This work investigated the peptide profile of skin secretion from Lithobates palmipes collected from the Brazilian Atlantic Forest. The secretion was submitted to reversed phase high-performance liquid chromatography (RP-HPLC) and the fractions were screened for antibacterial activity. RP-HPLC resulted in the separation of several peaks, among which 10 showed antibacterial activity and contained peptides of the ranatuerin, brevinin and temporin families. Fraction 6 was resubmitted to RP-HPLC and a novel peptide from temporin family (temporin-PMb) had its primary structure determined. Temporin-PMb and non-amidated temporin-PMb were synthesized, purified, and evaluated for antibacterial activity, hemolytic activity and cytotoxicity to keratinocytes and cancer cells. Temporin-PMb was active against Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa as well as against methicilin-resistant S. aureus (MRSA) and Acinetobacter baumannii. It was cytotoxic to human cervical adenocarcinoma cells (HeLa) and human mammary adenocarcinoma cells (MCF7) with IC of 32.4 and 24.1 μM, respectively. It was also toxic to human keratinocytes (HaCaT; IC of 25.0 μM) and showed hemolytic activity. The non-amidated form showed low hemolytic activity and lower HaCaT toxicity, but was only effective against E. coli, S. aureus MRSA, and A. baumanii. In conclusion, Atlantic Forest L. palmipes skin secretion contained different bioactive peptides, including a novel temporin with antibacterial effect and cytotoxicity towards human cancer cells. The amide group was responsible for the activities of the wild-type temporin-PMb. Peptide engineering studies are encouraged aiming at minimizing unwanted effects.

Air exposure is a common stressor for Chinese mitten crab (Eriocheir sinensis) during rearing and transport, and air exposure tolerance can serve as a crucial indicator for assessing the quality of juvenile E. sinensis. In this study, juvenile E. sinensis were divided into two groups based on their behavioral responses: Group S, which exhibited strong tolerance to air exposure, and Group W, which exhibited weak tolerance. Immersed crabs, not exposed to air, served as a control group (Group C). Whole body morphological characteristics and enzyme activities related to respiratory metabolism in the hemolymph and anterior gills were compared among the three groups. Non-targeted LC-MS metabolomic analysis was conducted on anterior gills. The results showed that, independent of developmental stage, crabs that were larger and had higher condition factor were more tolerant to air exposure. Additionally, compared to Group W, air exposure had a relatively small effect on glycolysis and anaerobic respiratory metabolic processes in the hemolymph and anterior gills of Group S. In response to air exposure, E. sinensis experienced increased energy demand, and switched from aerobic to anaerobic respiration to increase energy supply. Simultaneously, air exposure induced oxidative stress in the hemolymph and anterior gills. This study enhances our understanding of the response mechanism of E. sinensis to air exposure and provides a theoretical reference for the identification of high-quality juvenile E. sinensis.

MicroRNAs (miRNAs) are known to regulate gene expression and play a role in body color formation in fish. However, the molecular mechanisms underlying miRNA involvement in the body color of leopard coral grouper (Plectropomus leopardus) remain largely unexplored. In this study, we investigated the expression levels of miR-2188 in red and black P. leopardus (pl-miR-2188) and found significantly higher expression levels in red fish samples compared to those in black fish samples. Silencing pl-miR-2188 in vivo using a pl-miR-2188 antagomir resulted in increased melanin concentration. Following pl-miR-2188 silencing, the expression levels of melanin-related genes, such as tyrosinase (tyr), TYR-related protein 1 (tyrp1-1 and tyrp1-2) and TYR-related protein 2 (tyrp2), and microphthalmia-associated transcription factor (mitf), were elevated. RNAhybrid predictions and dual-luciferase reporter assays identified sox5 as a target mRNA of pl-miR-2188. Following pl-miR-2188 antagomir injection, sox5 expression was significantly upregulated in the injection group compared to that in control groups (P < 0.05). These results suggest that pl-miR-2188 may regulate melanin synthesis in P. leopardus by targeting sox5. This study provides new insights into the miRNA-mRNA interactions involved in melanin synthesis and body color formation in the leopard coral grouper.

