Cape Verde Island Research Articles

Kerguelen carbonatite tuff sourced from deep recycled material

Carbonatites are mantle-derived rocks associated with rare earth element deposits and their origin is debated. The majority of carbonatites are found in proximity to old continental crust and generally exhibit more geochemically enriched Sr and Nd isotopes relative to the prevalent mantle, with only a few known carbonatite occurrences found in intra-oceanic settings such as that in Cape Verde and Canary Island in the Atlantic Ocean. These oceanic carbonatites are moderately depleted with isotopic signatures similar to the prevalent mantle, indicating that Sr and Nd isotopic enrichment observed in continental carbonatites is controlled by the continental lithospheric mantle, metasomatized by melts and fluid over billions of years. Here we report a newly discovered intra-oceanic dolomite tuff unit with carbonatitic affinity, from the Kerguelen Archipelago, the emerged part of the long-lived Cretaceous Kerguelen Plateau. The Kerguelen dolomite tuff erupted at 24.1 ± 0.4 Ma after the main building phase of the northern Kerguelen Plateau and was fed by the Kerguelen mantle plume. The dolomite tuff shows strong Sr and Nd isotopic enrichments consistent with the presence of recycled material in the deep mantle source of the Kerguelen plume, possibly enriched during the assembly and breakup of the supercontinent Pangaea. These new data show a significant role of geodynamic processes in controlling deep material recycling, location of mantle plumes, and composition of carbonatitic melt.

Breeding habitat of poorly studied humpback whales (Megaptera novaeangliae) in Boa Vista, Cape Verde

The waters surrounding Cape Verde comprise one of two known breeding grounds for humpback whales in the North Atlantic. The population remains very small and has apparently failed to recover since the cessation of whaling there. During the breeding seasons of 2011 and 2012, sighting surveys were carried out for humpback whales off Boa Vista, the easternmost island of the Cape Verde Island archipelago. The distribution and relative abundance of humpback whales and mother-calf pairs was investigated by plotting effort-corrected sightings using a 2km2 grid-square. The study area, a 206km2 region from the coastline up to 8km offshore, covered the western half of Boa Vista where whales have previously been regularly recorded. Following 1,954km of search effort, 117 sightings of humpback whales were made. An encounter rate of 0.11 whales per km was recorded for both years. It is hoped that these data may assist in implementing conservation measures to protect humpback whales and the habitat of Baia Sal Rei, which appears to be the single most important bay for winter breeding, calving and nursing humpback whales in the eastern North Atlantic.

Contribution of RdDM to the ecotype-specific differential methylation on conserved as well as highly variable regions between Arabidopsis ecotypes

BackgroundSeveral studies showed genome-wide DNA methylation during Arabidopsis embryogenesis and germination. Although it has been known that the change of DNA methylation mainly occurs at CHH context mediated by small RNA-directed DNA methylation pathway during seed ripening and germination, the causality of the methylation difference exhibited in natural Arabidopsis ecotypes has not been thoroughly studied.ResultsIn this study we compared DNA methylation difference using comparative pairwise multi-omics dynamics in Columbia-0 (Col) and Cape Verde Island (Cvi) ecotypes. Arabidopsis genome was divided into two regions, common regions in both ecotypes and Col-specific regions, depending on the reads mapping of whole genome bisulfite sequencing libraries from both ecotypes. Ecotype comparison was conducted within common regions and the levels of DNA methylation on common regions and Col-specific regions were also compared. we confirmed transcriptome were relatively dynamic in stage-wise whereas the DNA methylome and small RNAome were more ecotype-dependent. While the global CG methylation remains steady during maturation and germination, we found genic CG methylation differs the most between the two accessions. We also found that ecotype-specific differentially methylated regions (eDMR) are positively correlated with ecotype-specifically expressed 24-nt small RNA clusters. In addition, we discovered that Col-specific regions enriched with transposable elements (TEs) and structural variants that tend to become hypermethylated, and TEs in Col-specific regions were longer in size, more pericentromeric, and more hypermethylated than those in the common regions. Through the analysis of RdDM machinery mutants, we confirmed methylation on Col-specific region as well as on eDMRs in common region are contributed by RdDM pathway. Lastly, we demonstrated that highly variable sequences between ecotypes (HOT regions) were also affected by RdDM-mediated regulation.ConclusionsThrough ecotype comparison, we revealed differences and similarities of their transcriptome, methylome and small RNAome both in global and local regions. We validated the contribution of RdDM causing differential methylation of common regions. Hypermethylated ecotype-specific regions contributed by RNA-directed DNA methylation pathway largely depend on the presence of TEs and copy-gain structural variations. These ecotype-specific regions are frequently associated with HOT regions, providing evolutionary insights into the epigenome dynamics within a species.

