Feasibility of robotic cholecystectomy at an academic center with a young robotic surgery program: a retrospective cohort study with umbrella review.

Laparoscopic cholecystectomy (LC) has been standard of care for surgical treatment of benign gallbladder pathology for decades. With the advent of robotic surgical technology, robotic cholecystectomy (RC) has gained attention as an alternative to conventional laparoscopy. This study introduces a single-surgeon experience with laparoscopic versus robotic cholecystectomy and an umbrella systematic review of the outcomes of both approaches. A retrospective chart review was performed at a single institution on a prospectively maintained database of patients undergoing laparoscopic or robotic cholecystectomy for benign gallbladder pathology. An umbrella systematic review was conducted using PRISMA methodology. A total of 103 patients were identified; 61 patients underwent LC and 42 underwent RC. In the RC cohort, 17 cases were completed using a four-port technique while 25 were completed using a three-port technique. Patients undergoing RC were older compared to the LC group (44.78 vs 57.02 years old; p < 0.001) and exhibited lower body mass index (29.37 vs 32.37 kg/m2, p = 0.040). No statistically significant difference in operative time or need for postoperative ERCP was noted. Neither this series nor the umbrella systematic review revealed significant differences in conversion to open surgery or readmissions between the LC and RC cohorts. Three-port RC was associated with reduced operative time compared to four-port RC (101.28 vs 150.76 min; p < 0.001). Robotic cholecystectomy is feasible and safe at a young robotic surgery program in an academic center setting and comparable to laparoscopic cholecystectomy clinical outcomes.

Efficacy of radiofrequency ablation for treatment of toxic thyroid nodules-a narrative review.

Background and Objective: Radiofrequency ablation (RFA) has been used in the treatment of benign thyroid nodules for the past 20 years. The adaptation of RFA to benign autonomously functioning thyroid nodules (AFTNs) has been introduced into clinical practice with variable efficacy and outcomes published in the literature. To better understand international practices, we performed a literature search to better elucidate the efficacy and outcomes in the treatment of AFTNs with RFA. Methods: Comprehensive literature searches were independently conducted by two investigators on PubMed, EMBASE, and Scopus in October of 2022 to identify articles reporting AFTN treated by RFA using the terms "RFA", "radiofrequency ablation", "thyroid nodule", "toxic nodules", and "autonomous functioning thyroid nodule". Papers were selected by relevance of the title or abstract, and the date of publication. Key Content and Findings: In patients with toxic nodules, studies have shown 50% remission rate one year after single session of RFA, up to 71% after second dose. Adverse events are generally limited to postoperative pain lasting less than one day, however there are reports of self-limited voice changes, and self-limited hypothyroidism. RFA has been shown to be safe with no reported instances of post-procedure hypothyroidism or hypocalcemia when compared to radioactive iodine (RAI) and surgery. Conclusions: RFA is an acceptable alternative to surgical resection for the treatment of AFTNs in selective patients, however more studies on long-term hyperthyroidism remission rates and nodule regrowth are necessary for further applications.

Enhancing autophagy leads to increased cell death in radiation-treated cervical cancer cells.

This study was carried out to determine the effect of autophagy modulation in radiation treatment of cervical cancer cells. HeLa and CaSki cells were irradiated with γ-rays (2 Gy/min) after treatment with an autophagy inducer (rapamycin) and inhibitor (3-MA). Expression of LC3 and cell death in two cell preparations were examined. In addition, expression of Caspase-3 and PARP were examined after radiation alone and with autophagy inhibitor treatment. A notable increment of LC3 expression was detected after radiation in both cell lines. Cell viability was observed to decrease in 3-MA-treated cells compared to radiation alone, and even further in rapamycin-treated cells. Apoptosis was confirmed to occur later than autophagy in radiation treatment, and inhibition of autophagy derived a decrease in apoptosis. In conclusion, radiation-induced autophagy may be regulated by modulators, and autophagy augmentation yields an increase in cervical cancer cell death under radiation.Impact statementWhat is already known on this subject? Autophagy is known to contribute both to tumour cell survival and death against radiation therapy. The effect of induction or inhibition of radiation-induced autophagy on cervical cancer cell death is not clear.What the results of this study add? Cell viability was observed to decrease in 3-MA-treated cells compared to radiation alone, and even further in rapamycin-treated cells. Apoptosis occurred later than autophagy in radiation treatment, and inhibition of autophagy derived a decrease in apoptosis.What the implications are of these findings for clinical practice and/or further research? Our results suggest that radiation-induced autophagy may be regulated by modulators, and autophagy augmentation yields an increase in cervical cancer cell death under radiation.

