatocytes through increased phosphorylation of glycogen phosphorylase, implying involvement of the adenylyl cyclase/protein kinase A system in signal transduction. We conclude that the broad physiological effectiveness of GLP-1 has been retained throughout vertebrate evolution, and that both insulinotropic activity and glycogenolytic actions belong to the repertoire of GLP-1.     

The distribution of Poecilancistrium caryophyllum (Trypanorhyncha) plerocercoids in spot, Leiostomus xanthurus Lacèpéde, and spotted seatrout, Cynoscion nebulosus (Cuvier)

Spotted seatrout, Cynoscion nebulosus (Cuvier), and spot, Leiostomus xanthurus Lacèpéde, from two sites along Florida's west coast were collected, weighed, sexed and measured. A systematic search for plerocercoids of the cestode Poecilancistrium caryophyllum yielded infection prevalences of 81.9% for C. nebulosus and 25.0% for L. xanthurus . The maximum infection intensity was 10 (mean = 2.65) plerocercoids per fish in C. nebulosus and six (mean = 1.69) per fish in L. xanthurus . Significant correlations were found between infection prevalence and length in C. nebulosus , and a significant correlation was observed between intensity and length in both species. Condition coefficient ( K ) and intensity were negatively correlated in C. nebulosus but not in L. xanthurus . An iterative computer technique based on the truncated negative binomial distribution indicated no parasite-induced mortality occurred in either species. Sand drum, Umbrina coroides Cuvier, is reported as a new host record for P. caryophyllum .     

Mortality and pathology in brown bullheads Amieurus nebulosus associated with a spontaneous Edwardsiella ictaluri outbreak under tank culture conditions

Brown bullheads Amieurus nebulosus (family Ictaluridae) are commonly used as a sentinel of environmental contamination. These fish are not generally cultured under laboratory conditions and little is known about their disease susceptibility. Here we report an outbreak of disease due to Edwardsiella ictaluri in a laboratory population of tank-reared, wild-caught brown bullheads. The isolate was positively identified as E. ictaluri using standard bacteriological substrate utilization tests and a monoclonal antibody specific for this bacterium. This pathogen causes a significant disease in channel catfish Ictalurus punctatus and is associated with disease in other ictalurid and non-ictalurid fishes. It appears that E. ictaluri is also a significant pathogen in brown bullheads and produces clinical signs and lesions similar but not identical to those observed in channel catfish. Since commercial sources of bullheads for laboratory tank studies are not available, precautions should be taken to prevent potential E. ictaluri disease outbreaks from wild-caught bullheads intended for laboratory research.     

Role of Anopheles melas Theobald (1903) on malaria transmission in a mangrove swamp in Saloum (Senegal)

From June 1995 to January 1998, entomological studies carried out in five villages located in the Delta's Saloum have allowed to better understand the contribution of An. melas Theobald (1903) to malaria transmission in mangrove swamp. Among the five villages studied, three of them (Simal, Djilor and Marlothie) located along the Saloum river, are colonised by An. arabiensis; the two others (Djifere and Diakhanor) located between the sea and the river, are colonised by An. melas. During the rainy season and at the beginning of the dry season, An. melas and An. arabiensis are sympatric. The ratio of An. melas/An. arabiensis increases when we go closer the coast where An. melas becomes quite exclusive. When An. melas is predominant, endophagy, endophily and anthropophily are very marked. The parturity rates are lower in An. melas than in An. arabiensis. In the predominance area of each species, transmission is on the same level. During the period of sympatry, An. arabiensis is responsible for the transmission and when it is absent, An. melas carries on. Transmission occurs from July to March with a maximum at the beginning of the dry season. In the villages of the mangrove swamp, its prolongation until the middle of the dry season is due to An. melas.     

Seasonal effects on some serum and muscle enzymes of catfish (Ictalurus melas) and common carp (Cyprinus carpio)1

Serum and muscle activities of enzymes (LDH, ALD, CK and ICDH) in intensively farmed catfish (Ictalurus melas) and common carp (Cyprinus carpio) were determined bimonthly between July 1 and November 2. Catfish serum enzymes showed no significant differences under different environmental conditions (exception = CK; values increased slighfly in the last sample). In carp serum, a remarkable increase of LDH and ALD occurred during the cold season. Muscle enzyme activity decreased in both species with decreasing water temperature and reduced metabolic activity.     

