Hepatic respiratory compensation and haematological changes in the cave cyprinid, Phreatichthys andruzzii

In several ectotherms, including all members of the Osteichthyes studied so far, the spleen is capable of storing and releasing erythrocytes according to the animal's respiratory needs. The tropical cave cyprinid Phreatichthys andruzzii uses its liver rather than the spleen as the site of accumulation in the respiratory compensation process, like the amphibian Rana esculenta. The reversible process of erythrocyte accumulation in the liver is very evident in animals anaesthetized with chlorobutanol; MS-222, an anaesthetic widely used in lower vertebrates alters all the haematological parameters and is not suitable for studies on blood and respiration. The hepatic respiratory compensation mechanism is as efficient as the splenic one: in animals kept at 18 °C for 24 h the mean liver weight percentage was 70% higher than in specimens kept at 28 °C (2.43% of the body weight compared to 1.39%, in groups of six specimens) while mean red blood cell counts fell from 2.49 to 1.60 · 10¹² per l, in agreement with the haematocrit value and haemoglobin concentration; mean corpuscular volume remained constant (at about 177 fl). Accepted: 15 April 1997     

Characterization and development of SSR markers of schizothoracine fish (Cypriniformes: Cyprinidae) based on SLAF-seq Technique

Highly specialized grade of Schizothoracine fishe is primarily distributed in the drainage of Qinghai-Tibet Plateau and its surrounding region, which has precious biological resources. However, overfishing and habitat destruction have seriously affected the germplasm resources and population genetic structure of HSG, so it is a significance to search for reliable genetic markers to protect its wild resources. In this work, 27 novel polymorphic microsatellite were firstly generated for the entire HSG based on the SLAF data of the grade and assess their polymorphism in HSG from 4 genera of 8 species. Among which W24, W41, W50 were existed only in 3–4 populations with low amplification efficiency, and loci of W3, W6, W12, W25, W28, and W32 were absent in 1–3 species, the rest of that 18 loci were successfully amplified in all specimens. The average of the number of alleles (NA) per locus was 46.04, ranging from 12 to 79, and the average observed and expected heterozygosities were estimated from 0.539 to 0.785 and 0.471 to 0.669 in 8 species, respectively. The average polymorphic information content (PIC) of each species was from 0.669 to 0.433. The range of average Shannon-Weiner diversity index (H') were calculated from 0.914 to 1.717 in 8 species. To sum up, we developed 27 microsatellite loci with higher quality and stability, which could provide effective technical support for the study of germplasm resources of highly specialized grade of schizothoracine fishe.     

Immunocytochemical characterization of adenohypophyseal cells in the greater weever fish (Trachinus draco)

The adenohypophysis of the greater weever fish (Trachinus draco) was studied using histochemical and immunocytochemical methods. The adenohypophysis comprised the rostral pars distalis (RPD), the proximal pars distalis (PPD), and the pars intermedia (PI). Neurohypophysis showed a patent hypophyseal stalk which was divided into several branches intermingled with the adenohypophysis. Salmon prolactin (PRL)-immunoreactive (ir) cells, arranged in follicles, resided in the RPD and the most rostral part of the ventral PPD. Human adrenocorticotropin (ACTH)-ir cells were located in the RPD between PRL-ir cells and the neurohypophyseal processes. Salmon and seabream somatotropin (GH)-ir cells were located in both the dorsal and the ventral PPD. Some GH-ir cells were seen in surrounding and in contact with neurohypophyseal branches, whereas other isolated or clustered GH-ir cells were embedded in adenohypophyseal cells of the PPD. In addition, isolated or clustered GH-ir cells were also detected in the tissue of the PPD covering the most rostral part of PI. Only one class of salmon and carp gonadotropin (GTH)-ir cells was detected. Isolated or clustered GTH-ir cells resided in both the dorsal and the ventral PPD and were seen surrounding the PI and in the tissue of the PPD covering the most rostral part of PI. In addition, a few scattered GTH-ir cells were observed in the ventral RPD. Scattered groups of thyrotropin (TSH)-ir cells were present in the anteroventral PPD. Salmon and seabream somatolactin (SL)-ir and bovine melanotropin (MSH)-ir cells were intermingled surrounding the neurohypophyseal tissue. SL-ir cells were negative to periodic acid-Schiff technique. MSH-ir cells showed a very weak immunoreactivity to anti-human ACTH((1-24)) serum. In addition to the PI location, few isolated or clustered SL- and MSH-ir cells were observed in the dorsal PPD.     

