Patterns of nucleotide substitutions inferred from the phylogenies of the class I major histocompatibility complex genes

Summary Patterns of nucleotide substitutions in human major histocompatibility complex (MHC) class I genes were estimated by using phylogenetic trees of DNA sequences. The pattern is defined as a set of 12 parameters, each of which represents the relative frequency of substitutions from a particular nucleotide to another. The pattern at the antigen recognition sites (ARS) in functional MHC genes was remarkably different from that at the remaining coding region (non-ARS). In particular, the proportion of transitions among all the nucleotide substitutions (P _s) was extremely low at the third codon positions of ARS. In the HLA-A genes, P _s at the third codon positions was only 6% in ARS, whereas it was 69% in non-ARS. In HLA-B, the corresponding values were 30% in ARS and 80% in non-ARS, respectively. On the other hand, P _s in a class I pseudogene (HLA-H) was 57%, which was in good agreement with P _s in other pseudogenes. Because pseudogenes are selectively neutral, the pattern in pseudogenes is regarded as the pattern of spontaneous substitution mutations. In general, the pattern in functional genes that are subject to selective forces deviates from the pattern in pseudogenes. At the third codon positions in coding regions, transitions scarcely cause amino acid replacements, whereas about half of transversions do cause replacements. Accordingly, P _s at the third codon positions decreases if amino acid replacements are accelerated by natural selection but increases if amino acids are conserved by functional constraint. Our observations imply that the ARS region is subject to natural selection favoring amino acid replacements, whereas the non-ARS region is subject to functional constraint. Offprint requests to: T. Gojobori     

R1-20, a novel monoclonal antibody reacting with a molecule distinct from integrin family, induces homotypic cell aggregation.

R1-20, a novel mAb reacting with a cell surface Ag on normal human lymphocytes and leukemic cell lines, was shown to induce homotypic cell aggregation in leukemic cell lines. This phenomenon was specific to mAb R1-20 because antibodies recognizing CD2, CD7, CD28, and HLA-ABC failed to exhibit homotypic cell aggregation. Induction of aggregation by mAb R1-20 occurred at 37 degrees C, but not at 4 degrees C and required cytoskeletal integrity. Sodium azide, a metabolic inhibitor, had no effect on the aggregation. Distinct from lymphocyte function-associated Ag-1/intercellular adhesion molecule-1 interaction in which divalent cations are essential elements, R1-20-mediated aggregation was not abolished with EDTA treatment. The R1-20 Ag was determined as a molecule of M(r) 100 to 110 kDa in immunoprecipitation and immunoblotting methods, under both reducing and nonreducing conditions. The molecular composition is quite different from that of any known integrin molecule. The R1-20 Ag was expressed on resting and activated T Lymphocytes as well as on normal B lymphocytes. Monocytes and granulocytes had no detectable R1-20 Ag. Among the leukemia-derived cell lines we used, mAb R1-20 reacted with 18 of 32 T cell lines, 2 of 20 B cell lines, 2 of 3 non-T-non-B cell lines, 2 of 7 myelomonocytic cell lines, and 2 of 3 nonlymphoid-nonmyeloid cell lines. All EBV-transformed B cell lines examined (10 cell lines) were R1-20+. The spectrum of reactivity among the cell lines tested was different from that of known antiadhesion antibodies tested. All these findings indicate that the Ag recognized by mAb R1-20 may represent a new type of cell adhesion molecule.     

Roles of Inorganic Nitrogen in Gametophytic Growth and in Initiation and Development of Sporophytic Shoots of Equisetum arvense

The formation of sporophytic shoots, which is induced by treatmentwith benzylaminopurine of gametophyte tissue of Equisetum arvense,can be divided into initiation and developmental phases. Thenitrogen in MS medium was suitable for two phases as well as gametophytic growth, buta reduction in the concentration of available nitrogen was neededfor the development of shoots. ions alone were effective for gametophytic growth and the initiationof sporophytic shoots, but both and ions was required for the developmental phase. (Received February 18, 1992; Accepted April 14, 1992)     

Parturition in a free-ranging Japanese monkey (Macaca fuscata)

Parturition behavior of a multiparous female and her interactions with group members throughout the birth process were recorded for a free-ranging Japanese monkey (Macaca fuscata). The female showed evidence of 18 contractions during the 35 min prior to delivery, with a mean duration and a mean intercontraction interval of 30 sec and 96 sec, respectively. These values were similar to those in individually caged Japanese monkeys. Some adult females remained in proximity to the female who was giving birth during the prepartum phase, and her 2-year-old daughter watched the delivery of the infant. Even during the prepartum phase the female moved in order to keep up with the group which traveled from the feeding site to a sleeping site in the forest.     

