Identification of certain cancer-mediating genes using Gaussian fuzzy cluster validity index.

In this article, we have used an index, called Gaussian fuzzy index (GFI), recently developed by the authors, based on the notion of fuzzy set theory, for validating the clusters obtained by a clustering algorithm applied on cancer gene expression data. GFI is then used for the identification of genes that have altered quite significantly from normal state to carcinogenic state with respect to their mRNA expression patterns. The effectiveness of the methodology has been demonstrated on three gene expression cancer datasets dealing with human lung, colon and leukemia. The performance of GFI is compared with 19 exiting cluster validity indices. The results are appropriately validated biologically and statistically. In this context, we have used biochemical pathways, p-value statistics of GO attributes, t-test and zscore for the validation of the results. It has been reported that GFI is capable of identifying high-quality enriched clusters of genes, and thereby is able to select more cancer-mediating genes.

Functional response analysis of Anisops sardea (Hemiptera: Notonectidae) against Culex quinquefasciatus in laboratory condition.

Background & objectives: Culex quinquefasciatus is the principal vector of lymphatic filariasis (LF). Application of alternative vector control methodologies are aimed at reduction of mosquito breeding sites and biting activity through the use of biological control methods. In the present study, functional response of aquatic Hemipteran backswimmer, Anisops sardea was assessed against Cx. quinquefasciatus larvae in laboratory bioassay. Methods: The functional respons of A. sardea was assessed against IIIrd instar larvae of Cx. quinquefasciatus. Respective handling times and coefficient of attack rates were determined by a non linear polynomeal regression equation. Results: The results of rates of predation in variable prey densities exhibited a ‘linear rise to plateau curve’, associated with ‘Type -II’ functional response. The logistic regression estimated a significant negative linear parameter (P1<0) which also supported the same observation. Associated ‘attack rates’ and ‘handling times’ were also calculated using the Holling Disc Equation. Interpretation & conclusions: The results of present experiments indicate that A. sardea can be used as a biocontrol agent against the larval forms of Cx. quinquefasciatus in temporarily available breeding places of mosquito with relatively clear water. However, a detailed field study has to be done to confirm these findings.

Laboratory evaluation of molluscicidal & mosquito larvicidal activities of leaves of Solanum nigrum L.

Background & objectives: Indiscriminate use of synthetic pesticides has created serious problem for the aquatic flora and fauna, and also resulted in appearance of pesticide resistance in vector population. This study was designed to evaluate the biocontrol efficacy of aqueous and solvent extracts of mature leaves of Solanum nigrum L., against fresh water snail Lymnaea acuminata f. rufescens (Gray) (an intermediate host of parasites causing fasciolopsiasis) and larvae of Culex vishnui group (Reuben) (vector of Japanese encephalitis). Methods: Aqueous and solvent extracts of fresh, mature, green/shed dried leaves of S. nigrum were tested against adult L. acuminata and larvae of Cx. vishnui group. The lethal concentration was determined and the appropriate lethal concentration at 24 h of benzene extract was also studied on non target organisms such as Daphnia sp, Diplonychus annulatum and Chironomus circumdatus. A qualitative phytochemical analysis was carried out in search of active ingredient and the chemical nature of the active substance was also evaluated by infrared (IR) analysis. Results: In a 72 h bioassay experiment with the aqueous extract, the highest mortality was recorded in 0.5 and 3 per cent extract against larvae of Cx. vishnui group and L. acuminata, respectivela. In the benzene solvent extract, the maximum mortality was recorded at a concentration of 150 ppm against L. acuminata and at 50 ppm against larvae of Cx. vishnui group with LC50 values of 55.45 and 11.59 ppm, respectively at 72 h. The log probit analysis (95% confidence level) recorded lowest value at 72 h of exposure. Qualitative phytochemical analysis reported the presence of some biochemical compounds, such as saponin, flavonoids, steroid and tannin. Among these, the toxic compound was detected by IR analysis having Rf = 0.87 (showed 66.70% and 76.70% mortality of L. acuminata and larvae of Cx. vishnui group, respectively). IR analysis provided preliminary information about the aliphatic amide nature of the active ingredient. Interpretation & conclusions: The study results provide considerable scope in exploiting local indigenous plant resources for molluscicidal and mosquito larvicidal activities.

Mosquito larvicidal potential of four common medicinal plants of India.

Background & objectives: Mosquitoes transmit serious human health diseases, causing millions of deaths every year. Plants may be sources of alternative mosquito control agents. The present study was carried out to assess the role of larvicidal activities of the crude extracts of four plants viz. Alternanthera sessilis L. (Amaranthaceae), Trema orientalis L. (Cannabaceae), Gardenia carinata Smith. (Rubiaceae) and Ruellia tuberosa L. (Acanthaceae) against Culex quinquefasciatus Say in laboratory bioassay. Methods: Selective concentrations (0.5, 1 and 1.5%) of crude extract of all four plant leaves were tested against Ist to IVth instar larvae of Cx. quinquefasciatus. Log probit analysis (at 95% confidence level) revealed the LC50 values. Preliminary qualitative phytochemical analyses of crude extracts were also done. The lethal concentrations (%) of crude extracts at 24 h against IIIrd instar larvae were also studied on non-target organisms. Result: In a 72 h bioassay experiment with crude extract, the highest mortality was recorded in 1.5 per cent extract. A. sessilis showed the highest mortality (76.7 %) at 1.5 per cent crude extract against IInd instar larvae having LC50 value of 0.35 per cent, followed by R. tuberosa (LC50 =1.84%), G. carinata (LC50 = 2.11) and T. orientalis (LC50 = 2.95%). The regression equation showed a dose-dependent mortality, as the rate of mortality (Y) was positively correlated with the concentration (X). Phytochemical analysis of the crude extract showed the presence of many bioactive phytochemicals such as steroids, alkaloids, terpenes, saponins, etc. No changes in the swimming behaviour and survivality of non-target organism were noticed at the studied concentrations. Interpretation & conclusions: Crude extract of the four selected plants showed larvicidal activity against Cx. quinquefasciatus. The extracts at the studied concentrations did not produce any harmful effect on non-target organisms.

