Sporopollenin is the main constituent of the exine layer of spore and pollen walls. The anther-specific chalcone synthase-like (ASCL) enzyme of Physcomitrella patens, PpASCL, has previously been implicated in the biosynthesis of sporopollenin, the main constituent of exine and perine, the two outermost layers of the moss spore cell wall. We made targeted knockouts of the corresponding gene, PpA...

The influence of mannose-containing oligosaccharides on the tissue uptake of glycoproteins has been examined with synthetic glycoconjugates. Oligosaccharides obtained from the acetolysis of bakers' yeast mannan have been coupled to the lysine residues of the cross-linked dimer of bovine pancreatic ribonuclease A and of human serum albumin by reductive amination with cyanoborohydride. 14C-labele...

Microalgae are a polyphyletic and biochemically diverse assemblage of chlorophyll a-containing microorganisms capable of oxygenic photosynthesis that are predominantly found in aquatic environments with observed high levels of ultraviolet (UV) radiation. Certain microalgae produce organic metabolites, such as sporopollenin, scytonemin and mycosporine-like amino acids, to protect themselves from...

The author reviews the information acquired in the last four years on the structure of isoglycans (branched glycans) N-glycosidically linked to asparagine. Developments of the structural methodology of conjugated carbohydrates are analysed with reference to the following procedures: sugar determination, chemical (partial acid hydrolysis, acetolysis, hydrazinolysis—nitrous deamination), and enzy...

Knowledge about the botanical source of honey is very important for the beekeeper while it indicates adequate and abundant supply sources of nectar and pollen for the bees, thus contributing toward improved yield. The present study means to identify the pollen types occurring in 58 samples of honey produced in two states of the northeastern region of Brazil, Piauí (38 samples) and Ceará (20 sam...

The objective of this work was to characterize the morphology and viability of the pollen of 15 genotypes of castor bean (Ricinus communis L.) and to generate information that can assist in the selection of highly promising male parents for future use in genetic improvement programs aimed at producing seeds for oil extraction. Acetolysis and scanning electron microscopy was used to characterize...

Treatment of the 6-aldehyde derived by Moffatt oxidation of 3-O-benzoyl-1,2-O-isopropylidene-alpha-D-ribo-hexofuranose (2c) with the dibromo- or bromofluoromethylene Wittig reagents generated in situ with tetrabromomethane or tribromofluoromethane, triphenylphosphine, and zinc gave the dihalomethyleneheptofuranose analogues 3b and 3d, respectively. Acetolysis, coupling with adenine, and deprote...