Local adaptation to hosts and parasitoids shape Hamiltonella defensa genotypes across aphid species

Facultative symbionts are common in insects and can provide their hosts with significant adaptations. Yet we still have a limited understanding of what shapes their distributions, such as why particular symbiont strains are common in some host species yet absent in others. To address this question, we genotyped the defensive symbiont Hamiltonella defensa in 26 aphid species that commonly carry this microbe. We found that Hamiltonella strains were strongly associated with specific aphid species and that strains found in one host species rarely occurred in others. To explain these associations, we reciprocally transferred the Hamiltonella strains of three aphid species, Acyrthosiphon pisum, Macrosiphoniella artemisiae and Macrosiphum euphorbiae, and assessed the impact of Hamiltonella strain on: the stability of the symbiosis, aphid fecundity and parasitoid resistance. We demonstrate that the Hamiltonella strains found in nature are locally adapted to specific aphid hosts, and their ecology: aphids tend to carry Hamiltonella strains that are efficiently transmitted to their offspring, non-lethal, and that provide strong protection against their dominant parasitoid species. Our results suggest that facultative symbiont distributions are shaped by selection from natural enemies, and the host itself, resulting in locally adapted symbioses that provide significant benefits against prevailing natural enemies

Thermosensitive nanofibers loaded with ciprofloxacin as antibacterial wound dressing materials

To obtain wound dressings which could be removed easily without secondary injuries, we prepared thermoresponsive electrospun fiber mats containing poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA). Blend fibers of PDEGMA and poly(l-lactic acid-co-ε-caprolactone) (P(LLA-CL) were fabricated via electrospinning, and analogous fibers containing the antibiotic ciprofloxacin (CIF) were also prepared. Smooth cylindrical fibers were obtained, albeit with a small amount of beading visible for the ciprofloxacin-loaded fibers. X-ray diffraction showed the drug to exist in the amorphous physical form post-electrospinning. The composite fibers showed distinct thermosensitive properties and gave sustained release of CIF over more than 160h in vitro. The fibers could promote the proliferation of fibroblasts, and by varying the temperature cells could easily be attached to and detached from the fibers. Antibacterial tests demonstrated that fibers loaded with ciprofloxacin were effective in inhibiting the growth of E. coli and S. aureus. In vivo investigations on rats indicated that the composite PDEGMA/P(LLA-CL) fibers loaded with CIF had much more potent wound healing properties than a commercial gauze and CIF-loaded fibers made solely of P(LLA-CL). These results demonstrate the potential of PDEGMA/P(LLA-CL)/ciprofloxacin fibers as advanced wound dressing materials

In Arabidopsis hybrids and Hybrid Mimics, up-regulation of cell wall biogenesis is associated with the increased plant size

© 2019 The Authors. Plant Direct published by American Society of Plant Biologists, Society for Experimental Biology and John Wiley & Sons Ltd. Hybrid breeding is of economic importance in agriculture for increasing yield, yet the basis of heterosis is not well understood. In Arabidopsis, crosses between different accessions produce hybrids with different levels of heterosis relative to parental phenotypes in biomass. In all hybrids, the advantage of the F1 hybrid in both phenotypic uniformity and yield gain is lost in the heterogeneous F2. F5/F6 Hybrid Mimics generated from a cross between C24 and Landsberg erecta (Ler) ecotypes demonstrated that the large plant phenotype of the F1 hybrids can be stabilized. Hybrid Mimic selection was applied to Wassilewskija (Ws)/Ler and Col/Ler hybrids. The two hybrids show different levels of heterosis. The Col/Ler hybrid generated F7 Hybrid Mimics with rosette diameter and fresh weight equivalent to the F1 hybrid at 30 DAS; F7 Ws/Ler Hybrid Mimics outperformed the F1 hybrid in both the rosette size and biomass. Transcriptome analysis revealed up-regulation of cell wall biosynthesis, and cell wall expansion genes could be a common pathway in increased size in the Arabidopsis hybrids and Hybrid Mimics. Intercross of two independent Hybrid Mimic lines can further increase the biomass gain. Our results encourage the use of Hybrid Mimics for breeding and for investigating the molecular basis of heterosis

Crop straw incorporation interacts with N fertilizer on N₂O emissions in an intensively cropped farmland

Nitrogen (N) fertilization and straw incorporation strongly influence nitrous oxide (N2O) emissions from agricultural fields. An in-situ micro-plot experiment on intensively farmed winter wheat (Triticum aestivum L.) was conducted to investigate the source and rate of N2O emissions from soils following labeled 15N fertilization with and without straw incorporation. Four treatments, i.e., no N fertilizer and no straw incorporation (N0S0), straw incorporation only (N0S1), N fertilizer only (N1S0), and N fertilization plus straw incorporation (N1S1), were established in the experiment. The N2O emissions mainly occurred after N fertilization and lasted for approximately 1–2 weeks, accounting for 60%–67% of the wheat seasonal N2O emissions. Within the 6 days after basal fertilization and 2–4 days after top-dressing, most of the N2O fluxes (>50%) were derived from fertilizer. Thereafter, soil-derived N2O dominated the total N2O emissions and within 10–20 days after N fertilization, fertilizer-derived N2O became negligible. Fertilizer N and soil N both accounted for 40%–60% of the seasonal N2O emissions, which may be explained by the high soil N stock due to long-term high N fertilization in the region. This implies the similar roles of soil N pool and fertilizer N in N2O generation under intensively farmed soils. The N fertilization had a significant priming effect on the turnover of soil N, which contributed 21.02%–50.47% of the total N2O emissions. During the basal fertilization/first irrigation event, straw incorporation significantly (P < 0.05) stimulated CO2 fluxes both in N-fertilized and non-N-fertilized plots; however, after the top-dressing/second irrigation event, the significant increase of CO2 fluxes induced by straw incorporation was only observed in the N-fertilized treatment. Straw incorporation interacted with N fertilization, and tended to enhance N2O emissions in the basal fertilization and lower N2O emissions in the top-dressing period. In N-fertilized plots, the seasonal N2O emissions from straw-incorporated and straw-removed treatments were similar, indicating that straw incorporation enhanced the N supply without increasing the N2O emissions. Our study highlights that there are significant benefits of straw incorporation to soil fertility improvement; however, the long-term impacts of straw incorporation on greenhouse gas emissions should be further examined