Due to its depletion in natural settings, the potential for aquaculture of the cnidarian Anemonia viridis is currently attracting research interest. Knowledge about the physiology of this species is necessary to ensure optimal development of, and well-being in, aquaculture. This study tested the effects of different abiotic (limited sunlight, brackish water) and biotic (integrated multitrophic aquaculture or IMTA) conditions on A. viridis in captivity. Growth and reproduction were measured, and antioxidant status was evaluated in tentacular and columnar tissues as antioxidant enzymatic activity (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glucose 6-phosphate dehydrogenase, glutathione S-transferase and DT-diaphorase), Trolox-equivalent antioxidant capacity (TEAC) and tissue lipid peroxidation (MDA). Animals in the brackish water and IMTA treatments displayed significant changes in glutathione peroxidase, glucose 6-phospate dehydrogenase and TEAC compared to control anemones, with these effects noted primarily in columnar tissue. These results support the relevance of enzymatic pathways involving glutathione as antioxidant mechanisms under osmotic disturbances or ecological interactions. Limited light intensity was not found to be detrimental to the oxidative status of the anemones, despite A. viridis harbouring photosynthetic symbionts, and enhanced growth performance parameters suggested a higher individual weight increase than in control conditions. Lipid peroxidation was not significantly affected in any experimental condition. Principal Component Analysis (PCA) suggested that similar antioxidant status parameters can correlate positively (tentacular parameters) or negatively (columnar parameters) with MDA concentration. In conclusion, aquaculture of Anemonia viridis can be improved under suitable environmental conditions supported by the evaluation of welfare markers based on antioxidant status.

Cyclic hibernation bouts in Daurian ground squirrels (Spermophilus dauricus) lead to repeated suppression and recovery of mitochondrial respiratory function across multiple organs, potentially impacting reactive oxygen species (ROS) dynamics. The Harderian gland (HG) plays an important role in endocrine regulation through porphyrin secretion. However, the influence of hibernation on oxidative pressure and associated antioxidant pathways in the HG remains inadequately understood. In the current study, we investigated the morphological changes, secretory activity, ROS levels, and underlying mechanisms in the HG of Daurian ground squirrels at distinct circannual stages of hibernation. Results indicated that: (1) Protoporphyrin levels in the HG increased during hibernation compared to the summer active (SA) phase, with a reduction in acinar lumen during torpor, potentially related to hibernation in a low-light environment. (2) Hydrogen peroxide (HO) and malondialdehyde (MDA) content during hibernation and post-hibernation (POST) did not exceed the levels observed in SA, indicating that the HG effectively mitigated oxidative pressure and lipid peroxidation during these periods. (3) Superoxide dismutase (SOD) activity increased while glutathione peroxidase (GPx) activity decreased during Inter-bout arousal (IBA) compared to both SA and torpor, although total antioxidant capacity (T-AOC) remained stable across all stages. (4) Overall fluorescent intensity of nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) was significantly lower than in SA. These findings demonstrate that the HG in Daurian ground squirrels maintains a favorable oxidative status through the regulation of antioxidant enzyme activities during hibernation and even post-hibernation.

A model of protein digestion and peptide and amino acid absorption along the midgut of Musca domestica larvae was proposed and supported by RNA-Seq analyses, protein bioinformatics, microvillar-membrane-enriched midgut proteomics, and enzymatic activities. Peptidase genes are highly expressed in the posterior midgut (PM), whereas those for cathepsins have expression limited to the middle midgut (MM). MM has the lowest levels of gene expression of almost all peptidases but has high expression of genes for membrane-bound serine endopeptidases. The anterior midgut (AM) has intermediate expression values of serine endopeptidase and aminopeptidase (AP) genes and low expression of carboxypeptidases (CPs). Gene expression and peptidase activities were usually consistent for putative intracellular and membrane-bound enzymes. However, secreted peptidase gene expression and activities have divergent values, especially in the PM, which may be due to the countercurrent water flux causing enzyme recycling, thus decreasing their excretion. Data suggest that Trys and APs act in the AM. In the acidic MM, lysozymes kill microorganisms found in the diet, releasing proteins digested by cathepsins D, which may also digest Trys coming from the AM. Finally, highly active serine endopeptidases, CPs, dipeptidases, and APs complete protein digestion in PM. Absorption of peptides and amino acids coupled to protons may occur along the midgut, especially in PM, as occurs for facilitated amino acid transport. Absorption with sodium ions is probably restricted to AM and PM. Our findings provide valuable insights into the protein digestion and amino acid absorption mechanism in M. domestica larvae.

