180 research outputs found
Biomass Accumulation and Carbon Sequestration in Four Different Aged Casuarina equisetifolia Coastal Shelterbelt Plantations in South China
Thousands of kilometers of shelterbelt plantations of Casuarina equisetifolia have been planted to protect the southeast coastline of China. These plantations also play an important role in the regional carbon (C) cycling. In this study, we examined plant biomass increment and C accumulation in four different aged C. equisetifolia plantations in sandy beaches in South China. The C accumulated in the C. equisetifolia plant biomass increased markedly with stand age. The annual rate of C accumulation in the C. equisetifolia plant biomass during 0-3, 3-6, 6-13 and 13-18 years stage was 2.9, 8.2, 4.2 and 1.0 Mg C ha(-1) yr(-1), respectively. Soil organic C (SOC) at the top 1 m soil layer in these plantations was 17.74, 5.14, 6.93, and 11.87 Mg C ha(-1), respectively, with SOC density decreasing with increasing soil depth. Total C storage in the plantation ecosystem averaged 26.57, 38.50, 69.78, and 79.79 Mg C ha(-1) in the 3, 6, 13 and 18-yrs plantation, with most of the C accumulated in the aboveground biomass rather than in the belowground root biomass and soil organic C. Though our results suggest that C. equisetifolia plantations have the characteristics of fast growth, high biomass accumulation, and the potential of high C sequestration despite planting in poor soil conditions, the interactive effects of soil condition, natural disturbance, and human policies on the ecosystem health of the plantation need to be further studied to fully realize the ecological and social benefits of the C equisetifolia shelterbelt forests in South China
Long‐lasting goodshielding at the equatorial ionosphere
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95323/1/jgra20828.pd
Expression of the chemokine receptor CXCR4 in human hepatocellular carcinoma and its role in portal vein tumor thrombus
<p>Abstract</p> <p>Background</p> <p>This study was conducted to investigate the expression of CXCR4 in portal vein tumor thrombus (PVTT) tissue and its possible role in the invasiveness of tumor thrombus cells.</p> <p>Methods</p> <p>We detected differential expression of CXCR4 between PVTT and hepatocellular carcinoma (HCC) by an immunohistochemical assay. Lentivirus-mediated RNA interference and a migration assay were performed on human primary cells derived from PVTT to study the impact of CXCR4 on the invasiveness of HCC.</p> <p>Results</p> <p>The expression of CXCR4 in tumor thrombus tissue was higher than that in HCC tissue. The invasion ratio of PVTT cells was significantly decreased (P < 0.05) after being infected with a CXCR4-targeting siRNA lentivirus, indicating that downregulation of CXCR4 by lentivirus-mediated RNA interference significantly impaired the invasive potential of PVTT.</p> <p>Conclusions</p> <p>These results indicate that CXCR4 is an effective curative target for hepatocellular carcinomas with PVTT.</p
GeoGauss: Strongly Consistent and Light-Coordinated OLTP for Geo-Replicated SQL Database
Multinational enterprises conduct global business that has a demand for
geo-distributed transactional databases. Existing state-of-the-art databases
adopt a sharded master-follower replication architecture. However, the
single-master serving mode incurs massive cross-region writes from clients, and
the sharded architecture requires multiple round-trip acknowledgments (e.g.,
2PC) to ensure atomicity for cross-shard transactions. These limitations drive
us to seek yet another design choice. In this paper, we propose a strongly
consistent OLTP database GeoGauss with full replica multi-master architecture.
To efficiently merge the updates from different master nodes, we propose a
multi-master OCC that unifies data replication and concurrent transaction
processing. By leveraging an epoch-based delta state merge rule and the
optimistic asynchronous execution, GeoGauss ensures strong consistency with
light-coordinated protocol and allows more concurrency with weak isolation,
which are sufficient to meet our needs. Our geo-distributed experimental
results show that GeoGauss achieves 7.06X higher throughput and 17.41X lower
latency than the state-of-the-art geo-distributed database CockroachDB on the
TPC-C benchmark
Mitogenome characterization and diversity of the nangqian grey yak (bos grunniens)
Nangqian grey yak (Bos grunniens) is a unique yak population in Qinghai Province, China.
In this study, the whole mitogenome sequences of 18 Nangqian grey yaks were sequenced
based on the next-generation sequencing (NGS) technology and annotated. The total
length of whole mitogenome sequence is between 16.323 bp and 16.325 bp, including
a non-coding control region (D-loop region), 22 tRNA genes, 13 protein-coding genes
and two rRNA genes (12S rRNA and 16S rRNA). Maternal genetic diversity based on the
mitogenome variations was analyzed. A total of 12 haplotypes were identified among
18 complete mitogenome sequences, the haplotype diversity and nucleotide diversity
of Nangqian grey yak were 0.948±0.033 and 0.001±0.001, respectively. Compared with
the wild yak population and six other domestic yak breeds/populations in China, the
haplotype diversity of Nangqian grey yak population was higher, indicating abundant
maternal genetic diversity in Nangqian grey yak. The phylogenetic tree showed that
Nangqian grey yak was most closely related to Tibet alpine, Xueduo, Changtai, Sibu,
Zhongdian, Tianzhu white, Ashdan, Jinchuan, Jiulong, Pamir, Pali, Qinghai plateau,
Huanhu, Datong, Bazhou and wild yak breeds/populations, closer to Chawula, Muli,
Gannan, Niangya and Yushu yak breeds, but far away from other yak breeds (i.e. Leiwuqi
and Maiwa yak)
ESX Secretion-Associated Protein C From Mycobacterium tuberculosis Induces Macrophage Activation Through the Toll-Like Receptor-4/Mitogen-Activated Protein Kinase Signaling Pathway
Mycobacterium tuberculosis, as a facultative intracellular pathogen, can interact with host macrophages and modulate macrophage function to influence innate and adaptive immunity. Proteins secreted by the ESX-1 secretion system are involved in this relationship. Although the importance of ESX-1 in host-pathogen interactions and virulence is well-known, the primary role is ascribed to EsxA (EAST-6) in mycobacterial pathogenesis and the functions of individual components in the interactions between pathogens and macrophages are still unclear. Here, we investigated the effects of EspC on macrophage activation. The EspC protein is encoded by an espA/C/D cluster, which is not linked to the esx-1 locus, but is essential for the secretion of the major virulence factors of ESX-1, EsxA and EsxB. Our results showed that both EspC protein and EspC overexpression in M. smegmatis induced pro-inflammatory cytokines and enhanced surface marker expression. This mechanism was dependent on Toll-like receptor 4 (TLR4), as demonstrated using EspC-treated macrophages from TLR4−/− mice, leading to decreased pro-inflammatory cytokine secretion and surface marker expression compared with those from wild-type mice. Immunoprecipitation and immunofluorescence assays showed that EspC interacted with TLR4 directly. Moreover, EspC could activate macrophages and promote antigen presentation by inducing mitogen-activated protein kinase (MAPK) phosphorylation and nuclear factor-κB activation. The EspC-induced cytokine expression, surface marker upregulation, and MAPK signaling activation were inhibited when macrophages were blocked with anti-TLR4 antibodies or pretreated with MAPK inhibitors. Furthermore, our results showed that EspC overexpression enhanced the survival of M. smegmatis within macrophages and under stress conditions. Taken together, our results indicated that EspC may be another ESX-1 virulence factor that not only modulates the host innate immune response by activating macrophages through TLR4-dependent MAPK signaling but also plays an important role in the survival of pathogenic mycobacteria in host cells
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