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1.
beta, a novel repetitive DNA element associated with tRNA genes in the pathogenic yeast Candida albicans 总被引:2,自引:0,他引:2
We have identified a novel 399 bp repetitive DNA element (which we designate beta ) 9 bp upstream of a seryl-tRNACAG gene in the genome of Candida albicans . There are two copies of the seryl-tRNACAG gene, one on each homologue of chromosome VI, and the beta element is found upstream of one copy of the gene in C. albicans strain 2005E. The beta element is not present upstream of either copy of the seryl-tRNACAG gene in eight other laboratory strains of C. albicans tested, but was detected in this location in several fresh clinical isolates. Southern blot analysis indicated that there are approximately eight copies of the beta element per diploid C. albicans genome and that it is a mobile element, being present on at least two different chromosomes. Three unique genomic DNA clones containing the beta element were isolated from strain 2005E; in each case, a different tRNA gene was found immediately adjacent to the beta element. Three new tRNA genes from C. albicans have thus been identified: tRNAAsp , tRNAAla and tRNAIle . The beta element shows no significant sequence homology to other known prokaryotic or eukaryotic repetitive elements, although an 8 bp repeat at the 3' end of the element is identical to that of the Ty3 retrotransposable element of Saccharomyces cerevisiae . We propose that the beta element is a solo long terminal repeat (LTR) sequence of a Ty3/gypsy-like transposable element in C. albicans that is closely associated with tRNA genes. 相似文献
2.
Although seedling herbivory is an important selective filter in many plant communities, how and why seedlings are selected
is poorly understood. Here, we examined the putative role of herbivore olfaction in dictating seedling selection. Using a
Y-tube olfactometer we compared snail (Helix aspersa) preference for pellets derived from 14-day-old macerated seedlings of nine European grassland (‘Test’) species against standard
(‘Control’) pellets derived from lettuce. Snail movement towards ‘Test’ pellets was strongly correlated with seedling acceptability
(Pearson’s r
2 = 0.86, P > 0.01) and where snails exhibited a positive choice for the ‘Test’ species, the choice was made more quickly for highly
acceptable species (r
2 = 0.86, P > 0.01). In elucidating a link between seedling acceptability and olfactory response to macerated seedlings, our study suggests
that even from an early ontogenetic stage plant selection by snails may be governed by olfactory cues. This finding highlights
the need for research on the role of plant volatiles in plant–herbivore interactions to consider more fully interactions operating
at the seedling stage. 相似文献
3.
P.Mick Richardson 《Biochemical Systematics and Ecology》1982,10(2):197-199
Published results of the distribution of anthocyanins in the Sterculiaceae have been re-interpreted on the basis of the phylogenetic status of the compounds present. A flavonoid score system was less useful than a cladistic interpretation based on Hennigian arguments. 相似文献
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6.
Ribosomal association of the yeast SAL4 (SUP45) gene product: implications for its role in translation fidelity and termination 总被引:8,自引:0,他引:8
Ian Stansfield Christopher M. Grant † Akhmaloka Mick F. Tuite 《Molecular microbiology》1992,6(23):3469-3478
The SAL4 gene of the yeast Saccharomyces cerevisiae encodes a novel translation factor (Sal4p) involved in maintaining translational fidelity. Using a polyclonal antibody raised against a Sal4p-beta-galactosidase fusion protein, Sal4p was shown to be almost exclusively associated with the ribosomal fraction. Even when the ribosomes were treated with 0.8 M KCl, only low levels of Sal4p were detected in the post-ribosomal supernatant, suggesting a very strong affinity between Sal4p and the ribosome. Analysis of the distribution of Sal4p in the ribosomal population revealed that it was principally associated with 40S subunits, monosomes and polysomes. Incubation in high salt concentrations (0.8 M KCl) suggested that the affinity of Sal4p for the 40S subunit was lower than that for monosomes or polysomes. The Sal4p:ribosome association was only maintained when ribosomes were prepared in the presence of the translation elongation inhibitor cycloheximide; in uninhibited cells much lower levels of Sal4p were detectable in the 'run-off' polysomes. In view of these data, and given the stoichiometry of Sal4p to individual ribosomal proteins (estimated at less than 1:20), we suggest that Sal4p plays an ancillary role in translation termination. 相似文献
7.
