Cell surface component(s) involved in rat hepatocyte intercellular adhesion

Aggregation of rat hepatocytes was effectively inhibited by monovalent antibodies (Fab fragments) directed against hepatocyte plasma membranes, but monovalent antibodies against some distinct, known hepatocyte surface antigens had no effect. Surface antigens, which neutralized the Fab inhibiting effect on cell aggregation, could be solubilized from plasma membranes by limited proteolytic digestion. Thus, hepatocyte intercellular adhesion seems to involve specific cell surface components, which may be proteins or protein derivatives.     

Heavy metal tolerance of marine phytoplankton. III. Combined effects of copper and zinc ions on cultures of four common species

The combined effects of copper and zinc ions on the growth of three marine diatoms and one dinoflagellate in culture have been studied. The two metals were found to act synergistically to all algae except Phaeodactylum tricornutum Bohlin. With this species an antagonistic effect was observed. Addition of zinc ions reduced the inhibition of growth caused by the more toxic copper ions. Zinc toxicity to this alga increased at low concentration of magnesium, indicating a common route for divalent metal ions in general.     

Rhizobial polysaccharide-degrading enzymes from roots of legumes

The surface structure and chemistry of symbiotic bacteria from the genus Rhizobium are probably important for the outcome of the infection of legume hosts. Exopolysaccharide, capsular polysaccharide, lipopolysaccharide and a low-molecular-weight polysaccharide were isolated from R. trifolii UTC 110-1 and R. leguminosarum UTC 114-5 and partially characterized. No or only minor differences in sugar composition could be found for the corresponding fractions from the two organisms. A general method to measure low activities of polymer-degrading enzymes was developed, and used to determine enzyme activities in root extracts of Trifolium repens L. cv. Lena and Pisum xativiini L. cv. Little Marvel against the isolated rhizobial polysaccharides. An enzyme preparation from T. repens partially degraded all polysaccharides isolated from its symbiont R. trifolii while polysaccharides from R. leguminosarum , symbiont of P. sativum , were degraded to a much lesser extent. Correspondingly, an enzyme preparation from P. sativum degraded all polysaccharides isolated from both its symbiont R. leguminosarum and its non-symbiont R. trifolii. The amount of symbiont polysaccharides degraded was larger than the amount of polysaccharides degraded from the non-symbiont R. trifolii.     

A Method for Simulating Signal Evolution Using Real Animals

We studied response biases to visual stimulation using a new experimental technique. The subjects (hens, Gallus gallus domesticus) were confronted with several rewarding and non‐rewarding patterns on a computer screen. In contrast with standard discrimination tasks the rewarding patterns were not identical and varied in a dimension differentiating them from the non‐rewarding patterns. The rewarding patterns changed in response to hens' biases in selection of patterns. The aim of the study was to examine the possibility of receivers being a driving force in signal evolution. In one of the experiments a clear‐cut result was obtained. During the course of the experiment the rewarding patterns became gradually more different from the non‐rewarding one, a result expected from theoretical studies of the effect of response bias in signal evolution. A second similar experiment was less conclusive, with ceiling and floor effects influencing the results.     

Shift Work Disorder in a Random Population Sample – Prevalence and Comorbidities

Few studies have investigated the presence of shift work disorder (SWD) in the general community. We addressed many of the limitations in this literature and present new findings. SWD has been treated as an ‘all or none’ construct but we propose the need to consider the ‘severity’ of the disorder. Using random digit dialling, we randomly recruited 1163 participants. Participants completed an extensive battery of scales and questions concerning work, health and individual differences. Three questions based on the criteria from the International Classification for Sleep Disorders were used to categorise participants with SWD (n = 176). In addition, we asked participants whether SWD interfered with aspects of their life and high ratings were used to define severe shift work disorder (SSWD). The prevalence of SWD was 32.1% among night workers and 10.1% in day workers (p<.001). SSWD was present in 9.1% of night workers and 1.3% of day workers (p<.001). Adjusted logistic regression analyses found significant associations between SWD and night work (OR  = 3.35, CI 2.19-5.12), weekly work hours (OR  = 1.02, CI 1.00–1.04), short sleep (≤6 h; OR  = 2.93, CI 1.94–4.41), languidity (OR  = 1.11, CI 1.06–1.16) and resilience (OR  = 0.56, CI 0.43–0.81). Night work, short sleep, languidity, and hypertension were significantly associated with SSWD. Overall, participants with SSWD slept 0.80 h less than other participants (p<.001). Night work, short sleep and languidity were associated with both SWD and SSWD. Day workers with SWD symptoms reported significantly shorter sleep duration, higher levels of languidity and worked longer working hours compared to day workers without SWD.     

Family studies of hereditary hemochromatosis in Denmark and the Faroe Islands

Summary Pedigree studies were performed based on one Faroese and four Danish probands with overt idiopathic hemochromatosis (IH). The study consisted of HLA typing and determination of biochemical iron status indicators (serum transferrin saturation, serum ferritin). In total, 130 persons were evaluated. The screening identified 6 homozygous (h/h) subjects with preclinical IH, 46 heterozygous (h/n), and 8 normal (n/n) subjects, while 39 subjects were classified as normal or heterozygous (n/h?). One family demonstrated both a homozygous x heterozygous as well as a heterozygous x heterozygous mating. Recombination between the HLA region and IH locus occurred possibly in three subjects in three different families. The significance of detailed screening in families with probands with IH is discussed.     

Genome scans and elusive candidate genes: detecting the variation that matters for speciation

Next‐generation sequencing is providing us with vast amounts of genetic data, yet we are currently struggling in our attempts to make sense of them. In particular, it has proven difficult to link phenotypic divergence and speciation to genome level divergence. In the current issue of Molecular Ecology, Ruegg et al. ( 2014 ) present new empirical results from two closely related bird taxa. They use a promising approach combining genome scan and candidate gene analysis. Their results suggest that we may have been looking in vain for candidate speciation genes by focusing only on genes found within genomic islands of divergence. This is because genes important in divergence and speciation may not be detected by genome scans and because features of the genomic architecture per se may have a large effect on the pattern of genome divergence.