scholarly journals Origins and patterning of avian outflow tract endocardium

Development ◽  
1991 ◽  
Vol 111 (4) ◽  
pp. 867-876 ◽  
Author(s):  
D.M. Noden
Keyword(s):  
Outflow Tract ◽  
Avian Embryo ◽  
Endocardial Cushions ◽  
Head Mesoderm ◽  
Developing Heart ◽  
History Of ◽  
Otic Placode ◽  
Species Specific ◽  
Antibodies Monoclonal ◽  
Lateral Mesoderm

Outflow tract endocardium links the atrioventricular lining, which develops from cardiogenic plate mesoderm, with aortic arches, whose lining forms collectively from splanchnopleuric endothelial channels, local endothelial vesicles, and invasive angioblasts. At two discrete sites, outflow tract endocardial cells participate in morphogenetic events not within the repertoire of neighboring endocardium: they form mesenchymal precursors of endocardial cushions. The objectives of this research were to document the history of outflow tract endocardium in the avian embryo immediately prior to development of the heart, and to ascertain which, if any, aspects of this history are necessary to acquire cushion-forming potential. Paraxial and lateral mesodermal tissues from between somitomere 3 (midbrain level) and somite 5 were grafted from quail into chick embryos at 3–10 somite stages and, after 2–5 days incubation, survivors were fixed and sectioned. Tissues were stained with the Feulgen reaction to visualize the quail nuclear marker or with antibodies (monoclonal QH1 or polyclonals) that recognize quail but not chick cells. Many quail endothelial cells lose the characteristic nuclear heterochromatin marker, but they retain the species-specific epitope recognized by these antibodies. Precursors of outflow tract but not atrioventricular endocardium are present in cephalic paraxial and lateral mesoderm, with their greatest concentration at the level of the otic placode. Furthermore, the ventral movement of individual angiogenic cells is a normal antecedent to outflow tract formation. Cardiac myocytes were never derived from grafted head mesoderm. Thus, unlike the atrioventricular regions of the heart, outflow tract endocardial and myocardial precursors do not share a congruent embryonic history. The results of heterotopic transplantation, in which trunk paraxial or lateral mesoderm was grafted into the head, were identical, including the formation of cushion mesenchyme. This means that cushion positioning and inductive influences must operate locally within the developing heart tubes.

Elevated transforming growth factor β2 enhances apoptosis and contributes to abnormal outflow tract and aortic sac development in retinoic X receptor α knockout embryos

Development ◽  
2002 ◽  
Vol 129 (3) ◽  
pp. 733-746
Author(s):  
Steven W. Kubalak ◽  
D. Reneé Hutson ◽  
Karen K. Scott ◽  
Rebecca A. Shannon
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Qualitative Difference ◽  
Outflow Tract ◽  
Brdu Incorporation ◽  
Wild Type ◽  
Endocardial Cushions ◽  
Precise Integration ◽  
Partial Restoration ◽  
Transforming Growth Factor Β2

Septation of the single tubular embryonic outflow tract into two outlet segments in the heart requires the precise integration of proliferation, differentiation and apoptosis during remodeling. Lack of proper coordination between these processes would result in a variety of congenital cardiac defects such as those seen in the retinoid X receptor α knockout (Rxra–/–) mouse. Rxra–/– embryos exhibit lethality between embryonic day (E) 13.5 and 15.5 and harbor a variety of conotruncal and aortic sac defects making it an excellent system to investigate the molecular and morphogenic causes of these cardiac malformations. At E12.5, before the embryonic lethality, we found no qualitative difference between wild type and Rxra–/– proliferation (BrdU incorporation) in outflow tract cushion tissue but a significant increase in apoptosis as assessed by both TUNEL labeling in paraffin sections and caspase activity in trypsin-dispersed hearts. Additionally, E12.5 embryos demonstrated elevated levels of transforming growth factor β2 (TGFβ2) protein in multiple cell lineages in the heart. Using a whole-mouse-embryo culture system, wild-type E11.5 embryos treated with TGFβ2 protein for 24 hours displayed enhanced apoptosis in both the sinistroventralconal cushion and dextrodorsalconal cushion in a manner analogous to that observed in the Rxra–/–. TGFβ2 protein treatment also led to malformations in both the outflow tract and aortic sac. Importantly, Rxra–/– embryos that were heterozygous for a null mutation in the Tgfb2 allele exhibited a partial restoration of the elevated apoptosis and of the malformations. This was evident at both E12.5 and E13.5. The data suggests that elevated levels of TGFβ2 can (1) contribute to abnormal outflow tract morphogenesis by enhancing apoptosis in the endocardial cushions and (2) promote aortic sac malformations by interfering with the normal development of the aorticopulmonary septum.

