Baptista M.,University of Lisbon |
Lopes V.M.,University of Lisbon |
Pimentel M.S.,University of Lisbon |
Bandarra N.,IPIMAR |
And 3 more authors.
Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology | Year: 2012
The objectives of the present work were to investigate the temporal variation in the fatty acid (FA) composition of the octocoral Veretillum cynomorium, examine the effects of reproduction and environmental factors on FA variation, and establish a chemotaxonomic identification for this species. Mean oocyte size-frequency distributions showed that the majority of the oocytes had an intermediate size (Group II) before spawning (April and June). The late-vitellogenic oocytes (Group III) became absent in August and October and, during this post-spawning period, oocytes were primarily of small size (Group I). Most of the major FA, 16:0, 18:0, 20:4. n-6, 20:5. n-3, and the tetracosapolyenoic fatty acid (TPA), 24:6. n-3, varied significantly throughout the year (p < 0.01), with two peaks in August/October and February. The boost in early oogenesis, also associated with warmer temperatures, seemed to be responsible for the observed increase in FA content between June and August. The highest values of FA content were observed in February when intermediate oogenesis (Group II) was at its peak and there were considerable levels of available food in the environment. Also, the increase in food availability seemed to trigger the final stages of gametogenesis. The high quantity of 18:1. n-7, odd-numbered and branched FAs, suggested the presence of a dynamic bacterial community in V. cynomorium, probably as an adaptive response to the lack of symbiotic microalgae. Although the presence of TPAs is the main feature distinguishing octocorals from other coral species, here we showed that there was no single FA clearly dominating the FA composition of V. cynomorium throughout the year. Instead, four main FAs share similar concentrations: 16:0, 20:4. n-6, 20:5. n-3 and 24:6. n-3. The predominance of these four FAs combined with the higher amount of 24:6. n-3 when compared to 24:5. n-6 may serve as a chemotaxonomic feature to distinguish this octocoral species (or genus). © 2011 Elsevier Inc.
Cabrita M.T.,IPIMAR |
Vale C.,IPIMAR |
Rauter A.P.,University of Lisbon
Marine Drugs | Year: 2010
Marine algae produce a cocktail of halogenated metabolites with potential commercial value. Structures exhibited by these compounds go from acyclic entities with a linear chain to complex polycyclic molecules. Their medical and pharmaceutical application has been investigated for a few decades, however other properties, such as antifouling, are not to be discarded. Many compounds were discovered in the last years, although the need for new drugs keeps this field open as many algal species are poorly screened. The ecological role of marine algal halogenated metabolites has somehow been overlooked. This new research field will provide valuable and novel insight into the marine ecosystem dynamics as well as a new approach to comprehending biodiversity. Furthermore, understanding interactions between halogenated compound production by algae and the environment, including anthropogenic or global climate changes, is a challenging target for the coming years. Research of halogenated metabolites has been more focused on macroalgae than on phytoplankton. However, phytoplankton could be a very promising material since it is the base of the marine food chain with quick adaptation to environmental changes, which undoubtedly has consequences on secondary metabolism. This paper reviews recent progress on this field and presents trends on the role of marine algae as producers of halogenated compounds. © 2010 by the authors; licensee MDPI.
Rosa L.G.,University of Lisbon |
Materials Science Forum | Year: 2010
In statistical analysis of failure data of brittle materials, the use of maximum likelihood estimators shows many advantages compared to other methods. The applicability and the robustness of the maximum likelihood method to analyze and to distinguish the data in several mixtures of two Weibull populations is demonstrated in this work. Estimations of percentage of data belonging to each of the populations, as well as Weibull parameters of the populations, are relatively simple to be conducted using adequate software. © (2010) Trans Tech Publications.
Perez S.,University of Santiago de Compostela |
Vale C.,University of Santiago de Compostela |
Alonso E.,University of Santiago de Compostela |
Alfonso C.,University of Santiago de Compostela |
And 7 more authors.
Chemical Research in Toxicology | Year: 2011
Ciguatera is a global disease caused by the consumption of certain warm-water fish (ciguateric fish) that have accumulated orally effective levels of sodium channel activator toxins (ciguatoxins) through the marine food chain. The effect of ciguatoxin standards and contaminated ciguatoxin samples was evaluated by electrophysiological recordings in cultured cerebellar neurons. The toxins affected both voltage-gated sodium (Nav) and potassium channels (Kv) although with different potencies. CTX 3C was the most active toxin blocking the peak inward sodium currents, followed by P-CTX 1B and 51-OH CTX 3C. In contrast, P-CTX 1B was more effective in blocking potassium currents. The analysis of six different samples of contaminated fish, in which a ciguatoxin analogue of mass 1040.6, not identical with the standard 51-OH CTX 3C, was the most prevalent compound, indicated an additive effect of the different ciguatoxins present in the samples. The results presented here constitute the first comparison of the potencies of three different purified ciguatoxins on sodium and potassium channels in the same neuronal preparation and indicate that electrophysiological recordings from cultured cerebellar neurons may provide a valuable tool to detect and quantify ciguatoxins in the very low nanomolar range. © 2011 American Chemical Society.
