Male Fish Research Articles

Probiotics as Potential Tool to Mitigate Nucleotide Metabolism Alterations Induced by DiNP Dietary Exposure in Danio rerio.

Diisononyl phthalate, classified as endocrine disruptor, has been investigate to trigger lipid biosynthesis in both mammalian and teleostean animal models. Despite this, little is known about the effects of DiNP exposure at tolerable daily intake level and the possible mechanisms of its toxicity. Probiotics, on the other hand, were demonstrated to have beneficial effects on the organism's metabolism and recently emerged as a possible tool to mitigate the EDC toxicity. In the present study, using a metabolomic approach, the potential hepatic sex-related toxicity of DiNP was investigated in adult zebrafish together with the mitigating action of the probiotic formulation SLAB51, which has already demonstrated its ability to ameliorate gastrointestinal pathologies in animals including humans. Zebrafish were exposed for 28 days to 50 µg/kg body weight (bw)/day of DiNP (DiNP) through their diet and treated with 109 CFU/g bw of SLAB51 (P) and the combination of DiNP and SLAB51 (DiNP + P), and the results were compared to those of an untreated control group (C). DiNP reduced AMP, IMP, and GMP in the purine metabolism, while such alterations were not observed in the DiNP + P group, for which the phenotype overlapped that of C fish. In addition, in male, DiNP reduced UMP and CMP levels in the pyrimidine metabolism, while the co-administration of probiotic shifted the DiNP + P metabolic phenotype toward that of P male and closed to C male, suggesting the beneficial effects of probiotics also in male fish. Overall, these results provide the first evidence of the disruptive actions of DiNP on hepatic nucleotide metabolism and mitigating action of the probiotic to reduce a DiNP-induced response in a sex-related manner.

Ultrasonography for non-invasive sex identification and reproductive assessment in Nile tilapia (Oreochromis niloticus).

Sex identification and the selection of monosex male tilapia are crucial for tilapia aquaculture. In this study, we evaluated the application of ultrasonography as an alternative procedure for sex identification and reproductive assessment in Nile tilapia (Oreochromis niloticus). Ultrasonography was performed on 23 fish weighing 232-1,281 g to capture longitudinal and transverse images of the ovaries and testes. Female tilapia were identified by the presence of numerous small egg granules and gray or light gray ovarian tissue and male tilapia by the homogeneous echogenicity and uniform gray tubular appearance of the testes. These distinct echogenic patterns allowed for accurate differentiation between the female and male fish. Ultrasonography achieved a 95% accuracy in sex identification, with minimal stress to the fish during the procedure, compared to manual sex sorting, which demonstrated an accuracy of 87%. Furthermore, the method facilitated the assessment of the reproductive status of the fish, including the maturation stages and fecundity potential. The use of ultrasonography offers significant advantages over traditional methods, such as animal welfare enhancements and improved breeding program efficiency. Our findings support the integration of ultrasonography into aquaculture practices and will promote sustainable and humane fish farming while optimizing reproductive management and productivity.

Effect of climatic factors on sexual maturity Labeo rohita fish

<p>This study examined the varying levels of thyroxine hormone impact (at doses of 2, 10, and 50 µg g-1 BW) as an environmentally responsive hormone on the fatty acid and sexual steroid profiles in male Labeo rohita fish. Each treatment group comprised six male fish with an average weight of 5.4 ± 0.58 kg. Blood samples were collected from male rohu fish pre-and post-injection, as well as following sperm retrieval from the caudal peduncle. Biotechnical parameters were evaluated post-fertilization. Among male breeders, the pituitary treatment and the 50 µg g-1 BW thyroxine treatment exhibited the highest levels of estradiol, testosterone, 17-alpha hydroxyprogesterone, cortisol, LH, as well as testicular protein and fat content. Whereas the lowest levels were observed in the LHRH recipient and control groups (p < 0.05). Moreover, the saturated fatty acids C16:0 and C18:0, monounsaturated fatty acids C18:1n9c and C24:1n9, along with polyunsaturated fatty acids C20:3n6 and C22:6n3 in male breeders, were found to be the predominant fatty acids in the testes under hormonal treatment. The pituitary treatment and the 50 µg g-1 BW thyroxine treatment demonstrated a greater total percentage of testicular fatty acids compared to other interventions (p < 0.05). These findings emphasize the heightened efficacy of pituitary hormone and subsequent thyroxine hormone administration at a dose of 50 µg g-1 BW, relative to lower thyroxine doses and LHRH. The aforementioned treatment can increase the levels of sex hormones that are important for sexual responsiveness, emphasizing their pivotal role in facilitating successful artificial reproduction in male Rohu breeders.</p>