scholarly journals The taxonomic history of Indo-Papuan groundsnakes, genus Stegonotus Duméril et al., 1854 (Colubridae), with some taxonomic revisions and the designation of a neotype for S. parvus (Meyer, 1874)

Zootaxa ◽  
2018 ◽  
Vol 4512 (1) ◽  
pp. 1
Author(s):  
CHRISTINE M. KAISER ◽  
HINRICH KAISER ◽  
MARK O’SHEA
Keyword(s):  
New Guinea ◽  
Molecular Data ◽  
The Philippines ◽  
Morphological Data ◽  
Valid Species ◽  
Museum Specimens ◽  
Type Specimens ◽  
History Of ◽  
Original Species ◽  
Species Specific

Since its conceptualization in 1854, 29 species of the colubrid genus Stegonotus have been recognized or described, of which 15 (admiraltiensis, batjanensis, borneensis, cucullatus, derooijae, diehli, florensis, guentheri, iridis, heterurus, melanolabiatus, modestus, muelleri, parvus, poechi) are still considered valid today. Original species descriptions for the members of this genus were published in Dutch, English, French, German, and Italian and, perhaps as a consequence of these polyglot origins, there has been a considerable amount of confusion over which species names should be applied to which populations of Stegonotus throughout its range across Borneo, the Philippines, Wallacea, New Guinea, Australia, and associated archipelagos. In addition, the terminology used to notate characteristics in the descriptions of these forms was not uniform and may have added to the taxonomic confusion. In this paper, we trace in detail the history of the type specimens, the species, and the synonyms currently associated with the genus Stegonotus and provide a basic, species-specific listing of their characteristics, derived from our examination of over 1500 museum specimens. Based on our data, we are able to limit the distribution of S. modestus to the islands of Ambon, Buru, and Seram in the central Moluccas of Indonesian Wallacea. We correct the type locality of S. cucullatus to the Manokwari area on the Bird’s Head Peninsula of West Papua, Indonesian New Guinea and designate a neotype for S. parvus, a species likely to be a regional endemic in the Schouten Archipelago of Cenderawasih Bay (formerly Geelvink Bay), Indonesian New Guinea. We unequivocally identify and explain the problematic localities of the type specimens of S. muelleri and Lycodon muelleri, which currently reside in the same specimen jar. We remove L. aruensis and L. lividum from the synonymy of S. modestus and recognize them as S. aruensis n. comb. and S. lividus n. comb., respectively. We remove S. keyensis and Zamenophis australis from the synonymy of S. cucullatus and recognize them as S. keyensis n. comb. and S. australis n. comb., respectively. We further remove S. reticulatus from the synonymy of S. cucullatus, S. dorsalis from the synonymy of S. diehli, and S. sutteri from the synonymy of S. florensis. We designate lectotypes for S. guentheri, S. heterurus, S. lividus, and S. reticulatus. Lastly, we introduce S. poechi, a valid species not mentioned in the scientific literature since its description in 1924. This brings the diversity in the genus Stegonotus to 22 species. We also caution that in a complex group of organisms like Stegonotus any rush to taxonomic judgment on the basis of molecular and incomplete morphological data sets may perpetuate errors and introduce incongruities. Only through the careful work of connecting type material with museum specimens and molecular data can the taxonomy and nomenclature of complex taxa be stabilized. 

scholarly journals Effect of NaCl on seed germination in some Centaurium Hill. Species (Gentianaceae)

2007 ◽  
Vol 59 (3) ◽  
pp. 227-231 ◽  
Author(s):  
S. Zivkovic ◽  
M. Devic ◽  
B. Filipovic ◽  
Z. Giba ◽  
D. Grubisic
Keyword(s):  
Life History ◽  
Salt Tolerance ◽  
Seed Germination ◽  
Gibberellic Acid ◽  
White Light ◽  
The Other ◽  
Distilled Water ◽  
Nacl Concentration ◽  
History Of ◽  
Species Specific

