Generation of Eco-Friendly and Disease-Resistant Channel Catfish(Ictalurus punctatus)Harboring the Alligator Cathelicidin Gene via CRISPR/Cas9 Engineering

As a precise and versatile tool for genome manipulation,the clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9)platform holds promise for modifying fish traits of interest.With the aim of reducing transgene introgression and controlling reproduction,upscaled disease resistance and reproductive intervention in catfish species have been studied to lower the potential environmental risks of the introgression of escapees as transgenic animals.Taking advantage of the CRISPR/Cas9-mediated system,we succeeded in integrating the cathelicidin gene(As-Cath)from an alligator(Alligator sinensis)into the target luteinizing hormone(lh)locus of channel catfish(Ictalurus punctatus)using two delivery systems assisted by double-stranded DNA(dsDNA)and single-stranded oligodeoxynucleotides(ssODNs),respectively.In this study,high knock in(KI)efficiency(22.38%,64/286)but low ontarget events was achieved using the ssODN strategy,whereas adopting a dsDNA as the donor template led to an efficient on-target KI(10.80%,23/213).The on-target KI of As-Cath was instrumental in establishing the lh knockout(LH^(–)_As-Cath^(+))catfish line,which displayed heightened disease resistance and reduced fecundity compared with the wild-type(WT)sibling fish.Furthermore,administration of human chorionic gonadotropin(HCG)and luteinizing hormone-releasing hormone analogue(LHRHa)can restore the reproduction of the transgenic fish line.Overall,we replaced the lh gene with an alligator cathelicidin transgene and then administered hormone therapy to move towards complete reproductive control of diseaseresistant transgenic catfish in an environmentally responsible manner.This strategy not only effectively improves consumer-valued traits but also guards against unwanted introgression,providing a breakthrough in aquaculture genetics to confine fish reproduction and prevent the establishment of transgenic or domestic genotypes in the natural environment.

Thiosulfate oxidation and autotrophy potential by marine prevalent heterotrophic bacteria of genus Marinobacter

The genus Marinobacter is very broadly distributed in global environments and is considered as aerobic heterotroph.In this study,six Marinobacter strains were identified with autotrophic thiosulfate oxidation capacity.These strains,namely Marinobacter guineae M3B^(T),Marinobacter aromaticivorans D15-8PT,Marinobacter vulgaris F01^(T),Marinobacter profundi PWS21^(T),Marinobacter denitrificans JB02H27T,and Marinobacter sp.ST-1M(with a 99.93%similarity to the 16S rDNA sequences of Marinobacter salsuginis SD-14B^(T)),were screened out of 32 Marinobacter strains by autotrophic thiosulfate oxidization medium.The population of cells grew in a chemolithotrophic medium,increasing from 105 cells/mL to 10^(7) cells/mL within 5 d.This growth was accompanied by the consumption of thiosulfate 3.59 mmol/L to 9.64 mmol/L and the accumulation of sulfate up to 0.96 mmol/L,and occasionally produced sulfur containing complex particles.Among these Marinobacter strains,it was also found their capability of oxidizing thiosulfate to sulfate in a heterotrophic medium.Notably,M.vulgaris F01^(T)and M.antarcticus ZS2-30^(T)showed highly significant production of sulfate at 9.45 mmol/L and 3.10 mmol/L.Genome annotation indicated that these Marinobacter strains possess a complete Sox cluster for thiosulfate oxidation.Further phylogenetic analysis of the soxB gene revealed that six Marinobacter strains formed a separate lineage within Gammaproteobacteria and close to obligate chemolithoautotroph Thiomicrorhabdus arctica.The results indicated that thiosulfate oxidizing and chemolithoautotrophic potential in Marinobacter genus,which may contribute to the widespread of Marinobacter in the global ocean.

