Long-chain polyunsaturated fatty acids (LC-PUFAs), particularly the omega-3 LC-PUFAs eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA), have been associated ...with beneficial health effects. Consequently, sustainable sources have to be developed to meet the increasing demand for these PUFAs. Here, we demonstrate the design and construction of artificial PUFA biosynthetic gene clusters (BGCs) encoding polyketide synthase-like PUFA synthases from myxobacteria adapted for the oleaginous yeast Yarrowia lipolytica. Genomic integration and heterologous expression of unmodified or hybrid PUFA BGCs yielded different yeast strains with specific LC-PUFA production profiles at promising yield and thus valuable for the biotechnological production of distinct PUFAs. Nutrient screening revealed a strong enhancement of PUFA production, when cells were phosphate limited. This represents, to the best of our knowledge, highest concentration of DHA (16.8 %) in total fatty acids among all published PUFA-producing Y. lipolytica strains.
The discovery of Streptomyces-produced streptomycin founded the age of tuberculosis therapy. Despite the subsequent development of a curative regimen for this disease, tuberculosis remains a ...worldwide problem, and the emergence of multidrug-resistant Mycobacterium tuberculosis has prioritized the need for new drugs. Here we show that new optimized derivatives from Streptomyces-derived griselimycin are highly active against M. tuberculosis, both in vitro and in vivo, by inhibiting the DNA polymerase sliding clamp DnaN. We discovered that resistance to griselimycins, occurring at very low frequency, is associated with amplification of a chromosomal segment containing dnaN, as well as the ori site. Our results demonstrate that griselimycins have high translational potential for tuberculosis treatment, validate DnaN as an antimicrobial target, and capture the process of antibiotic pressure-induced gene amplification.
Background
This was a prospective study of radiofrequency segmental thermal ablation (RFA) for the treatment of incompetent varicose great saphenous veins (GSVs). The present report describes ...long‐term follow‐up at 5 years.
Methods
The 5‐year follow‐up of this multicentre European study included assessment of the Venous Clinical Severity Score (VCSS), and GSV occlusion and reflux on duplex imaging.
Results
A total of 225 patients had 295 GSVs treated by RFA, achieving an initial vein occlusion rate of 100 per cent. With 80·0 per cent compliance, Kaplan–Meier analyses showed a GSV occlusion rate of 91·9 per cent and a reflux‐free rate of 94·9 per cent at 5 years. Among the 15 GSVs noted with reflux during follow‐up, only three showed full recanalization of the GSV at 1 week, 6 months and 3 years. Of the 12 legs with partial recanalization, reflux originated at the saphenofemoral junction in ten, with a mean length of the patent segment of 5·8 (range 3·2–10) cm; only six patients were symptomatic. Mean(s.d.) VCSS scores improved from 3·9(2·1) at baseline to 0·6(1·2), 0·9(1·3) and 1·3(1·7) at 1, 3 and 5 years.
Conclusion
At 5 years RFA proved to be an efficient endovenous treatment for incompetent GSVs in terms of sustained clinical and anatomical success for the vast majority of treated patients.
Effective and durable
In this article, we briefly review the potential of myxobacteria as 'natural product factories' by highlighting results from the recently sequenced myxobacterial model strain Myxococcus xanthus. We ...will focus on the production of polyketides, non-ribosomally-made peptides, and their hybrids, and discuss the evaluation of biosynthetic potential using genome-based methods, as well as biosynthetic process engineering.
•Intraspecific exceeds between species trait variability for most traits.•Between population exceeds within population trait variability.•The traits of different species vary mainly consistently ...between sites.•Climate factors can help explaining between population trait variability.•The proportion of intraspecific trait variability diminishes in the n-dimensional trait space.
The intraspecific plant trait variability (ITV) is key for many ecological processes, but large-scale analysis of co-occurring species are rare. Here we studied ITV of 14 plant traits for five co-occurring species across 56 European dry grassland sites – large parts of the species distribution ranges. We evaluated variation in ITV relative to between species trait variability (BTV) with a particular emphasis on how within versus between population variability contributes to ITV. We performed this analysis trait by trait (univariate) and by considering hypervolumes in the multi-variate trait space. We also tested whether climatic variables can be used to predict between population variation in traits.
