Daniela Candia

University of Milan | UNIMI · Department of Biomedical Science

The mutable collagenous tissue (MCT) of echinoderms has the capacity to undergo changes in its tensile properties within a timescale of seconds under the control of the nervous system. All echinoderm autotomy (defensive self-detachment) mechanisms depend on the extreme destabilisation of mutable collagenous structures at the plane of separation. Th...

The endoskeleton of echinoderms (Deuterostomia: Echinodermata) is of mesodermal origin and consists of cells, organic components, as well as an inorganic mineral matrix. The echinoderm skeleton forms a complex lattice-system, which represents a model structure for naturally inspired engineering in terms of construction, mechanical behaviour, and fu...

Extracellular matrix (ECM) plays a dynamic role during tissue development and re-growth. Body part regeneration efficiency relies also on effective ECM remodelling and deposition. Among invertebrates, echinoderms are well known for their striking regenerative abilities since they can rapidly regenerate functioning complex structures. To gather insi...

Collagen-based skin-like scaffolds (CBSS) are promising alternatives to skin grafts to repair wounds and injuries. In this work, we propose that the common marine invertebrate sea urchin represents a promising and eco-friendly source of native collagen to develop innovative CBSS for skin injury treatment. Sea urchin food waste after gonad removal w...

The information concerning the toxicity of sinking microplastics (MPs) on benthic marine animals, particularly benthic grazers, is still scant. No study focused on biological weathering of sinked MPs operated by benthic organisms. This study aims at investigating the ingestion and the effects induced by 7-days dietary exposure to environmentally re...

Reparative regeneration is defined as the replacement of lost adult body parts and is a phenomenon widespread yet highly variable among animals. This raises the question of which key cellular and molecular mechanisms have to be implemented in order to efficiently and correctly replace entire body parts in any animal. To address this question, diffe...

Regeneration is a post-embryonic developmental process that ensures complete morphological and functional restoration of lost body parts. The repair phase is a key step for the effectiveness of the subsequent regenerative process: in vertebrates, efficient re-epithelialisation, rapid inflammatory/immune response and post-injury tissue remodelling a...

The use of marine collagens is a hot topic in the field of tissue engineering. Echinoderms possess unique connective tissues (Mutable Collagenous Tissues, MCTs) which can represent an innovative source of collagen to develop collagen barrier-membranes for Guided Tissue Regeneration (GTR). In the present work we used MCTs from different echinoderm m...

The red starfish Echinaster sepositus is an excellent model for studying arm regeneration processes following traumatic amputation. The initial repair phase was described in a previous paper in terms of the early cicatrisation phenomena, and tissue and cell involvement. In this work we attempt to provide a further comprehensive description of the l...

Starfish can regenerate entire arms following their loss by both autotomic and traumatic amputation. Although the overall regenerative process has been studied several times in different asteroid species, there is still a considerable gap of knowledge as far as the detailed aspects of the repair phase at tissue and cellular level are concerned, par...

The compass depressors (CDs) of the sea-urchin lantern are ligaments consisting mainly of discontinuous collagen fibrils associated with a small population of myocytes. They are mutable collagenous structures, which can change their mechanical properties rapidly and reversibly under nervous control. The aims of this investigation were to characteri...

The viscoelastic properties of vertebrate connective tissues rarely undergo significant changes within physiological timescales, the only major exception being the reversible destiffening of the mammalian uterine cervix at the end of pregnancy. In contrast to this, the connective tissues of echinoderms (sea urchins, starfish, sea cucumbers, etc.) c...

Collagen has become a key-molecule in cell culture studies and in the tissue engineering field. Industrially, the principal sources of collagen are calf skin and bones which, however, could be associated to risks of serious disease transmission. In fact, collagen derived from alternative and riskless sources is required, and marine organisms are am...

Echinoderms possess unique connective tissues (Mutable Collagenous Tissues, MCT) which can dynamically modulate their mechanical state, reversibly switching between stiff and compliant conditions. From a structural point of view MCTs are composed of the same main components as all mammalian connective tissues: cells, collagen and other extracellula...

