4,480 research outputs found
Correspondence regarding Horace Kephart collection
No full textThis 1973 correspondence, between Congressman Roy A. Taylor, Ronald Walker, Lawrence C. Hadley, discusses the transfer of Horace Kephart collection from the library of Great Smoky Mountains National Park to Western Carolina University. Horace Kephart (1862-1931) was a noted naturalist, woodsman, journalist, and author and promoter of the Great Smoky Mountains National Park
Proline transport and stress tolerance of ammonia-insensitive mutants of the PUT4-encoded proline-specific permease in yeast
No full textThe imino amino acid, proline, has roles in both cellular nutrition and response to stress. Proline uptake in Saccharomyces cerevisiae is largely mediated by a high affinity, specific permease, Put4p, and a low affinity general amino acid permease, Gap1p. Both are subject to nitrogen catabolite repression (NCR) and nitrogen catabolite inactivation (NCI). In order for proline to be fully exploited, its transport must be derepressed, as occurs upon depletion of preferred nitrogen sources, and molecular oxygen must be present to allow the first step of catabolism via proline oxidase. This study focuses on the isolation of variants of Put4p, which are insensitive to repression by a preferred nitrogen source (ammonia) and their subsequent effect on proline transport and stress tolerance. Specific amino acid residues in the carboxy-terminal region of Put4p were targeted by site-directed mutagenesis. Substitution at Serine(605), a potential phosphorylation target, led to the amelioration of ammonia-induced down-regulation of Put4p. When combined with a promoter mutation (-160), the S(605)A mutation resulted in increased proline uptake and accumulation. This increase in proline accumulation was associated with increased cell viability in conditions of high temperature and osmotic stress raising possible benefits in industrial fermentation applications.Kate Poole, Michelle E. Walker, Tristan Warren, Jennie Gardner, Colin McBryde, Miguel de Barros Lopes and Vladimir Jiranekhttp://www.ncbi.nlm.nih.gov/pubmed/2011860
"I don’t really like tedious, monotonous work": working-class young women, service sector employment and social mobility in contemporary Russia
No full textThis article contributes a global perspective to the emerging literature on girlhood in western contexts by examining the changing shape of transitions to adulthood amongst working-class young women in St. Petersburg, Russia. As in many western countries, new forms of service sector employment and an increasingly accessible higher education system appear to offer young women new prospects for social mobility. In contrast to the increasingly impoverished and denigrated traditional pathways into work, the young women in the study derive significant value from these new opportunities, constructing narratives of self-actualisation and approximating notions of respectable femininity. Nevertheless, actual social mobility is elusive, as familiar patterns of classed and gendered stratification limit their prospects. Despite its specificity, the case thus further illustrates the limited nature of the transformations available to young women through the new forms of education and work characteristic of global neoliberal contexts
Editorial: Darwin and Kew anniversaries
No full textCharles Darwin was born 200 years ago this year and his monumental work On the origin of species, laying the foundation of modern evolutionary theory driven by natural selection, was published 150 years ago. Earlier in 1759, The Royal Botanic Gardens, Kew, were established. This year's special issue of Bradleya celebrates these anniversaries with the principal theme of evolution of succulents. Bradleya 27 includes the following articles:
•Editorial: Darwin and Kew anniversaries by Colin Walker
•Charles Darwin's succulent plants by Gordon D Rowley
•Living under temporarily arid conditions - succulence as an adaptive strategy by Urs Eggli and Reto Nyfeller
•Evolution of cacti driven by genetic drift not selection bt Root Gorelick
•Evolution of characters in the Opuntioideae by M Patrick Griffith
•Insect flower visitors and pollinators of cacti from the southwest USA by Zlatko Janeba
•On the evolution of nectaries in the Aizoaceae by H.E.K Hatrmann and I.M.Niesler
•Kew and its collections of succulent plants by David Hunt and Nigel Taylor
•The composite structure of cactus spines by Urs Schlegel
•Stapelia hirsuta L. and early portrait by H.A.Jonkers
•Rectification of a mistake by G.W.Reynolds on a Malagasy Aloe (Asphodelaceae) and description of a new species by Jean-Bernard Castillon
•The identity of Sansevieria arborescens (Ruscaceae), with an amplified description and description of a new species by Leonard E.Newton
•Priority of Aloe teissieri over Aloe andohahelensis by Susan Carter and John Lavranos
•Ceropegia thailandica (Asclepiadoideae-Ceropegieae), a spectacular new Thai species by Ulrich Meve
