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1.
Curr Biol ; 29(9): 1503-1511.e6, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-31006567

RESUMO

Rapid Na+/Ca2+-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+/Ca2+ channels (4D-Cavs/Navs). These channels are widely distributed across eukaryote diversity [4], albeit several eukaryotes, including land plants and fungi, have lost voltage-sensitive 4D-Cav/Navs [5-7]. Because these lineages appear to lack rapid Na+/Ca2+-based action potentials, 4D-Cav/Navs are generally considered necessary for fast Na+/Ca2+-based signaling [7]. However, the cellular mechanisms underpinning the membrane physiology of many eukaryotes remain unexamined. Eukaryotic phytoplankton critically influence our climate as major primary producers. Several taxa, including the globally abundant diatoms, exhibit membrane excitability [8-10]. We previously demonstrated that certain diatom genomes encode 4D-Cav/Navs [4] but also proteins of unknown function, resembling prokaryote single-domain, voltage-gated Na+ channels (BacNavs) [4]. Here, we show that single-domain channels are actually broadly distributed across major eukaryote phytoplankton lineages and represent three novel classes of single-domain channels, which we refer collectively to as EukCats. Functional characterization of diatom EukCatAs indicates that they are voltage-gated Na+- and Ca2+-permeable channels, with rapid kinetics resembling metazoan 4D-Cavs/Navs. In Phaeodactylum tricornutum, which lacks 4D-Cav/Navs, EukCatAs underpin voltage-activated Ca2+ signaling important for membrane excitability, and mutants exhibit impaired motility. EukCatAs therefore provide alternative mechanisms for rapid Na+/Ca2+ signaling in eukaryotes and may functionally replace 4D-Cavs/Navs in pennate diatoms. Marine phytoplankton thus possess unique signaling mechanisms that may be key to environmental sensing in the oceans.

2.
Curr Biol ; 28(19): R1145-R1147, 2018 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-30300599

RESUMO

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.


Assuntos
Chenopodium quinoa , Fenômenos Fisiológicos Vegetais , Salinidade , Cloreto de Sódio , Bexiga Urinária
3.
New Phytol ; 220(1): 147-162, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29916209

RESUMO

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. To determine whether the requirement for calcification differs between coccolithophore species, we utilized multiple independent methodologies to disrupt calcification in two important species of coccolithophore: E. huxleyi and Coccolithus braarudii. We investigated their physiological response and used time-lapse imaging to visualize the processes of calcification and cell division in individual cells. Disruption of calcification resulted in major growth defects in C. braarudii, but not in E. huxleyi. We found no evidence that calcification supports photosynthesis in C. braarudii, but showed that an inability to maintain an intact coccosphere results in cell cycle arrest. We found that C. braarudii is very different from E. huxleyi as it exhibits an obligate requirement for calcification. The identification of a growth defect in C. braarudii resulting from disruption of the coccosphere may be important in considering their response to future changes in ocean carbonate chemistry.


Assuntos
Calcificação Fisiológica , Haptófitas/fisiologia , Calcificação Fisiológica/efeitos dos fármacos , Cálcio/farmacologia , Adesão Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Ecologia , Germânio/farmacologia , Haptófitas/citologia , Haptófitas/crescimento & desenvolvimento , Haptófitas/ultraestrutura , Fotossíntese/efeitos dos fármacos , Polissacarídeos/metabolismo , Silício/farmacologia , Tubulina (Proteína)/metabolismo
4.
Curr Biol ; 28(9): R551-R553, 2018 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-29738727

RESUMO

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.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Aminoácidos , Ânions , Grão Comestível , Proteínas de Membrana , Estômatos de Plantas , Poaceae
5.
Nat Commun ; 9(1): 74, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29311545

