Experimental warming shifts coupling of carbon and nitrogen cycles in an alpine meadow

增温对高寒草甸生态系统碳氮循环耦合关系的影响 陆地生态系统碳吸收受土壤氮素可用性的调节。然而,全球变化背景下的不同生态系统组分的碳氮比及其所反映的碳氮循环耦合关系尚不十分清楚。本文运用数据同化的方法,将一个高寒草甸增温试验的14组数据同化到草地生态系统模型中,从而评估了增温如何影响陆地生态系统的碳氮循环耦合关系。研究结果表明,增温提高了土壤氮素的有效性,降低了土壤活性碳库的碳氮比,导致植物对土壤氮的吸收增加。但是由于植物叶片吸收的碳比吸收的氮增加更多,使得叶片中碳氮比增加,而根部的碳输入增加则低于氮的增加,导致根部的碳氮比减少。同时,增温降低了凋落物碳氮比,可能是在土壤高氮有效性的条件下,凋落物氮的固定得到增强;而且增温加速了凋落物的分解。同时增温还增加了慢速土壤有机质的碳氮比,使得该土壤碳库的碳固存潜力增大。由于大多数模型在不同的环境中通常使用相对固定的碳氮比,本研究所发现的气候变暖条件下碳氮比的差异变化可为模型参数化提供一个有效的参考,有利于模型对未来气候变化背景下生态系统碳氮耦合关系响应的预测。     

Targeting IFN-γ-inducible lysosomal thiol reductase overcomes chemoresistance in AML through regulating the ROS-mediated mitochondrial damage

The persistence of leukemia stem cells (LSCs) is one of the leading causes of chemoresistance in acute myeloid leukemia (AML). To explore the factors important in LSC-mediated resistance, we use mass spectrometry to screen the factors related to LSC chemoresistance and defined IFN-γ-inducible lysosomal thiol reductase (GILT) as a candidate. We found that the GILT expression was upregulated in chemoresistant CD34+ AML cells. Loss of function studies demonstrated that silencing of GILT in AML cells sensitized them to Ara-C treatment both in vitro and in vivo. Further mechanistic findings revealed that the ROS-mediated mitochondrial damage plays a pivotal role in inducing apoptosis of GILT-inhibited AML cells after Ara-C treatment. The inactivation of PI3K/Akt/ nuclear factor erythroid 2-related factor 2 (NRF2) pathway, causing reduced generation of antioxidants such as SOD2 and leading to a shifted ratio of GSH/GSSG to the oxidized form, contributed to the over-physiological oxidative status in the absence of GILT. The prognostic value of GILT was also validated in AML patients. Taken together, our work demonstrated that the inhibition of GILT increases AML chemo-sensitivity through elevating ROS level and induce oxidative mitochondrial damage-mediated apoptosis, and inhibition of the PI3K/Akt/NRF2 pathway enhances the intracellular oxidative state by disrupting redox homeostasis, providing a potentially effective way to overcome chemoresistance of AML.     

七种云南地衣植物的化学成分

本文报道分属于三个科的七种云南产地衣植物的化学成分。这些植物是亚洲树发(Alectoria asiatica DR.)、沟树发(Alectoria sulcata Nyl.)、长茎松萝(Usnea longissimaAch.)、胡子松萝(Usnea comosa(Ach.)Rohl.)、林石蕊(Cladonia arbuscula(Rabh.)Rabh.)、砖孢发(Oropogon loxensis(Fee.)Th.Fr.)和卷梢雪花衣(Anaptychiaboryi(Fee.)Mass.)。根据光谱数据测定,其化学成分为:松萝酸(Usnic acid)(1),维任西酸(Virensic acid)(2),赤星衣酸乙酯(Ethyl haematommate)(3),瑞藏酸(Rhizonic acid)(4),赤星衣酸(Haematommic acid)(5),扁枝衣酸乙酯(Ethyleverninate)(6),黑茶渍素(Atranorin)(7)和泽屋萜(Zeorin)(8)。上述资料,对开发利用这些植物资源提供了科学依据。     

