Phosphorus uptake from different sources of phosphatic fertilizers by maize and wheat at two stages of growth

The results of pot experiments on wheat and maize with³²P labelled phosphatic fertilizers showed that P uptake after one month of sowing and at ear emergence in case of wheat has significant positive correlations with dry matter yield where as P uptake after one month of sowing has only significant positive correlation with dry matter yield and P uptake at tasseling has no correlation with dry matter yield in case of maize. P uptake and P concentration have significant correlation at both the stages of growth in case of wheat but P uptake from fertilizer and its respective concentration has only significant correlation at both the stages in case of maize.     

Study on the Trace Elements in <Emphasis Type="Italic">Swertia chirayita</Emphasis> (Roxb.) H. Karsten

An attempt has been made to analyze some trace elements and electrolytes like Zn, Cu, Mn, Fe, Co, Na, K, Ca, and Li present in the Swertia chirayita roots and leaves. The concentration of Ca in all the samples was more than 1,346.0 mg/kg and the concentration of other elements was found in the order K > Ca > Fe > Na > Mn > Zn > Co > Cu > Li in different samples of S. chirayita.     

Genetic variation and relationship among and within Withania species as revealed by AFLP markers.

Withania somnifera is an important medicinal plant, and its anticancerous properties have been attributed to various classes of withanolide compounds. The objective of the present study was to investigate the inter- and intraspecific genetic variation present in 35 individuals of W. somnifera and 5 individuals of W. coagulans using AFLP (amplified fragment length polymorphism) marker technique. The information about genetic variation determined from AFLP data for 40 individuals was employed to estimate similarity matrix value based on Jaccard's coefficient. The similarity values were further used to construct a phenetic dendrogram revealing the genetic relationships. The dendrogram generated by UPGMA (unweighted pair group method of arithmetic averages) distinguished W. somnifera from W. coagulans and formed two major clusters. These two main clusters shared a similarity coefficient of 0.3, correlating with the high level of polymorphism detected. The dendrogram further separated W. somnifera into three subclasses corresponding to Kashmiri and Nagori groups and an intermediate type. The AFLP profile of Kashmiri individuals was distinct from that of the Nagori group of plants. The intermediate genotype was distinct as it shared bands with both the Kashmiri and Nagori individuals, even though it was identified as a Kashmiri morphotype. Furthermore, the intermediate type shared a similarity coefficient of 0.8 with the Kashmiri individuals. The present work revealed low levels of variation within a population though high levels of polymorphism were detected between Nagori and Kashmiri populations. The ability of AFLP markers for efficient and rapid detection of genetic variations at the species as well as intraspecific level qualifies it as an efficient tool for estimating genetic similarity in plant species and effective management of genetic resources.     

A Carbon-Nitrogen Lyase from Leucaena leucocephala Catalyzes the First Step of Mimosine Degradation