RESUMO

Photosynthesis by marine diatoms plays a major role in the global carbon cycle, although the precise mechanisms of dissolved inorganic carbon (DIC) uptake remain unclear. A lack of direct measurements of carbonate chemistry at the cell surface has led to uncertainty over the underlying membrane transport processes and the role of external carbonic anhydrase (eCA). Here we identify rapid and substantial photosynthesis-driven increases in pH and [CO32-] primarily due to the activity of eCA at the cell surface of the large diatom Odontella sinensis using direct simultaneous microelectrode measurements of pH and CO32- along with modelling of cell surface inorganic carbonate chemistry. Our results show that eCA acts to maintain cell surface CO2 concentrations, making a major contribution to DIC supply in O. sinensis. Carbonate chemistry at the cell surface is therefore highly dynamic and strongly dependent on cell size, morphology and the carbonate chemistry of the bulk seawater.


Assuntos
Carbonatos/metabolismo , Microambiente Celular , Diatomáceas/metabolismo , Fitoplâncton/metabolismo , Transporte Biológico , Carbono/química , Carbono/metabolismo , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Carbonatos/química , Anidrases Carbônicas/metabolismo , Diatomáceas/citologia , Concentração de Íons de Hidrogênio , Modelos Biológicos , Fotossíntese , Fitoplâncton/citologia , Água do Mar/química
6.
Sci Rep ; 7(1): 15409, 2017 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-29133928

RESUMO

The production of calcium carbonate by coccolithophores (haptophytes) contributes significantly to global biogeochemical cycling. The recent identification of a silicifying haptophyte, Prymnesium neolepis, has provided new insight into the evolution of biomineralisation in this lineage. However, the cellular mechanisms of biomineralisation in both calcifying and silicifying haptophytes remain poorly understood. To look for commonalities between these two biomineralisation systems in haptophytes, we have determined the role of actin and tubulin in the formation of intracellular biomineralised scales in the coccolithophore, Coccolithus braarudii and in P. neolepis. We find that disruption of the actin network interferes with secretion of the biomineralised elements in both C. braarudii and P. neolepis. In contrast, disruption of the microtubule network does not prevent secretion of the silica scales in P. neolepis but results in production of abnormally small silica scales and also results in the increased formation of malformed coccoliths in C. braarudii. We conclude that the cytoskeleton plays a crucial role in biomineralisation in both silicifying and calcifying haptophytes. There are some important similarities in the contribution of the cytoskeleton to these different forms of biomineralisation, suggesting that common cellular mechanisms may have been recruited to perform similar roles in both lineages.


Assuntos
Biomineralização/fisiologia , Citoesqueleto/metabolismo , Haptófitas/fisiologia , Microalgas/fisiologia , Actinas/metabolismo , Carbonato de Cálcio/metabolismo , Dióxido de Silício/metabolismo , Tubulina (Proteína)/metabolismo
7.
Curr Biol ; 27(15): R763-R764, 2017 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-28787608

RESUMO

The Venus flytrap effectively detects, traps, digests and absorbs insect prey. A recent study links the mechanical stimulation of sensory hair cells with short- and long-term signalling giving rise to different downstream secretion events that bring about conditions for prey digestion.


Assuntos
Droseraceae , Animais , Exocitose , Insetos , Fenômenos Fisiológicos Vegetais , Transdução de Sinais
8.
Curr Biol ; 27(13): R667-R679, 2017 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-28697370

RESUMO

The calcium-based intracellular signalling system is used ubiquitously to couple extracellular stimuli to their characteristic intracellular responses. It is becoming clear from genomic and physiological investigations that while the basic elements in the toolkit are common between plants and animals, evolution has acted in such a way that, in plants, some components have diversified with respect to their animal counterparts, while others have either been lost or have never evolved in the plant lineages. In comparison with animals, in plants there appears to have been a loss of diversity in calcium-influx mechanisms at the plasma membrane. However, the evolution of the calcium-storing vacuole may provide plants with additional possibilities for regulating calcium influx into the cytosol. Among the proteins that are involved in sensing and responding to increases in calcium, plants possess specific decoder proteins that are absent from the animal lineage. In seeking to understand the selection pressures that shaped the plant calcium-signalling toolkit, we consider the evolution of fast electrical signalling. We also note that, in contrast to animals, plants apparently do not make extensive use of cyclic-nucleotide-based signalling. It is possible that reliance on a single intracellular second-messenger-based system, coupled with the requirement to adapt to changing environmental conditions, has helped to define the diversity of components found in the extant plant calcium-signalling toolkit.


