Nicholas Romano

Virgin microplastics cause toxicity and modulate the impacts of phenanthrene on biomarker responses in African catfish (Clarias gariepinus)

Despite the ubiquity of microplastics (MPs) in aquatic environments and their proven ability to carry a wide variety of chemicals, very little is known about the impacts of virgin or contaminant-loaded MPs on organisms. The primary aim of this study was to investigate the impacts of virgin or phenanthrene (Phe)-loaded low-density polyethylene (LDPE) fragments on a suite of biomarker responses in juvenile African catfish (Clarias gariepinus). Virgin LDPE (50 or 500µg/L) were preloaded with one of two nominal Phe concentrations (10 or 100µg/L) and were exposed to the fish for 96h. Our findings showed one or both Phe treatments significantly increased the degree of tissue change (DTC) in the liver while decreased the transcription levels of forkhead box L2 (foxl2) and tryptophan hydroxylase2 (tph2) in the brain of C. gariepinus. Exposure to either levels of virgin MPs increased the DTC in the liver and plasma albumin: globulin ratio while decreased the transcription levels of tph2. Moreover, MPs modulated (interacted with) the impact of Phe on the DTC in the gill, plasma concentrations of cholesterol, high-density lipoprotein (HDL), total protein (TP), albumin, and globulin, and the transcription levels of fushi tarazu-factor 1 (ftz-f1), gonadotropin-releasing hormone (GnRH), 11 β-hydroxysteroid dehydrogenase type 2 (11β-hsd2), and liver glycogen stores. Results of this study highlight the ability of virgin LDPE fragments to cause toxicity and to modulate the adverse impacts of Phe in C. gariepinus. Due to the wide distribution of MPs and other classes of contaminants in aquatic environments, further studies are urgently needed to elucidate the toxicity of virgin or contaminant-loaded MPs on organisms.

A high-performance protocol for extraction of microplastics in fish

So far, several classes of digesting solutions have been employed to extract microplastics (MPs) from biological matrices. However, the performance of digesting solutions across different temperatures has never been systematically investigated. In the first phase of the present study, we measured the efficiency of different oxidative agents (NaClO or H2O2), bases (NaOH or KOH), and acids [HCl or HNO3; concentrated and diluted (5%)] in digesting fish tissues at room temperature (RT, 25°C), 40, 50, or 60°C. In the second phase, the treatments that were efficient in digesting the biological materials (>95%) were evaluated for their compatibility with eight major plastic polymers (assessed through recovery rate, Raman spectroscopy analysis, and morphological changes). Among the tested solutions, NaClO, NaOH, and diluted acids did not result in a satisfactory digestion efficiency at any of the temperatures. The H2O2 treatment at 50°C efficiently digested the biological materials, although it decreased the recovery rate of nylon-6 (NY6) and nylon-66 (NY66) and altered the colour of polyethylene terephthalate (PET) fragments. Similarly, concentrated HCl and HNO3 treatments at RT fully digested the fish tissues, but also fully dissolved NY6 and NY66, and reduced the recovery rate of most or all of the polymers, respectively. Potassium hydroxide solution fully eliminated the biological matrices at all temperatures. However, at 50 and 60°C, it degraded PET, reduced the recovery rate of PET and polyvinyl chloride (PVC), and changed the colour of NY66. According to our results, treating biological materials with a 10% KOH solution and incubating at 40°C was both time and cost-effective, efficient in digesting biological materials, and had no impact on the integrity of the plastic polymers. Furthermore, coupling this treatment with NaI extraction created a promising protocol to isolate MPs from whole fish samples.

Enrichment of common carp ( Cyprinus carpio ) diet with medlar ( Mespilus germanica ) leaf extract: Effects on skin mucosal immunity and growth performance

Abstract A feeding trial was performed to assess the effects of dietary Medlar (Mespilus germanica) leaf extract (MLE) on the growth performance, skin mucus non‐specific immune parameters as well as mRNA levels of immune and antioxidant related genes in the skin of common carp (Cyprinus carpio) fingerlings. Fish were fed diets supplemented with graded levels (0, 0.25, 0.50, and 1.00%) of MLE for 49 days. The results revealed an improvement to the growth performance and feed conversion ratio in MLE fed carps (P < 0.05), regardless of the inclusion level. The immunoglobulin levels and interleukin 8 levels in the skin mucous and skin, respectively, revealed significant increment in fish fed 1% MLE (P < 0.05) in comparison with the other MLE treatments and control group. Also, feeding on 0.25% and 0.50% MLE remarkably increased skin mucus lysozyme activity (P < 0.05). However, there were no significant difference between MLE treated groups and control (P > 0.05) in case protease activity in the skin mucous or tumor necrosis factor alpha and interleukin 1 beta gene expression in the skin of carps (P > 0.05). The expression of genes encoding glutathione reductase and glutathione S‐transferase alpha were remarkably increased in MLE fed carps compared to the control group (P < 0.05) while carp fed 0.50% or 1.00% MLE had significantly increased glutathione peroxidase expression in their skin (P < 0.05). The present results revealed the potentially beneficial effects of MLE on the mucosal immune system and growth performance in common carp fingerlings. HighlightsMedlar leaf extract (MLE) improved growth performance in fingerlings.MLE intake altered immune related genes expression in carp skin.MLE intake elevated the expression of antioxidant enzymes gene expression in skin.