The influence of high NaCl concentrations on seed germination in both light and darkness was examined in the species Centaurium pulchellum, C. erythraea, C. littorale, C. spicatum, and C. tenuiflorum. Salt tolerance was found to depend on the life history of the seeds. To be specific, seeds of all five species failed to complete germination when exposed to continuous white light if kept all the time in the presence of 100-200 mM and greater NaCl concentrations. However, when after two weeks NaCl was rinsed from the seeds and the seeds were left in distilled water under white light for an additional two weeks, all species completed germination to a certain extent. The percent of germination not only depended on NaCl concentration in the prior medium, but was also species specific. Thus, seeds of C. pulchellum, C. erythraea, and C. littorale completed germination well almost irrespective of the salt concentration previously experienced. On the other hand, seeds of C. tenuiflorum completed germination poorly if NaCl concentrations in the prior media were greater than 200 mM. When seeds after washing were transferred to darkness for an additional 14 days, they failed to complete germination if previously imbibed on media containing NaCl concentrations greater than 400 mM. However, the seeds of all species, even if previously imbibed at 800 mM NaCl, could be induced to complete germination in darkness by 1 mM gibberellic acid. .

Pax3 is required for cardiac neural crest migration in the mouse: evidence from the splotch (Sp2H) mutant

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 505-514 ◽  
Author(s):  
S.J. Conway ◽  
D.J. Henderson ◽  
A.J. Copp
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Neural Crest Cells ◽  
Outflow Tract ◽  
Avian Embryo ◽  
Cardiac Neural Crest ◽  
Branchial Arches ◽  
Aortic Arches ◽  
Cardiac Outflow

Neural crest cells originating in the occipital region of the avian embryo are known to play a vital role in formation of the septum of the cardiac outflow tract and to contribute cells to the aortic arches, thymus, thyroid and parathyroids. This ‘cardiac’ neural crest sub-population is assumed to exist in mammals, but without direct evidence. In this paper we demonstrate, using RT-PCR and in situ hybridisation, that Pax3 expression can serve as a marker of cardiac neural crest cells in the mouse embryo. Cells of this lineage were traced from the occipital neural tube, via branchial arches 3, 4 and 6, into the aortic sac and aorto-pulmonary outflow tract. Confirmation that these Pax3-positive cells are indeed cardiac neural crest is provided by experiments in which hearts were deprived of a source of colonising neural crest, by organ culture in vitro, with consequent lack of up-regulation of Pax3. Occipital neural crest cell outgrowths in vitro were also shown to express Pax3. Mutation of Pax3, as occurs in the splotch (Sp2H) mouse, results in development of conotruncal heart defects including persistent truncus arteriosus. Homozygotes also exhibit defects of the aortic arches, thymus, thyroid and parathyroids. Pax3-positive neural crest cells were found to emigrate from the occipital neural tube of Sp2H/Sp2H embryos in a relatively normal fashion, but there was a marked deficiency or absence of neural crest cells traversing branchial arches 3, 4 and 6, and entering the cardiac outflow tract. This decreased expression of Pax3 in Sp2H/Sp2H embryos was not due to down-regulation of Pax3 in neural crest cells, as use of independent neural crest markers, Hoxa-3, CrabpI, Prx1, Prx2 and c-met also revealed a deficiency of migrating cardiac neural crest cells in homozygous embryos. This work demonstrates the essential role of the cardiac neural crest in formation of the heart and great vessels in the mouse and, furthermore, shows that Pax3 function is required for the cardiac neural crest to complete its migration to the developing heart.

scholarly journals Blooms of Toxic Cyanobacterium Nodularia spumigena in Norwegian Fjords During Holocene Warm Periods

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 257
Author(s):  
Robert Konkel ◽  
Anna Toruńska-Sitarz ◽  
Marta Cegłowska ◽  
Žilvinas Ežerinskis ◽  
Justina Šapolaitė ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Phytoplankton Community ◽  
Sediment Cores ◽  
Specific Chemical ◽  
Nodularia Spumigena ◽  
History Of ◽  
Recent Sediments ◽  
Species Specific ◽  
Ecosystem Changes ◽  
Deep Sediments

