An in vitro demonstration of peroxisome proliferation and increase in peroxisomal β-oxidation system mRNAs in cultured rat hepatocytes treated with ciprofibrate

Using the normal adult rat hepatocytes, plated on rat tail collagen-coated dishes and fed a chemically defined medium, we demonstrate here that ciprofibrate at 0.1 mM concentration, increases significantly the mRNA levels of fatty acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, and thiolase (the three enzymes of the β-oxidation system), and causes peroxisome proliferation. Increase in mRNA levels of these genes was evident within 1 h and was maximal 24 h after the addition of ciprofibrate. In hepatocytes cultured in the absence of ciprofibrate, the basal levels of these enzymes were low and further declined with time. Concomitant treatment of hepatocytes with cycloheximide did not inhibit or superinduce the mRNA levels, indicating that this induction may represent a primary (direct) effect of this compound on the expression of these genes and does not apparently involve short-lived repressor protein(s).     

A new gene for resistance to green leafhopperNephotettix virescens (Distant) in rice

The mode of inheritance of resistance to green leafhopper in 12 cultivars of riceOryza saliva L. was studied. Seedlings of parent and hybrid populations were artificially infested with second- and third-instar virus-free green leafhopper nymphs. Seedling reaction was scored when TNI, the susceptible check, was completely killed. The results revealed that single dominant genes confer resistance in six varieties, two independent dominant genes in four varieties, and single recessive genes in two varieties. The single dominant genes in Sri Gaya, ARC 7320, and T23 and one of the two genes in Aswina and Bhura Rata 2 are allelic toGlh-1; while Bhawalia hasGlh-5 gene. The second gene of Bhura Rata 2 is allelic to IR28 gene. Resistance in Chamar is controlled by two independent genes one of which is allelic toGlh-5 and the other allelic to IR28 gene. Bazal hasGlh-2 andGlh-5. The single recessive gene in ARC 7012 is allelic toglh-4 but the single recessive gene in DV85 is nonallelic to and independent ofglh-4. This new recessive gene is designated asglh-8. The single dominant genes of Dumai, Gadur, and the second gene of Aswina are nonallelic to all the known genes for resistance.     

Macrophylloside, a flavone glucoside from Primula macrophylla

A new flavone glucoside macrophylloside has been isolated from the whole plant of Primula macrophylla and its structure was determined by spectroscopic methods as 2′-hydroxy-7-O-β- -glucopyranosyloxyflavone. Sitosterol glucoside was also isolated for the first time from this plant.     

Exploiting the chemical synthesis of RNA.

A number of nucleotide phosphoramidites are now available that permit the chemical synthesis of RNA, modified RNA and RNA-DNA chimeric oligonucleotides. Since the chemical strategy allows the introduction of a particular modification at any given site in a nucleotide polymer, very subtle and specific questions regarding structure-function relationships in RNA may be addressed.     

Prevention of guanine modification and chain cleavage during the solid phase synthesis of oligonucleotides using phosphoramidite derivatives.

Phosphoramidite reagents can phosphitylate guanine bases at the O6-position during solid phase synthesis and serious chain cleavage occurs if the base phosphitylation is not eliminated before the iodine/water oxidation step. This can be accomplished by blocking the O6-position with a 2-cyanoethyl protecting group for deoxyribonucleotides or with a p-nitrophenylethyl group for ribonucleotides, regenerating the guanine base with water or acetate ions, or using N-methylanilinium trifluoroacetate (TAMA) as the phosphoramidite activator. The effectiveness of these methods was demonstrated by both 31P NMR studies and by the synthesis of d(Gp)23G, (Gp)14G, and d-(Gp)13rG sequences.     

Kinetic properties and contribution to cellulose saccharification of a cloned Pseudomonas beta-glucosidase

The plasmid pND71, which encodes beta-glucosidase (cellobiase) activity, cloned from the cellulolytic Pseudomonad, PS2-2, was mobilized by conjugation into 10 Pseudomonas strains. The highest specific activity was produced by 17498 (pND71) and the properties of the enzyme produced from this transconjugant were studied. The enzyme was shown to be cell associated, to have a temperature optimum of 37 degrees C, a pH optimum of 7.0 and Km values of 1.33 and 2.94 mM for pNPG and cellobiose respectively. It was competitively inhibited by glucose, with a Ki of 30 mM. Evidence was obtained which suggested that the enzyme was produced constitutively and that synthesis was not repressed by glucose. When culture preparations were used in combination with Trichoderma reesei QM9414 and C30 enzyme preparations to saccharify cellulose, 17498 (pND71) was more effective than preparations of PS2-2 in acting synergistically with T. reesei to solubilize more carbohydrate and produce more glucose.     

