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151.
Relationship of Phenylalanine Ammonia-lyase Activity to o-Hydroxycinnamic Acid Content in Melilotus alba
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Phenylalanine ammonia-lyase activity was investigated in preparations representing various parts of sweetclover (Melilotus alba Desr.) plants of CuCu and cucu genotypes. In contrast to other plant parts, very young leaves and stems of CuCu plants displayed high phenylalanine ammonia-lyase activity. Initial leaf samples from CuCu plants were approximately 3 times as high in enzyme activity as leaves from cucu plants, but stems were only slightly higher in activity. Defoliation of the plants resulted in decreased enzyme activity, increased o-hydroxycinnamic acid content, and essentially no difference in enzyme activity between the genotypes. It appears that phenylalanine ammonia-lyase activity in leaves is not primarily controlled by the Cu/cu alleles and that the reaction catalyzed by this enzyme is not the limiting step in o-hydroxycinnamic acid synthesis. 相似文献
152.
153.
Localization of thyroglobulin antigenicity in rat thyroid sections using antibodies labled with peroxidase or (125)I-radioiodine
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In the hope of localizing thyroglobulin within focullar cells of the thyroid gland, antibodies raised against rat thyroglobulin were labeled with the enzyme horseradish peroxidase or with (125)I-radioiodine. Sections of rat thyroids fixed in glutaraldehyde and embedded in glycol methacrylate or Araldite were placed in contact with the labeled antibodies. The sites of antibody binding were detected by diaminobenzidine staining in the case of peroxidase labeling, and radioautography in the case of 125(I) labeling. Peroxidase labeling revealed that the antibodies were bound by the luminal colloid of the thyroid follicles and, within focullar cells, by colloid droplets, condensing vacuoles, and apical vesicles. (125)I labeling confirmed these findings, and revealed some binding of antibodies within Golgi saccules and rough endoplasmic reticulum. This method provides a visually less distinct distribution than peroxidase labeling, but it allowed ready quantitation of the reactions by counts of silver grains in the radioautographs. The counts revealed that the concentration of label was similar in the luminal colloid of different follicles, but that it varied within the compartments of follicular cells. A moderate concentration was detected in rough endoplasmic reticulum and Golgi saccules, whereas a high concentration was found in condensing vacuoles, apical vesicles, and in the luminal colloid. Varying amounts of label were observed over the different types of colloid droplets, and this was attributed to various degrees of lysosomal degradation of thyroglobulin. It is concluded that the concentration of thyroglobulin antigenicity increases during transport from the ribosomal site of synthesis to the follicular colloid, and then decreases during the digestion of colloid droplets which leads to the release of the thyoid hormone. 相似文献
154.
Summary Myxamoebae ofEchinostelium minutum exhibit extranuclear (open spindle) mitosis with centrioles present at the poles. Spindle microtubules are formed in association with a juxtanuclear MTOC which surrounds the cell's complement of centrioles. During late prophase or prometaphase the nuclear envelope breaks down and subsequently a metaphase plate is formed. Two anaphasic movements occur sequentially: firstly, the distance of the chromosomes to the poles shortens; secondly the distance between the spindle poles increases. The arrangement of spindle microtubules during anaphase is consistent with the hypothesis that chromosomal separation is due to lateral interaction (zippering) of microtubules. During telophase, reconstitution of the nuclear envelope usually takes place in the interzonal region prior to reformation in the polar region. Cytokinesis, which begins in anaphase or early telophase involves the participation of vesicles, microfilaments and microtubules.Based on the doctoral dissertation of the first author presented to the Department of Botany, University of Washington, Seattle, WA 98195, U.S.A. 相似文献
155.
Summary Mitosis in the plasmodium ofEchinostelium minutum is intranuclear (closed spindle) and centrioles are not present at the spindle poles. The nuclear envelope remains essentially intact throughout mitosis with polar fenestrae appearing in anaphase and persisting through telophase. During anaphase there is a shortening in the distance of the chromosomes to the poles followed by a further separation of the poles. Zippering of microtubules may be the basis for these two anaphasic movements. During telophase the polar MTOCs are extruded into the cytoplasm through the polar fenestrae prior to reconstitution of the nuclear envelope. It is proposed that during sporulation such MTOCs are responsible for the differentiation of the centrioles which subsequently persist in the myxamoebal phase of this species.Based on the doctoral dissertation of the first author presented to the Department of Botany, University of Washington, Seattle, WA 98195, U.S.A. 相似文献
156.