Assuntos
Sinalização do Cálcio , Evolução Molecular , Fenômenos Fisiológicos Vegetais , Plantas/metabolismo
9.
ISME J ; 11(12): 2869-2873, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28742072

RESUMO

Phaeoviruses are latent double-stranded DNA viruses that insert their genomes into those of their brown algal (Phaeophyceae) hosts. So far these viruses are known only from members of the Ectocarpales, which are small and short-lived macroalgae. Here we report molecular and morphological evidence for a new Phaeovirus cluster, referred to as sub-group C, infecting kelps (Laminariales) of the genera Laminaria and Saccharina, which are ecologically and commercially important seaweeds. Epifluorescence and TEM observations indicate that the Laminaria digitata Virus (LdigV), the type species of sub-group C, targets the host nucleus for its genome replication, followed by gradual degradation of the chloroplast and assembly of virions in the cytoplasm of both vegetative and reproductive cells. This study is the first to describe phaeoviruses in kelp. In the field, these viruses infected two thirds of their host populations; however, their biological impact remains unknown.


Assuntos
Vírus de DNA/isolamento & purificação , Kelp/virologia , Alga Marinha/virologia , Vírus de DNA/classificação , Vírus de DNA/genética , Filogenia
10.
Ann Rev Mar Sci ; 9: 283-310, 2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-27814031

RESUMO

Coccolithophores occupy a special position within the marine phytoplankton because of their production of intricate calcite scales, or coccoliths. Coccolithophores are major contributors to global ocean calcification and long-term carbon fluxes. The intracellular production of coccoliths requires modifications to cellular ultrastructure and metabolism that are surveyed here. In addition to calcification, which appears to have evolved with a diverse range of functions, several other remarkable features that likely underpin the ecological and evolutionary success of coccolithophores have recently been uncovered. These include complex and varied life cycle strategies related to abiotic and biotic interactions as well as a range of novel metabolic pathways and nutritional strategies. Together with knowledge of coccolithophore genetic and physiological variability, these findings are beginning to shed new light on species diversity, distribution, and ecological adaptation. Further advances in genetics and functional characterization at the cellular level will likely to lead to a rapid increase in this understanding.


Assuntos
Calcificação Fisiológica , Carbonato de Cálcio , Haptófitas/fisiologia , Ciclo do Carbono , Fitoplâncton
11.
New Phytol ; 212(4): 920-933, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27516045

RESUMO

Ca2+ -dependent signalling processes enable plants to perceive and respond to diverse environmental stressors, such as osmotic stress. A clear understanding of the role of spatiotemporal Ca2+ signalling in green algal lineages is necessary in order to understand how the Ca2+ signalling machinery has evolved in land plants. We used single-cell imaging of Ca2+ -responsive fluorescent dyes in the unicellular green alga Chlamydomonas reinhardtii to examine the specificity of spatial and temporal dynamics of Ca2+ elevations in the cytosol and flagella in response to salinity and osmotic stress. We found that salt stress induced a single Ca2+ elevation that was modulated by the strength of the stimulus and originated in the apex of the cell, spreading as a fast Ca2+ wave. By contrast, hypo-osmotic stress induced a series of repetitive Ca2+ elevations in the cytosol that were spatially uniform. Hypo-osmotic stimuli also induced Ca2+ elevations in the flagella that occurred independently from those in the cytosol. Our results indicate that the requirement for Ca2+ signalling in response to osmotic stress is conserved between land plants and green algae, but the distinct spatial and temporal dynamics of osmotic Ca2+ elevations in C. reinhardtii suggest important mechanistic differences between the two lineages.


