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161.
Xavier Arnan Alan N. Andersen Heloise Gibb Catherine L. Parr Nathan J. Sanders Robert R. Dunn Elena Angulo Fabricio B. Baccaro Tom R. Bishop Raphaël Boulay Cristina Castracani Xim Cerdá Israel Del Toro Thibaut Delsinne David A. Donoso Emilie K. Elten Tom M. Fayle Matthew C. Fitzpatrick Crisanto Gómez Donato A. Grasso Blair F. Grossman Benoit Guénard Nihara Gunawardene Brian Heterick Benjamin D. Hoffmann Milan Janda Clinton N. Jenkins Petr Klimes Lori Lach Thomas Laeger Maurice Leponce Andrea Lucky Jonathan Majer Sean Menke Dirk Mezger Alessandra Mori Jimmy Moses Thinandavha Caswell Munyai Omid Paknia Martin Pfeiffer Stacy M. Philpott Jorge L.P. Souza Melanie Tista Heraldo L. Vasconcelos Javier Retana 《Global Change Biology》2018,24(10):4614-4625
The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance‐impoverishment rule states that high levels of dominance only occur in species‐poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which dominant species limit local richness through competitive exclusion remains unclear, but such exclusion appears more apparent for non‐native rather than native dominant species. Here we perform the first global analysis of the relationship between behavioral dominance and species richness. We used data from 1,293 local assemblages of ground‐dwelling ants distributed across five continents to document the generality of the dominance‐impoverishment rule, and to identify the biotic and abiotic conditions under which it does and does not apply. We found that the behavioral dominance–diversity relationship varies greatly, and depends on whether dominant species are native or non‐native, whether dominance is considered as occurrence or relative abundance, and on variation in mean annual temperature. There were declines in diversity with increasing dominance in invaded communities, but diversity increased with increasing dominance in native communities. These patterns occur along the global temperature gradient. However, positive and negative relationships are strongest in the hottest sites. We also found that climate regulates the degree of behavioral dominance, but differently from how it shapes species richness. Our findings imply that, despite strong competitive interactions among ants, competitive exclusion is not a major driver of local richness in native ant communities. Although the dominance‐impoverishment rule applies to invaded communities, we propose an alternative dominance‐diversification rule for native communities. 相似文献
162.
Transformation of Diplonema papillatum,the type species of the highly diverse and abundant marine microeukaryotes Diplonemida (Euglenozoa)
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163.
Cells Persistently Infected with Newcastle Disease Virus: II. Ribonucleic Acid and Protein Synthesis in Cells Infected with Mutants Isolated from Persistently Infected L Cells 总被引:18,自引:14,他引:4
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A comparison of the replication patterns in L cells and in chick embryo (CE) cell cultures was carried out with the Herts strain of Newcastle disease virus (NDV(o)) and with a mutant (NDV(pi)) isolated from persistently infected L cells. A significant amount of virus progeny, 11 plaque-forming units (PFU)/cell, was synthesized in L cells infected with NDV(o), but the infectivity remained cell-associated and disappeared without being detectable in the medium. In contrast, in L cells infected with NDV(pi), progeny virus (30 PFU/cell) was released efficiently upon maturation. It is suggested that the term "covert" rather than "abortive" be used to describe the infection of L cells with NDV(o). In both L and CE cells, the latent period of NDV(pi) was 2 to 4 hr longer than for NDV(o). The delay in synthesis of viral ribonucleic acid (RNA) in the case of NDV(pi) coincided with the delay in the inhibition of host RNA and protein synthesis. Although both NDV(o) and NDV(pi) produced more progeny and more severe cell damage in CE cells than in L cells, the shut-off of host functions was significantly less efficient in CE cells than in L cells. Paradoxically, no detectable interferon was produced in CE cells by either of the viruses, whereas in L cells most of the interferon appeared in the medium after more than 90% of host protein synthesis was inhibited. These results suggest that the absence of induction of interferon synthesis in CE cells infected with NDV is not related to the general shut-off of host cell synthetic mechanisms but rather to the failure of some more specific event to occur. In spite of the fact that NDV(pi) RNA synthesis commenced 2 to 4 hr later than that of NDV(o), interferon was first detected in the medium 8 hr after infection with both viruses. This finding suggests that there is no relation between viral RNA synthesis and the induction of interferon synthesis. 相似文献
164.
The localization, isolation and partial characterization of a collagenolytic enzyme from the land planarian Bipalium kewense is described. This enzyme can be obtained by direct extraction of the organism, and can be separated from non-collagenous proteolytic activity by (NH(4))(2)SO(4) precipitation and Sephadex-gel chromatography. Its mode of attack on collagen and sensitivity to a variety of inhibitors indicate that this enzyme differs from vertebrate collagenases and a previously described invertebrate collagenase. 相似文献
165.
