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Jean M.p. Joss - One of the best experts on this subject based on the ideXlab platform.
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Developmental Endocrinology of the Dipnoan, Neoceratodus forsteri1
2015Co-Authors: Jean M.p. Joss, Sylvia P. Rajasekar, Ashni R. Raj-prasad, Klrsty RuitenbergAbstract:SYNOPSIS. The development of the pineal, pituitary and thyroid glands of the ex-tant lungfish, Neoceratodus forsteri, are being studied both morphologically and functionally. This paper presents data from hatching to 40-52 weeks for a stan-dardised series of lungfish, bred at Macquarie University. At hatching, the pineal comprises a single organ attached to the roof of the diencephalon, with well-de-veloped photoreceptor, supporting and ganglion cells. The photoreceptors gradu-ally degenerate, giving way to secretory cells which contain electron dense gran-ules. These latter are immunoreactive to melatonin antibodies and digestable with protease. The pituitary at hatching comprises a hollow ball of cells lying beneath the infundibular region of the hypothalamus. Ultrastructurally, four cell types can be distinguished by cytoplasmic granule size after the first four weeks of devel-opment posthatching. By 20 weeks, a further three cell types are recognisable. Inununogold labelling has identified corticotropes and melanotropes at four weeks and, at 20 weeks, prolactin cells, thyrotropes and somatotropes also can be iden-tified. The thyroid is only just apparent at hatching, containing 2-3 follicles. Th
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functional analyses of lymphocytes and granulocytes isolated from the thymus spiral valve intestine spleen and kidney of juvenile australian lungfish Neoceratodus forsteri
Fish & Shellfish Immunology, 2013Co-Authors: Jean M.p. Joss, Masoud Hassanpour, Mohammad G MohammadAbstract:Abstract Our current understanding of the lungfish immune system is limited. This study is characterizing the immune cells separated from primary and secondary immune organs of the Australian lungfish, Neoceratodus forsteri . Our functional studies utilized flow cytometry to study the immune cells extracted from the thymus, spiral valve intestine, spleen, and kidney. The different characteristics of lymphocytes and granulocytes were analyzed by utilization of viability, phagocytosis, oxidative burst, and apoptosis assays. Most of the nonviable intestinal cells were lymphocytes. Depending on the organ, 6–25% of the total population, predominantly granulocytes, underwent phagocytosis where the splenic cells were the most and intestinal cells the least phagocytic cells. Cells responded positively but differently to stimulation with phorbol myristate acetate (PMA) to produce radical oxygen species, an indication of their oxidative burst activity, which was mainly associated with granulocytes. Although cells were induced by dexamethasone to undergo apoptosis, such an induction did not follow a consistent pattern of dose of dexamethasone or incubation time between the different organs. In the absence of monoclonal antibodies against lungfish immune cells, these functional flow cytometric analyses aid our understanding on the functionality of immune cells.
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comparative pelvic development of the axolotl ambystoma mexicanum and the australian lungfish Neoceratodus forsteri conservation and innovation across the fish tetrapod transition
Evodevo, 2013Co-Authors: Jean M.p. Joss, Catherine A Boisvert, Per E AhlbergAbstract:The fish-tetrapod transition was one of the major events in vertebrate evolution and was enabled by many morphological changes. Although the transformation of paired fish fins into tetrapod limbs has been a major topic of study in recent years, both from paleontological and comparative developmental perspectives, the interest has focused almost exclusively on the distal part of the appendage and in particular the origin of digits. Relatively little attention has been paid to the transformation of the pelvic girdle from a small unipartite structure to a large tripartite weight-bearing structure, allowing tetrapods to rely mostly on their hindlimbs for locomotion. In order to understand how the ischium and the ilium evolved and how the acetabulum was reoriented during this transition, growth series of the Australian lungfish Neoceratodus forsteri and the Mexican axolotl Ambystoma mexicanum were cleared and stained for cartilage and bone and immunostained for skeletal muscles. In order to understand the myological developmental data, hypotheses about the homologies of pelvic muscles in adults of Latimeria, Neoceratodus and Necturus were formulated based on descriptions from the literature of the coelacanth (Latimeria), the Australian Lungfish (Neoceratodus) and a salamander (Necturus). In the axolotl and the lungfish, the chondrification of the pelvic girdle starts at the acetabula and progresses anteriorly in the lungfish and anteriorly and posteriorly in the salamander. The ilium develops by extending dorsally to meet and connect to the sacral rib in the axolotl. Homologous muscles develop in the same order with the hypaxial musculature developing first, followed by the deep, then the superficial pelvic musculature. Development of the pelvic endoskeleton and musculature is very similar in Neoceratodus and Ambystoma. If the acetabulum is seen as being a fixed landmark, the evolution of the ischium only required pubic pre-chondrogenic cells to migrate posteriorly. It is hypothesized that the iliac process or ridge present in most tetrapodomorph fish is the precursor to the tetrapod ilium and that its evolution mimicked its development in modern salamanders.