Impacts of the sampling design on the abundance index estimation of Portunus trituberculatus using bottom trawl

In the survey of fishery resources,the sampling design will directly impact the accuracy of the estimation of the abundance.Therefore,it is necessary to optimize the sampling design to increase the quality of fishery surveys.The distribution and abundance of fisheries resource estimated based on the bottom trawl survey data in the Changjiang River(Yangtze River)Estuary-Hangzhou Bay and its adjacent waters in 2007 were used to simulate the"true"situation.Then the abundance index of Portunus trituberculatus were calculated and compared with its true index to evaluate the impacts of different sampling designs on the abundance estimation.Four sampling methods(including fixed-station sampling,simple random sampling,stratified fixed-station sampling,and stratified random sampling)were simulated.Three numbers of stations(9,16 and 24)were assumed for the scenarios of fixed-station sampling and simple random sampling without stratification.While 16 stations were assumed for the scenarios with stratification.Three reaction distances(1.5 m,3 m and 5 m)of P.trituberculatus to the bottom line of trawl were also assumed to adapt to the movement ability of the P.trituberculatus for different ages,seasons and substrate conditions.Generally speaking,compared with unstratified sampling design,the stratified sampling design resulted in more accurate abundance estimation of P.trituberculatus,and simple random sampling design is better than fixed-station sampling design.The accuracy of the simulated results was improved with the increase of the station number.The maximum relative estimation error(REE)was 163.43%and the minimum was 49.40%for the fixed-station sampling scenario with 9 stations,while 38.62%and 4.15%for 24 stations.With the increase of reaction distance,the relative absolute bias(RAB)and REE gradually decreased.Resource-intensive area and the seasons with high density variances have significant impacts on simulation results.Thus,it will be helpful if there are prior information or pre-survey results about density distribution.The current study can provide reference for the future sampling design of bottom trawl of P.trituberculatus and other species.

Spatiotemporal factors affecting fish harvest and their use in estimating the monthly yield of single otter trawls in Putuo district of Zhoushan, China

We used generalized additive models (GAM) to analyze the relationship between spatiotemporal factors and catch, and to estimate the monthly marine fishery yield of single otter trawls in Putuo district of Zhoushan, China. We used logbooks from five commercial fishing boats and data in government's monthly statistical reports. We developed two GAM models: one included temporal variables (month and hauling time) and spatial variables (longitude and latitude), and another included just two variables, month and the number of fishing boats. Our results suggest that temporal factors explained more of the variability in catch than spatial factors. Furthermore, month explained the majority of variation in catch. Change in spatial distribution of fleet had a temporal component as the boats fished within a relatively small area within the same month, but the area varied among months. The number of boats fishing in each month also explained a large proportion of the variation in catch. Engine power had no effect on catch. The pseudo-coefficients (PCf) of the two GAMs were 0.13 and 0.29 respectively, indicating the both had good fits. The model yielded estimates that were very similar to those in the governmental reports between January to September, with relative estimate errors (REE) of <18%. However, the yields in October and November were significantly underestimated, with REEs of 36% and 27%, respectively.

Impacts of sampling design on the abundance estimation of Portunus trituberculatus using crab pots

Fishery-independent surveys can provide high-quality data and support fishery assessment and management.Optimization of sampling design is crucial to increase the quality of fishery surveys.Crab pots are important fishing gears used to catch crabs.We analyzed the impacts of sampling design of crab pots on the abundance of Portunus trituberculatus in the Changjiang(Yangtze)River estuary to the Hangzhou Bay and its adjacent waters in East China Sea.The crab pots were cylindrical,240 mm in height and 600 mm in diameter of the iron ring.Our sampling designs(including fixed-station sampling,simple random sampling,stratified fixed-station sampling,and stratified random sampling),three number of stations(9,16,and 24),and three numbers of crab pots(500,1000,and 3000)were simulated and compared with the“true”abundance that obtained from bottom trawl surveys in the study area in 2007.The scenarios with 16 stations were set in stratification as a control group for comparison with unstratified designs.Results show that simple random sampling can obtain more stable results than fixed-station sampling in the abundance estimation of P.trituberculatus.In addition,stratified sampling resulted in more accurate abundance than unstratified sampling.The accuracy of the simulated results improved with the increase of the number of stations.No remarkable differences in the results were found among the scenarios of different number of crab pots at each station.However,resource-intensive areas exerted great impacts on simulation results.Thus,prior information or pre-survey results about resource abundance and density distribution are necessary.This study may serve as a reference for future sampling designs of crab pots of P.trituberculatus and other species.