Cannibalism of Decapod Crustaceans and Implications for Their Aquaculture: A Review of its Prevalence, Influencing Factors, and Mitigating Methods

ABSTRACT The prevalence of cannibalistic behavior among many commercially important decapod crustaceans is one of the biggest limiting factors to their culture productivity and profitability in aquaculture. Various biotic and abiotic factors influence cannibalism including stocking densities, molt status, size heterogeneity, photoperiod, light intensity, and availability to refuge and food; however, their relative efficacies are often species or stage dependent. For instance, although generally penaeid shrimp are seldom cannibalistic when food and space are sufficient, this does not apply to many crab, lobster, and some crayfish species. This review will first discuss the cannibalistic prevalence among commercially important crustacean species followed by a brief review on the current knowledge regarding chemical cues that trigger cannibalism. The main focus will then be on various mitigating methods to improve survival for each of the three main aquaculture phases, that is hatchery, nursery, and grow-out, respectively. Throughout, areas in which one method may have applications to other species or life stages will be highlighted. A final section discusses possible future directions that include individually farming high-value crustaceans and the potential to manipulate hormones associated with aggression. It is hoped that such discussions as well as identifying knowledge gaps will prompt research to help expand and diversify the crustacean farming industry.

Improvement of feed pellet characteristics by dietary pre-gelatinized starch and their subsequent effects on growth and physiology in tilapia

A 9-week study was conducted to compare dietary corn starch (CS) or tapioca starch (TS), with or without being pre-gelatinized (PG), on the growth, feeding efficiencies, plasma and muscle biochemistry, intestinal short chain fatty acids (SCFA), and liver glycogen of triplicate groups of 20 red hybrid tilapia (Orecohromis sp.). Various pellet characteristics were evaluated, along with their surface and cross sectional microstructure. The PG diets had significantly higher water stability, bulk density, and protein solubility, along with a smoother surface. Tilapia fed the TS diet had lower growth than had all other tilapia, but were significantly improved when diet was pre-gelatinized. In the PG treatments, intestinal SCFA significantly decreased while plasma glucose, cholesterol and triglycerides, as well as liver glycogen, significantly increased. Fish fed the CS diet had significantly more long chain polyunsaturated fatty acid than had those fed by other treatments. Pre-gelatinization may improve fish productivity and offer greater flexibility during aquafeed production.

Trypsin-modulating oostatic factor (TMOF) decreased the survival, growth and digestion enzymes of Macrobrachium rosenbergii

Trypsin-modulating oostatic factor (TMOF) is an effective mosquito larvicide, but information on its potential toxicity to non-target organisms is limited. To investigate this, triplicate groups of 10 Macrobrachium rosenbergii were exposed to 0, 10, 50 or 100 mg/L nominal TMOF concentrations for 12 days. Tail moisture, crude protein, and hepatopancreatic glycogen/histopathology were unaffected, but increasing TMOF linearly decreased survival and growth. TMOF at the lowest concentration employed significantly decreased trypsin and chymotrypsin activities.

Alternative and new sources of feedstuffs

Abstract Much of the research into improving the nutritive values of ingredients has mainly focused on plant proteins by decreasing various antinutritional factors (ANFs) inherent in these ingredients. While the use of enzymes can successfully reduce ANFs, many plant proteins are in high demand in the food-producing industries, particularly soybean meal. Therefore, new or alternative feedstuffs to terrestrial plant protein sources are increasingly being investigated, such as feather meal, algae meals, and insect meals. Each of these ingredients has a high potential for use in animal and fish feeds, but they also contain unique compounds that can also potentially act as ANFs. Reducing these specific compounds can be accomplished with enzymes, whilst simultaneously enhancing their nutritive value, which will be part of the focus of this chapter. Algae constitute a renewable resource used by the food industry, as feed for animals, to produce phycocolloids, as cosmetic ingredients, and for pharmaceutical applications as well as for biomaterials. Also, on the one hand they have suitable potential for decontamination. However, on the other hand their uncontrolled proliferation due to excessive nutrients environmental load is a strong concern related to natural conditions preservation. The Earth’s available stocks of lignocellulosic biomass are tremendous and distributed all around the world. Thus, the sustainability of the valorization of cellulose by cellulases seems clear. More economical feeding can most probably be obtained by improving pretreatment and enzymatic hydrolysis of cellulose. Furthermore, an application into human nutrition may be also possible. Laccases are already utilized in several industries as well as in bioremediations tools. Their potential in valorization of lignocellulose from nonedible plant biomass for nutrition use should be evaluated.

