Chronic Exposure to Arsenic at Low Concentration Has Toxic Effect in Human but Short-Term Exposure in Vitro Induces Apoptosis

-- Rajdeep Chowdhury , Suchandra Chowdhury , Paromita Roychoudhury, Chitra Mandal and Keya Chaudhuri

Arsenic is an environmental toxicant and a human carcinogen, but paradoxically it has therapeutic effects too. A field survey, conducted amongst the inhabitants of north 24 Parganas, West Bengal, exposed to arsenic, shows the prevalence of different types of arsenic induced skin lesions at exposure to low non-toxic doses. The results reveal a significant preponderance of dermal effects like hyperkeratosis and raindrop pigmentation at low doses; however, little correlation was observed with the arsenic exposure and arsenic level in hair, nail or urine of the exposed subjects. Paradoxically, in vitro application of the soluble most toxic and naturally prevalent form of arsenic, sodium arsenite (NaAsO2), results in a different outcome in human malignant melanoma cell A375. Interestingly, 2 µM NaAsO2, the maximum dose that can be achieved in blood plasma, led to induction of apoptosis at 72 h of treatment, confirmed through Annexin V-PI dual staining and DNA content analysis. Increase in reactive oxygen species (ROS) production, loss of mitochondrial membrane potential, associated with an activation of caspases were found to be the critical mediators of apoptosis.

© 2008 IUP . All Rights Reserved.

Characterization of Some Popular Mulberry Cultivars of Karnataka Through RAPD Analysis

-- S Mahesh and Geetha Bali

Mulberry which belongs to the genus Morus is an economically important plant that is used as the sole food for rearing silkworms. Existing conventional methods of identification of different cultivars are difficult due to close similarities. Here we have described the use of polymerase chain reaction-based Random Amplified Polymorphic DNA (RAPD) for developing cultivar specific markers that can be employed in the identification of some popular mulberry cultivars of Karnataka. Twenty-five decamer oligonucleotide primers were screened for five different mulberry cultivars, among which three primers scored 47 bands ranging from 500-5000 bp. PCR amplification with these primers yielded 1-10 bands per primer. Genetic tree was constructed based on the band score following Ward's method. In the present study, we have also identified few putative cultivar specific RAPD markers that could be useful in developing SCAR markers for further studies in germplasm conservation and identification of mulberry cultivars.

© 2008 IUP . All Rights Reserved.

Phytochemical Screening and Antifungal Activity of Cyperus esculentus L.

-- N Prakash and B Ragavan

Cyperus esculentus L., a member of family Cyperaceae is an edible medicinal plant which is used for various ailments such as hypochondriasis, indigestion, nausea and fever. In the present study, the phytochemical screening and antifungal activity of various extracts (such as acetone, 50% ethanol (hydroethanol), chloroform and petroleum ether) of C. esculentus L. tubers were evaluated. The results showed the presence of various important secondary metabolites such as alkaloids, flavonoids, terpenoids, phenols, etc., in higher levels in hydroethanolic extract of the sample. Hydroethanolic and acetone extracts showed maximum antifungal activity against Candida albicans and Aspergillus flavus. Chloroform and petroleum ether extract showed maximum activity against A. flavus. Trichoderma sp. was known to be resistant against all the extracts of the sample.

© 2008 IUP . All Rights Reserved.

RESEARCH NOTE

MicroRNAs: Novel and Potential Candidates for Cancer Therapy

-- D Karunagaran, P Sripriya and B N Prabhakar

MicroRNAs (miRNAs) are a new class of non-protein-coding, endogenous, small RNAs typically 21-23 nucleotide (nt) in length, evolutionarily conserved in many organisms as disparate as yeast, fruit flies, human and plants (Bartel, 2004). They play profound and pervasive roles in manipulating genes involved in development, proliferation, apoptosis and stress response in various eukaryotes (Ambros, 2004). Recent evidences demonstrate that aberrant miRNA expression is a hallmark of tumor development, revealing that miRNA genes could function as potential oncogenes and repressors in the human body (He et al., 2005b; and Volinia et al., 2006).

© 2008 IUP . All Rights Reserved.

RESEARCH NOTE

RNA Interference and Functional Genomics: From Genes to Drug Discovery

-- Dashnamoorthy Ravi and Alex Bishop

Human genome has been predicted to consist 69,073 genes, of which an estimated 48,400 genes are believed to be transcribed, out of which 22,740 transcripts are expected to be translated into known and novel protein (www.ensembl.org). Extensive informatics about the genome sequence of several species has been accumulated so far and overlaps between such gene and protein sequences across various species have also been computed. As informatics about genomes continue to expand, the utility for such data-pools is becoming realized as it is becoming a need for functional genomics.

© 2008 IUP . All Rights Reserved.