Commercial Production of Tiger Puffer(Takifugu rubripes)in Winter Using a Recirculating Aquaculture System

Tiger puffer(Takifugu rubripes) is a promising species for aquaculture production because of its high value and limited supply. However, in the north of China, using sea cages to culture this species in winter is hampered by the fact that the seawater temperature is extremely low. Here, a large scale commercial production of tiger puffer has been successfully realized using a recirculating aquaculture system(RAS) from 3 October 2012 to 31 May 2013. The RAS was comprised of nine culture tanks(total water volume 200 m3) and stocked with approximately a total of 14400 fish(initial mean weight 160 g). The tiger puffer was hand-fed at a rate of 0.7% of total body weight per day, and the feed conversion rate was(1.21 ± 0.3) kg kg-1. The recycle water in RAS was treated by a sieve bend screen, a foam fractionator, a submerged biofilter, an UV sterilizer and a submersible aerator. During the whole culture period, an excellent water quality control was achieved in RAS. At the end of this experiment, the survival rate of tiger puffer was more than 98%. The final tank densities averaged 31.2 kg m-3, and the final individual mean weight was 440 g.

Identification of metastasis-associated genes in colorectal cancer through an integrated genomic and transcriptomic analysis

Objective： Identification of colorectal cancer （CRC） metastasis genes is one of the most important issues in CRC research. For the purpose of mining CRC metastasis-associated genes, an integrated analysis of mJcroarray data was presented, by combined with evidence acquired from comparative genornic hybridization （CGH） data. Methods： Gene expression profile data of CRC samples were obtained at Gene Expression Omnibus （GEO） website. The 15 important chromosomal aberration sites detected by using CGH technology were used for integrated genomic and transcriptomic analysis. Significant Analysis of Microarray （SAM） was used to detect significantly differentially expressed genes across the whole genome. The overlapping genes were selected in their corresponding chromosomal aberration regions, and analyzed by using the Database for Annotation, Visualization and Integrated Discovery （DAVID）. Finally, SVM-T-RFE gene selection algorithm was applied to identify ted genes in CRC. Results： A minimum gene set was obtained with the minimum number [14] of genes, and the highest classification accuracy （100%） in both PRI and META datasets. A fraction of selected genes are associated with CRC or its metastasis. Conclusions- Our results demonstrated that integration analysis is an effective strategy for mining cancer- associated genes.

Karacoline,identified by network pharmacology, reduces degradation of the extracellular matrix in intervertebral disc degeneration via the NF-κB signaling pathway

Karacoline is a compound found in the plant Aconitum kusnezoffii Reichb.Although Aconitum kusnezoffii Reichb is widely used for the treatment of pain,very few studies have been carried out on the use of karacoline due to its potential toxicity.In this study,we selected key matrix metalloproteinases(MMPs),collagen II,and aggrecan as targets due to their association with intervertebral disc degeneration(IDD).Using these targets,we then used network pharmacology to predict a series of molecules that might exert therapeutic effects on IDD.Of these molecules,karacoline was predicted to have the best effect.Tumor necrosis factor(TNF)-a is known to promote the degeneration of the extracellular matrix in IDD.We therefore applied different concentrations of karacoline(0,1.25,or 12.88 mM)along with 100 ng/mL TNF-a to rat nucleus pulposus cells and found that karacoline reduced the expression of MMP-14 in IDD by inhibiting the nuclear factor(NF)-κB pathway,while collagen II and aggrecan expression was increased.This suggested that extracellular matrix degradation was inhibited by karacoline(P<0.05).Our data therefore reveal a new clinical application of karacoline and provide support for the use of network pharmacology in predicting novel drugs.

