Drag Reduction in Wave-Swept Macroalgae: Alternative Strategies and New Predictions

Premise of the study: Intertidal macroalgae must resist extreme hydrodynamic forces imposed by crashing waves. How does frond flexibility mitigate drag, and how does flexibility affect predictions of drag and dislodgement in the field? Methods: We characterized flexible reconfiguration of six seaweed species in a recirculating water flume, documenting both shape change and area reduction as fronds reorient. We then used a high-speed gravity-accelerated water flume to test our ability to predict drag under waves based on extrapolations of drag recorded at slower speeds. We compared dislodgement forces to drag forces predicted from slow- and high-speed data to generate new predictions of survivorship and maximum sustainable frond size along wave-swept shores. Key results: Bladed algae were generally shape changers , limiting drag by reducing drag coefficients, whereas the branched alga Calliarthron was an area reducer , limiting drag by reducing projected area in flow. Drag predictions often underestimated actual drag measurements at high speeds, suggesting that slow- speed data may not reflect the performance of flexible seaweeds under breaking waves. Several seaweeds were predicted to dislodge at similar combinations of velocity and frond size, suggesting common scaling factors of dislodgement strength and drag. Conclusions: Changing shape and reducing projected area in flow are two distinct strategies employed by flexible seaweeds to resist drag. Flexible reconfiguration contributes to the uncertainty of drag extrapolation, and researchers should use caution when predicting drag and dislodgement of seaweeds in the field

Crusticorallina gen. nov., a nongeniculate genus in the subfamily Corallinoideae (Corallinales, Rhodophyta)

Molecular phylogenetic analyses of 18S rDNA (SSU) gene sequences confirm the placement of Crusticorallina gen. nov. in Corallinoideae, the first non-geniculate genus in an otherwise geniculate subfamily. Crusticorallina is distinguished from all other coralline genera by the following suite of morpho-anatomical characters: 1) sunken, uniporate gametangial and bi/tetrasporangial conceptacles, 2) cells linked by cell fusions, not secondary pit connections, 3) an epithallus of 1 or 2 cell layers, 4) a hypothallus that occupies 50% or more of the total thallus thickness, 5) elongate meristematic cells, 6) trichocytes absent. Four species are recognized based on rbcL, psbA and COI-5P sequences, C. painei sp. nov., the generitype, C. adhaerens sp. nov., C. nootkana sp. nov. and C. muricata comb. nov., previously known as Pseudolithophyllum muricatum. Type material of Lithophyllum muricatum, basionym of C. muricata, in TRH comprises at least two taxa, and therefore we accept the previously designated lectotype specimen in UC that we sequenced to confirm its identity. Crusticorallina species are very difficult to distinguish using morpho-anatomical and/or habitat characters, although at specific sites, some species may be distinguished by a combination of morpho-anatomy, habitat and biogeography. The Northeast Pacific now boasts six coralline endemic genera, far more than any other region of the world. This article is protected by copyright. All rights reserved

A Guide to the Brain Initiative Cell Census Network Data Ecosystem

Characterizing cellular diversity at different levels of biological organization and across data modalities is a prerequisite to understanding the function of cell types in the brain. Classification of neurons is also essential to manipulate cell types in controlled ways and to understand their variation and vulnerability in brain disorders. The BRAIN Initiative Cell Census Network (BICCN) is an integrated network of data-generating centers, data archives, and data standards developers, with the goal of systematic multimodal brain cell type profiling and characterization. Emphasis of the BICCN is on the whole mouse brain with demonstration of prototype feasibility for human and nonhuman primate (NHP) brains. Here, we provide a guide to the cellular and spatial approaches employed by the BICCN, and to accessing and using these data and extensive resources, including the BRAIN Cell Data Center (BCDC), which serves to manage and integrate data across the ecosystem. We illustrate the power of the BICCN data ecosystem through vignettes highlighting several BICCN analysis and visualization tools. Finally, we present emerging standards that have been developed or adopted toward Findable, Accessible, Interoperable, and Reusable (FAIR) neuroscience. The combined BICCN ecosystem provides a comprehensive resource for the exploration and analysis of cell types in the brain

Ancient origin of the biosynthesis of lignin precursors

BACKGROUND: Lignin plays an important role in plant structural support and water transport, and is considered one of the hallmarks of land plants. The recent discovery of lignin or its precursors in various algae has raised questions on the evolution of its biosynthetic pathway, which could be much more ancient than previously thought. To determine the taxonomic distribution of the lignin biosynthesis genes, we screened all publicly available genomes of algae and their closest non-photosynthetic relatives, as well as representative land plants. We also performed phylogenetic analysis of these genes to decipher the evolution and origin(s) of lignin biosynthesis. RESULTS: Enzymes involved in making p-coumaryl alcohol, the simplest lignin monomer, are found in a variety of photosynthetic eukaryotes, including diatoms, dinoflagellates, haptophytes, cryptophytes as well as green and red algae. Phylogenetic analysis of these enzymes suggests that they are ancient and spread to some secondarily photosynthetic lineages when they acquired red and/or green algal endosymbionts. In some cases, one or more of these enzymes was likely acquired through lateral gene transfer (LGT) from bacteria. CONCLUSIONS: Genes associated with p-coumaryl alcohol biosynthesis are likely to have evolved long before the transition of photosynthetic eukaryotes to land. The original function of this lignin precursor is therefore unlikely to have been related to water transport. We suggest that it participates in the biological defense of some unicellular and multicellular algae. REVIEWERS: This article was reviewed by Mark Ragan, Uri Gophna, Philippe Deschamps

26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15–20 July 2017

This work was produced as part of the activities of FAPESP Research,\ud Disseminations and Innovation Center for Neuromathematics (grant\ud 2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud supported by a CNPq fellowship (grant 306251/2014-0)

