宜昌大老岭种子植物区系研究

大老岭有野生种子植物１２２科４３５属８５６种。对本区科、属和种进行了统计与分析,结果表明,该地区的植物区系性质明显是温带性,且以北温带成分为主,地理成分复杂,仅属就有１３个分布区类型和１７个变型,地理联系广泛,具有古老性强和特有现象不很突出的特点。     

Increased glycolysis in skeletal muscle coordinates with adipose tissue in systemic metabolic homeostasis

Insulin-independent glucose metabolism, including anaerobic glycolysis that is promoted in resistance training, plays critical roles in glucose disposal and systemic metabolic regulation. However, the underlying mechanisms are not completely understood. In this study, through genetically manipulating the glycolytic process by overexpressing human glucose transporter 1 (GLUT1), hexokinase 2 (HK2) and 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3) in mouse skeletal muscle, we examined the impact of enhanced glycolysis in metabolic homeostasis. Enhanced glycolysis in skeletal muscle promoted accelerated glucose disposal, a lean phenotype and a high metabolic rate in mice despite attenuated lipid metabolism in muscle, even under High-Fat diet (HFD). Further study revealed that the glucose metabolite sensor carbohydrate-response element-binding protein (ChREBP) was activated in the highly glycolytic muscle and stimulated the elevation of plasma fibroblast growth factor 21 (FGF21), possibly mediating enhanced lipid oxidation in adipose tissue and contributing to a systemic effect. PFKFB3 was critically involved in promoting the glucose-sensing mechanism in myocytes. Thus, a high level of glycolysis in skeletal muscle may be intrinsically coupled to distal lipid metabolism through intracellular glucose sensing. This study provides novel insights for the benefit of resistance training and for manipulating insulin-independent glucose metabolism.     

Clonal immune responses of Mycobacterium-specific γδ T cells in tuberculous and non-tuberculous tissues during M. tuberculosis infection

Background

We previously demonstrated that unvaccinated macaques infected with large-dose M.tuberculosis(Mtb) exhibited delays for pulmonary trafficking of Ag-specific αβ and γδ T effector cells, and developed severe lung tuberculosis(TB) and “secondary” Mtb infection in remote organs such as liver and kidney. Despite delays in lungs, local immunity in remote organs may accumulate since progressive immune activation after pulmonary Mtb infection may allow IFNγ-producing γδ T cells to adequately develop and traffic to lately-infected remote organs. As initial efforts to test this hypothesis, we comparatively examined TCR repertoire/clonality, tissue trafficking and effector function of Vγ2Vδ2 T cells in lung with severe TB and in liver/kidney without apparent TB.

Methodology/Principal Findings

We utilized conventional infection-immunity approaches in macaque TB model, and employed our decades-long expertise for TCR repertoire analyses. TCR repertoires in Vγ2Vδ2 T-cell subpopulation were broad during primary Mtb infection as most TCR clones found in lymphoid system, lung, kidney and liver were distinct. Polyclonally-expanded Vγ2Vδ2 T-cell clones from lymphoid tissues appeared to distribute and localize in lung TB granuloms at the endpoint after Mtb infection by aerosol. Interestingly, some TCR clones appeared to be more predominant than others in lymphocytes from liver or kidney without apparent TB lesions. TCR CDR3 spetratyping revealed such clonal dominance, and the clonal dominance of expanded Vγ2Vδ2 T cells in kidney/liver tissues was associated with undetectable or low-level TB burdens. Furthermore, Vγ2Vδ2 T cells from tissue compartments could mount effector function for producing anti-mycobacterium cytokine.

Conclusion

We were the first to demonstrate clonal immune responses of mycobacterium-specific Vγ2Vδ2 T cells in the lymphoid system, heavily-infected lungs and lately subtly-infected kidneys or livers during primary Mtb infection. While clonally-expanded Vγ2Vδ2 T cells accumulated in lately-infected kidneys/livers without apparent TB lesions, TB burdens or lesions appeared to impact TCR repertoires and tissue trafficking patterns of activated Vγ2Vδ2 T cells.     

Activation of PI3K/AKT and MAPK pathway through a PDGFRβ-dependent feedback loop is involved in rapamycin resistance in hepatocellular carcinoma

Background

Rapamycin is an attractive approach for the treatment and prevention of HCC recurrence after liver transplantation. However, the objective response rates of rapamycin achieved with single-agent therapy were modest, supporting that rapamycin resistance is a frequently observed characteristic of many cancers. Some studies have been devoted to understanding the mechanisms of rapamycin resistance, however, the mechanisms are cell-type-dependent and studies on rapamycin resistance in HCC are extremely limited.