Mosquito larvicidal activity of Solanum nigrum berry extracts.

Phytochemicals are widely used as biocontrol agent against vector mosquitoes. The present study was undertaken to isolate and evaluate the mosquitocidal activity of various extracts of berries of S. nigrum against Culex quinquefasciatus. Crude and chloroform: methanol (1:1, v/v) extracts of fresh, mature, green berries of S. nigrum were tested against Cx. quinquefasciatus. The lethal concentration was determined and the chemical nature of the active substance was evaluated. A qualitative phytochemical analysis of chloroform: methanol (1:1, v/v) extract was performed in search of the active ingredient. The appropriate lethal concentrations at 24 h for chloroform: methanol (1:1, v/v) extract was also studied on non-target organisms. In a 72 h bioassay experiment with crude extract, the highest mortality was recorded in 3 per cent extract. In the chloroform: methanol (1:1, v/v) solvent extract, the maximum mortality was recorded at a concentration of 120 μg/ml. The log probit analysis (95% confidence level) recorded lowest LC50 value at 72 h of exposure. Both crude and chloroform: methanol (1:1, v/v) extracts showed good larvicidal activity against Cx. quinquefasciatus. The isolated active ingredient may be tested as a potential larvicide after determination of its structure.

Plant extracts as potential mosquito larvicides.

Mosquitoes act as a vector for most of the life threatening diseases like malaria, yellow fever, dengue fever, chikungunya ferver, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management (IMM), emphasis was given on the application of alternative strategies in mosquito control. The continuous application of synthetic insecticides causes development of resistance in vector species, biological magnification of toxic substances through the food chain and adverse effects on environmental quality and non target organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are non-toxic, easily available at affordable prices, biodegradable and show broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on phytochemical sources and mosquitocidal activity, their mechanism of action on target population, variation of their larvicidal activity according to mosquito species, instar specificity, polarity of solvents used during extraction, nature of active ingredient and promising advances made in biological control of mosquitoes by plant derived secondary metabolites have been reviewed.

Functional responses of Laccotrephes griseus (Hemiptera: Nepidae) against Culex quinquefasciatus (Diptera: Culicidae) in laboratory bioassay.

Background and objectives: In integrated vector management programmes, major emphasis is given on the application of biocontrol agents. In the present study, the hemipteran water bug, Laccotrephes griseus (Hemiptera: Nepidae) was evaluated to establish its functional response against the immature Culex quinquefasciatus Say in the laboratory. Methods: Adult water bugs (L. griseus) were collected from different ponds in Bankura, West Bengal, India. Predation rate was determined in semi-field conditions. Functional response, regression equation analysis and rate of predation were also determined in the presence of an alternative prey. Results: The long-term predation experiment (up to 30 days) revealed that L. griseus is a very good predator of mosquito larvae. The functional curve analysis of L. griseus exhibited a Type II functional response. Their handling times and coefficient of attack rates were 29.37 min and 2.17 respectively. Regression equations showed that consumption rate was directly proportional to prey and predator densities and inversely proportional to the search area. The selectivity index, niche width and food breadth were also determined. Interpretation and conclusion: The present study revealed that L. griseus can consume a good number of mosquito larvae in the laboratory conditions. The long-term bioassay also indicates their predatory response against mosquito larvae in the semi-field conditions. The result of selectivity index, niche width and food breadth were also highest for Cx. quinquefasciatus. In these respects, the water bugs L. griseus are indicative of their release in the aquatic habitat where Cx. quinquefasciatus is the most dominant mosquito species.

Antibacterial activities of some plant extracts used in Indian traditional folk medicine

Objective:To evaluate the antibacterial activity of the leaf extracts of Cestrum diurnum, Ocimum sanctum, Carcica papaya, Solanum villosum, Vitex negundo, and Clerodendron inerme against two gram positive bacteria (Staphylococcus aureus MTCC 2940 and Bacillus subtilis MTCC 441) and two gram negative bacteria (Escherichia coli MTCC 739 and Pseudomonas aeruginosa MTCC 2453). Methods: The sensitivity of two gram positive and two gram negative pathogenic multi-drug resistant bacteria to extracts of leaves of six medicinal plants used as popular medicine in India was studied in vitro by the disk diffusion method and minimal inhibitory concentration (MIC). Results: All the bacterial strains were found to be sensitive to aqueous, n-hexane and ethanol extracts. But, it is evident that the organic extracts were comparatively more effective than aqueous extracts. Conclusions: It can be concluded that the leaf extracts of the six medicinal plants possess antibacterial activity against human pathogens.