Cabrita E.,ICMAN Institute of Marine Science of Andalusia |
Soares F.,IPIMAR |
Beirao J.,University of León |
Garcia-Lopez A.,ICMAN Institute of Marine Science of Andalusia |
And 2 more authors.
Theriogenology | Year: 2011
Improving fertilization success in captive Senegalese sole broodstocks has been a challenge in the last years. Recent reports suggest that low sperm volume and quality could be one of the reasons leading to poor fertilization rates, although further studies are needed to reach a conclusive explanation. Here, we report on several experiments focused on this issue. Seasonal profiles of plasma androgen levels (testosterone and 11-ketotestosterone) and sperm production and quality parameters were assessed, although no statistical correlations among them were identified. The response of males to female presence/absence was also analyzed. Long-term isolation from females decreased male androgen levels at the peak of the reproductive period, suggesting some kind of disrupting effects on the endocrine system. On the other hand, short-term exposure of previously isolated males to ripe females decreased androgen levels, possibly reflecting a rapid steroidogenic shift promoting final maturation of spermatozoa, and increased sperm viability, motility and velocity, thus, supporting the concept of positive effects of female contact on male sole performance. Further evidence sustaining the relevant female-to-male communication in sole reproduction was obtained after treating the females with progestagen 17α,20β-dihydroxy-4-pregnen-3-one (regarded as pre-ovulatory pheromone in fish) and registering a significant increase in sperm viability, velocity and motility in surrounding males. Finally, we found that a single administration of a 20 μg/kg GnRH analogue in males was effective in stimulating androgen release and sperm quality, although the effects were transient and thus, the use of sustained hormone delivery methods were suggested for improving efficiency. Our results point to velocity, viability, and motility as the most sensitive parameters in sole sperm, although further studies will have to evaluate whether these parameters have any relation with fertilization success in captive broodstocks of this important aquaculture species. © 2011 Elsevier Inc.
Pacchiarini T.,CSIC - Institute of Marine Sciences |
Cross I.,University of Cádiz |
Leite R.B.,University of Algarve |
Gavaia P.,University of Algarve |
And 5 more authors.
Reproduction, Fertility and Development | Year: 2013
The Vasa protein is an RNA helicase belonging the DEAD (Asp-Glu-Ala-Asp)- box family. The crucial role played by the vasa gene in the germ-cell lineage of both vertebrates and invertebrates has made this gene a useful molecular marker for germinal cells and a useful tool in surrogate broodstock production using primordial germ cell transplantation. With the aim of establishing a novel approach to improving Solea senegalensis broodstock management, the vasa gene in this species was characterised. Four S. senegalensis vasa transcripts were isolated: Ssvasa1, Ssvasa2, Ssvasa3 and Ssvasa4. Their phylogenetic relationship with other vasa homologues was determined confirming the high degree of conservation of this helicase throughout evolution. Our qPCR results showed that S. senegalensis vasa transcripts are prevalently expressed in gonads, with ovary-specific expression for Ssvasa3 and Ssvasa4. During embryonic and larval development, a switch between the longest and the shortest transcripts was observed. While Ssvasa1 and Ssvasa2 were maternally supplied, Ssvasa3 and Ssvasa4 depended on the de novo expression program of the growing juveniles, suggesting that vasa mRNA could be involved in Senegalese sole gonad differentiation. In situ hybridisation and immunohistochemical analysis performed in 150-days after hatching (DAH) larvae showed vasa product expression in the germinal region of early gonads. In our work we demonstrated the usefulness of Ssvasa mRNAs as molecular markers for primordial germ cells and germinal cells during embryonic development, larval ontogenesis and gonad differentiation. Furthermore, our results confirmed the potential of vasa to help investigate germinal cell biotechnology for Senegalese sole reproduction. © 2013 CSIRO.
Bundy A.,Bedford Institute of Oceanography |
Shannon L.J.,University of Cape Town |
Rochet M.-J.,French Research Institute for Exploitation of the Sea |
Neira S.,Center for Ecosystem Research in Patagonia |
And 4 more authors.
ICES Journal of Marine Science | Year: 2010
Marine ecosystems have been exploited for a long time, growing increasingly vulnerable to collapse and irreversible change. How do we know when an ecosystem may be in danger? A measure of the status of individual stocks is only a partial gauge of its status, and does not include changes at the broader ecosystem level, to non-commercial species or to its structure or functioning. Six ecosystem indicators measuring trends over time were collated for 19 ecosystems, corresponding to four ecological attributes: resource potential, ecosystem structure and functioning, conservation of functional biodiversity, and ecosystem stability and resistance to perturbations. We explored the use of a decision-tree approach, a definition of initial ecosystem state (impacted or non-impacted), and the trends in the ecosystem indicators to classify the ecosystems into improving, stationary, and deteriorating. Ecosystem experts classified all ecosystems as impacted at the time of their initial state. Of these, 15 were diagnosed as "ugly", because they had deteriorated from an already impacted state. Several also exhibited specific combinations of trends indicating "fishing down the foodweb", reduction in size structure, reduction in diversity and stability, and changed productivity. The classification provides an initial evaluation for scientists, resource managers, stakeholders, and the general public of the concerning status of ecosystems globally. © 2010 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.
