Ferruginous conditions dominated later neoproterozoic deep-water chemistry     

Canfield DE  Poulton SW  Knoll AH  Narbonne GM  Ross G  Goldberg T  Strauss H 《Science (New York, N.Y.)》2008,321(5891):949-952

Earth's surface chemical environment has evolved from an early anoxic condition to the oxic state we have today. Transitional between an earlier Proterozoic world with widespread deep-water anoxia and a Phanerozoic world with large oxygen-utilizing animals, the Neoproterozoic Era [1000 to 542 million years ago (Ma)] plays a key role in this history. The details of Neoproterozoic Earth surface oxygenation, however, remain unclear. We report that through much of the later Neoproterozoic (<742 +/- 6 Ma), anoxia remained widespread beneath the mixed layer of the oceans; deeper water masses were sometimes sulfidic but were mainly Fe2+-enriched. These ferruginous conditions marked a return to ocean chemistry not seen for more than one billion years of Earth history.  相似文献   

VDAC2 inhibits BAK activation and mitochondrial apoptosis     

Cheng EH  Sheiko TV  Fisher JK  Craigen WJ  Korsmeyer SJ 《Science (New York, N.Y.)》2003,301(5632):513-517

The multidomain proapoptotic molecules BAK or BAX are required to initiate the mitochondrial pathway of apoptosis. How cells maintain the potentially lethal proapoptotic effector BAK in a monomeric inactive conformation at mitochondria is unknown. In viable cells, we found BAK complexed with mitochondrial outer-membrane protein VDAC2, a VDAC isoform present in low abundance that interacts specifically with the inactive conformer of BAK. Cells deficient in VDAC2, but not cells lacking the more abundant VDAC1, exhibited enhanced BAK oligomerization and were more susceptible to apoptotic death. Conversely, overexpression of VDAC2 selectively prevented BAK activation and inhibited the mitochondrial apoptotic pathway. Death signals activate "BH3-only" molecules such as tBID, BIM, or BAD, which displace VDAC2 from BAK, enabling homo-oligomerization of BAK and apoptosis. Thus, VDAC2, an isoform restricted to mammals, regulates the activity of BAK and provides a connection between mitochondrial physiology and the core apoptotic pathway.  相似文献   

Forms of Cu (II), Zn (II), and Pb (II) compounds in technogenically transformed soils adjacent to the Karabashmed copper smelter     

Tatiana M. Minkina  Vitaly G. Linnik  Dina G. Nevidomskaya  Tatiana V. Bauer  Saglara S. Mandzhieva  Vitaliy Y. Khoroshavin 《Journal of Soils and Sediments》2018,18(6):2217-2228

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Treatment of Indigo-Dyed Textile Wastewater Using Solar Photo-Fenton with Iron-Modified Clay and Copper-Modified Carbon     

Almazán-Sánchez  Perla Tatiana  Marin-Noriega  Paul William  González-Mora  Eduardo  Linares-Hernández  Ivonne  Solache-Ríos  Marcos J.  Martínez-Cienfuegos  Iván G.  Martínez-Miranda  Verónica 《Water, air, and soil pollution》2017,228(8):1-26

Water, Air, & Soil Pollution - Biochar presents great promise as a technology that makes a substantial contribution in various fields of environmental research. However, existing knowledge is...  相似文献   

What controls fish functional diversity patterns in Colombian Andean streams?     

Jose Luis Poveda-Cuellar  Edwin Orlando Lpez Delgado  Pamela Tatiana Zúiga-Upegui  Francisco Antonio Villa Navarro 《Ecology of Freshwater Fish》2022,31(1):87-101

Understanding the mechanisms that structure communities have been a major challenge in ecological theory. Functional trait-based approaches are increasingly used for studying the processes underlying community assembly. However, species-poor systems of Andean streams these processes are largely unknown. Tropical Andean streams are highly variable in space-time and characterised by the harsh or stable environment, resulting in a high taxonomic and ecological diversity. In this study, we tested the influence of environmental variables on the fish functional structure. We proposed that in ecosystems with harsh environments, environmental filtering will structure fish assemblages, and in ecosystems with a more stable environment, limiting similarity will prevail, increasing functional diversity. We analysed fish assemblages using functional diversity indices, fourth-corner RLQ analyses and multiple regression models. Environmental variables such as altitude, stream width, sub-Andean vegetation and pH influenced functional diversity. For instance, high values of functional redundancy were registered at high elevation streams, reflecting fish assemblages composed of highly dominant species with similar functional traits such as species of the genus Astroblepus. However, we found differences between Astroblepus species in the number and distance of gill rakers which might indicate resource partitioning and coexistence. On the other hand, our results show both stochastic dynamics and environmental filtering are structuring fish assemblages in low and high elevation Andean streams respectively.  相似文献