Structural characterization of polysaccharide obtained from red seaweed Gracilaria caudata (J Agardh)

Polysaccharides extracted from six red seaweed species growing in Vietnam have been studied. Characterisation of their structure by chemical and spectroscopic methods showed that all of them have a basic repeating structure of alternating 3-linked b-D-galactopyranosyl and 4-linked 3,6-anhydro a-L-galactopyranosyl units with substituted methyl ether groups. The native agar offers only weak gelling abilities owing to the 4-linked a-L-galactopyranosyl 6-sulfate as its precursor. Conversion of this unit into the corresponding 3,6-anhydride by treating with hot alkali generally led to gel strength increasing. The agars from G. fisheri and G. firma are poorly substituted, while those from G.asiatica, G.tenustipitata and G. heteroclada are partly methylated on position 6 of the 3-linked b-D- galactose. Agar from Gelidiella acerosa is partlly methylated on both positions 6 and 2 of the 4linked 3,6-anhydro a-L-galactose. The alkali- modified agars have been obtained in acceptable quantities with gel strength of 300932 g/cm2. The obtained results showed that all the six algal species are suitable as raw material for commercial agar production and worthy of further cultivation

Download Full-text

Structural characterization of cold extracted fraction of soluble sulfated polysaccharide from red seaweed Gracilaria birdiae

Carbohydrate Polymers ◽

10.1016/j.carbpol.2007.06.026 ◽

2008 ◽

Vol 71 (4) ◽

pp. 559-565 ◽

Cited By ~ 111

Author(s):

J MACIEL ◽

L CHAVES ◽

B SOUZA ◽

D TEIXEIRA ◽

A FREITAS ◽

...

Keyword(s):

Structural Characterization ◽

Sulfated Polysaccharide ◽

Red Seaweed ◽

Gracilaria Birdiae

Download Full-text

New ultrastructural findings about Borrelia burgdorferi by cryofixation, negative staining, thin sectioning and scanning techniques

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160467 ◽

1990 ◽

Vol 48 (3) ◽

pp. 582-583

Author(s):

S. F. Hayes ◽

M. D. Corwin ◽

T. G. Schwan ◽

D. W. Dorward ◽

W. Burgdorfer

Keyword(s):

Lyme Disease ◽

Borrelia Burgdorferi ◽

Structural Characterization ◽

Negative Staining ◽

Low Speed ◽

Thin Sectioning ◽

Ultrastructural Findings

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.

Download Full-text