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Comparative pelvic development of the axolotl (Ambystoma mexicanum) and the Australian lungfish (Neoceratodus forsteri): conservation and innovation across the fish-tetrapod transition
EvoDevo, 2013Co-Authors: Catherine A Boisvert, Jean M.p. Joss, Per E AhlbergAbstract:Background The fish-tetrapod transition was one of the major events in vertebrate evolution and was enabled by many morphological changes. Although the transformation of paired fish fins into tetrapod limbs has been a major topic of study in recent years, both from paleontological and comparative developmental perspectives, the interest has focused almost exclusively on the distal part of the appendage and in particular the origin of digits. Relatively little attention has been paid to the transformation of the pelvic girdle from a small unipartite structure to a large tripartite weight-bearing structure, allowing tetrapods to rely mostly on their hindlimbs for locomotion. In order to understand how the ischium and the ilium evolved and how the acetabulum was reoriented during this transition, growth series of the Australian lungfish Neoceratodus forsteri and the Mexican axolotl Ambystoma mexicanum were cleared and stained for cartilage and bone and immunostained for skeletal muscles. In order to understand the myological developmental data, hypotheses about the homologies of pelvic muscles in adults of Latimeria , Neoceratodus and Necturus were formulated based on descriptions from the literature of the coelacanth ( Latimeria) , the Australian Lungfish ( Neoceratodus) and a salamander ( Necturus) . Results In the axolotl and the lungfish, the chondrification of the pelvic girdle starts at the acetabula and progresses anteriorly in the lungfish and anteriorly and posteriorly in the salamander. The ilium develops by extending dorsally to meet and connect to the sacral rib in the axolotl. Homologous muscles develop in the same order with the hypaxial musculature developing first, followed by the deep, then the superficial pelvic musculature. Conclusions Development of the pelvic endoskeleton and musculature is very similar in Neoceratodus and Ambystoma . If the acetabulum is seen as being a fixed landmark, the evolution of the ischium only required pubic pre-chondrogenic cells to migrate posteriorly. It is hypothesized that the iliac process or ridge present in most tetrapodomorph fish is the precursor to the tetrapod ilium and that its evolution mimicked its development in modern salamanders.
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the epithelial sodium channel in the australian lungfish Neoceratodus forsteri osteichthyes dipnoi
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Minoru Uchiyama, Sho Maejima, Sumio Yoshie, Yoshihiro Kubo, Norifumi Konno, Jean M.p. JossAbstract:Epithelial sodium channel (ENaC) is a Na+-selective, aldosterone-stimulated ion channel involved in sodium transport homeostasis. ENaC is rate-limiting for Na+ absorption in the epithelia of osmoregulatory organs of tetrapods. Although the ENaC/degenerin gene family is proposed to be present in metazoans, no orthologues or paralogues for ENaC have been found in the genome databases of teleosts. We studied full-length cDNA cloning and tissue distributions of ENaCα, β and γ subunits in the Australian lungfish, Neoceratodus forsteri , which is the closest living relative of tetrapods. Neoceratodus ENaC ( n ENaC) comprised three subunits: n ENaCα, β and γ proteins. The n ENaCα, β and γ subunits are closely related to amphibian ENaCα, β and γ subunits, respectively. Three ENaC subunit mRNAs were highly expressed in the gills, kidney and rectum. Amiloride-sensitive sodium current was recorded from Xenopus oocytes injected with the n ENaCαβγ subunit complementary RNAs under a two-electrode voltage clamp. n ENaCα immunoreactivity was observed in the apical cell membrane of the gills, kidney and rectum. Thus, n ENaC may play a role in regulating sodium transport of the lungfish, which has a renin–angiotensin–aldosterone system. This is interesting because there may have been an ENaC sodium absorption system controlled by aldosterone before the conquest of land by vertebrates.
