Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.

An in-vacuum diffractometer for resonant elastic soft x-ray scattering

We describe the design, construction, and performance of a 4-circle in-vacuum diffractometer for resonant elastic soft x-ray scattering. The diffractometer, installed on the resonant elastic and inelastic x-ray scattering beamline at the Canadian Light Source, includes 9 in-vacuum motions driven by in-vacuum stepper motors and operates in ultra-high vacuum at base pressure of 2 × 10(-10) Torr. Cooling to a base temperature of 18 K is provided with a closed-cycle cryostat. The diffractometer includes a choice of 3 photon detectors: a photodiode, a channeltron, and a 2D sensitive channelplate detector. Along with variable slit and filter options, these detectors are suitable for studying a wide range of phenomena having both weak and strong diffraction signals. Example measurements of diffraction and reflectivity in Nd-doped (La,Sr)(2)CuO(4) and thin film (Ga,Mn)As are shown.

Application of multifocal visual evoked potentials in the assessment of visual dysfunction in macular diseases

PURPOSE

To evaluate the use of AccuMap multifocal visual evoked potentials (mfVEP) in visual dysfunction caused by macular diseases.

METHODS

Forty-eight eyes with known macular diseases underwent AccuMap mfVEP and microperimetry 1 (MP1) assessments. Evaluation of mfVEP abnormality was based on an amplitude deviation probability plot and the AccuMap Severity Index (ASI). Correlation analyses of the mean mfVEP amplitude corresponding to a radius of 2°, 5°, and 10° of the central visual field, minimum angle of resolution best-corrected visual acuity (BCVA), and MP1 mean sensitivity of the corresponding areas were performed.

RESULTS

Among the 48 affected eyes, AccuMap mfVEP detected an abnormality of the central visual field in 45 eyes, with a sensitivity of 93.8%. The mean mfVEP amplitudes within a radius of 2°, 5°, and 10° of the central visual field were found to be positively correlated with BCVA (P<0.01 for all groups). The mean amplitudes also positively correlated with the MP1 mean sensitivity value of the corresponding visual field (P<0.01 for all groups). In the group with stable fixation or predominantly central fixation, the mean mfVEP amplitudes did not correlate with the BCVA or the MP1 mean sensitivity value. Regardless of the fixation status, the ASI was found to correlate with both the BCVA and the total MP1 mean defect value.

CONCLUSION

Objective perimetry using AccuMap mfVEP might be applied in the assessment of macular function, with the ASI offering a potentially useful indicator for evaluating macular dysfunction.

Optical coherent control induced by an electric field in a semiconductor: a new manifestation of the Franz-Keldysh effect

In (100)-oriented GaAs illuminated at normal incidence by a laser and its second harmonic, interference between one- and two-photon absorption results in ballistic current injection, but not modulation of the overall carrier injection rate. Results from a pump-probe experiment on a transversely biased sample show that a constant electric field enables coherent control of the carrier injection rate. We ascribe this to the nonlinear optical Franz-Keldysh effect and calculate it for a two-band parabolic model. The mechanism is relevant to centrosymmetric semiconductors as well.

Anthracyclines disrupt telomere maintenance by telomerase through inducing PinX1 ubiquitination and degradation

Telomere maintenance is essential for cancer growth. Induction of telomere dysfunction, for example, by inhibition of telomeric proteins or telomerase, has been shown to strongly enhance cancer cells' sensitivity to chemotherapies. However, it is not clear whether modulations of telomere maintenance constitute cancer cellular responses to chemotherapies. Furthermore, the manner in which anti-cancer drugs affect telomere function remains unknown. In this study, we show that anthracyclines, a class of anti-cancer drugs widely used in clinical cancer treatments, have an active role in triggering telomere dysfunction specifically in telomerase-positive cancer cells. Anthracyclines interrupt telomere maintenance by telomerase through the downregulation of PinX1, a protein factor responsible for targeting telomerase onto telomeres, thereby inhibiting telomerase association with telomeres. We further demonstrate that anthracyclines downregulate PinX1 by inducing this protein degradation through the ubiquitin-proteasome-dependent pathway. Our data not only reveal a novel action for anthracyclines as telomerase functional inhibitors but also provide a clue for the development of novel anti-cancer drugs based on telomerase/telomere targeting, which is actively investigated by many current studies.

First Report of Fusarium cerealis Causing Fusarium Head Blight on Barley in China