Occurrence of keratinization in the structures associated with lips of a hill stream fish Garra lamta(Hamilton)(Cyprinidae,Cypriniformes)

Keratinized regions were found to occur in the rostral cap, adhesive pad and horny jaw sheaths associated with the lips of Garra lamta, which inhabits fast flowing turbulent hill streams. In these structures, the surface epithelial cells were modified into characteristic keratinized spine‐like or columnar tooth‐like unculi, which would provide firm anchorage for the fish on the substratum and assist the fish in browsing or scraping food materials from it.     

Predictors of body shape among populations of a stream fish (Cyprinella venusta,Cypriniformes: Cyprinidae)

Performance‐related variation in fitness can manifest as morphological responses to ecological and evolutionary pressures. Eco‐morphological studies often utilize stark binary comparisons, such as lentic to lotic populations of freshwater fishes, to characterize relationships between form and function despite possible complications from confounding factors. In the present study, we compared body shape variation among lotic populations of a stream fish (Cyprinella venusta Girard) to disentangle the influence of ecological and evolutionary drivers of phenotypic change. We assessed the extent to which body shape corresponded to three key environmental factors (mean channel velocity, mean discharge, and mean annual run‐off), phylogeny (mitochondrial DNA divergence), and body size (centroid size). We also examined relationships between these parameters and a fineness index, which is a measure of streamlining and morphological optimization for steady swimming performance. All three environmental variables had some explanatory power, although morphological characteristics were predominantly associated with variation in mean annual run‐off. Phylogeny was also a strong predictor of morphological variation, whereas body size had little predictive power. Populations experiencing higher mean annual run‐off exhibited a shorter base of the dorsal fin, a more slender body and caudal peduncle, a smaller head in both horizontal and vertical dimensions, and a more anterior placement of the eye. With some exceptions, such as variation in jaw length, differences in body shape associated with phylogenetic history were similar to those associated with run‐off. Notably, all clades exhibited parallel responses to variation in run‐off. Populations experiencing high mean annual run‐off approached a hydrodynamic optimum, suggesting a morphology optimized for steady swimming performance. In contrast to previous studies that emphasize the importance of average water velocity, the findings of the present study indicate that morphological variation among populations of stream fishes is tightly linked to more complex aspects of hydrology and evolutionary history. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●● , ●●–●●.     

Predation of a cave fish (Poecilia mexicana, Poeciliidae) by a giant water-bug (Belostoma, Belostomatidae) in a Mexican sulphur cave

Abstract.  1. Caves are often assumed to be predator-free environments for cave fishes. This has been proposed to be a potential benefit of colonising these otherwise harsh environments. In order to test this hypothesis, the predator–prey interaction of a belostomatid (predator) and a cave fish (prey) occurring in the Cueva del Azufre (Tabasco, Mexico) was investigated with two separate experiments.
2. In one experiment, individual Belostoma were given a chance to prey on a cave fish, the cave form of the Atlantic molly ( Poecilia mexicana ), to estimate feeding rates and size-specific prey preferences of the predator. In the other experiment, population density of Belostoma was estimated using a mark–recapture analysis in one of the cave chambers.
3. Belostomatids were found to heavily prey on cave mollies and to exhibit a prey preference for large fish. The mark–recapture analysis revealed a high population density of the heteropterans in the cave.
4. The absence of predators in caves is not a general habitat feature for cave fishes. None the less predation regimes differ strikingly between epigean and hypogean habitats. The prey preference of Belostoma indicates that cave-dwelling P. mexicana experience size-specific predation pressure comparable with surface populations, which may have implications for life-history evolution in this cave fish.     

