Papers by giacomo zaccone
Fishes
Immune and neuronal cells are often colocalized at defined anatomical sites, forming neuronal cel... more Immune and neuronal cells are often colocalized at defined anatomical sites, forming neuronal cell units, where both cells coordinate their responses [...]
Journal of Morphology, 2016
The morphological characteristics of the venous pole and pericardium of the heart were examined i... more The morphological characteristics of the venous pole and pericardium of the heart were examined in three hagfish species, Myxine glutinosa, Eptatretus stoutii, and Eptatretus cirrhatus. In these species, the atrioventricular (AV) canal is long, funnel-shaped and contains small amounts of myocardium. The AV valve is formed by two pocket-like leaflets that lack a papillary system. The atrial wall is formed by interconnected muscle trabeculae and a well-defined collagenous system. The sinus venosus (SV) shows a collagenous wall and is connected to the left side of the atrium. An abrupt collagen-muscle boundary marks the SV-atrium transition. It is hypothesized that the SV is not homologous to that of other vertebrates which could have important implications for understanding heart evolution. In M. glutinosa and E. stoutii, the pericardium is a closed bag that hangs from the tissues dorsal to the heart and encloses both the heart and the ventral aorta. In contrast, the pericardium is continuous with the loose periaortic tissue in E. cirrhatus. In all three species, the pericardium ends at the level of the SV excluding most of the atrium from the pericardial cavity. In M. glutinosa and E. stoutii, connective bridges extend between the base of the aorta and the ventricular wall. In E. cirrhatus, the connections between the periaortic tissue and the ventricle may carry blood vessels that reach the ventricular base. A further difference specific to E. cirrhatus is that the adipose tissue associated with the pericardium contains thyroid follicles. J. Morphol. 277:853-865, 2016. © 2016 Wiley Periodicals, Inc.
Histochemical Journal, 1984
Without Abstract
Journal of Morphology, 2015
We have studied the heart in three species of hagfish: Myxine glutinosa, Eptatretus stoutii, and ... more We have studied the heart in three species of hagfish: Myxine glutinosa, Eptatretus stoutii, and Eptatretus cirrhatus and report about the morphology of the ventricle, the arterial connection and the ventral aorta. On the whole, the hagfish heart lacks outflow tract components, the ventricle and atrium adopt a dorso-caudal rather than a ventro-dorsal relationship, and the sinus venosus opens into the left side of the atrium. This may indicate a "defective" cardiac looping during embryogenesis. The ventral aorta is elongated in M. glutinosa and E. stoutii but sac-like in E. cirrhatus. The ventricles are entirely trabeculated. The myocytes show a low myofibrillar content and junctional complexes formed by fascia adherens and desmosomes. Gap junctions could not be demonstrated. Myocardial cells in M. glutinosa contain numerous lipid droplets. These droplets are less numerous in E. stoutii and practically absent in E. cirrhatus, suggesting different metabolic requirements. Other cell types present in the ventricle are chromaffin cells and granular leukocytes that contain rod-shaped granules. The ventricle-aorta connection is guarded by a bicuspid valve with left and right, pocket-like leaflets. The leaflets extend from the cranial end of the ventricle into the aorta but the junction is asymmetrical. This junction contains a ganglion-like structure in E. cirrhatus. The ventral aorta shows endothelial, media, and adventitial layers. The media contains smooth muscle cells surrounded by dense bands formed by tightly-packed extracellular filaments. In addition, a short number of elastic fibers are observed in M. glutinosa and E. stoutii. Cellular and extracellular elements are more loosely organized in the aorta of E. cirrhatus. The collagenous adventitia contains ganglion-like cells in the three species. In the absence of nerves, chromaffin and ganglion-like cells may control the activity of the myocardium and that of the aortic smooth muscle cells, respectively. J. Morphol., 2015. © 2015 Wiley Periodicals, Inc.
The Journal of experimental biology, Jan 20, 2015
Nitric oxide (NO) is a gaseous neurotransmitter, which in adult mammals, modulates the acute hypo... more Nitric oxide (NO) is a gaseous neurotransmitter, which in adult mammals, modulates the acute hypoxic ventilatory response; its role in the control of breathing in fish during development is unknown. We addressed the interactive effects of developmental age and NO in the control of piscine breathing by measuring the ventilatory response of zebrafish (Danio rerio) adults and larvae to NO donors and by inhibiting endogenous production of NO. In adults, sodium nitroprusside (SNP), a NO donor, inhibited ventilation; the extent of the ventilatory inhibition was related to the pre-existing ventilatory drive, with the greatest inhibition exhibited during exposure to hypoxia (PO2=5.6 kPa). Inhibition of endogenous NO production using L-NAME supressed the hypoventilatory response to hyperoxia, supporting an inhibitory role of NO in adult zebrafish. Neuroepithelial cells, the putative oxygen chemoreceptors of fish, contain neuronal nitric oxide synthase (nNOS). In zebrafish larvae at 4 days po...
