[Role of the group effect in the exploratory behavior of Lebistes reticulatus L. (cyprinodontiform Poeciliidae fishes)].
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Animals↗
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[Action of adrenaline and ephedrine hydrochloride on the activity of Lebistes reticulus (Peociliidae--Cyprinodontiformes)].
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Animals↗
Novel relationships among ten fish model species revealed based on a phylogenomic analysis using ESTs.
The power of comparative phylogenomic analyses also depends on the amount of data that are included in such studies. We used expressed sequence tags (ESTs) from fish model species as a proof of principle approach in order to test the reliability of using ESTs for phylogenetic inference. As expected, the robustness increases with the amount of sequences. Although some progress has been made in the elucidation of the phylogeny of teleosts, relationships among the main lineages of the derived fish (Euteleostei) remain poorly defined and are still debated. We performed a phylogenomic analysis of a set of 42 of orthologous genes from 10 available fish model systems from seven different orders (Salmoniformes, Siluriformes, Cypriniformes, Tetraodontiformes, Cyprinodontiformes, Beloniformes, and Perciformes) of euteleostean fish to estimate divergence times and evolutionary relationships among those lineages. All 10 fish species serve as models for developmental, aquaculture, genomic, and comparative genetic studies. The phylogenetic signal and the strength of the contribution of each of the 42 orthologous genes were estimated with randomly chosen data subsets. Our study revealed a molecular phylogeny of higher-level relationships of derived teleosts, which indicates that the use of multiple genes produces robust phylogenies, a finding that is expected to apply to other phylogenetic issues among distantly related taxa. Our phylogenomic analyses confirm that the euteleostean superorders Ostariophysi and Acanthopterygii are monophyletic and the Protacanthopterygii and Ostariophysi are sister clades. In addition, and contrary to the traditional phylogenetic hypothesis, our analyses determine that killifish (Cyprinodontiformes), medaka (Beloniformes), and cichlids (Perciformes) appear to be more closely related to each other than either of them is to pufferfish (Tetraodontiformes). All 10 lineages split before or during the fragmentation of the supercontinent Pangea in the Jurassic.
Animals↗
Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: morphology, histology, and immunohistochemistry.
Morphology, histology, and immunohistochemistry of the adrenocortical and adrenomedullary homologs (adrenal glands) of the following developing and adult teleosts were examined: Salmoniformes-Oncorhynchus mykiss (rainbow trout), Salmo trutta fario (brown trout), Coregonus lavaretus (white fish); Cyprinodontiformes-Gambusia affinis (mosquito fish). Perciformes-Dicentrarchus labrax (sea bass), Sparus aurata (sea bream), Diplodus sargus (white bream), Oblada melanura (saddled bream). The anatomical relationships of the gland with the renal system and venous vessels were also noted. In adults of all species steroidogenic and catecholaminergic chromaffin cells were found in the head kidney, which is pronephric in origin and subsequently transformed into a hematopoietic lymphatic organ. In Perciformes, chromaffin cells are distributed around the anterior and posterior cardinal veins and ducts of Cuvier; in Salmoniformes, around the posterior cardinal veins and in the hematopoietic tissue; and in G. affinis, around the ducts of Cuvier and posterior cardinal veins, while a few are visible also around the sinus venosus. In Perciformes and Salmoniformes, numerous chromaffin cells are also present in the posterior kidney, derived from the opisthonephros, in contact with the caudal vein. Steroidogenic cells are always confined to the head kidney. During development chromaffin and steroidogenic cells appear early after hatching in the pronephric kidney, at the level of the ducts of Cuvier and of the cephalic part of the posterior cardinal veins. Later, chromaffin cells in Perciformes reach the anterior cardinal veins, and subsequently, in both Perciformes and Salmoniformes, they reach the developing posterior kidney. Their localization along the posterior kidney is still in progress about 4 months after hatching and is completed about a year after hatching. These findings support the concept that the structure of the adrenal gland in teleosts is intermediate between that of the other actinopterygians and that of tetrapods. The development differs from that of tetrapods in that it occurs mainly in the pronephros and only later do chromaffin cells reach the opisthonephric kidney.
