Isabel Bravo - Academia.edu (original) (raw)
Papers by Isabel Bravo
Toxicon : official journal of the International Society on Toxinology, Jan 17, 2015
Among toxin-producing dinoflagellates of the genus Alexandrium, A. ostenfeldii is the only specie... more Among toxin-producing dinoflagellates of the genus Alexandrium, A. ostenfeldii is the only species able to produce paralytic shellfish poisoning (PSP) toxins, spirolides (SPXs) and gymnodimines (GYMs). In this study we characterized and compared three A. ostenfeldii strains isolated from the Baltic, Mediterranean, and southern Chile Seas with respect to their toxin profiles, morphology, and phylogeny. Toxin analyses by HPLC-FD and LC-HRMS revealed differences in the toxin profiles of the three strains. The PSP toxin profiles of the southern Chile and Baltic strains were largely the same and included gonyautoxin (GTX)-3, GTX-2, and saxitoxin (STX), although the total PSP toxin content of the Chilean strain (105.83 ± 72.15 pg cell(-1)) was much higher than that of the Baltic strain (4.04 ± 1.93 pg cell(-1)). However, the Baltic strain was the only strain that expressed detectable amounts of analogues of GYM-A and GYM-B/-C (48.27 ± 26.12 pg GYM-A equivalents cell(-1)). The only toxin e...
A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conduct... more A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conducted from 2005 to 2007 in order to increase knowledge of the mechanisms governing recurrent blooms of these species. Considerable differences in their bloom dynamics were observed. G. catenatum blooms occurred in autumn and winter, following the pattern previously reported in the literature: they began off-shore and were advected to the Galician rias when a relaxation of the coastal upwelling occurred. On the other hand, A. minutum blooms developed inside embayments in spring and summer during the upwelling season and were associated with water stability and stratification. Both the vegetative population and the cyst distribution of A. minutum were related to less saline water from freshwater river outputs, which support a saline-gradient relationship postulated herein for this species. Dinoflagellates may produce both long-term double-walled cysts (resting) and short-term pellicle cysts. Resting cyst deposition and distribution in sediments showed that seeding occurred during the blooms of both species. However, the relationship between the cyst distribution in the sediments in Baiona Bay and the intensity and occurrence of G. catenatum blooms, suggests that the latter are not directly related to resting cyst germination. Moreover, the results presented in the present study point to other difference between the two species, such as the detection of pellicle cysts only for A. minutum. Finally, we discuss how the life cycle strategies of these two species may help to explain the different mechanisms of bloom formation reported herein.
![Research paper thumbnail of Life cycle stages of the benthic palytoxin-producing dinoflagellate Ostreopsis cf. ovata (Dinophyceae)[2012]](https://attachments.academia-assets.com/45191884/thumbnails/1.jpg)
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Dinoflagellates belonging to the genus Gambierdiscus are the causative agent of ciguatera fish po... more Dinoflagellates belonging to the genus Gambierdiscus are the causative agent of ciguatera fish poisoning (CFP). This syndrome, which is widespread in tropical and subtropical regions, has recently been reported also in temperate latitudes. Taxonomic studies of Gambierdiscus have yet to completely couple the morphological features of member species with their genetics. In this study, the cellular and nuclear morphology of a single strain of one species of Gambierdiscus was determined in cells grown under different culture conditions. The results showed a wide-ranging variability of cell sizes, together with a clear relationship between cell size and nuclear morphology. Thus, small cells were associated with round to oval or slightly U-shaped nuclei and large cells with obviously U-shaped nuclei. Most cells exhibited the typical anterio-posteriorly compressed lenticular, shape of Gambierdiscus, with the exception of a few small globular-shaped specimens. In all cells, regardless of their size, the arrangement of the thecal plates was typical of lenticular Gambierdiscus. Dividing cells were consistently the largest. In these cells, nuclear morphology, karyokinesis, and cytokinesis were characterized. Cells underwent division only during the dark period, thus demonstrating their spontaneous synchronized division. Cellular forms related to the sexual cycle were also present in the cultures and included gamete pairs and putative meiotic planozygotes. The effect of the culture medium was studied by means of principal component analyses, which showed a positive correlation between the medium used and nuclear size and shape but not cell size.
