Structural features of a sulphated,fucose-containing polysaccharide from the brown seaweed dictyota dichotoma

A sulphated heteropolysaccharide (～15% of the acid-extractable material) isolated from the brown alga Dictyota dichotoma contains residues of D-glucuronic acid, D-galactose, D-mannose, D-xylose, and L-fucose¹. Partial hydrolysis of the polysaccharide with acid gave one neutral and two acidic oligosaccharides. The behaviour towards periodate of the polysaccharide before and after partial hydrolysis, alkali-treatment, and methanolysis has been studied. Evidence is thereby provided that the polysaccharide is partially sulphated and composed of (1→4)-linked residues of D-glucuronic acid, D-galactose, D-mannose, and D-xylose, and (1→2)-linked L-fucose.     

Production of fertile transgenic wheat plants by laser micropuncture.

A modified, non-damaging, protocol for the production of fertile transgenic wheat (Triticum aestivum L. cultivar Giza 164) plants by laser micropuncture was developed. The new homemade setup secures the transformation of as many as 60 immature embryo-derived calli (10000 cells each) in less than one hour using a UV excimer laser with two dimensional translation stages, a suitable computer program and a proper optical system. Five-day-old calli were irradiated by a focused laser microbeam to puncture momentarily made self-healing holes ( approximately 0.5 microm) in the cell wall and membrane to allow uptake of the exogenous DNA. The plant expression vector pAB6 containing bar gene as a selectable marker for the herbicide bialaphos resistance and GUS (uidA) gene as a reporter gene was used for transformation. No selection pressure was conducted during the four-week callus induction period. Induced calli were transferred to a modified MS medium with 1 mg l(-1) bialaphos for regeneration, followed by selection on 2 mg l(-1) bialaphos for rooting. Three regenerated putative transgenic events were evaluated for the integration and stable expression of both genes and results indicated that this modified procedure of laser-mediated transformation can be successfully used in transforming wheat.     

Can the heart initiate some forms of hypertension?

An active role for the heart in the initiation of hypertension can be postulated in two different sets of conditions. 1) Activation of pressor reflexes from the ventricles, coronary arteries, or aorta has been shown to produce substantial rises of arterial pressure; experience with postcoronary bypass hypertension suggests that these reflexes could be responsible for some types of paroxysmal hypertension. 2) Increased cardiac action caused by either neural or humoral factors can initiate a rise in cardiac output and blood pressure; sustained hypertension could be produced experimentally in conscious dogs by electrical stimulation of the stellate ganglion or by continuous infusion of dobutamine in the left coronary artery. Evidence suggesting that this could occur in humans was derived from a study of the relationship of cardiac output to cardiopulmonary volume in essential hypertension.     

The effect of in vitro pretreatments on subsequent shoot organogenesis from excised Rubus and Malus leaves

Shoot regeneration from Rubus leaves was obtained on a medium containing MS salts, vitamins and sugars, Staba vitamins, casein hydrolysate (100 mg l^–1) and 10 M thidiazuron. Shoot regeneration from Malus leaves was obtained on N⁶ rice anther medium with 5 M thidiazuron. In vitro pretreatment of source shoots with either colchicine or thidiazuron enhanced the organogenic potential of detached leaves of two Rubus hybrids. The response to colchicine was quadratic and occurred at non-mutagenic concentrations (75–250 M). The response to thidiazuron was exponential between 0 and 5 M. When applied as a pretreatment, the effectiveness of several different cytokinins (benzyladenine, thidiazuron, zeatin) at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indolebutyric acid - MS Murashige & Skoog basal medium devoid of plant growth regulators - OI organogenesis-initiating subculture - PTI colchicine pretreatment subculture - PTII cytokinin pretreatment subculture - NAA naphthaleneacetic acid - TDZ thidiazuron - zeatin trans-zeatin     

Solid-state fermentation of carob pods byAspergillus niger for protein production: effect of particle size

Two strains ofAspergillus niger were cultured in solid-state fermentation system on carob pods ground from 1.25 to 8 mm diam. A particle size of 2.5 mm gave the highest protein content of the final product (20%, w/w) and 52% of the total soluble carbohydrates were utilized. The total tannin concentration of the carob pods decreased by 83% in 4 days of fermentation.T. Smail and O. Salhi are with the Laboratory of Microbiology, U.R.B.A.F., Institute of Biology, Tizi-Ouzou University, Algeria. J.S. Knapp is with the Department of Microbiology, The University of Leeds, Leeds LS2 9JT, UK;     

Evidence for root Fe nutrition in Hydrilla verticillata Royle

Summary The uptake of Fe by roots and apical leaves of the submersed aquatic plant Hydrilla verticillata Royle was studied using ⁵⁹FeEDTA. ⁵⁹FeEDTA was absorbed by both roots and apical leaves, and translocated to the other parts of the plant. Approximately 3% of the total ⁵⁹FeEDTA absorbed by the roots over a period of 60 h was translocated to the leaves. Downward translocation of ⁵⁹FeEDTA from the apical portion of the plant to the lower leaves was approximately 21% of the amount absorbed.Published as Journal Series No 333 of the Florida Agricultural Experiment Station.     

Carbohydrates of the brown seaweed Dictyota dichotoma

The fucose-containing polysaccharides of the brown alga Dictyota dichotoma were extracted with either trichloroacetic acid or HCl to give both water-soluble and water-insoluble materials. The latter had a high proportion (16 to 11%) of protein, and although all the sugars found in the water-soluble extracts were present, the major sugar in these water-insoluble polysaccharides was glucose. The water-soluble material extracted with HCl was a protein-free sulphated heteropolysaccharide. Complete removal of a glucan from the water-soluble extract was achieved by fractional precipitation with ethanol. The recovered glucan-free sulphated polysaccharide, which was rich in glucuronic acid, galactose, fucose and sulphate, showed high anticoagulating activity.     

The DNA polymerase from the archaebacterium Sulfolobus acidocaldarius: a thermophilic and thermoresistant enzyme which can perform automated polymerase chain reaction

A DNA polymerase purified from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius was used to perform automated DNA amplification at 70 degrees C as well as site directed mutagenesis by Polymerase Chain Reaction (P.C.R.). The yield of amplification performed at optimum MgCl2 concentration for the Taq or the S. acidocaldarius DNA polymerase, for the same DNA target, was equivalent. The ability of S. acidocaldarius DNA polymerase to perform P.C.R. under less stringent requirement of MgCl2 concentration gives this enzyme a non-negligible advantage over the Taq DNA polymerase.