<i>Baffinella frigidus</i> gen. et sp. nov. (Baffinellaceae fam. nov., Cryptophyceae) from Baffin Bay: Morphology, pigment profile, phylogeny, and growth rate response to three abiotic factors

Daugbjerg, Niels; Norlin, Andreas; Lovejoy, Connie

doi:10.1111/jpy.12766

Cited by 33 publications

(33 citation statements)

References 50 publications

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“…The majority were cold-water species (from the Arctic or Antarctic), but Rhodomonas lens was from the Gulf of Mexico and Rhodomonas salina was from Milford, Connecticut. The previously unclassified strain CCMP 2293 has recently been allocated to the new genus Baffinella (as Baffinella frigidus) (17). Table 1 lists GenBank accession numbers, source organisms, transcript names, and abbreviated protein names of the BCCR homologs identified in this study.…”

Section: Resultsmentioning

confidence: 99%

Conductance Mechanisms of Rapidly Desensitizing Cation Channelrhodopsins from Cryptophyte Algae

Sineshchekov

Govorunova

et al. 2020

mBio

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Channelrhodopsins guide algal phototaxis and are widely used as optogenetic probes for control of membrane potential with light. “Bacteriorhodopsin-like” cation channelrhodopsins (BCCRs) from cryptophytes differ in primary structure from other CCRs, lacking usual residues important for their cation conductance. Instead, the sequences of BCCR match more closely those of rhodopsin proton pumps, containing residues responsible for critical proton transfer reactions. We report 19 new BCCRs which, together with the earlier 6 known members of this family, form three branches (subfamilies) of a phylogenetic tree. Here, we show that the conductance mechanisms in two subfamilies differ with respect to involvement of the homolog of the proton donor in rhodopsin pumps. Two BCCRs from the genus Rhodomonas generate photocurrents that rapidly desensitize under continuous illumination. Using a combination of patch clamp electrophysiology, absorption, Raman spectroscopy, and flash photolysis, we found that the desensitization is due to rapid accumulation of a long-lived nonconducting intermediate of the photocycle with unusually blue-shifted absorption with a maximum at 330 nm. These observations reveal diversity within the BCCR family and contribute to deeper understanding of their independently evolved cation channel function. IMPORTANCE Cation channelrhodopsins, light-gated channels from flagellate green algae, are extensively used as optogenetic photoactivators of neurons in research and recently have progressed to clinical trials for vision restoration. However, the molecular mechanisms of their photoactivation remain poorly understood. We recently identified cryptophyte cation channelrhodopsins, structurally different from those of green algae, which have separately evolved to converge on light-gated cation conductance. This study reveals diversity within this new protein family and describes a subclade with unusually rapid desensitization that results in short transient photocurrents in continuous light. Such transient currents have not been observed in the green algae channelrhodopsins and are potentially useful in optogenetic protocols. Kinetic UV-visible (UV-vis) spectroscopy and photoelectrophysiology reveal that the desensitization is caused by rapid accumulation of a nonconductive photointermediate in the photochemical reaction cycle. The absorption maximum of the intermediate is 330 nm, the shortest wavelength reported in any rhodopsin, indicating a novel chromophore structure.

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Section: Resultsmentioning

confidence: 99%

Conductance Mechanisms of Rapidly Desensitizing Cation Channelrhodopsins from Cryptophyte Algae

Sineshchekov

Govorunova

et al. 2020

mBio

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“…Recently, another cryptophyte with a suspected dimorphism (Baffinella frigida) was described from the Arctic by Daugbjerg et al (22). This species was covered by hexagonal plates.…”

Section: Dimorphism In the Cryptophytesmentioning

confidence: 99%

Dimorphism in cryptophytes—The case of Teleaulax amphioxeia / Plagioselmis prolonga and its ecological implications

et al. 2020

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Growing evidence suggests that sexual reproduction might be common in unicellular organisms, but observations are sparse. Limited knowledge of sexual reproduction constrains understanding of protist ecology. Although Teleaulax amphioxeia and Plagioselmis prolonga are common marine cryptophytes worldwide, and are also important plastid donors for some kleptoplastic ciliates and dinoflagellates, the ecology and development of these protists are poorly known. We demonstrate that P. prolonga is the haploid form of the diploid T. amphioxeia and describe the seasonal dynamics of these two life stages. The diploid T. amphioxeia dominates during periods of high dissolved inorganic nitrogen (DIN) and low irradiance, temperature, and grazing (winter and early spring), whereas the haploid P. prolonga becomes more abundant during the summer, when DIN is low and irradiance, temperature, and grazing are high. Dimorphic sexual life cycles might explain the success of this species by fostering high genetic diversity and enabling endurance in adverse conditions.

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“…strain CCMP2045 ( Figure 6B). This genus was originally isolated from Baffin Bay and is the first Cryptophyta representative described from this region (Daugbjerg et al, 2018). Cells are ~1 0 μm long and 5 μm wide with a prominent pyrenoid ( Figure 7A).…”

Section: Cryptophytamentioning

confidence: 99%

Culturable diversity of Arctic phytoplankton during pack ice melting

Ribeiro

Santos

Gourvil

et al. 2020

Elementa: Science of the Anthropocene

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Massive phytoplankton blooms develop at the Arctic ice edge, sometimes extending far under the pack ice. An extensive culturing effort was conducted before and during a phytoplankton bloom in Baffin Bay between April and July 2016. Different isolation strategies were applied, including flow cytometry cell sorting, manual single cell pipetting, and serial dilution. Although all three techniques yielded the most common organisms, each technique retrieved specific taxa, highlighting the importance of using several methods to maximize the number and diversity of isolated strains. More than 1,000 cultures were obtained, characterized by 18S rRNA sequencing and optical microscopy, and de-replicated to a subset of 276 strains presented in this work. Strains grouped into 57 phylotypes defined by 100% 18S rRNA sequence similarity. These phylotypes spread across five divisions: Heterokontophyta, Chlorophyta, Cryptophyta, Haptophyta and Dinophyta. Diatoms were the most abundant group (193 strains), mostly represented by the genera Chaetoceros and Attheya. The genera Baffinella and Pyramimonas were the most abundant non-diatom nanoplankton strains, while Micromonas polaris dominated the picoplankton. Diversity at the class level was higher during the peak of the bloom. Potentially new species were isolated, in particular within the genera Navicula, Nitzschia, Coscinodiscus, Thalassiosira, Pyramimonas, Mantoniella and Isochrysis. Culturing efforts such as this one highlight the unexplored eukaryotic plankton diversity in the Arctic and provide a large number of strains for analyzing physiological and metabolic impacts in this changing environment.

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Baffinella frigidus gen. et sp. nov. (Baffinellaceae fam. nov., Cryptophyceae) from Baffin Bay: Morphology, pigment profile, phylogeny, and growth rate response to three abiotic factors

Cited by 33 publications

References 50 publications

Conductance Mechanisms of Rapidly Desensitizing Cation Channelrhodopsins from Cryptophyte Algae

Conductance Mechanisms of Rapidly Desensitizing Cation Channelrhodopsins from Cryptophyte Algae

Dimorphism in cryptophytes—The case of Teleaulax amphioxeia / Plagioselmis prolonga and its ecological implications

Culturable diversity of Arctic phytoplankton during pack ice melting

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