Identification and characterization of a novel gene controlling floral organ number in rice (Oryza sativa L.).

Floral organ number is crucial for successful seed setting and mature grain development. Although some genes and signaling pathways controlling floral organ number have been studied, the underlying mechanism is complicated and requires further investigation. In this study, a floral organ number mutant was generated by the ethyl methanesulfonate treatment of the Korean japonica rice cultivar Ilpum. In the floral organ number mutant, 37% of the spikelets showed an increase in the number of floral organs, especially stamens and pistils. Histological analysis revealed that the number of ovaries was determined by the number of stigmas; spikelets with two or three stigmas contained only one ovary, whereas spikelets with four stigmas possessed two ovaries. The floral organ number mutant showed pleiotropic phenotypes including multiple grains, early flowering, short plant height, and reduced tiller number compared with the wild-type. Genetic and MutMap analyses revealed that floral organ number is controlled by a single recessive gene located between the 8.0 and 20.0 Mb region on chromosome 8. Calculation of SNP-index confirmed Os08g0299000 as the candidate gene regulating floral organ number, which was designated as FLORAL ORGAN NUMBER7 (FON7). A single nucleotide polymorphism (G to A) was discovered at the intron splicing donor site of FON7, which caused the skipping of the entire sixth exon in the mutant, resulting in the deletion of 144 bp. Furthermore, the T-DNA-tagged line displayed the same floral organ number phenotype as the fon7 mutant. These results provide valuable insight into the mechanism of floral organ differentiation and formation in rice.

Atomic Layer Deposition of Sb2 Te3 /GeTe Superlattice Film and Its Melt-Quenching-Free Phase-Transition Mechanism for Phase-Change Memory.

Atomic layer deposition (ALD) of Sb2 Te3 /GeTe superlattice (SL) film on planar and vertical sidewall areas containing TiN metal and SiO2 insulator is demonstrated. The peculiar chemical affinity of the ALD precursor to the substrate surface and the 2D nature of the Sb2 Te3 enable the growth of an in situ crystallized SL film with a preferred orientation. The SL film shows a reduced reset current of ≈1/7 of the randomly oriented Ge2 Sb2 Te5 alloy. The reset switching is induced by the transition from the SL to the (111)-oriented face-centered-cubic (FCC) Ge2 Sb2 Te5 alloy and subsequent melt-quenching-free amorphization. The in-plane compressive stress, induced by the SL-to-FCC structural transition, enhances the electromigration of Ge along the [111] direction of FCC structure, which enables such a significant improvement. Set operation switches the amorphous to the (111)-oriented FCC structure.

Identification of volatile organic compounds related to the eating quality of cooked japonica rice.

Eating quality (EQ) of rice has a complex nature composed of physicochemical properties. Nevertheless, breeding programs evaluating EQ through sensory test or taste-evaluation instruments have been laborious, time-consuming and inefficient. EQ is affected by both taste and aroma. However, in actual breeding programs, aroma of cooked rice has been considered the least due to lack of information. Here we identified a total of 41 volatile compounds potentially affecting the EQ of non-aromatic, cooked japonica rice, identified by GC-MS, sensory panel test, and Toyo taste-meter analyses. Partial least squares discriminant analysis demonstrated an outstanding classification effect of the identified volatile compounds on eating-quality discrimination. Several volatile compounds related to lipid oxidation and fatty acid degradation were identified to affect the EQ in japonica rice. Of them, 1-octen-3-ol, 1-ethyl-3,5-dimethylbenzene, 2,6,11-trimethyldodecane, 3-ethyloctane, 2,7,10-trimethyldodecane, methyl salicylate, 2-octanone, and heptanal were selected as important compounds. The discriminant model for the classification of the quality of cultivars was robust and accurate, an r-squared value was 0.91, a q squared value was 0.85, and an accuracy was 1.0. Overall, the results of this study characterize EQ of rice cultivars based on volatile compounds, suggesting the application of metabolite profiling data for rice breeding of high eating quality.

