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13 recordsLinked to original sources
PubMed2000

Sonic/vocal motor pathways in squirrelfish (Teleostei, Holocentridae).

Similar to many teleost fish, squirrelfish (family Holocentridae) produce vocalizations by the contraction of muscles that lead to vibration of the swimbladder. We used biotinylated compounds to identify the position and extent of vocal motor neurons in comparison to additional motor neuron groups, namely those of red and white dorsal epaxial muscle and opercular muscle that are located adjacent to or near the sonic muscle. The sonic motor nucleus (SMN) was located in the caudal medulla and rostral spinal cord in a ventrolateral position with dendrites extending dorsally in a dense bundle along the lateral edge of the medulla and axons exiting via ventral occipital nerve roots. Transneuronal transport of biocytin identified premotor neurons within the SMN and in the medially adjacent reticular formation that projected to the contralateral SMN and more rostrally to the octavolateralis efferent nucleus and nucleus praeeminentialis, suggesting interactions between vocal and octavolateralis systems as seen in other teleosts. Motor neurons innervating the red and white dorsal muscle formed a loose aggregate in the dorsal motor column, adjacent to the medial longitudinal fasciculus, sending fibers bilaterally throughout the spinal cord with axons exiting via ventral spinal nerve roots. Opercular motor neurons were located within the facial motor nucleus. The anatomical characteristics of the SMN of squirrelfish, a representative member of the order Beryciformes, are similar to those of representative members of the closely related order Scorpaeniformes, but diverge from the SMN of more distantly related orders of paracanthopterygiian and ostariophysan teleosts. These results therefore suggest a possible homology among the SMNs of acanthopterygiian fishes.

Animals↗
PubMed1984

Visual receptive thalamopetal neurons in the optic tectum of teleosts (Holocentridae).

Tectal neurons previously known to receive retinofugal input were herein shown to project to the nucleus prethalamicus. Following HRP injections into the nucleus prethalamicus, pyriform neurons in the stratum periventriculare and stratum album centrale, and fusiform neurons in the stratum griseum centrale, were retrogradely labeled. Because the labeled types of neurons have been characterized as the main visual receptive neurons of the optic tectum, and because the nucleus prethalamicus of teleosts projects to the telencephalon, this nucleus can now be considered homologous to the nucleus rotundus of reptiles and birds and to the nucleus lateralis posterior-pulvinar complex of mammals, that is, it provides a relay for retinotectal visual input to the telencephalon. Orthogradely labeled terminals as well as retrogradely labeled neurons were also found in the dorsal area of the telencephalon. The tecto-prethalamotelencephalic projections are only ipsilateral.

Animals↗
PubMed1982

An indirect telencephalo-cerebellar pathway and its relay nucleus in teleosts.

In order to clarify telencephalo-cerebellar connections in teleosts, horseradish peroxidase (HRP) was injected into the telencephalon and the corpus cerebelli of 6 species which belong to Cyprinidae, Holocentridae, Scorpaenidae and Balistidae. In fishes belonging to Holocentridae, Scorpaenidae, and Balistidae, some fibers of the telencephalo-tectal tract were observed to terminate ipsilaterally in a longitudinal nucleus, which is located dorsolaterally to the posterior commissure, while the remaining fibers terminated in the tectum. Because the nucleus has not been identified as an independent cell-group or nucleus in previous papers, it was named the nucleus paracommissuralis in the present study. HRP injections into the ipsilateral side of the corpus cerebelli resulted in labeled cells in the nucleus paracommissuralis. Fibers from the nucleus pass through the tractus mesencephalo-cerebellaris anterior. Cytoarchitecture of the nucleus paracommissuralis was studied by means of the Bodian, Nissl and Golgi-Cox methods. The telencephalo-cerebellar fiber system could not be identified in cyprinoid species. Other orthograde- and retrograde-labeled areas were also reported following telencephalic and cerebellar injections with respect to the species difference.

Animals↗
PubMed1982

The brain of Photoblepharon palpebratus steinitzi (Pisces, Teleostei, Anomalopidae).

