Os mecanismos do motor ciliar são revelados: mero acaso, fortuita necessidade ou design inteligente?

ATP-induced conformational change of axonemal outer dynein arms revealed by cryo-electron tomography

Noemi Zimmermann, Akira Noga, Jagan Mohan Obbineni, Takashi Ishikawa

The EMBO Journal (2023)42:e112466

https://doi.org/10.15252/embj.2022112466

Outer dynein arms in the ciliary axoneme generate force for ciliary beating.

Abstract

Axonemal outer dynein arm (ODA) motors generate force for ciliary beating. We analyzed three states of the ODA during the power stroke cycle using in situ cryo-electron tomography, subtomogram averaging, and classification. These states of force generation depict the prepower stroke, postpower stroke, and intermediate state conformations. Comparison of these conformations to published in vitro atomic structures of cytoplasmic dynein, ODA, and the Shulin–ODA complex revealed differences in the orientation and position of the dynein head. Our analysis shows that in the absence of ATP, all dynein linkers interact with the AAA3/AAA4 domains, indicating that interactions with the adjacent microtubule doublet B-tubule direct dynein orientation. For the prepower stroke conformation, there were changes in the tail that is anchored on the A-tubule. We built models starting with available high-resolution structures to generate a best-fitting model structure for the in situ pre- and postpower stroke ODA conformations, thereby showing that ODA in a complex with Shulin adopts a similar conformation as the active prepower stroke ODA in the axoneme.

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Darwin, nós temos um problema: a perspectiva agencial

Evolution & Development Early View

RESEARCH ARTICLE

Open Access

The agential perspective: Countermapping the modern synthesis

Denis M. Walsh, Gregory Rupik

First published: 14 June 2023

https://doi.org/10.1111/ede.12448

Abstract

We compare and contrast two theoretical perspectives on adaptive evolution—the orthodox Modern Synthesis perspective, and the nascent Agential Perspective. To do so, we develop the idea from Rasmus Grønfeldt Winther of a ‘countermap’, as a means for comparing the respective ontologies of different scientific perspectives. We conclude that the modern Synthesis perspective achieves an impressively comprehensive view of a universal set of dynamical properties of populations, but at the considerable cost of radically distorting the nature of the biological processes that contribute to evolution. For its part, the Agential Perspective offers the prospect of representing the biological processes of evolution with much greater fidelity, but at the expense of generality. Trade-offs of this sort are endemic to science, and inevitable. Recognizing them helps us to avoid the pitfalls of ‘illicit reification’, i.e. the mistake of interpreting a feature of a scientific perspective as a feature of the non-perspectival world. We argue that much of the traditional Modern Synthesis representation of the biology of evolution commits this illicit reification.

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Darwin, nós temos um problema: toda biologia é processamento de informação cognitiva

Progress in Biophysics and Molecular Biology

Volume 182, September 2023, Pages 34-48

A revised central dogma for the 21st century: all biology is cognitive information processing

William B. Miller Jr. a, František Baluška b, Arthur S. Reber c

a Paradise Valley, AZ, USA

b IZMB, University of Bonn, Kirschellee 1, 53115, Bonn, Germany

c Department of Psychology, University of British Columbia, Vancouver, BC, Canada

Received 10 February 2023, Revised 28 March 2023, Accepted 30 May 2023, Available online 1 June 2023, Version of Record 6 June 2023.

https://doi.org/10.1016/j.pbiomolbio.2023.05.005 

Abstract

Crick's Central Dogma has been a foundational aspect of 20th century biology, describing an implicit relationship governing the flow of information in biological systems in biomolecular terms. Accumulating scientific discoveries support the need for a revised Central Dogma to buttress evolutionary biology's still-fledgling migration from a Neodarwinian canon. A reformulated Central Dogma to meet contemporary biology is proposed: all biology is cognitive information processing. Central to this contention is the recognition that life is the self-referential state, instantiated within the cellular form. Self-referential cells act to sustain themselves and to do so, cells must be in consistent harmony with their environment. That consonance is achieved by the continuous assimilation of environmental cues and stresses as information to self-referential observers. All received cellular information must be analyzed to be deployed as cellular problem-solving to maintain homeorhetic equipoise. However, the effective implementation of information is definitively a function of orderly information management. Consequently, effective cellular problem-solving is information processing and management. The epicenter of that cellular information processing is its self-referential internal measurement. All further biological self-organization initiates from this obligate activity. As the internal measurement by cells of information is self-referential by definition, self-reference is biological self-organization, underpinning 21st century Cognition-Based Biology.

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Progress in Biophysics and Molecular Biology