Assuntos
Sinalização do Cálcio , Chlamydomonas reinhardtii/fisiologia , Pressão Osmótica/efeitos dos fármacos , Estresse Fisiológico , Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Chlamydomonas reinhardtii/efeitos dos fármacos , Flagelos/efeitos dos fármacos , Flagelos/metabolismo , Mecanotransdução Celular/efeitos dos fármacos , Filogenia , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Fatores de Tempo
12.
Sci Adv ; 2(7): e1501822, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27453937

RESUMO

Calcifying marine phytoplankton-coccolithophores- are some of the most successful yet enigmatic organisms in the ocean and are at risk from global change. To better understand how they will be affected, we need to know "why" coccolithophores calcify. We review coccolithophorid evolutionary history and cell biology as well as insights from recent experiments to provide a critical assessment of the costs and benefits of calcification. We conclude that calcification has high energy demands and that coccolithophores might have calcified initially to reduce grazing pressure but that additional benefits such as protection from photodamage and viral/bacterial attack further explain their high diversity and broad spectrum ecology. The cost-benefit aspect of these traits is illustrated by novel ecosystem modeling, although conclusive observations remain limited. In the future ocean, the trade-off between changing ecological and physiological costs of calcification and their benefits will ultimately decide how this important group is affected by ocean acidification and global warming.


Assuntos
Calcificação Fisiológica/fisiologia , Haptófitas/metabolismo , Carbonato de Cálcio/química , Ecossistema , Aquecimento Global , Concentração de Íons de Hidrogênio , Oceanos e Mares , Fotossíntese , Água do Mar/química
13.
Nat Commun ; 7: 10543, 2016 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-26842659

RESUMO

Biomineralization by marine phytoplankton, such as the silicifying diatoms and calcifying coccolithophores, plays an important role in carbon and nutrient cycling in the oceans. Silicification and calcification are distinct cellular processes with no known common mechanisms. It is thought that coccolithophores are able to outcompete diatoms in Si-depleted waters, which can contribute to the formation of coccolithophore blooms. Here we show that an expanded family of diatom-like silicon transporters (SITs) are present in both silicifying and calcifying haptophyte phytoplankton, including some globally important coccolithophores. Si is required for calcification in these coccolithophores, indicating that Si uptake contributes to the very different forms of biomineralization in diatoms and coccolithophores. Significantly, SITs and the requirement for Si are absent from highly abundant bloom-forming coccolithophores, such as Emiliania huxleyi. These very different requirements for Si in coccolithophores are likely to have major influence on their competitive interactions with diatoms and other siliceous phytoplankton.


Assuntos
Calcificação Fisiológica , Diatomáceas/metabolismo , Haptófitas/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Silício/metabolismo , Eletroforese em Gel de Poliacrilamida , Perfilação da Expressão Gênica , Haptófitas/genética , Haptófitas/ultraestrutura , Proteínas de Membrana Transportadoras/genética , Microscopia Eletrônica , Microscopia de Fluorescência , Fitoplâncton , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Água do Mar/química
14.
Semin Cell Dev Biol ; 46: 11-6, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26498037

RESUMO

Coccolithophores are unicellular phytoplankton that are characterized by the presence intricately formed calcite scales (coccoliths) on their surfaces. In most cases coccolith formation is an entirely intracellular process - crystal growth is confined within a Golgi-derived vesicle. A wide range of coccolith morphologies can be found amongst the different coccolithophore groups. This review discusses the cellular factors that regulate coccolith production, from the roles of organic components, endomembrane organization and cytoskeleton to the mechanisms of delivery of substrates to the calcifying compartment. New findings are also providing important information on how the delivery of substrates to the calcification site is co-ordinated with the removal of H(+) that are a bi-product of the calcification reaction. While there appear to be a number of species-specific features of the structural and biochemical components underlying coccolith formation, the fluxes of Ca(2+) and a HCO3(-) required to support coccolith formation appear to involve spatially organized recruitment of conserved transport processes.


