E. Abollo - Academia.edu (original) (raw)

Papers by E. Abollo

Research paper thumbnail of Anisakis simplex complex (Nematoda: Anisakidae) in zooplankton communities from temperate NE Atlantic waters

The euphausiid Nyctiphanes couchii and an unidentified mysid have been found, for the first time,... more The euphausiid Nyctiphanes couchii and an unidentified mysid have been found, for the first time, with third-stage larvae (L3) of the Anisakis simplex complex in the mesozooplanktonic community of the coastal upwelling system in Galicia (NW Spain). Parasite larvae were molecularly identified using the internal transcribed spacer (ITS) region. The prevalence of these parasites in the euphausiid population was 0.0019%. The existence of parasites in a variety of mesozooplankton organisms suggests that the transmission routes of A. simplex sensu stricto and
A. pegrefii are wider than expected. The results suggest that these two Anisakis species are not specific to their intermediate hosts. Finally, the recruitment of A. simplex complex may be affected by oceanography, differing under upwelling or downwelling conditions.

Research paper thumbnail of Taylor & Francis Online :: Squid as trophic bridges for

Research paper thumbnail of Myxosporean infection in frozen blocks of Patagonian hakes

Journal of food protection, 2008

Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of ... more Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of commercial frozen blocks of Patagonian hakes of the species Macruronus magellanicus, Merluccius australis, and Merluccius hubbsi. Pseudocysts consisted of numerous diminutive quadrate spores with four polar capsules. The small subunit ribosomal DNA was amplified, cloned, and sequenced for phylogenetic study. Minimum evolution and maximum parsimony analyses placed the resulting sequences in a clade with Kudoa species of Patagonian hakes, K. rosenbuschi and K. alliaria, with bootstrap values of 99%. Molecular and morphological results indicated that the above species were the same, with some differences based on host-related factors. Minor muscular damage appeared as a focal distortion of host fiber architecture to accommodate the parasite. The mild host response consisted of different stages of encapsulation. In cases of concurrent heavy infections, these fish are unappealing as food, due...

Research paper thumbnail of Anisakid infection in the European shag Phalacrocorax aristotelis aristotelis

Journal of helminthology, 2001

A total of 100 specimens of the European shag Phalacrocorax aristotelis aristotelis were examined... more A total of 100 specimens of the European shag Phalacrocorax aristotelis aristotelis were examined for anisakid infections in the south-east North Atlantic. The taxonomic status of the anisakid nematodes was studied by structural analysis using light and scanning electron microscopy. Two species, Contracaecum septentrionale and C. rudolphii A (Nematoda: Ascaridoidea), occurred in the European shag with high values of prevalence and mean intensities of infection. These constitute new host records for both parasites, widening their known geographical distribution. Although the histopathology associated with the infections indicated that the anisakids did not have the potential to cause bird death, the parasites are capable of contributing to and hastening avian mortality in the case of heavily-parasitized cormorants and when stressed by xenobiotics and/or through a synergetic effect by other bioagressors.

Research paper thumbnail of Invited review Cell: sporozoite interactions and invasion by apicomplexan parasites of the genus Eimeria

Research paper thumbnail of Genetic evidence for the existence of sibling species within Contracaecum rudolphii (Hartwich, 1964) and the validity of Contracaecum septentrionale (Kreis, 1955) (Nematoda: Anisakidae)

Parasitology Research, 2005

Specimens of Contracaecum rudolphii sensu lato (s.l.) (Nematoda: Anisakidae) from Phalacrocorax c... more Specimens of Contracaecum rudolphii sensu lato (s.l.) (Nematoda: Anisakidae) from Phalacrocorax carbo sinensis from northeastern and central Italy were characterised genetically and compared with those from Phalacrocorax aristotelis from Galician coasts, Spain (identified as C. rudolphii A by multilocus enzyme electrophoresis) and with specimens of C. septentrionale from Alca torda from the Galician coasts, Spain. The first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of ribosomal DNA (rDNA) were amplified by polymerase chain reaction (PCR) from individual nematodes and the amplicons subjected to single-strand conformation polymorphism (SSCP) analysis and/or sequencing. For each ITS region, C. septentrionale specimens were distinct from those of C. rudolphii (s.l.) and C. rudolphii A based on SSCP profiles and ITS sequences. Some specimens of C. rudolphii (s.l.) had the same SSCP profiles and ITS sequences as C. rudolphii A, whereas the others had distinct SSCP profiles and ITS sequences and were suggested to represent C. rudolphii B based on host and geographical origins and genetic similarity to C. rudolphii A. While no length or nucleotide variation in the ITS-1 and ITS-2 sequences was detected within each taxon, nucleotide differences of 1.8-5.5% (ITS-1) and 5.1-12.2% (ITS-2) were detected among them. The results support the hypothesis that C. rudolphii represents a complex of at least two sibling species and provide support for the validity of C. septentrionale as a separate species. The definition of genetic markers in the ITS rDNA provides opportunities for investigating the life cycles, transmission patterns and ecology of the anisakid nematodes studied herein.

