A substitution mutation in OsPELOTA confers bacterial blight resistance by activating the salicylic acid pathway.

We previously reported a spotted-leaf mutant pelota (originally termed HM47) in rice displaying arrested growth and enhanced resistance to multiple races of Xanthomonas oryzae pv. oryzae. Here, we report the map-based cloning of the causal gene OsPELOTA (originally termed splHM47 ). We identified a single base substitution from T to A at position 556 in the coding sequence of OsPELOTA, effectively mutating phenylalanine to isoleucine at position 186 in the translated protein sequence. Both functional complementation and over-expression could rescue the spotted-leaf phenotype. OsPELOTA, a paralogue to eukaryotic release factor 1 (eRF1), shows high sequence similarity to Drosophila Pelota and also localizes to the endoplasmic reticulum and plasma membrane. OsPELOTA is constitutively expressed in roots, leaves, sheaths, stems, and panicles. Elevated levels of salicylic acid and decreased level of jasmonate were detected in the pelota mutant. RNA-seq analysis confirmed that genes responding to salicylic acid were upregulated in the mutant. Our results indicate that the rice PELOTA protein is involved in bacterial leaf blight resistance by activating the salicylic acid metabolic pathway.

Dual-wavelength Nd:YAG laser operation at 1319 and 1338 nm by direct pumping at 885 nm.

This paper presents a continuous wave and a Q-switched Nd:YAG laser pumped by diode laser at 885 nm. The maximum output power of the CW laser is 8.28 W with an absorbed slope efficiency of 35.01%. The Q-switching is achieved using a V³âº:YAG crystal as the saturable absorber. The maximum output power of the passively Q-switched laser is 3.55 W with an absorbed pumping power of 28.65 W operated with a dual wavelength at 1319 and 1338 nm. The shortest pulse widths of the Q-switched laser are 20.20 and 20.86 ns, with a maximum repetition rate of 64.10 kHz.

Single base substitution in OsCDC48 is responsible for premature senescence and death phenotype in rice.

A premature senescence and death 128 (psd128) mutant was isolated from an ethyl methane sulfonate-induced rice IR64 mutant bank. The premature senescence phenotype appeared at the six-leaf stage and the plant died at the early heading stage. psd128 exhibited impaired chloroplast development with significantly reduced photosynthetic ability, chlorophyll and carotenoid contents, root vigor, soluble protein content and increased malonaldehyde content. Furthermore, the expression of senescence-related genes was significantly altered in psd128. The mutant trait was controlled by a single recessive nuclear gene. Using map-based strategy, the mutation Oryza sativa cell division cycle 48 (OsCDC48) was isolated and predicted to encode a putative AAA-type ATPase with 809 amino-acid residuals. A single base substitution at position C2347T in psd128 resulted in a premature stop codon. Functional complementation could rescue the mutant phenotype. In addition, RNA interference resulted in the premature senescence and death phenotype. OsCDC48 was expressed constitutively in the root, stem, leaf and panicle. Subcellular analysis indicated that OsCDC48:YFP fusion proteins were located both in the cytoplasm and nucleus. OsCDC48 was highly conserved with more than 90% identity in the protein levels among plant species. Our results indicated that the impaired function of OsCDC48 was responsible for the premature senescence and death phenotype.

Q-switched 1329 nm Nd:CNGG laser.

We demonstrate a laser-diode-pumped Q-switched 1329 nm neodymium-doped calcium-niobium-gallium-garnet (Nd:CNGG) laser using a V:YAG crystal as a saturable absorber. An average output power of 353 mW and a repetition rate of 13.43 kHz for Q-switched pulses were obtained. The pulse width was from 124 to 151.4 ns under different pump powers. Output power of 685 mW was obtained without the V:YAG crystal inserted.

CD133+ subpopulation of the HT1080 human fibrosarcoma cell line exhibits cancer stem-like characteristics.

The cancer stem cell (CSC) theory holds that a minority population within tumors possesses stem cell properties of self-renewal and multilineage differentiation capacity and provides the initiating cells from which tumors are derived and sustained. However, verifying the existence of these CSCs has been a significant challenge. The CD133 antigen is a pentaspan membrane glycoprotein proposed to be a CSC marker for cancer-initiating subpopulations in the brain, colon and various other tissues. Here, CD133+ cells were obtained and characterized from the HT1080 cell line to determine the utility of this marker for isolating CSCs from human fibrosarcoma cells. In this study, CD133+ cells were separated from HT1080 cells using magnetic beads and characterized for their proliferation rate and resistance to chemotherapeutic drugs, cisplatin and doxorubicin, by MTS assay. Relative expression of tumor-associated genes Sox2, Oct3/4, Nanog, c-Myc, Bmi-1 and ABCG2 was measured by real-time polymerase chain reaction (PCR). Clonal sphere formation and the ability of CD133+ cells to initiate tumors in BALB/c nude mice was also evaluated. We found that CD133+ cells showed a high proliferation rate, increased resistance to chemotherapy drugs and overexpression of tumor-associated genes compared with these features in CD133- cells. Additionally, CD133+ cells were able to form spherical clusters in serum-free medium with high clonogenic efficiency, indicating a significantly greater tumor-initiating potential when compared with CD133- cells. These findings indicate that CD133+ cells identified within the HT1080 human fibrosarcoma cell line possess many CSC properties and may facilitate the development of improved therapies for fibrosarcoma.

