Expression analysis of Sox9 genes during annual reproductive cycles in gonads and after nanodelivery of LHRH in Clarias batrachus

Ovary of Zebrafish during Spawning Season: Ultrastructure and Immunohistochemical Profiles of Sox9 and Myostatin

This study sought to examine the ovarian cellular and stromal components of the zebrafish (Danio rerio) throughout the spawning season using light and electron microscopic tools. The ovaries of zebrafish showed oocytes in all stages of follicular development and degeneration (atresia). Six stages of oogenesis were demonstrated: oogonia, early oocytes, late oocytes, vacuolated follicles, the yolk globule stage (vitellogenesis), and mature follicles. The SOX9 protein was expressed in the ooplasm of the primary and previtellogenic oocytes and the theca cell layer of the mature follicles. Myostatin was expressed in the granulosa and theca cells. Many stem cells in the ovarian stroma expressed myostatin and SOX9. During the spawning season, the EM results indicated that the zona radiata increased in thickness and was crossed perpendicularly by pore canals that contained processes from both oocytes and zona granulosa. The granulosa cells contained many mitochondria, rER, sER, and vesicles. Meanwhile, the thecal layer consisted of fibroblast-like cells. Atretic follicles could be demonstrated that involved both oocytes and their follicular walls. Several types of cells were distinguished in the ovarian stroma, including mast cells, telocytes, lymphocytes, fibroblasts, endocrine cells, macrophages, adipocytes, dendritic cells, and steroidogenic (stromal) cells. The ovary of the zebrafish serves as a model to investigate follicular development.

CT, Kumar P, Babu P. G, Walke P, Nayak SK, Sharma R. Teleost Nonapeptides, Isotocin and Vasotocin Administration Released the Milt by Abdominal Massage in Male Catfish, Clarias magur

In the present work the nonapeptides i.e., isotocin and vasotocin alone or in a combination were tested in C. magur to evaluate their effect on stripping by abdominal massage. Also, we used chitosan-carbon nanotube nanocomposites to conjugate the nonapetides isotocin (abbreviated as COOH-SWCNTCSPeP) and isotocin and vasotocin (COOH-SWCNTCSPePs) with the aim of sustaining the effect for a longer duration. The conjugation of nonapeptides with nanocomposites was confirmed by Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Two experiments were conducted to study the effect of naked (without nanoparticles) and conjugated nonapeptides on the milt release by stripping. Both the experiments consisted of eight treatments which included four naked groups two nanoconjugated groups and two controls. Both naked and nonconjugated formulations were successful in stripping the male catfish. The mRNA expression of selected reproductive genes was analysed to decipher the effect of nanopeptides at the molecular level. Nonapeptide treatment either naked or nanoconjugated, resulted in the upregulation of the transcript level of genes. Histological analysis revealed the concentration of spermatozoa was more in peptide injected groups than in the controls. The synergistic effects of nonapeptides and Ovatide had a positive impact on GSI. Thus, the present formulations were successful in stripping the male catfish to obtain the milt with significant reproductive success. Even though the naked groups perform better but the number of males required to fertilize the eggs in nanoconjuagted groups was smaller making it worth using for the delivery of nonapeptides.

Insights into early ontogenesis: characterization of stress and development key genes of pikeperch (Sander lucioperca) in vivo and in vitro

There are still numerous difficulties in the successful farming of pikeperch in the anthropogenic environment of various aquaculture systems, especially during early developmental steps in the hatchery. To investigate the physiological processes involved on the molecular level, we determined the basal expression patterns of 21 genes involved in stress and immune responses and early ontogenesis of pikeperch between 0 and 175 days post hatch (dph). Their transcription patterns most likely reflect the challenges of growth and feed conversion. The gene coding for apolipoprotein A (APOE) was strongly expressed at 0 dph, indicating its importance for yolk sac utilization. Genes encoding bone morphogenetic proteins 4 and 7 (BMP4, BMP7), creatine kinase M (CKM), and SRY-box transcription factor 9 (SOX9) were highly abundant during the peak phases of morphological changes and acclimatization processes at 4-18 dph. The high expression of genes coding for peroxisome proliferator-activated receptors alpha and delta (PPARA, PPARD) at 121 and 175 dph, respectively, suggests their importance during this strong growth phase of juvenile stages. As an alternative experimental model to replace further in vivo investigations of ontogenetically important processes, we initiated the first approach towards a long-lasting primary cell culture from whole pikeperch embryos. The present study provides a set of possible biomarkers to support the monitoring of pikeperch farming and provides a first basis for the establishment of a suitable cell model of this emerging aquaculture species.

