The Hox gene abdominal-A specifies heart cell fate in theDrosophila dorsal vessel

Development ◽  
2002 ◽  
Vol 129 (21) ◽  
pp. 5019-5027 ◽  
Author(s):  
TyAnna L. Lovato ◽  
Thiennga P. Nguyen ◽  
Marco R. Molina ◽  
Richard M. Cripps

The Drosophila melanogaster dorsal vessel is a linear organ that pumps blood through the body. Blood enters the dorsal vessel in a posterior chamber termed the heart, and is pumped in an anterior direction through a region of the dorsal vessel termed the aorta. Although the genes that specify dorsal vessel cell fate are well understood, there is still much to be learned concerning how cell fate in this linear tube is determined in an anteroposterior manner, either in Drosophila or in any other animal. We demonstrate that the formation of a morphologically and molecularly distinct heart depends crucially upon the homeotic segmentation geneabdominal-A (abd-A). abd-A expression in the dorsal vessel was detected only in the heart, and overexpression of abd-Ainduced heart fate in the aorta in a cell-autonomous manner. Mutation ofabd-A resulted in a loss of heart-specific markers. We also demonstrate that abd-A and sevenup co-expression in cardial cells defined the location of ostia, or inflow tracts. Other genes of theBithorax Complex do not appear to participate in heart specification,although high level expression of Ultrabithorax is capable of inducing a partial heart fate in the aorta. These findings for the first time demonstrate a specific involvement for Hox genes in patterning the muscular circulatory system, and suggest a mechanism of broad relevance for animal heart patterning.

Author(s):  
Mohan Yende ◽  
Sheetal Laxmanrao Thosar ◽  
Jayashree S Gohane

ABSTRACT  : The word kala has been used in many senses in vedic & other ancient literature , Kala Sharira is an important part of Ayurvedic anatomy. Kala was first time described by Sushruta. He has explained kala as a barrier between dhatu and its ashaya Vagbhata has then added embryological development that it is the  important physical and functional components of the body. They form a protective coating for the ashayas as well as boundary between the ashayas and dhatus. There are seven kala in the body, in which second kala is Raktadhara kala. Kala sharira (anatomy and physiology of kala) gives us information about the important membranes and layers of the body which take part in many important functions of the body. Acharyas of Ayurveda have described the Anatomy & Physiology of Raktadhara kala in very brief manner.It is explained that Raktadhara kala holds the Raktadhatu (Blood) & present especially in sira (vessels), yakrita (liver) & pleeha (speen) but which structure inside of them is responsible for Raktadhara kala is not clearly mentioned. Hridaya (Heart) is an important organ of blood circulatory system but it is not included as a specific site of Raktadhara kala. So for proper understanding, it is essential to correlate it with the modern science & elaborate in a proper way.


Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 318 ◽  
Author(s):  
Markus Wolfien ◽  
Anne-Marie Galow ◽  
Paula Müller ◽  
Madeleine Bartsch ◽  
Ronald M. Brunner ◽  
...  

Analyses on the cellular level are indispensable to expand our understanding of complex tissues like the mammalian heart. Single-nucleus sequencing (snRNA-seq) allows for the exploration of cellular composition and cell features without major hurdles of single-cell sequencing. We used snRNA-seq to investigate for the first time an entire adult mammalian heart. Single-nucleus quantification and clustering led to an accurate representation of cell types, revealing 24 distinct clusters with endothelial cells (28.8%), fibroblasts (25.3%), and cardiomyocytes (22.8%) constituting the major cell populations. An additional RNA velocity analysis allowed us to study transcription kinetics and was utilized to visualize the transitions between mature and nascent cellular states of the cell types. We identified subgroups of cardiomyocytes with distinct marker profiles. For example, the expression of Hand2os1 distinguished immature cardiomyocytes from differentiated cardiomyocyte populations. Moreover, we found a cell population that comprises endothelial markers as well as markers clearly related to cardiomyocyte function. Our velocity data support the idea that this population is in a trans-differentiation process from an endothelial cell-like phenotype towards a cardiomyocyte-like phenotype. In summary, we present the first report of sequencing an entire adult mammalian heart, providing realistic cell-type distributions combined with RNA velocity kinetics hinting at interrelations.


