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Nico J. Smit - One of the best experts on this subject based on the ideXlab platform.
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Redescription, molecular characterisation and taxonomic re-evaluation of a unique African Monitor Lizard haemogregarine Karyolysus paradoxa (Dias, 1954) n. comb. (Karyolysidae)
Parasites & vectors, 2016Co-Authors: Courtney A. Cook, Edward C. Netherlands, Nico J. SmitAbstract:Background Within the African Monitor Lizard family Varanidae, two haemogregarine genera have been reported. These comprise five species of Hepatozoon Miller, 1908 and a species of Haemogregarina Danilewsky, 1885. Even though other haemogregarine genera such as Hemolivia Petit, Landau, Baccam & Lainson, 1990 and Karyolysus Labbe, 1894 have been reported parasitising other Lizard families, these have not been found infecting the Varanidae. The genus Karyolysus has to date been formally described and named only from Lizards of the family Lacertidae and to the authors’ knowledge, this includes only nine species. Molecular characterisation using fragments of the 18S gene has only recently been completed for but two of these species. To date, three Hepatozoon species are known from southern African varanids, one of these Hepatozoon paradoxa (Dias, 1954) shares morphological characteristics alike to species of the family Karyolysidae. Thus, this study aimed to morphologically redescribe and characterise H. paradoxa molecularly, so as to determine its taxonomic placement.
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Redescription, molecular characterisation and taxonomic re-evaluation of a unique African Monitor Lizard haemogregarine Karyolysus paradoxa (Dias, 1954) n. comb. (Karyolysidae)
Parasites & Vectors, 2016Co-Authors: Courtney A. Cook, Edward C. Netherlands, Nico J. SmitAbstract:Background Within the African Monitor Lizard family Varanidae, two haemogregarine genera have been reported. These comprise five species of Hepatozoon Miller, 1908 and a species of Haemogregarina Danilewsky, 1885. Even though other haemogregarine genera such as Hemolivia Petit, Landau, Baccam & Lainson, 1990 and Karyolysus Labbé, 1894 have been reported parasitising other Lizard families, these have not been found infecting the Varanidae. The genus Karyolysus has to date been formally described and named only from Lizards of the family Lacertidae and to the authors’ knowledge, this includes only nine species. Molecular characterisation using fragments of the 18S gene has only recently been completed for but two of these species. To date, three Hepatozoon species are known from southern African varanids, one of these Hepatozoon paradoxa (Dias, 1954) shares morphological characteristics alike to species of the family Karyolysidae. Thus, this study aimed to morphologically redescribe and characterise H. paradoxa molecularly, so as to determine its taxonomic placement. Methods Specimens of Varanus albigularis albigularis Daudin, 1802 (Rock Monitor) and Varanus niloticus (Linnaeus in Hasselquist, 1762) (Nile Monitor) were collected from the Ndumo Game Reserve, South Africa. Upon capture animals were examined for haematophagous arthropods. Blood was collected, thin blood smears prepared, stained with Giemsa, screened and micrographs of parasites captured. Haemogregarine morphometric data were compared with the data for named haemogregarines of African varanids. Primer set HepF300 and HepR900 was employed to target a fragment of the 18S rRNA gene and resulting sequences compared with other known haemogregarine sequences selected from the GenBank database. Results Hepatozoon paradoxa was identified infecting two out of eight (25 %) V. a. albigularis and a single (100 %) V. niloticus examined. Phylogenetic analyses revealed that H. paradoxa clustered with the ‘ Karyolysus ’ clade, and not with those of reptilian Hepatozoon spp. Conclusions In addition to this being the first morphological and molecular characterisation of a haemogregarine within the African Varanidae, it is the first report of a species of Karyolysus infecting the Monitor Lizard family. Furthermore, this constitutes now only the third described and named Karyolysus species for which there is a nucleotide sequence available.
C G Farmer - One of the best experts on this subject based on the ideXlab platform.