El dinoflagelado bentónico Prorocentrum lima produce toxinas lipofílicas, que pueden ocasionar in... more El dinoflagelado bentónico Prorocentrum lima produce toxinas lipofílicas, que pueden ocasionar intoxicaciones diarreicas (VDM) en humanos consumidores de mariscos. En sedimentos recolectados en Cabo San Isidro, Estrecho de Magallanes, durante el invierno de 2010, se logró cuantificar una abundancia de 1002 quistes tecados de Prorocentrum lima cm -3 de sedimento, la mayor concentración respecto a otros sitios de recolecta. Se aislaron 27−87 quistes tecados directamente desde los sedimentos mientras otras 60 células vegetativas fueron aisladas luego de promover la actividad y división de los quistes en condiciones de 15 ºC y 12:12 horas luz-oscuridad. Las células fueron puestas independientemente en tubos Eppendorf, así como también, 100 µL aproximados de sedimento húmedo. Luego de congelados los tubos, la extracción de la toxina se realizó con 500 µL de metanol 100%, se mezcló, filtró por 0.45 µm, trasvasijando a un vial. El extracto fue secado bajo nitrógeno gas a 40 ºC y conservado a 4 ºC hasta su análisis. La presencia de la toxina dinofisistoxina 1 (DTX-1) en las muestras fue confirmada en modo negativo, por su ión padre [M-H]-m/z 817.5 y iones hijos m/z 563.4 y 255.2, mediante cromatografía líquida acoplada a un espectrómetro de masas. Previo a la inyección, los extractos fueron resuspendidos en 150 µL de metanol. El contenido de DTX-1 en las muestras fue cuantificado en base al ion padre. Las células vegetativas presentaron un mayor contenido de DTX-1 por célula, en comparación a las células de resistencia.
Automatic taxonomic categorisation of 23 species of dinoflagellates was demonstrated using field-... more Automatic taxonomic categorisation of 23 species of dinoflagellates was demonstrated using field-collected specimens. These dinoflagellates have been responsible for the majority of toxic and noxious phytoplankton blooms which have occurred in the coastal waters of the European Union in recent years and make severe impact on the aquaculture industry. The performance by human 'expert' ecologists/taxonon~ists in identifying these species was compared to that achieved by 2 art~ficial neural network classifiers (multilayer perceptron and radial basis function networks) and 2 other statistical techniques, k-Nearest Neighbour and Quadratic Dlscnm~nant Analysis The neural network classifiers outperform the classical statistical techniques. Over extended trials, the human experts averaged 85% while the radial basis network achieved a best performance of 83%, the multilayer perceptron 66 %, k-Nearest Neighbour 60%, and the Quadratic Discriminant Analysis 56 %.
Journal of Plankton Research, 1996
A comparison was made between the use of linear and quadratic discriminant functions for classify... more A comparison was made between the use of linear and quadratic discriminant functions for classifying phytoplankton specimens of the genera Dinophysis and Ceratium by means of a general morphometric function. The class distributions were found to fit quadratic boundaries better than linear boundaries. A nine species quadratic discriminant classified within 95% confidence intervals. Morphological variants not used in the calibration were all correctly identified, although control species unknown to the model were poorly rejected. An accuracy of 99% was obtained for separating three morphological variants of Dinophysis acuminata. Digital filters were developed to extract the morphometric function directly from photomicrograph images, and present the data as an orientation-independent feature vector. Using this feature vector, a quadratic discriminant classified test data from 14 species of the genera Dinophysis, Ceratium and Ornithocercus with an accuracy of 83%, with 37% of the error due to two similarly shaped species of Dinophysis overlapping.