Research paper thumbnail of Accumulation of heavy metals in the whaleworm Anisakis simplex s.l. (Nematoda: Anisakidae)

Journal of the Marine Biological Association of the UK, 2003

... Santiago Pascual*P and Elvira AbolloO ... Third-stage larval and adult infrapopulations of th... more ... Santiago Pascual*P and Elvira AbolloO ... Third-stage larval and adult infrapopulations of the whaleworm Anisakis simplex sensu lato (sl) (Nematoda: Anisakidae) from their respective ¢sh, cephalopod and cetacean hosts caught or stranded in the Galician coast (north-west Spain ...

Research paper thumbnail of Role of microRNAs in the immunity process of the flat oyster Ostrea edulis against bonamiosis

Infection, Genetics and Evolution, 2014

MicroRNAs (miRNAs) are small (∼22nt) non-coding regulatory single strand RNA molecules that reduc... more MicroRNAs (miRNAs) are small (∼22nt) non-coding regulatory single strand RNA molecules that reduce stability and/or translation of sequence-complementary target. miRNAs are a key component of gene regulatory networks and have been involved in a wide variety of biological processes, such as signal transduction, cell proliferation and apoptosis. Many miRNAs are broadly conserved among the animal lineages and even between invertebrates and vertebrates. The European flat oyster Ostrea edulis is highly susceptible to infection with Bonamia ostreae, an intracellular parasite able to survive and proliferate within oyster haemocytes. Mollusc haemocytes play a key role in the immune response of molluscs as main cellular effectors. The roles of miRNAs in the immune response of O. edulis to bonamiosis were analysed using a commercial microarray platform (miRCURY LNA™ v2, Exiqon) for miRNAs. Expression of miRNAs in haemocytes from oysters with different bonamiosis intensity was compared. Differential expression was detected in 63 and 76 miRNAs when comparing heavily-affected with non-affected oysters and with lightly-affected ones, respectively. Among them, 19 miRNAs are known to be linked to immune response, being responsible of proliferation and activation of macrophages, inflammation, apoptosis and/or oxidative damage, which is consistent with the modulation of their expression in oyster haemocytes due to bonamiosis.

Research paper thumbnail of Infection of Manila clams Ruditapes philippinarum from Galicia (NW Spain) with a Mikrocytos-like parasite

Diseases of Aquatic Organisms, 2014

The name &amp... more The name 'microcells' is frequently used to refer to small-sized unicellular stages of molluscan parasites of the genera Bonamia (Rhizaria, Haplosporidia) and Mikrocytos (Rhizaria). Histological examination of Manila clams Ruditapes philippinarum revealed microcells in the connective tissue of adductor muscle, foot, mantle, gills, siphon and visceral mass. The clams had been collected from 4 beds on the coast of Galicia, Spain. The prevalence of these microcells ranged from 73 to 93% in surface clams and from 3 to 33% in buried clams. However, the detection of brown ring disease signs in clams from every bed prevented us from making the assumption that the microcells alone were responsible for clam mortality. PCR assays using primer pairs designed to detect Bonamia spp. and haplosporidians gave negative results, whereas positive results were obtained with primers for the genus Mikrocytos. A consensus sequence of 1670 bp of the ribosomal gene complex of the microcells was obtained. It contained a section of the 18S region, the whole first internal transcribed spacer, the 5.8S region, the second internal transcribed spacer and a section of the 28S region. Comparison of this sequence with those of M. mackini infecting Crassostrea gigas and Mikrocytos sp. infecting Ostrea edulis showed that the microcells of Galician clams were the most divergent among the compared parasites. This is the first report of a Mikrocytos-like parasite infecting Manila clams. Care must be taken to avoid the spread of this parasite through Manila clam transfers.

Research paper thumbnail of Whaleworms as a tag to map zones of heavy-metal pollution

Trends in Parasitology, 2005

Cover: Oral and topical applications of insecticides have revolutionized the control of cat fleas... more Cover: Oral and topical applications of insecticides have revolutionized the control of cat fleas (Ctenocephalides felis) on cats and dogs, eliminating the need for environmental treatments and reducing the incidence and severity of flea allergic dermatitis (see pp. 232-236).

Research paper thumbnail of Renal coccidiosis in the European cormorant Phalacrocorax aristotelis aristotelis from the Galician coast

Journal of the Marine Biological Association of the United Kingdom, 2005

Research paper thumbnail of Aggregata sagittata n. sp. (Apicomplexa: Aggregatidae), a coccidian parasite from the European flying squid Todarodes sagittatus (Mollusca: Cephalopoda)

Systematic Parasitology, 2000

A new species of the coccidian genus Aggregata Frenzel, 1885 (Apicomplexa, Aggregatidae) is descr... more A new species of the coccidian genus Aggregata Frenzel, 1885 (Apicomplexa, Aggregatidae) is described from the digestive tract of Todarodes sagittatus (Lamarck), an ommastrephid squid that lives in temperate waters in the northeastern Atlantic Ocean. Using light microscopy, oöcysts were 225-333 µm in length and 220-323 µm in width. Each oöcyst contained 600-1,000 sporocysts. Sporocysts were 16-18 µm in length and 15-17µm in width, with a smooth surface and thick wall. Each sporocyst contained 4-8 sporozoites each with a length of 11-13 µm. This paper presents the description of a new Aggregata species in a nerito-oceanic flying squid. Moreover, it extends the distribution of Aggregata to oceanic cephalopod host species. A. sagittata represents the third named species in the genus Aggregata in European waters and the seventh worldwide.

