Browsing by Author "NAJAFPOUR, BABAK"
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- Bacterial 16S ribosomal gene fingerprints as a tool to diagnose and mitigate fish larvae gut dysbiosisPublication . NAJAFPOUR, BABAK; Canario, Adelino; Power, Deborah MaryDysbiosis is associated with shifts in the diversity or relative abundance of beneficial versus harmful bacteria, leading to health issues in organisms. This study investigated gut bacterial dysbiosis associated with larval quality using 16S rRNA gene sequencing. The gut microbiome of gilthead sea bream and European sea bass, key commercial species and vertebrate models, was examined in high- and low-quality larvae batches from several European hatcheries. Larval quality, hatchery site and species influenced bacterial diversity in the gut. Individuals from larval batches that performed well had higher microbial diversity in the gut and individuals from batches that performed poorly had a gut microbiota dominated by pathogenic Vibrio (e.g., V. aestuarianus and V. cortegadensis). The bacterial dysbiosis index revealed a notable predominance of Fusobacteriota and Firmicutes phyla, Thermoanaerobacteria class and Lactobacillaceae, Moritellaceae, Clostridiaceae, Thiotrichaceae and Shewanellaceae families in good-quality larvae batches, and a prevalence of the Proteobacteria phylum, Gammaproteobacteria class, Sphingomonadaceae and Vibrionaceae families in the gut of individuals from poor-quality larvae batches. A positive dysbiosis index (cutoff >0.4) was associated with a high risk of decreased larval performance and quality. Additionally, the abundance of Clostridium_sensu_ stricto_15, Shewanellaceae_unclassified, Cetobacterium, Psychrilyobacter, Moritella and Latilactobacillus genera in the gut of good production batches, and the Vibrio genus in the gut of poor production batches, identified these genus as potential markers for diagnosing and mitigating bacterial dysbiosis in fish and potentially other vertebrates.
- Insights into core molecular changes associated with metamorphosis in gilthead seabream larvae across diverse hatcheriesPublication . NAJAFPOUR, BABAK; Santos, Soraia; Manchado, Manuel; Vidal, Aurora; Tsipourlianos, Andreas; Canario, Adelino; Moutou, Katerina A.; Power, Deborah MaryEarly development is a critical period in fish aquaculture and is influenced by biotic and abiotic factors (e.g., temperature, feed) that can vary significantly between hatcheries, making it difficult to identify core factors determining quality. Many of the existing larval transcriptome studies are small-scale and occur under specific rearing conditions that do not mirror the diversity of larviculture practices at an industrial level. In the present transcriptome study, gilthead seabream at the larval to juvenile transition (metamorphosis) from several hatcheries in Europe (Greece, Italy, and France) were analysed in a large-scale RNA-seq study. The aim was to uncover the most significant molecular modifications occurring during metamorphosis, irrespective of differences in biotic or abiotic factors, to address knowledge gaps associated with critical early developmental stages under industrial hatchery conditions. Commonly modified gene transcripts between larval stages were identified based on the clustering of gene expression profiles of 25 gilthead seabream libraries from different hatcheries in a PCA analysis. When larvae at flexion were compared to larvae at mid-metamorphosis, 2243 differentially expressed genes (DEGs) were identified, and when larvae at early to mid-metamorphosis were compared to mid to late-metamorphosis, 2299 DEGs were identified. Comparative analysis across the developmental stages of gilthead seabream revealed genes of importance for the metamorphic transition and adaptation to rearing conditions, including genes related to the nervous system at flexion (24 days post hatch), enteroendocrine cell differentiation, and lipid homeostasis at early to mid-metamorphosis (46 dph), and enrichment of genes indicative of immune competence at mid to late-metamorphosis (51-54 dph). The differential expression of some endocrine-associated genes, dio1, dio2, cldn1, ing4, Pou3f4, and fgf22, highlights their importance in metamorphosis. Meta-analysis of the transcriptomes from two species, the gilthead seabream and Senegalese sole, that have differing symmetry and ecology uncovered common molecular expression patterns that underlie larvae maturation during metamorphosis, and we propose that these represent core gene markers of metamorphosis in these two fish species.
- Quantitative PCR assays as a monitoring tool for bacterial genera in fresh fish filletsPublication . Pinto, Patricia IS; NAJAFPOUR, BABAK; Lima, Pedro; P. Machado; Aires, Tania; Engelen, Aschwin; Tsironi, T.; Anjos Guerreiro, Liliana Isabel Tomé; Power, Deborah MaryFresh fish fillets are a valuable but highly perishable food, and their rapid microbial deterioration is a drawback for food safety and sustainability of aquaculture, food and retail industries. Quantitative PCR (qPCR) assays based on 16S rRNA gene (16S) sequences were developed for the most abundant bacteria genera detected by metagenomics in fresh or processed fish fillets. The efficiency and specificity of six qPCR assays (for 16S of all bacteria or genera Shewanella, Pseudomonas, Carnobacterium, Janthinobacterium and Massilia) was verified using in silico predictions, cloning, sequencing and phylogenetic analyses of amplicons obtained from refrigerated control or high-pressure processed (HPP) European sea bass (Dicentrarchus labrax) fillets. In HPP sea bass fillets, significant decreases in total bacteria 16S and of Shewanella, Pseudomonas, Carnobacterium and Janthinobacterium 16S compared to control fillets were confirmed by qPCR, after 11 days of refrigerated storage. The qPCR assays were successfully applied to monitor microbial contamination during refrigerated storage of fresh fillets from commercial (retail) sea bass and gilthead sea bream (Sparus aurata). Significant increases in total bacterial and Shewanella, Pseudomonas, Carnobacterium and Janthinobacterium contamination were detected after 7-14 days. 16S copy number for total bacteria and the four target genera positively correlated with total viable counts using culture enumeration. 16S of Massilia, that is abundant in fresh fish fillets, did not significantly change during storage. The six validated qPCR assays developed are proposed as specific, sensitive, culture-independent methods for monitoring quality or processing outcomes for fish fillets during cold chain storage.
- Transcriptome datasets and histological profiles of critical larval stages in gilthead seabreamPublication . NAJAFPOUR, BABAK; Canario, Adelino; Power, Deborah MaryThe transcriptome of the seabream larvae farmed in different European commercial hatcheries was analysed during critical larval stages. The complementary data herein presented support the findings reported in the associated research article "Insights into core molecular changes associated with metamorphosis in gilthead seabream larvae across diverse hatcheries". Samples were collected from gilthead seabream ( Sparus aurata ) hatcheries in Greece (site Gr), Italy (site It), and France (site Fr). RNA was extracted from larvae with different weights, mainly at the flexion (23 and 25 dph) and mid-metamorphosis stages (43, 50, 52, 56, and 60 dph). RNAseq libraries were sequenced using Illumina HiSeq xten. The paired-end sequenced raw reads were deposited in the NCBISRA database with the accession number PRJNA956882. Differential expression and function of genes were obtained by comparing transcriptome profiles of larvae at different developmental stages.