Pelagic Cnidaria and Ctenophora diversity patterns and trends in Macaronesia insular systems (NE Atlantic)

Jellyfish are important components of the marine ecosystem and present a potential resource for different economic domains (e.g. medicine, food and biotechnology). We present an overview of the current state of jellyfish biodiversity in the Macaronesia region, which includes the archipelagos of the Azores, Madeira, the Canary Islands and Cape Verde, and examine possible biogeography patterns among its archipelagos. Based on a comprehensive literature survey, historical records, richness estimation and biogeographical distribution, our search included organisms belonging to Scyphozoa, Hydrozoa (strictly benthic species excluded) and Ctenophora. Our search detected 229 jellyfish species, with a dominance of holoplankton species, likely reflecting the insular and coastal morphology of the archipelagos. Differences in species richness, endemism and species affinities are found between the Azores, Madeira, Canary and Cape Verde island systems. Shared trend includes the dominance of holoplanktonic hydrozoans, while the second most speciose taxa (Scyphozoa and Ctenophore) vary between the archipelagos. While widespread distributed holoplankton predominate in the area, species with strict affinities suggests a pattern in the spatial distribution of jellyfish, dividing Macaronesia into two biogeographic units: (i) Azores-Madeira-Canary with temperate and subtropical and/or tropical species and (ii) Cape Verde with strictly subtropical and/or tropical species

Identification and molecular characterization of Subramaniula asteroides causing human fungal keratitis: a case report

BackgroundKeratitis due to by filamentous fungi are not easy to diagnose thus causing a delay in correct therapy. There are many descriptions of keratitis due to Candida, Fusarium and Aspergillus genera. Subramaniula genus has only recently been reported to cause human infections and there are few descriptions of eye infections due to this filamentous fungus. Diagnosis of fungal keratitis is usually based on microscopic and cultural techniques of samples obtained by corneal swabbing or scraping. Considering the amount of time required to obtain culture results it is wise to use other diagnostic methods, such as molecular analyses. Therapeutic options against these fungi are limited by low tissue penetration in the eye due to ocular barriers. We describe the first case of S. asteroides human keratitis treated with isavuconazole.Case presentationWe describe a rare case of fungal keratitis unresponsive to antimicrobial treatment in a 65-year-old male patient without a history of diabetes or immunological diseases. He reported that the onset of symptoms occurred during a long holiday in Cape Verde Island. Initial treatment with topical antibiotics associated to steroids were ineffective, allowing a slow clinical progression of disease to corneal perforation. On admission in our Hospital, slit-lamp examination of the left eye showed conjunctival congestion and hyperemia, a large inferior corneal ulceration with brown pigment, corneal edema, about 3 mm of hypopyon and irido-lenticular synechiae. The slow clinical progression of the disease to corneal perforation and the aspect of the ulcer were consistent with a mycotic etiology. Molecular methods used on fungal colonies isolated by Sabouraud’s dextrose agar cultures allowed the identification of Subramaniula asteroids from corneal scraping. Antimicrobial test showed a good susceptibility of this filamentous fungus to voriconazole and isavuconazole. Moreover, this fungal keratitis was successfully treated with isavuconazole, without side effects, observing a progressive clinical improvement.ConclusionsMolecular methods may be useful for the identification of filamentous fungal keratitis on scraping samples thus shortening the time of diagnosis. Systemic therapy by isavuconazole could be useful to treat the filamentous fungal keratitis, reducing the possible adverse effects due to the use of voriconazole by systemic administration.

