Genomics-based discrimination of 2n gamete formation mechanisms in polyploids: a case study in nonaploid Diospyros kaki ‘Akiou’

Unreduced gametes (2n gametes), possessing double the haploid genome, whatever ploidy that happens to be, are a common source of ploidy variation in plant populations. First and second division restitution (FDR and SDR) are the dominant mechanisms of 2n gamete production; all else being equal, FDR gametes have a higher degree of heterozygosity, thus they are advantageous in breeding. The discrimination of these mechanisms from the consequence of hybridization is challenging, especially in higher polyploids, and usually requires information on centromere location. In this study, we propose a genotyping-based strategy to uncover the mechanisms of 2n gamete formation in progeny that has a higher ploidy than its parents. Simulation of 2n gamete production revealed that FDR and SDR pathways can be discriminated based on allele transmission patterns alone without information on centromere location. We applied this strategy to study the formation mechanism of a nonaploid Diospyros kaki ‘Akiou', which was bred via hybridization between D. kaki hexaploid cultivars. The result demonstrated that ‘Akiou' was derived from the fertilization of a normal female gamete by a 2n male gamete and that this 2n gamete was produced through FDR. Consequently, the distinct duplex transmission pattern in the FDR gamete enabled us to infer the genomic characteristics of polyploid persimmon. The method could be tested only for the plant being polypoid, which allows for the ability to discriminate causes of 2n gamete formation using allele dosage in progeny, and will be useful in future studies of polyploid genomics

The role of the outer boundary condition in accretion disk models: theory and application

The influence of the outer boundary condition (OBC) on the dynamics and radiation of optically thin accretion flow is investigated. Bremsstrahlung and synchrotron radiations amplified by Comptonization are taken into account and two-temperature plasma assumption is adopted. The three OBCs we adopted are the temperatures of the electrons and ions and the specific angular momentum of the accretion flow at a certain outer boundary. We find that when the general parameters such as the mass accretion rate and the viscous parameter are fixed, the peak flux at various bands such as radio, IR and X-ray, can differ by as large as several orders of magnitude under different OBCs in our example. Our results indicate that OBC is both dynamically and radiatively important therefore should be regarded as a new ``parameter'' in accretion disk models. We apply the above results to the compact radio source Sgr A* and find that the discrepancy between the mass accretion rate favored by ADAF models in the literature and that favored by the three dimensional hydrodynamical simulation can be naturally resolved by seriously considering the outer boundary condition of the accretion flow.Comment: 23 pages, 9 figures,accepted by the Astrophysical Journa

Highly Prevalent Multidrug-Resistant Salmonella From Chicken and Pork Meat at Retail Markets in Guangdong, China

This study aimed to investigate the prevalence, serotype distribution, and antibiotic resistance, and to characterize the extended spectrum β-lactamases (ESBLs) producing Salmonella isolates from chicken and pork meats from retail markets in Guangdong province, China. A total of 903 retail meat samples (475 chicken and 428 pork meats) were obtained from six cities (Guangzhou, Shenzhen, Heyuan, Shaoguan, Foshan, and Yunfu) of Guangdong province between May 2016 and April 2017. High levels of Salmonella contamination were detected in chicken (302/475, 63.6%) and pork (313/428, 73.1%). Thirty-eight serotypes were identified in 615 detected Salmonella, and the serotypes varied greatly between chicken and pork samples. Agona (55/302, 18.2%), Corvallis (45/302, 14.9%), Kentucky (38/302, 12.6%), Mbandaka (32/302, 10.6%) was the dominant serotypes in chicken samples. However, Typhimurium (78/313, 24.9%), Rissen (67/313, 24.1%), Derby (66/313, 21.1%), and London (48, 15.3%) were the most common in pork samples. High rates of antibiotic resistance were found to sulfisoxazole (468/615, 76.1%), tetracycline (463/615, 75.3%), ampicillin (295/615, 48.0%), and ofloxacin (275/615, 44.7%). Notably, antimicrobial susceptibility tests identified resistance to polymyxin B (12/615, 2.0%) and imipenem (3/615, 0.5%). Multidrug-resistance (MDR) was detected in Salmonella isolated from chicken (245/302, 81.1%) and pork (229/313, 73.2%). The resistance rate of different Salmonella serotypes varied widely. Especially, isolates such as Typhimurium, Agona, Corvallis and Kentucky exhibited highly resistance to antibiotics. The MDR rate of Salmonella isolates from chicken was significantly higher than that from pork isolates (P < 0.05). Twenty-one Salmonella isolates were identified as ESBLs-producing, covering six Salmonella serotypes and displaying different pulse field gel electrophoresis (PFGE) genotypes. BlaOXA-1 was the dominant ESBLs gene (9/21, 42.9%), followed by blaCTX-M-55 (5/21, 23.8%). This study indicated that Salmonella was widespread in chicken and pork from retail markets in Guangdong province and the isolates showed high multidrug-resistance, especially the known multidrug-resistant Salmonella serotypes. Therefore, it is important to focus on Salmonella serotypes and strengthen the long-term monitoring of MDR Salmonella serotypes in animal-derived foods

Tau Pathology in Parkinson's Disease

Tau protein—a member of the microtubule-associated protein family—is a key protein involved in many neurodegenerative diseases. Tau pathology in neurodegenerative diseases is characterized by pathological tau aggregation in neurofibrillary tangles (NFTs). Diseases with this typical pathological feature are called tauopathies. Parkinson's disease (PD) was not initially considered to be a typical tauopathy. However, recent studies have demonstrated increasing evidence of tau pathology in PD. A genome-wide association (GWA) study indicated a potential association between tauopathy and sporadic PD. The aggregation and deposition of tau were also observed in ~50% of PD brains, and it seems to be transported from neuron to neuron. The aggregation of NFTs, the abnormal hyperphosphorylation of tau protein, and the interaction between tau and alpha-synuclein may all contribute to the cell death and poor axonal transport observed in PD and Parkinsonism

Diversity analysis of agronomic and nutritional traits of hybrid offspring of forage bermudagrass

Because of its excellent stress resistance and forage quality, the forage bermudagrass hybrid population had attracted the attention of scientific researchers in recent years. Studying its diversity could promote the breeding of desirable varieties. The variability in agronomic traits including fresh weight, dry weight, ash content, crude protein content, crude fat, phosphorus content, and relative feed value for 56 bermudagrass was investigated using Wrangler as an experimental reference. Grey correlation analysis and cluster analysis were employed to screen bermudagrass with high yield and superior quality. WCF-34 had the highest 2-year fresh weight (109,773.3 kg/ha), WCF-37 had the highest 2-year dry weight (31,951.6 kg/ha), WCF-24 had the lowest Ash content (7.46%), WCF-26 had the highest crude protein content (16.27%), WCF-27 had the highest curde fat content (3.58%), WCF-13 had the highest P content (0.45%), and WCF-42 had the highest relative feed value (95.32). Combining the results of grey relational analysis and cluster analysis, WCF-42, WCF-34, WCF-38, WCF-37, and WCF-40 were selected as high-quality bermudagrass. Through comprehensive analysis of the agronomic characters of bermudagrass, five bermudagrass were selected, the outcomes of this study would provide a theoretical basis for the breeding and genetic enhancement of bermudagrass