Bruno Tota

Biology of antarctic fish

1 Ecology, Evolution and Life History.- Ecology of Notothenioid Fish in the Weddell Sea (With 8 Figures).- Morphological Adaptations and Mode of Life in High Antarctic Fish (With 6 Figures).- The Biological and Demographic Peculiarities of the Icefish Champsocephalus gunnari Lonnberg, 1905 from the Kerguelen Plateau (With 8 Figures).- Is the Growth of Polar Fish Limited by Temperature? (With 6 Figures).- Review of the Early Life History of Antarctic Notothenioid Fish (With 1 Figure).- Age Determination in Antarctic Fish (With 4 Figures).- Microstructural Analysis of Growth Patterns in the Early Life History of Antarctic Fishes (With 7 Figures).- The Fossil and Modern Fish Faunas of Antarctica: Evolution and Diversity (With 3 Figures).- The Contribution of the BIOMASS Program to Antarctic Marine Ecosystem Research (With 3 Figures).- 2 Physiology, Biochemistry and Molecular Biology.- The Sensory Biology of Notothenioid Fish (With 9 Figures).- Viscosity of Body Fluids from Antarctic Notothenioid Fish (With 9 Figures).- Low Temperature Limits Burst Swimming Performance in Antarctic Fish (With 6 Figures).- Respiratory and Cardiovascular Adaptations in Hemoglobin-Free Fish: Resolved and Unresolved Problems (With 2 Figures).- Structural and Mechanical Characteristics of the Heart of the Icefish Chionodraco hamatus (Lonnberg) (With 10 Figures).- Physiological Roles of High Lipid Content in Tissues of Antarctic Fish Species (With 5 Figures).- Biochemical Mechanisms of Cold Adaptation and Stenothermality in Antarctic Fish (With 10 Figures).- Polymerization of Microtubule Proteins from Antarctic Fish (With 6 Figures).- The Biochemistry of Oxygen Transport in Red-Blooded Antarctic Fish (With 2 Figures).

Cardiac growth, myoglobin, proteins and DNA in developing tuna (Thunnus thynnus thynnus L.)

Abstract 1. 1. The relative heart weight in the developing tuna (body weights range from 0.6–350 kg) is substantially greater than in other seawater fish and corresponds to values found in small mammals. 2. 2. The relative heart weight shows two different growth velocities with the breaking point between 10 and 20 kg of body weight. The concentration of cardiac myoglobin also shows two velocities, smaller tunas exhibiting lower rates compared with the larger ones, with the breaking point close to that of the body weight to heart weight relation. 3. 3. Of the total myocardial proteins 86% are of muscular type. The outer layer of the cardiac ventricle, which is compact, contains more muscular proteins than the inner spongy layer and in both these muscular compartments there is a slight increase of muscular proteins with age. 4. 4. For juvenile animals, in both muscular compartments there are high DNA concentrations which decline with age.

Morphometric and ultrastructural features of the ventricular myocardium of the haemoglobin-less icefish Chaenocephalus aceratus

Abstract 1. 1. The relationship between heart ventricle weight and body weight has been determined for three species of Antarctic fish with respiratory pigments (Notothenia gibberifrons, Notothenia neglecta and Notothenia rossii) and the haemoglobin-less icefish Chaenocephulus aceratus. 2. 2. Relative heart weights of Notothenidae are similar to those of other teleosts whilst those of Channichthyidae are similar to those reported for tuna and small mammals. 3. 3. The volume densities of mitochondria and myofibrils for ventricular myocytes were 0.47 and 0.25 respectively. The values for mitochondrial volume density are higher and those for myofibrillar volume density lower than for most vertebrate hearts. 4. 4. Some unusual characteristics of these mitochondria are reported and discussed in relation to the unique constraints characterizing this type of heart.

Myoglobin in the heart ventricle of tuna and other fishes.

The myoglobin content in the hearts of several fishes is positively correlated with the ecological physiology of the species. In the tuna heart, where the highest myoglobin values are found, the logarithmic relationship between myoglobin content and body weight is reported.

Catecholamines, cardiac natriuretic peptides and chromogranin A: evolution and physiopathology of a ‘whip-brake’ system of the endocrine heart

