Crimson Snapper Research Articles

The Effects of Vibration Frequency on Oxidative Stress, Digestive Enzymes and ATPases of Crimson Snapper (Lutjanus erythropterus) Fry during Transport

In this study, we sought to characterize the effect of water vibration frequency stress on crimson snapper (Lutjanus erythropterus) survival to determine an optimal transportation speed. To achieve this, we used a transport tank (25 cm × 17 cm × 16 cm) to simulate the transport process. After 8 h at five different vibration frequencies (D1 = 75 rpm, D2 = 105 rpm, D3 = 135 rpm, D4 = 165 rpm, and D5 = 195 rpm), the pH and dissolved oxygen (DO) levels in the tanks decreased; ammonia nitrogen levels (NH4-N) and temperature (T) increased with increasing density; and significant changes in oxidative stress biomarkers, digestive enzymes, and ATPase levels were observed in crimson snapper fry. The enzyme activity increased and reached the maximum value at 195 rpm. The experimental results suggested that during the actual transport, when using transport tanks, the length of the transport time was less than 8 h, and setting the vibration frequency for transportation at 135 rpm was more appropriate, that is, a speed of 50 km/h for transporting crimson snapper fry.

Lipid‐lowering activity and underlying mechanism of glycosylated peptide–calcium chelate prepared by transglutaminase pathway

AbstractThe compounds that promote calcium absorption and osteogenesis may have great potential in controlling adipogenesis and obesity. In this study, the glycosylated peptides–calcium chelate prepared from Crimson Snapper scale protein hydrolysates (CSPHs) and xylooligosaccharide (XOS) via transglutaminase pathway with calcium absorption promoting and osteogenic activities, named XOS‐CSPHs‐Ca‐TG, were used to explore the potential prebiotic effect and lipid‐lowering activity on 3T3‐L1 cells. The presence of XOS‐CSPHs‐Ca‐TG in pure cultures could significantly promote the proliferation of probiotics (Bifidobacterium adolescentis and Lactobacillus acidophilus), enabling them to enter the logarithmic growth phase 2–4 h earlier. Results of in vitro fermentation of mice intestinal flora further indicated that XOS‐CSPHs‐Ca‐TG increased the number of beneficial bacteria such as Bifidobacterium and Lactobacillus by 11.57% and 7.63%, respectively, and boosted the production of short‐chain fatty acids, thereby improving the colonization ability of the intestinal microbiota. Results of quantitative real‐time polymerase chain reaction confirmed that XOS‐CSPHs‐Ca‐TG achieved lipid‐lowering effects by accelerating calcium influx and activating the mitogen‐activated protein kinase/extracellular signal‐regulated kinases signaling pathway, thereby inhibiting the gene expressions of the downstream peroxisome proliferator‐activated receptors γ and CCAAT/enhancer‐binding protein α, and further attenuating the secretion of adipokines and controlling the expression of key lipases. These results suggest that glycosylated peptides–calcium chelates are potentially functional foods in lipid metabolism‐related disease prevention.

The First High-Quality Chromosome-Level Genome of the Lutjanus erythropterus (Bloch, 1790) Using Single-Tube Long Fragment Reads and Hi-C Technologies.

Lutjanus erythropterus (Bloch, 1790), a Perciformes from the Lutjanidae family, is a commercially important species because of its taste and abundance. Despite the increase in genome resources in recent years, few genome assemblies are available within this fish family for comparative and functional studies. In this study, we determined the chromosomal genome of Crimson snapper using high-throughput Single-Tube Long Fragment Reads sequencing technology and Hi-C data. The final assembly size was 973.04 Mb with contig and scaffold N50 values of 1.51 and 40.65 Mb, respectively. We successfully scaffolded 95.84% of the genome sequence onto 24 chromosomes ranging in length from 19.37 to 49.48 Mb. A total of 22,663 genes and 13,877 gene families were identified in the genome, with 29 gene families being L. erythropterus-specific. A phylogenetic analysis using single-copy gene families showed that L. erythropterus and Larimichthys crocea had the closest genetic relationship with a divergence time of ∼47.7 Ma. This new genomic resource will facilitate comparative genomic studies as well as genetic breeding programs for L. erythropterus.

