| Records |
| Author |
Abbruzzetti, S.; Crema, E.; Masino, L.; Vecli, A.; Viappiani, C.; Small, J.R.; Libertini, L.J.; Small, E.W. |
| Title |
Fast events in protein folding: structural volume changes accompanying the early events in the N-->I transition of apomyoglobin induced by ultrafast pH jump |
Type |
Journal Article |
| Year |
2000 |
Publication |
Biophysical Journal |
Abbreviated Journal |
Biophys J |
| Volume |
78 |
Issue |
1 |
Pages |
405-415 |
| Keywords |
Animals; Apoproteins/*chemistry; Horses; *Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; Protein Conformation; *Protein Folding; Protein Structure, Secondary; Spectrometry, Fluorescence |
Abstract  |
Ultrafast, laser-induced pH jump with time-resolved photoacoustic detection has been used to investigate the early protonation steps leading to the formation of the compact acid intermediate (I) of apomyoglobin (ApoMb). When ApoMb is in its native state (N) at pH 7.0, rapid acidification induced by a laser pulse leads to two parallel protonation processes. One reaction can be attributed to the binding of protons to the imidazole rings of His24 and His119. Reaction with imidazole leads to an unusually large contraction of -82 +/- 3 ml/mol, an enthalpy change of 8 +/- 1 kcal/mol, and an apparent bimolecular rate constant of (0.77 +/- 0.03) x 10(10) M(-1) s(-1). Our experiments evidence a rate-limiting step for this process at high ApoMb concentrations, characterized by a value of (0. 60 +/- 0.07) x 10(6) s(-1). The second protonation reaction at pH 7. 0 can be attributed to neutralization of carboxylate groups and is accompanied by an apparent expansion of 3.4 +/- 0.2 ml/mol, occurring with an apparent bimolecular rate constant of (1.25 +/- 0.02) x 10(11) M(-1) s(-1), and a reaction enthalpy of about 2 kcal/mol. The activation energy for the processes associated with the protonation of His24 and His119 is 16.2 +/- 0.9 kcal/mol, whereas that for the neutralization of carboxylates is 9.2 +/- 0.9 kcal/mol. At pH 4.5 ApoMb is in a partially unfolded state (I) and rapid acidification experiments evidence only the process assigned to carboxylate protonation. The unusually large contraction and the high energetic barrier observed at pH 7.0 for the protonation of the His residues suggests that the formation of the compact acid intermediate involves a rate-limiting step after protonation. |
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Dipartimento di Fisica, Universita di Parma, 43100 Parma, Italia |
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0006-3495 |
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PMID:10620304 |
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no |
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Equine Behaviour @ team @ |
Serial |
3792 |
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| Author |
Drummond, H.; Canales, C. |
| Title |
Dominance between booby nestlings involves winner and loser effects |
Type |
Journal Article |
| Year |
1998 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
55 |
Issue |
6 |
Pages |
1669-1676 |
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| Abstract |
Two-chick broods of the blue-footed booby,Sula nebouxii, ordinarily exhibit stable dominance-subordinance, with the senior (first-hatched) chick habitually aggressive and the junior one habitually submissive (Nelson 1978,The Sulidae: Gannets and Boobies. London: Oxford University Press). But are both the subordinate and the dominant chick affected in their agonistic tendencies by early social experience? To answer this, we permanently paired subordinate and dominant chicks, 2-3 weeks old, with singletons (chicks lacking experience with a nestmate) by cross-fostering. During the first 4 h after pairing, subordinate chicks were seven times less aggressive than singletons and twice as likely to be submissive; dominant chicks were six times as aggressive as singletons. Although most subordinates consistently lost agonistic encounters during the first 10 days after pairing, the proportion of dominants that won decreased progressively until, by day 6, only about half of dominant chicks were winning. Early social experience has a strong but reversable training effect on both subordinates and dominants. Training as a subordinate showed more persistent effects than training as a dominant, possibly in part because our testing situation perpetuated subordinate training and counteracted dominant training. |
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refbase @ user @ |
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861 |
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| Author |
Ray, E.D.; Heyes, C.M. |
| Title |
Do rats in a two-action test encode movement egocentrically or allocentrically? |
Type |
Journal Article |
| Year |
2002 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
5 |
Issue |
4 |
Pages |
245-252 |
| Keywords |
Animals; *Behavior, Animal; *Discrimination Learning; *Imitative Behavior; Male; Random Allocation; Rats/physiology/*psychology; Smell |
| Abstract |
