Anatomy / Physiology
Vascularization of the trachea in the bottlenose dolphin: comparison with bovine and evidence for evolutionary adaptations to diving
Autori: Ballarin C, Bagnoli P, Peruffo A, Cozzi B
Riferimenti: R Soc Open Sci. (2018) 5(4):171645
Summary: The rigid structure of the mammalian trachea is functional to maintain constant patency and airflow during breathing, but no gas exchange takes place through its walls. The structure of the organ in dolphins shows increased rigidity of the tracheal cartilaginous rings and the presence of vascular lacunae in the submucosa. However, no actual comparison was ever made between the size and capacity of the vascular lacunae of the dolphin trachea and the potentially homologous structures of terrestrial mammals. In the present study, the extension of the lacunae has been compared between the bottlenose dolphin and the bovine, a closely related terrestrial Cetartiodactyla. Our results indicate that the extension of the blood spaces in the submucosa of dolphins is over 12 times larger than in the corresponding structure of the bovines. Furthermore, a microscopic analysis revealed the presence of valve-like structures in the walls of the cetacean lacunae. The huge difference in size suggests that the lacunae are not merely a product of individual physiological plasticity, but may constitute a true adaptive evolutionary character, functional to life in the aquatic environment. The presence of valve-like structures may be related to the regulation of blood flow, and curtail excessive compression under baric stress at depth.
Link: https://royalsocietypublishing.org/doi/10.1098/rsos.171645
Forebrain neuroanatomy of the neonatal and juvenile dolphin (T.truncatus and S. coeruloalba)
Autori: Parolisi R, Peruffo A, Messina S, Panin M, Montelli S, Giurisato M, Cozzi B, Bonfanti L
Riferimenti: Front Neuroanat. (2015) 9:140
Summary: Knowledge of dolphin functional neuroanatomy mostly derives from post-mortem studies and non-invasive approaches (i.e., magnetic resonance imaging), due to limitations in experimentation on cetaceans. As a consequence the availability of well-preserved tissues for histology is scarce, and detailed histological analyses are referred mainly to adults. Here we studied the neonatal/juvenile brain in two species of dolphins, the bottlenose dolphin (Tursiops truncatus) and the striped dolphin (Stenella coeruleoalba), with special reference to forebrain regions. We analyzed cell density in subcortical nuclei, white/gray matter ratio, and myelination in selected regions at different anterior–posterior levels of the whole dolphin brain at different ages, to better define forebrain neuroanatomy and the developmental stage of the dolphin brain around birth. The analyses were extended to the periventricular germinal layer and the cerebellum, whose delayed genesis of the granule cell layer is a hallmark of postnatal development in the mammalian nervous system. Our results establish an atlas of the young dolphin forebrain and, on the basis of occurrence/absence of delayed neurogenic layers, confirm the stage of advanced brain maturation in these animals with respect to most terrestrial mammals.
Link: https://www.frontiersin.org/articles/10.3389/fnana.2015.00140/full#h1
The claustrum of the bottlenose dolphin Tursiops truncatus (Montagu 1821)
Autori: Cozzi B, Roncon G, Granato A, Giurisato M, Castagna M, Peruffo A, Panin M,Ballarin C, Montelli S, Pirone A
Riferimenti: Front Syst Neurosci. (2014) 28; 8:42
Summary: The mammalian claustrum is involved in processing sensory information from the environment. The claustrum is reciprocally connected to the visual cortex and these projections, at least in carnivores, display a clear retinotopic distribution. The visual cortex of dolphins occupies a position strikingly different from that of land mammals. Whether the reshaping of the functional areas of the cortex of cetaceans involves also modifications of the claustral projections remains hitherto unanswered. The present topographic and immunohistochemical study is based on the brains of eight bottlenose dolphins and a wide array of antisera against: calcium-binding proteins (CBPs) parvalbumin (PV), calretinin (CR), and calbindin (CB); somatostatin (SOM); neuropeptide Y (NPY); and the potential claustral marker Gng2. Our observations confirmed the general topography of the mammalian claustrum also in the bottlenose dolphin, although (a) the reduction of the piriform lobe modifies the ventral relationships of the claustrum with the cortex, and (b) the rotation of the telencephalon along the transverse axis, accompanied by the reduction of the antero-posterior length of the brain, apparently moves the claustrum more rostrally. We observed a strong presence of CR-immunoreactive (-ir) neurons and fibers, a diffuse but weak expression of CB-ir elements and virtually no PV immunostaining. This latter finding agrees with studies that report that PV-ir elements are rare in the visual cortex of the same species. NPY- and somatostatin-containing neurons were evident, while the potential claustral markers Gng2 was not identified in the sections, but no explanation for its absence is currently available. Although no data are available on the projections to and from the claustrum in cetaceans, our results suggest that its neurochemical organization is compatible with the presence of noteworthy cortical inputs and outputs and a persistent role in the general processing of the relative information.