Combining catch-based indicators suggests overexploitation and poor status of Indonesia's deep demersal fish stocks

The Indonesian deep-slope demersal fisheries are economically valuable and contribute to the wellbeing of millions of people. However, the sustainability of these fisheries is uncertain because they lack data and assessment. As a precursor to management, we developed and applied a framework for using standardized catch per unit effort (CPUE) and spawning potential ratio (SPR) as indicators to assess eight primary species-fishing gear complexes: the Malabar blood snapper Lutjanus malabaricus (droplines and longlines), goldbanded jobfish Pristipomoides multidens (droplines and longlines), sharptooth jobfish P. typus (droplines and longlines), crimson snapper L. erythropterus (droplines), and rusty jobfish Aphareus rutilans (droplines). We standardized CPUE by identifying relevant fishing trips using a species-association approach and removing any changes in the index not attributable to abundance by using a delta-generalized linear model. SPR values were estimated on a per-recruit basis from life-history parameters using length data. Results indicated that in 2020, all stocks were unhealthy (SPR values < 25%) with only a few exceptions (e.g., P. multidens and L. erythropterus). Most fishing grounds with low SPR values had stable or decreasing CPUE trends, suggesting that current fishing rates are suboptimal or unsustainable. However, L. erythropterus had an increasing CPUE trend but moderate to low SPR, indicating that fishing pressure has decreased so SPR may be an underestimate, leading to an optimistic but uncertain conclusion about stock health and the sustainability of current fishing rates. Such discrepancies between CPUE and SPR may be challenging for the implementation of management measures, but we have outlined and applied a framework for interpretation. The most recent yield values set by the Indonesian Ministry of Marine Affairs and Fisheries for these stocks, however, are 1.4–2.4 times higher than our calculations. This discrepancy may be attributed to several factors, such as inclusion of species that are atypical for deep demersal fish stocks in the Ministry's estimates, differences in methods or the types of data used, or annual variability.

Weighted Gene Co-Expression Network Analysis of red body color formation of crimson snapper, Lutjanus erythropterus

Crimson snapper (Lutjanus erythropterus) is a highly valued economic fish species, with its red body color being a crucial economic characteristic. A systematic study of skin pigmentation could offer insights into the mechanism of red coloration. In this study, we conducted the first network analysis of snapper transcriptomes during key developmental stages of pigmentation, identifying a cascade of cellular development and responsive gene modules and key genes, including eight developmental-specific modules. Among the four candidate hub genes (TNNT2, ROBO2, APBA2, and APOD), APOD was involved in pigmentation development. The network further revealed some key genes, such as TYRP1a, TYRP1b, PMEL, BCO1, BCO2, CYP2J2, CYP2J6, CYP3A4, PNPLA2, FABP6, ENPP7, and FFAR3, associated with melanin synthesis, carotenoids, and lipid metabolism. Our findings showed that pteridine and carotenoids were involved in yellow coloration after initial feeding, while yellow pigmentation-related genes (e.g., GCH1, PTS, SPR, CBR1, SCARB1, CD36, ABCA1, NpC1L1, etc.) had the same expression pattern at three days post-hatching (3 dph). At the red coloration emergence stage (45 dph), we observed an RNA level signal indicating the conversion of coloring substances from pteridine to carotenoids. These results substantially enhance understanding of the molecular mechanisms underlying pigmentation and skin color variation in L. erythropterus, providing a theoretical basis for improving of body coloration in economically cultured fish and genetic breeding of ornamental fish.

In-vitro self-assembly and antioxidant properties of collagen type I from Lutjanus erythropterus, and Pampus argenteus skin

The fish processing by-products are rich source of various novel and valuable biomolecules such as collagen and gelatin. Herein, we have extracted and purified collagen from the skin of two different marine fish species-crimson snapper (Lutjanus erythropterus) and silver pomfret (Pampus argenteus). The processing of these fishes produces huge quantities of by-products such as skin, fins, and bones. So, the extraction of collagen will be promising for the value addition to their by-products. Finally, the yield is moderately high viz. 13% (crimson snapper) and 7.5% (silver pomfret) on dry weight basis, respectively. The isolated proteins were characterized by different physicochemical techniques like FTIR, CD, SDS-PAGE, Zeta potential analyzer, SEM, and EDX. The denaturation temperatures (Td) as determined by CD was 34.54 °C and 33.58 °C for crimson snapper and silver pomfret, respectively. The Td is close to the mammalian collagen and hence, they serve as better alternative to mammalian collagen. The collagen from both the sources had lowest solubility at a basic pH (8–10), and lower ionic strength while higher solubility in acidic pH (1–5), and higher ionic strength. Further, the fibrillogenesis process was studied to understand the effects of temperature and ionic strength on collagen in vitro self-assembly. Collagen self-assembly is advantageous in making collagen-based gels for cell culture, and biomedical applications. In addition, the antioxidant activities of collagen and collagen hydrolysates prepared by enzyme (trypsin) were examined by DPPH, FRAP, NO and TAP antioxidant assays. The hydrolysates showed outstanding antioxidant activities as compared to native collagen solution. The result shows that fish waste is the potential and sustainable sources of collagen where its applications are not limited by religious conflicts and threats of various transmittable diseases.