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unidirectional pulmonary airflow patterns in the savannah Monitor Lizard
Nature, 2014Co-Authors: Emma R Schachner, Robert L Cieri, James P Butler, C G FarmerAbstract:Unlike the tidal (in and out) breathing of mammals, bird lungs have unidirectional airflow patterns; here the savannah Monitor Lizard is shown to have unidirectional airflow too, with profound implications for the evolution of unidirectional airflow in reptiles, predating the origin of birds. Ventilation in mammals is tidal — breathe in then breathe out. In birds, however, the situation is more complicated. The lungs are just part of an extensive network of air sacs connected in such a way that airflow is unidirectional. It was thought that this arrangement was related to the energetic demands of flight but when similar systems were found in crocodilians and inferred in dinosaurs, it appeared that unidirectional airflow ventilation may have been primitive for archosaurs — the clade that includes birds, crocodiles and dinosaurs. But could the unidirectional airflow system be even more widespread? Lepidosaurs (Lizards, snakes and allies) are the sister taxon to archosaurs and now a study of the Monitor Lizard shows that for this lepidosaur, at least some of its ventilation is tidal. This is an important discovery, but the jury is still out on whether unidirectional airflow is a convergent feature of archosaurs and lepidosaurs, or whether it is a basal character of both groups. If the latter, then unidirectional airflow evolved 100 million years before the first bird flew. The unidirectional airflow patterns in the lungs of birds have long been considered a unique and specialized trait associated with the oxygen demands of flying, their endothermic metabolism1 and unusual pulmonary architecture2,3. However, the discovery of similar flow patterns in the lungs of crocodilians indicates that this character is probably ancestral for all archosaurs—the group that includes extant birds and crocodilians as well as their extinct relatives, such as pterosaurs and dinosaurs4,5,6. Unidirectional flow in birds results from aerodynamic valves, rather than from sphincters or other physical mechanisms7,8, and similar aerodynamic valves seem to be present in crocodilians4,5,6. The anatomical and developmental similarities in the primary and secondary bronchi of birds and crocodilians suggest that these structures and airflow patterns may be homologous4,5,6,9. The origin of this pattern is at least as old as the split between crocodilians and birds, which occurred in the Triassic period10. Alternatively, this pattern of flow may be even older; this hypothesis can be tested by investigating patterns of airflow in members of the outgroup to birds and crocodilians, the Lepidosauromorpha (tuatara, Lizards and snakes). Here we demonstrate region-specific unidirectional airflow in the lungs of the savannah Monitor Lizard (Varanus exanthematicus). The presence of unidirectional flow in the lungs of V. exanthematicus thus gives rise to two possible evolutionary scenarios: either unidirectional airflow evolved independently in archosaurs and Monitor Lizards, or these flow patterns are homologous in archosaurs and V. exanthematicus, having evolved only once in ancestral diapsids (the clade encompassing snakes, Lizards, crocodilians and birds). If unidirectional airflow is plesiomorphic for Diapsida, this respiratory character can be reconstructed for extinct diapsids, and evolved in a small ectothermic tetrapod during the Palaeozoic era at least a hundred million years before the origin of birds.
Courtney A. Cook - One of the best experts on this subject based on the ideXlab platform.
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Redescription, molecular characterisation and taxonomic re-evaluation of a unique African Monitor Lizard haemogregarine Karyolysus paradoxa (Dias, 1954) n. comb. (Karyolysidae)
Parasites & vectors, 2016Co-Authors: Courtney A. Cook, Edward C. Netherlands, Nico J. SmitAbstract:Background Within the African Monitor Lizard family Varanidae, two haemogregarine genera have been reported. These comprise five species of Hepatozoon Miller, 1908 and a species of Haemogregarina Danilewsky, 1885. Even though other haemogregarine genera such as Hemolivia Petit, Landau, Baccam & Lainson, 1990 and Karyolysus Labbe, 1894 have been reported parasitising other Lizard families, these have not been found infecting the Varanidae. The genus Karyolysus has to date been formally described and named only from Lizards of the family Lacertidae and to the authors’ knowledge, this includes only nine species. Molecular characterisation using fragments of the 18S gene has only recently been completed for but two of these species. To date, three Hepatozoon species are known from southern African varanids, one of these Hepatozoon paradoxa (Dias, 1954) shares morphological characteristics alike to species of the family Karyolysidae. Thus, this study aimed to morphologically redescribe and characterise H. paradoxa molecularly, so as to determine its taxonomic placement.
