The debate about the pattern of muscle formation in teleost fish has recently been heightened in the literature. Here we examine superficial muscle development in the pearlfish, a cyprinid endemic to a small area of Central Europe, and uninfluenced by economic interest and breeding. Using light and electron microscopy, histochemistry and immunohistochemistry techniques, we report that: (1) Superficial fibre precursors originate close to the notochord, are part of the same cell population as the so-called muscle pioneer cells, and are transferred laterally to end up at the surface of the myotome. (2) Superficial fibre maturation is exceptionally rapid. Structural and enzymatic functionality is attained at a time when prospective deep fibres have not passed beyond the early myotube state. This strong contrast weakens as the embryo develops. (3) Apart from the muscle pioneers, the superficial fibres appear to be capable of functioning before they receive any direct innervation, implying that signals are transferred to these fibres via cell-to-cell junctions. We suggest that the capability of rapid superficial fibre maturation is a rather general feature among teleosts and may aid pre-hatch survival under a variable environment. Our results indicate that muscle formation in teleost fish may follow a common basic pattern that is open to considerable ontogenetic and phylogenetic modification in response to habitat conditions.
The patterns ofcoiling of the gut were compared in 22 species of Eurasian Cyprinidae. In selected species, also the length of gut and mucosal surface structure were compared. Piscivorous (Aspius u.spiu.s). planktivorous (Ahramis hullerus) fishes as well as species feeding mainly on plankton and wind-borne ' drift ' (Alburnus alburnus, Pelecus cullrarus) have the relatively shortest guts, with only a single loop. The same simple arrangement of a short gut is present in many euryphagous species with more or less carnivorous tendencies (Abrumis scipa, Alhurnoides bipunctatus, Ahramis hruma. Bliccu hjoerkna. Chalcalhurnus chalcoides men to. Gohio gohio, Leuciscuy cephalus. Luuciscus Ieuciscus, Rutilirs rulilus, Scardinius erythrophthalmus. Tinca tinca. Vimhu vimba). Some benthivorous winnowers (oropharyngeal sorters) and species with herbivorous feeding tendencies have relatively long guts showing a more complex pattern of loops and coils (Barhus harhus. Cumssius carassius, Chondrostoma nasus. Ctenophuryngodon idelia, Cyprinus carpio). The goldfish, Curassius auratus, has the most complex coils. Scanning electron microscopy of the mucosal surface revealed five types of folding in the intestinal bulb which were only loosely related to feeding: I. smooth surface (Aspius aspius, Leuciscus cephalus, Vimha vintba); 2, irregularly branching folds (Alhurnus alburnus, Barbus barhus, Blicca bjoerknu, Chalcalhurnus chalcoides mento, Luuciscirs Ieuciscus, Rutilus rutilus. Scardinius erythrophthalmus); 3, curl-like folds (Tincu tinca); 4, nct-like folding pattern (Ahramis brama); 5. honeycomb-like mucosal structure (Cyprinus carpio).
We studied the status of Crested newt (Triturus cristatus superspecies) ponds in the province of Salzburg during the years 2004 and 2005. Historical and current distribution data were collected and compared. In the end of 2004, 51 ponds with Crested newt records of which 39 still existed were known in Salzburg. In 2005 we carried out a monitoring of these ponds using a combination of three survey methods. Presence or absence of adult and larval Crested newts and the number of syntopic amphibian species were recorded. Detection probabilities and the effects of seven characteristic pond features on pond occupancy were calculated for adult and larval newts separately. We observed a strong decline of ponds occupied by Crested newts with presence of adults in 22 and presence of larvae in 16 surveyed ponds, respectively. Detection probabilities imply that we detected all ponds occupied by adults and larvae. Key habitat features for Crested newt presence are low degree of shading for adults and larvae as well as a high density of submerged vegetation for larvae. Pond size and depth are not significant. Furthermore we recorded a significantly higher number of amphibian species in ponds occupied by Crested newts. Our results might aid in the implementation of sustainable measures for a conservation of these critically endangered species in the province of Salzburg.
The purpose of the present study was to investigate patterns of circadian rhythmicity in the retina of a salmonid fish, the rainbow trout (Oncorhynchus mykiss). In a first attempt to show both morphological and neurochemical variations during light/dark conditions (LD) and during continuous darkness (DD), we investigated retinomotor movements and the associated regulatory transmitters, dopamine and melatonin. All parameters studied showed patterns of rhythmicity in LD and DD, clearly indicating the presence of an endogenous clock in the rainbow trout eye. The most salient variations of all parameters studied were found at the transitions from light to dark and vice versa in LD and from subjective day to subjective night and vice versa in DD. The amplitudes of rhythms compared between LD and DD were similar in pigment index, whereas a clear reduction was found for cone index, dopamine and melatonin.
Three regions of the axial complex in Sphaerechinus granularis can be distinguished: 1) The axial organ which protrudes from one side of the axial sinus; the sinus septum which separates the sinus from the body cavity and encloses the stone canal; the pulsating vessel which runs along the inside of the axial organ. 2) The blindly-ending terminal sinus in which the pulsating vessel broadens out to the contractile terminal process. 3) The ampulla of the stone canal which connects the axocoel and water vascular system and which opens out through the madreporite. A single-layered, monociliated coelomic epithelium surrounds all regions of the axial complex. This epithelium contains smooth muscle cells at the contractile areas. Canaliculi, surrounded by basal lamina, are formed through infolding of epithelia; they end blindly in the fluid- and connective tissue-matrix of the inner structures. The lacunae of the dorso-ventral mesentery connect the periesophageal and the perianal haemal ring with the axial organ. The axial organ contains many coelomocytes rich in pigment and granules. These coelomocytes are separated into compartments by elastic fibres. Phagocytosis of whole cells and transformational stages of coelomocytes suggest storage and degradation functions. An excretory function via the water vascular system is also suggested.
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