Drosophila vitelline membrane genes contain a 114 base pair region of highly conserved coding sequence

Two Drosophila vitelline membrane (VM) genes located at polytene band positions 26A and 34C have been characterized at the nucleotide level. Sequence comparison of the two genes VM26A.1 and VM34C.1 has revealed a similar 114 base pair region centrally located in the coding regions of both genes. The conserved region has a 91% homology at the nucleic acid level and a 100% conservation at the amino acid level. This suggests a common evolutionary origin for these VM genes and indicates that a strong selective pressure exists to maintain a specific polypeptide sequence in a domain of the proteins.     

Fallen retention aspen trees on clear-cuts can be important habitats for red-listed polypores: a case study in Finland

Green-tree retention is a relatively new forestry application, which aims at decreasing the negative effects of clear-cut logging on forest biodiversity. In this study, the value of retained aspens in maintaining diverse assemblages of wood-decaying fungi (polypores; Basidiomycota) on clear-cuts was investigated, after the retention trees had died, fallen and started to decay. A total of 110 fallen aspen trunks were investigated on clear-cuts and within old-growth forests in eastern Finland, southern boreal zone; and 499 records of polypores belonging to 46 species were made. The intermediately decayed trunks on a clear-cut area hosted more species and more red-listed species than did trunks within forests. Most of the polypore species with more than two records were found in both habitats. These results suggest that many aspen-associated polypores are able to live and reproduce in sun-exposed habitats, if the quality and quantity of dead wood fulfill the species-specific requirements. This unexpected result, however, may be partly due to the exceptionally great abundance of aspen in the study area. Furthermore, in the long term, the local benefits of fallen retention trees can be limited, unless the local continuity of large aspens, both living and dead, is ensured.     

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.     

Population and community level responses in Anas -species to patch disturbance caused by an ecosystem engineer, the beaver

We studied the response of a guild of three Anas -species, to patch disturbance caused by the beaver Castor canadensis in southern Finland during 1988–1996 Of the three species, the teal Anas crecca increased in beaver ponds during the first two years of beaver occupation compared to the situation before the beaver The mallard Anas platyrhynchos and wigeon Anas penelope did not respond to beaver flooding during the first two years Also dominance relations changed upon inundation The mallard usually was more numerous than the teal before the beaver, but the reverse was the case during beaver occupation The study shows that some animal guilds may benefit from disturbance although species dominance relations may change And, that this change in dominance can be caused by an ecosystem engineer, the beaver