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41.
Mechelli A Humphreys GW Mayall K Olson A Price CJ 《Proceedings. Biological sciences / The Royal Society》2000,267(1455):1909-1913
Previous studies have shown differential responses in the fusiform and lingual gyri during reading and suggested that the former is engaged in processing local features of visual stimuli and the latter is engaged in global shape processing. We used positron emission tomography in order to investigate how these regions are modulated by two common variables in reading: word length (three, six and nine letters) and perceptive similarity to the background (high and low contrast). Increasing both word length and visual contrast had a positive monotonic effect on activation in the bilateral fusiform. However, in the lingual gyrus, activation increased with increasing word length but decreased with increasing contrast. On the basis of previous studies, we suggest that (i) increasing word length increases the demands on both local feature and global shape processing, but (ii) increasing visual contrast increases the demands on local feature processing while decreasing the demands on global shape processing. 相似文献
42.
韩世辉 《中国科学C辑(英文版)》2003,46(2):113-126
Palmer and Rock proposed that uniform connectedness (UC) occurs prior to classical Gestalt factors to define the primitive units for visual perception. Han, Humphreys and Chen, however, found that grouping by proximity can take place as quickly as that based on UC in a letter discrimination task. The present study employed a letter detection task to examine the relationship between UC and proximity grouping in 3 experiments. We showed that reaction times to targets defined by proximity or UC were equally fast when one or two global objects were presented in the visual field. However, as the number of global objects was increased, responses were faster to targets defined by UC than to targets defined by proximity. In addition, the advantage of UC over proximity was not affected by the space between global objects. The results suggest that UC was more effective than proximity in forming perceptual units under multiple object conditions. Possible reasons for this finding are discussed. 相似文献
43.
We examined gazelle peripheral blood leucocytes using the α-Naphthyl acetate esterase (ANAE) staining technique (pH 5.8). Our purpose was to determine the percentage of ANAE positive lymphocytes. The proportion of ANAE positive T-lymphocytes was 72%. T-lymphocytes showed an ANAE positive reaction, but eosinophilic granulocytes and monocytes also showed a positive reaction. By contrast, no reaction was detected in B-lymphocytes, neutrophil granulocytes or platelets. The reaction observed in T-lymphocytes was a red-brown coloration, usually 1–2 granules, but enough granules to fill the cytoplasm were detected rarely. As a result of ANAE enzyme staining, we concluded that the staining technique can be used as a cytochemical marker for gazelle T-lymphocytes. 相似文献
44.
45.
Replication Protein A (RPA) is a single-stranded DNA-binding protein essential for DNA replication, repair, recombination and cell-cycle regulation. A human homolog of the RPA2 subunit, called RPA4, was previously identified and shown to be expressed in colon mucosal and placental cells; however, the function of RPA4 was not determined. To examine the function of RPA4 in human cells, we carried out knockdown and replacement studies to determine whether RPA4 can substitute for RPA2 in the cell. Unlike RPA2, exogenous RPA4 expression did not support chromosomal DNA replication and lead to cell-cycle arrest in G2/M. In addition, RPA4 localized to sites of DNA repair and reduced γ-H2AX caused by RPA2 depletion. These studies suggest that RPA4 cannot support cell proliferation but can support processes that maintain the genomic integrity of the cell. 相似文献
46.
William J. Kenyon Sue Humphreys Mark Roberts Michael P. Spector 《Antonie van Leeuwenhoek》2010,98(1):51-63
Carbon-energy source (C)-starved cells of Salmonella enterica serovar Typhimurium (S. Typhimurium) are remarkably more resistant to stress than actively growing ones. Carbon-starved S. Typhimurium is capable of withstanding extended periods of starvation and assault from a number of different stresses that
rapidly kill growing cells. These unique properties of the C-starved cell are the direct result of a series of genetic and
physiological adaptations referred to as the starvation-stress response (SSR). Previous work established that the SSR of S. Typhimurium is partially regulated by the extracytoplasmic function sigma factor σE. As part of an effort to identify σE-regulated SSR genes, we investigated surA and fkpA, encoding two different classes of peptidyl-prolyl isomerase that function in folding cell envelope proteins. Both surA and fkpA are members of the heat-shock-inducible σE regulon of Escherichia coli. Although both genes are expressed in C-starved Salmonella cells, evidence indicates that surA and fkpA are not C-starvation-inducible. Furthermore, their expression during C-starvation does not appear to be σE-dependent. Nonetheless, surA and fkpA proved to be important, to differing degrees, for long-term C-starvation survival and for the cross-resistance of C-starved
cells to high temperature, acidic pH, and the antimicrobial peptide polymyxin B, but neither were required for cross-resistance
to oxidative stress. These results point to fundamental differences between heat-shock-inducible and C-starvation-inducible
genes regulated by σE and suggest that genes other than surA and fkpA are involved in the σE-regulated branch of the SSR in Salmonella. 相似文献
47.
