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1.
2.
Raif G. Vasilov Alfred Hahn Horst Mölders Jon J. van Rood Martijn Breuning Hidde L. Ploegh 《Immunogenetics》1983,17(4):333-356
Class I antigens were isolated by immunoprecipitation from cell extracts prepared from mitogenically stimulated and internally radiolabeled peripheral blood lymphocytes (PLBs). The precipitating antibodies used are monomorphic and recognize a determinant on the heavy chain of HLA-A, B, C antigens regardless of their allelic specificities when complexed with
2m, or determinants on
2m itself. Comparison of class I molecules isolated from 25 different homozygous typing cels (HTC) and analyzed by two-dimensional (2-D) gel electrophoresis allowed the identification of those HLA-A,13 locus specificities most common in the European Caucasoid population. Class I antigens isolated from HTC that are HLA identical are biochemically indistinguishable also. Evidence was obtained for the expression of additional class I antigens besides the HLA-A, B, C locus products: for some haplotypes, up to six class I genes may be active in mitogenically activated PBLs. No differences in molecular weight and isoelectric point of the class I heavy chains were observed between the antigens recognized by W6/32, the anti-heavy chain reagent, and anti-
2m reagents. The nature of the mitogenic stimulus, i. e., pokeweed mitogen or phytohemagglutinin, was irrelevant with respect to the class I antigens isolated by this method. Using the HTCs as reference, a panel of HLA-B27 positive heterozygous cells was analyzed. Two types of HLA-B27 antigens, distinct by CML typing were represented. These two forms differed also in their biochemical properties. In addition, we obtained evidence for the existence of an A2 variant. This finding was likewise confirmed by CML typing. 相似文献
3.
Martijn A. Huynen 《Journal of molecular evolution》1996,43(3):165-169
RNA secondary-structure folding algorithms predict the existence of connected networks of RNA sequences with identical secondary
structures. Fitness landscapes that are based on the mapping between RNA sequence and RNA secondary structure hence have many
neutral paths. A neutral walk on these fitness landscapes gives access to a virtually unlimited number of secondary structures
that are a single point mutation from the neutral path. This shows that neutral evolution explores phenotype space and can
play a role in adaptation.
Received: 23 December 1995 / Accepted: 17 March 1996 相似文献
4.
Donatella Zona Peter M. Lafleur Koen Hufkens Beniamino Gioli Barbara Bailey George Burba Eugénie S. Euskirchen Jennifer D. Watts Kyle A. Arndt Mary Farina John S. Kimball Martin Heimann Mathias Göckede Martijn Pallandt Torben R. Christensen Mikhail Mastepanov Efrén López-Blanco Albertus J. Dolman Roisin Commane Charles E. Miller Josh Hashemi Lars Kutzbach David Holl Julia Boike Christian Wille Torsten Sachs Aram Kalhori Elyn R. Humphreys Oliver Sonnentag Gesa Meyer Gabriel H. Gosselin Philip Marsh Walter C. Oechel 《Global Change Biology》2023,29(5):1267-1281
Long-term atmospheric CO2 concentration records have suggested a reduction in the positive effect of warming on high-latitude carbon uptake since the 1990s. A variety of mechanisms have been proposed to explain the reduced net carbon sink of northern ecosystems with increased air temperature, including water stress on vegetation and increased respiration over recent decades. However, the lack of consistent long-term carbon flux and in situ soil moisture data has severely limited our ability to identify the mechanisms responsible for the recent reduced carbon sink strength. In this study, we used a record of nearly 100 site-years of eddy covariance data from 11 continuous permafrost tundra sites distributed across the circumpolar Arctic to test the temperature (expressed as growing degree days, GDD) responses of gross primary production (GPP), net ecosystem exchange (NEE), and ecosystem respiration (ER) at different periods of the summer (early, peak, and late summer) including dominant tundra vegetation classes (graminoids and mosses, and shrubs). We further tested GPP, NEE, and ER relationships with soil moisture and vapor pressure deficit to identify potential moisture limitations on plant productivity and net carbon exchange. Our results show a decrease in GPP with rising GDD during the peak summer (July) for both vegetation classes, and a significant relationship between the peak summer GPP and soil moisture after statistically controlling for GDD in a partial correlation analysis. These results suggest that tundra ecosystems might not benefit from increased temperature as much as suggested by several terrestrial biosphere models, if decreased soil moisture limits the peak summer plant productivity, reducing the ability of these ecosystems to sequester carbon during the summer. 相似文献
5.
Martijn H. Breuning Ella M. van den Berg-Loonen Luigi F. Bernini Jan B. Bijlsma Erna van Loghem P. Meera Khan Lourens E. Nijenhuis 《Human genetics》1977,37(2):131-139
Summary A detailed marker gene study in a large Dutch kindred segregating for a reciprocal translocation between the chromosomes 6 and 20, t(6;20) (p21;p13), revealed a close linkage between the HLA genes and the breakpoint on the short arm of 6. During this study an apparent peak lod score of 2.9 was obtained at a recombination value of 0.05 for a linkage between HLA and the breakpoint, indicating that the chromosomal region, carrying the HLA genes, is situated near the breakpoint in band 6p21 close to the transition to 6p22. 相似文献
6.
