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Jun Wang - One of the best experts on this subject based on the ideXlab platform.
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Medulloprotaxodioxylon triassicum gen. et sp. nov., a taxodiaceous conifer wood from the Norian (Triassic) of northern Bogda Mountains, northwestern China
Review of Palaeobotany and Palynology, 2017Co-Authors: Mingli Wan, Wan Yang, Peng Tang, Lujun Liu, Jun WangAbstract:A permineralized coniferous wood, Medulloprotaxodioxylon triassicum Wan, Yang, Tang, Liu et Wang gen. et sp. nov., is described from the Norian (Late Triassic) Huangshanjie Formation in the Dalongkou Section, Jimsar County, Xinjiang Uygur Autonomous Region, northwestern China. The fossil wood is composed of the pith, primary and secondary xylem. The pith is solid, circular, heterocellular, with numerous isolated or clustered secretory cells, and parenchyma. Secretory cells commonly form a network in a radial view. The pith is surrounded by numerous primary xylem strands and about 22 distinctive leaf traces. The primary xylem is endarch. Tracheids of primary xylem have helical and scalariform thickenings. The secondary xylem is pycnoxylic, composed of tracheids, rays and axial parenchyma. The general aspect of the tracheids and rays, presence of taxodioid cross-field pits, and abundant axial parenchyma, indicate M. triassicum can be related to the taxodiaceous Cupressaceae sensu lato. By comparison with fossil and extant species of the Cupressaceae, M. triassicum is most comparable to Sequoiadendron giganteum (Lindley) Buchholz. It is hypothesized that M. triassicum represents an ancestral form of the Sequoioideae Saxton based on the anatomical characteristics of the pith and secondary xylem. The occurrence of M. triassicum would indicate that the taxodiaceous conifers had already individualized within the Cupressaceae during the Late Triassic.
Jong Seong Kang - One of the best experts on this subject based on the ideXlab platform.
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Distribution of (-)-yatein in Cupressaceae family analysed by high performance liquid chromatography.
Archives of pharmacal research, 2004Co-Authors: Gwi Seo Hwang, Nguyen Thi Phuong, Kyung Rae Park, Young Ho Kim, Kyeong Ho Kim, Jong Seong KangAbstract:The method for the chiral analysis of (−)-yatein was developed and the distribution of this component in the plants of three genera likeJuniperus, Thuja andChamaecyparis belonging to Cupressaceae family was examined. The chiral analysis of (−)-yatein from the plants was carried out by high performance liquid chromatography on (R,R)-Whelk-O1 column using 81 v/v% methanol as mobile phase. The yatein content in the leaves ofJuniperus was the highest in compare with that of the other two genera, providing the possibility of the chemical discrimination of the plants inJuniperus from the other plants in the Cupressaceae family. In general, the yatein content in the leaves was much higher than that in the twigs. This method could be applied for the quality control of (−)-yatein in the plants belonging to Cupressaceae family.
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Stereoselective determination of (-)-yatein in the plants of the Cupressaceae family by capillary electrophoresis
Journal of Separation Science, 2002Co-Authors: Hwanmi Lim, Young Ho Kim, Yong Kim, Byung Zun Ahn, Jong Seong KangAbstract:The concentration of (–)-Yatein in plants of the Cupressaceae family was determined by capillary electrophoresis. Separation was carried out using a borate buffer (100 mM, pH 10.5) containing 30% v/v methanol and 20 mM carboxymethyl-β-cyclodextrin on a fused silica capillary (75 μm ID×34.6 cm, 30 cm to detector). Only (–)-yatein was found and the contents in the Juniperus, Thuja, and Chamaecyparis species were 7.13, 0.24, and 0.11 mg/g, respectively, indicating that this method could be applied for the quality control of (–)-yatein in the plants belong to the Cupressaceae family.
Hidenori Tachida - One of the best experts on this subject based on the ideXlab platform.
