First report of de novo assembly and annotation from brain and blood transcriptome of an anadromous shad, Alosa sapidissima.

OBJECTIVES: American shad (Alosa sapidissima) is an important migratory fish under Alosinae and has long been valued for its economic, nutritional and cultural attributes. Overfishing and barriers across the passage made it vulnerable to sustain. To protect this valuable species, aquaculture action plans have been taken though there are no published genetic resources prevailing yet. Here, we reported the first de novo assembled and annotated transcriptome of A. sapidissima using blood and brain tissues. DATA DESCRIPTION: We generated 160,481 and 129,040 non-redundant transcripts from brain and blood tissues. The entire work strategy involved RNA extraction, library preparation, sequencing, de novo assembly, filtering, annotation and validation. Both coding and non-coding transcripts were annotated against Swissprot and Pfam datasets. Nearly, 83% coding transcripts were functionally assigned. Protein clustering with clupeiform and non-clupeiform taxa revealed ~ 82% coding transcripts retained the orthologue relationship which improved confidence over annotation procedure. This study will serve as a useful resource in future for the research community to elucidate molecular mechanisms for several key traits like migration which is fascinating in clupeiform shads.

Characterization and phylogenetic analyses of the complete mitochondrial genome of Sillaginopsis panijus (Perciformes: Sillaginidae).

The complete mitochondrial genome of Sillaginopsis panijus has been determined for the first time using Sanger Dideoxy DNA sequencing. The mitogenome is a circular molecule of 16,529 bp in length. It contains 37 mitochondrial genes (13 protein-coding genes, two ribosomal RNA, and 22 transfer RNA) and a control region as other bony fishes. In the phylogenetic analysis using 12H-strand protein-coding genes, monotypic S. panijus is situated separately from the genus Sillago. The present phylogeny supports its taxonomic position according to morphology and will be helpful for evolutionary analysis.

Cross-species gene enrichment revealed a single population of Hilsa shad (Tenualosa ilisha) with low genetic variation in Bangladesh waters.

Tenualosa ilisha is a popular anadromous and significant trans-boundary fish. For sustainable management and conservation of this fish, drawing an appropriate picture reflecting population status of this species is very essential based on their all-strategic habitats in Bangladesh. In this study, 139 samples from 18 sites were collected and cross-species gene enrichment method was applied. Like most of the Clupeiforms, nucleotide diversity of this shad was very low (0.001245-0.006612). Population differences between most of the locations were low and not significant (P > 0.05). However, P values of a few locations were significant (P < 0.05) but their pairwise FST values were very poor (0.0042-0.0993), which is inadequate to recognize any local populations. Our study revealed that the presence of a single population in the Bangladesh waters with some admixtured individuals, which may contain partial genes from other populations. Most of the individuals were admixed without showing any precise grouping in the ML IQtree and Network, which might due to their highly migratory nature. Fishes from haors and small coastal rivers were not unique and no genetic differences between migratory cohorts. The hilsa shad fishery should be managed considering it as a single panmictic population in Bangladesh with low genetic diversity.

Health risk estimation of metals bioaccumulated in commercial fish from coastal areas and rivers in Bangladesh.

Metal contaminations in commercial fish have become a great public health concern worldwide including Bangladesh. The current study was conducted to provide preliminary evidence of nine metals in three commercially significant fish namely Pampus argenteus, Sardinella longiceps and Tenualosa ilisha collected from four coastal stations- Kuakata, Pathorghata, Cox's Bazar, and Pirojpur, and eight stations of five rivers- Padma, Meghna, Jamuna, Katcha, and Nobogonga in Bangladesh. High magnitudes of Pb (0.74-4.59 mg/kg ww), Cd (0.07-0.24 mg/kg ww), and Mn (0.45-2.03 mg/kg ww) were recorded in the sampling stations that exceeded the maximum permissible limits (MPL) proposed by different recognized organizations. Significant mean differences of metal concentrations were observed (p < 0.05) between species and stations. In fish samples, excessive metals accumulations were recorded from Kuakata (St.1) at the coastal area, and Nobogonga (St. 12) among the rivers. The health risk assessment (HRA) was carried out comprehensively via the estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR) calculations. The outcomes of EDI, THQ, and HI suggest that chronic exposure to towering Pb content might pose potential health threats to inhabitants particularly living in highly polluted stations of the coastal area. In addition, the massive TR values of Cd intake through fish consumption from the coastal area might create cancer risks. Accordingly, the ingestion of metals contaminated fish portends chronic as well as acute health risks to Bangladeshi people living both at home and abroad.

