Chromosome numbers in Australian charophytes (Characeae, Charophyceae)

Over the course of a 25 year ecological and taxonomic study, the chromosomes of Australian charophytes (family Characeae) were examined and enumerated. The usual number for members of Chara was n = 14 (for dioecious species) or n = 28 (for monoecious species); although Chara braunii has always been recorded as having n = 14 despite being monoecious. Species in sections Agardhia and Grovesia often had higher ploidy levels [n = 3 x 14 (42), n = 4 x 14 (56)]. The usual number for Australian members of Nitella was n = 9 (for dioecous species) and n = 18, 24 or 27 for monoecious species. Nitella stuartii was an exception, having n = 15 in the specimens studied here. The usual number for monoecious members of Lamprothamnium was n = 28; although, monoecious Lamprothamnium inflatum consistently had n = 14 (populations from Western Australia, Kangaroo Island and South Australia). Chromosome numbers were different for each species of Tolypella examined (n = 11 to 36). There was a high degree of polyploidy within Characeae, and there was evidence that even the lowest numbers of chromosomes represented polyploids (3n for Nitella and 2n for Chara). Polyploidy and consequent doubling or tripling of enzymatic capacity (via potential multiple isozymes) is likely to have a role in the morphological variability and biochemical flexibility of charophytes. Information about the number and appearance of chromosomes (karyotypes) can be used in systematic studies to determine relatedness of taxa and to understand some of the evolutionary processes operating at the population or species level. © 2015 International Phycological Society

Pectic oligosaccharides as prebiotics

Pectic oligosaccharides were observed to have bifidogenic prebiotic properties. Pectic oligosaccharides were also found to possess anti-adhesive properties for food pathogen toxins and they stimulated apoptosis of colon cancer cells. Orange peel albedo (white part) was a good source of pectic oligosaccharides with prebiotic properties. Microwave and autoclave extraction produced pectic oligosaccharides with higher degrees of polymerization than those produced with an ultrafiltration dead-end membrane enzyme reactor. We propose that these larger orange albedo pectic oligosaccharides may have greater persistence through the colon, making them excellent candidates for second generation prebiotic product development

In vitro determination of prebiotic properties of oligosaccharides derived from an orange juice manufacturing by-product stream

Fermentation properties of oligosaccharides derived from orange peel pectin were assessed in mixed fecal bacterial culture. The orange peel oligosaccharide fraction contained glucose in addition to rhamnogalacturonan and xylogalacturonan pectic oligosaccharides. Twenty-four-hour, temperature- and pH-controlled, stirred anaerobic fecal batch cultures were used to determine the effects that oligosaccharides derived from orange products had on the composition of the fecal microbiota. The effects were measured through fluorescent in situ hybridization to determine changes in bacterial populations, fermentation end products were analyzed by high-performance liquid chromatography to assess short-chain fatty acid concentrations, and subsequently, a prebiotic index (PI) was determined. Pectic oligosaccharides (POS) were able to increase the bifidobacterial and Eubacterium rectale numbers, albeit resulting in a lower prebiotic index than that from fructo-oligosaccharide metabolism. Orange albedo maintained the growth of most bacterial populations and gave a PI similar to that of soluble starch. Fermentation of POS resulted in an increase in the Eubacterium rectale numbers and concomitantly increased butyrate production. In conclusion, this study has shown that POS can have a beneficial effect on the fecal microflora; however, a classical prebiotic effect was not found. An increase in the Eubacterium rectale population was found, and butyrate levels increased, which is of potential benefit to the host

Cell wall antibodies without immunization:Generation and use of de-esterified homogalacturonan block-specific antibodies from a naive phage display library

Homogalacturonan (HG) is a multi-functional pectic polysaccharide of primary cell walls involved in calcium cross-linking and gel formation, and the regulation of ionic status and porosity of the cell wall matrix, and is a source of oligosaccharins functioning in development and defence. Phage display monoclonal antibodies with specificity for de-esterified stretches ('blocks') of pectic HG have been isolated from a naive phage display library without the need for immunization of animals or conjugation of an oligosaccharide to protein. These antibodies, designated PAM1 and PAM2, bind specifically to de-esterified and un-substituted HG. Assays with a series of pectins de-esterified by the action of plant or fungal pectin methyl esterases indicated that the antibodies were specific to de-esterified blocks resulting from the blockwise action of plant pectin methyl esterases. Analysis of antibody binding to a series of oligogalacturonides indicated that optimal binding required in the region of 30 de-esterified Gala residues. The recognition of such a large epitope by these antibodies allows the HG block architecture of primary cell walls to be identified and localized for the first time. Furthermore, we have demonstrated that monoclonal antibodies with high specificity and avidity to cell wall epitopes can be generated using a 'single pot' phage display approach