Clavispora,a new yeast genus of the Saccharomycetales

In Candida lusitaniae van Uden et do Carmo-Sousa (1959), strains of opposite sex have been found. Cells of the opposite mating types conjugate and form asci with one to four clavate spores. These are easily liberated from the ascus. The type strain of Candida obtusa (Dietrichson) van Uden et do Carmo-Sousa ex van Uden et Buckley (1970) also produces ascospores after mating with one of the strains of Candida lusitaniae. As clavate ascospores are unknow in yeasts, a new genus, Clavispora, is proposed with Clavispora lusitaniae spec. nov. as type species.     

Molecular cloning and selection of genes regulated in Aspergillus development

Over 350 clones homologous to poly(A)+ RNAs that are significantly more prevalent in conidiating cultures of Aspergillus nidulans than in somatic cells have been selected from a recombinant DNA library formed between nuclear DNA and lambda Charon 4A. The procedure used for this selection involved in situ hybridization to a cDNA probe which had been selectively depleted of sequences represented in somatic cells by complement hybridization. Five of these clones have been characterized further. All but one encoded poly(A)+ RNAs that were at least ten times more prevalent in conidiating cultures than in somatic cells. One clone hybridized to a single, developmentally regulated RNA. The three others were complementary to several RNAs having different molecular weights, each of which was more prevalent in condiating cultures than in vegetative cells. These results and quantitative aspects of the selection procedure suggest that developmentally controlled poly(A)+ RNA coding regions may not be distributed randomly in the Aspergillus genome.     

Alpha-locus hexosaminidase genetic compound with juvenile gangliosidosis phenotype: clinical,genetic, and biochemical studies.

A 3-year-old boy developed progressive neurological deterioration in his third year, characterized by dementia, ataxia, myoclonic jerks, and bilateral macular cherry-red spots. Hexosaminidase A (HEX A) was partially decreased in the patient''s serum, leukocytes, and cultured skin fibroblasts. Hexosaminidase was studied in serum and leukocytes from family members. Four members of the paternal branch appeared to be carriers of classical infantile Tay-Sachs allele, HEX alpha 2, probably receiving the gene from one great-grandparent of Ashkenazi origin. In the maternal branch, no one was a carrier of classical infantile Tay-Sachs disease, but five individuals were carriers of a milder alpha-locus defect. The patient, therefore, was a genetic compound of two different alpha-locus hexosaminidase mutations. At least 21 families with late-infantile or juvenile GM2 gangliosidosis have been reported, 18 of them with alpha-locus mutations, and three with beta-locus mutations. Genetic compounds of hexosaminidase have been reported in at least seven families, five with alpha-locus mutations and two with beta-locus mutations. The compound had the phenotype of infantile Tay-Sachs disease in one family, infantile Sandhoff disease in another, and the normal phenotype in the rest.     

Distribution of Nothanguina phyllobia and Its Potential as a Biological Control Agent for Silver-leaf Nightshade

The nematode Nothanguina phyllobia Thorne was found within large foliar galls on the perennial weed Solanum elaeagnifolium Cav. in west Texas. A two-year survey of a 6400 sq-km area in west Texas showed extensive distribution of the nematode. No hosts other than S. elaeagnifolium were observed. Densities of juvenile nematodes in the soil were high. N. phyllobia spread rapidly after small numbers of infective juveniles were applied in a foliar spray to an S. elaeagnifolium population. The host plant declined in vigor and frequently died. Artificial inoculation of an S. elaeagnifolium population with large numbers of the nematodes by broadcasting infected plant tissue resulted in high infection incidence.     