Joss Jean - One of the best experts on this subject based on the ideXlab platform.
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The integument of lungfish: General structure and keratin composition
'Informa UK Limited', 2016Co-Authors: Alibardi Lorenzo, Joss Jean, Toni MattiaAbstract:The aquatic environment poses less restrictions on mechanical and barrier performances in the integument of both marine and freshwater vertebrates, mainly fish and some amphibians, in comparison to the skin of terrestrial vertebrates (Whitear 1977; Zaccone et al. 2001; Alibardi 2006). As a result, apart from specific locations of the body in a few species of fishes and amphibians, the epidermis of aquatic vertebrates resembles the relatively poorly keratinised multi-layered epithelia found in the mucoses lining the respiratory or alimentary canals of terrestrial vertebrates (Whitear 1986a,b). In particular a corneal layer is missing over the general epidermis of fishes and perennibranchiate amphibians. Th is includes also sarcopterygian fish, both crossopterygians (Latimeria, saltwater) and dipnoans (freshwater). Th is chapter is mainly concerned with the skin, especially the epidermis of the Australian lungfish, Neoceratodus forsteri, which is compared where studies are available, with the epidermis of other species of dipnoans (Kitzan and Sweeny 1968; Imaki and Chavin 1975a,b, 1984). In addition to a previously published study (Alibardi and Joss 2003), N. forsteri skin derived from two extra larval stages are described and the keratins have been partially characterised
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Functional analyses of lymphocytes and granulocytes isolated from the thymus, spiral valve intestine, spleen, and kidney of juvenile Australian lungfish, Neoceratodus forsteri
'Elsevier BV', 2013Co-Authors: Hassanpour Masoud, Joss Jean, Mohammad, Mohammad GAbstract:Our current understanding of the lungfish immune system is limited. This study is characterizing the immune cells separated from primary and secondary immune organs of the Australian lungfish, Neoceratodus forsteri. Our functional studies utilized flow cytometry to study the immune cells extracted from the thymus, spiral valve intestine, spleen, and kidney. The different characteristics of lymphocytes and granulocytes were analyzed by utilization of viability, phagocytosis, oxidative burst, and apoptosis assays. Most of the nonviable intestinal cells were lymphocytes. Depending on the organ, 6-25% of the total population, predominantly granulocytes, underwent phagocytosis where the splenic cells were the most and intestinal cells the least phagocytic cells. Cells responded positively but differently to stimulation with phorbol myristate acetate (PMA) to produce radical oxygen species, an indication of their oxidative burst activity, which was mainly associated with granulocytes. Although cells were induced by dexamethasone to undergo apoptosis, such an induction did not follow a consistent pattern of dose of dexamethasone or incubation time between the different organs. In the absence of monoclonal antibodies against lungfish immune cells, these functional flow cytometric analyses aid our understanding on the functionality of immune cells.8 page(s
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The Biology of lungfishes
Enfield N.H : Science Publishers, 2011Co-Authors: Jorgensen, Jorden Morup, Joss JeanAbstract:The fossil record of lungfishes / Jennifer A. Clack, Esther L. Sharp & John A. Long -- Phylogeny of lungfishes / Zerina Johanson & Per E. Ahlberg -- The natural history of the Australian lungfish Neoceratodus forsteri (Krefft, 1870) / Peter K. Kind -- The general natural history of the African lungfishes / Chrisestom M. Mlewa, John M. Green & Robert L. Dunbrack -- Biology of the South American lungfish, Lepidosiren paradoxa / Vera Maria Fonseca de Almeida-Val ... [et al.] -- Early head development in the Australian lungfish, Neoceratodus forsteri / Rolf Ericsson, Jean Joss & Lennart Olsson -- The head muscles of dipnoans - a review on the homologies and evolution of these muscles within vertebrates / Rui Diogo & Virginia Abdala -- The dipnoan dentition : a unique adaptation with a longstanding evolutionary record / Maya Meredith Smith & Zerina Johanson -- The integument of lungfish : general structure and keratin composition / Lorenzo Alibardi, Jean Joss & Mattia Toni -- Respiratory function in lungfish (Dipnoi) and a comparison to land vertebrates / Mogens L. Glass -- Respiratory