The external morphology of the brain of Photoblepharon palpebratus steinitzi is typically teleostean in character, and recalls that of the brain of Holocentrus, described by Meader (1934). The encephalization index is very high and near those of Holocentridae, which belong to the same order Beryciformes. The brain organization, studied from the relative volumes of different brain parts, is near that of Holocentridae and Labridae and shows that microsomy (small olfactory bulbs) and the great extension of the cerebellum, visible in external morphology, are good criteria of the peculiarities of the brain of Photoblepharon, which shows no apparent structure in connexion with the light organ.

Animals↗
PubMed2026

Insights Into the Structural Features, Codon Usage Patterns, and Phylogenetic Analysis in Neoniphon argenteus (Teleostei: Holocentriformes) Based on Complete Mitochondrial Genome.

Neoniphon argenteus, a widely distributed nocturnal coral reef fish in the family Holocentridae, plays an important role in maintaining coral reef ecosystem health, yet its phylogenetic position remains poorly resolved. To bridge this gap, we sequenced and analyzed the complete mitochondrial genome of a specimen from the South China Sea to characterize its structural features, codon usage patterns, and phylogenetic relationships. The 16,569 bp mitogenome (GenBank: PP190474.1) encodes 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and two non-coding regions, exhibiting a distinct A + T bias. All tRNAs fold into typical cloverleaf secondary structures except tRNA-Ser (AGN), which lacks the dihydrouridine (DHU) arm. The control region contains palindromic motifs (TACAT/ATGTA) capable of forming hairpin structures and five conserved sequence blocks, whereas the OL region harbors a conserved 5'-GCCGG-3' motif. RSCU analysis revealed 31 frequently used codons (RSCU > 1) with a pronounced preference for A/C-ending codons. The ΔRSCU method identified 10 candidate optimal codons (GCA, CAA, GAA, GGA, AUU, CUA, CCA, CGA, ACA, and GUC). Selection pressure analysis using EasyCodeML and site-specific models indicated that all PCGs are predominantly under purifying selection, with no significant evidence of pervasive positive selection. ND6 exhibited elevated pairwise Ka/Ks ratios (mean = 1.209 ± 0.047), consistent with reduced selective constraint rather than adaptive evolution. Phylogenetic analysis of 19 Holocentriformes species using maximum likelihood and Bayesian inference with partitioned models based on 13 PCGs and two rRNA genes (12S and 16S) assigned all taxa to two well-supported subfamilies (Holocentrinae and Myripristinae). Within Holocentrinae, Neoniphon species form a monophyletic clade nested within a paraphyletic Sargocentron, suggesting that the genus Sargocentron as currently defined is not monophyletic. This study provides useful baseline molecular data for further exploration of the evolutionary history of N. argenteus and other members of Holocentriformes.

Holocentridae↗
PubMed2000

Phylogenetic investigations of the stephanoberyciformes and beryciformes, particularly whalefishes (Euteleostei: Cetomimidae), based on partial 12S rDNA and 16S rDNA sequences.

DNA data were collected from a number of acanthomorph fishes for 12S rDNA (30 sequences) and 16S rDNA (39 sequences) to investigate the phylogenetic relationships of genera within Cetomimidae (whalefishes) and of this family within the Stephanoberyciformes/Beryciformes assemblage. The Cetomimidae are apparently monophyletic. Within the family, species of Gyrinomimus and Cetomimus form a clade but the former genus is paraphyletic with respect to the latter. Cetostoma is sister to Ditropichthys rather than to Gyrinomimus plus Cetomimus as suggested by morphological analyses. Rondeletiidae + Cetomimidae + Barbourisiidae are shown, as expected from morphological analyses, as a monophyletic group in the 12S rDNA analyses, but not in the 16S rDNA or combined analyses, although the shortest trees showing the group require only one extra step in each case. These three families plus Melamphaidae (our sample of Stephanoberyciformes) are not shown as a group in any analysis, with Melamphaidae being sister to Berycidae in the 16S and combined analyses, but dispersed in the 12S analyses. Maximum-parsimony trees without imposed constraints are notably shorter than trees constrained to show ordinal groupings or either of the two main current hypotheses of Stephanoberyciformes/Beryciformes relationships. The length difference is highly significant for most comparisons using either 12S or 16S rDNA sets or their combination, and significant or nearly so for all comparisons. In particular, the Beryciformes is unlikely to be monophyletic. The Holocentridae are included, with high bootstrap and Bremer support, in a clade of non-beryciforms comprising the Gempylidae, Zeidae, and Atheriniformes (the only higher acanthomorphs sampled) and not with other Beryciform families. In these data, the Berycidae are the sister to the Melamphaidae, a stephanoberyciform family.