Intervessel pit membrane thickness best explains variation in embolism resistance amongst stems of Arabidopsis thaliana accessions.

Background and AimsThe ability to avoid drought-induced embolisms in the xylem is one of the essential traits for plants to survive periods of water shortage. Over the past three decades, hydraulic studies have been focusing on trees, which limits our ability to understand how herbs tolerate drought. Here we investigate the embolism resistance in inflorescence stems of four Arabidopsis thaliana accessions that differ in growth form and drought response. We assess functional traits underlying the variation in embolism resistance amongst the accessions studied using detailed anatomical observations.MethodsVulnerability to xylem embolism was evaluated via vulnerability curves using the centrifuge technique and linked with detailed anatomical observations in stems using light microscopy and transmission electron microscopy.Key ResultsThe data show significant differences in stem P50, varying 2-fold from −1.58 MPa in the Cape Verde Island accession to −3.07 MPa in the woody soc1 ful double mutant. Out of all the anatomical traits measured, intervessel pit membrane thickness (TPM) best explains the differences in P50, as well as P12 and P88. The association between embolism resistance and TPM can be functionally explained by the air-seeding hypothesis. There is no evidence that the correlation between increased woodiness and increased embolism resistance is directly related to functional aspects. However, we found that increased woodiness is strongly linked to other lignification characters, explaining why mechanical stem reinforcement is indirectly related to increased embolism resistance.ConclusionsThe woodier or more lignified accessions are more resistant to embolism than the herbaceous accessions, confirming the link between increased stem lignification and increased embolism resistance, as also observed in other lineages. Intervessel pit membrane thickness and, to a lesser extent, theoretical vessel implosion resistance and vessel wall thickness are the missing functional links between stem lignification and embolism resistance.

Unusual cause of left ventricular dysfunction in a child

Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery is a rare congenital heart disease and a cause of myocardial ischemia during childhood. Most undiagnosed cases die in the first year of life as an extensive collateral network is essential for survival. The diagnosis requires a high index of clinical suspicion. The authors present the case of an 8-year-old black asymptomatic child referred from Cape Verde Island in order to clarify left ventricular dilatation and dysfunction with systo-diastolic turbulent flows observed at the interventricular septum. At the age of 3 months, she was diagnosed with heart failure, in the context of showing dilated cardiomyopathy. She was managed and clinically improved with anticongestive therapy, which she was still taking at the time of admission to our Center. The echocardiogram findings suggested Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery and the diagnosis was confirmed by computerized angiotomography and cardiac catheterization. The patient was successfully submitted to direct implantation of the left coronary artery into the aorta, allowing the creation of a double coronary perfusion system. This case illustrates an unusual presentation of a rare pathology that survived without a diagnosis after the first year of life. It also reinforces the importance of multimodality image screening in these cases.

Characterization of GPS and EGNOS amplitude scintillations over the African equatorial/low-latitude region

