Interactions in a mixed bacterial population growing on methane in continuous culture

The growth of a mixed methane-utilizing culture in a continuous flow fermenter has been studied under both methane and oxygen limitation. Small additions of methanol have been shown to inhibit the methane-utilizing moiety in the culture and it has been shown that the Hyphomicrobium sp. in the mixed culture removes any inhibitory methanol. The interaction between the methane-utilizing Pseudomonas sp., and the Hyphomicrobium sp. has been explained and a model of the continuous mixed culture under oxygen limitation has been formulated. Qualitative predictions of transient phenomena by the model have been verified experimentally.     

Molecular cloning of mei-41, a gene that influences both somatic and germline chromosome metabolism of Drosophila melanogaster

The mei-41 gene of Drosophila melanogaster plays an essential role in meiosis, in the maintenance of somatic chromosome stability, in postreplication repair and in DNA double-strand break repair. This gene has been cytogenetically localized to polytene chromosome bands 14C4-6 using available chromosomal aberrations. About 60 kb of DNA sequence has been isolated following a bidirectional chromosomal walk that extends over the cytogenetic interval 14C1-6. The breakpoints of chromosomal aberrations identified within that walk establish that the entire mei-41 gene has been cloned. Two independently derived mei-41 mutants have been shown to carry P insertions within a single 2.2 kb fragment of the walk. Since revertants of those mutants have lost the P element sequences, an essential region of the mei-41 gene is present in that fragment. A 10.5 kb genomic fragment that spans the P insertion sites has been found to restore methyl methanesulfonate resistance and female fertility of the mei-41 ^D3 mutants. The results demonstrate that all the sequences required for the proper expression of the mei-41 gene are present on this genomic fragment. This study provides the foundation for molecular analysis of a function that is essential for chromosome stability in both the germline and somatic cells.This Paper is dedicated to the memory of Professor James B. Boyd     

Generation and characterization of an ordered lambda clone array for the 460-kb region surrounding the murine Xist sequence

The Xist sequence has several characteristics that make it a potential candidate for the X-inactivation center. To investigate the role of Xist and adjacent sequences lying within the X-inactivation center candidate region, a 460-kb region surrounding the murine Xist sequence has been arrayed in lambda contigs with a combination of IRS-PCR-based hybridization and YAC fragmentation. The orientation of the Xist sequence in relation to the telomere and centromere of the X Chromosome (Chr) has been established with this contig and shown to be inverted compared to that in human.     

Absence of qualitative genes controlling interspecific pairing in rye B chromosomes

Summary The meiotic behaviour of hybrids between Secale cereale carrying B chromosomes and S. vavilovii has been studied in order to estimate the effects of B chromosomes on hybrid meiotic pairing. The possible effect of Bs on the meiotic pairing of the offspring from backcrosses with S. vavilovii has been studied also. The results obtained clearly indicate that no detectable differences existed in chromosome pairing of hybrids with or without B chromosomes. The hypothetical existence of epistatic genes on cereale genome masking the effect of Bs has been rejected after the results obtained in backcrosses. Therefore, lack of qualitative genes controlling interspecific pairing on rye B chromosomes has been concluded. A quantitative effect of B chromosomes was detected only when they were in alien cytoplasm.     

Nuclear division,nuclear distribution and cytokinesis in filamentous fungi

Nuclear division, nuclear distribution and cytokinesis are fundamental processes of all eukaryotic organisms, and filamentous fungi, specificallyAspergillus nidulans andNeurospora crassa, have provided sophisticated genetic systems for identification of the genes required for these processes. Mutational analyses have led to identification of novel proteins that have subsequently been found to be conserved components required for nuclear-specific functions. Formation of the mitotic spindle inA. nidulans has been shown to be dependent onγ-tubulin, a central element of all microtubule organizing centres, and two kinesin-related proteins. Analysis ofA. nidulans mitotic mutants has led to identification of two important cell-cycle regulators, NIMA and BIME. The NIMA kinase is required for entry into mitosis, and BIME has recently been identified as a subunit of an anaphase-promoting complex that targets cyclins for proteolysis. The microtubule-associated motor protein cytoplasmic dynein has been discovered in bothA. nidulans andN. crassa, and it has been proposed that it provides motive force for the distribution of nuclei within hyphae. Future studies of nucleus-specific processes in filamentous fungi are likely not only to identify additional novel structural and regulatory proteins, but also lead to an understanding of how the processes of nuclear division, nuclear distribution and septation are altered to meet the developmental needs of the organism.     

