147 results match your criteria: "Institute of Evolutionary and Ecological Sciences[Affiliation]"
Physiol Rev
July 1996
Institute of Evolutionary and Ecological Sciences, Animal Physiology, Gorlaeus Laboratories, University of Leiden, The Netherlands.
The most attractive feature of nuclear magnetic resonance spectroscopy (MRS) is the noninvasive and nondestructive measurement of chemical compounds in intact tissues. MRS already has many applications in comparative physiology, usually based on observation of 31P, since levels of phosphorus compounds indicate tissue energy status and are changed during exercise, fatigue, recovery, hypometabolism, anesthesia, hypoxia, hypercapnia, and osmotic and acid stress. Nuclei other than 31P may also be monitored, such as 1H, 13C, 15N, 19F, or 23Na, and applied in biological research.
View Article and Find Full Text PDFNeurosci Lett
May 1996
Institute of Evolutionary and Ecological Sciences, Leiden University, Van der Klaauw Laboratory, The Netherlands.
As part of a study concerning the organization of premotor areas in the medullary reticular formation in birds we used a fluorescent retrograde double labeling technique to localize the premotor neurons of the trigeminal (mV) and supraspinal motor nucleus (SSp). Diamidino Yellow injections in mV and Fast Blue injections in SSp demonstrated that mV and SSp do not share premotor neurons, but the premotor neurons form a mixed population in the ventromedial part of the parvocellular reticular formation.
View Article and Find Full Text PDFJ Morphol
April 1996
Research Group in Ecological Morphology, Institute of Evolutionary and Ecological Sciences, Leiden University, 2300 RA Leiden, The Netherlands.
During suction feeding teleost fish have to start mouth opening prior to other expansion movements of the head such as operculo-suspensorium abduction. The distribution of the input force over the various expansion movements is determined by the position of the hyoid in the expansion apparatus. Based on a three-dimensional (3-D) kinematic model of this apparatus it can be calculated at which positions of the hyoid operculo-suspensorial abduction is precluded.
View Article and Find Full Text PDFBehav Neurosci
December 1995
Section Theoretical Biology, Institute of Evolutionary and Ecological Sciences, Leiden, The Netherlands.
Stressors and different manipulations of the paraventricular nucleus of the hypothalamus (PVH) increase self-grooming in the rat. To assess the effect of these PVH manipulations on the timing of grooming in relation to other ongoing behavior, the authors describe these behavioral responses by a time-structured model. The authors show the following: (a) Behavior in each treatment group can be described by a semi-Markov model.
View Article and Find Full Text PDFMol Phylogenet Evol
December 1995
Institute of Evolutionary and Ecological Sciences, Leiden University, The Netherlands.
An analysis of the ITS1 sequence variation among five species of terrestrial pulmonate snails was performed to decide between two conflicting hypotheses concerning the phylogeny of these anatomically similar gastropods. It turned out that the so-called genus Isabellaria is a polyphyletic entity; the diagnostic, apomorphic structure of its clausilial apparatus, enabling a nearly complete obstruction of the shell aperture with the animal at rest, apparently evolved more than once from ancestors currently classified with the speciose genus Albinaria. The classification based on general shell shape and sculpture, and distributional patterns, turns out to be the natural one.
View Article and Find Full Text PDFBehav Neurosci
October 1995
Theoretical Biological Section, Institute of Evolutionary and Ecological Sciences, Leiden, The Netherlands.
Specific brain manipulations, such as stimulation of the paraventricular nucleus of the hypothalamus (PVH) or injections of neuropeptides, increase self-grooming in the rat. Such manipulations also affect the different movements that constitute grooming. Using models to assess the time structure of these movements, the authors demonstrate that the rules that control the time structure within grooming are different from the ones that control its initiation.
View Article and Find Full Text PDFTrends Ecol Evol
September 1995
Institute of Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300 RA Leiden, The Netherlands.
Theor Appl Genet
August 1995
Institute of Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300, RA Leiden, the Netherlands.
Several techniques of DNA analysis were applied to identify chrysanthemum cultivars. Unrelated cultivars could be distinguished by using RAPDs (random amplified polymorphic DNAs), inter-SSR (simple sequence repeat) PCR (polymerase chain reaction), hybridization-based DNA fingerprinting, as well as RFLPs (restriction fragment length polymorphisms). Cultivars with different flower colours and belonging to one family, i.
View Article and Find Full Text PDFJ Chem Ecol
May 1995
Institute of Evolutionary and Ecological Sciences, Research Group Ecology of Plant-Animal Interactions, P.O. Box 9516, 2300 RA, Leiden, The Netherlands.
In this study we tested whether pyrrolizidine alkaloids (PAs) ofCynoglossum officinale serve as antifeedants against herbivores. Total PA N-oxide extracts of the leaves significantly deterred feeding by generalist herbivores. Specialist herbivores did not discriminate between food with high and low PA levels.
View Article and Find Full Text PDFTrends Ecol Evol
May 1995
Institute of Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300 RA, Leiden, The Netherlands.
Cladistics
March 1995
Theoretical Biology Section, Institute of Evolutionary and Ecological Sciences, Leiden University, The Netherlands.