Accuracy of Catheter Positioning during Left Subclavian Venous Access: A Randomized Comparison between Radiological and Topographical Landmarks.

Left subclavian venous access increases the risk of vascular damage and thrombosis based on the catheter course and location of the catheter tip. We investigated the accuracy of tip positioning with conventional landmarks using transesophageal echocardiography. The carina as a radiological landmark and the right third intercostal space as a topographical landmark were selected for tip positioning within the target zone, defined as 2 cm above and 1 cm below the right atrial junction. A total of 120 participants were randomized into two groups. The catheter insertion depth was determined as 1.5 cm more than the distance between the venous insertion point and the carina via the right first intercostal space in the radiological group, and between the venous insertion point and the right third intercostal space via the right first intercostal space in the topographical group. The determined insertion depth and actual distance to the right atrial junction of the radiological and topographical groups were 19.5 cm and 20.5 cm, and 19.8 cm and 20.4 cm, respectively. Acceptable positioning was more frequent in the topographical group (96.4% vs. 85.7%; p = 0.047). The catheter tip is more accurately positioned in the distal superior vena cava using topographical landmarks than radiological landmarks.

Sequencing and de novo assembly of the Koshihikari genome and identification of the genomic region related to the eating quality of cooked rice.

The japonica rice (Oryza sativa L.) cultivar Koshihikari is considered an important breeding material with good eating quality (EQ). To effectively utilize Koshihikari in molecular breeding programs, determining its whole genome sequence including cultivar-specific segment is crucial. Here, the Koshihikari genome was sequenced using Nanopore and Illumina platforms, and de novo assembly was performed. A highly contiguous Koshihikari genome sequence was compared with Nipponbare, the reference genome of japonica. Genome-wide synteny was observed, as expected, without large structural variations. However, several gaps in alignment were detected on chromosomes 3, 4, 9, and 11. It was notable that previously identified EQ-related QTLs were found in these gaps. Moreover, sequence variations were identified in chromosome 11 at a region flanking the P5 marker, one of the significant markers of good EQ. The Koshihikari-specific P5 region was found to be transmitted through the lineage. High EQ cultivars derived from Koshihikari possessed P5 sequences; on the other hand, Koshihikari-derived low EQ cultivars didn't contain the P5 region, which implies that the P5 genomic region affects the EQ of Koshihikari progenies. The EQ of near-isogenic lines (NILs) of Samnam (a low EQ cultivar) genetic background harboring the P5 segment was improved compared to that of Samnam in Toyo taste value. The structure of the Koshihikari-specific P5 genomic region associated with good EQ was analyzed, which is expected to facilitate the molecular breeding of rice cultivars with superior EQ. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01335-3.

Retrospective lumbosacral CT analysis and prospective observational study of the ipsilateral tunnel view technique for fluoroscopy-guided selective S1 transforaminal epidural injection.

BACKGROUND: The purpose of this study was to retrospectively observe the anatomic relationship between dorsal S1 foramen (DS1F) and ventral S1 foramen (VS1F) through computed tomography (CT) analysis and to prospectively determine the optimal angle of ipsilateral tunnel view technique for performing S1 transforaminal epidural steroid injection (S1-TFESI). METHODS: The axial lumbosacral CTs taken between in 208 consecutive patients and the following measurements were obtained on both sides: (1) the α-angle was defined as an angle between a sagittal line passing through the center of the sacrum and an imaginary line passing through the center of DS1F, (2) the largest diameter of DS1F and VS1F. The fluoroscopy was adjusted to show the largest L5/S1 intervertebral disc space, which was defined as the cephalad angle, and tilted to the ipsilateral oblique side until the entrance of DS1F had a well-defined, round shape, which defined as the ß-angle in 40 humans. RESULTS: CT measurements showed that the α-angle was 26.3 ± 3.3 degrees (15-38 degrees) and the diameter of DS1F was 7.1 ± 0.7 mm (4-10.9 mm), which was significantly smaller than the diameter of VS1F, 10.1 ± 1.0 mm (7.2-13.8 mm). The ß-angle was 24 ± 4.6 degrees, which was not much different from the α-angle and the cephalad angle was 23 ± 4.6 degrees. The success rate of S1-TFESI was 100% and there were no procedure-related complications. CONCLUSIONS: The entrance of DS1F is easily identified with an ipsilateral 25 degrees-tunnel view technique while performing S1-TFESI, and it is a clinically applicable approach.