3-Hydroxysteroid Dehydrogenases↗
Mhc class I genes of swordtail fishes, Xiphophorus: variation in the number of loci and existence of ancient gene families.
Swordtail fishes and platies in the genus Xiphophorus (order Cyprinodontiformes, Teleostei) encompass 22 closely related species which are the products of a recent adaptive radiation in the streams of Central America. To investigate the evolution of the major histocompatibility complex (Mhc) genes in the period immediately following speciation, the class I genes from 20 of the 22 species were cloned and characterized by sequencing. The analysis revealed the existence of multiple loci (at least seven in some individuals) whose numbers vary among the different species and probably also among individuals of the same species. The variation does not seem to bear any relationship to the taxonomy of the genus. Genes at the different loci are distinguished by their intron sequences and by the presence of characteristic motifs in exons 2 and 3. The variation in copy number of loci may have been effected in part by unequal crossing over occurring between introns of misaligned closely related genes. The sequences of the genes fall into two groups, A and B, which represent ancient lineages. The groups define two families of loci, which diverged from each other an estimated 85 million years ago, before the separation of the Acanthopterygii from the Paracanthopterygii of the advanced bony fishes. Evolution of the genes within each family can be explained by the birth-and-death process driven by gene duplications and mutational differentiation.
Amino Acid Sequence↗
Cloning of cytochrome P450 1A (CYP1A) genes from the hermaphrodite fish Rivulus marmoratus and the Japanese medaka Oryzias latipes.
To use two small fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and the Japanese medaka Oryzias latipes (Belloniformes) as testing models in molecular ecotoxicology, we have cloned the cytochrome P450 1A (CYP1A) gene after screening of both genomic DNA libraries, and sequenced 11,863 and 7,243 bp including all the exons and introns with promoter regions, respectively. The Rivulus and the medaka CYP1A gene consisted of seven exons (including non-coding exons) with high homology to mammals. In the promoter region, Rivulus CYP1A gene has seven xenobiotic response elements (XREs) and two metal response elements (MREs), while the Japanese medaka CYP1A gene has six XREs and four MREs. Interestingly, medaka CYP1A gene has a number of MREs at the promoter, which may affect its response on metal exposure. We describe here the gene structure of both fish CYP1A genes.
Animals↗
Cloning and sequence analysis of the self-fertilizing fish Rivulus marmoratus immediate early gene c-fos.
We have cloned the proto-oncogene c-fos from a self-fertilizing fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) after screening of R. marmoratus lambdaGEM-11 genomic DNA library, and sequenced over 12 kb including all exons, introns and the promoter region. The R. marmoratus c-fos gene consisted of one noncoding exon and four exons with high similarity to those of fugu and mammals. We sequenced approximately 7 kb of the R. marmoratus c-fos gene promoter region to gain a better understanding of the molecular anatomy of the immediate response of this gene upon cellular damage. In the promoter region, R. marmoratus c-fos gene has seven xenobiotic response elements (XREs) and eight metal response elements (MREs) as well as two estradiol (E2), 4 NFkappaB, 2 CarG, 2 prolactin (PRL) motifs and one pit1 site, while the 3'-UTR of this gene contains the estrogen response element (ERE). The seven XRE and eight MRE motifs raise the possibility of its regulation by exposure to environmental pollutants. In this paper, we discuss the gene structure of R. marmoratus c-fos gene and compare its promoter region with those of other organisms' c-fos genes. We propose its potential use in ecotoxicology.
Amino Acid Sequence↗
Assessment of environmental stress by the micronucleus test and the Comet assay on the genome of teleost populations from two natural environments.
The aim of the present paper was to assess the biological damage caused by exposure of the test organism (Gambusia holbrooki: Cyprinodontiformes, Poecilidae) to various mutagenic agents present in the polluted waters of the Sarno River. For this purpose, we performed a micronuclei (MN) test and single cell gel electrophoresis (the Comet assay), testing DNA migration in an electrophoretic field using erythrocytes of G. holbrooki specimens both from the Sarno River and from the waters of the crater of the Astroni natural reserve as negative controls. The results indicate statistically higher values for both MN and DNA migration in the samples from the Sarno River compared with those from Astroni and point to a strong genotoxic action of the mixture of pollutants present in the Sarno River. These data were compared with the values found in the G. holbrooki specimens from the Sarno River kept under laboratory conditions for 100 days in clean water.