adaptations in lungfish blood and hemoglobin / Roy E. Weber & Frank Bo Jensen -- Lungfish metabolism / James S. Ballantyne & Natasha T. Frick -- The lungfish digestive system / Masoud Hassanpour & Jean Joss -- The lungfish urogenital system / Jean Joss -- The lungfish endocrine system / Jean Joss -- The central nervous system of lungfishes / R. Glenn Northcutt -- Vision in lungfish / Justin Marshall ... [et al.] -- The lateral line system in lungfishes : mechanoreceptive neuromasts and electroreceptive ampullary organs / Jørgen Mørup Jørgensen -- The inner ear of lungfishes / Jørgen Mørup Jørgensen & Arthur N. Popper -- Hearing in the African lungfish, Protopterus annectens / Jakob Christensen-Dalsgaard ... [et al.].536 page(s
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Anatomy and histology of the spiral valve intestine in juvenile Australian lungfish, Neoceratodus forsteri
'Bentham Science Publishers Ltd.', 2009Co-Authors: Hassanpour Masoud, Joss JeanAbstract:The Australian lungfish, Neoceratodus forsteri, is the only vertebrate that possesses a complete spiral valve intestine with pre-pyloric coiling. This study describes the anatomy and histology of the spiral valve intestine in juvenile N. forsteri and compares it to a previous study of adult N. forsteri, thus providing a broader picture and better understanding of the intestine of the Australian lungfish. Not surprisingly, most features of the spiral valve intestine in juvenile and adult N. forsteri are similar. However, our study goes further to show that, unlike most other vertebrates, the stomach (pre-pyloris) is non-distensible (lacks rugae). Rugae are confined to the post-pyloric duodenum. The epithelium of the pyloric fold, between foregut and midgut, is ciliated and the presence of lymphoid tissue in the pyloric fold implies the involvement of this region in the immune system. Lymphoid tissue is also present around the posterior spleen in the medial axis, which indicates a broader gut-associated lymphoid tissue (GALT) in juvenile Neoceratodus than has been previously recognized in adult Neoceratodus. This study also found some node-like structures in the epithelium of the mucosal tissue, which resemble the Peyer’s patches of other more advanced vertebrates. Furthermore, a previously unreported parasite was found in the spleen encased in fibrous tissue, indicating an immune response had been mounted by the host against it. These latter observations suggest that a thorough investigation of GALT in Neoceratodus is warranted.24 page(s
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Cytoskeletal proteins in thymic epithelial cells of the Australian lungfish Neoceratodus forsteri
'Wiley', 2009Co-Authors: Mohammad, Mohammad G, Raftos David, Joss JeanAbstract:The vertebrate thymus consists of distinctive subpopulations of epithelial cells that contain a diverse repertoire of cytoskeletal proteins. In this study of the thymus in the Australian lungfish, Neoceratodus forsteri, immunohistochemistry was used to distinguish the cytoskeletal proteins present in each class of thymic epithelial cell. A panel of antibodies (Abs), each specific for a different cytoskeletal polypeptide (keratins, vimentin, desmin, actin and tubulins), was used on paraffin and ultrathin resin sections of thymus. Ab AE I (reactive against human type I cytokeratins (CK) 14, 16 and 19) selectively stained the cytoplasm of capsular, trabecular and the outermost epithelial cells of Hassall's corpuscles. Anti-CK 10 Abs strongly labelled the capsular epithelial cells and less than 20% of cortical and medullary epithelial cells. The anti-50-kDa desmin Ab did not react with any thymic cells, whereas the anti-53-kDa desmin Ab labelled some capsular, cortical and medullary thymic epithelial cells. The anti-vimentin Ab stained most of the capsular and ~60% of the cortical epithelium. Thymic nurse cells and Hassall's corpuscles were found to be devoid of actin, which was strongly detected in medullary and perivascular epithelium. Both α and β tubulins were detected in all thymic cells. This study extends the concept of thymic epithelial heterogeneity. The complexity of thymic epithelium in N. forsteri may indicate a relationship between thymic epithelial subpopulations and the thymic microenvironment. These data identify anti-keratin Abs as a valuable tool for studying differentiation and ontogeny of the thymic epithelium in N. forsteri.13 page(s
Agustín González - One of the best experts on this subject based on the ideXlab platform.
