DNA-based species identification methods enable the reliable determination of species and a more accurate elucidation of evolutionary relationships. Internal transcribed spacer (ITS) rDNA regions are used as a reliable molecular marker in species discrimination. This study investigated the zoonotic nematode Eustrongylides excisus in Neogobius fluviatilis population of Lake Uluabat, Türkiye, contributing to the understanding of its genetic diversity, taxonomic status, and zoonotic risk. Sequencing of the ITS region identified a single, distinct haplotype from the Lake Uluabat isolates. Comparative genetic analysis revealed low-to-moderate intraspecific variation (pairwise distances: 0.000–0.0404) among global isolates. Phylogenetic analysis confirmed the monophyly of E. excisus and revealed geographically correlated clustering. Turkish isolates formed a distinct, well-supported clade most closely related to a homogeneous Italian clade. Chinese and Australian isolates showed greater internal diversity and grouped separately. The genetic data provide new insights into the structure of E. excisus, demonstrating both widespread, conserved lineages and region-specific diversification. The close phylogenetic relationship between Turkish and Italian isolates points to historical connectivity within the Mediterranean basin. These findings are crucial for monitoring the parasite's spread, understanding its evolutionary history, and developing targeted risk assessments for human infection.
Hybridisation happens a lot in Indian major carps, both in hatcheries and in natural water environments. This makes it very hard to maintain brood stock and keep the genetic integrity of native fish. Reliable identification of hybrids is therefore essential in sustainable aquaculture and conservation environments. The present study demonstrates the identification of an interspecific hybrid between rohu (Labeo rohita) and mrigal (Cirrhinus mrigala) using a morphometric approach along with some molecular markers. Fish samples identified as rohu, mrigal, as well as their putative hybrids, were collected from markets across the eastern states of India. Analyses of morphometric measurements were performed using regression and clustering techniques to explore phenotypic differences among the groups. The morphometric analyses showed a marked difference in growth relationships for rohu, mrigal and hybrids, and cluster analysis successfully separated the three groups. Further analyses through sequencing of the mitochondrial and nuclear DNA indicated that mrigal contributed more to mtDNA, reflecting maternal inheritance in hybrids, while the contributions from rohu were greater for nuclear genes, indicating paternal contribution. The combination of morphometric and molecular tools, therefore, could work effectively in identifying hybrids, ultimately improving broodstock management and conservation practices for Indian major carps.
This study aimed to optimize heat shock conditions for triploidy induction in all-female rainbow trout (Oncorhynchus mykiss) under controlled hatchery conditions. The experiment included a control group and two experimental groups. The first group consisted of eggs obtained from neo-males fertilized with natural females (treatments 1–27), and the second included eggs from natural male and female parents (treatments 28–54). Eggs were exposed to heat shock at 23, 25, and 27°C for 15, 17, or 19 minutes at 15, 17 and 19 minutes post-fertilization. Sperm used for fertilization was selected based on high motility, and eggs were handled under standardized conditions to minimize variability. Larvae were reared on a commercial diet until four months, and survival rates and triploidy success were evaluated. Survival rates at different developmental stages did not differ significantly among control and treated groups (P>0.05). In triploid individuals, erythrocyte nuclear volume and cell size were 2.38 and 1.57 times larger than diploids. The highest triploidy percentage was observed under 27°C for 19 minutes, applied 17 minutes post-fertilization; however, variation indicates sensitivity to precise timing and conditions. These findings suggest a practical, cost-effective approach for producing all-female triploid rainbow trout under controlled hatchery conditions.
The Vietnam Hungarian hybrid carp has been used as broodstock in several selective breeding programs; however, its underlying transcriptomic mechanisms remain poorly understood. In this study, pure Vietnamese carp (V) were crossed with pure Hungarian carp (H) and growth performance was evaluated after one year of culture. The greatest heterosis was observed in the V♀×H♂ cross (VH) compared with the reciprocal cross (H♀ × V♂, HV) and pure Vietnamese carp (VV). To elucidate the molecular basis of this hybrid vigor, high-throughput RNA-Seq was performed on liver and muscle tissues from fast- and slow-growing individuals within VH hybrids. A total of 28 differentially expressed genes (DEGs) were identified, including 11 upregulated and 17 downregulated in fast-growing fish. Gene Ontology enrichment analysis showed that the upregulated DEGs were mainly associated with growth related processes, whereas the downregulated DEGs were primarily involved in cell polarity and immune responses. Notably, fast-growing VH hybrids exhibited a stronger genetic influence from Hungarian carp, as reflected in both morphological traits and gene expression patterns. Overall, these findings provide novel insights into the molecular regulation of growth in hybrid common carp and highlight the potential of selective breeding strategies to improve growth performance in common carp.
Studies on the identification, functional roles, and environmental factors shaping the gut microbiota composition of the sea cucumber Bohadschia marmorata remain scarce. This study aims to (i) characterize the gut bacterial community structure of B. marmorata from Barobo, Surigao del Sur using 16S rRNA gene-based metagenomic analysis, (ii) describe microbial diversity and community composition, and (iii) identify bacterial taxa with potential relevance to probiotic development, opportunistic pathogenicity, and food safety. In November 2024 and February 2025, adult Bohadschia marmorata were collected from seagrass beds in Barobo, Surigao del Sur, with six individuals selected for gut microbiome analysis. The V3–V4 region of the bacterial 16S rRNA gene was sequenced using the Oxford Nanopore MinION platform and analyzed with QIIME2, SILVA, and PICRUSt2. The gut microbiota was dominated by Pseudomonadota (~60%), followed by Bacillota (~25%) and Bacteroidota (~10%). Functional profiling revealed enrichment in energy metabolism, carbohydrate degradation, amino acid metabolism, and oxidative phosphorylation. Several taxa, including Bacillus velezensis, Ruminococcus, and Pseudomonas, showed potential probiotic and biotechnological relevance. These findings provide baseline information for sustainable aquaculture, biomonitoring, and the ecological understanding of B. marmorata.