This study characterizes GPS and EGNOS amplitude scintillations over the African equatorial/low-latitude region. The data set covers January–December 2013 at three stations; namely, Cape-Verde Island (Lat: 16°N, Lon: 24°W, Mag. Lat: 11°N), Dakar (Lat: 14.75°N, Lon: 17.45°W, Mag. Lat: 5.88°N) [Senegal] and Addis Ababa (Lat: 9.03°N, Lon: 38.77°W, Mag. Lat: 0.18°N) [Ethiopia]. Firstly, we investigated the seasonal variations of scintillations over the study sites. In doing this, we suppressed multipath effects on the data by imposing a 30° elevation masking on the data. Seasonally, scintillations recorded highest occurrences during equinoxes, and the least during June solstice. Secondly, we investigated scintillation occurrences at the three sites on a satellite-by-satellite basis at varying elevation and azimuthal angles. Generally, scintillations (at both low- and high-elevation angles) recorded the highest occurrences at Cape-Verde, followed by Dakar, and the least at Addis Ababa. Scintillation activities were generally localized within the northern skies of the study locations. EGNOS satellites signals scintillated at Dakar and Addis Ababa during the time intervals when GPS satellites signals experienced scintillations. Data showed that Cape-Verde is off the EGNOS geostationary satellite footprint. These results have the potentials of supporting the development of scintillation models for equatorial Africa. Furthermore, with a view to providing robust services for the African user community, the current research effort is also expected to provide value addition to GPS and EGNOS service providers and system designers.

Characterization of protistan plankton diversity in ancient salt evaporation ponds located in a volcanic crater on the island Sal, Cape Verde.

Salinity is an important factor when exploring the limits known for life. Therefore, hypersaline systems have attracted much attention in recent years. In this study, we investigated the protistan diversity and community composition in two natural salt evaporation ponds (27-30% salinity) located in an ancient volcanic crater on the Cape Verde island Sal using high-throughput DNA sequencing. Our study revealed a broad range of protistan taxa and a high taxonomic diversity within the Ciliophora, Dinophyceae, and Chlorophyta. We detected a total of 23 Dinophyceae families, although Dinophyceae were generally considered to be only this diverse in aquatic environments of less than 10% salinity. Moreover, we uncovered a high degree of genetic novelty in this habitat. The mean similarity of all detected OTUs to previously described sequences was only 93.6%. These findings strongly dispute the traditional view that extreme hypersaline environments generally maintain low protistan diversity. A meta-analysis covering our and previously published data from other inland and coastal salt ponds clearly showed that our samples clustered according to salinity and not biogeography. This result further supports the claim that salinity is a major transition boundary for protistan communities, regardless of their biogeographic origin.

Redescription of the halophile ciliate, Blepharisma halophilum Ruinen, 1938 (Ciliophora, Heterotrichea, Heterotrichida) shows that the genus Blepharisma is non-monophyletic

We collected a heterotrich ciliate from hypersaline waters on the Cape Verde island Sal. After living observation and protargol-staining, it closely matched Blepharisma halophilum Ruinen, 1938. However, because (i) Ruinen most likely described several different species as B. halophilum, and (ii) he provided only very scarce diagnostic features, we redescribe this species with state-of-the-art methods according to modern standards. This will facilitate an accurate identification of this ciliate species, globally distributed in hypersaline water bodies: halophile Blepharisma, about 100–250μm in vivo; 32–42 adoral membranelles; 13–17 somatic kineties, including 2–4 anterior kinety fragments; single elongated macronucleus; cortical granules colourless. Its SSU rRNA gene sequence is very similar (99.7%) to an uncultured organism (environmental sequence) obtained from the hypersaline Lake Tyrrell in Australia. In phylogenetic analyses, these two sequences form a cluster, which with nearly full support (ML/BI, 99/1.00) branches as sister to the Fabreidae, showing for the first time that Blepharisma is yet another non-monophyletic ciliate genus.

Identification of a Dolabellane Type Diterpene Synthase and other Root-Expressed Diterpene Synthases in Arabidopsis.