Research paper thumbnail of An SEM study of Phocascaris cystophorae Berland, 1964 (Nematoda: Anisakidae), a parasite of the hooded seal Cystophora cristata

Systematic Parasitology, 2002

Scanning electron microscopy was used to study the surface morphological characteristics (excreto... more Scanning electron microscopy was used to study the surface morphological characteristics (excretory pore, interlabia knobs, lips and adjacent structures, caudal papillae and papilla-like structures) of the nematode Phocascaris cystophorae, a parasite from the stomach of the hooded seal Cystophora cristata. A comparative morphological analysis was made between species of Phocascaris and Contracaecum osculatum (sensu lato), which are all parasitic in phocid seals.

Research paper thumbnail of Anisakis infestation in marine fish and cephalopods from Galician waters: an updated perspective

Parasitology Research, 2001

A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained fro... more A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained from commercial local fisheries in Galician waters (NW Spain). They were examined for anisakid nematodes by digestion of the muscle and elution of the viscera and whole body cavity. All larval nematodes recovered were identified by light microscopy and multilocus electrophoresis as belonging to the species Anisakis simplex sensu stricto and A. pegreffii. Encysted larvae mostly occurred in the viscera but were also found in the flesh of squid and fish. Demographic values for larval nematodes are discussed in relation to host preferences and the ecological niche of both anisakid species at the sampling area. Primary recommendations are also expressed concerning the effects of current fishing and aquaculture practices on the Anisakis problem.

Research paper thumbnail of Differential diagnosis of Perkinsus species by polymerase chain reaction-restriction fragment length polymorphism assay

Molecular and Cellular Probes, 2006

Perkinsosis is an infection of marine molluscs caused by the protistan parasites of the genus Per... more Perkinsosis is an infection of marine molluscs caused by the protistan parasites of the genus Perkinsus, which has been classified by the OIE as a disease that warrants notification. In the present study, we have applied a molecular genetic approach to develop an optional method for the specific identification of Perkinsus species.

Research paper thumbnail of Identification of Relevant Cancer Related-Genes in the Flat Oyster Ostrea edulis Affected by Disseminated Neoplasia

Marine Biotechnology, 2013

Disseminated neoplasia (DN), an oyster disease resembling leukaemia, has been reported in a numbe... more Disseminated neoplasia (DN), an oyster disease resembling leukaemia, has been reported in a number of species of marine bivalve molluscs. The disease is characterised by a proliferation of abnormal circulating cells of unknown origin resulting in the invasion of tissues and organs, frequently with a fatal end of the affected individuals. To obtain a more comprehensive view of bivalve cancer processes, suppressive subtracted hybridisation (SSH) and quantitative RT-PCR (q-PCR) approaches were combined to investigate changes in the transcriptome of Ostrea edulis haemolymph cells associated to DN. Two SSH libraries were constructed and 587 expressed sequence tags (ESTs) were sequenced, obtaining 329 ESTs which showed expression changes in neoplastic process. Transcription expression analyses (q-PCR) were done for a total of 24 genes that could be relevant in neoplastic process, including genes with role in the regulation of cell cycle, apoptosis or chromosomal defects. Most of those genes had not been reported in association with cancer in non-vertebrate organisms. The over-expression and under-expression of some of those genes in DN-affected oysters was in agreement with observations in vertebrate cancer. The results herein reported contribute to cancer understanding in bivalve molluscs.

Research paper thumbnail of The occurrence of haplosporidian parasites, Haplosporidium nelsoni and Haplosporidium sp., in oysters in Ireland

Journal of Invertebrate Pathology, 2013

The phylum Haplosporidia is a group of obligate protozoan parasites that infect a number of fresh... more The phylum Haplosporidia is a group of obligate protozoan parasites that infect a number of freshwater and marine invertebrates. Haplosporidian parasites have caused significant mortalities in commercially important shellfish species worldwide. In this study, haplosporidia were detected in Pacific oysters Crassostrea gigas originating in Ireland and were subsequently identified independently in laboratories both in Ireland and in Spain as Haplosporidium nelsoni. In Ireland, H. nelsoni plasmodia were also observed in the heart tissue of a single Ostrea edulis. A range of techniques including heart smear screening, histology, standard polymerase chain reaction (PCR), direct sequencing and in situ hybridisation with an H. nelsoni specific DNA probe were carried out to confirm diagnosis. This is the first reporting of H. nelsoni in oysters in Ireland and this is the first reporting of the detection of this haplosporidian in O. edulis. In Ireland, another haplosporidian was also observed in a single O. edulis during heart smear screening. PCR and DNA sequencing were carried out and indicated the presence of a Haplosporidium sp., most likely Haplosporidium armoricanum. The low prevalence and intensity of infection of both haplosporidian species in Irish C. gigas and in particular O. edulis may indicate that their presence is inconsequential.

