Intramitochondrial binding of ruthenium red in degenerating chondroblasts

Analysis of the structure of fish lymphocystis disease virions from skin tumours of pleuronectes

Virions of fish lymphocystis disease (FLDV) from tumour-carrying-fishes (flounder, dab, plaice and gurnard) collected in the North Sea were isolated directly from the tumours and purified by sucrose and subsequent caesium chloride gradient centrifugation. They were studied by electron microscopy using embedding methods, negative staining and using metal shadowing methods. Tumours of dermal connective fish tissue showed particles with hexagonal outlines. Occasionally, an "empty structure" was observed. Subunits of the virus membrane were identified after 3 per cent phosphotungstic acid (PTA) or 0.2 per cent Ruthenium red (RR) staining. FLDV measures 199-227 nm in diameter.

Affinity of intramitochondrial granules for ruthenium red accompanying induced cell death in chick embryos

To test the hypothesis that ruthenium red binding of intramitochondrial granules might reflect an altered or pathological state of membranes associated with degeneration, embryos were treated with 6-AN to induce cell death in cartilaginous skeletons of chick embryos. Cervical cartilage from normal, 6-AN-treated and nicotinamide-alleviated 6-AN embryos was examined ultrastructurally for presence of IM RR-positive granules. Mitochondria of normal cervical chondroblasts which undergo normal phenotypic expression acquire RR-positive granules, although few mature cells are observed in young embryos. Necrotic chondroblasts, chondroblasts in various stages of degeneration, and proliferating chondrogenic cells of 6-AN-treated embryos all demonstrated induced RR-positive IM granules. Foci of degenerating chondroblasts, with mitochondria demonstrating RR granules, were observed infrequently in teratogen-alleviated tissue. The cytological features induced by 6-AN confirm its lethal effect and the degenerative effect on membranes presumably "unmasks" mitochondrial Ca-affinity sites which then become RR-positive. Cytochemical observations correspond with the biochemical and structural changes induced by 6-AN and confirm the hypothesis that RR-positive sites are the result of pathological changes.

Thallium-induced achondroplasia in chicken embryos and the concept of critical periods during development

Achondroplasia was induced in chicken embryos by in ovo application of 0.6 mg/egg thallium sulfate. The critical (sensitive) period for production of achondroplasia began on day 5 of incubation and ended at the start of HH stage 35 (8.5 days). The end of the critical period was accurately timed and found to be 205-207 hours of incubation and to coincide with a 66% decrease in growth rate of the embryos. Treatment resulted in reduced tibial growth one day later, tibial angulation two days later, and chrondrocytic necrosis four days later. The last was therefore not the cause of the angulation. Tibias were taken from thallium-treated and control donor embryos of various ages and grafted to the chorioallantoic membranes of treated and control host embryos of various ages during and outside the critical period and achondroplastic changes induced in grafted tibias exposed to thallium while on the chorioallantoic membrane. The critical period was extended into day 10 of incubation in such grafted tibias. Tibias maintained for seven days in organ culture were achondroplastic if pretreated with thallium at seven or eight days of incubation but not at ten days. Exposure of as little as 0.5 hour was sufficient to elicit micromelia when the tibias were grafted or organ cultured. Thallium therefore rapidly binds to skeletal tissues during a critical period of embryonic development but this critical period may be extended when tibias are removed from the embryo.