Plankton’s candidate blue-light receptors grow more diverse towards the poles
Global marine sequence data show greater diversity of candidate light-sensing proteins at high latitudes. Aureochromes, which connect blue-light sensing to gene regulation, were widespread across ocean regions. A peer-reviewed evolutionary analysis also traced related sequences to nonphotosynthetic lineages, suggesting an origin before photosynthesis arose in this branch of life. Individual candidates still require functional testing.
Science··Evening
Ocean sequences reveal a polar diversity pattern
A peer-reviewed analysis of marine microorganisms identified a richer variety of possible blue-light sensors near the polar regions. The comparison used ribonucleic acid (RNA), the molecules that carry information from active genes, sampled across ocean regions. The polar pattern persisted after accounting for differences in sequencing depth and community diversity. Blue light reaches far into seawater and gives organisms information about their surroundings.[1]
Aureochromes connect light sensing with gene control
Aureochromes were the most frequently detected receptor family of the type studied. These proteins combine a light-sensitive region with a region that binds deoxyribonucleic acid (DNA), the genetic material. An evolutionary comparison retained 323 aureochrome sequences from 96 species after screening 201 datasets. It covered stramenopiles, a broad group of nucleated organisms including diatoms, the microscopic algae common in marine plankton.[1]
Related sequences also appeared in early-diverging lineages that do not photosynthesize. Researchers interpret this distribution as consistent with an origin before photosynthesis arose in the group. Polar and nonpolar diatoms retained similar basic receptor architecture. Adaptation could involve gene regulation instead, but that remains a proposed explanation. Sequence detection alone does not demonstrate blue-light responses in every candidate; ancestry and temperature may also affect the diversity pattern.[1]