Among echinoderms, crinoids are well known for their remarkable regenerative potential. Regeneration depends mainly on progenitor cells (undifferentiated or differentiated), which migrate and proliferate in the lesion site. The crucial role of the "progenitor" elements involved in the regenerative processes, in terms of cell recruitment, sources, a...

Echinoderms and sponges share a unique feature that helps them face predators and other environmental pressures. They both possess collagenous tissues with adaptable viscoelastic properties. In terms of morphology these structures are typical connective tissues containing collagen fibrils, fibroblast- and fibroclast-like cells, as well as unusual c...

The mesohyl of the demosponge Chondrosia reniformis Nardo 1847 mainly consists of collagen, which is responsible of typical cartilaginous consistency of this sponge. It has been reported (Bonasoro et al., 2001; Wilkie et al., 2006) that following specific stimuli this species is able to change the mesohyl mechanical properties by modifying the inte...

Although sponges are still often considered to be simple, inactive animals, both larvae and adults of different species show clear coordination phenomena triggered by both extrinsic and intrinsic stimuli. Chondrosia reniformis (Nardo, 1847), a common Mediterranean demosponge, lacks both endogenous siliceous spicules and reinforcing spongin fibers a...

In the present work, primary cell cultures from ovaries of the edible sea urchin Paracentrotus lividus were developed in order to provide a simple and versatile experimental tool for researches in echinoderm reproductive biology. Ovary cell phenotypes were identified and characterized by different microscopic techniques. Although cell cultures coul...

Despite the extensive use of sea urchins in embryology, the hormonal mechanisms regulating echinoid reproductive pro­cesses are scarcely known. This research is focused on the role of estradiol (E2), whose presence and seasonal variations in different echinoderm tissues have been previously reported. Three different concentrations of E2 were admini...

Mutable collagenous tissues (MCTs) of echinoderms can be regarded as intelligent and dynamic biomaterials, due to their ability to reversibly change their mechanical properties in a short physiological time span. This mutability phenomenon is nervously mediated and involves secreted factors of the specialized 'juxtaligamental' cells, which, when re...

Mutable collagenous tissues (MCTs) of echinoderms show reversible changes in tensile properties (mutability) that are initiated and modulated by the nervous system via the activities of cells known as juxtaligamental cells. The molecular mechanism underpinning this mechanical adaptability has still to be elucidated. Adaptable connective tissues are...

Although l-glutamate is the most widespread excitatory neurotransmitter in vertebrate and invertebrate nervous systems, there is only sparse evidence that it has this role in echinoderms. Following our previous finding that l-glutamate is widely distributed in the arms of the featherstar (crinoid echinoderm) Antedon mediterranea and initiates arm a...

Chondrosia reniformis is a common marine demosponge that shows striking tissue plasticity and unusual body deformability. This sponge can develop long and slender outgrowths extending from the parental body. According to some authors, this phenomenon, called “creeping”, can be related to asexual reproduction, atypical mechanisms of «localized» loco...

Although several authors have suggested a plausible involvement of steroids in the reproductive biology of echinoderms, their definitive role is still poorly understood. In this paper we focused on oestradiol (E2), whose presence and variations were previously revealed in different echinoderm tissues. The aim of this investigation was to provide fu...

In the recent decades, the importance of echinoderm endocrinology has increased because of the use of echinoderms as models for aquatic ecotoxicology and due to their evolutionary closeness to chordates. Nonetheless, apart from asteroids and echinoids, there is limited information available on the reproductive physiology of echinoderm groups, parti...

Echinoderms have been used often as experimental models in developmental biology and evolutionary biology studies. Numerous data on echinoid and asteroid development are available, whereas little is known about crinoid larval biology. This contribution focussed on the life cycle of the Mediterranean feather star Antedon mediterranea. Light and elec...

This paper provides insights into the achievements and challenges of implementing education on dual-use in four countries: Austria, Italy, Pakistan and Sweden. It draws attention to the different institutional mechanisms through which dual-use education may be introduced into academic curricula and some of the difficulties encountered in this proce...

The mutable collagenous tissue (MCT) of echinoderms has the ability to undergo rapid and reversible changes in passive mechanical properties that are initiated and modulated by the nervous system. Since the mechanism of MCT mutability is poorly understood, the aim of this work was to provide a detailed morphological analysis of a typical mutable co...

