An official website of the United States government
Summary We investigated the molecular basis and physiological implications of anion transport during pollen tube (PT) growth inArabidopsis thaliana(Col‐0).Patch‐clamp whole‐cell configuration analysis of pollen grain protoplasts revealed three subpopulations of anionic currents differentially regulated by cytoplasmic calcium ([Ca2+]cyt). We investigated the pollen‐expressed proteinsAtSLAH3,AtALMT12,AtTMEM16 andAtCCCas the putative anion transporters responsible for these currents.AtCCC‐GFPwas observed at the shank andAtSLAH3‐GFPat the tip and shank of thePTplasma membrane. Both are likely to carry the majority of anion current at negative potentials, as extracellular anionic fluxes measured at the tip ofPTs with an anion vibrating probe were significantly lower inslah3−/−andccc−/−mutants, but unaffected inalmt12−/−andtmem16−/−. We further characterised the effect ofpHandGABAby patch clamp. Strong regulation by extracellularpHwas observed in the wild‐type, but not intmem16−/−. Our results are compatible withAtTMEM16 functioning as an anion/H+cotransporter and therefore, as a putativepHsensor.GABApresence: (1) inhibited the overall currents, an effect that is abrogated in thealmt12−/−and (2) reduced the current inAtALMT12 transfectedCOS‐7 cells, strongly suggesting the direct interaction ofGABAwithAtALMT12.Our data show thatAtSLAH3 andAtCCCactivity is sufficient to explain the major component of extracellular anion fluxes, and unveils a possible regulatory system linkingPTgrowth modulation bypH,GABA, and [Ca2+]cytthrough anionic transporters.
more »
« less
This content will become publicly available on December 1, 2025
Nocturnal Cleaning Interactions Between the Giant Moray ( Gymnothorax javanicus ) and the Clear Cleaner Shrimp ( Urocaridella antonbruunii )
ABSTRACT We observed a novel, nocturnal cleaning interaction between a cleaner shrimp (GenusUrocaridella) and the giant moray eel (Gymnothorax javanicus) on a lagoonal patch reef in Moorea, French Polynesia. Over the course of an 85‐min foraging bout (recorded on video by a snorkeler), we observed three separate, stereotyped cleaning interactions betweenG. javanicusand a cleaner shrimp in the genus Urocaridella (which surveys of Moorea biodiversity previously visually identified asUrocaridella antonbruunii). During these interactions, the shrimp would slowly crawl along one of the eel's flanks towards its head, enter its mouth, emerge on the other side of its head, then crawl back towards the reef along the eel's opposite flank, often causing it to jolt in response. On each of the visits, the moray spent roughly 9–12 min at the cleaning station and was observed being cleaned for a total of 62 s. Although this was a chance observation of only a few instances of cleaning, it may have several important implications for our understanding of the behavioral ecology of cleaning mutualisms, including (1) indicating potential temporal trade‐offs between being cleaned and foraging in eels, (2) suggesting a degree of temporal niche partitioning among sympatric cleaner species and (3) updating our understanding of cleaner‐client communication, given the nocturnal nature of our observations.