1988 ◽  
Vol 134 (1) ◽  
pp. 235-246 ◽  
Author(s):  
JAN-PETER HILDEBRANDT

In the leech, the physiological significance of high-pressure phases (HIP) and lowpressure phases (LOP) of the lateral vessels was studied by intravascular pressure recordings and observation of blood flow in different parts of the circulatory system, and by measurements of the blood flow velocities in the dorsal vessel. Different shapes of the pressure pulses were found in the anterior lateral vessel segments during HIP and LOP phases, according to the different modes of diastolic filling in both phases. Pressure recordings in the lateral abdominal vessels showed the different action of the lateral abdominal sphincters in the HIP and LOP phases of the ipsilateral lateral vessel. The LOP contractions were responsible for the blood supply to the capillary networks of the organs and the body wall, with the possible exception of the intestine. The HIP contractions caused a forward bloodflow within the lateral vessel. In the dorsal vessel, the blood pressure was about 0.9-1.9kPa in different animals. The blood flow was discontinuous with velocities of 0.5-10 mms−1. Average blood flow in the dorsal vessel was 22.9μl min−1. An improved model of the circulation in the leech is presented.


1956 ◽  
Vol s3-97 (38) ◽  
pp. 235-249
Author(s):  
R. B. CLARK

The four longitudinal vessels of the circulatory system of Nephtys californiensis are dorsal, sub-intestinal, and neural, the latter being paired. There is a complete longitudinal circulation; the dorsal vessel communicates with the sub-intestinal by way of the proboscidial circulation and with the neural by way of the circum-oral vessels. In each middle and posterior segment segmental vessels from each of the longitudinal trunks carry blood to and from the parapodia and body-wall. The segmental circulation is completed by a circum-intestinal vessel connecting the dorsal and subintestinal vessels in each segment and an intersegmental branch connecting the dorsal and sub-intestinal segmental vessels. A trans-septal branch of the neural segmental vessel communicates with the sub-intestinal segmental vessel. This arrangement is modified in anterior segments which house the muscular, eversible pharynx, and no blood-vessels cross the coelom except by running through the body-wall. On anatomical grounds and by comparison with other polychaetes it seems likely that segmental is subordinate to longitudinal circulation. There are no endothelial capillaries such as have been described in some other polychaetes; instead there are numerous blindending vessels the walls of which are composed of the same three layers as other vessels and which are probably contractile. The dorsal vessel, where it is in contact with the ventral surface of the supra-oesophageal ganglion, forms a plexus in close association with a modified part of the brain capsule and a special axonal tract within the ganglion. It is thought that by way of this ‘cerebro-vascular complex’, hormones produced in the neurosecretory cells of the brain pass into the blood-stream.


Cell Cycle ◽  
2005 ◽  
Vol 4 (3) ◽  
pp. 422-425 ◽  
Author(s):  
Christian Berger ◽  
S.K. Pallavi ◽  
Mohit Prasad ◽  
L.S. Shashidhara ◽  
Gerhard M. Technau

1998 ◽  
Vol 72 (5) ◽  
pp. 894-906 ◽  
Author(s):  
Thomas M. Lehman

An exceptionally large skeleton of Pentaceratops sternbergi (Ornithischia:Ceratopsia) provides for the first time an accurate impression of the body proportions in this horned dinosaur. This is the only known specimen with a skull associated with most of the postcranial skeleton. The restored skull is nearly three meters in length and is thus the largest of any ceratopsian and the largest skull thus far known in any terrestrial vertebrate. The elongate rostrum, elaborate premaxillary structure, and complex frontal and cornual sinuses demonstrate a high level of intraspecific variability in these features. Such features are therefore likely not useful in providing species-level discrimination in other chasmosaurines. The function of the intricate chasmosaurine premaxillary narial structures is probably associated with an advanced level of herbivory.


Author(s):  
Javier TAJADURA TEJADA

LABURPENA: Lan honetan, Konstituzioa defendatzeko organo bat osatzearen beharrari buruz Sieyès apaizak egindako hausnarketak azaldu dira. Sieyès botere eratzailearen eta botere eratuen arteko bereizketaren —hortaz, konstituzionalismo garaikidearen— sortzaile intelektuala izan zen. Konstituzioa aldatzeko prozedura berezia ezartzeko beharra defendatzeaz gain —alderdi hori nabarmendu zuten beste idazle batzuek—, Konstituzioa defendatzeko organoa ere diseinatu zuen. Frantziako Iraultzan, Frejúsko apaizak soilik eman zuen horren berri. Konstituzioa defendatzeko organoa bere eredu politikoaren giltzarria da, baita botere eratzailea kontzeptuaren ondorio logikoa ere, botere horrek sortutako estatu konstituzionalaren oinarria delako. Behar hori Thermidorren 2an esandako hitzaldi garrantzitsu batean azaldu zuen lehen aldiz. Handik bi astera, III. urteko Thermidorren 18an, ideia bera garatu zuen Konbentzio Nazionalean eman zuen beste hitzaldi batean. Sieyèsek Konstituzioa nahitaez bete beharreko arau juridiko loteslea izateko «Konstituzioaren zaindari» bat sortu behar zela planteatu zuen. Sieyès izan zen magistratura horren oinarrizko diseinua egiten lehena, zehaztasun tekniko eta xehetasun maila handiekin, bai osaerari bai funtzioei zegokienez. Eta egun Europako Zuzenbide Konstituzionalaren ondare diren ideia asko aurreratu zituen. Nabarmentzekoa da Justizia Konstituzionala sortu zuela, hainbat helbururekin: gutxiengoak babesteko instituzioa, politika integratzeko organoa, konstituzioarekin lotutako gatazkak ebazteko instantzia gorena eta askatasun jurisdikzioa izatea. RESUMEN: En este trabajo se exponen las reflexiones del abate Sieyès sobre la necesidad de configurar un órgano de defensa de la Constitución. Sieyès —creador intelectual de la distinción entre Poder Constituyente y poderes constituidos, y uno de los fundadores, por tanto, del constitucionalismo contemporáneo— no sólo defendió siempre la necesidad de establecer un procedimiento especial de reforma de la Constitución —aspecto este que fue destacado por otros autores— sino que llevó a cabo también el diseño de un órgano de defensa de la Constitución. En el contexto revolucionario francés, el abate de Frejús fue el único en advertirlo. El órgano de defensa de la Constitución se configura como la clave de bóveda de su modelo político y el corolario lógico del concepto de Poder Constituyente, como fundamento del Estado Constitucional, por él alumbrado. Esta necesidad la advirtió por vez primera en un importante discurso pronunciado el 2 de Termidor. Dos semanas después desarrolló su idea en otro discurso proferido en la Convención Nacional, concretamente el 18 de Thermidor del año III. En él, Sieyès se plantea la necesidad de crear un «guardián de la Constitución» para que esta pueda configurarse como una norma jurídica vinculante, y de obligatorio cumplimiento. Sieyès fue el primero en establecer con gran rigor técnico, y con un muy elevado nivel de detalle, el diseño básico de esa magistratura, tanto en lo que se refiere a su composición como a sus funciones. Y lo hizo anticipándose a muchas ideas que son hoy patrimonio común del Derecho Constitucional europeo. Entre ellas cabe destacar la configuración de la Justicia Constitucional como una institución protectora de las minorías, como un órgano de integración política, como la suprema instancia jurídico-política para la resolución de los conflictos constitucionales, y como una jurisdicción de la libertad. ABSTRACT: This work sets forth the critical thoughts of the Abate Sièyes regarding the need to set up a body for the protection of the Constitution. Sièyes —the intelectual author of the distinction between constituent power and constituted power, and one of the fathers of the contemporary constitutionalism—, did not only stand up for the need to establish a special procedure for the reform of the Constitution —a facet which was emphasyzed by another authors— but also he carried out the design of a body for the defense of the Constitution. In the framework of the revolutionary french context, the Abate from Frejús was the only one to notice it. The body for the defense of the Constitution was envisaged as the cornerstone of his political model and the logic corollary of the notion of constituent power, as the basis for the Constitutional state figured out by him. This necessity was notized for the first time in an important speech pronounced the 2 of Thermidor. Two weeks later, he developed his idea in another speech issued before the National Convention, specifically the 18 of Thermidor of the third year. Sièyes sets the need to establish a «guardian for the Constitution» in order to become a binding legal rule of compulsory observance. Sièyes is the firt one to establish with great technical rigour and with a high level of details, the basic design of that court both regarding its membership and its tasks. And he did it so foreseeing many ideas which are nowadays common ground for the European Constitutional law. Among them it can be emphasyzed the configuration of constitutional justice as a protective institution for minorities, as a body of political integration, as the supreme instance for the resolution of constitutional conflicts and as a jurisdicition for freedom.


Development ◽  
1999 ◽  
Vol 126 (10) ◽  
pp. 2261-2272 ◽  
Author(s):  
J. Kavaler ◽  
W. Fu ◽  
H. Duan ◽  
M. Noll ◽  
J.W. Posakony

The adult peripheral nervous system of Drosophila includes a complex array of mechanosensory organs (bristles) that cover much of the body surface of the fly. The four cells (shaft, socket, sheath, and neuron) which compose each of these organs adopt distinct fates as a result of cell-cell signaling via the Notch (N) pathway. However, the specific mechanisms by which these cells execute their conferred fates are not well understood. Here we show that D-Pax2, the Drosophila homolog of the vertebrate Pax2 gene, has an essential role in the differentiation of the shaft cell. In flies bearing strong loss-of-function mutations in the shaven function of D-Pax2, shaft structures specifically fail to develop. Consistent with this, we find that D-Pax2 protein is expressed in all cells of the bristle lineage during the mitotic (cell fate specification) phase of bristle development, but becomes sharply restricted to the shaft and sheath cells in the post-mitotic (differentiative) phase. Two lines of evidence described here indicate that D-Pax2 expression and function is at least in part downstream of cell fate specification mechanisms such as N signaling. First, we find that the lack of late D-Pax2 expression in the socket cell (the sister of the shaft cell) is controlled by N pathway activity; second, we find that loss of D-Pax2 function is epistatic to the socket-to-shaft cell fate transformation caused by reduced N signaling. Finally, we show that misexpression of D-Pax2 is sufficient to induce the production of ectopic shaft structures. From these results, we propose that D-Pax2 is a high-level transcriptional regulator of the shaft cell differentiation program, and acts downstream of the N signaling pathway as a specific link between cell fate determination and cell differentiation in the bristle lineage.


Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1095-1101 ◽  
Author(s):  
G.N. Serbedzija ◽  
J.N. Chen ◽  
M.C. Fishman

In many vertebrates, removal of early embryonic heart precursors can be repaired, leaving the heart and embryo without visible deficit. One possibility is that this ‘regulation’ involves a cell fate switch whereby cells, perhaps in regions surrounding normal progenitors, are redirected to the heart cell fate. However, the lineage and spatial relationships between cells that are normal heart progenitors and those that can assume that role after injury are not known, nor are their molecular distinctions. We have adapted a laser-activated technique to label single or small patches of cells in the lateral plate mesoderm of the zebrafish and to track their subsequent lineage. We find that the heart precursor cells are clustered in a region adjacent to the prechordal plate, just anterior to the notochord tip. Complete unilateral ablation of all heart precursors with a laser does not disrupt heart development, if performed before the 18-somite stage. By combining extirpation of the heart precursors with cell labeling, we find that cells anterior to the normal cardiogenic compartments constitute the source of regulatory cells that compensate for the loss of the progenitors. One of the earliest embryonic markers of the premyocardial cells is the divergent homeodomain gene, Nkx2.5. Interestingly, normal cardiogenic progenitors derive from only the anterior half of the Nkx2.5-expressing region in the lateral plate mesoderm. The posterior half, adjacent to the notochord, does not include cardiac progenitors and the posterior Nkx2.5-expressing cells do not contribute to the heart, even after ablation of the normal cardiogenic region. The cells that can acquire a cardiac cell fate after injury to the normal progenitors also reside near the prechordal plate, but anterior to the Nkx2.5-expressing domain. Normally they give rise to head mesenchyme. They share with cardiac progenitors early expression of GATA 4. The location of the different elements of the cardiac field, and their response to injury, suggests that the prechordal plate supports and/or the notochord suppresses the cardiac fate.


2008 ◽  
Vol 1 (2) ◽  
pp. 139-155 ◽  
Author(s):  
YAEL DARR

This article describes a crucial and fundamental stage in the transformation of Hebrew children's literature, during the late 1930s and 1940s, from a single channel of expression to a multi-layered polyphony of models and voices. It claims that for the first time in the history of Hebrew children's literature there took place a doctrinal confrontation between two groups of taste-makers. The article outlines the pedagogical and ideological designs of traditionalist Zionist educators, and suggests how these were challenged by a group of prominent writers of adult poetry, members of the Modernist movement. These writers, it is argued, advocated autonomous literary creation, and insisted on a high level of literary quality. Their intervention not only dramatically changed the repertoire of Hebrew children's literature, but also the rules of literary discourse. The article suggests that, through the Modernists’ polemical efforts, Hebrew children's literature was able to free itself from its position as an apparatus controlled by the political-educational system and to become a dynamic and multi-layered field.


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