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Relaxation of Functional Constraint on Light-Independent Protochlorophyllide Oxidoreductase in Thuja
Molecular biology and evolution, 2006Co-Authors: Junko Kusumi, Aya Sato, Hidenori TachidaAbstract:The light-independent protochlorophyllide oxidoreductase (DPOR) plays a key role in the ability of nonflowering plants and algae to synthesize chlorophyll in darkness. This enzyme consists of three subunits encoded by the chlB, chlL, and chlN genes in the plastid genome. Previously, we found a high nonsynonymous substitution rate (dN) of the chlL gene in the lineage of Thuja standishii, a conifer belonging to the Cupressaceae. Here we revealed that the acceleration of dN in the chlL occurred as well in other species of Thuja, Thuja occidentalis and Thuja plicata. In addition, dark-grown seedlings of T. occidentalis were found to exhibit a pale yellowish color, and their chlorophyll concentration was much lower than that of other species of Cupressaceae. The results suggested that the species of Thuja have lost the ability to synthesize chlorophyll in darkness, and the functional constraint on the DPOR would thus be expected to be relaxed in this genus. Therefore, we expected to find that the evolutionary rates of all subunits of DPOR would in this case be accelerated. Sequence analyses of the chlN and chlB (encoding the other subunits of DPOR) in 18 species of Cupressaceae revealed that the dN of the chlN gene was accelerated in Thuja as was the dN of the chlL gene, but the dN of the chlB gene did not appear to differ significantly among the species of Cupressaceae. Sequencing of reverse transcription-polymerase chain reaction (RT-PCR) products of these genes showed that RNA editing was rare and unlikely to have contributed to the acceleration. Moreover, the RT-PCR analysis indicated that all chl genes were still transcriptionally active in T. occidentalis. Based on these results, it appears that species of Thuja still bear the DPOR protein, although the enzyme has lost its activity because of nonsynonymous mutations of some of the chl genes. The lack of acceleration of the dN of the chlB gene might be accounted for by various unknown functions of its gene product.
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Phylogenetic relationships in Taxodiaceae and Cupressaceae sensu stricto based on matK gene, chlL gene, trnL-trnF IGS region, and trnL intron sequences.
American journal of botany, 2000Co-Authors: Junko Kusumi, Yoshihiko Tsumura, Hiroshi Yoshimaru, Hidenori TachidaAbstract:Nucleotide sequences from four chloroplast genes, the matK, chlL, intergenic spacer (IGS) region between trnL and trnF, and an intron of trnL, were determined from all species of Taxodiaceae and five species of Cupressaceae sensu stricto (s.s.). Phylogenetic trees were constructed using the maximum parsimony and the neighbor-joining methods with Cunninghamia as an outgroup. These analyses provided greater resolution of relationships among genera and higher bootstrap supports for clades compared to previous analyses. Results indicate that Taiwania diverged first, and thenAthrotaxis diverged from the remaining genera. Metasequoia, Sequoia, and Sequoiadendron form a clade. Taxodium and Glyptostrobus form a clade, which is the sister to Cryptomeria. Cupressaceae s.s. are derived from within Taxodiaceae, being the most closely related to the Cryptomeria/Taxodium/Glyptostrobus clade. These relationships are consistent with previous morphological groupings and the analyses of other molecular data. In addition, we found acceleration of evolutionary rates in Cupressaceae s.s. Possible causes for the acceleration are discussed.
Mingli Wan - One of the best experts on this subject based on the ideXlab platform.