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comparative analysis of the serotonergic systems in the cns of two lungfishes protopterus dolloi and Neoceratodus forsteri
Brain Structure & Function, 2015Co-Authors: Jesus M Lopez, Agustín GonzálezAbstract:The organization of the serotonergic system, one of the most important neurotransmitter systems in the brain, has been carefully analyzed in most vertebrate groups, and major shared characteristics have been described, although traits particular to each vertebrate class have also been found. The present study is the first that provides a comprehensive and detailed map of the serotonergic structures in the brain of two representative species of lungfishes, the African lungfish (Protopterus dolloi) and the Australian lungfish (Neoceratodus forsteri), as revealed by immunohistochemistry against serotonin (5-HT). Lungfishes are currently considered the closest living relatives of tetrapods and represent an interesting group for the study of evolutionary traits in the transition from fishes to tetrapods. Distinct groups of serotonin immunoreactive cells were observed in the preoptic area, nucleus of the periventricular organ, pretectum, optic tectum and the long column of the raphe. Fiber labeling was widely distributed in all main brain subdivisions but was more abundant in regions such as the striatum, septum, amygdaloid complex, preoptic area, suprachiasmatic nucleus, lateral hypothalamic area, prethalamus, thalamus, mesencephalic tegmentum and rhombencephalic reticular formation. Comparison of these results with those from other classes of vertebrates highlights numerous common traits shared by most groups of fishes but also reveals that the serotonergic system in lungfishes largely resembles those of amphibians and other tetrapods.
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organization of the cholinergic systems in the brain of two lungfishes protopterus dolloi and Neoceratodus forsteri
Brain Structure & Function, 2012Co-Authors: Jesus M Lopez, Laura Dominguez, Ruth Morona, Glenn R Northcutt, Agustín GonzálezAbstract:Lungfishes (dipnoans) are currently considered the closest living relatives of tetrapods. The organization of the cholinergic systems in the brain has been carefully analyzed in most vertebrate groups, and major shared characteristics have been described, although traits particular to each vertebrate class have also been found. In the present study, we provide the first detailed information on the distribution of cholinergic cell bodies and fibers in the central nervous system in two representative species of lungfishes, the African lungfish (Protopterus dolloi) and the Australian lungfish (Neoceratodus forsteri), as revealed by immunohistochemistry against the enzyme choline acetyltransferase (ChAT). Distinct groups of ChAT immunoreactive (ChAT-ir) cells were observed in the basal telencephalon, habenula, isthmic nucleus, laterodorsal tegmental nucleus, cranial nerve motor nuclei, and the motor column of the spinal cord, and these groups seem to be highly conserved among vertebrates. In lungfishes, the presence of a cholinergic cell group in the thalamus and the absence of ChAT-ir cells in the tectum are variable traits, unique to this group and appearing several times during evolution. Other characters were observed exclusively in Neoceratodus, such as the presence of cholinergic cells in the suprachiasmatic nucleus, the pretectal region and the superior raphe nucleus. Cholinergic fibers were found in the medial pallium, basal telencephalon, thalamus and prethalamus, optic tectum and interpeduncular nucleus. Comparison of these results with those from other classes of vertebrates, including a segmental analysis to correlate cell populations, reveals that the cholinergic systems in lungfishes largely resemble those of amphibians and other tetrapods.