Arabidopsis thaliana maintains a complex metabolism for the production of secondary or specialized metabolites. Such metabolites include volatile and semivolatile terpenes, which have been associated with direct and indirect defensive activities in flowers and leaves. In comparison, the structural diversity and function of terpenes in Arabidopsis roots has remained largely unexplored despite a substantial number of root-expressed genes in the Arabidopsis terpene synthase (TPS) gene family. We show that five root-expressed TPSs of an expanded subfamily-a type clade in the Arabidopsis TPS family function as class I diterpene synthases that predominantly convert geranylgeranyl diphosphate (GGPP) to different semi-volatile diterpene products, which are in part detectable at low levels in the ecotypes Columbia (Col) and Cape Verde Island (Cvi). The enzyme TPS20 produces a macrocyclic dolabellane diterpene alcohol and a dolabellane-related diterpene olefin named dolathaliatriene with a so far unknown C6-C11 bicyclic scaffold besides several minor olefin products. The TPS20 compounds occur in all tissues of Cvi but are absent in the Col ecotype because of deletion and substitution mutations in the Col TPS20 sequence. The primary TPS20 diterpene products retard the growth of the root rot pathogen Pythium irregulare but only at concentrations exceeding those in planta. Together, our results demonstrate that divergence and pseudogenization in the Arabidopsis TPS gene family allow for structural plasticity in diterpene profiles of above- and belowground tissues.

Allelic differences in a vacuolar invertase affect Arabidopsis growth at early plant development.

Improving carbon fixation in order to enhance crop yield is a major goal in plant sciences. By quantitative trait locus (QTL) mapping, it has been demonstrated that a vacuolar invertase (vac-Inv) plays a key role in determining the radical length in Arabidopsis. In this model, variation in vac-Inv activity was detected in a near isogenic line (NIL) population derived from a cross between two divergent accessions: Landsberg erecta (Ler) and Cape Verde Island (CVI), with the CVI allele conferring both higher Inv activity and longer radicles. The aim of the current work is to understand the mechanism(s) underlying this QTL by analyzing structural and functional differences of vac-Inv from both accessions. Relative transcript abundance analyzed by quantitative real-time PCR (qRT-PCR) showed similar expression patterns in both accessions; however, DNA sequence analyses revealed several polymorphisms that lead to changes in the corresponding protein sequence. Moreover, activity assays revealed higher vac-Inv activity in genotypes carrying the CVI allele than in those carrying the Ler allele. Analyses of purified recombinant proteins showed a similar K m for both alleles and a slightly higher V max for that of Ler. Treatment of plant extracts with foaming to release possible interacting Inv inhibitory protein(s) led to a large increase in activity for the Ler allele, but no changes for genotypes carrying the CVI allele. qRT-PCR analyses of two vac-Inv inhibitors in seedlings from parental and NIL genotypes revealed different expression patterns. Taken together, these results demonstrate that the vac-Inv QTL affects root biomass accumulation and also carbon partitioning through a differential regulation of vac-Inv inhibitors at the mRNA level.

Iconography and Distribution of the Cape Verde Island Abalone, Haliotis tuberculata fernandesi Owen & Afonso, 2012, with Comparisons to H. tuberculata coccinea Reeve, 1846, of the Canary Islands

Specimens of Haliotis tuberculata fernandesi collected from Santa Luzía Island, Cape Verde Islands, are illustrated to provide additional representatives of this subspecies. Comparisons are made with Haliotis tuberculata coccinea Reeve, 1846, of the Canary Islands. Differences in shell morphology between the two subspecies are discussed in greater detail.

International Students in China: Cross-Cultural Interaction, Integration, and Identity Construction

This qualitative study engaged five international graduate students from four different countries (the U.S., Colombia, Cape Verde Island, and Spain) who were studying at a Chinese university in Shanghai. The researcher investigated their personal and academic lives in China, their interaction with local people and integration into the local context. Their sense of belonging was also explored. Data were drawn from a questionnaire, email correspondence, face-to-face interviews, and follow-up emails during the period of 1 year. In light of the data, I discussed factors such as language proficiency, engagement with culture, and the power of native language in relation to sense of belonging. I conceptualized a mediated space, one incorporating these students’ multiple cultures, and created through negotiation with themselves and the host culture. Implications for China’s international education are discussed.