Analysis of opsin gene family of Crimson snapper (Lutjanus erythropterus)

Opsin is a fellow of the G protein-coupled receptors (GPCRs) superfamily. It can be divided into visual and non-visual opsin according to whether it is directly involved in visual imaging. Opsin plays an important role in visual image formation and the regulation of non-image forming functions such as circadian entrainment in the growth, development and evolution of fish. Crimson snapper belongs to Perciforme mainly found in the Indo-West Pacific and the South China Sea. It is one of the most influential economic fishes in the South China Sea. In order to study the existence and expression of opsin gene in Crimson snapper, we sequenced the genome and tissue sample transcriptome of Crimson snapper. In this study, 32 opsin genes were identified from the genome of Crimson snapper. The length of these genes ranged from 1061bp to 86203bp and were distributed on 15 different chromosomes. The analysis of opsin gene family of Crimson snapper showed that the sws2 had two extra copies as compared with that of Zebrafish. Domain and motif analysis revealed that all the 32 opsin genes have seven-(pass)-transmembrane domain receptors (7TM receptors) each, and the opsin family contained 10 common motifs. The expression level of opsin gene, confirmed by RT-qPCR, was analyzed by using nine tissues transcriptome databases of Crimson snapper. The results showed that almost all opsin genes were highly expressed in the retina and brain, except opn7a and opn7b which were expressed in intestine and red skin, and almost no expression in other tissues. Our results provide a comprehensive basic knowledge for the opsin gene family of Crimson snapper, which has significance for the study of the function of opsin in Lutjanidaes.

Characteristics and osteogenic mechanism of glycosylated peptides-calcium chelate

Finding effective practical components to promote bone mineralization from the diet has become an effective method to regulate bone mass. In this study, peptides-calcium chelate derived from Crimson Snapper scales protein hydrolysates (CSPHs), and xylooligosaccharide (XOS)-peptides-calcium chelate prepared by transglutaminase (TGase) pathway, named CSPHs-Ca and XOS-CSPHs-Ca-TG, were used to explore the effects of glycosylation on their structural properties and osteogenic activity in vitro. Results showed that XOS-CSPHs-Ca-TG had better calcium phosphate crystallization inhibition activity with more unified structures than CSPHs-Ca, and could effectively maintain a stable calcium content in the gastrointestinal tract. Meanwhile, the glycosylated peptide-calcium chelate could accelerate the calcium transport efficiency in the Caco-2 cell monolayer, up to 3.54 folds of the control group. Moreover, XOS-CSPHs-Ca-TG exhibited prominent osteogenic effects by promoting the proliferation of MC3T3-E1 cells, increasing the secretion of osteogenic related factors, and accelerating the formation of intracellular mineralized nodules. RT-qPCR results further confirmed that this beneficial effect of XOS-CSPHs-Ca-TG was achieved by activating the Wnt/β-catenin signaling pathway. These results suggested that glycosylation might be a promising method for optimizing structural properties and osteogenic activity of peptide-calcium chelate.

Protective effects of crimson snapper scales peptides against oxidative stress on Drosophila melanogaster and the action mechanism

Peptides derived from crimson snapper scales (CSSPs) were reported to possess excellent free radical scavenging activities in vitro. In present study, the anti-aging and anti-oxidative stress effects of CSSPs were evaluated in Drosophila melanogaster models. Results showed that the addition of CSSPs in the diets of normal Drosophila could effectively extend their lifespan and improve the motor ability of aged Drosophila. Moreover, CSSPs could protect Drosophila from oxidative damage induced by H2O2, paraquat and UV irradiation. The extension of lifespan was found to be associated with the effects of CSSPs in improving the antioxidant defense system of Drosophila, manifesting as the reduction of oxidation products MDA and PCO, the elevated activities of T-SOD, CAT and GSH-Px, and the upregulated expression of antioxidant related genes after CSSPs supplemented. Furthermore, CSSPs at 6 mg/mL significantly downregulated mTOR signaling pathway and activated autophagy in aged male Drosophila, and the inhibition on mTOR activation was probably mediated by the antioxidant effects of CSSPs. Our findings suggest that CSSPs have the potential in making dietary supplements against natural aging and oxidative stress in organisms.

