Akbar John

Background: The mangrove horseshoe crab ( Carcinoscorpius rotundicauda ), a species thriving in the muddy brackish waters of Cox's Bazar, holds significant ecological and biomedical value. Hematological and biochemical analyses can serve as a valuable diagnostic tool for assessing health; however, reports remain limited for horseshoe crabs. Objective: This study investigated hemolymph values to determine preliminary reference intervals (RIs) from free‐ranging mangrove horseshoe crabs. Methods: Forty adult Carcinoscorpius rotundicauda (20 males, 20 females) were collected from intertidal zones of Cox's Bazar in February 2024. Hemolymph was extracted by cardiac puncture under cold anesthesia for amebocyte counting and biochemical profiling. Plasma metabolites, enzymes, and electrolytes were analyzed using a standard automated laboratory biochemistry analyzer (Humalyzer 3000, Human Diagnostics, Germany), and data were statistically evaluated in accordance with established guidelines. Results: Total amoebocyte counts demonstrated substantial variability (RI: 0.6–38.5 × 10 ⁶ cells/mL). This study found significantly ( p < 0.05) higher levels of cholesterol, triglycerides, chloride (Cl ⁻ ), calcium (Ca ²⁺ ), magnesium (Mg ²⁺ ), and aspartate aminotransferase (AST) in female horseshoe crabs, whereas alanine aminotransferase (ALT) activity was significantly higher in males. In contrast, no significant ( p > 0.05) differences between sexes were observed in glucose, total protein, albumin, alkaline phosphatase (ALP), uric acid, creatinine, urea, blood urea nitrogen (BUN), sodium (Na ⁺ ), potassium (K ⁺ ), and amebocyte counts. Reference intervals (RIs) were established after excluding outliers identified across multiple measurands in both sexes. Conclusion: This study provides baseline data and underscores the need for further research, particularly across different seasons, to enhance the suitability and applicability of the established RIs.

Aim: Maintaining viable populations of the Atlantic horseshoe crab, Limulus polyphemus , is a high conservation priority given their biomedical importance and keystone status in coastal‐marine ecosystems, a task made more difficult by impending climate change. Their longevity and cryptic lifestyle have hindered population assessments, highlighting the value of a genetic and ecological approach to inform conservation planning. Location: Atlantic coast of the United States (from Maine to Florida) and Mexico (Yucatán Peninsula), covering the entire extant geographical distribution of the American horseshoe crab. Methods: Using genome‐wide polymorphisms from 55 samples across 16 sites, we inferred population structure via reconstructing ancestries and demographic histories. Using species distribution modelling and genome‐environment association analyses, we assessed future climate change impacts on extant populations. Results: Analyses on genome‐wide polymorphisms suggest two population clusters of L. polyphemus across its natural range, which diverged slightly before the Last Glacial Maximum and are separated by a habitat gap in the western Gulf. Historical demographic reconstruction indicates post‐glacial expansion, suggesting that current populations may be in an expansion phase. Environmental association analyses indicate a potentially high vulnerability to future climate change, particularly for the Florida sub‐population. Main Conclusions: Conservation strategies for L. polyphemus should account for populations' genetic differences and susceptibility to climate change. Maintaining and facilitating population expansion can be crucial to mitigate potential future bottlenecks. A uniform conservation approach may be inadequate due to varying regional vulnerabilities.

The phylum Cnidaria is the outgroup of Bilateria and includes sea anemones, corals, hydroids, and jellyfish. Cnidarians play crucial ecological roles in marine ecosystems, including the formation of highly diverse and productive coral reefs, and acting as important predator and prey species. They are also well known for their remarkable regeneration capacities. Here, we report single-cell RNA sequencing of bell tissue remodeling/regeneration after amputation in two species of scyphozoans or “true jellyfish,” the Asian moon jelly, Aurelia coerulea, and the flame jellyfish, Rhopilema esculentum. We delineated 12 cell populations in Aurelia and Rhopilema and revealed their respective marker genes and enriched gene pathways. During this process, conserved transcription factor Otx, TFAP2A, Erg, NFIA, and Wnt/β-catenin signaling pathway genes were identified. Additionally, we discovered two conserved, sequentially activated patterns, with putative proliferative cells, gastrodermal cells, neural cells, and secretory gland cells modulated in the first phase, followed by cnidocytes in the second phase. Further comparison among cnidarian genomes identified a suite of lineage-specific scyphozoan genes, a subset of which were frequently significantly expressed in cnidocytes in both jellyfish species. Using powerful single-cell RNA sequencing approaches, this study elucidates the evolution of lineage-specific genetic networks and biological processes in true jellyfish, which remain comparatively poorly studied, and in particular provides key insights into the molecular pathways underlying their remarkable regenerative capacity.

