Selective foraging on woody plant species by the Eurasian beaver (Castor fiber) in Telemark, Norway

Beavers Castor spp. are generalist herbivores, feeding on the bark, shoots and leaves of woody plants, terrestrial herbs and forbs, ferns and aquatic vegetation. As central-place foragers, beavers move out from water to select and cut trees and vegetation, and then transport it back to their refuge. These terrestrial forays are energetically costly; therefore, beavers should concentrate their foraging activity near the central place and increase the degree of selectivity for specific sizes or species of food with increasing distance from the water. The aim of this study was to test the predictions of the central place and the optimal foraging theories for the food selection of the Eurasian beaver Castor fiber , and show the foraging preferences of the focal species in the boreal conifer forest zone of Europe. Foraging intensity by beavers and the abundance of woody species were surveyed in transects positioned randomly at seven beaver territories. In compliance with the central-place foraging theory, the foraging intensity declined with increasing distance from the river. Beavers fed preferentially on willows ( Salix ), rowan ( Sorbus ) and birches ( Betula ), although alders ( Alnus ) dominated their diet. Size selectivity showed similar patterns to previous North American studies, which were also carried out in habitats with predominantly small saplings. The probability of selection of small saplings dropped as distance increased, which is consistent with the predictions of optimal foraging models that larger prey items are more likely to be favoured with increasing provisioning distance.     

Measurement of light within thin plant tissues with fiber optic microprobes

Vogelmann, T. C., Knapp, A. K., McClean, T. M. and Smith, W. K. 1988. Measurement of light within thin plant tissues with fiber optic microprobes. - Physiol. Plant. 72: 623–630.
The measurement of light with fiber optic microprobes has been extended to thin (200–300 μm) plant tissue samples. To test the method, light measurements were made in thin aqueous films and paradermal sections from 10-day-old etiolated Cucurbita pepo L. cv. Fordhook cotyledons. The measurements obtained were highly reproducible. Paradermal sections of spongy mesophyll that were irradiated with collimated light scattered light more effectively than the palisade layer of intact cotyledons. These results demonstrate that different plant tissues have different light scattering characteristics. The successful extension of the fiber optic microprobe technique to thin systems makes it possible to examine the optical properties of different cell layers within leaves and other plant organs.     

Hormonal regulation of cotton ovule and fiber growth: Effects of bromodeoxyuridine,AMO-1618 and p-chlorophenoxyisobutyric acid

The effects of 5-bromo-2-deoxyuridine (BUdR, thymidine analogue), AMO-1618 (2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride), a growth retardant, and p-chlorophenoxyisobutyric acid (PCIB, an antiauxin) on growth (dry weight increase) and fiber development in unfertilized cotton (Gossypium hirsutum L.) ovules grown in vitro have been studied. BUdR (5 M) causes about 70% inhibition of fiber production, with little effect on ovule growth, if applied during the first 6 d of culture in the presence of GA₃ and IAA. AMO-1618, when used with GA₃ alone, causes only a small reduction in both dry weight and fiber production, but when used with IAA alone reduces both fiber production and dry weight, the effect on the latter being predominant. In the presence of both IAA and GA₃, AMO-1618 causes a small decrease in fiber production but a major decrease in dry weight. PCIB completely inhibits fiber growth but has little effect on dry weight, especially when GA₃ is present. These results indicate that GA₃ mainly promotes ovule growth while IAA is largerly responsible for fiber growth.Abbreviations AMO-1618 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride - BUdR 5-bromo-2-deoxyuridine - GA₃ gibberellic acid - IAA indole-3-acetic acid - PCIB p-chlorophenoxyisobutyric acid - TFU total fiber units     

The salting-in hypothesis of post-hypertonic lysis

The phenomenon of slow cooling cryoinjury has remained one of the primary areas of research in cryobiology since the early 1950s when it was first investigated thoroughly. Lovelock demonstrated that cell death from freezing and thawing was mainly due to exposure to hypertonic solutions and the subsequent dilution back to isotonic conditions. He suggested that the cell became permeable to sodium in hypertonic conditions leading to a loading of sodium during the hypertonic exposure, which caused the cell to swell past its elastic limit during resuspension in isotonic media (post-hypertonic lysis). This idea was pursued by Zade-Oppen, Farrant, and others who were able to show that the membrane became leaky to cations in hypertonic media but they could not provide any mechanism that would cause the cell to load up with sodium (other than an exchange of extracellular sodium for intracellular potassium, leaving the cell with the same cation concentration that it started out with). In the absence of such a mechanism, predicting post-hypertonic lysis from osmotic simulations cannot be done.A simplified model is proposed in which the intracellular milieu is composed of both KCl and a proteinaceous component that normally forms many salt bridges between amino acids with fixed charges. When the intracellular salt concentration increases, the proteins are “salted in” to solution (salt bridges are replaced with ionic interactions) thereby decreasing the intracellular cation concentration. Cation channels in the plasma membrane are opened by exposure to a high salt concentration (either inside or outside the membrane) allowing extracellular sodium to take the place of the intracellular potassium that is interacting with anionic groups on the proteins. Dilution of the external medium (which also occurs during melting) causes water to move into the cells, diluting the cytoplasm. The proteins are then “salted out” of solution and release the salt back to free ions in solution. The cell has an excess of intracellular ions and may swell past its elastic limit due to water influx. A simulation engine is developed based on the model and compared to results in the literature for freeze–thaw injury in human red blood cells.     

Real-Time Monitoring of Slow-Wave Sleep by Electroencephalogram Variance

Based on statistical variance as an index of electroencephalogram (EEG) parameters, we monitored slow-wave sleep in both humans and rats in real time and on-line with a widely used personal computer. This EEG variance method may be a useful tool to carry out biological rhythm research, including sleep studies.     

Cotton Biotechnology

Genetically modified (GM) cotton altered for insect and herbicide resistance released into commercial production in 1996 to 1997 now accounts for the lion's share of cotton acreage in the U.S. The rapid increase in transgenic cotton acreage in such a short period of time attests to the overall success of agricultural biotechnology. Grower satisfaction with transgenic cotton is largely due to several significant benefits, such as lower production costs, streamlined yet flexible management, and a reduced impact on the environment. This review article provides an overview of what has been accomplished thus far, as well as what improved germplasm may lurk on the horizon. A critical assessment of the gene delivery systems in cotton and possible targets for improvement is presented. The performance of the first generation of transgenic cotton plants engineered for insect, disease, or herbicide resistance is evaluated from the perspective of the benefits, the limitations that impact field performance, and management strategies. A few traits that hold future promise for increasing fiber productivity, enhancing and/or increasing the novelty of cotton-based products for the consumer, and improving human health and well-being are presented. Above all, cotton biotechnology offers to greatly enhance breeding programs by introducing novel traits that have eluded more traditional plant improvement methods and therefore will likely play an increasingly important role in the genetic improvement of cotton.     

Slow food and the politics of pork fat: Italian food and European identity

This paper explores the emergence of the Slow Food Movement, an international consumer movement dedicated to the protection of ‘endangered foods.’ The history of one of these ‘endangered foods’, lardo di Colonnata, provides the ethnographic window through which I examine Slow Food's cultural politics. The paper seeks to understand the politics of ‘slowness’ within current debates over European identity, critiques of neo-liberal models of rationality, and the significant ideological shift towards market-driven politics in advanced capitalist societies.