Population dynamics of threadfin porgy Evynnis cardinalis, an endangered species on the IUCN red list in the Beibu Gulf, South China Sea.

Threadfin porgy Evynnis cardinalis is both a dominant fish species and an important fishing target in bottom trawl fisheries in the Beibu Gulf, South China Sea. It was listed as endangered (EN) in a recent International Union for Conservation of Nature (IUCN) red list. Despite its economic importance and endangered status, limited research on its biological characteristics and spatial-temporal distribution has been undertaken this last decade, creating uncertainty in current conservation and management. We analyse this species' spatial distribution characteristics using data from four seasonal bottom trawl surveys in 2014-2015, and report average catch per unit effort to vary seasonally, from 49.1 to 594.5 ind h-1 . Growth, mortality and sexual maturity are reported for four time periods based on data from bottom trawl fishery surveys over 1961-1962, 1998-1999, 2006, and 2014-2015. Length frequency distributions changed from bimodal to unimodal, and the female-to-male ratio increased. Mean body length and length at first maturity decreased, whereas the growth coefficient increased, indicating miniaturization, early sexual maturity and accelerated growth, respectively. We report sparid catch to have first exceeded maximum sustainable yield in 2001, and to have remained overfished from 2010 to 2015. Since the 1980s, low-trophic-level fishes such as E. cardinalis have replaced high-trophic-level fishes such as Crimson snapper Lutjanus erythropterus to become dominant species. As catches have increased substantially, these species have been faced with overfishing, driving the ecosystem into an unstable state.

Difficulties in DNA barcoding-based authentication of snapper products due to ambiguous nucleotide sequences in public databases

Fishery products are traded worldwide, have long and branched supply chains and are among the most counterfeit foods. Food control authorities are responsible of controlling food labelling in order to ensure the safety and quality of products. This is particularly important for tropical and subtropical fish species, such as snappers (Lutjanidae), because certain species are known to be frequently contaminated with ciguatoxins that cause harmful Ciguatera Fish Poisoning outbreaks. The analytical method of choice for the identification of a sample at species level is ‘DNA barcoding’, the sequencing of specific genetic markers and the comparison of the sequences with international nucleotide databases, such as GenBank and BOLD. However, the results of these analyses can be severely impaired by an insufficient data basis and especially by database entries with incorrect species annotations. In this work, the available nucleotide sequences for common genetic markers (COI, cytb, 16S rDNA, 12S rDNA, rag1 and ITS) of snapper species in GenBank were subjected to careful examination with regard to their unambiguousness and clarity. Phylogenetic neighbour joining trees were prepared and checked for ambiguous and contradictory placement of species' sequences with special emphasis on the Malabar blood snapper (Lutjanus malabaricus), the two-spot red snapper (L. bohar) and the crimson snapper (L. erythropterus). The results indicate that ambiguous and contradictory database nucleotide sequences impede the DNA barcoding-based authentication of snapper products at species level. A species assignment for the Malabar snapper and the crimson snapper based solely on database queries seems questionable.

Length-frequency data approaches to evaluate snapper and grouper fisheries in the Java Sea, Indonesia

Indonesia is the most important producer country of snapper and grouper species worldwide, with a notable increase in landings over the past decades. The Java Sea is one of the most frequently fished areas for these species in Indonesia, but in 2016 a decrease in landings was observed. This study applied two approaches (Length-based Indicators and Length-Structured Growth-Type-Group Model) to assess the status of snapper and grouper fisheries in the Java Sea, using length-composition data from the commercial fishery and covering multiple gears with different selectivity. The work focused on the dominant species in the catches: Malabar blood snapper (Lutjanus malabaricus), Areolate grouper (Epinephelus areolatus), Crimson snapper (Lutjanus erythropterus), and Goldbanded jobfish (Pristipomoides multidens). Considerable differences were observed, related to the type of gear used. Catch data obtained from the longline fishery presented good stock status indicators for all species studied. The spawning potential ratio (SPR) estimates calculated for Malabar blood snapper and crimson snapper indicated that these species are currently fished in the Java Sea at unsustainable levels (below 30 % SPR) by the dropline and mixed-gear fleets, while areolate grouper and goldbanded jobfish are not overfished (above 30 % SPR). For both methods, bias in Linf and, secondarily, bias in M/K have a stronger influence on the indicators values, in particular for the proportion of individuals above the length of optimal yield + 10 % (Pmega) estimates and SPR, than bias in Lmat values. This study highlighted other areas where improvements are critical to ensure the sustainability of the snapper and grouper fisheries in the Java Sea.