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immunohistochemical localization of calbindin d28k and calretinin in the retina of two lungfishes protopterus dolloi and Neoceratodus forsteri colocalization with choline acetyltransferase and tyrosine hydroxylase
Brain Research, 2011Co-Authors: Ruth Morona, Glenn R Northcutt, Agustín GonzálezAbstract:Abstract There are no previous studies of the distribution of calbindin-D28k (CB) and calretinin (CR) in retinal neurons in lungfishes. The present study aimed to characterize the distribution of these neurons in a lepidosirenid lungfish ( Protopterus dolloi ) and a ceratodontid lungfish ( Neoceratodus forsteri ) using the same immunohistochemical protocol, with specific poly- and monoclonal antibodies, used in a previous comparative study of amphibians. The pattern for both proteins was similar in the two lungfishes studied, but some differences were also found. CB was found in photoreceptors, in subpopulations of bipolar and amacrine cells, and in horizontal and ganglion cells. Photoreceptors were negative for CR, whereas subpopulations of horizontal, bipolar, and amacrine cells contained CR, as did cells in the ganglion cell layer. Colocalization of CB/CR occurred in some cells of the inner nuclear layer. Tyrosine hydroxylase (TH) immunoreactivity colocalized with CB in some amacrine cells and, less frequently, with CR, but colocalization of TH with CB or CR in cholinergic cells was never found. Our data suggest a specific pattern for CB and CR distribution in the retinal neurons of lungfishes, a pattern that is highly comparable to that seen in amphibians, with unique features not observed in other vertebrates.
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An immunohistochemical approach to lungfish telencephalic organization.
Brain Behavior and Evolution, 2009Co-Authors: Agustín GonzálezAbstract:The brains of lungfishes have received little attention in comparative neuroanatomy, in spite of the strategic position of these fishes in phylogeny, in that they are currently recognized as the closest living relatives of tetrapods. The neglect has probably been due to the difficulty of obtaining these unique animals, which comprise (along with the coelacanths) the only extant representatives of the lobe-finned fishes. Several previous studies have established the basic anatomy of the telencephalon in lungfishes, but many aspects of the intrinsic organization of the main telencephalic subregions have remained unclear. The immunohistochemical localization of diverse neurotransmitters, neuromodulators, and transcription factors expressed by genes involved in brain regionalization has served to clarify many aspects of the organization of the telencephalon in lungfishes. Here we describe the main immunohistochemical features of the telencephalon in two lungfish species, Protopterus dolloi and Neoceratodus forsteri. Our analysis highlights the common traits shared by lungfishes and tetrapods. These include four pallial regions, distinct striatal and pallidal components of the basal ganglia, specific regionalization of the septum, and the presence of three amygdaloid regions. In general, the use of immunohistochemistry in the study of the telencephalon of lungfishes reveals that this structure is notably more complex than previously thought and that it possesses all major subregions recognized in amphibians and amniotes.
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distribution of orexin hypocretin immunoreactivity in the brain of the lungfishes protopterus dolloi and Neoceratodus forsteri
Brain Behavior and Evolution, 2009Co-Authors: Jesus M Lopez, Laura Dominguez, Ruth Morona, Nerea Moreno, Alberto Joven, Agustín GonzálezAbstract:Lungfishes are currently considered the closest living relatives of tetrapods and represent an interesting group for the study of evolutionary traits in the transition from fishes to tetrapods. The br
Anne Kemp - One of the best experts on this subject based on the ideXlab platform.
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formation and structure of scales in the australian lungfish Neoceratodus forsteri osteichthyes dipnoi
Journal of Morphology, 2012Co-Authors: Anne KempAbstract:The large elasmoid scales of the Australian lungfish, Neoceratodusforsteri, are formed within the dermis by unpigmented scleroblasts, growing within a collagenous dermal pocket below a thick glandular epidermis. The first row of scales, on the trunk of the juvenile lungfish, appears below the lateral line of the trunk, single in this species, at around stage 53. The scales, initially circular in outline, develop anteriorly and posteriorly from the point of initiation in the mid-trunk region, and rows are added alternately below the line, and above the line, until they reach the dorsal or ventral midline, or the margins of the fins. Scales develop later on the ventral surface of the head, from a separate centre of initiation. Scales consist of three layers, all produced by scleroblasts of dermal origin. The outermost layer of interlocking plates, or squamulae, consists of a mineralised matrix of fine collagen fibrils, covered by unmineralised collagen and a single layer of cells. Squamulae of the anterior and lateral surfaces are ornamented with short spines, and the mineralised tissue of the posterior surface is linked to the pouch by collagen fibrils. The innermost layer, known as elasmodin, consists of bundles of thick collagen fibrils and cells arranged in layers. An intermediate layer, made up of collagen fibrils, links the outer and inner layers. The elasmoid scales of N. forsteri can be compared with scale types among other osteichthyan groups, although the cellsand canaliculi in the mineralised squamulae bear littleresemblance to typical bone.
