Citric acid production

Techniques for possible higher and rapid production of citric acid from the well known industrial medium i.e. molasses has been reported using Aspergillus niger. This includes optimization of the total reducing sugar (TRS) and nutrients like nitrogen and phosphorous. The long and unproductive lag periods normally associated with this type of fermentation has been reduced. These strategies are discussed in detail. Dr. M. Chellapandian is thankful to the Council of Scientific and Industrial Research, New Delhi, for the award of research associateship.     

Role of some riparian wetland plants in reducing erosion of organic carbon and selected cations

Five riparian herbaceous plants, Leonotis nepetaefolia, Cassia tora, Ageratum conyzoides, Parthenium hysterophorus and Sida acuta, dominant on the banks of the Rihand river at Renukoot (India), were selected to assess experimentally their quantitative role in conserving organic-C, Na, K and Ca. Young seedlings from the river bank were planted on sloping experimental plots made of alluvial soil. Simulated rainfall totalling 42.5 mm was applied at 300 mm h⁻¹ on five vegetated and one bare plots. Runoff water and eroded soil were collected from each experimental plot in artificial reservoirs and their quantities were measured. The soil conservation value of the five selected species ranged between 33 and 84% while the water conservation value varied between 19 and 50%. The overall nutrient conservation value, based on the losses in runoff water and eroded soil taken together, varied from 30 to 83% for organic-C, 19 to 78% for Na, 13 to 72% for K and 29 to 52% for Ca under different species. Loss of these four nutrients in response to 42.5 mm simulated rainfall was much higher than their input through rainfall. Loss value for the nutrients were in following order: organic-C > Ca > K > Na. The fraction of organic-C transported down the slope was higher in eroded soil (averaging 73%) and of exchangeable bases in runoff water (averaging 86% for Na, 82% for K and 90% for Ca). Flow-weighted concentrations of all the studied nutrients were consistently greater from bare stands. Number of fine roots was found to play greater role in the case of organic-C (92%; p < 0.01) and Na (70%; p < 0.05) runoff and their conservation by different plant species but canopy cover played greater role for K (58%; p < 0.08) and Ca (90%; p < 0.01).     

Mammalian myristoyl CoA: protein N-myristoyltransferase

Myristoyl CoA:Protein N-myristoyltransferase (NMT) is the enzyme which catalyses the covalent transfer of myristate from myristoyl CoA to the amino-terminal glycine residue of protein substrates. Although NMT is ubiquitous in eukaryotic cells, the enzyme levels and cellular distribution vary among tissues. In this article, we describe the properties of mammalian NMT(s) with reference to subcellular distribution, molecular weights, substrate specificity and the possible involvement of NMT in pathological processes. The cytosolic fraction of bovine brain contains multiple forms of NMT activity whereas bovine spleen contains only a single form. In bovine brain and spleen, the cytosol contained majority of NMT activity. In contrast, rabbit colon and rat liver NMT activity was predominantly particulate. Regional differences in NMT activity have been observed in both rabbit intestine and bovine brain. Results from our laboratory along with the existing knowledge, provide evidence for the existence of tissue specific isozymes of NMT.     

Flow cytometric determination of radiation-induced chromosome damage and its correlation with cell survival

Chinese hamster M3-1 cells were irradiated with several doses of X rays or alpha particles from 238Pu. Propidium iodide-stained chromosome suspensions were prepared at different times after irradiation; cells were also assayed for survival. The DNA histograms of these chromosomes showed increased background counts with increased doses of radiation. This increase in background was cell-cycle dependent and was correlated with cell survival. The correlation between radiation-induced chromosome damage and cell survival was the same for X rays and alpha particles. Data are presented which indicate that flow cytometric analysis of chromosomes of irradiated cell populations can be a useful adjunct to classical cytogenic analysis of irradiation-induced chromosomal damage by virtue of its ability to express and measure chromosomal damage not seen by classical cytogenic methods.     

ACYL AND ALK-1'-ENYL GROUP COMPOSITION OF ETHANOLAMINE PHOSPHOGLYCERIDES OF HUMAN BRAIN

Ethanolamine phosphogylcerides (EPG) of human brain gray and white matter were analyzed for their alk-1′-enyl group and fatty acid compositions in sn-glycerol positions 1 and 2. Gray matter contained more 18:0 (54%) and less 18:1 (24.5%) alk-1′-enyl residues than white matter (16% and 57%. Sixty per cent of alk-1′-enyl 18.1 in gray matter was the (n-7), against 71%, in white matter. Both gray and white matter contained small amounts of 18:1 (n-5) and (n-3) isomers. The fatty acids in position I of the phosphatidylethanolamines were more saturated than the corresponding alk-1′-enyl groups of the plasmalogens. The ratios of monoenoic fatty acid isomers in position 1 were markedly different from those of the corresponding alk-1′-enyl groups in gray matter. The fatty acid patterns in position 2 of plasmalogen and phosphatidylethanolamines of white matter were similar except for 22:4(n-6) which was concentrated in the plasmalogen (16% against 10%, in the phosphatidyl ethanolamine). In gray matter, the same trend was noted. The data suggest that alk-1′-enyl residues and the fatty acids in position 1 as well as the fatty acids in position 2 of alk-1′-enyl acyl and diacyl type EPG in both gray and white matter are, at least in part, of different provenance.     

