3,063 research outputs found
The bulbus arteriosus of the holocephalan heart
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013.Anatomical Record, Volume 296, Special Feature — 1: P-074.Previous work has shown that the outflow tract of the elasmobranch heart, namely the
cardiac portion intercalated between the ventricle and the ventral aorta, does not consist
of a single component, the conus arteriosus, as has classically been assumed, but two,
the myocardial conus arteriosus and the non-myocardial bulbus arteriosus. From the
evolutionary perspective, knowledge of the anatomy of the cardiac outflow tract of the
holocephali is important, as they are the sister group of elasmobranchs. Our aim is to
describe the cardiac outflow tract of four holocephalan species, two of them, Chimaera
monstrosa and Hydrolagus affinis of the family Chimaeridae, and the other two, Harriotta
raleighana and Rhinochimaera atlantica, of the family Rhinochimaeridae. The cardiac
outflow tract of the four species consisted of a myocardial conus arteriosus, furnished
with valves, and a bulbus arteriosus devoid of cardiac muscle. Both the bulbus and
conus are tubular in shape. The length of the bulbus relative to the total length of the
outflow tract is somewhat smaller in the rhinochimaerids (15%-19%) than in the
chimaerids (19%-23%). The bulbus is covered by epicardium and is crossed by the main
coronary artery trunks. Histologically, the bulbus is mainly composed of elastin and
collagen, and, to a lesser extent, by smooth muscle. This suggests that in
holocephalans, the bulbus actively helps to protect the gill vasculature from exposure to
high-pressure pulses of blood. Our results prove that the bulbus arteriosus is common to
chondrichthyans. In addition, they support the hypothesis that the cardiac outflow tract
consisted of a conus arteriosus and a bulbus arteriosus from the beginning of the jawed
vertebrate radiation, contributing to our understanding of the morphological changes that
have occurred at the arterial pole of the heart in both actinopterygians and
sarcopterygians.Proyecto CGL2010-16417/BOS; Fondos FEDE
MYOCARDIAL STRUCTURE AND VASCULARIZATION OF THE HEART VENTRICLE IN HOLOCEPHALI: IMPLICATIONS FOR HEART EVOLUTION
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013. Anatomical Record, Volume 296, Special Feature — 1: P-075.It has been classically assumed that the ventricle of the primitive vertebrate heart is
composed of spongy myocardium, supplied exclusively by oxygen-poor, luminal blood.
This idea is on two facts: (1) extant agnathans have a spongy ventricular myocardium,
and (2) in avian and mammalian embryos, the formation of trabeculated myocardium
precedes the appearance of compact myocardium. Recently, it has been proposed that,
like elasmobranchs, the early gnathostomes possess a fully vascularised ventricle
composed of mixed myocardium. We tested this idea by studying the structure and
vascularisation of the ventricular myocardium in four holocephalan species of the
families Chimaeridae and Rhinochimaeridae. Chimaera monstrosa, Hidrolagus affinis
and Harriotta raleighana have a spongy myocardium covered by a thin layer of cardiac
muscle. In H. raleighana, the compacta is reduced to an extremely fine rim. In all three
species there is a well-developed coronary artery system consisting of subepicardial
vessels which give off branches that penetrate the myocardial trabeculae.
Rhinochimaera atlantica has no compacta and its ventricular coronary artery system is
reduced to subepicardial vessels that do not enter the spongy layer. This report is the
first to show that in wild living vertebrates, a coronary artery system supplying the whole
myocardium exists in the absence of a well-developed compacta, which supports
experimental work that shows that myocardial cell proliferation and coronary vascular
growth rely on genetically separated programs. We conclude that the mixed ventricular
myocardium is primitive for chondrichthyans, and that the lack of compacta in some
holocephalans is a derived character. Moreover our results support the hypotheses that
the mixed myocardium is the primitive condition in gnathostomes, and that the absence
of a compacta in different actinopterygian taxa is the result of its repeated loss during
evolution.Proyecto CGL2010-16417/BOS; Fondos FEDE
The Myosin Heavy Chain specific A4.1025 antibody discriminates different cardiac segments in ancient groups of gnathostomes: Morphological and evolutionary implications
El resumen aparece en el Program & Abstracts of the 11th International Congress of Vertebrate Morphology, Washington DC 2016. Anatomical Record, Volume 299, Special Feature: 263.The pan-Myosin Heavy Chain (pan-MyHC) marker MF20 have been reported to show similar, homogeneous signal in the myocardial segments of the heart of teleosts and tetrapods. However, in an ongoing study of the myocardial structure of the dogfish (Scyliorhinus canicula; Chondrichthyes), we observed differential immunostaining of the cardiac segments using another pan-MyHC, the A4.1025 antibody. In order to investigate the
relevance of this finding for better understanding of the morphology and evolution of the vertebrate heart, we performed immunohistochemistry, slot blot and western blot in several species of chondrichthyans, actinopterygians and mammals using the above mentioned antibodies. In the dogfish heart, A4.1025 and MF20 specifically recognized MyHC isoforms, although with different degree of affinity. MF20 reactivity was homogeneous and high in all the myocardial segments. However, A4.1025 reactivity was heterogeneous. It was high in the sinus venosus (external layer), atrium and atrioventricular region, low in the ventricle and conus arteriosus, and null in the internal layer of the sinus venosus. A heterogeneous pattern of A4.1025 immunoreactivity was also detected in two other elasmobranchs, a holocephalan, a polypteryform and an acipenseriform. In all of these species, MF20 immunoreactivity was homogeneous. In addition, both markers showed a homogeneous immunoreactivity pattern in teleosts and mammals. Our results indicate that in the hearts of ancient gnathostomes, in all of which a conspicuous conus arteriosus exists, one or more MyHC isoforms with low affinity for A4.1025 show segment-specific distributions. Thus, A4.1025 appears to be an appropriated marker to identify the cardiac segments and their boundaries. We propose that the segmentspecific distribution of MyHC isoforms may generate a particular type of myocardial contractility associated with the
