Cloning of the Lentinula edodes B mating-type locus and identification of the genetic structure controlling B mating

During the life cycle of heterothallic tetrapolar Agaricomycetes such as Lentinula edodes (Berk.) Pegler, the mating type system, composed of unlinked A and B loci, plays a vital role in controlling sexual development and resulting formation of the fruit body. L. edodes is produced worldwide for consumption and medicinal purposes, and understanding its sexual development is therefore of great importance. A considerable amount of mating type factors has been indicated over the past decades but few genes have actually been identified, and no complete genetic structures of L. edodes B mating-type loci are available. In this study, we cloned the matB regions from two mating compatible L. edodes strains, 939P26 and 939P42. Four pheromone receptors were identified on each new matB region, together with three and four pheromone precursor genes in the respective strains. Gene polymorphism, phylogenetic analysis and distribution of pheromone receptors and pheromone precursors clearly indicate a bipartite matB locus, each sublocus containing a pheromone receptor and one or two pheromone precursors. Detailed sequence comparisons of genetic structures between the matB regions of strains 939P42, 939P26 and a previously reported strain SUP2 further supported this model and allowed identification of the B mating type subloci borders. Mating studies confirmed the control of B mating by the identified pheromone receptors and pheromones in L. edodes.     

Is CD36 gene polymorphism in region encoding lipid-binding domain associated with early onset CAD?

CD36 is a fatty acid translocase in striated muscle cells and cardiomyocytes. Some study suggested that alterations in CD36 gene may be associated with coronary artery disease (CAD) risk. The aim of the current study was to compare the frequency of CD36 variants in region encoding lipid-binding domain in Caucasian patients with early-onset CAD, no-CAD adult controls and neonates. The study group comprised 100 patients with early onset CAD. The genetic control groups were 306 infants and 40 no-CAD adults aged over 70 years. Exons 4, 5 and 6 including fragments of flanking introns were studied using the denaturing high-performance liquid chromatography technique and direct sequencing. Changes detected in analyzed fragment of CD36: IVS3-6 T/C (rs3173798), IVS4-10 G/A (rs3211892), C311T (Thr104Ile, not described so far) in exon 5, G550A (Asp184Asn, rs138897347), C572T (Pro191Leu, rs143150225), G573A (Pro191Pro, rs5956) and A591T (Thr197Thr, rs141680676) in exon 6. No significant differences in the CD36 genotype, allele and haplotype frequencies were found between the three groups. Only borderline differences (p = 0.066) were found between early onset CAD patients and newborns in the frequencies of 591T allele (2.00% vs 0.50%) and CGCGCGT haplotype (2.00% vs 0.50%) with both IVS3-6C and 591T variant alleles. In conclusion, CD36 variants: rs3173798, rs3211892, rs138897347, rs5956, rs143150225 rs141680676 and C311T do not seem to be involved in the risk of early-onset CAD in Caucasian population.     

Locating QTLs controlling several adult root traits in an elite Chinese hybrid rice

This study aimed to elucidate the genetics of the adult root system in elite Chinese hybrid rice. Several adult root traits in a recombinant inbred line (RIL) population of Xieyou 9308 and two backcross F₁ (BCF₁) populations derived from the RILs were phenotyped under hydroponic culture at heading stage for quantitative trait locus (QTL) mapping and other statistical analysis. There a total of eight QTLs detected for the root traits. Among of them, a pleiotropic QTL was repeatedly flanked by RM180 and RM5436 on the short arm of chromosome 7 for multiple traits across RILs and its BCF₁ populations, accounting for 6.88% to 25.26% of the phenotypic variances. Only additive/dominant QTLs were detected for the root traits. These results can serve as a foundation for facilitating future cloning and molecular breeding.     

Grand Molecular Dynamics: A Method for Open Systems

We present a new molecular dynamics method for studying the dynamics of open systems. The method couples a classical system to a chemical potential reservior. In the formulation, following the extended system dynamics approach, we introduce a variable, v to represent the coupling to the chemical potential reservoir. The new variable governs the dynamics of the variation of number of particles in the system. The number of particles is determined by taking the integer part of v. The fractional part of the new variable is used to scale the potential energy and the kinetic energy of an additional particle: i.e., we introduce a fractional particle. We give the ansatz Lagrangians and equations of motion for both the isothermal and the adiabatic forms of grand molecular dynamics. The averages calculated over the trajectories generated by these equations of motion represent the classical grand canonical ensemble (μVT) and the constant chemical potential adiabatic ensemble (μVL) averages, respectively. The microcanonical phase space densities of the adiabatic and isothermal forms the molecular dynamics method are shown to be equivalent to adiabatic constant chemical potential ensemble, and grand canonical ensemble partition functions. We also discuss the extension to multi-component systems, molecular fluids, ionic solutions and the problems and solutions associated with the implementation of the method. The statistical expressions for thermodynamic functions such as specific heat; adiabatic bulk modulus, Grüneissen parameter and number fluctuations are derived. These expressions are used to analyse trajectories of constant chemical potential systems.     

