Scat Scatophagus Argus Research Articles

Influences of supplemental methods of commercial probiotics on the growth and digestive enzyme activities of spotted scat Scatophagus argus fingerlings

Influences of supplemental methods of commercial probiotics on the growth and digestive enzyme activities of spotted scat Scatophagus argus fingerlings

The Effect of Benzo[a]pyrene on Xenobiotic Metabolizing Cytochrome P4501A (CYP1A) Expression in Spotted Scat, Scatophagus argus (Linnaeus, 1766)

Low molecular weight Polycyclic Aromatic Hydrocarbons (PAHs) are widely concerned due to their significant health risks such as carcinogenicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity on human and marine animals. The induction pattern of xenobiotic metabolizing cytochrome P4501A (CYP1A1) gene was studied on 150 spotted scat Scatophagus argus (weight 32±3 g) captured from Northern Persian Gulf and exposed to 0, 5, 10, 15, 20 mg kg-1 of benzo[a]pyrene in 100L aquarium. The induction of CYP1A1 was quantified using reverse-transcription real-time PCR from treated fish liver samples. The results revealed that the expression of CYP1A1 gene in S. argus liver is time-dependent and directly correlated to the concentration of B[a] P, therefore the study provides the basis for further use of CYP1A1 of this commercially ad ecologically important species as a biomarker.

The effects of Synthetic gonadotropin releasing hormone analogue (S-GnRHa) on artificial propagation of spotted scat, Scatophagus argus (Linnaeus, 1766)

Spotted scat Scatophagus argus is an important brackishwater species predominantly inhabited in south-west coast of Bangladesh. The aim of this study was to develop a hormonal induced reproduction protocol of farm-domesticated S. argus along with larvae rearing techniques. Synthetic gonadotropin releasing hormone analogue (S-GnRHa) was injected at the dose of 60:30 μg/kg BW (Female: Male). In female fish 20% of the total dose was applied as priming dose and 12 hours later 80% as resolving dose. The latency period ranged from 32 to 36 h was determined by observing the time between first injection and ovulation. However, after achieving full oocyte maturation and ovulation, eggs were collected by stripping and fertilization was carried out using pooled sperm from male. The mean ovulation, buoyancy, fertilization and hatching rate were found 70±1.8; 68±7.7; 40±2.3% and 53±5.2% respectively. Over the embryonic development following stages were witnessed in embryos: meroblastic cleavage (2-cell), blastula, gastrula and pharyngula. Maximum embryos hatched within 19 hr post fertilization at 28±2.0°C temperature and 28±2.0 ppt salinity. In this study, we dispense the first information on the reproduction of spotted scat in captive condition using S-GnRHa and the optimal dose limit and larval rearing techniques are established. Further studies are warranted to develop the larvae into juvenile stage under variable environmental conditions to increase the fertilization, hatching rate and survival of embryos.

Lysine requirement of the spotted scat Scatophagus argus (Linaeus, 1766)

The study aimed to determine the lysine requirement of young spotted scat Scatophagus argus (Linaeus, 1776) (average body weight = 10.7 g). The feeding trial was conducted for 8 weeks with 5 experimental diets which were isonitrogenous, isocaloric and isolipidic (35% CP, 18.3 MJkg-1, containing lysine levels as treatments containing equal dietary protein (35%) and lipid levels (5%) in 3 replicates. The lysine content was from 1.22 g to 1.94 g lysinekg-1 dry diet (35 to 55 gkg-1 CP) with an average content of 0.18 g lysinekg-1 dry diet per treatment. Results showed that the growth rate, feed conversion and protein efficiency ratios were significantly highest at lysine level of 1.58 gkg dry diet-1(45 gkg-1 CP). Fish survival was not influenced by dietary lysine. Lysine requirement level for juvenile scat was estimated using quadratic regression of the percent weight gain (PWG) and specific growth rate (SGR) against dietary lysine level to have a mean value of 1.64 gkg dry diet-1 (4.75 gkg-1 CP).