In paleoecological studies, molecular markers are being used increasingly often to reconstruct community structures, environmental conditions and ecosystem changes. In this work, nodularin, anabaenopeptins and selected DNA sequences were applied as Nodularia spumigena markers to reconstruct the history of the cyanobacterium in the Norwegian fjords. For the purpose of this study, three sediment cores collected in Oslofjorden, Trondheimsfjorden and Balsfjorden were analyzed. The lack of nodularin in most recent sediments is consistent with the fact that only one report on the sporadic occurrence and low amounts of the cyanobacterium in Norwegian Fjords in 1976 has been published. However, analyses of species-specific chemical markers in deep sediments showed that thousands of years ago, N. spumigena constituted an important component of the phytoplankton community. The content of the markers in the cores indicated that the biomass of the cyanobacterium increased during the warmer Holocene periods. The analyses of genetic markers were less conclusive; they showed the occurrence of microcystin/nodularin producing cyanobacteria of Nostocales order, but they did not allow for the identification of the organisms at a species level.

scholarly journals Vertebrate Alpha2,8-Sialyltransferases (ST8Sia): A Teleost Perspective

2020 ◽  
Vol 21 (2) ◽  
pp. 513 ◽  
Author(s):  
Marzia Tindara Venuto ◽  
Mathieu Decloquement ◽  
Joan Martorell Ribera ◽  
Maxence Noel ◽  
Alexander Rebl ◽  
...  
Keyword(s):  
Fish Species ◽  
Evolutionary History ◽  
Recombinant Enzymes ◽  
Sequence Alignments ◽  
Multiple Sequence ◽  
Multiple Sequence Alignments ◽  
Functional Studies ◽  
Genome Duplications ◽  
History Of ◽  
Species Specific

We identified and analyzed α2,8-sialyltransferases sequences among 71 ray-finned fish species to provide the first comprehensive view of the Teleost ST8Sia repertoire. This repertoire expanded over the course of Vertebrate evolution and was primarily shaped by the whole genome events R1 and R2, but not by the Teleost-specific R3. We showed that duplicated st8sia genes like st8sia7, st8sia8, and st8sia9 have disappeared from Tetrapods, whereas their orthologues were maintained in Teleosts. Furthermore, several fish species specific genome duplications account for the presence of multiple poly-α2,8-sialyltransferases in the Salmonidae (ST8Sia II-r1 and ST8Sia II-r2) and in Cyprinus carpio (ST8Sia IV-r1 and ST8Sia IV-r2). Paralogy and synteny analyses provided more relevant and solid information that enabled us to reconstruct the evolutionary history of st8sia genes in fish genomes. Our data also indicated that, while the mammalian ST8Sia family is comprised of six subfamilies forming di-, oligo-, or polymers of α2,8-linked sialic acids, the fish ST8Sia family, amounting to a total of 10 genes in fish, appears to be much more diverse and shows a patchy distribution among fish species. A focus on Salmonidae showed that (i) the two copies of st8sia2 genes have overall contrasted tissue-specific expressions, with noticeable changes when compared with human co-orthologue, and that (ii) st8sia4 is weakly expressed. Multiple sequence alignments enabled us to detect changes in the conserved polysialyltransferase domain (PSTD) of the fish sequences that could account for variable enzymatic activities. These data provide the bases for further functional studies using recombinant enzymes.

scholarly journals Left Ventricular Outflow Tract Pseudoaneurysm after Aortic Valve Replacement

Aorta ◽  
2015 ◽  
Vol 03 (05) ◽  
pp. 167-171 ◽  
Author(s):  
Masood Shariff ◽  
Daniel Martingano ◽  
Usman Khan ◽  
Nikhil Goyal ◽  
Raman Sharma ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Valve Replacement ◽  
Left Ventricular Outflow Tract ◽  
Ventricular Outflow Tract ◽  
Left Ventricular ◽  
Outflow Tract ◽  
Lower Extremity Weakness ◽  
Left Ventricular Outflow ◽  
History Of

AbstractLeft ventricular outflow tract pseudoaneurysm is an uncommon complication following aortic valve replacement (AVR), occurring most frequently secondary to endocarditis. We present a case of a 47-year-old female with a history of intravenous drug abuse and a past surgical history of two AVRs (2001 and 2009 with aortic root replacement for endocarditis) who presented with symptoms of lower extremity weakness. Subsequent radiologic imaging revealed the presence of a left ventricular outflow tract pseudoaneurysm, which was surgically managed with a homologous conduit.