Echinoderms possess unique connective tissues, called mutable collagenous tissues (MCTs), which undergo nervously mediated, drastic and reversible or irreversible changes in their mechanical properties. Connective tissue mutability influences all aspects of echinoderm biology and is a key-factor in the ecological success of the phylum. Due to their...

The organization of the cnidarian nervous system has been widely documented in polyps and medusae, but little is known about the nervous system of planula larvae, which give rise to adult forms after settling and metamorphosis. We describe histological and cytological features of the nervous system in planulae of the hydrozoan Clava multicornis. Th...

Echinoderms possess a dynamic connective tissue, which can undergo drastic nervously-mediated changes in its mechanical properties. In the up to date biomimetic approach, this tissue seems to provide a suitable model for biomaterial design. This contribution shows the last results of an integrated analysis of Mutable Collagenous Tissues (MCTs) of t...

The mechanically adaptable connective tissue of echinoderms (Mutable Collagenous Tissue -MCT), which can undergo drastic nervously-mediated changes in its stiffness, tensile strength and viscosity, represents a promising model for biomaterial design and biomedical applications. MCT could be a source of, or an inspiration for, new composite material...

Gli echinodermi posseggono un peculiare tipo di tessuto connettivo mutabile (MCT), in grado di andare incontro a rapidi cambiamenti delle proprietà meccaniche intrinseche, mediati dal sistema nervoso, fenomeno noto come mutabilità. Gli MCTs possono quindi rappresentare una preziosa fonte di ispirazione per biomateriali dinamici biomateriali dinamic...

The regenerative potential is expressed to a maximum extent in echinoderms and ascidians. They provide unique and valuable deuterostome models, closely related to vertebrates (man included), for an integrated approach exploring regeneration from tissue repair to asexual cloning. The comparison of results derived from different experimental models o...

The crinoid echinoderm Antedon mediterranea autotomises its arms at specialised skeletal joints known as syzygies that occur at regular intervals along the length of each arm. Detachment is achieved through the nervously mediated destabilisation of ligament fibres at a particular syzygy. The aim of this investigation was to identify neurotransmitte...

As well as acting as a neurotransmitter, serotonin is also involved in morphogenetic signalling during crucial phases of many developmental and regenerative processes such as cleavage, migration and differentiation. Echinoderms display nerve-dependent regenerative phenomena and serotonin is one of the main neural regulatory factors that have been i...

Regular sea–urchins, as a rule, prepare and process their food as pellets in their buccal cavity before ingesting them. This is obtained through the synergistic interaction of the five teeth with five fleshy protuberances (paradental tongues) which extend into the oral cavity and work like tongues. Each of these structures consists of two anatomica...

Two echinoderm species, the sea urchin Paracentrotus lividus and the feather star Antedon mediterranea, were exposed for 28 days to several EDCs: three putative androgenic compounds, triphenyltin (TPT), fenarimol (FEN), methyltestosterone (MET), and two putative antiandrogenic compounds, p,p'-DDE (DDE) and cyproterone acetate (CPA). The exposure no...

The potential for regenerating tissues, organs and body parts, even the ability to reconstruct virtually a complete animal from a body fragment, is expressed to a maximum extent in echinoderms which provide fantastic and tractable models for the study of regeneration. Regenerative processes are common in all classes of the phylum, even though speci...

The peristomial membrane (PM) is the area of flexible body wall which surrounds the mouth of regular sea-urchins. In cidaroid sea-urchins, like Stylocidaris. affnis (Phil.), it contains an extensive endoskeleton of overlapping plates. This paper describes the basic mechanical properties of the PM of S. affinis and compares them with those of the PM...

Gonads of the mediterranean crinoid Antedon mediterranea were analyzed in order to reconstruct their histological organization. The tissue arrangement resembled that previously described in other crinoids. Five reproductive stages were identified in both males and females: recovery, growing, premature, mature, spent. Sexually dimorphic characters w...

In the present analysis experimental results and computer modelling have been used to compare biomechanics of the two most contrasting lantern types among regular echinoids, i.e. the cidarid-type (Stylocidaris affinis) and the camarodont (Paracentrotus lividus) lantern. The lantern is modelled as a rigid pyramid anchored in the centre of the perist...

