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By sensing changes in one or few environmental factors biological systems can anticipate future changes in multiple factors over a wide range of time scales (daily to seasonal). This anticipatory behavior is important to the fitness of diverse species, and in context of the diurnal cycle it is overall typical of eukaryotes and some photoautotrophic bacteria but is yet to be observed in archaea. Here, we report the first observation of light-dark (LD)-entrained diurnal oscillatory transcriptiondoi:10.1371/journal.pone.0005485 pmid:19424498 pmcid:PMC2675056 fatcat:agxfjmheprfzpghx47no2wzdsq
more »... n up to 12% of all genes of a halophilic archaeon Halobacterium salinarum NRC-1. Significantly, the diurnally entrained transcription was observed under constant darkness after removal of the LD stimulus (free-running rhythms). The memory of diurnal entrainment was also associated with the synchronization of oxic and anoxic physiologies to the LD cycle. Our results suggest that under nutrient limited conditions halophilic archaea take advantage of the causal influence of sunlight (via temperature) on O 2 diffusivity in a closed hypersaline environment to streamline their physiology and operate oxically during nighttime and anoxically during daytime.
These results were compared with those from a previous characterization of mycosporines in terrestrial fungi at the laboratory of Dr Whitehead, which also included high-resolution MS for compound verification ...doi:10.1002/yea.1148 pmid:15484286 fatcat:eecfpfiabrccdinacqtuyiuxsa
The extracts were re-dissolved in 2 ml of 0.2% aqueous acetic acid with 6% methanol added (v/v) and analysed following Whitehead and Hedges (2002) with small changes as described below. ... Results from LC-MS and comparison of MS/MS spectra with those previously published for MAA standards (Whitehead and Hedges 2003) confirmed all MAAs identified by HPLC and identified the second fraction ...doi:10.1016/j.protis.2006.01.002 pmid:16621697 fatcat:nmcqxfru5nfzfowdezisvhlicq
The microbial loop is the conventional model by which nutrients and minerals are recycled in aquatic eco-systems. Biochemical pathways in different organisms become metabolically inter-connected such that nutrients are utilized, processed, released and re-utilized by others. The result is that unrelated individuals end up impacting each others' fitness directly through their metabolic activities. This study focused on the impact of programmed cell death (PCD) on a population's growth as well asdoi:10.1371/journal.pone.0062595 pmid:23667496 pmcid:PMC3648572 fatcat:ugzeei7jpzbs5j23ibipcos5ae
more »... its role in the exchange of carbon between two naturally co-occurring halophilic organisms. Flow cytometric, biochemical, 14 C radioisotope tracing assays, and global transcriptomic analyses show that organic algal photosynthate released by Dunalliela salina cells undergoing PCD complements the nutritional needs of other non-PCD D. salina cells. This occurs in vitro in a carbon limited environment and enhances the growth of the population. In addition, a co-occurring heterotroph Halobacterium salinarum re-mineralizes the carbon providing elemental nutrients for the mixoheterotrophic chlorophyte. The significance of this is uncertain and the archaeon can also subsist entirely on the lysate of apoptotic algae. PCD is now well established in unicellular organisms; however its ecological relevance has been difficult to decipher. In this study we found that PCD in D. salina causes the release of organic nutrients such as glycerol, which can be used by others in the population as well as a co-occurring halophilic archaeon. H. salinarum also re-mineralizes the dissolved material promoting algal growth. PCD in D. salina was the mechanism for the flow of dissolved photosynthate between unrelated organisms. Ironically, programmed death plays a central role in an organism's own population growth and in the exchange of nutrients in the microbial loop.
The quantitative role of carbon-rich compounds for bacterial carbon demand can vary with nutrient availability. This study is the first to investigate the effect of nutrient concentrations on bacterial uptake of a carbon-rich compound (glucose) along a naturally occurring nutrient gradient. Seawater was collected from varying depths at six stations across the nutrient gradient between the nutrient-poor North Pacific gyre and the nutrient-rich sub-Arctic gyre. Ambient concentrations of freedoi:10.4319/lo.2002.47.6.1676 fatcat:awavncv76ndypge3vsupafvakm
more »... se, glucose uptake, bacterial production, and nutrient concentrations were determined across the gradient. Incubations were carried out to determine the effect of nutrient additions on glucose uptake and bacterial production. Samples from the northern, nutrient-rich end of the transect had high glucose uptake rates and high bacterial production in surface waters. The northern stations also showed rapid turnover of the glucose pool. At the southern stations, glucose uptake rates, bacterial growth rates, and fractional glucose turnover were lower. At these stations, glucose uptake increased when inorganic nutrients and amino acids were added. The variations in glucose uptake indicate that microbial uptake of nitrogen-and phosphorus-poor organic material depends on the availability of nitrogen and phosphorus from other sources.
