Determination of ß-N-oxalyl-L-α,ß-diaminopropionic acid and homoarginine in Lathyrus sativus and Lathyrus cicera by capillary zone electrophoresis.

BACKGROUND: Lathyrus species as legumes represent an alternative protein source for human and animal nutrition. Heavy consumption of these species can lead to lathyrism, caused by the non-protein amino acid ß-N-oxalyl-l-α,ß-diaminopropionic acid (ß-ODAP). Currently, there is no well-defined level below which ß-ODAP is considered non-toxic. In this work, the ß-ODAP content was determined in L. sativus and L. cicera samples to assess their potential toxicity. Homoarginine is another non-protein amino acid found in Lathyrus spp. with interesting implications for human and animal nutrition. RESULTS: The level of ß-ODAP found in these two species ranged from 0.79 to 5.05 mg g(-1). The homoarginine content of the samples ranged from 7.49 to 12.44 mg g(-1). CONCLUSION: This paper describes an accurate, fast and sensitive method of simultaneous detection and quantification of ß-ODAP and homoarginine by capillary zone electrophoresis in L. cicera and L. sativus seeds. Moreover, several methods of extraction were compared to determine the highest performance.

Fungal lectin of Peltigera canina induces chemotropism of compatible Nostoc cells by constriction-relaxation pulses of cyanobiont cytoskeleton.

A glycosylated arginase acting as a fungal lectin from Peltigera canina is able to produce recruitment of cyanobiont Nostoc cells and their adhesion to the hyphal surface. This implies that the cyanobiont would develop organelles to motility towards the chemoattractant. However when visualized by transmission electron microscopy, Nostoc cells recently isolated from P. canina thallus do not reveal any motile, superficial organelles, although their surface was covered by small spindles and serrated layer related to gliding. The use of S-(3,4-dichlorobenzyl)isothiourea, blebbistatin, phalloidin and latrunculin A provide circumstantial evidence that actin microfilaments rather than MreB, the actin-like protein from prokaryota, and, probably, an ATPase which develops contractile function similar to that of myosin II, are involved in cell motility. These experimental facts, the absence of superficial elements (fimbriae, pili or flagellum) related to cell movement, and the appearance of sunken cells during of after movement verified by scanning electron microscopy, support the hypothesis that the motility of lichen cyanobionts could be achieved by contraction-relaxation episodes of the cytoskeleton induced by fungal lectin act as a chemoattractant.

Isolation and characterization of a cyanobacterium-binding protein and its cell wall receptor in the lichen Peltigera canina.

Peltigera canina, a cyanolichen containing Nostoc as cyanobiont, produces and secretes arginase to a medium containing arginine. Secreted arginase acts as a lectin by binding to the surface of Nostoc cells through a specific receptor which develops urease activity. The enzyme urease has been located in the cell wall of recently isolated cyanobionts. Cytochemical detection of urease is achieved by producing a black, electron-dense precipitate of cobalt sulfide proceeding from CO(2) evolved from urea hydrolysis in the presence of cobalt chloride. This urease has been pre-purified by affinity chromatography on a bead of active agarose to which arginase was attached. Urease was eluted from the beads by 50 mM alpha-D-galactose. The experimentally probed fact that a fungal lectin developing subsidiary arginase activity acts as a recognition factor of compatible algal cells in chlorolichens can now been expanded to cyanolichens.

A Lichen Lectin Specifically Binds to the alpha-1,4-Polygalactoside Moiety of Urease Located in the Cell Wall of Homologous Algae.

A lectin from the lichen Evernia prunastri developing arginase activity (EC. 3.5.3.1) binds to the homologous algae that contain polygalactosilated urease (EC. 3.5.1.5) in their cell walls acting as a lectin ligand. The enzyme bound to its ligand shows to be inactive to hydrolyze of arginine. Hydrolysis of the galactoside moiety of urease in intact algae with alpha-1,4-galactosidase (EC. 3.2.1.22) releases high amount of D-galactose and impedes the binding of the lectin to the algal cell wall. However, the use of beta-,4-galactosidase (EC.3.2.1.23) releases low amounts of D-galactose from the algal cell wall and does not change the pattern of binding of the lectin to its ligand. The production of glycosilated urease is restricted to the season in which algal cells divide and this assures the recognition of new phycobiont produced after cell division by its fungal partner.