Two-action tests of imitation compare groups that observe topographically different responses to a common manipulandum. The general aim of the two experiments reported here was to find a demonstrator-consistent responding effect in a procedure that could be elaborated to investigate aspects of what was learned about the demonstrated lever response. Experiment 1 was a pilot study with rats of a variant of the two-action method of investigating social learning about observed responses. Groups of observer rats ( Rattus norvegicus) saw a demonstrator push a lever up or down for a food reward. When these observers were subsequently given access to the lever and rewarded for responses in both directions, their directional preferences were compared with two 'screen control' groups that were unable to see their demonstrators' behaviour. Demonstrator-consistent responding was found to be restricted to observers that were able to see demonstrator performance, suggesting that scent cues alone were insufficient to cue a preference for the demonstrators' response direction and thereby that the rats learned by observation about body movements (imitation) or lever movement (emulation). Experiment 2 assessed responding on two levers, one that had been manipulated by the demonstrator, and a second, transposed lever positioned some distance away. Demonstrator-consistent responding was abolished when actions were observed and performed in different parts of the apparatus, suggesting that observed movement was encoded allocentrically with respect to the apparatus rather than egocentrically with respect to the actor's body. With particular reference to the influence of scent cues, the results are discussed in relation to the strengths and weaknesses of this and other varieties of the two-action procedure as tests of imitation in animals and human infants. |
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Department of Psychology, University College London, London WC1E 6BT, UK. e.ray@ucl.ac.uk |
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1435-9448 |
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PMID:12461602 |
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no |
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Equine Behaviour @ team @ |
Serial |
2588 |
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Rubin, L.; Oppegard, C.; Hindz, H.F. |
| Title |
The effect of varying the temporal distribution of conditioning trials on equine learning behavior |
Type |
Journal Article |
| Year |
1980 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
| Volume |
50 |
Issue |
6 |
Pages |
1184-1187 |
| Keywords |
Animals; Conditioning (Psychology); *Horses; *Learning |
| Abstract |
Two experiments were conducted to study the effect of varying the temporal distrbution of conditioning sessions on equine learning behavior. In the first experiment, 15 ponies were trained to clear a small hurdle in response to a buzzer in order to avoid a mild electric shock. Three treatments were used. One group received 10 learning trials daily, seven times a week; one group was trained in the same fashion two times a week and one group was trained once a week. The animals conditioned only once a week achieved a high level of performance in significantly fewer sessions than the ones conditioned seven times a week, although elapsed time from start of training to completion was two to three times greater for the former group. The twice-a-week group learned at an intermediate rate. In the second experiment, the ponies were rearranged into three new groups. They were taught to move backward a specific distance in response to a visual cue in order to avoid an electric shock. Again, one group was trained seven times a week, one group was trained two times and one group was trained once a week. As in the first experiment, the animals trained once a week achieved the learning criteria in significantly fewer sessions than those trained seven times a week, but, as in trial 1, elapsed time from start to finish was greater for them. The two times-a-week group learned at a rate in-between the rates of the other two groups. |
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0021-8812 |
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| Notes |
PMID:7400060 |
Approved |
no |
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Equine Behaviour @ team @ |
Serial |
3558 |
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| Author |
Fiset, S.; Beaulieu, C.; Landry, F. |
| Title |
Duration of dogs' (Canis familiaris) working memory in search for disappearing objects |
Type |
Journal Article |
| Year |
2003 |
Publication |
Animal Cognition |
Abbreviated Journal |
Anim. Cogn. |
| Volume |
6 |
Issue |
1 |
Pages |
1-10 |
| Keywords |
Animals; Dogs/*psychology; *Exploratory Behavior; Female; Male; *Memory; Visual Perception |
| Abstract |
Two experiments explored the duration of dogs' working memory in an object permanence task: a delay was introduced between the disappearance of a moving object behind a box and the beginning of the search by the animal. In experiment 1, the dogs were tested with retention intervals of 0, 10, 30, and 60 s. Results revealed that the dogs' accuracy declined as a function of the length of the retention interval but remained above chance for each retention interval. In experiment 2, with new subjects, longer retention intervals (0, 30, 60, 120, and 240 s) were presented to the dogs. Results replicated findings from experiment 1 and revealed that the dogs' accuracy remained higher than chance level with delays up to 240 s. In both experiments, the analysis of errors also showed that the dogs searched as a function of the proximity of the target box and were not subject to intertrial proactive interference. In the discussion, we explore different alternatives to explain why dogs' search behaviour for hidden objects decreased as a function of the retention intervals. |
