Infraspecific variation in Cerastium alpinum s. lat. (Caryophyllaceae) in Central Norway

Within Cerastium alpinum s. lat., several taxa have been circumscribed. Three infraspecific taxa are currently recognized in Nordic literature, but the opinions have varied about their taxonomic levels and relations to each other. Populations of these three taxa — alpinum, glabratum and lanatum — were investigated in Central Norway to elucidate taxonomic relationships on a regional scale. Morphometric analyses (PCA ordination) based on two data sets; one with 61 characters, and one without the 35 indumentum characters, gave different results. The former partly support the use of a higher rank for glabratum , but this analysis may put too much weight on indumentum characters. The reduced data set gave a more continuous transition between the three taxa, with no special status for glabratum. Crossing experiments between the taxa indicated full cross compatibility as far as relative seed set was concerned. Finally, vegetation analysis (DCA ordination) indicated that the three taxa have somewhat different ecological demands. This suggests that they, in spite of hybridization abilities, normally are maintained as separate entities due to habitat differences. A delimitation of three infraspecific taxa at the same level within C. alpinum s. lat. is thus supported by this study. Whether these taxa should be treated as subspecies or varieties strongly depends upon the definitions of these categories. Viewed in a wide geographical context, however, the arguments for subspecific rank are strengthened.     

Changes in the population dynamics of Keratella cochlearis (Gosse), Kellicottia longispina (Gosse) and Polyarthra vulgaris Carlin in a fertilized enclosure

The population dynamics of phytoplankton and zooplankton in a fertilized enclosure were studied from April 1977 to June 1978. During the first spring period, the rotifers Keratella cochlearis, Kellicottia longispina, and Polyarthra vulgaris were scarce. During the following spring, all three species were abundant. An attempt is made to explain these differences. Food resource competition from cladocerans, and the low food quality and possible inhibitory effects of Coccomyxa sp. were found to be the most likely factors limiting the growth of these rotifers during the first spring period.     

On the origin of Z-band material and myofilaments in myoblasts from the human atrial wall

Summary The origin of cardiac myofibrils in cells from the atrial wall in human embryos was studied. Z-band substance appears throughout the cytoplasm as irregular electron dense patches in a network of thin filaments. The thin and thick filaments are synthesized as separate units in the sarcoplasm and are later aggregated into myofibrils. Complexes of Z substance and thin filaments occur numerously at different stages of myofibrillar organisation. Thick filaments are formed in close proximity to free ribosomes and are later incorporated in an hexagonal pattern into the Z-band/thin filament complex.This work was supported by grants from The Norwegian Council on Cardiovascular Disease and from The Norwegian Research Council for Science and the Humanities     

Some molecular properties of NAD(P)H dehydrogenase from rat liver

NAD(P)H dehydrogenase (EC 1.6.99.2) purified from rat liver cytosol revealed three discrete bands, of mol.wts. about 27000, 18000 and 9000, when subjected to polyacrylamidegel electrophoresis in the presence of sodium dodecyl sulphate. Elution of the bands from the gel and individual re-electrophoresis on separate gels showed that the 27000-mol.wt. band yielded three bands similar to those obtained with the intact enzyme, whereas the 18000-mol.wt. band retained its characteristic mobility. Amino acid analysis of native enzyme and protein extracted from each of the three bands from sodium dodecyl sulphate/polyacrylamide gels suggests that the native enzyme is composed of two subunits and that each subunit consists of two dissimilar non-covalently bound polypeptides, so that altogether the enzyme is composed of four polypeptides, two of mol.wt. 18000 and two of mol.wt. 9000. NAD(P)H dehydrogenase was active over a wide pH range with no sharp optimum. The same K(m) value for NADH but different values for V(max.) were obtained for the enzyme purified from Sprague-Dawley and Wistar rats. In immunodiffusion, however, the enzymes from the two rat strains showed a reaction of complete identity. NAD(P)H dehydrogenase was effectively inhibited by thiol-blocking reagents, indicating that the activity is dependent on free thiol group(s). By amino acid analysis six cysteine residues were found per mol of enzyme. Guanidino-group- and amino-group-selective reagents had only moderate inactivating effects on the enzyme activity.     

