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- Galluzzi, L, et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring cell death in higher eukaryotes.
- 2009
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Ingår i: Cell death and differentiation. - : Springer Science and Business Media LLC. - 1476-5403 .- 1350-9047. ; 16:8, s. 1093-107
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Forskningsöversikt (refereegranskat)abstract
- Cell death is essential for a plethora of physiological processes, and its deregulation characterizes numerous human diseases. Thus, the in-depth investigation of cell death and its mechanisms constitutes a formidable challenge for fundamental and applied biomedical research, and has tremendous implications for the development of novel therapeutic strategies. It is, therefore, of utmost importance to standardize the experimental procedures that identify dying and dead cells in cell cultures and/or in tissues, from model organisms and/or humans, in healthy and/or pathological scenarios. Thus far, dozens of methods have been proposed to quantify cell death-related parameters. However, no guidelines exist regarding their use and interpretation, and nobody has thoroughly annotated the experimental settings for which each of these techniques is most appropriate. Here, we provide a nonexhaustive comparison of methods to detect cell death with apoptotic or nonapoptotic morphologies, their advantages and pitfalls. These guidelines are intended for investigators who study cell death, as well as for reviewers who need to constructively critique scientific reports that deal with cellular demise. Given the difficulties in determining the exact number of cells that have passed the point-of-no-return of the signaling cascades leading to cell death, we emphasize the importance of performing multiple, methodologically unrelated assays to quantify dying and dead cells.
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| 3. |
- Folland, Chris K., et al.
(författare)
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The Summer North Atlantic Oscillation: past, present and future
- 2009
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Ingår i: Journal of Climate. - 0894-8755. ; 22:5, s. 1082-1103
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Tidskriftsartikel (refereegranskat)abstract
- Summer climate in the North Atlantic-European sector possesses a principal pattern of year-to-year variability that is the parallel of the well-known North Atlantic Oscillation in winter. This ‘Summer North Atlantic Oscillation’ (SNAO) is defined here as the first empirical orthogonal function (EOF) of observed summertime extratropical North Atlantic pressure at mean sea level. It is shown to be characterised by a more northerly location and smaller spatial scale than its winter counterpart. The SNAO is also detected by cluster analysis and has a near equivalent barotropic structure on daily and monthly time scales. Although of lesser amplitude than its wintertime counterpart, the SNAO exerts a strong influence on Northern European rainfall, temperature and cloudiness through changes in the position of the North Atlantic storm track. It is, therefore, of key importance in generating summer climate extremes, including flooding, drought and heat stress in North Western Europe. The El Niño/Southern Oscillation (ENSO) phenomenon is known to influence summertime European climate; however, interannual variations of the SNAO are only weakly influenced by ENSO. On interdecadal time scales, both modelling and observational results indicate that SNAO variations are partly related to the Atlantic Multidecadal Oscillation. It is shown that SNAO variations extend far back in time, as evidenced by reconstructions of SNAO variations back to 1706 using tree-ring records. Very long instrumental records, such as Central England Temperature, are used to validate the reconstruction. Finally, two climate models are shown to simulate the present-day SNAO and predict a trend towards a more positive index phase in the future under increasing greenhouse gas concentrations. This implies the long-term likelihood of increased summer drought for North Western Europe
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| 4. |
- Gilbert, M. Thomas P., et al.
(författare)
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Intraspecific phylogenetic analysis of Siberian woolly mammoths using complete mitochondrial genomes
- 2008
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 105:24, s. 8327-8332
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Tidskriftsartikel (refereegranskat)abstract
- We report five new complete mitochondrial DNA (mtDNA) genomes of Siberian woolly mammoth (Mammuthus primigenius), sequenced with up to 73-fold coverage from DNA extracted from hair shaft material. Three of the sequences present the first complete mtDNA genomes of mammoth clade II. Analysis of these and 13 recently published mtDNA genomes demonstrates the existence of two apparently sympatric mtDNA clades that exhibit high interclade divergence. The analytical power afforded by the analysis of the complete mtDNA genomes reveals a surprisingly ancient coalescence age of the two clades, approximate to 1-2 million years, depending on the calibration technique. Furthermore, statistical analysis of the temporal distribution of the C-14 ages of these and previously identified members of the two mammoth clades suggests that clade II went extinct before clade I. Modeling of protein structures failed to indicate any important functional difference between genomes belonging to the two clades, suggesting that the loss of clade II more likely is due to genetic drift than a selective sweep.
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| 7. |
- Peate, I U, et al.
(författare)
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Volcanic stratigraphy of large-volume silicic pyroclastic eruptions during Oligocene Afro-Arabian flood volcanism in Yemen
- 2005
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Ingår i: Bulletin of Volcanology. - : Springer Science and Business Media LLC. - 0258-8900 .- 1432-0819. ; 68:2, s. 135-156
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Tidskriftsartikel (refereegranskat)abstract
- A new stratigraphy for bimodal Oligocene flood volcanism that forms the volcanic plateau of northern Yemen is presented based on detailed field observations, petrography and geochemical correlations. The > 1 km thick volcanic pile is divided into three phases of volcanism: a main basaltic stage ( 31 to 29.7 Ma), a main silicic stage ( 29.7 to 29.5 Ma), and a stage of upper bimodal volcanism ( 29.5 to 27.7 Ma). Eight large-volume silicic pyroclastic eruptive units are traceable throughout northern Yemen, and some units can be correlated with silicic eruptive units in the Ethiopian Traps and to tephra layers in the Indian Ocean. The silicic units comprise pyroclastic density current and fall deposits and a caldera-collapse breccia, and they display textures that unequivocally identify them as primary pyroclastic deposits: basal vitrophyres, eutaxitic fabrics, glass shards, vitroclastic ash matrices and accretionary lapilli. Individual pyroclastic eruptions have preserved on-land volumes of up to similar to 850 km(3). The largest units have associated co-ignimbrite plume ash fall deposits with dispersal areas > 1 x 10(7) km(2) and estimated maximum total volumes of up to 5,000 km(3), which provide accurate and precisely dated marker horizons that can be used to link litho-, bio- and magnetostratigraphy studies. There is a marked change in eruption style of silicic units with time, from initial large-volume explosive pyroclastic eruptions producing ignimbrites and near-globally distributed tuffs, to smaller volume (< 50 km(3)) mixed effusive-explosive eruptions emplacing silicic lavas intercalated with tuffs and ignimbrites. Although eruption volumes decrease by an order of magnitude from the first stage to the last, eruption intervals within each phase remain broadly similar. These changes may reflect the initiation of continental rifting and the transition from pre-break-up thick, stable crust supporting large-volume magma chambers, to syn-rift actively thinning crust hosting small-volume magma chambers.
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| 9. |
- Östman, Örjan, et al.
(författare)
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Habitat area affects arthropod communities directly and indirectly through top predators
- 2007
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Ingår i: Ecography. - 0906-7590 .- 1600-0587. ; 30:3, s. 359-366
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Tidskriftsartikel (refereegranskat)abstract
- Both habitat area and predators are known to affect the diversity and composition of species that live in a locality. In addition, habitat area can influence the presence of predators, indirectly affecting the diversity of prey. Thus, habitat area may influence species diversity directly and indirectly through the presence of top predators. Here we examine the effects of habitat area and predators on the species richness and composition of a foliage living arthropod community in a fragmented complex of glades (small grassland patches within a forested matrix) in the Ozark Plateau, Missouri. We find that a top predator, the eastern collared lizard Crotaphytus collaris collaris, occurs primarily on larger glades. Glade area was positively correlated with arthropod diversity, but only after removing the effect of collared lizard presence. Moreover, collared lizards reduced overall arthropod richness, and shifted the dominance from predatory arthropods (e.g. spiders) and Orthopteran grasshoppers to Homopterans (planthoppers). This study shows the importance of accounting for variation in the presence of a top predator when studying the effect of landscape-level processes on species richness and composition.
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