Comparing urban food system characteristics and actions in US and Indian cities from a multi‐environmental impact perspective: Toward a streamlined approach

Food action plans in many global cities articulate interest in multiple objectives including reducing in‐ and trans‐boundary environmental impacts (water, land, greenhouse gas (GHG)). However, there exist few standardized analytical tools to compare food system characteristics and actions across cities and countries to assess trade‐offs between multiple objectives (i.e., health, equity) with environmental outcomes. This paper demonstrates a streamlined model applied for analysis of four cities with varying characteristics across the United States and India, to quantify system‐wide water, energy/GHG, and land impacts associated with multiple food system actions to address health, equity, and environment. Baseline diet analysis finds key differences between countries in terms of meat consumption (Delhi 4; Pondicherry 16; United States 59, kg/capita/year), and environmental impact of processing of the average diet (21%, 19%, <1%, <1% of community‐wide GHG‐emissions for New York, Minneapolis, Delhi, and Pondicherry). Analysis of supply chains finds city average distance (food‐miles) varies (Delhi 420; Pondicherry 200; United States average 1,640 km/t‐food) and the sensitivity of GHG emissions of food demand to spatial variability of energy intensity of irrigation is greater in Indian than US cities. Analysis also finds greater pre‐consumer waste in India versus larger post‐consumer accumulations in the United States. Despite these differences in food system characteristics, food waste management and diet change consistently emerge as key strategies. Among diet scenarios, all vegetarian diets are not found equal in terms of environmental benefit, with the US Government's recommended vegetarian diet resulting in less benefit than other more focused targeted diet changes.     

Total in vitro biosynthesis of the nonribosomal macrolactone peptide valinomycin

Natural products are important because of their significant pharmaceutical properties such as antiviral, antimicrobial, and anticancer activity. Recent breakthroughs in DNA sequencing reveal that a great number of cryptic natural product biosynthetic gene clusters are encoded in microbial genomes, for example, those of Streptomyces species. However, it is still challenging to access compounds from these clusters because many source organisms are uncultivable or the genes are silent during laboratory cultivation. To address this challenge, we develop an efficient cell-free platform for the rapid, in vitro total biosynthesis of the nonribosomal peptide valinomycin as a model. We achieve this goal in two ways. First, we used a cell-free protein synthesis (CFPS) system to express the entire valinomycin biosynthetic gene cluster (>19 kb) in a single-pot reaction, giving rise to approximately 37 μg/L of valinomycin after optimization. Second, we coupled CFPS with cell-free metabolic engineering system by mixing two enzyme-enriched cell lysates to perform a two-stage biosynthesis. This strategy improved valinomycin production ~5000-fold to nearly 30 mg/L. We expect that cell-free biosynthetic systems will provide a new avenue to express, discover, and characterize natural product gene clusters of interest in vitro.     

Experimental models of maternal–fetal interface and their potential use for nanotechnology applications

During pregnancy, the placenta regulates the transfer of oxygen, nutrients, and residual products between the maternal and fetal bloodstreams and is a key determinant of fetal exposure to xenobiotics from the mother. To study the disposition of substances through the placenta, various experimental models are used, especially the perfused placenta, placental villi explants, and cell lineage models. In this context, nanotechnology, an area of study that is on the rise, enables the creation of particles on nanometric scales capable of releasing drugs aimed at specific tissues. An important reason for furthering the studies on transplacental transfer is to explore the potential of nanoparticles (NPs), in new delivery strategies for drugs that are specifically aimed at the mother, the placenta, or the fetus and that involve less toxicity. Due to the fact that the placental barrier is essential for the interaction between the maternal and fetal organisms as well as the possibility of NPs being used in the treatment of various pathologies, the aim of this review is to present the main experimental models used in studying the maternal–fetal interaction and the action of NPs in the placental environment.     

