Wind power is a quickly growing renewable energy resource within the continental United States and is expected to continue increasing as more wind farms are installed onshore and offshore. As a part ...of this growth, larger turbines benefit from economies of scale from taller towers. However, the development of ultra-tall wind turbine towers is hindered by transportation restrictions which limit the diameter and weight of the prefabricated tower sections. One proposed solution to this problem is to employ concrete additive manufacturing to build ultra-tall wind turbine towers on-site. To evaluate the potential environmental impacts of this approach, this study performed a life cycle assessment comparing four prototype 7.5-MW wind turbine towers designed with a height of 140 m: a conventional tubular steel tower assembled using bolted connections, two 3D printed concrete towers additively manufactured on-site with normal-strength (35 MPa) or high-strength (78 MPa) concrete, and a 3D cast concrete tower with normal strength (35 MPa) concrete cast into concrete formworks additively manufactured with high-strength (78 MPa) concrete. The 3D cast concrete tower segments are manufactured off-site and assembled on-site. The life cycle assessment examined the impacts of differences in materials inventory, structural designs, manufacturing methods, maintenance schedules, and end-of-life options for the four towers. The results indicate that the material production stage dominates, contributing over 92% of the total CO2 emissions and 67–93% of the energy consumption of the four towers. Compared with the steel tower, the normal-strength 3D printed concrete tower has 23% lower total life cycle CO2 emissions but 29% higher energy consumption; the high-strength 3D printed concrete tower has 16% higher life cycle CO2 emissions and 64% higher energy consumption. Parametric studies were also conducted to examine the effects of cement content by weight, distance from the concrete plant to the tower construction site, the number of tower sections, rated tower life, and tower end-of-life recycling rate. The results indicate that reducing cement content in 3D printed concrete such as by incorporating waste or recycled materials can significantly reduce the life cycle environmental impacts of ultra-tall turbine towers.
•3D printed low-cement concrete tower has 23% lower GWP than steel tower.•3D printed high-cement concrete tower has 16% higher GWP than steel tower.•Material stage contributes to 93–99% of lifecycle GWP of concrete and steel towers.•Tower manufacturing generates 0.3–0.8% (concrete) and 0.2% (steel) of lifecycle GWP.•Increasing service life and recycling percentage reduces environmental impacts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The nitrogen-fixing rhizobial symbiont Sinorhizobium meliloti 1021 produces acidic symbiotic exopolysaccharides that enable it to initiate and maintain infection thread formation on host legume ...plants. The exopolysaccharide that is most efficient in mediating this process is succinoglycan (exopolysaccharide I EPSI), a polysaccharide composed of octasaccharide repeating units of 1 galactose and 7 glucose residues, modified with succinyl, acetyl, and pyruvyl substituents. Previous studies had shown that S. meliloti 1021 mutants that produce increased levels of succinoglycan, such as exoR mutants, are defective in symbiosis with host plants, leading to the hypothesis that high levels of succinoglycan production might be detrimental to symbiotic development. This study demonstrates that increased succinoglycan production itself is not detrimental to symbiotic development and, in fact, enhances the symbiotic productivity of S. meliloti 1021 with the host plant Medicago truncatula cv. Jemalong A17. Increased succinoglycan production was engineered by overexpression of the exoY gene, which encodes the enzyme responsible for the first step in succinoglycan biosynthesis. These results suggest that the level of symbiotic exopolysaccharide produced by a rhizobial species is one of the factors involved in optimizing the interaction with plant hosts.