Assuntos
Cálcio/metabolismo , Complexo de Golgi/metabolismo , Haptófitas/metabolismo , Fitoplâncton/metabolismo , Antiporters/metabolismo , Transporte Biológico , Calcificação Fisiológica , Proteínas de Transporte de Cátions/metabolismo , Complexo de Golgi/ultraestrutura , Haptófitas/citologia , Haptófitas/ultraestrutura , Microscopia Eletrônica de Varredura , Modelos Biológicos , Fitoplâncton/citologia , Fitoplâncton/ultraestrutura , ATPases Vacuolares Próton-Translocadoras/metabolismo
15.
Proc Biol Sci ; 282(1804): 20142604, 2015 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-25716793

RESUMO

Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO2 into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake of dissolved inorganic carbon during photosynthesis increases water-column pH (bloom-induced basification). This increased pH can adversely affect plankton growth. With OA, basification commences at a lower pH. Using experimental analyses of the growth of three contrasting phytoplankton under different pH scenarios, coupled with mathematical models describing growth and death as functions of pH and nutrient status, we show how different conditions of pH modify the scope for competitive interactions between phytoplankton species. We then use the models previously configured against experimental data to explore how the commencement of bloom-induced basification at lower pH with OA, and operating against a background of changing patterns in nutrient loads, may modify phytoplankton growth and competition. We conclude that OA and changed nutrient supply into shelf seas with eutrophication or de-eutrophication (the latter owing to pollution control) has clear scope to alter phytoplankton succession, thus affecting future trophic dynamics and impacting both biogeochemical cycling and fisheries.


Assuntos
Biodiversidade , Eutrofização , Fitoplâncton/fisiologia , Água do Mar/química , Carbonatos/química , Concentração de Íons de Hidrogênio , Modelos Teóricos , Fitoplâncton/crescimento & desenvolvimento
16.
Ecol Evol ; 4(13): 2787-98, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25077027

RESUMO

Seaweed and seagrass communities in the northeast Atlantic have been profoundly impacted by humans, and the rate of change is accelerating rapidly due to runaway CO2 emissions and mounting pressures on coastlines associated with human population growth and increased consumption of finite resources. Here, we predict how rapid warming and acidification are likely to affect benthic flora and coastal ecosystems of the northeast Atlantic in this century, based on global evidence from the literature as interpreted by the collective knowledge of the authorship. We predict that warming will kill off kelp forests in the south and that ocean acidification will remove maerl habitat in the north. Seagrasses will proliferate, and associated epiphytes switch from calcified algae to diatoms and filamentous species. Invasive species will thrive in niches liberated by loss of native species and spread via exponential development of artificial marine structures. Combined impacts of seawater warming, ocean acidification, and increased storminess may replace structurally diverse seaweed canopies, with associated calcified and noncalcified flora, with simple habitats dominated by noncalcified, turf-forming seaweeds.

17.
PLoS One ; 9(3): e90749, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24618939

RESUMO

Diatoms can occur as single cells or as chain-forming aggregates. These two strategies affect buoyancy, predator evasion, light absorption and nutrient uptake. Adjacent cells in chains establish connections through various processes that determine strength and flexibility of the bonds, and at distinct cellular locations defining colony structure. Chain length has been found to vary with temperature and nutrient availability as well as being positively correlated with growth rate. However, the potential effect of enhanced carbon dioxide (CO2) concentrations and consequent changes in seawater carbonate chemistry on chain formation is virtually unknown. Here we report on experiments with semi-continuous cultures of the freshly isolated diatom Asterionellopsis glacialis grown under increasing CO2 levels ranging from 320 to 3400 µatm. We show that the number of cells comprising a chain, and therefore chain length, increases with rising CO2 concentrations. We also demonstrate that while cell division rate changes with CO2 concentrations, carbon, nitrogen and phosphorus cellular quotas vary proportionally, evident by unchanged organic matter ratios. Finally, beyond the optimum CO2 concentration for growth, carbon allocation changes from cellular storage to increased exudation of dissolved organic carbon. The observed structural adjustment in colony size could enable growth at high CO2 levels, since longer, spiral-shaped chains are likely to create microclimates with higher pH during the light period. Moreover increased chain length of Asterionellopsis glacialis may influence buoyancy and, consequently, affect competitive fitness as well as sinking rates. This would potentially impact the delicate balance between the microbial loop and export of organic matter, with consequences for atmospheric carbon dioxide.


