Lower Specific Growth Rate Research Articles

Nutritional Evaluation of Black Soldier Fly Frass as an Ingredient in Florida Pompano (Trachinotus carolinus L.) Diets.

Simple SummaryCarnivorous fish species, such as the Florida pompano, currently require expensive and unsustainable feed in order to be raised in an aquaculture setting. A waste product of the black soldier fly, frass has the potential to be an alternative carbohydrate source for these fish. This study aims to assess the potential of frass to mimic the growth, body, composition, and intestinal microbiome of pompano that can be achieved through commercial feed. Three diets with varying frass levels as well as a control diet were developed. The frass was found to increase the visceral somatic index and lower the hepatosomatic index. The frass did not alter the body composition or improve the growth performance, leading to a lower specific growth rate and higher feed conversion rate. The microbiome analysis showed the highest diversity of the gut flora in the control diet, while the frass diets showed signs of community imbalance. This may have been due to the decreased starch in the frass, which is usually metabolized by those microbial communities. Overall, frass diets are not ideal for carnivorous fish diets, but have could have potential for feed replacement in herbivore and detritivore fish species.The aquaculture industry is in need of sustainable fish feed to reduce the use of expensive and environmentally invasive wild-caught fish currently fed to many carnivorous species. The black soldier fly (BSF) has become a popular sustainable alternative protein source; however, the nutritional waste byproduct of BSF, frass, has not been extensively studied as a feed replacement in carnivorous species. This study evaluates the potential of BSF frass on the growth, body composition, and intestinal microbiome of the Florida pompano, Trachinotus carolinus. Four experimental diets were formulated containing different levels of frass, replacing plant-based carbohydrate sources. As a result of this study, the frass did not improve the growth performance, resulting in a lower specific growth rate and higher feed conversion rate. While the frass diets did not alter the body composition, the visceral somatic index (VSI) significantly increased compared to the control diet and the hepatosomatic index (HIS) was lowered. The microbiome analysis showed high variation among the diets, with the control diet having the most distinct consortia, which may have been driven by the increased levels of starch compared to frass diets. This study indicates that BSF frass may not be a suitable feed replacement for carnivorous pompano; however, frass could still potentially be a replacement feed for herbivore or detritivore fish and should be further studied.

Plant‐based diets fed to juvenile meagre Argyrosomus regius with low methionine and taurine supplementation led to an overall reduction in fish performance and to an increase in muscle fibre recruitment

Methionine and taurine are amino acids (AA) that are usually deficient when fish meal is replaced by plant proteins. In this study, three diets were tested in juvenile meagre (initial weight: 13.4 g) for 8 weeks. The D1 diet had 0.2% methionine and 1% taurine supplementation; the D2 and D3 diets had 0.6% methionine and 1% and 2% taurine supplementation, respectively. The results showed that meagre fed the D1 diet had lower specific growth rate (2.2 to 2.5), lower feed efficiency (0.9 to 1.2) and higher food conversion rate (FCR, 1.1 to 0.8) as well as a lower activity of the alanine aminotransferase (ALAT) enzyme. Furthermore, a higher recruitment of muscle fibres (46% compared to 36%) as well as a higher fibre density was observed (1019 compared to 870 fibres mm-2 ). This study shows that meagre requires a sufficient quantity of methionine in plant-based diets to avoid a reduction in fish performance. Furthermore, taurine supplementation in the D1 diet was not able to mitigate the effects of methionine deficiency. A higher taurine supplementation did not improve meagre performance.

An excess of glycolytic enzymes under glucose-limited conditions may enable Saccharomyces cerevisiae to adapt to nutrient availability.

Microorganisms, including the budding yeast Saccharomyces cerevisiae, express glycolytic proteins to a maximal capacity that (largely) exceeds the actual flux through the enzymes, especially at low growth rates. An open question is if this apparent expression level is really an overcapacity, or maintains the (optimal) enzyme capacity needed to carry flux at (very) low substrate availability. Here, we use computational modelling to suggest that yeast maintains a genuine excess of glycolytic enzymes at low specific growth rates. During fast fermentative growth at high glucose levels, the observed expression of the glycolytic enzymes matched the predicted optimal levels. We suggest that the excess glycolytic capacity at low glucose levels is apreparatory strategy in the adaptation to sugar fluctuations in the environment.