An immunocytochemical and electron-microscopical study of endocrine cells in the gut and pancreas of a stomachless teleost fish,Barbus conchonius (Cyprinidae)

Summary Four immunoreactive endocrine cell types can be distinguished in the pancreatic islets of B. conchonius: insulin-producing B cells, somatostatin-producing A₁ (= D) cells, glucagon-producing A₂ cells and pancreatic poly-peptide-producing PP cells. The principal islet of this species contains only a few PP cells, while many PP cells are present in the smaller islets. Except for the B cell all pancreatic endocrine cell types are also present in the pancreatic duct.At least six enteroendocrine cell types are present in the gut of B. conchonius: 1. a cell type (I) with small secretory granules, present throughout the intestine, and possibly involved in the regulation of gut motility; 2. a C-terminal gastrin immunoreactive cell, probably producing a caerulein-like peptide; these cells are located at the upper parts of the folds, especially in the proximal part of the intestinal bulb; 3. a met-enkephalin-immunoreactive cell, present throughout the first segment; 4. a glucagon-immunoreactive cell, which is rare in the first segment; 5. a PP-immunoreactive cell, mainly present in the first half of the first segment; 6. an immunoreactive cell, which cannot at present be specified, located in the intestinal bulb. The latter four cell types are mostly located in the basal parts of the folds, although some PP-immunoreactive cells can also be found in the upper parts.Most if not all enteroendocrine cells are of the open type. The possible functions of all enteroendocrine cell types are discussed.Abbreviations BPP bovine pancreatic polypeptide - CCK cholecystokinin - GEP gastro-entero-pancreatic - GIP gastric inhibitory peptide or glucose-dependent insulin releasing peptide - PPP pig pancreatic polypeptide - VIP vasoactive intestinal polypeptide     

Immunohistochemical localization of (neuro)peptide hormones in endocrine cells and nerves of the gut of a stomachless teleost fish,Barbus conchonius (Cyprinidae)

Summary Enteroendocrine cells containing glucagon-, substance P-, neurotensin- and VIP-like substances have been demonstrated immunocytochemically in the gut of Barbus conchonius. Mainly based on the distribution of the immunoreactive endocrine cells in this and a previous^* study, at least eight different enteroendocrine cell types appear to be present in this stomachless fish: 1. C-terminal-gastrinimmunoreactive cells^*, predominantly present in the upper parts of the folds of the proximal part of the intestinal bulb. 2. Metenkephalin-immunoreactive cells^*, basally located in the folds of the first segment. 3. Pancreatic polypeptide (PP)-immunoreactive cells^*, mainly present in the first half of the first segment. 4. Glucagon-like-immunoreactive (GLI) cells that are basally located in the folds of the first segment and that contain a different polypeptide (possibly glicentin) than pancreatic glucagon cells. 5. Substance P-immunoreactive cells, present in the upper parts of the folds throughout the gut. 6. C-terminal-neurotensin-immunoreactive cells, basally located in the folds throughout the first segment. 7. Vasoactive intestinal polypeptide (VIP)-immunoreactive cells, present in small numbers in the proximal part of the intestinal bulb. 8. Nonspecifically-immunoreactive cells^*, found throughout the intestinal bulb. Many VIP-immunoreactive nerves have been demonstrated in the smooth muscle layer and myenteric plexus of the gut; furthermore some of them are peptide histidineisoleucine (PHI)-immunoreactive. Substance P-, somatostatin-, neurotensin- and met-enkephalin-immunoreactive nerves are also found. Thus, at least partial sequences of four different mammalian neuropeptide hormones (VIP, substance P, neurotensin, met-enkephalin) occur both in endocrine cells and enteric nerves of the gut of B. conchonius.     