Benefits of both physical assessment and electronic health record review to assess frailty prior to heart transplant.

INTRODUCTION: Frailty status affects outcomes after heart transplantation, but the optimal way to assess frailty prior to transplant remains unknown. METHODS: This single-center, observational study assessed 44 heart transplant candidates for frailty using three methods. The Short Physical Performance Battery (SPPB) and Fried Frailty Phenotype (FFP) were used as two physical assessments of frailty. The Frailty Risk Score (FRS) was used as a chart-review based assessment measuring 20 different biopsychosocial and functional components, including biomarkers, depression, cognitive impairment, and sleep. RESULTS: We determined the correlation between FRS, SPPB, and FFP and how each correlated with clinical outcomes. Of 44 participants, mean age was 60 years. FRS correlated with SPPB and FFP (P = .043, P < .001, respectively). Higher frailty as measured by SPPB and FRS was significantly associated with lack of achieving waitlist status (P = .022; P = .002) and not being transplanted (P = .026; P = .008). Higher frailty by SPPB and FFP was also associated with mortality (P = .010; P = .025). CONCLUSION: SPPB and chart-review FRS showed potential for predicting waitlist and transplant status of heart transplant candidates, while SPPB and FFP were associated with mortality. Additional studies may serve to validate these observations.

Predictors of COVID-19 outcomes: Interplay of frailty, comorbidity, and age in COVID-19 prognosis.

Prior research has identified frailty, comorbidity, and age as predictors of outcomes for patients with coronavirus disease 2019 (COVID-19), including mortality. However, it remains unclear how these factors play different roles in COVID-19 prognosis. This study focused on correlations between frailty, comorbidity and age, and their correlations to discharge outcome and length-of-stay in hospitalized patients with COVID-19. Clinical data was collected from 56 patients who were ≥50 years old and admitted from March 2020 to June 2020 primarily for COVID-19. Frailty Risk Score (FRS) and the Charlson Comorbidity Index (CCI) were used for assessment of frailty and comorbidity burden, respectively. Age had significant positive correlation with FRS and CCI (P < .001, P < .001, respectively). There was also significant positive correlation between FRS and CCI (P < .001). For mortality, patients who died during their hospitalization had significantly higher FRS and CCI (P = .01 and P < .001, respectively) but were not significantly older than patients who did not. FRS, CCI, and age were all significantly associated when looking at overall adverse discharge outcome (transfer to other facility or death) (P < .001, P = .005, and P = .009, respectively). However, none of the 3 variables were significantly correlated with length-of-stay. Multivariate analysis showed FRS (P = .007) but not patient age (P = .967) was significantly associated with death. We find that frailty is associated with adverse outcomes from COVID-19 and supplants age in multivariable analysis. Frailty should be part of risk assessment of older adults with COVID-19.

Atrial Cardiopathy Biomarkers and MRI-Based Infarct Patterns in Patients with Embolic Strokes of Undetermined Source.