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ultrastructure of developing tooth plates in the australian lungfish Neoceratodus forsteri osteichthyes dipnoi
Tissue & Cell, 2003Co-Authors: Anne KempAbstract:While the lungfish dentition is partially understood as far as morphology and light microscopic structure is concerned, the ultrastructure is not. Each tooth plate is associated with a dental lamina that develops from the inner layer of endodermal cells that form the oral epithelium. Dentines, bone and cartilage of the jaws differentiate from mesenchyme cells aggregating beneath the oral endothelium. Enamel, in the developing and in the mature form, has similarities to that of other early vertebrates, but unusual characters appear as development proceeds. Ameloblasts are capable of secreting enamel, and, with mononuclear osteoclasts, of remodelling the bone below the tooth plate. The forms of dentine, all based largely on an extracellular matrix of collagen and mineralised with biological apatite, differ from each other and from the underlying bone in the ultrastructure of associated cells and in the mineralised extracellular matrices produced. Cell processes emerging from the odontoblasts and from the osteoblasts vary in length, degree of branching and of anastomoses between the processes, although all of the cell types have large amounts of rough endoplasmic reticulum. Mineralisation of the extracellular matrices varies among the enamel, dentines and bone in the tooth plate. In addition, the development of the hard tissues of the tooth plates indicates that many of the similarities in fine structure of the dentition in lungfish, to tissues in other fish and amphibia, apparent early in development, disappear as the dentition matures.
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Ontogeny of the skull of the Australian lungfish Neoceratodus forsteri (Osteichthyes: Dipnoi)
Journal of Zoology, 1999Co-Authors: Anne KempAbstract:Development of the sensory lines, dermal skull bones, neurocranium, quadrate, mandible and hyoid apparatus of the Holocene Australian lungfish Neoceratodus forsteri is described, beginning at stage 40, before the formation of any skeletal elements, until skull development is complete in the sub-adult fish. The sequence of the initial development of skeletal structures of the head and shoulder girdle reflects the need to feed and to acquire efficient gill respiration. The appearance of the neurocranium and dermal bones of the skull follows the formation of teeth, jaw bones and the cartilaginous quadrate, and the opercular bones, the skeletal elements directly associated with these functions. Dermal skull elements are closely related to the distribution of the sensory line system of the head. Each bone of the normal developing skull roof arises from a single centre of ossification, forming in a collagenous template secreted by mesenchymal cells. The numbers and arrangement of the skull bones found in the adult N. forsteri is the same as the pattern of bones laid down in the hatchling and juvenile, and the structures develop in an ordered and functional sequence.
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a revision of australian mesozoic and cenozoic lungfish of the family neoceratodontidae osteichthyes dipnoi with a description of four new species
Journal of Paleontology, 1997Co-Authors: Anne KempAbstract:The taxonomy of the predominantly Australian fossil dipnoan genus, Neoceratodus, is revised and the Recent Australian lungfish, Neoceratodus forsteri, and two fossil species, Neoceratodus eyrensis and Neoceratodus nargun, are redefined. Two new species of the related Tertiary genus, Mioceratodus, are described on the basis of tooth plates from central and northern localities in Australia. These are Mioceratodus diaphorus and Mioceratodus poastrus. A new genus, Archaeoceratodus, is erected to include three rare Tertiary species and one Mesozoic species. The Tertiary members of this genus are the type species, Archaeoceratodus djelleh, described originally as Neoceratodus djelleh, and two new species, Archaeoceratodus rowleyi and Archaeoceratodus theganus. The Mesozoic species is Archaeoceratodus avus from Triassic and Cretaceous deposits in southeastern Australia, described originally as Ceratodus avus. All three genera belong in the family Neoceratodontidae.