Link: https://www.frontiersin.org/articles/10.3389/fnsys.2014.00042/full#h1
Growth and stress factors in ballan wrasse (Labrus bergylta) larval development
Autori: Piccinetti CC, Grasso L, Maradonna F, Radaelli G, Ballarin C, Chemello G, Evjemo JO, Carnevali O, Olivotto I
Riferimenti: Aquaculture Research, 48 (5), pp. 2567-2580.
Summary: Ballan wrasse (Labrus bergylta) is a specialized cleaner fish used in salmon farms as a biological treatment against sea lice. Its commercial rearing is at present mostly experimental. A number of key aspects, including the molecular and physiological mechanisms that promote its growth and development, are still largely unexplored. In this study histological, biometric, biochemical and molecular approaches are combined for the first time to investigate the changes in growth (insulin‐like growth factor 1 and 2 and myostatin) and stress (heat shock protein 70 and cortisol) markers that occur during ballan wrasse larval development by relating them to larval stages and feed changes. The real‐time PCR data demonstrated that igf1 transcripts rose from 1 day post‐hatching (dph) and were no longer detectable 38 dph, whereas igf2 and myostatin transcripts were low and stable until 28 dph, then rose in late larval stages. The biometric and histological data matched the molecular findings, documenting rapid growth and development of the larval digestive tract and assimilation ability. Cortisol was lowest at hatching, it rose slightly at first feeding, and then increased during larval development; a similar trend was detected for hsp70 gene expression. The low cortisol levels found at the earliest larval stages reflect a poor stress‐coping ability, a feature that may actually protect larvae from the elevated metabolic demands involved by stress responses and promote faster growth and survival. The present data can be applied to improve the rearing performances of this important cleaner species and reduce captures from the wild.
Sperm quality in wild-caught and farmed males of the European eel (Anguilla anguilla)
Autori: Locatello L, Bertotto D, Cerri R, Parmeggiani A, Govoni N, Trocino A, Xiccato G, Mordenti O
Riferimenti: Animal Reproduction Science (2018) 198, pp. 167-176
Summary: Sperm density and performance of wild and farmed male European eels were evaluated to investigate the effect of maintenance in captivity on ejaculate quality. Hormonal stimulation (with human chorionic gonadotropin) lasted for 17 weeks. Different origins of the male European eels partially influenced the quality of the ejaculates. Indeed, wild animals (i.e., collected at a natural site) had greater sperm longevity during the hormonal stimulation, whereas there was no significant effect of the origin on sperm density, spermatocrit, the percentage of motile sperm, and plasma testosterone concentrations. The different origins of the males also affected fatty acid sperm content, with greater unsaturated fatty acid and omega-6 concentrations in wild eels and lesser concentrations of saturated fatty acids and omega-3 fatty acids in farmed eels. Regarding sperm quality of European eels, this is the first study that takes into account the effect of different origins of stimulated males (wild-caught compared with farmed) on sperm quality, and these findings may help to improve the production of high-quality gametes in this endangered species.