OBJECTIVES: The study aimed to investigate whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration and/or left atrial volume index (LAVI), as atrial cardiopathy biomarkers, were associated with infarct patterns on diffusion-weighted imaging in patients with embolic strokes of undetermined source (ESUS). MATERIALS AND METHOD: We retrospectively evaluated patient with ESUS from our stroke registry between January 2018 and November 2019. Cut-off values for atrial cardiopathy biomarkers were defined as >250 pg/mL for NT-proBNP and >34 mL/m2 for LAVI. Eligible patients were then assigned to 3 groups and infarct patterns were compared according to their atrial cardiopathy markers: Group 1 (no atrial cardiopathy markers), Group 2 (one marker), and Group 3 (both markers). RESULTS: Among 194 eligible patients with ESUS (76 women; mean age, 69.2 years), simultaneous increases of NT-proBNP concentration and LAVI were identified in 39 (20.1%). Group 3 had a significantly larger infarct volume, relative to Group 1 and Group 2 (P=0.043) Multivariable logistic regression analyses revealed that these patients (Group 3) were significantly more likely to have multi-territorial infarcts (adjusted odds ratio [aOR]: 3.03, 95% confidence interval [CI]: 1.05-8.72; P=0.04), a maximal lesion diameter >15mm (aOR: 4.51, 95% CI: 1.70-11.93; P=0.001), and large cortical infarctions (aOR: 4.17, 95% CI: 1.75-9.96; P=0.001). CONCLUSION: We found that simultaneously increased values for NT-proBNP concentration and LAVI were independently associated with multi-territorial and large cortical infarct patterns in patients with ESUS. These findings suggest that NT-proBNP and LAVI may be useful biomarkers for identifying cardioembolic subtypes and guiding treatment selection in patients with ESUS.

Antioxidant Activity in Rheum emodi Wall (Himalayan Rhubarb).

Using natural products as antioxidant agents has been beneficial to replace synthetic products. Efforts have been made to profile the antioxidant capacities of natural resources, such as medicinal plants. The polyphenol content of Himalayan rhubarb, Rheum emodi wall, was measured and the antioxidant activity was determined using DPPH and ABTS+ assay, and the oxidative stress was assessed using SOD enzymatic assay. Five different solvent fractions, n-hexane, n-butanol, ethyl acetate, dichloromethane, and water, were used for screening the antioxidant capacity in effort to determine the optimum extraction solvent. The total phenolic contents for R. emodi fractions ranged from 27.76 to 209.21 mg of gallic acid equivalents (GAE)/g of dry weight. DPPH and ABTS+ assay results are presented into IC50 values, ranged from 21.52 to 2448.79 µg/mL and 90.25 to 1718.05 µg/mL, respectively. The ethyl acetate fraction had the highest antioxidant activity among other fractions. Also, n-butanol and water fractions showed significantly lower IC50 values than the positive control in DPPH radical scavenging activity. The IC50 values of SOD assay of fractions ranged from 2.31 to 64.78 µg/mL. A similar result was observed with ethyl acetate fraction showing the highest SOD radical scavenging activity. The study suggests that the ethyl acetate fraction of R. emodi possess the strongest antioxidant activity, thus the most efficient in extracting antioxidant contents. Moreover, a highly significant correlation was shown between total polyphenol content and antioxidant activity screening assays. The compounds related to the antioxidant activity of R. emodi were identified to myricitrin, myricetin 3-galloyl rhamnoside, and myricetin, which have not been reported in studies about R. emodi before.

Major QTLs, qARO1 and qARO9, Additively Regulate Adaxial Leaf Rolling in Rice.

Moderate leaf rolling is considered optimal for the ideal plant type in rice (Oryza sativa L.), as it improves photosynthetic efficiency and, consequently, grain yield. Determining the genetic basis of leaf rolling via the identification of quantitative trait loci (QTLs) could facilitate the development of high-yielding varieties. In this study, we identified three stable rice QTLs, qARO1, qARO5, and qARO9, which control adaxial leaf rolling in a recombinant inbred line (RIL) population derived from a cross between Tong 88-7 (T887) and Milyang 23 (M23), using high-density SNP markers. These QTLs controlled the rolling phenotype of both the flag leaf (FL) and secondary leaf (SL), and different allelic combinations of these QTLs led to a wide variation in the degree of leaf rolling. Additive gene actions of qARO1 and qARO9 on leaf rolling were observed in a backcross population. In addition, qARO1 (markers: 01id4854718 and 01asp4916781) and qARO9 (markers: 09id19650402 and 09id19740436) were successfully fine-mapped to approximately 60- and 90-kb intervals on chromosomes 1 and 9, respectively. Histological analysis of near-isogenic lines (NILs) revealed that qARO1 influences leaf thickness across the small vein, and qARO9 affects leaf thickness in the entire leaf and bulliform cell area, thus leading to adaxial leaf rolling. The results of this study advance our understanding of the genetic and molecular bases of adaxial leaf rolling, and this information can be used for the development of rice varieties with the ideal plant type.

