Fish swimbladder: an excellent mesodermal inductor in primary embryonic induction. (1/551)

Swimbladder of the crucian carp, Carassius auratus, was found to be better as a vegatalizing tissue than other tissues, such as guinea-pig bone marrow, when presumptive ectoderm of Triturus gastrulae was used as reacting tissue. Swimbladder usually induced assemblies of highly organized mesodermal tissues, such as notochord, somites and pronephric tubules, some of which were covered by mesodermal epithelium without any epidermal covering. A special character of the effect of swimbladder was the rather frequent induction of solid balls of undifferentiated cells, which were identified as mesodermal or mesodermal and probably endodermal. These findings show that swimbladder has a strong and fast spreading vegetalizing effect on the responding presumptive ectoderm.  (+info)

Preliminary characterization of a reovirus isolated from golden ide Leuciscus idus melanotus. (2/551)

Some characteristics of a reovirus recently isolated from golden ide Leuciscus idus melanotus and tentatively designated as golden ide reovirus (GIRV) were determined. Spherical non-enveloped particles with an outer capsid of about 70 nm and an inner capsid of about 50 nm were observed by electron microscopy. The density of the virus determined in CsCl gradients was 1.36 g ml-1. The genome contained 11 segments of dsRNA. GIRV differed from other aquareoviruses by a slight reduction of infectivity after treatment with chloroform and by the absence of forming syncytia in cell monolayers.  (+info)

Inter-laboratory comparison of cell lines for susceptibility to three viruses: VHSV, IHNV and IPNV. (3/551)

Eleven European National Reference Laboratories participated in an inter-laboratory comparison of the susceptibility of 5 selected cell lines to 3 fish pathogenic viruses. The test included viral hemorrhagic septicaemia virus (VHSV); infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV), and the cell lines derived from bluegill fry (BF-2), chinook salmon embryo (CHSE-214), epithelioma papulosum cyprini (EPC), fathead minnow (FHM) and rainbow trout gonad (RTG-2). The results showed that for isolation of VHSV, BF-2 and RTG-2 cells performed equally well and had higher sensitivity compared to the other cell lines. For IHNV, EPC and FHM cells gave the best results, and for IPNV it was BF-2 and CHSE-214 cells. FHM cells showed the largest variability among laboratories, whereas EPC was the cell line showing the smallest variability.  (+info)

Branchial osteogenetic neoplasm in barbel Barbus barbus plebejus. (4/551)

A branchial osteogenetic neoplasm affecting a barbel Barbus barbus plebejus (Valenciennes, 1829) is described. The osteoblasts' pleomorphism, the lack of a well-developed and complete separation, the presence of eccentric, terminal proliferative edges infiltrating the lining tissues and the abundant tumour matrix suggest a histopathological diagnosis of a 'productive osteoblastic osteosarcoma'. The occurrence of eosinophilic granule cells (EGCs) scattered among neoplastic tissue is discussed in relation to the neoplastic growth and the inflammatory reaction, with reference to recent discoveries in mammalian mast cell biology.  (+info)

Phylogenetic origins of immune recognition: lymphocyte surface immunoglobulins in the goldfish, Carassius auratus. (5/551)

Membrane immunoglobulin (Ig) of splenocytes and thymocytes of the goldfish, Carassius auratus, was demonstrated by indirect fluorescent-antibody techniques. Observations on shedding and resynthesis indicated that the thymocyte Ig was endogenously produced. The lymphocyte surface proteins were radioiodinated using the lactoperoxidase-catalyzed reaction, and the labeled Ig molecules were isolated by specific precipitation and analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The IgM-like membrane Igs of splenocytes and thymocytes were shown to differ in their ease of solubilization with nonionic detergent, and in the sodium dodecyl sulfate/electrophoretic mobility of their heavy chains. The significance of these observations for the evolution of T-cell recognition is discussed.  (+info)

Experimental detection of the actinospores of Myxobolus pseudodispar (Myxosporea: Myxobolidae) in oligochaete alternate hosts. (6/551)

The development of Myxobolus pseudodispar Gorbunova, 1936, an intracellular myxosporean muscle parasite of the roach Rutilus rutilus L., was studied in experimentally infected oligochaetes. In one experiment, uninfected Tubifex tubifex Muller and Limnodrilus hoffmeisteri (Claparede) were exposed to mature spores of M. pseudodispar. Triactinomyxon spores developed both in T. tubifex and L. hoffmeisteri specimens. Triactinospores were first released from the oligochaetes 76 d after initial exposure. At that time, pansporocysts containing 8 triactinospores were located in the gut epithelium of experimentally infected oligochaetes, but free actinosporean stages were also found in their gut lumen. Each triactinospore had 3 pyriform polar capsules and an elongated cylindrical sporoplasm with 8 secondary cells. The spore body joined the 3 caudal projections with a relatively long style. One of the 3 caudal projections was shorter than the other two. The total length of the triactinospore was on average 206.5 microns.  (+info)

Establishing a captive broodstock for the endangered bonytail chub (Gila elegans). (7/551)

It is crucial for endangered species to retain as much genetic variation as possible to enhance recovery. Bonytail chub (Gila elegans) is one the most imperiled freshwater fish species, persisting as a declining population of large and old individuals primarily in Lake Mohave on the lower Colorado River. Establishment of a new captive broodstock from the 1981 F1 progeny of at most 10 wild fish plus any newly captured wild fish is evaluated and reviewed. The effective number of founders contributing to the 1981 F1 progeny appears quite small, varying from approximately 3.5, based on F1 allozyme data and supported by mtDNA data, to approximately 8.5, based on the original production records. Using a sample of these progeny to initiate a new broodstock further reduces the effective number of founders. With even the most optimistic evaluation of the amount of genetic variation in F1 progeny, it is obvious that including wild fish in the broodstock is essential to increase the amount of genetic variation. The approach given here could be applied to retain genetic variation in other endangered species in a captive broodstock until they have stable natural populations of adequate size.  (+info)

Mitochondrial DNA differentiation in the critically endangered Berg River redfin (Pseudobarbus burgi). (8/551)

The Berg River redfin (Pseudobarbus burgi) is a critically endangered endemic cyprinid from South Africa. We investigated mitochondrial DNA control region variation among specimens representative of five populations drawn from two adjacent river systems. Phylogenetic analyses, a minimum spanning network, and an analysis of molecular variance underscore the pronounced genetic separation of redfins originating from the geographically closely allied Verlorevlei and Berg Rivers, two populations that may have remained isolated since the Pleistocene. Despite a lack of geographic structuring within the Berg River, historic female gene flow among the upper and middle/lower parts of the river appears to be limited and the contemporary populations are probably isolated due to deterioration of the mainstream of the river. Our results suggest that the Berg and Verlorevlei populations should be managed as distinct conservation units. We encourage the use of sanctuaries, particularly by private landowners within both river systems, as this approach may contribute effectively to preserving genetic diversity within the species.  (+info)