•Aloe arborescens Miller (Asphodelaceae) is spreading in Portugal by Gideon F.Smith and Estrela Figueired
Application of the reuseable, KanMX selectable marker to industrial yeast: construction and evaluation of heterothallic wine strains of Saccharomyces cerevisiae, possessing minimal foreign DNA sequences
No full textThe characterisation of wine yeasts and the complex metabolic processes influencing wine fermentation and the quality of wine might best be achieved by exploiting the standard classical and recombinant genetic techniques which have been successfully used with laboratory strains. However, application of these techniques to industrial strains has been restricted because such strains are typically prototrophic and often polyploid. To overcome this problem, we have identified commercial wine strains with good mating and sporulation properties from which heterothallic derivatives were constructed by disruption of the HO gene. Consequently, these haploids are amenable to genetic analysis, whilst retaining desirable wine-making properties. The approach used was an adaptation of a previously published gene disruption procedure for laboratory yeast and is based on the acquisition of geneticin resistance from a removable KanMX marker. The present work is the first report of the application of a construct of this type to the disruption of the HO gene in wine yeasts that are in common commercial use. Most of the 4.9-kb disruption construct was successfully removed from the genome of the haploid derivative strains by loop-out of the KanMX marker through meiotic recombination. Sequencing of the HO region confirmed the reduction of foreign sequences to a 582-bp fragment comprised largely of a single direct repeat at the target gene. The removal of the active foreign gene (conferring antibiotic resistance) allows the application of other constructs based on the KanMX module without the need to resort to other selectable marker systems. Laboratory-scale fermentation trials typically showed minimal differences between the HO disruptants and the parental wine strains in terms of fermentation kinetics and formation of key metabolites.Michelle E. Walker, Jennie M. Gardner, Andrea Vystavelova, Colin McBryde, Miguel de Barros Lopes and Vladimir Jirane
Optimisation of industrial strains of Saccharomyces cerevisiae using recombinant and non-recombinant methods
No full textA. Maria Astorga, Jennie M. Gardner, Colin McBryde, Frank Schmid, Michelle E. Walker & Vladimir Jiranekhttp://cambridgemedia.com.au/Default.aspx?f=pv&ctr=Default&mid=1&pid=24&page_id=9
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CactusTalk: More dragon tree tales
No full textDragon trees (Dracaena species) are updated since the last synopsis (Walker, 2001) with three new subspecies being newly described. Dracaena draco subsp. caboverdeana is endemic to the Cape Verde Islands, leaving subsp. draco restricted to the Canary Islands and Madeira. Dracaena serrulata subsp. dhofarica is endemic to the Dhofar Province of Oman. Dracaena serrulata subsp. mccoyorum is endemic to Saudi Arabia, where it occurs near the summit of a single mountain and hence is assessed as being on the brink of extinction
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Contrasting cotyledons
No full textCotyledon is a small, highly diverse and complex genus in the Crassulaceae (Walker, 2022). It is particularly diverse in terms of stem and leaf form and arrangement, for which some is undoubtedly accounted for by natural selection.
Here the diversity is considered by illustrating and discussing six different plants ranging from the sprawling, low-growing herbaceous Cotyledon papillaris to the erect and shrubby C. barbeyi that can grow up to 2m tall, while the others are shrubs or shrublets intermediate to this range of growth forms. Of especial interest is the newly-described C. mckayi which has, to my knowledge, yet to appear in cultivation in the UK but is illustrated here growing in habitat in KwaZulu-Natal where it is endemic
Conibosa occidentis Walker 1858
No full textConibosa occidentis (Walker, 1858). The species is currently known from Mexico and Panama (Metcalf 1963 c, Duffels & van der Laan 1985) but the author has also identified specimens from Costa Rica (Sanborn unpublished). The Mexican specimens have been reported from Veracruz (Stål 1864).Published as part of Sanborn, Allen F., 2007, New species, new records and checklist of cicadas from Mexico (Hemiptera: Cicadomorpha: Cicadidae), pp. 1-42 in Zootaxa 1651 on page 37, DOI: 10.11646/zootaxa.1651.1.1, http://zenodo.org/record/27398
RAC Council
No full textColor photo; unmounted; undated - c mid-1970s.Back - Gil Hollamby, Anthony Honner, Colin Haines, Hugh Reimers, Richard Wilson, Lex Walker, Colin Gramp, Ray Taylor. Front - ?, ?, Bill Nankivell, ?, Director Don Williams, Brian Chatterton
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