Sexual differentiation of rat liver carbonic anhydrase III

Using radioimmunoassay, the concentration of carbonic anhydrase III in the livers of adult male rats was found to be approx. 30-times greater than that observed in mature females. Castration of male rats led to a marked reduction in liver carbonic anhydrase III concentrations which could be partially restored to control levels by testosterone replacement. Administration of testosterone to ovariectomised female rats induced about a 5-fold increase in liver carbonic anhydrase III concentration. Immunoprecipitation analysis of the products of liver mRNA translation in vitro with antiserum specific for carbonic anhydrase III showed that hormonal control of the levels of carbonic anhydrase III in liver is mediated by changes in the amount of translatable carbonic anhydrase III mRNA. Marked changes in liver carbonic anhydrase III concentrations were also observed in developing and ageing male rats.     

Elevated specific activity of 5′-nucleotidase in a spinal cord myelin fraction from shiverer mice comparison with other myelin-associated enzymes and myelin proteins

Meylin partially purified from spinal cords of dysmyelinating mutant (shiverer) mice had almost three-fold the specific activity of 5′-nucleotidase found in the respective myelin fraction from normal mice. The specific activities of two other normally myelin-associated enzymes, 2′,3′-cyclic nucleotide-3′-phosphohydrolase and carbonic anhydrase, were only slightly higher in the myelin membranes from shiveres, compared to those from controls. In the mutants, the three enzymes probably occur in oligodendrocyte processes. Hhypothetically, the 5′-nucleotidase in the myelin sheath in shiverer and normal mice may be localized in specialized structures.     

Coccidia from the Tiger Salamander, Ambystoma tigrinum, in Northeastern Colorado and in Northern New Mexico

SYNOPSIS. Oocysts of Eimeria ambystomae Saxe, 1955, Eimeria microcapi sp. n., and Eimeria urodela sp. n. are described from the tiger salamander, Ambystoma tigrinum , collected in Colorado and New Mexico. The oocysts of E. ambystomae are ellipsoid, 29.8 × 17.3 (24–38 × 15–25) μm, and the sporocysts lanceolate, 22.6 × 5.4 (16–27 × 5–7) μm. Oocyst and sporocyst residua are present, but not a polar granule and a micropyle. The oocysts and sporocysts of E. microcapi are ellipsoid, measuring respectively 38.1 × 25.3 (35-41 × 23-26) μm and 18.1 × 7.4 (16-19 × 6–8) μm. Oocyst and sporocyst residua, a micropyle (mean 3 μm), and a distinct micropyle cap (2 μm high) are present, but not a polar granule. The oocysts of E. urodela are spheroid, 22.2 (14-26) μm, and the sporocysts lanceolate, 16.3 × 5.8 (12-19 × 4-7) μm. Oocyst and sporocyst residua are present, but a polar granule and a micropyle are absent.     

Involution of the caudal musculature during metamorphosis in the ascidian,Botryllus schlosseri

Summary The caudal musculature of the free-swimming tadpole of the ascidian, B. schlosseri consists of cylindrical mononucleated cells connected in longitudinal rows flanking the axial notochord. During resorption of the larval tail, which is apparently induced by the contraction of the epidermis, muscle cells are dissociated and pushed into the body cavity where most of them are rapidly engulfed by phagocytes. In the initial stages of tail withdrawal muscle cells display surface alterations due to the disruption of intercellular junctions and disarrangement of myofibrils. Extensive degenerative changes, with shrinkage of mitochondria and disintegration of the contractile material are subsequently observed. Lysosomes and autophagic vacuoles are rarely seen and appear to play a secondary role in the degradation of the muscle cells, which occurs predominantly within the phagocytes. Myofilaments and myofibrils have never been observed within autophagic vacuoles. Clumps of muscle fragments and degenerated phagocytes undergo eventual dissolution in the blood lacunae, concomitantly with the differentiation of the young oozooid.This investigation was supported in part by a grant from the Muscular Dystrophy Associations of America and by CNR contract No. 7100396/04115542 from the Istituto di Biologia del Mare, Venice. We gratefully acknowledge the skillful assistance of Mr. G. Gallian, Mr. M. Fabbri and Mr. G. Tognon. We also thank the staff of the Stazione Idrobiologica at Chioggia for collecting the colonies.     

On the carbohydrate—protein linkage group in vitreous humor hyaluronate

Fractional molar ratios of serine, threonine and aspartic acid to neutral sugars in the purified bovine vitreous humor hyaluronate, and a 4–5-fold increase in the percentage of these amino acids and the absence of sugar alditols in hyaluronate reduced with NaBH₄---PdCl₂ after alkali treatment indicated the absence of a carbohydrate—protein linkage. Gel filtration behavior, a decrease in intrinsic viscosity of reduced hyaluronate to about one-half and a significant decrease in its specific rotation suggested that the two antiparallel chains of the hyaluronate double helix may come apart upo reduction. The vitreous humor hyaluronate contained 109.2 ppm of “bound” silicon. It is suggested that the bound silicon may bridge the two antiparallel chains through the neutral sugars and/or through the hydroxyl group of the uronic acid moiety.     

Inhibition of photosynthetic electron transfer by amphotericin B

The polyene antibiotic amphotericin B inhibits photosynthetic electron transfer by Class II maize mesophyll chloroplasts, from water to FeCN, DCIP and diquat but not to plastocyanin. Photosystem 1 activity is also inhibited by amphotericin B, but ferredoxin-NADP reductase activity is not affected. The activity of all the photosynthetic electron transfer systems inhibited by amphotericin B can be restored by the addition of carrier amounts of plastocyanin. The results suggest that amphotericin B inhibits photosynthetic electron transfer by acting only at the plastocyanin site in the chain, and that the primary site of reduction of FeCN and DCIP from water by Class II chloroplasts lies on the reducing side of photosystem 1.