presence of a conus arteriosus.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. CGL2014-52356-P, CEIMAR, BIO 203, FEDE
Vortex Plastic Motion in Twinned Superconductors
We present simulations, without electrodynamical assumptions, of
, and , in hard superconductors, for a variety
of twin-boundary pinning potential parameters, and for a range of values of the
density and strength of the pinning sites. We numerically solve the overdamped
equations of motion of up to 10^4 flux-gradient-driven vortices which can be
temporarily trapped at pinning centers. These simulations relate
macroscopic measurements (e.g., M(H), ``flame'' shaped profiles) with
the underlying microscopic pinning landscape and the plastic dynamics of
individual vortices
Anatomical, histochemical and immunohistochemical characterization of the outflow tract of ray hearts (Rajiformes; Chondrichthyes)
El resumen aparece en el Program & Abstracts of the 11th International Congress of Vertebrate Morphology, Washington DC 2016. Anatomical Record, Volume 299, Special Feature: 264.Recent work has shown that the cardiac outflow tract of sharks and chimaeras does not consist of a single myocardial component, the conus arteriosus, as classically accepted, but two, namely, the myocardial conus arteriosus and the non-myocardial bulbus arteriosus. However, the anatomical composition of the outflow tract of the batoid hearts remains unknown. The present study was designed to fill this gap. The material examined consisted of hearts of two species of rays, namely, the Mediterranean starry ray (Raja asterias) and sandy ray (Leucoraja circularis). They were studied using scanning electron microscopy, and histochemical and inmunohistochemical
techniques. In both species, the outflow tract consists of two components, proximal and distal with regard to the ventricle. The proximal component is the conus arteriosus; it is characterized by the presence of compact
myocardium in its wall and several transverse rows of pocket-shaped valves at its luminal side. Each valve consists of a leaflet and its supporting sinus. Histologically, the leaflet has two fibrosas, inner and outer, and a middle coat, the
spongiosa. The distal component lacks myocardium. Its wall consists of smooth muscle cells, elastic fibers and collagen. Thus, it shows an arterial-like structure. However, it differs from the aorta because it is covered by the epicardium and crossed by coronary arteries. These findings indicate that the distal component is morphologically equivalent to the bulbus arteriosus of sharks and chimaeras. In contrast to foregoing descriptions, the valves of the
first transverse row are distally anchored to the bulbus arteriosus and not to the ventral aorta. Our findings give added support to the notion that presence of a bulbus arteriosus at the arterial pole of the heart is common to all
chondrichtyans, and not an apomorphy of actinopterygians as classically thought.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. CGL2014-52356-P, CEIMAR, BIO 203, FEDE
Celiotomía en una tortuga mora
En el presente trabajo se describe la técnica quirúrgica empleada para resolver una obstrucción de oviducto en una tortuga mora debido a una alteración ovulatoria.In this work it is described the surgical technique used to resolve an oviduct obstruction in a Greek tortoise (Testudo graeca) caused by the retention of eggs
Exploring wind direction and SO2 concentration by circular-linear density estimation
The study of environmental problems usually requires the description of
variables with different nature and the assessment of relations between them.
In this work, an algorithm for flexible estimation of the joint density for a
circular-linear variable is proposed. The method is applied for exploring the
relation between wind direction and SO2 concentration in a monitoring station
close to a power plant located in Galicia (NW-Spain), in order to compare the
effectiveness of precautionary measures for pollutants reduction in two
different years.Comment: 17 pages, 7 figures, 2 table
Structural analysis, magnetic and transport properties of the (Ru1-xCox)Sr2GdCu2O8 system
The effects of Co substitution on structural and superconducting properties
of RuSr2GdCu2O8 compound have been studied. Rietveld refinements of the X-ray
diffraction patterns indicate that the cobalt ion progressively replaces
ruthenium sites. This replacement induces significant changes on the crystal
structure and on the magnetic and superconducting properties. The effects Co
substitution on the superconducting behaviour, and more particulary on the
changes induce by the hole doping mechanism, were investigated in
(Ru1-xCox)Sr2GdCu2O8 by a "bond valence sum" analysis with Co content from x=
0.0 to x = 0.2. The weak ferromagnetic transition at Tm= 138.2 K is shifted to
lower temperature, and suppressed at higher Co content. From the
crystallographic point of view the Ru-O(1)-Cu bond angle, associated to the
rotation of the RuO6 octahedra, around the c-axis remain essetially constant
when Ru is substituted by Co. Furthermore, increasing Co content has the effect
to increase the weak ferromagnetic moment, which may be interpreted as the main
responsible for breaking the delicate balance between magnetic and
superconducting ordering.Comment: 21 pages, 8 figure
Descripción morfológica de una nueva anomalía arterial coronaria en el hamster sirio Mesocricetus auratus (Waterhouse, 1839): interpretaciones genéticas y filogenéticas
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