Research paper thumbnail of Comparison of haemocytic parameters among flat oyster Ostrea edulis stocks with different susceptibility to bonamiosis and the Pacific oyster Crassostrea gigas

Journal of Invertebrate Pathology, 2012

Farming of the flat oyster Ostrea edulis in Europe is severely constrained by the protozoan Bonam... more Farming of the flat oyster Ostrea edulis in Europe is severely constrained by the protozoan Bonamia ostreae. The introduction of the resistant species Crassostrea gigas has been a relief for the farmers, while the pilot programmes to select O. edulis strains resistant to bonamiosis performed in various countries can be seen as a promising strategy to minimise the effects of bonamiosis. However, the physiological bases of this differential susceptibility remain unknown. A search for an explanation of the intra and interspecific differences in oyster susceptibility to bonamiosis was accomplished by comparing some immune parameters among various O. edulis stocks and C. gigas. On December 2003, naïve and Bonamia-relatively resistant flat oysters from Ireland, Galician flat oysters and Pacific oysters C. gigas were deployed in a Galician area affected by bonamiosis; haemolymph samples were taken in February and May 2004. A new oyster deployment at the same place was carried out on June 2004 and haemolymph sampling was performed on April 2005. On November 2004, new sets of Irish flat oysters and C. gigas were deployed in Ireland and haemolymph sampling was performed in June 2005. Various haemocytic parameters were measured: total and differential haemocyte count, phagocytic ability, respiratory burst (superoxide anion [ ] and hydrogen peroxide [H 2 O 2 ]) and nitric oxide [NO] production. The comparison of the parameters was carried out at 3 levels: (1) between O. edulis and C. gigas, (2) among O. edulis stocks with different susceptibility to bonamiosis, and between Bonamia-infected and non infected O. edulis. In addition, haemocyte-B. ostreaein vitro encounters were performed to analyse interspecific differences in the haemocytic respiratory burst, using flow cytometry. Significant differences associated with total and differential haemocyte count, and respiratory burst between O. edulis and C. gigas were detected, which could be linked to differences in susceptibility to bonamiosis between both species. Additionally, significant changes in total and differential haemocyte count, and respiratory burst of O. edulis associated with B. ostreae infection were found. However, no consistent difference in any haemocyte parameter between the O. edulis stocks involved in the study was recorded.

Research paper thumbnail of Hepatic coccidiosis of the blue whiting, Micromesistius poutassou (Risso), and horse mackerel, Trachurus trachurus (L.), from Galician waters

Journal of Fish Diseases, 2001

ABSTRACT

Research paper thumbnail of Genetic divergence and reproductive isolation between Anisakis brevispiculata and Anisakis physeteris (Nematoda: Anisakidae)s

International Journal for Parasitology, 2001

In order to assess the taxonomic status of Anisakis brevispiculata Dollfus, 1966 population sampl... more In order to assess the taxonomic status of Anisakis brevispiculata Dollfus, 1966 population samples of this taxon from central and south-eastern Atlantic ocean were compared at 22 enzymatic loci with samples belonging to Anisakis physeteris Baylis, 1923 from the Mediterranean sea and central-eastern Atlantic ocean. Very low interpopulational genetic divergence was observed both within A. brevispiculata (average D(Nei) = 0.008) and within A. physeteris (D(Nei) = 0.009) despite the geographic distance among the samples, indicating high levels of gene flow in both taxa. On the other hand, the average genetic distance between A. brevispiculata and A. physeteris was found to be D(Nei) = 0.80, a value generally observed between well differentiated congeneric species. The reproductive isolation between A. brevispiculata and A. physeteris is indicated by the following observations: (1) no F(1) hybrids or recombinant genotypes were until now observed; and (2) the two Anisakis species do not seem to share their definitive hosts. The main definitive host of A. brevispiculata is the pygmy sperm whale (Kogia breviceps), while for A. physeteris it is the sperm whale (Physeter catodon). Only adult males differ slightly in spicule length, while females and larval stages are not differentiated morphologically. Both A. brevispiculata and A.physeteris show a type II larva. The correct recognition of A. brevispiculata from A. physeteris and from other Anisakis species studied, in either sexes and at any life stage, is made easy by allozyme markers (e.g. Icdh, Gapdh, Sod-1, Np, Aat-2, Adk-2, fEst-2, PepB, PepC-2, Mpi). Diagnostic keys, which can be used for routine identification in the field of these Anisakis worms, based on genetic markers, are given.