Link: https://www.sciencedirect.com/science/article/pii/S0378432018301155?via%3Dihub
Histological development of the long-snouted seahorse Hippocampus guttulatus during ontogeny
Autori: Ofelio C, Díaz AO, Radaelli G, Planas M
Riferimenti: J Fish Biol. (2018) Jul; 93(1): 72-87
Summary: The objective of the present study was to describe histological development of the European long-snouted seahorse Hippocampus guttulatus, to increase understanding of the biology and physiology of the species. Most vital organs were present in juveniles by the time of their release from the male's pouch. Digestive tract specialization occurred at 89 effective day-degrees (D°eff ), corresponding to 15 days post partum (dpp), with development of the first intestinal loop and mucosal folding. At 118 D°eff (20 dpp), lipids were being mobilized from the liver and oocytes attained the perinuclear stage. The fovea emerged at 177 D°eff (30 dpp), contemporaneous with the shift from pelagic to benthic behaviour in juveniles. At this stage, the most interesting feature was the formation of the second intestinal loop. Male gonads were never observed during the study (from 0 to 354 D°eff ; 0-60 dpp), but the first oogonia were present at 30 D°eff (5 dpp). In 354 D°eff (60 dpp) juveniles, oocytes were observed in a cortical alveoli stage, indicating maturity. Low digestive efficiency was observed at early stages, which was due to a poorly developed gastrointestinal tract and an immature digestive tract prior to 89 D°eff . The present study demonstrates that approximately 89 and 177 D°eff represent two important transitional stages in the early development of H. guttulatus. At a temperature of approximately 19 ± 1°C and an age of 1 month (177 D°eff ), main organs were fully functional, suggesting that the adult phenotype was largely established by that age, with females becoming mature at the age of 2 months (354 D°eff ).
Insights Into Dolphins’ Immunology: Immuno-Phenotypic Study on Mediterranean and Atlantic Stranded Cetaceans
Autori: Centelleghe C, Da Dalt L, Marsili L, Zanetti L, Fernandez A, Arbelo M, Sierra E, Castagnaro M, Di Guardo G, Mazzariol S
Riferimenti: Front. Immunol. (2019) 10:888
Summary: Immunology of marine mammals is a relatively understudied field and its monitoring plays an important role in the individual and group management of these animals, along with an increasing value as an environmental health indicator. This study was aimed at implementing the knowledge on the immune response in cetaceans stranded along the Italian coastline to provide a baseline useful for assessing the immune status of bottlenose (Tursiops truncatus) and striped (Stenella coeruleoalba) dolphins. In particular, since the Mediterranean Sea is considered a heavily polluted basin, a comparison with animals living in open waters such as the Atlantic Ocean was made. Formalin-fixed, paraffin-embedded spleen, thymus, and lymph node tissues from 16 animals stranded along Italian and 11 cetaceans from the Canary Island shores were sampled within 48 h from death. Information regarding stranding sites, gender, and age as well as virologic, microbiological, and parasitological investigations, and the cause and/or the death mechanism were also collected in order to carry out statistical analyses. Selected tissues were routinely stained with hematoxylin-eosin (H&E) and with immunohistochemical techniques (IHC). For IHC analysis, anti-human CD5 monoclonal mouse antibody to identify T lymphocytes, CD20 monoclonal mouse antibody for the identification of mature B lymphocytes and HLA-DR antigen (alpha-chain) monoclonal mouse antibody for the identification of the major histocompatibility complex type II were previously validated for both species by Western-blotting technique. T-test method applied to quantitative evaluation of IHC positive cells showed a significant relationship between the number of (expression) of CD20 stained lymphocytes and normal and hypoplastic lymph nodes, respectively. No other significant correlations were noticed. Analyses for organochlorines (OC) compounds were performed in animals (n°5) having frozen blubber tissue available. A simple linear regression was calculated to predict if the amount of OCs could influence the number of inflammatory cell subpopulations and a moderate negative correlation was found between the presence of high quantity of contaminants and the number of T lymphocytes. Future analysis should be aimed to understand the effect of the major immunomodulatory pathogens on sub-populations of B and T cells.
