Measuring chlorophyll a and C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer

A compound that quantitatively correlated with chlorophyll a could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60°C but rapidly degraded in sunlight or when acidified. ¹⁴C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H¹⁴CO₃, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll a content and ¹⁴C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).     

Identification of Toxigenic Fusarium Species using PCR Assays

Isolates of the toxigenic cereal pathogens Fusarium culmorum, Fusarium graminearum, Fusarium crookwellense and Fusarium avenaceum, from Poland (48 isolates) and 12 from England, New Zealand, Italy and Canada, were examined using random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR), sequence-characterized amplified regions (SCARs), morphology and mycotoxin production under laboratory conditions. Their DNA products were compared by RAPD-PCR, which showed species-specific bands and the greatest diversity among isolates of F. avenaceum. PCR using three 20-mer-primer-pairs that are reported to be useful for identification of F. culmorum and F. graminearum group 2 confirmed their species-specificity. The same species-specific PCR product was observed in isolates of both nivalenol and deoxynivalenol chemotypes of F. culmorum or F. graminearum. A clear relationship was found between morphological and species-specific PCR identification of F. culmorum and F. graminearum isolates. However, F. avenaceum can be confused when using primers FA-ITS F/R (SCAR 2-14) with Fusarium tricinctum because the same band 272 bp appears in the gel, in both species probes.     

Identification of an alpha3-fucosyltransferase and a novel alpha2- fucosyltransferase activity in cercariae of the schistosome Trichobilharzia ocellata: biosynthesis of the Fucalpha1-->2Fucalpha1-- >3[Gal(NAc)beta1-->4]GlcNAc sequence

Fucose is a major constituent of the protein- and lipid-linked glycans of the various life-cycle stages of schistosomes. These fucosylated glycans are highly antigenic and seem to play a role in the pathology of schistosomiasis. In this article we describe the identification and characterization of two fucosyltransferases (FucTs) in cercariae of the avian schistosome Trichobilharzia ocellata, a GDP-Fuc:[Galbeta1-- >4]GlcNAcbeta-R alpha1-->3-FucT and a novel GDP-Fuc:Fucalpha-R alpha1-- >2-FucT. Triton X-100 extracts of cercariae were assayed for FucT activity using a variety of acceptor substrates. Type 1 chain (Galbeta1- ->3GlcNAc) based compounds were poor acceptors, whereas those based on a type 2 chain (Galbeta1-->4GlcNAc), whether alpha2'-fucosylated, alpha3'-sialylated, or unsubstituted, and whether present as oligosaccharide or contained in a glycopeptide or glycoprotein, all served as acceptor substrates. In this respect the schistosomal alpha3- FucT resembles human FucT V and VI rather than other known FucTs. N- ethylmaleimide, an inhibitor of several human FucTs, had no effect on the activity of the schistosomal alpha3-FucT, whereas GDP-beta-S was strongly inhibitory. Large scale incubations were carried out with Galbeta1-->4GlcNAc, GalNAcbeta1-->4GlcNAcbeta-O -(CH2)8COOCH3 and Fucalpha1-->3GlcNAcbeta1-->2Man as acceptor substrates and the products of the incubations were isolated using a sequence of chromatographic techniques. By methylation analysis and 2D-TOCSY and ROESY1H-NMR spectroscopy the products formed were shown to be Galbeta1-- >4[Fucalpha1-->2Fucalpha1-->3]GlcNAc, GalNAcbeta1-->4[Fucalpha1-- >2Fucalpha1-->3]GlcNAcbe ta-O-(CH2)8COOCH3, and Fucalpha1-->2Fucalpha1-- >3GlcNAcbeta1-->2Man, respectively. It is concluded that the alpha2- FucT and alpha3-FucT are involved in the biosynthesis of the (oligomeric) Lewisx sequences and the Fucalpha1-->2Fucalpha1-->3GlcNAc structural element that have been described on schistosomal glycoconjugates.      

Cladichnus parallelum isp. nov. – a Mid- to Deep-Tier Feeding Burrow System

The ichnospecies Cladichnus parallelum consists of upper components characterized by downward branching, decreasingly inclined tubes, and lower components having horizontal, long, parallel tubes formed in the laminated part of a muddy, marly turbidite. The tubes of both components were successively produced, and the lower ones display an annulated fill. The producers of Cladichnus exhibit thigmotactic and phobotactic behavior in that the tubes are regularly spaced apart, do not cross over- or cross-cut, and their orientation is related to the fabric of the turbidite. The tube fill of both components is enriched in terrigenous material and organic matter suggesting selective feeding on the sediment surface, and the tubes do not show any grain sorting around them. The strong compression of the horizontal tubes suggests that the fill initially had high porosity. The producer of Cladichnus parallelum probably took advantage of burrowing in an anoxic setting; microbes likely played a role in converting organic material stored within the tubes or in processing dissolved compounds drained into the highly porous tubes.