more »
« less
- PAR ID:
- 10591140
- Publisher / Repository:
- Ecology and Evolution
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 14
- Issue:
- 12
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract ARGONAUTES are the central effector proteins ofRNAsilencing which bind target transcripts in a smallRNA‐guided manner.Arabidopsis thalianahas 10ARGONAUTE(AGO) genes, with specialized roles inRNA‐directedDNAmethylation, post‐transcriptional gene silencing, and antiviral defense. To better understand specialization amongAGOgenes at the level of transcriptional regulation we tested a library of 1497 transcription factors for binding to the promoters ofAGO1,AGO10, andAGO7using yeast 1‐hybrid assays. A ranked list of candidateDNA‐bindingTFs revealed binding of theAGO7promoter by a number of proteins in two families: the miR156‐regulatedSPLfamily and the miR319‐regulatedTCPfamily, both of which have roles in developmental timing and leaf morphology. Possible functions forSPLandTCPbinding are unclear: we showed that these binding sites are not required for the polar expression pattern ofAGO7, nor for the function ofAGO7in leaf shape. NormalAGO7transcription levels and function appear to depend instead on an adjacent 124‐bp region. Progress in understanding the structure of this promoter may aid efforts to understand how the conservedAGO7‐triggeredTAS3pathway functions in timing and polarity.more » « less
-
Abstract Anthropogenic climate change compromises reef growth as a result of increasing temperatures and ocean acidification. Scleractinian corals vary in their sensitivity to these variables, suggesting species composition will influence how reef communities respond to future climate change. Because data are lacking for many species, most studies that model future reef growth rely on uniform scleractinian calcification sensitivities to temperature and ocean acidification. To address this knowledge gap, calcification of twelve common and understudied Caribbean coral species was measured for two months under crossed temperatures (27, 30.3 °C) andCO2partial pressures (pCO2) (400, 900, 1300 μatm). Mixed‐effects models of calcification for each species were then used to project community‐level scleractinian calcification using Florida Keys reef composition data andIPCC AR5 ensemble climate model data. Three of the four most abundant species,Orbicella faveolata, Montastraea cavernosa,andPorites astreoides, had negative calcification responses to both elevated temperature andpCO2. In the business‐as‐usualCO2emissions scenario, reefs with high abundances of these species had projected end‐of‐century declines in scleractinian calcification of >50% relative to present‐day rates.Siderastrea siderea, the other most common species, was insensitive to both temperature andpCO2within the levels tested here. Reefs dominated by this species had the most stable end‐of‐century growth. Under more optimistic scenarios of reducedCO2emissions, calcification rates throughout the Florida Keys declined <20% by 2100. Under the most extreme emissions scenario, projected declines were highly variable among reefs, ranging 10–100%. Without considering bleaching, reef growth will likely decline on most reefs, especially where resistant species likeS. sidereaare not already dominant. This study demonstrates how species composition influences reef community responses to climate change and how reducedCO2emissions can limit future declines in reef calcification.more » « less
-
PremiseHerbarium specimens have been used to detect climate‐induced shifts in flowering time by using the day of year of collection (DOY) as a proxy for first or peak flowering date. Variation among herbarium sheets in their phenological status, however, undermines the assumption thatDOYaccurately represents any particular phenophase. Ignoring this variation can reduce the explanatory power of pheno‐climatic models (PCMs) designed to predict the effects of climate on flowering date. MethodsHere we present a protocol for the phenological scoring of imaged herbarium specimens using an ImageJ plugin, and we introduce a quantitative metric of a specimen's phenological status, the phenological index (PI), which we use inPCMs to control for phenological variation among specimens ofStreptanthus tortuosus(Brassicaceeae) when testing for the effects of climate onDOY. We demonstrate that includingPIas an independent variable improves model fit. ResultsIncludingPIinPCMs increased the modelR2relative toPCMs that excludedPI; regression coefficients for climatic parameters, however, remained constant. DiscussionOur protocol provides a simple, quantitative phenological metric for any observed plant. IncludingPIinPCMs increasesR2and enables predictions of theDOYof any phenophase under any specified climatic conditions.more » « less
-
Ninety‐six juvenile specimens (37–54 mm standard length;LS) of the rarely collected Upward‐Mouth SpikefishAtrophacanthus japonicus(Triacanthodidae) were obtained from the stomachs of three Yellowfin TunaThunnus albacarescollected off Guam in the Mariana Islands in the central Pacific Ocean. These specimens extend the range ofA. japonicuseastward into Oceania. We review the systematic characters of the monotypic genusAtrophacanthusand present colour photographs of freshly collected specimens. The diet of the juvenile specimens ofA. japonicusconsisted of thecosome pteropods and foraminiferans. We present a range map ofA. japonicusbased on all known specimens and show that specimen size is related to whether specimens were collected in the pelagic zone or on the bottom. Our results support that, compared to all other Triacanthodidae,A. japonicushas an unusually extended pelagic larval and juvenile period, up to 54 mmLS, before settling to the bottom as adults. Lastly, we provide a multilocus phylogeny addressing the phylogenetic placement ofAtrophacanthusbased on eight of 11 triacanthodid genera and six genetic markers. Our results reveal thatAtrophacanthusis the sister group ofMacrorhamphosodesand they provide new insights about the evolutionary history of the family.more » « less