Research paper thumbnail of Anisakis simplex complex (Nematoda: Anisakidae) in zooplankton communities from temperate NE Atlantic waters

The euphausiid Nyctiphanes couchii and an unidentified mysid have been found, for the first time,... more The euphausiid Nyctiphanes couchii and an unidentified mysid have been found, for the first time, with third-stage larvae (L3) of the Anisakis simplex complex in the mesozooplanktonic community of the coastal upwelling system in Galicia (NW Spain). Parasite larvae were molecularly identified using the internal transcribed spacer (ITS) region. The prevalence of these parasites in the euphausiid population was 0.0019%. The existence of parasites in a variety of mesozooplankton organisms suggests that the transmission routes of A. simplex sensu stricto and
A. pegrefii are wider than expected. The results suggest that these two Anisakis species are not specific to their intermediate hosts. Finally, the recruitment of A. simplex complex may be affected by oceanography, differing under upwelling or downwelling conditions.

Research paper thumbnail of Taylor & Francis Online :: Squid as trophic bridges for

Research paper thumbnail of Myxosporean infection in frozen blocks of Patagonian hakes

Journal of food protection, 2008

Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of ... more Numerous pseudocysts of the myxosporean genus Kudoa were found infecting the body musculature of commercial frozen blocks of Patagonian hakes of the species Macruronus magellanicus, Merluccius australis, and Merluccius hubbsi. Pseudocysts consisted of numerous diminutive quadrate spores with four polar capsules. The small subunit ribosomal DNA was amplified, cloned, and sequenced for phylogenetic study. Minimum evolution and maximum parsimony analyses placed the resulting sequences in a clade with Kudoa species of Patagonian hakes, K. rosenbuschi and K. alliaria, with bootstrap values of 99%. Molecular and morphological results indicated that the above species were the same, with some differences based on host-related factors. Minor muscular damage appeared as a focal distortion of host fiber architecture to accommodate the parasite. The mild host response consisted of different stages of encapsulation. In cases of concurrent heavy infections, these fish are unappealing as food, due...

Research paper thumbnail of Anisakid infection in the European shag Phalacrocorax aristotelis aristotelis

Journal of helminthology, 2001

A total of 100 specimens of the European shag Phalacrocorax aristotelis aristotelis were examined... more A total of 100 specimens of the European shag Phalacrocorax aristotelis aristotelis were examined for anisakid infections in the south-east North Atlantic. The taxonomic status of the anisakid nematodes was studied by structural analysis using light and scanning electron microscopy. Two species, Contracaecum septentrionale and C. rudolphii A (Nematoda: Ascaridoidea), occurred in the European shag with high values of prevalence and mean intensities of infection. These constitute new host records for both parasites, widening their known geographical distribution. Although the histopathology associated with the infections indicated that the anisakids did not have the potential to cause bird death, the parasites are capable of contributing to and hastening avian mortality in the case of heavily-parasitized cormorants and when stressed by xenobiotics and/or through a synergetic effect by other bioagressors.

Research paper thumbnail of Invited review Cell: sporozoite interactions and invasion by apicomplexan parasites of the genus Eimeria

Research paper thumbnail of Genetic evidence for the existence of sibling species within Contracaecum rudolphii (Hartwich, 1964) and the validity of Contracaecum septentrionale (Kreis, 1955) (Nematoda: Anisakidae)

Parasitology Research, 2005

Specimens of Contracaecum rudolphii sensu lato (s.l.) (Nematoda: Anisakidae) from Phalacrocorax c... more Specimens of Contracaecum rudolphii sensu lato (s.l.) (Nematoda: Anisakidae) from Phalacrocorax carbo sinensis from northeastern and central Italy were characterised genetically and compared with those from Phalacrocorax aristotelis from Galician coasts, Spain (identified as C. rudolphii A by multilocus enzyme electrophoresis) and with specimens of C. septentrionale from Alca torda from the Galician coasts, Spain. The first (ITS-1) and second (ITS-2) internal transcribed spacers (ITS) of ribosomal DNA (rDNA) were amplified by polymerase chain reaction (PCR) from individual nematodes and the amplicons subjected to single-strand conformation polymorphism (SSCP) analysis and/or sequencing. For each ITS region, C. septentrionale specimens were distinct from those of C. rudolphii (s.l.) and C. rudolphii A based on SSCP profiles and ITS sequences. Some specimens of C. rudolphii (s.l.) had the same SSCP profiles and ITS sequences as C. rudolphii A, whereas the others had distinct SSCP profiles and ITS sequences and were suggested to represent C. rudolphii B based on host and geographical origins and genetic similarity to C. rudolphii A. While no length or nucleotide variation in the ITS-1 and ITS-2 sequences was detected within each taxon, nucleotide differences of 1.8-5.5% (ITS-1) and 5.1-12.2% (ITS-2) were detected among them. The results support the hypothesis that C. rudolphii represents a complex of at least two sibling species and provide support for the validity of C. septentrionale as a separate species. The definition of genetic markers in the ITS rDNA provides opportunities for investigating the life cycles, transmission patterns and ecology of the anisakid nematodes studied herein.

