Comparing the plant virus spread patterns of non-persistently transmitted virus and persistently transmitted virus using an individual-based model

To compare the spread patterns between two types of plant viruses, non-persistent virus (NPV) and persistent virus (PV), we developed a spatially-explicit individual-based model. Our probability-based model is driven by the actions of insect vectors that are affected by interactions with host plants and plant viruses, considering both biological and behavioral components of their relationship. As a model system, we used potato virus y and potato leafroll virus, respectively for NPV and PV, potato for host plant, and Myzus persicae for the insect vector; empirical results from previous studies were acquired and adjusted to be used as our parameter values. Our simulation results showed that initial infection of PV in the field resulted in over 1.3 times greater number of insect vectors while causing approximately 7 times greater number of virus-infected plants compared to NPV by the end of simulation. Furthermore, spatial analysis showed that PV-infected plants showed greater aggregation in the field, forming larger patches compared to NPV-infected plants. Our results demonstrated the importance of host plant and insect vector manipulation by plant viruses as well as biological properties such as infectious period in the insect on the difference in overall spread pattern.     

Development and characterization of a continuous cell line (EL) from the liver of European eel Anguilla anguilla

In the present study, a new hepatic tissue‐origin cell line from European eel Anguilla anguilla has been developed and characterized. This cell line designated EL has been maintained in Leibovitz L‐15 supplemented with 10% fetal bovine serum over 72 months, and subcultured more than 90 times. The EL cell line consisted predominantly of fibroblast‐like cells, which could survive over 100 days in vitro, and could grow at 15–32°C. The optimum temperature for growth was 27°C. The chromosome analysis revealed a modal diploid karyotype of 2n = 38. The origin of this cell line was confirmed by the 18S recombinant (r)RNA sequencing. The susceptibility test indicated significant cytopathic effects in the EL cells with regard to the Rana grylio virus and the Herpesvirus anguillae. The viral replication was confirmed by transmission electron microscopy and polymerase chain reaction analysis. Following poly (I:C) exposure, the expression levels of the immune‐related molecules interferon regulatory factor‐7 (irf7) and transforming growth factor‐β (TGF‐β) were downregulated in EL cells, whereas the expression levels of the rf3 and the cytochrome P450 (CYP450) were upregulated. All four genes were significantly upregulated following inflammation by lipopolysaccharide (LPS). These data suggested the application of EL cell line for viral identification, as well as for immunodiagnosis and pharmacological targeting.     

Structure comparison of the chimeric AAV2.7m8 vector with parental AAV2

The AAV2.7m8 vector is an engineered capsid with a 10-amino acid insertion in adeno-associated virus (AAV) surface variable region VIII (VR-VIII) resulting in the alteration of an antigenic region of AAV2 and the ability to efficiently transduce retina cells following intravitreal administration. Directed evolution and in vivo screening in the mouse retina isolated this vector. In the present study, we sought to identify the structural differences between a recombinant AAV2.7m8 (rAAV2.7m8) vector packaging a GFP genome and its parental serotype, AAV2, by cryo-electron microscopy (cryo-EM) and image reconstruction. The structures of rAAV2.7m8 and AAV2 were determined to 2.91 and 3.02 Å resolution, respectively. The rAAV2.7m8 amino acid side-chains for residues 219–745 (the last C-terminal residue) were interpretable in the density map with the exception of the 10 inserted amino acids. While observable in a low sigma threshold density, side-chains were only resolved at the base of the insertion, likely due to flexibility at the top of the loop. A comparison to parental AAV2 (ordered from residues 217–735) showed the structures to be similar, except at some side-chains that had different orientations and, in VR-VIII containing the 10 amino acid insertion. VR-VIII is part of an AAV2 antigenic epitope, and the difference is consistent with rAAV2.7m8′s escape from a known AAV2 monoclonal antibody, C37-B. The observations provide valuable insight into the configuration of inserted surface peptides on the AAV capsid and structural differences to be leveraged for future AAV vector rational design, especially for retargeted tropism and antibody escape.     

Factors Affecting the Mixotrophic Flagellate Poterioochromonas malhamensis Grazing on Chlorella Cells

Grazing behaviour between protozoa and phytoplankton exists widely in planktonic ecosystems. Poterioochromonas malhamensis is a well‐known and widespread mixotrophic flagellate, which is recognized to play an important role within marine and freshwater planktonic ecosystems and regarded as the greatest contamination threat for mass algal cultures of Chlorella. In this study, a comprehensive range of factors, including morphological characters, biochemical compositions, and specific growth rate of ten species or strains of Chlorella, were evaluated for their effect on the feeding ability of P. malhamensis, which was assessed by two parameters: the clearance rate of P. malhamensis on Chlorella spp. and the specific growth rate of P. malhamensis. The results showed that the clearance rate of P. malhamensis was negatively correlated with cell wall thickness and specific growth rate of Chlorella spp., while the specific growth rate of P. malhamensis was positively correlated with carbohydrate percentage and C/N ratio and negatively correlated with protein, lipid percentage, and nitrogen mass. In conclusion, the factors influencing feeding selectivity include not only the morphological character and chemical composition of Chlorella, but also its population dynamics. Our study provides useful insights into the key factors that affect the feeding selectivity of P. malhamensis and provides basic and constructive data to help in screening for grazing‐resistant microalgae.     