| Address |
Secteur Sciences Humaines, Universite de Moncton, Campus d'Edmundston, E3V 2S8, Edmundston, New Brunswick, Canada. sfiset@umce.ca |
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1435-9448 |
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PMID:12658530 |
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no |
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Equine Behaviour @ team @ |
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2586 |
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| Author |
Connor, R.C.; Mann, J.; Tyack, P.L.; Whitehead, H. |
| Title |
Social evolution in toothed whales |
Type |
Journal Article |
| Year |
1998 |
Publication |
Trends in Ecology & Evolution |
Abbreviated Journal |
Trends. Ecol. Evol |
| Volume |
13 |
Issue |
6 |
Pages |
228-232 |
| Keywords |
odontocetes; toothed whales; social evolution; communication; bottlenose dolphins; sperm whales; long-term studies; foraging |
| Abstract |
Two contrasting results emerge from comparisons of the social systems of several odontocetes with terrestrial mammals. Researchers have identified remarkable convergence in prominent features of the social systems of odontocetes such as the sperm whale and bottlenose dolphin with a few well-known terrestrial mammals such as the elephant and chimpanzee. In contrast, studies on killer whales and Baird's beaked whale reveal novel social solutions to aquatic living. The combination of convergent and novel features in odontocete social systems promise a more general understanding of the ecological determinants of social systems in both terrestrial and aquatic habitats, as well as the relationship between relative brain size and social evolution. |
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0169-5347 |
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no |
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Equine Behaviour @ team @ |
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4789 |
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Mal, M. E.; McCall, C. A.; Cummins, K. A.; Newland, M. C. |
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Influence of preweaning handling methods on post-weaning learning ability and manageability of foals. |
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Journal Article |
| Year |
1994 |
Publication |
Applied Animal Behaviour Science |
Abbreviated Journal |
Appl. Anim. Behav. Sci. |
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40 |
Issue |
3-4 |
Pages |
187-195 |
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Twenty-three foals were used to determine if different amounts of handling between birth and weaning affected their later learning ability and manageability. Foals were assigned to one of three treatments: non-handled (NH) foals were not handled except for necessary maintenance procedures; intermediately handled (IH) foals were handled daily in two 10-min sessions for 7 days after birth and then not handled except for necessary maintenance procedures; extensively handled (EH) foals were handled daily for 7 days as were IH foals and then handled for 10 min once weekly until weaning. Foals were weaned at 120 +/- 10 days of age. On days 1, 3, and 15 after weaning, foals were subjected to a one-trial learning test. The learning test consisted of placing the foal in a familiar pen with an 1.5 X .6-m apparatus containing 40 15 X 15-cm compartments. Number of visits to the apparatus and compartment visited were recorded for 5 min. A small amount of concentrate feed then was placed in a target compartment, and visits were recorded for an additional 5 min. On day 16 after weaning, foals were subjected to a manageability test in which flight distance from an unfamiliar handler and reaction to a novel stimulus were recorded. Split-plot analysis of variance revealed no treatment differences in performance on the learning test (P > .05). Foal performance on the test was greater on day 15 than on day 1 or day 3 (P < .01). Analysis of variance indicated handling treatment had no effect (P > .05) on foal performance during the manageability test. Results indicate that this preweaning handling regimen has no effect on foal learning ability or manageability as measured by these procedures. |
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no |
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Equine Behaviour @ team @ |
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3674 |
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| Author |
Fiske, J.C.; Potter, G.D. |
| Title |
Discrimination reversal learning in yearling horses |
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Journal Article |
| Year |
1979 |
Publication |
