iReenCAM: automated imaging system for kinetic analysis of photosynthetic pigment biosynthesis at high spatiotemporal resolution during early deetiolation.

Seedling de-etiolation is one of the key stages of the plant life cycle, characterized by a strong rearrangement of the plant development and metabolism. The conversion of dark accumulated protochlorophyllide to chlorophyll in etioplasts of de-etiolating plants is taking place in order of ns to µs after seedlings illumination, leading to detectable increase of chlorophyll levels in order of minutes after de-etiolation initiation. The highly complex chlorophyll biosynthesis integrates number of regulatory events including light and hormonal signaling, thus making de-etiolation an ideal model to study the underlying molecular mechanisms.

An atypical tubulin kinase mediates stress-induced microtubule depolymerization in Arabidopsis.

Background: As sessile organisms, plants adapt to adverse environmental conditions by quickly adjusting cell physiology and metabolism. Transient depolymerization of interphase microtubules is triggered by various acute stresses and biotic interactions with pathogenic organisms. Although rapid remodeling of plant microtubule arrays in response to external stresses is an intriguing phenomenon, the underlying molecular mechanisms and the advantages of this response to plant performance are poorly understood.

Mitogen-activated protein kinase phosphatase PHS1 is retained in the cytoplasm by nuclear extrusion signal-dependent and independent mechanisms.

The organization of plant microtubule arrays is thought to be regulated by phosphorylation and other signaling cascades, but the molecular components involved are largely unknown. We have previously found that a dominant missense mutation (phs1-1) in a putative kinase-docking motif of an Arabidopsis PHS1 phosphatase, which belongs to the mitogen-activated protein kinase phosphatase (MKP) family, compromises the stability of cortical microtubules. We here report that suppressor screening of phs1-1 recovered several intragenic recessive mutations in PHS1.

A study of enzymic degradation of a macromolecular substrate, poly[N5-(2-hydroxyethyl)-L-glutamine], by gel permeation chromatography and kinetic modelling.

The enzymatic degradation of poly[N5-(2-hydroxyethyl)-L-glutamine] (PHEG) by papain was investigated with the aim of evaluating the role of the random and/or a non-random mechanism of cleavage. The random degradation was modelled experimentally by the reaction of PHEG with ethanolamine. Assuming that different mechanisms of cleavage would yield different molecular weight distributions (MWDs) of the polymer degraded to the same degree, the evaluation was based on the comparison of experimental MWDs, measured by gel permeation chromatography, with MWDs simulated kinetically for the assumed mechanism of degradation.

Degradation of N5-(2-hydroxyethyl)-L-glutamine and L-glutamic acid homopolymers and copolymers by papain.

The rate of degradation of poly[N5-(2-hydroxyethyl)-L-glutamine] (PHEG), poly(L-glutamic acid) (PGA) and poly[HEG-co-GA] random copolymers by papain was measured in the pH range 4.0-7.5, employing the gel permeation chromatography method.