Electrospun gelatin nanofibers loaded with vitamins A and E as antibacterial wound dressing materials

Vitamin A palmitate and vitamin E TPGS, common derivatives of the unstable vitamins A and E, were successfully incorporated into biodegradable gelatin nanofibers via electrospinning. Electron microscopy showed that smooth cylindrical fibers were produced, albeit with a small amount of beading visible for the vitamin-loaded systems. The diameters of the fibers decrease with the addition of vitamins. The presence of the vitamins in the fibers was confirmed by IR spectroscopy, and X-ray diffraction showed them to exist in the amorphous physical form post-electrospinning. The addition of vitamins did not affect the hydrophilic properties of the gelatin nanofibers. Fibers containing vitamin A or E alone showed a sustained release profile over more than 60 hours, and those incorporating both vitamins showed similar release characteristics, except that the extent of release for vitamin A was increased. Antibacterial tests demonstrated that materials loaded with vitamin E were effective in inhibiting the growth of E. coli and S. aureus. The fibers could promote the proliferation of fibroblasts during the early stages of culture, and enhance the expression of collagen-specific genes. In vivo tests determined that the fibers loaded with vitamins have better wound healing performance than a commercially used antiseptic gauze and casting films

Brief Report: Incubation Period Duration and Severity of Clinical Disease Following Severe Acute Respiratory Syndrome Coronavirus Infection

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Anti-inflammatory effects of naringin in chronic pulmonary neutrophilic inflammation in cigarette smoke-exposed rats

Naringin, a well-known flavanone glycoside of grapefruit and citrus fruits, was found to be as an effective anti-inflammatory compound in our previous lipopolysaccharide-induced acute lung injury mouse model via blockading activity of nuclear factor κB. The current study sought to explore the anti-inflammatory effects of naringin on chronic pulmonary neutrophilic inflammation in cigarette smoke (CS)-induced rats. Seventy Sprague-Dawley rats were randomly divided into seven groups to study the effects of CS with or without various concentrations of naringin or saline for 8 weeks. The results revealed that naringin supplementation at 20, 40, and 80mg/kg significantly increased body weight of CS-induced rats as compared to that in the CS group. Moreover, naringin of 20, 40, and 80mg/kg prevented CS-induced infiltration of neutrophils and activation of myeloperoxidase and matrix metalloproteinase-9, in parallel with suppression of the release of cytokines, such as tumor necrosis factor-α and interleukin-8 (IL-8). IL-10 in bronchoalveolar lavage fluid was significantly suppressed after CS exposure, but dose dependently elevated by naringin. The results from hematoxylin and eosin staining revealed that naringin dose dependently reduced CS-induced infiltration of inflammatory cells, thickening of the bronchial wall, and expansion of average alveolar airspace. In conclusion, our data suggest that naringin is an effective anti-inflammatory compound for attenuating chronic pulmonary neutrophilic inflammation in CS-induced rats. © Copyright 2012, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition 2012.published_or_final_versio

Intra-ejaculate sperm selection in female zebra finches

Among internal fertilizers, typically fewer than 1% sperm survive the journey through the oviduct. Several studies suggest that the sperm reaching the ovum-the 'fertilizing set'-comprise a non-random sub-population, but the characteristics of this group remain unclear. We tested whether oviductal selection in birds results in a morphologically distinct subset of sperm, by exploiting the fact that the fertilizing set are trapped by the perivitelline layer of the ovum. We show that these sperm have remarkably low morphological variation, as well as smaller head size and greater tail length, compared with those inseminated. Our study shows that the morphological composition of sperm-rather than length alone-influences success in reaching the ovum

On the complexity of color-avoiding site and bond percolation

The mathematical analysis of robustness and error-tolerance of complex networks has been in the center of research interest. On the other hand, little work has been done when the attack-tolerance of the vertices or edges are not independent but certain classes of vertices or edges share a mutual vulnerability. In this study, we consider a graph and we assign colors to the vertices or edges, where the color-classes correspond to the shared vulnerabilities. An important problem is to find robustly connected vertex sets: nodes that remain connected to each other by paths providing any type of error (i.e. erasing any vertices or edges of the given color). This is also known as color-avoiding percolation. In this paper, we study various possible modeling approaches of shared vulnerabilities, we analyze the computational complexity of finding the robustly (color-avoiding) connected components. We find that the presented approaches differ significantly regarding their complexity.Comment: 14 page