Influence of light,DMSO and glycerol on the hatchability ofThamnocephalus platyurus Packard cysts

Effects of two light intensities and different concentration of dimethyl sulfoxide (DMSO) and glycerol on hydrated cyst hatching inThamnocephalus platyurus were studied. A maximum of 65±6% hatching was recorded within seven days at 2500 lux continuous light regime. Hatching was at a minimum during the first two days, peaked between the third and fourth days, decreased thereafter. Hatching success was a function of duration of light exposure. Eight percent of cysts hatched in the dark, while cysts exposed to 24h light and subsequently incubated in the dark showed 27±2% hatching. Hatchability was significantly increased (23%) in 0.0375% DMSO and 0.0125% glycerol. Concentration above 0.05% DMSO and 0.025% glycerol had no or a negative influence on hatching. Since low concentrations of DMSO were non-toxic, apolar compounds like Ca²⁺ ionophore can be dissolved in DMSO to study the role of Calcium in cyst hatching.     

Larvicidal efficacy of Pavonia zeylanica L. and Acacia ferruginea D.C. against Culex quinquefasciatus Say

Larvicidal efficacy of leaf extracts of Pavonia zeylanica and Acacia ferruginea were tested against the late third instar larvae of Culex quinquefasciatus. The larval mortality was observed after 24 h of treatment. The LC50 values of P. zeylanica and A. ferruginea were 2214.7 and 5362.6 ppm, respectively.     

Forced flowering of pineapple (<Emphasis Type="Italic">Ananas comosus</Emphasis> cv. Tainon 17) in response to cold stress,ethephon and calcium carbide with or without activated charcoal

Ethylene, a gaseous plant hormone, is responsible for the initiation of reproductive development in pineapple. Reproductive development can be forced in pineapple (Ananas comosus var. comosus) throughout the year with ethylene. Inhibition of natural flowering initiation with aviglycine [(S)-trans-2-amino-4-(2-aminoethoxy)-3-butenoic acid hydrochloride], an inhibitor of ethylene biosynthesis, provides evidence that reproductive development in response to cold stress and short daylength is also in response to ethylene production. We studied the effect of cold treatment of pineapple on ethylene production and flower induction by applying a short-term cold stress to stem apices. Shoot apices of pineapple treated with ice crystals also produced twice as much ethylene as did those of control plants and significantly more than was produced by “D” leaf basal tissue. Moreover, pineapple plants treated four times with ice crystals or ice water were induced to flower under field conditions and the forcing efficiency, as evaluated by the percentages of inflorescence emergence and fruit harvest, was comparable to forcing with calcium carbide (CaC₂) and ethephon. In another field experiment two applications of a 1.0% solution of CaC₂ or 0.15% ethephon applied at 48 h intervals was sufficient to force reproductive development of ‘Tainon 17’. Furthermore, 0.5 or 1.0% solutions of CaC₂ supplemented with 0.5% activated charcoal (AC) significantly improved the forcing effectiveness of CaC₂. This could/would make it possible to reduce the number or concentration, or both, of CaC₂ required to effect forcing in pineapple.     

Isolation and characterization of biosurfactant producing <Emphasis Type="Italic">Bacillus</Emphasis> sp. from diesel fuel-contaminated site

Among hydrocarbon pollutants, diesel oil is a complex mixture of alkanes and aromatic compounds which are often encountered as soil contaminants leaking from storage tanks and pipelines or as result of accidental spillage. One of the best ecofriendly approaches is to restore contaminated soil by using microorganisms able to degrade those toxic compounds in a bioremediation process. In the present study, nineteen bacteria were isolated by enrichment culture technique from diesel spilled soil collected from electric generator shed of NBAIM, Mau. All the isolates were subjected to screening for lipase production and twelve isolates were found to be positive for lipase. When the isolates were screened for biosurfactant production using CTAB-methylene blue agar plates, only one isolate viz. 2NBDSH3 was found positive which was found to be phylogenetically closely related with Bacillus flexus. Despite having low emulsification index, the bacterium could degrade 88.6% of diesel oil in soil. Biosurfactant from the isolate was extracted and characterized through infra-red spectroscopy which indicated its possible lipopeptide nature which was further supported by strong absorption in UV range in the UV-Vis spectrum. The results of the present study indicated that the isolate either does not produce any bioemulsifier or produces very low amount of emulsifier rather it produces a lipopeptide biosurfactant which helps in degradation of diesel oil by lowering the surface tension. The bacterium thus isolated and characterized can serve as a promising solution for ecofriendly remediation of bacterium diesel contaminated soils.     