Glucocorticoids (GCs) are well-established anti-inflammatory agents, with cortisol, an endogenous GC, exerting pivotal regulatory effects on normal physiological processes. However, the immune regulatory role of cortisol in teleost fish, particularly in inflammation induced by pathogenic infection, remains largely unexplored. Here, we revealed that lipopolysaccharide (LPS) triggers a pro-inflammatory response in the large yellow croaker (Larimichthys crocea), as evidenced by increased expression of key pro-inflammatory cytokines and activation of the mitogen-activated protein kinase (MAPK) signaling pathway. We further explored the immunosuppressive capacity of cortisol in LPS-stimulated large yellow croaker kidney cells (PCK cells) and in vitro tissues of the large yellow croaker. Our findings indicated that cortisol effectively suppresses LPS-induced overexpression of pro-inflammatory cytokines and p38 MAPK pathway activation. Moreover, the immunosuppressive effects of cortisol were reversed by pretreatment with mifepristone, a glucocorticoid receptor (GR) antagonist. Collectively, this study delineated the inhibitory role of cortisol in the LPS-induced inflammatory cascade in large yellow croaker and underscores the significance of GR in mediating this response. These insights advance our comprehension of GCs-mediated immune modulation and provide a theoretical basis for the application of cortisol in disease prevention and the selective breeding of disease-resistant traits in aquaculture.

Visceral adipose tissue (VAT) is the primary fat reservoir and energy source in fish. Other relevant fat depots include subcutaneous adipose tissue (SAT), located under epithelial layers, and intramuscular adipose tissue (IMAT), found between the myotomes. The present study investigates the morphological, gene expression and functional characteristics of these different depots in rainbow trout (Oncorhynchus mykiss). Commercial rainbow trout of two different average weights were sampled for histology, lipid quantification and fatty acids profile. Mature adipocytes were isolated for gene expression analyses of lipid metabolic markers. Both VAT and SAT showed large adipocytes, and high total lipid content, suggesting hypertrophic growth. Adipocytes in IMAT were consistently smaller regardless of fish size. While fatty acid composition was similar across depots, SAT had lower levels of palmitic acid and higher levels of polyunsaturated fatty acids that act as precursors of phospholipids and eicosanoids such as eicosapentaenoic acid, compared to VAT and IMAT. Gene expression analyses revealed higher levels of fatty acid transporters, lipolysis and β-oxidation markers in VAT and SAT compared to IMAT, suggesting a more active lipid metabolism. These data support the role of VAT as the main energy depot, while SAT may act as a secondary reservoir, and IMAT potentially serves as an occasional energy source for muscles. This study provides valuable insights into the distinct properties of the different fat depots in fish, which may help to optimize strategies to modulate adiposity for improved health, metabolism, and product quality.

The whiteleg marine shrimp Penaeus vannamei, originally from the Eastern Pacific Ocean, now inhabits tropical waters across Asia and Central and Southern America. This benthic species exhibits rapid growth, wide salinity and temperature tolerance, and disease resistance. These physiological traits have led to extensive research on its osmoregulatory mechanisms, including next-generation sequencing, transcriptomic analyses, and lipidomic responses. In crustaceans, osmotic and ionic homeostasis is primarily maintained by the membrane-bound metalloenzyme (Na, K)-ATPase. However, little is known about how various ligands modulate this enzyme in P. vannamei. Here, we examined the kinetic characteristics of the gill (Na, K)-ATPase to get biochemical insights into its modulation. A prominent immunoreactive band of ~120 kDa, corresponding to the (Na, K)-ATPase alpha-subunit, was identified. The enzyme exhibited two ATP hydrolyzing sites with K = 0.0003 ± 0.00002 and 0.05 ± 0.003 mmol L and was stimulated by low sodium ion concentrations. Potassium and ammonium ions also stimulated enzyme activity with similar K values of 0.08 ± 0.004 and 0.06 ± 0.003 mmol L, respectively. Ouabain inhibition profile suggested a single enzyme isoform with a K value of 2.10 ± 0.16 mmol L. Our findings showed significant kinetic differences in the (Na, K)-ATPase in Penaeus vannamei compared to marine and freshwater crustaceans. We expect our results to enhance understanding of the modulation of gill (Na, K)-ATPase in Penaeus vannamei and to provide a valuable tool for studying the shrimp's biochemical acclimation to varying salinity conditions.

