nsights into the impact of increasing temperature, light intensity, and UV-B exposure on the circadian rhythm of microcystin production and release, and the expression of mcy genes in the cyanobacterium Microcystis aeruginos

Author(s)

Cordeiro-Araujo, Micheline Kezia ^[1] ; Lorenzi, Adriana Sturion ^{[1, 2]} ; Chia, Mathias Ahii ^[3] ; Mota, Eliane Christina ^[1] ; Bittencourt-Oliveira, Maria do Carmo ^[1]

Affiliation

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Biol Sci, Lab Cyanobacteria, Av Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

^[2] Univ Brasilia, Inst Biol Sci, Dept Cellular Biol, UnB, BR-70910900 Brasilia, DF - Brazil

^[3] Ahmadu Bello Univ, Dept Bot, Zaria 810001 - Nigeria

• Document type: Journal article
• Source: JOURNAL OF APPLIED PHYCOLOGY; v. 34, n. 1 NOV 2021.
• Web of Science Citations: 0

Abstract

Increasing temperature and varying light quality can favor the formation of blooms of toxin-producing cyanobacteria. With respect to light quality, increasing type-B ultraviolet radiation (UV-B) causes cellular damage with cascading effects at different levels of biological systems. This study aimed to evaluate the combined effects of light intensity, UV-B, and increasing temperature on the circadian rhythm of production and release of microcystins (MCs) as well as the expression of mcy genes (mcyA, mcyD, and mcyE) and internal H2O2 formation of Microcystis aeruginosa. Microcystis aeruginosa was exposed to UV-B (0.8 W m(-2)) in 24-h cycles (12 h light:12 h dark) at 23, 25, and 30 degrees C combined with 30 or 50 mu mol photons m(-2) s(-1). Samples were collected every 4 h during each 24-h cycle for MC analyses, evaluation of mcy gene expression by RT-qPCR, and internal H2O2 formation. The combination of 23 and 30 degrees C with UV-B changed the circadian rhythm of MC production and release and reduced the cyanotoxin concentration per cell quota. mcyD gene expression was 10.75-fold higher at 23 degrees C and 50 mu mol photons m(-2) s(-1) treatment. However, a 7.55-fold decline in the expression of the mcyE gene occurred at 12 h (light period). The combination of 23 degrees C with UV-B caused the highest intracellular H2O2 formation. The enhanced expression of genes involved in MC synthesis at midday demonstrated that there is a critical period of stress that signals the toxin-production, which has significant implications for the general well-being of aquatic ecosystems. (AU)

• FAPESP's process: 13/15296-2 - Comparative metagenomics of cyanobacterial blooms in freshwater reservoirs from Pernambuco State
• Grantee: Adriana Sturion Lorenzi
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 17/15769-9 - The influence of UV radiation and high temperature on the carbon dioxide sequestration and microcystins production by Microcystis strains
• Grantee: Micheline Kézia Cordeiro de Araújo
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 15/17397-6 - CIRCADIAN RHYTHM IN THE PRODUCTION AND RELEASE OF MICROCYSTINS, EXPRESSION OF mcyE GENE AND PHYSIOLOGICAL STRESS IN CYANOBACTERIA: IMPLICATIONS OF GLOBAL CLIMATE CHANGES
• Grantee: Micheline Kézia Cordeiro de Araújo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/01913-2 - Comparative Metagenomics of cyanobacterial blooms in freshwater reservoirs from Pernambuco State
• Grantee: Adriana Sturion Lorenzi
• Support Opportunities: Scholarships in Brazil - Young Researchers