Cottoid Fishes Research Articles

Partial formation of sperm dimorphism from spermatocytes of the cottoid fish, Hemilepidotus gilberti in cell culture

Polymorphism of sperm is considered to be significant for the reproductive strategy in some animal species. The phenomenon is thought to occur in the species-specific stage of spermatogenesis, but how the identical germ cells are differentiated towards polymorphic sperm remains unknown. We here performed a germ cell culture in the cottoid fish, Hemilepidotus gilberti, whose sperm exhibit dimorphism with fertilizable eusperm and unfertilizable parasperm. In the culture, germ cells, which were obtained with an identical morphology, a spherical shape of 5-7 microm in diameter, differentiated into smaller spherical cells with a single nucleus, a moving flagellum and localized mitochondria. In addition, large retroflex-shaped cells with two elongated nuclei were also observed in the cell culture. Germ cells that had each morphological feature were histologically also observed in some cysts of the spermatogenetic testis, suggesting that the former type of cell corresponded to developing eusperm and the latter corresponded to developing parasperm. When BrdU was incorporated into germ cells in the culture, it was detected in both cells with eusperm-like and those with parasperm-like morphologies. These findings suggest that DNA-duplicating spermatocytes are potent to autonomously progress a part of spermatogenesis to form dimorphic sperm.

Parasperm: morphological and functional studies on nonfertile sperm

Sperm polymorphism, a phenomenon in which more than one type of sperm is produced within a species, occurs widely in animals from invertebrates to vertebrates. Sperm in this phenomenon can be categorized into fertile sperm and nonfertile sperm on the basis of fertilization ability. Nonfertile sperm can be further classified into parasperm and aberrant deformed sperm. Parasperm are sperm produced through a constant developmental process along with normal fertile eusperm, and they are readily distinguished from deformed sperm, which are irregularly crippled by unpredictable errors at certain stages during spermatogenesis. Sperm identified as parasperm occur widely in invertebrates but are presently quite limited in vertebrates. This may be the result of the deficiency both of studies on parasperm and of clear criteria to identify parasperm in vertebrates. Some vertebrates show unique spermatogenesis, such as symplastic spermatid and semicystic spermatogenesis. Thus, parasperm must be identified by comparing cells in each cyst and in semen, because irregularly shaped cells in the seminal duct could be either parasperm or normal spermatids. Although parasperm are identified by clear criteria in vertebrates, only in cottoid fishes to date, it is possible for parasperm to be discovered in other vertebrates. Recently, roles related to sperm competition have been reported in several species (e.g., the marine cottoid fish Hemilepidotus gilberti), and, with some of them, parasperm production is influenced by an intraspecific factor such as a sex ratio or the density of a population. Sperm competition is one of the important candidates for influencing evolution of parasperm functions, but not all parasperm seem to have a relation to sperm competition. Parasperm function may relate to the ecological conditions of each species that produces parasperm. Studies on parasperm function will be advanced by an ecological approach concerning male fertilization success as well as cytological investigation for parasperm.

Evolutionary changes of eyes of some bottom species of Baikalian cottoid fishes

The cottoids – Batrachocottus multiradiatus, Asprocottus herzensteini, Cyphocottus megalops, Limnocottus bergianus and Limnocottus pallidus are bottom eurybathic species in Lake Baikal, which reside under similar light conditions. All have mixed rod–cone retinas. However, B. multiradiatus and C. megalops have more developed cone vision, whereas A. herzensteini, L. bergianus and L. pallidus have scotopic vision as predominant. Differences in retinal structure of these species, living under almost the same conditions of luminosity, suggest they colonized deep water at different periods in the long history of Baikal.