Internal Microanatomy and Zoological Affinity of the Early Cambrian Olivooides

The early Cambrian pentamerous microfossil Olivooides/Punctatus in South China, which is characterized by a diagnostic stellate tubular apex, has been well-known for its almost complete development sequence that can be confidently traced from embryos and hatched juveniles, to conical adults. However, its zoological affinity remains highly controversial. Here we describe the internal microanatomic structures of the soft-body inside the peridermal theca of Olivooides multisulcatus Qian, 1977, including interradial pairs of tentacles, adradial and perradial frenula, perradial oral marginal lappets and twins of perradial gastric saccule-like humps as well as a circular velarium with striated coronal muscles. Particularly, one specimen shows bifurcated velarial canals along the bell aperture. Both the components of the soft-body and the external theca （or cyst） are arranged in perfect pentaradial symmetry. These characteristics are more compatible with those of living cubomedusans and co-occurring Cambrian athecate embryonic cubozoans. Concerning the presence of peridermal theca, Olivooides most likely represents an extinct thecate stem-group cubomedusae but devoid of both perradial eyes and specialized pedalia. The well-grown soft body inside the peridermal tube displays a set of mixed features of both polyp and medusa.

Mitochondrial DNA control region diversity and population structure of Pacific herring(Clupea pallasii)in the Yellow Sea and the Sea of Japan

To investigate the genetic variation and population structure of Pacific herring in the Yellow Sea and the genetic differentiation between the Yellow Sea and the Sea of Japan, fragments of 479-bp mitochondrial DNA control region were sequenced for 110 individuals collected from three different periods in the Yellow Sea and one locality in the Sea of Japan. High haplotype diversity and moderate nucleotide diversity were observed in Pacific herring. AMOVA and exact test of population differentiation showed no significant genetic differentiations among the three populations of the Yellow Sea and suggested the populations can be treated as a single panmictic stock in the Yellow Sea. However, a large and significant genetic differentiation （ФST=0.11; P=0.00） was detected between the populations in the Yellow Sea and the Sea of Japan. The high sea water temperature in the Tsushima Strait was thought a barrier to block the gene exchange between populations of the two sea areas. The neutrality tests and mismatch distribution indicated recent population expansion in Pacific herring.

An Evaluation on the Ratio of Plant to Animal Protein in the Diet of Juvenile Sea Cucumber(Apostichopus japonicus):Growth,Nutrient Digestibility and Nonspecific Immunity

This study was conducted to evaluate the effects of plant/animal(P/A) protein ratios(viz.1:4, 1:3, 1:2, 1:1,2:1, 3:1, 4:1) on growth performance, body composition, apparent digestibility of diets, and nonspecific immunity of juvenile sea cucumber(Apostichopus japonicus). Sea cucumbers were divided into 21 plastic tanks, and each tank was stocked with 15 individuals(initial weight: about 23.73 g). Each feed was allocated to three replicates of sea cucumbers. The feeding experiment lasted for 50 days. Results indicated that weight gain rate(WGR) and body wall weight(BWW) significantly increased as dietary ratio of P/A increased from 1:4 to 3:1, and then decreased significantly with further increase of this ratio(P < 0.05). The body wall coefficient(BWC) showed a similar tendency to WGR and BWW, but no significance was detected among dietary treatments(P > 0.05). The apparent digestibility of dry matter, protein and lipid increased with ratio of P/A increasing from 1:4 to 2:1(P < 0.05), and then decreased with further increase of this ratio. Correspondingly, activities of trypsin and amylase were significantly increased as P/A increased from 1:4 to 2:1(P < 0.05). The activities of SOD and CAT showed a similar trend with WGR, with the highest value observed in the ratio of 1:2 and 1:1, respectively. Results above showed that moderate or relatively higher ratio of P/A protein(1:1-3:1) significantly increased the growth performance, apparent digestibility, and nonspecific immunity of sea cucumber. This will contribute to improving the feed formulation for juvenile cucumbers.