Genome wide identification, phylogeny, and synteny analysis of sox gene family in common carp (Cyprinus carpio)

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27 SOX (high-mobility group HMG-box) genes were identified in the C. carp genome.

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SOX genes ranging from 3496 (SOX6) to 924bp (SOX17b) which coded with putative protein series from 307 to 509 amino acids.

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Gene ontology revealed SOX proteins maximum involvement is in metabolic process 49.796 %.

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Chromosomal location and synteny analysis display all SOX gene are located on different chromosomes.

Common carp (Cyprinus carpio) is a commercial fish species valuable for nutritious components and plays a vital role in human healthy nutrition. The SOX (SRY-related genes systematically characterized by a high-mobility group HMG-box) encoded important gene regulatory proteins, a family of transcription factors found in a broad range of animal taxa and extensively known for its contribution in multiple developmental processes including contribution in sex determination across phyla. In our current study, we initially accomplished a genome-wide analysis to report the SOX gene family in common carp fish based on available genomic sequences of zebrafish retrieved from gene repository databases, we focused on the global identification of the Sox gene family in Common carp among wide range of vertebrates and teleosts based on bioinformatics tools and techniques and explore the evolutionary relationships. In our results, a total of 27 SOX (high-mobility group HMG-box) domain genes were identified in the C. carp genome. The full length sequences of SOX genes ranging from 3496 (SOX6) to 924bp (SOX17b) which coded with putative proteins series from 307 to 509 amino acids and all gene having exon number expect SOX9 and SOX13. All the SOX proteins contained at least one conserved DNA-binding HMG-box domain and two (SOX7 and SOX18) were found C terminal. The Gene ontology revealed SOX proteins maximum involvement is in metabolic process 49.796 %, average in biological regulation 45.188 %, biosynthetic process (19.992 %), regulation of cellular process 39.68, 45.508 % organic substance metabolic process, multicellular organismal process 23.23 %,developmental process 21.74 %, system development 16.59 %, gene expression 16.05 % and 14.337 % of RNA metabolic process. Chromosomal location and syntanic analysis show all SOX gene are located on different chromosomes and apparently does not fallow the unique pattern. The maximum linkage of chromosome is (2) on Unplaced Scaffold region. Finally, our results provide important genomic suggestion for upcoming studies of biochemical, physiological, and phylogenetic understanding on SOX genes among teleost.

Chitosan-Based Drug Delivery System: Applications in Fish Biotechnology

Chitosan is increasingly used for safe nucleic acid delivery in gene therapy studies, due to well-known properties such as bioadhesion, low toxicity, biodegradability and biocompatibility. Furthermore, chitosan derivatization can be easily performed to improve the solubility and stability of chitosan-nucleic acid polyplexes, and enhance efficient target cell drug delivery, cell uptake, intracellular endosomal escape, unpacking and nuclear import of expression plasmids. As in other fields, chitosan is a promising drug delivery vector with great potential for the fish farming industry. This review highlights state-of-the-art assays using chitosan-based methodologies for delivering nucleic acids into cells, and focuses attention on recent advances in chitosan-mediated gene delivery for fish biotechnology applications. The efficiency of chitosan for gene therapy studies in fish biotechnology is discussed in fields such as fish vaccination against bacterial and viral infection, control of gonadal development and gene overexpression and silencing for overcoming metabolic limitations, such as dependence on protein-rich diets and the low glucose tolerance of farmed fish. Finally, challenges and perspectives on the future developments of chitosan-based gene delivery in fish are also discussed.