Summary In the past 50 years, extensive evidence has shown the ability of vertebrate cardiac non-neuronal cells to synthesize and release catecholamines (CA). This formed the mindset behind the search for the intrinsic endocrine heart properties, culminating in 1981 with the discovery of the natriuretic peptides (NP). CA and NP, co-existing in the endocrine secretion granules and acting as major cardiovascular regulators in health and disease, have become of great biomedical relevance for their potent diagnostic and therapeutic use. The concept of the endocrine heart was later enriched by the identification of a growing number of cardiac hormonal substances involved in organ modulation under normal and stress-induced conditions. Recently, chromogranin A (CgA), a major constituent of the secretory granules, and its derived cardio-suppressive and antiadrenergic peptides, vasostatin-1 and catestatin, were shown as new players in this framework, functioning as cardiac counter-regulators in ‘zero steady-state error’ homeostasis, particularly under intense excitatory stimuli, e.g. CA-induced myocardial stress. Here, we present evidence for the hypothesis that is gaining support, particularly among human cardiologists. The actions of CA, NP and CgA, we argue, may be viewed as a hallmark of the cardiac capacity to organize ‘whip-brake’ connection-integration processes in spatio-temporal networks. The involvement of the nitric oxide synthase (NOS)/nitric oxide (NO) system in this configuration is discussed. The use of fish and amphibian paradigms will illustrate the ways that incipient endocrine-humoral agents have evolved as components of cardiac molecular loops and important intermediates during evolutionary transitions, or in a distinct phylogenetic lineage, or under stress challenges. This may help to grasp the old evolutionary roots of these intracardiac endocrine/paracrine networks and how they have evolved from relatively less complicated designs. The latter can also be used as an intellectual tool to disentangle the experimental complexity of the mammalian and human endocrine hearts, suggesting future investigational avenues.

The homologous rat chromogranin A1–64 (rCGA1–64) modulates myocardial and coronary function in rat heart to counteract adrenergic stimulation indirectly via endothelium-derived nitric oxide

Chromogranin A (CGA), produced by human and rat myocardium, generates several biologically active peptides processed at specific proteolytic cleavage sites. A highly conserved cleavage N‐terminal site is the bond 64–65 that reproduces the native rat CGA sequence (rCGA1–64), corresponding to human N‐terminal CGA‐derived vasostatin‐1. rCGA1–64 cardiotropic activity has been explored in rat cardiac preparations. In Langendorff perfused rat heart, rCGA1–64 (from 33 nM) induced negative inotropism and lusitropism as well as coronary dilation, counteracting isoproterenol (Iso)‐ and endothelin‐1 (ET‐1) ‐induced positive inotropic effects and ET‐1‐dependent coronary constriction. rCGA1–64 also depressed basal and Iso‐induced contractility on rat papillary muscles, without affecting calcium transients on isolated ventricular cells. Structure‐function analysis using three modified peptides on both rat heart and papillary muscles revealed the disulfide bridge requirement for the cardiotropic action. A decline in Iso intrinsic activity in the presence of the peptides indicates a noncompetitive antagonistic action. Experiments on rat isolated cardiomyocytes and bovine aortic endothelial cells indicate that the negative inotropism observed in rat papillary muscle is probably due to an endothelial phosphatidylinositol 3‐kinase‐dependent nitric oxide release, rather than to a direct action on cardiomyocytes. Taken together, our data strongly suggest that in the rat heart the homologous rCGA1–64 fragment exerts an autocrine/paracrine modulation of myocardial and coronary performance acting as stabilizer against intense excitatory stimuli.— Cerra, M. C., Gallo, M. P., Angelone, T., Quintieri, A. M., Pulera, E., Filice, E., Guerold, B., Shooshtarizadeh, P., Levi, R., Ramella, R., Brero, A., Boero, O., Metz‐Boutigue, M. H., Tota, B., Alloatti, G. The homologous rat chromogranin A1‐64 (rCGA1‐64) modulates myocardial and coronary function in rat heart to counteract adrenergic stimulation indirectly via endothelium‐derived nitric oxide. FASEB J. 22, 3992–4004 (2008)

The catecholamine release-inhibitory peptide catestatin (chromogranin A344-364) modulates myocardial function in fish

SUMMARY Catestatin (CST), the 21-amino acid, cationic and hydrophobic peptide proteolytically derived from the ubiquitous chromogranin A (CgA), is an endogenous inhibitor of catecholamine release, a potent vasodilator in vivo and an anti-hypertensive agent in mammals, including humans. Recently, we discovered that CST also functions as an important negative modulator of heart performance in frog and rat. To gain an evolutionary perspective on CST cardiotropism in fish, we analysed the influence of bovine CST (CgA344-364) on the eel heart, as well as the eventual species-specific mechanisms of its myocardial action. Experiments were carried out on fresh-water eels (Anguilla anguilla L.) using an electrically paced isolated working heart preparation. Stroke volume and stroke work were used as measures of ventricular performance. Under basal conditions, CST (from 11 nmol l–1 to 165 nmol l–1) caused a concentration-dependent negative inotropism, which was abolished by inhibitors of either β1/β2 (propranolol) or β3 (SR59230) adrenergic receptors, or by Gi/o protein (PTx) or nitric oxide synthase (L-NMMA), or guanylate cyclase (ODQ) blockers. This suggests a β-adrenergic receptor-Gi/o protein-NO-cGMP-dependent mechanism. By contrast, the CST-induced cardio-suppression was not influenced by atropine, unspecific muscarinic antagonist, thus excluding cholinergic receptor involvement. CST also counteracted the adrenergic (isoproterenol)-mediated positive inotropism. Under increased preload (i.e. Frank–Starling response) conditions, CST induced a significant increase of the Frank–Starling response, which was blocked by L-NMMA and thapsigargin, but independent from guanylate cyclase. In conclusion, this is the first report in fish that CST modulates myocardial performance under basal, as well as under increased preload, conditions and counteracts the adrenergic-mediated positive inotropism, which strikingly supports the evolutionary significance and establishes the cardioactive role of this peptide.