Genetic variation within and among range-wide populations of three ecotypes of the Japanese grenadier anchovy Coilia nasus with implications to its conservation and management

Studies of range-wide populations can contribute to the comprehension of the relative roles of historical events and contemporary factors that influence genetic variation within and among populations.Japanese grenadier anchovy,Coilia nasus,is a commercially important fish,which widely distributes in the Changjiang River,the coasts of China and Korea,and the Ariake Sea of Japan.This species exhibits three life-history strategies(anadromous,landlocked and freshwater resident forms).Using two fragments of nuclear DNA,genetic variation within and among 18 populations across the rivers and coast of China and Ariake Sea of Japan was examined.Patterns of genetic diversity and divergence among populations varied widely across C.nasus'range,and indicated the different effects of historical events and anthropogenic factors.Strong genetic divergence between freshwater resident populations and other populations suggested that historical geographical factors greatly influenced the genetic structure of C.nasus.Significant genetic differentiation observed among lakes in lower Changjiang River and Huaihe River might be probably influenced by hydraulic facilities.The population genetic structure among the three ecotypes revealed in the present study indicated an important role for environment variation,and the factors responsible for shaping C.nasus different life history strategies might also impact population structure.

Reproductive biology of Schizopygopsis younghusbandi Regan 1905(Cyprinidae:Schizothoracinae)in the middle reaches of Yarlung Tsangpo River,China

The reproductive biology of Schizopygopsis younghusbandi(Cyprinidae: Schizothoracinae) was studied by 719 individuals that collected from August 2008 to August 2009 in the middle reaches of Yarlung Tsangpo River, China. We coupled monthly variations of the gonadosomatic index(GSI), monthly proportions of the macroscopic maturity stages with size distribution of oocytes to evaluate spawning seasons. Taken as a set, these results indicated that S. younghusband i spawned from March to April with high degree of the spawning synchronicity. The standard lengths and the ages at 50% maturity for male were 222 mm and 4.4 year, and 308 mm and 7.0 year for female. In addition, the estimated mean fecundity and mean relative fecundity were 18682 and 57.8 eggs per g body weight. The fecundity of S. younghusbandi increased linearly with increasing of standard length and body weight. This study provides details about the S. younghusbandi reproduction suggesting that may be this species is vulnerable to exploitation in the middle reaches of Yarlung Tsangpo River.

Continuous Saccharification of Laminarin by Immobilized Laminarinase ULam111 Followed by Ethanol Fermentation with a Marine-Derived Yeast

We isolated a novel laminarinase ULam111 from Flavobacterium sp. strain UMI-01. Purified ULam111 showed degradation activity against laminarin with the specific activity of 224 ± 18 U/mg at 30°C and pH 6.0. Its optimum temperature was 50°C, and degradation activities against laminarin were observed at 4°C - 80°C. With a laminarin degradation system, we investigated the preparation and properties of immobilized ULam111 with the use of the 11 types of carriers. The high activity recoveries of immobilized ULam111 were as follows: 19.4% for IB-S60P carrier beads (the non-ionic type), 15.6% for IB-S60S carrier beads (the non-ionic type), 11.9% for IB-150P carrier beads (the covalent type), and 7.1% for IB-C435 carrier beads (the cationic type). With the repeated use of immobilized ULam111, the enzyme activities immobilized on IB-S60S and those on IB-S60P remained at 40% and 30% respectively after the sixth trial. We selected IB-S60S as suitable beads for enzyme immobilization, and we attempted to construct a reactor system with ULam111 immobilized on IB-S60S beads. In this system, 1.2 - 1.9 g/L glucose was repeatedly produced from 30 mg/mL laminarin solutions after 20 hr when the reactor operation was repeated 10 times. We examined ethanol fermentation from the saccharified solutions with a marine-derived yeast (Saccharomyces cerevisiae C-19), and 0.51 - 0.58 g/L bioethanol was produced from the saccharified solution that contained 1.71 - 1.86 g/L of glucose.

