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1.
2.
Crystallization and preliminary x-ray diffraction studies of two new antigen-antibody (lysozyme-Fab) complexes 总被引:2,自引:0,他引:2
T Fischmann H Souchon M M Riottot D Tello R J Poljak 《Journal of molecular biology》1988,203(2):527-529
The complexes between the Fab fragments of two monoclonal anti-lysozyme antibodies, Fab10.6.6 (high affinity) and D44.2 (lower affinity), and their specific antigen, hen egg-white lysozyme, have been crystallized. The antibodies recognize an antigenic determinant including Arg68, but differ significantly in their association constants for the antigen. Two crystalline forms were obtained for the complex with FabF10.6.6, the higher affinity antibody. One of them is monoclinic, space group P21, with unit cell dimensions a = 145.6 A, b = 78.1 A, c = 63.1 A, beta = 89.05 degrees, consistent with the presence of two molecules of the complex in the asymmetric unit. These crystals diffract X-rays beyond 3 A making this form suitable for high-resolution X-ray diffraction studies. The second form crystallizes in the triclinic space group P1, with unit cell dimensions a = 134.0 A, b = 144.7 A, c = 98.6 A, alpha = 90.30 degrees, beta = 97.1 degrees, gamma = 90.20 degrees, consistent with the presence of 10 to 12 molecules of the complex in the unit cell. These crystals do not diffract X-rays beyond 5 A resolution. The antigen-antibody complex between FabD44.2, the lower affinity antibody, and hen egg-white lysozyme crystallizes in space group P2(1)2(1)2(1), with unit cell dimensions a = 99.7 A, b = 167.3 A, c = 84.7 A, consistent with the presence of two molecules of the complex in the asymmetric unit. These crystals diffract X-rays beyond 2.5 A resolution. 相似文献
3.
Construction of immunogens for synthetic malaria vaccines 总被引:1,自引:0,他引:1
D Lise C Dubeaux D Tello D Mazier M Jolivet D H Schlesinger F Audibert L Chedid 《Biochemical and biophysical research communications》1988,153(1):31-38
The immunogenicity of a peptide consisting of eight repeats of the tetrapeptide sequence NANP (Asn-Ala-Asn-Pro) contained in the circumsporozoite protein of Plasmodium falciparum was investigated in mice under different modes of presentation. This peptide was able to produce biologically active antibodies when administered with adjuvant and linked to a protein carrier. However, a (NANP) peptide polymerized by carbodiimide was found to be immunogenic in the absence of protein carrier in H-2b mice. In contrast, the (NANP)8 peptide polymerized by glutaraldehyde was not immunogenic in the same strain. Furthermore, the efficacy of murabutide in saline, as an immunological adjuvant, was compared to the efficacy of Freund's complete adjuvant. 相似文献
4.
A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera 总被引:14,自引:1,他引:13
Levels of mitochondrial DNA (mtDNA) sequence divergence between species
within each of several avian (Anas, Aythya, Dendroica, Melospiza, and
Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were
compared. An analysis of digestion profiles generated by 13-18 restriction
endonucleases indicates little overlap in magnitude of mtDNA divergence for
the avian versus nonavian taxa examined. In 55 interspecific comparisons
among the avian congeners, the fraction of identical fragment lengths (F)
ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these
translate into estimates of nucleotide sequence divergence (p) ranging from
0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F
values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater
than 0.070. The small mtDNA distances among avian congeners are associated
with protein-electrophoretic distances (D values) less than approximately
0.2, while the mtDNA distances among assayed fish and amphibian congeners
are associated with D values usually greater than 0.4. Since the
conservative pattern of protein differentiation previously reported for
many avian versus nonavian taxa now appears to be paralleled by a
conservative pattern of mtDNA divergence, it seems increasingly likely that
many avian species have shared more recent common ancestors than have their
nonavian taxonomic counterparts. However, estimates of avian divergence
times derived from mtDNA- and protein-calibrated clocks cannot readily be
reconciled with some published dates based on limited fossil remains. If
the earlier paleontological interpretations are valid, then protein and
mtDNA evolution must be somewhat decelerated in birds. The empirical and
conceptual issues raised by these findings are highly analogous to those in
the long-standing debate about rates of molecular evolution and times of
separation of ancestral hominids from African apes.
