New Insights into the Apoptotic Process in Mollusks: Characterization of Caspase Genes in Mytilus galloprovincialis

Apoptosis is an essential biological process in the development and maintenance of immune system homeostasis. Caspase proteins constitute the core of the apoptotic machinery and can be categorized as either initiators or effectors of apoptosis. Although the genes encoding caspase proteins have been described in vertebrates and in almost all invertebrate phyla, there are few reports describing the initiator and executioner caspases or the modulation of their expression by different stimuli in different apoptotic pathways in bivalves. In the present work, we characterized two initiator and four executioner caspases in the mussel Mytilus galloprovincialis. Both initiators and executioners showed structural features that make them different from other caspase proteins already described. Evaluation of the genes’ tissue expression patterns revealed extremely high expression levels within the gland and gills, where the apoptotic process is highly active due to the clearance of damaged cells. Hemocytes also showed high expression values, probably due to of the role of apoptosis in the defense against pathogens. To understand the mechanisms of caspase gene regulation, hemocytes were treated with UV-light, environmental pollutants and pathogen-associated molecular patterns (PAMPs) and apoptosis was evaluated by microscopy, flow cytometry and qPCR techniques. Our results suggest that the apoptotic process could be tightly regulated in bivalve mollusks by overexpression/suppression of caspase genes; additionally, there is evidence of caspase-specific responses to pathogens and pollutants. The apoptotic process in mollusks has a similar complexity to that of vertebrates, but presents unique features that may be related to recurrent exposure to environmental changes, pollutants and pathogens imposed by their sedentary nature

Comparison of polychlorinated biphenyl (PCB) induced effects on innate immune functions in harbour and grey seals

Polychlorinated biphenyls (PCBs) are known to have detrimental effects on the innate immune system of several mammalian species. Top predators such as marine mammals may be badly affected as PCBs can bioaccumulate in their blubber to high concentrations and previous studies have suggested that harbour seals may be particularly vulnerable to the immunotoxic effects of such contaminants. To investigate the effects of PCBs on innate immune functions in phocid seals, blood samples were collected from harbour and grey seals and exposed in vitro to a mixture of Aroclors. Separated mononuclear (PBMCs) and polymorphonuclear (PMNCs) leukocytes from each species were incubated with Aroclors (at 3 and 30 ng ml(-1)) for 3 and 24 h incubation periods, after which phagocytosis, respiratory burst and cytotoxic activity were measured. The phagocytic activity of harbour seal PMNCs was decreased at both incubation times and at both Aroclor concentrations tested, but there was no effect on the grey seals. Similarly, the respiratory burst activity of harbour seals was decreased at both incubation times, but only at the higher concentration used. There were no differences in the cytotoxic activity of the PBMCs with respect to incubation times or concentrations in either species. However, differences were observed in the level of cytotoxic activity against YAC-1 target cells, with the grey seal PBMCs showing higher levels of activity. The observed differences in phagocytosis, respiratory burst and cytotoxic activity of the leukocytes following incubation with PCBs may have implications for the previously recorded differences in disease susceptibility between grey and harbour seals. (C) 2005 Elsevier B.V. All rights reserved.</p