J. Anim. Sci. |
Abbreviated Journal |
J. Anim. Sci. |
| Volume |
49 |
Issue |
2 |
Pages |
583-588 |
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| Abstract |
Twenty-six yearling horses were tested on a serial reversal learning discrimination combining spatial and brightness cues. An original discrimination of rewarded or nonrewarded stimuli was made followed by 20 daily reversals for position/brightness discrimination. Learning criteria were defined as 11 out of 12 correct, with the last eight responses all correct. Each horse was allowed 30 trials per discrimination to achieve criteria. Mean errors (ME) and mean trials (MT) required to achieve criteria were computed for each horse. A relative learning ability index (LAI) was calculated by the formula 1000/MT/ME. A daily emotionality score, based on a scale of one (tranquil) to six (very excitable) was assigned each horse each day after testing and a mean computed for each horse. A single subjective trainability score, based on a scale of one (difficult to train) to six (easy to train) was obtained for each horse from an independent trainer. Linear regression analyses for all 26 horses revealed a reduction in MT and ME (P<.01) over the 21-day test period indicating evidence of learning to learn. Differences (P<.05) were evident between sexes for MT and ME. Significant correlations between trainability scores and learning ability indices MT, ME, and LAI were evident for colts and geldings but not for fillies. Pooled data showed significant correlations between ME and trainability. There was a negative correlation (P<.05) between emotionality and trainability scores for all 26 horses, although the filly group did not exhibit significant correlation between these parameters. |
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Cited By (since 1996): 31; Export Date: 24 October 2008 |
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Admin @ knut @ |
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4583 |
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Heird, J.C.; Lennon, A.M.; Bell, R.W. |
| Title |
Effects of early experience on the learning ability of yearling horses |
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Journal Article |
| Year |
1981 |
Publication |
Journal of Animal Science |
Abbreviated Journal |
J. Anim Sci. |
| Volume |
53 |
Issue |
5 |
Pages |
1204-1209 |
| Keywords |
Animals; Conditioning (Psychology); Female; *Handling (Psychology); Horses/*physiology; *Learning |
| Abstract |
Twenty-four yearling Quarter Horse fillies were divided into three groups (I) very limited handling, (II) intermediate handling and (III) extensive handling. At about 14 months of age, each horse was preconditioned for 2 weeks and then run in a simple place-learning T-maze test in which it had to locate its feed. Thirty trials were run daily for 20 days, with the location of the feed changed each day. To retire from the maze, a horse had to meet the criterion: 11 correct responses in 12 tries, with the last eight being consecutive. Horses in Group II required the fewest trials to reach criterion. These horses also learned more and had the highest percentage of correct responses (P less than .05). Mean trainability tended to predict learning ability; however, trainability and trials to criterion were not significantly correlated. Mean emotionality scores indicated a tendency for horses in the intermediately handled group to be less emotional than those in Group I or III. Results indicated that horses with an intermediate amount of handling scored higher on an intermediate test of learning. All handled horses scored higher on learning tests than those not handled. |
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0021-8812 |
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PMID:7319966 |
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no |
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Equine Behaviour @ team @ |
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3577 |
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Hamilton, C.R.; Vermeire, B.A. |
| Title |
Complementary hemispheric specialization in monkeys |
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Journal Article |
| Year |
1988 |
Publication |
Science |
Abbreviated Journal |
Science |
| Volume |
242 |
Issue |
4886 |
Pages |
1691-1694 |
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| Abstract |
Twenty-five split-brain monkeys were taught to discriminate two types of visual stimuli that engage lateralized cerebral processing in human subjects. Differential lateralization for the two kinds of discriminations was found; the left hemisphere was better at distinguishing between tilted lines and the right hemisphere was better at discriminating faces. These results indicate that lateralization of cognitive processing appeared in primates independently of language or handedness. In addition, cerebral lateralization in monkeys may provide an appropriate model for studying the biological basis of hemispheric specialization. |
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Equine Behaviour @ team @ |
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5342 |
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