Water temperature is an abiotic factor influencing fish metabolism and physiological responses. As poikilothermic creatures, fish are notable sensitivity to fluctuations in water temperature, which also significantly influences intestinal microbial proliferation. This study aimed to investigate the impact of both low (8 °C) and high (28 °C) water temperatures on oxidative stress and the intestinal microbiota of Chromis notata, a species that has recently migrated northward owing to changes in sea water temperature. Laboratory experiments were conducted to assess changes in superoxide dismutase (SOD), catalase (CAT), and lysozyme activities, as well as changes in the abundance and diversity of intestinal microbiota. The activities of antioxidant enzymes, specifically SOD and CAT, in C. notata exposed to low and high temperatures, showed an increase compared to the control group (maintained at 18 °C). Moreover, liver HO levels exhibited a significant increase over time. Conversely, plasma lysozyme activity significantly decreased in groups subjected to low and high water temperatures compared to the control group. Analyzing changes in the intestinal microbiota, we observed an increase in the proportion of Firmicutes but a decrease in Proteobacteria, which are known for their role in immune enhancement, in C. notata exposed to both low and high water temperatures. We propose that alterations in water temperature impact the antioxidant enzyme activity of C. notata, leading to compromised immune responses and disruption of the biological balance of the intestinal microbiota, potentially affecting the host's survival.

Mitochondria play a critical role in follicular development and ovulation, at least in part through the actions of growth hormone (GH)/insulin-like growth factor-1 (IGF-1) on mitochondrial biogenesis. This study aimed to identify seasonal alterations in the GH/IGF-1 system and mitochondrial biogenesis in muskrat (Ondatra zibethicus) ovaries. We utilized the muskrat, a typical seasonal breeder, to clarify the potential impact of the GH/IGF-1 system on mitochondrial biogenesis across different breeding seasons using immunohistochemistry, gene expression and high-throughput sequencing. Alterations in follicular development existed in muskrat ovaries between the breeding season (BS) and non-breeding season (NBS), accompanied by a striking decrease in circulating and ovarian GH and IGF-1 concentrations. GH, GHR, IGF-1, IGF-1R, and mitochondrial biogenesis markers were localized in the ovarian cells of muskrats during both seasons. In contrast, Gh, Ghr, Igf-1, Igf-1r, Ppargc1a, Ppargc1b, Tfam, and Nrf1/2 mRNA levels were higher in BS. The relative levels of GH and IGF-1 in circulation and ovaries were positively associated with mitochondrial biogenesis markers. Additionally, RNA-seq analysis demonstrated that differentially expressed genes might be associated with insulin and PI3K/Akt signaling pathways, as well as mitochondrial function-related pathways. These findings suggest that the intra-ovarian GH/IGF-1 system, which is associated with seasonal changes in mitochondrial biogenesis, is activated in muskrat ovaries in BS.

In many vertebrates, dietary yellow carotenoids are enzymatically transformed into 4C-ketocarotenoid pigments, leading to conspicuous red colourations. These colourations may evolve as signals of individual quality under sexual selection. To evolve as signals, they must transmit reliable information benefiting both the receiver and the signaler. Some argue that the reliability of 4C-ketocarotenoid-based colourations is ensured by the tight link between individual quality and mitochondrial metabolism, which is supposedly involved in transforming yellow carotenoids. We studied how a range of carotenoids covary in the feathers and blood plasma of a large number (n > 140) of wild male common crossbills (Loxia curvirostra). Plumage redness was mainly due to 3-hydroxy-echinenone (3HOE). Two other, less abundant, red 4C-ketocarotenoids (astaxanthin and canthaxanthin) could have contributed to feather colour as they are redder pigments. This was demonstrated for astaxanthin but not canthaxanthin, whose feather levels were clearly uncorrelated to colouration. Moreover, moulting crossbills carried more 3HOE and astaxanthin in blood than non-moulting ones, whereas canthaxanthin did not differ. Canthaxanthin and 3HOE can be formed from echinenone, a probable product of dietary β-carotene ketolation. Echinenone could thus be ketolated or hydroxylated to produce canthaxanthin or 3HOE, respectively. In moulting birds, 3HOE blood levels positively correlated to astaxanthin, its product, but negatively to canthaxanthin levels. Redder crossbills also had lower plasma canthaxanthin values. A decrease in hydroxylation relative to ketolation could explain canthaxanthin production. We hypothesize that red colouration could indicate birds' ability to avoid inefficient deviations within the complex enzymatic pathways.

