Development of a Cytosensor for the Detection of Fusarium Oxysporum - A Functional Approach Towards Bioanalytical Applications

The development of bio-analytical methods for monitoring microorganisms have created opportunities for applications in biosensors, bioprocess monitoring, assessment of cell signalling, analysis of drug responses, among several others. The voltammetric sensing system employed for studying the electrode behavior of the fungus Fusarium oxysporum comprised working (gold) electrode (0.2 cm2 ) platinum as counter electrode (0.2 cm2 ) and a saturated calomel as the reference, where the electrochemical response corresponded to the growth phases (lag, log, stationary and decline) of the fungus. The electrochemical method based on voltammetric response matched well with the response obtained through conventional methodology, where the dry weight of the fungus is estimated against time. The peak potential is a function of scan rate, which is one of the characteristic features of a totally irreversible electrode process. It is important to mention here that this dependence is true regardless of reversibility for any diffusing redoxactive species. The proposed electrochemical method is less cumbersome and more accurate. Furthermore, the proposed electrochemical method captures the decline phase of fungal growth, which is generally difficult using the conventional method of assessment of the growth curve. Further experiments confirm that the anodic peaks were not due to the biomass or the fungal spores and only due to the extracellular metabolites. However, at this stage it is difficult to exactly determine the metabolite or the group of metabolites that are responsible for the anodic peak. In conclusion this cytosensor is capable of accurately and rapidly quantifying fungi with Fusarium oxysporum as a model organism

Preliminary phytochemical screening and antimicrobial activity of Samanea saman

Samanea saman is a tropically distributed medicinal plant. Antimicrobial activity of aqueous extract of this plant was investigated by Well-diffusion method against three organisms: Escherichia coli, Staphylococcus aureus and Candida albicans. The plant extract showed inhibitory activity against all the tested organisms. Five mg/ml inhibited the growth of E. coli but slightly higher concentration of 10 mg/mL was necessary to show inhibition against S. aureus and C. albicans. Phytochemical screening of the plant revealed the presence of tannins, flavonoides, saponins, steroids, cardiac glycosides and terpenoids. The study scientifically validates the use of plant in traditional medicine

Instabilities of the Whistler Mode in the Magnetosphere

248-253The nature of the convective instability has been investigated for whistler wave propagation at frequencies less than and close to the cyclotron frequency for an anisotropic and loss cone velocity distribution for the electrons. The dispersion equation has been solved and an expression is given for the growth or decay rate of the waves for convective instability. Detailed numerical calculations have been made for the growth or decay rate of the wave for different values of the anisotropy ratio T/TII of the perpendicular and parallel temperatures, and the Mcllwain parameter L. It is found that for parallel propagation, the waves are unstable for frequencies less than the cyclotron frequency and the instability depends only on the anisotropy parameter T/TII and not on the loss cone index i

Instabilities of Obliquely Propagating Electromagnetic Modes in the Magnetosphere

242-246The oblique propagation of the ordinary and the extraordinary electromagnetic modes in the magnetosphere and the instabilities in these modes arising from temperature anisotropy are studied. The dispersion equation is solved numerically using a TDC 316 computer for (i) McIIwain parameter L = 2 and 3; (ii) temperature anisotropy ratio δ (= T/TII ) values varying from 10 to 0.1 and (iil) for wavelength of waves of the order of a kilometer. The computer calculations are carried out for frequencies in the range ω1, to 3 ω1, and ω2 to 3 ω2, where ω1, and ω2, are the left-hand and right-hand cut-off frequencies, and both the real as well as the imaginary parts of the wave vector are calculated. It is found that both the ordinary and the extraordinary electromagnetic waves are unstable and the instability shows a strong dependence on the propagation angle θ, McIlwain parameter L, propagation frequency and also on the temperature anisotropy ratio δ

Temperature anisotropy instabilities in a plasma containing cold and hot species in the magnetosphere

The nature of convective instability has been investigated for an electromagnetic wave, either right circularly polarised or left circularly polarised, propagating along a magnetic line of force in a plasma whose distribution function exhibits a temperature anisotropy in the hot species, a loss cone structure and a beam of cold electrons or ions travelling along the line of force with velocity V<SUB>1</SUB>. Detailed numerical calculations have been made using a computer for the growth and decay of the wave for different values of the anisotropy ratio T<SUB>⊥</SUB> /T<SUB>║ </SUB>= δ of the perpendicular and parallel temperatures, the McIlwain parameter L, the loss cone index j, velocity V<SUB>1</SUB> of the streaming particle and the particle density ratio ε. The ranges of values of ε and δ for which the wave becomes unstable have been studied in detail. It is found that wave propagation shows no dependence on the loss cone index but shows very strong dependence on the temperature anisotropy δ

Children with developmental coordination disorder (DCD) can adapt to perceptible and subliminal rhythm changes but are more variable

Children with DCD demonstrate impairments in bimanual finger tapping during self-paced tapping and tapping in synchrony to different frequencies. In this study, we investigated the ability of children with DCD to adapt motorically to perceptible or subliminal changes of the auditory stimuli without a change in frequency, and compared their performance to typically developing controls (TDC). Nineteen children with DCD between ages 6–11 years (mean age ± SD = 114 ± 21 months) and 17 TDC (mean age ± SD = 113 ± 21 months) participated in this study. Auditory perceptual threshold was established. Children initially tapped bimanually to an antiphase beat and then to either a perceptible change in rhythm or to gradual subliminal changes in rhythm. Children with DCD were able to perceive changes in rhythm similar to TDC. They were also able to adapt to both perceptible and subliminal changes in rhythms similar to their age- and gender- matched TDC. However, these children were significantly more variable compared with TDC in all phasing conditions. The results suggest that the performance impairments in bilateral tapping are not a result of poor conscious or sub-conscious perception of the auditory cue. The increased motor variability may be associated with cerebellar dysfunction but further behavioral and neurophysiological studies are needed