Toxicon, 2001
The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galici... more The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galician rias (Vigo and Pontevedra) was investigated by high performance liquid chromatography coupled with fluorimetric detection. Boiling and freeze/thaw/hydrolyse methodology were applied during extraction to detect OA, DTX1, DTX2 and their esterified derivatives. OA and DTX2 were detected in both free and esterified form, the latter
Unreported aspects in the sexual cycle of the marine dinoflagellate Lingulodinium polyedrum (Stei... more Unreported aspects in the sexual cycle of the marine dinoflagellate Lingulodinium polyedrum (Stein) Dodge were described. Our observations in- cluded the description of two types of hypnozygote formation, because culture planozygotes were ob- served to encyst in two different ways: an ecdysal sexual stage or a spiny resting cyst. Phosphate de- ficiency was the main nutritional condition required for fusing
Protist, 2015
Elucidation of the cell cycle of dinoflagellates is essential to understand the processes leading... more Elucidation of the cell cycle of dinoflagellates is essential to understand the processes leading to their massive proliferations, known as harmful algal blooms. In this study, we used imaging flow cytometry (IFC) to monitor the changes in DNA content and nuclear and cell morphology that occur during clonal growth of the toxic species Alexandrium minutum Halim. Our results indicate that the population was in S phase (C→2C DNA content) during the light period, whereas haploid cells with a C DNA content peaked only during a short interval of the dark period. The timing of the phases, identified based on the nuclear morphology and cytoplasmic-to-nuclear (CNR) ratio of the cells, suggests that the length of the G2/M phase is regulated by nutrient levels whereas the beginning of S phase is clock controlled. In addition we found that up to 7% of individual cells achieved a DNA content higher than 2C, indicative of either zygote formation and replication (homothallism), or of double-haploid cells able to divide (polyploid forms). Cells belonging to different cell cycle phases (G1-S-G2/M) could be readily discriminated based on nuclear size. Our study provides evidence of cell-cycle plasticity during clonal growth and unambiguously characterizes the cell-cycle phases of this dinoflagellate species. (R.I. Figueroa). phases: G1, in which growing cells exhibit high metabolic activity; S, during which cellular DNA is replicated; and G2, a temporal gap between S phase and the following division in which cells accumulate the nutrients needed for the division process; ii) mitosis (M phase), during which there is nuclear division, or karyokinesis; and iii) cytokinesis, when cytoplasmic division marks the completion of cell division and thus of the cell cycle. The molecular events that determine a cell's http://dx.
Toxicon, 2001
The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galici... more The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galician rias (Vigo and Pontevedra) was investigated by high performance liquid chromatography coupled with fluorimetric detection. Boiling and freeze/thaw/hydrolyse methodology were applied during extraction to detect OA, DTX1, DTX2 and their esterified derivatives. OA and DTX2 were detected in both free and esterified form, the latter always in very low amounts, whilst DTX1 was always present in the free form. This indicate that the hypothesized self-protection mechanism of toxin storage in the less active esterified forms does not seem to apply to DTX1. A slight increase in the toxin concentration per cell was found during growth, although toxin composition did not vary appreciably. Toxin production and toxin profile varied significantly depending on the isolate. Four groups of P. lima were differentiated by cluster analysis according to their toxin composition. It is noteworthy that one of the clusters comprised all the strains collected from one location characterised by its geographical isolation, whereas the other clusters consisted of isolates from different locations. The differences in the toxin profile from P. lima strains and from the DSP contaminated shellfish, together with the very good correlation between Dinophysis spp occurrence and DSP toxicity in shellfish, support that these planktonic species are the main agents responsible for DSP events in Galicia.
Protist, 2013
This study begins with a description of the infective process in the dinoflagellate type host Ale... more This study begins with a description of the infective process in the dinoflagellate type host Alexandrium minutum by a strain of the parasitoid, Parvilucifera sinerae, including the morphologies of the various dinoflagellate and parasitoid stages during the infection. Then, the susceptibility of 433 microalgal strains to P. sinerae infection was studied. The parasitoid was found to be capable of infecting several dinoflagellate species of the genera Alexandrium, Coolia, Dinophysis, Fragilidium, Gambierdiscus, Gymnodinium, Gyrodinium, Heterocapsa, Kryptoperidinium, Lepidodinium, Ostreopsis, Pentapharsodinium, Protoceratium, Scrippsiella, and Woloszynskia. Intra-strain variability was observed as well, such that within the same dinoflagellate species some strains were infected whereas others were not. Likewise, species of other dinoflagellate genera were not infected, such as Akashiwo, Amphidinium, Barrufeta, Bysmatrum, Karenia, Karlodinium, Prorocentrum, and Takayama. Moreover, P. sinerae was not able to infect any of the tested haptophyte, diatom, and chlorophyte species. In natural samples screened for P. sinerae infectivity, several dinoflagellate species of the genera Alexandrium, Coolia, Gonyaulax, Gymnodinium, Phalacroma, Protoperidinium, and Scrippsiella were identified as susceptible. Sporangia size was found to be proportional to the size of the host, and variations in the sporangia size were observed to influence their maturation time.
