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Long-term microclimatic stress causes rapid adaptive radiation of kaiABC clock gene family in a cyanobacterium, Nostoc linckia, from "Evolution Canyons" I and II, Israel.

ABSTRACT: Cyanobacteria are the only prokaryotes known thus far possessing regulation of physiological functions with approximate daily periodicity, or circadian rhythms, that are controlled by a cluster of three genes, kaiA, kaiB, and kaiC. Here we demonstrate considerably higher genetic polymorphism and extremely rapid evolution of the kaiABC gene family in a filamentous cyanobacterium, Nostoc linckia, permanently exposed to the acute natural environmental stress in the two microsite evolutionary models known as "Evolution Canyons," I (Mount Carmel) and II (Upper Galilee) in Israel. The family consists of five distinct subfamilies (kaiI-kaiV) comprising at least 20 functional genes and pseudogenes. The obtained data suggest that the duplications of kai genes have adaptive significance, and some of them are evolutionarily quite recent (approximately 80,000 years ago). The observed patterns of within- and between-subfamily polymorphisms indicate that positive diversifying, balancing, and purifying selections are the principal driving forces of the kai gene family's evolution.

SUBMITTER: Dvornyk V

PROVIDER: S-EPMC123721 | biostudies-literature | 2002 Feb

REPOSITORIES: biostudies-literature

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Long-term microclimatic stress causes rapid adaptive radiation of kaiABC clock gene family in a cyanobacterium, Nostoc linckia, from "Evolution Canyons" I and II, Israel.

Dvornyk Volodymyr V Vinogradova Oxana O Nevo Eviatar E

Proceedings of the National Academy of Sciences of the United States of America 20020212 4

Cyanobacteria are the only prokaryotes known thus far possessing regulation of physiological functions with approximate daily periodicity, or circadian rhythms, that are controlled by a cluster of three genes, kaiA, kaiB, and kaiC. Here we demonstrate considerably higher genetic polymorphism and extremely rapid evolution of the kaiABC gene family in a filamentous cyanobacterium, Nostoc linckia, permanently exposed to the acute natural environmental stress in the two microsite evolutionary models ...[more]

PMID: 11842226

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Project description:Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.

Dataset Information

Long-term microclimatic stress causes rapid adaptive radiation of kaiABC clock gene family in a cyanobacterium, Nostoc linckia, from "Evolution Canyons" I and II, Israel.

Publications

Long-term microclimatic stress causes rapid adaptive radiation of kaiABC clock gene family in a cyanobacterium, Nostoc linckia, from "Evolution Canyons" I and II, Israel.

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