Can we Predict the Clinical Course of Immune Thrombocytopenia in Children by The Mean Platelet Volume? A Preliminary Study.

BACKGROUND: Mean platelet volume (MPV) is considered a marker of platelet function and is known to increase in immune thrombocytopenia (ITP). We aimed to investigate the predictive value of MPV for predicting the clinical course of ITP in children. METHODS: We retrospectively analyzed children aged < 18 years with ITP (n = 36) and healthy controls (n = 36) from June 2010 to November 2018. The subjects were stratified into: (i) Healthy controls [group I, n = 36]; (ii) Newly diagnosed ITP (nITP) and persistent ITP (pITP) [group II, n = 24]; and (iii) Chronic ITP (cITP) [group III, n = 12]. Hematological indices including MPV were measured and compared between the three groups. RESULTS: The median MPV values at diagnosis in group I, II, and III were 7.20, 8.15, and 8.65 fL, respectively (p = 0.0004). Cutoff value of MPV at diagnosis differentiating group I from group II + III was 7.6 fL, and group II from group III was 8.7 fL. MPV change (ΔMPV after three months minus MPV at diagnosis) in children with nITP and pITP (n = 22) was greater than in those with cITP (n = 6) (-2.18 fL vs. 0.66 fL, p = 0.0059). CONCLUSIONS: This study revealed that group III had a higher MPV than group II at diagnosis. Therefore, an initial MPV value more than 8.7 fL may be used as a predictive factor for chronicity in children with ITP. The change in MPV over time as well as MPV at diagnosis, may be regarded as a prognostic marker to predict the course of ITP in children.

Genetic Basis of Tiller Dynamics of Rice Revealed by Genome-Wide Association Studies.

A tiller number is the key determinant of rice plant architecture and panicle number and consequently controls grain yield. Thus, it is necessary to optimize the tiller number to achieve the maximum yield in rice. However, comprehensive analyses of the genetic basis of the tiller number, considering the development stage, tiller type, and related traits, are lacking. In this study, we sequence 219 Korean rice accessions and construct a high-quality single nucleotide polymorphism (SNP) dataset. We also evaluate the tiller number at different development stages and heading traits involved in phase transitions. By genome-wide association studies (GWASs), we detected 20 significant association signals for all traits. Five signals were detected in genomic regions near known candidate genes. Most of the candidate genes were involved in the phase transition from vegetative to reproductive growth. In particular, HD1 was simultaneously associated with the productive tiller ratio and heading date, indicating that the photoperiodic heading gene directly controls the productive tiller ratio. Multiple linear regression models of lead SNPs showed coefficients of determination (R2) of 0.49, 0.22, and 0.41 for the tiller number at the maximum tillering stage, productive tiller number, and productive tiller ratio, respectively. Furthermore, the model was validated using independent japonica rice collections, implying that the lead SNPs included in the linear regression model were generally applicable to the tiller number prediction. We revealed the genetic basis of the tiller number in rice plants during growth, By GWASs, and formulated a prediction model by linear regression. Our results improve our understanding of tillering in rice plants and provide a basis for breeding high-yield rice varieties with the optimum the tiller number.

Characterization of the Common Japonica-Originated Genomic Regions in the High-Yielding Varieties Developed from Inter-Subspecific Crosses in Temperate Rice (Oryza sativa L.).

The inter-subspecific crossing between indica and japonica subspecies in rice have been utilized to improve the yield potential of temperate rice. In this study, a comparative study of the genomic regions in the eight high-yielding varieties (HYVs) was conducted with those of the four non-HYVs. The Next-Generation Sequencing (NGS) mapping on the Nipponbare reference genome identified a total of 14 common genomic regions of japonica-originated alleles. Interestingly, the HYVs shared japonica-originated genomic regions on nine chromosomes, although they were developed through different breeding programs. A panel of 94 varieties was classified into four varietal groups with 38 single nucleotide polymorphism (SNP) markers from 38 genes residing in the japonica-originated genomic regions and 16 additional trait-specific SNPs. As expected, the japonica-originated genomic regions were only present in the japonica (JAP) and HYV groups, except for Chr4-1 and Chr4-2. The Wx gene, located within Chr6-1, was present in the HYV and JAP variety groups, while the yield-related genes were conserved as indica alleles in HYVs. The japonica-originated genomic regions and alleles shared by HYVs can be employed in molecular breeding programs to further develop the HYVs in temperate rice.