Protist, 2009
Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus o... more Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus of diatom origin. However, it is unknown whether the binucleate condition is permanent or not and how the diatom nucleus behaves during the life history processes. In this sense, it is also unknown if there is a sexual cycle or a resting stage during the life history of this species, two key aspects necessary to understand the life history strategy of this dinoflagellate. To answer these questions, life history and cell cycle studies were performed with the following results: (i) Kryptoperidinium foliaceum has a sexual cycle and in the dinoflagellate strains studied, the binucleate condition is permanent. Sexuality in the host was confirmed by the presence of fusing gamete pairs and planozygotes in clonal cultures (revealing homothallism), but signs of meiosis in the endosymbiont were not observed. The endosymbiont nucleus likely fuses first, because fusing gamete pairs were found to have two dinoflagellate nuclei but only one endosymbiont nucleus. After complete gamete fusion, the planozygotes had apparently normal endosymbiont and dinoflagellate nuclei. (ii) Asexual division studies using flow cytometry showed that the S phase in the endosymbiont (diatom) nucleus starts 6-8 h later than in the host nucleus, but there was no evidence of mitosis in the former. (iii) Sexual and asexual cysts were formed in culture. Neither cysts from natural samples nor those formed in culture exhibited a dormancy period before germination.
Phycologia, 1995
Abstract A new chain-forming dinoflagellate Gyrodinium impudicum sp. nov., Gymnodiniaceae, is des... more Abstract A new chain-forming dinoflagellate Gyrodinium impudicum sp. nov., Gymnodiniaceae, is described from Valencia Harbour, Ría de Vigo (Spain) and Fusaro Lagoon (Italy). The cingulum is a descending left spiral, displaced between 1/3-1/4 of the total length of the cell and the sulcus is without torsion, two reasons why the new species is assigned to Gyrodinium. This red tide organism has been misidentified in several previous papers as Gymnodinium catenatum Graham or Polykrikos schwartzii Bütschli. It differs ...
Toxicon : official journal of the International Society on Toxinology, Jan 17, 2015
Among toxin-producing dinoflagellates of the genus Alexandrium, A. ostenfeldii is the only specie... more Among toxin-producing dinoflagellates of the genus Alexandrium, A. ostenfeldii is the only species able to produce paralytic shellfish poisoning (PSP) toxins, spirolides (SPXs) and gymnodimines (GYMs). In this study we characterized and compared three A. ostenfeldii strains isolated from the Baltic, Mediterranean, and southern Chile Seas with respect to their toxin profiles, morphology, and phylogeny. Toxin analyses by HPLC-FD and LC-HRMS revealed differences in the toxin profiles of the three strains. The PSP toxin profiles of the southern Chile and Baltic strains were largely the same and included gonyautoxin (GTX)-3, GTX-2, and saxitoxin (STX), although the total PSP toxin content of the Chilean strain (105.83 ± 72.15 pg cell(-1)) was much higher than that of the Baltic strain (4.04 ± 1.93 pg cell(-1)). However, the Baltic strain was the only strain that expressed detectable amounts of analogues of GYM-A and GYM-B/-C (48.27 ± 26.12 pg GYM-A equivalents cell(-1)). The only toxin e...
A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conduct... more A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conducted from 2005 to 2007 in order to increase knowledge of the mechanisms governing recurrent blooms of these species. Considerable differences in their bloom dynamics were observed. G. catenatum blooms occurred in autumn and winter, following the pattern previously reported in the literature: they began off-shore and were advected to the Galician rias when a relaxation of the coastal upwelling occurred. On the other hand, A. minutum blooms developed inside embayments in spring and summer during the upwelling season and were associated with water stability and stratification. Both the vegetative population and the cyst distribution of A. minutum were related to less saline water from freshwater river outputs, which support a saline-gradient relationship postulated herein for this species. Dinoflagellates may produce both long-term double-walled cysts (resting) and short-term pellicle cysts. Resting cyst deposition and distribution in sediments showed that seeding occurred during the blooms of both species. However, the relationship between the cyst distribution in the sediments in Baiona Bay and the intensity and occurrence of G. catenatum blooms, suggests that the latter are not directly related to resting cyst germination. Moreover, the results presented in the present study point to other difference between the two species, such as the detection of pellicle cysts only for A. minutum. Finally, we discuss how the life cycle strategies of these two species may help to explain the different mechanisms of bloom formation reported herein.