Fernandez C.,Spanish Institute of Oceanography |
Cervino S.,Spanish Institute of Oceanography |
Perez N.,Spanish Institute of Oceanography |
ICES Journal of Marine Science | Year: 2010
A Bayesian age-structured stock assessment model is developed to take into account available information on discards and to handle gaps in the time-series of discard estimates. The model incorporates mortality attributable to discarding, and appropriate assumptions about how this mortality may change over time are made. The result is a stock assessment that accounts for information on discards while, at the same time, producing a complete time-series of discard estimates. The method is applied to the hake stock in ICES Divisions VIIIc and IXa, for which the available data indicate that some 60 of the individuals caught are discarded. The stock is fished by Spain and Portugal, and for each country, there are discard estimates for recent years only. Moreover, the years for which Portuguese estimates are available are only a subset of those with Spanish estimates. Two runs of the model are performed; one assuming zero discards and another incorporating discards. When discards are incorporated, estimated recruitment and fishing mortality for young (discarded) ages increase, resulting in lower values of the biological reference points Fmax and F0.1 and, generally, more optimistic future stock trajectories under F-reduction scenarios. © 2010 United States Government, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center.
Lorance P.,French Research Institute for Exploitation of the Sea |
Agnarsson S.,University of Iceland |
Damalas D.,Hellenic Center for Marine Research |
Des Clers S.,University College London |
And 3 more authors.
ICES Journal of Marine Science | Year: 2011
Stakeholder knowledge was collected through questionnaires and cognitive maps and used to summarize biological, environmental, technical, management, and socio-economic factors for several deep-water fisheries, identifying regional management issues and solutions. The questionnaires and cognitive maps revealed different technical, environmental, and management concerns in these fisheries. Dissatisfaction with management was more at an implementation than a conceptual level, because the existing management measures were mostly considered fit for purpose. Further, catch-and-effort data provided by the fishing industry were used to calculate standardized landings per unit effort. The results suggested different trends over time for three deep-water stocks exploited by the same fleet. The examples demonstrate how stakeholder involvement and use of qualitative knowledge and quantitative data might improve the management process and stock assessments when data are limited. © 2011 International Council for the Exploration of the Sea.
Oliveira C.,University of Murcia |
Duncan N.J.,IRTA - Institute of Agricultural-Alimentary Research and Technology |
Pousao-Ferreira P.,IPIMAR |
Mananos E.,Institute of Aquaculture of Torre La Sal IATS CSIC |
Sanchez-Vazquez F.J.,University of Murcia
Aquaculture | Year: 2010
The effect of the moon light cycle on plasma melatonin rhythms was examined in Senegal sole (Solea senegalensis) exposed to natural outdoor or artificial indoor lighting conditions. Furthermore, in a second experiment, the effect of the lunar cycle on vitellogenin and sex steroids (Testosterone, T; Estradiol, E2; 11-ketotestosterone, 11kt) was studied using mature individuals during reproductive season. In the first experiment, during full moon, plasma melatonin peaked at night in covered tanks (deprived of night illumination) from both outdoor (133.2±12.8pgml-1) and indoor (190.6±41.5pgml-1) groups. However, for fish in the open tanks, exposed to approximately 0.3lx of illumination, nocturnal plasma melatonin was significantly reduced (p<0.05), approaching to mid-light (ML) values, (79.6±7.1 and 81.8±14.0pgml-1, for outdoor and indoor groups, respectively). During new moon a similar pattern was observed in outdoor group: fish in the covered tank showed higher melatonin values than those in the open tank, which were exposed to the near undetectable night illumination. In the second experiment, plasma sex steroid concentrations were significantly higher during the full moon compared to the new moon. In the case of females, E2 concentration reduced from 2.4±0.6 to 0.4±0.1ngml-1 between full and new moon samplings, while T decreased from 0.3±0.0 to 0.2±0.0ngml-1. Vitellogenin, however, did not show such differences between moon phases. In males, 11kt exhibited a plasma concentration of 14.3±2.1ngml-1 during full moon and 4.7±0.7ngml-1 during new moon while T values were 2.6±0.4 and 1.0±0.1ngml-1 for full and new moon, respectively. In conclusion, these findings pointed out the high sensitivity to moon light of the Senegal sole, which could be using the melatonin signalling to synchronize their reproduction rhythms to the lunar cycle. © 2010 Elsevier B.V.