نتایج جستجو برای: multicellular life

تعداد نتایج: 760686  

2015
Hyun-Jun Nam Inhae Kim James U. Bowie Sanguk Kim

A central question in animal evolution is how multicellular animals evolved from unicellular ancestors. We hypothesize that membrane proteins must be key players in the development of multicellularity because they are well positioned to form the cell-cell contacts and to provide the intercellular communication required for the creation of complex organisms. Here we find that a major mechanism f...

Journal: :Journal of the Royal Society, Interface 2015
Salva Duran-Nebreda Ricard Solé

How multicellular life forms evolved from unicellular ones constitutes a major problem in our understanding of the evolution of our biosphere. A recent set of experiments involving yeast cell populations have shown that selection for faster sedimenting cells leads to the appearance of stable aggregates of cells that are able to split into smaller clusters. It was suggested that the observed evo...

پایان نامه :0 1392

it is definitely necessary to understand the concept and behavior of causation of life insurance policies and its determinants for insurance managers, regulators, and customers. for insurance managers, the profitability and liquidity of insurers can be increasingly influenced by the number of causation through costs, adverse selection, and cash surrender values. therefore, causation is a materi...

Donyapour N Gharamaleki H Roshangar L, Soleimani Rad J Valipoor A

Background: Electromagnetic fields interact with human tissues and may have adverse effects on fertility and reproduction. During the last decades there has been a growing concern on the effects of electromagnetic radiations on biological systems in general. Radiation risks from electromagnetic fields generated by processes such as reduced fertility and a significant decrease in implantation ra...

2013
Jack Hessel Sherri Goings

The processes by which multicellular organisms first emerged from their unicellular ancestors are fundamental to the biology of complex, differentiated life forms. Previous work suggests that reproductive division of labor between specialized germ and soma cells was central to this evolution in some cases. Here, we assess the potential of the digital life platform Avida to examine the trade-off...

Journal: :Current Biology 2013
Roberta M. Fisher Charlie K. Cornwallis Stuart A. West

The evolution of multicellular organisms represents one of approximately eight major evolutionary transitions that have occurred on earth. The major challenge raised by this transition is to explain why single cells should join together and become mutually dependent, in a way that leads to a more complex multicellular life form that can only replicate as a whole. It has been argued that a high ...

2017
Lars Witting

I show that the natural selection of metabolism and mass can select for the major life-history and allometric transitions that define lifeforms from viruses, over prokaryotes and larger unicells, to multicellular animals. The proposed selection is driven by a mass-specific metabolism that is selected as the pace of the resource handling that generates net energy for self-replication. An initial...

2015
C. Athena Aktipis Amy M. Boddy Gunther Jansen Urszula Hibner Michael E. Hochberg Carlo C. Maley Gerald S. Wilkinson

Multicellularity is characterized by cooperation among cells for the development, maintenance and reproduction of the multicellular organism. Cancer can be viewed as cheating within this cooperative multicellular system. Complex multicellularity, and the cooperation underlying it, has evolved independently multiple times. We review the existing literature on cancer and cancer-like phenomena acr...

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