Multicellular plants depend for their integrity on effective adhesion between their component cells. This adhesion depends upon various cross-links; ionic, covalent or weak interactions between the macromolecules of the adjacent cell walls. In sugar-beet (Beta vulgaris L. Aztec) root parenchyma, cell-cell adhesion is disrupted by successive extractions with a calcium-chelating agent (imidazole) and a de-esterifying agent (sodium carbonate) but not by the calciumchelating agent or the de-esterifying agent alone. Cell-cell adhesion in sugarbeet parenchyma thus depends upon both ester and Ca 2þ cross-linked polymers. Pectic polysaccharides are removed by these treatments. Both parallel-electron energy-loss spectroscopy (PEELS) and Image-EELS show that calcium-binding sites are removed from the wall by imidazole. Using a monoclonal antibody that recognizes a relatively unesterified epitope of homogalacturonan, JIM 5, we show that a subset of JIM 5-reactive antigens remain in the middle lamella after Ca 2þ chelation and that this subset is removed by cold (4 C) Na 2 CO 3 -induced breakage of ester bonds. Fourier transform infrared, nuclear magnetic resonance, and spectrophotometric assays show that methyl and feruloyl esters are removed from the wall by Na 2 CO 3 but acetyl esters remain. Sodium carbonate extraction at 20 C removes cell wall autofluorescence and most of the feruloylated moieties from the wall. We propose that the chelator-resistant subset of ester-linked JIM 5-reactive pectins are important for cell-cell adhesion.

SUMMARYSystemic movement of Sonchus yellow net virus to leaves and roots was first detected by ELISA 24 h after mechanical inoculation. Thereafter, virus levels rose to a maximum 10 days after inoculation; the highest levels were between 4-0 and 7.3 Ixg/g tissue, in leaves which were not yet fully expanded. Electron microscopy of tissue sections revealed that when the virus content of tissues was greatest, virtually all leaf and root cells were infected. Most of the virions were in the perinuclear space; only a few were scattered in the cytoplasm. Nuclei contained large viroplasms associated with viral nucleocapsids. Between 10 and 20 days after inoculation, levels of virus antigen and viral RNA fell to about 20~ of their maximum. By 20 days after inoculation, no more than 10~o of cells contained virus particles and almost all the virions were in the Cytoplasm. These results suggest that this virus spreads systemically until most or all cells are infected. The plants then undergo a recovery phase during which virus disappears from the nuclei of infected cells and vesiculates into the cytoplasm.

Background Evidence about how population mental health has evolved from before and over the COVID-19 pandemic remains mixed, with impacts on mental health inequalities being unclear. We investigated changes in mental health and sociodemographic inequalities from before and across the first year of the pandemic. Methods Data from 11 UK longitudinal population-based studies with pre-pandemic measures of psychological distress were analysed, estimates pooled, and stratified by age, sex, ethnicity, country and lone household status. Trends in the prevalence of poor mental health were assessed before the pandemic (TP0) and across the pandemic at three time periods (initial lockdown (TP1), easing of restrictions (TP2), and a subsequent lockdown (TP3)). Results In total, 49,993 adult participants were analysed across the 11 cohort studies. There was an overall worsening in mental health from pre-pandemic scores across all three pandemic timepoints, (TP1 Standardised Mean Difference: 0.15 (95% CI: 0.06 - 0.25); TP2 SMD: 0.18 (0.09 - 0.27); TP3 SMD: 0.21 (0.10 - 0.32)) with no evidence of improvement during the period of eased lockdown restrictions in summer 2020. Changes from pre-pandemic psychological distress were higher in females during the pandemic (TP3 SMD: 0.23 (0.11 - 0.35)), amongst those with degree-level education (TP3 SMD: 0.26 (0.14 - 0.38)), and adults aged 25-44 years. We did not find evidence of changes in distress differing by ethnicity, lone household status or UK nation. Conclusions The substantial deterioration in mental health seen in the UK during the first lockdown did not reverse when lockdown lifted and a sustained worsening was observed across the pandemic. Mental health declines have been unequal across the population and these results have implications for policy, including the need for specific investment for support for those most affected to mitigate the effects of the pandemic and measures to reduce inequalities within these specific groups. Key messages • A sustained deterioration in mental health was observed from before the start of the COVID-19 pandemic, and did not recover when social restrictions were eased. • Deterioration in mental health varied by sociodemographic factors, namely age, sex, and education, and highlights a need for improved mental health care provision to minimise widening inequalities.