Scorpaenid Fish Research Articles

Development of a PCR-RFLP method for differential identification of Microcotyle sebastis and Microcotyle caudata isolated from cultured rockfish in Korea.

Microcotylid monogeneans can cause considerable health problems in cultured fish, and several Microcotyle species are reported from scorpaenid fish, an economically important aquaculture target species in Korea. We developed a PCR-RFLP assay targeting the mitochondrial cox1 gene, for discriminating Microcotyle sebastis and M.caudata from cultured Korean rockfish Sebastes schlegelii and dark-banded rockfish S.inermis. AseI enzyme treatment of the PCR products showed that M.sebastis sequence was cleaved while M.caudata was not. A total of 95.2% (118/124) of monogeneans from S.schlegelii were identified as M.sebastis, and 96.2% (126/131) of monogeneans from S.inermis were identified as M.caudata by PCR-RFLP. However, the remaining parasites from each host showed the opposite digestion pattern. Additional analyses of these specimens by targeting the ITS region by PCR-RFLP showed the same results, suggesting that cross-species infection by the parasites may have occurred. In Korea, S.inermis net cages are commonly located nearby S.schlegelii net cages, and this encaged proximity might have provided the opportunity for cross-infection to occur. Further examination of wild host populations and experimental cross-infection will be necessary to explain this phenomenon. The PCR-RFLP method in this study will help investigate the epidemiology and infection dynamics of Microcotyle species in S.inermis.

Parasitological Records of Eight Rockfish Species (Scorpaeniformes: Scorpaenidae) from Pacific Baja California, Mexico

This study reports parasitological records of eight species of marine rockfishes (Sebastes auriculatus, S. chlorostictus, S. umbrosus, S. miniatus, S. atrovirens, S. constellatus, S. serranoides, and Scorpaena guttata) collected from Todos Santos bay and San Quintin coast, Baja California, Mexico. The vermilion rockfish, S. miniatus, showed the highest parasite species richness (two species of monogeneans, two species of digeneans, three species of nematodes and one species of copepods), while the lowest richness was found in S. atrovirens and S. umbrosus (one species of copepod and one species of nematode, respectively). The species S. auriculatus, S. chlorostictus, S. constellatus, S. serranoides, and S. guttata showed a richness of up to four parasite species. Seven of the eight fish species (except S. atrovirens) presented larval stages of nematodes Anisakis sp., Pseudoterranova sp. and Hysterothylacium sp. (prevalences ranging from 8.3 to 100%), which were found in the fish mesentery (guts). The parasite species with the highest prevalence values (>80%) were found in S. miniatus (Anisakis sp.), S. guttata (Anisakis sp. and Hysterothylacium sp.), S. umbrosus (Anisakis sp.), S. auriculatus (Anisakis sp.), and S. constellatus (Anisakis sp.). The most abundant parasite species (>4 ind./host) were recorded in S. guttata (Anisakis sp. and Hysterothylacium sp.), S. umbrosus (Anisakis sp.), S. constellatus (Parabothriocephalus sagitticeps), and S. miniatus (Anisakis sp.). The parasite species with the highest intensity of infection values (>5 ind./host) were found in S. constellatus (P. sagitticeps), followed by S. guttata (Anisakis sp., Hysterothylacium sp.), S. umbrosus (Anisakis sp.), and S. serranoides (Microcotyle sebastis). The present study, in addition to listing the helminths and parasitic copepod species (and providing quantitative data on them) of eight commercially important scorpaenid fish species in the northwestern Mexico, can also serve as a baseline for future parasitological studies on these fish species.

Marine regime shifts impact synchrony of deep‐sea fish growth in the northeast Atlantic