Animals↗
New observations on Mexiconema cichlasomae (Nematoda: Dracunculoidea) from fishes in Mexico.
The dracunculoid nematode Mexiconema cichlasomae Moravec, Vidal et Salgado Maldonado, 1992, originally described from the abdominal cavity and viscera of Cichlasoma spp. from Mexico, was recorded from the abdominal cavity of the poeciliid Xiphophorus helleri Heckel in Lake Catemaco and its small tributary Arroyo Agrio, Veracruz and from the intestine of the nurse shark Ginglystoma cirratum (Bonnaterre) off the southern coast of the Gulf of Mexico in Campeche; both these findings represent new host records. The nematode specimens from these hosts are briefly described and illustrated. Whereas X. helleri evidently served as the true definitive host of this parasite, G. cirratum probably acquired Mexiconema infection accidentally while feeding on fish definitive hosts in the brackish or salt-water environment. The ability of M. cichlasomae to utilize fishes of different orders (Perciformes and Cyprinodontiformes) as definitive hosts is rather exceptional among dracunculoid nematodes.
Animals↗
Effects of diflubenzuron on growth and glutathione in mosquito fish (Gambusia affinis).
Although some biological control agents and related biorational approaches are available for mosquito control, insecticides remain the principal control method. In addition, the secondary affects of conventional insecticides in environment has led to the discovery of more target-specific chemical such as insect growth regulators. Dimilin (25% WP), the common name of diflubenzuron, prevent molting by interfering with chitin synthesis in several insect orders. This study evaluate toxicity of this insecticide on a larvivorous non-target species, Gambusia affinis (Cyprinodontiformes: Poeciliidae). Dimilin, applied for 24 h at a concentration of 78 ng/l, corresponding to the LD90 against the fourth instar larvae of Culex pipiens (Diptera: Culicidae) was first tested on growth and development of 7-day old juvenile mosquitofish during 45 days following treatment. Results showed that dimilin caused significant (p < 0.01) reduction in both length and weight of juveniles from days 30 following treatment, compared to controls. In a second series of experiments, designated for measurements of glutathione (GSH), adults of G. affinis were exposed continuously to a concentration of 78 ng/l for 30 days. Treatment resulted in a significant reduction in the amount of glutathione in mosquitofish bodies starting day 15 during treatment, compared to controls.
Animals↗
Mycobacteriosis in mangrove killifish (Rivulus magdalenae) caused by living fish food (Tubifex tubifex) infected with Mycobacterium marinum.
Mycobacterium marinum was demonstrated in the mud tube worm Tubifex tubifex. These worms served as live fish food for aquarium fishes. The ingestion of Tubifex tubifex by the mangrove killifish Rivulus magdalenae, a neotropical species in the order Cyprinodontiformes, was the source of an atypical mycobacteriosis of these fishes.
Animal Feed↗
Comparative study of the anatomy and laminar organization in the olfactory bulb of three orders of freshwater teleosts.
The anatomy and lamination of the olfactory bulb in Cyprinus carpio, Tinca tinca, Barbus bocagei (Fam. Cyprinidae, Or. Cypriniformes); Salmo gairdneri (Fam. Salmonidae, Or. Salmoniformes); and Gambusia affinis (Fam. Poeciliidae, Or. Cyprinodontiformes), all of them freshwater teleosts, are studied. These species show significative differences on the location, size, morphology, and lamination of their olfactory bulbs. The presence of a new stratum in the olfactory bulb of Salmo gairdneri and a completely different laminar organization in the olfactory bulb of Gambusia affinis are described for the first time. The anatomical and histological peculiarities of this structure in the orders studied could be the basis for different experimental approaches.
Animals↗
Modifications of the falciform process in the eye of beloniformes (Teleostei: Atherinomorpha): evolution of a curtain-like septum in the eye.