Ultrastructural observations of euspermatozoa and paraspermatozoa in a copulatory cottoid fish Blepsias cirrhosus

Euspermatozoa and paraspermatozoa of a copulatory (internal insemination with external sperm transfer) cottoid fish Blepsias cirrhosus were observed ultrastructurally. Euspermatozoa of B. cirrhosus consisted of an acrosome‐less, thin, disk‐like sperm head (1·6‐2·0 μm in length and 1·3‐1·6 μm in width), a long middle piece, and a long flagellum (c. 30 μm). Aberrant spermatids, which were rich in cytoplasm and possessed two nuclei, occurred in testicular lobules. They were also observed in semen and were round (5·0‐5·3 μm in diameter) and biflagellate, suggesting that they are released along with euspermatozoa at ejaculation. The nuclei of aberrant spermatids developed into masses of highly electron‐dense globules. Judging from their form, nuclear condition, and connection with normal spermatids by intercellular bridges during spermiogenesis, aberrant spermatids of B. cirrhosus are considered hyperpyrenic paraspermatozoa formed by incomplete cytokinesis at the second meiotic division.

Endemic diversification of the monophyletic cottoid fish species flock in Lake Baikal explored with mtDNA sequencing

In the ancient Lake Baikal in East Siberia, cottoid fishes have diversified into an endemic flock of 33 species. From an ancestral shallow-water, benthic life-style, Baikalian cottoids have shifted to deep-water life in environments even below 1500 m, and also colonized the pelagic habitat. We examined phylogenetic relationships among 22 Baikalian and 10 extra-Baikalian cottoid taxa using a total of 2822 bp of mitochondrial DNA sequence, from complete sequences of ATPase 8 and 6 and cytochrome b genes and the control region. Unlike in earlier studies, we found strong support for a monophyly of the whole endemic Baikalian cottoid diversity. The Baikalian clade, currently assigned to three families and 12 genera, appears to be nested within the Holarctic freshwater genus Cottus. In the molecular phylogeny, all but one of the current Baikalian genera formed well-supported monophyletic groups. However, the topology was inconsistent with the present morphology-based familial subdivision; particularly in positioning the genus Batrachocottus of Cottidae within Abyssocottidae. The branching order of the Baikalian genera could not be resolved completely, however; short basal branches indicate rapid diversification early in the history of the species flock. Using synonymous divergence rates from other fish species for calibration, the diversification of the Baikalian cottoids seems to have started in the Pliocene or early Pleistocene.

Spectral tuning and evolution of short wave-sensitive cone pigments in cottoid fish from Lake Baikal.

The cottoid fishes of Lake Baikal in eastern Siberia provide a unique opportunity to study the evolution of visual pigments in a group of closely related species exposed to different photic environments. Members of this species flock are adapted to different depth habitats down to >1000 m, and both the rod and cone visual pigments display short wave shifts as depth increases. The blue-sensitive cone pigments of the SWS2 class cluster into two species groups with lambda(max) values of 450 and 430 nm, with the pigment in Cottus gobio, a cottoid fish native to Britain, forming a third group with a lambda(max) of 467 nm. The sequences of the SWS2 opsin gene from C. gobio and from two representatives of the 450 and 430 nm Baikal groups are presented. Approximately 6 nm of the spectral difference between C. gobio and the 450 nm Baikal group can be ascribed to the presence of a porphyropsin/rhodopin mixture in C. gobio. Subsequent analysis of amino acid substitutions by site-directed mutagenesis demonstrates that the remainder of the shift from 461 to 450 nm arises from a Thr269Ala substitution and the shift from 450 to 430 nm at least partly from Thr118Ala and Thr118Gly substitutions. The underlying adaptive significance of these substitutions in terms of spectral tuning and signal-to-noise ratio is discussed.

Lipids and fatty acids of two pelagic cottoid fishes ( Comephorus spp.) endemic to Lake Baikal

Matured females of two Lake Baikal endemic fish species, Comephorus baicalensis and Comephorus dybowski, have been investigated for lipid of the whole body and specific tissues (liver, muscles, ovaries), phospholipid classes and fatty acids of neutral and polar lipids. Total lipid in the body (38.9% fresh weight), liver (23.5%) and muscles (14.5%) of C. baicalensis were greater than those of C. dybowski (4.7, 8.7 and 2.6%, respectively); only their ovaries were similar (5.3 and 5.6% lipid, respectively). In both species, phosphatidylcholine and phosphatidylethanolamine were the major phospholipids, ranging from 60.7 to 75.1% of total phospholipid and 14.5–25.7%, respectively. In most cases, monounsaturated fatty acids (MUFA) were the major fatty acid group in C. baicalensis, whereas polyunsaturated fatty acids (PUFA) were the major group in C. dybowski. The MUFA 18:1(n-9) prevailed over other fatty acids in C. baicalensis and varied from 19% in polar lipids of muscles to 56.1% in neutral lipids of muscles. In polar lipid of C. dybowski, the PUFA 22:6(n-3) prevailed over other fatty acids in muscles and ovaries, while 16:0 dominated polar liver lipids and neutral lipids of all tissues. Other major fatty acids included 16:1(n-7), 18:1(n-7), and 20:5(n-3). Values of the (n-3)/(n-6) fatty acid ratio for neutral lipids of C. baicalensis (0.5–0.9) are well below the range of values characteristic either for marine or freshwater fish, while these values for polar lipids (1.6–1.8) are in the range typical of freshwater fish. Neutral lipid fatty acid ratios in C. dybowski (2.5–3.1) allow it to be assigned to freshwater fish, but polar lipids (2.8–3.7) leave it intermediary between freshwater and marine fish.

Stable isotope analyses of the pelagic food web in Lake Baikal

Stable isotope ratios of various organisms were analyzed to elucidate food web structure in the pelagic zone of Lake Baikal. The pelagic food web of Lake Baikal is simple and consists of five major ecological groups: phytoplankton (Aulacoseira baicalensis), mesozooplankton (Epischura baicalensis), macrozooplankton amphipod (Macrohectopus branickii), fish (Coregonus autumnalis migratorius and four species of cottoid fishes), and seal (Phoca sibirica). Because of the low diversity and consequently small number of possible diets for each species, we were able to quantitatively estimate the diet composition of each animal with stable isotopes. Our carbon isotope data indicated that pelagic phytoplankton are the primary carbon source of the pelagic food web because δ13C levels of animals were close to those of pelagic phytoplankton. The δ15N levels of animals showed a clear trend of stepwise enrichment with trophic level according to the following equation: δ15N (‰) = 3.3 (Trophic Level – 1) – 3.8. In addition to interspecific food web analysis, important pelagic animals, such as M. branickii, two species of pelagic sculpin, C. autumnalis migratorius, and P. sibirica, were also examined, with emphasis on ontogenic diet changes. δ15N levels of M. branickii and sculpins increased with body length, suggesting a change in feeding habits during growth. We demonstrate that carbon and nitrogen stable isotopes can be successfully applied to elucidate trophic relationships and conclude that the pelagic food web of Lake Baikal has an ideal, isotopically ordered structure.

Molecular Evolution of the Cottoid Fish Endemic to Lake Baikal Deduced from Nuclear DNA Evidence

Lake Baikal in Eastern Siberia contains a remarkable flock of 29 species of teleost fishes of the suborder Cottoidei (sculpins, bullheads) that are endemic to the lake and its associated rivers and occupy all depth habitats down to over 1500 m. The species are divided into three families, the Cottidae with 7 species, the Abyssocottidae with 20 species, and the Comephoridae with 2 species. Nucleotide sequences of the rod opsin gene from 12 of these species, plus a non-Baikal marine species, have been used to examine the evolutionary relations and the divergence time of the flock. Phylogenetic trees, generated by neighbor-joining and maximum parsimony, indicate that the unique Comephoridae family with its viviparity and unusual appearance is closely related to the Cottidae and Abyssocottidae, whereas the genusCottocomephorus,at present placed in the Cottidae, was the first to diverge from the ancestral species and forms a separate lineage. The major adaptation to deep water would appear to be of relatively recent origin, and there is evidence that the ancestral species occupied a shallow-water marine or brackish habitat. Estimates of antiquity obtained from synonymous substitutions place the origin of the species flock at around 4.9 million years ago.

Seasonal cycles in total chemical composition of two Lake Baikal benthic‐pelagic sculpins (Cottocomephorus, Cottoidei)

Annual cycles in chemical composition of the body, liver, gonads, red and white muscles were determined for two medium fat sculpins, Cottocomephorus grewingki and C. inermis, endemic to Lake Baikal. Their total lipid content ranged from 3 to 9% during the year. The content of defatted dry substance was 14–17%, similar to the protein content of the other Baikalian cottoid fishes. The prespawning period was characterized by a positive lipid and protein balance in both species. In C. grewingki the liver performed largely a metabolic function, whereas in C. inermis it served also as a storage site for lipid reserves. During spawning, total body lipids of females of both species showed a two‐ to threefold decrease. Males of C. grewingki guarding nests deplete greatly their total body lipids, which decrease seven‐ to ninefold by the time of larval hatching in comparison with the prespawning period, and constitute 1–2%. After spawning, lipid reserves of C. grewingki were quickly restored to the initial level (from about 3 to 9%) and maintained during the long sexual maturation period. In C. inermis total body lipids increased only twofold in comparison to those observed during the spawning period.

Comparative character of the deep‐water and inshore cottoid fishes endemic to Lake Baikal

Lake Baikal's 29 endemic species of cottoid fishes form three groups: shallow‐water species in depths to 350 m; eurybathic species from 50 to 1300 m; and abyssal species from 400 to 1600 m. These groups differ in their abilities to withstand high hydrostatic pressure. As in marine deep‐water fishes, abyssal cottoids in Baikal have few or no cones in the retina, and some have tubular eyes. Their seismosensory systems predominate, based chiefly on free neuromasts. The proportion of species with canal systems decreases with depth. Diversity of the predominantly gammarid foods also decreases from 45 species in shallow water to five species in deep water, and the lateral line system plays the dominant role in food detection at all depths. Two abyssal cottoids have become secondary pelagic, achieving close to neutral buoyancy through high lipid levels and reduced skeletal mineralization. These forms take advantage of the abundant pelagic planktonic amphipod populations. The adaptations of abyssal forms parallel those seen in deep‐water marine fishes.

Spectral tuning and molecular evolution of rod visual pigments in the species flock of cottoid fish in Lake Baikal

Lake Baikal in Eastern Siberia is the deepest and one of the largest and most ancient lakes in the world. However, even in the deepest regions, oxygenation levels do not fall below 75–80% of the surface levels. This has enabled a remarkable flock of largely endemic teleost fish of the sub-order Cottoidei to colonize all depth habitats. We have previously shown that species that occupy progressively deeper habitats show a blue shift in the peak wavelength of absorbance ( λ max ) of both their rod and cone visual pigments; for the rod pigments, a number of stepwise shifts occur from about 516 nm in littoral species to about 484 nm in abyssal species. By sequencing the rod opsin gene from 11 species of Baikal cottoids that include representatives from all depth habitats, we have been able to identity four amino acid substitutions that would account for these shifts. The effect of each substitution on λ max is approximately additive and each corresponds to a particular lineage of evolution.

Spectral tuning of visual pigments: the rhodopsins of cottoid fish from Lake Baikal

Brain responses to repeated sensory stimuli are typically buried in the more prominent background activity, and thus analysis of these responses on a single-trial basis would require advanced procedures to estimate the brain activity related only to the experimental task. Recently, we have proposed a new iterative independent component analysis (iICA) approach to estimate single-trial responses. In this paper, we compare the performance of iICA at estimating single-trial responses with ensemble averaging and wavelet transform (WT) denoising.We analyzed simulated evoked potentials (EPs) and actual recordings of the auditory N100 component from 33 normal subjects, and the performance of each method was quantified in terms of the average root-mean-square error and average correlation before and after processing.We found that WT gave a smoother overall average EP, while iICA could isolate the N100 component out of the entire EP waveform. With simulated data, iICA provided significantly better estimates of the true EP compared to plain averaging (p < 0.01) and WT (p < 0.01). With actual data, iICA showed clear responses in single trials, in all subjects. Additionally, the corresponding average EPs had a sharper N100–P200 complex, with flatter preceding and following regions, resulting in an enhanced N100 component.The iICA procedure can provide clear responses in each single trial, and the resulting average N100 component is significantly improved compared to plain averaging and wavelet denoising.The proposed technique may have a significant impact as a clinical tool in the analysis of single-trial responses.

Visual pigments and the photic environment: The cottoid fish of Lake Baikal

The endemic cottoid fish of Lake Baikal in Eastern Siberia offer a singular opportunity for examining within a number of closely related species, the relationships of visual pigments, photoreceptor complements and depth within a deep freshwater environment. The lake, the deepest (1600 m) and one of the largest and most ancient in the world, is unique in that the oxygen levels at the bottom are only reduced to about 80% of the surface levels. We have studied, by light microscopy, microspectrophotometry and visual pigment extraction, the retinas from 17 species of Baikal cottoids that live at different depths within the lake. Generally the retinas contain, in addition to rods, large green-sensitive double cones and small blue-sensitive single cones: surprisingly for freshwater fish, the visual pigments are based on Vitamin A 1 The λ max of both rods and cones are displaced to shorter wavelengths with increasing depth. Surface species have cones with λ max at about 546,525 and 450 nm and rods at 523 nm, deeper living species retain cones, but with λ max shifting towards 500 and 425 nm and with rods at 480 nm, whereas the deepest living fish possess only rods (λ max, 480–500 nm). These data clearly show a correlation between photoreceptor complement, visual pigment λ max, and depth, but question the hypothesis that there is a correlation of pigment (λ max with water colour since, in contrast to oceanic waters, the maximum transmission of Baikal water is between 550 and 600 nm.

The morphology of the lateral line system in 3 species of Pacific cottoid fishes occupying disparate habitats

The superficial neuromasts inLeptocottus armatus (Pacific staghorn sculpin) andOligocottus maculosus (tidepool sculpin) are depressed below the rim of an epidermal collar, whereas the superficial neuromasts inPsychrolutes paradoxus (tadpole sculpin) are surrounded by a pair of hillocks. The lateral line canal system appears identical across these species, whereas the system of superficial neuromasts shows some intraspecific variation. The sand-livingLeptocottus has a more highly developed system of superficial neuromasts thanOligocottus, which lives in a rocky habitat. The present results support the correlation between lateral line system morphology and habitat features previously postulated by Dijkgraaf.

Physiological adaptation of cottoid fishes of lake baikal to abyssal depths

Abstract 1. 1. Pressure tolerance of ten species of shallow water ( 2. 2. The observed family differences reflect not merely acclimation to habitat pressure, but rather suggest a significant degree of genetic determinacy of this characteristic, pointing to a possible role of hydrostatic pressure as a selection factor in the evolution of deep water faunas.

A New Cottoid Fish of the Family Ereuniidae, Marukawichthys pacificus, from the Central North Pacific

A New Cottoid Fish of the Family Ereuniidae, Marukawichthys pacificus, from the Central North Pacific

A Cytotaxonomical Study in Some Freshwater Cottoid Fishes (Cottidae, Pisces)

A Cytotaxonomical Study in Some Freshwater Cottoid Fishes (Cottidae, Pisces)

Intra- and interspecies variability of vertebrate high-pressure neurological syndrome.

ArticleIntra- and interspecies variability of vertebrate high-pressure neurological syndrome.R W Brauer, R W Beaver, C D Hogue 3rd, B Ford, S M Goldman, and R T VentersR W Brauer, R W Beaver, C D Hogue 3rd, B Ford, S M Goldman, and R T VentersPublished Online:01 Dec 1974https://doi.org/10.1152/jappl.1974.37.6.844MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByDivers: Air-Breathing Animals, Including Humans, at High Pressure13 July 2021Adaptation to High Pressure in the Laboratory13 July 2021Effects of High Pressure on the Activity of Ordinary Animals, Including Humans, and on the Function of Their Excitable Cells and Ion Channels13 July 2021Does hydrostatic pressure influence lumpfish ( Cyclopterus lumpus ) heart rate and its response to environmental challenges?22 July 2021 | Conservation Physiology, Vol. 9, No. 1Study on arbor leaf and ring as a potential biological indicator for atmospheric polybrominated diphenyl ethers (PBDEs) distribution at e-wastes recycling sites8 June 2019 | International Journal of Environmental Science and Technology, Vol. 16, No. 12The efficacy of physiological and pharmacological N-methyl-d-aspartate receptor block is greatly reduced under hyperbaric conditionsNeuroscience, Vol. 169, No. 1Differential modulation of cerebellar climbing fiber and parallel fiber synaptic responses at high pressureYoram Etzion*, Amir Mor*, and Yoram Grossman1 February 2009 | Journal of Applied Physiology, Vol. 106, No. 2High pressure modulation of NMDA receptor dependent excitabilityEuropean Journal of Neuroscience, Vol. 25, No. 7Modulation of isolated N -methyl-d-aspartate receptor response under hyperbaric conditionsEuropean Journal of Neuroscience, Vol. 24, No. 127 Pressure Effects on Shallow-Water FishesMixed‐gas Saturation Diving1 January 2011Comparative character of the deep-water and inshore cottoid fishes endemic to Lake BaikalJournal of Fish Biology, Vol. 49, No. saComparison between subjective feelings to alcohol and nitrogen narcosis: A pilot studyAlcohol, Vol. 13, No. 1High-pressure neurological syndrome (HPNS)29 January 2009 | Acta Neurologica Scandinavica, Vol. 90, No. 1FishThe Nervous System: Man and Laboratory MammalsBehavioral Analysis of Rats Exposed to High PressureEffects of high pressure on striatal dopamine release in freely moving rats: A microdialysis studyNeuroscience Letters, Vol. 146, No. 2A new device for behavioral analysis on rats exposed to high pressurePhysiology & Behavior, Vol. 49, No. 2Hyperbaric effects on sensorimotor reactivity studied with acoustic startle in the ratPhysiology & Behavior, Vol. 42, No. 3Effects of hydrostatic pressure on the motor activity of fish from shallow water and 900 m depths; some results of challenger cruise 6B/85Comparative Biochemistry and Physiology Part A: Physiology, Vol. 88, No. 3The effect of pressure on the lateral swimming muscle of the european eel Anguilla anguilla and the deep sea eel Histiobranchus bathybius; results of challenger cruise 6B/85Comparative Biochemistry and Physiology Part A: Physiology, Vol. 88, No. 3Physiological adaptation of cottoid fishes of lake baikal to abyssal depthsComparative Biochemistry and Physiology Part A: Physiology, Vol. 77, No. 4Interactions of γ-aminobutyric acid and noradrenaline in the high pressure neurological syndrome19 July 2012 | British Journal of Pharmacology, Vol. 79, No. 3The pressure tolerance of deep sea amphipods collected at their ambient high pressureComparative Biochemistry and Physiology Part A: Physiology, Vol. 71, No. 2PROCEEDINGS OF THE British Pharmacological Society19 July 2012 | British Journal of Pharmacology, Vol. 74, No. 4Pressure/temperature interactions in relation to development of high pressure convulsions in ectotherm vertebratesComparative Biochemistry and Physiology Part A: Physiology, Vol. 69, No. 4Functional Adaptations of Deep-Sea OrganismsBrain monoamines and the high pressure neurological syndromeNeuropharmacology, Vol. 19, No. 11THE TOLERANCE OF ANIMALS TO PRESSURE More from this issue > Volume 37Issue 6December 1974Pages 844-51 https://doi.org/10.1152/jappl.1974.37.6.844PubMed4215787History Published online 1 December 1974 Published in print 1 December 1974 Metrics

カジカ科魚類の鰭の分類學的意義

カジカ科魚類の鰭の分類學的意義