Genotoxic biomarkers and histological changes in marine medaka (Oryzias melastigma) exposed to 17α-ethynylestradiol and 17β-trenbolone

Endocrine-disrupting pollutants in marine environments have aroused great concern for their adverse effects on the reproduction of marine organisms. This study aimed to seek promising biomarkers for estrogenic/androgenic chemicals. First, two possible male-specific genes, SRY-box containing gene 9a2 (sox9a2) and gonadal soma-derived factor (gsdf), were cloned from marine medaka (Oryzias melastigma). Then the responses of sox9a2, gsdf, choriogenin (chgH and chgL), vitellogenin (vtg1 and vtg2), and cytochrome P450 aromatase (cyp19a and cyp19b) were investigated after exposure to 17α-ethynylestradiol (EE₂) and 17β-trenbolone (TB) at 2, 10, and 50 ng/L. The results showed that gsdf was specifically expressed in the testes and easily induced in the ovaries after TB exposure, indicating that gsdf was a potential biomarker of environmental androgens. ChgL was a useful biomarker of weak estrogen pollution for its high sensitivity to low levels of EE₂. In addition, both EE₂ and TB exposure damaged gonadal structures and inhibited gonadal development.

Chitosan-eurycomanone nanoformulation acts on steroidogenesis pathway genes to increase the reproduction rate in fish

The study was undertaken to explore the molecular mechanism of eurycomanone, a major compound of Eurycoma longifolia plant in increasing the reproductive processes in the male fish model. Chitosan-nanoconjugated eurycomanone nanoparticles with a significant particle size [130 nm (CED1); 144.1 nm (CED2)] and stable zeta potentials (+49.1 mV and +30 mV) were synthesized and evaluated against naked eurycomanone (ED1 and ED2). In present study, short-term and long-term experiments were conducted to evaluate the effect of nano-formulation on expression of endocrine-related genes, circulating hormone concentrations (Follicle stimulating hormone, FSH; luteinizing hormone, LH; progesterone, testosterone and 17-β estradiol) and reproductive capacity of male Clarias magur. In short-term experiment, the sampling of tissues was done on hourly basis after injection of eurycomanone either alone or with chitosan and long-term experiment was carried for 21 days and in this the injection was repeated after 7 days and 14 days. Treatments CED1 and CED2 showed controlled and sustained surge of the transcript level of selected genes (except aromatase) and serum hormones (except 17β-estradiol) compared to ED1 and ED2 groups. The transcript levels of aromatase and serum 17β-estradiol hormone showed the declining trend in the chitosan conjugated groups. The gonadosomatic index (GSI), reproductive capacity, intracellular calcium and selenium and cellular structure of testes were improved in CED1 and CED2 groups compared to other treatments. Furthermore, the effect of chitosan conjugated eurycomanone was evaluated in primary testicular cells and an increase in the mRNA expression level of endocrine-related genes was detected. This is the first report of the use of chitosan conjugated eurycomanone and present study elucidates the molecular mechanism of eurycomanone in increasing the reproductive output in animals.

Ameliorative effect of chitosan-conjugated 17α-methyltestosterone on testicular development in Clarias batrachus

Chitosan nanoparticles conjugated with 17α-methyltestosterone (CS + MT) were used for studying their effect on the testicular development of Clarias batrachus during different reproductive phases. The size of chitosan nanoparticles was 127.2 nm and the nano-conjugated 17α methyltestosterone (17α-MT) was 196.1 nm (20 mg/100 ml of chitosan). Single injections of CS + MT at different doses such as 0.01, 0.1 and 0.5 μg/g body weight were administered to adults during the pre-spawning, spawning and post-spawning phase. Nano-conjugated steroid was effective at the lower dose; showing an increase in the Gonadosomatic Index (GSI) and 11-ketotestosterone level compared to the control group. Histological observations confirmed the dose-dependent advancement in spermatogenesis. These findings indicate the possibility of using CS + MT for enhancing gonadal maturity of C. batrachus.