昆虫质型多角体病毒同义密码子使用模式分析

昆虫质型多角体病毒(cypovirus,CPV)是害虫种群重要调节因子,可用作生物防治剂。本研究采用多元统计分析方法对7种CPV进行密码子使用模式分析,结果表明:CPV密码子使用偏好性较弱,多数基因密码子使用模式受碱基组成影响,少数基因密码子使用模式除碱基组成外还有其它影响因素;中性绘图分析表明碱基组成主要受选择压力影响,受突变影响较小。同一电泳型CPV之间比同一宿主CPV之间共有的偏好性密码子多。CPV基因组内10个基因组片段之间密码子偏好性存在差异。CPV密码子偏好性与宿主昆虫密码子偏好性存在差异,所有CPV与其宿主昆虫共有的偏好性密码子均较少。对应分析进一步证明碱基组成是影响密码子使用的主要因素,不同电泳型CPV具有不同的密码子使用模式。聚类分析表明同一电泳型CPV密码子使用模式相似,同一宿主CPV密码子使用模式差异较大。     

Modeling the impact of early therapy for latent tuberculosis patients and its optimal control analysis

Effective tuberculosis (TB) control depends on case findings to discover infectious cases, investigation of contacts of those with TB, as well as appropriate treatment. Adherence and successful completion of the treatment are equally important. Unfortunately, due to a number of personal, psychosocial, economic, medical, and health service factors, a significant number of TB patients become irregular and default from treatment. In this paper, a mathematical model is developed to assess the impact of early therapy for latent TB and non-adherence on controlling TB transmission dynamics. Equilibrium states of the model are determined and their local stability is examined. With the aid of the center manifold theory, it is established that the model undergoes a backward bifurcation. Qualitative mathematical analysis of the model suggests that a high level of latent tuberculosis case findings, coupled with a decrease of defaulting rate, may be effective in controlling TB transmission dynamics in the community. Population-level effects of organized campaigns to improve early therapy and to guarantee successful completion of each treatment are evaluated through numerical simulations and presented in support of the analytical results.     

Production of phenolics and the emission of volatile organic compounds by perennial ryegrass (Lolium perenne L.)/Neotyphodium lolii association as a response to infection by Fusarium poae

Grasses very often form symbiotic associations with Neotyphodium/Epichloë endophytic fungi. These endophytes often allow the host grass to be protected from different pathogens. However, there is little known about the mechanisms of such endophyte influence on the host. Thus, the purpose of this research was to examine the effect of the N. lolii endophyte on the total production of phenolic compounds, VOCs emission and the resistance of three perennial ryegrass genotypes infected by pathogenic Fusarium poae. Analyses of total phenolics content were performed in control (not inoculated) and inoculated plants after 1, 2, 3, 4, 5, and 6 days (DAI) and for VOCs after 0, 3, 6 and 12 DAI. The presence of endophytes significantly reduced the disease index in two of the three genotypes relative to that in E−. Plants infected by N. lolii exhibited higher production of phenolics relative to the E− plants. The highest amounts of phenolics were observed on the second and sixth DAI. Genotype Nl22 showed the strongest effect of the endophyte on the production of phenolics, which increased by over 61%. Both the endophyte infected and non-infected plants emitted most abundantly two GLVs ((Z)-3-hexenal, (Z)-3-hexen-1-yl acetate), three terpenes (linalool, (Z)-ocimene, β-caryophyllene) and three shikimic acid pathway derivatives (benzyl acetate, indole, and methyl salicylate). The endophyte presence and the intervals of VOCs detection were a highly significant source of variation for all emitted volatiles (P < 0.001). The genotype of the perennial ryegrass significantly affected only the emission of methyl salicylate (P < 0.05) and β-caryophyllene (P < 0.05). Most of the VOCs ((Z)-3-hexen-1-yl acetate, (Z)-3-hexenal, linalool and methyl salicylate) reached their highest levels of emission on the sixth DAI, when averaged over genotypes and endophyte status. The results highlight the role of Neotyphodium spp. in the mediation of quadro-trophic interactions among plants, symbiotic endophytes, invertebrate herbivores and plant pathogenic fungi. Our results also confirm the fact that symbiotic plants can activate a defense reaction faster than non-symbiotic plants after a pathogen attack. Thus, N. lolii can be involved in the defense of perennial ryegrass against pathogens and potentially could be central to the host plants’ protection.     

Allelic Diversity and Its Implications for the Rate of Adaptation

Genetic variation is usually estimated empirically from statistics based on population gene frequencies, but alternative statistics based on allelic diversity (number of allelic types) can provide complementary information. There is a lack of knowledge, however, on the evolutionary implications attached to allelic-diversity measures, particularly in structured populations. In this article we simulated multiple scenarios of single and structured populations in which a quantitative trait subject to stabilizing selection is adapted to different fitness optima. By forcing a global change in the optima we evaluated which diversity variables are more strongly correlated with both short- and long-term adaptation to the new optima. We found that quantitative genetic variance components for the trait and gene-frequency-diversity measures are generally more strongly correlated with short-term response to selection, whereas allelic-diversity measures are more correlated with long-term and total response to selection. Thus, allelic-diversity variables are better predictors of long-term adaptation than gene-frequency variables. This observation is also extended to unlinked neutral markers as a result of the information they convey on the demographic population history. Diffusion approximations for the allelic-diversity measures in a finite island model under the infinite-allele neutral mutation model are also provided.     

A modified FCR test to evaluate pollen viability in Juniperus communis L.

Pollen viability of Juniperus communis L. and other gymnosperms with taxoid type pollen cannot be assessed with the more common viability tests because the thick sporoderm prevents reagents from penetrating into the cytoplasm. Here we describe a technique for pre‐hydration of pollen that overcomes this problem so that the common FCR test can be used to assess its viability. Pollen of J. communis must be re‐hydrated by suspending in water. This re‐hydration causes the splitting of the exine and a huge swelling of the intine. The sporoderm becomes permeable to fluoresceine diacetate and the FCR‐viability test can be applied. The FCR result is supported by scoring the germination percentage in vitro.