Research paper thumbnail of Accumulation of heavy metals in the whaleworm Anisakis simplex s.l. (Nematoda: Anisakidae)

Journal of the Marine Biological Association of the UK, 2003

... Santiago Pascual*P and Elvira AbolloO ... Third-stage larval and adult infrapopulations of th... more ... Santiago Pascual*P and Elvira AbolloO ... Third-stage larval and adult infrapopulations of the whaleworm Anisakis simplex sensu lato (sl) (Nematoda: Anisakidae) from their respective ¢sh, cephalopod and cetacean hosts caught or stranded in the Galician coast (north-west Spain ...

Research paper thumbnail of Role of microRNAs in the immunity process of the flat oyster Ostrea edulis against bonamiosis

Infection, Genetics and Evolution, 2014

MicroRNAs (miRNAs) are small (∼22nt) non-coding regulatory single strand RNA molecules that reduc... more MicroRNAs (miRNAs) are small (∼22nt) non-coding regulatory single strand RNA molecules that reduce stability and/or translation of sequence-complementary target. miRNAs are a key component of gene regulatory networks and have been involved in a wide variety of biological processes, such as signal transduction, cell proliferation and apoptosis. Many miRNAs are broadly conserved among the animal lineages and even between invertebrates and vertebrates. The European flat oyster Ostrea edulis is highly susceptible to infection with Bonamia ostreae, an intracellular parasite able to survive and proliferate within oyster haemocytes. Mollusc haemocytes play a key role in the immune response of molluscs as main cellular effectors. The roles of miRNAs in the immune response of O. edulis to bonamiosis were analysed using a commercial microarray platform (miRCURY LNA™ v2, Exiqon) for miRNAs. Expression of miRNAs in haemocytes from oysters with different bonamiosis intensity was compared. Differential expression was detected in 63 and 76 miRNAs when comparing heavily-affected with non-affected oysters and with lightly-affected ones, respectively. Among them, 19 miRNAs are known to be linked to immune response, being responsible of proliferation and activation of macrophages, inflammation, apoptosis and/or oxidative damage, which is consistent with the modulation of their expression in oyster haemocytes due to bonamiosis.

Research paper thumbnail of Infection of Manila clams Ruditapes philippinarum from Galicia (NW Spain) with a Mikrocytos-like parasite

Diseases of Aquatic Organisms, 2014

The name &amp... more The name 'microcells' is frequently used to refer to small-sized unicellular stages of molluscan parasites of the genera Bonamia (Rhizaria, Haplosporidia) and Mikrocytos (Rhizaria). Histological examination of Manila clams Ruditapes philippinarum revealed microcells in the connective tissue of adductor muscle, foot, mantle, gills, siphon and visceral mass. The clams had been collected from 4 beds on the coast of Galicia, Spain. The prevalence of these microcells ranged from 73 to 93% in surface clams and from 3 to 33% in buried clams. However, the detection of brown ring disease signs in clams from every bed prevented us from making the assumption that the microcells alone were responsible for clam mortality. PCR assays using primer pairs designed to detect Bonamia spp. and haplosporidians gave negative results, whereas positive results were obtained with primers for the genus Mikrocytos. A consensus sequence of 1670 bp of the ribosomal gene complex of the microcells was obtained. It contained a section of the 18S region, the whole first internal transcribed spacer, the 5.8S region, the second internal transcribed spacer and a section of the 28S region. Comparison of this sequence with those of M. mackini infecting Crassostrea gigas and Mikrocytos sp. infecting Ostrea edulis showed that the microcells of Galician clams were the most divergent among the compared parasites. This is the first report of a Mikrocytos-like parasite infecting Manila clams. Care must be taken to avoid the spread of this parasite through Manila clam transfers.

Research paper thumbnail of Whaleworms as a tag to map zones of heavy-metal pollution

Trends in Parasitology, 2005

Cover: Oral and topical applications of insecticides have revolutionized the control of cat fleas... more Cover: Oral and topical applications of insecticides have revolutionized the control of cat fleas (Ctenocephalides felis) on cats and dogs, eliminating the need for environmental treatments and reducing the incidence and severity of flea allergic dermatitis (see pp. 232-236).

Research paper thumbnail of Renal coccidiosis in the European cormorant Phalacrocorax aristotelis aristotelis from the Galician coast

Journal of the Marine Biological Association of the United Kingdom, 2005

Research paper thumbnail of Aggregata sagittata n. sp. (Apicomplexa: Aggregatidae), a coccidian parasite from the European flying squid Todarodes sagittatus (Mollusca: Cephalopoda)

Systematic Parasitology, 2000

A new species of the coccidian genus Aggregata Frenzel, 1885 (Apicomplexa, Aggregatidae) is descr... more A new species of the coccidian genus Aggregata Frenzel, 1885 (Apicomplexa, Aggregatidae) is described from the digestive tract of Todarodes sagittatus (Lamarck), an ommastrephid squid that lives in temperate waters in the northeastern Atlantic Ocean. Using light microscopy, oöcysts were 225-333 µm in length and 220-323 µm in width. Each oöcyst contained 600-1,000 sporocysts. Sporocysts were 16-18 µm in length and 15-17µm in width, with a smooth surface and thick wall. Each sporocyst contained 4-8 sporozoites each with a length of 11-13 µm. This paper presents the description of a new Aggregata species in a nerito-oceanic flying squid. Moreover, it extends the distribution of Aggregata to oceanic cephalopod host species. A. sagittata represents the third named species in the genus Aggregata in European waters and the seventh worldwide.

