Computational study of Richness and Diversity Indices of fish species in rivers and other wetland areas and fish marketplaces under Kurigram District, Banglades

The present study revealed that a total of 101 indigenous species of large fish (28 species) and Small Indigenous fish (73 species) belonging to 63 genera and 31 families were observed and identified while 17 exotic fish species were found under 5 families. Among the indigenous species, the highest number of species were found in family Cyprinidae and Bagridae with a relative diversity of 28.28% and 11.11%. In case of group species richness, highest number 27 fish species were found in catfish group followed by 12 species of carp, 8 species of each barbs and minnows, 6 species of eel fish, 8 species of loaches, 4 species of each prawn, snake-headed or airbreathing fish and glass perches, 3 species of each climbing perches and clupeid, 2 species of each goby fish, knifefish and puffer fish, and rest of the group true perch, leaf fish, halfbeak fish, Needlefish, mullet fish, anchovies and killifish has one species. Of the total species, 47 species were considered as least concerned, 10 species as vulnerable, 11 species as endangered, 11 species as critically endangered, 14 species as nearly threatened and 8 species as data deficient. Considering the seasonal variation for all selected areas simultaneously, Shannon-Weaver diversity (H) index were found ranged from 3.53 (May) to 4.37 (January) where the highest Shannon -Weaver diversity index value 4.37 were found in winter season while 3.01 in Phulkumar, 3.73 in Dudhkumar, 3.87 in Dharla, 3.67 in Tista and 3.79 in Brahmaputra were recorded separately.

Morphology and molecular phylogeny of Heterobothrium lamothei (Monogenea: Diclidophoridae), a gill parasite infecting the tiger puffer fish Lagocephalus sceleratus (Tetraodontidae)

ABSTRACT Members of the family Diclidophoridae are potentially dangerous species for the puffer fish aquaculture worldwide. They are parasitic polyopisthocotyleans, with a posterior haptor equipped with clamps for attachment to the host's surface, allowing the worm to resist the flow of water to maintain its position on gills. The anterior body of the worm is deformable, allows the worm to feed on blood sucked from fish gills. The present study is the first description of a Heterobothrium species from the gills of the tiger puffer Lagocephalus sceleratus (Tetraodontidae) from the coasts of the Arabian Gulf at Jubail, Saudi Arabia morphologically by light microscopy as well as by molecular analysis of the parasite partial 28S rRNA through multiple sequence alignments and phylogeny by maximum likelihood analysis which is provided for the first time for the described species. Seventeen tiger puffer fish were captured alive from marine water off Saudi Arabia; gills were separated and further examined for parasitic infection. Nine fish were found infected with a monogenean parasite which was robust, equipped by two buccal organs at the tapered anterior end; the posterior haptor was rectangular with four symmetrically arranged clamps, with no isthmus. Marginal hooks absent. Ovary elongated, U-shaped, testes numerous, irregularly shaped and extended from the posterior part of the ovary to the anterior margin of the haptor. Copulatory organ muscular, as a spherical cup armed with 12 to 15 genital hooks. The molecular analysis of the parasite 28s rRNA and phylogeny revealed a percentage of identities between 87.47-89.09%, with Diclidophoridae species within the monophyletic clade of Mazocraeidea where a maximum percentage of 89.09% were obtained for the morphologically different sister taxon H. okamotoi. The results obtained from molecular analysis are consistent with the conclusions drawn from morphological classification where that the parasite recorded was morphologically similar to H. lamothei which was not characterized by molecular analysis before. The recovered sequences were deposited into the GeneBank under accession number MT322610.

Isolation and Toxigenic Characteristics of a Tetrodotoxin Producing Bacteria

Tetrodotoxin (TTX) is a kind of neurotoxin with great scientific research and medicinal value. Studies have confirmed that microorganism is one of the important sources of TTX. However, the specific biosynthetic and regulatory pathway of TTX production by microorganisms are still unclear. In this paper, out of twelve symbiotic bacteria screened from the wild puffer fish (Fugu rubripes) collected from coastal sea area of Ningbo (Zhejiang, China), a strain named He-1 isolated from the liver of puffer fish was found can produce TTX. It was identified as Bacillus cereus based on physiological, biochemical characteristics and 16S rDNA gene analysis. However, the strain He-2, which is the subculture strain of He-1, cannot produce TTX under the normal culture condition. Further study showed that by adding the metabolite of the He-1, the ability of TTX producing of He-2 could be restored. A peptide compound was obtained by separating and purifying of the metabolites from strain He-1, which could induce the TTX production of strain He-2. This work will provide a new way for further revealing the anabolic pathway of TTX.

Tetrodotoxin, a Potential Drug for Neuropathic and Cancer Pain Relief?

Tetrodotoxin (TTX) is a potent neurotoxin found mainly in puffer fish and other marine and terrestrial animals. TTX blocks voltage-gated sodium channels (VGSCs) which are typically classified as TTX-sensitive or TTX-resistant channels. VGSCs play a key role in pain signaling and some TTX-sensitive VGSCs are highly expressed by adult primary sensory neurons. During pathological pain conditions, such as neuropathic pain, upregulation of some TTX-sensitive VGSCs, including the massive re-expression of the embryonic VGSC subtype NaV1.3 in adult primary sensory neurons, contribute to painful hypersensitization. In addition, people with loss-of-function mutations in the VGSC subtype NaV1.7 present congenital insensitive to pain. TTX displays a prominent analgesic effect in several models of neuropathic pain in rodents. According to this promising preclinical evidence, TTX is currently under clinical development for chemo-therapy-induced neuropathic pain and cancer-related pain. This review focuses primarily on the preclinical and clinical evidence that support a potential analgesic role for TTX in these pain states. In addition, we also analyze the main toxic effects that this neurotoxin produces when it is administered at therapeutic doses, and the therapeutic potential to alleviate neuropathic pain of other natural toxins that selectively block TTX-sensitive VGSCs.