Inflammatory responses associated with hyposaline stress in gill epithelial cells of the spotted scat Scatophagus argus

The molecular processes of immune responses in mucosal tissues such as fish gills under environmental stress are poorly understood. In the present study, pro-inflammatory response under hyposaline stress and its regulation by cortisol/corticosteroid receptors (CRs) in gill epithelial cells of the spotted scat Scatophagus argus were analyzed. The fish were transferred to freshwater for 6 days (144 h) of acclimation. Following freshwater exposure, the cortisol concentration increased transiently before returning to the control level over time. mRNA expression of pro-inflammatory cytokines (TNF-a, IL-1b and IL-6) was stimulated by cortisol through CR signals at early stages of acclimation, but hyposaline stress inhibited their levels by the end of the experimental period. The transcriptional profile of anti-inflammatory cytokine IL-10 was quite different from these pro-inflammatory cytokines, and its value fluctuated within a narrow range during the experimental period. Full-length cDNAs of mineralocorticoid receptor (MR) and glucocorticoid receptor 1 (GR1) (different kinds of CRs) were cloned from the gills. Our results showed that MR and GR displayed mutually antagonistic effects during hyposaline stress. MR responded quickly at early stages, and its expression decreased with the drop of cortisol concentration. By contrast, GR expression was maintained at high levels after the acclimation of freshwater exposure. The tight coordination of GR and MR helps to shape the effects of stress on the immune system, which in turn, regulates the stress response. Our results confirm the interaction between endocrine and cytokine messengers and a clear difference in the sensitivity of GR and MR during the hyposaline challenge in gill epithelial cells of the spotted scat Scatophagus argus.

Cryptic diversity of the spotted scat Scatophagus argus (Perciformes: Scatophagidae) in the South China Sea: pre- or post-production isolation

The population genetic structure and historical demography of the spotted scat Scatophagus argus along the coast of the South China Sea were examined on the basis of a 1141-bp segment of the mitochondrial DNA cytochrome b gene to resolve difficulties in artificial breeding in Taiwan. In all, 213 samples were collected from 15 locations, and 75 haplotypes were obtained. The haplotypes were divided into two sympatric lineages. The genetic distance between these two lineages was 2.55%. The observed genetic structures are the result of complex interactions of historical events and oceanographic currents. During glaciations, sea level fluctuations played major roles in isolation, and changes in environmental factors affected diversification. The observed genetic patterns imply that these two lineages are not only genetically distinct, but also ecologically distinct populations. Such divergence may contribute to the development of reproductive isolation. These results suggest the existence of cryptic species within S. argus. We considered it possible that many populations from Taiwan Island were introduced from South-east Asia and that the populations in the Gulf of Tonkin originated from these introduced populations from Taiwan. This study offers important resources for the further study of conservation genetics, hybridisation and speciation.

Effect of Salinity on Survival, Growth, Body Composition, Oxygen Consumption, and Ammonia Excretion of Juvenile Spotted Scat

AbstractThe effects of five salinities (5, 10, 20, 30, and 35‰) on the survival, growth, body composition, oxygen consumption, and ammonia excretion of juvenile Spotted Scat Scatophagus argus (initial body size 3.3–3.4 cm body length and 2.0–2.3 g; final body size: 5.5–5.6 cm body length and 9.2–9.8 g) were studied. Salinity did not affect survival (>94%) or oxygen consumption rate (OCR) significantly, but it did affect growth, ammonia excretion rate (AER), and body composition. The growth rate was related to the combined effect of food intake (3.1–3.2%/d) and feed conversion efficiency (56.8–60.2%). The highest slope of the body length/weight with rearing time regression equation at 5‰ salinity was 0.0333/0.1137, which indicated that the growth rate of the fish at 5‰ salinity was higher than that of those at the other salinities for 70 d at 24.4 ± 0.4°C. The ammonia excretion rate decreased significantly with the increase of salinity. Low O:N ratios (5.6–19.2) occurred at salinities ranging from 5‰ to 35‰, indicating a protein‐dominated catabolism. Salinity affected crude protein content significantly, and high salinity was beneficial to protein deposition. The results indicated that juvenile Spotted Scat could adapt to a wide range of salinity, from 5‰ to 35‰. However, it is recommended that juveniles be cultured at low salinity (5‰).

