Adiabatic compressibility of myosin subfragment-1 and heavy meromyosin with or without nucleotide.

The partial specific adiabatic compressibilities of myosin subfragment-1 (S1) and heavy meromyosin (HMM) of skeletal muscle in solution were determined by measuring the density and the sound velocity of the solution. The partial specific volumes of S1 and HMM were 0.713 and 0.711 cm3/g, respectively. The partial specific adiabatic compressibilities of S1 and HMM were 4.2 x 10(-12) and 2.9 x 10(-12) cm2/dyn, respectively. These values are in the same range as the most of globular proteins so far studied. The result indicates that the flexibility of S1 region almost equals to that of HMM. After binding to ADP.orthovanadate, S1 and HMM became softer than their complexes with ADP. The bulk moduli of S1 and HMM were of the order of (4-6) x 10(10) dyn/cm2, which are very comparable with the bulk modulus of muscle fiber.     

Polymerase chain reaction analysis of mitochondrial DNA polymorphism in N'Dama and Zebu cattle

A study of polymorphisms of mitochondrial DNA (mtDNA) of West African N'Dama (Bos taurus) and East African Zebu (B. indicus) cattle was carried out to obtain information on maternal phylogenetic relationships between these breeds. A relatively large sample size was made possible by using polymerase chain reaction (PCR) amplification of DNA prepared from small blood samples to generate fragments of two known polymorphic mtDNA regions, one within the gene encoding subunit 5 of NADH dehydrogenase and one encompassing the entire D-loop. This approach allowed us to achieve a higher resolution restriction analysis on mtDNA from more animals than would have been possible by conventional methods. PCR-amplified mtDNA of 58 animals from five populations was examined at 26 restriction sites by 16 enzymes. In this way 154 nucleotides of mtDNA were scanned for polymorphism. Six polymorphic sites were located by this means, five of which were within the D-loop and one of which was within the NADH dehydrogenase 5 gene. None of the polymorphisms observed could be con sidered typical of breed or type.     

Germination ofRubus palmatus var.coptophyllus andR. microphyllus seeds buried in soil for 7.5 years

Seeds of twoRubus species,R. palmatus var.coptophyllus andR. microphyllus, buried for 7.5 years in soil were subjected to germination tests to investigate their germinability and germination traits. Most of the retrieved seeds were viable, and germinated at the alternating temperatures of 20/30°C in both light and dark. The twoRubus species showed similar responses of germination to temperature and light, although the final percentages of germination were slightly higher inR. palmatus var.coptophyllus. These characteristics of seed dormancy and germination would be involved in the species' utilization of ephemeral habitats created by unpredictable and infrequent disturbances.     

Variations in and Inheritance of NS-Glycoprotein in Self-Incompatible Brassica campestris L.

The stigma of Brassica species contain NS-glycoproteins thatexhibit a high degree of structural homology to the S-glycoproteinsof self-incompatibility. Inheritance of and variations in theNS-glycoprotein were studied with reference to self-incompatibility.The detection of NS-glycoproteins was performed by cross-reactionwith an antiserum raised against a purified NS-glycoprotein.In B. campestris, four isoforms of the NS-glycoprotein weredifferentiated by their pI values, but their molecular weightswere identical to one another. The genes for these isoformsof NS-glycoprotein were controlled by alleles at a single locus,tentatively named the NS allele, which was independent of Salleles at both the protein and the DNA level. Segregation ofF₂ plants with respect to the self-incompatibility behaviorof pollen tubes can be explained by the S allele model, butit appears not to be affected by the NS alleles. NS-glycoproteinswere found in all 21 species of Brassica and its allies examinedto date. The pI values of these glycoproteins varied among differentspecies. In addition to the isoforms of the NS alleles, maturestigmas contained other groups of proteins that reacted weaklywith the antiserum against the NS-glycoprotein. (Received July 30, 1991; Accepted February 21, 1992)     

Qualitative and quantitative difference in mutation induction between carbon- and neon-ion beams in normal human cells.

We investigated the difference in cell-killing effect and mutation induction between carbon- and neon-ion beams in normal human cells. Carbon- and neon-ion beams were accelerated by the Riken Ring Cyclotron (RRC) at the Institute of Physical and Chemical Research in Japan. Cell-killing effect was measured as the reproductive cell death using the colony formation assay. Mutation induction at the HPRT locus was detected to measure 6-thioguanine-resistant clones. The mutation spectrum of the deletion pattern of exons of induced mutants was analyzed using the multiplex polymerase chain reaction (PCR). Cell-killing effect was almost the same between carbon- and neon-ion beams with similar linear energy transfer (LET) values, while there observed a large difference in mutation frequency. Furthermore, in the case of neon-ion beams 60% of mutants showed total deletions and 35-40% showed partial deletions, while 95-100% of carbon-ion induced mutants showed total deletions. The results suggest that different ion species may cause qualitative and quantitative difference in mutation induction even if the LET values are similar.     

Role of water receptor in the frog

To elucidate the role of the water receptor in the frog (Rana catesbeiana), reflex activities elicited by its excitation were studied. Application of tap water to the oral mucosa depressed the rhythmical movement of gorge (buccal) respiration, accompanied by an elevation of the inner pressure of the oral cavity (buccal pressure). Tonic reflex discharges were elicited in the nerves innervating the submental and submaxillary muscles, which close the nostrils, the pterygoid and the profound portion of the major masseter muscles, which produce a strong bite, and the geniohyoid and hyoglossus muscles, which elevate buccal pressure. These muscles, except for the pterygoid, also participate in the rhythmical movement of gorge respiration as expiratory muscles. Rhythmical movements in the minor masseter and sternohyoid muscles, which act as inspiratory muscles in gorge respiration, were depressed by the water stimulation of the oral mucosa. These findings indicate that the water receptor plays a role in the interruption of gorge respiratory movements, accompanied by an elevation of buccal pressure.     

A specific microbial sensor for formic acid

Summary A microbial sensor consisting of immobilized Clostridium butyricum, two gas permeable Teflon membranes and fuel cell type electrode was suitable for the determination of formic acid. When the sensor was inserted into the sample solution containing formic acid, the current increases to a steady state with a response time of 20 min. The relationship between the steady state current and the formic acid concentration is linear up to 1 000 mg l^–1. The currents are reproducible with an average relative error of 5%. Selectivity of the sensor is satisfactory. Results obtained with this sensor and by gas chromatography were in good agreement (regression coefficient; 0.98) when the cultivation medium of Aeromonas formicans was employed. Immobilized Clostridium butyricum is stable for more than 20 days.     

The crystallization of mitochondrial cytochrome oxidase-cytochrome c complex

Conditions are described under which crystals are formed with equimolar complex of mitochondrial cytochrome oxidase and cytochrome c. Characteristic absorption bands of the solubilized crystals could be attributed to the cytochrome oxidase-cytochrome c complex with heme a:c ratio of 2:1. Activity of crystals shows more close heme-heme interaction between two cytochromes than that of the mixture.