Methodology/Principal Findings

The anti-tumor sensitivity of rapamycin was modest in vitro and in vivo. In both human and rat HCC cells, rapamycin up-regulated the expression and phosphorylation of PDGFRβ in a time and dose-dependent manner as assessed by RT-PCR and western blot analysis. Using siRNA mediated knockdown of PDGFRβ, we confirmed that subsequent activation of AKT and ERK was PDGFRβ-dependent and compromised the anti-tumor activity of rapamycin. Then, blockade of this PDGFRβ-dependent feedback loop by sorafenib enhanced the anti-tumor sensitivity of rapamycin in vitro and in an immunocompetent orthotopic rat model of HCC.

Conclusions

Activation of PI3K/AKT and MAPK pathway through a PDGFRβ-dependent feedback loop compromises the anti-tumor activity of rapamycin in HCC, and blockade of this feedback loop by sorafenib is an attractive approach to improve the anti-tumor effect of rapamycin, particularly in preventing or treating HCC recurrence after liver transplantation.     

Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations

The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate.     

Survivin regulates the expression of VEGF-C in lymphatic metastasis of breast cancer

ABSTRACT: BACKGROUND: As a known regulator of apoptosis, survivin has positive relationship with lymphatic metastasis in breast cancer. This study aims to detect the difference in expression between survivin and vascular endothelial growth factor-C (VEGF-C) in treated breast cancer cells and tissues, and to analyze the correlation among survivin, VEGF-C and lymphatic metastasis. METHODS: Plasmid with survivin and VEGF-C shRNA and lentivirus with survivin gene were constructed and transfected into breast cancer cell ZR-75-30. Then the expressions of the two genes were examined using western blot analysis and real-time PCR. The change of invasiveness of breast cancer cells was assessed using matrigel invasion assay. Using immunohistochemistry, the expression of survivin and VEGF-C were analyzed in 108 clinical breast cancer cases with breast cancer tissue and lymph node. RESULTS: Survivin regulated the expression of VEGF-C at both protein and mRNA levels in breast cancer cells. Immunohistochemical analysis showed that the level of VEGF-C expression was significantly related with that of survivin in breast cancer tissues (p<0.05). VEGF-C was found to participate in the process of breast cancer cells invasion mediated by survivin. The co-expression of the two and the single expression of any one took significant difference in positive lymph node (p<0.05). CONCLUSIONS: Survivin takes an important part in regulating the expression of VEGF-C. VEGF-C could influence the invasive ability mediated by survivin. The co-expression of survivin and VEGF-C is more statistically significant to assess lymphatic metastasis in breast cancer. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9193530897100952.     

The BMP1 gene is essential for pathogenicity in the gray mold fungus Botrytis cinerea

In Magnaporthe grisea, a well-conserved mitogen-activated protein (MAP) kinase gene, PMK1, is essential for fungal pathogenesis. In this study, we tested whether the same MAP kinase is essential for plant infection in the gray mold fungus Botrytis cinerea, a necrotrophic pathogen that employs infection mechanisms different from those of M. grisea. We used a polymerase chain reaction-based approach to isolate MAP kinase homologues from B. cinerea. The Botrytis MAP kinase required for pathogenesis (BMP) MAP kinase gene is highly homologous to the M. grisea PMK1. BMP1 is a single-copy gene. bmp1 gene replacement mutants produced normal conidia and mycelia but were reduced in growth rate on nutrient-rich medium. bmp1 mutants were nonpathogenic on carnation flowers and tomato leaves. Re-introduction of the wild-type BMP1 allele into the bmp1 mutant restored both normal growth rate and pathogenicity. Further studies indicated that conidia from bmp1 mutants germinated on plant surfaces but failed to penetrate and macerate plant tissues. bmp1 mutants also appeared to be defective in infecting through wounds. These results indicated that BMP1 is essential for plant infection in B. cinerea, and this MAP kinase pathway may be widely conserved in pathogenic fungi for regulating infection processes.     

Mosaic genome architecture of the Anopheles gambiae species complex

Background

Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.

Methodology

We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.

Principal Findings

We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.

Conclusions

Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism.