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51.
Cortinarius sarcoflammeus is proposed as a new species belonging to subgenus Dermocybe, on the basis of its morphological, chemical and ecological characters. The strong red-orange colour of the context and stipe
base, large spores, sphagnicolous habitat and high dermorubin content are characteristic for the new species. Holotypes of
C. huronensis and C. huronensis var. olivaceus have been examined for comparison, and their differences discussed. Photographs and line drawings of C. sarcoflammeus are added.
Received February 13, 2001 Accepted March 23, 2001 相似文献
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Questions: Is change in cover of dominant species driving the velocity of succession or is it species turnover (1)? Is the length of the time‐step chosen in sampling affecting our recognition of the long‐term rate of change (2)1 Location: 74 permanent plots located in the Swiss National Park, SE Switzerland, ca. 1900 m a.s.l. Methods: We superimpose several time‐series from permanent plots to one single series solely based on compositional dissimilarity. As shown earlier (Wildi & Schütz 2000) this results in a synthetic series covering about 400 to 650 yr length. Continuous power transformation of cover‐percentage scores is used to test if the dominance or the presence‐absence of species is governing secondary succession from pasture to forest. The effect of time step length is tested by sub‐samples of the time series. Results: Altering the weight of presence‐absence versus dominance of species affects the emerging time frame, while altering time step length is uncritical. Where species turnover is fast, different performance scales yield similar results. When cover change in dominant species prevails, the solutions vary considerably. Ordinations reveal that the synthetic time series seek for shortest paths of the temporal pattern whereas in the real system longer lasting alternatives exist. Conclusions: Superimposing time series differs from the classical space‐for‐time substitution approach. It is a computation‐based method to investigate temporal patterns of hundreds of years fitting between direct monitoring (usually limited to decades) and the analysis of proxy‐data (for time spans of thousands of years and more). 相似文献
54.
Daile Avila Rolando Cardenas Osmel Martin 《Origins of life and evolution of the biosphere》2013,43(1):67-75
In this work we apply a mathematical model of photosynthesis to quantify the potential for photosynthetic life in the very Early Archean oceans. We assume the presence of oceanic blockers of ultraviolet radiation, specifically ferrous ions. For this scenario, our results suggest a potential for photosynthetic life greater than or similar to that in later eras/eons, such as the Late Archean and the current Phanerozoic eon. 相似文献
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A new class of Phycomyces behavioral mutants with enhanced tropic responses has been analyzed genetically to determine the number of genes involved and the nature of their expression. These hypertropic mutants carry pleiotropic nuclear mutations. Besides their effects on sensory behavior, they also affect morphology and meiotic processes. Behavioral analyses of heterokaryons containing hypertropic and wild-type nuclei in varying proportions show that the hypertropic mutations in strains L82, L84, L86, and L88 are strongly dominant. Conversely, the hypertropic mutations carried by the strains L83, L85, and L87 are strongly recessive. We performed recombination analyses between hypertropic mutants and mutants with diminished phototropism, affected in the seven genes madA to madG. We found no evidence of linkage between the hypertropic mutations and any of these mad mutations. From crosses, we isolated double mutants carrying hypertropic mutations together with madC (night blind) and madG (stiff) mutations. The behavioral phenotypes of the double mutants are intermediate between those of the parentals. Complementation analyses show that the three recessive hypertropic mutations affect the same gene, which we call madH. The expression of the recessive hypertropic allele becomes dominant in heterokaryons carrying madC and madH nuclei; the madC gene has been implicated separately with the photoreceptor at the input to the sensory pathway, while the madH gene is associated with the growth control output. This result suggests the physical interaction of both gene products, madH and madC, in a molecular complex for the photosensory transduction chain. 相似文献
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Pampatheres are extinct, large‐bodied cingulates, which share morphological characters with both armadillos and glyptodonts but are considered to be more closely related to the latter. The osteoderm histology of six pampathere taxa was examined and compared to the histology of other cingulate osteoderms. This study investigates the development and functional adaptation of pampathere osteoderms as well as the phylogenetic relationships of the Pampatheriidae within the Cingulata. We found that pampathere osteoderms share a uniform histological organization based on a basic diploe‐like structure. After initial stages of intramembranous growth, metaplastic ossification, that is, the direct incorporation and mineralization of pre‐existing protein fibers, plays an important role in osteoderm development and provides information on various kinds of soft tissue otherwise not preserved. The latest stages of osteoderm growth are dominated by periosteal bone formation especially in the superficial cortex. Movable band osteoderms show regular arrangements of incorporated fibers that may increase the resistance of particularly weak areas against strain. The histological composition of pampathere osteoderms is plesiomorphic in its basic structure but shows a number of derived features. A unique array of Sharpey's fibers that are incorporated into the bone matrix at sutured osteoderm margins is interpreted as a synapomorphy of pampatheres. The arrangement of dermal fibers in the deep and superficial cortexes supports the close relationship between pampatheres and glyptodonts. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc. 相似文献
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Six peripheral blood lymphoid fractions (total lymphocytes, non-T, T, Tar (autologous rosette-forming T cells/precursor), T mu (helper), and T gamma (suppressor) lymphocytes) isolated through rosetting procedures were examined for the presence of ferritin by a direct immunofluorescence technique. Although ferritin was present in all lymphoid fractions studied, a significantly higher proportion of ferritin-containing cells were detected in the T-cell fraction than in the non-T-cell fraction, (mean +/- SD = 7.9 +/- 1.6% and 5.0 +/- 1.2%, respectively). T mu- and T gamma-cell fractions showed a twofold increase in the number of ferritin-positive cells (14.1 +/- 1.4% and 15.4 +/- 2.6%, respectively), as compared with Tar (7.0 +/- 0.9%)-and total lymphocyte (6.9 +/- 1.3%)-cell fractions. These results indicate that ferritin is preferentially distributed in T mu and T gamma lymphocytes and may constitute the basis for explaining some of the roles exercised by these cells in the control of other biological systems. 相似文献
60.