Genetics of the peroxidase isoenzymes in Petunia

Summary By starch gel electrophoresis three mobility variants of a cathodic moving doublet of bands, encoded by the structural gene prxC, were detected in all organs of flowering petunias. In root tissue two of the variants showed a lower electrophoretic mobility than in other organs. During development of flower buds the PRXc enzymes showed an increase in mobility. The gene prxC was located on chromosome IV by showing linkage to the genes An3 and Dw1, by trisomic segregation, and by the construction of triply heterozygous trisomics IV. The gene order on chromosome IV is B1-An3/Dw1-prxC. It was concluded that the temporal programming difference in the expression of the alleles prxC2 and prxC3 is caused by internal site mutation. Analysis of progeny obtained by crossing of lines to the trisomic IV with genotype prxC1/C1/C2 showed differential expression of the two prxC1 alleles of the trisomic IV.     

Ecophysiology and distribution of the endemic leafless spurgeEuphorbia aphylla and the introducedE. tirucalli (Euphorbiaceae,Euphorbia sect.Tirucalli) in the Canary Islands

The leafless spurgeEuphorbia aphylla (Euphorbiaceae), an endemic species restricted to several of the Canary Islands where it inhabits coastal and arid localities, expresses Crassulacean Acid Metabolism (CAM) when it is subjected to summer drought. A flexible CAM is consistent with the general ecology of the species. It is the only member of sect.Tirucalli native to the Canary Islands and is at the north-western edge of the section's biogeographical range. The other members of the section have a paleotropic distribution and are found throughout Africa. Many of them are regarded as obligate CAM plants, includingE. tirucalli which was used as a comparison in ecophysiological experiments examining the response ofE. aphylla to drought and temperature.     

Symptoms of Lewy body dementia and clinical course compared with Alzheimer's disease

Lewy body dementia (LBD) is a neurodegenerative disease with well-defined symptoms and established clinical criteria, characterized by the presence of cortical and subcortical dementia, accompanied by some characteristic features such as Parkinsonism, visual hallucinations and fluctuations in alertness and attention, as well as hypersensitivity to neuroleptics. Compared with Alzheimer's disease, LBD seems to have a more rapid clinical course and greater mortality. The differences with Alzheimer's disease may be more apparent in the initial stages of the disease but tend to disappear with disease progression. Because of the greater presence of neuropsychiatric symptoms and the higher degree of dependency in LBD, there is greater caregiver overload and probably greater resource use.     

Chromium oxalate: a new spin label broadening agent for use with thylakoids.

Potassium tris(oxalato)chromate(III) trihydrate (chromium ixalate) has been shown to be a more useful broadening agent than potassium ferricyanide for the spin label 2,2,6,6-tetramethylpiperidine-N-oxyl-4-amine (Tempamine) in thylakoid suspensions. Our data show that chromium oxalate is less permeable than ferricyanide, does not inhibit thylakoid electron transport or photophosphorylation, and is not photoreduced by thylakoids.     

Peroxidase activity and structural transitions of cytochrome c bound to cardiolipin-containing membranes

During apoptosis, cytochrome c (cyt c) is released from intermembrane space of mitochondria into the cytosol where it triggers the caspase-dependent machinery. We discovered that cyt c plays another critical role in early apoptosis as a cardiolipin (CL)-specific oxygenase to produce CL hydroperoxides required for release of pro-apoptotic factors [Kagan, V. E., et al. (2005) Nat. Chem. Biol. 1, 223-232]. We quantitatively characterized the activation of peroxidase activity of cyt c by CL and hydrogen peroxide. At low ionic strength and high CL/cyt c ratios, peroxidase activity of the CL/cyt c complex was increased >50 times. This catalytic activity correlated with partial unfolding of cyt c monitored by Trp(59) fluorescence and absorbance at 695 nm (Fe-S(Met(80)) band). The peroxidase activity increase preceded the loss of protein tertiary structure. Monounsaturated tetraoleoyl-CL (TOCL) induced peroxidase activity and unfolding of cyt c more effectively than saturated tetramyristoyl-CL (TMCL). TOCL/cyt c complex was found more resistant to dissociation by high salt concentration. These findings suggest that electrostatic CL/cyt c interactions are central to the initiation of the peroxidase activity, while hydrophobic interactions are involved when cyt c's tertiary structure is lost. In the presence of CL, cyt c peroxidase activity is activated at lower H(2)O(2) concentrations than for isolated cyt c molecules. This suggests that redistribution of CL in the mitochondrial membranes combined with increased production of H(2)O(2) can switch on the peroxidase activity of cyt c and CL oxidation in mitochondria-a required step in execution of apoptosis.     

Influence of the inoculation time of high sugar content must on the formation of wine aroma

The addition of inocula of a commercially available strain of Saccharomyces cerevisiae to musts with a high initial sugar content at various fermentation stages induces variable changes in the different components of the volatile fraction of wine and, potentially, its sensory properties as well. Inoculation alters the concentration ratio between the 2,3-butanediol isomers and causes a decrease in acetates and ethyl ester content. We propose an analytical ratio to evaluate the aromatic quality of the wine.     

Characteristics of bird species using forest and agricultural land covers in southern Costa Rica

Our understanding of why tropical forest species differ in their ability to inhabit agroecosystems is limited, despite the link between this ability and the likelihood of population decline for species inhabiting regions undergoing widespread conversion of forest to agriculture. We used logistic regression and data from southern Costa Rica to develop a model based on natural history characteristics to distinguish between forest species that did or did not use agricultural land covers. We sampled birds along 15 3.0-km routes, seven in forest and eight in agriculture, five times over three years. Each species was classified as an F-species, detected only in forest, a G-species, detected in both forest and agriculture, or an A-species, detected only in agriculture. Thirty percent of species were F-species, 42% were G-species, and 28% were A-species. Based on the logistic regression model, the likelihood of being a G-species, as opposed to an F-species, was low for species that were dependent on forest interior, had a stenophagous diet, and a small elevational range. Weight, resident versus migrant status, and whether or not a species was insectivorous, were not significant predictors of being a G-species. For all F–G species pairs, the model correctly predicted the G-species 70% of the time. The model provides a first step in identifying those characteristics that predispose forest species to use agricultural land. In addition, our results indicate that the structurally simple agricultural systems of the study region are of limited value for a large proportion of the regional species pool.