The tree legume Leucaena leucocephala contains a large amount of a toxic nonprotein aromatic amino acid, mimosine, and also an enzyme, mimosinase, for mimosine degradation. In this study, we isolated a 1,520-bp complementary DNA (cDNA) for mimosinase from L. leucocephala and characterized the encoded enzyme for mimosine-degrading activity. The deduced amino acid sequence of the coding region of the cDNA was predicted to have a chloroplast transit peptide. The nucleotide sequence, excluding the sequence for the chloroplast transit peptide, was codon optimized and expressed in Escherichia coli. The purified recombinant enzyme was used in mimosine degradation assays, and the chromatogram of the major product was found to be identical to that of 3-hydroxy-4-pyridone (3H4P), which was further verified by electrospray ionization-tandem mass spectrometry. The enzyme activity requires pyridoxal 5′-phosphate but not α-keto acid; therefore, the enzyme is not an aminotransferase. In addition to 3H4P, we also identified pyruvate and ammonia as other degradation products. The dependence of the enzyme on pyridoxal 5′-phosphate and the production of 3H4P with the release of ammonia indicate that it is a carbon-nitrogen lyase. It was found to be highly efficient and specific in catalyzing mimosine degradation, with apparent K_m and V_max values of 1.16 × 10⁻⁴ m and 5.05 × 10⁻⁵ mol s⁻¹ mg⁻¹, respectively. The presence of other aromatic amino acids, including l-tyrosine, l-phenylalanine, and l-tryptophan, in the reaction did not show any competitive inhibition. The isolation of the mimosinase cDNA and the biochemical characterization of the recombinant enzyme will be useful in developing transgenic L. leucocephala with reduced mimosine content in the future.Leucaena leucocephala is an important agroforestry tree legume of the tropics, and its foliage can be used as a protein-rich fodder (Garcia et al., 1996; Soedarjo and Borthakur, 1998). L. leucocephala is highly tolerant to drought (Shelton and Brewbaker, 1994) and resistant to many pests and diseases. The protein-rich foliage and tolerance to various abiotic and biotic stresses make L. leucocephala a promising legume for use as a fodder. In spite of these desirable attributes, the use of L. leucocephala as a fodder is rather limited because its foliage also contains an N-heterocyclic nonprotein amino acid, known as mimosine, which is toxic to both prokaryotic cells (Soedarjo et al., 1994) and eukaryotic cells (Lalande, 1990). Mimosine inactivates a variety of enzymes either by chelating bivalent metallic ions and thereby limiting their availability for use as cofactors by several metallic ion-dependent enzymes, such as ribonucleotide reductase, alkaline phosphatase, and dopamine β-hydroxylase (Chang, 1960; Hashiguchi and Takahashi, 1977; Dai et al., 1994), or by forming a stable complex with pyridoxal-5′-phosphate (PLP), leading to the inactivation of PLP-dependent enzymes, such as cystathionine synthetase, cystathionase, Asp-Glu transaminase, Tyr decarboxylase, tyrosinase, and l-dopa decarboxylase (Crounse et al., 1962; Lin et al., 1962, 1963; Hylin, 1969). The inactivation of important enzymes by mimosine causes various physiological abnormalities, including enlarged thyroid glands, infertility, birth defects, and loss of hairs (Crounse et al., 1962; Hamilton et al., 1968; Joshi, 1968; Dewreede and Wayman, 1970; Reis et al., 1975; Jones et al., 1976).Mimosine is abundant in all parts of L. leucocephala, and on a dry weight basis, L. leucocephala leaves contain approximately 5% mimosine (Soedarjo and Borthakur, 1998). Such high mimosine content in the foliage indicates that mimosine may have some functional role in the plant. Previously, mimosine has been shown to inhibit DNA synthesis in many DNA viruses by chelating iron required by ribonucleotide reductase (Dai et al., 1994), suggesting its role in defense against virus attacks. Besides this, other possible roles of mimosine in L. leucocephala are not well established. Considering its biochemical properties of inactivating various enzymes that require either bivalent metallic ions or PLP as cofactors, mimosine may have a role in plant defense, and based on its chemical composition, it may serve as a reservoir of carbon and nitrogen for survival and growth under nutrient-limiting conditions. But the utilization of mimosine as a source of carbon and nitrogen is possible only if the plant has specific enzymes to catabolize it. Interestingly, the presence of such mimosine-degrading enzymes has been reported from seedling extracts of L. leucocephala and Mimosa pudica, another mimosine-containing plant (Suda, 1960; Smith and Fowden, 1966). Smith and Fowden (1966) identified the mimosine-degrading enzyme from L. leucocephala seedling extracts as a carbon-nitrogen (C-N) lyase that converted mimosine into 3,4-dihydroxypyridine (3,4DHP), pyruvic acid, and ammonia (Fig. 1). Additionally, a mimosine-degrading enzyme, mimosinase, was purified from L. leucocephala leaves (Tangendjaja et al., 1986) and was found to degrade mimosine into 3-hydroxy-4-pyridone (3H4P; Fig. 1). However, the genes encoding the mimosine-degrading enzymes from L. leucocephala have not been isolated and characterized.Open in a separate windowFigure 1.Chemical structures of mimosine (A), 3H4P (B), 3,4DHP (C), pyruvate (D), and ammonium (E).The goals of this study were to isolate complementary DNA (cDNA) for a mimosine-degrading enzyme from L. leucocephala and to determine the biochemical and kinetic properties of the encoded enzyme. This will help us to understand roles of mimosine and mimosine-degrading enzymes in L. leucocephala. Additionally, it may be useful in developing transgenic L. leucocephala with reduced mimosine content, which will make this tree legume suitable for use as a nutritious fodder for animals in the future.     