Two high quality chromosome-scale genome assemblies of female and male silver pomfret (Pampus argenteus)

Pampus argenteus is a highly commercial marine fish whose population is declining sharply. Here, we generated a female P. argenteus genome, spanning 536.33 Mb with contig N50 of 1.79 Mb; 24070 genes (99.50% of 24,182) were functionally annotated. To improve quality of it, we assembled a 553.79 Mb genome of male fish with contig N50 of 24.75 Mb through HiFi and ultra-long ONT sequence technologies; 550.82 Mb were anchored onto 24 gap-free chromosomes; 22,892 genes (98.1% of 23,346) were functionally annotated; the QV value was 51.55 with 98.9% of BUSCO and 99.39% coverage of Illumina reads. Finally, we compared this genome with previous published one, revealing 37,301 SVs. 52.82 Mb and 18.05 Mb SDs were characterized in our and published assemblies, respectively, and 48.96 Mb PURs were constructed. Thus, this genome assembly exhibits excellent completeness, continuity and accuracy comparing to the published one, which can be current preferred reference genome. Overall, these works help aquaculture and wild resources recovery of P. argenteus and provide a valuable genetic resource for study.

Molecular Fish Sexing on Taisho Sanshoku Koi (Cyprinus carpio) Based on ArS.9-15 Gene Amplification using PCR Method

Taisho Sanshoku is a variant of Koi fish (Cyprinus carpio) that has high demand due to its high economic value and relatively expensive price. This study aimed to determine the sex of the Taisho Sanshoku Koi fish by molecular sexing using the PCR method to amplify the ArS.9-15 gene. This study was initiated by rearing a 4–6 month-old of 10 Taisho Sanshoku Koi fish in a fish tank with a filter and oxygen aeration. The fish were fed with fish pellets for 1–3 days. The Koi fishes were then anesthetized using Koi anesthesia containing β-hydroxyethyl phenyl ether. Each fish's peripheral blood was collected as much as 0.5 mL per fish and then stored in tubes containing Ca-EDTA anticoagulant. The genomic DNA was extracted from peripheral blood samples and used as a template DNA for PCR amplification targeting ArS.9-15 gene. Agarose with 1.5% concentration and CybrSafe staining was used in electrophoresis for visualization of the PCR results then visualized in a dark chamber using a UV transilluminator. The Taisho Sanshoku Koi fish's sex was determined using descriptive analysis based on the electrophoresis results. According to the PCR results, the female Taisho Sanshoku Koi fish only produced one 800 bp DNA band, whereas the male fish produced two 800 bp and 1,100 bp DNA bands. The outcome of molecular fish sexing of the 10 Taisho Sanshoku Koi fish reported that 60% were male and 40% were female.

Understanding sex and populational differences in spatio-temporal exploration patterns and homebase dynamics of zebrafish following repeated ethanol exposure

Ethanol (EtOH) is one of the most widely consumed substance, affecting neurobehavioral functions depending on multiple environmental and biological factors. Although EtOH modulates zebrafish (Danio rerio) anxiety-like behaviors in novelty-based paradigms, the potential role of biological sex and populational variability in the exploratory dynamics in the open field test (OFT) is unknown. Here, we explored whether a repeated EtOH exposure protocol modulates the spatio-temporal exploration and homebase-related parameters in a population- and sex-dependent manner. Male and female fish from the short-fin (SF) and leopard (LEO) phenotypes were exposed to EtOH for 7 days (1 % v/v, 20 min per day). On the 8th day, the OFT was performed to assess locomotor and exploratory behaviors. We verified significant populational differences in the baseline spatio-temporal exploration patterns, supporting a pronounced anxiety in LEO with a higher homebase index compared to SF. We also found sex-dependent differences in EtOH sensitivity, where SF was more sensitive to EtOH, especially in females, which showed marked alterations in thigmotaxis and homebase occupancy. Conversely, only LEO female subjects showed increased center occupancy following EtOH. Principal component analysis (PCA) showed the main components that explained data variability, which were sex- and population-dependent. Overall, our novel findings support the utility of zebrafish-based models to assess how EtOH influences the exploratory profile in the OFT, as well as to elucidate potential differences of sex and population in the neurobehavioral responses of alcohol exposure in a translational perspective.