Cultivation of previously uncultured sponge-associated bacteria using advanced cultivation techniques: A perspective on possible key mechanisms

Most of the microbes from natural habitats cannot be cultivated with standard cultivation in laboratory, and sponge-associated microbes are no exception. We used two advanced methods based on a continuous-flow bioreactor (CF) and in situ cultivation (I-tip) to isolate previously uncultivated marine sponge-associated bacteria. We also characterized the physiological properties of the isolates from each method and attempted to clarify the mechanisms operating in each cultivation method. A greater number of novel bacteria were isolated using CF and in situ cultivation compared to standard direct plating (SDP) cultivation. Most isolates from CF cultivation were poor growers (with lower specific growth rates and saturated cell densities than those of isolates from SDP cultivation), demonstrating that it is effective to carry out pre-enrichment cultivation targeting bacteria that are less competitive on conventional cultivation, especially K-strategists and bacterial types inhibited by their own growth. Isolates from in situ cultivation showed a positive influence on cell recovery stimulated by chemical compounds in the extract of sponge tissue, indicating that some of the bacteria require a “growth initiation factor” that is present in the natural environment. Each advanced cultivation method has its own distinct key mechanisms allowing cultivation of physiologically and phylogenetically different fastidious bacteria for cultivation compared with conventional methods.

Verbascoside: An Efficient and Safe Natural Antibacterial Adjuvant for Preventing Bacterial Contamination of Fresh Meat.

Inappropriate and disproportionate antibiotic use contributes immensely to the development of antibiotic resistance in bacterial species associated with food contamination. Therefore, alternative strategies to treat multidrug-resistant (MDR) bacterial infections are urgently needed. In this study, verbascoside was shown to exhibit excellent antibacterial activity and synergistic effects in combination with cell wall synthesis-inhibiting antibiotics, indicating that it can be used as an adjuvant to restore or increase the activity of antibiotics against resistant pathogens. In a mechanistic study, higher concentrations of verbascoside resulted in a longer lag phase and a lower specific exponential-phase growth rate of bacteria. Furthermore, verbascoside exerted its antimicrobial activity through multiple mechanisms, including cell membrane dysfunction, biofilm eradication and changes in cell morphology. The promising antibacterial activity and in vitro safety assessment results suggested that verbascoside can be used as a food additive for fresh meat preservation. Treatment with medium and high doses of verbascoside caused significant bacterial death in meat samples, slowed the spoilage rate, and extended the shelf life. Collectively, verbascoside is expected to be useful as an antibiotic adjuvant to prevent or treat resistant bacteria-related infections and an alternative novel antimicrobial additive in the food industry.

Evaluation of dietary fish meal analog with or without supplementation of natural feed additives as the substitute of fish meal in juvenile Japanese eel, Anguilla japonica

We investigated the nine experimental diets containing fish meal (FM) and/or fish meal analog (FMA) as the major source of animal protein to determine the optimum FMA level as the substitute of FM protein in the diet of juvenile Japanese eel. In addition, two natural feed additives such as Song-Gang stone (SG) and Yucca meal (YM) were supplemented in the diet to evaluate their efficacy as the immunostimulants. The diets are as follows: 100% FM + 0% FMA in diet (FMA0), 90% FM + 10% FMA in diet (FMA10), 80% FM + 20% FMA in diet (FMA20), 70% FM + 30% FMA in diet (FMA30), 60% FM + 40% FMA in diet (FMA40), FMA0 + 0.4% SG (FMA0SG), FMA0 + 0.1% YM (FMA0YM), FMA20 + 0.4% SG (FMA20SG), and FMA20 + 0.1% YM (FMA20YM). Nine groups of Japanese eel each with three replicates were distributed (initial weight of 9 ± 0.2 g) in rectangular tanks receiving flow through water. Each group of the treatment consisted with 15 fish and fed one of the diets for 8 weeks. At the end of the feeding trial, fish fed with the FMA0 and FMA10 diets showed no significant differences in weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER). Meanwhile, fish fed with FMA20, FMA30, and FMA40 diets showed significantly lower WG, SGR, FE, and PER than the fish fed with the FMA0 (control) diet. In addition, there were no significant differences among fish fed with the SG- and YM-supplemented diet groups. However, lysozyme activities in fish fed with the FMA10, FMA20, FMA30, and FMA40 were significantly lower than the fish fed with the FMA0SG, FMA0YM, FMA20SG, and FMA20YM diets. After 7 days of injection with V. Anguillarum, cumulative survival rates of fish fed with the FMA0SG and FMA0YM diets were significantly higher than the FMA0 diet group. The results revealed that the FMA could replace up to 10% of FM as a protein source in the diet of Japanese eel and both of the natural feed additives (SG and YM) could improve replacing rates of FMA from 10% to 20% without compromising growth and health status of fish.