Bioactive peptides derived from crimson snapper and in vivo anti-aging effects on fat diet-induced high fat Drosophila melanogaster.

Crimson snapper is an important marine economy fish, and its scales are rich in collagen. Crimson snapper scale peptides (CSSPs) obtained from crimson snapper scales by enzymatic hydrolysis exhibited significantly antioxidant activities to DPPH, ABTS and hydroxyl radicals in vitro. In vivo antioxidant and anti-aging effects of CSSPs on the Drosophila melanogaster aging model constructed by lard were investigated in this study. The results showed that CSSPs could prolong the mean lifespan, 50% survival days and the maximum lifespan of Drosophila, and especially when the concentration of CSSPs was increased to 6 mg mL-1, the mean lifespan of male and female Drosophila increased by 21.2% and 26.2%, respectively, indicating the effective life extension effect of CSSPs. Meanwhile, the addition of CSSPs effectively reduced the contents of malondialdehyde (MDA) and protein carbonylation (PCO) and increased the levels of total superoxide dismutase (T-SOD) and catalase (CAT) in Drosophila, which showed a significant dose dependence. Besides, the antioxidant-related genes SOD1, SOD2 and CAT were up-regulated in Drosophila when fed with diets containing CSSPs. In conclusion, CSSPs played an antioxidant and anti-aging role by reducing the accumulation of peroxide products and improving the activity of antioxidant enzymes, as well as by up-regulating the expression of antioxidant-related genes. The results suggest that CSSPs have potential to be used in the food and healthcare industries as potential food-borne antioxidant and anti-aging agents.

Diversity and succession of microbial communities and chemical analysis in dried Lutianus erythropterus during storage

The population, diversity and succession of microbial communities and chemical characteristics of dried crimson snapper (Lutianus erythropterus) during storage for 50 days were investigated. The population of bacteria, yeasts and filamentous fungi in the samples were enumerated by culture methods using appropriate agar media. The amplicons of the 16S rRNA of bacteria and the ITS region of fungi were sequenced and compared with gene libraries to obtain the identity and abundance of microorganisms in the community. Free amino acids and several other chemical characteristics were determined by HPLC and corresponding chemical reaction methods. Before storage, the average counts of bacteria, yeasts and filamentous fungi in the dried fish were 3.2, 2.5 and 2.2 log CFU/g, which increased to 4.6, 3.6 and 3.9 log CFU/g, respectively after storage. Major succession in the bacterial > fungal communities occurred during storage as evidenced by a significant decline in the number and diversity of microbial communities. Predominant bacterial genera were Phytobacteria, Vibrio, Acinetobacter and Macrococcus in the freshly dried fish, which were replaced by Bacillaceae, Halomonas, Lentibacillus, Alkalibacillus after storage. The fungal community of the freshly dried fish consisted of Penicillum > Yamadazyma, Malassezia, Candida and Eurotiales with Penicillum being the most dominant. Penicillium camemberti was the most abundant fungal species in the dried fish before storage with most dominant after storage and accounted for >96% of the abundance. The succession in the microbial community was accompanied by major changes in chemical characteristics with a significant decrease in fat, and an increase in total free amino acids and total volatile basic nitrogen (TVB-N).