Summary
The formation of nitrogen‐fixing nodules on legume hosts is a finely tuned process involving many components of both symbiotic partners. Production of the exopolysaccharide succinoglycan by ...the nitrogen‐fixing bacterium Sinorhizobium meliloti 1021 is needed for an effective symbiosis with Medicago spp., and the succinyl modification to this polysaccharide is critical. However, it is not known when succinoglycan intervenes in the symbiotic process, and it is not known whether the plant lysin‐motif receptor‐like kinase MtLYK10 intervenes in recognition of succinoglycan, as might be inferred from work on the Lotus japonicus MtLYK10 ortholog, LjEPR3. We studied the symbiotic infection phenotypes of S. meliloti mutants deficient in succinoglycan production or producing modified succinoglycan, in wild‐type Medicago truncatula plants and in Mtlyk10 mutant plants. On wild‐type plants, S. meliloti strains producing no succinoglycan or only unsuccinylated succinoglycan still induced nodule primordia and epidermal infections, but further progression of the symbiotic process was blocked. These S. meliloti mutants induced a more severe infection phenotype on Mtlyk10 mutant plants. Nodulation by succinoglycan‐defective strains was achieved by in trans rescue with a Nod factor‐deficient S. meliloti mutant. While the Nod factor‐deficient strain was always more abundant inside nodules, the succinoglycan‐deficient strain was more efficient than the strain producing only unsuccinylated succinoglycan. Together, these data show that succinylated succinoglycan is essential for infection thread formation in M. truncatula, and that MtLYK10 plays an important, but different role in this symbiotic process. These data also suggest that succinoglycan is more important than Nod factors for bacterial survival inside nodules.
Significance Statement
This work should be of interest across the field of plant–microbe endosymbioses by providing insights into key determinants of both bacteria and plants for successful microbial host invasion. It is timely with much current interest in symbiotic roles of plant LysM‐RLK proteins and the evolutionary origins of nitrogen‐fixing endosymbiosis. MtLYK10 is a Medicago truncatula component that specifically intervenes in rhizobial infection, independently of succinoglycan recognition.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The deltaretroviruses human T cell lymphotropic virus type 1 (HTLV-1) and human T cell lymphotropic virus type 2 (HTLV-2) have long been believed to differ from retroviruses in other genera by their ...mode of transmission. While other retroviruses were thought to primarily spread by producing cell-free particles that diffuse through extracellular fluids prior to binding to and infecting target cells, HTLV-1 and HTLV-2 were believed to transmit the virus solely by cell-cell interactions. This difference in transmission was believed to reflect the fact that, relative to other retroviruses, the cell-free virions produced by HTLV-infected cells are very poorly infectious. Since HTLV-1 and HTLV-2 are primarily found in T cells in the peripheral blood, spread of these viruses was believed to occur between infected and uninfected, T cells, although little was known about the cellular and viral proteins involved in this interaction. Recent studies have revealed that the method of transmission of HTLV is not unique: other retroviruses including human immunodeficiency virus (HIV) are also transmitted from cell-to-cell, and this method is dramatically more efficient than cell-free transmission. Moreover, cell-cell transmission of HTLV-1, as well as HIV, can occur following interactions between dendritic cells and T cells, as well as between T cells. Conversely, other studies have shown that cell-free HTLV-1 is not as poorly infectious as previously thought, since it is capable of infecting certain cell types. Here we summarize the recent insights about the mechanisms of cell-cell transmission of HTLV-1 and other retroviruses. We also review in vitro and in vivo studies of infection and discuss how these finding may relate to the spread of HTLV-1 between individuals.
Axenically cultured Liberibacter crescens (Lcr) is a closely related surrogate for uncultured plant pathogenic species of the genus Liberibacter, including 'Candidatus L. asiaticus' (CLas) and 'Ca. ...L. solanacearum' (CLso). All Liberibacters encode a completely conserved gene repertoire for both flagella and Tad (Tight Adherence) pili and all are missing genes critical for nucleotide biosynthesis. Both flagellar swimming and Tad pilus-mediated twitching motility in Lcr were demonstrated for the first time. A role for Tad pili in the uptake of extracellular dsDNA for food in Liberibacters was suspected because both twitching and DNA uptake are impossible without repetitive pilus extension and retraction, and no genes encoding other pilus assemblages or mechanisms for DNA uptake were predicted to be even partially present in any of the 35 fully sequenced Liberibacter genomes. Insertional mutations of the Lcr Tad pilus genes cpaA, cpaB, cpaE, cpaF and tadC all displayed such severely reduced growth and viability that none could be complemented. A mutation affecting cpaF (motor ATPase) was further characterized and the strain displayed concomitant loss of twitching, viability and reduced periplasmic uptake of extracellular dsDNA. Mutations of comEC, encoding the inner membrane competence channel, had no effect on either motility or growth but completely abolished natural transformation in Lcr. The comEC mutation was restored by complementation using comEC from Lcr but not from CLas strain psy62 or CLso strain RS100, indicating that unlike Lcr, these pathogens were not naturally competent for transformation. This report provides the first evidence that the Liberibacter Tad pili are dynamic and essential for both motility and DNA uptake, thus extending their role beyond surface adherence.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nitrogen-fixing rhizobial bacteria and leguminous plants have evolved complex signal exchange mechanisms that allow a specific bacterial species to induce its host plant to form invasion structures ...through which the bacteria can enter the plant root. Once the bacteria have been endocytosed within a host-membrane-bound compartment by root cells, the bacteria differentiate into a new form that can convert atmospheric nitrogen into ammonia. Bacterial differentiation and nitrogen fixation are dependent on the microaerobic environment and other support factors provided by the plant. In return, the plant receives nitrogen from the bacteria, which allows it to grow in the absence of an external nitrogen source. Here, we review recent discoveries about the mutual recognition process that allows the model rhizobial symbiont Sinorhizobium meliloti to invade and differentiate inside its host plant alfalfa (Medicago sativa) and the model host plant barrel medic (Medicago truncatula).