Adaptation to chronic hypobaric hypoxia and sexual hormones

The role of the gonads and their hormones on body weight was studied in rats of both sexes submitted to chronic hypoxia and their controls at sea level atmospheric pressure. Intact rats were exposed to either 4 700 or 6 000 m simulated altitude in a hypopressure chamber. Castrated rats and castrated rats daily injected with either 0.5 mg of testosterone or 20 microgram of estradiol or the vehicle, were exposed to the higher altitude. The rat weight was recorded for a period of at least eight weeks. All groups of hypoxic male animals increased their weight significantly less than the controls at sea level. Also in castrated females and in castrated injected with testosterone or the vehicle the same pattern of weight curves was observed. On the contrary, groups of intact females and castrated females injected with estradiol did not show significant differences between hypoxic and control animals. Only in a group of smaller intact females (50-80 g) the body weight increase was significantly diminished by exposure to either 4 700 or 6 000 m simulated altitude.     

Invasion and metastasis.

Malignant tumours cause sickness and death largely because they invade and metastasize. Such spread is made possible by many cellular properties, including the ability of neoplastic cells to move and to release degradative enzymes. These properties enable tumour cells to break free of the primary tumour, penetrate blood or lymphatic vessels and, after being transported to distant sites, pass out of the vessels to establish new tumours. Not all cells in a tumour, however, are able to metastasize, so the process tends to select for greater malignancy in the secondary tumour. The heterogeneity of tumours probably accounts for the difficulty of providing effective treatment, in that the various subpopulations of cells arising from each tumour vary in their responses to chemotherapeutic agents. We do not yet understand the process sufficiently to treat cancer patients by interfering selectively with the metastatic mechanisms.     

Determination of the chromosomal size of three different strains of Enterococcus faecalis and one strain of Enterococcus faecium.

Pulsed-field gel electrophoresis was used to determine the chromosomal size of three different strains of Enterococcus faecalis and one strain of Enterococcus faecium. The size determinations of OG1X, a strain of E. faecalis widely used in many laboratories for genetic studies, using Sma I, Not I, and Sfi I alone or in combination, ranged from 2,750 to 2,761 kb. Using the same enzymes as with OG1X, the size of HH-67, a plasmid-free clinical isolate of E. faecalis, was determined to be 2,170-2,288 kb and the size of JH2-2, an E. faecalis recipient strain, ranged from 2,008 to 2,135 kb. The size range generated for GE-1, a plasmid-free E. faecium strain, with the use of Sma I, Not I, and Apa I was 2,045-2,155 kb. Although OG1X differed in size from the other three enterococci, each individual enterococcal strain generated reproducible results in different experiments. However, for both E. faecalis OG1X and E. faecium GE-1, one of the enzymes used generated a considerably smaller molecular size than that generated by the other two enzymes. The discrepancy was due to visually undiscernible comigrating fragments, and serves to point out a potential source of error if fewer than two enzymes are used to size a genome. The size discrepancies were resolved by digesting individual fragments with a second enzyme. The molecular sizes of these enterococcal strains are larger than that recently reported for Campylobacter, smaller than that of Escherichia coli and Pseudomonas aeruginosa, and similar (OG1X) or smaller (JH2-2, HH67, and GE-1) than the 2,819-kb reported for Streptococcus mutans.     

Regulation of gene expression in preimplantation mouse embryos: effects of the zygotic clock and the first mitosis on promoter and enhancer activities

Previous studies have reported that promoters requiring enhancers for full activity in mammalian somatic cells also require enhancers when injected into mouse two-cell embryos, whereas the same promoters can be expressed just as efficiently in the absence of an enhancer when injected into arrested one-cell embryos. Experiments were designed to determine whether this phenomenon reflected normal developmental changes at the beginning of mammalian development, or simply differences in the physiological states of these cells under the experimental conditions employed. The activity of three different promoters that function in a wide variety of mammalian cells was measured both in embryos whose morphological development was arrested and in embryos that continued development in vitro. Expression of the injected gene was related to the onset of zygotic gene expression ("zygotic clock"), the phase of the cell proliferation cycle, the use of aphidicolin to arrest cell proliferation, and formation of two-cell embryos in vitro and in vivo. The results demonstrated that promoter activity was tightly linked to zygotic gene expression, while the need for enhancers to stimulate promoter activity depended only on formation of a two-cell embryo. These results further support the hypothesis that the first mitosis induces a general repression of promoters prior to initiation of zygotic gene expression that is relieved specifically by enhancers.