Cellular and molecular biology
Basic and applied histochemistry
The skin epidermis of the Teleost fish Lepadogaster candollei has been studied by cytoenzymatic m... more The skin epidermis of the Teleost fish Lepadogaster candollei has been studied by cytoenzymatic methods. Besides the common epithelial cells, the epidermis is constituted of various cell types, among which are calciform cells, sacciform cells and acidophilic cells. In the cells of the basal epithelium are found hydrolytic enzymes and oxidation-reduction enzyme systems that are tied to processes of growth and cell proliferation. The positive cytoenzymatic reactions in the epithelial elements and in the glandular sacciform cells of the intermediate layers reflect their high metabolic activity. There is even more intense activity in the polygonal epithelial cells of the more superficial layers whose enzymatic machinery is characterized by high reductase and oxidoreductase activities and by alkaline phosphatase activity. These results suggest an active utilization of glucose by anaerobic and aerobic processes as well as by the pentose phosphate shunt thus suggesting the absence of the keratinization processes in the piscine skin epidermis. The cytoenzymatic findings also demonstrate that the epidermis is capable of synthesizing and elaborating materials for cell regeneration.
Gegenbaurs morphologisches Jahrbuch
The skin epidermis of the teleost fish Mastacembelus erythrotaenia has been studied by histochemi... more The skin epidermis of the teleost fish Mastacembelus erythrotaenia has been studied by histochemical methods. 4 cell types were considered in the comparison; mucous goblet cells, sacciform cells, eosinophilic granular cells, and Malpighian cells. Succinate, isocitrate, glucose-6-phosphate, malate, and alpha-glycero-phosphate dehydrogenase did not indicate any changes in activity in the outer epidermal cell layers in comparison with the lower ones where the weakening or absence of the reactions could be inferred to a reversible metabolic state in the fields of the tricarboxylic acid cycle and pentose phosphate pathways. The strong activities of the above oxido-reductive enzymes found in the basal layer were correlated with the proliferative activity of stem cell differentiation and kinetic processes of cell division. The major component of the mucus produced by the mucous goblet cells consists of weakly acidic mucins showing in their carbohydrate moieties both the sialic acids and sulphated components with a lower degree of sulphation as evidenced by the appropriate histochemical methods. The sacciform cells produce a tryptophan rich protein and serotonin, the latter presumably acting in the control of mucus release since the N-acetylneuraminic acid is known to be an integral part of the serotonin receptor (Gottschalk 1972). Other functions related to the above amine may include its toxicity against the potential predators.
Amia calva is the only living representative of Amiiformes order. It is a species having a swim b... more Amia calva is the only living representative of Amiiformes order. It is a species having a swim bladder transformed into a lung, so it can breathe an air. It gives him a high tolerance to varying oxygen conditions and the ability to survive even in the water almost devoid of oxygen. The aim of the study was to examine whether different oxygen conditions (hypoxia , normoxia and hyperoxia) affect the development of the olfactory organ in A. calva in different age classes. The study used a left olfactory organ olfactory rosette with two age classes of fish breed at defined oxygen conditions. After sectioning of olfactory rosettes, and then individual olfactory lamellas, both-side surface was measured out. In the individuals from an older age group also the number of proliferating and apoptotic cells were counted using immunocytochemistry method (PCNA and CPP- 32). Bilateral olfactory rosettes area, the number of proliferating cells and apoptotic showed statistically significant differe...
Annals of the New York Academy of Sciences, Jan 8, 2015
Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have ... more Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxygen sensing, adaptation to hypoxia, and mechanisms of anoxia tolerance in nonmammalian vertebrates. We discuss the respiratory structures in fish, including the skin, gills, and air-breathing organs, and recent evidence for chemosensory neuroepithelial cells (NECs) in these tissues that initiate reflex responses to hypoxia. The use of the zebrafish as a genetic and developmental model has allowed observation of the ontogenesis of respiratory and chemosensory systems, demonstration of a putative intracellular O2 sensor in chemoreceptors that may initiate transduction of the hypoxia signal, and investigation into the effects of extreme hypox...
Journal of experimental zoology. Part A, Comparative experimental biology, 2006
Anatomical and histochemical studies have demonstrated that the bulk of autonomic neurotransmissi... more Anatomical and histochemical studies have demonstrated that the bulk of autonomic neurotransmission in fish gill is attributed to cholinergic and adrenergic mechanisms (Nilsson. 1984. In: Hoar WS, Randall DJ, editors. Fish physiology, Vol. XA. Orlando: Academic Press. p 185-227; Donald. 1998. In: Evans DH, editor. The physiology of fishes, 2nd edition. Boca Raton: CRC Press. p 407-439). In many tissues, blockade of adrenergic and cholinergic transmission results in residual responses to nerve stimulation, which are termed NonAdrenergic, NonCholinergic (NANC). The discovery of nitric oxide (NO) has provided a basis for explaining many examples of NANC transmissions with accumulated physiological and pharmacological data indicating its function as a primary NANC transmitter. Little is known about the NANC neurotransmission, and studies on neuropeptides and NOS (Nitric Oxide Synthase) are very fragmentary in the gill and the air-breathing organs of fishes. Knowledge of the distribution...
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Papers by giacomo zaccone