The Study of Visible Implant Elastomer(VIE)Tag on Small-sized Chinese Shrimp(Fenneropenaeus chinensis)

[ Objective] The paper was to prove the feasibility of using visible implant elastomer （VIE） tags to mark Chinese shrimp of about 1 em in length. [Method] In June 2014, 2 856 Chinese shrimps with an average length of 1.14 cm were tagged with red VIE. After temporary rearing for one day, 2 321 tagged shrimps were cultured in the same pond with 60 000 untagged shrimps in this experiment. In predation test, spottedtail gobies （Synechogobius ommaturus） were se- lected as the predator, and the predation rate of spottedtail gobies on small-sized Chinese shrimps was measured. [ Result] On September 21,2014, 206 kg of Chi- nese shrimp was harvested in the pond. There were 389 tagged shrimps, with an average body weight of 16.84 g, and an average length of 11.15 cm. The untagged shrimps had an average body weight of 17.08 g, and average length of 11.23 cm. The results indicated that there was no significant difference in growth between the tagged and untagged shrimps. The survival rate of the tagged shrimps was 2.7% lower than the untagged ones. Mthough the fluorescent tag dispersed and the posi- tion changed, the tag was still distinct both under ultraviolet light and to the naked eye. The predation test revealed that the fluorescent tag of shrimps did not in- crease the predation rate by spottedtail gobies. [ Conclusion] Red VIE tagging is feasible in Chinese shrimps. There was no significant difference in predation rate between untagged and VIE tagged shrimps.

Maximum sustainable yield estimation of enhancement species with the characteristics of movement inside and outside marine ranching

Marine ranching can be regarded as a type of artificial fishery,and its construction aims at the sustainable utilisation of fishery resources.Therefore,the sustainable yield level of target species in marine ranching has become one of the concerns of stakeholders.The enhancement surplus production model proposed by Wang(2021)based on the traditional surplus production model can be used to assess the sustainable utilisation of settled species in marine ranches.However,when the target species has the characteristics of migration inside and outside marine ranches,its sustainability assessment will be aff ected.Based on the movement range and resource density levels of enhancement species inside and outside marine ranches,we built a biomass change model that is suitable for enhancement species with migration characteristics inside and outside marine ranches(migration enhancement biomass model).Moreover,we simulated the effects of factors,such as the ratio of the movement range and the ratio of resource density within and outside marine ranches and the fishing strategy for the enhancement species in marine ranches,on the estimation of maximum sustainable yield(MSY).Results show that the large movement range of enhancement species outside marine ranches was associated with the obvious advantage of the proposed migration enhancement model over the traditional enhancement production model.A small difference in the densities of enhancement species inside and outside marine ranches was highly beneficial for improving the accuracy of MSY estimation.The migration enhancement biomass model proposed in this study provides an idea for estimating the MSY of an enhancement species that migrates inside and outside marine ranches.Researchers can adjust the parameters of the model in accordance with the actual situation of resource distribution and changes to improve the scientificity of fishery stock assessment.

Involvement of Cbl-b-mediated macrophage inactivation in insulin resistance

Aging and overnutrition cause obesity in rodents and humans. It is well-known that obesity causes various diseases by producing insulin resistance(IR). Macrophages infiltrate the adipose tissue(AT) of obese individuals and cause chronic low-level inflammation associated with IR. Macrophage infiltration is regulated by the chemokines that are released from hypertrophied adipocytes and the immune cells in AT. Saturated fatty acids are recognized by toll-like receptor 4(TLR4) and induce inflammatory responses in AT macrophages(ATMs). The inflammatory cytokines that are released from activated ATMs promote IR in peripheral organs, such as the liver, skeletal muscle and AT. Therefore, ATM activation is a therapeutic target for IR in obesity. The ubiquitin ligase Casitas b-lineage lymphoma-b(Cbl-b) appears to potently suppress macrophage migration and activation. Cbl-b is highly expressed in leukocytes and negatively regulates signals associated with migration and activation. Cbl-b deficiency enhances ATM accumulation and IR in aging- and diet-induced obese mice. Cbl-b inhibits migration-related signals and SFA-induced TLR4 signaling in ATMs. Thus, targeting Cbl-b may be a potential therapeutic strategy to reduce the IR induced by ATM activation. In this review, we summarize the regulatory functions of Cbl-b in ATMs.