Dinoflagellates belonging to the genus Gambierdiscus are the causative agent of ciguatera fish po... more Dinoflagellates belonging to the genus Gambierdiscus are the causative agent of ciguatera fish poisoning (CFP). This syndrome, which is widespread in tropical and subtropical regions, has recently been reported also in temperate latitudes. Taxonomic studies of Gambierdiscus have yet to completely couple the morphological features of member species with their genetics. In this study, the cellular and nuclear morphology of a single strain of one species of Gambierdiscus was determined in cells grown under different culture conditions. The results showed a wide-ranging variability of cell sizes, together with a clear relationship between cell size and nuclear morphology. Thus, small cells were associated with round to oval or slightly U-shaped nuclei and large cells with obviously U-shaped nuclei. Most cells exhibited the typical anterio-posteriorly compressed lenticular, shape of Gambierdiscus, with the exception of a few small globular-shaped specimens. In all cells, regardless of their size, the arrangement of the thecal plates was typical of lenticular Gambierdiscus. Dividing cells were consistently the largest. In these cells, nuclear morphology, karyokinesis, and cytokinesis were characterized. Cells underwent division only during the dark period, thus demonstrating their spontaneous synchronized division. Cellular forms related to the sexual cycle were also present in the cultures and included gamete pairs and putative meiotic planozygotes. The effect of the culture medium was studied by means of principal component analyses, which showed a positive correlation between the medium used and nuclear size and shape but not cell size.
El dinoflagelado bentónico Prorocentrum lima produce toxinas lipofílicas, que pueden ocasionar in... more El dinoflagelado bentónico Prorocentrum lima produce toxinas lipofílicas, que pueden ocasionar intoxicaciones diarreicas (VDM) en humanos consumidores de mariscos. En sedimentos recolectados en Cabo San Isidro, Estrecho de Magallanes, durante el invierno de 2010, se logró cuantificar una abundancia de 1002 quistes tecados de Prorocentrum lima cm -3 de sedimento, la mayor concentración respecto a otros sitios de recolecta. Se aislaron 27−87 quistes tecados directamente desde los sedimentos mientras otras 60 células vegetativas fueron aisladas luego de promover la actividad y división de los quistes en condiciones de 15 ºC y 12:12 horas luz-oscuridad. Las células fueron puestas independientemente en tubos Eppendorf, así como también, 100 µL aproximados de sedimento húmedo. Luego de congelados los tubos, la extracción de la toxina se realizó con 500 µL de metanol 100%, se mezcló, filtró por 0.45 µm, trasvasijando a un vial. El extracto fue secado bajo nitrógeno gas a 40 ºC y conservado a 4 ºC hasta su análisis. La presencia de la toxina dinofisistoxina 1 (DTX-1) en las muestras fue confirmada en modo negativo, por su ión padre [M-H]-m/z 817.5 y iones hijos m/z 563.4 y 255.2, mediante cromatografía líquida acoplada a un espectrómetro de masas. Previo a la inyección, los extractos fueron resuspendidos en 150 µL de metanol. El contenido de DTX-1 en las muestras fue cuantificado en base al ion padre. Las células vegetativas presentaron un mayor contenido de DTX-1 por célula, en comparación a las células de resistencia.
Automatic taxonomic categorisation of 23 species of dinoflagellates was demonstrated using field-... more Automatic taxonomic categorisation of 23 species of dinoflagellates was demonstrated using field-collected specimens. These dinoflagellates have been responsible for the majority of toxic and noxious phytoplankton blooms which have occurred in the coastal waters of the European Union in recent years and make severe impact on the aquaculture industry. The performance by human 'expert' ecologists/taxonon~ists in identifying these species was compared to that achieved by 2 art~ficial neural network classifiers (multilayer perceptron and radial basis function networks) and 2 other statistical techniques, k-Nearest Neighbour and Quadratic Dlscnm~nant Analysis The neural network classifiers outperform the classical statistical techniques. Over extended trials, the human experts averaged 85% while the radial basis network achieved a best performance of 83%, the multilayer perceptron 66 %, k-Nearest Neighbour 60%, and the Quadratic Discriminant Analysis 56 %.