Spin Label Scanning Reveals Likely Locations of ß-Strands in the Amyloid Fibrils of the Ure2 Prion Domain.

In yeast, the formation of Ure2 fibrils underlies the prion state [URE3], in which the yeast loses the ability to distinguish good nitrogen sources from bad ones. The Ure2 prion domain is both necessary and sufficient for the formation of amyloid fibrils. Understanding the structure of Ure2 fibrils is important for understanding the propagation not only of the [URE3] prion but also of other yeast prions whose prion domains share similar features, such as the enrichment of asparagine and glutamine residues. Here, we report a structural study of the amyloid fibrils formed by the Ure2 prion domain using site-directed spin labeling and electron paramagnetic resonance (EPR) spectroscopy. We completed a spin label scanning of all the residue positions between 2 and 80 of the Ure2 prion domain. The EPR data show that the Ure2 fibril core consists of residues 8-68 and adopts a parallel in-register ß-sheet structure. Most of the residues show strong spin-exchange interactions, suggesting that there are only short turns and no long loops in the fibril core. Based on the strength of spin-exchange interactions, we determined the likely locations of the ß-strands. EPR data also show that the C-terminal region of the Ure2 prion domain is more disordered than the N-terminal region. The roles of hydrophobic and charged residues are analyzed. Overall, the structure of Ure2 fibrils appears to involve a balance of stabilizing interactions, such as asparagine ladders, and destabilizing interactions, such as stacking of charged residues.

Polymorphic Aß42 fibrils adopt similar secondary structure but differ in cross-strand side chain stacking interactions within the same ß-sheet.

Formation of polymorphic amyloid fibrils is a common feature in neurodegenerative diseases involving protein aggregation. In Alzheimer's disease, different fibril structures may be associated with different clinical sub-types. Structural basis of fibril polymorphism is thus important for understanding the role of amyloid fibrils in the pathogenesis and progression of these diseases. Here we studied two types of Aß42 fibrils prepared under quiescent and agitated conditions. Quiescent Aß42 fibrils adopt a long and twisted morphology, while agitated fibrils are short and straight, forming large bundles via lateral association. EPR studies of these two types of Aß42 fibrils show that the secondary structure is similar in both fibril polymorphs. At the same time, agitated Aß42 fibrils show stronger interactions between spin labels across the full range of the Aß42 sequence, suggesting a more tightly packed structure. Our data suggest that cross-strand side chain packing interactions within the same ß-sheet may play a critical role in the formation of polymorphic fibrils.

Mapping and Validation of QTLs for the Amino Acid and Total Protein Content in Brown Rice.

Highly nutritious rice production will be benefited with the improvement of amino acid content (AAC) and protein content (PC). The identification of quantitative trait loci (QTLs) associated with the PC and AAC of rice grains could provide a basis for improving the nutritional value of rice grains. Here, we conducted QTL analyses using recombinant inbred lines from the cross between indica (Milyang 23 or M23) and japonica (Tong 88-7 or T887) rice varieties, afterward employing genotyping-by-sequencing to obtain a high-density genetic map. A total of 17 and 3 QTLs were detected for AAC and PC, respectively. Among them, two QTLs associated with more than 10 AACs, qAAC6.1 and qAAC7.1, were identified for the first time in this study. Each favorable allele that increased the AAC of the two QTLs was derived from M23 and T887, respectively. Allelic combination of qAAC6.1 M23 and qAAC7.1T887 showed significantly higher content of associated amino acids (AAs) than other allelic combinations. Near-isogenic line (NIL) possessing qAAC7.1T887 with M23 genetic background had significantly higher AACs than both parents. These results indicate that the pyramiding of QTLs would be useful in developing brown rice with a high AA and protein content.