The novel chromogranin A-derived serpinin and pyroglutaminated serpinin peptides are positive cardiac β-adrenergic-like inotropes

Three forms of serpinin peptides, serpinin (Ala26Leu), pyroglutaminated (pGlu)‐serpinin (pGlu23Leu), and serpinin‐Arg‐Arg‐Gly (Ala29Gly), are derived from cleavage at pairs of basic residues in the highly conserved C terminus of chromogranin A (CgA). Serpinin induces PN‐1 expression in neuroendocrine cells to up‐regulate granule biogenesis via a cAMP‐protein kinase A‐Sp1 pathway, while pGlu‐serpinin inhibits cell death. The aim of this study was to test the hypothesis that serpinin peptides are produced in the heart and act as novel β‐adrenergic‐like cardiac modulators. We detected serpinin peptides in the rat heart by HPLC and ELISA methods. The peptides included predominantly Ala29Gly and pGlu‐serpinin and a small amount of serpinin. Using the Langendorff perfused rat heart to evaluate the hemodynamic changes, we found that serpinin and pGlu‐serpinin exert dose‐dependent positive inotropic and lusitropic effects at 11–165 nM, within the first 5 min after administration. The pGlu‐serpinin‐induced contractility is more potent than that of serpinin, starting from 1 nM. Using the isolated rat papillary muscle preparation to measure contractility in terms of tension development and muscle length, we further corroborated the pGlu‐serpinin‐induced positive inotropism. Ala29Gly was unable to affect myocardial performance. Both pGlu‐serpinin and serpinin act through a β1‐adrenergic receptor/adenylate cyclase/cAMP/PKA pathway, indicating that, contrary to the β‐blocking profile of the other CgA‐derived cardiosuppressive peptides, vasostatin‐1 and catestatin, these two C‐terminal peptides act as β‐adrenergic‐like agonists. In cardiac tissue extracts, pGluserpinin increased intracellular cAMP levels and phosphorylation of phospholamban (PLN)Ser16, ERK1/2, and GSK‐3β. Serpinin and pGlu‐serpinin peptides emerge as novel β‐adrenergic inotropic and lusitropic modulators, suggesting that CgA and the other derived cardioactive peptides can play a key role in how the myocardium orchestrates its complex response to sympathochromaffin stimulation.—Tota, B., Gentile, S., Pasqua, T., Bassino, E., Koshimizu, H., Cawley, N. X., Cerra, M. C., Loh, Y. P., Angelone, T. The novel chromogranin A‐derived serpinin and pyroglutaminated serpinin peptides are positive cardiac β‐adrenergic‐like inotropes. FASEB J. 26, 2888–2898 (2012). www.fasebj.org

Myofibrillar ATPase in the various red and white trunk muscles of the tunny (Thunnus thynnus L.) and the tub gurnard (Trigla lucerna L.)

Abstract 1. 1. Measurements of myofibrillar adenosine triphosphatase activities have been made from the various red and white muscles of the tunny (Thunnus thynnus L.) and the tub gurnard (Trigla lucerna L.). 2. 2. The ratios of the activities of the white to red muscle were found to be 4·4 times in the case of the tub gurnard and 2 times in the case of the tunny. 3. 3. The activity of the superficial red muscle was found to be twice as high in the tunny as in the tub gurnard although the activities in the white muscle were similar. 4. 4. No difference in specific activity was found between the superficial and deep red muscles of the tunny. 5. 5. These results are discussed in terms of the division of labour between fish myotomal muscles.

Morphological and biochemical characterisation of the inner and outer ventricular myocardial layers of adult tuna fish (Thunnus thynnus L.).

Abstract 1. 1. The inner and outer myocardial layers of ventricles from adult tuna fish were studied using biochemical and ultrastructural methods. 2. 2. Electron transport particle preparations prepared from the inner layer were found to have higher respiratory enzyme activities than the outer layer. 3. 3. No difference was observed between the myofibrillar ATPase activity or the LDH isoenzyme of the two layers. 4. 4. The mitochondria of the inner layer were found to have a higher cristae density than those from the outer layer. 5. 5. It is suggested that the higher metabolic activity of the inner layer may provide a means of metabolising some of the excess lactate produced by the myotomal muscles.