2.0 Ga orogenic graphite deposits and associated 13C-enriched meta-carbonate rocks from South China Craton:Implications for global Lomagundi event

The Lomagundi(-Jatuli)event,characterized by extremely high positive global inorganic carbon isotope excursion at about 2.2 billion years ago,is pivotal in investigating the causes and consequences of great oxygenation event,inventory and sequestration of carbon on the Earth’s surface,evolution of life,and more profoundly tectonic control on Earth’s environment.However,the reasons that caused the isotopic excursion are not resolved yet.Herein,we report the discovery of meta-carbonate rocks with distinct positive carbon isotopic excursion from the Paleoproterozoic continental collision zone of the Kongling Complex,South China Craton.The δ^(13)C_(V-PDB) values for meta-carbonate rocks show positive values in the range from+5.5‰to+11.6‰,whereas the δ^(13)C_(V-PDB) values of associated graphite deposits range from-25.8‰to-9.5‰.Zircon U-Pb-Hf isotopes from zircon-bearing meta-carbonate sample yielded weighted average _(207)Pb/_(206)Pb age of 2001.3±9.5 Ma,with correspondingε_(Hf)(t)range from-7.05 to-3.16,comparable to the values of local 2.9–2.6 Ga basement rocks.Geochemical characteristics of meta-carbonate rocks,such as their rare earth element patterns and the trace element parameters of La,Ce,Eu,and Gd anomalies and Y/Ho ratio,suggest that the carbonate deposition took place in passive continental margin in association with large volumes of organic carbon.The extensive graphite deposits from Kongling Complex in South China Craton,their equivalents in the North China Craton and elsewhere across the globe prove that the burial of ^(12)C-enriched organic carbon has eventually resulted in the global enrichment of ^(13)C in the atmospheric CO_(2),which is recorded in the marine carbonate rocks.Isotopic mass balance estimates indicate that more than half of the organic carbon was buried during the oceanic closure.Hence,the observed global shift could be directly related to the continent collision event in greater China,thus resolving the long-standing paradox of the Lomagundi global positive carbon isotope excursion.Moreover,the present results suggest that orogenesis play a significant role in sequestration of carbon into the continental crust.

SIRT2 interacts with DDX24 to promote nasopharyngeal carcinoma growth

Background:Nasopharyngeal carcinoma(NPC)is one of the most prevalent cancers in Southeast Asia.Sirtuin 2(SIRT2)is a member of the NAD+-dependent deacetylase family and has been shown to play important roles in numerous biological processes.However,Its function in NPC remains uncertain.The primary aim of this study is to clarify the role of SIRT2 in NPC.Methods:In this research,we examined the effect of SIRT2 silencing on NPC cell proliferation and colony formation using vitro NPC cell lines.Co-immunoprecipitation and mass spectrometry was applied to identify SIRT2-interacting proteins in NPC cells.Results:In comparison to nasopharyngeal epithelial NP69 cells,SIRT2 was up-regulated in multiple NPC cell lines,particularly in CNE2 cells.SIRT2 knockdown abrogated CNE2 cell proliferation and colony formation,whereas SIRT2 overexpression promoted HNE1 cell proliferation and colony formation.The SIRT2-interacting proteins were gathered in gene expression and regulation processes including RNA processing and translation.Among the SIRT2-interacting proteins,there were multiple DEAD-box(DDX)family members.Of note,silencing of DDX24 phenocopied the effect of SIRT2 knockdown on NPC growth.Overexpression of DDX24 restored SIRT2-depleted CNE2 cells to proliferative and colony formation.Conclusions:Our study indicates that SIRT2 can interact with DDX24 to enhance NPC growth.The clinical relevance of SIRT2 and DDX24 in NPC warrants further investigation.

Study on Virus-free and Rapid Propagation Technology of Artemisia selengensis sp.in Yangxin County

[Objectives]This study was conducted to culture virus-free tissue culture plantlets of mid-maturing green-stalk Artemisia selengensis sp.varieties in Yangxin County.[Methods]With bud tips of A.selengensis in Yangxin as explants and MS as the basal medium,screening and proportioning of plant growth regulators were performed to establish a virus-free and rapid propagation system for mid-maturing green-stalk varieties of A.selengensis in Yangxin.[Results]The optimal callus induction medium,adventitious shoot differentiation medium,adventitious shoot elongation medium and rooting medium for explants were MS+6-BA 1.0 mg/L+NAA 0.5 mg/L+sucrose 25 g/L+agar 7 g/L,MS+6-BA 0.1 mg/L+NAA 0.1 mg/L+sucrose 25 g/L+agar 7 g/L,MS+6-BA 0.02 mg/L+NAA 0.02 mg/L+sucrose 25 g/L+agar 7 g/L and 1/2 MS+NAA 0.05 mg/L+sucrose 25 g/L+agar 7 g/L,respectively,and the seedling rate reached more than 95%.The culture conditions were as follows:temperature(25±2)℃,relative humidity 85%,illumination intensity 3000 lx,and illumination time 14 h/d.[Conclusions]This study has important practical significance for the purification and rejuvenation and large-scale industrial breeding of Yangxin A.selengensis seedlings.

How Do the Nucleons Pack in an Atomic Nucleus?

A nuclear structure model of “ring plus extra nucleon” is proposed. For nuclei larger than 4He, protons (P) and neutrons (N) are basically bound alternatively to form a ZP + ZN ring. The ring folds with a “bond angle” of 90° for every 3 continuous nucleons to make the nucleons packed densely. Extra N(‘s) can bind to ring-P with the same “bond angle” and “bond distance”. When 2 or more P’s are geometrically available, the extra N tends to be stable. Extra P can bind with ring N in a similar way when the ratio of N/P < 1 although the binding is weaker than that of extra N. Even-Z rings, as well as normal even-even nuclei, always have superimposed gravity centers of P and N;while for odd-Z rings, as well as all odd-A (A: number of nucleon) nuclei, the centers of P and N must be eccentric. The eccentricity results in a depression of binding energy (EB) and therefore odd and even Z dependent zigzag features of EB/A. This can be well explained by the shift of eccentricity by extra nucleons. Symmetrical center may present in even-Z rings and normal even-even nuclei. While for odd-Z ring, only antisymmetric center (every P can find an N through the center and vice versa) is possible. Based on this model, a pair of mirror nuclei, PX+nNX and PXNX+n, should be equivalent in packing structure just like black-white photo and the negative film. Therefore, an identical spin and parity was confirmed for any pair. In addition, the EB/A difference of mirror nuclei pair is nearly a constant of 0.184n MeV. Many other facts can also be easily understood from this model, such as the neutron halo, the unusual stability sequence of 9Be, 7Be and 8Be and so on.