相似文献
5.
Methods for computing the standard errors of branching points in an evolutionary tree and their application to molecular data from humans and apes 总被引:23,自引:2,他引:21
Statistical methods for computing the standard errors of the branching
points of an evolutionary tree are developed. These methods are for the
unweighted pair-group method-determined (UPGMA) trees reconstructed from
molecular data such as amino acid sequences, nucleotide sequences,
restriction-sites data, and electrophoretic distances. They were applied to
data for the human, chimpanzee, gorilla, orangutan, and gibbon species.
Among the four different sets of data used, DNA sequences for an
895-nucleotide segment of mitochondrial DNA (Brown et al. 1982) gave the
most reliable tree, whereas electrophoretic data (Bruce and Ayala 1979)
gave the least reliable one. The DNA sequence data suggested that the
chimpanzee is the closest and that the gorilla is the next closest to the
human species. The orangutan and gibbon are more distantly related to man
than is the gorilla. This topology of the tree is in agreement with that
for the tree obtained from chromosomal studies and DNA-hybridization
experiments. However, the difference between the branching point for the
human and the chimpanzee species and that for the gorilla species and the
human-chimpanzee group is not statistically significant. In addition to
this analysis, various factors that affect the accuracy of an estimated
tree are discussed.
相似文献
6.
W W Vick J W Tello C J Wikstrand X He D Longee P Fredman L Svennerholm D D Bigner W W Johnston S H Bigner 《Acta cytologica》1992,36(5):697-705
The cytologic evaluation of poorly differentiated tumors frequently poses a diagnostic dilemma as to the tissue of origin. To assess the diagnostic utility of monoclonal antibodies (MAbs) in these situations, we applied a panel of three highly purified MAbs specific for tumor-associated ganglioside epitopes to a diverse series of cytologic specimens. The panel was composed of DMAb-3, reactive with the epitope GalNAc beta 1-4 (NeuAc alpha 2-3)Gal- of GM2; DMAb-7, reactive with the epitope (NeuAc alpha 2-8NeuAc alpha 2-3)Gal beta 1-4(Glc or GlcNAc)- of GD3 and 3'8'-LD1; and DMAb-20, reactive with the epitope GalNAc beta 1-4(NeuAc alpha 2-8NeuAc alpha 2-3)Gal- of GD2. The cytologic material consisted of air-dried Cytospin preparations prepared predominantly from fine needle aspirates and stained with the ABC immunohistochemical method. Positive reactivity was recognized when greater than 5% of tumor cells stained with the antibody; lesser reactivity was called negative. DMAb-3 stained 9/14 (64%) glial tumors, 4/13 (31%) nonglial central nervous system tumors, 1/21 (5%) melanomas, 7/38 (18%) non-small cell carcinomas (NSCC), 1/15 (7%) small cell carcinomas (SCC), 0/9 (0%) lymphomas/leukemias, 2/10 (20%) sarcomas, 1/7 (14%) miscellaneous tumors and 2/2 (100%) reactive fluids. DMAb-7 recognized 14/14 (100%) glial tumors, 9/13 (69%) non-glial central nervous system tumors, 19/22 (86%) melanomas, 19/43 (44%) NSCC, 5/15 (33%) SCC, 2/9 (22%) lymphomas/leukemias, 6/10 (60%) sarcomas, 1/7 (14%) miscellaneous tumors and 4/4 (100%) reactive fluids. DMAb-20 stained 6/14 (43%) glial tumors, 2/13 (15%) nonglial central nervous system tumors, 1/21 (5%) melanomas, 4/38 (10%) NSCC, 0/15 (0%) SCC, 0/9 (0%) lymphomas/leukemias, 1/10 (10%) sarcomas, 1/7 (14%) miscellaneous tumors and 1/3 (33%) reactive fluids. The GD3-reactive DMAb-7 recognized a large portion of many tumor types and thus is not diagnostically useful alone. DMAb-3 and DMAb-20 were more selective and showed the strongest reactivity for glial tumors and minimal reactivity for melanomas, small cell carcinomas, and lymphomas or leukemias. DMAb-3 and DMAb-20 may be useful as components of a larger panel of MAbs in distinguishing between poorly differentiated tumors in samples derived from the central nervous system. 相似文献
7.