Novel and potent oxazolidinone antibacterials featuring 3-indolylglyoxamide substituents

Novel oxazolidinone antibacterials bearing a variety of 3-indolylglyoxamide substituents have been explored in an effort to improve the spectrum and potency of this class of agents. A subclass of this series was also made with the diversity at C-5 terminus. These derivatives have been screened against a panel of clinically relevant Gram-positive pathogens and fastidious Gram-negative organisms. Several analogs in this series were identified with in vitro activity superior to linezolid (MIC=0.25-2 microg/mL). Compounds 10a, 10c, 10e and 10f displayed activity against linezolid resistant Gram-positive organisms (MIC=2-4 microg/mL). Selected oxazolidinones were evaluated for in vivo efficacy against a mouse systemic infection model.     

Anti-biofilm activity of Salvadora persica on cariogenic isolates of Streptococcus mutans: in vitro and molecular docking studies

Salvadora persica sticks are used for chewing and oral-hygiene measures worldwide. The growth inhibition and anti-biofilm effects of various extracts on cariogenic Streptococcus mutans isolates were evaluated. Biofilm inhibition, gas chromatography-mass spectrometry (GC-MS) analyses for phytochemicals and their possible mode of interaction with biofilm response regulators were revealed using LigandFit docking protocols. All S. persica extracts showed considerable inhibitory activity and the cariogenic S. mutans showed varied susceptibility when compared with controls. The percentage reduction in biofilm inhibition obtained for methanol, ethanol, chloroform, acetone, and aqueous extracts were 87.92%, 85.75%, 72.44%, 61.66% and 58.68%, respectively. GC-MS analyses revealed?>28 compounds, of which benzyl (6Z,9Z,12Z)-6,9,12-octadecatrienoate, 3-benzyloxy-1-nitro-butan-2-ol and 1,3-cyclohexane dicarbohydrazide interacted efficiently with the bacterial communication quorum-sensing (QS) regulators Streptococcus OmpP and Staphylococcus Lux proteins. The bioactive, dual-function, anti-biofilm agents in S. persica not only inhibit growth, but also control the colonization and accumulation of caries-causing S. mutans.     

Non hemolytic short peptidomimetics as a new class of potent and broad-spectrum antimicrobial agents

Since the bacterial resistance to antibiotics is increasing rapidly, numerous studies have contributed to the design and synthesis of potent synthetic mimics of antimicrobial peptides (AMPs). In an attempt to find the pharmacophore of short antimicrobial peptidomimetics through systematic tuning of hydrophobic and hydrophilic patterns, we have identified a set of short histidine-derived antimicrobial peptides (SAMPs) with potent and broad-spectrum activity. A combination of high antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA), without hemolytic activity and proteolytic stability makes these molecules promising candidates for novel antimicrobial therapeutics.     

Oviposition deterrent, ovicidal and gravid mortality effects of ethanolic extract of Andrographis paniculata Nees against the malarial vector Anopheles stephensi Liston (Diptera: Culicidae)

Oviposition is an important phenomenon of mosquitoes and has recently become the focus in the concept of integrated vector control management. In the present study, we evaluated oviposition deterrent, ovicidal and mortality effects of ethanolic extract of Andrographis paniculata Nees against gravid and oviposited females of Anopheles stephensi Liston. Water treated with the ethanolic extract had a high deterrent activity in ovipositing females: oviposition activity index values for the test species were –0.28, –0.45, –0.49 and –0.59 for extract concentrations of 29, 35, 41 and 46 p.p.m., respectively. High degrees of mortality were observed with various concentrations of extract: 1.12 (control) to 11.70 for gravid females, and 0.65 (control) to 10.25 for oviposited females. The highest mortality in both gravid and oviposited females was observed soon after they came in contact with oviposition medium treated with the extract, and this was found to be significant at doses higher than 35 p.p.m., suggesting possible contact toxicity of the extract. The extract caused moderate ovicidal activity against various age groups of A. stephensi, but it inflicted delayed effects such as high larval, pupal and adult mortality. The age of the eggs and the duration of the extract treatment influenced the ovicidal activity observed. It is clear that ethanolic extract of A. paniculata Nees can affect the oviposition cycle of A. stephensi Liston, thereby suppressing the vector population and adversely influencing transmission of the disease pathogen.