Reference gene selection for quantitative real-time RT-PCR normalization in Clarias magur at different larval developmental stages

Reference genes employed for normalizing quantitative PCR data are important for the accurate analysis of gene expression. To date, no reference genes have been screened for developmental gene expression studies in Clarias magur. In the present study, three commonly used and constitutively expressed genes viz. beta actin (β- actin), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and elongation factor-alpha 1 (EFa1) were examined for their efficacy as internal control to avoid any variation during qRT-PCR expression analysis at different developmental stages of C. magur. All the selected housekeeping genes showed a variable level of mRNA expression during the developmental stages of C. magur. Using three independent statistical algorithms (delta-CT, BestKeeper and NormFinder), β-actin and GAPDH were identified as the suitable genes at different developmental stages. However, comprehensive gene stability evaluation denoted β-actin to be the most stable gene for carrying any gene expression studies. The present results, recommend β-actin as the optimal housekeeping gene for qRT-PCR analysis during different developmental stages of C. magur.

Fabrication and characterization of chitosan conjugated eurycomanone nanoparticles: In vivo evaluation of the biodistribution and toxicity in fish

Chitosan nanoparticles (CNPs) have been proven considerable delivery agents due to their remarkable physicochemical properties. Present study reports the fabrication of CNPs by ionic gelation process and their characterization by different approaches. The constructed nanoparticles were successfully conjugated with eurycomanone with significant entrapment efficiency. Particle size of chitosan and chitosan conjugated eurycomanone nanoparticles were 126.2nm and 130nm respectively. Scanning electron microscopy showed that the particles were spherical in shape and well dispersed. Cross-linking between CNPs and eurycomanone (CENPs) were confirmed by Fourier-transform infrared (FTIR) spectroscopy. Fluorescent nanoparticles were prepared by using Rhodamine-6G dye, characterised by SEM and confirmed for conjugation by FTIR. Biodistribution of CENPs showed the presence of fluorescent nanoparticles in liver, kidney, testes and brain of C. magur. The toxicity of CENPs was evaluated by comparing the histological sections of catfish testes collected from treated and control group. No signs of toxicity were seen in testes after the delivery of CENPs. Molecular docking study revealed high spontaneous binding ability of chitosan with eurycomanone and aromatase enzyme. The study reports that CNPs can act as a stabilizing agent for eurycomanone formulation and could be a promising approach to increase the reproductive performance of the fishes.

Cloning, characterisation, docking and expression analysis of 3-beta-hydroxysteroid dehydrogenase during ontogenetic development and annual reproductive cycles in catfish, Clarias batrachus

Fish like higher animals, have a well-defined mechanism to produce sex steroids that play a critical role in gonadal development and maturation. In this study, we aimed to analyse the expression pattern of 3β-HSD in different tissues, during ontogenetic development and gonadal recrudescence of Clarias batrachus. A full-length cDNA of 1617 bp including an open reading frame (ORF) of 1125 bp encoding 374 amino acids was isolated from testes of C. batrachus. The docking analysis between C. batrachus 3β-HSD protein and eurycomanone exhibited high binding affinity toward each other with total energy of -108.292 kcal/mol and van der Waals (VDW) interaction of -84.2838 kcal/mol. The 3β-HSD transcript level during ontogeny was detected in all the stages starting from the fertilized egg. The mature C. batrachus showed more expression of 3β-HSD mRNA in gonads and brain while weak expression was detected in the remaining tissues analysed. The 3β-HSD mRNA expression during annual reproductive phases of gonads was more in preparatory and pre-spawning stages than that of spawning and post-spawning phases. The mRNA expression results together suggest that 3β-HSD plays an important role in gonadal development. Furthermore, the active binding sites on 3β-HSD protein could be targeted in pharmacological drug designing to cope with reproductive dysfunctions in fish.

