A (1→4)-β-mannan-specific monoclonal antibody and its use in the immunocytochemical location of galactomannans

Galactomannan was coupled to a protein carrier for the preparation of monoclonal antibodies. The monoclonal antibodies generated bound to galactomannans from different sources as well as to glucomannan and galactoglucomannan. One monoclonal antibody, BGM C6, was characterised and found to be specific for (1-->4)-beta-linked mannopyranosyl residues; it had a binding affinity estimated at 1x10(-6) M for the (1-->4)-beta-linked mannohexaose. BGM C6 was used in immunogold labelling studies to locate galactomannans in the endosperm walls of normal coconuts (Cocos nucifera L.) and those of the mutant makapuno at two different developmental stages. The pattern and intensity of antibody labelling varied for each type of coconut at the mature and immature stages, indicating differences in the galactomannan composition of the endosperm walls.     

Identification of a Novel Triterpenoid Saponin from Pisum sativum as a Specific Inhibitor of the Diguanylate Cyclase of Acetobacter xylinum

A specific and highly potent inhibitor of diguanylate cyclase,the key regulatory enzyme of the cellulose synthesizing apparatusin the bacterium Acetobacter xylinum, was isolated from extractsof etiolated pea shoots (Pisum sativum). The inhibitor has beenpurified by a multistep procedure, and sufficient amounts ofhighly purified compound (3-8 mg) for spectral analysis wereobtained. The structure of this compound was established as3-O-a-L-rhamnopyranosyl-(l     

Re‐evaluation of the role of a transmitting tract‐specific glycoprotein on pollen tube growth

It has been proposed that a stylar glycoprotein, the transmitting tissue-specific (TTS) protein isolated from Nicotiana tabacum, serves both as a growth stimulant, by providing a source of nutrients, and as an attractant for pollen tubes during their growth through the style. Working with a galactose-rich style glycoprotein (GaRSGP) that is the N. alata homologue (97% homology) of the TTS protein, a series of experiments, similar to those done with the TTS protein, was performed. Evidence was found for inhibition of pollen tube growth at high concentrations, but no evidence was found for stimulation of growth at concentrations up to 2 mg ml^–1. No effect as a pollen tube attractant was detected. The discrepancies in the features and functionality between these homologous glycoproteins in the closely related Nicotiana species warrants further investigation before a general function is assigned to these molecules.     

Histochemistry and composition of the cell walls of styles of Nicotiana alata Link et Otto

The cell walls of styles of Nicotiana alata Link et Otto (ornamental tobacco; Solanaceae) were analysed chemically and examined histochemically. Cell-wall preparations were obtained from whole styles and from isolated transmitting-tissue cells. The style epidermal cells were shown histochemically to have thick, lignified secondary walls. These walls probably constituted a large proportion of the cell-wall preparation from whole styles as analysis of whole-style walls indicated that the major polysaccharides were xylans and cellulose, which are typical of lignified secondary walls of Magnoliopsida (dicotyledons). Lignification of the style epidermal walls was also demonstrated histochemically in 10 other species (5 genera including Nicotiana) of the sub-family Cestroideae of the Solanaceae, but not in 15 species (9 genera) of the sub-family Solanoideae of the Solanaceae, nor in 3 other species of dicotyledons and 2 species of Liliopsida (monocotyledons). Analysis of the cell-wall preparation from isolated transmitting-tissue cells of N. alata indicated that these contained cellulose, xyloglucans, and pectic polysaccharides, which is typical of primary cell walls of dicotyledons. However, the analysis indicated that the walls also contained an unusually high proportion of Type II arabinogalactans. Staining of the transmitting-tissue cell-wall preparation with β-glucosyl Yariv reagent, a histochemical reagent specific for arabinogalactan proteins, confirmed their presence, which may be related to the role of these cells in secreting the stylar extracellular matrix.     

BETA/KAPPA-CARRAGEENANS AS EVIDENCE FOR CONTINUED SEPARATION OF THE FAMILIES DICRANEMATACEAE AND SARCODIACEAE (GIGARTINALES,RHODOPHYTA)1

The Dicranemataceae consists of five species in four genera of macroscopic red algae endemic to the southern half of Australia plus a single species from southern Japan. Investigations of the nonfibrillar wall components of five of the six species show that all are composed mainly of hybrid (or mixed) beta (β)/kappa(κ)-type carrageenans. Detailed studies of Tylotus obtusatus (Sonder) J. Agardh show that it produces the largest dry-weight percentage of β-carrageenan yet recorded. Monosaccharide composition, total sulfate content, sulfation pattern revealed by infrared and ¹³C-nuclear magnetic resonance spectroscopy and a positive specific optical rotation ([α]_D+ 54°) are indicative of a low-sulfate-containing carrageenan with gelling properties similar to those of agar and furcellaran. β-carrageenan is recorded in only five other red algal species belonging to relatively unrelated families, and we conclude that its uniform occurrence in the highly specialized family Dicranemataceae has phylogenetic significance. Chemical and anatomical examination of the genus Sarcodia, which produce lambda-type carrageenan in both its gametophytic and tetrasporophytic phases, suggests that, despite the recent proposal to incorporate the Dicranemataceae into the Sarcodiaceae, the two families should continue to be separated.     

Composition of High Molecular Weight Excretions-Secretions from Infective Larvae of Meloidogyne javanica

Infective larvae (J2) of Meloidogyne javanica were incubated in distilled water for up to 14 days, and their high molecular weight (> 1,000 daltons) excretions-secretions (ES) were isolated and partially characterized. The ES consisted of a mixture of proteins, glycoproteins, and proteoglycans or polysaccharides as revealed by differential staining on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and compositional analysis. Carbohydrate, with approximately equal amounts of neutral monosaccharides and hexosamines, was the major constituent of the ES, with only low levels of protein detected. Acidic sugar residues, including sialic acids, were not detected.