1,721,083 research outputs found
Introduction to MARISTEM - stem cells of marine/aquatic invertebrates: from basic research to innovative applications
Full text linkMarine/aquatic invertebrates constitute the largest biodiversity and the widest phylogenetic radiation on Earth, from morphologically simple organisms (e.g., sponges, cnidarians), to the more complex mollusks, crustaceans, echinoderms, and protochordates. Today, adult marine/aquatic invertebrate stem cell (MISC) biology is of prime research and medical interest. However, studies on stem cells from organisms outside the classical vertebrate (e.g., human, mouse, and zebrafish) and invertebrate (e.g., Drosophila, Caenorhabditis) models have not been pursued vigorously. These organisms contain a variety of MISC-types that allow the production of a large number of novel bioactive-molecules, many of which are of significant potential interest for human health. MISCs further participate in aging and regeneration phenomena, including whole-body regeneration. For years, the European MISC-community has been highly fragmented and has established scarce ties with biomedical industries in an attempt to harness MISCs for human welfare. Thus, it is important to (i) consolidate the European community of researchers working on MISCs; (ii) promote and coordinate European research on MISC biology; (iii) stimulate young researchers to embark on research in MISC-biology; (iv) develop, validate, and share novel MISC tools and methodologies; (v) establish the MISC discipline as a forefront interest of biomedical disciplines, including nanobiomedicine; and (vi) establish collaborations with industries to exploit MISCs as sources of bioactive molecules. In order to fill the recognized gaps, the EC-COST Action 16203 “MARISTEM” has recently been launched. At its initial stage, the consortium unites scientists from 24 EC countries, Cooperating countries, and Near Neighbor Countries
The complement system of Botryllus schlosseri
Full text linkAmong the various effector mechanisms involved in immune responses, the complement system is one of the most ancient, deeply-rooted and important for its ability to orchestrate different cells and factors of both innate and adaptive immunity. The comprehension of its roots in the evolution is useful to understand how the main complement-related proteins had changed in order to adapt to new environmental conditions and life-cycles or, in the case of vertebrates, to interact with the adaptive immunity. In this context, data from organisms evolutionary close to vertebrates, such as tunicates, are of primary importance for a better understanding of the changes in immune responses associated with the invertebratevertebrate transition. In our model tunicate Botryllus schlosseri we have described a lectin and alternative pathway of complement system activation very similar to those of Vertebrates. All the complement-related genes such as c3, bf, ficolin, mbl and masp are transcribed by morula cells, the immunocytes in immunomodulation and cytotoxic responses. Functional data suggest a complement-related cross-talk between morula cells and phagocytes immunocyte during the immune response. When B. schlosseri hemocytes are incubated with yeast (Saccharomyces cerevisiae) cells, there is an overexpression of C3 by morula cell that led to increase of phagocytosis that is prevented in the presence of the C3 inhibitor, compstatin. In the next future, we will focus our efforts on the regulation of complement system in tunicates to shed new light on the complement system function in a pre-adaptive immunity scenario
Preliminary data on a Toll-like receptor from the colonial ascidian Botryllus schlosseri.
No full textToll-like receptors (TLRs) represent a well-known family of conserved pattern recognition receptors the importance of which, in non-self recognition, was demonstrated in both vertebrates and invertebrates. Tunicates represent the vertebrate sister group and, as invertebrates, they rely only on innate immunity for their defense. As regards TLRs, two transcripts have been described and characterized in the solitary species Ciona intestinalis, referred to as CiTLR1 and CiTLR2. Using the Ciona TLR nucleotide sequences, we examined the genome and the available transcriptomes of Botryllus schlosseri looking for similar sequences. We were able to identify a sequence, with similarity to CiTLR2 and, through in silico transduction and subsequent sequence analysis, we studied the domain content of the putative protein. The sequence, called BsTLR, has a TIR and a transmembrane domain, four LLR and two LRR-CT domains. In addition, we analized Bstlr expression in vivo and in vitro, under various experimental conditions and in different phases of the Botryllus blastogenetic cycle. Our data show that, in different phases, there is a change in gene expression and mRNA location, according to the blastogenetic phase
The C1q domain-containing protein from the ascidian Botryllus schlosseri manifests a cytokine-like behavior.