Yukie Sato Maurice W. Sabelis Martijn Egas Farid Faraji 《Experimental & applied acarology》2013,61(1):31-41
Severe intraspecific competition for mates selects for aggressive individuals but may also lead to the evolution of alternative phenotypes that do not act aggressively, yet manage to acquire matings. The two-spotted spider mite, Tetranychus urticae, shows male mate-guarding behaviour and male–male combat for available females. This may provide opportunity for weaker males to avoid fighting by adopting alternative mating behaviour such as sneaker or satellite tactics as observed in other animals. We investigated male precopulatory behaviour in the two-spotted spider mite by means of video-techniques and found three types of male mating behaviour: territorial, sneaker and opportunistic. Territorial and sneaker males associate with female teleiochrysales and spend much time guarding them. Territorial males are easily disturbed by rival males and engage themselves in fights with them. However, sneaker males are not at all disturbed by rival males, never engage in fights and, strikingly, never face attack by territorial males. Opportunistic males wander around in search of females that are in the teleiochrysalis stage but very close to or at emergence. To quickly classify any given mate-guarding male as territorial or sneaker we developed a method based on the instantaneous response of males to disturbance by a live male mounted on top of a brush. We tested this method against the response of the same males to natural disturbance by two or three other males. Because this method proved to be successful, we used it to collect territorial and sneaker males, and subjected them to morphological analysis to assess whether the various behavioural phenotypes are associated with different morphological characters. However, we found no statistical differences between territorial and sneaker males, concerning the length of the first legs, the stylets, the pedipalps or the body. 相似文献
7.
8.
Bouma B Kroon-Batenburg LM Wu YP Brünjes B Posthuma G Kranenburg O de Groot PG Voest EE Gebbink MF 《The Journal of biological chemistry》2003,278(43):41810-41819
Amyloid fibrils are components of proteinaceous plaques that are associated with conformational diseases such as Alzheimer's disease, transmissible spongiform encephalopathies, and familial amyloidosis. Amyloid polypeptides share a specific quarternary structure element known as cross-beta structure. Commonly, fibrillar aggregates are modified by advanced glycation end products (AGE). In addition, AGE formation itself induces protein aggregation. Both amyloid proteins and protein-AGE adducts bind multiligand receptors, such as receptor for AGE, CD36, and scavenger receptors A and B type I, and the serine protease tissue-type plasminogen activator (tPA). Based on these observations, we hypothesized that glycation induces refolding of globular proteins, accompanied by formation of cross-beta structure. Using transmission electron microscopy, we demonstrate here that glycated albumin condensates into fibrous or amorphous aggregates. These aggregates bind to amyloid-specific dyes Congo red and thioflavin T and to tPA. In contrast to globular albumin, glycated albumin contains amino acid residues in beta-sheet conformation, as measured with circular dichroism spectropolarimetry. Moreover, it displays cross-beta structure, as determined with x-ray fiber diffraction. We conclude that glycation induces refolding of initially globular albumin into amyloid fibrils comprising cross-beta structure. This would explain how glycated ligands and amyloid ligands can bind to the same multiligand "cross-beta structure" receptors and to tPA. 相似文献
9.
10.
Doohyung Lee Katja Apelt Seong-Ok Lee Hsin-Ru Chan Martijn S Luijsterburg Justin W C Leung Kyle
M Miller 《Nucleic acids research》2022,50(7):3922
An inability to repair DNA double-strand breaks (DSBs) threatens genome integrity and can contribute to human diseases, including cancer. Mammalian cells repair DSBs mainly through homologous recombination (HR) and nonhomologous end-joining (NHEJ). The choice between these pathways is regulated by the interplay between 53BP1 and BRCA1, whereby BRCA1 excludes 53BP1 to promote HR and 53BP1 limits BRCA1 to facilitate NHEJ. Here, we identify the zinc-finger proteins (ZnF), ZMYM2 and ZMYM3, as antagonizers of 53BP1 recruitment that facilitate HR protein recruitment and function at DNA breaks. Mechanistically, we show that ZMYM2 recruitment to DSBs and suppression of break-associated 53BP1 requires the SUMO E3 ligase PIAS4, as well as SUMO binding by ZMYM2. Cells deficient for ZMYM2/3 display genome instability, PARP inhibitor and ionizing radiation sensitivity and reduced HR repair. Importantly, depletion of 53BP1 in ZMYM2/3-deficient cells rescues BRCA1 recruitment to and HR repair of DSBs, suggesting that ZMYM2 and ZMYM3 primarily function to restrict 53BP1 engagement at breaks to favor BRCA1 loading that functions to channel breaks to HR repair. Identification of DNA repair functions for these poorly characterized ZnF proteins may shed light on their unknown contributions to human diseases, where they have been reported to be highly dysregulated, including in several cancers. 相似文献