Identification and candidate analysis of a new brown planthopper resistance locus in an Indian landrace of rice, paedai kalibungga.

The brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive pest of rice (Oryza sativa L.). Utilizing resistant rice cultivars that harbor resistance gene/s is an effective strategy for integrated pest management. Due to the co-evolution of BPH and rice, a single resistance gene may fail because of changes in the virulent BPH population. Thus, it is urgent to explore and map novel BPH resistance genes in rice germplasm. Previously, an indica landrace from India, Paedai kalibungga (PK), demonstrated high resistance to BPH in both in Wuhan and Fuzhou, China. To map BPH resistance genes from PK, a BC1F2:3 population derived from crosses of PK and a susceptible parent, Zhenshan 97 (ZS97), was developed and evaluated for BPH resistance. A novel BPH resistance locus, BPH39, was mapped on the short arm of rice chromosome 6 using next-generation sequencing-based bulked segregant analysis (BSA-seq). BPH39 was validated using flanking markers within the locus. Furthermore, near-isogenic lines carrying BPH39 (NIL-BPH39) were developed in the ZS97 background. NIL-BPH39 exhibited the physiological mechanisms of antibiosis and preference toward BPH. BPH39 was finally delimited to an interval of 84 Kb ranging from 1.07 to 1.15 Mb. Six candidate genes were identified in this region. Two of them (LOC_Os06g02930 and LOC_Os06g03030) encode proteins with a similar short consensus repeat (SCR) domain, which displayed many variations leading to amino acid substitutions and showed higher expression levels in NIL-BPH39. Thus, these two genes are considered reliable candidate genes for BPH39. Additionally, transcriptome sequencing, DEGs analysis, and gene RT-qPCR verification preliminary revealed that BPH39 may be involved in the jasmonic acid (JA) signaling pathway, thus mediating the molecular mechanism of BPH resistance. This work will facilitate map-based cloning and marker-assisted selection for the locus in breeding programs targeting BPH resistance. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-024-01485-6.

Relationships between Size-specific Dose Estimate and Signal to Noise Ratio under Chest CT Examinations with Tube Current Modulation.

PURPOSE: Exploring the relationship between the signal-to-noise ratio (SNR) of organs and size-specific dose estimate (SSDE) in tube current modulation (TCM) chest CT examination. METHODS: Forty patients who received TCM chest CT scanning were retrospectively collected and divided into four groups according to the tube voltage and sexes. We chose to set up the region of interest (ROI) at the tracheal bifurcation and its upper and lower parts in slice images of the heart, aorta, lungs, paracranial muscles, and female breast, and the SNR of each organ was calculated. We also calculated the corresponding axial volume CT dose index (CTDIvolz) and axial size-specific dose estimate (SSDEz). RESULTS: The correlation analysis showed that the correlation between the SNR of the slice images of most organs and SSDEz was more significant than 0.8, and that between the SNR and CTDIvol was more significant than 0.7. The simple linear regression analysis results showed that when the sex is the same, the SNR of the same organ at 100kVp was higher than 120kVp, except for the lung. In multiple regression analysis, the result indicated that the determination coefficients of the SNR and SSDEz of the four groups were 0.934, 0.971, 0.905, and 0.709, respectively. CONCLUSION: In chest CT examinations with TCM, the correlation between the SNR of each organ in slice images and SSDEz was better than that of CTDIvolz. And when the SSDEz was the same, the SNR at 100 kVp was better than that at 120 kVp.

[Calculation of water equivalent diameter based on anteroposterior localizer CT images].

ObjectiveTo explore a method for calculating water equivalent diameter (Dw) based on localizer CT images for calculation of the size specific dose estimates (SSDE).MethodGE Revolution CT and LightSpeed VCT were used to scan CT dose index phantoms 16 cm and 32 cm in diameter at the tube voltages of 80, 100 and 120 kV to obtain the axial image and anteroposterior localizer radiograph. According to the definition of CT Hounsfield unit, the axial images were used to calculate the conversion factors that convert the phantom thickness to water equivalent thickness. The gray value of the localizer radiograph and the water equivalent thickness were calibrated with a linear equation, and the parameters of the calibration were used to calculate the water equivalent thickness. The method was verified using 2 CT dose index phantoms and in 22 patients undergoing chest and abdominal CT examination.ResultComparison of the water equivalent diameter (Dw) based on the localizer radiograph and axial image of the 2 phantoms showed that the percentage difference between Dw from the axial images and from the localizer radiograph was below 3%. The trend of Dw variations with location in the two methods was sonsistent. The difference in Dw in intermediate region of interest between the axial image and the localizer radiograph from the 22 patients was below 6.6%. With the mean Dw in the ROI, the maximum percentage difference was 7.5%.ConclusionCalibration of the gray value of the localizer radiograph and the water equivalent thickness using the axial image and localizer radiograph of CT dose index phantoms allows quick calculation of the SSDE based on the parameters of calibration.

