The Effects of Freshwater Clam (Corbicula fluminea) Extract on Activated Hepatic Stellate Cells

Background. The extract of freshwater clams has been used to protect the body against liver diseases in traditional folk medicine. This study aims at investigating the effects of freshwater clam extract on activated hepatic stellate cells (aHSCs), which are critical contributors to liver fibrosis. Methods. The aHSCs used in this study were derived from hepatic stellate cells that were isolated and purified from the livers of male Wistar rats and then transformed into the activated phenotype by culturing on uncoated plastic dishes. Freshwater clam extract (CE) was collected after the outflow from the live freshwater clams in a water bath at 100°C for 60 min. The effects of CE on aHSCs were analyzed by MTT assay, flow cytometry, Oil Red O (ORO) staining, western blot, and real-time RT-PCR. Results. The results indicated that CE suppressed the proliferation of aHSCs through G0/G1 cell cycle arrest by downregulating cyclin D1 and upregulating p27. The expression levels of a-SMA, collagen I, TGF-β, and TNF-α were inhibited in the CE-treated aHSCs. In addition, the CE treatment increased the lipid contents in aHSCs by promoting PPARγ expression. Furthermore, CE modulated the expression of ECM-related genes, i.e., by upregulating MMP-9 and downregulating TIMP-II. Conclusions. These data revealed that CE could induce the deactivation of aHSCs. We therefore suggest that CE has potential as an adjuvant therapeutic agent against hepatic fibrosis.

Homogenization of Macroinvertebrate Assemblages and Asiatic Clam Corbicula fluminea Invasion in a River of the Arid Patagonian Plateau, Argentina

The invasion of the Asiatic clam Corbicula fluminea in South America has already reached Patagonia. Despite the well-known direct and indirect impacts that this species exerts on fresh-water ecosystems, particularly on benthic communities, few studies have been undertaken on its effect on the composition and structure of aquatic macroinvertebrate assemblages. This study evaluated the effects of the invasion of the Asiatic clam C. fluminea on the aquatic macroinvertebrate assemblages of the Limay River, one of the most important rivers of the arid plateau of Argentinian Patagonia. As this river is currently in the process of being invaded, it was possible to compare invaded and non-invaded sites. Invaded sites displayed a certain homogenization of their constituent species and functional composition. Non-metric multidimensional scaling, similarity analysis and similarity percentages showed negative or positive influence of the presence of this species on the abundance of some taxa, due to competition for resources in this low-productivity Patagonian ecosystem. The deposition of the faeces and pseudo-faeces of C. fluminea enriches the organic content of the sediments. However, its pedal feeding can function as a competitive strategy: by consuming its own deposited organic matter when food is scarce, the amount available to other macroinvertebrates is reduced. This paper is the first contribution on the impact of this invasion on northern Patagonia’s aquatic macroinvertebrate assemblages.

Dissecting the chromosome-level genome of the Asian Clam (Corbicula fluminea)

The Asian Clam (Corbicula fluminea) is a valuable commercial and medicinal bivalve, which is widely distributed in East and Southeast Asia. As a natural nutrient source, the clam is rich in protein, amino acids, and microelements. The genome of C. fluminea has not yet been characterized; therefore, genome-assisted breeding and improvements cannot yet be implemented. In this work, we present a de novo chromosome-scale genome assembly of C. fluminea using PacBio and Hi-C sequencing technologies. The assembled genome comprised 4728 contigs, with a contig N50 of 521.06 Kb, and 1,215 scaffolds with a scaffold N50 of 70.62 Mb. More than 1.51 Gb (99.17%) of genomic sequences were anchored to 18 chromosomes, of which 1.40 Gb (92.81%) of genomic sequences were ordered and oriented. The genome contains 38,841 coding genes, 32,591 (83.91%) of which were annotated in at least one functional database. Compared with related species, C. fluminea had 851 expanded gene families and 191 contracted gene families. The phylogenetic tree showed that C. fluminea diverged from Ruditapes philippinarum, ~ 228.89 million years ago (Mya), and the genomes of C. fluminea and R. philippinarum shared 244 syntenic blocks. Additionally, we identified 2 MITF members and 99 NLRP members in C. fluminea genome. The high-quality and chromosomal Asian Clam genome will be a valuable resource for a range of development and breeding studies of C. fluminea in future research.