Metabolic and physiological regulation of Chlorella sp.(Trebouxiophyceae, Chlorophyta) under nitrogen deprivation

A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic effciency, biochemical pro?les and non-targeted metabolic pro?ling were studied to compare between the nitrogen-replete and deplete conditions. Slowed growth, change in photosynthetic pigments and lowered photosynthetic effciency were observed in response to nitrogen deprivation. Biochemical pro?les of the cultures showed an increased level of carbohydrate, lipids and total fatty acids, while the total soluble protein content was lowered. A trend of fatty acid saturation was observed in the nitrogen-deplete culture with an increase in the level of saturated fatty acids especially C16:0 and C18:0, accompanied by a decrease in proportions of monounsaturated and polyunsaturated fatty acids. Fifty-nine metabolites, including amino acids, lipids, phytochemical compounds, vitamins and cofactors were signi?cantly dysregulated and annotated in this study. Pathway mapping analysis revealed a rewiring of metabolic pathways in the cells, particularly purine, carotenoid, nicotinate and nicotinamide, and amino acid metabolisms. Within the treatment period of nitrogen deprivation, the key processes involved were reshu ? ing of nitrogen from proteins and photosynthetic machinery, together with carbon repartitioning in carbohydrates and lipids.

Ontogenetic changes in feeding and food preferences of the dog conch Laevistrombus canarium Linnaeus 1758 (Mollusca： Gastropoda) from Merambong shoal, Malaysia

Laevistrombus canarium is one of the marine gastropod mollusks that have high commercial value, particularly in the aquaculture sector in Malaysia. This study was conducted to determine the feeding and food items of L. canarium at different ontogenetic stages （juveniles, sub-adults and adults） from Merambong shoals, Malaysia. Field observations on feeding activity were conducted, followed by detailed laboratory analysis on the stomach content. Five-minutes observations on randomly selected individuals were conducted at the field sampling site and their feeding activities were recorded with reference to age stage. Various shell sizes from each ontogenetic stage were randomly collected and quickly anaesthetized with ice and preserved in 10% formalin before being transported to the laboratory for stomach content analyses. Field observations showed that L. canarium mainly grazed on epiphytes occurring on seagrass （46.67%）, followed by sediment surface （40%） and epiphytes occurring on macroalgae （13.33%）. Stomach content analyses showed a significant difference （P〈0.05） in gastro-somatic index （Gasi） between the juveniles （0.39±0.05）, sub-adults （0.68±0.09） and adults （0.70±0.05） （P〈0.05）. Food items found in the conch stomach include diatoms, detritus, foraminifera, seagrass and macroalgae fragments, sand particles and shell fragments. The Index of Relative Importance （%IRI） indicates three main types of food dominated the three ontogenetic stages namely diatoms, sand particles and detritus. However, no significant difference （P〉0.05） was detected between the three main food items （diatoms, sand particles and detritus） among the ontogenetic stages. Therefore, feeding activity revealed the role of the dog conch in the marine food network. While, classification of the types of food consumed by L. canarium through stomach content analysis determines the particular position of the gastropod in the food chain. Further studies are needed to provide a better insight between trophic relationships ofL. eanarium with marine ecosystem.

Growth, Proximate Composition and Pigment Production of Tetraselmis chuii Cultured with Aquaculture Wastewater

Microalgae are cultured commercially as healthy food, cosmetic products, food preservatives, and a source of valuable compounds. However, the high cost of commercial culture medium is one of the challenges to microalgal production. Therefore, it is essential to find an alternative cost-effective culture medium. Aquaculture wastewater is considered as a highly potential candidate due to its high nutrient content and large quantity generated from the rapid growth of aquaculture sector. In this study, Tetraselmis chuii cultured in different media with or without wastewater was evaluated for its growth, proximate composition and carotenoid production. The results showed that significantly(P < 0.05) higher growth(4.3 × 105 cells mL^(-1)) and protein(56.4% dry weight), lipid(44% dry weight) and carbohydrate(20% of dry weight) contents were found in T. chuii when they were cultured in the combination of both wastewater and Conway(wastewater + Conway) medium. However, carotenoid production of T. chuii was significantly increased(P < 0.05) when it was cultured in wastewater only, followed by Conway + wastewater and Conway medium only. Therefore, the incorporation of wastewater with commercial medium Convey is recommended for a cost-effective microalgae culture, as well as for the enhancement of growth and nutritional content of microalgae.