Rapid Reconstitution of Biosynthetic Machinery for Fungal Metabolites in Aspergillus oryzae: Total Biosynthesis of Aflatrem

Reconstitution of the biosynthetic machinery for fungal secondary metabolites in Aspergillus oryzae provides an opportunity both for stepwise determination of the biosynthetic pathways and the total biosynthesis of fungal natural products. However, to maximize the utility of the reconstitution system, a simple and rapid strategy for the introduction of heterologous genes into A. oryzae is required. In this study, we demonstrated an effective method for introducing multiple genes involved in the biosynthesis of fungal metabolites by using the expression vectors pUARA2 and pUSA2, each of which contains two cloning sites. The successful introduction of all the aflatrem biosynthetic genes (seven genes in total) after two rounds of transformation enabled the total biosynthesis of aflatrem. This rapid reconstitution strategy will facilitate the functional analysis of the biosynthetic machinery of fungal metabolites.     

基于Volterra 级数对火工品起爆过程的辨识

为解决火工品起爆过程中线性函数不能解决元件参数变化、不确定性和非线性强的问题,将Volterra 级 数模型与基因表达式编程(gene expression programing,GEP)相结合,设计一种新的火工品起爆过程辨识算法。利用 Volterra 级数能准确反应非线性系统的特征来描述火工品起爆过程,GEP 算法则克服传统辨识方法的不足,辨识出正 确的模型。仿真结果表明,该方法能精确、快速地辨识出火工品起爆过程。     

AuCuI（A8AuA4Cu）化合物无序化路径跟踪的原子移动新机制

以由AAu8和ACu4干基因组成的AuCuI（AAu Cu8 A4）化合物的无序化实验路径为例,介绍了3个发现和1个方法。发现AuCuI（AAuCu8A4）化合物抗拒温度变化保持结构稳定性的能力归因于AAu8和ACu4基因的势阱深度远超过其振动能,这导致其无序化实验路径是亚平衡的;发现AuCuI（AAu Cu8 A4）适应温度变化改变结构的原子移动新机制是合金基因的＂共振激活-同步交换＂机制,这导致无序化是非均匀性和递次性的亚平衡转变;发现无序化过程中存在跳变有序度,导致存在跳变温度和升温速度增加跳变温度降低的＂逆反效应＂,即所谓的＂Retro效应＂。采用实验混合焓路径法,建立了一整套亚平衡全息网络路径图。     

Delayed self-regulation and time-dependent chemical drive leads to novel states in epigenetic landscapes

The epigenetic pathway of a cell as it differentiates from a stem cell state to a mature lineage-committed one has been historically understood in terms of Waddington''s landscape, consisting of hills and valleys. The smooth top and valley-strewn bottom of the hill represent their undifferentiated and differentiated states, respectively. Although mathematical ideas rooted in nonlinear dynamics and bifurcation theory have been used to quantify this picture, the importance of time delays arising from multistep chemical reactions or cellular shape transformations have been ignored so far. We argue that this feature is crucial in understanding cell differentiation and explore the role of time delay in a model of a single-gene regulatory circuit. We show that the interplay of time-dependent drive and delay introduces a new regime where the system shows sustained oscillations between the two admissible steady states. We interpret these results in the light of recent perplexing experiments on inducing the pluripotent state in mouse somatic cells. We also comment on how such an oscillatory state can provide a framework for understanding more general feedback circuits in cell development.     

Electricity generation and microbial community structure of air-cathode microbial fuel cells powered with the organic fraction of municipal solid waste and inoculated with different seeds

The organic fraction of municipal solid waste (OFMSW), normally exceeding 60% of the waste stream in developing countries, could constitute a valuable source of feed for microbial fuel cells (MFCs). This study tested the start-up of two sets of OFMSW-fed air-cathode MFCs inoculated with wastewater sludge or cattle manure. The maximum power density obtained was 123 ± 41 mW m⁻² in the manure-seeded MFCs and 116 ± 29 mW m⁻² in the wastewater-seeded MFCs. Coulombic efficiencies ranged between 24 ± 5% (manure-seeded MFCs) and 23 ± 2% (wastewater-seeded MFCs). Chemical oxygen demand removal was >86% in all the MFCs and carbohydrate removal >98%. Microbial community analysis using 16S rRNA gene pyrosequencing demonstrated the dominance of the phylum Firmicutes (67%) on the anode suggesting the possible role of members of this phylum in electricity generation. Principal coordinate analysis showed that the microbial community structure in replicate MFCs converged regardless of the inoculum source. This study demonstrates efficient electricity production coupled with organic treatment in OFMSW-fueled MFCs inoculated with manure or wastewater.