Proximate composition and elemental analysis in soft tissues of freshwater mussels （Anodonta anatina） from the Chashma Lake, River Indus Pakistan

BACKGROUND： Aquatic invertebrates are playing an important role in assessment of the water contaminants and also serve as a major component of food chain. Freshwater mussels are considered to be the good bioindicator species of aquatic environment and widely used to determine the metals load. METHODS： Proximate composition and elemental analysis were carried out in edible （foot, mantle） and non-edible portion （gills） of freshwater mussels （Anodonta anatina） harvested from various site of Chashma Lake, River Indus Pakistan. RESULTS： The nutritional components were varied among the studied portion and muscular foot found to be the best part for consumption. Protein and fat contents were significantly higher in foot （15.90±0.88%, 1.19 ±0.26%） as compared to mantle （10.78±2.24%, 0.27±0.09%） and gills （6.44± 1.22%, 0.53 4-0.15%） respectively. For the macro minerals mantle had high concentration of Ca （46838±984 mg/kg）, Na （2706±343 mg/kg）, P （6921± 1063 mg/kg） and Mn （7207± 1046 mg/kg） as compared to foot. CONCLUSIONS： Heavy metals （Cd, Cu, Cr） concentration in edible portions were lower than the permissible limit by WHO whereas the concentration of Pb was slightly higher than the recommended value that might be the risk for the consumers. Being filter feeder gills accumulated the high concentration of all the metals and found to be the key portion for biomonitoring studies. Freshwater mussels of Chashma Lake Indus River are the rich source of protein and all the other micro and macro minerals therefore could be used as an excellent source of food.

Optimization of the ultrasonic-microwave assisted enzymatic hydrolysis of freshwater mussel meat

In the present study,the Ultrasonic-Microwave(US-MW)technique was applied for assisting enzymatic hydrolysis of freshwater mussel meat.The operating parameters of enzymatic hydrolysis were investigated and the properties and qualities of the freshwater mussel hydrolysates were also analyzed.The considerable optimum conditions for enzymatic hydrolysis of mussel meat were ratio of liquid to material of 10.36:1,power of 360.52 W,processing time of 6.91 min,enzymolysis time of 4 h.Under these conditions,a degree of hydrolysis(DH)of 48.40% was obtained.The hydrolysates produced under optimum conditions,were characterized in terms of electrophoretic profile,amino acid composition and infrared spectrum analysis.SDS-PAGE profiles of the hydrolysates revealed that several protein bands were cleaved and several light myosin chains(25 kDa and 15 kDa,respectively)and peptides of molecular weight lower than 6.5 kDa were identified.The infrared spectrum absorption peak of amide band A and band III shifted after US-MW pre-treatment,which indicated that the N-H(hydrogen bonding)stretching vibration and triple helix structure of samples were affected.The essential amino acids in hydrolysates with or without US-MW pre-treatment were 36.62 mg/100 g and 33.40 mg/100 g.It was proved that US-MW assisted enzymatic hydrolysis is an effective technology to utilize freshwater mussel meat.

Occurrence and fate of chlorinated methylsiloxanes in surrounding aqueous systems of Shengli oilfield, China

Mono-chlorinated products of cyclic volatile methylsiloxanes(cVMS),i.e.,Monochlormethylheptamethylcyclotetrasiloxane[D3D(CH_(2)Cl)],monochlormethylnonamethylcyclopentasiloxane[D4D(CH_(2)Cl)],and monochlormethylundemethylcyclohexasiloxane[D5D(CH_(2)Cl)],were detected in water[<LOQ(Limit of quantitation)-86.3 ng/L,df(detection frequency)=23%-38%,n=112]and sediment samples[<LOQ-504 ng/g dw(dry weight),df=33%-38%,n=112]from 16 lakes located in Shengli oilfield of China,and had apparent increasing trends(31%-34%per annum)in sediments during Year 2014-2020.Simulated experiments showed that chloro-cVMS in sediment-water system had approximately 1.7-2.0 times slower elimination rates than parent cVMS.More specifically,compared with those of parent cVMS,volatilization(86-2558 days)and hydrolysis(135-549 days)half-lives of chlorocVMS were respectively 1.3-2.0 and 1.8-2.1 times longer.In two species of freshwater mussels(n=1050)collected from six lakes,concentrations of chloro-cVMS ranged from 9.8-998 ng/g dw in Anodonta woodiana and 8.4-970 ng/g dw in Corbicula fluminea.Compared with parent cVMS,chloro-cVMS had 1.1-1.5 times larger biota-sediment accumulation factors(2.1-3.0)and 1.1-1.7 times longer half-lives(13-42 days).Their stronger persistence in sediment and bioaccumulation in freshwatermussels suggested that environmental emission,distribution and risks of chloro-cVMS deserve further attention.

Hic74,a novel alanine and glycine rich matrix protein related to nacreous layer formation in the mollusc Hyriopsis cumingii

Organic matrix proteins play an important role in the biomineralization of mollusc shells.We have identified and characterized a novel matrix protein,namely hic74,isolated from the mantle of the freshwater mussel Hyriopsis cumingii.The hic74 gene encodes a 850 amino acid protein that is rich in alanine(ala,30.8%),glycine(gly,25.8%)and serine(ser,10.6%),with ala mainly existing in poly-ala forms within the ala/gly-rich regions.Quantitative PCR expression analysis demonstrated that hic74 was specifically amplified from the mantle and in situ hybridization showed a strong signal in the epithelial cells in the pallial region of the mantle.Lower levels of expression were detected during the early stages of pearl sac formation but increased and remained constant during nacreous layer formation suggesting that hic74 might be involved in this process.

Cloning of a microphthalmia-associated transcription factor gene and its functional analysis in nacre formation and melanin synthesis in Hyriopsis cumingii

Microphthalmia-associated transcription factor(MITF)is an essential transactivator in melanin synthesis.To characterize the role of MITF in the pearl mussel Hyriopsis cumingii,the MITF homolog of H.cumingii was isolated.The full-length HcMitf cDNA consisted of a 1332-bp with an open reading frame that encode for a 443 amino acid protein that contain a conserved basic helix-loop-helix zipper domain.The HcMitf was found to widespread tissue distribution but expression was higher in purple mussels than in white mussels,mostly in mantle,liver,kidney,gill,and foot with the exception of the adductor mussel.HcMitf and its downstream gene tyrosinase(HcTyr)were highly expressed at the nacre deposition stage after implantation of mantle tissue to produce pearls.Using RNA interference,the expression of HcMitf was reduced by 78%(P<0.01)and expression of HcTyr was also significantly suppressed and consequently total melanin content was decreased(P<0.05).The results suggest that HcMitf plays an important role in melanin synthesis,nacre formation and shell pigmentation in the H.cumingii.