The hake fishery plays a crucial role due to its significant economic impact. The genus Merluccius includes 12 extant species found along the coasts of the Americas, Europe, and Africa. However, research on their digestive physiology and the enzymes involved in digestion, including proteases, remains limited. Proteases play a key role in protein digestion, a vital process for all living organisms. This study focused on screening the genomes of eight Merluccius spp. for eight specific proteases previously identified in Merluccius polli. Additionally, the study conducted biochemical analyses of proteases found in the stomach and intestine of Pacific whiting fish (Merluccius productus), comparing the results with the genomic findings. The analysis revealed that proteases across Merluccius spp. are conserved, although with slight variations, particularly in chymotrypsin and aspartic proteases. Biochemical characterization of M. productus identified at least three main proteases in the stomach, active at acidic pH, and at least seven proteases in the intestine, active at alkaline pH, as determined by electrophoresis. Further investigation, including specific inhibition studies, determination of molecular mass, and assessment of pH and temperature preferences for catalysis, revealed that one of the stomach proteases functioning at acidic pH likely belongs to the acid peptidase class, likely pepsin. Similarly, analysis of proteases active at alkaline pH indicated the presence of a chymotrypsin and a trypsin, consistent with genomic findings in M. productus. These results are important as they provide insights into the digestive physiology of Merluccius spp., contributing to a better understanding of their nutritional needs.

The present experiment evaluated whether dietary protein (P) or lipid (L) is preferred as an energy source by genetically improved farmed tilapia (GIFT) reared at high temperatures. A 60-day feeding trial was conducted at 28.3 °C and 33.3 °C, testing five diets with varying protein (34,36,38 %) and lipid (8,10,12 %) levels, viz., PL, PL, PL, PL, PL. Parameters assessed included growth, body composition, serum lipids, enzyme activities, fatty acid profiles, and PPAR-α mRNA expression. Results indicated that the fish fed optimum protein and highest lipid level (PL) showed significantly higher (P < 0.05) weight gain percent and thermal growth coefficient. Increasing dietary lipid content reduced whole-body lipid deposition and mobilised serum triglycerides and cholesterol at higher temperatures (HT). Hepatic malic enzyme activity decreased with rising temperature and lipid content, while lipoprotein lipase activity in muscle increased. The fatty acid composition altered substantially with the changes in rearing temperature and diets. Unsaturated fats were preferred as direct fuels for β-oxidation, wherein the PL groups preserved body (area %) EPA, DHA, and linolenic acid, especially at HT. The expression of PPAR-α, a lipolytic marker, was upregulated with increasing temperature and high dietary lipid content, peaking in PL groups. The study concludes that high-lipid diets (12 %) are metabolically superior to high-protein diets for GIFT tilapia at elevated temperatures, optimising growth, enhancing metabolic efficiency, and maintaining essential fatty acid profiles under hyperthermal stress.

Calcifying organisms are suffering from negative impacts induced by climate change, such as CO-induced acidification, which may impair external calcified structures. Freshwater mollusks have the potential to suffer more from CO-induced acidification than marine calcifiers due to the lower buffering capacity of many freshwater systems. One of the most important enzymes contributing to the biomineralization reaction is carbonic anhydrase (CA), which catalyzes the reversible conversion of CO to bicarbonate, the major carbon source of the calcareous structure in calcifiers. In this study we characterized two α-CA isoforms (LsCA1 and LsCA4) from the freshwater snail Lymnaea stagnalis using a combination of gene sequencing, gene expression, phylogenetic analysis and biochemical assays. Both CA isoforms demonstrated high expression levels in the mantle tissue, the major site for biomineralization. Furthermore, expression of LsCA4 during development parallels shell formation. The primary protein structure analysis, active site configuration and the catalytic activity of LsCA4 together suggest that the LsCA4 is embedded in the apical and basolateral membranes of mantle cells; while LsCA1 is proposed to be cytosolic and might play an important role in acid-base regulation. These findings of LsCA isoforms form a strong basis for a more detailed physiological understanding of the effects of elevated CO on calcification in freshwater mollusks.

