Effects of single, binary and tertiary combinations with Jatropha gossypifolia and other plant-derived molluscicides on reproduction and survival of the snail Lymnaea acuminata.

The effect of sub-lethal doses (40% and 80% of LC(50)/24h) of plant derived molluscicides of singly, binary (1:1) and tertiary (1:1:1) combinations of the Rutin, Ellagic acid, Betulin and taraxerol with J. gossypifolia latex, leaf and stem bark powder extracts and their active component on the reproduction of freshwater snail Lymnaea acuminata have been studied. It was observed that the J. gossypifolia latex, stem bark, individual leaf and their combinations with other plant derived active molluscicidal components caused a significant reduction in fecundity, hatchability and survival of young snails. It is believed that sub-lethal exposure of these molluscicides on snail reproduction is a complex process involving more than one factor in reducing the reproductive capacity.

EFFECTS OF SINGLE, BINARY AND TERTIARY COMBINATIONS WITH Jatropha gossypifolia AND OTHER PLANT-DERIVED MOLLUSCICIDES ON REPRODUCTION AND SURVIVAL OF THE SNAIL Lymnaea acuminata / Efeitos de combinações unitárias, binárias e terciárias de Jatropha gossypifolia e outros muluscicidas derivados de plantas na reprodução e sobrevivência do caramujo Lymnaea acuminata

The effect of sub-lethal doses (40% and 80% of LC50/24h) of plant derived molluscicides of singly, binary (1:1) and tertiary (1:1:1) combinations of the Rutin, Ellagic acid, Betulin and taraxerol with J. gossypifolia latex, leaf and stem bark powder extracts and their active component on the reproduction of freshwater snail Lymnaea acuminata have been studied. It was observed that the J. gossypifolia latex, stem bark, individual leaf and their combinations with other plant derived active molluscicidal components caused a significant reduction in fecundity, hatchability and survival of young snails. It is believed that sub-lethal exposure of these molluscicides on snail reproduction is a complex process involving more than one factor in reducing the reproductive capacity.

O efeito de doses sub-letais (40% e 80% de LC50/24h) de moluscicidas derivados de plantas com combinações unitárias, binárias (1:1) e terciárias (1:1:1) de Rutin, ácido Elágico, Betulin e taraxerol com látex da J. gossypifolia, folhas e extrato em pó de casca de caule e seus componentes ativos foram estudados na reprodução do caramujo de água fresca Lymnaea acuminata. Foi observado que o látex da J. gossypifolia, casca do caule, folhas individualmente e suas combinações com componentes moluscicidas ativos derivados de outras plantas causaram redução significante na fecundidade, incubação e sobrevivência dos caramujos jovens. Acredita-se que a exposição sub-letal destes moluscicidas sobre a reprodução dos caramujos é processo complexo envolvendo mais de um fator na redução da capacidade reprodutiva.

The uncertain consequences of transferring bacterial strains between laboratories - rpoS instability as an example.

BACKGROUND: Microbiological studies frequently involve exchanges of strains between laboratories and/or stock centers. The integrity of exchanged strains is vital for archival reasons and to ensure reproducible experimental results. For at least 50 years, one of the most common means of shipping bacteria was by inoculating bacterial samples in agar stabs. Long-term cultures in stabs exhibit genetic instabilities and one common instability is in rpoS. The sigma factor RpoS accumulates in response to several stresses and in the stationary phase. One consequence of RpoS accumulation is the competition with the vegetative sigma factor σ70. Under nutrient limiting conditions mutations in rpoS or in genes that regulate its expression tend to accumulate. Here, we investigate whether short-term storage and mailing of cultures in stabs results in genetic heterogeneity. RESULTS: We found that samples of the E. coli K-12 strain MC4100TF exchanged on three separate occasions by mail between our laboratories became heterogeneous. Reconstruction studies indicated that LB-stabs exhibited mutations previously found in GASP studies in stationary phase LB broth. At least 40% of reconstructed stocks and an equivalent proportion of actually mailed stock contained these mutations. Mutants with low RpoS levels emerged within 7 days of incubation in the stabs. Sequence analysis of ten of these segregants revealed that they harboured each of three different rpoS mutations. These mutants displayed the classical phenotypes of bacteria lacking rpoS. The genetic stability of MC4100TF was also tested in filter disks embedded in glycerol. Under these conditions, GASP mutants emerge only after a 3-week period. We also confirm that the intrinsic high RpoS level in MC4100TF is mainly due to the presence of an IS1 insertion in rssB. CONCLUSIONS: Given that many E. coli strains contain high RpoS levels similar to MC4100TF, the integrity of such strains during transfers and storage is questionable. Variations in important collections may be due to storage-transfer related issues. These results raise important questions on the integrity of bacterial archives and transferred strains, explain variation like in the ECOR collection between laboratories and indicate a need for the development of better methods of strain transfer.