The dental apparatus or Aristotle's lantern of sea-urchins is a complex system of interacting skeletal ossicles, joints, muscles and ligaments arranged in a rigorous geometry and involved in a variety of activities. In this paper we study the movement of the whole lantern system modelled as a rigid body. The model lantern is constrained at its apex...

An unsteady-state fugacity model has been developed and validated as a predictive tool that will be useful in the planning phase of aquatic ecotoxicological tests. The model predicts the compound concentration trends in water and biota in experimental aquaria, with respect to the chemical and experimental conditions. The model has been validated wi...

All species of the Ophiuroidea have exceptional regenerative capabilities; in particular, they can replace arms lost following traumatic or self-induced amputation. In order to reconstruct this complex phenomenon, we studied arm regeneration in two different ophiuroids, Ophioderma longicaudum (Retzius, 1805) and Amphiura filiformis O. F. Müller, 17...

Triphenyltin is an organotin compound that has been used extensively as an antifouling biocide and as an agricultural pesticide. Certain organotin compounds act as endocrine-active agents and have been reported to affect reproduction in mollusks and mammals. Here we studied the histopathological effects of 2 or 6mg triphenyltin chloride (TPTCl)/kg...

Echinoderms are valuable test species in marine ecotoxicology and offer a wide range of biological processes appropriate for this approach. Regenerating echinoderms can be regarded as amenable experimental models for testing the effects of exposure to contaminants, particularly endocrine disrupter compounds (EDCs). As regeneration is a typical deve...

The specific mechanism regulating reproduction in invertebrates is a field of topical interest which needs to be explored in detail considering also the intriguing possible comparison with vertebrates. In this paper levels of Testosterone (T) and Estradiol (E2) and their reciprocal ratios were determined in ovaries and testis of the echinoid model...

Echinoderms are valuable test species in marine ecotoxicology and offer a wide range of biological processes appropriate for this approach. In spite of this potential, available data in literature are still rather limited, particularly with regard to the possible effects of endocrine disrupter compounds (EDCs). This review presents echinoderms as u...

The outer membrane (OM) of gram-negative bacteria is an asymmetric lipid bilayer that protects the cell from toxic molecules. Lipopolysaccharide (LPS) is an essential component of the OM in most gram-negative bacteria, and its structure and biosynthesis are well known. Nevertheless, the mechanisms of transport and assembly of this molecule in the O...

Crinoids are able to regenerate completely many body parts, namely arms, pinnules, cirri, and also viscera, including the whole gut, lost after self-induced or traumatic mutilations. In contrast to the regenerative processes related to external appendages, those related to internal organs have been poorly investigated. In order to provide a compreh...

The marine sponge Chondrosia reniformis Nardo consists largely of a collagenous tissue, the mesohyl, which confers a cartilaginous consistency on the whole animal. This investigation was prompted by the incidental observation that, despite a paucity of potentially contractile elements in the mesohyl, intact C. reniformis stiffen noticeably when tou...

Androgen metabolism (androstenedione and testosterone) has been assessed in the digestive tube and gonads of the echinoderm Paracentrotus lividus exposed to different concentrations of the biocide triphenyltin (TPT) in a semi-static water regime for 4 weeks. Key enzymatic activities involved in both synthesis and metabolism of androgens, namely 17b...

Sexual steroids (testosterone and estradiol) were measured in the whole body of wild specimens of the crinoid Antedon mediterranea collected from the Tyrrhenian Sea (Italy). Testosterone levels (274-1,488 pg/g wet weight (w.w.)) were higher than those of estradiol (60-442 pg/g w.w.) and no significant differences between males and females were obse...

Tens of thousands of man-made chemicals are in regular use and discharged into the environment. Many of them are known to interfere with the hormonal systems in humans and wildlife. Given the complexity of endocrine systems, there are many ways in which endocrine-disrupting chemicals (EDCs) can affect the body's signaling system, and this makes unr...

Regenerative phenomena reproduce developmental processes in adult organisms and are regulated by neuro-endocrine mechanisms. They can therefore provide sensitive tests for monitoring the effects of exposure to endocrine disrupter contaminants (EDs) which can be bioaccumulated by the organisms causing dysfunctions in steroid hormone metabolism and a...

