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In electron micrographs it could be shown that hazelnut (Corylus avellana) pollen grains are covered on their surface by a diffusible 10 nm thick lamellar layer. On pollen surface as well as in pollen extract this layer could be precipitated and stained by the polycationic dye Cuprolinic blue. By subsequent application of both immunogold labeling with serum from a hay-fever patient allergic to tree pollen grains and histochemical detection with Cuprolinic blue this pollen surface layer proved to be an effective antigen.

The initial reactions of transitory starch degradation in Spinacia oleracea L. were investigated using an in-vitro system composed of native chloroplast starch granules, purified chloroplast and non-chloroplast forms of phosphorylase (EC 2.4.1.1) from spinach leaves, and α-amylase (EC 3.2.1.1) isolated from Bacillus subtilis. Starch degradation was followed by measuring the release of soluble glucans, by determining phosphorylase activity, and by an electron-microscopic evaluation following deep-etching of the starch granules. Starch granules were readily degraded by α-amylase but were not a substrate for the chloroplast phosphorylase. Phosphorolysis and glucan synthesis by this enzyme form were strictly dependent upon a preceding amylolytic attack on the starch granules. In contrast, the non-chloroplast phosphorylase was capable of using starch-granule preparations as substrate. Hydrolytic degradation of the starch granules was initiated at the entire particle surface, independently of its size. As a result of amylolysis, soluble glucans were released with a low degree of polymerization. When assayed with these glucans as substrate, the chloroplast phosphorylase form exhibited a higher apparent affinity and a higher reaction velocity compared with the non-chloroplast phosphorylase form. It is proposed that transitory starch degradation in vivo is initiated by hydrolysis; phosphorolysis is most likely restricted to a pool of soluble glucan intermediates.

Summary It is an experimental fact that lactoferrin binds to DNA. In the present study, a lactoferrin-gold complex was first bound by the cell surface, then became internalized (inside coated or smooth vesicles). Intracellularly the complex appeared in tube-like or vesicle-like structures, which approximated the nucleus, and some vesicles even showed indications of association with the external nuclear membrane. Neither membrane binding, nor internization of the lactoferrin-gold complex had taken place in cells pretreated with DNase.

The apical portion of the uterine lining of the ovoviviparous fire salamander, Salamandra salamandra, was studied by the freeze-fracture technique in conjunction with the polyene antibiotic filipin. Filipin-sterol complexes were found in the luminal plasmalemma and in the membranes limiting the mucous secretory granules typical of this epithelium. In all females, but particularly in non-pregnant females, more or less discrete clusters of filipin-sterol complexes were occasionally found overlying heavily affected secretory granules. The findings are discussed with regard to comparable results (Orci et al. 1980) based on the examination of collapsed and stretched urinary bladders of toads.

Several types of the 14–15 kDa fatty acid-binding proteins (FABPs) are known to occur in the cytosol of mammalian cells. With antibodies raised against the cardiac-type protein from bovine heart, immunoblots indicated a more widespread distribution of the cardiac FABP in subcellular fractions, such as mitochondria and nuclei. A detailed view was obtained when the post-embedding protein A-gold labeling method was applied to cross-sections of heart cells and isolated subcellular fractions. Cardiac FABP in myocytes was associated with myofibrils and localized within mitochondria and nuclei. After subfractionation of mitochondria, the binding protein was recovered with matrix proteins only. A non-competitive enzyme-linked immunosorbent assay (ELISA) of the direct type was developed specifically for bovine cardiac FABP. This assay was sensitive in the range of 0.05 to 1 ng, and concentrations of cardiac FABP per mg protein were found for cytosol, matrix and nuclei to be around 3.18, 0.18 and 0.03 μg, respectively. The newly found compartmentation of cardiac FABP in the heart cell must be considered when the true functions of the protein, yet to be defined, are studied.

Decorin, a small dermatan-sulfate proteoglycan, participates in extracellular matrix assembly and influences directly and indirectly cell behavior via interactions with signaling membrane receptors and transforming growth factor (TGF)-beta. We have therefore compared the development of tubulointerstitial kidney fibrosis in wild-type (WT) and decorin-/- mice in the model of unilateral ureteral obstruction. Without obstruction, kidneys from decorin-/- mice did not differ in any aspect from their WT counterparts. However, already 12 hours after obstruction decorin-/- animals showed lower levels of p27(KIP1) and soon thereafter a more pronounced up-regulation and activation of initiator and effector caspases followed by enhanced apoptosis of tubular epithelial cells. Later, a higher increase of TGF-beta1 became apparent. After 7 days, there was an up to 15-fold transient up-regulation of the related proteoglycan biglycan, which was mainly caused by the appearance of biglycan-expressing mononuclear cells. Other small proteoglycans showed no similar response. Because of enhanced degradation of type I collagen, end-stage kidneys from decorin-/- animals were more atrophic than WT kidneys. These data suggest that decorin exerts beneficial effects on tubulointerstitial fibrosis, primarily by influencing the expression of a key cyclin-dependent kinase inhibitor and by limiting the degree of apoptosis, mononuclear cell infiltration, tubular atrophy, and expression of TGF-beta1.