Effect of salinity on somatic growth and gonadal enhancement of the sea urchin Paracentrotus lividus (Lamarck, 1816)

Salinity plays a major role in several physiological processes in sea urchins, including reproduction and growth, ultimately affecting survival. Optimal salinity ranges vary considerably between species, as a consequence of ecological adaptations. However, related research in the context of aquaculture is quite scarce, particularly for the stenohaline sea urchin Paracentrotus lividus (Lamarck, 1816), a target species for aquaculture diversification in Europe. It is thus important to better understand the response of this species to hyposalinity conditions over an extended rearing period. Four salinity treatments (20, 25, 30 and 35 psu) were evaluated, over 120 days, in terms of survival, feed intake, growth, gametogenic development and gonadal colour in P. lividus. While a 100% survival was obtained in all treatments, salinity significantly affected all other parameters. Sea urchins reared at 20 psu presented significantly lower linear and specific growth rates, feed intake, gonadosomatic index, as well as a higher feed conversion ratio. While sea urchins reared at 30 and 35 psu were mostly mature, hyposalinity led to a slower gametogenic progression in the lower salinities, particularly at 20 psu. Gonad colouration was only affected in males, as individuals reared at 20 psu presented less brighter, but more reddish and yellowish gonads. The results clearly demonstrate that despite the absence of mortality, rearing salinities of 20 and 25 psu promote a negative effect on somatic and gonadal yield of P. lividus.

Effects of Different Marine-Based Lipid Sources on Growth Performance, Activities of Digestive Enzyme, Antioxidant Responses, and Lipid Metabolism of Large Yellow Croaker (Larimichthys crocea) Larvae

The study of lipid nutrition is an important guarantee for the development of high-efficiency artificial microdiet for fish larvae. Existing studies on lipid nutrition of larvae mainly focus on nutrient requirements and metabolism through a single lipid source. However, there are few reports on the effects of different marine-based lipid sources on fish larvae. In this study, a 30-day feeding experiment was conducted to evaluate the effects of different dietary marine-based lipid sources on survival, growth performance, appetite gene expression, activities of digestive enzyme, antioxidant responses, and lipid metabolism of large yellow croaker (Larimichthys crocea) larvae (initial weight 4.71 ± 0.21 mg ). Four isonitrogenous (520 g/kg crude protein) and isolipidic (190 g/kg crude lipid) diets were formulated to contain fish oil (FO), krill oil (KO), squid viscera oil (SVO), and Schizochytrium sp. oil (SSO), respectively. Results showed that larvae fed with the SSO diet had significantly higher survival rate (SR) than those fed with dietary FO and SVO ( P < 0.05 ). However, larvae fed with the SSO diet had significantly lower final body weight (FBW) and specific growth rate (SGR) than those fed with other diets ( P < 0.05 ). Furthermore, larvae fed with the SSO diet had significantly higher percentage of total n-3 long-chain polyunsaturated fatty acids (LC-PUFA) than those fed with other diets, followed by KO and SVO diets ( P < 0.05 ). Larvae fed with the SSO diet had significantly lower mRNA expression of orexigenic genes (npy and ghrelin) and significantly higher mRNA expression of anorexigenic gene (cart) than those fed with dietary FO ( P < 0.05 ). Meanwhile, larvae fed with the SSO diet had significantly higher activity of alkaline phosphatase (AKP) in intestinal segments (IS) and brush border membrane (BBM) than those fed with dietary FO and SVO ( P < 0.05 ). Larvae fed with the SSO diet had significantly higher activity of total antioxidant capacity (T-AOC) than those fed with dietary FO ( P < 0.05 ). The TG content and mRNA expression of lipogenesis genes (srebp-1c, fas, and scd1) were markedly lower in larvae fed with SSO, KO, and SVO diets than in those fed with dietary FO ( P < 0.05 ). Meanwhile, larvae fed with KO and SSO diets had significantly higher mRNA expression of the lipolysis gene (cpt-1) than those fed with other diets ( P < 0.05 ). In conclusion, results of the present study showed that FO can be completely replaced in large yellow croaker larvae feed with KO and SVO without negative effects. Moreover, the complete replacement of FO by SSO can improve survival, activities of digestive enzyme, antioxidant responses, and lipid metabolism, despite inhibiting the appetite and growth of large yellow croaker larvae.

Environment Constrains Fitness Advantages of Division of Labor in Microbial Consortia Engineered for Metabolite Push or Pull Interactions.

