Cellular calcium homeostasis and regulation of its dynamic perturbation.

Calcium ions (Ca) play pivotal roles in a host of cellular signalling processes. The requirement to maintain resting cytosolic Ca levels in the 100-200 nM range provides a baseline for dynamic excursions from resting levels that determine the nature of many physiological responses to external stimuli and developmental processes. This review provides an overview of the key components of the Ca homeostatic machinery, including known channel-mediated Ca entry pathways along with transporters that act to shape the cytosolic Ca signature.

Plant-like heliotropism in a photosymbiotic animal.

As in plants, photosynthesis also represents a key energy source in photosymbiotic cnidarians bearing microalgae. We observed that the cnidarian sea anemone Anemonia viridis, commonly known as the snakelocks anemone, displayed heliotropism or solar tracking in their natural habitats. When exposed to sunlight, A.

The requirement for external carbonic anhydrase in diatoms is influenced by the supply and demand for dissolved inorganic carbon.

Photosynthesis by marine diatoms contributes significantly to the global carbon cycle. Due to the low concentration of CO in seawater, many diatoms use extracellular carbonic anhydrase (eCA) to enhance the supply of CO to the cell surface. While much research has investigated how the requirement for eCA is influenced by changes in CO availability, little is known about how eCA contributes to CO supply following changes in the demand for carbon.

Mesoscale oceanographic meanders influence protist community function and structure in the southern Indian Ocean.

The interface between the nutrient-rich Southern Ocean and oligotrophic Indian Ocean creates unique environmental conditions that can strongly influence biological processes. We investigated protist communities across a mesoscale meander of the Subtropical Front within the Southern Indian Ocean. 18S V9 rDNA metabarcoding suggests a diverse protist community in which the dinoflagellates and parasitic Syndiniales were abundant.

-Bacteria Interactions under Increasing CO Concentrations.

The interactions established between marine microbes, namely phytoplankton-bacteria, are key to the balance of organic matter export to depth and recycling in the surface ocean. Still, their role in the response of phytoplankton to rising CO concentrations is poorly understood. Here, we show that the response of the cosmopolitan () to increasing CO is affected by the coexistence with bacteria.

Characterization of the molecular mechanisms of silicon uptake in coccolithophores.

Coccolithophores are an important group of calcifying marine phytoplankton. Although coccolithophores are not silicified, some species exhibit a requirement for Si in the calcification process. These species also possess a novel protein (SITL) that resembles the SIT family of Si transporters found in diatoms.

The Effect of cytoskeleton inhibitors on coccolith morphology in Coccolithus braarudii and Scyphosphaera apsteinii.

The calcite platelets of coccolithophores (Haptophyta), the coccoliths, are among the most elaborate biomineral structures. How these unicellular algae accomplish the complex morphogenesis of coccoliths is still largely unknown. It has long been proposed that the cytoskeleton plays a central role in shaping the growing coccoliths.

Plant physiology: Anatomy of a plant action potential.

The Venus flytrap possesses modified leaves that can snap shut fast enough to catch a fly. A new study identifies the major components of the toolkit that allows the flytrap to fire action potentials, illustrating how different ion channels and transporters are recruited to give rise to this unique plant behavioural response.

Cold-induced [Ca2+]cyt elevations function to support osmoregulation in marine diatoms.

Diatoms are a group of microalgae that are important primary producers in a range of open ocean, freshwater, and intertidal environments. The latter can experience substantial long- and short-term variability in temperature, from seasonal variations to rapid temperature shifts caused by tidal immersion and emersion. As temperature is a major determinant in the distribution of diatom species, their temperature sensory and response mechanisms likely have important roles in their ecological success.

Reduced H channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH.

Coccolithophores are major producers of ocean biogenic calcite, but this process is predicted to be negatively affected by future ocean acidification scenarios. Since coccolithophores calcify intracellularly, the mechanisms through which changes in seawater carbonate chemistry affect calcification remain unclear. Here we show that voltage-gated H+ channels in the plasma membrane of Coccolithus braarudii serve to regulate pH and maintain calcification under normal conditions but have greatly reduced activity in cells acclimated to low pH.

Regulation and integration of membrane transport in marine diatoms.

Diatoms represent one of the most successful groups of marine phytoplankton and are major contributors to ocean biogeochemical cycling. They have colonized marine, freshwater and ice environments and inhabit all regions of the World's oceans, from poles to tropics. Their success is underpinned by a remarkable ability to regulate their growth and metabolism during nutrient limitation and to respond rapidly when nutrients are available.

Ca elevations disrupt interactions between intraflagellar transport and the flagella membrane in .