The complexity and spatio–temporal scale of populations’ dynamics influence how populations respond to large‐scale ecological pressures. Detecting and attributing synchrony (i.e. temporally coincident fluctuations in populations’ parameters) is key as synchronous populations can become more vulnerable to stochastic events that can affect the viability of harvest and have profound consequences to community structure. Here, we aimed to estimate the level of synchrony in fish growth within and among species across 1 million km2 and identify the environmental drivers contributing to synchronous population fluctuations. We developed otolith increment‐based growth chronologies for two deep‐sea scorpaenid fishes (Helicolenus dactylopterus and Pontinus kuhlii) from geographically and bathymetrically disjunct populations in the northeast Atlantic (one species in three locations; two species with different depth preferences). We used hierarchical models to partition variation in growth within and between populations attributing it to intrinsic (age, species, population) and extrinsic (environmental variables) drivers. We assessed synchrony in growth variation within and among species and identified common change points in population specific growth patterns. We documented time‐variant synchrony in growth variation of geographically and bathymetrically segregated deep‐sea fish populations, lasting 25 and 18 years, respectively. The observed synchrony was likely driven by shared environmental forcing (Moran effect) as large‐scale climate indices (East Atlantic pattern and North Atlantic Oscillation) were important environmental drivers of overall growth variation while the onset of synchrony in growth variation was likely related to marine regime shifts occurring in a wide area of the northeast Atlantic that affected the entire ecosystem. However, our capacity to extrapolate growth information across species and locations was dependent on the timing and magnitude of environmental change. Developing a better understanding of the mechanisms driving growth synchrony is key to ensure sustainable management of populations in habitats that are fragile and highly sensible to environmental change, such as the deep‐sea.

Trace elements in a Mediterranean scorpaenid fish: Bioaccumulation processes and spatial variations

The black scorpionfish Scorpaena porcus, a carnivorous sedentary species, was studied as an indicator of local trace element (TE) contamination of coastal fish species in the northwestern Mediterranean Sea. Fish were collected in seagrass meadows in winter 2012 at four sampling sites: three were located near Marseille, a highly urbanized and industrial area that is subjected to various types of contaminant inputs, and one was located near Hyères, a less urbanized area. Size, sex, age and diet of fish were determined before stable isotope and TE analyses. C and N isotopic compositions and concentrations of nine TEs (As, Ba, Cd, Cu, Cr, T-Hg, Ni, Pb, and Zn) were determined in dorsal white muscle. Most TEs did not bioaccumulate in S. porcus, as no increase in TE concentrations with increasing size, age or trophic level of fish was evident. Total mercury (T-Hg) was the only element to bioaccumulate and biomagnify, displaying strong positive correlations of its concentration with age (r = 0.88, p < 0.01), length (r = 0.84, p < 0.01) and δ15N value (r = 0.68, p < 0.01). Compared with the reference site, higher concentrations of As, Ba, Cd, T-Hg, Pb, and Zn were recorded in fish collected at one or all of the Marseille site. In contrast, no difference was observed for Cr, Cu, and Ni concentrations with site. Spatial differences in TE concentrations in S. porcus were related to differences in isotopic composition and to the primary environmental characteristics and human activities prevailing at each site. Concentrations of Cd, T-Hg and Pb in fish muscle (priority substances for monitoring) were all below the maximum permitted European values.

Activities of digestive enzymes and histology of digestive system during larval development of devil stinger (Inimicus japonicus)

Devil stinger is a valuable demersal scorpaenid fish while the rearing of stinger larvae still relies on live prey. This study was conducted to illustrate the development of the main digestive enzymes and digestive system during larval development of this species to provide evidence for the application of artificial feeds. Enzymatic and histological assays were conducted from 1 day post hatching (dph) to 36 dph in larvae. The result showed that the selected digestive enzyme activities increased significantly after 15 dph. Specifically, the total trypsin activities increased significantly from 18 dph to 33 dph. The total pepsin and amylase activities increased significantly first and thereafter decreased significantly. The lipase activities followed the similar pattern with trypsin. With regard to the histological study, the stinger larvae open their mouth to first feeding at 3 dph and turned into totally exogenous nutritional stage at 6 dph. In addition, mucous membrane, rich in goblet cells, was widely distributed in oesophagus epithelium at 18 dph. The height and amounts of gastric gland in cardia and main body of the stomach increased gradually with the development of stinger larvae after 15 dph. The intestine length of stinger larvae was short, and goblet cell was abundant in anterior intestine after 12 dph, not the posterior intestine. The ontogeny of liver and pancreas started from newly hatched stage, and the differentiation of liver was prior to pancreas. The above findings would provide evidence for the use of artificial feeds from the larval stage of stinger larvae (at least from 21 dph).