The phylum Cnidaria is the outgroup of Bilateria and includes sea anemones, corals, hydroids, and jellyfish. Cnidarians play crucial ecological roles in marine ecosystems, including the formation of highly diverse and productive coral reefs, and acting as important predator and prey species. Cnidarians are also well known for their remarkable regeneration capacities. Here, we report single-cell RNA sequencing during bell regeneration in two species of scyphozoans or true jellyfish, Aurelia coerulea and Rhopilema esculentum . We delineated 12 cell populations in Aurelia and Rhopilema , and revealed their respective marker genes and enriched gene pathways. Conserved transcription factor Otx and Wnt/ β-catenin signalling pathway genes were identified during regeneration processes. Additionally, we discovered two conserved, sequentially activated modules during regeneration, with stem cells, gastrodermal cells, neural cells, and secretory gland cells modulated in the first phase, followed by cnidocytes in the second phase. Further comparison among cnidarian genomes identified a suite of scyphozoan lineage-specific genes, a subset of which were frequently significantly expressed in cnidocytes in both jellyfish species during the first phase of regeneration. This study reveals key insights into the evolution and contribution of conserved and novel genes to the formation of lineage-specific genetic networks and biological processes.

Horseshoe crabs have survived until Holocene but, their persistence beyond the Anthropocene is challenged by drastic environment modifications that entail impoverishments and the resultant unusual growth sizes. Previously, allometry via morphometric ratio was introduced to classify horseshoe...

Macrobenthos animals are an architect of a variety of roles including as a part of the food web of aquatic ecosystem and improve the structure of the sediment and can determine the quality of the water. Macrobenthos communities have shown their potential role in biomonitoring to analyze contaminant loads due to high sensitivity to organic pollutants along the coastal water area. Besides, it is also used to determine heavy metals and petroleum hydrocarbons in coastal water due to their long sustainability with chemicals are primarily related with industrial calamities and occupational activities. Based on above perspectives, this systematic review has shown interesting findings about the macrobenthic diversity including community composition in the coastal areas of Malaysia. The study has focused on the diversity and abundance of macrobenthos communities along some potential coastal areas of Malaysia which emphasis on the states of Johor, Pulau Pinang, Selangor, Pahang, Terengganu, and Sarawak. Several studies have evidently revealed that pollutants and human activities have contributed to loss of macrobenthos towards abundance (individuals/m²) and species richness. The highest abundance of macrobenthos was Coleoptera sp. (1650 ind./m² followed by Hemiptera sp. (860 ind./m²) were observed in Sarawak and Crustacea sp. (597 ind/m²) was found in Selangor, respectively. While Crustacea (10 ind/m²) was found as the lowest in the coastal water Pahang only. A major shortcoming among the studies was sampling time along with sampling method which was observed in this systematic review of different studies of macrobenthic assemblages in the coastal waters of Malaysia. However, the existing study reveals the baseline information on macrobenthic community which are still inadequate in Malaysia. Hence, a long-term monitoring for eco-biology and species diversity of macrobenthic assemblages are necessary for their sustainable development in this fascinating tropical coastal water of Malaysia.

Two novel ternary hybrid nanoparticles (THNp) consisting of graphene oxide (GO) and reduced graphene oxides (rGO) were added to samples of DNA. The effect of the addition of nanoparticles on the thermal denaturation of DNA samples was studied by measuring the absorbance using a temperature-controlled Perkin Elmer UV spectrophotometer. Adding GO-TiO2-Ag and rGO-TiO2-Ag nanoparticles lowered the denaturation temperature of template DNA significantly. The nanoparticles affect the denaturation rate. The optimal GO-TiO2-Ag and rGO-TiO2-Ag concentrations were found to be 5 x 10(-2), which resulted in 86- and 180-folds augmentation of DNA denaturation (6.5 mu g/mL), respectively, while it resulted in 2- and 7-folds augmentation of DNA denaturation (11.5 mu g/mL), respectively, at temperature as low as 80 degrees C. The results indicated that rGO-TiO2-Ag nanoparticles exhibited significantly higher DNA denaturation enhancement than rGO-TiO2-Ag nanoparticles, owing to their enhanced thermal conductivity effect. Therefore, these nanoparticles could help to get improved PCR yield, hence enable amplification to be performed for longer cycles by lowering the denaturation temperatures.