Reconstruction of adaptive radiation in insular habitats using integrated biogeographic information

Aim To develop an analytical method for accurately reconstructing the biogeographic events associated with adaptive radiation in a system of insular habitats. Location An idealized, two-dimensional model system of insular habitats is based on the altitudinally stratified vegetation zones on the island-like mountains of eastern Africa. Methods The model system is treated as a two-dimensional array of insular habitats, and adaptive radiation is treated as a ‘space-filling’ process according to six premises based on uniformitarian principles. Previous approaches to this class of problems have used (1) Hennig's progression rule, (2) optimization of biogeographic character states, and (3) reasoned argumentation with an intuitive synthesis of information. The strengths and limitations of these previous approaches are evaluated. Results A closed analytical method is presented that accurately reconstructs biogeographic events. This methodological approach integrates atomized information back up to the appropriate level of biological organization and has general applicability to phylogenetic analysis. Main conclusions In a truly evolutionary approach to phylogenetic systematics and biogeography, the initial analysis of the pattern of descent should be complemented with a subsequent analysis of the pattern of modification. The method presented here offers one approach to analysing the pattern of modification, which in this case constitutes biogeographic movement.     

Red cell aging. II. Anomalous electrophoretic properties of neuraminidase treated human erythrocytes.

Desialylation of human red blood cells (RBC) by Vibrio cholerae neuraminidase (VCN) was found to produce cells with electrophoretic properties which were inconsistent with the view of simple loss of N-acetylneuraminic acid (NANA) as the sole effect of VCN treatment. Modification of human RBC with 50--350 U VCN/10(10) RBC for one hour at 37 degrees C releases 90-100% of the NANA and produces a progressive decrease towards zero in their electrophoretic mobilities when measured in 0.15 M NaCl (pH 7.2) at 25 degrees C. The appearance of positive groups on the desialylated cells was indicated by the VCN-treated cells displaying positive mobilities below approximately pH 5.5 and increased negative mobilities at approximately pH 9 as well as substantial increases in their mobility at neutral pH following treatment with formaldehyde. Adsorption of about 95% of the VCN activity at 0 degrees C to the RBC did not produce any significant change in their electrophoretic mobilities thus indicating that the observed changes in the electrophoretic properties of the RBC following VCN treatment could not be attributable to adsorption of VCN. These studies indicate that the cationic charge groups which appear at the electrophoretic surface of the RBC after VCN treatment are probably of endogenous origin. It is suggested that this alteration rather than simple NANA release may operate to shorten the in vivo survival time of desialylated red cells.     

Development and histochemistry of the cells,cell walls,and cuticle of the dermal system of fruit of the grape,Vitis vinifera L.

Summary The dermal system comprises the outer epidermis of the pericarp, its covering of wax and cuticle and the collenchymatous hypodermal cells. During the first of the two post-anthesis phases of fruit growth, differentiation occurred with respect to cell and nuclear volume, content of polyphenolic substances, and wall thickening. Walls of the presumptive dermal system cells developed massive primary thickenings which stained intensely with fluorescent brightener dyes. In the second phase of fruit growth these cells were redifferentiated, their walls becoming thinner as they enlarged to accommodate fruit expansion. Binding of the fluorescent brightener dye was reduced and confined to the outer edges of the walls. At maturity, the walls of the cortical cells adjacent to the dermal system underwent autolysis.The cuticle was evident during the first 16 days after anthesis as a thin layer which reacted positively with neutral lipid dyes and which contained periodate sensitive vinyl groups. Differentiation of a secondary cuticle followed, and a number of distinct layers were detected by autofluorescence, and staining with auramine 0, Nile blue, and PAS. Cuticle thickness and complexity was maintained throughout the second growth phase.     

Disproportionate effect of cationic antiseptics on the quantum yield and fluorescence lifetime of bacteriochlorophyll molecules in the LH1-RC complex of R. rubrum chromatophores

Photosynthesis Research - Photosynthetic membrane complexes of purple bacteria are convenient and informative macromolecular systems for studying the mechanisms of action of various physicochemical...     

Theory of fluorescence polarization in magnetically oriented photosynthetic systems.

Many cells and cell fragments are known to assume specific alignments with respect to an applied magnetic field. One indicator of this alignment is a difference between the intensities of fluorescence observed in polarizations parallel and perpendicular to the magnetic filed. We calculate these two intensities using a model that assumes axially symmetric membranes and that covers a wide variety of shapes from flat disk to right cylinder. The fluorescence is assumed to originate at chromophores randomly exicted but nonrandomly oriented in the membranes. The membrane alignment is assumed to be due to the net torque on a nonrandom distribution of diamagnetically anisotropic molecules. The predicted results are consistent with most magnetoorientation data from green cells, but we are able to show that Chlorella data are not consistent with the hypothesis that the membranes have, and maintain, a cuplike configuration.