Research paper thumbnail of An SEM study of Phocascaris cystophorae Berland, 1964 (Nematoda: Anisakidae), a parasite of the hooded seal Cystophora cristata

Systematic Parasitology, 2002

Scanning electron microscopy was used to study the surface morphological characteristics (excreto... more Scanning electron microscopy was used to study the surface morphological characteristics (excretory pore, interlabia knobs, lips and adjacent structures, caudal papillae and papilla-like structures) of the nematode Phocascaris cystophorae, a parasite from the stomach of the hooded seal Cystophora cristata. A comparative morphological analysis was made between species of Phocascaris and Contracaecum osculatum (sensu lato), which are all parasitic in phocid seals.

Research paper thumbnail of Anisakis infestation in marine fish and cephalopods from Galician waters: an updated perspective

Parasitology Research, 2001

A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained fro... more A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained from commercial local fisheries in Galician waters (NW Spain). They were examined for anisakid nematodes by digestion of the muscle and elution of the viscera and whole body cavity. All larval nematodes recovered were identified by light microscopy and multilocus electrophoresis as belonging to the species Anisakis simplex sensu stricto and A. pegreffii. Encysted larvae mostly occurred in the viscera but were also found in the flesh of squid and fish. Demographic values for larval nematodes are discussed in relation to host preferences and the ecological niche of both anisakid species at the sampling area. Primary recommendations are also expressed concerning the effects of current fishing and aquaculture practices on the Anisakis problem.

Research paper thumbnail of Differential diagnosis of Perkinsus species by polymerase chain reaction-restriction fragment length polymorphism assay

Molecular and Cellular Probes, 2006

Perkinsosis is an infection of marine molluscs caused by the protistan parasites of the genus Per... more Perkinsosis is an infection of marine molluscs caused by the protistan parasites of the genus Perkinsus, which has been classified by the OIE as a disease that warrants notification. In the present study, we have applied a molecular genetic approach to develop an optional method for the specific identification of Perkinsus species.

Research paper thumbnail of Identification of Relevant Cancer Related-Genes in the Flat Oyster Ostrea edulis Affected by Disseminated Neoplasia

Marine Biotechnology, 2013

Disseminated neoplasia (DN), an oyster disease resembling leukaemia, has been reported in a numbe... more Disseminated neoplasia (DN), an oyster disease resembling leukaemia, has been reported in a number of species of marine bivalve molluscs. The disease is characterised by a proliferation of abnormal circulating cells of unknown origin resulting in the invasion of tissues and organs, frequently with a fatal end of the affected individuals. To obtain a more comprehensive view of bivalve cancer processes, suppressive subtracted hybridisation (SSH) and quantitative RT-PCR (q-PCR) approaches were combined to investigate changes in the transcriptome of Ostrea edulis haemolymph cells associated to DN. Two SSH libraries were constructed and 587 expressed sequence tags (ESTs) were sequenced, obtaining 329 ESTs which showed expression changes in neoplastic process. Transcription expression analyses (q-PCR) were done for a total of 24 genes that could be relevant in neoplastic process, including genes with role in the regulation of cell cycle, apoptosis or chromosomal defects. Most of those genes had not been reported in association with cancer in non-vertebrate organisms. The over-expression and under-expression of some of those genes in DN-affected oysters was in agreement with observations in vertebrate cancer. The results herein reported contribute to cancer understanding in bivalve molluscs.

Research paper thumbnail of The occurrence of haplosporidian parasites, Haplosporidium nelsoni and Haplosporidium sp., in oysters in Ireland

Journal of Invertebrate Pathology, 2013

The phylum Haplosporidia is a group of obligate protozoan parasites that infect a number of fresh... more The phylum Haplosporidia is a group of obligate protozoan parasites that infect a number of freshwater and marine invertebrates. Haplosporidian parasites have caused significant mortalities in commercially important shellfish species worldwide. In this study, haplosporidia were detected in Pacific oysters Crassostrea gigas originating in Ireland and were subsequently identified independently in laboratories both in Ireland and in Spain as Haplosporidium nelsoni. In Ireland, H. nelsoni plasmodia were also observed in the heart tissue of a single Ostrea edulis. A range of techniques including heart smear screening, histology, standard polymerase chain reaction (PCR), direct sequencing and in situ hybridisation with an H. nelsoni specific DNA probe were carried out to confirm diagnosis. This is the first reporting of H. nelsoni in oysters in Ireland and this is the first reporting of the detection of this haplosporidian in O. edulis. In Ireland, another haplosporidian was also observed in a single O. edulis during heart smear screening. PCR and DNA sequencing were carried out and indicated the presence of a Haplosporidium sp., most likely Haplosporidium armoricanum. The low prevalence and intensity of infection of both haplosporidian species in Irish C. gigas and in particular O. edulis may indicate that their presence is inconsequential.