A new simple model, based on the fugacity approach, has been developed to provide a predictive tool useful in the planning phase of aquatic ecotoxicological tests for assessing the actual daily concentrations in water. In our experiments, three nominal concentrations (100, 225, and 500 ng L) of triphenyltin chloride (TPT-Cl) were employed for an ex...

The regenerative phenomena that reproduce developmental processes in adult organisms and are regulated by endocrine and neurohumoral mechanisms can provide new sensitive tests for monitoring the effects of exposure to anthropogenic chemicals such as endocrine disrupter (ED) contaminants. These pollutants in fact can be bioaccumulated by the organis...

This paper provides the first detailed account of the histological and ultrastructural organisation of an echinoderm ligament that is non-mutable. Each of the five compass ossicles on the aboral side of the lantern of regular echinoids is linked to an underlying rotular ossicle by a compass-rotular ligament (CRL). The structure and anatomical relat...

Invertebrates have frequently been used to help understand the complexities of regulatory gene function and evolution. The bone morphogenetic proteins (BMPs) are a highly conserved group of secreted regulatory factors that play an important part in early embryonic patterning. In the present study we have used the remarkable regenerative potential o...

A new mechanoreceptor organ, the "coronal organ," located in the oral siphon, is described by light and electron microscopy in the colonial ascidians Botryllus schlosseri and Botrylloides violaceus. It is composed of a line of sensory cells (hair cells), accompanied by supporting cells, that runs continuously along the margin of the velum and tenta...

The phylum Echinodermata is well known for its extensive regenerative capabilities. Although there are substantial data now available that describe the histological and cellular bases of this phenomenon, little is known about the regulatory molecules involved. Here, we use an immunochemical approach to explore the potential role played by putative...

Crinoids are well known for their striking regenerative potential and can rapidly and completely regenerate arms lost following self-induced or traumatic amputation. Thus they provide a valuable experimental model for investigation of the regenerative process from the macroscopic to the molecular level. In these last years we have studied in detail...

The common demosponge Chondrosia reniformis possesses the capacity to undergo an unusual creep process which results in the formation of long outgrowths from the parent body. These shape changes, which have been interpreted as adaptive strategies related to environmental factors, asexual reproduction or localised locomotor phenomena, are due mainly...

There has been much recent interest in the presence and biological functions of growth regulators in invertebrates. In spite of the different distribution patterns of these molecules in different phyla (from molluscs, insects, and annelids to echinoderms and tunicates), they seem always to be extensively involved in developmental processes, both em...

The study of regeneration in armed echinoderm species, including crinoids, ophiuroids and asteroids, is attracting increasing attention. Recent interest has focused on the presence and potential role of growth factors, including members of the nerve growth factor (NGF) and transforming growth factor-beta (TGF-beta) families, in the regenerative pro...

All organisms show a common defensive mechanism that results in the expression of conserved heat shock proteins (Hsps). These proteins function in a wide range of stressful conditions. We have monitored their levels in species of regenerating echinoderms with different mechanisms of regeneration and from different geographical locations. The effect...

The exterior coelomic septum (ECS) is a mesentery-like structure that encloses the lantern of regular sea-urchins and connects it to the inner surface of the test. This paper describes the ultrastructure and microarchitecture of the ECS in Stylocidaris affinis (Cidaridae, Echinoida) and provides information on its contractile and passive mechanical...

Growth of laterarl muscle in the teleost fish Sparus aurata (L.) was examined from hatching to juvenile by a basic morphofunctional approach that takes into account structural and ecophysiological aspects and combines in vivo observations and LM and TEM microscopic analysis. As shown in most teleost fishes, muscle growth proceeds by a double mechan...

Crinoid echinoderms can provide a valuable experimental model for studying all aspects of regenerative processes from molecular to macroscopic level. Recently we carried out a detailed study into the overall process of arm regeneration in the crinoid Antedon mediterranea and provided an interpretation of its basic mechanisms. However, the problem o...