Dietary Euphorbia hirta Extract Improved the Resistance of Sharptooth Catfish Clarias gariepinus to Aeromonas hydrophila

Aqueous and methanol extracts of lemon Citrus limon peel, Euphorbia hirta (aerial parts), and fenugreek Trigonella foenum-graecum seeds were tested for their in vitro antimicrobial activities against the bacterium Aeromonas hydrophila. A swab paper disk method showed that the methanol extract of E. hirta (EHE) had the largest inhibition zone and the lowest minimal inhibitory concentration compared to all other herbal extracts. Based on these results, EHE was included in the diets of Sharptooth Catfish Clarias gariepinus at 0 (control), 2, 5, or 7 g/kg of diet (experiment 1). Each treatment was conducted in triplicate, with 30 fish (mean weight ± SE = 9.4 ± 0.4 g) in each replicate. After 30 d, the growth, feed intake, hepatosomatic index (HSI), and plasma biochemical parameters were measured. With a separate batch of Sharptooth Catfish, the efficacy of the EHE diets in conferring fish resistance to A. hydrophila over 30 d was compared to that of a diet containing oxytetracycline (OTC; experiment 2). Six treatments were conducted in triplicate groups of 30 fish (mean weight ± SE = 9.0 ± 0.3 g); the Control fish were fed the control diet and were not injected with A. hydrophila, while the Control-AH and OTC-AH groups were infected with A. hydrophila and were fed either the control diet or the diet containing OTC at 1 g/199 g. The other three treatments included fish that were injected with A. hydrophila but fed diets with increasing EHE at 2, 5, or 7 g/kg. Experiment 1 showed no change to growth, feeding efficiency, HSI, or plasma biochemical parameters. In experiment 2, however, fish that were fed dietary EHE at 5 g/kg had significantly lower mortality than the Control-AH group, with further resistance observed for fish fed EHE at 7 g/kg. Dietary OTC was more effective than EHE as a prophylactic to A. hydrophila infection in Sharptooth Catfish. Nevertheless, EHE can potentially be a valuable dietary supplement to improve the resistance of Sharptooth Catfish to A. hydrophila infection. Received May 3, 2017; accepted August 24, 2017.

Fatty acid compositional changes during the embryonic development of the swimming crab, Portunus pelagicus (Portunidae: Decapoda)

Abstract The fatty acid composition, moisture, and total lipid of the eggs from the swimming crab, Portunus pelagicus, at three different embryonic stages (within 24 h, during the eye placode stage and the final heart beat stage), were measured. Results showed that the moisture and lipid content significantly increased and decreased (p < 0.05), respectively, as the stages progressed. The most prevalent fatty acids that were initially deposited included C16:0, C18:1n-9, and C18:0, while the most consumed fatty acids were C22:5n-6, C22:5n-3, and C20:1n-7. Among the major fatty acid groups, polyunsaturated fatty acids (PUFA) and long-chain PUFA (LC-PUFA) were consumed more than saturated fatty acids and significantly more (p < 0.05) than monounsaturated fatty acids (p < 0.05). Meanwhile, n-3 PUFA was deposited in significantly higher amounts (p < 0.05) than n-6 PUFA, but both were consumed at similar amounts at 43.4% and 41.3%, respectively. The relatively low amount of C20:5n-3 and C22:6n-3 consumption may indicate these fatty acids were conserved, while the essential fatty acids C18:3n-3 and C18:3n-6 were consumed at high amounts. These findings may have implications for broodstock nutrition in order to formulate a well-balanced diet.

Metabolism and Nutritive Role of Cholesterol in the Growth, Gonadal Development, and Reproduction of Crustaceans

ABSTRACT Cholesterol is a major sterol in crustaceans that occurs in all cells and in the hemolymph, either in free form or combined with fatty acids. Unlike vertebrates, shrimps and other crustaceans are incapable of de novo synthesis of cholesterol; therefore, dietary cholesterol is essential for their growth and survival. Their requirement, however, is often species-specific and may also depend on the dietary protein and lipid sources. Dietary lipid sources can include the presence of phytosterols and phospholipids, which may have a cholesterol sparing effect in some species. On the other hand, compounds found within some fishmeal alternatives may disrupt cholesterol utilization. Understanding these relationships is important because cholesterol is essential for the synthesis of ecdysteroids and sesquiterpenoids, which are a class of hormones that regulate moulting and reproduction in crustaceans. The biosynthetic pathway of these hormones is not completely understood in crustaceans. When knowledge gaps exist, available information from a better-studied animal group (the insect), is extrapolated to produce a hypothetical model of putative ecdysteroid synthesis in crustaceans. The key steps in cholesterol metabolism, including digestion, absorption, and transportation are highlighted. There is also a focus on various pathways involving candidate genes (encoding enzymes) linking cholesterol metabolism and moulting. Considering the relatively high cost of cholesterol, a better understanding of factors influencing dietary cholesterol requirements in crustaceans and role this plays in lipid metabolism may facilitate more cost-effective feed formulations.