No full textGenes encoding complement component 3 (C3) have been extensively investigated in invertebrate genomes and traced back in evolutionary history to the early metazoan radiation. However, other components of the complement system, such as those related to the classical activation pathway, are still not much investigated. Currently, the genes encoding for proteins with a C1q domain, probably the main components of the classical pathway, have been only partially investigated from an evolutionary perspective. These genes exist in many of the sequenced genomes, from both vertebrates and invertebrates and functions have been described for some of the corresponding proteins. A C1q-like gene have been identified in the medicinal leech Hirudo medicinalis where a C1q-like peptide elicits a chemotactic behavior that could be blocked using a human antibody against the gC1q receptor. C1q-like genes have also been found in the urochordate Ciona intestinalis and the cephalocordate Branchiostoma floridae where it has been demonstrated that the globular domain is able to recognize and bind mammalian antibodies initiating the classical pathway of complement activation. The globular head C1q domain is a lectin domain present in transcriptomes of amphioxus, lamprey, and several teleost fishes. Few of these putative C1q-like proteins have been characterized; however, they can bind to a variety of carbohydrates. In Botryllus schlosseri we have found, in our EST collection, a single transcript with C1q characteristics (BsC1q-like). The deduced protein contains two globular head C1q domains, a feature unknown in invertebrates. As regard Vertebrates, we can find a similar architecture only in mammals, in the so called C1q/TNF-related Protein 4 (CTRP4). This protein is very poorly studied and seems to be expressed in the hypothalamus and contribute to the modulation of food intake and body weight. Our data, from the colonial ascidian, suggest a role for the BsC1q-like protein as mediator of the activation and degranulation of the cytotoxic hemocytes. Both ISH and ICC demonstrate that both cytotoxic morula cells and phagocytes express the BsC1q-like mRNA and protein; functional analyses demonstrate that the human antibody against globular head C1q is able to inhibit morula cell degranulation after bacterial challenge. It is not yet clear if it is possible to considered this molecule as member of the complement system in Botryllus but future analyses will be directed to the study of the functional relationships between BsC3 and BsC1q-like as well as of the binding capabilities of the latter
The days after: cellular events following the inflammatory allorejection reaction in the colonial ascidian Botryllus schlosseri
No full textAllorecognition between contacting, genetically incompatible colonies of the ascidian Botryllus schlosseri represents a typical inflammatory reaction. It leads to the formation of a series of cytotoxic, necrotic spots along the contact border known as points of rejection (PORs). This is the consequence of the selective recruitment of morula cells (MCs), a peculiar granular, cytotoxic cells present in botryllid ascidians, in the lumen of the ampullae (the peripheral blind termini of the colonial vasculature) facing the alien colony, their migration into the tunic and their degranulation. The released material includes the enzyme phenoloxidase, the activity of which is responsible for the observed cytotoxicity. In the present work, we studied the cellular events in the facing ampullae for 9 days following the initial contact of the colonies. Data confirm that MCs gather inside the lumen of facing ampullae already at day 1 from the contact and start to leak into the tunic at day 2, when the first PORs appear. MCs then decrease progressively in the following days, probably because most of them leave the circulation and enter the tunic whereas, at day 5 from the contact, round phagocytes increase significantly inside facing ampullae, likely deriving from spreading phagocytes having ingested MC corpses in order to prevent a diffuse inflammation in the circulatory network. After the allorejection reaction, colonies orient their growth towards opposite directions and ampullae previously involved in the allorecognition remain in a region of old tunic which is progressively released by the colonies
Preliminary data in immune priming in the Mediterranean mussel Mytilus galloprovincialis
No full textMolluscs, like all the other invertebrate, rely only on innate immunity for their defence. The latter has been traditionally associated with low specificity and lack of immune memory. However, in the last decade, the presence of short-term immune memory, referred to as “immune priming”, was revealed in representatives of various invertebrate phyla. In the present work, we studied the response of the mussel Mytilus galloprovincialis to single or double exposure (second one after 7 days from the first) to the gram-positive bacterium Bacillus clausii. One day after the 1st or 2nd exposure, the digestive gland and the gills were collected from exposed and unexposed animals (controls) frozen in liquid nitrogen and stored at -20°C. Haemolymph was also collected from the adductor muscle and haemocytes were obtained by centrifugation and resuspended in filtered seawater (FSW). The following parameters were measured: superoxide dismutase (SOD) and catalase (CAT) activities on tissues; total haemocyte count (THC), haemocyte volume (HV), haemocyte diameter (HD) and the percentage of phagocytosing cells on haemocytes. No variations in SOD and CAT activities were observed in exposed animals with respect to their control after a single exposure, whereas a significant decrease in CAT activity was observed after the 2nd exposure. No significant differences in the THC and phagocytosing activity were observed whereas significant increases in HV and HD were observed after the exposures without any significant variations between the two exposures. Collectively, these data represent a first attempt to study immune priming in M. galloprovincialis. Further studies are required using a more appropriate stimulus (B. clausii is not a natural pathogen for M. galloprovincialis) and changing the interval between the 1st and the 2nd exposure
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