- Goloboff recently introduced a method of character weighting that can be performed concomitantly with tree reconstruction. The basis for this method is his tree fitness measure F. The behaviour of F is examined for a number of hypothetical and real data sets.
View Article and Find Full Text PDFTrends Ecol Evol
March 1995
Institute of Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300 RA, Leiden, The Netherlands.
Dev Biol
March 1995
Institute of Evolutionary and Ecological Sciences, University of Leiden, The Netherlands.
Eyespot colour patterns decorate the wings of many butterfly species. The eyespot is specified in the early pupal epidermis by signals from a central "focus," and it has been suggested that the focus is the source of a diffusible morphogen gradient. We show that ectopic eyespots can be induced in nonfocal positions throughout the distal, but not the proximal, wing epidermis of Bicyclus anynana by mild epidermal damage inflicted at 12-18 hr (into a 6- to 7-day pupal period).
View Article and Find Full Text PDFOecologia
September 1994
Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, 2300 RA, Leiden, The Netherlands.
The constitutive pyrrolizidine alkaloid (PA) concentration of both shoots and roots differed significantly between 17 selfed families. The broad-sense heritability accounted for 33-43% of the variation in PA levels. Families also differed significantly in the amount and the direction of PA induction in both shoots and roots, 24 h after punching 15 holes in the leaves.
View Article and Find Full Text PDFEvolution
August 1994
Institute of Cell, Animal and Population Biology, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh, EH9 3JT, UK.
We have studied interactions between developmental processes and genetic variation for the eyespot color pattern on the adult dorsal forewing of the nymphalid butterfly, Bicyclus anynana. Truncation selection was applied in both an upward and a downward direction to the size of a single eyespot consisting of rings with wing scales of differing color pigments. High heritabilities resulted in rapid responses to selection yielding divergent lines with very large or very small eyespots.
View Article and Find Full Text PDFEur J Morphol
August 1994
Institute of Evolutionary and Ecological Sciences, Leiden University, The Netherlands.
Reticular premotor neurons of craniocervical muscles in the duck were localized with the retrograde tracer HRP and the anterograde tracer WGA-HRP. In the reticular formation neck premotor neurons were found in the gigantocellular reticular nucleus and in the ventromedial part of the parvocellular reticular nucleus rostral to the obex, and caudal to the obex in the nucleus centralis ventralis of the medulla. Results were compared with premotor areas of jaw muscles.
View Article and Find Full Text PDFEur J Morphol
August 1994
Institute of Evolutionary and Ecological Sciences, Leiden University, The Netherlands.
The trigeminal and facial motor nuclei in the mallard comprise several subnuclei which innervate tongue, jaw and other head muscles. The premotor cells of the subnuclei innervating jaw muscles are distributed in two longitudinal cell columns within the parvocellular reticular formation (RPc). The ventromedial part of RPc contains cells projecting to subnuclei innervating either jaw-closer muscles or jaw-opener muscles.
View Article and Find Full Text PDFEur J Morphol
August 1994
Institute of Evolutionary and Ecological Sciences, Leiden University, The Netherlands.
Two sensorimotor 'feeding' circuits and their descending projections are described in the mallard and compared to those in the pigeon. The tactile/trigeminal circuit consists of a pattern of reciprocal connections of the nucleus basalis with the overlying parts of the frontal neostriatum (Nf) and hyperstriatum ventrale (HV). The dorsal zone of Nf projects to the sensorimotor part of archistriatum, to the paleostriatum augmentatum (PA) and to the lateral lobus parolfactorius.
View Article and Find Full Text PDFEvolution
June 1994
Systematic Zoology Group, Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, NL-2300 RA Leiden, The Netherlands.
The amount of gene flow among local populations partly determines the relative importance of genetic drift and natural selection in the differentiation of such populations. Land snails, because of their limited powers for dispersal, may be particularly likely to show such differentiation. In this study, we directly estimate gene flow in Albinaria corrugata, a sedentary, rock-dwelling gastropod from Crete, by mark-recapture studies.
View Article and Find Full Text PDFTrends Ecol Evol
June 1994
Institute of Evolutionary and Ecological Sciences, University of Leiden, PO Box 9516, 2300 RA Leiden, The Netherlands.
Oecologia
May 1994
Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, 2300 RA, Leiden, The Netherlands.
Costs of pyrrolizidine alkaloid (Pa) production in vegetative ragwort (Senecio jacobaea) were examined under conditions in which plant growth was limited by light, nitrogen and phosphorus. Measurable costs of Pa production were demonstrated under light-limiting conditions. Plants with higher Pa concentrations grew more slowly than those with lower Pa concentration.
View Article and Find Full Text PDFOecologia
September 1993
Institute for Bio-Pharmaceutical Sciences, University of Leiden, P.O. Box 9502, 2300 RA, Leiden, The Netherlands.
In this paper we test three plant species for the inducibility of their alkaloid production. The plants were heavily damaged by cutting off 50% of their leaf surface using a pair of scissors. The cut-off leaf tips were used as controls for possible diurnal fluctuations.
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