Ultrastructure of the heart of the sturgeon Acipenser stellatus (Chondrostei)

Summary The ultrastructure of atrial and ventricular myocardial cells from Acipenser stellatus is described. The cells of the atrium are more loosely connected than those of the ventricle. Cell contact is by simple intercalated discs and by desmosomes. The cells are flattened, with peripheral myofibrils and a central region of mitochondria and the nucleus. The sarcoplasmic reticulum consists of subsarcolemmal tubules, that frequently extend towards the central mitochondria. Dyads are small and positioned at any sarcomeric level. No T-tubules are present. Specific granules are restricted to the atrial cell, and are sometimes present within the SR tubules.     

Heterogeneity of 11q13 region rearrangements in laryngeal squamous cell carcinoma analyzed by microarray platforms and fluorescence in situ hybridization

We reinvestigated rearrangements occurring in region q13 of chromosome 11 aiming to: (i) describe heterogeneity of the observed structural alterations, (ii) estimate amplicon size and (iii) identify of oncogenes involved in laryngeal cancer progression as potential targets for therapy. The study included 17 cell lines derived from laryngeal cancers and 34 specimens from primary laryngeal tumors. The region 11q13 was analyzed by fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH) and gene expression microarray. Next, quantitative real time PCR was used for chosen genes to confirm results from aCGH and gene expression microarray. The observed pattern of aberrations allows to distinguish three ways, in which gain and amplification involving 11q13 region may occur: formation of a homogeneously staining region; breakpoints in/near 11q13, which lead to the three to sevenfold increase of the copy number of 11q13 region; the presence of additional copies of the whole chromosome 11. The minimal altered region of gain and/or amplification was limited to ~1.8 Mb (chr.11:69,395,184–71,209,568) and comprised mostly 11q13.3 band which contain 12 genes. Five, out of these genes (CCND1, ORAOV1, FADD, PPFIA1, CTTN) had higher expression levels in comparison to healthy controls. Apart from CCND1 gene, which has an established role in pathogenesis of head and neck cancers, CTTN, ORAOV1 and FADD genes appear to be oncogene-candidates in laryngeal cancers, while a function of PPFIA1 requires further studies.     

Weighted average regression and environmental calibration as a tool for quantifying climate-driven changes in vegetation

Aims Studies of the climatic responses of plant assemblages via vegetation-based environmental reconstructions by weighted averaging (WA) regression and calibration are a recent development in modern vegetation ecology. However, the performance of this technique for plot-based vegetation datasets has not been rigorously tested. We assess the estimation accuracy of the WA approach by comparing results, mainly the root mean square error of prediction (RMSEP) of WA regressions for six different vegetation datasets (total species, high-frequency species and low-frequency species as both abundance and incidence) each from two sites.     

Genetic structure of brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis> L.) from the Hardangervidda mountain plateau (Norway) analyzed by microsatellite DNA: a basis for conservation guidelines

The Hardangervidda in southern Norway, the largest mountain plateau in Europe, has thousands of lakes and streams, mainly between 1000 and 1300 m above sea level, where brown trout is the only fish species. To describe the current genetic diversity of brown trout in this area, a total of 863 fish from 20 lakes were genotyped with eleven microsatellites. Most diversity is within lake populations, but diversity among geographical groups and populations within groups was significant, too. Neighbor-joining, principle coordinate analysis and Bayesian clustering show three major geographic groups in accordance with the river systems. Bias was caused by recent stocking in two lakes. Low/no genetic differentiation among some populations indicates that intermixing is common when lakes are well-connected, as was also shown by assignment test. We recommend preserving the genetic diversity of brown trout in this unique area by managing stocking in lake systems according to genetic structure.