Although many species have gone extinct,their genetic components might exist in extant species because of ancient hybridization.Via advances in genome sequencing and development of modern population genetics,one can f...Although many species have gone extinct,their genetic components might exist in extant species because of ancient hybridization.Via advances in genome sequencing and development of modern population genetics,one can find the legacy of unknown or extinct species in the context of available genomes from extant species.Such discovery can be used as a strategy to search for hidden species or fossils in conservation biology and archeology,gain novel insight into complex evolutionary history,and provide the new sources of genetic variation for breeding and trait improvement in agriculture.展开更多
Clam shrimps are large bivalved branchiopod crustacean. They first occurred in the Devonian, and flourished during the Mesozoic in Asia. Fossil clam shrimps play an important role in the subdivision and correlation of...Clam shrimps are large bivalved branchiopod crustacean. They first occurred in the Devonian, and flourished during the Mesozoic in Asia. Fossil clam shrimps play an important role in the subdivision and correlation of non-marine fossil-bearing strata. The phosphatized carapaces or carapace external/internal moulds are the main objects for taxonomical studies. The delicate ornament and the ontogenetically developing morphological patterns on the growth bands of carapaces are the main fossil taxonomic criteria. While modern clam shrimp taxonomy is based on soft body morphological features and molecular data, which could not be found in the fossil records. This makes it difficult to discuss the fossil and modern clam shrimp phylogenetic relationship. Nowadays scanning electron microscopes are widely available, and can play an important role in investigating clam shrimp carapace morphology which could be common language to integrate fossil and modern taxonomy.展开更多
The selective nucleoside synthesis through direct condensation between nucleobase and unactivated sugar in aqueous media has long been a formidable obstacle for the early chemical transformations hypothesized to const...The selective nucleoside synthesis through direct condensation between nucleobase and unactivated sugar in aqueous media has long been a formidable obstacle for the early chemical transformations hypothesized to construct the RNAWorld,due to product complexity and the low selectivity of the desired isomer.The preference ofβ-furanoside,the extant RNA component,has never been documented.Here we report an aqueous ribosylation mediated by divalent transition-metal ions,which unprecedentedly enhances the selectivity of furanosyl ribonucleosides as opposed to the traditionally predominating pyranosyl ones,with the furanoside/pyranoside ratio reaching up to 9/1.Furthermore,β-furanoside stands out for the first time as the most prevalent isomer in the presence of zinc and ammonium salts.The mechanism of this selectivity is elucidated with density functional theory calculations.The selectivity forβ-furanoside can be further elevated via the adsorption on a zinc mineral.These findings exhibit as the first example that the selection of nucleosides with the desired,canonical configuration might be completed in the early stage of the RNA-forming process as opposed to later evolution,promoted by simple and widespread transition-metal minerals.The study may also find its value in synthetic chemistry as a guideline for developing a sustainable and selective glycosylation process.展开更多
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA2004010302)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(2019QZKK05010703)+1 种基金the Young Academic and Technical Leagder Raising Foundation of Yunnan Province(2018HB033)D.-D.W.was supported by the National Natural Science Foundation of China(31822048 and 31621062)。
文摘Although many species have gone extinct,their genetic components might exist in extant species because of ancient hybridization.Via advances in genome sequencing and development of modern population genetics,one can find the legacy of unknown or extinct species in the context of available genomes from extant species.Such discovery can be used as a strategy to search for hidden species or fossils in conservation biology and archeology,gain novel insight into complex evolutionary history,and provide the new sources of genetic variation for breeding and trait improvement in agriculture.
文摘Clam shrimps are large bivalved branchiopod crustacean. They first occurred in the Devonian, and flourished during the Mesozoic in Asia. Fossil clam shrimps play an important role in the subdivision and correlation of non-marine fossil-bearing strata. The phosphatized carapaces or carapace external/internal moulds are the main objects for taxonomical studies. The delicate ornament and the ontogenetically developing morphological patterns on the growth bands of carapaces are the main fossil taxonomic criteria. While modern clam shrimp taxonomy is based on soft body morphological features and molecular data, which could not be found in the fossil records. This makes it difficult to discuss the fossil and modern clam shrimp phylogenetic relationship. Nowadays scanning electron microscopes are widely available, and can play an important role in investigating clam shrimp carapace morphology which could be common language to integrate fossil and modern taxonomy.
基金supported by the National Natural Science Foundation of China(21872068)the“GeoX”Interdisciplinary Research Funds for the Frontiers Science Center for Critical Earth Material Cycling of Nanjing University(0205-14380316)+1 种基金the Technology Innovation Fund of Nanjing University(0205-14913426)the Postgraduate Research&Practice Innovation Program of Jiangsu Province。
文摘The selective nucleoside synthesis through direct condensation between nucleobase and unactivated sugar in aqueous media has long been a formidable obstacle for the early chemical transformations hypothesized to construct the RNAWorld,due to product complexity and the low selectivity of the desired isomer.The preference ofβ-furanoside,the extant RNA component,has never been documented.Here we report an aqueous ribosylation mediated by divalent transition-metal ions,which unprecedentedly enhances the selectivity of furanosyl ribonucleosides as opposed to the traditionally predominating pyranosyl ones,with the furanoside/pyranoside ratio reaching up to 9/1.Furthermore,β-furanoside stands out for the first time as the most prevalent isomer in the presence of zinc and ammonium salts.The mechanism of this selectivity is elucidated with density functional theory calculations.The selectivity forβ-furanoside can be further elevated via the adsorption on a zinc mineral.These findings exhibit as the first example that the selection of nucleosides with the desired,canonical configuration might be completed in the early stage of the RNA-forming process as opposed to later evolution,promoted by simple and widespread transition-metal minerals.The study may also find its value in synthetic chemistry as a guideline for developing a sustainable and selective glycosylation process.