Larvicidal Activity against Aedes Aegypti of Foeniculum Vulgare Essential Oils from Portugal and Cape Verde

Dengue is a potentially fatal mosquito-borne infection with 50 million cases per year and 2.5 billion people vulnerable to the disease. This major public health problem has recurrent epidemics in Latin America and occurred recently in Cape Verde and Madeira Island. The lack of anti-viral treatment or vaccine makes the control of mosquito vectors a high option to prevent virus transmission. Essential oil (EO) constituents can affect insect's behaviour, being potentially effective in pest control. The present study evaluated the potential use of Foenicultm vulgare (fennel) EO in the control of the dengue vector Aedes aegypti. EOs isolated from fennel aerial parts collected in Cape Verde and from a commercial fennel EO of Portugal were analysed by NMR, GC and GC-MS. trans-Anethole (32 and 30%, respectively), limonene (28 and 18%, respectively) and fenchone (10% in both cases) were the main compounds identified in the EOs isolated from fennel from Cape Verde and Portugal, respectively. The larvicidal activity of the EOs and its major constituents were evaluated, using WHO procedures, against third instar larvae ofAe. aegypti for 24 h. Pure compounds, such as limonene isomers, were also assayed. The lethal concentrations LC50, C90 and LC99 were determined by probit analysis using mortality rates of bioassays. A 99% mortality of Ae. aegypti larvae was estimated at 37.1 and 52.4 µL L-1 of fennel EOs from Cape Verde and Portugal, respectively. Bioassays showed that fennel EOs from both countries displayed strong larvicidal effect against Ae. aegypti, the Cape Verde EO being as active as one of its major constituents, (-)-limonene.

Respiration rates of tropical Atlantic copepods in relation to the oxygen minimum zone

Zooplankton respiration plays an important role in the carbon cycling of pelagic ecosystems. The rate of oxygen consumption in zooplankton is affected by the physical environment, vertical distribution range and species-specific behavior. Especially in tropical oceans, oxygen minimum zones (OMZs) may influence zooplankton metabolic processes and vertical distribution and thus structure zooplankton communities. Here we present respiration rates of tropical Atlantic copepods in relation to environmental factors, especially O2 concentration, and species-specific characteristics. Copepods were sampled during two research stays on the Cape Verde Island São Vicente in March/April and May/June 2010. Minimum O2 concentrations of 51μmolkg−1 (pO2 of 4.25kPa) at 400m depth were recorded within the OMZ. Respiration rates of epi- and mesopelagic calanoid copepods were measured by optode respirometry at three different ambient temperatures (13, 18, and 23°C) to establish the effect of temperature on metabolic rates. Mass-specific oxygen consumption ranged from 27μmolO2gDM−1h−1 in copepodids C5 of Lophothrix sp. at 13°C to 774μmolO2gDM−1h−1 in Pleuromamma xiphias copepodids C5 at 18°C and was mainly controlled by body mass and temperature. Mass-specific respiration rates were highest in surface-dwelling organisms and decreased with increasing depth. To allow for a comparison of shallow and deep-living copepods, respiration rates were standardized to a common temperature of 18°C and a mean body dry mass of 0.5mg, applying a Q10 of 2.0 and a body mass exponent of −0.56. Temperature- and body mass-corrected respiration rates did not decrease with increasing depth indicating that neither depth of occurrence, nor current hypoxic conditions within the OMZ had a fundamental, persistent effect on zooplankton respiration.

