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J. De Riek J. Dendauw M. Mertens M. De Loose J. Heursel E. Van Bockstaele 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(7-8):1155-1165
Fluorescent AFLP and automated data analysis were employed to assess the genetic conformity within a breeders’ collection
of evergreen azaleas. The study included 75 genotypes of Belgian pot azaleas (Rhododendron simsii Planch. hybrids), Kurume and Hirado azaleas and wild ancestor species from the Tsutsusi subgenus. Fluorescent detection and addition of an internal size standard to each lane enabled the automated scoring of each
fragment arising from a single AFLP primer combination (PC). The use of three PCs generated an initial data set with a total
of 648 fragments ranging from 70 bp to 450 bp. Different marker selection thresholds for average fluorescent signal intensity
and marker frequency were used to create eight extra restricted data subsets. Pairwise plant genetic similarity was calculated
for the nine data sets using the Simple Matching coefficient (symmetrical, including double-zeros) and Jaccard coefficient
(asymmetrical, excluding double zeros). The averages, the ranges and the correlation to one other (Mantel analysis) were compared
for the obtained similarity matrices. This revealed the sensitivity of ordinations obtained by both similarity coefficients
for the presence of weak or intensive markers or for the degree of polymorphism of the markers. For 34 cultivars, pedigree
information (at maximum to the fifth ancestor generation) was available. Genetic similarity by descent (kinship coefficient)
was turned into a genetic distance and correlated to the genetic conformity, as revealed by the different selections of AFLP
markers (Mantel analysis). Use of a Simple Matching coefficient with no or moderate selection to signal intensity and excluding
rare and abundant markers gave the best correlation with pedigree. Finally, the ordination of the studied genotypes by means
of dendrograms and principal co-ordinate analysis was confronted with known or accepted relationships based on geographical
origin, parentage and morphological characters. Genotypes could be assigned to three distinct groups: pot azaleas, Kurume
azaleas and Hirado azaleas. Wild ancestor species appeared to be more related to the Japanese azaleas. Intermediate cultivars
could be typified as crossings with Kurume or Hirado azaleas or with wild species.
Received: 3 September 1998 / Accepted: 25 March 1999 相似文献
95.
C L Hill T F Booth B V Prasad J M Grimes P P Mertens G C Sutton D I Stuart 《Nature structural biology》1999,6(6):565-568
Cytoplasmic polyhedrosis virus (CPV) is unique among the double-stranded RNA viruses of the family Reoviridae in having a single capsid layer. Analysis by cryo-electron microscopy allows comparison of the single shelled CPV and orthoreovirus with the high resolution crystal structure of the inner shell of the bluetongue virus (BTV) core. This suggests that the novel arrangement identified in BTV, of 120 protein subunits in a so-called 'T=2' organization, is a characteristic of the Reoviridae and allows us to delineate structural similarities and differences between two subgroups of the family--the turreted and the smooth-core viruses. This in turn suggests a coherent picture of the structural organization of many dsRNA viruses. 相似文献
96.
D. Gisselsson Mattias Höglund Fredrik Mertens Bertil Johansson Paola Dal Cin Herman Van den Berghe William C. Earnshaw Felix Mitelman Nils Mandahl 《Human genetics》1999,104(4):315-325
Acquired ring chromosomes have been found in most types of human neoplasia, with a frequency approaching 10% in malignant
mesenchymal tumours. In this study, the composition and dynamics of ring chromosomes were analysed in eight cases of acute
myelogenous leukaemia, 17 solid tumours, and five cases with constitutional rings. Chromosomal banding and fluorescence in
situ hybridisation were performed to determine the content and the structural heterogeneity of the rings. Telomeric repeats
were detected using peptide nucleic acid probes or primed in situ labelling, whereas centromeric activity was evaluated by
detection of kinetochore proteins. Mitotic instability was assessed by the frequency of anaphase bridges. The results suggest
that human ring chromosomes can be structurally and functionally divided into two categories. In the first of these, size
variation is minimal and rearrangement at cell division is uncommon. The majority of such rings contain subtelomeric sequences.
Constitutional ring chromosomes and most rings in leukaemias belong to this group, whereas only a few mesenchymal tumours
exhibit rings of this type. The second category consists of rings with amplified sequences, primarily from chromosome 12,
characteristically occurring in atypical lipomatous tumours and other subtypes of low or borderline malignant mesenchymal
neoplasms. Variation in size and number is extensive, and breakage-fusion-bridge events occur at a high frequency. Abnormalities
in pericentromeric sequences are common and, in some cases, kinetochores assemble in the absence of alphoid DNA. We conclude
that it is not only the ring structure per se or the neoplastic nature of the host cell that determines ring instability,
but probably also the functional role of the genes carried in the ring.