In order to comparatively analyze curtain-like septa in the eyes of visually orientated "close-to-surface-predators" among atherinomorph teleosts, we examined the eyes of 24 atherinomorph species under a binocular microscope with regard to the falciform process and related structures in the vitreous cavity. Additionally, falciform process samples were analyzed by transmission electron microscopy. All the studied representatives of the Cyprinodontiformes and Atheriniformes, and of one of the beloniform suborder, Adrianichthyioidei, possess a "typical" processus falciformis. In the eyes of the representatives of the other beloniform suborder, Belonoidei, however, pigmented structures that originate in the region of the optic disc and protrude into the vitreous cavity were noted. In the Hemiramphidae (halfbeaks) and Exocoetidae (flying fishes) these pigmented structures have a more cone-like shape, whereas in the Belonidae (needlefishes) and Scomberesocidae (sauries) horizontally oriented heavily pigmented curtain-like septa occur that divide the vitreous cavity dorsoventrally. It is suggested that the "typical" processus falciformis represents a plesiomorphic feature within the Atherinomorpha, whereas the pigmented modifications of the falciform process must be seen as a synapomorphic character state of the Belonoidei. The curtain-like septum of the Belonidae and Scomberesocidae might have evolved from the cone-like structures that are found in the Exocoetoidea. The functional significance of the pigmented structures in the eye is as yet not clear, except for the curtain-like septum found in Belonidae. It might play a role in visual orientation near the water surface at Snell's window.
Animals↗
Sexual selection constrained by internal fertilization in the livebearing fish Xenotoca eiseni
Fish of the family Goodeidae have an advanced form of viviparity but males lack a specialized copulatory organ. Goodeids show reduced sexual-size dimorphism compared with the other livebearing families of the order Cyprinodontiformes. I investigated some mechanisms of sexual selection acting on body size in the goodeid fish Xenotoca eiseni. Both males and females strongly prefer mates of their own size. Comparison of mating activities in pairs with various degrees of size difference between males and females showed that matched pairs copulated more successfully. Similar mate preference in the two sexes thus appears to be the consequence of the primitive method of internal fertilization that requires the partners to be exactly synchronized during sperm transfer. Competition for access to a female was intense and body size determined the hierarchy in a small group. However, unless the size of the female was close to that of the dominant male, assortative mate preferences prevailed and the large-male advantage in competition was offset. Reduced size dimorphism in X. eiseni and in other goodeids may be explained by constraints on the action of sexual selection imposed by the need for effective fertilization.Copyright 1997 The Association for the Study of Animal BehaviourCopyright 1997The Association for the Study of Animal Behaviour.
Journal Article↗
Phylogenetic utility of the tyrosine kinase gene X-src for assessing relationships among representative cichlid fishes.
The nuclear gene X-src is a member of the tyrosine-kinase class of proto-oncogenes whose normal product is localized within the cytoplasm of the cell. The X-src gene has been used in only a few phylogenetic studies, each focusing on systematics of killifishes (Cyprinodontiformes). The present study is an attempt to examine the phylogenetic utility of X-src for uncovering relationships of representative cichlid fishes, especially the cichlids of Middle America. The family Cichlidae is a species-rich group of tropical freshwater fish made up of more than 1000 species which show a Gondwanan pattern of distribution. Cichlid fish have been the focus of numerous studies ranging from behavioral to biogeographical to systematic in nature. Particular emphasis has focused on the cichlids of the African Great Lakes and the explosive adaptive radiation of this group. However, Neotropical cichlids have received considerably less attention than their African counterparts. Our findings regarding the utility of X-src concur with those of previous phylogenetic analyses showing the exons of X-src to be highly conserved and useful mostly for revealing deep relationships among taxa. Like previous X-src studies, we also found the intron sequences of the gene to be variable in length and difficult to align across distantly related taxa but they provided useful information for resolving relationships among more closely related taxa. The X-src phylogeny supports the monophyly of Neotropical cichlids and cichlasomines groups A (=heroines) + B (=cichlasomines). A highly resolved tree is obtained within the heroines but little support is evident for most nodes based on the low number of unambiguous substitutions. The X-src gene is likely to be quite useful for resolving deep phylogenetic relationships such as those among major groups of actinopterygian fishes.
