Expression of photosynthesis- and senescence-related genes during leaf development and senescence in silver birch (Betula pendula) seedlings

Leaf development and senescence were studied in greenhouse-grown silver birch ( Betula pendula Roth) seedlings over a period of 7 weeks. Prior to the experiment, leaves from 100 seedlings were marked for five sampling dates. Timing of the developmental phases was studied with biochemical analyses of total soluble protein, Rubisco protein, chlorophyll concentration and at the level of gene expression related to photosynthesis, energy metabolism, ethylene synthesis and protein degradation. During the sampling period, an initial increase in photosynthetic capacity could be seen, when expression of the Rubisco small subunit gene ( RbcS ) and Rubisco protein (EC 4.1.1.39) were examined. Down-regulation of photosynthesis, visible as a decrease in Rubisco protein and RbcS mRNA, started soon after full expansion of the leaves and processes related to senescence followed. mRNA accumulation for the ethylene-forming enzyme 1-aminocyclopropane-1-carboxylic acid oxidase increased first during the onset of senescence. Protein degradation was observed as a loss of soluble proteins, with a simultaneous increase in the leucine aminopeptidase (EC 3.4.11.1) mRNA levels. The mRNA levels of ribonuclease-like pathogenesis-related protein 10 also increased clearly during senescence, but the mitochondrial phosphate translocator mRNA showed only a slight increase. Chlorophyll concentration of the leaves decreased after the mRNA levels of these senescence-related genes had become more abundant.     

Multiple origins of symbioses between ascomycetes and bryophytes suggested by a five‐gene phylogeny

Numerous species of microscopic fungi inhabit mosses and hepatics. They are severely overlooked and their identity and nutritional strategies are mostly unknown. Most of these bryosymbiotic fungi belong to the Ascomycota. Their fruit‐bodies are extremely small, often reduced and simply structured, which is why they cannot be reliably identified and classified by their morphological and anatomical characters. A phylogenetic hypothesis of bryosymbiotic ascomycetes is presented. New sequences of 78 samples, including 61 bryosymbionts, were produced, the total amount of terminals being 206. Of these, 202 are Ascomycetes. Sequences from the following five gene loci were used: rDNA SSU, rDNA LSU, RPB2, mitochondrial rDNA SSU, and rDNA 5.8S. The program TNT was used for tree search and support value estimation. We show that bryosymbiotic fungi occur in numerous lineages, one of which represents a newly discovered lineage among the Ascomycota and exhibits a tripartite association with cyanobacteria and sphagna. A new genus Trizodia is proposed for this basal clade. Our results demonstrate that even highly specialized life strategies can be adopted multiple times during evolution, and that in many cases bryosymbionts appear to have evolved from saprobic ancestors. © The Willi Hennig Society 2009.     

Genetic and environmental factors in health-related behaviors: studies on Finnish twins and twin families.

Family, twin and adoption studies have provided evidence for familial and genetic influences on individual differences in disease risk and in human behavior. Attempts to identify individual genes accounting for these differences have not been outstandingly successful to date, and at best, known genes account for only a fraction of the familiality of most traits or diseases. More detailed knowledge of the dynamics of gene action and of specific environmental conditions are needed. Twin and twin-family studies with multiple measurements of risk factors and morbidity over time can permit a much more detailed assessment of the developmental dynamics of disease risk and the unfolding of behavioral risk factors.     

The active site and the phospholipid activation of rat liver lysosomal lipase are not stereospecific

The stereochemical specificity of lysosomal lipase of rat liver was investigated using enantiomeric triacylglycerol analogs, sn-1-alkyl-2,3-diacylglycerol and sn-3-alkyl-1,2-diacylglycerol as substrates. Lysosomal lipase utilized both substrates with equal rates. The dependence of the activity of lysosomal lipase on the stereoconfiguration of activating acidic phospholipid was also studied. Our results showed that both sn-3-phospholipids (diphosphatidylglycerol, phosphatidylserine) and sn-1-phospholipids (bis(monoacylglycero)phosphate (BMP) were efficient activators of this enzyme and thus the stereochemical configuration of the activating phospholipid is not important. Accordingly, the rat liver lysosomal lipase lacks stereospecificity with respect to both the triacylglycerol substrate and the acidic phospholipid activator.     

Family break-up in farmed silver foxes (Vulpes vulpes) housed in enlarged cage systems as families

We monitored the behaviour of farmed silver foxes housed in family units in enlarged cage systems from weaning until late October. Activity of family members, use of space available, and aggressive acts were recorded. Aggressiveness between family members increased from July until October, leading to a more scattered use of the available space. Furthermore, the mean activity level of family members increased, and the synchrony of activity decreased. We conclude that social tension in the fox families increased gradually during the autumn, leading to dispersion of the family members. Received in revised form: 22 October 2001 Electronic Publication