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1.
The E3/19K protein of adenovirus type 2 binds to the domains of histocompatibility antigens required for CTL recognition 总被引:9,自引:0,他引:9 下载免费PDF全文
The E3/19K protein of human adenovirus type 2 binds to HLA class I antigens and blocks their terminal glycosylation and cell surface expression. The nature of this interaction is non-covalent and involves neither disulfide bridges between the two molecules nor their carbohydrates. The murine H-2 Kd antigen associates with the E3/19K protein in a similar fashion to human HLA antigens whereas the allelic product H-2 Kk does not. Hybrid genes between the Kd and Kk alleles were constructed and their products were expressed in embryonic kidney cells together with the E3/19K protein. This allowed us to identify the alpha 1 and alpha 2 domains as the essential structures of the histocompatibility antigens for binding the viral protein. Interestingly, these domains are also crucial for T cell recognition. The implications for the evolution of adenoviruses and their ability to cause persistent infections are discussed. 相似文献
2.
Jens Kvist Nielsen Arne Henrik Kirkeby-Thomsen Marianne K. Petersen 《Entomologia Experimentalis et Applicata》1989,53(2):157-166
Host plant relations of the monophagous weevil Ceutorhynchus constrictus Marsh. (Coleoptera: Curculionidae: Ceutorhynchinae) feeding on garlic mustard, Alliaria petiolata (Bieb.) Cavara & Grande (Cruciferae) were studied in the laboratory. Most other crucifers were rejected in choice tests using garlic mustard as a reference plant, but Brassica nigra, Sinapis alba and Thlaspi arvense were as acceptable as the host plant. Flowering plants of Descurainia sophia were acceptable while young plants of this species were not. The most important feeding stimulants in extracts of garlic mustard were uncharged, water soluble compounds. The most abundant glucosinolate in garlic mustard, sinigrin, was a feeding stimulant, too. However, the feeding stimulatory activity of sinigrin was only expressed in the presence of still unidentified uncharged compounds from garlic mustard leaves. Host plant relations in monophagous crucifer-feeding insects is discussed in relation to the distinctness of glucosinolate patterns found in their host plants.
Zusammenfassung Ceutorhynchus constrictus Marsh. (Coleoptera: Chrysomelidae: Ceutorhynchinae) ist ein monophager Rüsselkäfer, der an Knoblauchhederich frisst. Das Wirtswahl-Verhalten dieses Käfers ist im Labor untersucht worden. Die meisten Crucifiren waren im Wahlversuche nicht akzeptiert, wenn Knoblauchhederich als Vergleichspflanze vorhanden war. Von Brassica nigra, Sinapis alba, und Thlaspi arvense wurden im Vergleich gleiche Mengen verzehrt wie von der Wirtspflanze. Blühende Descurainia sophia Pflanzen wurden, im Gegensatz zu Jungpflanzen der gleichen Art, angenommen. Die wichtichsten Phagostimulanten in Extrakten von Knoblauchhederich-Blättern waren ungeladene, wasserlösliche Substanzen. Das häufigste Glukosinolat im Knoblauchhederich, Sinigrin, war auch ein Phagostimulant. Doch war die phagostimulierende Wirkung von Sinigrin nur in Kombinationen mit noch nicht identifizierten, ungeladenen Substanzen aus Knoblauchhederich-Blätter nachweisbar. Wirtspfanzen-Beziehungen von monophagen Insekten werden diskutiert im Zusammenhang mit der Eigenart des Glukosinolat-Inhaltes ihrer Wirtspflanzen.相似文献
3.
Jens Kvist Nielsen 《Entomologia Experimentalis et Applicata》1989,51(3):249-259
All recorded host plants of Phyllotreta nemorum L. (Coleoptera: Chrysomelidae) contain glucosinolates and belong to the plant families Brassicaceae (Cruciferae), Resedaceae and Capparaceae. The acceptability of 56 plant species from 28 other plant families (non-hosts) for young larvae has been studied in the laboratory. None of these species were fully acceptable for initiations of leaf mines when intact untreated leaves were presented, and only one species, Malva silvestris L. (Malvaceae), was partially acceptable. The acceptability of some species increased when leaf discs were presented instead of intact leaves; but the highest percentages of mine initiations occurred in leaf discs treated with the glucosinolate, sinigrin. A stimulatory effect of sinigrin could be demonstrated in experiments with 7 plant species: Papaver dubium L., Papaver rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. and Lactuca sativa L. The majority of species remained unacceptable even after treatment with glucosinolates.The main causes for these differences between plant species are supposed to be differences in contents of deterrents and/or other stimulants for mine initiation. These possibilities are discussed in relation to the content of allelochemicals in acceptable plants and the position of these plants in botanical classifications.