Evaluation of Effective Dose from CT Scans for Overweight and Obese Adult Patients Using the VirtualDose Software.

This paper evaluates effective dose (ED) of overweight and obese patients who undergo body computed tomography (CT) examinations. ED calculations were based on tissue weight factors in the International Commission on Radiological Protection Publication 103 (ICRP 103). ED per unit dose length product (DLP) are reported as a function of the tube voltage, body mass index (BMI) of patient. The VirtualDose software was used to calculate ED for male and female obese phantoms representing normal weight, overweight, obese 1, obese 2 and obese 3 patients. Five anatomic regions (chest, abdomen, pelvis, abdomen/pelvis and chest/abdomen/pelvis) were investigated for each phantom. The conversion factors were computed from the DLP, and then compared with data previously reported by other groups. It was observed that tube voltage and BMI are the major factors that influence conversion factors of obese patients, and that ED computed using ICRP 103 tissue weight factors were 24% higher for a CT chest examination and 21% lower for a CT pelvis examination than the ED using ICRP 60 factors. For body CT scans, increasing the tube voltage from 80 to 140 kVp would increase the conversion factors by as much as 19-54% depending on the patient's BMI. Conversion factor of female patients was ~7% higher than the factors of male patients. DLP and conversion factors were used to estimate ED, where conversion factors depended on tube voltage, sex, BMI and tissue weight factors. With increasing number of obese individuals, using size-dependence conversion factors will improve accuracy, in estimating patient radiation dose.

Polymorphisms in checkpoint kinase 2 may contribute to lymph node metastasis from esophageal cancer.

Esophageal cancer, which is commonly accompanied by lymph node metastasis, is among the deadliest of cancers and carries a grim prognosis. We investigated the association between genetic variation in checkpoint kinase 2 (CHEK2), which has been linked to metastasis in other cancers, and the risk of developing lymph node metastasis from esophageal cancer. CHEK2-122 G/C genotypes were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) in 296 subjects with esophageal cancer (67 cases with and 229 cases without lymph node metastasis). The associations between CHEK2 genotypes and the risk of lymph node metastasis from esophageal cancer were estimated by computing odds ratios (OR) and their 95% confidence intervals (CI). The CHEK2 GG, GC, and CC genotype frequencies in patients with and without lymph node metastasis were 47.8%, 40.3%, and 11.9% and 31.0%, 50.7%, and 18.3% respectively, and were statistically significant (χ(2) =6.591, P=0.037). Logistic regression analyses revealed that the CHEK2-122 GC genotype significantly reduced the risk of lymph node metastasis (adjusted OR=0.54, 95% CI=0.29-0.93, P=0.028) compared to the GG genotype. Subsequently, we propose that the CHEK2-122 G/C polymorphism may play a protective role in preventing lymph node metastasis from esophageal cancer, and may also provide insight toward determining patient prognosis without the use of surgery.

[Analysis of the evolution of esophageal tumor volume in radiotherapy process using a mathematical model].

The volume change of tumor during radiotherapy processes indirectly reflects the short-term efficacy and the quality of radiotherapy planning. We analyzed clinical data of radiotherapy using a mathematical model in our study. First, we selected eight esophageal carcinoma patients with only using 3DRT and conventional dose fractionation schemes. And then we observed and measured the change of tumor volume during the radiotherapy. Based on the LQ model, repopulation and re-oxygenation in 4Rs, and the kinetics of doomed tumor disintegration, we established the mathematical model of tumor evolution in radiotherapy. And then we used the model to analyze the clinical trial data about esophageal carcinoma with radiotherapy. It was proved that the results of the model almost coincided with the clinical trial data. According to the analysis results, we could get the related radiobiology parameters to estimate biological effective dose and repopulation of patients. The mathematical model could provide reference for assessment of prognosis and further scheme of treatment.

[Mathematical model of tumor evolution in radiotherapy].

The schemes of dose fractionation play an important role in tumor radiotherapy. We used mathematical methods to describe the process of tumor cells evolution during radiotherapy, trying to find how the schemes of dose fractionation affect tumor cells. In clinical radiobiology, linear-quadratic (LQ) model is frequently used to describe radiation effects of tumor cells. We integrated LQ model with effect of oxygen, and with the phenomenon of repopulation and reoxygenation in the theory of radiation biology. While we considered the disappearing progress of doomed cells in tumor, we established the mathematical model of tumor evolution in radiotherapy. We simulated some common treatment schedules, and studied the change role of tumor cells during radiotherapy. These results can serve for the optimization of dose fractionation scheme based on tumor radiobiological characteristics.