The fungus Fusarium cerealis (Cooke) Sacc. (1886) (synonym F. crookwellense L.W. Burgess, P.E. Nelson et Toussoun (1982)) is one of the causal agents of Fusarium head blight (FHB), a significant fungal disease of small grains and maize in many countries (3). Miller et al. identified trichothecene chemotypes from three F. cerealis (F. crookwellense) strains collected from Chinese wheat in 1991 (2). However, there have been no other reports of this Fusarium species in China since then. The disease has been an important threat to the production of wheat and barley in China, and has caused yield losses of approximately 212,000 t (data from China National Agro-Technical Extension and Service Center) in 2008, one of the most severe FHB epidemic years in Chinese wheat in the past 10 years. Scabby heads of barley and wheat were collected from Yuxi and Zhaotong in Yunnan Province, respectively, in 2008. Each of 15 strains was isolated from a different spike of barley and eight isolates were derived from different wheat spikes. All strains were single spored. On the basis of a multilocus genotyping assay (4), all 15 isolates from barley and six of the eight strains from wheat were identified as F. cerealis with the nivalenol (NIV) genotype. To validate this result, partial translation elongation factor (TEF-1α, ~700 bp) gene sequences of isolates were generated (GenBank Accession Nos. HQ824369 and HQ824370) and then compared with the FUSARIUM-ID database (1). The TEF-1α sequences of all 21 isolates were highly conserved and showed 100% identity with the sequences of F. cerealis in the database. A pathogenicity test was performed on a winter wheat cultivar, Yangmai158, using a three-replicate randomized complete block design in Langfang Experimental Farm. Langfang is not an FHB-endemic area and is very dry, with almost no infection source in normal years. At anthesis, the central floret of each of five spikes was injected with 20 μl of a conidial suspension (10⁶ macroconidia/ml) of each isolate in each block, such that 105 spikes were injected per block. An equal amount of water was injected into five heads in each block as a control. The inoculated spikes were enclosed in sandwich bags misted with water for 3 days to ensure infection by the inoculated pathogen and prevent infections from other sources. The plots were misted twice daily after inoculation. The average night and day temperatures were 19.0 and 25.2°C, respectively. Typical FHB symptoms (light tan or bleached spikelets, bases of infected spikelets, and portions of the rachis were dark brown), which were observed in the heads inoculated with F. cerealis 7 days after inoculation, were similar to the original symptoms in the sampling sites. The control plants remained asymptomatic. F. cerealis was reisolated from the infected heads, indicating it was the pathogen causing this disease. To our knowledge, this is the first report of F. cerealis causing FHB on barley in China, and also the first time that a high proportion of F. cerealis strains were isolated from one sampling site (15 of 15 in Yuxi and 6 of 8 in Zhaotong). More isolates must be collected in Yunnan Province and further studies conducted to gain a better understanding of the spatial and temporal dynamics of this pathogen. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2010. (2) J. D. Miller et al. Mycologia 83:121, 1991. (3) D. W. Parry et al. Plant Pathol. 44:207, 1995. (4) T. J. Ward et al. Fungal Genet. Biol. 45:473, 2008.

A reproductive fitness cost associated with Hessian fly (Diptera: Cecidomyiidae) virulence to wheat's H gene-mediated resistance

We studied whether adaptation of the Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), to plant resistance incurs fitness costs. In this gene-for-gene interaction, adaptation to a single H resistance gene occurs via loss of a single effector encoded by an Avirulence gene. By losing the effector, the adapted larva now survives on the H gene plant, presumably because it evades the plant's H gene-mediated surveillance system. The problem is the Hessian fly larva needs its effectors for colonization. Thus, for adapted individuals, there may be a cost for losing the effector, with this then creating a trade-off between surviving on H-resistant plants and growing on plants that lack H genes. In two different tests, we used wheat lacking H genes to compare the survival and growth of a nonadapted strain to two H-adapted strains. The two adapted strains differed in that one had been selected for adaptation to H9, whereas the other strain had been selected for adaptation to H13. Tests showed that two H-adapted strains were similar to the nonadapted strain in egg-to-adult survival but that they differed in producing adults with smaller wings. By using known relationships between wing length and reproductive potential, we found that losses in wing length underestimate losses in reproductive potential. For example, H9- and H13-adapted females had 9 and 3% wing losses, respectively, but they were estimated to have 32 and 12% losses in egg production. Fitness costs of adaptation will be investigated further via selection experiments comparing Avirulence allele frequencies for Hessian fly populations exposed or not exposed to H genes.

Ventilator-induced lung injury and sepsis: two sides of the same coin?

Unequivocal evidence from both experimental and clinical research has shown that mechanical ventilation can damage the lungs and initiate an inflammatory response, possibly contributing to extrapulmonary organ dysfunction. This type of injury, referred to as ventilator-induced lung injury (VILI), resembles the syndromes of acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS). VILI can trigger a complex array of inflammatory mediators, resulting in a local and systemic inflammatory response. Substances produced in the lungs can be translocated into the systemic circulation as a result of injury to the pulmonary epithelium and to the capillary endothelium. This type of injury forms the basis for the use of low tidal volumes (5-7 mL/kg of predicted body weight) during mechanical ventilation of patients with ALI/ARDS. The recognition of VILI has prompted a number of investigators to suggest that ALI/ARDS may be, in part, a product of our efforts to mechanically ventilate patients rather than the progression of the underlying disease. On the other hand, current scientific evidence supports a link between VILI and the development of extrapulmonary organ dysfunction, similar to how most severe cases of sepsis are clinically manifested. In addition, functional genomics approaches using a gene array methodology to measure lung gene expression have identified differential patterns of gene expression in animal models of VILI, similar to those gene pathways activated during experimental and clinical sepsis. In this line of thought, we hypothesize that injurious mechanical ventilation could be responsible for the perpetuation and worsening of sepsis in some patients and for the development of a sepsis-like syndrome in others.