Effect of the parasitic isopod,Catoessa boscii(Isopoda,Cymothoidae),a buccal cavity parasite of the marine fish,Carangoides malabaricus

Objective:To examine the effect of isopod parasite Catoessa boscii(C.boscii)on Carangoides malabaricus(C.malabaricus).Methods:The host fish C.malabaricus infested by C.boscii were collected directly from the trawlers landed at Parangipettai coast during December 2008 to November2009.Data regarding the total length,width,weight and sex of the host fish were recorded.Effect of infestation on C.malabaricus,the length and weight data were analysed and host specificity of isopods was also examined.Results:During the sampling period,585 C.malabaricus were examined.Among them,218 specimens were found to carry 243 parasites.Three pairs of isopods(one male with one female)were recorded from the host fish and each pair was attached to the tongue in the buccal cavity of the host.Another pair was also found where the male and male,female and female isopod had settled on the tongue in the buccal cavity.Gross lesions observed in the buccal cavity of infested fish showed small pin-holes in the tongue region,through which dactyls of pereopod's penetrating claws dig into the host tissues.The maximum weight loss was reported in females(5.43%)than in males(3.75%)of C.malabaricus.Due to infestation of different isopod parasites in both male and female fish,the effects on the length-weight relationship of C.malabaricus were compared.The rate of increased growth in weight in uninfested female fish was found to be higher than that of the infested.The weight gain is faster in uninfested fish than in the infested fish.Conclusions:From the above mentioned observations,it is clear that the worst of fish on account of the infestation of isopods are the C.malabaricus succumbed to the attack of isopod parasites.Although,the infestation did not cause immediate death,it had affected the normal growth of the host fish.

Preliminary studies for a new antibiotic from the marine mollusk Melo melo(Lightfoot,1786)

Objective:To search for new bioactive compounds from marine mollusks Melo melo(M.melo). Methods:Preliminary work for bioactive compound was identified by using disc diffusion methods against human pathogens.Further analyses of compound were done by using TLC, SDS-PACE.And also estimate the amount of protein in the samples by following Biuret method.Results:In antibacterial activity the maximum diameter of 24 mm zone of inhibition was recorded against Klebsiella pneumoniae(K.pneumoniae) strain of the mucus extract and minimum zone of inhibition of 11 mm was observed in Salmonella typhi(S.typhi) strain of body tissue extract.The antifungal activity of the extraction shows maximum activity against Trichophyton mentagarophytes(T.mentagarophytes)(14 mm) and minimum activity was recorded in Aspergillus flavus(A.flavus)(11 mm).The extract of mucus,nerve tissue,body tissue and kidney that showed antimicrobial activity was subjected to TLC to determine the presence of the peptides and amide groups,and also subjected to SDS-PACE to estimate the molecular weight of proteins in a clear band were detected in the gel that represented kidney,body tissue,brain and mucus represent 14,17,22,45 kDa.Conclusions:The extracts from marine mollusks M.melo is the potential source of producing bioactive compounds against human pathogens and can be used for synthesis of new drugs.

Invasion of parasitic isopods in marine fishes

Objective:To carry out a detailed three-year observation study on isopod parasites infestation in fish.Methods:Fish samples were collected from different localities in various landing centers along the Tamil Nadu coastal area.The prevalence and mean intensity were calculated.The proximate composition of infestation and uninfestation were studied in different marine fishes.A comparative analysis of bacteria and fungi in the infected and uninfected regions of fishes were analysed.Results:Tweenty six species including 12 genera of isopods(Cymothoidae)distributed in 39 species of marine fishes along the Tamil Nadu coast.The isopod parasites were attached in three different microhabitats in host fishes viz.,buccal,branchial and body surfaces.They exhibited host and site specific occurrence.Maximum prevalence 17.11%was recorded in March 2010 and minimum 0.27%in Febuary 2010.The intensity ranged from 1 to 1.7 parasites per fish during the different months from Decmber 2008 to November 2011.There was a decrease in the protein,carbohydrate and lipid content in the infested fishes compared to uninfected fishes.A comparative analysis of bacteria and fungi in the infected and uninfected region of fishes were analysed.It revealed that infected portions had dense bacterial load as observed in the lesions of infected fishes than uninfected fishes.Conclusion:Factors which are able to induce parasitic manifestation are stock quality,stocking density,environmental conditions,biological and physiological characteristics of parasite,zoo technical measures,food quantity,feeding strategies,etc.

Histopathological changes in the skins and gills of some marine fishes due to parasitic isopod infestation

Objective:To study the histopathological symptoms owing to cymothoid isopod that were categorised as gross lesions.Methods:Nature of damage fish tissues and gills were taken from the parasite attachment area of infested and uninfested fishes which were cut out in fresh condition fixed in 10%buffered neutral formalin.Fresh and recently preserved tissues and gills were washed in tap water and dehydrated using alcohol series.The tissues gills were then cleaned in methylbenzoate and benzene and embedded in paraffin wax.The serial sections cutting 4 to 5 m thickness,were stained with Erlich’s haematoxylin and Eosin for histopathological analysis.Results:In normal muscle tissue,the tensile strength of muscle fibers with extra cellular matrix collagen was extensively tight associated.This gave a rigid musculature pattern to the tissues.Infested fish exhibited histopathological anomalies such as tissue reactions,primarily associated with the formation of granulomas consisted of macrophages and epitheleioid cells,which were occasionally surrounded by a thin rim of fibroblasts.The infestations such as lipofibrosis,hyperaemia,haemorhagic lesions and penetration of dactylus usually pressure atrophy often accompanied by the presence of parasites.Lesions had well developed granulomas that underlined in the muscle or overlying subcutaneous tissue,form these spread to underlying organs.Conclusions:It could be concluded that the infection studies of parasite that attaches or settles on the host body,at first,causes localized inflammatory changes,but with time,assuring a different or diffused character.The changes always begin with hyperaemia in the angles between adjacent sides at the site of attachment and then move towards deeply situated area.