Efficacy of Euphorbia hirta latex as plant derived molluscicides against freshwater snails.

The toxic effect of binary and tertiary combinations of Euphorbia hirta Linn latex powder with other plant molluscicidal compounds, were evaluated against the freshwater snails Lymnaea (Radix) acuminata and Indoplanorbis exustus in pond. These combinations showed significant time and dose dependent effect against both the snails. These compounds at higher doses were also lethal to freshwater fish Channa punctatus (Bloch) (Channidae {Ophicephalidae}), which shares the habitat with these snails, but the LC90 (24h) doses of snails have no apparent killing properties in fish populations when treated in mixed population of snails and fish.

Efficacy of euphorbia hirta latex as plant derived molluscicides against freshwater snails / Eficácia do látex da Euphorbia hirta como moluscicida vegetal contra caramujos de água doce

The toxic effect of binary and tertiary combinations of Euphorbia hirta Linn latex powder with other plant molluscicidal compounds, were evaluated against the freshwater snails Lymnaea (Radix) acuminata and Indoplanorbis exustus in pond. These combinations showed significant time and dose dependent effect against both the snails. These compounds at higher doses were also lethal to freshwater fish Channa punctatus (Bloch) (Channidae {Ophicephalidae}), which shares the habitat with these snails, but the LC90 (24h) doses of snails have no apparent killing properties in fish populations when treated in mixed population of snails and fish.

Os efeitos tóxicos das combinações binárias e terciárias do pó de látex da Euphorbia hirta Linn assim como outros compostos vegetais moluscicidas foram avaliados em sua ação sobre caramujos de água doce Lymnaea (Radix) acuminata e Indoplanorbis exustus em represas. Estas combinações mostraram significante efeito dose e tempo dependente contra ambos os caramujos. Estes compostos em doses altas foram também letais para peixes de água doce Channa punctatus (Bloch) (Channidae {Ophicephalidae}), que compartilham o ambiente com estes caramujos mas a dose LC90 (24h) para caramujos aparentemente não tem propriedade de matar as populações de peixes quando uma população mista de peixes e caramujos são tratadas.

Chitinase from Enterobacter sp. NRG4: Its purification, characterization and reaction pattern

Enterobacter sp. NRG4 was shown to excrete chitinase into the culture supernatant when cultivated in medium containing chitin. A 60 kDa extracellular chitinase was purified to homogeneity and characterized. The enzyme hydrolyzed swollen chitin, colloidal chitin, regenerated chitin and glycol chitin but did not hydrolyze chitosan. The chitinase exhibited Km and Vmax values of 1.43 mg ml-1 and 83.33 µM µg-1 h-1 for swollen chitin, 1.41 mg ml-1 and 74.07 µM µg-1 h-1 for colloidal chitin, 1.8 mg ml-1 and 40 µM µg-1 h-1 for regenerated chitin and 2.0 mg ml-1 and 33.33 µM µg-1 h-1 for glycol chitin, respectively. The optimal temperature and pH for activity were 45ºC and pH 5.5, respectively. Mg2+, K+ and Ca2+ stimulated chitinase activity by 13, 16 and 18%, respectively whereas Cu2+, Co2+, Ag+ and Hg2+ inhibited chitinase activity by 9.7, 15, 22 and 72.2%, respectively at 1 mM concentration. N-bromosuccinamide (NBS) at 1 mM and iodoacetamide at 10 mM concentration completely inhibited the enzyme activity. Dithiobisnitrobenzoic acid (DTNB) at 10 mM concentration inhibited chitinase activity by 97.2%. Chitin was hydrolyzed to chitobiose and N-acetyl D-glucosamine when incubated with the purified enzyme. The hydrolysis pattern of the purified enzyme indicated that the chitinase was an endochitinase.