After its endocytosis from the colloid, some thyroglobulin (Tg) is transcytosed intact across thyrocytes, accounting in part for its presence in the circulation. We previously showed that megalin (gp330), an endocytic Tg receptor, mediates apical to basolateral Tg transcytosis. Here we investigated whether a portion of megalin remains combined with Tg after its transcytosis, using studies with ...

The nuclear inelastic scattering signatures of the low-spin centers of the methanosulphonate, tosylate, and perchlorate salts of the spin crossover polymer ([Fe(II)(4-amino-1,2,4-triazole)3])n have been compared for the low-spin phase, for the mixed high-spin and low-spin phases, as well as for Zn(II) diluted samples. Within this series a change in the vibrational pattern in the 320–500 cm ́1 re...

The role of antioxidants in maintaining the functional integrity of adrenocortical cells during in vitro exposure to endosulfan, an organochlorine pesticide, was investigated in rainbow trout (Oncorhynchus mykiss). Aminotriazole (ATA), an inhibitor of catalase (CAT), L-buthionine sulfoximine (L-BSO), an inhibitor of glutathione (GSH) synthesis, and N-acetyl cysteine (NAC), a glutathione precurs...

Hormone secretion by thyrocytes occurs by fluid phase uptake and lysosomal degradation of the prohormone thyroglobulin (Tg). However, some Tg internalized by megalin bypasses lysosomes and is transcytosed across cells and released into the bloodstream. Because the hormone content of Tg is variable, we investigated whether this affects transcytosis. We found that rat Tg with a low hormone conten...

In oxygen-sensitive excitable cells, responses to hypoxia are initiated by membrane depolarization due to closing of the K channels that is thought to be mediated by a decrease in reactive oxygen species (ROS). Because the mechanisms of hypoxic inhibition of ion transport of alveolar epithelial cells (Planes C, Friedlander G, Loiseau A, Amiel C, and Clerici C. Am J Physiol Lung Cell Mol Physiol...

Among chlorosis-inducing herbicides that interfere with carotenoid synthesis two groups o f different potency can be discriminated (group 1; aminotriazole amd haloxidine; group 2 with more extensive photodestructions: pyridazinone herbicides and difunon). After application of herbicides o f group 2 colored carotenoids were completely absent and preexisting chlorophyll was degraded by photochemi...

Neutrophils, triggered by heat-aggregated human IgG (Agg.IgG), were found to lyse chicken red blood cells (CRBC) as determined by a 51Cr release method. The lysis was inhibited by azide, catalase, chloride-free medium and amino acids, suggesting the requirement for myeloperoxidase (MPO), hydrogen peroxide (H2O2), chloride ions (Cl-), and hypochlorous acid (HOC1), respectively. These results ind...

The model hydrogen peroxide-myeloperoxidase-chloride system is capable of generating the powerful oxidant hypochlorous acid, which can be quantitated by trapping the generated species with the beta-amino acid, taurine. The resultant stable product, taurine chloramine, can be quantitated by its ability to oxidize the sulfhydryl compound, 5-thio-2-nitro-benzoic acid to the disulfide, 5,5'-dithiob...

At the time of fertilization, sea urchin eggs release a peroxidase which, together with H2O2 generated by a respiratory burst, is responsible for hardening of the fertilization membrane. We demonstrate here that the ovoperoxidase of unfertilized eggs is located in cortical granules and, after fertilization, is concentrated in the fertilization membrane. Fertilization of sea urchin eggs or their...

The distribution of endogenous peroxidase activity in the lacrimal gland of the rat during postnatal development was investigated by electron microscope cytochemistry Peroxidase activity is first found 6 hr after birth in only a few acinar cells At this stage, reaction product fills only localized segments of the scant rough endoplasmic reticulum and of the perinuclear cisternae. Peroxidase act...