Ni<Superscript>+2</Superscript>-inhibited radicle growth in germinating wheat seeds involves alterations in sugar metabolism

Nickel (Ni) is a trace element essential for the growth and development of plants. Conversely, when in excess, Ni inhibits seed germination and reduces seedling growth. Therefore, we investigated the effect of Ni⁺² (5–50 μM; supplied as nickel sulfate: NiSO₄·6H₂O) on the activity of enzymes involved in sugar metabolism of wheat (Triticum aestivum L.) seedlings after 96 h of exposure to the metal. Ni⁺² treatment reduced root and coleoptile length of emerging wheat seedlings and the effect was more pronounced on the root length. Ni⁺² (5–50 μM) treatment significantly enhanced carbohydrate content by 21–100 % over that of the control. In contrast, protein and reducing sugar contents declined by 17–43 and 22–69 %, respectively. The reduction in total protein content was confirmed by SDS-PAGE analysis. The activities of starch-metabolizing enzymes declined upon Ni⁺² stress in a concentration-dependent manner. Activities of α- and β-amylases, acid and alkaline invertases, acid and alkaline phosphatases, and starch phosphorylase declined by 18–74 and 24–85 %, 42–76 and 21–73 %, 15–54 and 28–72 %, and 50–83 %, respectively, when compared to the control. The study concludes that Ni⁺² impairs sugar metabolism as indicated by decline in the activity of sucrose and starch hydrolyzing enzymes. It resulted in decrease in the availability of biochemical energy and sugars required for the synthesis, leading to inhibition of radicle growth in germinating wheat seeds.     

Arbitrary-primed PCR for genomic fingerprinting and identification of differentially regulated genes in Indian isolates of Leishmania donovani

The arbitrary-primed PCR (AP-PCR) technique was employed with the twin goals of identifying genetic polymorphisms within the Indian isolates and to identify differentially expressed gene sequences. The parasite isolates from Indian Kala-azar patients could be differentiated from Leishmania donovani isolates from distinct geographic regions. Moreover, differences within the Indian isolates could also be identified. A majority (17/19) of the Indian isolates gave identical AP-PCR pattern, while two isolates gave consistently divergent pattern. The distinctive AP-PCR fragments obtained with Indian isolates were used as probes in Northern blot analysis. Three such fragments were found to represent transcribed sequences that were differentially expressed in the two stages of the parasite. These sequences led to cloning and characterization of Leishmania Centrin gene and a novel gene termed A-1 that is over-expressed in amastigote stage of the parasite. The study demonstrates the utility of random genome sampling methods in genomic fingerprinting and in identifying differentially transcribed sequences that could potentially contribute to parasite virulence.     

