Age-dependent increase in the non-specific cholinesterase activity of the capillaries in the rat neostriatum

Summary Histochemically demonstrable non-specific cholinesterase activity in the capillaries of the neostriatum of 3–5-month-old rats was much weaker than that of 24–27-month-old rats. In the young adult rats the activity was electron microscopically localized mainly in endoplasmic reticulum and perinuclear cisternae of the endothelial cells, while capillaries of old rats showed a positive reaction also in the basal lamina and outer cell membranes of glial processes.     

Optimal Regulation of Gas Exchange: Evidence from Field Data

Since the work of Cowan in 1977 it has been assumed that plantsregulate their stomata in a way that maximizes photosynthesisat a constant average rate of transpiration. The approach wasfurther developed by Hari et al. (1986) by introducing additionalassumptions which enabled the mathematical solution of the optimizationproblem using the Lagrangian method. The solution is testedfor Scots pine seedlings against field data. The results supportthe optimization hypothesis.Copyright 1993, 1999 Academic Press Pinus sylvestris (L.), stomatal conductance, photosynthesis, transpiration, optimization, field measurements, mathematical model, Lagrangian method     

Finding a common ordination for several data sets by individual differences scaling

Individual differences scaling is a multidimensional scaling method for finding a common ordination for several data sets. An individual ordination for each data set can then be derived from the common ordination by adjusting the axis lengths so as to maximize the correlations between observed proximities and individual ordination distances. The importance of the various axes for each data set and the mutual similarities and goodness of fit for the individual data sets are described by weight plots. As an example, 46 soft-water lakes in eastern Finland are ordinated on two dimensions according to 3 chemical data sets (water in summer and autumn, sediment) and 4 biological sets (major phytoplankton groups, phytoplankton, surface sediment diatom and cladoceran assemblages). The method seems to be effective as a means of ordination for obtaining the common ordination for the data sets. The major taxonomic groups gave the ordination which differed most clearly from the ordinations of the other data sets. Phytoplankton was most poorly ordinated in all the analyses. The other data sets were fairly coherent. When only biological data sets were ordinated, the diatoms and cladocerans showed rather different patterns. It seems that the cladocerans are best correlated with water chemistry, both according to weights in the joint analysis, and according to correlation between the axes from the biological data sets and the chemical variables.Abbreviations CCA = Canonical correspondence analysis - IDS = Individual differences scaling - MDS = multidimensional scaling - PCA = Principal components analysis     

Complementary developmental expression of the two tyrosine hydroxylase transcripts in zebrafish

Tyrosine hydroxylase (TH) is a rate-limiting enzyme in the biosynthesis of catecholamines. In zebrafish, two genes encoding TH have been identified. We cloned them and studied their expression in zebrafish. In adult tissues, th1 mRNA was more abundant than th2 mRNA in the brain and eyes, whereas th2 mRNA was more abundant in the liver, kidney, heart and gills. In developing brain, th1 mRNA was readily detected at 1 day post-fertilization using qPCR and in situ hybridization, whereas th2 mRNA appeared later. th1 was found in 17 catecholaminergic groups in larval brain, whereas th2 was found in four additional groups. A monoclonal antibody commonly used against TH detected preferentially TH1 protein. The two th genes, probably originated as a result of genome duplication, thus show complementary expression, although th1 is predominant in the brain and th2 in the periphery. th2 may be a novel essential factor in regulation of catecholamine synthesis in zebrafish.     

Notes on the morphological variation of the rotifer species Keratella cochlearis (Gosse) s.l. in one eutrophic pond

Morphological variation of Keratella cochlearis (Gosse) s.l.were monitored during two years in one eutrophic pond in centralFinland. Nine different taxonomical forms were found duringthe observations. Very significant negative correlation wasfound between water temperature and total length of tecta series.Some forms (forms of hispida series and irregularis series)were found only during warm water seasons. The lorica structureof different morphs was also studied by SEM techniques and besidesin the plaque patterns, differences were found among pustulationand pustule structure of different types.