Colin W. Hiebert Julian B. Thomas Brent D. McCallum D. Gavin Humphreys Ronald M. DePauw Matthew J. Hayden Rohit Mago Wendelin Schnippenkoetter Wolfgang Spielmeyer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,121(6):1083-1091
Adult plant resistance (APR) to leaf rust and stripe rust derived from the wheat (Triticum aestivum L.) line PI250413 was previously identified in RL6077 (=Thatcher*6/PI250413). The leaf rust resistance gene in RL6077 is
phenotypically similar to Lr34 which is located on chromosome 7D. It was previously hypothesized that the gene in RL6077 could be Lr34 translocated to another chromosome. Hybrids between RL6077 and Thatcher and between RL6077 and 7DS and 7DL ditelocentric
stocks were examined for first meiotic metaphase pairing. RL6077 formed chain quadrivalents and trivalents relative to Thatcher
and Chinese Spring; however both 7D telocentrics paired only as heteromorphic bivalents and never with the multivalents. Thus,
chromosome 7D is not involved in any translocation carried by RL6077. A genome-wide scan of SSR markers detected an introgression
from chromosome 4D of PI250413 transferred to RL6077 through five cycles of backcrossing to Thatcher. Haplotype analysis of
lines from crosses of Thatcher × RL6077 and RL6058 (Thatcher*6/PI58548) × RL6077 showed highly significant associations between
introgressed markers (including SSR marker cfd71) and leaf rust resistance. In a separate RL6077-derived population, APR to stripe rust was also tightly linked with cfd71 on chromosome 4DL. An allele survey of linked SSR markers cfd71 and cfd23 on a set of 247 wheat lines from diverse origins indicated that these markers can be used to select for the donor segment
in most wheat backgrounds. Comparison of RL6077 with Thatcher in field trials showed no effect of the APR gene on important
agronomic or quality traits. Since no other known Lr genes exist on chromosome 4DL, the APR gene in RL6077 has been assigned
the name Lr67. 相似文献
48.
Michael Abberton Jacqueline Batley Alison Bentley John Bryant Hongwei Cai James Cockram Antonio Costa de Oliveira Leland J. Cseke Hannes Dempewolf Ciro De Pace David Edwards Paul Gepts Andy Greenland Anthony E. Hall Robert Henry Kiyosumi Hori Glenn Thomas Howe Stephen Hughes Mike Humphreys David Lightfoot Athole Marshall Sean Mayes Henry T. Nguyen Francis C. Ogbonnaya Rodomiro Ortiz Andrew H. Paterson Roberto Tuberosa Babu Valliyodan Rajeev K. Varshney Masahiro Yano 《Plant biotechnology journal》2016,14(4):1095-1098
Agriculture is now facing the ‘perfect storm’ of climate change, increasing costs of fertilizer and rising food demands from a larger and wealthier human population. These factors point to a global food deficit unless the efficiency and resilience of crop production is increased. The intensification of agriculture has focused on improving production under optimized conditions, with significant agronomic inputs. Furthermore, the intensive cultivation of a limited number of crops has drastically narrowed the number of plant species humans rely on. A new agricultural paradigm is required, reducing dependence on high inputs and increasing crop diversity, yield stability and environmental resilience. Genomics offers unprecedented opportunities to increase crop yield, quality and stability of production through advanced breeding strategies, enhancing the resilience of major crops to climate variability, and increasing the productivity and range of minor crops to diversify the food supply. Here we review the state of the art of genomic‐assisted breeding for the most important staples that feed the world, and how to use and adapt such genomic tools to accelerate development of both major and minor crops with desired traits that enhance adaptation to, or mitigate the effects of climate change. 相似文献
49.
John F. Kennedy John D. Humphreys S. Alan Barker Roderick N. Greenshields 《Enzyme and microbial technology》1980,2(3):209-216
Various strains of Acetobacter species have been immobilized on hydrous titanium(IV) oxide or hydrous titanium(IV) chelated cellulose and used in the continuous conversion of a dilute aqueous alcoholic solution (in the form of‘charging wort’) into acetic acid (in the form of vinegar) in tower fermenter-type reactors. A strain of Acetobacter species producing extracellular polysaccharide aggregated in the presence of hydrous titanium(IV) oxide thereby enabling higher medium flow rates and an increased acetic acid output to be achieved. A strain of Acetobacter species not producing polysaccharide showed no effect with hydrous titanium(IV) oxide but did produce more acetic acid when a titanium(IV)-cellulose chelate was added to the fermentation, although aggregation was not observed. Mechanisms, which appear to conform to established results, are proposed for the aggregation of both strains of bacteria. Apparently, these water-insoluble titanium compounds can interact with the bacterial cells, increasing their density and thus making them more resistant to ‘wash out’ by increasing the rate at which they sediment in the fermenter. This enables a greater cell mass per unit volume to be achieved which in turn leads to an increase in conversion rate in the reactor. 相似文献
50.
Selena Humphreys Chris S. Elphick Carina Gjerdrum Margaret Rubega 《Journal of Field Ornithology》2007,78(2):152-158
ABSTRACT. Saltmarsh Sharp-tailed Sparrows ( Ammodramus caudacutus ) build ground nests, often with a closely-woven dome, in marshes that frequently flood during high tides. To test the hypothesis that domed nests help reduce the loss of eggs and chicks due to flooding or predation, we examined the characteristics and fate of 102 nests at sites along the coast of Connecticut. To test whether nest structure was tailored to suit microhabitat conditions, we also measured vegetation characteristics around nests. Finally, we conducted artificial nest-flooding experiments to determine whether removal of domes reduced egg retention during flooding. We found no significant effects of nest structure on breeding success or failure, and few significant correlations between nest structure and microhabitat. The height of nests above the ground, however, increased with vegetation height, supporting the hypothesis that nest construction is influenced by flooding, but not supporting the hypothesis that predation risk is important. Dome removal experiments showed that domes have a highly significant effect on the retention of eggs during flooding, suggesting that domes help eggs survive the regular tidal flooding of marshes. 相似文献