Journal of Plankton Research, 1996
A comparison was made between the use of linear and quadratic discriminant functions for classify... more A comparison was made between the use of linear and quadratic discriminant functions for classifying phytoplankton specimens of the genera Dinophysis and Ceratium by means of a general morphometric function. The class distributions were found to fit quadratic boundaries better than linear boundaries. A nine species quadratic discriminant classified within 95% confidence intervals. Morphological variants not used in the calibration were all correctly identified, although control species unknown to the model were poorly rejected. An accuracy of 99% was obtained for separating three morphological variants of Dinophysis acuminata. Digital filters were developed to extract the morphometric function directly from photomicrograph images, and present the data as an orientation-independent feature vector. Using this feature vector, a quadratic discriminant classified test data from 14 species of the genera Dinophysis, Ceratium and Ornithocercus with an accuracy of 83%, with 37% of the error due to two similarly shaped species of Dinophysis overlapping.
Toxicon, 2001
The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galici... more The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galician rias (Vigo and Pontevedra) was investigated by high performance liquid chromatography coupled with fluorimetric detection. Boiling and freeze/thaw/hydrolyse methodology were applied during extraction to detect OA, DTX1, DTX2 and their esterified derivatives. OA and DTX2 were detected in both free and esterified form, the latter
Unreported aspects in the sexual cycle of the marine dinoflagellate Lingulodinium polyedrum (Stei... more Unreported aspects in the sexual cycle of the marine dinoflagellate Lingulodinium polyedrum (Stein) Dodge were described. Our observations in- cluded the description of two types of hypnozygote formation, because culture planozygotes were ob- served to encyst in two different ways: an ecdysal sexual stage or a spiny resting cyst. Phosphate de- ficiency was the main nutritional condition required for fusing
Protist, 2015
Elucidation of the cell cycle of dinoflagellates is essential to understand the processes leading... more Elucidation of the cell cycle of dinoflagellates is essential to understand the processes leading to their massive proliferations, known as harmful algal blooms. In this study, we used imaging flow cytometry (IFC) to monitor the changes in DNA content and nuclear and cell morphology that occur during clonal growth of the toxic species Alexandrium minutum Halim. Our results indicate that the population was in S phase (C→2C DNA content) during the light period, whereas haploid cells with a C DNA content peaked only during a short interval of the dark period. The timing of the phases, identified based on the nuclear morphology and cytoplasmic-to-nuclear (CNR) ratio of the cells, suggests that the length of the G2/M phase is regulated by nutrient levels whereas the beginning of S phase is clock controlled. In addition we found that up to 7% of individual cells achieved a DNA content higher than 2C, indicative of either zygote formation and replication (homothallism), or of double-haploid cells able to divide (polyploid forms). Cells belonging to different cell cycle phases (G1-S-G2/M) could be readily discriminated based on nuclear size. Our study provides evidence of cell-cycle plasticity during clonal growth and unambiguously characterizes the cell-cycle phases of this dinoflagellate species. (R.I. Figueroa). phases: G1, in which growing cells exhibit high metabolic activity; S, during which cellular DNA is replicated; and G2, a temporal gap between S phase and the following division in which cells accumulate the nutrients needed for the division process; ii) mitosis (M phase), during which there is nuclear division, or karyokinesis; and iii) cytokinesis, when cytoplasmic division marks the completion of cell division and thus of the cell cycle. The molecular events that determine a cell's http://dx.