ABSTRACTFitness benefits from division of labor are well documented in microbial consortia, but the dependency of the benefits on environmental context is poorly understood. Two synthetic Escherichia coli consortia were built to test the relationships between exchanged organic acid, local environment, and opportunity costs of different metabolic strategies. Opportunity costs quantify benefits not realized due to selecting one phenotype over another. The consortia catabolized glucose and exchanged either acetic or lactic acid to create producer-consumer food webs. The organic acids had different inhibitory properties and different opportunity costs associated with their positions in central metabolism. The exchanged metabolites modulated different consortial dynamics. The acetic acid-exchanging (AAE) consortium had a “push” interaction motif where acetic acid was secreted faster by the producer than the consumer imported it, while the lactic acid-exchanging (LAE) consortium had a “pull” interaction motif where the consumer imported lactic acid at a comparable rate to its production. The LAE consortium outperformed wild-type (WT) batch cultures under the environmental context of weakly buffered conditions, achieving a 55% increase in biomass titer, a 51% increase in biomass per proton yield, an 86% increase in substrate conversion, and the complete elimination of by-product accumulation all relative to the WT. However, the LAE consortium had the trade-off of a 42% lower specific growth rate. The AAE consortium did not outperform the WT in any considered performance metric. Performance advantages of the LAE consortium were sensitive to environment; increasing the medium buffering capacity negated the performance advantages compared to WT.IMPORTANCE Most naturally occurring microorganisms persist in consortia where metabolic interactions are common and often essential to ecosystem function. This study uses synthetic ecology to test how different cellular interaction motifs influence performance properties of consortia. Environmental context ultimately controlled the division of labor performance as shifts from weakly buffered to highly buffered conditions negated the benefits of the strategy. Understanding the limits of division of labor advances our understanding of natural community functioning, which is central to nutrient cycling and provides design rules for assembling consortia used in applied bioprocessing.

Dietary replacement of fish meal with soybean meal for the optimal growth of Juvenile Milkfish, Chanos chanos (Forsskal, 1775) in seawater tanks

The core of the current study is to find out a different source of diet that stimulates better growth rate and low-cost feed for commercial fish milkfish Chanos chanos. This study was to assess the impact of partial replacement of fish meal by soybean meal in the diet of juvenile milkfish, Chanos chanos (initial weight 25 ± 0.6 g). The juveniles were fed with two types of iso-nitrogenous diets (40% crude protein). Plant protein source diet (D1) comprised of soybean meal 45% and 10% fish meal, while animal protein source diet (D2) contained fish meal 25% and soybean meal 30%. The trial was conducted with two replications for 60 days. Fish juveniles (10 each) were stocked in outdoor fiberglass seawater tanks (5000 Liters). Results revealed that final weight gain (WG), and specific growth rate (SGR) were significantly lower in fish fed D2 diet. Fish fed D1 had better feed efficiency, weight gain (21.88 ± 1.9 g), and SGR (1.05 ± 0.3), while D2 had a lower growth rate, WG (18.71 ± 2.3 g) and SGR (0.93 ± 0.2). The maximum growth rate found on plant diet which is significantly higher weight gain than D2. In D2 feed conversion ratio (0.54 ± 0.21) was significantly higher (P≤0.05). Condition factor among both treatments did not differ significantly (P≥0.05). The survival rate remained constant (100%) in both treatments. Based on the obtained results, it is recommended that 45% soybean meal with addition of 10% fishmeal (40% protein) is more effective than 30% soybean meal with addition of 25% fish meal to the omnivorous milkfish for aquaculture.

Dietary Parsley Seed Mitigates Methomyl-Induced Impaired Growth Performance, Hemato-Immune Suppression, Oxidative Stress, Hepato-Renal Damage, and Pseudomonas aeruginosa Susceptibility in Oreochromis niloticus.

The present experiment investigated the potential protective role of parsley (Petroselinum crispum) seed meal (PSM) in alleviating methomyl (MET)-adverse impacts on growth, whole-body composition, hematological indicators, hepatorenal function, immune response, oxidative status, and disease resistance to Pseudomonas aeruginosa. For this purpose, 225 healthy Nile tilapia (Oreochromis niloticus) were allotted into five groups (45 fish/group in triplicate). One group was reared in clean water and fed a non-supplemented basal diet, while the other groups were exposed to 20.39 μg L−1 MET and fed a non-fortified basal diet or basal diets supplemented with 0.5, 1.0, or 2.0% of PSM for 60 days. The obtained data revealed significantly lower weight gain, feed intake, and specific growth rate, but higher feed conversion ratio and decreases in crude protein, lipid, and ash contents in the MET-exposed fish. Anemia, leukopenia, lymphocytopenia, and esonipenia were also obvious. Furthermore, MET-exposed fish had significantly higher serum levels of hepatic enzymes and renal damage products. Nevertheless, there was a significant depletion of enzymatic and non-enzymatic antioxidants and increased malondialdehyde, myeloperoxidase, and tumor necrosis factor-α levels in MET-exposed fish. The MET exposure significantly depressed lysozyme activity, nitric oxide, complement3, acetylcholinesterase activity, total proteins, globulin, and albumin levels in O. niloticus serum. Furthermore, pathological alterations in the liver and kidney were noted. The relative percentage of survival rate in MET-exposed fish was dramatically reduced on day 14 post-challenge with P. aeruginosa. The inclusion of PSM, on the other hand, greatly alleviated most of the MET-related negative effects. Taken together, the dietary intervention with PSM has a promising role in alleviating MET-deleterious impacts, rendering parsley seeds a viable aqua feed additive for O. niloticus.

