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1.
W. Powell P. D. S. Caligari J. S. Swanston J. L. Jinks 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,71(3):461-466
Summary Random inbred lines produced by doubled haploidy (DH) and single seed descent (SSD) have been used to investigate the genetics of -glucan (gum) content in barley (Hordeum vulgare). Genetical analyses indicated that gum content is controlled by a simple additive genetic system. Significant negative genetic correlations were observed between -glucan content, thousand grain weight and height in the DH samples. These correlations were much reduced in the SSD samples and would suggest linkage of the genes controlling these characters. The presence of repulsion linkages could be exploited in a barley breeding programme by producing F1 derived DH to generate recombinants with high thousand grain weight and low -glucan content. Genetical parameters estimated from DH and F3 samples have successfully been used to predict the number of inbred lines transgressing the parental range for -glucan content and bivariate combinations involving -glucan. 相似文献
2.
Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study 总被引:3,自引:1,他引:2 下载免费PDF全文
The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions. 相似文献
3.
Classification and nomenclature of all human homeobox genes 总被引:2,自引:0,他引:2
Background
The homeobox genes are a large and diverse group of genes, many of which play important roles in the embryonic development of animals. Increasingly, homeobox genes are being compared between genomes in an attempt to understand the evolution of animal development. Despite their importance, the full diversity of human homeobox genes has not previously been described.Results
We have identified all homeobox genes and pseudogenes in the euchromatic regions of the human genome, finding many unannotated, incorrectly annotated, unnamed, misnamed or misclassified genes and pseudogenes. We describe 300 human homeobox loci, which we divide into 235 probable functional genes and 65 probable pseudogenes. These totals include 3 genes with partial homeoboxes and 13 pseudogenes that lack homeoboxes but are clearly derived from homeobox genes. These figures exclude the repetitive DUX1 to DUX5 homeobox sequences of which we identified 35 probable pseudogenes, with many more expected in heterochromatic regions. Nomenclature is established for approximately 40 formerly unnamed loci, reflecting their evolutionary relationships to other loci in human and other species, and nomenclature revisions are proposed for around 30 other loci. We use a classification that recognizes 11 homeobox gene 'classes' subdivided into 102 homeobox gene 'families'.Conclusion
We have conducted a comprehensive survey of homeobox genes and pseudogenes in the human genome, described many new loci, and revised the classification and nomenclature of homeobox genes. The classification scheme may be widely applicable to homeobox genes in other animal genomes and will facilitate comparative genomics of this important gene superclass. 相似文献4.
Molina-Cano JL Simiand JP Sopena A Pérez-Vendrell AM Dorsch S Rubiales D Swanston JS Jahoor A 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(7):1278-1287
Mildew-resistant mutants were induced with sodium azide in three North American malting barley cultivars, two in the six-rowed Ursula (URS1 and URS2), one in the six-rowed Gertrud (GER1), and one in the two-rowed Prudentia (PRU1). Two of the mutants, URS1 and PRU1, showed complete resistance and were shown to have two new alleles at the mlo locus; these were designated, respectively, mlo31 and mlo32. Mutant URS2, showing partial resistance, was inherited as a dominant gene, but was not an allele at the Mla locus. The mean yield of each mutant was higher than that of its parental line, but yield levels varied across environments, although this was independent of the severity of the mildew attack. Other reasons, for example, the severity of the necrotic lesions in the mutants, may account for yield variations. The malting quality of the GER1 mutant proved similar to that of Gertrud, but both URS1 and URS2 showed lower malt extract than Ursula. This lower extract might be due to the smaller grain size of the mutants that could, in turn, result from necrotic lesions in the leaves, as implied by the effects on grain yield.Communicated by G. Wenzel 相似文献
5.
Characterization of terminal NeuNAcalpha2-3Galbeta1-4GlcNAc sequence in lipooligosaccharides of Neisseria meningitidis 总被引:1,自引:0,他引:1
Group B and C Neisseria meningitidis are the major cause of meningococcal
disease in the United States and in Europe. N . meningitidis
lipooligosaccharide (LOS), a major surface antigen, can be divided into 12
immunotypes of which L1 through L8 were found among Group B and C
organisms. Groups B and C but not Group A may sialylate their LOSs with
N-acetylneuraminic acid (NeuNAc) at the nonreducing end because they
synthesize CMP-NeuNAc. Using sialic acid-galactose binding lectins as
probes in an ELISA format, six of the eight LOS immunotypes (L2, L3, L4,
L5, L7, and L8) in Groups B and C bound specifically to Maackia amurensis
leukoagglutinin (MAL), which recognizes NeuNAcalpha2- 3Galbeta1-4GlcNAc/Glc
sequence, but not to Sambucus nigra agglutinin, which binds
NeuNAcalpha2-6Gal sequence. The combination of SDS-PAGE and MAL-blot
analyses revealed that these six LOSs contained only the
NeuNAcalpha2-3Galbeta1-4GlcNAc trisaccharide sequence in their 4.1 kDa LOS
components, which have a common terminal lacto-N-neotetraose (LNnT,
Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structure when nonsialylated as shown
by previous studies. The LOS-lectin binding was abolished when the LOSs
were treated with Newcastle disease viral neuraminidase which cleaves
alpha2-->3 linked sialic acid. Methylation analysis of a representative
LOS (L2) confirmed that NeuNAc is 2-->3 linked to Gal. Thus, these LOSs
structurally mimic certain glycolipids, i.e., paragloboside (LNnT-ceramide)
and sialylparagloboside and some glycoproteins in having LNnT and
N-acetyllactosamine sequences, respectively, with or without alpha2-->3
linked NeuNAc. The molecular mimicry of the LOSs may play a role in the
pathogenesis of N.meningitidis by assisting the organism to evade host
immune defenses in man.