A new species of Prohatschekia Nunes-Ruivo, 1954 (Siphonostomatoida: Hatschekiidae) from the scorpaenid fish, Scorpaena neglecta Temminck & Schlegel, 1843 (Scorpaeniformes: Scorpaenidae), in Korean waters.

A new species of parasitic copepod, Prohatschekia pseudocremouxi sp. nov. is described based on adult females collected from the gills of the scorpaenid fish, Scorpaena neglecta Temminck & Schlegel, 1843 caught in Korean waters. The new species is most closely related to P. cremouxi Nunes-Ruivo, 1954, but differs from it by the following combination of characters in the adult female: the size of the trunk which is about 3.7 times as long as cephalothorax; the short and strongly curved antennary claw; and the distal segment of the maxilla is tipped with a simple seta. This discovery raises the number of nominal species in Prohatschekia Nunes-Ruivo, 1954 to eight and represents the first record of the genus in Korea.

A new species of scorpionfish, Ebosia vespertina (Scorpaenidae: Pteroinae), from the southwestern Indian Ocean

A new species of scorpaenid fish, Ebosia vespertina sp. nov., is described on the basis of 19 specimens from off Mozambique, South Africa, and Madagascar, southwestern Indian Ocean. The new species is most similar to Ebosia falcata and Ebosia saya, known from the northern and eastern Indian Ocean and Saya de Malha Bank, respectively, in having usually 8 anal-fin soft rays, usually more than 17 pectoral-fin rays, and the elongated parietal spine in males narrow and strongly curved posterodorsally. However, E. vespertina can be distinguished from the two latter species by the following combination of characters: pectoral-fin rays 17–18 (modally 18); scale rows above the lateral line 4–6 (5); scale rows between the last dorsal-fin spine base and lateral line 4–5 (5); scale rows between the sixth dorsal-fin spine base and lateral line 4–5 (5); postorbital length 17.4–20.3 (mean 18.7) % of standard length (SL); longest pectoral-fin ray length 54.6–73.9 (65.1) % of SL; longest pelvic-fin soft ray length 32.4–44.0 (37.6) % of SL. The remaining congener, Ebosia bleekeri, known from the western Pacific Ocean, usually has 7 anal-fin soft rays and 16 pectoral-fin rays, and the elongated parietal spine in males relatively broad and not so strongly curved.

Shortspine thornyhead and rockfish (Scorpaenidae) distribution in response to substratum, biogenic structures and trawling

Learmonth Bank in northern British Columbia sustains an active trawl fishery that returns large bycatches of deep-sea sponges and corals. To examine effects of biogenic structures on the distribution of fish, we examined nearly 30 km of high-definition imagery from a remotely oper- ated vehicle and documented locations of 2770 scorpaenid fish. The 2 local genera have similar abun- dances, averaging about 1.2 individuals 100 m -2 , but have different spatial abundance patterns: shortspine thornyhead Sebastolobus alascanus are randomly distributed on featureless substrata and their abundance increases with depth. Rockfish Sebastes spp. associate with higher seafloor relief nonrandomly and select for sponges and corals over the inert substrata alone; 95% of the rockfish occurred on 27% of the seafloor surveyed. Sponges (Demospongia and Hexactinellida) were abun- dant on the bedrock and boulders of the bank and adjacent moraine and covered 30 to 55% of the seafloor compared with 1% of the sediment and aggregates of the surrounding basin. The majority of rockfish (80%) occurred with sponges ≥50 cm in height, and even beds of short sponges attracted 4 times as many rockfish than did substrata with no large epifauna. While over half of primnoid corals over 30 cm tall had associated rockfish, less than 2% of the seafloor had large coral, and small coral had no associated rockfish. On the adjacent seafloor with past trawling activity, Primnoa pacifica was 13 times less abundant, and large corals and sponges were rare. Thornyhead abundance doubled but rockfish had a 3-fold reduction in numbers. Our study indicates that degradation of biogenic struc- tures is a long-term detriment to rockfish species and, although the mechanism remains unclear, our data suggest it occurs through the destruction of a habitat that is more effective for shelter than rough inert seafloor.

