Mero acaso, fortuita necessidade ou design inteligente???

terça-feira, dezembro 29, 2020

Click here/Clique aqui: (157) Do You Love Me? - YouTube

Um megatsunami atingiu a costa israelense há 10.000 anos atrás.

segunda-feira, dezembro 28, 2020

A Neolithic mega-tsunami event in the eastern Mediterranean: Prehistoric settlement vulnerability along the Carmel coast, Israel

Gilad Shtienberg ,Assaf Yasur-Landau,Richard D. Norris,Michael Lazar,Tammy M. Rittenour,Anthony Tamberino,Omri Gadol,Katrina Cantu,Ehud Arkin-Shalev,Steven N. Ward,Thomas E. Levy

Published: December 23, 2020


Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older tsunamis on prehistoric societies has not been investigated. Here we report, based on optically stimulated luminescence chronology, the earliest documented Holocene tsunami event, between 9.91 to 9.29 ka (kilo-annum), from the eastern Mediterranean at Dor, Israel. Tsunami debris from the early Neolithic is composed of marine sand embedded within fresh-brackish wetland deposits. Global and local sea-level curves for the period, 9.91–9.29 ka, as well as surface elevation reconstructions, show that the tsunami had a run-up of at least ~16 m and traveled between 3.5 to 1.5 km inland from the palaeo-coastline. Submerged slump scars on the continental slope, 16 km west of Dor, point to the nearby “Dor-complex” as a likely cause. The near absence of Pre-Pottery Neolithic A-B archaeological sites (11.70–9.80 cal. ka) suggest these sites were removed by the tsunami, whereas younger, late Pre-Pottery Neolithic B-C (9.25–8.35 cal. ka) and later Pottery-Neolithic sites (8.25–7.80 cal. ka) indicate resettlement following the event. The large run-up of this event highlights the disruptive impact of tsunamis on past societies along the Levantine coast.


Nanomáquinas propulsoras: evolução convergente de arquelas, flagelos e cílios ou design inteligente?

terça-feira, dezembro 08, 2020

Propulsive nanomachines: the convergent evolution of archaella, flagella and cilia 

Morgan Beeby, Josie L Ferreira, Patrick Tripp, Sonja-Verena Albers, David R Mitchell 

FEMS Microbiology Reviews, Volume 44, Issue 3, May 2020, Pages 253–304, 

Published: 09 March 2020

Flagellar motor structure - FEMS


Echoing the repeated convergent evolution of flight and vision in large eukaryotes, propulsive swimming motility has evolved independently in microbes in each of the three domains of life. Filamentous appendages – archaella in Archaea, flagella in Bacteria and cilia in Eukaryotes – wave, whip or rotate to propel microbes, overcoming diffusion and enabling colonization of new environments. The implementations of the three propulsive nanomachines are distinct, however: archaella and flagella rotate, while cilia beat or wave; flagella and cilia assemble at their tips, while archaella assemble at their base; archaella and cilia use ATP for motility, while flagella use ion-motive force. These underlying differences reflect the tinkering required to evolve a molecular machine, in which pre-existing machines in the appropriate contexts were iteratively co-opted for new functions and whose origins are reflected in their resultant mechanisms. Contemporary homologies suggest that archaella evolved from a non-rotary pilus, flagella from a non-rotary appendage or secretion system, and cilia from a passive sensory structure. Here, we review the structure, assembly, mechanism and homologies of the three distinct solutions as a foundation to better understand how propulsive nanomachines evolved three times independently and to highlight principles of molecular evolution.

flagella, cilia, archaella, molecular evolution, microbial motility, convergent evolution

FREE PDF GRATIS: FEMS Microbiology Reviews