Improving the aqueous solubility of HCV‐E2 glycoprotein epitope mimics by cyclization using POLAR hinges

In this research we describe the improvement of the water‐solubility of cyclic epitope mimics based on the HCV E2 glycoprotein by incorporation of suitable polar hinges. The poor solubility of epitope mimics based on peptide sequences in the envelope (E2) protein hampered their synthesis and purification and made it very difficult to prepare the molecular constructs for evaluation of their bioactivity. Since changes in the amino acid composition are hardly possible in these epitope mimics in order to increase water‐solubility, a polar cyclization hinge may offer a remedy leading to a significant increase of polarity and therefore water solubility. These polar hinges were applied in the synthesis of better water‐soluble HCV‐E2 epitopes. An azide functionality in the polar hinges allowed attachment of a tetraethylene glycol linker by Cu‐catalyzed azide‐alkyne cyclo‐addition (CuAAC) for a convenient conjugation to ELISA plates in order to evaluate the bio‐activity of the epitope mimics. The immunoassays showed that the use of more polar cyclization hinges still supported anti‐HCV antibody recognition and did not negatively influence their binding. This significantly increased solubility induced by polar hinges should therefore allow for the molecular construction and ultimate evaluation of synthetic vaccine molecules.     

Abundance and phenology of macrofungal fruiting bodies in central and northern Japan

To understand how ectomycorrhizal (ECM), wood-decomposing (WDC) and litter-decomposing (LDC) fungi differ in abundance and fruiting season, fruiting-body production was monitored by counting their number and/or measuring their biomass in deciduous broad-leaved and coniferous forests in Ishikawa (central Japan) and Hokkaido (northern Japan). ECM fungi were dominant in forests of both types in Ishikawa and a Larix kaempheri forest in Tomakomai (Hokkaido), whereas WDC fungi were dominant in a deciduous broad-leaved forest in Sapporo (Hokkaido). ECM and WDC fungi usually showed two abundance peaks in Kanazawa (Ishikawa), mid-summer and autumn for ECM fungi and spring or summer and autumn for WDC fungi, whereas LDC fungi usually showed one peak in autumn. In Tomakomai, the abundance peak appeared later in ECM fungi but earlier in LDC and WDC fungi in comparison with Kanazawa. The mode of resource acquisition is assumed as one of factors that affect the seasonal timing of fruiting-body production. On the other hand, highly positive correlations were often observed between precipitation in Jun or Aug and the fruiting-body production in summer and/or autumn in the survey in Kanazawa, suggesting that precipitation could affect the fruiting-body production a few months later.     

Increased high‐latitude photosynthetic carbon gain offset by respiration carbon loss during an anomalous warm winter to spring transition

Arctic and boreal ecosystems play an important role in the global carbon (C) budget, and whether they act as a future net C sink or source depends on climate and environmental change. Here, we used complementary in situ measurements, model simulations, and satellite observations to investigate the net carbon dioxide (CO₂) seasonal cycle and its climatic and environmental controls across Alaska and northwestern Canada during the anomalously warm winter to spring conditions of 2015 and 2016 (relative to 2010–2014). In the warm spring, we found that photosynthesis was enhanced more than respiration, leading to greater CO₂ uptake. However, photosynthetic enhancement from spring warming was partially offset by greater ecosystem respiration during the preceding anomalously warm winter, resulting in nearly neutral effects on the annual net CO₂ balance. Eddy covariance CO₂ flux measurements showed that air temperature has a primary influence on net CO₂ exchange in winter and spring, while soil moisture has a primary control on net CO₂ exchange in the fall. The net CO₂ exchange was generally more moisture limited in the boreal region than in the Arctic tundra. Our analysis indicates complex seasonal interactions of underlying C cycle processes in response to changing climate and hydrology that may not manifest in changes in net annual CO₂ exchange. Therefore, a better understanding of the seasonal response of C cycle processes may provide important insights for predicting future carbon–climate feedbacks and their consequences on atmospheric CO₂ dynamics in the northern high latitudes.     

Field evaluation of nucleopolyhedrosis virus and some biorational insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

American bolloworm, Helicoverpa armigera Hubner (Noctuidae: Lepidoptera) is considered as a major pest of various crops all over the world. It is mainly controlled by indiscriminate use of synthetic insecticides in the world due to which this pest developed resistance to most of the available insecticides. Therefore, in the current study, the efficacy of virulent strain of HaNPV (0.5 × 10⁹ PIB/ml) alone and in combination with recommended doses of spintoram (20 g/100 L of water) and emamectin benzoate (200 ml/100 L of water) was tested in field. The combination of HaNPV with spintoram and emamectin benzoate 100% reduced the larval population as compared to emamectin benzoate and HaNPV alone. This suggested that the combination of spintoram and emamectin benzoate with HaNPV could be used in field to manage the infestation of H. armigera.