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marginal tooth bearing bones in the lower jaw of the recent australian lungfish Neoceratodus forsteri osteichthyes dipnoi
Journal of Morphology, 1995Co-Authors: Anne KempAbstract:Developmental studies of the Recent Australian lungfish, Neoceratodus forsteri, show that this species has two sets of functional tooth-bearing bones in the lower jaw of young hatchlings. These coincide with an early stage in the life history when the fish is strictly carnivorous. In N. forsteri, a paired tooth-bearing dentary and an unpaired symphyseal bone and tooth develop slightly later than the permanent vomerine, prearticular, and pterygopalatine tooth plates, which appear at stage 44 of development, and erupt with the permanent dentition between stages 46 and 48, when the hatchling first starts to feed on small aquatic invertebrates. At these stages of development, all of the teeth are long, sharp, and conical and help to retain prey items in the mouth. Disappearance of the transient dentition coincides with complete eruption of the permanent tooth plates and precedes the change to an omnivorous diet. Existence of a transient marginal dentition in this species of lungfish suggests that the presence of an apparently similar marginal dentition in adults of many species of Palaeozoic dipnoans should be considered in phylogenetic analyses of genera within the group, and when analysing the relationships of dipnoans with other primitive animals. © 1995 Wiley-Liss, Inc.
Masoud Hassanpour - One of the best experts on this subject based on the ideXlab platform.
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functional analyses of lymphocytes and granulocytes isolated from the thymus spiral valve intestine spleen and kidney of juvenile australian lungfish Neoceratodus forsteri
Fish & Shellfish Immunology, 2013Co-Authors: Jean M.p. Joss, Masoud Hassanpour, Mohammad G MohammadAbstract:Abstract Our current understanding of the lungfish immune system is limited. This study is characterizing the immune cells separated from primary and secondary immune organs of the Australian lungfish, Neoceratodus forsteri . Our functional studies utilized flow cytometry to study the immune cells extracted from the thymus, spiral valve intestine, spleen, and kidney. The different characteristics of lymphocytes and granulocytes were analyzed by utilization of viability, phagocytosis, oxidative burst, and apoptosis assays. Most of the nonviable intestinal cells were lymphocytes. Depending on the organ, 6–25% of the total population, predominantly granulocytes, underwent phagocytosis where the splenic cells were the most and intestinal cells the least phagocytic cells. Cells responded positively but differently to stimulation with phorbol myristate acetate (PMA) to produce radical oxygen species, an indication of their oxidative burst activity, which was mainly associated with granulocytes. Although cells were induced by dexamethasone to undergo apoptosis, such an induction did not follow a consistent pattern of dose of dexamethasone or incubation time between the different organs. In the absence of monoclonal antibodies against lungfish immune cells, these functional flow cytometric analyses aid our understanding on the functionality of immune cells.
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anatomy and histology of the spiral valve intestine in juvenile australian lungfish Neoceratodus forsteri
The Open Zoology Journal, 2009Co-Authors: Masoud Hassanpour, Jean M.p. JossAbstract:The Australian lungfish, Neoceratodus forsteri, is the only vertebrate that possesses a complete spiral valve intestine with pre-pyloric coiling. This study describes the anatomy and histology of the spiral valve intestine in juvenile N. forsteri and compares it to a previous study of adult N. forsteri, thus providing a broader picture and better understanding of the intestine of the Australian lungfish. Not surprisingly, most features of the spiral valve intestine in juvenile and adult N. forsteri are similar. However, our study goes further to show that, unlike most other vertebrates, the stomach (pre-pyloris) is non-distensible (lacks rugae). Rugae are confined to the post-pyloric duodenum. The epithelium of the pyloric fold, between foregut and midgut, is ciliated and the presence of lymphoid tissue in the pyloric fold implies the involvement of this region in the immune system. Lymphoid tissue is also present around the posterior spleen in the medial axis, which indicates a broader gut-associated lymphoid tissue (GALT) in juvenile Neoceratodus than has been previously recognized in adult Neoceratodus. This study also found some node-like structures in the epithelium of the mucosal tissue, which resemble the Peyer's patches of other more advanced vertebrates. Furthermore, a previously unreported parasite was found in the spleen encased in fibrous tissue, indicating an immune response had been mounted by the host against it. These latter observations suggest that a thorough investigation of GALT in Neoceratodus is warranted.