Cellular response to stress entails complex mRNA and protein abundance changes, which translate into physiological adjustments to maintain homeostasis as well as to repair and minimize damage to cellular components. We have characterized the response of the halophilic archaeon Halobacterium salinarum NRC-1 to 60 Co ionizing gamma radiation in an effort to understand the correlation between genetic information processing and physiological change. The physiological response model we havedoi:10.1038/msb4100091 pmid:16969339 pmcid:PMC1681521 fatcat:kx52lkx6xzbkfiomlseg66kul4
more »... ed is based on integrated analysis of temporal changes in global mRNA and protein abundance along with protein-DNA interactions and evolutionarily conserved functional associations. This systems view reveals cooperation among several cellular processes including DNA repair, increased protein turnover, apparent shifts in metabolism to favor nucleotide biosynthesis and an overall effort to repair oxidative damage. Further, we demonstrate the importance of time dimension while correlating mRNA and protein levels and suggest that steadystate comparisons may be misleading while assessing dynamics of genetic information processing across transcription and translation.
Microcolonial fungi, long-living modified mycelia frequently occurring on desert and pseudodesert rock surfaces, are exposed to strong ultraviolet (UV) radiation, desiccation, and nutrient scarcity. They lack ascospores; all their cells grow by mitotic cell divisions and possess a thick melanized cell wall. Colonies of several randomly selected microcolonial strains were cultured and their structure was examined by cryo-scanning and transmission electron microscopy. Extracts of nine strainsdoi:10.1139/b03-011 fatcat:2trwv2jvy5cmrne56fpdoimune
more »... analyzed by high performance liquid chromatography interfaced with mass spectrometry for the presence of mycosporines. These UV-absorbing compounds, common in spores and other survival structures, were thought to be limited to reproductive morphogenesis and unknown in growing hyphae. Mycosporines were present in eight of the strains, and mycosporine-glutaminol-glucoside (λmax = 310 nm; MH+ = 465) was the major mycosporine detected. Mycosporines present in the vegetative fungal microcolonies may be associated with the high survival potential, nonexpansive intracolonial growth, and longevity of these fungi. Intrahyphal growth and recolonization of old cells by new ones were observed in all strains investigated. Résumé : Les champignons micro-coloniaux, constitués de mycéliums longivives modifiés, se retrouvent fréquemment sur des surfaces rocheuses en milieux désertiques et pseudo-désertiques; ils sont exposés à de fortes radiations UV, au dessèchement et à la rareté des nutriments. Ils n'ont pas d'ascospore; la croissance cellulaire se fait totalement par mitose et ils possèdent une paroi cellulaire épaisse mélanisée. Les auteurs ont cultivé les colonies de plusieurs souches microcoloniales fongiques choisies au hasard, et ils en ont examiné les structures en microscopie par cryo-balayage et par transmission d'électrons. Ils ont analysé les extraits de neuf souches en chromatographie liquide de haute performance couplée avec la spectrographie de masse, pour y rechercher des mycosporines. On pensait que ces composés qui absorbent les UV, fréquents dans les spores et autres structures de survie, étaient limités à la morphogenèse reproductive et absents des hyphes en croissance. On a retrouvé des mycosporines dans huit souches, et le mycosporineglutaminol-glucoside (le λmax = 310 nm; MH+ = 465) est la principale mycosporine détectée. Les mycosporines associées aux micro-colonies fongiques végétatives pourraient être liées à leur haut potentiel de survie, à la croissance intra-coloniale non-expansive et à la longévité de ces champignons. On retrouve des croissances intra-hyphales et la recolonisation de vielles cellules par de nouvelles, dans toutes les souches examinées.