Received: 24 November 1998 / Accepted: 18 January 1999 相似文献
97.
Polygalacturonase (PG) enzymes hydrolyze the long polygalacturonic acid chains found in the smooth regions of pectin. Interest
in this enzyme class continues due to their ability to macerate tissues of economically important crops and their use in a
number of industrial processes. Rhizopus oryzae has a large PG gene family with 15 of 18 genes encoding unique active enzymes. The PG enzymes, 12 endo-PG and 3 exo-galacturonases,
were expressed in Pichia pastoris and purified enabling biochemical characterization to gain insight into the maintenance of this large gene family within
the Rhizopus genome. The 15 PG enzymes have a pH optima ranging from 4.0 to 5.0. Temperature optima of the 15 PG enzymes vary from 30
to 40°C. While the pH and temperature optima do little to separate the enzymes, the specific activity of the enzymes is highly
variable ranging from over 200 to less than 1 μmol/min/mg. A general pattern related to the groupings found in the phylogentic
tree was visible with the group containing the exo-PG enzymes demonstrating the lowest specific activity. Finally, the progress
curves of the PG enzymes, contained within the phylogenetic group that includes the exo-PG enzymes, acting on trigalacturonic
acid lend additional support to the idea that the ancestral form of PG in Rhizopus is endolytic and exolytic function evolved later. 相似文献
98.
The three-dimensional structure of activated factor IX comprises multiple contacts between the two epidermal growth factor (EGF)-like domains. One of these is a salt bridge between Glu(78) and Arg(94), which is essential for binding of factor IXa to its cofactor factor VIII and for factor VIII-dependent factor X activation (Christophe, O. D., Lenting, P. J., Kolkman, J. A., Brownlee, G. G., and Mertens, K. (1998) J. Biol. Chem. 273, 222-227). We now addressed the putative hydrophobic contact at the interface between the EGF-like domains. Recombinant factor IX chimeras were constructed in which hydrophobic regions Phe(75)-Phe(77) and Lys(106)-Val(108) were replaced by the corresponding sites of factor X and factor VII. Activated factor IX/factor X chimeras were indistinguishable from normal factor IXa with respect to factor IXa enzymatic activity. In contrast, factor IXa(75-77)/factor VII displayed approximately 2-fold increased factor X activation in the presence of factor VIII, suggesting that residues 75-77 contribute to cofactor-dependent factor X activation. Activation of factor X by factor IX(106-108)/factor VII was strongly decreased, both in the absence and presence of factor VIII. Activity could be restored by simultaneous substitution of the hydrophobic sites in both EGF-like domains for factor VII residues. These data suggest that factor IXa enzymatic activity requires hydrophobic contact between the two EGF-like domains. 相似文献
99.
Peterson C Simon M Hodges J Mertens P Higgins L Egelman E Anderson D 《Journal of structural biology》2001,135(1):18-25
The protein composition of the Bacillus subtilis bacteriophage phi29 prohead and virion was determined by combustion of gel bands of (3)H-labeled proteins. Copy numbers of individual proteins were calculated relative to the 12 copies of the head-tail connector protein. The mean numbers of copies of the major capsid protein in the prohead and virion were 241 and 218, respectively, approaching the 235 copies determined previously by cryoelectron microscopy. The mean numbers of copies of the dimeric head fiber on the prohead and virion were 24 and 31, respectively, demonstrating partial occupancy of the 55 fiber binding sites. Measured copies of neck and tail proteins in the virion included 11 of the lower collar, 58 of the appendage, and 9 of the tail; if the true copies of these proteins are 12, 60, and 9, respectively, the entire neck and tail of phi29 has quasi-sixfold symmetry. The mass of the fiberless prohead with pRNA was about 14.2 MDa, and the mass of the prohead determined by scanning transmission electron microscopy was consistent with the biochemical data. The mass of the fiberless virion containing the 12.8-MDa DNA genome was about 30.4 MDa. A full complement of dimeric fibers on the prohead or virion would increase the mass of the particle by about 3.2 MDa. The data complement studies relating the structure of phi29 components to dynamic functions in morphogenesis and infection. 相似文献
100.