Interspecific comparison of radiocesium trophic transfer in two tropical fish species

The trophic transfer of radiocesium (134Cs) was investigated in two tropical fish, the silver moony Monodactylus argenteus and the spotted scat Scatophagus argus. Juveniles of both species were exposed to dietary 134Cs using the pulse-chase feeding methodology. The food was brine shrimp (Artemia salina) previously exposed to the dissolved radiotracer. Depuration kinetics of 134Cs were followed for 45 d. Results showed that Cs was similarly efficiently assimilated by both species (AE > 50%). The estimated trophic transfer factors in the two species ranked from 1 to 2, suggesting that 134Cs could be biomagnified in both omnivorous species. In complement, dissections of 7 body compartments were carried out at three different times in order to highlight 134Cs organotropism. 134Cs organotropism was similar in both species: more than 50% of 134Cs was quickly distributed in the muscles and skeleton (after 3 days of depuration), which is likely related to the analogous behavior between Cs and K, an essential element for muscle contractions and bone formation.

Genomic structure, polymorphism, and expression analysis of the spotted scat Scatophagus argus major histocompatibility complex class I alpha gene

The complete complementary DNA (cDNA) sequence of the major histocompatibility complex (MHC) class I α gene in Scatophagus argus was obtained by homology-based cloning and rapid amplification of cDNA ends polymerase chain reaction (PCR. The intron sequences, polymorphism, and tissue expression of this gene were then analyzed. The gene cDNA sequence is 2020 base pairs (bp) in length, including a 86-bp 5′-untranslated region (UTR), 866-bp 3′-UTR and 1068-bp open reading frame. It contains seven exons and six introns, of which there are two types of the fourth intron with respective lengths of 655 and 691 bp; it also has microsatellite (T)n fragments, and the sixth intron has a separate 3′-UTR. From 42 individuals, 20 alleles of the class I α-chain gene were identified, called here “Scar-UA*0101–Scar-UA*2001,” which demonstrate high polymorphism. Reverse transcription-PCR analysis shows its expression in ten tissues, with high expression levels in the liver, spleen, and kidney, and low levels of expression in the stomach, intestines, and muscle. A tree depicting the molecular relationships built using the neighbor-joining method shows that Scatophagus argus has a close genetic relationship to Perciformes fish such as Sparus aurata, Dicentrarchus labrax, and a more distant relationship to salmonid and cyprinid fishes, amphibians, birds, and mammals.

Revision of Metahaliotrema Yamaguti, 1953 (Monogenoidea: Dactylogyridae), with new and previously described species from the spotted scat Scatophagus argus (Linnaeus) (Perciformes: Scatophagidae) in Vietnam.

An emended diagnosis of Metahaliotrema Yamaguti, 1953 (Monogenoidea: Dactylogyridae) is provided based on specimens of six species collected from the spotted scat Scatophagus argus (Linnaeus) (Scatophagidae) in Vietnam: M. scatophagi Yamaguti, 1953 (type-species); M. cf. yamagutii Mizelle & Price, 1964; M. mizellei Venkatanarasaiah, 1981; M. kulkarnii Venkatanarasaiah, 1981; M. ypsilocleithrum n. sp.; and M. similis n. sp. Methaliotrema filamentosum Venkatanarasaiah, 1981 from the whipfin silver-biddy Gerres filamentosus Cuvier (Gerreidae) is included as the only other valid member of the genus. Metahaliotrema arii Yamaguti, 1953 from an ariid catfish is considered incertae sedis within the Dactylogyridae; and Metahaliotrema srivastavai Singh & Agarwal, 1994 from a bagrid catfish is transferred to Chauhanellus Bychowsky & Nagibina, 1969 as Chauhanellus srivastavai (Singh & Agarwal, 1994) n. comb. Metahaliotrema geminatohamula Pan, Ding & Zhang, 1995 from spotted scat in China is determined to be a junior subjective synonym of M. scatophagi. The two new species and M. scatophagi, M. mizellei, and M. kulkarnii are described or redescribed based on specimens from Vietnam.

Long-chain polyunsaturated fatty acid biosynthesis in the euryhaline herbivorous teleost Scatophagus argus: Functional characterization, tissue expression and nutritional regulation of two fatty acyl elongases.