Reaction of endotoxin and surfactants. I. Physical and biological properties of endotoxin treated with sodium deoxycholate 总被引:31,自引:7,他引:24
E Ribi R L Anacker R Brown W T Haskins B Malmgren K C Milner J A Rudbach 《Journal of bacteriology》1966,92(5):1493-1509
Ribi, E. (Rocky Mountain Laboratory, Hamilton, Mont.), R. L. Anacker, R. Brown, W. T. Haskins, B. Malmgren, K. C. Milner, and J. A. Rudbach. Reaction of endotoxin and surfactants. I. Physical and biological properties of endotoxin treated with sodium desoxycholate. J. Bacteriol. 92:1493-1509. 1966.-Endotoxins from three species of gram-negative bacteria were shown to be dissociated by the bile salt sodium deoxycholate (NaD) into nontoxic subunits with molecular weights of about 20,000. When the bile salt was removed by dialysis, the subunits reaggregated in an orderly manner to form a relatively uniform population of biologically active endotoxin particles with average molecular weights of 500,000 to 1,000,000. If a small amount of human plasma was added to the dissociated endotoxin before removal of the NaD, reassociation apparently did not occur and the preparation remained nonpyrogenic. However, the plasma protein could subsequently be removed from the endotoxin subunits, and reaggregation to the toxic form would then occur. The studies on the physical nature of endotoxin performed with biophysical solution techniques were supplemented and confirmed by direct examination of the endotoxin polymers by electron microscopy. The results of these studies were consonant with the theory that the biologically active endotoxic elements are composed of micellar aggregates of linear lipopolysaccharide subunits. 相似文献
157.
158.
The clock gene period (per) controls a number of biological rhythms in
Drosophila. In D. melanogaster, per has a repetitive region that encodes a
number of alternating threonine-glycine residues. We sequenced and compared
this region from several different Drosophila species belonging to various
groups within the Drosophila and Sophophora subgenera. This part of per
shows a great variability in both DNA sequence and length. Furthermore,
analysis of the data suggests that changes in the length of this variable
region might be associated with amino acid replacements in the more
conserved flanking sequences.
相似文献
159.
Bas E Dutilh Cristiane C Thompson Ana CP Vicente Michel A Marin Clarence Lee Genivaldo GZ Silva Robert Schmieder Bruno GN Andrade Luciane Chimetto Daniel Cuevas Daniel R Garza Iruka N Okeke Aaron Oladipo Aboderin Jessica Spangler Tristen Ross Elizabeth A Dinsdale Fabiano L Thompson Timothy T Harkins Robert A Edwards 《BMC genomics》2014,15(1)
Background
Vibrio cholerae is a globally dispersed pathogen that has evolved with humans for centuries, but also includes non-pathogenic environmental strains. Here, we identify the genomic variability underlying this remarkable persistence across the three major niche dimensions space, time, and habitat.Results
Taking an innovative approach of genome-wide association applicable to microbial genomes (GWAS-M), we classify 274 complete V. cholerae genomes by niche, including 39 newly sequenced for this study with the Ion Torrent DNA-sequencing platform. Niche metadata were collected for each strain and analyzed together with comprehensive annotations of genetic and genomic attributes, including point mutations (single-nucleotide polymorphisms, SNPs), protein families, functions and prophages.Conclusions
Our analysis revealed that genomic variations, in particular mobile functions including phages, prophages, transposable elements, and plasmids underlie the metadata structuring in each of the three niche dimensions. This underscores the role of phages and mobile elements as the most rapidly evolving elements in bacterial genomes, creating local endemicity (space), leading to temporal divergence (time), and allowing the invasion of new habitats. Together, we take a data-driven approach for comparative functional genomics that exploits high-volume genome sequencing and annotation, in conjunction with novel statistical and machine learning analyses to identify connections between genotype and phenotype on a genome-wide scale.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-654) contains supplementary material, which is available to authorized users. 相似文献160.
Joris J Benschop Tineke L Lenstra Dik van Leenen Marian JA Groot Koerkamp Thanasis Margaritis Mariel O Brok Patrick Kemmeren Frank CP Holstege 《Molecular systems biology》2014,10(6):732
Growth condition perturbation or gene function disruption are commonly used strategies to study cellular systems. Although it is widely appreciated that such experiments may involve indirect effects, these frequently remain uncharacterized. Here, analysis of functionally unrelated Saccharyomyces cerevisiae deletion strains reveals a common gene expression signature. One property shared by these strains is slower growth, with increased presence of the signature in more slowly growing strains. The slow growth signature is highly similar to the environmental stress response (ESR), an expression response common to diverse environmental perturbations. Both environmental and genetic perturbations result in growth rate changes. These are accompanied by a change in the distribution of cells over different cell cycle phases. Rather than representing a direct expression response in single cells, both the slow growth signature and ESR mainly reflect a redistribution of cells over different cell cycle phases, primarily characterized by an increase in the G1 population. The findings have implications for any study of perturbation that is accompanied by growth rate changes. Strategies to counter these effects are presented and discussed. 相似文献