Dietary Sodium Butyrate Supplementation Attenuates the Detrimental Effects of High‐Fat Diets on Growth Performance, Liver Health, and Disease Resistance in Grass Carp

AbstractAn 8‐week experiment was conducted to investigate the effects of sodium butyrate (NaBT) inclusion in high‐fat (HF) diets on growth performance, liver health, and disease resistance in Grass Carp Ctenopharyngodon idella. Three diets (Control diet containing crude lipid at 58 g/kg, HF diet with 108‐g/kg crude lipid, and NaBT diet with 108‐g/kg crude lipid and 1‐g/kg NaBT) were randomly assigned to nine tanks with 30 fish (9.50 ± 0.06 g) in each tank. After the feeding trial, disease resistance was assessed by injecting the fish with Aeromonas hydrophila. Compared to the Control diet group, the HF diet group showed lower specific growth rate, feed efficiency, and survival rate (15.7%) after the A. hydrophila challenge; significantly higher activity levels of alanine aminotransferase and aspartate aminotransferase in plasma; higher malondialdehyde content; higher messenger RNA (mRNA) expression of interleukin‐8, cysteinyl aspartate specific protease (caspase) 9, and caspase 3; lower activity level of glutathione peroxidase; and lower mRNA expression of nuclear factor erythroid 2‐related factor 2 in liver. However, the NaBT diet significantly increased fish growth performance and survival rate (39.7%) after the A. hydrophila challenge and reduced hepatic oxidative stress, inflammation, and apoptosis compared to the HF diet. In conclusion, NaBT can ameliorate the detrimental effects of HF diets on fish growth performance and fish health.

A Study on the Specific Growth Rate (SGR) at Different Stages of Tilapia (Oreochromis niloticus) Production Cycle in Tank Based Aquaculture System

The conventional assessment of the specific growth rate (SGR) avoiding intermediary data is highly criticized by scholars as to the data of the beginning and the end of the production cycle usually considered for the measurement. To evaluate the SGR, the study was conducted in six concrete tanks under an outdoor laboratory shed from 10th May to 29th July 2017. Tilapia (Oreochromis niloticus) fry was released at the rate of 8 fries per tank as per the recommended stocking density of 320 fishes/decimal in an intensive aquaculture system. To evaluate the experiment, sinking and floating feeds as treatment 1 (T1) and treatment 2 (T2) were used for feeding the fish, respectively. There were three replications for each treatment. During the experimental period, the feed was supplied at the rate of 20%, 15%, and 10% of the body weight in the 1st, 2nd, and 3rd months, respectively. The daily ration of fish was divided into two parts and delivered to fish in the morning and in the evening. Aeration facilities were installed for 24 hours using an air stone aerator. Digital balance was used for measuring the weight of fish in 3 days intervals to assume the trend of SGR while a customized scoop net was used to sample the fish minimizing the stress on the fish. The weight gains of fish were 126.08±5.65 and 132.23±1.29 for T1 and T2, respectively. The mean percent weight gain was found higher in T2 (1715.03±0.00) than in T1 (1639.43±0.00). Feed conversion ratio (FCR) in T1 and T2 were 1.97±0.11 and 2.13±0.18, respectively. The specific growth rates (SGR) of tilapia in T1 and T2 were 4.90±3.03 and 4.98±2.28 considering the data at the beginning and the end of the production cycle, respectively. However, the SGR for floating feed was higher at the initial stage of the production cycle and lower in the later stages. The SGR was almost static for sinking feed from the beginning to the end of the experimental period. The higher FCR in T2 was correlated with the lower SGR in the later stage of the culture period. This ascertains that the pre-determined required amount of feeding ration imparted by the farmers in case of floating feed which wastes the high-cost feed and money. Higher total production was obtained in T2 (1119.52 g) than in T1 (1070.19 g) with 100% survival in both treatments. Therefore, determining SGR in a specific interval might be a useful tool at the farmer’s level.