Effects of nanoparticles in species of aquaculture interest

Recently, it was observed that there is an increasing application of nanoparticles (NPs) in aquaculture. Manufacturers are trying to use nano-based tools to remove the barriers about waterborne food, growth, reproduction, and culturing of species, their health, and water treatment in order to increase aquaculture production rates, being the safe-by-design approach still unapplied. We reviewed the applications of NPs in aquaculture evidencing that the way NPs are applied can be very different: some are direclty added to feed, other to water media or in aquaculture facilities. Traditional toxicity data cannot be easily used to infer on aquaculture mainly considering short-term exposure scenarios, underestimating the potential exposure of aquacultured species. The main outputs are (i) biological models are not recurrent, and in the case, testing protocols are frequently different; (ii) most data derived from toxicity studies are not specifically designed on aquaculture needs, thus contact time, exposure concentrations, and other ancillary conditions do not meet the required standard for aquaculture; (iii) short-term exposure periods are investigated mainly on species of indirect aquaculture interest, while shrimp and fish as final consumers in aquaculture plants are underinvestigated (scarce or unknown data on trophic chain transfer of NPs): little information is available about the amount of NPs accumulated within marketed organisms; (iv) how NPs present in the packaging of aquacultured products can affect their quality remained substantially unexplored. NPs in aquaculture are a challenging topic that must be developed in the near future to assure human health and environmental safety. Graphical abstract ᅟ.

Steroidogenic acute regulatory protein (StAR) gene expression construct: Development, nanodelivery and effect on reproduction in air-breathing catfish, Clarias batrachus

Steroidogenic acute regulatory protein (StAR) is responsible for the relocation of cholesterol across mitochondrial membrane in vertebrates and is, therefore, a key factor in regulating the rate and timing of steroidogenesis. In the present study, we developed chitosan nanoparticle (CNP) conjugated StAR gene construct (CNP-pcDNA4-StAR) in a eukaryotic expression vector, pcDNA4/HisMax A. CNPs of 135.4nm diameter, 26.7mV zeta potential and 0.381 polydispersity index were used for conjugation. The loading efficiency (LE) of pcDNA4-StAR construct with CNPs was found to be 86%. After the 24h of intramuscular injection, the CNP-pcDNA4-StAR plasmid could be detected from testis, brain, kidney and muscle tissues of Clarias batrachus. The transcript levels of important reproductive genes viz. cyp11a1, cyp17a1, 3β-hsd, 17β-hsd and cyp19a1 in CNP-pcDNA4-StAR treated group were initially low up to 24h, but significantly increased subsequently up to 120h. In naked pcDNA4-StAR treated group, the mRNA level of 3β-hsd, 17β-hsd and cyp19a1 increased initially up to 24h, while cyp11a1 and cyp17a1 increased up to 48h and then started declining. Similar results were obtained for 11-Ketotestosterone and 17β-estradiol. The results indicate relatively long lasting effects of nano-conjugated construct compared to the construct alone. Furthermore, the histopathology of gonads and liver authenticates its possible role in the gonadal development in fish without any adverse effect.

Metabolite and gene expression responses in juvenile flounder Paralichthys olivaceus exposed to reduced salinities

Seawater salinity is one of the most important changeable environmental factors influencing the behavior, survival, growth and production of marine organisms. In this work, metabolite and gene expression profiles were used to elucidate the biological effects of reduced salinities in juvenile flounder Paralichthys olivaceus. Metabolic profiling indicated that both reduced salinities (23.3‰ and 15.6‰) enhanced proteolysis and disturbed osmotic regulation and energy metabolism in juvenile flounder P. olivaceus. Furthermore, the low salinity (15.6‰) enhanced anaerobic metabolism indicated by the elevated lactate in flounder tissue extracts. Gene expression profiles exhibited that reduced salinities could induce immune stress and oxidative stress and disturb energy metabolism in juvenile flounder P. olivaceus. In addition, reduced salinities might promote the growth and gonadal differentiation in juvenile flounder P. olivaceus.