Tricellaria porteri

&lt;i&gt;Tricellaria porteri&lt;/i&gt; (MacGillivray, 1889) &lt;p&gt; &lt;i&gt;Tricellaria porteri&lt;/i&gt;, which is, to date, only known from southern Australia, was highlighted by Occhipinti Ambrogi and d&rsquo; Hondt (1994) as a possible senior synonym of &lt;i&gt;T. inopinata&lt;/i&gt;. The original description of &lt;i&gt;Menipea porteri&lt;/i&gt; by MacGillivray (1889) refers to the presence of reniform (kidney-shaped) scuta, variable internode lengths and bi&reg;d spines. It also refers to the ovicell pores as forming a single transverse row. We have examined paratype specimens of &lt;i&gt;T. porteri&lt;/i&gt;, all from South Australia (including slides 65508, 65509, Rev. Porter collection; 65511, 65513, Museum of Victoria, Melbourne) and have come to the conclusion that this taxon is morphologically diOEerentiable from the other two taxa. The most striking characteristic is the consistently large and highly reniform scuta, quite unlike those encountered in the other two taxa (&reg;gure 2). Only a small minority of scuta bear irregular margins. We observed 3&plusmn;13 autozooids per internode and proximal external bi&reg;d spines on many autozooids. Lateral avicularia were sparsely present. We found the arrangement of ovicell pores to be very variable, usually scattered but occasionally forming a row in the manner described by MacGillivray (1889).&lt;/p&gt; &lt;p&gt; Two recent published descriptions from South Australia attributed to &lt;i&gt;T. porteri&lt;/i&gt; present di culties. Bock (1982) made reference to variable internodes and`ovate&rsquo; scuta (but &reg;gured more irregularly-shaped ones) and made no mention of bi&reg;d spines. This material needs re-appraising. Brock (1985) &reg;gured a variety of scuta morphologies and some bi&reg;d spines. The former is only consistent with our characterization of &lt;i&gt;T. inopinata.&lt;/i&gt; A more recent study makes reference to the presence of &lt;i&gt;T. porteri&lt;/i&gt; as a fouling species in Port Kembla, New South Wales (Moran and Grant, 1993) although the information provided is insu cient to con&reg;rm its identity according to the criteria de&reg;ned here.&lt;/p&gt;Published as part of &lt;i&gt;Dyrynda, P. E. J., Fairall, V. R., Ambrogi, A. Occhipinti &amp; d'Hondt, J. - L., 2000, The distribution, origins and taxonomy of Tricellaria inopinata d'Hondt and Occhipinti Ambrogi, 1985, an invasive bryozoan new to the Atlantic, pp. 1993-2006 in Journal of Natural History 34 (10)&lt;/i&gt; on page 2001, DOI: 10.1080/00222930050144828, &lt;a href="http://zenodo.org/record/10083127"&gt;http://zenodo.org/record/10083127&lt;/a&gt

The Internal-Brooding Apparatus in the Bryozoan Genus Cauloramphus (Cheilostomata: Calloporidae) and Its Inferred Homology to Ovicells

We studied by SEM the external morphology of the ooecium in eight bryozoans of the genus Cauloramphus Norman, 1903 (Cheilostomata, Calloporidae): C. spinifer, C. variegatus, C. magnus, C. multiavicularia, C. tortilis, C. cryptoarmatus, C. niger, and C. multispinosus, and by sectioning and light microscopy the anatomy of the brooding apparatus of C. spinifer, C. cryptoarmatus, and C. niger. These species all have a brood sac, formed by invagination of the non-calcified distal body wall of the maternal zooid, located in the distal half of the maternal (egg-producing) autozooid, and a vestigial, maternally budded kenozooidal ooecium. The brood sac comprises a main chamber and a long passage (neck) opening externally independently of the introvert. The non-calcified portion of the maternal distal wall between the neck and tip of the zooidal operculum is involved in closing and opening the brood sac, and contains both musculature and a reduced sclerite that suggest homology with the ooecial vesicle of a hyperstomial ovicell. We interpret the brooding apparatus in Cauloramphus as a highly modified form of cheilostome hyperstomial ovicell, as both types share 1) a brood chamber bounded by 2) the ooecium and 3) a component of the distal wall of the maternal zooid. We discuss Cauloramphus as a hypothetical penultimate stage in ovicell reduction in calloporid bryozoans. We suggest that the internal-brooding genus Gontarella, of uncertain taxonomic affinities, is actually a calloporid and represents the ultimate stage in which no trace of the ooecium remains. Internal brooding apparently evolved several times independently within the Calloporidae

The ‘Coral Bulker’ Fuel Oil Spill on the North Coast of Portugal: Spatial and Temporal Biomarker Responses in Mytilus galloprovincialis

In December 2000, the ship ‘Coral Bulker’ ran aground at the entrance of the port of Viana do Castelo (North–west coast of Portugal). A large amount of fuel oil was spilled and part of it reached the shore. To evaluate the spatial and temporal impact of this oil spill, a field study, and several laboratory toxicity tests were performed using Mytilus galloprovincialis as biological indicator of environmental contamination and the biomarkers glutathione S-transferases (GSTs) and acetylcholinesterase (AChE) as indicative criteria. Fifteen days after the oil spill, mussels collected at stations located near the ship presented higher and lower values of GSTs and AChE activity, respectively. These results, and those obtained in the laboratory toxicity tests, evidence that these biomarkers were sensitive indicators of exposure to this kind of pollution and were able to monitor a spatial impact of the oil spill of at least 10 km, confirming the higher level of contamination near the ship and a contamination gradient along the sampling stations. One year after the accident, such a contamination gradient was no longer evident. This study highlight the potential suitability of a biomarker approach for assessing spatial and temporal impacts of marine pollution accidents, such as fuel oil spills, suggesting the inclusion of these biomarkers in risk assessment studies, as cost-effective and early warning recognized tools. Major advantages and limitations of the biomarker approach used in this study are further discussed