Antibiogram of Escherichia coli isolated from semi-closed system farmed Asian clam (Corbicula fluminea)

In the present study, antibiogram of Escherichia coli isolated from farmed Asian clam, Corbiculafluminea was characterised. Asian clam or locally known as ‘etak’ is processed to became smokedclam and consumed as snack by Kelantanese. However, there are many diarrhoea cases afterconsuming smoked clam. Furthermore, there are also insufficient information about the E.coli levelin Asian clam farm and effective antibiotic in controlling the bacteria in the litereature. Hence, thisstudy was carried out to provide information of antibiogram of E.coli to be reference in the future.Eosin Methylene Blue agar (EMB) was used to isolate E. coli. A total of 100 isolated bacteria weresubjected to antibiotic sensitivity test using disk diffusion method. A total of 18 types of antibioticsnamely novobiocin (30µg/disk), fosfomycin (50 µg/disk), tetracycline (30µg/disk), lincomycin(15µg/disk), flumequine (30µg/disk), sulphamethoxazole (25 µg/disk), amoxycillin (25 µg/disk),chloramphenicol (30 µg/disk), oleandomycin (15 µg/disk), spiramycin (100 µg/disk), ampicillin(10 µg/disk), oxytetracycline (30 µg/disk), doxycycline (30 µg/disk), nalidixic acid (30 µg/disk),florfenicol (30 µg/disk), erythromycin (15 µg/disk), kanamycin (30 µg/disk) and oxolinic acid (2µg/disk). The findings of the present study showed total plate count of E. coli was 6.45 x 103 colonyforming unit (CFU/100g) of sampled Asian clam. Hence, the clam is needed to be under cleansingtreatment before can consider safe for human consumption. Antibiotic results showed 51 % wasrecorded as antibiotic resistance case, 44 % antibiotic sensitive case and 5 % as antibioticintermediary sensitive case. None of the tested antibiotics was successfully inhibited the growth ofthe present bacterial isolates indicating more antibiotics are needed to be screen in the future studyto find out the most effective antibiotic in controlling isolated E. coli.

Effects of Feeding Treatments on Growth and Survival of Asian Clam (Corbicula fluminea) in the Hatchery

Asian clam (Corbicula fluminea) is potentially reared as aquaculture species but feeding regimes and nutrition for this clam remain questioned. The growth and survival of C. fluminea were evaluated with the assessment of feeding regimes raised in captive rearing treatments (with substrates) fed with spirulina (Arthrospira platensis). Three feeding methods were applied, Treatment A: deposit-feeding, Treatment B: suspension feeding, and Treatment C: combination deposit and suspension-feeding. Shell length (SL) and weight of the individuals were taken every 7 d which last for 6 wk. Condition index (CI), instantaneous growth rates of weight (Kw), and SL (KL) were determined after the experiment ends. Water parameters such as temperature (°C), pH, ammonia (NH4), and dissolved oxygen (DO) also being monitored along the experimental period. Significant weight gained (Kw) and CI was found higher in C. fluminea fed in Treatment C, where the increment was recorded at 6.24x10-3±2.4x10-3gday-1 and 4.34 ±0.3 respectively. Whereas, the increment of SL (KL) was insignificant in all treatments. Survival rates (SR) were greater than 95% in all treatments. The rearing conditions are significant factors that affect the feed utilization for their growth. The growth and survival indicate the specific feeding methods for captive C. fluminea and spirulina feasibility as their feed.