Systematic status and first description of male of Dujardinia cenotae Pearse, 1936 [= Hysterothylacium cenotae (Pearse, 1936) Moravec et al., 1995] (Nematoda: Anisakidae)

A new collection of adult anisakid nematodes from the intestine of the catfish Rhamdia guatemalensis from two cenotes (= sinkholes) and a cave in the Yucatan Peninsula, southeastern Mexico, has shown that they are conspecific with those inadequately described as Dujardinia cenotae Pearse, 1936. The female is redescribed and the male is described for the first time. The morphology of this species shows that it belongs to the genus Hysterothylacium. This is the only Hysterothylacium species recorded from freshwater fishes in Mexico and it may well be endemic to cenotes and caves of the Yucatan Peninsula.     

Biosociology and ecology of pomacentrid fishes around the Sinai Peninsula (northern Red Sea)

Pomacentrid fishes inhabiting the coral formations along the Red Sea coast of Sinai Peninsula form specific groups of species on various habitats. Amphirion bicinctus, Dascyllus aruanus, D. marginatus and Pomacentrus trichourus are typical for the backreef lagoon; Pomacentrus sulfureus, Abudefduf melanopus and A. melas are common along the rearreef wall; Pomacentrus albicaudatus, P. tripunctatus, Abudefduf lacrymatus, A. leucozona and A. annulatus dominate the coral reef table. The forereef wall is occupied by Abudefduf saxatilis, A. sexfasciatus and A. leucogaster . The lower part of the forereef and coral knolls along it are inhabited by groups of Abudefduf azysron, Chromis dimidiatus, C. caeruleus, C. ternatensis and of the Dascyllus trimaculatus . Among the fishes observed a part are living in groups or schools, whereas others are typical solitary, permanent territory holders. Most of them are polygamous, breeding in colonies, or solitary in nests, guarded by males. The variation in feeding behaviour as well as in sociobiology, enables the high diversity of these fishes on various parts of the habitat.     

Inhibition of adenylate cyclase of catfish and rat hepatocyte membranes by 9-(tetrahydro-2-furyl)adenine (SQ 22536).

The adenosine analogue 9-(Tetrahydro-2-furyl)adenine, SQ 22536, inhibited adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity of crude membrane preparations from catfish (Ictalurus melas) and rat isolated hepatocytes in a non-competitive manner. The IC50s were reduced in the presence of NaF. SQ 22536 reduced the activity of adenylate cyclase also in the presence of increasing concentrations of GTP, as well as Mg++ and Mn++. In the presence of catecholamines (epinephrine, norepinephrine, isoproterenol, phenylephrine) SQ 22536 reduced their activating effect on adenylate cyclase in both catfish and rat membranes. SQ 22536 also inhibited the effect of glucagon (0.1 microM) on rat membrane cyclase activity.     

Comparative tolerance to gas supersaturated water of carp, Cyprinus carpio, and black bullhead, Ictalurus melas, from the U.S.A. and Italy

Supersaturation of surface water with atmospheric gases may result from hydroelectric or thermoelectric power generation and adversely affect aquatic biota. Although the phenomenon has been extensively studied in the northwestern United States, its occurrence is less well documented in Europe. We evaluated the tolerance of carp, Cyprinus carpio , and black bullhead, Ictalurus melas , from Italy to gas supersaturated water and compared our results to data reported in the literature for the same species from the Columbia River, U.S.A. Carp and black bullhead from Italy were more susceptible to gas supersaturation than those from the Columbia River. This may reflect greater adaptation of Columbia River fish due to their historical exposure to supersaturated water resulting from numerous hydroelectric dams.     

The isozymes of lactate dehydrogenase, malate dehydrogenase and glucosephosphate isomerase in Italian ictalurids

1. The isozymes of lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and glucose-phosphate isomerase (GPI) of three species of Italian ictalurids: Ictalurus sp., I. nebulosus marmoratus, and I. punctatus, were analyzed. 2. Isoelectric focusing (IEF) was applied to polyacrylamide gel plates, and the isozymes revealed by means of specific histochemical staining. 3. Species-specific monomorphic patterns were found for LDH. 4. In contrast, MDH and GPI have the same patterns in I. sp. and I. nebulosus marmoratus and different patterns in I. punctatus. 5. Comparison of the isozymatic patterns of the three species clearly showed the close relationship between I. sp. and I. nebulosus marmoratus and the relative taxonomic distance of I. punctatus, and thus the early detachment of this last species from a presumptive common ancestral lineage.