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21.
Cytochemical demonstration of hydrogen peroxide in polymorphonuclear leukocyte phagosomes 总被引:7,自引:1,他引:6
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Phagocytosis by polymorphonuclear leukocytes (PMN) is accompanied by specific morphological and metabolic events which may result in the killing of internalized micro-organism. Hydrogen peroxide is produced in increased amounts during phagocytosis (17) and in combination with myeloperoxidase and halide ions constitute a potent, microbicidal mechanism (8,9,11). There can be direct iodination of micro-organisms (10), or alternatively, other intermediate reaction products, i.e. chloramines and aldehydes (21), can exert a microbicidal effect. The H2O2-peroxidase-halide system is presumed to operate within the phagocytic vacuole (12,18). Myeloperoxidase, present in the primary granules of PMN, enters the phagocytic vacuole during degranulation (1,4,7), and halide ions are probably derived from the extracellular medium or are present in the PMN (see 11, 18). For the operation of this system in intact cells, the presence of H2O2 in the phagocytic vacuole is necessary, and indeed this has been suggested by the work of several investigators (12, 18, 21). In the present investigation, the diaminobenzidine reaction of Graham and Karnovsky (5), modified to utilize endogenous myeloperoxidase and hydrogen peroxide, has been applied to actively phagocytizing PMN to demonstrate cytochemically the presence of H2O2 in the phagocytic vacuole. 相似文献
22.
Tobamoviruses, mostly isolated from solanaceous plants, may represent
ancient virus lineages that have codiverged with their hosts. Recently
completed nucleotide sequences of six nonsolanaceous tobamoviruses allowed
assessment of the codivergence hypothesis and support a third subgroup
within tobamoviruses. The genomic sequences of 12 tobamoviruses and the
partial sequences of 11 others have been analyzed. Comparisons of the
predicted protein sequences revealed three clusters of tobamoviruses,
corresponding to those infecting solanaceous species (subgroup 1), those
infecting cucurbits and legumes (subgroup 2), and those infecting
crucifers. The orchid-infecting odontoglossum ringspot tobamovirus was
associated with subgroup 1 genomes by its coat and movement protein
sequences, but with the crucifer-pathogenic tobamoviruses by the remainder
of its genome, suggesting that it is the progeny of a recombinant. For four
of five genomic regions, subgroup 1 and 3 genomes were equidistant from a
subgroup 2 genome chosen for comparison, suggesting uniform rates of
evolution. A phylogenetic tree of plant families based on the tobamoviruses
they harbor was congruent with that based on rubisco sequences but had a
different root, suggesting that codivergence was tempered by rare events of
viruses of one family colonizing another family. The proposed subgroup 3
viruses probably have an origin of virion assembly in the movement protein
gene, a large (25-codon) overlap of movement and coat protein open reading
frames, and a comparably shorter genome. Codon-position- dependent base
compositions and codon prevalences suggested that the coat protein frame of
the overlap region was ancestral. Bootstrapped parsimony analysis of the
nucleotides in the overlap region and of the sequences translated from the
-1 frame (the subgroup 3 movement protein frame) of this region produced
trees inconsistent with those deduced from other regions. The results are
consistent with a model in which a no or short overlap organization was
ancestral. Despite encoding of subgroup 2 and 3 movement protein C-termini
by nonhomologous nucleotides, weak similarities between their amino acid
sequences suggested convergent sequence evolution.
相似文献
23.
Mapping of the cyst nematode resistance locus Gpa2 in potato using a strategy based on comigrating AFLP markers 总被引:9,自引:0,他引:9
J. Rouppe van der Voort P. Wolters R. Folkertsma R. Hutten P. van Zandvoort H. Vinke K. Kanyuka A. Bendahmane E. Jacobsen R. Janssen J. Bakker 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(5-6):874-880
The nematode resistance locus Gpa2 was mapped on chromosome 12 of potato using information on the genomic positions of 733 known AFLP markers. The minimum number
of AFLP primer combinations required to map Gpa2 was three. This demonstrates that a reference collection of potato AFLP markers may be a valuable tool for mapping studies
in potato. By use of RFLP probes, Gpa2 was more precisely mapped at the distal end of chromosome 12. Gpa2 confers resistance to a distinct group of populations of the potato cyst nematode Globodera pallida and originates from the same potato accession as locus H1, conferring resistance to pathotype Ro1 of G. rostochiensis. This study shows that these two nematode resistance loci are unlinked and that Gpa2 is linked to the Rx1 locus conferring resistance to potato virus X. The efficiency of AFLPs for genetic mapping of a highly heterozygous crop
like potato is discussed and compared with the RFLP technique.