Animals↗
PubMed1988

Pigment migration in fish erythrophores is controlled by alpha 2-adrenoceptors.

1. The aggregation of erythrosomes within erythrophores of the squirrel fish (Myripristis occidentalis; belonging to the family Holocentridae) was, on pharmacological grounds, shown to be mediated by alpha 2-adrenoceptors. 2. The erythrophores were shown to be controlled by adrenergic nerves activating the alpha 2-adrenoceptors. 3. The erythrophores themselves were found to possess a K+-sensitive mechanism of aggregation. 4. Some similarities and differences of the alpha 2-adrenoceptor-mediated chromatosome aggregation in melanophores and erythrophores are also discussed.

Animals↗
PubMed2003

Physiology and endocrinology of zinc accumulation during the female squirrelfish reproductive cycle.

Females of the squirrelfish family (Holocentridae) accumulate higher levels of hepatic zinc than any other studied animal. This accumulation is accompanied by high expression of the zinc-binding protein, metallothionein (MT), and is strongly correlated to the onset of sexual maturity. In an attempt to further characterize the timeframe of this accumulation, and to possibly discern any potential mediators, we examined the physiology and endocrinology of the yearly reproductive cycle of mature female squirrelfish. There are two separate reproductive events during the year in December-January and again in March-April, as evidenced by peaks in ovarian growth, VTG production, steroid levels, zinc accumulation and redistribution. Increased hepatic zinc seems to be preceded by a necessary increase in MT, but this was not clearly correlated to plasma 17beta-estradiol, testosterone, or progesterone levels. The plasma zinc protein vitellogenin (VTG) is one, but probably not the predominant, vehicle for the transport of hepatic zinc to the ovary.

Animals↗
PubMed2001

Effects of 17 beta-estradiol on levels and distribution of metallothionein and zinc in squirrelfish.

Females of the squirrelfish family (Holocentridae) accumulate higher levels of zinc in the liver than any other known animal. This zinc accumulation is made possible by high expression of the zinc-binding protein, metallothionein (MT). In the present study, the squirrelfish (Holocentrus ascensionis) MT cDNA was cloned and sequenced. The deduced amino acid sequence was very similar to other teleost MT. The role of estrogens on zinc metabolism was investigated by injecting male and immature female squirrelfish with 17 beta-estradiol (E(2)). E(2) treatment triggered transient increases in plasma zinc and vitellogenin (VTG) levels, and both of these variables showed very similar time courses. These results suggest that E(2) is responsible for the large hepatoovarian translocation of zinc observed in female squirrelfish and that VTG might be a vehicle for zinc. E(2) did not directly alter the levels of zinc or MT mRNA in the liver. However, the hepatic MT protein concentration increased differentially in the nuclear fraction. Thus E(2) is probably responsible for the association of MT with the nuclear fraction previously observed in untreated mature female squirrelfish.

Amino Acid Sequence↗
PubMed1996

The physiology of massive zinc accumulation in the liver of female squirrelfish and its relationship to reproduction.