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Medulloprotaxodioxylon triassicum gen. et sp. nov., a taxodiaceous conifer wood from the Norian (Triassic) of northern Bogda Mountains, northwestern China
Review of Palaeobotany and Palynology, 2017Co-Authors: Mingli Wan, Wan Yang, Peng Tang, Lujun Liu, Jun WangAbstract:A permineralized coniferous wood, Medulloprotaxodioxylon triassicum Wan, Yang, Tang, Liu et Wang gen. et sp. nov., is described from the Norian (Late Triassic) Huangshanjie Formation in the Dalongkou Section, Jimsar County, Xinjiang Uygur Autonomous Region, northwestern China. The fossil wood is composed of the pith, primary and secondary xylem. The pith is solid, circular, heterocellular, with numerous isolated or clustered secretory cells, and parenchyma. Secretory cells commonly form a network in a radial view. The pith is surrounded by numerous primary xylem strands and about 22 distinctive leaf traces. The primary xylem is endarch. Tracheids of primary xylem have helical and scalariform thickenings. The secondary xylem is pycnoxylic, composed of tracheids, rays and axial parenchyma. The general aspect of the tracheids and rays, presence of taxodioid cross-field pits, and abundant axial parenchyma, indicate M. triassicum can be related to the taxodiaceous Cupressaceae sensu lato. By comparison with fossil and extant species of the Cupressaceae, M. triassicum is most comparable to Sequoiadendron giganteum (Lindley) Buchholz. It is hypothesized that M. triassicum represents an ancestral form of the Sequoioideae Saxton based on the anatomical characteristics of the pith and secondary xylem. The occurrence of M. triassicum would indicate that the taxodiaceous conifers had already individualized within the Cupressaceae during the Late Triassic.
Ignacio H. Escapa - One of the best experts on this subject based on the ideXlab platform.
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Towards a whole plant reconstruction for Austrohamia (Cupressaceae): New fossil wood from the Lower Jurassic of Argentina
Review of Palaeobotany and Palynology, 2016Co-Authors: Josefina Bodnar, Ignacio H. EscapaAbstract:Abstract Early diversification of modern conifer lineages occurred during the Late Triassic and Early Jurassic, and worldwide ecosystems were dominated by conifers throughout the Jurassic. The knowledge about the palaeobiology and palaeoecology of basal representatives of those clades, however, has only recently begun to be developed due to the relative scarcity of complete plant reconstructions for many of these conifer families. In regards to the Cupressaceae sensu lato, some reconstructions have been proposed, although none has linked all plant organs. One of the oldest records of this family is the genus Austrohamia , described from the Lower Jurassic of Argentina and China. The original material consists of impressions of leafy branches, organically attached to ovulate and pollen cones. This conifer has a combination of characters that support its assignation to the Cunninghamioideae subfamily, the most basal member of the Cupressaceae stem group. In this paper, we describe permineralized woods from the same strata where Austrohamia minuta was found in the Canadon Asfalto Basin, Chubut Province, Argentina. The fossil woods were assigned to the genus Protaxodioxylon , due to homoxylic pycnoxylic secondary xylem, with distinct growth rings, radial tracheid pitting of mixed type, abundant axial parenchyma, taxodioid cross-fields and uniseriate homocellular rays. Consistent with the differences in other Protaxodioxylon species, we propose a new specific taxon for the Patagonian specimens. This genus has often been related to the taxodiaceous Cupressaceae. This linkage, together with the fact that all the conifer impressions from these strata correspond to Austrohamia , reinforces the idea that the wood belongs to the same biological entity as A. minuta . From this interpretation, Austrohamia represents the most complete Mesozoic Cupressaceae to date.
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A new genus of the Cupressaceae (sensu lato) from the Jurassic of Patagonia: Implications for conifer megasporangiate cone homologies
Review of Palaeobotany and Palynology, 2008Co-Authors: Ignacio H. Escapa, Rubén Cúneo, Brian J. AxsmithAbstract:Abstract A new conifer, Austrohamia minuta , gen. et sp. nov., from the Jurassic of Chubut province, Argentina, is described and proposed as the type species of a new genus of the Cupressaceae s.l. The material consists of impressions represented by well-preserved leafy twigs and branches as well as ovulate and pollen cones. The ovulate cones show a simple organization with helically arranged bracts, each bearing one or two inverted ovules on their adaxial surfaces. Pollen cones occur in terminal clusters subtended by modified leaves. This conifer possesses a combination of characters indicating placement within the basal Cupressaceae ( i.e. the former “Taxodiaceae”). This conclusion is supported by a phylogenetic analysis that places the Argentinean fossil close to the extant genera Athrotaxis and Cunninghamia , and the fossil genera Elatides and Sewardiodendron . In this context some classical characters in conifer systematics are reconsidered in order to clarify their homologies and significance in the early evolution of the Cupressaceae. This represents the first convincing record of the Cupressaceae s.l. in Jurassic floras from the southern hemisphere.