Eric M. Lind Elizabeth Borer Eric Seabloom Peter Adler Jonathan D. Bakker Dana M. Blumenthal Mick Crawley Kendi Davies Jennifer Firn Daniel S. Gruner W. Stanley Harpole Yann Hautier Helmut Hillebrand Johannes Knops Brett Melbourne Brent Mortensen Anita C. Risch Martin Schuetz Carly Stevens Peter D. Wragg 《Ecology letters》2013,16(4):513-521
Plant growth can be limited by resource acquisition and defence against consumers, leading to contrasting trade‐off possibilities. The competition‐defence hypothesis posits a trade‐off between competitive ability and defence against enemies (e.g. herbivores and pathogens). The growth‐defence hypothesis suggests that strong competitors for nutrients are also defended against enemies, at a cost to growth rate. We tested these hypotheses using observations of 706 plant populations of over 500 species before and following identical fertilisation and fencing treatments at 39 grassland sites worldwide. Strong positive covariance in species responses to both treatments provided support for a growth‐defence trade‐off: populations that increased with the removal of nutrient limitation (poor competitors) also increased following removal of consumers. This result held globally across 4 years within plant life‐history groups and within the majority of individual sites. Thus, a growth‐defence trade‐off appears to be the norm, and mechanisms maintaining grassland biodiversity may operate within this constraint. 相似文献
8.
The planthopper genus Neodurium Fennah is reviewed and Neodurium
fennahi Chang & Chen, sp. n. (Hemiptera: Fulgoromorpha: Issidae) from China (Yunnan), is described and illustrated. A checklist of the species of Neodurium is given and a key provided for their separation. The female genitalia of Neodurium species are described for the first time. 相似文献
9.
Joshua D. Campbell Gang Liu Lingqi Luo Ji Xiao Joseph Gerrein Brenda Juan-Guardela John Tedrow Yuriy O. Alekseyev Ivana V. Yang Mick Correll Mark Geraci John Quackenbush Frank Sciurba David A. Schwartz Naftali Kaminski W. Evan Johnson Stefano Monti Avrum Spira Jennifer Beane Marc E. Lenburg 《RNA (New York, N.Y.)》2015,21(2):164-171
10.
Oxidative stress conditions increase the frequency of de novo formation of the yeast [PSI+] prion 下载免费PDF全文
Victoria A. Doronina Gemma L. Staniforth Shaun H. Speldewinde Mick F. Tuite Chris M. Grant 《Molecular microbiology》2015,96(1):163-174
Prions are self‐perpetuating amyloid protein aggregates which underlie various neurodegenerative diseases in mammals and heritable traits in yeast. The molecular basis of how yeast and mammalian prions form spontaneously into infectious amyloid‐like structures is poorly understood. We have explored the hypothesis that oxidative stress is a general trigger for prion formation using the yeast [PSI+] prion, which is the altered conformation of the Sup35 translation termination factor. We show that the frequency of [PSI+] prion formation is elevated under conditions of oxidative stress and in mutants lacking key antioxidants. We detect increased oxidation of Sup35 methionine residues in antioxidant mutants and show that overexpression of methionine sulphoxide reductase abrogates both the oxidation of Sup35 and its conversion to the [PSI+] prion. [PSI+] prion formation is particularly elevated in a mutant lacking the Sod1 Cu,Zn‐superoxide dismutase. We have used fluorescence microscopy to show that the de novo appearance of [PSI+] is both rapid and increased in frequency in this mutant. Finally, electron microscopy analysis of native Sup35 reveals that similar fibrillar structures are formed in both the wild‐type and antioxidant mutants. Together, our data indicate that oxidative stress is a general trigger of [PSI+] formation, which can be alleviated by antioxidant defenses. 相似文献