Epigenetic regulation of HIF-1α in renal cancer cells involves HIF-1α/2α binding to a reverse hypoxia-response element

Inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene underlies the majority of sporadic clear cell renal cell carcinomas (CCRCCs) and is also responsible for the hereditary VHL cancer syndrome. VHL loss of function results in constitutive stabilization of hypoxia-inducible factors (HIF-1α and HIF-2α) due to insufficient proteolysis in the presence of oxygen. This activates multiple genes relevant to tumorigenesis, allowing cells to acquire further mutations and undergo malignant transformation. However, the specific role of each HIF-α subunit in CCRCC tumorigenesis is not yet well understood. The current paradigm supports that in the first stages of CCRCC formation the stabilization of HIF-1α is dominant and this limits proliferation, but later on HIF-2α increases and this induces a more aggressive cell behavior. Understanding how this transition happens is highly relevant, as it may provide novel ways to treat these cancers. Here, we show that VHL inactivation in CCRCC cells results in HIF-1α/2α-dependent downregulation of HIF-1α mRNA through direct binding of either subunit to a reverse hypoxia-response element in the HIF-1α proximal promoter. This binding activates a series of repressive histone modification marks including histone 3 lysine 27 trimethylation (H3K27me3) to make the changes stable, and if overturned reduces CCRCC cell proliferation due to excessive HIF-1α expression level. Our findings thus help understand how HIF-α subunits influence each other and also reinforce the idea that epigenetic mechanisms are a key step of CCRCC progression.

Incommensurate spin-density wave order in electron-doped BaFe2 As2 superconductors

Neutron diffraction studies of Ba(Fe(1-x)Co(x))(2)As)(2) reveal that commensurate antiferromagnetic order gives way to incommensurate magnetic order for Co compositions between 0.056 < x < 0.06. The incommensurability has the form of a small transverse splitting (0, ± ε, 0) from the commensurate antiferromagnetic propagation vector Q(AFM) = (1,0,1) (in orthorhombic notation) where ε ≈ 0.02-0.03 and is composition dependent. The results are consistent with the formation of a spin-density wave driven by Fermi surface nesting of electron and hole pockets and confirm the itinerant nature of magnetism in the iron arsenide superconductors.

Intrapericardial pheochromocytoma

Pheochromocytoma is a catecholamine-secreting tumor. Most cases are intra-adrenal, and intrapericardial pheochromocytomas are extremely rare. We report a case of a 30-year-old woman with a seven-year history of hypertension. The concentration of blood noradrenaline was found to be elevated. Chest computed tomography scan showed a limited bulge in the superior border of the right atrium. Magnetic resonance imaging confirmed the existence of a tumor. Coronary arteriography detected a mass near the right atrium, which was nourished by an aberrant branch of the right coronary artery. After preoperative preparation, the patient underwent pericardial tumor resection. Postoperative recovery was uneventful and the patient was successfully discharged 20 days later.

Strain-Induced Elevation of the Spontaneous Polarization in BaTiO3 Thin Films

A manmade ferroelectric-paraelectric heterostructure, a BaTiO3 / SrTiO3 superlattice, was studied to explore the effect of strain on ferroelectricity. An atomically abrupt BaTiO3 / SrTiO3 superlattice was grown on a (001) SrTiO3 substrate by reactive molecular beam epitaxy. Both BaTiO3 and SrTiO3 layers were grown with their individual thicknesses less than the critical thickness for the formation of interfacial misfit dislocations, leaving the entire superlattice fully coherent with the substrate. This resulted in a uniformly and highly strained BaTiO3 layer to study the effect of strain on ferroelectricity. Quantitative high-resolution transmission electron microscopy was employed to examine the atomic positions of cations and anions in the strained BaTiO3 layers. It was found that the relative static displacement of cations (Ti4+, Ba2+) to anions (O2−) is larger than that of bulk BaTiO3. Our observation thus illustrates the strain-induced elevation of spontaneous polarization in BaTiO3 thin films.