Larvae and Juveniles of the Scorpaenid Fish, Sebastes schlegeli

Larvae and Juveniles of the Scorpaenid Fish, Sebastes schlegeli

First Record of the Scorpaenid Fish Brachypterois serrulatus from Japan, with a Key to Japanese Genera of the Pteroinae

First Record of the Scorpaenid Fish Brachypterois serrulatus from Japan, with a Key to Japanese Genera of the Pteroinae

Early developmental stages of the scorpaenid fish, Scorpaena miostoma, reared in the laboratory

Embryonic development and morphology of the eggs, egg masses and larvae of the scorpaenid fish,Scorpaena miostoma are described on the basis of the laboratory-reared specimens. The gelatinous egg mass is not bilobed but simple, oval and balloon-like in shape. It usually floats at or near the surface. The individual egg is colorless and ovoid in shape, measuring 0.86 × 0.75 mm. Hatching occurs between ca. 34 and 40 hours after spawning at the water temperature of 22–24°C. A newly hatched larva measures 1.55 mm in notochord length and has ca. 25 myomeres. The finfold is balloon-like in shape and almost completely covers the larval body. Minute “cell-like” granules scatter on the findfold.

Comparative study on ovarian structures in scorpaenids: possible evolutional process of reproductive mode

The reproductive modes of the Scorpaenidae are extremely varied: oviparity, viviparity, and even spawning of internally fertilized eggs or embryos (zygoparity or embryoparity), as in Helicolenus, are known. The ovarian structure of this family is divided into two types by the arrangement of the stroma and the ovarian cavity. One type is the ovary in which the lamella-like stroma develops from the ovarian hilus located on the dorsal side and where the ovarian cavity is located on the ventral side of ovary, classified as “cystovarian type II-1” by Takano (1989). In the other type, the stroma in the ovary develops radially around the blood circulatory system that traverses the center of the ovary, and then the ovarian cavity surrounds all the ovary, classified as “cystovarian type II-3” by Takano (1989). In the present analysis, previous reports about ovarian structure and the relationship to the reproductive mode of scorpaenids were described, and the ovarian structure of eight genera of Scorpaenidae was examined. The ovary of cystovarian type II-1 is seen only in viviparous genera and is not seen in oviparous genera. However, the cystovarian type II-1 is a general structure in other families of Scorpaeniformes, and this structure could be considered a primitive type of ovary rather than that acquired by the process of evolution from oviparity to viviparity. The ovary of cystovarian type II-3 is seen in all six oviparous genera and the one zygoparous genus examined. The ovary of this type is not found in any other family of teleosts, so it could be a structure originally divided in Scorpaenidae. In the genera having the cystovarian type II-3 ovary, there is a common feature of spawning: a floating egg mass encompassed by the gelatinous material. We postulate that the evolution of reproductive mode in the scorpaenid fishes is as follows: Sebastes and Sebastiscus have a primitive ovary in which viviparity has developed, whereas the genera that spawn a floating egg mass evolved the ovarian structure from primitive type to cystovarian type II-3, and further zygoparity, such as in Helicolenus, evolved from them.

A new species of Prohatschekia Nunes-Ruivo, 1954 (Copepoda: Hatschekiidae) parasitic on Scorpaena elongata (Cadenat) off Algeria

A new species of parasitic copepod, Prohatschekia mediterranea n. sp. (Siphonostomatoida: Hatschekiidae), is described from a scorpaenid fish, Scorpaena elongata, collected off Algeria. This is the seventh species of Prohatschekia Nunes-Ruivo, 1954 to be described and the first record of the genus from the Mediterranean Sea. The new species is most closely related to P. cremouxi Nunes-Ruivo, 1954, known from a congeneric host collected in Senegal. A key is provided to distinguish the new species from other members of the genus.

Age determination and validation studies of marine fishes: do deep-dwellers live longer?

Age determination and validation studies on deep-water marine fishes indicate they are difficult to age and often long-lived. Techniques for the determination of age in individual fish includes growth-zone analysis of vertebral centra, fin rays and spines, other skeletal structures, and otoliths (there are three sets of otoliths in most bony fish semicircular canals, each of which is made of calcium carbonate). Most have regular increments deposited as the fish (and its semicircular canals) grows. The most commonly used otolith for age determination is the largest one called the sagitta. Age validation techniques include: (1) tag-recapture, often combined with oxytetracycline injection and analysis in growth-zones of bone upon recapture; (2) analysis of growth-zones over time; and (3) radiometric approaches utilizing a known radioactive decay series as an independent chronometer in otoliths from bony fishes. We briefly summarize previous studies using these three validation approaches and present results from several of our radiometric studies on deep-water, bony fishes recently subjected to expanding fisheries. Radiometric age validation results are presented for four species of scorpaenid fishes (the bank, Sebastes rufus, and bocaccio, S. paucispinis, rockfishes, and two thornyhead species, Sebastolobus altivelis and S. alascanus). In addition, our analysis of scorpaenids indicates that longevity increases exponentially with maximum depth of occurrence. The reason that the deep-water forms of scorpaenid fishes are long-lived is uncertain. Their longevity, however, may be related to altered physiological processes relative to environmental parameters like low temperature, high pressures, low light levels, low oxygen, and poor food resources.

Accurate 3-D Morphological Measurement Using a Structured-Light Range Sensor

A single-plane structured light range-sensor was tested to establish its usefulness in acquiring 3-D measurements of fish skulls. Twenty-one distances among 22 landmark points for each of 12 neurocrania of the scorpaenid fish Neomerinthe hemingway were taken with digital calipers, with a video-based 2-D imaging system widely used in systematic studies, and with a single-plane structured-light range sensor of inexpensive and simple design. Measures taken by 3-D sensor are highly correlated with those obtained from caliper measurement (r = 0.9995, P << 0.001 ), with a precision ranging from 0.08–0.43 mm. Like caliper-based measurements, they are less strongly correlated with measurements derived from projected video-imaging. Most skulls were scanned in just over 3 minutes each. Range maps, typically establishing the (x,y,z) coordinates of more than 75,000 points per scan, can be obtained in about 40–50 CPU seconds using software running on multiple platforms. Sensor data taken from different views can be merged to build a more complete 3-D reconstruction. System design, calibration, and use are discussed. By eliminating error due to perspective effects inherent in measuring from projected video images, such sensors hold considerable promise in quantifying biological shape in 3-D for comparative and functional studies.

Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 219:229-239 (2001) - doi:10.3354/meps219229 Baseline respiration and spontaneous activity of sluggish marine tropical fish of the family Scorpaenidae Christopher Zimmermann1,2,*, Andreas Kunzmann1,3 1Institut für Polarökologie der Universität Kiel, Wischhofstr. 1-3, Geb. 12, 24148 Kiel, Germany 2Institut für Seefischerei, Bundesforschungsanstalt für Fischerei, Palmaille 9, 22767 Hamburg, Germany 3Zentrum für Marine Tropenökologie, Universität Bremen, Fahrenheitstr. 6, 28359 Bremen, Germany *E-mail: czimmermann@ipoe.uni-kiel.de ABSTRACT: Baseline respiration and spontaneous activity were determined simultaneously for 6 specimens of tropical scorpionfishes, belonging to 2 different genera: Scorpaenopsis oxycephalus and S. diabolus (false stonefish) and Parascorpaena sp. and P. aurita. The experiments were conducted in an intermittent-flow respirometer at 24°C, at ambient light regime (12 h dark: 12 h light) and salinity (S = 32). Permanent measurements of fish activity by an infrared video system (number of movements) and oxygen consumption were coupled allowing the calculation of a standard oxygen consumption (SOC) rate. The experimental set-up allowed quantification of spontaneous activity. Relative SOC values varied between 32.3 mg O2 h-1 kg-1 wet mass (wm) for a large S. oxycephalus (82 g WM) and 68.9 mg O2 h-1 kg-1 WM for the smallest investigated specimen, a P. aurita (16 g WM). The latter also showed the highest spontaneous activity rate (mean 98 movements h-1; max.: 870 h-1), while the values for the most sluggish individual did not exceed 24.6 h-1 (mean) and 480 h-1 (max.), respectively. Absolute SOC for a standard mass of 50 g was calculated to be 2.0 mg O2 h-1, using a wet mass versus oxygen consumption relationship of SOC (mg O2 h-1) = 0.26 x WM(g)0.527. The tropical scorpionfish investigated are some of the most sluggish fish found on coral reefs, with activity levels (means and variance) similar to that of boreal or polar scorpaenids (e.g. sculpins). In this respect, there was no indication for any specific adaptation to temperature. Baseline oxygen consumption values of the fish in this study were the lowest recorded for marine tropical species, and a first rough comparison of the resting metabolism of scorpaenid fish over a wide range of environmental temperatures might indicate a reduced thermal sensitivity of the tropical fish investigated. KEY WORDS: Respiration · Standard oxygen consumption · Spontaneous activity · Coral reefs · Scorpionfishes · Scorpaenidae Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 219. Online publication date: September 10, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Bathymetric demography, enzyme activity patterns, and bioenergetics of deep-living scorpaenid fishes (genera Sebastes and Sebastolobus):paradigms revisited

Previous metabolic studies of scorpaenid fishes have measured interand intra-specific diffcrt,nccs in physiological and biochemical capacities in fishes llving at different depths. Small sample sizes and undocumented provenance of the samplesstudied have not allowed a full examination of the environmental b a s t for metabolic adaptation. The objective of this study was to determine the bathymetric demography of 22 scorpaenid fishes of the genera Sebastes and Sebastolobus, and to examine intera l n t r a s p e c i f ~ c hanges in metabolic capacity in 4 of them (Sebastes goodei, Sebastes diploproa, Sebastolobrrs alascanus and Sel~astolobus altivelis) representative of different environmental conditions. Weattempted to collect samples that spanned the tull depth and size ranges of each species. We examined changes in mefabolic capacity as it was affected by size, depth ot occurrence, and the existence of an oxygen minimum zone (OMZ) centered at 800 m. Lactate dehydrogenasc (LDH) was measured as an indicator of glycolytic capacity. Citrate synthase (CS), a Krebs cycle enzyme, was measured as an indicator 01 aerobic capacity, Midate dehydrogenase (MDH), an enzyme which helps maintain redox balance between the mltochondrion and cytosol, was also used as an indicator of aerobic capacity. When normal17ed to a common size. S. goodei, S. diploproa, S. alascanus and S. altivelis displayed an inter-specific pattern of declining metabolic activity with depth of occurrence. Intra-specific size scaling of glycolytic capacity (LDH) was positive in the shallow-livlng S. goodei. However, no scaling occurred in S diploproa and S. alascanus, and negative scaling of glycolytic activity occurred in the deep-living S. altivehs. MDH did not scale in S. goodei and S. diploproa but was negative in the 2 deeper-living Sebastolobus species. CS activity scaled negatively in S. goodei, S. alascanus, and S. altivelis, but the deep-watc!r specialist, S. altivelis, had the steepest slope. S. altivehs was the only species where similar-sized individuals could be compared over a wide depth range. There was no elvvdtion of LDH, or increase in anaerobic poise, in response to the hypoxia of the OMZ. Rather, all 3 enzyme activities were highest at 600 m and generally declined with ~ncreaslng depth. Contrary to the existing paradigm, S. alascanus and S. altivelis were not found to be shallowand deep-living congeners. Rather. S. altivelis is a permanent resident of deep water, whlle S. alascanus settles in shallow water then migrates to deep water with the onset of sexual maturity. When living in deep water, the supposed shallow water species. S. alascanus, maintains hlgher activities of all enzymes and grows an order of magnitude larger (>5000 vs <500 g) . In deep-water slope habitats expected patterns of allometric scaling of white muscle enzyme activities appear to be altered by the limitations of food and oxygen availability, a pattern previously observed in flatfishes.

Differential Susceptibility of Guanine Nucleotide-binding Proteins to Pertussis Toxin-catalyzed ADP-ribosylation in Brain Membranes of Two Congeneric Marine Fishes.