Localization of vimentin,the nonspecific intermediate filament protein,in embryonal glia and in early differentiating neurons: In vivo and in vitro immunofluorescence study of the rat embryo with vimentin and neurofilament antisera

Antisera raised against vimentin, the protein subunit of nonspecific intermediate-sized filaments (IFs), were used in conjunction with neurofilament (NF) antisera to study the early development of neurons and glia in the rat embryo. Vimentin-positive fibers spanning the entire thickness of the neural tube including the cerebral vesicles were first observed on Day 12, concomitant with the appearance of NF protein in more confined areas (anterolateral regions of spinal cord and brain stem; motor roots emerging from the NF-positive areas). From Day 15 onwards vimentin and NF antisera selectively decorated glia and neurons, respectively, both in vivo and in vitro. Before Day 15 it appeared that NF-positive structures also stained with antivimentin in cryostat sections. In vitro experiments confirmed the presence of vimentin in early differentiating neurons. NF-positive cells were observed which also reacted with antivimentin in cultures obtained from 13- and 14-day embryos, but not later in development. Most neurons in these cultures became vimentin negative after 2–3 days in vitro.     

Pollination Ecology and Endemic Trends in Pedicularis bracteosa var. atrosanguinea Pennell & Thompson (Scrophulariaceae) in North America

Abstract Pedicularis bracteosa var. atrosanguinea occurs locally in association with P. racemosa or P. groenlandica in the Olympic Mountains in Washington. Other plant species, e.g., Polygonum bistortoides, Lupinus argenteus var. parviflorus and Valeriana sitchensis compete for space and bumblebee pollinators within the study area. Pollinator sharing, resulting from such competition, may increase the frequency of unvisited flowers of P. bracteosa var. atrosanguinea. P. bracteosa var. atrosanguinea , with blood purple nectariferous flowers, is presumed to lack intense reflections of blue spectral components from its corollas in attracting bumblebees compared to those of P. racemosa and P. groenlandica . Six species of bumblebees ( Bombus ) and cuckoo bees ( Psithyrus ) pollinate P. bracteosa var. atrosanguinea . Of these, Bombus mixtus and B. occidentalis occur in higher frequencies and are the major pollinators of P. bracteosa var. atrosanguinea . Queen and larger worker bumblebees pollinate nototribically as they probe for nectar, while smaller worker bumblebees pollinate sternotribically while scraping pollen from anthers deeply hidden in the dome-shaped galea. Corbicular pollen loads of bumblebees collected in the study area contain Pedicularis pollen alone/in combination of Polygonum, Valeriana, Lupinus, Erigeron and Bidens , or exclusively of Polygonum or Valeriana. P. bracteosa var. atrosanguinea does not suffer seriously from deficient pollination but seedlings resulting from pollinated flowers may be subjected to natural selection pressure exerted by colonial plant species for space. P. bracteosa var. atrosanguinea does not propagate asexually but resumes aerial growth seasonally from the self-same underground root stocks. If seedlings are under continuous selection pressure for lack of space, P. bracteosa var. atrosanguinea is presumed to regenerate primarily by perennial root stocks. This behavior may favor endemism in P. bracteosa var. atrosanguinea .     

Evaluation of Certain Cowpea Genotypes for Partial Resistance to Powdery Mildew (Erysiphe polygoni)

Partial resistance to powdery mildew (Erysiphe polygoni) in twenty one cowpea cultivars was assessed over two to three seasons under field conditions. Mildew incidence was recorded as number of leaflets affected/plant and severity as AUDPC or infection rate using Gompertz transformation. Irrespective of the parameter used to measure mildew resistance or the season, mean response of cvs V-105, V-269, V-276, V-282 and V-385 showed clear slow-mildewing, while RC-48, S-488, TVX-944-02E, V-27, V-36 and V-118 were rated as susceptible. Mildew resistance in some cultivars was negatively correlated with that for the leaf rust (Uromyces vignae). AUDPC was a more robust disease parameter than infection rate and showed a good correlation (r²= 0.79) with incidence.