Two dicentric Y isochromosomes,one without the Yqh heterochromatic segment

Summary Two women with primary amenorrhoea and few other stigmata of Turner's syndrome were found to be chromosome mosaics: 45,X/46,X,idic(Y). In Case 1, the dicentric isochromosome Y was found to have a long-arm breakpoint of formation. This structure was interpreted as containing two Y short arms and centromeres separated by a region derived from the proximal Y long arm. One of the centromeres in the Case 1 —idic(Y) was suppressed in 80% of cells in blood, and in these cells it appeared as a regular Y-shaped chromosome. In Case 2 the idic(Y) was derived by a short-arm breakpoint of formation. In all the dicentrics of this case with one primary constriction (functional monocentrics) there was a single Cd band. In the 10% of dicentrics with two primary constrictions, there were two Cd bands. It is argued that the instability of sex isochromosomes is due to this functional dicentricity in some cells. These cases are compared with 42 other Y isochromosomes with various short- and long-arm breakpoints of formation. It is suggested that some of the nonheterochromatic, nonfluorescent Y chromosomes previously reported may be explained as dicentric i(Y) with proximal long-arm breakpoints of formation and one suppressed centromere.     

A light microscopical investigation of amoebal and plasmodial mitosis in the MyxomyceteEchinostelium minutum

Summary Light microscopical observations on mitosis in living material of the amoebal and plasmodial phases of the MyxomyceteEchinostelium minutum de Bary (orderEchinosteliales) are reported for the first time. The uninucleate amoebal cell undergoes centric, open spindle mitosis whereas the multinucleate plasmodium exhibits acentric, closed spindle mitosis.     

The purification of cellulase and exo-laminaranase and their role in the formation ofPythium sp. “protoplasts”

A cellulase and a laminaranase have been purified from a Streptomyces lytic enzyme complex. Lipase and protease were separated from glucanases. A combination of the purified glucanases produced protoplasts fromPythium sp. PRL 2142. Lipase was shown to act as an adjuvant in this process.National Research Council of Canada Postdoctorate Fellow 1965–67.     

Chemical, Biological, and Structural Properties of Stable Proteus L Forms and Their Parent Bacteria

Proteus L forms were disrupted by osmotic shock, and the sedimentable material present in the homogenate was further fragmented in a Sorvall pressure cell. The pressure cell was also used for disrupting normal Proteus cells. The homogenates obtained were fractionated by differential centrifugation. Purified endotoxins were isolated from the major fractions by phenol extraction. Material extracted with phenol from the membrane fraction of the L forms was about as toxic and pyrogenic on a weight basis as the typical enterobacterial endotoxins isolated from cell walls of normal bacteria. The yield of extract from L forms was about one-third of that from an equal weight of normal bacteria. No differences in the gross chemical composition of the phenol extracts from the L forms and the normal cells could be ascertained. A close serological relationship existed between extracts obtained from two L forms and their respective parent bacteria, but no such relationship was found in the case of the third L form studied and its parent bacterium. Diaminopimelic acid was not detected in the membranes of the L forms, but these membranes contained most of the succinic dehydrogenase of the organisms. Only small amounts of this enzyme were present in the wall fraction of normal bacteria. The data obtained suggest that precursors of the Proteus endotoxins are formed either in the soluble protoplasm of normal cells and L forms or at sites on the membrane from which they are readily liberated into the protoplasm, whereas the final steps of the synthesis of these toxins take place at the cytoplasmic membrane. In normal cells, much endotoxin is transported to and concentrated in the walls.     

ELECTRON BOMBARDMENT OF BIOLOGICAL MATERIALS : II. THE RATE OF DEATH OF FUNGUS SPORES BOMBARDED IN VACUUM WITH CATHODE RAY BEAMS FROM 4 KV.–15 KV.

A study has been undertaken of the rate of inactivation of spores of the ascomycete fungus Aspergillus niger when bombarded in vacuum, with homogeneous beams of cathode rays of energies from 4 to 15 electron kv. and current densities of 1 x 10^–7 to 3 x 10^–6 amperes per square cm. These velocities and densities are in the range of those of showers of secondary electrons produced in biological materials irradiated with moderately soft x-rays, and so may be made to serve as quantitative indicators of the mechanics of x-ray action. Four qualitative effects are described.     

Cat gene frequencies in Richmond,California

The frequency of eight mutant genes was sampled and the results compared with studies on other cat populations for various locatities in the U.S.A.