Both the spotted scat Scatophagus argus and rabbitfish Siganus canaliculatus belong to the few cultured herbivorous marine teleost, however, their fatty acyl desaturase (Fad) system involved in long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis is different. The S. argus has a △6 Fad, while the rabbitfish has △4 and △6/△5 Fads, which were the first report in vertebrate and marine teleost, respectively. In order to compare the characteristics of elongases of very long-chain fatty acids (Elovl) between them, two Elovl cDNAs were cloned from S. argus in the present study. One has 885bp of open read fragment (ORF) encoding a protein with 294 amino acid (aa) showing Elovl5 activity functionally characterized by heterologous expression in yeast, which was primarily active for the elongation of C18 and C20 PUFAs. The other has 915bp of ORF coding for a 305 aa protein showing Elovl4 activity, which was more efficient in the elongation of C20 and C22 PUFAs. Tissue distribution analyses by RT-PCR showed that elovl5 was highly expressed in the liver compared to other tissues determined, whereas elovl4 transcripts were only detected in the eye. The expression of elovl5 and elovl4 were significantly affected by dietary fatty acid composition, with highest expression of mRNA in the liver and eye of fish fed a diet with an 18:3n-3/18:2n-6 ratio of 1.7:1. These results indicated that the S. argus has a similar Elovl system in the LC-PUFA biosynthetic pathway to that of rabbitfish although their Fad system was different, suggesting that the diversification of fish LC-PUFA biosynthesis specificities is more associated with its Fad system. These new insights expand our knowledge and understanding of the molecular basis and regulation of LC-PUFA biosynthesis in fish.

Characterization and gonadal expression of FOXL2 relative to Cyp19a genes in spotted scat Scatophagus argus

In the present study, we cloned the full-length cDNAs of FOXL2, Cyp19a1a and Cyp19a1b and analyzed their expression patterns during gonadal development in spotted scat, Scatophagus argus. All three genes were expressed in ovaries and testes but showed sexual dimorphism. At early stages of gonadal development, the expression of FOXL2 in ovaries was higher than testes. FOXL2 expression deceased gradually as gonadal development continued, and reached the lowest level at the mature stage. Cyp19a1a and Cyp19a1b were expressed coordinately with FOXL2, except at the early vitellogenic stage in the ovary. The expression of FOXL2, Cyp19a1a and Cyp19a1b was mainly localized in granulosa cells of ovaries. In S. argus testes, strong expression of FOXL2 gene was observed in the interstitial cells including tubules and Leydig cells, while Cyp19a1a and Cyp19a1b were mainly expressed in Sertoli cells throughout gametogenesis. These results show that FOXL2 plays an essential role in sexual development, and imply that it may regulate Cyp19a1a and Cyp19a1b expression in S. argus.

Effects of temperature and fish oil supplementation on ovarian development and foxl2 mRNA expression in spotted scat Scatophagus argus.

In this study, the complete foxl2 complementary (c)DNA sequence was isolated by simple modular-architecture research tool (SMART)er rapid amplification of cDNA ends (RACE). Two year-old female spotted scat, Scatophagus argus, were reared at different temperatures (23, 26 and 29° C) for 6 weeks, or fed with different concentrations of dietary fish oil (0, 2 or 6%) for 8 weeks. Ovarian development, serum oestradiol-17β (E2 ) levels, as well as ovarian foxl2 expression were measured. At the end of experiment, ovarian foxl2 messenger (m)RNA expression in fish reared at 23 and 26° C was significantly higher than that in fish reared at 29° C, and that in 2 and 6% fish oil groups was also significantly higher than that in control group (P < 0·05). Serum E2 levels exhibited the same trend with foxl2 mRNA expression in temperature treatment groups and fish oil fed groups. There was a significant positive correlation between stage of oocytes and foxl2 expressions. Results showed that from 23 to 29° C, the optimal temperature for ovarian development in S. argus was 23-26° C, and 6% fish oil supplementation could effectively promote ovarian development. Optimal temperature and fish oil supplement might increase ovarian foxl2 mRNA expressions to promote ovarian development in S. argus.