Effect of mangrove leaf litter on shrimp (Penaeus monodon, Fabricius, 1798) growth and color

Color, texture and flavor are all important determinants of seafood product quality and value. For shrimp, Penaeus monodon, one of the highest-priced shrimp species of the South-East Asia shrimp industry, dark tiger-striped coloration is a key product quality criterion. We evaluated the effects of leaf litter of the mangrove species Avicennia officinalis (AO), Heritiera fomes (HF), Sonneratia apetala (SA) and S.caseolaris (SC) on length, weight and body color of shrimp (Penaeus monodon) post-larvae (PL). Fifteen-day-old PL (weight: 0.01 g) were reared in 1100-L fiber-reinforced polyethylene tanks. Five treatments having three replications were conducted for four weeks. Four treatments received leaf litter of the four mangrove species and supplemental feeds and one control treatment was provided with supplemental feed only (FO). The pH, biological oxygen demand (BOD5), chemical oxygen demand (COD) and phytoplankton and zooplankton biomass were lower, while total ammonia nitrogen (TAN) concentration were significantly higher in the FO treatment than in treatments including leaf litter. PL survival averaged 89% and only differed significantly between the SA and SC leaf litter treatments (p < 0.05). After 4 weeks of culture, larvae in the FO treatment had significantly shorter body and carapace length, lower body weight and a lower specific growth rate than larvae in the other treatments, while SA-reared larvae attained significantly greater length and weight than in the other leaf litter treatments. Shrimp body coloration and pattern with leaf litter treatments were significantly different from the FO treatment. SA-reared larvae at harvest were significantly darker in body color than larvae reared with other mangrove species. Shrimp value chain stakeholders preferred dark shrimp as an indicator of organic production and higher price. Mangrove leaf litter was found to enhance the production and color quality of black tiger shrimp and this technique can be applied in commercial shrimp aquaculture.

Effects of fishmeal substitution by four fermented soybean meals on growth， antioxidant capacity and inflammation responses of turbot juveniles (Scophthalmus maximus L.)

A 10-week feeding trial was conducted to examine the effects of fishmeal (FM) substitution by different types of FSBM on growth performance, antioxidant capacity and inflammatory responses of turbot juveniles (Scophthalmus maximus L.). Four strains of microorganisms Saccharomycopsis fibuligera isolate Y27 (SF), Bacillus tequilensis KCTC 13622 (BT), Bacillus subtilis strain D7XPN1 (BS) and Bacillus aryabhattai B8W22 (BA) with high-efficiency degradation of glucoside of soybean isoflavones (SI) were obtained through screening and isolation, and were used to ferment soybean meal (SBM) to enhance the utilization of SBM. Six isonitrogenous (50.05% crude protein) and isolipidic (10.46% crude lipid) diets were formulated. The FM diet (the control diet) was formulated with 55% fishmeal. Five experimental diets (Diets SBM45, SF45, BT45, BS45 and BA45) were formulated by replacing 45% of FM inclusion level of control diet using SBM or either FSBM produced by the above four strains, respectively. Results showed that there was a significant decrease in feed intake (FI) of fish fed the SBM45 diet than those of the control and either FSBM diets (P = 0.000), and no significant difference was found among the control, SF45, BT45 and BS45 groups (P > 0.05). Meanwhile, fish fed the diet BA45 showed a significantly higher FI compared with the control group (P = 0.000). The appetite-stimulating factor (agouti gene-related protein, agrp1) gene expression was significantly up-regulated in fish fed the diet SF45 compared with the SBM45 group (P = 0.058). Meanwhile, the appetite-suppressive factors (proopiomelanocorein, pomc and cocaine and amphetamine regulated transcript, cart) gene expression was significantly down-regulated in fish fed the diet SF45 compared with the SBM45 group (P = 0.009, 0.006). The foregut α-amylase and trypsin activity were significantly promoted in fish fed the diet BS45 compared with those of the SBM45 and BA45 treatments (P = 0.000). There was a significant decrease in apparent digestibility coefficient of dry matter in fish fed the SBM45 diet compared with fish fed the control diet and fish fed either FSBM-based diet (P = 0.000), however, no significant difference was found among the control, SF45, BS45 and BA45 groups (P > 0.05). Moreover, no significant difference was observed in survival rate among dietary treatments (P > 0.05). Fish fed the diet BT45 had significantly lower feed efficiency than that of the control group (P = 0.048), meanwhile no significant difference was found among the control, SBM45, SF45, BS45 and BA45 treatments (P > 0.05). Fish fed the SBM45 diet had significantly lower specific growth rate compared with fish fed the control diet and fish fed either FSBM-based diet (P = 0.000). Furthermore, the antioxidant capacity significantly increased in fish fed the control and four FSBM diets compared with the SBM45 group (P < 0.05). The serum, liver and hindgut inflammatory responses of fish fed the control and four FSBM diets were significantly lower than those of the SBM45 group (P < 0.05). In conclusion, fish fed four FSBM diets could promote growth, enhance antioxidant capacity and reduce inflammatory responses of turbot juveniles compared with those of the SBM45 group.