Evolution: A kit for fooling your rivals

Some male swordtail fish mimic female 'pregnancy spots' to reduce aggression from rival males and gain a fitness advantage. This sexual mimicry is linked to evolutionary changes in the regulatory region of the kit-liganda gene that controls melanocyte development.

Hyperglycosylation as an Indicator of Aging in the Bone Metabolome of Oryzias latipes.

Chronological aging of bone tissues is a multi-faceted process that involves a complex interplay of cellular, biochemical, and molecular mechanisms. Metabolites play a crucial role for bone homeostasis, and a changed metabolome is indicative for bone aging, although bone metabolomics are currently understudied. The vertebral bone metabolome of the model fish Japanese medaka (Oryzias latipes) was employed to identify sex-specific markers of bone aging. 265 and 213 metabolites were differently expressed in 8-month-old vs. 3-month-old female and male fish, respectively. The untargeted metabolomics pathway enrichment analysis indicated a sex-independent increased hyperglycosylation in 8-month-old individuals. The upregulated glycosylation pathways included glycosphingolipids, glycosylphosphatidylinositol anchors, O-glycans, and N-glycans. UDP-sugars and sialic acid were found to be major drivers in regulating glycosylation pathways and metabolic flux. The data indicate a disruption of protein processing at the endoplasmic reticulum and changes in O-glycan biosynthesis. Dysregulation of glycosylation, particularly through the hexosamine biosynthetic pathway, may contribute to bone aging and age-related bone loss. The results warrant further investigation into the functional involvement of increased glycosylation in bone aging. The potential of glycan-based biomarkers as early warning systems for bone aging should be explored and would aid in an advanced understanding of the progression of bone diseases such as osteoporosis.

Effects of 17α-methyltestosterone and letrozole on growth and gonadal development in largemouth bass (Micropterus salmodies).

In order to optimize the parameters for reversing masculinization and establish the techniques for sex induction of pseudo-males and creation of all-female fry in largemouth bass (Micropterus salmodies, LMB), 15-day-old LMB (1.00 ± 0.10cm in length, 0.10 ± 0.01g in weight) were fed a diet supplemented with either 17α-methyltestosterone (MT) or letrozole (LE) and their combination. The experimental groups were M20 (20mg/kg MT), L20 (20mg/kg LE) and M10L10 (10mg/kg MT and 10mg/kg LE). The control group, named C, was not feed MT or LE. After 60 days, exogenous hormone in the diets was stopped and the effects of MT and LE on growth, male ratio, and gonadal development in LMB were evaluated. At 12-month-old, blood and gonadal tissue samples were collected to measure sex steroid hormones levels, analyze expression levels of dmrt1 and cyp19a1a genes, as well as examine the gonads morphology. The results showed no significant differences in growth between the experimental groups and the control group after a 60-day feeding period with the formulated diet (p > 0.05). The sex reversal ratio of M20, L20, M10L10 were 95.00%, 80.00%, 76.47%, respectively. The gonadal tissue sections showed that the gonadal structure of masculinized fish morphologic resembled that of control male fish. At 12-month-old, the sex reversal ratio in M20, L20, M10L10 and C groups were 100%, 86.67%, 73.33% and 50.00%, respectively. The testicular of pseudo-male fish in the M20 group exhibited well-developed morphology similarities to that of the control group males. However, the testes of pseudo-male fish in the L20 and M10L10 groups were smaller size Estradiol (E2) levels in the experimental groups was significantly lower than those in the control group females (p < 0.05), while testosterone (T) levels were significantly higher than that of the control group (p < 0.05). Compared to the female fish in the control group, pseudo-male fish from all experimental groups showed significantly upregulated expression of dmrt1 (p < 0.05), and significantly downregulated expression of cyp19a1a (p < 0.05). Pseudo-males selected from group M20 exhibited a significantly higher proportion of female offspring (92.00%) compared to the control group (46.50%). In summary, 20mg/kg MT was the optimal inducing concentration.