Lipase modification by various synthetic polymers for use in chloroform

Summary Lipase was modified with several hydrophilic and hydrophobic synthetic polymers. The modified lipase was solubilized into chloroform by. The catalytic esterification activity of modified lipase increased linearly with the increase of its solubility in chloroform.     

Influence of livestock grazing on vegetation in a saline area in Northeast Thailand

The influence of grazing by water buffalo (Bubalas bufalis) and cattle (Bos taurus) was estimated for vegetation inside and outside cages in a saline area at Khon Kaen, Northeast Thailand. The home range of water buffalo and cattle shifted in response to the period of rice cultivation: during the rice-growing season these animals grazed on roadsides and abandoned places such as the study area; after rice harvest they grazed mainly rice stubble on the paddy. The vegetation in the study area was divided into three types: 1) dominated by the annual grassesChloris barbata andIschaemum rugosum; vegetational cover and plant height in the cage increase due to the increase of these grasses; 2) thorny shrub patch ofMaytenus mekongensis; other species in this patch almost died a year after experimental elimination of this shrub; this salt-tolerant shrub not only protected the co-existing species from grazing, but also suppressed salt accumulation; 3) almost pure stand ofPanicum repens; livestock preferred this perennial grass over others. Electrical conductivity (EC) of surface soil did not increase under the vegetation protected from grazing. Litter and other organic matter in the soil suppressed the upward movement of brine. Grazing led to an increase of bare ground where NaCl accumulated, and modified the heterogeneity of vegetation, which was reflected in the degree of salt accumulation.     

Establishment and characterization of a bi-phenotypic leukemic cell line, NALM-19, from a patient with acute leukemia.

Based on the immunophenotypic and genotypic findings, this acute leukemia cell line, designated NALM-19, is unique in that a partial expression of both B-cell and myeloid cell features are present in this single clonal leukemic cell population. It is noteworthy that two "normal" EB virus-transformed B cell lines, B239 and B240, (paired with NALM-19) were established from the same leukemic blood.     

Evaluation of chemical pretreatment for enzymatic solubilization of rice straw

Summary Rice straw was treated with NaOH, peracetic acid (PA), and sodium chlorite (NaClO₂). Quantitative changes in the composition of the treated straw, crystallinity of the treated straw and extracted cellulose, and susceptibility of the treated straw to Trichoderma reesei cellulase were studied. The alkali treatment resulted in a remarkable decrease in hemicellulose as well as lignin. Consequently, the recovery of residual straw after NaOH treatment was lowest among the three chemical reagents evaluated. The treatment with PA or NaCIO₂ resulted in a slight loss in hemicellulose and cellulose in the straw. The three chemical treatments caused little or no breakdown of the crystalline structure of cellulose in the straw. The treated straw was solubilized with the culture filtrate of T. reesei. The degree of enzymatic solubilization relative to the amount of residual straw was 69% after treatment with 0.25 N NaOH, 42% after treatment with 20% PA, and 50% after treatments with NaClO₂ (twice). The degree of enzymatic solubilization relative to the amount of the untreated straw, however, was 30% after treatment with 0.25 N NaOH, 32% after treatment with 20% PA, and 37% after treatments with NaClO₂ (twice).     

Polyploid cytotypes and their habitat preferences inLycopodium clavatum

Morphological, cytological and ecological observations were made onLycopodium clavatum. Among 121 individuals from 26 populations studied 31 were of the diploid cytotype with 2n=68, 45 were of the triploid cytotype with 2n=102 and 45 were of the tetraploid cytotype with 2n=136. The populations were divided into three types: (1) the sole type—characterized by a single cytotype occupying an entire population, (2) the mixed type A—characterized by two or three cytotypes occupying together the same population, but each cytotype choosing different habitats, (3) the mixed type B—characterized by two or three cytotypes occupying together the same population and sharing the same habitat with each other. The mixed type B populations were found in the places of the early phase of secondary succession in a plant community. In the sole type and the mixed type A, the habitat preference for each cytotype was described as follows: the habitat for the diploid was in humid and shady places, that for the tetraploid was in open and sunny, unstable places, and that for the triploid was intermediate between the other two. Each cytotype can progress towards occupying their optimum habitat successively from the mixed type B population to the mixed type A population and finally reaching the sole type population.     

α-Guanidinoglutaric Acid in Cobalt-Induced Epileptogenic Cerebral Cortex of Cats

: Guanidino compounds in the cobalt-induced epileptogenic cerebral cortex of cats were fluorometrically analysed by a JASCO G-520 guanidino compounds analyser, and an unknown high peak was observed in the chromatogram that was identical to the peak of authentic α-guanidinoglutaric acid. In another experiment, the substance was extracted from the cobalt focus tissue, converted into dimethylpyrimidyl derivative-butylester, and analysed by a GC/MS technique. The mass spectrum of the substance was identical to the dimethylpyrimidyl derivative of α-guanidinoglutaric acid butylester (M⁺= 365).