Genetic Control of the Rate of α-Amylase Synthesis in Bacillus subtilis

The level of extracellular alpha-amylase (EC 3.2.1.1) of Bacillus subtilis Marburg was increased about fivefold by introducing the amyR marker from B. natto 1212 through transformation. amyR2 of B. natto 1212 has been assumed to determine a high level of alpha-amylase of the organism. The gene acts specifically on alpha-amylase synthesis but not on the production of other extracellular enzymes. alpha-Amylase of an amyR2-carrying strain was found to be quite similar to that of an isogenic amyR1-carrying strain in the thermostability and electrophoretic behavior of whichever amylase the strain produces. Marburg-type alpha-amylase (amyEm) or B. natto-alpha-amylase (amyEn). Anti-amylase serum titration indicates that a high level of the enzyme activity in the amyR2-carrying strain is caused by the existence of more enzyme rather than the presence of an enzyme having higher efficiency. This is supported further by the fact that amyR controls the synthesis of the amyE gene product in mutant M9, which synthesizes a temperature-sensitive-alpha-amylase, and in mutant M07, which secretes cross-reacting material. The results indicate that amyR regulates the rate of alpha-amylase synthesis.     

Chlorophyll a forms in mesophyll and bundle sheath chloroplasts of Zea mays leaves grown at low light intensity

Mesophyll and bundle sheath chloroplasts were prepared fromleaves of Zea mays grown at light intensities of 1.1 and 240µW/cm², respectively. The mesophyll chloroplasts thatdeveloped at the low intensity and bundle sheath chloroplatsthat developed at both low and high intensities showed higherratios of chlorophyll a/b and P700/chlorophylls compared withthe normal ratios found for the mesophyll chloroplasts thathad developed at the high intensity. Derivative absorption spectrophotometryat 77?K revealed that the low intensity mesophyll chloroplastscontained more of chlorophyll a forms with longer wavelengthred bands than high intensity mesophyll chloroplasts. More ofthe longer wavelength forms of chlorophyll a were also presentin the bundle sheath chloroplasts that had developed at lowand high intensities. All these four types of chloroplasts showedtwo peaks of fluorescence, one at 687 hra and the other at 733or 738 nm. In addition to these peaks, the high intensity mesophyllchloroplasts showed a shoulder at 697 nm, and the two typesof bundle sheath chloroplasts showed a shoulder at 680 nm. (Received June 17, 1974; )     

A bacteriolytic enzyme from Chaetomium globosum,a marine-isolate

Summary When a marine-isolate, Chaetomium globosum was cultivated in a medium with an increased MgCl₂ content, a bacteriolytic enzyme was extracellularly produced. The enzyme was purified approximately 130-fold. It lyzed Staphylococcus aureus, Micrococcus lysodeikticus and several other Gram-positive bacteria. Optimal pH and temperature for the lysis were 8.0 and 37°C, respectively. The enzyme was heat-labile with maximum stability at neutral pH. Enzymatic activity was greatly stimulated by NaCl and CaCl₂ with maximum activity obtained in the presence of 0.1 M NaCl and 0.003 M to 0.005 M CaCl₂. The activity was stimulated by SH-compounds and was inhibited by SH-reactants.The enzyme is an N-acetylhexosaminidase.     

Geographical Distribution of Twelve Transferrin Alleles in Black Rats of Asia and Oceania

About 450 black rats (Rattus rattus) were collected from 25 localities in Asia and Oceania. Their serum transferrins were analyzed by a newly developed thin layer acrylamide gel electrophoresis accompanied with acrinol pretreatment, exhibiting 12 transferrin bands. Generally, Asian type rats (2N=42) had fast-moving transferrins (R-series), Ceylon type (2N=40) moderately moving ones and Oceanian type (2N=38) slowly moving ones (C-series). Exceptionally, in northern India and Pakistan all Asian-type rats had C-series Tf. The possibility that divergence of R-series Tf and C-series Tf had preceded the karyotypic differentiation from 42 to 38 is proposed. In combination with the previous molecular data, the time of the divergence is roughly estimated between the order of a million years and ten thousand years.     

An {alpha}-Glucan from Suspension-Cultured Rice Cells

An -glucan was isolated from 11-day-old suspension-culturedrice cells by extraction with hot Na-phosphate buffer (pH 6.8).The -glucan had []_D=+234? (C = 0.14, in water) and its averagemolecular weight was estimated to be about 1.4 ? 10⁴, basedon elution characteristics on acalibrated Sepharose CL-6B column.Upon partial acid hydrolysis, the -glucan gave mainly malto-oligosaccharides.The maximum absorption of the iodine complex of the -glucanin the presence of Na₂SO₄ was at 470 nm. The results of hydrolysisby , ß- and iso-amylases and methylation analysisindicated that the isolated -glucan is a highly branched polysaccharidewith an average chain length of 9. The exterior and interiorchain lengths of the -glucan were calculated to be 5 and 3,respectively. (Received July 23, 1986; Accepted February 7, 1987)     

Sexual preference of meiotic recombination within the H-2 complex

The recombination frequency between the H-2K and H-2D marker loci in male mice was measured using heterozygotes that carry the H-2 ^wm7 haplotype derived from the Japanese wild mouse and common H-2 haplotypes derived from inbred mice. Previous mating experiments in which backcross progeny of heterozygous females were screened demonstrated that the H-2 ^2m7 displays marked enhancement of recombination within the H-2 complex. In contrast to recombination in female mice, no enhancement of recombination was observed during male meiosis in the present study. Thus, it appeared that enhancement of recombination is specific to female mice. A genealogical study of recombination indicated that the postmeiotic stage is not involved in the generation of sexual preference of enhancement of recombination, suggesting that the preference is meiotic-drive and that a female-specific mechanism is involved in meiotic recombination mediated by the H-2 ^wm7 haplotype.     

Asymmetric replication of an oriC plasmid in Escherichia coli

Summary Plasmid pTSO118 containing the Escherichia coli origin of replication, oriC, initiated replication simultaneously with the chromosome when temperature-sensitive host cells were synchronized by temperature shifts. Replicating intermediates of the plasmid as well as of the chromosome were isolated from the outer membrane fraction of the cell. Plasmid DNA with eye structures was enriched when cytosine-1--arabinofuranoside was introduced into the culture during replication. Electron microscopy of the replicating molecules, after digestion with restriction endonucleases, showed that the replication fork proceeds exclusively counter-clockwise towards the unc operon. We conclude that the replication of the oriC plasmid is unidirectional or, if bidirectional, is highly asymmetric.