Modeling of dynamical systems through deep learning

This review presents a modern perspective on dynamical systems in the context of current goals and open challenges. In particular, our review focuses on the key challenges of discovering dynamics from data and finding data-driven representations that make nonlinear systems amenable to linear analysis. We explore various challenges in modern dynamical systems, along with emerging techniques in data science and machine learning to tackle them. The two chief challenges are (1) nonlinear dynamics and (2) unknown or partially known dynamics. Machine learning is providing new and powerful techniques for both challenges. Dimensionality reduction methods are used for projecting dynamical methods in reduced form, and these methods perform computational efficiency on real-world data. Data-driven models drive to discover the governing equations and give laws of physics. The identification of dynamical systems through deep learning techniques succeeds in inferring physical systems. Machine learning provides advanced new and powerful algorithms for nonlinear dynamics. Advanced deep learning methods like autoencoders, recurrent neural networks, convolutional neural networks, and reinforcement learning are used in modeling of dynamical systems.     

The role of extracellular matrix in biomechanics and its impact on bioengineering of cells and 3D tissues

The cells and tissues of the human body are constantly exposed to exogenous and endogenous forces that are referred to as biomechanical cues. They guide and impact cellular processes and cell fate decisions on the nano-, micro- and macro-scale, and are therefore critical for normal tissue development and maintaining tissue homeostasis. Alterations in the extracellular matrix composition of a tissue combined with abnormal mechanosensing and mechanotransduction can aberrantly activate signaling pathways that promote disease development. Such processes are therefore highly relevant for disease modelling or when aiming for the development of novel therapies.In this mini review, we describe the main biomechanical cues that impact cellular fates. We highlight their role during development, homeostasis and in disease. We also discuss current techniques and tools that allow us to study the impact of biomechanical cues on cell and tissue development under physiological conditions, and we point out directions, in which in vitro biomechanics can be of use in the future.     

革兰氏阴性细菌外膜主要成分的跨膜转运机制研究进展

革兰氏阴性细菌的外膜由脂多糖、磷脂、外膜蛋白和脂蛋白等成分组成,是细菌抵御外界有害物质的首要物理屏障,与细菌致病性和耐药性密切相关.外膜各组分依赖特定的系统进行跨膜转运,包括脂多糖转运系统(lipopolysaccharide transport, Lpt)、脂质不对称维持系统(maintenance of lipid asymmetry, Mla)、β-桶状装配机器(β-barrel assembly machinery,Bam)以及脂蛋白定位系统(localization of lipoprotein,Lol).这些系统能够保证细菌外膜的完整与稳定,被视为维持细菌生命活动的"命门".因此,本文系统地综述革兰氏阴性细菌外膜主要成分的跨膜转运系统结构与功能,并对其未来研究方向进行展望,为新型靶向抗菌类药物研发提供新的思路.     

Cretaceous origins of the vibrotactile bill-tip organ in birds

Some probe-foraging birds locate their buried prey by detecting mechanical vibrations in the substrate using a specialized tactile bill-tip organ comprising mechanoreceptors embedded in densely clustered pits in the bone at the tip of their beak. This remarkable sensory modality is known as ‘remote touch’, and the associated bill-tip organ is found in probe-foraging taxa belonging to both the palaeognathous (in kiwi) and neognathous (in ibises and shorebirds) clades of modern birds. Intriguingly, a structurally similar bill-tip organ is also present in the beaks of extant, non-probing palaeognathous birds (e.g. emu and ostriches) that do not use remote touch. By comparison with our comprehensive sample representing all orders of extant modern birds (Neornithes), we provide evidence that the lithornithids (the most basal known palaeognathous birds which evolved in the Cretaceous period) had the ability to use remote touch. This finding suggests that the occurrence of the vestigial bony bill-tip organ in all modern non-probing palaeognathous birds represents a plesiomorphic condition. Furthermore, our results show that remote-touch probe foraging evolved very early among the Neornithes and it may even have predated the palaeognathous–neognathous divergence. We postulate that the tactile bony bill-tip organ in Neornithes may have originated from other snout tactile specializations of their non-avian theropod ancestors.