Inhibition of prolyl hydroxylase by poly(ADP-ribose) and phosphoribosyl-AMP. Possible role of ADP-ribosylation in intracellular prolyl hydroxylase regulation

Poly(ADP-ribose) prepared by incubating NAD+ with rat liver nuclei inhibited the hydroxylation reaction catalyzed by purified prolyl hydroxylase (proline,2-oxoglutarate dioxygenase, EC 1.14.11.2) in vitro. Near complete inhibition of the enzyme was seen in the presence of 6 nM (ADP-Rib)18 with a Ki(app) of 1.5 nM. The monomer unit of poly(ADP-ribose), adenosine diphosphoribose (ADP-Rib), was found to be a weak inhibitor. On the other hand, poly(ADP-ribose)-derived phosphoribosyl-AMP (PRib-AMP) and its dephosphorylated product, ribosyl-ribosyl-adenine (Rib-RibA), inhibited the enzyme in nanomolar concentrations (Ki(app) 16.25 nM). The order of inhibition was (ADP-Rib)18 greater than PRib-AMP, Rib-RibA much greater than ADP-Rib. These results suggested that the 1"----2' ribosyl-ribosyl moiety in these compounds was involved in the inhibition of the enzyme. The possibility that intracellular prolyl hydroxylase is regulated by the involvement of ADP-ribosylation reactions was examined in confluent cultures of skin fibroblast treated with 20 mM lactate. The activity of prolyl hydroxylase was stimulated by 145% over that of untreated cultures. In the lactate-treated cells, the level of NAD+ was lowered and the total ADP-ribosylation of cellular proteins reduced by 40%. These observations imply that the lactate-induced activation of cellular prolyl hydroxylase is mediated by a reduction in ADP-ribosylation and that the synthesis and degradation of ADP-ribose moiety(ies) may possibly regulate prolyl hydroxylase activity in vivo.     

Biochemical and Physiological Responses of Cucumis sativus Cultivars to Different Combinations of Low-Temperature and High Humidity

Low-temperature and high humidity are typical environmental factors in the plastic tunnel and solar greenhouse during the cold season that restricts plant growth and development. Herein, we investigated the impact of different combinations of low-temperature and high humidity (day/night: T1 15/10 °C?+?95%, T2 12/8 °C?+?95%, and T3 9/5 °C?+?95%) along with a control (CK 25/18 °C?+?80%) on cucumber cultivars viz: Zhongnong37 (ZN37: resistant) and Shuyanbailv (SYB: sensitive). The low-temperature and high humidity stresses increased electrolyte leakage (EL), malondialdehyde (MDA), hydrogen peroxide (H₂O₂) and intercellular concentration of carbon dioxide (Ci), and reduced morphological indices, relative water content (RWC), net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (E) and leaf pigments in both cultivars as compared to control (CK). Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were decreased in cv. SYB under stress conditions as compared to cv. ZN37. Low-temperature and high humidity treatments showed an increase in proline and soluble protein content in cv. ZN37 as compared to cv. SYB. Abscisic acid (ABA) and jasmonic acid (JA) were augmented while indole-3-acetic acid (IAA), zeatin (ZT), zeatin riboside (ZR), and gibberellic acid (GA) were decreased in both cultivars. Under T3 (9/5 °C?+?95%), Pn, protoporphyrin, and ZT were extremely decreased by 71.3%, 74.3%, and 82.4%, respectively, in cv. SYB compared to control. Moreover, principal component analysis (PCA) based on physiochemical traits confirmed that cv. ZN37 had the strongest correlation with antioxidant enzymes, proline, and soluble protein content than cv. SYB under low-temperature and high humidity treatments. Our results suggest that a stress-tolerant cultivar mitigates stress damage in cucumber transplants by regulating photosynthetic efficiency, antioxidant capacity and hormonal profile when compared to a stress-sensitive cultivar.

     

Occurrence of hemoglobin in the nitrogen-fixing root nodules of Alnus glutinosa

A true hemoglobin (Hb) was shown to be present in the root nodules of Alnus glutinosa L. After purification by gel filtration and ion exchange, the Hb formed a stable complex with oxygen. This oxygen complex could then be converted to carboxyhemoglobin by treatment with CO. Optical absorption spectra typical of Hb were observed. The molecular weight was estimated to be 15 100 by gel filtration, and 18 300 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Hb was largely insoluble when the initial homogenization was done in the absence of a detergent. Under these conditions much of the Hb appears to be associated with clusters of Frankia , the nitrogen-fixing actinomycete that infects plant cells within the nodules. The exact localization of the Hb in vivo is uncertain. The relatively low average concentration of Hb in Alnus nodules suggests that it is either confined to a relatively small fraction of total nodule volume, or has a function other than facilitation of O₂ transport.