Toluidine blue staining for cell and tissue biology applications.

Articular cartilage: Collagen II-proteoglycans interactions.Availability of reative groups.Variation in birefringence and differences as compared to Collagen I

Polarization Optical Analysis of Blood Cell Membranes

A filamentous secretion composed of carboxylated and sulfated acid glycosaminoglycans (AGAG), neutral polysaccharides, and protein(s) appears in the lumen of the Malpighian tubes of the fully grown larvae of the bumblebee,Bombus atratus Franklin. A well-ordered macromolecular array was demonstrated specially for the carboxylated AGAG components of this secretion, based on their linear dichroism and birefringence properties. It is suggested that the carboxylated AGAG macromolecules can acquire a helical conformation when present at the lumen of the organ. The mucous secretion elaborated by the Malpighian tubes ofB. atratus is excreted from the larvae in the form of condensed filaments. Its function remains unclear. Globules with concentric lamination containing protein and neutral polysaccharides were seen detaching from the apical border of the epithelial cells of the Malpighian tubes of the fully grown larvae. It could not be established whether they contribute for the elaboration of the filamentous secretion. Morphologically similar globules have been assumed in some other insect groups to originate from cytolysomes. Urate crystals surrounded by a halo of calcium granules were also found in the lumen of the Malpighian tubes ofB. atratus.

A mucous secretion in the malpighian tubes of a neotropical bumblebee, Bombus atratus Franklin

Entheses are specialized biological structures that functionally anchor tendons to bones. The complexity, mechanical characteristics and properties of the entheses, particularly those related to exercise, mechanical load and pathologies, have been extensively analyzed; however, the macromolecular organization of the enthesis fibers, as assessed by polarization microscopy, has not yet been investigated. Morphological and optical anisotropy characteristics, such as birefringence, linear dichroism (LD) and differential interference contrast (DIC-PLM) properties, are thus analyzed in this study of a healthy adult mouse calcaneal tendon-bone enthesis. The molecular and supramolecular order of collagen and GAGs was determined for the collagen bundles of this enthesis. Based on a birefringence plot pattern as well as on metachromasy and linear dichroism after toluidine blue staining at pH 4.0, a similarity between the calcaneal tendon-bone enthesis and cartilage during ossification may be assumed. This similarity is assumed to favor the adequacy of this enthesis to support a compressive load. Considering that the collagen-proteoglycan complexes and the enthesis fibers themselves have a chiral nature, these structures could be acting via reciprocal signaling with the cellular environment of the enthesis.

Optical anisotropy reveals molecular order in a mouse enthesis

The anormal dispersion of birefringence (ADB) and linear dichroism (LD) of poly-l-glutamic acid-Toluidin blue complexes (PGA-TB) and Pseudoisocyanin (N.N.-Methylpseudoisocyanin) (PIC) aggregates were measured.

de Campos Vidal B

Papers

Anormal dispersion of birefringence, linear dichroism, and relationships with ORD (extrinsic cotton effect).