Toxicon, 2001
The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galici... more The DSP toxin composition of 19 Prorocentrum lima isolates from different locations of the Galician rias (Vigo and Pontevedra) was investigated by high performance liquid chromatography coupled with fluorimetric detection. Boiling and freeze/thaw/hydrolyse methodology were applied during extraction to detect OA, DTX1, DTX2 and their esterified derivatives. OA and DTX2 were detected in both free and esterified form, the latter always in very low amounts, whilst DTX1 was always present in the free form. This indicate that the hypothesized self-protection mechanism of toxin storage in the less active esterified forms does not seem to apply to DTX1. A slight increase in the toxin concentration per cell was found during growth, although toxin composition did not vary appreciably. Toxin production and toxin profile varied significantly depending on the isolate. Four groups of P. lima were differentiated by cluster analysis according to their toxin composition. It is noteworthy that one of the clusters comprised all the strains collected from one location characterised by its geographical isolation, whereas the other clusters consisted of isolates from different locations. The differences in the toxin profile from P. lima strains and from the DSP contaminated shellfish, together with the very good correlation between Dinophysis spp occurrence and DSP toxicity in shellfish, support that these planktonic species are the main agents responsible for DSP events in Galicia.
Protist, 2013
This study begins with a description of the infective process in the dinoflagellate type host Ale... more This study begins with a description of the infective process in the dinoflagellate type host Alexandrium minutum by a strain of the parasitoid, Parvilucifera sinerae, including the morphologies of the various dinoflagellate and parasitoid stages during the infection. Then, the susceptibility of 433 microalgal strains to P. sinerae infection was studied. The parasitoid was found to be capable of infecting several dinoflagellate species of the genera Alexandrium, Coolia, Dinophysis, Fragilidium, Gambierdiscus, Gymnodinium, Gyrodinium, Heterocapsa, Kryptoperidinium, Lepidodinium, Ostreopsis, Pentapharsodinium, Protoceratium, Scrippsiella, and Woloszynskia. Intra-strain variability was observed as well, such that within the same dinoflagellate species some strains were infected whereas others were not. Likewise, species of other dinoflagellate genera were not infected, such as Akashiwo, Amphidinium, Barrufeta, Bysmatrum, Karenia, Karlodinium, Prorocentrum, and Takayama. Moreover, P. sinerae was not able to infect any of the tested haptophyte, diatom, and chlorophyte species. In natural samples screened for P. sinerae infectivity, several dinoflagellate species of the genera Alexandrium, Coolia, Gonyaulax, Gymnodinium, Phalacroma, Protoperidinium, and Scrippsiella were identified as susceptible. Sporangia size was found to be proportional to the size of the host, and variations in the sporangia size were observed to influence their maturation time.
Protist, 2009
Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus o... more Kryptoperidinium foliaceum is a binucleate dinoflagellate that contains an endosymbiont nucleus of diatom origin. However, it is unknown whether the binucleate condition is permanent or not and how the diatom nucleus behaves during the life history processes. In this sense, it is also unknown if there is a sexual cycle or a resting stage during the life history of this species, two key aspects necessary to understand the life history strategy of this dinoflagellate. To answer these questions, life history and cell cycle studies were performed with the following results: (i) Kryptoperidinium foliaceum has a sexual cycle and in the dinoflagellate strains studied, the binucleate condition is permanent. Sexuality in the host was confirmed by the presence of fusing gamete pairs and planozygotes in clonal cultures (revealing homothallism), but signs of meiosis in the endosymbiont were not observed. The endosymbiont nucleus likely fuses first, because fusing gamete pairs were found to have two dinoflagellate nuclei but only one endosymbiont nucleus. After complete gamete fusion, the planozygotes had apparently normal endosymbiont and dinoflagellate nuclei. (ii) Asexual division studies using flow cytometry showed that the S phase in the endosymbiont (diatom) nucleus starts 6-8 h later than in the host nucleus, but there was no evidence of mitosis in the former. (iii) Sexual and asexual cysts were formed in culture. Neither cysts from natural samples nor those formed in culture exhibited a dormancy period before germination.
Phycologia, 1995
Abstract A new chain-forming dinoflagellate Gyrodinium impudicum sp. nov., Gymnodiniaceae, is des... more Abstract A new chain-forming dinoflagellate Gyrodinium impudicum sp. nov., Gymnodiniaceae, is described from Valencia Harbour, Ría de Vigo (Spain) and Fusaro Lagoon (Italy). The cingulum is a descending left spiral, displaced between 1/3-1/4 of the total length of the cell and the sulcus is without torsion, two reasons why the new species is assigned to Gyrodinium. This red tide organism has been misidentified in several previous papers as Gymnodinium catenatum Graham or Polykrikos schwartzii Bütschli. It differs ...