Link: https://www.frontiersin.org/articles/10.3389/fimmu.2019.00888/full
Dynamics of blood circulation during diving in the bottlenose dolphin (Tursiops truncatus): the role of the retia mirabilia
Autori: Bonato M, Bagnoli P, Centelleghe C, Maric M, Brocca G, Mazzariol S, Cozzi B
Riferimenti: J Exp Biol. (2019) Mar 7; 222
Summary: The retia mirabilia are vascular nets composed of small vessels dispersed among numerous veins, allowing blood storage, regulation of flow and pressure damping effects. Here, we investigated their potential role during the diving phase of the bottlenose dolphin (Tursiops truncatus). To this effect, the whole vertebral retia mirabilia of a series of dolphins were removed during post-mortem analysis and examined to assess vessel diameters, and estimate vascular volume and flow rate. We formulated a new hemodynamic model to help clarify vascular dynamics throughout the diving phase, based on the total blood volume of a bottlenose dolphin, and using data available about the perfusion of the main organs and body systems. We computed the minimum blood perfusion necessary to the internal organs, and the stroke volume and cardiac output during the surface state. We then simulated breath-holding conditions and perfusion of the internal organs under the diving-induced bradycardia and reduction of stroke volume and cardiac output, using 10 beats min−1 as the limit for the heart rate for an extended dive of over 3 min. Within these simulated conditions, the retia mirabilia play a vital role as reservoirs of oxygenated blood that permit functional performances and survival of the heart and brain. Our theoretical model, based on the actual blood capacity of the retia mirabilia and available data on organ perfusion, considers the dynamic trend of vasoconstriction during the diving phase and may represent a baseline for future studies on the diving physiology of dolphins and especially for the blood supply to their brain.
Differences in brain gene transcription profiles advocate for an important role of cognitive function in upstream migration and water obstacles crossing in European eel
Autori: Podgorniak T, Milan M, Pujolar JM, Maes GE, Bargelloni L, De Oliveira E, Pierron F, Daverat F.
Riferimenti: BMC Genomics. 2015 May 12;16:378. doi: 10.1186/s12864-015-1589-y.
Summary: Background European eel is a panmictic species, whose decline has been recorded since the last 20 years. Among human-induced environmental factors of decline, the impact of water dams during species migration is questioned. The main issue of this study was to pinpoint phenotypic traits that predisposed glass eels to successful passage by water barriers. The approach of the study was individual-centred and without any a priori hypothesis on traits involved in the putative obstacles selective pressure. We analyzed the transcription level of 14,913 genes.
Results Transcriptome analysis of three tissues (brain, liver and muscle) from individuals sampled on three successive forebays separated by water obstacles indicated different gene transcription profiles in brain between the two upstream forebays. No differences in gene transcription levels were observed in liver and muscle samples among segments. A total of 26 genes were differentially transcribed in brain. These genes encode for, among others, keratins, cytokeratins, calcium binding proteins (S100 family), cofilin, calmodulin, claudin and thy-1 membrane glycoprotein. The functional analysis of these genes highlighted a putative role of cytoskeletal dynamics and synaptic plasticity in fish upstream migration.
Conclusion Synaptic connections in brain are solicited while eels are climbing the obstacles with poorly designed fishways. Successful passage by such barriers can be related to spatial learning and spatial orientation abilities when fish is out of the water.
Link: https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-015-1589-y
Revealing Mytilus galloprovincialis transcriptomic profiles during ontogeny
Autori: Moreira R, Pereiro P, Balseiro P, Milan M, Pauletto M, Bargelloni L, Novoa B, Figueras A
Riferimenti: Developmental and Comparative Immunology 2018 Feb 23;84:292-306.
Summary: Mediterranean mussels are a worldwide spread bivalve species with extraordinary biological success. One of the reasons of this success could be the reproduction strategy of bivalves, characterized by the presence of trochophore larvae. Larval development in bivalves has been a topic of raising interest in the scientific community but it deserves much more attention. The principal objective of this work was to study the transcriptomic profile of the ontogeny of Mytilus galloprovincialis analyzing the gene expression in different developmental stages, from oocytes to juveniles. For this purpose, after conducting a 454 sequencing of the transcriptomes of mussel hemocytes, adult tissues and larvae, a new DNA microarray was designed and developed.
The studied developmental stages: unfertilized oocytes, veliger, pediveliger, settled larvae and juveniles, showed very different transcriptomic profiles and clustered in groups defining their characteristic gene expression along ontogeny. Our results show that oocytes present a distinct and characteristic transcriptome. After metamorphosis, both settled larvae and juveniles showed a very similar transcriptome, with no enriched GO terms found between these two stages. This suggests: 1.- the progressive loss of RNA of maternal origin through larval development and 2.- the stabilization of the gene expression after settlement.