Received: 24 February 1997/Accepted: 2 May 1997 相似文献
24.
J. Rouppe van der Voort W. Lindeman R. Folkertsma R. Hutten H. Overmars E. van der Vossen E. Jacobsen J. Bakker 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(5):654-661
Broad-spectrum resistance in potato to the potato cyst nematode (PCN) species Globodera rostochiensis and G. pallida is commonly regarded as a polygenically inherited trait. Yet, by use of QTL analysis and a selected set of PCN populations,
resistance to both PCN species could be ascribed to the action of locus Grp1. Grp1 confers major resistance to G. rostochiensis line Ro5-22 and G. pallida population Pa2-D383 and partial resistance to G. pallida population Pa3-Rookmaker. Grp1 was mapped on chromosome 5 using previously characterized AFLP markers. Cleaved amplified polymorphic sequence (CAPS) markers
available for RFLP loci GP21 and GP179 revealed that Grp1 maps on a genomic region harboring other resistance factors to viral, fungal and nematodal pathogens. The present data indicate
that Grp1 is a compound locus which contains multiple genes involved in PCN resistance.
Received: 10 September 1997 / Accepted: 6 October 1997 相似文献
25.
Both the Entamoeba histolytica lectin, a virulence factor for the causative
agent of amebiasis, and the mammalian hepatic lectin bind to
N-acetylgalactosamine (GalNAc) and galactose (Gal) nonreducing termini on
oligosaccharides, with preference for GalNAc. Polyvalent GalNAc-
derivatized neoglycoproteins have >1000-fold enhanced binding affinity
for both lectins (Adler,P., Wood,S.J., Lee,Y.C., Lee,R.T., Petri,W.A.,Jr.
and Schnaar,R.L.,1995, J. Biol. Chem ., 270, 5164-5171). Substructural
specificity studies revealed that the 3-OH and 4-OH groups of GalNAc were
required for binding to both lectins, whereas only the E.histolytica lectin
required the 6-OH group. Whereas GalNAc binds with 4-fold lower affinity to
the E.histolytica lectin than to the mammalian hepatic lectin,
galactosamine and N-benzoyl galactosamine bind with higher affinity to the
E. histolytica lectin. Therefore, a synthetic scheme for converting
polyamine carriers to poly-N-acyl galactosamine derivatives (linked through
the galactosamine primary amino group) was developed to test whether such
ligands would bind the E.histolytica lectin with high specificity and high
affinity. Contrary to expectations, polyvalent derivatives including
GalN6lys5, GalN4desmosine, GalN4StarburstTMdendrimer, and
GalN8StarburstTMdendrimer demonstrated highly enhanced binding to the
mammalian hepatic lectin but little or no enhancement of binding to the
E.histolytica lectin. We propose that the mammalian hepatic lectin binds
with greatest affinity to GalNAc "miniclusters," which mimic branched
termini of N-linked oligosaccharides, whereas the E.histolytica lectin
binds most effectively to "maxiclusters," which may mimic more widely
spaced GalNAc residues on intestinal mucins.
相似文献
26.
Folkertsma RT Rattunde HF Chandra S Raju GS Hash CT 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(3):399-409
The Guinea-race of sorghum [Sorghum bicolor (L.) Moench] is a predominantly inbreeding, diploid cereal crop. It originated from West Africa and appears to have spread throughout Africa and South Asia, where it is now the dominant sorghum race, via ancient trade routes. To elucidate the genetic diversity and differentiation among Guinea-race sorghum landraces, we selected 100 accessions from the ICRISAT sorghum Guinea-race Core Collection and genotyped these using 21 simple sequence repeat (SSR) markers. The 21 SSR markers revealed a total of 123 alleles with an average Dice similarity coefficient of 0.37 across 4,950 pairs of accessions, with nearly 50% of the alleles being rare among the accessions analysed. Stratification of the accessions into 11 countries and five eco-regional groups confirmed earlier reports on the spread of Guinea-race sorghum across Africa and South Asia: most of the variation was found among the accessions from semi-arid and Sahelian Africa and the least among accessions from South Asia. In addition, accessions from South Asia most closely resembled those from southern and eastern Africa, supporting earlier suggestions that sorghum germplasm might have reached South Asia via ancient trade routes along the Arabian Sea coasts of eastern Africa, Arabia and South Asia. Stratification of the accessions according to their Snowden classification indicated clear genetic variation between margeritiferum, conspicuum and Roxburghii accessions, whereas the gambicum and guineënse accessions were genetically similar. The implications of these findings for sorghum Guinea-race plant breeding activities are discussed. 相似文献
27.