BMC Systems Biology
Rapidly characterizing the operational interrelationships among all genes in a given organism is a critical bottleneck to significantly advancing our understanding of thousands of newly sequenced microbial and eukaryotic species. While evolving technologies for global profiling of transcripts, proteins, and metabolites are making it possible to comprehensively survey cellular physiology in newly sequenced organisms, these experimental techniques have not kept pace with sequencing efforts.doi:10.1186/1752-0509-4-64 pmid:20470417 pmcid:PMC2880973 fatcat:m53dcozgtzeptnltvehja6kqla
more »... nding these technological challenges is the fact that individual experiments typically only stimulate relatively small-scale cellular responses, thus requiring numerous expensive experiments to survey the operational relationships among nearly all genetic elements. Therefore, a relatively quick and inexpensive strategy for observing changes in large fractions of the genetic elements is highly desirable. Results: We have discovered in the model organism Halobacterium salinarum NRC-1 that batch culturing in complex medium stimulates meaningful changes in the expression of approximately two thirds of all genes. While the majority of these changes occur during transition from rapid exponential growth to the stationary phase, several transient physiological states were detected beyond what has been previously observed. In sum, integrated analysis of transcript and metabolite changes has helped uncover growth phase-associated physiologies, operational interrelationships among two thirds of all genes, specialized functions for gene family members, waves of transcription factor activities, and growth phase associated cell morphology control. Conclusions: Simple laboratory culturing in complex medium can be enormously informative regarding the activities of and interrelationships among a large fraction of all genes in an organism. This also yields important baseline physiological context for designing specific perturbation experiments at different phases of growth. The integration of such growth and perturbation studies with measurements of associated environmental factor changes is a practical and economical route for the elucidation of comprehensive systems-level models of biological systems.
., 2006; Whitehead et al., 2006) . 4 Integrate diverse data (mRNA levels, evolutionarily conserved associations among proteins, metabolic pathways, cis-regulatory motifs, etc.) with the cMonkey algorithm ... The remaining studies investigated perturbed responses in genetically perturbed strains (Table S2) , gamma radiation (Whitehead et al., 2006) , transition metals , oxygen (Schmid et al., 2007) , etc ...doi:10.1016/j.cell.2007.10.053 pmid:18160043 fatcat:er5gtgwidfebnfvot5auywpg4i
Dundas that important falls existed a few miles higher up, and as the water was shallow, the Kenia commenced its return journey. Capt. ... Whitehead added greatly to our zoological knowledge of Borneo by his ascent of Kina Balu, from which mountain he brought back a collection that demonstrated the existence of a Himalayan fauna. Mr. ...doi:10.1086/275781 fatcat:w5na3c7rujfarmd56saqfzopy4
Studia i Prace WNEiZ
Państwowe fundusze majątkowe jako czynnik rozwoju krajów Afryki
Państwowe fundusze majątkowe jako czynnik rozwoju krajów Afryki
Taka sytuacja wystąpiła w przypadku Angoli i Nigerii, dla których agencja Moody's Investors Service podniosła ocenę ratingową, uzasadniając decyzję m.in. ustanowieniem PFM (Whitehead, 2012) . ... W 2015 roku, oprócz 17 aktywnych PFM, w Afryce oficjalnie planowano lub ustanowiono (ale nie podjęły działalności), 12 kolejnych PFM w następujących krajach: Sierra Leone, Tunezja, Południowa Afryka, Kenia ...doi:10.18276/sip.2017.49/1-16 fatcat:hujlcbngizfonbdkpvbblspo7e
Coincidimos con Underwood & Suttle (1999) y Whitehead (2000) , que la concentración de nutrimentos del forraje refleja la fertilidad del suelo donde éste crece. ... Estudios llevados a cabo en Kenia por Corbett (1990) indican que los requerimientos de Zn son de aproximadamente 25 µg / g de materia seca, sin embargo han registrado valores de de sólo 5 a 10 ppm sin ...doi:10.21704/rea.v10i1-2.410 fatcat:ud4ls7nxkff73pgjjnxv4ajyzu
Facciotti and Kenia Whitehead for their ideas, support, and critical reading of the manuscript at all stages. ... Proteomics data analysis Proteomics data analysis was performed essentially as described in Whitehead et al. (2006) . ... The data for the 10 iTRAQ sets were then merged and loaded into the Gaggle software package to facilitate data integration and visualization Whitehead et al. 2006) . ...doi:10.1101/gr.6728007 pmid:17785531 pmcid:PMC1987344 fatcat:vm3zvp3envbm3didy2kjpexv4e
Whitehead, On Reforma- tory Institutions,—Dr. Tuffnell’s Address to the Trish College of Surgeons,—Mr. ... The country of Monomwézi and its lakes will have been brought into the immediate vicinity of the head of the basin of the Nile, in which same direction snowy mountains, such as Kilimandjéra, Kénia, and ...
Actualmente, ONU-Habitat, con sede en Nairobi-Kenia, se encarga de coordinar actividades en asentamientos humanos dentro del sistema de dicha organización. ... La ciudad está implicada en el mundo natural con conexiones que consideran y reflejan el poder político, social y económico (Whitehead, 2003) . ...doi:10.15446/bitacora.v27n2.62483 fatcat:gir6c4mb5vbitphsa5jri4rlz4
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