Characterization and genetic analysis of a novel rice spotted-leaf mutant HM47 with broad-spectrum resistance to Xanthomonas oryzae pv. oryzae.

A stable inherited rice spotted-leaf mutant HM47 derived from an EMS-induced IR64 mutant bank was identified. The mutant expressed hypersensitive response (HR)-like symptoms throughout its whole life from the first leaf to the flag leaf, without pathogen invasion. Initiation of the lesions was induced by light under natural summer field conditions. Expression of pathogenesis-related genes including PAL, PO-C1, POX22.3 and PBZ1 was enhanced significantly in association with cell death and accumulation of H2 O2 at and around the site of lesions in the mutant in contrast to that in the wild-type (WT). Disease reaction to Xanthomonas oryzae pv. oryzae from the Philippines and China showed that HM47 is a broad-spectrum disease-resistant mutant with enhanced resistance to multiple races of bacterial blight pathogens tested. An F2 progeny test showed that bacterial blight resistance to race HB-17 was co-segregated with the expression of lesions. Genetic analysis indicated that the spotted-leaf trait was controlled by a single recessive gene, tentatively named spl(HM47) , flanked by two insertion/deletion markers in a region of approximately 74 kb on the long arm of chromosome 4. Ten open reading frames are predicted, and all of them are expressed proteins. Isolation and validation of the putative genes are currently underway.

Ultrasensitive detection of amplified spontaneous emission at 710 nm by means of picosecond collinear optical parametric amplification near degeneracy.

We report the experimental results on improving the detection of an ultraweak optical signal using a 355 nm pumped picosecond collinear optical parametric amplification (OPA). The OPA is seeded by the amplified spontaneous emission (ASE) generated in a solution of pyridine-1 dye in ethanol. The gain factor of this amplifier is determined as ~1.5×10(8), and the detection limit is ~1.25 aJ per pulse, corresponding to five photons at 710 nm within the 15 ps pulse width of the pump beam. This is achieved by reducing superfluorescence background noise by means of signal/idler double seeding near degeneracy, amplification under a slightly phase-mismatched condition, and space filtering with increasing observation distance up to 3.2 m. Compared with previous reports, the detection limit is significantly enhanced. The pulse shape of the ASE is also measured with OPA, and it agrees well with that measured by an ultrafast oscilloscope.

Characterization and genetic analysis of a light- and temperature-sensitive spotted-leaf mutant in rice.

A rice spotted-leaf mutant was isolated from an ethane methyl sulfonate (EMS) -induced IR64 mutant bank. The mutant, designated as spl30 (spotted-leaf30), displayed normal green leaf color under shade but exhibited red-brown lesions under natural summer field conditions. Initiation of the lesions was induced by light and the symptom was enhanced at 33 (°) C relative to 26 (°) C. Histochemical staining did not show cell death around the red-brown lesions. Chlorophyll contents in the mutant were significantly lower than those of the wild type while the ratio of chlorophyll a/b remained the same, indicating that spl30 was impaired in biosynthesis or degradation of chlorophyll. Disease reaction patterns of the mutant to Xanthomonas oryzae pv. oryzae were largely unchanged to most races tested except for a few strains. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively named spl30(t), which co-segregated with RM15380 on chromosome 3, and was delimited to a 94 kb region between RM15380 and RM15383. Spl30(t) is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region. The genetic data and recombination populations provided in this study will enable further fine-mapping and cloning of the gene.

Generation and optical parametric amplification of picosecond supercontinuum.

We have demonstrated the output characteristics of optical parametric amplification (OPA) seeded by a supercontinuum (SC) generated in deionized water excited by 1064 nm. The SC spectrum (from 426 to 943 nm) overlaps well with the tuning range of a 355 nm pumped OPA for both the signal and idler. The tunable range covers from 430 to 2035 nm, with a maximum overall energy conversion efficiency of 32% in the OPA stage. A FWHM bandwidth of 54 nm near the degeneracy point from 658 to 760 nm can be generated by using a collinear OPA. Chirping of the SC pulses is also investigated with the OPA technique. The time delay between the 430 nm component and the 567 nm component of the generated SC due to chirp is measured to be -10.72 ps, increasing almost linearly with the wavelength.