The Resonance and Adaptation of Neurospora crassa Circadian and Conidiation Rhyth ms to Short Light-Dark Cycles.

Huan Ma,Yunzhen Li,Xiaohong Ma,Xiaolin Yang,Jinhu Guo,Yu Yuan,Ling Yang,Jie Yan,Yin Zhang,Luyao Li

doi:10.3390/jof8010027

Huan Ma, Yunzhen Li + Show 8 more

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https://doi.org/10.3390/jof8010027

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Abstract

Circadian clocks control the physiological and behavioral rhythms to adapt to the environment with a period of ~24 h. However, the influences and mechanisms of the extreme light/dark cycles on the circadian clock remain unclear. We showed that, in Neurospora crassa, both the growth and the microconidia production contribute to adaptation in LD12:12 (12 h light/12 h dark, periodically). Mathematical modeling and experiments demonstrate that in short LD cycles, the expression of the core clock protein FREQUENCY was entrained to the LD cycles when LD > 3:3 while it free ran when T ≤ LD3:3. The conidial rhythmicity can resonate with a series of different LD conditions. Moreover, we demonstrate that the existence of unknown blue light photoreceptor(s) and the circadian clock might promote the conidiation rhythms that resonate with the environment. The ubiquitin E3 ligase FWD-1 and the previously described CRY-dependent oscillator system were implicated in regulating conidiation under short LD conditions. These findings shed new light on the resonance of Neurospora circadian clock and conidiation rhythms to short LD cycles, which may benefit the understandings of both the basic regulatory aspects of circadian clock and the adaptation of physiological rhythms to the extreme conditions.

Highlights

Published: 29 December 2021The Earth rotates with a period of approximately 24 h, which causes periodic changes in many environmental factors
We investigated the influence of short light-dark cycling conditions on the circadian clock in Neurospora, and compared the effects of the different light-dark cycles on growth, microconidia production, conidiation rhythmicity and gene expression
To address how the short LD cycles affect the rhythms, we conducted race tube assays with the wild-type strain (301-5, bd), under the following series of short LD cycling conditions including LD9:9, LD6:6, LD4:4, LD3:3, LD2:2, LD1:1, LD45 min:45 min and LD30 min:30 min, which consisted of symmetric light and dark phases

Summary

Introduction

Published: 29 December 2021The Earth rotates with a period of approximately 24 h, which causes periodic changes in many environmental factors. Circadian clocks are the inner mechanisms that allow organisms to adjust their physiology and behavior to the daily cycling of environmental factors, e.g., light and temperature [1]. In the natural daily cycling conditions, rhythms with the same 24 h period to the environmental factors occur in organisms, which are called diurnal rhythms. Whereas in constant conditions in which any environmental cues are absent, e.g., light, dark, temperature or humidity, organisms display rhythms with periods slightly deviated from 24 h, which are called free-running rhythms [2]. Non-24 h light-dark (LD) cycles can entrain the circadian rhythms, and the flexibility of this entrainability dramatically varies between different organisms. Within the range of entrainment, which is called the limit of stable entrainment, the rhythm changes in accordance with the non-24 h T-cycles and show stable phase angles. Phase angle represents the relationship between the timing of the rhythm and the timing of an Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations

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