Anophthalmia and elongation of body appendages in cave scale worms (Annelida: Aphroditiformia)

This study addresses whether cave dwelling annelids exhibited similar reductive and constructive traits equally as strong as those of arthropods and vertebrates inhabiting caves. Known as troglomorphism, these adaptations bring about striking morphologies across invertebrates and vertebrates from both aquatic and terrestrial cave habitats, and include varying degrees of eye and pigmentation loss, as well as hypertrophy of body appendages and sensorial structures. Employing phylogenetic comparative methods and ancestral character reconstructions on a worldwide data set of a group of annelids, the scale worms (Aphroditiformia), we investigate the behavioural and morphological traits of species living in marine caves in comparison with those species living outside caves. Our work demonstrated that cave scale worms respond similar to arthropods in cave environments, showing a significant elongation of sensory parapodial cirri, while lacking eyes and pigmentation. However, whereas elongation of sensory appendages likely occurred in correlation to cave colonization, eyes were plausibly lost in correlation with specialization and colonization of deep‐sea habitats.     

Isolation of microsatellite loci in the freshwater fish,the bitterling Rhodeus sericeus (Teleostei: Cyprinidae)

We isolated 30 microsatellites from the freshwater fish, the bitterling Rhodeus sericeus. Twenty‐three microsatellite sequences possessed sufficient flanking DNA from which to design primers. Twelve loci were characterized and all were found to be polymorphic. These loci were isolated and characterized as part of a project to investigate the consequences of male alternative mating tactics and sperm competition using the bitterling as a model species.     

Functional morphology of the anchorage system and food scrapers of a hillstream fish, Garra lamta (Ham.) (Cyprinidae, Cypriniformes)

The functional morphology of the anchorage system and food scrapers of a hillstream fish, Garra lamta (Ham.) is described in relation to their role in the swift water current of the hillstreams (Ranchi, Bihar, India).     

The ontogeny and homology of the Weberian apparatus in the zebrafish Danio rerio (Ostariophysi: Cypriniformes)

The ontogeny of the Weberian apparatus was examined in the zebrafish, Danio rerio , using both cleared and stained specimens and histology. Over 300 individuals from four independent zebrafish lineages, ranging in size from 3 to 28 mm TL, were examined for this study. Results provide a basic understanding of the development of the Weberian apparatus in the wild-type zebrafish. Our results, in conjunction with those already published, point to substantial variation in the development of the Weberian apparatus among otophysans and new interpretations of the homology of certain ossicles (e.g. tripus and claustrum). Hypotheses of homology among various Weberian ossicles are considered and represent an important step in understanding the evolution of sound transmission in ostariophysan fishes.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 241–254.     

Early development of the endemic dace Telestes karsticus (Leuciscidae,Cypriniformes) in a Dinaric karst stream in Croatia

Early development of the endemic dace Telestes karsticus is described in a Dinaric karst stream in Croatia. Larvae were acquired from successful rearing in an aquarium. Basic morphometric and meristic measures of larvae were taken during 55 days of observation. The mean total length of larvae at the time of hatching was 6.45 mm. The yolk sac was completely absorbed in all larvae by day 9 post-hatching (PH), when the mouth also opened and independent feeding and intestinal function were observed. Flexion of the urostyle was completed between days 12–16 PH. The caudal fin became completely forked on day 23 PH. Formation of fin rays was complete on day 48 PH when fish fully resembled juvenile specimens. The number of soft ray fins corresponds to the adult. Understanding the early development is particularly valuable in assessing environmental impacts and recovering of this endangered species and it is essential for effective monitoring and its conservation. This is the first report of the early development for the endemic Telestes karsticus, pointing out the importance of the obtained results for the effective conservation of the species.     