In Vitro Antimicrobial Activity of <Emphasis Type="Italic">Acacia catechu</Emphasis> and Its Phytochemical Analysis

Acacia catechu, commonly known as catechu, cachou and black cutch is an important medicinal plant and an economically important forest tree. The methanolic extract of this plant was found to have antimicrobial activities against six species of pathogenic and non-pathogenic microorganisms: Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The maximum zone of inhibition (20 mm) was found to be exhibited against S. aureus. For this organism the minimum bactericidal concentration (MBC) of the crude extract was 1,000 μg/ml. The extract was found to be equally effective against gram positive and gram negative bacteria. The antimicrobial activity of the extract was found to be decreased during purification. The chemical constituents of organic plant extracts were separated by thin layer chromatography (TLC) and the plant extracts were purified by column chromatography and were further identified by Gas chromatography–mass selection (GC–MS) analysis. The composition of A. catechu extract had shown major components of terpene i.e. camphor (76.40%) and phytol (27.56%) along with other terpenes in minor amounts which are related with their high antibacterial and antifungal properties.     

Multiple dexamethasone treatment affects morphometric parameters of gonadotrophic cells in adult female rats

Exposure to glucocorticoids leads to numerous changes in various biological systems including the reproductive system. The aim of the present work was to find out whether dexamethasone (Dx) treatment of adult female rats would influence the histological and morphometric characteristics of the pituitary gonadotrophic cells (luteinizing--LH cells and follicle stimulating--FSH cells). One group of female Wistar rats received Dx injections on three consecutive days in doses 1.0, 0.5 and 0.5 mg/kg b.w. respectively, while the control rats were treated with equivalent volumes of saline. Experimental and control animals were sacrificed 24 h and 72 h after the last injection. The peroxidase-antiperoxidase (PAP) immunocytochemical procedure was used to study the LH and FSH cells. The stereological and morphometric analyses showed that multiple Dx treatments of female rats significantly decreased the volume of LH cells and the volume of their nuclei 24 h and 72 h after the last Dx injection in comparison with control values. At 24 h after Dx treatment, the volume density of LH cells was significantly increased, but at 72 h differences between the experimental and control groups were insignificant. The increase in number of LH cells per unit area (mm2) was significant at both timepoints (24 h and 72 h). Stereologic and morphometric characteristics of FSH cells was changed after Dx treatment in the same manner as that of LH cells, except for the volume density, where a significant increase was established 24 h and 72 h after the last Dx application. These results clearly demonstrate that 24 h and 72 h after the last of three Dx injections there were changes in the immunocytochemical and morphometric features of gonadotrophic cells.     

Torrefaction: a sustainable method for transforming of agri-wastes to high energy density solids (biocoal)

Reviews in Environmental Science and Bio/Technology - The depletion of fossil fuel reserves and greenhouse gas emissions led to limit the use of fossil fuels, including natural gas, coal, or...     

Inhibitory effect of leachate from Helianthus annuus on germination and growth of Kharif crops and weeds

Allelopathic potential of sunflower (Helianthus annuus L.) fresh plant tissues aqueous extraction in bioassay, rhizosphere soil in pot experiment and phytotoxicity of decomposed sunflower plant biomass in bioassay against Vigna radiata, Pennisetum glaucum, Trianthema portulacastrum and Parthenium hysterophorum was investigated. In bioassay aqueous extracts of fresh sunflower plant tissue inhibited the germination, seedling growth (shoot and root) and dry matter accumulation of test plant species. In pot study sunflower rhizosphere soil inhibited growth attributes (plant height, population, number of branches) and yield attributes (grain yield, biomass yield) of selected crops and weeds. Phytotoxicity of decomposed sunflower biomass showed inhibitory effect on selected plant species. The fresh plant tissues was greatest inhibitory to test plants and followed by that of the decomposed biomass extracts in all bioassays. Significant reductions in the root and shoot growth were observed as the extract concentration was increased. The concentrations of extract fraction of fresh sunflower was determined, since nine compounds i.e. ferulic, p-coumaric, syringic, chlorogenic acid, isochlorogenic acid, neochlorogenic acid, vanillic acid, p-hydroxybenzoic acid, caffeoylquinic acid, found to be main growth inhibitors in sunflower plant tissue. These results suggested that sunflower plants may possess allelopathic potential, and the plant tissues may be potentially useful for weed management.