Biosynthesis of folic acid

Summary It has been attempted to isolate and characterize the folate precursors in the culture filtrates of two folate-requiring organisms, Streptococcus faecalis R and Lactobacillus casei. On the basis of paper chromatography, bioautography, ultra violet absorption spectra, chemical reactions, and differential microbiological responses it has been concluded that L. casei cultures contain a compound similar to pteroic acid which can be utilized by S. faecalis R. The S. faecalis R cultures on the other hand appear to accumulate a pteridine derivative active for Crithidia fasciculata It has been confirmed that this pteridine is not derived from the folic acid usually added to the growth medium.Abbreviations PGA Pterolyglutamic acid - PABA p-aminobenzoic acid     

The 5S and 5.8S Ribosomal RNA Sequences of Tetrahymena thermophila and T. pyriformis1

The nucleotide sequences of the 5S rRNAs of Tetrahymena thermophila and two strains of T. pyriformis have been determined to be identical. The 5.8S rRNA sequences have also been determined; these sequences correct several errors in an earlier report. The 5.8S rRNAs of the two species differ at a single position. The sequencing results indicate that the species are of recent common ancestry. Molecular evidence that has been interpreted in the past as suggestive of an ancient divergence has been reviewed and found to be consistent with a T. pyriformis complex radiation beginning approximately 30–40 million years ago.     

Genetic control of two electrophoretic variants of glucosephosphate isomerase in the mouse (Mus musculus)

The autosomal variation and the genetic control of GPI has been determined by a comparison of electrophoretic patterns of F₁ and backcross progeny of three inbred strains of mice. The locus controlling the production of GPI in the mouse has been designated Gpi-1. Two alleles at this locus have been described and designated Gpi-1 ^a and Gpi-1 ^b, which represent, respectively, the slow and fast electrophoretic forms. Twenty-seven inbred strains of mice have been classified for these two alleles. The absence of close linkage of Gpi-1 to seven other genetic loci has been determined. It has been demonstrated that the polymorphism of Gpi-1 is widely distributed in feral mice. GPI was expressed in vitro and in four types of malignant tumors.Supported by U.S. Public Health Service Grants GM-09966, from General Medical Sciences, and GY 4193.     

Reporter genes in transgenic mice

Althoughin vivo models utilizing endogenous reporter genes have been exploited for many years, the use of reporter transgenes to dissect biological issues in transgenic animals has been a relatively recent development. These transgenes are often, but not always, of prokaryotic origin and encode products not normally associated with eukaryotic cells and tissues. Some encode enzymes whose activities are detected in cell and tissue homogenates, whereas others encode products that can be detectedin situ at the single cell level. Reporter genes have been used to identify regulatory elements that are important for tissue-specific gene expression or for development; they have been used to producein vivo models of cancer; they have been employed for the study ofin vivo mutagenesis; and they have been used as a tool in lineage analysis and for marking cells in transplanation experiments. The most commonly usedin situ reporter gene islacZ, which encodes a bacterial -galactosidase, a sensitive histochemical marker. Although it has been used with striking success in cultured cells and in transgenic mouse embryos, its postnatalin vivo expression has been unreliable and disappointing. Nevertheless, the ability to express reporter genes in transgenic mice has been an invaluable resource, providing insights intoin vivo biological mechanisms. The development of newin vivo models, such as those in which expression of transgenes can be activated or repressed, should produce transgenic animal systems that extend our capacity to address heretofore unresolved biological questions.     

Studies on the effect of feeding some freshwater fishes with Scenedesmus obliquus (Turpin) Kuetzing

Summary The effect of feeding S. obliquus on two freshwater fishes Puntius ticto and Trichogaster fasciatus has been studied. It is observed that there is overall improvement in the conditions of the fishes and a marked increase in weight, volume and measurements has been observed as compared to control.     

Changes of DNA replication behavior associated with intragenic changes of thewhite region inDrosophila melanogaster

The pattern of late labeling spots in the X chromosome ofDrosophila melanogaster has been studied by H³-thymidine autoradiography. The pattern has been found to be identical with that of the “weak spots”, or places of “ectopic pairing”. The late replicating spot in region 3C has been found to lie close to the right of the locus ofwhite. A triplication and a deficiency involving the right half of thewhite region and exhibiting changes in their interaction with the mutantzeste have been found to be associated with changes in the frequency and intensity of labeling of the late material in 3 C. Twoz ⁺ revertants derived from the triplication by X irradiation again show concomitant changes in labeling behavior at 3C.     

The first isolation of two types of trifluoroleucine resistant mutants of Saccharomyces servazzii

Saccharomyces servazzii plays a crucial role in the making of Japanese radish pickles. To make more flavorsome pickles, we sought to generate trifluoroleucine-resistant mutants of S. servazzii. The three resulting mutants could be classified into two types: one that produces more isoamyl alcohol than the parental strain, and one that produces less. The first type has been well documented in Saccharomyces cerevisiae but the latter appears to be novel and has been characterized as such.     

Cultivation of Macrocystis integrifolia (Laminariales,Phaeophyta) in southeastern Alaskan waters

The artificial culture of Macrocystis integrifolia in southeastern Alaskan waters has been initiated as a first step in a project to augment the existing herring roe-on-kelp fishery in the state. The growing of Macrocystis in Prince William Sound has the potential of considerably enhancing this fishery by eliminating the costly importation of this kelp from southeast Alaska. In an ongoing feasibility study, Macrocystis has been cultured under laboratory conditions through the embryonic sporophyte stage and outplanted in waters near Sitka, Alaska (57° N). Growth of the outplanted kelps has been monitored as a function of the time and depth of the outplanting. Preliminary results suggest that light is limiting for growth in winter and that the optimal depth for outplanting will vary with the season.     

