Relative expression analysis of light-harvesting genes in the freshwater alga Lympha mucosa (Batrachospermales, Rhodophyta)

Fine-tuning RNA extraction protocols for polysaccharide-rich freshwater red algae (Rhodophyta)

Freshwater red algae are important primary producers, widely distributed, contributing significantly to nutrient cycling in aquatic ecosystems. Recent studies have focused on identifying the effect of different environmental conditions such as light on the gene expression in photosynthesis pathways. However, obtaining the necessary RNA quantity and quality for sequencing from these algae has been challenging. Although RNA extractions have been optimized for model organisms, RNA extraction for non-model organisms, such as gelatinous (polysaccharide-rich) red algae, requires considerable troubleshooting. The common freshwater red alga, Batrachospermum gelatinosum , was used to test protocols. The extraction efficiency of various sample disruption methods in combination with seven RNA extraction kits was compared. Using a 2-minute disruption procedure with a modification of TRIzol ™ Plus RNA Purification Kit (PureLink ™ RNA Mini Kit + Trizol ™ ) protocol resulted in significantly higher RIN scores (p < 0.05) and high RNA concentration, compared to other methods. The fine-tuned protocol yielded quality RNA (RIN>7) in high concentrations for subsequent sequencing.

A multifaceted ecological assessment reveals the invasion of the freshwater red macroalga Montagnia macrospora (Batrachospermales, Rhodophyta) in Taiwan

Invasive freshwater macroalgae are rarely described. Montagnia macrospora is a freshwater red alga introduced from South America to East Asia via the global aquarium trade. The earliest occurrence record of this alga in Taiwan is dated 2005. To determine whether M. macrospora has become invasive in Taiwan and to understand the traits that facilitated its invasion, we took a multifaceted approach that combines examination of ecological background and population genetic analysis. Our island-wide survey showed that M. macrospora is widespread in the field across Taiwan, where the climate greatly differs from that of South America, and can self-sustain for nearly a decade. Our population genetic analysis revealed a lack of genetic diversity of M. macrospora in Taiwan, consistent with the hypothesis that the alga expanded through asexual reproduction. Moreover, during our long-term ecological assessments and field surveys, we observed that M. macrospora is an ecological generalist that can survive in a wide range of temperature, pH, illumination, and nutrient enrichment. Taken together, our data suggest that M. macrospora has successfully invaded the freshwater ecosystems of Taiwan, likely due to its ability to disperse asexually and to grow under broad environmental conditions. We hope that our study brings attention to invasive freshwater algae, which have been overlooked in conservation planning and management.