The movement of ciliary membrane proteins is directed by transient interactions with intraflagellar transport (IFT) trains. The green alga has adapted this process for gliding motility, using retrograde IFT motors to move adhesive glycoproteins in the flagella membrane. Ca signalling contributes directly to the gliding process, although uncertainty remains over the mechanism through which it acts.

Spatiotemporal patterns of intracellular Ca signalling govern hypo-osmotic stress resilience in marine diatoms.

Diatoms are globally important phytoplankton that dominate coastal and polar-ice assemblages. These environments exhibit substantial changes in salinity over dynamic spatiotemporal regimes. Rapid sensory systems are vital to mitigate the harmful consequences of osmotic stress.

Role of silicon in the development of complex crystal shapes in coccolithophores.

The development of calcification by the coccolithophores had a profound impact on ocean carbon cycling, but the evolutionary steps leading to the formation of these complex biomineralized structures are not clear. Heterococcoliths consisting of intricately shaped calcite crystals are formed intracellularly by the diploid life cycle phase. Holococcoliths consisting of simple rhombic crystals can be produced by the haploid life cycle stage but are thought to be formed extracellularly, representing an independent evolutionary origin of calcification.

A Novel Ca Signaling Pathway Coordinates Environmental Phosphorus Sensing and Nitrogen Metabolism in Marine Diatoms.

Diatoms are a diverse and globally important phytoplankton group, responsible for an estimated 20% of carbon fixation on Earth. They frequently form spatially extensive phytoplankton blooms, responding rapidly to increased availability of nutrients, including phosphorus (P) and nitrogen (N). Although it is well established that diatoms are common first responders to nutrient influxes in aquatic ecosystems, little is known of the sensory mechanisms that they employ for nutrient perception.

A Novel Single-Domain Na-Selective Voltage-Gated Channel in Photosynthetic Eukaryotes.

The evolution of Na-selective four-domain voltage-gated channels (4D-Nas) in animals allowed rapid Na-dependent electrical excitability, and enabled the development of sophisticated systems for rapid and long-range signaling. While bacteria encode single-domain Na-selective voltage-gated channels (BacNa), they typically exhibit much slower kinetics than 4D-Nas, and are not thought to have crossed the prokaryote-eukaryote boundary. As such, the capacity for rapid Na-selective signaling is considered to be confined to certain animal taxa, and absent from photosynthetic eukaryotes.

Coccolithophore calcification: Changing paradigms in changing oceans.

Coccolithophores represent a major component of the marine phytoplankton and contribute to the bulk of biogenic calcite formation on Earth. These unicellular protists produce minute calcite scales (coccoliths) within the cell, which are secreted to the cell surface. Individual coccoliths and their arrangements on the cell surface display a wide range of morphological variations.

Publisher Correction: Genetic tool development in marine protists: emerging model organisms for experimental cell biology.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Genetic tool development in marine protists: emerging model organisms for experimental cell biology.

Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa.

Alternative Mechanisms for Fast Na/Ca Signaling in Eukaryotes via a Novel Class of Single-Domain Voltage-Gated Channels.

Rapid Na/Ca-based action potentials govern essential cellular functions in eukaryotes, from the motile responses of unicellular protists, such as Paramecium [1, 2], to complex animal neuromuscular activity [3]. A key innovation underpinning this fundamental signaling process has been the evolution of four-domain voltage-gated Na/Ca channels (4D-Cas/Nas). These channels are widely distributed across eukaryote diversity [4], albeit several eukaryotes, including land plants and fungi, have lost voltage-sensitive 4D-Ca/Nas [5-7].

Plant Physiology: One Way to Dump Salt.

Soil salinization is a major challenge to global food security. The quinoa plant tolerates saline conditions by dumping excess salt into specialised bladder cells on the leaves. The pathways and transporters underlying this one-way accumulation system are now becoming clearer.

The requirement for calcification differs between ecologically important coccolithophore species.

Coccolithophores are globally distributed unicellular marine algae that are characterized by their covering of calcite coccoliths. Calcification by coccolithophores contributes significantly to global biogeochemical cycles. However, the physiological requirement for calcification remains poorly understood as non-calcifying strains of some commonly used model species, such as Emiliania huxleyi, grow normally in laboratory culture.

Stomatal Physiology: Cereal Successes.

The grasses have been extremely successful in colonizing a wide range of terrestrial habitats, partially due to the unique physiology of their stomatal complexes. A new study has added new insight into the regulation of cereal stomata in showing that they are sensitive to nitrate concentration, and how a specific anion channel is responsible for this sensitivity.