Pertussis toxin-catalyzed [32P]ADP-ribosylation was used to probe the guanine nucleotide binding regulatory proteins Gi and Go in brain membranes from two scorpaenid fishes, Sebastolobus alascanus and S. altivelis. The membranes of the two species exhibit a differential sensitivity to [32P]ADP-ribosylation produced by a fixed concentration of pertussis toxin. The membranes from the deeper-living S. altivelis consistently incorporated more [32P]ADP than the membranes from S. alascanus. Proteins of 39 and 41 kDa are specifically labeled in both species, corresponding to the apparent molecular masses of the α subunits of Gi and Go. At 5°C the ribosylation reaction is linear for at least 7 h. The pertussis toxin concentration-response relationship was evaluated with concentrations of pertussis toxin from 0 to 100 ng/ {mu}l. The extent of [32P]ADP-ribosylation was quantified by autoradiography and computer-assisted image analysis. The EC50 values for pertussis toxin were similar for the two species, but the maximum level of [32P]ADP-ribosylation was significantly greater in S. altivelis brain membranes. Because the heterotrimeric holoprotein is the substrate for ribosylation, the modulatory effects of the guanyl nucleotides GDP and GTPγS on the ribosylation were assessed. GDP increased [32P]ADP-ribosylation of the α subunits in S. altivelis. Only the highest concentration tested (1000 μM) increased [32P]ADP-ribosylation in S. alascanus brain membranes and only to a modest extent. Increasing concentrations of GTPγS suppressed [32P]ADP-ribosylation in S. alascanus brain membranes, presumably by promoting dissociation of the holotrimer. GTPγS had much less of an effect on the S. altivelis brain membranes. These differences in the extent of ADP-ribosylation and the modulatory effects of guanyl nucleotides may reflect different coupling efficiencies of G proteins and receptors. The expression of the α and β subunits of Gi and Go in the two Sebastolobus species, the deep-sea morid teleost fish Antimora rostrata, and the rat were compared by Western immunoblotting of brain membranes with antipeptide antisera. Levels of Giα3 were 63% higher in brain membranes of S. altivelis than those in S. alascanus. The levels of Giα1, Giα2, Go and β36 were similar in the two species. Although the complement of G proteins identified by the array of antisera used was similar in all the species, there appears to be additional diversity of α subunits in the teleost brain membranes. In fish, antiserum to Goα reacted with an additional 41 to 42 kDa protein that was not expressed in rat brain.

Respiratory, Blood, and Heart Enzymatic Adaptations of Sebastolobus alascanus (Scorpaenidae; Teleostei) to the Oxygen Minimum Zone: A Comparative Study.

The scorpaenid fishes Sebastolobus alascanus and Scorpaena guttata have similar life styles but differ in their depth distributions: S. guttata lives in shallow water (< 180 m); adult S. alascanus occur predominantly on the upper continental slope (400-1200 m) where the oxygen minimum zone (OMZ) prevails and ambient temperature is much colder. Respiratory properties and the activities of heart-tissue enzymes of these species were compared to determine the effect of different thermal and ambient O2 regimens on metabolism. Measured over the appropriate habitat temperature ranges, the oxygen consumption (VO2) of S. alascanus is two to four times less than that of S. guttata. Correction for differences in habitat temperature accounted for over 50% of this reduction. The depth-related decrease in VO2 for these two benthic fishes is less than that observed for pelagic fishes. The VO2 of S. guttata decreases at O2 concentrations below 1 ml/l, whereas the VO2 of S. alascanus is regulated down to 0.3 ml/l. The ventilation frequency (Vf) of both species increases in progressive hypoxia; but at < 0.5 ml/l, the Vf of S. guttata declines, while that of S. alascanus does not. When measured at the same temperature, pH and CO2, the blood-O2 affinity of S. guttata is significantly lower than that of S. alascanus. The anaerobic/aerobic enzyme activity ratio of pyruvate kinase to citrate synthase, which correlates with the ability of heart tissue to tolerate hypoxia, is significantly higher for S. alascanus than S. guttata. Lactate dehydrogenase (LDH) activity in freshly collected S. alascanus is also significantly above that of specimens acclimated to normoxic water in the laboratory. Only the skeletal muscle isozyme of LDH (LDH-A) is present in the heart of S. alascanus, whereas S. guttata has both LDH-A and heart (LDH-B) isozymes. Data for metabolic rate, critical O2 tension, blood oxygen affinity, and heart metabolic enzyme profiles all show essential adaptations of S. alascanus for life in the OMZ.

Early developmental stages of the scorpaenid fish,Scorpaena miostoma, reared in the laboratory

Early developmental stages of the scorpaenid fish,Scorpaena miostoma, reared in the laboratory