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Redescription, molecular characterisation and taxonomic re-evaluation of a unique African Monitor Lizard haemogregarine Karyolysus paradoxa (Dias, 1954) n. comb. (Karyolysidae)
Parasites & Vectors, 2016Co-Authors: Courtney A. Cook, Edward C. Netherlands, Nico J. SmitAbstract:Background Within the African Monitor Lizard family Varanidae, two haemogregarine genera have been reported. These comprise five species of Hepatozoon Miller, 1908 and a species of Haemogregarina Danilewsky, 1885. Even though other haemogregarine genera such as Hemolivia Petit, Landau, Baccam & Lainson, 1990 and Karyolysus Labbé, 1894 have been reported parasitising other Lizard families, these have not been found infecting the Varanidae. The genus Karyolysus has to date been formally described and named only from Lizards of the family Lacertidae and to the authors’ knowledge, this includes only nine species. Molecular characterisation using fragments of the 18S gene has only recently been completed for but two of these species. To date, three Hepatozoon species are known from southern African varanids, one of these Hepatozoon paradoxa (Dias, 1954) shares morphological characteristics alike to species of the family Karyolysidae. Thus, this study aimed to morphologically redescribe and characterise H. paradoxa molecularly, so as to determine its taxonomic placement. Methods Specimens of Varanus albigularis albigularis Daudin, 1802 (Rock Monitor) and Varanus niloticus (Linnaeus in Hasselquist, 1762) (Nile Monitor) were collected from the Ndumo Game Reserve, South Africa. Upon capture animals were examined for haematophagous arthropods. Blood was collected, thin blood smears prepared, stained with Giemsa, screened and micrographs of parasites captured. Haemogregarine morphometric data were compared with the data for named haemogregarines of African varanids. Primer set HepF300 and HepR900 was employed to target a fragment of the 18S rRNA gene and resulting sequences compared with other known haemogregarine sequences selected from the GenBank database. Results Hepatozoon paradoxa was identified infecting two out of eight (25 %) V. a. albigularis and a single (100 %) V. niloticus examined. Phylogenetic analyses revealed that H. paradoxa clustered with the ‘ Karyolysus ’ clade, and not with those of reptilian Hepatozoon spp. Conclusions In addition to this being the first morphological and molecular characterisation of a haemogregarine within the African Varanidae, it is the first report of a species of Karyolysus infecting the Monitor Lizard family. Furthermore, this constitutes now only the third described and named Karyolysus species for which there is a nucleotide sequence available.
Kornsorn Srikulnath - One of the best experts on this subject based on the ideXlab platform.
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List of 86 cDNA clones mapped to the Hokou gecko (Gekko hokouensis) chromosomes and their chromosomal locations in the sand Lizard (Lacerta agilis), the water Monitor Lizard (Varanus salvator macromaculatus), the butterfly Lizard (Leiolepis reevesii
2015Co-Authors: Kornsorn Srikulnath, Yoshinobu Uno, Chizuko Nishida, Hidetoshi Ota, Yoichi MatsudaAbstract:aNucleotide sequences of two accession numbers were determined separately by forward and reverse primers in one clone.bThe cDNA fragment were obtain from G. hokouensis, which were mapped in our previous study (Kawai et al. [39]). For mapping of ATP5A1, ACO1/IREBP and CHD1, total length of cDNA fragment concatenated with multiple–: No dataList of 86 cDNA clones mapped to the Hokou gecko (Gekko hokouensis) chromosomes and their chromosomal locations in the sand Lizard (Lacerta agilis), the water Monitor Lizard (Varanus salvator macromaculatus), the butterfly Lizard (Leiolepis reevesii rubritaeniata), the Japanese four-striped rat snake (Elaphe quadrivirgata), the green anole (Anolis carolinensis), and the chicken (Gallus gallus).