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Chagas disease, caused by the parasite Trypanosoma cruzi, develops into chronic Chagas' cardiomyopathy in ~30% of infected individuals, characterized by conduction disorders, arrhythmias, heart ...failure, and even sudden cardiac death. Current anti-parasitic treatments are plagued by significant side effects and poor efficacy in the chronic phase of disease; thus, there is a pressing need for new treatment options. A therapeutic vaccine could bolster the protective TH1-mediated immune response, thereby slowing or halting the progression of chronic Chagas' cardiomyopathy. Prior work in mice has demonstrated therapeutic efficacy of a Tc24 recombinant protein vaccine in the acute phase of Chagas disease. However, it is anticipated that humans will be vaccinated therapeutically when in the chronic phase of disease. This study investigates the therapeutic efficacy of a vaccine prototype containing recombinant protein Tc24, formulated with an emulsion containing the Toll-like receptor 4 agonist E6020 as an immunomodulatory adjuvant in a mouse model of chronic T. cruzi infection. Among outbred ICR mice vaccinated during chronic T. cruzi infection, there is a significant increase in the number of animals with undetectable systemic parasitemia (60% of vaccinated mice compared to 0% in the sham vaccine control group), and a two-fold reduction in cardiac fibrosis over the control group. The vaccinated mice produce a robust protective TH1-biased immune response to the vaccine, as demonstrated by a significant increase in antigen-specific IFNγ-production, the number of antigen-specific IFNγ-producing cells, and IgG2a antibody titers. Importantly, therapeutic vaccination significantly reduced cardiac fibrosis in chronically infected mice. This is a first study demonstrating therapeutic efficacy of the prototype Tc24 recombinant protein and E6020 stable emulsion vaccine against cardiac fibrosis in a mouse model of chronic T. cruzi infection.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by the progressive loss of striatal medium spiny neurons. Using a highly efficient protocol for direct ...reprogramming of adult human fibroblasts with chemically modified mRNA, we report the first generation of HD induced neural precursor cells (iNPs) expressing striatal lineage markers that differentiated into DARPP32+ neurons from individuals with adult‐onset HD (41‐57 CAG). While no transcriptional differences between normal and HD reprogrammed neurons were detected by NanoString nCounter analysis, a subpopulation of HD reprogrammed neurons contained ubiquitinated polyglutamine aggregates. Importantly, reprogrammed HD neurons exhibited impaired neuronal maturation, displaying altered neurite morphology and more depolarized resting membrane potentials. Reduced BDNF protein expression in reprogrammed HD neurons correlated with increased CAG repeat lengths and earlier symptom onset. This model represents a platform for investigating impaired neuronal maturation and screening for neuronal maturation modifiers to treat HD.
Directly reprogrammed Huntington's disease induced neural precursor cells generate DARPP32+ striatal neurons exhibiting ubiquitinated huntingtin aggregates, altered neuronal morphologies, reduced hyperpolarization, and reduced BDNF expression that correlates with age of symptom onset and increased CAG expansion.
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