In this study, we isolated a novel lectin from the marine sponge Aiolochroia crassa, named AcrL. The lectin showed a preference for glycans containing sialic acid terminal residues, as indicated by the strongest inhibition with fetuin and bovine submaxillary mucin. Primary structure determination by mass spectrometry revealed that AcrL is a galectin with conserved amino acid residues typically involved in carbohydrate binding. Structural modeling indicated that AcrL adopts a typical galectin β-sandwich motif, featuring two anti-parallel β-sheets with five strands each. Docking calculations revealed a carbohydrate-binding site composed of a main site, capable of hosting galactopyranosides, and an extended site, facilitating the binding of complex carbohydrates. AcrL inhibited significant biofilm formation against Staphylococcus aureus, S. epidermidis, and Escherichia coli with concentrations ranging from 500 to 15.6 μg.mL for S. aureus, 7.8 μg.mL for S. epidermidis, and 500 μg.mL for E. coli. Furthermore, when combined with different antibiotics, AcrL potentiated their effect against pathogenic bacteria. The antimicrobial mechanism of AcrL was investigated using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The analysis indicates that AcrL induces damage to the bacterial membrane. These findings underscore the discovery of a novel galectin in a basal organism and the comprehensive biochemical characterization conducted in this research, highlighting the potential of AcrL as a novel antibacterial agent and emphasizing its importance in combating bacterial infections.

In this study, the effect of the Streptomyces misakiensis metabolite (α- sitosterol, 0, 20, 40, 60, and 80 mg/kg) dietary supplementation on growth performance, antioxidant-immune stability and Candida albicans resistance of Nile tilapia was evaluated. The results revealed that the incorporation of α-sitosterol at doses of 60 and 80 mg/kg into the diet significantly improved the growth rate of Nile tilapia. The fish receiving 80 mg/kg showed an increased level of high-density lipoprotein, total protein, globulin, and albumin, and significantly reduced levels of indicators of hepato-renal damage, glucose, triglycerides, low-density lipoprotein, and total cholesterol. Dietary α-sitosterol induced a considerable increase in hepatopancreas glutathione peroxidase, superoxide dismutase and catalase activities and a significant drop in malondialdehyde levels. Supplementing the diet with 80 mg/kg of α-sitosterol increased nitric oxide, complement-3, nitro blue tetrazolium levels, lysozyme, and phagocytic activities. In particular, supplementing with α-sitosterol at 60-80 mg/kg of diet significantly enhanced the expression of pro/anti-inflammatory markers (il1b, il10, tgfb, ifng, tnfa and il8) after the C. albicans challenge. Also, there was a decrease in cumulative mortality percent, pro-apoptotic markers (casp3, bax and hsp70) and an increase in anti-apoptotic indicators (bcl2). Interestingly, following the C. albicans challenge, fish that received 0 and 20 mg α-sitosterol/kg exhibited significant inflammation in the hepatopancreas, spleen, and intestine. On the other hand, inflammation could be alleviated by feeding 60-80 mg α-sitosterol/kg. Due to these findings, α-sitosterol could be an innovative option to enhance growth, general physiological status, immune service, and antifungal resistance of Nile tilapia against C. albicans.

Environmental RNA (eRNA) is an emerging technique with significant potential for the assessment of organismal function in field settings. It has the advantage of being non-invasive, facilitating insight into the physiological status of an organism without complications associated with processes such as capture, handling, and transportation from the field to the laboratory. It is hypothesised that eRNA approaches will be especially valuable for assessing sublethal stress of species living in environmental settings undergoing change and could therefore be integral for examining population health and for testing hypotheses regarding organismal physiology developed from laboratory studies. However, the successful application of eRNA approaches requires further data regarding the stability and persistence of eRNA in natural substrates; established and validated relationships between molecular biomarkers and the physiological processes they participate in; and an understanding of the contributions of different epithelia in direct contact with the environment (skin, gill, gut) to the eRNA transcriptome. The utility of microRNA as a component of the eRNA pool should be an area of specific future research focus. Ultimately, eRNA has the potential to provide fundamental physiological information regarding the responses of organisms in their natural settings and could increase the sensitivity and acuity of biomonitoring efforts.