Molecular Cloning of the scd1 Gene and Its Expression in Response to Feeding Artificial Diets to Mandarin Fish (Siniperca chuatsi).

Background/Objectives: Stearoyl-coenzyme A desaturase 1 (SCD1) plays a crucial role in fatty acid metabolism. However, its roles in the feeding habit transformation of mandarin fish (Siniperca chuatsi) remain largely unknown. Methods: Juvenile mandarin fish (10.37 ± 0.54)g were trained to feed on an artificial diet and then divided into artificial diet feeders and nonfeeders according to their feed preference. Afterwards, the scd1 gene of mandarin fish (Sc-scd1) was identified and characterized, and its transcription difference was determined between S. chuatsi fed live artificial diets and those fed prey fish. Results: Our results show that Sc-scd1 coding sequence is 1002 bp long, encoding 333 amino acids. The assumed Sc-SCD1 protein lacks a signal peptide, and it contains 1 N-linked glycosylation site, 24 phosphorylation sites, 4 transmembrane structures, and 3 conserved histidine elements. We found that Sc-SCD1 exhibits a high similarity with its counterparts in other fish by multiple alignments and phylogenetic analysis. The expression level of Sc-scd1 was detected with different expression levels in all tested tissues between male and female individuals fed either live prey fish or artificial diets. Conclusions: In particular, the Sc-scd1 expression level was the highest in the liver of both male and female mandarin fish fed artificial diets, indicating that scd1 genes may be associated with feed adaption of mandarin fish. Taken together, our findings offer novel perspectives on the potential roles of scd1 in specific domestication, and they provide valuable genetic information on feeding habits for the domestication of mandarin fish.

Parasites of African catfish (&lt;i&gt;Clarias gariepinus&lt;/i&gt;) cultured in selected homestead ponds in Rivers State, Nigeria

Fish are a major source of protein to humans and one of the constraints to improved fish production in Nigeria are parasites/parasitic diseases. A study to evaluate the parasites of African catfish (Clarias gariepinus Burchell, 1822) cultured in selected homestead ponds in Rivers State, Nigeria was conducted from January to June, 2023. One hundred and twenty catfish were randomly selected from two homestead ponds (sixty fish per pond) and categorized (sex, weight and length); each fish was analyzed for parasites (ecto and endo) using standard parasitological techniques. Descriptive analyses (mean and percentages) were used to represent data obtained and chi-square test was used to determine the level of significance with a P&lt;0.05 considered significant. An overall parasite prevalence of 30 (25.0%) was recorded in this study (P&lt;0.05) and four parasites were observed; Ichthiphitrius 14 (11.7%), Chilodinella 6 (5.0%), Trichodina 6 (5.0%) and Crytobia 4 (3.3%). Male and female fish had parasite prevalence of 8 (16.0%) and 22 (31.4%) respectively (P&gt;0.05).According to weight, parasite prevalence values of 4 (16.0%), 4 (17.4%), 8 (28.6%), 8 (30.8%) and 6 (33.3%) were recorded for 140 – 160g, 161 – 180g, 181 – 200g, 201 – 220g and 221 – 240g respectively while according to length, parasite prevalence values of 8 (21.1%), 10 (24.4%), 7 (26.9%) and 5 (33.3%) were recorded for 20 – 22cm, 23 – 25cm, 26 – 28cm and 29 – 31cm respectively (P&gt;0.05). Proper management practices should be adhered to in aquaculture to increase yield and reduce the detrimental effects of fish parasites.

