Long-Term Existence of SARS-CoV-2 in COVID-19 Patients: Host Immunity,Viral Virulence,and Transmissibility

Virologica Sinica - COVID-19 patients can recover with a median SARS-CoV-2 clearance of 20 days post initial symptoms (PIS). However, we observed some COVID-19 patients with existing...     

Environmental analysis of packaging‐derived changes in food production and consumer behavior

This study analyzed the environmental impacts of packaging‐derived changes in food production and consumer behavior to assist packaging designers in making environmentally conscious decisions. Packaging can be functionalized to prevent food loss and waste (FLW), for example, extending the expiration date and apportioning the package size, but it can generate additional environmental impacts from changes in food and packaging production. Previous studies assessed additional impacts from packaging production; however, the effects of packaging functionalization are yet to be connected with food production and consumer behavior. To examine the effect of functionalization on these aspects, we analyzed packaging‐derived changes in food production for milk and cabbage products. The case study compared products with functionalized packaging that permits a longer expiration date or a smaller portion size to their base‐case products. Our results showed that the packaging‐derived changes increased the global warming potential (GWP) of food production more than other processes did. Thus, changes in food production weakened the effectiveness of the packaging functionalization to decrease the GWP. Moreover, the analysis of consumer behavior scenarios showed that consumers’ perception of the expiration date decisively influences the effectiveness of packaging functionalization. When consumers discarded food after the expiration date, provided they consumed in small quantities, the packaging functionalization reduced FLW. From the scenario analysis, we identified appropriate combinations of packaging functionalization and consumer behaviors to effectively decrease total GWP. With our expanded analysis, packaging designers can understand the effectiveness of their decisions on the product life cycle in reducing FLW and environmental impacts.     

Investigation of structural stability and functionality of homodimeric gramicidin towards peptide-based drug: a molecular simulation approach

Increasing death rates due to antibiotic resistance deteriorate the existing treatment measures. Antimicrobial peptides have turned into the emerging cure for multidrug resistance. However, the stability and functionality determine an antimicrobial peptide as a drug. Analyses of the homodimeric β-helical peptide, gramicidin have suggested the significant role of gramicidin-A, gramicidin-B, and gramicidin-C as antimicrobial compounds, but the structural basis for understanding the stability and functionality is insufficient to resolve multidrug resistance. To identify the best template among gramicidin types as a therapeutic product, we combined a detailed comparative static analysis and dynamic analysis along with conformational free energy and secondary structure prediction. We observed that the high intramolecular interactions and the geometrical features favored gramicidin-A among other types of gramicidin. Our analyses further revealed that the secondary structure of gramicidin-A showed β sheets with coils along the conformations without any disruption, thereby enhanced its membrane interactions in terms of binding free energy. In conclusion, gramicidin-A has definitely showed enhanced structural stability and functionality; this could be considered the best template for a potential therapeutic product.     

Reductive C-N bond cleavage of the NCCCN β-diketiminate backbone: A direct approach to azabutadienyl and alkylidene-anilide scaffolds

Tetrahydrofuran/toluene solutions of (nacnac)TiCl₂ (nacnac⁻ = [ArNC(^tBu)]₂CH, Ar = 2,6-ⁱPr₂C₆H₃) react readily with KC₈ to afford the titanium imide (ArN(^tBu)CCHC(^tBu))TiNAr(THF)Cl (1) in 67% isolated yield. Complex 1 forms from the two-electron reductive C-N bond cleavage of the β-diketiminate ligand. Likewise, reduction of (nacnac)TiCl(NHAr) (2), prepared in 85% yield from (nacnac)TiCl₂ and LiNHAr, with KC₈ results in formation of the imide-anilide analogue (ArN(^tBu)CCHC(^tBu))TiNAr(NHAr) (3) in 88% yield. Another reductant such as Li^tBu (3 equiv.) reacts cleanly with the precursor (nacnac)TiCl₂ to afford the alkylidene-ate complex [Li(Et₂O)][(ArN(^tBu)CCHC(^tBu))TiNAr(Et₂O)] (4), in 81% yield. Complexes 1-4 have been characterized by ¹H and ¹³C NMR spectra as well as single-crystal X-ray diffraction analysis. Plausible mechanisms to formation of compounds 1, 3 and 4 are also presented and discussed.     

Comparison of Post‐mining Rehabilitation with Reference Ecosystems in Monsoonal Eucalypt Woodlands,Northern Australia

Rehabilitation of post‐mining lands frequently aims to create “self‐sustaining” systems. Where native vegetation is the designated post‐mining land use, it is generally assumed that rehabilitation that is similar to local native ecosystems is more likely to be sustainable. I compared landscape functionality, plant community composition, and vegetation structure in (1) reference sites representing pre‐mining native forest; (2) reference sites representing potential landscape analogues for the post‐mining landscape; and (3) a 23‐year chronosequence of post‐mining rehabilitation on the Weipa bauxite plateau, Cape York Peninsula, Australia. The trends across the post‐mining chronosequence indicate that vegetation growth is rapid in the first 5–8 years, and then slows with mean height approaching an asymptote after approximately 15 years. Landscape function indices showed a response that coincided with vegetation growth. Vegetation composition was significantly different from reference native forest. Most importantly, from the perspective of creating self‐sustaining ecosystems, the contribution of local framework species to vegetation in rehabilitation was significantly lower than in reference native forest. I discuss the results in relation to theoretical models of succession and conclude that without management intervention, differences between post‐mining rehabilitation and native forest are likely to be persistent.     

