The work deals with the oogenesis, spermatogenesis and associated reproductive structures of the little Indian squid Loliolus (Loliolus) hardwickei. Histological descriptions of the ovary, oviduct, testis and needham sac were made, the various changes observed during maturation were described and the functional significance was discussed. The female reproductive system consists of the ovary, glandular oviduct, lace-like oviducal funnel, paired nidamental gland, accessory nidamental glands and a seminal receptacle for sperm storage on the ventral side of the buccal cavity. The average size of the cells of the ovary varied from 7.635±3.466 µm (primary oogonia) to 1191.114±288.188µm (Ripe oocyte). Oocyte resorption or the presence of atretic oocytes was observed in some sections. The male reproductive system consists of the testis, vas deferens, spermatophoric organ, spermduct, the system of spermatophoric glands (SG) and spermatophoric sac (Needham sac) and penis. The spermatogenesis passed through the differentiation of primodial germ cells, primary and secondary spermatogonia, primary and secondary spermatocytes, rounded spermatids, and elongated spermatids to spermatozoa or sperms. The testis is connected to a thin-walled Needham sac by the spermatophoric duct. The testis is made up of numerous seminiferous tubules and is enveloped by tunica albuginea made up of connective tissue. Histological authentication of reproductive structures in L(L) hardwickei serves the specific purpose of providing a detailed understanding of the species' reproductive biology, which has implications for ecological, environmental, and conservation management efforts.

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Taxonomic ambiguity still exists in ariid catfish species identification. Morphological similarities occur in ariid catfishes which lead to misidentification of the species. To overcome this taxonomic ambiguity osteology is one of the effective integrated taxonomic tools for species discrimination. From this study, we provide an osteotaxonomic key for the field identification of ariid catfish species.The present paper deals with a comparative study of the five Ariidae family species discussed, they are Arius arius (Hamilton, 1822), Plicofollis layardi (Gunther, 1866), Netuma thalassina (Ruppell, 1837), Nemapteryx caelata (Valenciennes, 1840) and Osteogeneiosus militaris (Linnaeus, 1758). The osteological portions used for this study like premaxillary, dentary, neurocranium, otolith, vertebral and caudal bone. The aforementioned osteological portions made the important primitive characters that will be used to differentiate the species.

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Prolonged exposure of human dermal fibroblasts (HDF) to ultraviolet (UV) radiation triggers the production of reactive oxygen species by upregulating the expression of matrix metalloproteinases (MMPs), causing type-I collagen degradation and photoaging. A sulfated (1 → 3)/(1 → 4) mannogalactan exopolysaccharide (BVP-2) characterized as [→3)-α-Galp-{(1 → 4)-α-6-O-SO3-Manp}-(1 → 3)-α-6-O-SO3-Galp-(1→] was isolated from seaweed-associated heterotrophic bacterium Bacillus velezensis MTCC13097. Whole genome analysis of B. velezensis MTCC13097 (Accession number JAKYLL000000000) revealed saccharine biosynthetic gene clusters for exopolysaccharide production. BVP-2 administered cells showed noteworthy reduction in mitochondrial superoxide (∼85 %, p < 0.05) and ROS production (62 %) than those exhibited by UV-A irradiated HDF cells. Oxidative imbalance in HDF cells (after UV-A exposure) was recovered with BVP-2 treatment by significantly downregulating nitric oxide (NO) production (98.6 μM/mL, 1.9-fold) and DNA damage (?67 %) in comparison with UV-A induced cells (191.8 μM/mL and 98.7 %, respectively). UV-irradiated HDF cells showed a ∼30-50 % downregulation in the expression of MMPs (1, 2, and 9) following treatment with BVP-2. Considerable amount of sulfation (18 %) along with (1 → 3)/(1 → 4) glycosidic linkages in BVP-2 could be pivotal factors for down-regulation of the intracellular MMP-1, which was further supported by molecular docking and structure-activity studies. The (1 → 3)/(1 → 4)-linked bacterial exopolysaccharide (BVP-2) might be used as prospective natural lead to attenuate and mitigate UV-A-induced photoaging.

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The needlefish genus Ablennes remains monotypic, characterized by the globally distributed flat needlefish known as Ablennes hians. Their taxonomy has been mired with ambiguities due to the greater-than-average morphological variations observed in samples from different regions. Utilizing integrated taxonomic methods relying on mitochondrial molecular markers, it was revealed that the species initially perceived as a single entity is, in fact, a complex comprising at least three different species. In this context, we introduce two new species: Ablennes joseberchmansis sp. nov. and Ablennes gracalii sp. nov., They are morphologically distinct: in view of the morphometry and meristic characteristics. A. joseberchmansis sp. nov. and A. gracalii sp. nov. display distinct differentiation characteristics from A. hians in terms of dorsal fin, nostril position, dorsal fin origin, vertebrae count, scale counts, head length, eye diameter, interorbital width, maxilla length, dorsal ray height, depth at pelvic origin, lower lobe of the caudal fin, and caudal peduncle depthcaudal peduncle depth. These variations highlight their unique morphological traits and aid in their differentiation within the genus Ablennes. We assessed genetic relationships using a Maximum likelihood (ML) phylogenetic tree, revealing three distinct clades of morphological differences in Ablennes specimens from different morphological groups. The genetic variation, as represented by Kimura 2 parameter (K2P) distances, within the three Ablennes species spans from 6.5% to 9.4%. More specifically, we observed a 7.5% genetic difference between A. hians and A. joseberchmansis sp. nov., and a 6.5% distinction between A. hians and A. gracalii sp. nov. The interspecies divergence between the two newly identified species measured at 9.4%. These findings, which showcase the genetic distinctions among the three morphologically distinct Ablennes specimens, provide strong confirmation for the existence of three separate species within the Ablennes genus of needlefish in the Indian Ocean.

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Observations and analysis of the food and feeding habits of penaeid shrimp are decisive for understanding food webs and ecological processes. Published information on the feeding habits of the green shrimp, Penaeus semisulcatusDe Haan, 1844, from Indian waters, however, dates back four decades, despite the fact that green tiger shrimp is one of the important shrimp species that forms a unique fishery in Palk Bay, on the southeastern India. Hence, its dietary preferences were analysed concerning sex, season, gonad maturity, and size. The species preyed on were composed of diversified components, with mollusc remains being the most common food item in females, followed by crustacean remains, whereas in males, the crustacean remains were the most common food items followed by mollusc remains. There was no significant difference in the gastrosomatic index of females and gonadal maturity stages among seasons, but a significant difference among size groups. In males, there was no significant difference among seasons, gonadal maturity, and size groups. Females were more active feeders than males, and the difference could be seen in their size groups. Larger groups fed more actively than smaller groups. Feeding was more active in the post-monsoon and summer monsoon seasons. Penaeus semisulcatus dominates the ecosystem among the shrimp species due to its carnivorous behaviour. The observations made in this study form key inputs for trophic modelling and ecosystem-based studies, which could help develop suitable strategies for managing the shrimp resource in Palk Bay.

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