Note on the karyotype and NOR phenotype of leuciscine fish Acanthobrama marmid (Osteichthyes, Cyprinidae)

The karyotype and major ribosomal sites as revealed using silver staining of Anatolian leuciscine cyprinid fish Acanthobrama marmid were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs of subtelocentric to acrocentric chromosomes. The largest chromosome pair of the complement was subtelo-to acrocentric characteristically, which is a characteristic cytotaxonomic marker for representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were detected in the telomeres of two pairs of medium sized submeta-to subtelocentric chromosomes. No heteromorphic sex chromosomes were found. The karyotype pattern of A. marmid is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple NOR phenotype appears to be more derived as opposed to a uniform one, ubiquitous in this group.     

Four fish species new to the Omo-Turkana basin,with comments on the distribution ofNemacheilus abyssinicus (Cypriniformes: Balitoridae) in Ethiopia

Four fish species,Pollimyrus isidori (Mormyridae),Barbus paludinosus, Labeo forskalii (Cyprinidae), andNemacheilus abyssinicus (Balitoridae), new to the Omo-Turkana basin, were recorded from the Gojeb River, a tributary of the Omo River (south-western Ethiopia). Occurrence of the latter species in the upper reaches of the Blue Nile and of the Omo drainage substantiates the belonging of the upper parts of these water systems to the Abyssinian highlands ichthyofaunal province.     

The effect of water acidification on prolactin cells and pars intermedia PAS-positive cells in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus and Carassius auratus

Summary Although exposure to acid water (pH 3.5) induces severe and prolonged reduction in plasma osmolarity and total plasma calcium concentration in tilapia (Oreochromis mossambicus) and goldfish (Carassius auratus), the responses of the hypophyseal cells are clearly different. In tilapia, the size of the rostral pars distalis of the pituitary gland is enlarged as a result of the increase in size and number of prolactin cells. The pars intermedia PAS-positive (PIPAS) cells are not noticeably changed. Conversely, in goldfish, prolactin cells are unaffected, whereas the number of enlarged PIPAS cells increases markedly. Stimulation of prolactin secretion may be responsible for the partial restoration of plasma osmolarity and calcium levels observed in tilapia after two weeks exposure to acid water. Prolactin cells apparently play a role in the adaptation to acid stress by counteracting osmoregulatory disturbances. Goldfish show no restoration of plasma osmolarity during the course of the experiment. Plasma calcium levels tend to increase. Although prolactin may have an osmoregulatory function in goldfish under steady state conditions, goldfish prolactin cells do not seem to participate in the physiological adaptation to environmental changes that disturb water and ion homeostasis. The function of PIPAS cells in tilapia remains unclear and is apparently unconnected with ion regulation. The observations on these cells in goldfish are consistent with the hypercalcemic activity suggested for them.     

Immunocytochemical identification of prolactin cells in the pituitary gland of tilapia larvae (Oreochromis mossambicus: Teleostei)

Summary Using an antiserum to highly purified chum salmon prolactin, prolactin cells were identified in the putative rostral pars distalis of newly hatched tilapia larvae (Oreochromis mossambicus) by the immunogold method for the electron microscope. In the putative rostral pars distalis, some cells had another kind of secretory granule which was much less numerous, much smaller in size, and without immunoreactivity to salmon prolactin antiserum. Controls incubated with salmon prolactin-preabsorbed antiserum or normal serum showed no immunoreactive cells, confirming the specificity of the antiserum. The possible role of prolactin in the osmoregulation of tilapia larvae is discussed.     

Metabolic responses of fish larvae [Rutilus vutilus (L.)] to forced activity (Cyprinidae, Teleostei)

Larvae of Rutilus rutilus (L.) weighing approx. 40 mg were exercised for 5 min by mechanical stimulation. Individual larvae were taken before and immediately after stimulation, and during 2 h of recovery. The concentrations of glucose, glucose-6-phosphate, pyruvate, lactate, 2-oxoglutarate, and ascorbic acid were determined in individual larvae. The larvae recovered faster from forced activity than juvenile roach, recovery being complete after 1 h. Larvae also differed from juveniles in that metabolite levels increased less during activity. It is suggested that the combination of low glycolytic, and high oxidative capacity was responsible for the specific metabolic responses of the larvae.