相似文献
6.
Mixtures of genotypes are the norm in natural and seminatural ecosystems and subsistence agriculture but have been replaced by pure genotypes in modern agriculture to maximise profitability in high-input systems. However, crop function with respect to the stability of yield and quality in particular tends to be lost in this process. Diversity can be reintroduced into cropping systems as a trait not only to confer stability but also to exploit synergies between component genotypes, compensating for potential performance losses against the best performing genotype in any given season or location. Quality need not be compromised, and research has demonstrated practical development and deployment approaches, which challenge the assumed benefits of current approaches to agronomy and achieve enhanced crop function. 相似文献
7.
Susan E. Crow Christopher W. Swanston Kate Lajtha J. Renée Brooks Heath Keirstead 《Biogeochemistry》2007,85(1):69-90
Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent
approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as
sodium polytungstate (SPT). Soil density fractions are often interpreted as organic matter pools with different carbon (C)
turnover times, ranging from years to decades or centuries, and with different functional roles for C and nutrient dynamics.
In this paper, we discuss the development and mechanistic basis of common density-based methods for dividing soil into distinct
organic matter fractions. Further, we directly address the potential effects of dispersing soil in a high density salt solution
on the recovered fractions and implications for data interpretation. Soil collected from forested sites at H. J. Andrews Experimental
Forest, Oregon and Bousson Experimental Forest, Pennsylvania was separated into light and heavy fractions by floatation in
a 1.6 g cm−3 solution of SPT. Mass balance calculations revealed that between 17% and 26% of the original bulk soil C and N content was
mobilized and subsequently discarded during density fractionation for both soils. In some cases, the light isotope was preferentially
mobilized during density fractionation. During a year-long incubation, mathematically recombined density fractions respired
∼40% less than the bulk soil at both sites and light fraction (LF) did not always decompose more than the heavy fraction (HF).
Residual amounts of tungsten (W) present even in well-rinsed fractions were enough to reduce microbial respiration by 27%
compared to the control in a 90-day incubation of Oa material. However, residual W was nearly eliminated by repeated leaching over the year-long incubation, and is not likely
the primary cause of the difference in respiration between summed fractions and bulk soil. Light fraction at Bousson, a deciduous
site developed on Alfisols, had a radiocarbon-based mean residence time (MRT) of 2.7 or 89 years, depending on the interpretation
of the radiocarbon model, while HF was 317 years. In contrast, both density fractions from H. J. Andrews, a coniferous site
developed on andic soils, had approximately the same MRT (117 years and 93 years for LF and HF). At H. J. Andrews the organic
matter lost during density separation had a short MRT (19 years) and can account for the difference in respired CO2 between the summed fractions and the bulk soil. Recognition and consideration of the effects of the density separation procedure
on the recovered fractions will help prevent misinterpretation and deepen our understanding of the specific role of the recovered
organic matter fractions in the ecological context of the soil studied. 相似文献
8.
Stuart Swanston J. Thomas William T.B. Powell Wayne Young George R. Lawrence Patricia E. Ramsay Luke Waugh Robbie 《Molecular breeding : new strategies in plant improvement》1999,5(2):103-109
Two barley quality characters of specific interest to whisky distillers are fermentability and production of the ethyl carbamate
precursor, epi-heterodendrin. The former is a quantitative trait, while the latter may be determined by a single Mendelian
genetic factor. Molecular markers have been used to map, to barley chromosome 5(1H), the locus responsible for epi-heterodendrin
synthesis and the inheritance of this character and a closely linked microsatellite have been followed through the pedigrees
of several contemporary cultivars. Six loci, which affected fermentability in random inbred lines from a barley cross, have
been mapped to chromosomes 2(2H), 3(3H) and 7(5H). This would permit the use of molecular markers in a breeding programme,
to select barleys best suited for distilling. In addition, one of the loci related to fermentability mapped to an area of
the genome indicated, by a previous study, to affect the activity of β-amylase, a character likely to influence fermentability.
Molecular markers may, therefore, be powerful tools in exploring the contribution and detecting the mode of action of the
genetical components influencing malt whisky distilling.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Tom Lenaerts Jesper Ferkinghoff-Borg Francois Stricher Luis Serrano Joost WH Schymkowitz Frederic Rousseau 《BMC structural biology》2008,8(1):43
Background
Efficient communication between distant sites within a protein is essential for cooperative biological response. Although often associated with large allosteric movements, more subtle changes in protein dynamics can also induce long-range correlations. However, an appropriate formalism that directly relates protein structural dynamics to information exchange between functional sites is still lacking. 相似文献10.
Michael CW Chan Renee WY Chan Wendy CL Yu Carol CC Ho WH Chui CK Lo Kit M Yuen Yi Guan John M Nicholls JS Malik Peiris 《Respiratory research》2009,10(1):102