Development and characterization of 33 polymorphic microsatellite markers in Trachurus japonicus by SLAF-seq technology

Trachurus japonicus is an economically important fish in the northwestern Pacific Ocean. However, its resources have declined seriously and there is an urgent need for a wide-range of investigations of the existing genetic resources. This requires a large number of diverse molecular markers with high discriminating power. In this study, we identified 43,264 perfect SSRs in T. japonicus genome using SLAF-seq technology. Of these, we randomly selected 106 SSRs (tri-nucleotide to hexa-nucleotide) to test for polymorphism. Eventually, we successfully developed a total of 33 loci including 8 tri-nucleotide and 25 long repeat motifs (tetra-nucleotide to hexa-nucleotide). The number of alleles (Na) of these loci ranged from 4 to 24 (mean 12.6). The observed heterozygosity (Ho) and expected heterozygosity (He) varied from 0.258 to 0.969 (mean 0.723) and from 0.452 to 0.962 (mean 0.827), respectively. All loci except TJ6-7 were highly informative (PIC > 0.5). These results showed that the shortlisted 33 loci exhibited moderate to relatively high genetic diversity, of which 18 were regarded as highly polymorphic and well-resolved. In summary, these diverse and potential microsatellites detected in our study provide substantial genetic basis for the screening of polymorphic SSR markers of T. japonicus and also provide a powerful tool to perform further studies on the genetic resource assessment and conservation of T. japonicus.     

Developmental competence of frozen-thawed yak (Bos grunniens) oocytes followed by in vitro maturation and fertilization

In the present study, we examined the ability of immature germinal vesicle (GV) and subjected to in vitro matured (MII) yak oocytes to survive after cryopreservation as well as their subsequent development following in vitro maturation and fertilization. Both GV and MII oocytes were cryopreserved by using two different vitrification solutions (VS); VS-I contained 10% ethylene glycol (EG) and 10% dimethylsulfoxide (DMSO) in TCM-199 + 20% (v/v) fetal calf serum (FCS) whereas VS-II contained 40% EG + 18% Ficoll + 0.5 M sucrose in TCM-199 + 20% FCS. The percentage of oocytes found to be morphologically normal was greater (P < 0.01) in VS-I group than in VS-II group. Rates of cleavage (30.6–42.2%) and blastocyst formation (2.9–8.9%) did not differ among groups, but were lower than in unfrozen control (55.7% and 25.4%, P < 0.01). These results show that a combination of EG and DMSO or EG, Ficoll and sucrose can be used to cryopreserve yak oocytes in French straws.     

Repression of SIRT1 Promotes the Differentiation of Mouse Induced Pluripotent Stem Cells into Neural Stem Cells

The use of transplanting functional neural stem cells (NSCs) derived from induced pluripotent stem cells (iPSCs) has increased for the treatment of brain diseases. As such, it is important to understand the molecular mechanisms that promote NSCs differentiation of iPSCs for future NSC-based therapies. Sirtuin 1 (SIRT1), a NAD⁺-dependent protein deacetylase, has attracted significant attention over the past decade due to its prominent role in processes including organ development, longevity, and cancer. However, it remains unclear whether SIRT1 plays a role in the differentiation of mouse iPSCs toward NSCs. In this study, we produced NSCs from mouse iPSCs using serum-free medium supplemented with retinoic acid. We then assessed changes in the expression of SIRT1 and microRNA-34a, which regulates SIRT1 expression. Moreover, we used a SIRT1 inhibitor to investigate the role of SIRT1 in NSCs differentiation of iPSCs. Data revealed that the expression of SIRT1 decreased, whereas miRNAs-34a increased, during this process. In addition, the inhibition of SIRT1 enhanced the generation of NSCs and mature neurocytes. This suggests that SIRT1 negatively regulated the differentiation of mouse iPSCs into NSCs, and that this process may be regulated by miRNA-34a.