Complex genetic effect of B10.D2 (M504) (H-2dm1) mutation

Serological and capping experiments show that the strain B10.D2 (M504) carrying the mutant haplotypeH-2 ^dm1 has two molecules in the products of theD region: H-2D^dm1 and H-2L^dm1 which are detectable by anti-H-2.4 and by anti-H-2.28 sera, respectively. Both these molecules differ serologically from the H-2D^d and H-2L^d molecules of the original (nonmutant) strain B10.D2. A third molecule, different from H-2D and H-2L, was detected inH-2 ^d ,H-2 ^dm2 but not inH-2 ^dm1 products.     

A diploid form ofPhragmites communis,as a possible result of cytogenetical response to ecological stress

Phragmites communis Trin., a highly polymorphous and widely spread species has been described by several authors by the series of polyploidy ranging from triploid to octoploid forms (2n=36 to 96). The original spontaneous diploid form was not known. The present communication describes the experimental transplantation of a dwarf saline form into freshwater substrate conditions, including a new and extremely changed habitus of a sterile plant, the chromosome number of which has been determined as 2n=24.     

Electron-microscopic and autoradiographic study of giant cells of foreign bodies in the focus of aseptic inflammation]

Ultrastructure of sinuous proximal and straight distal tubules, as well as collecting tubules of the cortical layer in the rat kidney fixed with perfusion has been studied with electron microscopic morphometry 7--8 weeks after contralateral nephrectomy. The volume of mitochondria, the area of their crists, the area of the membranes in intracellular labyrinth and other morphometrical parameters have been calculated. Relative volume of mitochondria in the nephron areas studied does not change, while in the collecting tubules it is elevated. The area of crists in mitochondria and "coefficient of morphological organization level" of these organells in the proximal tubules are increased, in the distal do not change, in the collecting tubules increase again. Subcellular changes described are discussed mainly in terms of enhancement of concentrating function of the compensatory-hypertrophic kidney.     

Transbilayer movement of cholesterol in phospholipid vesicles under equilibrium and non-equilibrium conditions

1. The exchange of [3H] cholesterol between phospholipid: cholesterol vesicles and an excess of red cell ghosts is examined. 2. Using a number of different phophatidylcholines, only the cholesterol thought to be associated with the outer half of the bilayer (about 70 percent) is available for exchange, suggesting that at least at equilibrium the transbilayer movement of cholesterol or "flip-flop", occurs very slowly, if it occurs at all. 3. The rate of exchange of cholesterol between the vesicles and the ghosts is dependent on the nature of the fatty acid chain of the phospholipids, being a function of both the fatty acid chain length and the degree of unsaturation. 4. Under non-equilibrium conditions, when cholesterol is being both exchanged and depleted from the lipid vesicles to red cell ghosts, the previously non-exchangeable vesicle cholesterol becomes available for exchange, suggesting that under these conditions "flip-flop" can occur.     

The absence of an effect of photoreactivation on sub-lethal damage accumulation in a photoreactive wallaby cell-line.

Monolayer cultures of JU56 wallaby cells were exposed to germicidal U.V. and/or photoreactivating (PR) light. The U.V. exposures induced dose-dependent cell-death. The survival data are consistent with a common extrapolation number (n) of 6 x 17 +/- 0 x 98 with a D(0) of 123 x 0 +/- 6 x 8 erg/mm2 for photo-reactivated cells and a D0 of 87 x 3 +/- 4 x 9 erg/mm2 for non-photoreactivated cells; the photoreactivation protected the cells with a dose-modification factor of 1 x 41 +/- 0 x 02. Therefore PR is not a shoulder phenomenon and so has no relationship to the repair of sub-lethal damage.     

The zoospore ofOlpidium brassicae

Summary The ultrastructure of the zoospore ofOlpidium brassicae is described and compared with observations made of other zoospores of the uniflagellatePhycomycetes. The zoospore ofO. brassicae is characterized by an extensive, cone-shaped rhizoplast and a lack of a nuclear cap, as well as a side-body complex or a rumposome. Vacuoles which contain osmiophilic material are termed gamma-like particles. Three-dimensional reconstructions based on serial sectioning were made of the organelles in the region of the nucleus, showing that the zoospore ofO. brassicae contains one or at most two elaborately branched mitochondria. Microbodies have a high degree of interconnection and are in intimate association with the mitochondrion, lipid drops, and the nuclear envelope.     

Human liver alcohol dehydrogenase: purification, composition, and catalytic features.

Alcohol dehydrogenase has been purified from human liver by affinity chromatography. Ultracentrifugation, Sephadex G-200 chromatography, and amino acid analyses of multiple preparations demonstrate homogeneity of molecular weight. Sodium dodecyl sulfate disc gel electrophoresis reveals a single species of molecular weight 42 000. Based on a molecular weight of 85 000 for the dimer obtained from the amino acid composition and a molar absorptivity of A280nm0.1% = 0.58, the enzyme contains 3.6-4.2 g-atoms of zinc, as determined by emission spectrography, microwave-induced emission, and atomic absorption spectrometry. Inhibition by o-phenanthroline, (ethylenedinitrilo)tetraacetic acid, and alpha,alpha'-bipyridine demonstrates that zinc is essential to enzymatic function. Detailed kinetic analyses using primary alcohols of the homologous series CH3(CH2)nOH, n = 0-5, and the corresponding aldehydes as substrates show that KM values become smaller as n increases. This suggest that hydrophobic interactions play a role in substrate binding. The availability of well-defined preparations of human liver alcohol dehydrogenase now allows definitive genetic and functional studies of this enzyme to elucidate human ethanol metabolism.     

Daughter cells as an important factor in determining the physiological state of yeast populations

Cells of Candida utilis grown in a single-stage chemostat at D = 0.05, 0.1, 0.25, and 0.35 hr^?l were separated into a fraction of scar-bearing mother cells and a fraction of scar-free daughter cells. The scar-free cells were transferred into small batch cultures where the length of the maturation phase, changes in length and width of cells, specific growth rate, and specific rate of RNA and protein synthesis were examined for 5 hr. The daughter cells grown at D = 0.05 hr^?1 were very small at the moment of separation from the mother cells (about one-third of the mother cell). Their maturation phase (in a batch culture), at the beginning of which they attain the specific growth rate approaching the μ_max of the strain used, lasts for 3 hr. On the other hand, daughter cells grown at D = 0.35 hr^?1 are almost the same size as the mother cells at the moment of separation. After transfer to a batch culture they begin to bud almost immediately. Similarly, in their other morphological and physiological parameters they differ strikingly from immature daughter cells which are formed at low specific growth rates. The importance of these differences from the point of view of mathematical modeling of growth processes is discussed.