Identification of antibodies directed against O-acetylated sialic acids in visceral leishmaniasis: its diagnostic and prognostic role

A significantly increased O-acetylated sialic acid (O-AcSA) binding fraction was purified from serum of visceral leishmaniasis (VL) patients by affinity chromatography on immobilized bovine submaxillary mucin (BSM) and found to be immunoglobulin in origin. The serodiagnostic and prognostic potential of BSM as a capture antigen was established by ELISA with no cross reactivity with coendemic diseases like malaria, tuberculosis, leprosy, chagas disease and cutaneous leishmaniasis; however, a strong cross reactivity was present with trypanosomiasis patients. In 56 clinically diagnosed VL patients, the BSM-ELISA was compared with diagnosis by microscopy using Giemsa stained tissue smears and direct ELISA using crude parasite antigen (parasite-ELISA); 49/56(87.5%) and 5/56(9.0%) were positive and negative respectively by all 3 methods. The BSM-ELISA failed to diagnose 2/56(3.5%) patients which were biopsy and parasite-ELISA positive. The prognostic potential of the BSM-ELISA in 18 longitudinally monitored VL patients before and after conventional antimonial treatment showed a significant decrease in anti O-AcSA titres in drug responsive patients whereas anti O-AcSA levels persisted in drug unresponsive patients. The IgG subclass distribution of antibodies directed against O-AcSA showed increased IgG2 levels in VL patients as compared to healthy controls. The BSM-based ELISA holds great promise as a serodiagnostic and prognostic assay for VL.     

Nitrogen Economy of the Main Shoot of Field Grown Barley (Hordeum Vulgare L.): III. CONTENT OF REDUCED NITROGEN IN DIFFERENT ORGANS

Nitrogen concentration pattern and total nitrogen content inthe various organs of the main shoot of field grown Jyoti barleyat 40 kg N ha^–1 were determined. The laminae had a muchhigher N concentration (µmol g^–1 dry wt.) than theother organs at a corresponding stage. The major amount of Naccumulates in the main shoot by ear emergence. An observationof interest is the decline in the total N content of the laminaebefore anthesis. The results are discussed in relation to mobilizationof N within the shoot and the contribution of the vegetativeparts to the N in developing grains.     

Composition of Bleeding Sap in Vigna radiata

Bleeding sap and nodules from Vigna radiata were analysed for their free amino nitrogen content and amino acid composition at different stages of growth and development. The bleeding sap contained mostly basic amino acids, whereas the nodules contained both acidic and basic amino acids. The amino nitrogen content of the bleeding sap increased during growth and then declined appreciably during fruit development. In contrast, nodule amino nitrogen declined from seedling stage onwards till flowering, increased during fruit development and then declined again. Nitrate reductase activity in the leaves examined at different stages of development increased from seedling stage onwards and was maximum during early fruit-development stage. It declined during pod-filling stage. The study suggests that the amount of nitrogen fixed from the atmosphere is insufficient, so that the plant has to draw upon soil nitrogen as well. This may be necessary due to the high demand of nitrogen during pod filling.     

Studies on Certain Aspects of Senescence in Nicotiana plumbaginifolia Sps

Senescence of Nicotiana plumbaginifolia VIV. (Solanaceae) wasstudied in normal, in deflowered, and in defruited plants. Removalof flowers and fruits delayed senescence, inhibited growth ofthe bolted axis and branches, and promoted the formation ofleaves on them. An increase of dry weight of leaves occurreddue to these operations and the rate of increase was a maximumin deflowered plants. Increase in dry weight was accompaniedby an increase in laminar area and this was most pronouncedin deflowered plants. Changes in total chlorophyll level ofrosette and axial leaves in deflowered, defruited, and controlplants could not, however, be correlated with dry-weight changes.Results of biochemical analyses showed that total basic proteinand RNA increased initially in leaves of deflowered and defruitedplants and during this period dry weight, total chlorophylllevel, and laminar area also increased. During later periodsthe basic protein and RNA levels declined and the rate of declinewas slowest in deflowered plants.     

Chemical Examination of Viable and Non-Viable Rice Seeds

A chemical examination has revealed four phenolic compounds in nonviable rice seeds (Oryza sativa L.). Their inhibitory bioactivity in the wheat coleoptile extension bioassay and the absence of these components in viable seeds have confirmed the relation of the phenolics with nonviability of the seeds. The compounds isolated from nonviable rice seeds were Kaempferol-4′-methyl ether, Kaempferol, quercetin and caffeic acid as identified on the basis of physical and chemical evidences.     

Influence of Reproduction on the Abscission Process of Cotton (Gossypium barbadense L.) Leaves

Abscission responses of debladed petioles of young and olderleaves were analysed during flowering, fruiting and post fruitingstages of development of G. barbadense plants. Identical abscissionexperiments were performed with materials collected from plantsmaintained in a vegetative condition by removal of flower buds. Inhibition of the abscission of debladed petioles by NAA wasgreater in debudded plants as compared to normal plants andthe extent of inhibition gradually declined during growth. Promotiveeffects of ethrel and abscisic acid were higher in normal plantsthan in debudded plants. The duration of auxin-inhibitablc stage-I of abscission wasextended in debudded plants and it gradually declined with theprogress of development. Debudded plants were characterizedby higher abscission inhibition during stage-I and lower abscissionpromotion during stage-II as a result of application of auxincompounds to the debladed petioles. Laminar tissues of debudded plants contained higher amountsof endogenous IAA and lesser amount of abscisions than did thoseof normal plants and in both cases the levels of these compoundschanged markedly during plant development. Decrease of total RNA content in the distal tissues of the abscissionzones was accompanied by increase in proximal tissues duringabscission in both normal and debudded plants. This tendencywas more pronounced in normally grown plants as compared todebudded plants.     

Seasonal Changes in the Levels of Some Cellular Components in the Abscission Zone of Coleus Leaves of Different Ages

The present study with intact petioles of Coleus of varyingages suggests an involvement of the phenomenon of mobilizationwith the abscission process. There was a gradual increase inthe levels of chlorophyll and nucleic acids and also solublenitrogen compounds in the proximal tissues with the approachof abscission with a concomitant decrease of these substancesin the distal tissues. This increase of metabolites in the proximaltissues was clearer in petioles at the first node than at thefourth node suggesting a lesser degree of metabolic activityof the proximal tissues in older petioles. The change of levelsof chlorophyll and nucleic acids and also of soluble nitrogenwas more marked in winter than in summer months. The application of NAA to petioles of the third node; just afterdeblading (i.e. in the auxin-inhibited stage 1), not only stoppedthe decline of nucleic acid levels (particularly RNA) at thedistal tissues but also caused an increase of nucleic acidsover the initial levels. This effect was more pronounced insummer than in winter months. If the initially inhibitory concentration of NAA was appliedin the auxin-promoted stage 2 of abscission, instead of an increase,there followed a quicker rate of decrease in nucleic acids (particularlyRNA). This effect was also more prominent in summer.