Ecological risk and source apportionment of heavy metals in surface water and sediments on Saint Martin's Island in the Bay of Bengal.

The study aimed to determine eight hazardous heavy metals in surface water and sediment samples collected from the Naf River, Shah Porir Dwip (estuary), and mostly around Saint Martin's Island in the Bay of Bengal. The results of heavy metals in water samples were ranged as Pb 14.7-313.0, Cd 33.0-70.0, Cr < 11.0-37.0, Cu 38.0-57.0, Zn 26.8-69.2, Ni 102.0-285.0, and Hg 0.3-1.6 µg L-1. The concentrations of metals in sediment samples were ranged as Pb < 10.0-37.5, Cd 0.2-1.0, Cr < 5.0-30.1, Cu < 3.0-30.9, Zn 24.1-88.0, Ni < 4.0-48.3, As 0.1-7.3, and Hg < 0.01-0.08 mg kg-1 dw. Ni and Cr were strongly correlated, suggesting that this pair of metals might diffuse from a common origin. The contamination factor (Cif) demonstrated that sediment samples were mostly contaminated by Cd and slightly contaminated by Pb and Zn. The geoaccumulation index (Igeo) revealed considerable values for Cd on Saint Martin's Island. Cd as a single regulator posed moderate to considerable risk frequently among the sampling stations. Pollution load index (PLI) values remained below 1 (< 1), which indicated a decrease from baseline pollution value among all stations. However, potential ecological risk (PER) was graded for two stations (St1 and St13) with a moderate-risk zone due to the Cd contribution. However, shipping emission and lithogenic sources were the most predominant for heavy metals in the sediment, which were determined by applying the principal component analysis-absolute principal component score (PCA-APCS). Graphical abstract.

Health risk assessment of heavy metal accumulation in the Buriganga and Turag River systems for Puntius ticto, Heteropneustes fossilis, and Channa punctatus.

This study aimed to assess the effects of major ecotoxic heavy metals accumulated in the Buriganga and Turag River systems on the liver, kidney, intestine, and muscle of common edible fish species Puntius ticto, Heteropneustes fossilis, and Channa punctatus and determine the associated health risks. K was the predominant and reported as a major element. A large concentration of Zn was detected in diverse organs of the three edible fishes compared with other metals. Overall, trace metal analysis indicated that all organs (especially the liver and kidney) were under extreme threat because the maximum permissible limit set by different international health organizations was exceeded. The target hazard quotient and target cancer risk due to the trace metal content were the largest for P. ticto. Thus, excessive intake of P. ticto from the rivers Buriganga and Turag could result in chronic risks associated with long-term exposure to contaminants. Histopathological investigations revealed the first detectable indicators of infection and findings of long-term injury in cells, tissues, and organs. Histopathological changes in various tissue structures of fish functioned as key pointers of connection to pollutants, and definite infections and lesion types were established based on biotic pointers of toxic/carcinogenic effects. The analysis of histopathological alterations is a controlling integrative device used to assess pollutants in the environment.

Concentration of heavy metals in seafood (fishes, shrimp, lobster and crabs) and human health assessment in Saint Martin Island, Bangladesh.