On the other hand during metamorphosis a specific profile of differentially expressed genes was found. These genes were related to processes such as differentiation and biosynthesis. Processes related to the immune response were strongly down regulated. These suggest a development commitment at the expense of other non-essential functions, which are temporary set aside. Immune genes such as antimicrobial peptides suffer a decreased expression during metamorphosis. In fact, we found that the oocytes which express a higher quantity of genes such as myticins are more likely to reach success of the offspring, compared to oocytes poor in such mRNAs, whose progeny died before reaching metamorphosis.
Link: https://www.sciencedirect.com/science/article/pii/S0145305X17306699?via%3Dihub
Changes in the gene expression profiles of the brains of male European eels (Anguilla anguilla) during sexual maturation
Autori: Churcher AM, Pujolar JM, Milan M, Hubbard PC, Martins RS, Saraiva JL, Huertas M, Bargelloni L, Patarnello T, Marino IA, Zane L, Canário AV
Riferimenti: BMC Genomics. 2014 Sep 17;15:799. doi: 10.1186/1471-2164-15-799.
Summary: Background The vertebrate brain plays a critical role in the regulation of sexual maturation and reproduction by integrating environmental information with developmental and endocrine status. The European eel Anguilla anguilla is an important species in which to better understand the neuroendocrine factors that control reproduction because it is an endangered species, has a complex life cycle that includes two extreme long distance migrations with both freshwater and seawater stages and because it occupies a key position within the teleost phylogeny. At present, mature eels have never been caught in the wild and little is known about most aspects of reproduction in A. anguilla. The goal of this study was to identify genes that may be involved in sexual maturation in experimentally matured eels. For this, we used microarrays to compare the gene expression profiles of sexually mature to immature males.
Results Using a false discovery rate of 0.05, a total of 1,497 differentially expressed genes were identified. Of this set, 991 were expressed at higher levels in brains (forebrain and midbrain) of mature males while 506 were expressed at lower levels relative to brains of immature males. The set of up-regulated genes includes genes involved in neuroendocrine processes, cell-cell signaling, neurogenesis and development. Interestingly, while genes involved in immune system function were down-regulated in the brains of mature males, changes in the expression levels of several receptors and channels were observed suggesting that some rewiring is occurring in the brain at sexual maturity.
Conclusions This study shows that the brains of eels undergo major changes at the molecular level at sexual maturity that may include re-organization at the cellular level. Here, we have defined a set of genes that help to understand the molecular mechanisms controlling reproduction in eels. Some of these genes have previously described functions while many others have roles that have yet to be characterized in a reproductive context. Since most of the genes examined here have orthologs in other vertebrates, the results of this study will contribute to the body of knowledge concerning reproduction in vertebrates as well as to an improved understanding of eel biology.
Link: https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-15-799
Production, Characterization and Biocompatibility of Marine Collagen Matrices from an Alternative and Sustainable Source: The Sea Urchin Paracentrotus lividus
Autori: Cristiano Di Benedetto, Alice Barbaglio, Tiziana Martinello, Valentina Alongi, Dario Fassini, Emanuele Cullorà, Marco Patruno, Francesco Bonasoro, Mario Adolfo Barbosa, Maria Daniela Candia Carnevali and Michela Sugni
Riferimenti: Mar. Drugs 2014, 12, 4912-4933; doi:10.3390/md12094912
Summary: 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 among the safest and recently exploited ones. Sea urchins possess a circular area of soft tissue surrounding the mouth, the peristomial membrane (PM), mainly composed by mammalian-like collagen. The PM of the edible sea urchin Paracentrotus lividus therefore represents a potential unexploited collagen source, easily obtainable as a food industry waste product. Our results demonstrate that it is possible to extract native collagen fibrils from the PM and produce suitable substrates for in vitro system. The obtained matrices appear as a homogeneous fibrillar network (mean fibril diameter 30-400 nm and mesh < 2 μm) and display remarkable mechanical properties in term of stiffness (146 ± 48 MPa) and viscosity (60.98 ± 52.07 GPa·s). In vitro tests with horse pbMSC show a good biocompatibility in terms of overall cell growth. The obtained results indicate that the sea urchin P. lividus can be a valuable low-cost collagen source for mechanically resistant biomedical devices.