Low specific growth rate and temperature in fed-batch cultures of a beta-propeller phytase producing Pichia pastoris strain under GAP promoter trigger increased KAR2 and PSA1-1 gene expression yielding enhanced extracellular productivity

Previously, we showed that the methylotrophic yeast Pichia pastoris (syn. Komagataella phaffii) could produce and secrete the beta-propeller phytase FTEII in an active form under the control of the AOX1 promoter and methanol as the inductor. In this work, we engineered P. pastoris strains to construct a constitutive P. pastoris expression system (GAP promoter) and extracellularly produce the phytase FTEII. We optimized the culture conditions to increase the extracellular volumetric phytase productivity (Qp) and evaluated the impact of the optimization process on the physiological response of the host. Moreover, we analyzed the expression levels of the FTEII gene and endogenous genes for P. pastoris cells in cultures with the lowest and highest Qp to understand which processes (from heterologous gene expression to protein secretion) might be responsible for the increase in Qp. The results indicate that a low specific growth rate and temperature in the fed-batch phase increases the Qp, which was correlated with an upregulation of the KAR2 and PSA1–1/MPG1 genes rather than increased heterologous gene transcription.

Quantification of tumor response of cystic vestibular schwannoma to Gamma Knife radiosurgery by using artificial intelligence.

Gamma Knife radiosurgery (GKRS) is a common treatment modality for vestibular schwannoma (VS). The ability to predict treatment response is important in patient counseling and decision-making. The authors developed an algorithm that can automatically segment and differentiate cystic and solid tumor components of VS. They also investigated associations between the quantified radiological features of each component and tumor response after GKRS. This is a retrospective study comprising 323 patients with VS treated with GKRS. After preprocessing and generation of pretreatment T2-weighted (T2W)/T1-weighted with contrast (T1WC) images, the authors segmented VSs into cystic and solid components by using fuzzy C-means clustering. Quantitative radiological features of the entire tumor and its cystic and solid components were extracted. Linear regression models were implemented to correlate clinical variables and radiological features with the specific growth rate (SGR) of VS after GKRS. A multivariable linear regression model of radiological features of the entire tumor demonstrated that a higher tumor mean signal intensity (SI) on T2W/T1WC images (p < 0.001) was associated with a lower SGR after GKRS. Similarly, a multivariable linear regression model using radiological features of cystic and solid tumor components demonstrated that a higher solid component mean SI (p = 0.039) and a higher cystic component mean SI (p = 0.004) on T2W/T1WC images were associated with a lower SGR after GKRS. A larger cystic component proportion (p = 0.085) was associated with a trend toward a lower SGR after GKRS. Radiological features of VSs on pretreatment MRI that were quantified using fuzzy C-means were associated with tumor response after GKRS. Tumors with a higher tumor mean SI, a higher solid component mean SI, and a higher cystic component mean SI on T2W/T1WC images were more likely to regress in volume after GKRS. Those with a larger cystic component proportion also trended toward regression after GKRS. Further refinement of the algorithm may allow direct prediction of tumor response.

Characterization of curly branch of Gracilariopsis lemaneiformis (Rhodophyta) at morphological, physiological, and molecular levels

Gracilariopsis lemaneiformis is an important commercial macroalgae. However, G. lemaneiformis strains with curly branches (CB), located at tertiary order with different phenotype when compared with those with normal branches (NB), were found in the cultivation region. This study investigated CB of G. lemaneiformis. The results revealed that CB exhibited loosely arranged epidermal cells with decreased number of layers; thickened cell wall of medullary cells; reduced plastids with loose lamellas; and lower specific growth rate, pigment contents, chlorophyll fluorescence parameters, and nucleic acid contents when compared with NB. Genes involved in plastid, pyrimidine, and purine biosynthesis as well as nitrogen metabolism were enriched, whereas those encoding small heat shock proteins (sHSPs) in the vicinity of transposable elements (TEs) were evidently down-regulated in CB. The morphological changes in CB might be caused by the alteration at microstructural level. The photosystem II (PSII) in CB presented weak light energy utilization ability and electron transfer activity, compared with that in NB, and the photosynthetic structure of CB may be damaged, which further exerted negative effect on photosynthetic intensity. The reduced plastid structure may be one of the reasons for the decreased photosynthetic intensity of CB. Genes encoding glutamine synthetase involved in nitrogen metabolism were down-regulated in CB, resulting in decrease in nucleic acids synthesis. Under certain stress condition, TEs in the vicinity of sHSPs genes were activated, leading to a decrease in sHSPs, causing loss of algal flexibility to cope with changes in the external environment. These results provided valuable information about irregular branches formation in G. lemaneiformis.