Assuntos
Dióxido de Carbono/química , Diatomáceas/crescimento & desenvolvimento , Água do Mar/química , Dióxido de Carbono/farmacologia , Carbonatos/química , Carbonatos/metabolismo , Divisão Celular , Diatomáceas/efeitos dos fármacos , Diatomáceas/metabolismo
18.
PLoS One ; 9(1): e86040, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24465858

RESUMO

Phaeoviruses infect the brown algae, which are major contributors to primary production of coastal waters and estuaries. They exploit a Persistent evolutionary strategy akin to a K- selected life strategy via genome integration and are the only known representatives to do so within the giant algal viruses that are typified by r- selected Acute lytic viruses. In screening the genomes of five species within the filamentous brown algal lineage, here we show an unprecedented diversity of viral gene sequence variants especially amongst the smaller phaeoviral genomes. Moreover, one variant shares features from both the two major sub-groups within the phaeoviruses. These phaeoviruses have exploited the reduction of their giant dsDNA genomes and accompanying loss of DNA proofreading capability, typical of an Acute life strategist, but uniquely retain a Persistent life strategy.


Assuntos
Evolução Biológica , Phycodnaviridae/genética , Sequência de Aminoácidos , Sequência de Bases , DNA Polimerase Dirigida por DNA/química , DNA Polimerase Dirigida por DNA/genética , Genes Virais , Funções Verossimilhança , Microscopia de Fluorescência , Dados de Sequência Molecular , Phycodnaviridae/enzimologia , Filogenia , Alinhamento de Sequência
19.
Curr Biol ; 23(22): 2311-2318, 2013 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-24210618

RESUMO

Intraflagellar transport (IFT) underpins many of the important cellular roles of cilia and flagella in signaling and motility. The microtubule motors kinesin-2 and cytoplasmic dynein 1b drive IFT particles (protein complexes carrying ciliary component proteins) along the axoneme to facilitate the assembly and maintenance of cilia. IFT is regulated primarily by cargo loading onto the IFT particles, although evidence suggests that IFT particles also exhibit differential rates of movement. Here we demonstrate that intraflagellar Ca(2+) elevations act to directly regulate the movement of IFT particles. IFT-driven movement of adherent flagella membrane glycoproteins in the model alga Chlamydomonas enables flagella-mediated gliding motility. We find that surface contact promotes the localized accumulation of IFT particles in Chlamydomonas flagella. Highly compartmentalized intraflagellar Ca(2+) elevations initiate retrograde transport of paused IFT particles to modulate their accumulation. Gliding motility induces mechanosensitive intraflagellar Ca(2+) elevations in trailing (dragging) flagella only, acting to specifically clear the accumulated microtubule motors from individual flagella and prevent a futile tug-of-war. Our results demonstrate that compartmentalized intraciliary Ca(2+) signaling can regulate the movement of IFT particles and is therefore likely to play a central role in directing the movement and distribution of many ciliary proteins.


Assuntos
Sinalização do Cálcio , Chlamydomonas/citologia , Chlamydomonas/metabolismo , Flagelos/metabolismo , Transporte Biológico/fisiologia , Cílios/metabolismo , Potenciais da Membrana
20.
Curr Biol ; 23(17): R714-6, 2013 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-24028948

RESUMO

The Venus flytrap digests and absorbs its prey, but how does it coordinate digestion and absorption to maximise the efficiency of this highly evolved mechanism? A new study that combines direct recordings from cells within the trap along with molecular characterization of nutrient transport reveals a complex and coordinated suite of mechanisms that underlie this elegant process.


Assuntos
Compostos de Amônio/metabolismo , Droseraceae/metabolismo , Canais Iônicos/metabolismo , Animais
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