Drag Reduction in Wave-Swept Macroalgae: Alternative Strategies and New Predictions

Premise of the study: Intertidal macroalgae must resist extreme hydrodynamic forces imposed by crashing waves. How does frond flexibility mitigate drag, and how does flexibility affect predictions of drag and dislodgement in the field? Methods: We characterized flexible reconfiguration of six seaweed species in a recirculating water flume, documenting both shape change and area reduction as fronds reorient. We then used a high-speed gravity-accelerated water flume to test our ability to predict drag under waves based on extrapolations of drag recorded at slower speeds. We compared dislodgement forces to drag forces predicted from slow- and high-speed data to generate new predictions of survivorship and maximum sustainable frond size along wave-swept shores. Key results: Bladed algae were generally shape changers , limiting drag by reducing drag coefficients, whereas the branched alga Calliarthron was an area reducer , limiting drag by reducing projected area in flow. Drag predictions often underestimated actual drag measurements at high speeds, suggesting that slow- speed data may not reflect the performance of flexible seaweeds under breaking waves. Several seaweeds were predicted to dislodge at similar combinations of velocity and frond size, suggesting common scaling factors of dislodgement strength and drag. Conclusions: Changing shape and reducing projected area in flow are two distinct strategies employed by flexible seaweeds to resist drag. Flexible reconfiguration contributes to the uncertainty of drag extrapolation, and researchers should use caution when predicting drag and dislodgement of seaweeds in the field

Ancient origin of the biosynthesis of lignin precursors

Background: Lignin plays an important role in plant structural support and water transport, and is considered one of the hallmarks of land plants. The recent discovery of lignin or its precursors in various algae has raised questions on the evolution of its biosynthetic pathway, which could be much more ancient than previously thought. To determine the taxonomic distribution of the lignin biosynthesis genes, we screened all publicly available genomes of algae and their closest non-photosynthetic relatives, as well as representative land plants. We also performed phylogenetic analysis of these genes to decipher the evolution and origin(s) of lignin biosynthesis. Results: Enzymes involved in making p-coumaryl alcohol, the simplest lignin monomer, are found in a variety of photosynthetic eukaryotes, including diatoms, dinoflagellates, haptophytes, cryptophytes as well as green and red algae. Phylogenetic analysis of these enzymes suggests that they are ancient and spread to some secondarily photosynthetic lineages when they acquired red and/or green algal endosymbionts. In some cases, one or more of these enzymes was likely acquired through lateral gene transfer (LGT) from bacteria. Conclusions: Genes associated with p-coumaryl alcohol biosynthesis are likely to have evolved long before the transition of photosynthetic eukaryotes to land. The original function of this lignin precursor is therefore unlikely to have been related to water transport. We suggest that it participates in the biological defense of some unicellular and multicellular algae. Reviewers: This article was reviewed by Mark Ragan, Uri Gophna, Philippe Deschamps.Botany, Department ofNon UBCScience, Faculty ofReviewedFacult

Cell wall chemistry and tissue structure underlie shifts in material properties of a perennial kelp

<p><i>Laminaria</i> is an abundant kelp genus in temperate nearshore ecosystems that grows with a circannual ‘stop-start’ pattern. Species of <i>Laminaria</i> play important ecological roles in kelp forests worldwide and are harvested commercially as a source of food and valuable extracts. In order to evaluate seasonal differences in tissue properties and composition, we compared the material properties, histology and cell-wall composition of overwintering blades with newly synthesized, actively growing blades from <i>Laminaria setchellii</i>. We found that overwintering blades were fortified with a thicker cortex and increased cell wall investment, leading to increased material strength. Overwintering tissues were composed of higher proportions of cellulose and fucose-containing polysaccharides (i.e. FCSPs, fucoidans) than newly formed blades and were found to possess thicker cell walls, likely to withstand the waves of winter storms. Chemical cell wall profiling revealed that significant proportions of fucose were associated with cellulose, especially in overwintering tissues, confirming the association between cellulose and some fucose-containing polysaccharides. Changes in material properties during the resting phase may allow these kelps to retain their non-growing blades through several months of winter storms. The results of this study demonstrate how one species might regulate its material properties seasonally, and at the same time shed light on the mechanisms that might control the material properties of kelps in general.</p

Seawater carbonate chemistry and the growth, calcification, and biomechanics of two species of articulated coralline algae

Ocean warming and acidification are predicted to impact the physiology of marine organisms, especially marine calcifiers that must deposit calcium carbonate and resist dissolution. Of particular concern are articulated coralline algae, which must maintain both calcified segments (intergenicula) and uncalcified joints (genicula) in order to thrive along wave-swept rocky coastlines. We examined the effect of pH and temperature, both individually and in combination, on the growth, calcification, and biomechanical properties of 2 species of articulated coralline algae, Corallina vancouveriensis and Calliarthron tuberculosum, common on wave-exposed shores in the NE Pacific. Increased temperature and reduced pH were found to reduce growth rates in both species (30-89% lower) but had little influence on the amount of intergenicular calcium carbonate or on the genicular biomechanical properties of these species. Results suggest that although growth rates may decline, these 2 coralline species will maintain the integrity of their tissues and continue to persist under future climate stress

Dataset in support of Guenther, R.G. et al., 2022. "Effects of temperature and pH on the growth, calcification, and biomechanics of two species of articulated coralline algae"

This dataset supports the manuscript: Guenther, R.G. et al., 2022. "Effects of temperature and pH on the growth, calcification, and biomechanics of two species of articulated coralline algae" in Marine Ecology Progress Series. DOI: https://doi.org/10.3354/meps14166. Full author listing is Rebecca Guenther, Elliot M. A. Porcher, Emily Carrington, Patrick T. Martone