For the trait by trait analysis, for 9 out of 14 traits ITV exceeded BTV, which suggests an extraordinary large role of ITV. However, when considering all traits jointly the hypervolume occupied by ITV was only 23% of overall trait variability.
We found comparatively small effects of within population variability in the uni- as well as in the multivariate analysis decreasing rapidly with increasing number of considered traits. The dominance of between population variability suggests that ITV is mainly driven by environmental effects rather than local biotic interactions and microsite effects. ITV of leaf chemical traits was related to precipitation and growing degree days until sampling
ITV can be substantial compared to BTV, in particular when considering single traits, such that ITV should be considered in trait-based research. Since the importance of ITV appears to decrease when considering multiple traits jointly, using species mean trait values is more appropriate for multi-variate trait analysis. Because ITV varied mainly between populations rather than within populations, and was related to climatic conditions, we suggest that ITV could be accounted for in future trait based research by including environmental covariates in hierarchical models of trait variation
Microorganisms produce an immense variety of natural products with useful biological activities. These compounds are often biosynthesized by multifunctional megasynthetases known as polyketide ...synthases and nonribosomal peptide synthetases. Recent literature on these natural product assembly lines suggests that they have a much greater mechanistic diversity than originally anticipated.
Synthetic biology techniques coupled with heterologous secondary metabolite production offer opportunities for the discovery and optimisation of natural products. Here we developed a new assembly ...strategy based on type IIS endonucleases and elaborate synthetic DNA platforms, which could be used to seamlessly assemble and engineer biosynthetic gene clusters (BGCs). By applying this versatile tool, we designed and assembled more than thirty different artificial myxochromide BGCs, each around 30 kb in size, and established heterologous expression platforms using a derivative of
DK1622 as a host. In addition to the five native types of myxochromides (A, B, C, D and S), novel lipopeptide structures were produced by combinatorial exchange of nonribosomal peptide synthetase (NRPS) encoding genes from different myxochromide BGCs. Inspired by the evolutionary diversification of the native myxochromide megasynthetases, the ancestral A-type NRPS was engineered by inactivation, deletion, or duplication of catalytic domains and successfully converted into functional B-, C- and D-type megasynthetases. The constructional design approach applied in this study enables combinatorial engineering of complex synthetic BGCs and has great potential for the exploitation of other natural product biosynthetic pathways.
Due to raising functional integration in micro fluidic, micro mechanic, micro electronic and micro optical systems the trend to scaling down the work piece sizes while increasing its complexity ...requires high precise machine accuracy. With respect to the process and geometrical parameters, most of the finishing manufacturing processes can be covered by milling and grinding operations with three or five machine axes. But whereas the available machine tools hardly achieve the required process dynamic and accuracy in all degrees of freedom, the requirements still increase. For this reason the Fraunhofer IPT has developed high precise machine tools following a compact design strategy by reducing the overall machine dimensions as far as conventional machine components such as measuring or drive systems were available. The developments of two compact machine tools exemplify the dynamic and accuracy enhancement by compact design and are described in the following.
The bengamides, sponge‐derived natural products that have been characterized as inhibitors of methionine aminopeptidases (MetAPs), have been intensively investigated as anticancer compounds. We ...embarked on a multidisciplinary project to supply bengamides by fermentation of the terrestrial myxobacterium M. virescens, decipher their biosynthesis, and optimize their properties as drug leads. The characterization of the biosynthetic pathway revealed that bacterial resistance to bengamides is conferred by Leu 154 of the myxobacterial MetAP protein, and enabled transfer of the entire gene cluster into the more suitable production host M. xanthus DK1622. A combination of semisynthesis of microbially derived bengamides and total synthesis resulted in an optimized derivative that combined high cellular potency in the nanomolar range with high metabolic stability, which translated to an improved half‐life in mice and antitumor efficacy in a melanoma mouse model.
A terrestrial dive to bengamides: Bengamides, sponge‐derived natural products, have been generated from a terrestrial source. Their biosynthesis and self‐resistance mechanism against methionine aminopeptidases was elucidated, a heterologous expression platform was established, and their pharmaceutical properties were improved by medicinal chemistry.
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