An assessment of fish and marine growth associated with an oil and gas platform jacket using an augmented remotely operated vehicle

Scientists, industry and regulators are seeking to understand the influence of oil and gas infrastructure in our oceans to mitigate its impacts and maximise environmental benefits. This project equipped a standard work-class ROV with a light-weight stereo-video camera system to collect high definition imagery of fish and habitats formed by marine growth associated with Woodside Energy's Goodwyn Alpha Platform jacket (GWA) 138 km offshore of Dampier, north-west Australia. ROV video surveys were rapidly performed by industry on four faces of the GWA jacket, from the surface to the seabed at 130 m, yielding 1 h and 14 min of imagery. The stereo-video cameras continued to film during standard ROV operations collecting a further 150 h of HD imagery, used to build a comprehensive fish species list. A total of 8676 individual fish from at least 57 species and 20 families, with an estimated combined mass of 8719 kg, were recorded from the vertical transects of four faces of the jacket. An additional 43 fish species from 21 families were recorded via rapid assessment of a subset of the additional, standard ROV operations imagery. The jacket was characterised by abundant Caranx sexfasciatus (bigeye trevally), Pseudanthias spp. (basslets), Heniochus diphreutes (schooling bannerfish), Labridae sp. (wrasse) and Acanthurus spp. (surgeonfish). Several fish important to the demersal scalefish fishery in the region were observed, including: Lutjanus argentimaculatus (mangrove jack), Lutjanus erythropterus (crimson snapper), Lutjanus malabaricus (saddletail snapper), Lutjanus russellii (Moses' snapper). Eleven broad marine growth types were observed with encrusting/enveloping species (brown algae, filamentous mat, coralline algae, calcite) and hard corals (Tubastrea sp.) present in the greatest coverage. Both marine growth and fish assemblages changed markedly with depth. The addition of a lightweight stereo-video system to an industrial ROV and the allocation of short amounts of time for rapid vertical surveys provided important information on the ecology of an oil and gas platform jacket. Future industrial ROV campaigns should consider utilising this approach to gather scientific information that may have value in the context of decommissioning comparative assessments and, more generally, improves our understanding of the impact of oil and gas infrastructure in our oceans.

Development of immune functionality in larval and juvenile crimson snapper Lutjanus erythropterus (Bloch 1790)

Ontogenetic development of the immune system in crimson snapper (Lutjanus erythropterus Bloch 1790) larvae was histologically and enzymatically studied from hatch to 36 days post-hatch (DPH). Primitive hepatopancreas appeared on 2 DPH and renal tubules started hematopoiesis on 4 DPH. The spleen anlage appeared on 6 DPH and the thymus formed on 14 DPH. Total activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and sodium-potassium adenosine triphosphatase (Na+ K+-ATPase) gradually increased after hatch, and showed a sharp increase after 29 DPH during the transitional feeding period from Artemia to inert feed. The specific activities of SOD, CAT, and GPX showed a trend of sharp increase and reached the maximum level on 4 DPH when exogenous feeding started, except for Na+ K+-ATPase where the peak occurred on10 DPH. The specific activities of these five enzymes reached the peak during the food transition from rotifers to Artemia, but the total activity of enzymes showed an increasing trend as fish grew. The present study provides new knowledge of the development of functional enzymes relevant to fish larvae immunity, sheds light on the understanding of the change of larval health, and improves hatchery management of crimson snapper.

The moonfish, Mene maculata (Perciformes: Menidae), and the crimson snapper, Lutjanus erythropterus (Perciformes: Lutjanidae), in Omani waters: a questioned occurrence and possible presence of self-sustaining populations

The first confirmed record of the moonfish, Mene maculata (Bloch &amp; Schneider, 1801) (Perciformes: Menidae), and the crimson snapper, Lutjanus erythropterus Bloch, 1790 (Perciformes: Lutjanidae), in Omani waters is reported on the basis of 10 (M. maculata) and 7 (L. erythropterus) specimens, ranging in total length 290–410mm and 300–720mm respectively, which were collected using gill-net on the coast of Muscat City, Oman. Morphometric and meristic data are provided and compared with those of several specimens of these species from other parts of the world. The present study reports on the largest recorded specimen of M. maculata. It also reports on the presence of a sustainable population of both species in the Oman Sea, Sultanate of Oman.