A Study on Total Mercury Content in Surface Water and Backwater Fishes of Periyar

Aquatic systems are extensively contaminated with heavy metals released due to anthropogenic activities. Mercury is one of toxic elements and its toxicity to humans has been established. The concern about mercuric pollution in the environments started with the incident of ‘Minamata’ in Japan in 1950’s. During the study period, flowing mercury electrode was used for the preparation of caustic at Travancore Cochin Chemicals Ltd (TCC), Eloor and effluents of small industries at Edayar were the sources of mercuric pollution. Surface water samples were collected from 1Km apart from TCC, near to Indian Rare Earth Ltd (IRE), Muttinakam and Mannamthuruth and fishes (male and female) were collected from this region with the help of local fishermen. This study implies the amount of mercury in aquatic system and its influence in different body components of three fishes. Total mercury content in both the samples analysed using cold vapour atomic absorption using Mercury Analyser MA-5840 and loss on mercury on heating processes (fishes) was decreased by the use of Bethge Apparatus. Fishes were Oreochromis mossambicus (Thilapia), Mugil cephalus (Mullet) and Arius arius (Cat fish) which were living in surface to near shore, middle of the river and bottom. The proximate composition (AOAC, 2000) of fishes showed that they were low fat (0.57-4.24%) with high protein content (18.4-21.96%). The total mercury content in surface water varied from 1.667- 3.334ng/ml and it was above tolerance level (1ng/ml) while in fishes followed the order A. arius&gt; M. cephalus&gt; O. mossambicus. Relatively higher concentrations of mercury were noticed in gut and liver than muscle, and also male fishes predominated over female. This study shows that mercury cycle in the habitat water did not influence to any hazardous level in these three fishes.

Evaluation of black tilapia (Oreochromis niloticus) hatchery in UPT-Perikanan Budidaya Air Tawar (PBAT) Sukorejo, Malang

Abstract Black tilapia is a freshwater fish that has become a leading commodity in the UPT-PBAT (Unit Pelayanan Teknis-Pengembangan Budidaya Air Tawar) Sukorejo Freshwater Aquaculture Fisheries with an optimal selling price. The purpose of this study was to evaluate the hatcheries activity performance in UPT-PBAT Sukorejo. The method in this research used active participation and descriptive methods. The data collection method used was from primary and secondary data. Primary data taken in this study were fertilization rate, hatching rate, and survival rate while secondary data was from literature comparison and asking directly to the staffs of UPT-PBAT Sukorejo. The results of hatchery performance showed fertilization rate of 95%, hatching rate of 98.6%, and survival rate of 93%. Hatching was carried out naturally using a 1:3 ratio (50 male fish and 150 female fish per pond). The research results indicated that hatchery activity in UPT-Freshwater Aquaculture (PBAT) Sukorejo, Malang showed good performance. However, water quality (ammonia) needs more attention to prevent negative effect in the next aquaculture cycle activity since this study found the ammonia value reached minimum tolerable value. Ammonia that exceeds the limit can cause mortality to black tilapia. Changing water is important to avoid mortality due to high ammonia content.

Exploitation and Application of a New Genetic Sex Marker Based on Intron Insertion Variation of erc2 Gene in Oplegnathus punctatus.

Spotted knifejaw (Oplegnathus punctatus), one of the most valuable mariculture species, grows with significant sexual dimorphism, with males growing significantly faster than females. O. punctatus not only has excellent growth characteristics and high food value, but also shows high economic value in aquaculture, which has become a hotspot in the field of aquaculture. The current insufficiency of sex marker identification in O. punctatus restricts the process of its unisexual breeding. Rapid identification of sex will help to study the mechanisms of sex determination and accelerate the development of sex-controlled breeding. With the completion of the sequencing of the male and female genomes of O. punctatus, the efficient and precise development of genetic sex markers has been made possible. In this study, we used genome-wide information combined with molecular biology techniques from marker sequences to further establish a rapid method for DNA insertion variant detection in the intron of O. punctatus erc2 gene, which can be used to rapidly, accurately, and efficiently identify whether DNA insertion occurs in the intron of O. punctatus erc2 gene to be detected, and to identify the sex of O. punctatus to be detected. It could also be distinguished by agarose gel electrophoresis, which would shorten the time for accurate identification and improves the detection efficiency. Homozygous comparison of male and female individuals showed that the length of the DNA fragment of the erc2 gene was 239bp on chromosome X1 and 1173bp on chromosome Y. It can therefore be inferred that a 934bp insertion fragment exists on the Y chromosome. The PCR amplification results showed that two DNA fragments of 1173bp and 239bp could be amplified in male O. punctatus, and the 1173bp fragment was a marker fragment specific to the variant intron erc2 gene, while only a single DNA fragment of 239bp was amplified in female O. punctatus. It has important significance and application value in the study of neurotransmitter transmission and environmental adaptability of female and male fish based on erc2 gene, as well as the identification of male and female sex, the preparation of high male fry, and family breeding.

