The breakdown of 2,3-bis(phospho)-D-glycerate by Fe(III)-haemoglobin.

Fe(III)-haemoglobin is shown to catalyse the hydrolysis of 2,3-bis(phospho)-D-glycerate to Pi and 3-phosphoglycerate, although the rate is slow, even when the protein is present at concentrations in the millimolar range. The rate of hydrolysis is proportional to the subtrate concentration up to at least 10 mM, so if the process is enzymic, the Km must be high.     

Pathological consequences of copper deficiency and cobalt deficiency

Aspects of the pathology of copper deficiency in several species, and cobalt deficiency in sheep, are summarized. An attempt is made to interpret morphological changes in copper-deficient animals in terms of biochemical defects. The common denominator may be mitochondrial lesions, with a generalized effect on energy-dependent synthetic functions of the cell. In copper deficiency, such defects can be attributed to depletion of copper-dependent enzymes, while deficiency of cobalt in ruminants is, in effect, deficiency of vitamin B12. The pathological consequences of vitamin B12 deficiency form a syndrome, notable features of which are neurological and muscular lesions, in which the metabolic consequences of hepatic damage may play a significant role.     

The preparation and properties of pyruvate kinase from yeast

A new method is described for the preparation of pyruvate kinase from yeast. This eliminates proteolysis during the preparation. The molecular weight of yeast pyruvate kinase is 215000, and it is composed of four subunits. Such properties of the enzyme as its extinction coefficient, cold-lability, thiol-group reactivity and binding of Mn(2+) ions are compared with those previously reported for yeast pyruvate kinase prepared by different methods. The specific activity is significantly higher than previously observed, but otherwise the enzyme is similar, apart from its molecular weight and Mn(2+)-binding characteristics, to preparations from Saccharomyces cerevisiae obtained in this laboratory (e.g. Fell et al., 1972, and references therein) and that of C. H. Suelter (e.g. Kuczenski & Suelter, 1971, and references therein), and is different from the enzyme isolated from Saccharomyces carlsbergensis by B. Hess and his co-workers (e.g. Wieker & Hess, 1972, and references therein).     

Isolation of heterothallic yeast strains ofMetschnikowia Kamienski and their mating reactions withChlamydozyma Wickerham spp

Isolation ofMetschnikowia bicuspidata var.australis in the haplophase from Antarctic waters, andM. bicuspidata var.zobellii in haplo-and diplophases at Chatham Is. N.Z., led to the study of mating reactions within theChlamydozyma - Metschnikowia complex. The results indicate the phylogenetic relationships between species. The plant-associatedCh. pulcherrima. Ch. reukaufii, andM. zygota are distinct species; when cross-mated they will conjugate but not produce asci. These three species are closely related toM. bicuspidata; when they are mated withM. bicuspidata and its varieties (var.australis and var.zobellii) asci are produced without spores. The taxonomic status ofM. bicuspidata and its varieties is based on less frequent formation of ascospores between than within taxa.The new varietyM. bicuspidata var.australis and the new combinationsM. zygota andM. bicuspidata var.zobellii are proposed.Contribution No. 925 from the Institute of Marine Sciences, University of Miami, Florida.     

The involvement of nurse cells in oogenesis and embryonic development in the marine sponge,Haliclona ecbasis

Oogenesis and embryonic development in the marine sponge, Haliclona ecbasis, were studied using standard histological procedures. When the oocytes reach a diameter of about 30 μ, nurse cells begin to aggregate around them. Then when the oocytes are about 36 μ in diameter, they begin to engulf the associated nurse cells. Whole nurse cells are engulfed; and although the nucleus of the nurse cells disappears either as or soon after the cells are engulfed, the cytoplasm remains essentially unchanged. The accumulation of these cells within the oocytes most of the cytoplasm is nurse cell cytoplasm. During cleavage of the egg, the engulfed nurse cells are gradually fragmented, but otherwise appear unchanged. At the same time the cytoplasm of the nurse cells is progressively incorporated into that of the blastomeres by what appears to be fusion process. When the latter process is complete, the embryo develops into a typical parenchymula larva.