During development of the olfactory pathway, calcitonin gene-related peptide (CGRP) expression is regulated both temporally and spatially. We had previous evidence that between E13 and E19 CGRP mRNA was present at the level of olfactory axons but the resolution of light-microscope in situ hybridization did not permit the axons to be distinguished f...

 Certain components of the jaw apparatus, or lantern, of regular sea-urchins form a ’compass system’ the function of which has still to be established. This system includes ten compass depressors (CDs) which connect the compass ossicles to the inner edge of the test. Previous studies focused on the CDs of euechinoid sea-urchins. This paper provides...

L-leucine uptake in stage V Xenopus laevis oocytes was affected by the specific methods used to remove the follicle cells. In the presence of 100 mM NaCl, L-leucine uptake was reduced by 67.5% +/- 5.7 when defolliculation was performed enzymatically by collagenase treatment, whereas the reduction was 30.5% +/- 6.4 after mechanical defolliculation....

The jaw apparatus, or lantern, of sea-urchins contains five pairs of retractor and protractor muscles which are responsible for lantern displacement. Using intact retractor or protractor groups, the force-length relations of these muscles were compared in two taxonomically distant species, Paracentrotus lividus and Stylocidaris affinis. The total c...

The overall process of arm regeneration in the crinoid Antedon mediterranea is a typical epimorphic process (blastemal regeneration). This can be subdivided into three main phases: a repair phase, an early regenerative phase, and an advanced regenerative phase. The crucial problem of the identification of cell lineages responsible for both repair a...

To investigate the role of dynamic changes in actin cytoskeleton in cellular response to oxidative stress, we have analyzed the state of actin polymerization and synthesis in human alveolar cells exposed to paraquat, an oxidant agent. Cellular content of monomeric actin was assayed by DNase I inhibition. It decreased significantly in treated cells...

Crinoid echinoderms can completely and rapidly regenerate arms lost following self-induced or traumatic amputation. Arm regeneration in these animals therefore provides a valuable experimental model for studying all aspects of regenerative processes, particularly with respect to the nervous system and its specific contribution to regenerative pheno...

Arm regeneration in the crinoid echinoderm Antedon mediterranea can provide a very useful model for studying regenerative development. This process can be described as an epimorphic process in which new structures develop from migratory actively proliferating cells. Both the repair and the regenerative phases are due to this fundamental mechanism,...

The functional organization of both the epidermis and the coelomic lining of the peristomial membrane in the regular sea‐urchin Paracentrotus lividus is described and correlated with the extreme deformability of the peristomial membrane and with the ≪mutability≫ of its related dermis. The epidermis consists of a monolayer of columnar supporting cel...

The peristomial membrane is an area of flexible body wall which connects the test to the lantern or masticatory apparatus of regular sea‐urchins. The peristomial membrane of Paracentrotus lividus was examined by various light microscopical techniques and by scanning and transmission electron microscopy, and its mechanical properties were investigat...

Crinoids have remarkable regenerative capacities. After traumatic or self-induced amputation they can replace one or several arms through a complex sequence of morphogenetic events which lead quickly to the complete reconstruction of the lost part. These phenomena are well known in their general aspects and a comprehensive description of arm regene...

The Aristotle's lantern, or masticatory apparatus, of regular sea-urchins is a complex musculo-skeletal system which is thought to have contributed significantly to the evolutionary success of these animals. This paper gives an account of the antomical relationships and functional morphology of both skeletal and soft tissue components in the lanter...

Echinoids are the echinoderm group which has explored and exploited most efficiently the potential of the endoskeleton in a range of extremely advanced and sophisticated adaptive solutions. The most ingenious of these adaptations are employed in the dental apparatus, whose different elements represent a striking example of the versatility of the sk...

The regeneration of the arm of the crinoid Antedon mediterranea has been studied by means of LM, TEM, and SEM techniques as regards the development of both the external form and the internal anatomical organization. According to the timing and the modalities of development of the different structures and their reciprocal interactions, three main st...

The peculiar functional structure of the Z-line in the obliquely striated muscles of some feather stars is described. It is known that cross-striated muscles are characterized by linear and continuous Z-bands, and obliquely striated muscles by disconnected, obliquely aligned Z-elements. Owing to this discontinuous organization, the sarcomere can pe...