Infection and pathogenesis of the Delta variant of SARS-CoV-2 in Rhesus macaque

Highlights
1. Delta variant of SARS-CoV-2 can effectively infect the Rhesus macaque.
2. The Delta variant grows faster than the early strain isolated from Wuhan in late 2019.
3. The shedding pattern, viral load and disease severity of Delta variant are similar with the early strain isolated from Wuhan in late 2019.
4. This study supports the attributed rapid disease spread of the Delta variant.     

Purification and characterization of lysozyme from plasma of the eastern oyster (Crassostrea virginica)

Lysozyme was purified from the plasma of eastern oysters (Crassostrea virginica) using a combination of ion exchange and gel filtration chromatographies. The molecular mass of purified lysozyme was estimated at 18.4 kDa by SDS-PAGE, and its isoelectric point was greater than 10. Mass spectrometric analysis of the purified enzyme revealed a high-sequence homology with i-type lysozymes. No similarity was found however between the N-terminal sequence of oyster plasma lysozyme and N-terminal sequences of other i-type lysozymes, suggesting that the N-terminal sequences of the i-type lysozymes may vary to a greater extent between species than reported in earlier studies. The optimal ionic strength, pH, cation concentrations, sea salt concentrations, and temperature for activity of the purified lysozyme were determined, as well as its temperature and pH stability. Purified oyster plasma lysozyme inhibited the growth of Gram-positive bacteria (e.g., Lactococcus garvieae, Enterococcus sp.) and Gram-negative bacteria (e.g., Escherichia coli, Vibrio vulnificus). This is a first report of a lysozyme purified from an oyster species and from the plasma of a bivalve mollusc.     

The glycine max xylem sap and apoplast proteome

Molecular signaling interactions in the plant apoplast are important for defense and developmental responses. We examined the soybean proteome of the apoplastic conduit of root-to-shoot communication, the xylem stream, using gel electrophoresis combined with two types of tandem mass spectrometry. We examined soybeans for the presence of a Bradyrhizobium japonicum-induced, long distance developmental signal that controls autoregulation of nodulation (AON) to determine if xylem proteins (XPs) were involved directly or indirectly in AON. The xylem and apoplast fluids collected in hypocotyl, epicotyl, and stem tissue contained a highly similar set of secreted proteins. The XPs were different from those secreted from imbibing seed implying they play important basic roles in xylem function. The XPs of wild-type and nts1007 plants were indistinguishable irrespective of plant age, inoculation status, or time after inoculation suggesting that none was directly involved in AON. XPs were continuously loaded into the xylem stream, as they were present even 28 h after shoot decapitation. These results were consistent with semiquantitative RT-PCR studies that examined the expression of genes corresponding to the XPs under inoculated or uninoculated conditions. Monitoring the expression of XP genes by RT-PCR showed that four possessed root biased expression. This suggested that the corresponding protein products could be produced in roots and travel long distances to shoots. Of these, a species of lipid transfer protein is a candidate for a water-soluble, long-distance signal-carrier due to the presence of hydrophobic clefts that bind known plant signals in vitro. Two soybean XPs identified in this study, lipid transfer protein and Kunitz trypsin inhibitor (KTI), have known roles in plant signaling.     

Preparation of 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid catalyzed by iron(III)porphyrins with (diacetoxyiodo)benzene

Using iron(III)porphyrins in combination with (diacetoxyiodo)benzene allows for the conversion of 2,9-bis(bromomethyl)-4,7-diphenyl-1,10-phenanthroline into 4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid. This method provides a cost-effective and environmentally-friendly oxidation procedure using less toxic PhI(OAc)₂ and biologically relevant iron(III)porphyrins. The catalytic activity of five kinds of iron-metallated functional porphyrins were investigated using different oxidants, including air, H₂O₂, PhI(OAc)₂, PhIO and NaClO. Our results showed that the use of T(p-NO₂)PPFeCl with PhI(OAc)₂ as the oxidant in the presence of water displays remarkable activity for the desired oxidation reaction. The generality of this method was examined by synthesizing the carboxylic acids of pyridines and quinolines.     

Altered Functional Connectivity in Patients with Subcortical Vascular Cognitive Impairment—A Resting-State Functional Magnetic Resonance Imaging Study

Recent neuroimaging studies have shown that people with subcortical vascular cognitive impairment (sVCI) have structural and functional abnormalities in the frontal lobe and subcortical brain sites. In this study, we used seed-based resting-state functional connectivity (rsFC) analysis and voxel-mirrored homotopic connectivity (VMHC) techniques to investigate the alteration of rsFC in patients with sVCI. rsFC and structural magnetic resonance images were acquired for 51 patients with subcortical cerebrovascular disease. All patients were subdivided based on cognitive status into 29 with sVCI and 22 controls; patient characteristics were matched. rsFC of the posterior cingulate cortex (PCC) and VMHC were calculated separately, and rsFC of the PCC and VMHC between the two groups were compared. The regions showing abnormal rsFC of the PCC or VMHC in sVCI patients were adopted as regions of interest for correlation analyses. Our results are as follows: The patients with sVCI exhibited increases in rsFC in the left middle temporal lobe, right inferior temporal lobe and left superior frontal gyrus, and significant decreases in rsFC of the left thalamus with the PCC. sVCI patients showed a significant deficit in VMHC between the bilateral lingual gyrus, putamen, and precentral gyrus. Additionally, the z-memory score was significantly positively associated with connectivity between the left thalamus and the PCC (r = 0.41, p = 0.03, uncorrected) in the sVCI group. Our findings suggest that the frontal lobe and subcortical brain sites play an important role in the pathogenesis of sVCI. Furthermore, rsFC between the left thalamus and the PCC might indicate the severity of sVCI.     

Involvement of Polyamine Oxidase in Abscisic Acid induced Cytosolic Antioxidant Defense in Leaves of Maize

Using pharmacological and biochemical approaches, the role of maize polyamine oxidase (MPAO) in abscisic acid (ABA)induced antioxidant defense in leaves of maize (Zea mays L.) plants was investigated. Exogenous ABA treatment enhanced the expression of the MPAO gene and the activities of apoplastic MPAO. Pretreatment with two different inhibitors for apoplastic MPAO partly reduced hydrogen peroxide (H2O2) accumulation induced by ABA and blocked the ABA-induced expression of the antioxidant genes superoxide dismutase 4 and cytosolic ascorbate peroxidase and the activities of the cytosolic antioxidant enzymes. Treatment with spermidine, the optimum substrate of MPAO, also induced the expression and the activities of the antioxidant enzymes, and the upregulation of the antioxidant enzymes was prevented by two inhibitors of MPAO and two scavengers of H2O2. These results suggest that MPAO contributes to ABA-induced cytosolic antioxidant defense through H2O2, a Spd catabolic product.