Cultures of Bacillus subtilis infected with phage SP-15 were examined to investigate the metabolic origin of two of the unique components of the phage DNA: the component responsible for the unusually high buoyant density in CsCl and the unusual pyrimidine, 5-(4', 5'-dihydroxypentyl) uracil (DHPU). Newly synthesized pulse-labeled DNA was light in buoyant density and shifted to the high density of mature phage DNA upon further incubation. Parental DNA was converted to a light-density intermediate form prior to replication. When labeled uracil, thymidine, or DHPU were added to infected cells, it was found that only uracil served as the precursor to DHPU and thymine in phage DNA. Analysis of the bases from hydrolyzed DNA of labeled phage or infected cells indicated that the uracil was incorporated into the DNA as such (presumably via deoxyuridine triphosphate) and later converted to DHPU and thymine at the macromolecular level. The sequence of events after phage infection appeared to be: (i) injection of parental DNA; (ii) conversion of parental DNA to a light form; (iii) DNA replication, yielding light DNA containing uracil; (iv) conversion of uracil to DHPU and thymine; and (v) addition of the heavy component. 相似文献
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Julius Pia 《Molecular & general genetics : MGG》1922,30(1):63-98
Ohne ZusammenfassungVergleiche: J. Pia: DieSiphoneae verticillatae vom Karbon bis zur Kreide. Abhandl. Zool.-bot. Ges. Wien. Bd. 11. Heft 2. 1920. Mit Literaturliste. Seit dem Erscheinen dieser Arbeit sind mir folgende wichtigere einschlägige Veröffentlichungen bekannt geworden:A. Andreae: Ein Beitrag zur Kenntnis des Elsässer Tertiärs. Abhandl. z. geol. Spezialk. v. Elsaß-Lotr. vol. 2. fasc. 3. Straßburg 1884.A. Baretti: Contributo allo studio delleSiphoneae Verticillatae del calcare di Villanova-Mondovi. Atti soc. Ital. sc. nat. vol. 58. Pavia 1919. p. 216.F. Börgesen: The Marine Algae of the Danish West Indies. Part. 1.Chlorophyceae. Dansk. Bot. Arkiv. vol. 1. No. 4. 1913.F. Börgesen: The Marine Algae of the Danish West Indies. III.Rhodophyceae with Addenda to theChlorophyceae, Phaeophyceae andRhodophyceae. Ebendort. vol. 3. No. 1a–f. 1917–20.S. v. Bubnoff: Die ladinische Fauna von Forno (Mezzovalle) bei Predazzo. Verhandl. Heidelb. Naturh.-mediz. Vereins 1920. N. F. Bd. 14. S. 257.E. Fossa-Mancini:Sifoneae verticillatae triasiche e liassiche dell' Appennino umbro-marchigiano. Pro. verb. soc. Tosc. sc. nat. vol. 30. 10. III. 1921.M. Gortani: La fauna permocarbonifera del Col Mezzodi presso Forni Avoltri. Pal. Ital. vol. 12. 1906. p. 1.J. Kiaer: Oversigt over Kalkalgefloraerna i Norges Ordovicium og Silur. Norsk Geol. Tidskr. vol. 6. 1921. p. 113.O. Lignier: Végétaux fossiles de Normandie. VI. — Flore jurassique de Mamers (Sarthe). Mém. soc. Linn. Normandie. vol. 24. 1911–13. fasc. 1. p. 1.O. Lignier: Végétaux fossiles de Normandie. VII. — Contribution à la flore jurassique. Ebendort fasc. 2. 1913. p. 67.L. Morellet: Deux Algues siphonées verticillées du Thanétien de Boncourt (Oise). Bull. soc. géol. France ser. 4. vol. 8. 1908. p. 96.L. Morellet et J. Morellet: Les Dasycladacées du Tertiaire Parisien. Mém. soc. géol. France, Paléontologie. vol. 21. fasc. 1. Mém. No. 47. 1913.L. Morellet: Note sur les algues siphonées. In H. Douvillé: Le crétacé et l'éocène du Tibet central. Pal. Indica, New Ser. vol. 5. Mém. No. 3. p. 47. 1916.Munier-Chalmas: Notes préliminaires pour servir à l'étude des terrains crétacées. Bull. soc. géol. France. ser. 3. vol. 25. 1897. p. 82.Ph. Négris: Roches cristallophylliennes et tectonique de la Grèce. 2e appendice. Athènes 1919.S. Squinabol: Di una specie fossile di Acetabularia. Atti e Mem. Acc. sc. Padova, n. s. vol. 18. 1902. p. 151.Mit Tafel 1. 相似文献
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