Impacts of Global Warming on Quality of Male Fishes: Evidence From A Meta‐Analysis of Temperature Effects on Sperm Motility Kinematics

Impacts of Global Warming on Quality of Male Fishes: Evidence From A Meta‐Analysis of Temperature Effects on Sperm Motility Kinematics

Transcriptome analysis of four types of gonadal tissues in largemouth bass (Micropterus salmoides) to reveal its sex-related genes.

The sex determination system of largemouth bass (Micropterus salmoides, LMB) is XX/XY; however, the underlying molecular mechanisms involved in early sex differentiation, gonadal development, and exogenous hormone-induced sex reversal remain unknown. In this study, LMB at 15days post-hatching (dph) were fed diets containing 20mg/kg of 17α-methyltestosterone (17α-MT) or 30mg/kg of 17β-estradiol (17β-E2) for 60days, respectively. Serum steroid levels, histological observations of the gonads, and identification of sex-specific markers were employed to screen the gonads of 60-day-old normal female fish (XX-F), normal male fish (XY-M), 17β-E2 induced pseudo-female fish (XY-F), and 17α-MT-induced pseudo-male fish (XX-M) for transcriptome sequencing in order to uncover genes and pathway involved in the process of sexual reversal. The results from histology and serum sex steroid hormone analysis showed that both 17α-MT and 17β-E2 were capable of inducing sex reversal of LMB at 15dph. Transcriptome results revealed a total of 2,753 genes exhibiting differential expression, and the expression pattern of these genes in the gonads of XX-M or XY-F resembled that of normal females or males. The male sex-biased genes that are upregulated in XX-M and downregulated in XY-F are referred to as key genes for male reversal, while the female sex-biased genes that are upregulated in XY-F and downregulated in XX-M are referred to as key genes for female reversal. Finally, 12 differentially expressed genes (DEGs) related to male sex reversal were screened, including star2, cyp17a, cyp11b1, dmrt1, amh, sox9a, katnal1, spata4, spata6l, spata7, spata18 and foxl3. 2 DEGs (foxl2a and cyp19a1b) were found to be associated with female sex reversal. The changes in these genes collectively influence the direction of sex differentiation of LMB. Among them, star2, dmrt1 and cyp19a1b with significantly altered expression levels may play potentially crucial role in the process of gender reversal. The expression patterns of 21 randomly selected genes were verified using qRT-PCR which confirmed the reliability and accuracy of the RNA-seq results. These findings not only enhance our understanding of the molecular basis underlying sex reversal but also provide crucial data support for future breeding research on unisexual LMB.

Chromosome-level genome assemblies of vulnerable male and female elongate loach (Leptobotia elongata)

Endemic to the upper and middle reaches of the Yangtze River in China, elongate loach (Leptobotia elongata) has become a vulnerable species mainly due to overfishing and habitat destruction. Thus far, no genome data of this species are reported. As a result, lacking of such genomic information has restricted practical conservation and utilization of this economic fish. Here, we constructed chromosome-level genome assemblies for both male and female elongate loach by integration of MGI, PacBio HiFi and Hi-C sequencing technologies. Two primary genome assemblies (586-Mb and 589-Mb) were obtained for female and male fishes, respectively. Indeed, 98.22% and 98.61% of the contig sequences were anchored onto 25 chromosomes, with identification of 26.22% and 25.92% repeat contents in both assembled genomes. Meanwhile, a total of 25,215 and 25,253 protein-coding genes were annotated, of which 97.41% and 98.8% could be predicted with functions. Taken together, our genome data presented here provide a valuable genomic resource for in-depth evolutionary and functional research, as well as molecular breeding and conservation of this economic fish species.