Research paper thumbnail of Comparison of haemocytic parameters among flat oyster Ostrea edulis stocks with different susceptibility to bonamiosis and the Pacific oyster Crassostrea gigas

Journal of Invertebrate Pathology, 2012

Farming of the flat oyster Ostrea edulis in Europe is severely constrained by the protozoan Bonam... more Farming of the flat oyster Ostrea edulis in Europe is severely constrained by the protozoan Bonamia ostreae. The introduction of the resistant species Crassostrea gigas has been a relief for the farmers, while the pilot programmes to select O. edulis strains resistant to bonamiosis performed in various countries can be seen as a promising strategy to minimise the effects of bonamiosis. However, the physiological bases of this differential susceptibility remain unknown. A search for an explanation of the intra and interspecific differences in oyster susceptibility to bonamiosis was accomplished by comparing some immune parameters among various O. edulis stocks and C. gigas. On December 2003, naïve and Bonamia-relatively resistant flat oysters from Ireland, Galician flat oysters and Pacific oysters C. gigas were deployed in a Galician area affected by bonamiosis; haemolymph samples were taken in February and May 2004. A new oyster deployment at the same place was carried out on June 2004 and haemolymph sampling was performed on April 2005. On November 2004, new sets of Irish flat oysters and C. gigas were deployed in Ireland and haemolymph sampling was performed in June 2005. Various haemocytic parameters were measured: total and differential haemocyte count, phagocytic ability, respiratory burst (superoxide anion [ ] and hydrogen peroxide [H 2 O 2 ]) and nitric oxide [NO] production. The comparison of the parameters was carried out at 3 levels: (1) between O. edulis and C. gigas, (2) among O. edulis stocks with different susceptibility to bonamiosis, and between Bonamia-infected and non infected O. edulis. In addition, haemocyte-B. ostreaein vitro encounters were performed to analyse interspecific differences in the haemocytic respiratory burst, using flow cytometry. Significant differences associated with total and differential haemocyte count, and respiratory burst between O. edulis and C. gigas were detected, which could be linked to differences in susceptibility to bonamiosis between both species. Additionally, significant changes in total and differential haemocyte count, and respiratory burst of O. edulis associated with B. ostreae infection were found. However, no consistent difference in any haemocyte parameter between the O. edulis stocks involved in the study was recorded.

Research paper thumbnail of Hepatic coccidiosis of the blue whiting, Micromesistius poutassou (Risso), and horse mackerel, Trachurus trachurus (L.), from Galician waters

Journal of Fish Diseases, 2001

ABSTRACT

Research paper thumbnail of Genetic divergence and reproductive isolation between Anisakis brevispiculata and Anisakis physeteris (Nematoda: Anisakidae)s

International Journal for Parasitology, 2001

In order to assess the taxonomic status of Anisakis brevispiculata Dollfus, 1966 population sampl... more In order to assess the taxonomic status of Anisakis brevispiculata Dollfus, 1966 population samples of this taxon from central and south-eastern Atlantic ocean were compared at 22 enzymatic loci with samples belonging to Anisakis physeteris Baylis, 1923 from the Mediterranean sea and central-eastern Atlantic ocean. Very low interpopulational genetic divergence was observed both within A. brevispiculata (average D(Nei) = 0.008) and within A. physeteris (D(Nei) = 0.009) despite the geographic distance among the samples, indicating high levels of gene flow in both taxa. On the other hand, the average genetic distance between A. brevispiculata and A. physeteris was found to be D(Nei) = 0.80, a value generally observed between well differentiated congeneric species. The reproductive isolation between A. brevispiculata and A. physeteris is indicated by the following observations: (1) no F(1) hybrids or recombinant genotypes were until now observed; and (2) the two Anisakis species do not seem to share their definitive hosts. The main definitive host of A. brevispiculata is the pygmy sperm whale (Kogia breviceps), while for A. physeteris it is the sperm whale (Physeter catodon). Only adult males differ slightly in spicule length, while females and larval stages are not differentiated morphologically. Both A. brevispiculata and A.physeteris show a type II larva. The correct recognition of A. brevispiculata from A. physeteris and from other Anisakis species studied, in either sexes and at any life stage, is made easy by allozyme markers (e.g. Icdh, Gapdh, Sod-1, Np, Aat-2, Adk-2, fEst-2, PepB, PepC-2, Mpi). Diagnostic keys, which can be used for routine identification in the field of these Anisakis worms, based on genetic markers, are given.