A contaminated aquatic environment may end up in the food chain and pose risks to tourist health in a tourist destination. To assess the health risk for tourists that visit St. Martine Island, which is a popular domestic and foreign tourist destination in Bangladesh, a study is undertaken to analyse the level of heavy metal contamination from chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg) and iron (Fe) in six of the most consumed fish (L. fasciatus, R. kanagurta, H. nigrescens, P. cuneatus, P. annularis and S. rubrum) and five crustacean species, which consist of a shrimp (P. sculptilis), a lobster (P. versicolor) and three crabs (P. sanguinolentus, T. crenata and M. victor) captured. The samples were analysed for trace metals using atomic absorption spectrometer, and the concentrations of the metals were interpreted using the United State Environmental Protection Agency (USEPA) health risk model. The muscle and carapace/exoskeleton of shrimp, lobster and crabs were analysed and contained various concentrations of Pb, Hg, As, Cr, Cd, Fe, Cu, Zn and Mn. The hierarchy of the heavy metal in marine fish is Fe > Cd > Zn > Pb > Cu > Cr > Mn > Hg. The concentrations of Pb in the species R. kanagurta, H. nigresceus and S. rubrum were above the food safety guideline by Australia, New Zealand and other legislations in most marine fish and crustaceans. Crabs showed higher mean heavy metal concentrations than shrimp and lobster. Acceptable carcinogen ranges were observed in three fish species (R. kanagurata, H. nigresceus and S. rubrum) and one crustacean species (P. sculptilis) samples.

Human health risks from heavy metals in fish of Buriganga river, Bangladesh.

Heavy metals are known to cause deleterious effects on human health through food chain. Human health risks were evaluated from consumption of heavy metal contaminated fish from Buriganga River in Bangladesh. Whole body of five fish species (Puntius ticto, Puntius sophore, Puntius chola, Labeo rohita and Glossogobius giuris) were analyzed which contained various concentrations of Cd, As, Pb, Cr, Ni, Zn, Se, Cu, Mo, Mn, Sb, Ba, V and Ag. Concentrations of Mn, Zn, Se and Pb in all fish species were above the Food Safety Guideline (FSG) by WHO/FAO. Assessment of noncarcinogenic health hazard by target hazard quotient (THQ) indicated no concern from consumption of these fish except for Mn. However, all metals together may affect human health as revealed by hazard index (HI). The target cancer risk (TR) values suggested carcinogenic risk from Ni and As. Taken together it can be concluded that there is potential human health risk in consuming fish from river Buriganga.

Human health risk assessment of heavy metals in tropical fish and shellfish collected from the river Buriganga, Bangladesh.

Although fish, crustacean, and shellfish are significant sources of protein, they are currently affected by rapid industrialization, resulting in increased concentrations of heavy metals. Accumulation of heavy metals (V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Sb, Ba, and Pb) and associated human health risk were investigated in three fish species, namely Ailia coila, Gagata youssoufi, and Mastacembelus pancalus; one crustacean (prawn), Macrobrachium rosenbergii; and one Gastropoda, Indoplanorbis exustus, collected from the Buriganga River, Bangladesh. Samples were collected from the professional fishermen. Cu was the most accumulated metal in M. rosenbergii. Ni, As, Ag, and Sb were in relatively lower concentrations, whereas relatively higher accumulation of Cr, Mn, Zn, and Se were recorded. Mn, Zn, and Pb were present in higher concentrations than the guidelines of various authorities. There were significant differences in metal accumulation among different fish, prawn, or shellfish species. Target hazard quotient (THQ) and target cancer risk (TR) were calculated to estimate the non-carcinogenic and carcinogenic health risks, respectively. The THQ for individual heavy metals were below 1 suggesting no potential health risk. But combined impact, estimated by hazard index (HI), suggested health risk for M. pancalus consumption. Although consumption of fish at current accumulation level is safe but continuous and excess consumption for a life time of more than 70 years has probability of target cancer risk.