Molecular basis of organic acidemia--propionic acidemia

Propionic acidemia is an inborn error of organic acid metabolism caused by deficiency of propionyl-CoA carboxylase (PCC: E. C. 6. 4. 1. 3.). We have detected three types of mutation in the same exon of the coding sequence of beta-subunit of PCC (beta PCC) from two ethnic background (Caucasians and Japanese): an insertion/deletion which replaces 14 nucleotides with 12 unrelated nucleotides results in the elimination of an Msp I site; a 3-bp inframe deletion results in loss of one of two consecutive isoleucine codons immediately preceding the same Msp I site; the C----T transition results a in loss of the same Msp I site. The insertion/deletion and the C----T transition show high allele frequency in Caucasians (0.32) and in Japanese (0.3), respectively. These results reveal the possibility of the independent origin of the mutation in the two ethnic backgrounds and suggest a key role of this exon in the structure and catalytic function of the beta-subunit of PCC.     

A Computational Model of Afterimage Rotation in the Peripheral Drift Illusion Based on Retinal ON/OFF Responses

Human observers perceive illusory rotations after the disappearance of circularly repeating patches containing dark-to-light luminance. This afterimage rotation is a very powerful phenomenon, but little is known about the mechanisms underlying it. Here, we use a computational model to show that the afterimage rotation can be explained by a combination of fast light adaptation and the physiological architecture of the early visual system, consisting of ON- and OFF-type visual pathways. In this retinal ON/OFF model, the afterimage rotation appeared as a rotation of focus lines of retinal ON/OFF responses. Focus lines rotated clockwise on a light background, but counterclockwise on a dark background. These findings were consistent with the results of psychophysical experiments, which were also performed by us. Additionally, the velocity of the afterimage rotation was comparable with that observed in our psychophysical experiments. These results suggest that the early visual system (including the retina) is responsible for the generation of the afterimage rotation, and that this illusory rotation may be systematically misinterpreted by our high-level visual system.     

A rapid bioassay method of gibberellin activity using pale malt

The availability of brewery pale malt as a substrate for gibberellinbioassay was investigated. GA₃ at the concentration of 0.001to 1 µg/ml caused an increase in a-amylase activity inpale malt under aerobic incubation, while no increase was observedunder anaerobic conditions. Pale malt heated at 130°C for2 hr showed no increase in a-amylase activity in the presenceof GA₃. Although the mechanism for the enhancement of a-amylaseactivity in pale malt by GA₃ is not clear, it is evident thatthis phenomena can be used in bioassay of gibberellins. Experimentalconditions for the bioassay using pale malt are described. Withthis method, the enhancement of a-amylase activity by differentgibberellins was: GA₃>GA₄>GA₂₀ (inactive). (Received October 16, 1975; )     

Plectranthias maekawa,a new species of perchlet from the Tokara Islands,Kagoshima, Japan,with a review of Japanese records of P. wheeleri (Serranidae: Anthiadinae)

Ichthyological Research - A new species of perchlet, Plectranthias maekawa, is described on the basis of three specimens (58.2–65.1 mm standard length: SL) from the Tokara Islands,...     

Spring and summer microhabitat use by Schlegel’s Japanese gecko,Gekko japonicus (Reptilia: Squamata: Gekkonidae), in urban areas

Differential microhabitat use may be beneficial to achieving fitness in seasonally variable environmental conditions. To explore whether the microhabitat use of the nocturnal Schlegel’s Japanese gecko, Gekko japonicus, varies seasonally and depends on juvenile, male, and female reproductive groups, we investigated five categorical and five quantitative measure variables of microhabitat use in a wild population both in spring and summer. Most geckos were found on white, vertical planes of concrete and plastered brick walls. None of the categorical variables (type of location, substrate, substrate color, light source, and refuge) significantly differed according to season or group, while substrate temperature and irradiance at the location where geckos were observed and the distance from the nearest potential refuge were significantly greater in summer than in spring. The quantitative measure variables did not differ among the reproductive groups. These results suggest that G. japonicus seasonally adjusts its microhabitat use mainly in terms of quantitative measure variables rather than categorical variables.     

Production and characterization of recombinant P1 adhesin essential for adhesion,gliding, and antigenic variation in the human pathogenic bacterium,Mycoplasma pneumoniae

Mycoplasma pneumoniae forms an attachment organelle at one cell pole, binds to the host cell surface, and glides via a unique mechanism. A 170-kDa protein, P1 adhesin, present on the organelle surface plays a critical role in the binding and gliding process. In this study, we obtained a recombinant P1 adhesin comprising 1476 amino acid residues, excluding the C-terminal domain of 109 amino acids that carried the transmembrane segment, that were fused to additional 17 amino acid residues carrying a hexa-histidine (6?×?His) tag using an Escherichia coli expression system. The recombinant protein showed solubility, and chirality in circular dichroism (CD). The results of analytical gel filtration, ultracentrifugation, negative-staining electron microscopy, and small-angle X-ray scattering (SAXS) showed that the recombinant protein exists in a monomeric form with a uniformly folded structure. SAXS analysis suggested the presence of a compact and ellipsoidal structure rather than random or molten globule-like conformation. Structure model based on SAXS results fitted well with the corresponding structure obtained with cryo-electron tomography from a closely related species, M. genitalium. This recombinant protein may be useful for structural and functional studies as well as for the preparation of antibodies for medical applications.