Zusammenfassung Phyllotreta nemorum L. ist ein oligophager Erdfloh, der an Cruciferen und anderen Glukosinolat-haltigen Pflanzenarten gebunden ist. Die Imagines fressen Löcher in die Blätter und die Weibchen legen ihre Eier in den Boden. Die Larven sind Blattminierer. Nach dem Schlüpfen im Boden klettern sie an die Pflanzen hoch, und die Einbohrung und der Anfang der Minierung erfolgt in eines der unteren Blätter der Wirtspflanze.Die Wirkung von Glukosinolaten auf die Einbohrung von Junglarven in Pflanzenarten, die keine natürliche Inhalt von Glukosinolaten haben, ist in Laborexperimenten untersucht worden. 56 Pflanzenarten aus 28 Familien wurden präsentiert teils als unbehandelte Blätter und teils als Glukosinolatbehandelte Blattscheiben. Unbehandelte Blätter von nicht-Glukosinolathaltigen Arten waren immer unbefriedigend für die Larven. Nur in eine Art, Malva silvestris L. war die Frequenz der Einbohrung ein bisschen höher als 10%. Eine signifikante Erhöherung der Anzahl eingebohrten Larven nach der Sinigrin-behandlung erfolgte in 7 Pflanzenarten: Papaver dubium L., P. rhoeas L., Fumaria officinalis L., Malva silvestris L., Pisum sativum L., Campanula latifolia L. und Lactuca sativa L. Doch blieben die meisten Pflanzenarten (84%) auch nach der Sinigrin-Behandlung unbesiedelt.Pflanzenarten, die nach der Sinigrin-Behandlung nicht besiedelt werden enthalten vielleicht frasshemmende Stoffe, oder ihnen fehlen noch weitere Frass-stimulierende Stoffe. Diese Möglichkeiten werden diskutiert in Zusammenhang mit den Inhalt von Allelochemikalien in besiedelten Pflanzenarten und mit ihrer taxonomischer Position.相似文献
4.
5.
Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews
(genus Sorex) for the region between the tRNA(Pro) and the conserved
sequence block-F revealed variable numbers of 79-bp tandem repeats. These
repeats were found in all 19 individuals sequenced, representing three
subspecies and one closely related species of the masked shrew group (Sorex
cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an
outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an
adjacent 76-bp imperfect copy of the tandem repeats. One individual was
heteroplasmic for length variants consisting of five and seven copies of
the 79-bp tandem repeat. The sequence of the repeats is conducive to the
formation of secondary structure. A termination-associated sequence is
present in each of the repeats and in a unique sequence region 5' to the
tandem array as well. Mean genetic distance between the masked shrew taxa
and the pygmy shrew was calculated separately for the unique sequence
region, one of the tandem repeats, the imperfect repeat, and these three
regions combined. The unique sequence region evolved more rapidly than the
tandem repeats or the imperfect repeat. The small genetic distance between
pairs of tandem repeats within an individual is consistent with a model of
concerted evolution. Repeats are apparently duplicated and lost at a high
rate, which tends to homogenize the tandem array. The rate of D- loop
sequence divergence between the masked and pygmy shrews is estimated to be
15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid
sequence evolution in shrews may be due either to their high metabolic rate
and short generation time or to the presence of variable numbers of tandem
repeats.
相似文献
6.
7.
大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育 总被引:1,自引:0,他引:1
本实验用免疫组织化学ABC法研究了大鼠胼胝体内神经肽Y免疫反应阳性(NPY-IR)纤维的生后发育。结果发现,许多NPY-IR纤维在大鼠出生时便存在于胼胝体内。NPY-IR胼胝体纤维的密度在生后1周内继续逐渐增高,在第2周内达到最高峰。之后,NPY-IR胼胝体纤维的密度逐渐下降,至第3周末时接近成年时的水平,即仅有少量NPY-IR纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多NPY-IR胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。 相似文献
8.
Complete nucleotide sequence of the murine H-2Kk gene. Comparison of three H-2K locus alleles. 总被引:16,自引:3,他引:13 下载免费PDF全文
We have determined the DNA sequence of the H-2Kk gene of the mouse major histocompatibility complex (MHC). Comparison on the nucleotide and protein level of three H-2K alleles (Kk, Kb and Kd) reveals a high degree of homology, in particular between the Kb and Kk alleles. Differences between the two latter antigens are almost exclusively confined to the alpha 1 and alpha 2 domains. At nine positions in the extracellular part of the molecules we have found allele-specific amino acids. Interestingly, 78% of these residues are either polar or carry hydroxyl-groups. This makes it likely that they are exposed on the surface of the molecules and might then be part of antigenic determinants. We have also identified potentially allele-specific nucleotide sequences of the K genes which might be used as specific DNA probes. 相似文献
9.