This study assesses the effects of a prebiotic derived from Morinda citrifolia (noni fruit) extract and a probiotic of Lactobacillus plantarum CMT1 alone and in combination on the survival, growth performance, digestive enzymes, and disease resistance of whiteleg shrimp. A total of 1200 juvenile shrimp were randomly allocated to four treatments: control (not supplemented with noni fruit extract or L. plantarum CMT1), Treatment 1 (TRT1) (supplemented with 1 % noni fruit extract), Treatment 2 (TRT2) (supplemented with 10 CFU/kg L. plantarum CMT1), and Treatment 3 (TRT3) (supplemented with 1 % noni fruit extract and 10 CFU/kg L. plantarum CMT1). After 56 days of feeding, the growth indices of the TRT3 group were statistically larger than the other treatments (P < 0.05). Shrimp in the three treatment groups demonstrated significantly enhanced survival compared to those in the control group (P < 0.05), but no significant differences were observed among these three groups (P > 0.05). Shrimp fed the TRT3 diet had the lowest feed conversion rate, which was statistically significant compared to the other groups. Shrimp in the TRT3 group also had significantly higher amylase and protease levels than the control group. In addition, the use of fruit extract or L.plantarum CMT1 alone and in combination significantly increased shrimp survival after exposure to Vibrio parahaemolyticus, with the TRT3 group recording the highest value. The results indicate that a synbiotic of M. citrifolia extract and L.plantarum CMT1 could be used in shrimp aquaculture to promote animal development and health.

"Pinhead" is an abnormal condition of farmed fish which is rarely studied, albeit well known among fish culturists, and is characterized by extreme emaciation and anorexia. In this study, the potential impacts of pinhead condition in milkfish were analyzed and compared to fed, healthy, and a group starved for four weeks. The condition factor and hepatosomatic index of pinhead milkfish were significantly lower compared with fed, healthy individuals. Abnormal plasma osmolality and muscle water content in pinhead milkfish indicated an imbalance in their internal water content. The anorexigenic hormone, leptin A was highly expressed in liver of pinhead milkfish, which could be related to their lack of appetite. Meanwhile, the hepatosomatic index, intestinal somatic index, enterocyte height, number of villi and goblet cells, Na/K- ATPase activity, and intestinal protein content of the pinhead milkfish were similar to those of the 4-week starved individuals. Taken together, our results characterized key physiological parameters of pinhead milkfish for the first time. Further investigation is required to understand how environmental or artificial stress can lead to the occurrence of pinhead milkfish, and to develop methods for alleviating this condition.

This study assessed the impact of dietary Chlorella sp. and Schizochytrium sp. extracts on growth performance, feed utilization, body composition, and gene expression related to growth, digestion, antioxidant defense, and immune response in rainbow trout (Oncorhynchus mykiss). A total of 180 fish (average weight 8.92 ± 0.04 g) were randomly distributed into 12 fiberglass tanks (400 L, 15 fish per tank, three replicates per treatment). Fish were divided into four dietary groups for 60 days: 0 % (Control), 0.5 % Chlorella sp. extract (CH), 0.5 % Schizochytrium sp. extract (SC), and a combined 0.25 % Chlorella sp. and 0.25 % Schizochytrium sp. (CH + SC). At trial end, fish in the CH + SC group had a final weight (FW) of 27.06 ± 0.28 g, significantly higher than other groups (P < 0.05), with improved growth parameters (P < 0.05). While body composition showed no differences in moisture, lipid, or ash content, crude protein was significantly higher in CH + SC (P < 0.05). Gene expression analysis showed upregulation of the growth hormone GH-I gene in the CH + SC group (P < 0.05). Genes related to digestive enzymes (trypsin, lipase, amylase) were also upregulated in all microalgae groups, with the highest levels in CH + SC (P < 0.05). Additionally, antioxidant genes (SOD, CAT, GPx) and immune-related genes (LYZII, TNF-α, IL-1β) showed elevated expression in CH + SC (P < 0.05). This study demonstrated that a diet containing Chlorella sp. and Schizochytrium sp. extracts supports growth, enhances nutrient utilization, and upregulates genes related to antioxidant and immune function in rainbow trout. Further research is recommended to assess functional immune responses and enzyme activities to confirm these physiological effects.