Ontogenetic development of digestive enzymes in larval and juvenile crimson snapperLutjanus erythopterus(Bloch 1790)

Ontogenetic development of digestive system in crimson snapper (Lutjanus erythopterus Bloch 1790) larvae was histologically and enzymatically (alkaline phosphatase, amylase, lipase, pepsin, trypsin) examined from hatching to 36 days post hatching (DPH). The ontogenetic development of crimson snapper larval fish ontogeny was divided into three distinct phases: phase I starting from hatch to the onset of exogenous feeding, phase II starting from first feeding (2–3 DPH) until the formation of gastric glands (13–14 DPH) and phase III beginning from the appearance of gastric glands and continuing onwards. The specific activities of amylase, lipase, trypsin showed sharp increase and reached to the maximum from hatch to 4 DPH, 10 DPH, 20 DPH, respectively, followed by a declining trend with irregular fluctuation. In contrast to other enzymes, the specific activities of alkaline phosphatase showed a gradual increase from hatch to 29 DPH, followed by a sharp increase towards 36 DPH. The specific activity of pepsin was firstly detected on 17 DPH and gradually increased towards the end of this study. The total activities of these five enzymes showed a gradual increase till 29 DPH, followed by a sharp increase towards 36 DPH except for amylase and lipase reaching maximum at 32 DPH. The present study provides better understanding of the digestive ontogeny of crimson snapper during the larval stage and a guide to feeding and weaning of this economically important fish in hatcheries.

Zeylanicobdella arugamensis, the marine leech from cultured crimson snapper (Lutjanus erythropterus), Jerejak Island, Penang, Malaysia

ObjectiveTo investigate the prevalence, phylogenetics and DNA barcoding of Zeylanicobdella arugamensis (Z. arugamensis) from crimson snapper (Lutjanus erythropterus), Jerejak Island, Penang, Malaysia. MethodsExperiment was conducted with 200 fish specimens of cultured Lutjanus erythropterus from Jerejak Island, Penang, Peninsular Malaysia. The water temperature and length for each fish were measured prior to parasites examination. Next, the morphological identification of parasites was performed. Genomic DNA from parasites was extracted for further molecular analysis. After PCR amplification, phylogenetic tree was constructed. The lowest Bayesian information criterion scores showed that the most compatible model is Tajima and Nei. Finally, data sets of cytochrome oxidase subunit I gene sequence and trace file have been submitted to Barcode of Life Data System. ResultsThe prevalence rate of Z. arugamensis was recorded to be 11.5%, and the intensity was 1.48. The low intensity was due to the water temperature recorded in this study (32.9–33.2 °C). All the individuals of Z. arugamensis recorded in this study showed a close relationship with species that were recorded in NCBI database (Z. arugamensisDQ414344, Aestabdella leiostomiDQ414305, Pterobdella amaraDQ414334 and Cystobranchus meyeriDQ414315) but less relationship with Aestabdella abditovesiculataDQ414300. Finally, the DNA sequences submitted to Barcode of Life Data System in accordance to species have already obtained Barcode Index Number as BOLD: ACM3477. ConclusionsThis study has provided an overview of sequence divergence at cytochrome oxidase subunit I gene, DNA barcodes and parasite prevalence of Z. arugamensis.

Sensory, Microbiological and Chemical Changes in Vacuum-Packaged Blue Spotted Emperor (Lethrinus sp), Saddletail Snapper (Lutjanus malabaricus), Crimson Snapper (Lutjanus erythropterus), Barramundi (Lates calcarifer) and Atlantic Salmon (Salmo salar) Fillets Stored at 4°C.

Quality assessment of finfish fillets during storage is important to be able to predict the shelf life of the fresh product during distribution. Microbial, chemical (pH, TMA, and TVB‐N), and sensory (Quality index assessment QIA, Torry scheme) changes in vacuum‐packaged blue‐spotted emperor (Lethrinus sp), saddletail (Lutjanus malabaricus), crimson snapper (Lutjanus erythropterus), barramundi (Lates calcarifer), and Atlantic salmon (Salmo salar) fillets stored at 4°C were evaluated for 5 days. Microbiological study included evaluation of TVC (total viable counts), total psychrotrophic organisms, and H2S‐producing bacteria. Numbers increased during storage time and reached an average of 8.5, 8.5, and 9.2 log10 cfu/g, respectively, for the five different fish species. These levels were above accepted microbiological limits for fish fillets. Although the sensory analyses showed a decrease in quality, none of the finfish fillets were considered unacceptable at the end of the storage trial. Chemically, there was a slight pH increase, but trimethylamine (TMA) levels remained low. However, total volatile basic nitrogen (TVB‐N) levels increased over time, reaching levels above 35 mg/100 g for blue spotted emperor, saddletail snapper, and crimson snapper by the end of the storage period. Results show that the deterioration of finfish fillet quality is a complex event of biochemical, sensory, and microbial factors, and multiple analyses may be required to define acceptability.