An SEI model for sarcoptic mange among chamois

We consider a simple model to study the dynamics of sarcoptic mange in a population of chamois. The epidemiological patterns observed during an epidemic in Italy are reconstructed and key parameters of the model are estimated from field data. In particular, we calculate the basic reproductive ratio R ₀, a threshold value for chamois density for the occurrence of an epidemic and the speed of propagation of the epidemic wave. The model is then used to obtain indications on the effect of culling as a possible control measure in a closed population and extended to analyse the spatial diffusion of the epidemic. Our results are in agreement with mange epidemiology and observations, and suggest that intervention could be efficacious in reducing the impact of an epidemic.     

一个马铃薯种质资源圃致病疫霉群体的分析

由致病疫霉Phytophthora infestans引起的晚疫病是马铃薯生产上最严重的病害之一,认识其群体结构特征,可为晚疫病防控策略的制定以及抗病品种的合理布局提供指导。对2009年采自宁夏一个种植有93个品种(品系)的马铃薯种质资源圃的致病疫霉进行了交配型、致病型和线粒体DNA单倍型分析,结果表明,116个致病疫霉菌株中存在A1、A2和自育型3种交配型,发生频率分别为24.1%、57.8%和18.1%,A2交配型为优势类型;对其中43个菌株的致病型进行测试,检测到两种致病类型:1.2.3.4.5.6.7.8.9.10.11和3.4.10,发生频率分别为95.3%和4.7%,可克服所有11个抗病基因的1.2.3.4.5.6.7.8.9.10.11类型占绝对优势;对62个菌株的线粒体DNA单倍型进行分析,检测到Ia和IIa两种类型,发生频率分别为74.2%和25.8%。综合表型和基因型数据分析发现,该马铃薯种质资源圃中致病疫霉群体致病型单一,但致病型毒力因子高度复合;线粒体DNA分析表明,该马铃薯种质资源圃引入了遗传背景较为复杂的致病疫霉"新"群体。     

Application of Artificial Bee Colony Algorithm to Maximum Likelihood DOA Estimation

Maximum Likelihood (ML) method has an excellent performance for Direction-Of-Arrival (DOA) estimation, but a multidimensional nonlinear solution search is required which complicates the computation and prevents the method from practical use. To reduce the high computational burden of ML method and make it more suitable to engineering applications, we apply the Artificial Bee Colony (ABC) algorithm to maximize the likelihood function for DOA estimation. As a recently proposed bio-inspired computing algorithm, ABC algorithm is originally used to optimize multivariable functions by imitating the behavior of bee colony finding excellent nectar sources in the nature environment. It offers an excellent alternative to the conventional methods in ML-DOA estimation. The performance of ABC-based ML and other popular meta-heuristic-based ML methods for DOA estimation are compared for various scenarios of convergence, Signal-to-Noise Ratio (SNR), and number of iterations. The computation loads of ABC-based ML and the conventional ML methods for DOA estimation are also investigated. Simulation results demonstrate that the proposed ABC based method is more efficient in computation and statistical performance than other ML-based DOA estimation methods.     

GAP promoter‐based fed‐batch production of highly bioactive core streptavidin by Pichia pastoris

Streptavidin is a homotetrameric protein binding the vitamin biotin and peptide analogues with an extremely high affinity, which leads to a large variety of applications. The biotin‐auxotrophic yeast Pichia pastoris has recently been identified as a suitable host for the expression of the streptavidin gene, allowing both high product concentrations and productivities. However, so far only methanol‐based expression systems have been applied, bringing about increased oxygen demand, strong heat evolution and high requirements for process safety, causing increased cost. Moreover, common methanol‐based processes lead to large proportions of biotin‐blocked binding sites of streptavidin due to biotin‐supplemented media. Targeting these problems, this paper provides strategies for the methanol‐free production of highly bioactive core streptavidin by P. pastoris under control of the constitutive GAP promoter. Complex were superior to synthetic production media regarding the proportion of biotin‐blocked streptavidin. The optimized, easily scalable fed‐batch process led to a tetrameric product concentration of up to 4.16 ± 0.11 µM of biotin‐free streptavidin and a productivity of 57.8 nM h^?1 based on constant glucose feeding and a successive shift of temperature and pH throughout the cultivation, surpassing the concentration in un‐optimized conditions by a factor of 3.4. Parameter estimation indicates that the optimized conditions caused a strongly increased accumulation of product at diminishing specific growth rates (μ ≈ D < 0.01 h^?1), supporting the strategy of feeding. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:855–864, 2016     

High‐throughput multiplex cpDNA resequencing clarifies the genetic diversity and genetic relationships among Brassica napus,Brassica rapa and Brassica oleracea

Brassica napus (rapeseed) is a recent allotetraploid plant and the second most important oilseed crop worldwide. The origin of B. napus and the genetic relationships with its diploid ancestor species remain largely unresolved. Here, chloroplast DNA (cpDNA) from 488 B. napus accessions of global origin, 139 B. rapa accessions and 49 B. oleracea accessions were populationally resequenced using Illumina Solexa sequencing technologies. The intraspecific cpDNA variants and their allelic frequencies were called genomewide and further validated via EcoTILLING analyses of the rpo region. The cpDNA of the current global B. napus population comprises more than 400 variants (SNPs and short InDels) and maintains one predominant haplotype (Bncp1). Whole‐genome resequencing of the cpDNA of Bncp1 haplotype eliminated its direct inheritance from any accession of the B. rapa or B. oleracea species. The distribution of the polymorphism information content (PIC) values for each variant demonstrated that B. napus has much lower cpDNA diversity than B. rapa; however, a vast majority of the wild and cultivated B. oleracea specimens appeared to share one same distinct cpDNA haplotype, in contrast to its wild C‐genome relatives. This finding suggests that the cpDNA of the three Brassica species is well differentiated. The predominant B. napus cpDNA haplotype may have originated from uninvestigated relatives or from interactions between cpDNA mutations and natural/artificial selection during speciation and evolution. These exhaustive data on variation in cpDNA would provide fundamental data for research on cpDNA and chloroplasts.     

Home range size of adult Indo‐Pacific bottlenose dolphins (Tursiops aduncus) in a coastal and estuarine system is habitat and sex‐specific

This study examined sex‐specific differences in home range size of adult Indo‐Pacific bottlenose dolphins off Bunbury, Western Australia. We applied a new kernel density estimation approach that accounted for physical barriers to movements. A Bayesian mixture model was developed to estimate a sex effect in home range size with latent group partitioning constrained by association data. A post hoc analysis investigated group partitioning relating to the proportion of time spent in open vs. sheltered waters. From 2007 to 2013, photographic‐identification data were collected along boat‐based systematic transect lines (n = 586). Analyses focused on adult dolphins of known sex (sighted ≥ 30 times; n = 22 males and 34 females). The 95% utilization distributions of males varied between 27 and 187 km² (; 94.8 ± 48.15) and for females between 20 and 133 km² (65.6 ± 30.9). The mixture model indicated a 99% probability that males had larger home ranges than females. Dolphins mostly sighted in open waters had larger home ranges than those in sheltered waters. Home ranges of dolphins sighted in sheltered waters overlapped with areas of highest human activity. We suggest that sex differences in home ranges are driven by male mating strategies, and home range size differences between habitats may be influenced by prey availability and predation risk.