Mung Bean Hypocotyl Homogalacturonan: Localization, Organization and Origin

Specific antibodies were used to localize both pectic structuresand pectinmethylesterases (PME) along the mung bean hypocotyl.Calcium ions were also detected and estimated in both young,plastic and mature, stiffened cell walls. Highly methylesterifiedpectins were present in all cell walls but decreased from thehypocotyl hook downwards. Expanded cell walls were characterizedby a high content of calcium ions and acidic pectins, althoughthe latter's cross-reactivity to JIM 5 antibodies was partlylost. Co-localization of acidic homogalacturonan and calciumions suggests the presence of egg-box structures that mightparticipate in the cell wall stiffening process which developsalong the hypocotyl. Acidic polymers could originate from theactivity of the pectinmethylesterases present in precise wallareas but direct export of acidic polygalacturonan through Golgivesicles was also observed. Copyright 1999 Annals of BotanyCompany Cell walls, immunolocalization, hypocotyl, mung bean, pectin organization, Vigna radiata.     

Effects of Protease Inhibitors on Protein Breakdown and Enzyme Induction in Starving <Emphasis Type="Italic">Escherichia coli</Emphasis>

PROTEIN degradation is relatively slow in growing bacteria but much faster when there is no source of carbon or nitrogen^1–3. These changes in degradative rates seem to be important for the adaptation of the cell to non-growing conditions and may be controlled by mechanisms similar to those regulating synthesis of ribosomal RNA⁴. Identification of selective inhibitors of protein breakdown could greatly facilitate study of the mechanisms of this process and its physiological significance.