High temperatures constrain microhabitat selection and activity patterns of the insular Cape Verde wall gecko

The diel activity, microhabitat selection and thermobiology were investigated in Tarentola substituta, a gecko endemic to an arid Cape Verde island, S. Vicente. Standardized transects were performed recording the microhabitat availability and the body, soil, refuge, air temperatures, relative humidity, gecko category (juvenile, adult male or female) and activity status for each observation. Thermal conditions were monitored with data-loggers. The activity pattern of the species was strictly nocturnal, as desert geckos. All individuals selected rocks as diurnal refuges, but adults used more medium-sized rocks (scarce) and juveniles small rocks (abundant). Such selection was mostly attributable to the refuges thermal properties: small rocks attained higher temperatures due to their lower thermal inertia. Geckos behaved as tigmotherms when active by night and as thermoconformers with the substrate by day. Nocturnal body temperatures did not differ among gecko categories or microhabitats. However, since juveniles selected small rocks, their diurnal body temperatures became higher, sometimes possibly risking overheating. Territoriality, scarcity of optimal refuges, high conspecific densities and lack of ground-predators may explain why juveniles use thermally suboptimal microhabitats. Results suggest that ecological shifts (nocturnality, microhabitat selection) and lack of competitors allowed T. substituta to adapt to the archipelago’s demanding arid and hot conditions.

Thermoinhibition Uncovers a Role for Strigolactones in Arabidopsis Seed Germination

Strigolactones are host factors that stimulate seed germination of parasitic plant species such as Striga and Orobanche. This hormone is also important in shoot branching architecture and photomorphogenic development. Strigolactone biosynthetic and signaling mutants in model systems, unlike parasitic plants, only show seed germination phenotypes under limited growth condition. To understand the roles of strigolactones in seed germination, it is necessary to develop a tractable experimental system using model plants such as Arabidopsis. Here, we report that thermoinhibition, which involves exposing seeds to high temperatures, uncovers a clear role for strigolactones in promoting Arabidopsis seed germination. Both strigolactone biosynthetic and signaling mutants showed increased sensitivity to seed thermoinhibition. The synthetic strigolactone GR24 rescued germination of thermoinbibited biosynthetic mutant seeds but not a signaling mutant. Hormone analysis revealed that strigolactones alleviate thermoinhibition by modulating levels of the two plant hormones, GA and ABA. We also showed that GR24 was able to counteract secondary dormancy in Arabidopsis ecotype Columbia (Col) and Cape Verde island (Cvi). Systematic hormone analysis of germinating Striga helmonthica seeds suggested a common mechanism between the parasitic and non-parasitic seeds with respect to how hormones regulate germination. Thus, our simple assay system using Arabidopsis thermoinhibition allows comparisons to determine similarities and differences between parasitic plants and model experimental systems for the use of strigolactones.

Spectral particle absorption coefficients, single scattering albedos and imaginary parts of refractive indices from ground based in situ measurements at Cape Verde Island during SAMUM-2

Spectral particle absorption coefficients, single scattering albedos and imaginary parts of refractive indices from ground based in situ measurements at Cape Verde Island during SAMUM-2

Functional analysis in Arabidopsis of FsPTP1, a tyrosine phosphatase from beechnuts, reveals its role as a negative regulator of ABA signaling and seed dormancy and suggests its involvement in ethylene signaling modulation

By means of an RT-PCR approach we isolated a specific tyrosine phosphatase (FsPTP1) induced by abscisic acid (ABA) and correlated with seed dormancy in Fagus sylvatica seeds. To provide genetic evidence of FsPTP1 function in seed dormancy and ABA signal transduction pathway, we overexpressed this gene in Cape Verde Island ecotype of Arabidopsis thaliana, which shows the deepest degree of seed dormancy among Arabidopsis accessions. As a result, 35S:FsPTP1 transgenic seeds showed a reduced dormancy and insensitivity to ABA and osmotic stress conditions accompanied by a reduction in the level of expression of RAB18 and RD29, well-known ABA-responsive genes. Taken together, all these data are consistent with a role of this tyrosine phosphatase as a negative regulator of ABA signaling. In addition, phenotypes of FsPTP1 transgenic plants resemble those observed in ethylene constitutive mutants, accompanied by an increase in the level of expression of a key gene involved in ethylene signaling such as EIN2. All the data presented along the paper suggest that the effect of tyrosine phosphatases in ABA action during the transition from seed dormancy to germination may be through modulation of ethylene signaling.