B Dobberstein S Kvist L Roberts 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1982,300(1099):161-172
Histocompatibility antigens (H-2K, D and L, and HLA-A, B and C) are highly polymorphic cell surface proteins. Their primary structure has been determined by sequencing the protein, complementary DNAs (cDNAs) or genes in several laboratories. H-2Ld and Kd antigens are encoded by eight separate exons: one encodes the signal sequence, three encode the external domains, one encodes the membrane spanning segment and three encode the cytoplasmic domain. A similar structural organization has been found for an HLA gene. H-2 and HLA antigens are synthesized on membrane-bound ribosomes and are co-translationally inserted into the membrane of the endoplasmic reticulum. Here they assemble with beta 2-microglobulin, a small secretory protein. We describe the structure, the membrane insertion in vitro and in vivo, the intracellular transport and the surface expression of these antigens. 相似文献
10.
Jens Kvist Nielsen 《Entomologia Experimentalis et Applicata》1978,24(1):41-54
Feeding responses of four Chrysomelidae to six less acceptable plants and to compounds from them were investigated by means of leaf disc tests. Significant differences were found between responses of different species, and plants containing potent feeding inhibitors were always rejected. Cucurbitacins are potent feeding inhibitors to Phyllotreta nemorum, and this species does not eat Iberis species containing these compounds. Cardenolides are potent feeding inhibitors to P. undulata, P. tetrastigma and Phaedon cochleariae, and these three species do not eat the cardenolide containing Cheiranthus and Erysimum.Six different glucosinolates all proved to be stimulatory when applied to pea leaf discs. Although the glucosinolates differed somewhat in their ability to stimulate feeding, no correlation is found between content of glucosinolates and acceptability of the investigated plants. Application of sinigrin to Iberis and Cheiranthus did not improve their acceptability. The presence of glucosinolates is necessary for feeding to occur, but it is less important which glucosinolates are present.Cardenolides and cucurbitacins are suggested to be a second generation of protective compounds in Cruciferae, glucosinolates being the first.
The Danish Natural Science Research Council supported the research. 相似文献
Zusammenfassung Der Einfluss einiger sekundärer Pflanzenstoffe aus Cruciferen auf die Futteraufnahme von vier Chrysomeliden, die auf dieser Pflanzenfamilie vorkommen, wurde mittels Blattscheiben-Tests untersucht. Cucurbitacine sind starke Frasshemmstoffe für Phyllotreta nemorum, weniger starke Hemmstoffe für P. undulata und schwache Hemmstoffe für P. tetrastigma und Phaedon cochleariae. Iberis-Arten, die Cucurbitacine enthalten, werden von P. nemorum und P. undulata abgelehnt, von den beiden anderen Arten aber akzeptiert. Cardenolid-Glykoside vom Strophanthidin-Typ sind starke Frasshemmstoffe für P. undulata, P. tetrastigma und Phaedon cochleariae. Diese Arten lehnen Cheiranthus-und Erysimum-Arten, die solche Stoffe enthalten, ab. Die Futteraufnahme von P. nemorum wird von diesen Stoffen nicht beeinflusst; P. nemorum akzeptiert Cheiranthus- und Erysimum-Arten.Futteraufnahme fand bei Abwesenheit von Senfölglukosiden nicht statt. Sechs verschiedene Senfölglukoside waren alle imstande, das Aufnehmen von Erbsen-Blattscheiben zu stimulieren. Gewisse Unterschiede in der stimulierenden Wirkung der einzelnen Glukoside wurden gefunden. Das Vorkommen bestimmter Glukoside und die Akzeptabilität der Pflanzen zeigten aber keine Korrelation. Anwesenheit oder Abwesenheit von Frasshemmstoffen beeinflusst die Akzeptabilität der Pflanzenarten mehr als die Anwesenheit bestimmter Senfölglukoside.Wenn Senfölglukoside als eine erste Generation von Abwehrstoffen in Cruciferen aufgefasst werden, können Cucurbitacine in Iberis und Cardenolid-Glykoside in Cheiranthus und Erysimum als eine zweite betrachtet werden.
The Danish Natural Science Research Council supported the research. 相似文献