Diversity of culturable ericoid mycorrhizal fungi of Rhododendron decorum in Yunnan, China

The diversity of ericoid mycorrhizal fungi isolated from Rhododendron decorum Franch. in Yunnan, southwestern China, was examined for the first time. In total 300 hair-root samples were collected from 13 R. decorum individuals in two adjacent wild population sites and one cultivated population site. Two hundred eighteen slow-growing isolates were obtained; the ability of some to form ericoid mycorrhiza was tested in vitro. One hundred twenty-five isolates formed hyphal structures morphologically corresponding to ericoid mycorrhiza, and these were determined by morphological and molecular means to belong to 12 fungal species. There were hardly any differences in species among the three sampled populations. The sequences of several isolates were similar to those of Oidiodendron maius and ericoid mycorrhizal fungi from Helotiales, accounting respectively for 18.4% and 24.8% of the total culturable ericoid mycorrhizal fungi assemblage. Dark septate endophytes were detected in the sampled hair roots by microscopy.

Quantitative diffusion tensor imaging for evaluation of motor function in patients with brain infarcts

OBJECTIVE

To evaluate the quantitative diffusion value in ipsilateral cerebral peduncle of patients with differing motor function abilities and analyse the thresholds discriminating the poor motor function disability.

METHOD

Twenty-nine patients who previously suffered stroke underwent diffusion tensor imaging examinations. Motor function was evaluated 8 months after the event. The ipsilateral apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of cerebral peduncle and ADC ratio and FA ratio of patients with different motor function scales were analysed.

RESULTS

The ipsilateral FA value and FA ratio were distinctly different in patients with different motor function scales, and significantly correlated with the motor function scales. There was no significant difference of ipsilateral ADC and ADC ratio, and neither had correlation with motor function scale. The patients with poor motor function scale could be discriminated by the cutoff value of ipsilateral FA of 0.453 and FA ratio of 0.623 with sensitivity of 90%, 75% and specificity of 88.9%, 88.9% respectively.

CONCLUSIONS

The ipsilateral FA value and FA ratio were feasible and better imaging indices in discriminating patients with poor motor function ability.

HLA-G*0105N and HLA-G 14 bp dimorphisms in exon 8 in four distinct populations in mainland China

In this study, we investigated human leukocyte antigen (HLA)-G*0105N and the 14 bp deletion/insertion polymorphism in exon 8 of the HLA-G gene in 600 individuals from two southern Chinese Han populations (Hunan Han and Guangdong Han) and two northern Chinese populations (Inner Mongolia Han and Inner Mongolia Mongol), we also studied the linkage disequilibrium (LD) between HLA-G and HLA-A locus in these four populations. Our data showed that (1) the allele and haplotype frequencies of HLA-G and HLA-A loci did not differ significantly between the two southern Chinese Han populations, and showed remarkable homogeneity in the two northern Chinese populations; (2) HLA-G*0105N had significantly higher frequencies in the two northern Chinese populations with a frequency of 10.1% in the Inner Mongolia Han population, HLA-G 14 bp deletion/insertion frequency did not differ significantly between the southern and northern Chinese populations; (3) Ewens-Watterson homozygosity statistics at HLA-G*0105N, HLA-G 14 bp deletion/insertion polymorphism and HLA-A were consistent with neutral expectations for all populations; (4) HLA-G*0105N allele harbored the HLA-G 14 bp insertion in exon 8 and was linked to HLA-A*30, five HLA-G*0105N homozygotes were detected in the four populations; (5) haplotypes HLA-A*30-HLA-G*0105N and HLA-A*02-HLA-G 14 bp deletion were in significant LD across four populations, other LD patterns were more population-specific. Our data suggest that HLA-A*30-HLA-G*0105N-HLA-G 14 bp insertion is a conserved haplotype, the ethnic and/or geographic difference in HLA-G*0105N and HLA-G 14 bp distribution could largely be attributable to demographic factors other than selection. The LD patterns uncovered will facilitate the understanding of HLA-G role in associations previously described between HLA-A subregion and diseases.

Introduction of a rice blight resistance gene,Xa21, into five Chinese rice varieties through an Agrobacterium-mediated system

A cloned gene, Xa21 was transferred into five widely-used Chinese rice varieties through an Agrobacterium- mediated system, and over 110 independent transgenic lines were obtained. PCR and Southern analysis of transgenic plants revealed the integration of the whole Xa21 gene into the host genomes. The integrated Xa21 gene was stably inherited, and segregated in a 3: 1 ratio in the selfed T(1) generation when one copy of the gene was integrated in the transformants. Inoculation tests displayed that transgenic T(0) plants and Xa21 PCR-positive T(1) plants were highly resistant to bacterial blight disease. The selected Xa21 homozygous resistant transgenic lines with desirable qualities may be propagated as new varieties or utilized in hybrid rice breeding.