A revision of Australia' s hammer orchids (Drakaea: Orchidaceae), with some field data on species-specific sexually deceived wasp pollinators

2007 ◽  
Vol 20 (3) ◽  
pp. 252 ◽  
Author(s):  
Stephen D. Hopper ◽  
Andrew P. Brown
Keyword(s):  
Field Data ◽  
Wildlife Conservation ◽  
Conservation Status ◽  
Environment Protection ◽  
Sexual Deception ◽  
Molecular Phylogenetic ◽  
History Of ◽  
Species Specific ◽  
Unique Part ◽  
Western Australian

Drakaea Lindley, 1840 is a genus of 10 species of geophytic orchids endemic to the South-west Australian Floristic Region. The genus is renowned for its morphological and chemical adaptations, achieving pollination by sexual deception of male thynnid wasps. The history of taxa in Drakaea has been one of dispute and confusion right to the present day. Here we provide a revision of the genus, the first made by using modern collections and field data, formalising names for undescribed taxa featured by Hoffman and Brown (1992, 1998), several of which are threatened with extinction. We describe six new species: D. andrewsiae, D. concolor, D. confluens, D. gracilis, D. isolata and D. micrantha. Experimental baiting of male wasps has helped show the specific status of some of these new taxa. Molecular phylogenetic research is needed to clarify relationships and patterns of speciation in the genus. Five of the 10 Drakaea species are legally protected under the Western Australian Wildlife Conservation Act and the Commonwealth Environment Protection and Biodiversity Conservation Act, signalling the ongoing need for research and management to ensure the conservation of this unique part of Australia’s orchid heritage. D. andrewsiae has been recorded only three times from the Gnowangerup–Tunney district. Urgent surveys are needed to establish its conservation status.

Regulation of apoptosis in the endocardial cushions of the developing chick heart

2002 ◽  
Vol 282 (6) ◽  
pp. C1348-C1360 ◽  
Author(s):  
William M. Keyes ◽  
Esmond J. Sanders
Keyword(s):  
Heart Development ◽  
Time Course ◽  
Nuclear Staining ◽  
Caspase 9 ◽  
Endocardial Cushions ◽  
Similar Time ◽  
Cleavage Fragment ◽  
Protein Levels ◽  
Developing Heart

During the early stages of heart development, there are two main foci of cell death: outflow tract (OT) and atrioventricular (AV) endocardial cushions. These tissues contribute to the septa and valves of the mature heart and receive cell populations from neural crest (NC) cell migration and epicardial cell invasion. We examined embryonic chick hearts for expression, in the cushions, of bcl-2 family members, caspase-9, and the caspase substrate poly(ADP-ribose) polymerase. Antiapoptotic bcl-2 is expressed heavily in the OT and AV regions throughout embryonic days (ED) 4–7, with a decrease in levels at ED 4 and 5 in OT and AV cushions, respectively. Proapoptotic bax predominantly associated with the prongs of the NC-derived aorticopulmonary (AP) septum but was expressed throughout the AV cushions. Proapoptotic bak also associated with the prongs of the AP septum in the OT, while protein levels were upregulated at ED 4–5 and 4–6 in OT and AV cushions, respectively. Bid expression showed a similar time course. We found the 10-kDa cleavage fragment of active caspase-9 at ED 4–8 and 5–8 in OT and AV cushions, respectively, and the 24-kDa cleavage fragment of poly(ADP-ribose) polymerase throughout ED 3–8 and 7–8 in OT and AV cushions, respectively. Caspase-3 cleavage occurred throughout the time period examined. Using cushion cell cultures, we found that inhibitors of caspases-3 and -9 and a universal caspase inhibitor significantly reduced apoptosis, as did retroviral overexpression of bcl-2 using an RCAS expression vector. Premigratory NC cells were fluorescently labeled in vivo with 1,1-didodecyl-3,3,3′,3′-tetramethylindocarbocyanine. Subsequent nuclear staining of cushion cells with 4,6-diamidino-2-phenylindole revealed the presence of apoptotic nuclei in the NC cells in the OT cushions and in the prongs of the AP septum. These results demonstrate a developmentally regulated role for the bcl-2 and the caspase families of molecules in the endocardial cushions of the developing heart and lend support to the possibility that some of the dying cells in the cushions are derived from the NC.

Cell Death in the Endocardial Cushions of the Developing Heart

1999 ◽  
Vol 31 (5) ◽  
pp. 1015-1023 ◽  
Author(s):  
William M. Keyes ◽  
Esmond J. Sanders
Keyword(s):  
Cell Death ◽  
Endocardial Cushions ◽  
Developing Heart
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