It is well known that zinc is an essential micronutrient and, as a rule, organisms keep relatively constant low levels of zinc to maintain cellular functions. The squirrelfish family (Holocentridae) is the only known exception from this rule. Squirrelfish accumulate very high concentrations of zinc in the liver. In the present study, we demonstrate that, while female squirrelfish store large amounts of zinc in the liver and ovaries, the males show zinc levels that are typical for vertebrates. The zinc content of the diet is the same in males and females, and zinc is not lost from the liver during starvation. Thus, the difference between genders in zinc storage is not dependent upon the diet. Rather, there are at least two processes that contribute to the accumulation in females. First, females possess high levels of two major zinc-binding proteins: metallothionein (MT) and a novel female-specific zinc-binding protein (FZnBP). In females, but not in males, almost all MT is present in the hepatocyte nucleus. FZnBP is exclusively found in the hepatocyte cytosol of females. Second, hepatocytes of female squirrelfish have a high capacity to transport zinc across the plasma membrane. In addition to the liver, only the gonads of females showed unusually high concentrations of zinc. Administration of exogenous oestrogen to females decreases the hepatic zinc concentration while there is a matching increase in the zinc content of the ovaries. Thus, oestrogen may trigger a redistribution of zinc from liver to ovaries. Together, our findings suggest that female squirrelfish may be uniquely adapted to detoxify zinc and to utilize it as a macronutrient for processes related to reproduction.

Animals↗
PubMed2002

Sexual maturation and reproductive zinc physiology in the female squirrelfish.

Female squirrelfish (Holocentridae) accumulate higher concentrations of hepatic zinc than any other known organism. In the liver cells, up to 70% of zinc is bound to metallothionein (MT), which is expressed at extremely high levels. These attributes are related to reproduction in ways that have not been fully characterized. In the present study, we have demonstrated that female-specific zinc and MT accumulation and distribution are strongly correlated to the onset of sexual maturity in Holocentrus adsenscionis. Sexual maturation not only resulted in increased concentrations of zinc in the liver and plasma, but also increased levels of hepatic MT mRNA. Furthermore, mature female squirrelfish exhibited greater proportions of MT protein in the nuclear liver cell fractions. To characterize the physiology further, we have examined the influence of the female sex hormone 17 beta-estradiol (E(2)). E(2) was not sufficient to elicit an increase in hepatic zinc concentrations or MT mRNA levels. E(2) administration did, however, result in increased levels of MT in the nuclear fraction as well as overall hepatic MT protein. E(2) also increased concentrations of zinc in the plasma. The changes in zinc concentration in the bloodstream followed the same time course as vitellogenin (VTG) transport from the liver. However, the high ratio of molar concentrations of zinc to VTG in the bloodstream suggest that VTG may not be the primary vehicle for hepato-ovarian zinc transport in squirrelfish.

Animals↗
PubMed1998

Cucullanin nematodes from coral reef fishes of French Polynesia, with a description of Cucullanus faliexae n. sp. (Nematoda: Chitwoodchabaudiidae).

Cucullanus faliexae n. sp. is described from the moray eel Gymnothorax javanicus (Muraenidae) collected in Rangiroa (Tuamotu Islands, French Polynesia) in the South Pacific and is reported from the same host collected in Moorea (Society Islands, French Polynesia). This nematode is distinguished from its congeners by its protrubant anus and the presence of a single pair of subdorsal postanal papillae. Cucullanus faliexae resembles C. laurotravassosi from which it is distinguished by the farther anterior position of the first pair of male caudal preanal papillae and by the greater size of its spicules. Cucullanus bourdini Petter and Le Bel, 1992 is reported from the coral reef fishes Balistapus undulatus (Balistidae), Lutjanus gibbus (Lutjanidae), and Myripristis kuntee (Holocentridae) from French Polynesia. Additionally, Cucullanus sp. is reported from the coral reef fish Sufflamen bursa (Balistidae) in Moorea and Rangiroa. Given that C. faliexae and C. bourdini have been found in widely disparate locations between which their definitive hosts cannot migrate, it would seem likely that the life cycles of these worms include an intermediate or transport host that has a greater capability for dispersal.

Animals↗