Natural Behavior Patterns Research Articles

Sublethal effects of tributyltin oxide on the dogwhelk Nucella lapillus

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 158:191-204 (1997) - doi:10.3354/meps158191 Sublethal effects of tributyltin oxide on the dogwhelk Nucella lapillus I. M. Davies1,*, M. J. C. Harding1, S. K. Bailey1, A. M. Shanks1, R. Länge2 1Fisheries Research Services Marine Laboratory, PO Box 101, Victoria Road, Aberdeen AB11 9DB, Scotland, UK 2Institute for Experimental Toxicology, Schering AG, D-13342 Berlin, Germany *E-mail: daviesim@marlab.ac.uk The sublethal effects of tributyltin oxide (TBT) at concentrations of 2 to 128 ng l-1 in sea water on imposex development, weight, activity and feeding rate of the adult common dogwhelk Nucella lapillus (L.) were investigated over 12 mo under conditions conforming to the UK Good Laboratory Practice standard. TBT promoted imposex development, with a no-effect concentration of <2 ng l-1 for exposure of 6 mo or more. The degree of imposex did not exceed levels which caused sterility in any treatment group. Low levels of imposex in controls showed seasonal changes in intensity. Seasonal patterns were overridden by 2 ng TBT l-1 or more. The low numbers of mortalities observed were not related to TBT concentration. The activity of dogwhelks (tendency to climb the tank walls) varied seasonally, reflecting natural behaviour patterns of wild populations. TBT exposure had no effect on this activity. The feeding rate (predation on mussels Mytilus edulis) showed marked seasonal variations in all tanks, but there was no correlation with TBT exposure. Exposure to TBT had no effect on the tissue weight of male dogwhelks, but the body weight of females was negatively correlated with TBT after 12 mo exposure. Mean bioconcentration factors (water to tissue of dogwhelks) ranged from 7400 to 25000, and decreased with increasing TBT exposure concentration. It is estimated that the feed mussels accounted for approximately 40% of the TBT accumulated by the dogwhelks. Nucella · Tributyltin · Effects · Imposex Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 158. Publication date: November 17, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Frogs (Anura: Ranidae) Can Learn to Inhibit the Righting Reflex without Electric Shock

Postlarval anurans of the family Ranidae failed to demonstrate learning in common assays such as shuttle boxes that required the subjects to jump to escape from an electric shock. For instance, Rana pipiens and R. clamitans never displayed learned responses such as anticipatory behavior or a decrease in response time towards an electric shock (McGill, 1960; Boice, 1970; Thompson and Boice, 1975). In some cases, frogs died because they did not avoid repeated shocks (McGill, 1960). Ranids might have difficulty in demonstrating learning under these conditions because the normal avoidance response of some species is to remain motionless rather than run away from aversive stimuli (Gregory, 1979; Licht, 1986). Breland and Breland (1972) stressed the importance of knowledge of a species' instinctive patterns, evolutionary history, and ecological niche in order to predict or understand its behavioral patterns in laboratory situations. Therefore, laboratory studies of avoidance learning in ranids must consider the natural behavioral patterns of these species rather than require the subjects to perform responses that run counter to these patterns. Harvey et al. (1976, 1981) exploited the natural behavioral repertoire of ranids by demonstrating that when R. catesbeiana were flipped on their backs they would remain overturned to avoid an electric shock.

A hierarchical organization of blood pressure during natural behaviour in rat and the effects of central catecholamine neurons thereon.

1. Changes in arterial pressure associated with a repertoire of natural behaviour patterns in the rat were examined. 2. A hierarchy of such changes was found. Eating and drinking were associated with higher pressures than grooming and exploration, which in turn were associated with higher pressures than resting. 3. Desynchronized sleep was associated with higher pressures than slow-wave sleep. 4. Lesions of the catecholamine neurons of the A2 region of the medulla did not disrupt the normal hierarchy but resulted in an exaggerated pressor response.

Covergent effects of lordosis-relevant somatosensory and hypothalamic influences on central gray cells in the rat mesencephalon

In female rats anesthetized with urethane, extracellular recordings were made from neurons in the mesencephalic central gray. Their responses to somatosensory stimuli and the hypothalamic electrical stimulation were tested with or without estrogen treatment. Effects of stimuli which potentiate or disrupt the lordosis reflex were examined. Of the 156 cells tested 32.7% were transsynaptically activated from the gigantocellular nucleus of the medulla. Pressure on the skin had excitatory effects on cutaneous-responsive cells, some of which were found to have well-defined receptive fields on the perineum. Noxious stimuli produced either excitation or inhibition. One-third of the cells changed their discharge rate after stimulation of the ventromedial nucleus of the hypothalamus or the medial preoptic region by trains of pulses at 10 Hz. Facilitation prevailed in the responses to the ventromedial hypothalamic stimulation. Convergences of somatosensory and hypothalamic effects were commonly observed; 55.2% of the cells responded to at least two different stimuli. Directions of responses by individual cells to the various somatosensory and hypothalamic stimuli were frequently consistent with their effects on lordosis. In these cells estrogen treatment resulted only in a subtle shift toward excitatory responses. Central gray neurons recorded here, probably short-axoned, may help to integrate hypothalamic outputs with somatosensory influences on natural behavior patterns, including lordosis in the female rat.

Thermoregulatory aspects of behavior in the blue spiny lizard Sceloporus cyanogenys (Sauria, Iguanidae).

Abstract1. The thermal relations of blue spiny lizards, Sceloporus cyanogenys, were studied in laboratory habitats which were designed to allow the expression of a large repertoire of natural behavior patterns. Body temperatures obtained with fast-reading thermometers and by radio telemetry from implanted transmitters were correlated with postures and activities. 2. The morning emergence of lizards was found to be cued by light, often in the absence of immediate thermal reinforcement. 3. Two basking postures which altered a lizard's air and substrate thermal interfaces could be distinguished. The environmental and body temperature correlates of these postures were not appreciably different, and the change from one posture to another could not be interpreted as thermoregulatory. 4. When thermal conditions permitted, basking continued up to the attainment of the maximum voluntary body temperature (38.7 C), and was then followed by perching. 5. The body temperature correlates of perching had a range and mean much like the "normal activity range" of other species of Sceloporus (28.2-38.7 C, X= 35.2). 6. Defecation occurred mostly in the morning towards the end of the basking period, but had a broad thermal range (27.5 to 35.7 C). 7. The range of body temperatures during feeding was broad (25.3-38.5 C), but that of foraging was much narrower (34.3-38.7 C).