Proteomic analysis revealed gender-related differences in the skin mucus proteome of discus fish (Symphysodon haraldi) during the parental and non-parental care periods

The discus fish, Symphysodon spp., a South American cichlid, has a unique parental care behavior where fry bite on parental skin mucus after hatching. In this study, we used LC-MS/MS technique to compare the skin mucus proteome composition of male or female discus fish during parental and non-parental care periods. By multivariate statistical analysis, we found clear separations between different periods and between different sexes of mucus proteome. Compared with non-parental female fish, parental female fish had 283 up-regulated and 235 down-regulated expressed proteins. Compared with non-parental male fish, parental male fish had 169 up-regulated and 120 down-regulated expressed proteins. The differentially expressed proteins for male fish were enriched in sulfur relay system, mucin type O-glycan biosynthesis and antigen processing and presentation pathways, while those for female fish were enriched in sulfur relay system, steroid biosynthesis and complement and coagulation cascades pathways. During the parental care, both male and female discus showed an enhanced lipid metabolism, producing more phospholipids and cholesterol. The difference is that male discus had increased tricarboxylic acid cycle producing more energy during the parental care, while females produced more nucleotides especially guanylic acid. Our study could provide new insights into the understanding of the unique mucus supply behavior of discus fish based on proteomic change.

Polystyrene nanoplastics alter intestinal toxicity of 2,4-DTBP in a sex-dependent manner in zebrafish (Danio rerio)

Nanoplastics (NPs) and 2,4-di-tert-butylphenol (2,4-DTBP) are ubiquitous emerging environmental contaminants detected in aquatic environment. While the intestinal toxicity of 2,4-DTBP alone has been studied, its combined effects with NPs remain unclear. Herein, adult zebrafish were exposed to 80 nm polystyrene nanoplastics (PS-NPs) or/ and 2,4-DTBP for 28 days. With co-exposure of PS-NPs, impact of 2,4-DTBP on feeding capacity and intestinal histopathology was enhanced in males while attenuated in females. Addition of PS-NPs significantly decreased the uptake of 2,4-DTBP in females, while the intestinal concentrations of 2,4-DTBP were not different between the sexes in co-exposure groups. Furthermore, lower intestinal pH and higher contents of digestive enzymes were detected in male fish, while bile acid was significantly increased in co-exposed females. In addition, co-exposure of PS-NPs stimulated female fish to remodel microbial composition to potentially enhance xenobiotics degradation, while negative Aeromonas aggravated inflammation in males. These results indicated that in the presence of PS-NPs, the gut microenvironment in females can facilitate the detoxification of 2,4-DTBP, while exaggerating toxiciy in males. Overall, this study demonstrates that toxicological outcomes of NPs-chemical mixtures may be modified by sex-specific physiology and microbiota composition, furthering understanding for environmental risk assessment and management of aquatic environments.

PERTUMBUHAN DAN KEMATANGAN GONAD IKAN WAKONG MERAH (Caesio chrysozona) DI KEPULAUAN BANDA

The fusilier fish (Caesio chrysozona) is an abundant fish resource that contributes to the economy of the Banda Islands community. This study aims to examine the growth, gonad maturity level (GML), and gonad maturity index (GMI) of the red fusilier fish landed on the coast of Kampung Baru Village, Banda District, Central Maluku. The study was conducted from July to August 2023. A total of 40 fish were collected, measured for their total length, and weighed for their body weight. After that, the fish were dissected for gonad observation, which was then weighed and determined for gonad maturity levels. The results showed that out of 40 fish, there were 14 male and 26 female fish. The length of the fish ranged from 18 to 24 cm, with body weights for females between 83 and 220 grams, and for males between 79 and 171 grams. The length-weight relationship analysis showed a (b) value for female fish of 3.664 with an ( R2) value of 0.834, while male fish had a (b) value of 1.446 with an (R2) value of 0.273. The length-weight relationship equations for female fish is (W=0.0018 L{3.664}), and for male fish (W=1.7876 L{1.446}). The gonad maturity level (GML) was dominated by GML II for both genders. The gonad maturity index (GMI) varied each month during the study, with the highest GMI for males reaching 3.10% and the lowest at 0.25%, while the highest GMI for females was 2.562% and the lowest was 0.091%.