Effects of anoxia on root ultrastructure of four neotropical trees.

The root ultrastructure of seedlings grown in anaerobic conditions was investigated in four neotropical species: Sesbania virgata, Erythrina speciosa, Sebastiania commersoniana (all present in waterlogged or flooded areas), and Schizolobium parahyba (that occupies mainly dry areas). Anaerobiosis induced an increase in the size of mitochondria, dilatation of cristae and of the endoplasmic reticulum, and fragmentation or concentric arrangement of reticulum saccules. The ultrastructural alterations were reversible only for S. virgata and E. speciosa. The seedlings of S. parahyba and S. commersoniana were more sensitive to oxygen deprivation and presented extensive cell disruption. The results are discussed in terms of energy supply.

Basic fuchsins and the Schiff-aldehyde reaction. I. Spectral absorption characteristics in solution.

Spectral absorption profiles at the UV and visible ranges were detected spectrophotometrically for solutions of various basic fuchsins, for the SCHIFF reagent prepared from these stains and for the end product from SCHIFF-formaldehyde reaction. The aim was to detect whether absorption spectra could vary as a function of the basic fuchsin origin up to the point of being suspected of affecting potentially the spectrum of FEULGEN-stained chromatin. The results indicate a constancy in the spectral absorption characteristics for the absorption profiles at the visible range, when one considers SCHIFF reagents prepared from various basic fuchsins added with aldehyde. However, it is possible that size, stereoarrangement and electron distribution of the aldehyde- (eventually, ketone-) bearing molecule involved in SCHIFF-carbonyl reactions would function as auxochroms, the spectral characteristics of which could be affected by dye content and contaminants of the basic fuchsin.