Water economy in bird nests

Summary Nest humidity ( ) under an incubating bantam hen was measured at ambient ranging from 1.3 to 25.0 mmHg. Weight loss of eggs was recorded in clutches of varying size. Nest and ambient were also measured in wild incubating willow ptarmigan nests in dry and wet habitats.Nest increased linearly with ambient in a way predictable on the assumption that the water vapour conductance ( ) of brood patch skin, plumage and eggs were constant and independent of ambient . Nest was also dependent of clutch size. Egg dehydration was quantitatively predicted from measured values and the laws of diffusion.Our findings confirm earlier conclusions that the adult bird does not actively regulate nest at varying ambient . Birds can presumably achieve appropriate egg dehydration by a strategy combining nest site, nest construction, egg shell conductance and incubation behaviour which meets the requirements of their breeding climate.Abbreviations water vapur pressure - water vapur conductance - water flux     

Determination of growth-limiting nutrients for red species of Oscillatoria and two ‘oligotrophic’ diatoms

Laboratory batch experiments with dilute phytoplankton communities were carried out to determine growth-limiting nutrients and the degree of growth limitation for Asterionella formosa, Hass., Tabellaria fenestrata (Lyngb.) Kütz. and red species of Oscillatoria under specific temperature and light conditions. Water samples from five Norwegian lakes with average epilimnetic total phosphorus concentrations ranging from 5 to 30 µg P per 1 were investigated. Both enrichment and transplant experiments were carried out. In samples from the most oligotrophic lakes (Lake Randsfjorden and Lake Tyrifjorden) phosphorus was found to be the growth-limiting nutrient. In samples from Lake Mjøsa silicate was also growth-limiting for the diatoms, while nitrogen could be limiting for both asterionella and Oscillatoria from Lake Steinsfjorden. Phosphorus was often the only limiting nutrient determined for Oscillatoria in Lake Gjersjøen (the most eutrophic of the lakes). In samples from this lake, however, Asterionella was also growth-limited directly or indirectly as a result of high (pH > 9). This was also found for Asterionella and Tabellaria from lake Mjøsa by means of transplant experiments. Oscillatoria from Lake Gjersjøen could not grow in filtered water from Lake Mjøsa but obtained maximum growth rate after addition of phosphate and chelated iron in combination.     

Multiple Forms of Choline Acetyltransferase from Rat Brain

WE have found that several different forms of choline acetyl-transferase (ChAc) from rat brain can be separated by isoelectric focusing. Such heterogeneity of ChAc is of particular interest in the context of its ultrastructural localization. Subcellular fractionation^1–4 and histochemistry⁵ have shown that the enzyme in rat, in conditions of low ionic strength and pH, adhered to several different membranous structures.     

Starvation survival and body composition in mammals with particular reference toHomo sapiens

A computer model of body mass and composition in relation to gross energy balance is constructed. The model is built using conventional empirical physiological formulae rather than statistical or analytical mathematical techniques. The model is applied to the Minnesota and other experiments and produces as good or better simulations of observed values of changes in body weight than reported for other formulae or models. Alternative physiological mechanisms concerning metabolic adaptions to starvation, changes in time activity budgets and the energy equivalents of weight loss offer equally good simulations of experimental results. The present analysis highlights the survival value of a basal metabolic depression during starvation and indicates an optimal body composition of 10% mobilizable fat for starvation survival for a 70 kg man. Proper quantification of the effects of the physiological mechanisms involved depends on new experimental data, however. Long term continuous monitoring of time activity budgets are a necessary part of such experiments.     

The evolutionary history of the amylase multigene family in Drosophila pseudoobscura

In Drosophila pseudoobscura, the amylase (Amy) multigene family is contained within a series of inversions, or gene arrangements, on the third chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL) inversions are central to the phylogeny of arrangements, and have clusters of other arrangements derived from them. The gene arrangements belonging to each of these three clusters have a characteristic number of Amy genes, ranging from three in ST to two in SC to one in TL. This distribution pattern can reflect a history of either duplications or deletions, although the data available in the past did not permit a decision between these alternatives. We provide unambiguous evidence that three Amy genes were present before the divergence of the ST, SC, and TL arrangements. Thus, the current status of the Amy multigene family is the result of deletions in the TL and SC arrangements, which created three new pseudogenes: TL Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences revealed that, in the SC and ST arrangements, pseudogene evolution has been retarded, most likely due to the homogenization effect of gene conversion. Finally, by determining the original copy number, we have reconstructed the evolutionary history of the Amy multigene family and linked it with the evolution of the central gene arrangements.      

High Velocity Projectiles for Killing Whales. Hunting Trials using 20 mm High Velocity Projectiles for Minke Whales in 1982

Norway was requested by the International Whaling Commission (IWC) to explore the use of high-velocity projectiles to replace cold harpoon as killing device for minke whales (Anon 1980). Tests of suitable high-velocity projectiles for minke whales were therefore initiated in 1982 as part of a wider project with the purpose of studying alternative killing methods to the traditional cold harpoon used in the Norwegian minke whale hunt until 1984 (Øen 1995). The results of the trials have previously been presented in unpublished reports to the IWC (Øen 1982, 1983, 1992).     

High-density algal photobioreactors using light-emitting diodes

Lack of high-density algal photobioreactors (PBR) has been a limitation in exploiting the biotechnological potential of algae. Recent developments of highly efficient light-emitting diodes (LED using gallium aluminum arsenide chips) have made the development of a small LED-based PBR possible. We have calculated theoretical values of gas mass transfer requirements and light-intensity requirement to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. A prototype PBR has been designed based on these calculations. A cell concentration of more than 2 x 10(9) cells/mL (more than 6.6% v%sol;v), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/L culture/h were achieved using on-line ultrafiltration to periodically provide fresh medium. (c) 1994 John Wiley & Sons, Inc.