28.
P. Ramu B. Kassahun S. Senthilvel C. Ashok Kumar B. Jayashree R. T. Folkertsma L. Ananda Reddy M. S. Kuruvinashetti B. I. G. Haussmann C. T. Hash 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(7):1193-1204
The sequencing and detailed comparative functional analysis of genomes of a number of select botanical models open new doors
into comparative genomics among the angiosperms, with potential benefits for improvement of many orphan crops that feed large
populations. In this study, a set of simple sequence repeat (SSR) markers was developed by mining the expressed sequence tag
(EST) database of sorghum. Among the SSR-containing sequences, only those sharing considerable homology with rice genomic
sequences across the lengths of the 12 rice chromosomes were selected. Thus, 600 SSR-containing sorghum EST sequences (50
homologous sequences on each of the 12 rice chromosomes) were selected, with the intention of providing coverage for corresponding
homologous regions of the sorghum genome. Primer pairs were designed and polymorphism detection ability was assessed using
parental pairs of two existing sorghum mapping populations. About 28% of these new markers detected polymorphism in this 4-entry
panel. A subset of 55 polymorphic EST-derived SSR markers were mapped onto the existing skeleton map of a recombinant inbred
population derived from cross N13 × E 36-1, which is segregating for Striga resistance and the stay-green component of terminal drought tolerance. These new EST-derived SSR markers mapped across all
10 sorghum linkage groups, mostly to regions expected based on prior knowledge of rice–sorghum synteny. The ESTs from which
these markers were derived were then mapped in silico onto the aligned sorghum genome sequence, and 88% of the best hits corresponded to linkage-based positions. This study demonstrates
the utility of comparative genomic information in targeted development of markers to fill gaps in linkage maps of related
crop species for which sufficient genomic tools are not available. 相似文献
29.
Daniel RomeroMujalli Markus Rochow Sandra Kahl Sofia Paraskevopoulou Remco Folkertsma Florian Jeltsch Ralph Tiedemann 《Ecology and evolution》2021,11(11):6341
Populations adapt to novel environmental conditions by genetic changes or phenotypic plasticity. Plastic responses are generally faster and can buffer fitness losses under variable conditions. Plasticity is typically modeled as random noise and linear reaction norms that assume simple one‐to‐one genotype–phenotype maps and no limits to the phenotypic response. Most studies on plasticity have focused on its effect on population viability. However, it is not clear, whether the advantage of plasticity depends solely on environmental fluctuations or also on the genetic and demographic properties (life histories) of populations. Here we present an individual‐based model and study the relative importance of adaptive and nonadaptive plasticity for populations of sexual species with different life histories experiencing directional stochastic climate change. Environmental fluctuations were simulated using differentially autocorrelated climatic stochasticity or noise color, and scenarios of directional climate change. Nonadaptive plasticity was simulated as a random environmental effect on trait development, while adaptive plasticity as a linear, saturating, or sinusoidal reaction norm. The last two imposed limits to the plastic response and emphasized flexible interactions of the genotype with the environment. Interestingly, this assumption led to (a) smaller phenotypic than genotypic variance in the population (many‐to‐one genotype–phenotype map) and the coexistence of polymorphisms, and (b) the maintenance of higher genetic variation—compared to linear reaction norms and genetic determinism—even when the population was exposed to a constant environment for several generations. Limits to plasticity led to genetic accommodation, when costs were negligible, and to the appearance of cryptic variation when limits were exceeded. We found that adaptive plasticity promoted population persistence under red environmental noise and was particularly important for life histories with low fecundity. Populations producing more offspring could cope with environmental fluctuations solely by genetic changes or random plasticity, unless environmental change was too fast. 相似文献
30.