分类： 地球科学 >> 地球科学史 提交时间： 2020-10-20 合作期刊: 《干旱区科学》
摘要： To date, much of research on revegetation has focused on soil microorganisms due to their contributions in the formation of soil and soil remediation process. However, little is known about the soil bacteria and their functions respond to the diverse vegetational types in the process of vegetation restoration. Effects of dominated vegetation, i.e., Artemisia halodendron Turcz Ex Bess, Caragana microphylla Lam., Hedysarum fruticosum Pall. and Pinus sylvestris L. on bacterial community structures and their potential functions in the Hulun Buir Sandy Land, China were determined using high-throughput 16S rRNA gene sequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) in 2015. Although the dominant phyla of soil bacterial community among different types of vegetation, including Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes and Firmicutes, were similar, the relative abundance of these dominant groups significantly differed, indicating that different types of vegetation might result in variations in the composition of soil bacterial community. In addition, functional genes of bacterial populations were similar among different types of vegetation, whereas its relative abundance was significantly differed. Most carbon fixation genes showed a high relative abundance in P. sylvestris, vs. recalcitrant carbon decomposition genes in A. halodendron, suggesting the variations in carbon cycling potential of different types of vegetation. Abundance of assimilatory nitrate reduction genes was the highest in P. sylvestris, vs. dissimilatory nitrate reduction and nitrate reductase genes in A. halodendron, indicating higher nitrogen gasification loss and lower nitrogen utilization gene functions in A. halodendron. The structures and functional genes of soil bacterial community showed marked sensitivities to different plant species, presenting the potentials for regulating soil carbon and nitrogen cycling.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A mass paucity of compact objects in the range of $\sim 2-5 ~M_\odot$ has been suggested by X-ray binary observations, namely, the "lower mass gap". Gravitational wave detections have unlocked another mass measurement method, and aLIGO/Virgo has observed some candidates in the gap. We revisit the numerical simulations on the core-collapse supernovae (CCSNe) for $\sim 20-40~M_\odot$ progenitor stars with differently initial explosion energies. As a result, the lower explosion energy naturally causes more efficient fallback accretion for low-metallicity progenitors, and then the newborn black holes (BHs) in the center of the CCSNe can escape from the gap, but neutron stars cannot easily collapse into BHs in the gap; nevertheless, the final remnants of the solar-metallicity progenitors stick to the gap. If we consider that only drastic CCSNe can be observed and that those with lower explosion energies are universal, the lower mass gap can be reasonably built. The width and depth of the gap are mainly determined by the typical CCSN initial explosion energy and metallicity. One can expect that the future multi-messenger observations of compact objects delineate the shape of the gap, which might constrain the properties of the CCSNe and their progenitors.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-12
摘要： Tandem-arranged PDZ [PSD-95 (postsynaptic density-95), Dlg (discs large homologue) and ZO-1 (zonula occludens-1)] domains often form structural and functional supramodules with distinct target-binding properties. In the present study, we found that the two PDZ domains within the PDZ34 tandem of Scribble, a cell polarity regulator, tightly pack in a 'front-to-back' mode to form a compact supramodule. Although PDZ4 contains a distorted alpha B/beta B pocket, the attachment of PDZ4 to PDZ3 generates an unexpected interdomain pocket that is adjacent to and integrates with the canonical aB/aB pocket of PDZ3 to form an expanded target-binding groove. The structure of the PDZ34-target peptide complex further demonstrated that the peptide binds to this expanded target-binding groove with its upstream residues anchoring into the interdomain pocket directly. Mutations of the interdomain pocket and disruptions of the PDZ34 supramodule both interfere with its target-binding capacity. Therefore, the interdomain interface between the PDZ34 supramodule is intrinsically required for its target recognition and determines its target-binding specificity. This interdomain interface-mediated specific recognition may represent a novel mode of target recognition and would broaden the target-binding versatility for PDZ supramodules. The supramodular nature and target recognitionmode of the PDZ34 tandem found in the present study would also help to identify the new binding partners of Scribble and thus may direct further research on the PDZ domain-mediated assembly of Scribble polarity complexes.
分类： 生物学 >> 生物物理学 >> 生物物理、生物化学与分子生物学 提交时间： 2016-05-15
Wu, Fan
Qi, Xin
Zhao, Hong-Yu
Wang, Zheng
Zhang, Hui
Ren, Jin-Qi
Feng, Wei
Hu, Jun-Jie
Zhang, Hong
Watanabe, Yasunori
Fujioka, Yuko
Noda, Nobuo N.
Guo, Xiang-Yang
Fang, Tian-Cheng
Wang, Peng
Shen, Yu-Xian
摘要： Multicellular organisms have multiple homologs of the yeast ATG8 gene, but the differential roles of these homologs in autophagy during development remain largely unknown. Here we investigated structure/function relationships in the two C. elegans Atg8 homologs, LGG-1 and LGG-2. lgg-1 is essential for degradation of protein aggregates, while lgg-2 has cargo-specific and developmental-stage-specific roles in aggregate degradation. Crystallography revealed that the N-terminal tails of LGG-1 and LGG-2 adopt the closed and open form, respectively. LGG-1 and LGG-2 interact differentially with autophagy substrates and Atg proteins, many of which carry a LIR motif. LGG-1 and LGG-2 have structurally distinct substrate binding pockets that prefer different residues in the interacting LIR motif, thus influencing binding specificity. Lipidated LGG-1 and LGG-2 possess distinct membrane tethering and fusion activities, which may result from the N-terminal differences. Our study reveals the differential function of two ATG8 homologs in autophagy during C. elegans development.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Kong, Ruirui
Wen, Pushuai
Liu, Jianghong
Zhu, Li
Wu, Jane Y.
Yi, Fengshuang
Ren, Jinqi
Feng, Wei
Yi, Fengshuang
Chen, Xiaoping
Wu, Jane Y.
Li, Xiaofei
Nie, Yongzhan
Wu, Kaichun
Fan, Daiming
Zhu, Li
Nie, Yongzhan
Wu, Kaichun
Fan, Daiming
Zhu, Li
摘要： Emerging evidence indicates that the neuronal guidance molecule SLIT plays a role in tumor suppression, as SLIT-encoding genes are inactivated in several types of cancer, including lung cancer; however, it is not clear how SLIT functions in lung cancer. Here, our data show that SLIT inhibits cancer cell migration by activating RhoA and that myosin 9b (Myo9b) is a ROBO-interacting protein that suppresses RhoA activity in lung cancer cells. Structural analyses revealed that the RhoGAP domain of Myo9b contains a unique patch that specifically recognizes RhoA. We also determined that the ROBO Intracellular domain interacts with the Myo9b RhoGAP domain and inhibits its activity; therefore, SLIT-dependent activation of RhoA is mediated by ROBO inhibition of Myo9b. In a murine model, compared with control lung cancer cells, SLIT-expressing cells had a decreased capacity for tumor formation and lung metastasis. Evaluation of human lung cancer and adjacent nontumor tissues revealed that Myo9b is upregulated in the cancer tissue. Moreover, elevated Myo9b expression was associated with lung cancer progression and poor prognosis. Together, our data identify Myo9b as a key player in lung cancer and as a ROBO-interacting protein in what is, to the best of our knowledge, a newly defined SLIT/ROBO/Myo9b/RhoA signaling pathway that restricts lung cancer progression and metastasis. Additionally, our work suggests that targeting the SLIT/ROBO/Myo9b/RhoA pathway has potential as a diagnostic and therapeutic strategy for lung cancer.
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