Effects of First Feeding Regime on Gene Expression and Enzyme Activity in Pikeperch (Sander lucioperca) Larvae

The present study investigates the effects of different feeding regimes with rotifers (Brachionus plicatilis) and Artemia salina on the gene expression and digestive enzymes in pikeperch (Sander lucioperca) larvae at 17 days post-hatch (DPH) over a period of 13 days. Five experimental feeding protocols were performed in four replicates. At 4 DPH, the larvae (total length= 5.62 ± 0.03 mm, body weight = 0.66 ± 0.16 mg) were divided into five experimental groups (2-L tanks) at initial density of 100 larvae per liter. Light intensity on the water surface was 90-100 lux and photoperiod was set at 13L: 11D (07:00 to 20:00 h). Water temperature, pH, and dissolved oxygen (DO) were measured before each feeding and the values were 17.8 ± 0.17°C, 7.3 ± 0.04 and 88.5 ± 2.53%. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8–13 DPH rotifers/14–17 DPH Artemia; (C) 8–10 DPH rotifers/11–17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Frozen paste of algae was added to the larval tanks twice a day (2 x 300,000 cells/mL). Rotifers and Artemia were provided as live feed to larvae three times a day with residual counts prior to each feeding. Feeding densities were steadily increased based on residual counts, performed prior to each feeding. The expression of genes related to intestinal development and maturation (aminopeptidase N, anpep; leucine aminopeptidase 3, lap3; intestinal-type alkaline phosphatase, alpi), together with key pancreatic digestive proenzymes (trypsinogen 1, try1; chymotrypsinogen b, ctrb; carboxyl ester lipase precursor, cel; phospholipase a2, pla2g1b; pancreatic alpha amylase, amy2a), were assessed. Additionally, the activity of six enzymes (trypsin, lipase, alkaline phosphatase, amino peptidase, amylase, and chymotrypsin) were determined. The highest expression of two genes related to intestine (lap3; anpep) were observed in the fish fed a combination of rotifers and Artemia from 8 DPH (Group E). The expression of amy2a, ctrb, pla2g1b, try1 was significantly lower in larvae fed rotifers until 14 DPH and replaced by Artemia afterwards (Group B). The specific activity of brush border membrane enzymes (alkaline phosphatase and aminopeptidase N) increased with combination of rotifers and Artemia in larval diet (Group E), indicating a more efficient functionality of digestive structures. The groups fed only with rotifers till 17 DPH (Group A) (38 ± 4.07%) and larvae fed with rotifers till 14 DPH followed by feeding with Artemia till 17 DPH (Group B) (36 ± 5.25%) showed significantly (P&amp;lt;0.05) lower survival rates than the other groups (54-67%). The group fed only with rotifers (Group A) showed significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding (Group E). The highest standard length (8.32 ± 0.48 mm) was obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Combination of rotifers and Artemia from 8 DPH (Group E) could be considered a more appropriate diet for first feeding pikeperch larvae compared with later introduction of Artemia, as indicated by the higher expression of genes and activities of digestive enzymes. Our findings provide new insight into the effect of temporal sequence of rotifers and Artemia on the expression of genes and activities of digestive enzymes in pikeperch larvae.

Interactions between multi-walled carbon nanotubes and plankton as detected by Raman spectroscopy

Raman spectroscopy has been commonly used in materials science to detect chemicals. Based on inelastic scattering of light after incident photons interact with a molecule, it has high potential for non-destructive detection of specific contaminants in living biological specimens. The increasing use of carbon nanotubes (CNTs) increases its chance to enter the aquatic habitats through direct discharge, surface runoff and atmospheric deposition, but their potential environmental impacts remain poorly known. We tested the use of Raman spectroscopy to investigate the interactions between multi-walled CNTs (MWCNTs) and aquatic plankton in vivo. For phytoplankton cells (Scenedesmus obliquus) that were exposed to MWCNTs, Raman spectroscopy was able to distinguish between background biological material and MWCNTs that adhere to the cells (G-band peak at 1590 cm−1 and D-band peak at 1350 cm−1 in the Raman spectra that were unique to MWCNTs). Harmful effects of MWCNT exposure manifested as lower photosynthetic efficiency and/or lower specific growth rate in the phytoplankton. MWCNT particles also adhered to the body surface of zooplankton, especially the carapace. Both Ceriodaphnia sp. and Daphnia sp. ingested MWCNTs directly, which was verified by the signature G-band and D-band Raman peaks in the zooplankton gut region. MWCNTs remained in the gut overnight after the zooplankton had been returned to clean water, showing that the zooplankton retained MWCNTs inside their body for an extended time, thereby increasing the chance to disperse and transfer the contaminants throughout the aquatic food web. Our results demonstrate that Raman spectroscopy is a promising method for non-destructive investigation of the uptake and dynamic fate of CNTs and other contaminants in aquatic organisms.