Anonymous nuclear DNA markers in the American oyster and their implications for the heterozygote deficiency phenomenon in marine bivalves 总被引:4,自引:0,他引:4
A puzzling population-genetic phenomenon widely reported in allozyme
surveys of marine bivalves is the occurrence of heterozygote deficits
relative to Hardy-Weinberg expectations. Possible explanations for this
pattern are categorized with respect to whether the effects should be
confined to protein-level assays or are genomically pervasive and expected
to be registered in both protein- and DNA-level assays. Anonymous nuclear
DNA markers from the American oyster were employed to reexamine the
phenomenon. In assays based on the polymerase chain reaction (PCR), two
DNA-level processes were encountered that can lead to artifactual genotypic
scorings: (a) differential amplification of alleles at a target locus and
(b) amplification from multiple paralogous loci. We describe symptoms of
these complications and prescribe methods that should generally help to
ameliorate them. When artifactual scorings at two anonymous DNA loci in the
American oyster were corrected, Hardy-Weinberg deviations registered in
preliminary population assays decreased to nonsignificant values.
Implications of these findings for the heterozygote-deficit phenomenon in
marine bivalves, and for the general development and use of PCR-based
assays, are discussed.
相似文献
8.
9.
Sarina Thiel Franziska Willems Nina Farwig Finn Rehling Dana G. Schabo Matthias Schleuning Ney Shahuano Tello Till Töpfer Marco Tschapka Eckhard W. Heymann Katrin Heer 《Biotropica》2023,55(3):650-664
Vertical stratification is a key feature of tropical forests and structures plant–frugivore interactions. However, it is unclear whether vertical differences in plant-frugivore interactions are due to differences among strata in plant community composition or inherent preferences of frugivores for specific strata. To test this, we observed fruit removal of a diverse frugivore community on the liana Marcgravia longifolia in a Peruvian rain forest. Unlike most other plants, Marcgravia longifolia produces fruits across forest strata. This enabled us to study effects of vertical stratification on fruit removal without confounding effects of plant species and stratum. We found a high number of visits of a few frugivore species in the understorey and a low number of visits of many different frugivores in the canopy and midstorey. Whereas partial and opportunistic frugivores foraged across strata with differing frequencies, obligate frugivores were only found eating fruits in the higher strata. Avian frugivores foraging in the canopy were mainly large species with pointed wings, whereas under- and midstorey avian foragers were smaller with rounded wings. Our findings suggest a continuous shift in the frugivore community composition along the vertical gradient, from a few generalized frugivores in the understorey to a diverse set of specialized frugivores in the canopy. This shift in the frugivore community leads to correlated, reciprocal changes from specialized to generalized plant-frugivore interactions. Thus, we conclude that vertical niche differentiation between species in tropical forests persists even when food resources are available across strata. This highlights its role for promoting biodiversity and ecosystem functioning. 相似文献
10.
Diseased fruit bodies of Agaricus bitorquis, with similar symptoms to those caused by dry bubble on Agaricus bisporus, were observed in some Spanish crops during summer 1999. Isolates of Verticillium fungicola from A. bitorquis and A. bisporus were submitted to different temperatures and to prochloraz–Mn sensitivity tests. All the isolates collected from A. bitorquis and A. bisporus were identified as V. fungicola var. fungicola. Artificial infections of A. bisporus and A. bitorquis with V. fungicola var. fungicola are also described in the present study. The appearance of natural infections of V. fungicola var. fungicola in A. bitorquis crops could well be due to the growing temperatures used in Spain, which are considerably below those used in other countries. 相似文献