A Genetic Assessment of Ecological Restoration Success in Banksia attenuata

Rarely assessed in the success of ecological restoration projects is the maintenance of genetic variation in restored populations and, critically, their offspring. A founding population sourced from a limited genetic pool of nonlocal provenance seed can result in genetic bottlenecking and inbreeding, potentially reducing future population resilience and restoration success. We used microsatellite markers to assess the genetic variation of natural and restored populations, and their offspring, in Banksia attenuata R.Br. (Proteaceae), a keystone species of Banksia woodlands in south‐west Australia. Both natural and restored populations, and their offspring, displayed similarly high levels of heterozygosity (H_e range = 0.57–0.62) and allelic diversity (N_e range = 6.67–8.86) across 7 microsatellite loci. There was very weak population divergence (F_ST = 0.006) between the restored population and the adjacent natural population, indicating local provenance sourcing of seed. Genetic structuring within the natural population was weak, but detectable at 10 m and more strongly genetically structured than the restored population (Sp = 0.006 and 0.002, respectively). Complete outcrossing, low‐correlated paternity, and very low bi‐parental inbreeding were observed in both populations. Extensive pollen dispersal was observed within and among populations, with >50% of paternity assigned to sires beyond the local population. In a greenhouse experiment, differences in the overall performance of seedlings from natural and restored populations were negligible. Results indicate the successful genetic management of B. attenuata in this restoration project, from which general principles emphasizing the use of diverse local provenance seeds, genetic integration, and delivery of pollinator services are supported.     

A biomechanical approach to the analysis of methods and procedures of bariatric surgery

Bariatric surgery includes a variety of procedures that are performed on obese people and aim at decreasing the intake of food and calories. This goal is usually pursued by reducing stomach capacity and/or absorbing capability. Adjustable gastric banding is the most common and successful operation. In general, bariatric surgical procedures are effective, but are often associated with major complications.Surgical procedure and post-surgical conformation of the stomach are usually defined on clinical and surgical basis only. Instead, the optimal configuration should be identified by analyzing the mechanical functionality of the stomach and the surrounding structures, and the relationship between food intake, nutrient adsorption, mechanical stimulation of stomach wall and feeling of satiety.A novel approach to bariatric surgery is required, integrating competences in the areas of biomechanics, physiology and surgery, based on a strong interaction between engineers and clinicians. Preliminary results from coupled experimental and computational investigations are here reported. The analyses aim to develop computational tools for the investigation of stomach mechanical functionality in pre- and post-surgical conformations.     

Heterozygosity is linked to the costs of immunity in nestling great tits (Parus major)

There is growing evidence that heterozygosity–fitness correlations (HFCs) are more pronounced under harsh conditions. Empirical evidence suggests a mediating effect of parasite infestation on the occurrence of HFCs. Parasites have the potential to mediate HFCs not only by generally causing high stress levels but also by inducing resource allocation tradeoffs between the necessary investments in immunity and other costly functions. To investigate the relative importance of these two mechanisms, we manipulated growth conditions of great tit nestlings by brood size manipulation, which modifies nestling competition, and simultaneously infested broods with ectoparasites. We investigated under which treatment conditions HFCs arise and, second, whether heterozygosity is linked to tradeoff decisions between immunity and growth. We classified microsatellites as neutral or presumed functional and analyzed these effects separately. Neutral heterozygosity was positively related to the immune response to a novel antigen in parasite‐free nests, but not in infested nests. For nestlings with lower heterozygosity levels, the investments in immunity under parasite pressure came at the expenses of reduced feather growth, survival, and female body condition. Functional heterozygosity was negatively related to nestling immune response regardless of the growth conditions. These contrasting effects of functional and neutral markers might indicate different underlying mechanisms causing the HFCs. Our results confirm the importance of considering marker functionality in HFC studies and indicate that parasites mediate HFCs by influencing the costs of immune defense rather than by a general increase in environmental harshness levels.     

Complete genome sequencing of exopolysaccharide-producing Lactobacillus plantarum K25 provides genetic evidence for the probiotic functionality and cold endurance capacity of the strain

Lactobacillus plantarum (L. plantarum) K25 is a probiotic strain isolated from Tibetan kefir. Previous studies showed that this exopolysaccharide (EPS)-producing strain was antimicrobial active and cold tolerant. These functional traits were evidenced by complete genome sequencing of strain K25 with a circular 3,175,846-bp chromosome and six circular plasmids, encoding 3365 CDSs, 16 rRNA genes and 70 tRNA genes. Genomic analysis of L. plantarum K25 illustrates that this strain contains the previous reported mechanisms of probiotic functionality and cold tolerance, involving plantaricins, lysozyme, bile salt hydrolase, chaperone proteins, osmoprotectant, oxidoreductase, EPSs and terpenes. Interestingly, strain K25 harbors more genes that function in defense mechanisms, and lipid transport and metabolism, in comparison with other L. plantarum strains reported. The present study demonstrates the comprehensive analysis of genes related to probiotic functionalities of an EPS-producing L. plantarum strain based on whole genome sequencing.