Development of a bifunctional crosslinking agent with potential for the preparation of immunotoxins

A new protein crosslinking agent, 2,3-dibromopropionyl-N-hydroxysuccinimide ester, has been synthesized and characterized. The potential use of this compound as a temperature-controllable heterobifunctional crosslinking agent has been investigated using model systems and its reactivity compared with that of chlorambucil-N-hydroxysuccinimide ester. The coupling of¹⁴C-labeled phenylethylamine to lysozyme has been used to illustrate the feasibility of the use of this crosslinking agent for the synthesis of immunotoxins.     

Genetics and physiology of the rel system of Bacillus subtilis

Summary Stringent factor (ATP:GTP-3 pyrophosphotransferase) has been purified from wild type Bacillus subtilis and it has been shown that guanosine tetra- and pentaphosphate (ppGpp and pppGpp) are synthesized in vitro in the presence of ribosomes, unacylated tRNA and its specific codon, as has been demonstrated in Escherichia coli. relA, the genetic determinant for the stringent factor, has been mapped on the B. subtilis chromosome by transduction and is found between aroD and leu.The relC locus, defined by mutations which were originally selected by resistance to thiostrepton, has been mapped adjacent to spoOH in the order cysA, spoOH, relC, rif.Stringent factor and ribosomes are functional for the in vitro synthesis of (p)ppGpp in early stages of sporulation (up to at least 4 h). This contradicts the findings of other laboratories.     

Mapping of the genes for tubular basement membrane antigen and a submaxillary gland protease in the rat

The gene for tubular basement membrane (Tbm) antigen in the rat has been mapped relative to other markers in the first linkage group, and a polymorphic locus for a submaxillary gland protease, Tamase-1, has been identified. The hair-loss mutation fuzzy has also been mapped and occupies a position which is similar to that of the frizzy gene in the mouse. There are now at least five, and possibly six, genetic loci distributed over more than 30 centimorgans in the first linkage group of the rat which map in positions of approximate homology on the seventh chromosome of the mouse.     

Biostratigraphic distribution of ammonites and calpionellids in the Tithonian of the internal Prerif (Msila area,Morocco)

Because of the relatively thick succession exposed in the Msila area, new bed-by-bed sampling has been carried out in order to investigate late Tithonian ammonites and the correlation between biostratigraphic scales based on ammonites and calpionellids. The outcrop begins with Lower Tithonian beds assigned to the Fallauxi Zone. Ammonites have been found that allow recognition in the same section both Fallauxi and Ponti Zones. The most significant species are: Simoceras admirandum Zittel, which is the marker of the upper subzone of the Fallauxi Zone, i.e. the Admirandum/Biruncinatum Subzone, and several species of the genus Lemencia and Burckhardticeras peroni (Roman), that characterize the Ponti Zone. Ammonites that belong to the Microcanthum Zone appear in bed 18. This zone is usually subdivided into two subzones, of which only the lower one, the Simplisphinctes Subzone, has been recognized. The upper Transitorius Subzone has been recognized on the basis of the occurrence of Moravisphinctes fischeri (Kilian). The last ammonite unit, the Durangites Zone, is easily recognizable because of the occurrence of species of the genera Durangites and Protacanthodiscus. The section ends with the beginning of the Berriasian, which is characterized by a well-exposed, ammonite-rich bed of the Jacobi Zone. Correlation of the ammonite zones with calpionellid zones has been investigated. The Chitinoidella Zone is characterized by calpionellids with microgranular tests that appear in the ammonite Admirandum/Biruncinatum Subzone with species of the Dobeni Subzone, which extends up to the Ponti Zone. Representatives of the Boneti Sub-Zone appear in bed 16, which probably correlates with the base of the ammonite Upper Tithonian Microcanthum Zone. Two horizons have been distinguished within the calpionellid Subzone A3.     

The cytology of the genus Briza L. (Gramineae)

Meiosis has been studied in five European and four South American species of Briza. The various species have different chiasma frequencies and different patterns of chiasma localisation. Population studies show that there are significant differences in mean plant chiasma frequency between populations of B. maxima whereas B. media and B. spicata do not show interpopulation differences. B. media is shown to have diploid and autotetraploid races and the distribution of these chromosome races in Europe has been plotted. The South American species studied are all bivalent forming tetraploids and would therefore appear to have an allopolyploid origin. Interchange heterozygosity has been found in B. media and B. elatior, different populations of B. media have been shown to be heterozygous for different interchanges. These topics are discussed in relation to the regulation of recombination.     

Genetic studies on theH-3 region of mice and implications for polymorphism of histocompatibility loci

Evidence has been obtained for recombination betweenH-3 and the closely linkedIr-2 locus, which controls the antibody response toEa-1 antigens. The data suggest thatIr-2 maps close toH-3, betweenH-3 andH-13. The YBR strain has been found to possess anH-3 allele not previously reported. A comparison has been made between the degree of polymorphism of histocompatibility loci and that which involves electrophoretically detectable protein variants.