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highly species specific centromeric repetitive dna sequences in Lizards molecular cytogenetic characterization of a novel family of satellite dna sequences isolated from the water Monitor Lizard varanus salvator macromaculatus platynota
Journal of Heredity, 2013Co-Authors: Nampech Chaiprasertsri, Yoshinobu Uno, Surin Peyachoknagul, Ornjira Prakhongcheep, Sudarath Baicharoen, Saranon Charernsuk, Chizuko Nishida, Yoichi Matsuda, Akihiko Koga, Kornsorn SrikulnathAbstract:Two novel repetitive DNA sequences, VSAREP1 and VSAREP2, were isolated from the water Monitor Lizard (Varanus salvator macromaculatus, Platynota) and characterized using molecular cytogenetics. The respective lengths and guanine-cytosine (GC) contents of the sequences were 190 bp and 57.5% for VSAREP1 and 185 bp and 59.7% for VSAREP2, and both elements were tandemly arrayed as satellite DNA in the genome. VSAREP1 and VSAREP2 were each located at the C-positive heterochromatin in the pericentromeric region of chromosome 2q, the centromeric region of chromosome 5, and 3 pairs of microchromosomes. This suggests that genomic compartmentalization between macro- and microchromosomes might not have occurred in the centromeric repetitive sequences of V. salvator macromaculatus. These 2 sequences did only hybridize to genomic DNA of V. salvator macromaculatus, but no signal was observed even for other squamate reptiles, including Varanus exanthematicus, which is a closely related species of V. salvator macromaculatus. These results suggest that these sequences were differentiated rapidly or were specifically amplified in the V. salvator macromaculatus genome.
Emma R Schachner - One of the best experts on this subject based on the ideXlab platform.
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unidirectional pulmonary airflow patterns in the savannah Monitor Lizard
Nature, 2014Co-Authors: Emma R Schachner, Robert L Cieri, James P Butler, C G FarmerAbstract:Unlike the tidal (in and out) breathing of mammals, bird lungs have unidirectional airflow patterns; here the savannah Monitor Lizard is shown to have unidirectional airflow too, with profound implications for the evolution of unidirectional airflow in reptiles, predating the origin of birds. Ventilation in mammals is tidal — breathe in then breathe out. In birds, however, the situation is more complicated. The lungs are just part of an extensive network of air sacs connected in such a way that airflow is unidirectional. It was thought that this arrangement was related to the energetic demands of flight but when similar systems were found in crocodilians and inferred in dinosaurs, it appeared that unidirectional airflow ventilation may have been primitive for archosaurs — the clade that includes birds, crocodiles and dinosaurs. But could the unidirectional airflow system be even more widespread? Lepidosaurs (Lizards, snakes and allies) are the sister taxon to archosaurs and now a study of the Monitor Lizard shows that for this lepidosaur, at least some of its ventilation is tidal. This is an important discovery, but the jury is still out on whether unidirectional airflow is a convergent feature of archosaurs and lepidosaurs, or whether it is a basal character of both groups. If the latter, then unidirectional airflow evolved 100 million years before the first bird flew. The unidirectional airflow patterns in the lungs of birds have long been considered a unique and specialized trait associated with the oxygen demands of flying, their endothermic metabolism1 and unusual pulmonary architecture2,3. However, the discovery of similar flow patterns in the lungs of crocodilians indicates that this character is probably ancestral for all archosaurs—the group that includes extant birds and crocodilians as well as their extinct relatives, such as pterosaurs and dinosaurs4,5,6. Unidirectional flow in birds results from aerodynamic valves, rather than from sphincters or other physical mechanisms7,8, and similar aerodynamic valves seem to be present in crocodilians4,5,6. The anatomical and developmental similarities in the primary and secondary bronchi of birds and crocodilians suggest that these structures and airflow patterns may be homologous4,5,6,9. The origin of this pattern is at least as old as the split between crocodilians and birds, which occurred in the Triassic period10. Alternatively, this pattern of flow may be even older; this hypothesis can be tested by investigating patterns of airflow in members of the outgroup to birds and crocodilians, the Lepidosauromorpha (tuatara, Lizards and snakes). Here we demonstrate region-specific unidirectional airflow in the lungs of the savannah Monitor Lizard (Varanus exanthematicus). The presence of unidirectional flow in the lungs of V. exanthematicus thus gives rise to two possible evolutionary scenarios: either unidirectional airflow evolved independently in archosaurs and Monitor Lizards, or these flow patterns are homologous in archosaurs and V. exanthematicus, having evolved only once in ancestral diapsids (the clade encompassing snakes, Lizards, crocodilians and birds). If unidirectional airflow is plesiomorphic for Diapsida, this respiratory character can be reconstructed for extinct diapsids, and evolved in a small ectothermic tetrapod during the Palaeozoic era at least a hundred million years before the origin of birds.