Animals↗
Identification of major histocompatibility complex genes in the guppy, Poecilia reticulata.
The guppy, Poecilia reticulata, a teleostean fish of the order Cyprinodontiformes, has been used extensively in studies of host-parasite interactions, courtship behavior, and mating preference, as well as in ecological and evolutionary genetics. A related species was among the first poikilotherm vertebrates to be used in the study of histocompatibility genes. All these studies could benefit from the identification and characterization of the guppy major histocompatibility complex (Mhc) genes. Here, both class I and class II genes of the guppy are described. The number of expressed loci, as determined by representation of clones in a cDNA library, sequencing, and Southern blot analysis, may be low in both Mhc classes: combined evidence suggests that there may be one expressed class II locus only and one or two expressed class I loci. The variability of aquaristic guppy stocks is very low: only three and two genes have been detected at the class I and class II loci, respectively, in the stocks examined. This genetic paucity is most likely the consequence of breeding practices employed by aquarists and commercial establishments. Limited sampling of wild guppy populations revealed extensive Mhc polymorphism at loci of both classes in nature. Comparison of guppy Mhc sequences with those of other vertebrates has revealed the existence of a set of insertions/deletions which can be used as characters in cladistic analysis to infer phylogenetic relationships among vertebrate taxa and the Mhc genes themselves. These indels are particularly frequent in the regions coding for the loops of alpha 1 and alpha 2 domains of class I proteins.
Amino Acid Sequence↗
Nonlinkage of major histocompatibility complex class I and class II loci in bony fishes.
In tetrapods, the functional (classical) class I and class II B loci of the major histocompatibility complex (Mhc) are tightly linked in a single chromosomal region. In an earlier study, we demonstrated that in the zebrafish, Danio rerio, order Cypriniformes, the two classes are present on different chromosomes. Here, we show that the situation is similar in the stickleback, Gasterosteus aculeatus, order Gasterosteiformes, the common guppy, Poecilia reticulata, order Cyprinodontiformes, and the cichlid fish Oreochromis niloticus, order Perciformes. These data, together with unpublished results from other laboratories suggest that in all Euteleostei, the classical class I and class II B loci are in separate linkage groups, and that in at least some of these taxa, the class II loci are in two different groups. Since Euteleostei are at least as numerous as tetrapods, in approximately one-half of jawed vertebrates, the class I and class II regions are not linked.
Animals↗
Identification of immunoreactive FSH and LH cells in the cichlid fish Cichlasoma dimerus during the ontogeny and sexual differentiation.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) expressing cells were detected in pituitary, brain and ovary of the Perciform cichlid fish Cichlasoma dimerus. This detection was carried out by immunohistochemistry (IHC) and Western blot techniques using antisera of the Cyprinodontiform Fundulus heteroclitus raised against the conservative region of the teleost betaFSH and the betaLH subunits. The estimated molecular weights were 24 kDa for LH and 19 and 15 kDa for FSH. In the adult pituitary, both cell types were distributed along mid and ventral zones of the proximal pars distalis (PPD, mid-immunoreactive cells), and along the ventral and dorsal external border of the pars intermedia (PI, high-immunoreactive cells). Double IHC showed that FSH and LH are mainly expressed in different pituitary cells. FSH cells were detected in the pituitary around day 21 after hatching (ah) (prior to sex differentiation), while LH cells were detected by day 60 ah (during the sexual differentiation period). A correlation between gonadal sex differentiation and FSH was demonstrated in a 15 days organ culture system. FSH and LH neurons were localized in the nucleus lateralis tuberis and their fibers project through the ventral hypothalamus, preoptic area and neurohypophysis. FSH neurons differentiated on day 21 ah, while LH neurons appeared on day 15 ah. In the ovary, the immunoreactivity for both FSH and LH was restricted to the cytoplasm of previtellogenic and early vitellogenic oocytes.
Age Factors↗