Molecular cloning and dimorphic expression of growth hormone (gh) in female and male spotted scat Scatophagus argus

Spotted scat Scatophagus argus exhibits a typical sexual growth dimorphism in which the females grow faster than the males. Growth hormone (GH) is best known as an anterior pituitary hormone fundamental in regulating growth. To clarify the roles in sexual growth dimorphism in the spotted scat, gh cDNA was isolated from the pituitary. A phylogenetic tree was constructed based on the GH amino acid sequences of spotted scat and other vertebrates, and the resulting topology clearly reflects the taxonomic relationship of the Perciformes species selected. Alignment of GH amino acid sequences displayed very high similarity between the spotted scat and the other Perciformes species. The qRT-PCR analysis demonstrated that females exhibited higher pituitary gh mRNA levels than males at 6, 18, and 30 months (P < 0.05), which was 1.84, 4.61 and 6.34 times greater, respectively. In addition, immature males (6 months) exhibited higher pituitary gh mRNA levels than mature males (18 and 30 months). These results imply that the sexual growth dimorphism may be ascribable to the gh levels in pituitary in spotted scat.

Complete mitochondrial genome of the spotted scat Scatophagus argus (Teleostei, Scatophagidae)

The complete mitochondrial sequence of the spotted scat Scatophagus argus has been determined using long amplification polymerase chain reaction (LA-PCR). The total length of sequence is 16,778 bp, and includes 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes and 1 control region. The base composition of H-strand is 27.23% (A), 27.54% (T), 16.22% (G) and 28.81% (C), with an AT content of 55.08%. The arrangement of genes in S. argus is identical to that of other fish species. All genes are encoded on the heavy strand with the exception of ND6 and eight tRNA genes. The mitochondrial genome of S. argus presented here will contribute to resolve phylogenetic relationships within the family Scatophagidae and the Perciformes.

An overlooked and unexpected introduction? Occurrence of the spotted scat Scatophagus argus (Linnaeus, 1766) (Osteichthyes: Scatophagidae) in the Maltese Islands

The spotted scat Scatophagus argus (Linnaeus, 1766) is recorded for the first time from Malta and the Mediterranean from fish offered for sale at a Maltese fish market. Interviews with fish sellers and fishermen showed that this fish is caught occasionally in small numbers in trammel nets from shallows on seagrass meadows in the southeast of Malta and that it has been present since at least 2007. The native range of the species is the Indian Ocean and the tropical to warm temperate Pacific but the species is commercially available as a brackish water aquarium fish. Given that this species has also been regularly imported into Malta by the aquarium trade since at least 1986, an escape or deliberate release by an aquarist seem to be the most probably mode of introduction. It is surprising that this euryhaline species which requires brackish water to complete its life cycle should have become established in Malta where there is a dearth of such habitats.

Acanthocephala of Marine Fishes off Fiji Islands, with Descriptions of Filisoma longcementglandatus n. sp., Neorhadinorhynchus macrospinosus n. sp. (Cavisomidae), and Gravid Females of Rhadinorhynchus johnstoni (Rhadinorhynchidae); And Keys to Species of the Genera Filisoma and Neorhadinorhynchus

A parasitological collection from marine fishes off the Fiji Islands yielded 5 species of acanthocephalans from 4 species of fish as follows: Filisoma longcementglandatus n. sp. from scat Scatophagus argus; Neorhadinorhynchus macrospinosus n. sp. from vermiculated rabbit fish Siganus vermicularis; Neorhadinorhynchus nudum (Harada, 1938) Yamaguti, 1939 (Cavisomidae) from mackerel tuna Euthynnus affinis; Rhadinorhynchus johnstoni Golvan, 1969 (Rhadinorhynchidae) from E. affinis; and Neoechinorhynchus agilis (Rudolphi, 1819) Van Cleave, 1916 (Neoechinorhynchidae) from striped mullet Mugil cephalus. All are new locality records and, except for N. agilis, new host records. Filisoma longcementglandatus is distinguished from all other species of the genus by its very long cement glands and size and armature of its proboscis. Neorhadinorhynchus macrospinosus has distinctly larger proboscis hooks than all other members of the genus. Keys to species of the genera Filisoma and Neorhadinorhynchus are included. Gravid females of the inadequately described R. johnstoni are described for the first time. Taxonomic notes on the other acanthocephalan species are also included.