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Author Andersen, N.H.; Norgaard, A.; Jensen, T.J.; Ulstrup, J.
Title Sequential unfolding of the two-domain protein Pseudomonas stutzeri cytochrome c4 Type Journal Article
Year 2002 Publication Journal of Inorganic Biochemistry Abbreviated Journal
Volume 88 Issue 3-4 Pages 316-327
Keywords (up) P. stutzeri cytochrome c4; Sequential unfolding; Di-haem protein; Unfolding
Abstract P. stutzeri cytochrome c4 is a di-haem protein, composed of two globular domains each with His-Met coordinated haem, and a hydrogen bond network between the domains. The domain foldings are highly symmetric but with specific differences including structural differences of ligand coordination, and different spin states of the oxidised haem groups. We have studied unfolding of oxidised P. stutzeri cyt c4 induced thermally and by chemical denaturants. Horse heart cyt c was a reference molecule. Isothermal unfolding induced by guanidinium chloride and acid was followed by Soret, α/β, and 701-nm band absorption, and by far-UV circular dichroism spectroscopy. Multifarious patterns emerge, but the two domains clearly unfold sequentially. One phase, assigned to unfolding of the N-terminal domain, proceeds at guanidinium concentrations up to [approximate]1.0 M. This is followed by two overlapping phases at higher concentrations. The intermediate state maintains Fe-Met coordination, assigned to the C-terminal domain. Interdomain interaction is reflected in decreasing values of the cooperativity parameters. Differential scanning calorimetry shows a single peak, but two peaks appear when guanidinium chloride up to 0.4 M is present. This reflects different chemical action in chemical and thermal unfolding. Acid-induced unfolding kinetics was addressed by pH jumps using diode array stopped-flow techniques. Three kinetic phases in the 701 nm Fe-Met marker band, and four phases in the Soret and α/β bands, spanning 4-1000 ms could be distinguished on pH jumps from 7.5 to the range 2.5-3.5. In this range of time and pH cyt c appears to unfold in no more than two phases. Spectral properties of the kinetic intermediates could be identified. Sequential domain unfolding, formation of high-spin states, and an intermediate state with Fe-Met coordination to a single haem group are features of the unfolding kinetics.
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Call Number refbase @ user @ Serial 3973
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Author King, S.R.B.
Title Home range and habitat use of free-ranging Przewalski horses at Hustai National Park, Mongolia Type Journal Article
Year 2002 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.
Volume 78 Issue 2-4 Pages 103-113
Keywords (up) Przewalski horse; Equus przewalskii; Takhi; Home range; Re-introduction; Habitat use
Abstract Przewalski horses (Equus ferus przewalskii), also known as takhi, were first re-introduced to the wild in Hustai National Park, Mongolia, in 1994. Since then the number of free harems increased to a maximum of seven; there are currently six (October 2000). The size of the home range of each of the harems changed among years and among seasons. The horses tended to settle in a home range close to where they were released although they explored the surrounding area. The use of the habitat within each home range changed through the day, with the horses grazing in the valleys during the morning and evening, and moving to higher places to stand rest and use as a refuge from heat and flies during the middle of the day. Range establishment and area, as well as habitat use are discussed.
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ISSN 0168-1591 ISBN Medium
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Call Number Equine Behaviour @ team @ Serial 4682
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Author Giraldeau, Luc-Alain; Valone, Thomas, J.; Templeton, Jennifer, J.
Title Potential disadvantages of using socially acquired information Type Journal Article
Year 2002 Publication Philosophical Transactions of the Royal Society B: Biological Sciences Abbreviated Journal Phil. Trans. Biol. Sci.
Volume 357 Issue 1427 Pages 1559-1566
Keywords (up) Public Information Informational Cascades Social Learning Sampling
Abstract The acquisition and use of socially acquired information is commonly assumed to be profitable. We challenge this assumption by exploring hypothetical scenarios where the use of such information either provides no benefit or can actually be costly. First, we show that the level of incompatibility between the acquisition of personal and socially acquired information will directly affect the extent to which the use of socially acquired information can be profitable. When these two sources of information cannot be acquired simultaneously, there may be no benefit to socially acquired information. Second, we assume that a solitary individual's behavioural decisions will be based on cues revealed by its own interactions with the environment. However, in many cases, for social animals the only socially acquired information available to individuals is the behavioural actions of others that expose their decisions, rather than the cues on which these decisions were based. We argue that in such a situation the use of socially acquired information can lead to informational cascades that sometimes result in sub-optimal behaviour. From this theory of informational cascades, we predict that when erroneous cascades are costly, individuals should pay attention only to socially generated cues and not behavioural decisions. We suggest three scenarios that might be examples of informational cascades in nature.
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Call Number Equine Behaviour @ team @ Serial 4197
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Author Ligout, S.; Porter, R.H.; Bon, R.
Title Social discrimination in lambs: persistence and scope Type Journal Article
Year 2002 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.
Volume 76 Issue 3 Pages 239-248
Keywords (up) Social discrimination; Social cognition; Persistence of recognition; Lambs
Abstract Social recognition among familiar unrelated lambs was assessed in a series of tests. Lambs and their mothers were housed together in small groups for 1 week (Original groups; O) then reorganized into new groupings (Recent-groups; R) for the remainder of the experiment. During test series 1, lambs that were paired with a familiar O-group partner, from which they had been separated for 5 days, emitted fewer distress bleats than did those tested with an unfamiliar partner. This same effect was not evident when the test was repeated several hours later, indicating that the animals had become habituated to the testing procedures. Two days later, when given the choice between an O- versus a R-partner (test series 2), lambs did not display a preference for either of the stimulus lambs. However, in an additional two-choice test (test series 3) the subject lambs responded discriminatively to a recent familiar partner that was simultaneously present with an unfamiliar lamb. Overall, the results suggest that lambs are capable of developing discriminative relationships with age-mates from different sub-groups, and that such social discrimination persists over a separation period lasting at least several days. It is not clear whether lambs recognize several individual conspecifics per se or discriminate between members of higher order social categories (e.g. familiar versus unfamiliar individuals). Proximal and distal social discrimination may be mediated by different combinations of sensory modalities.
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Call Number Equine Behaviour @ team @ Serial 2906
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Author Barnard, C.J.; Luo, N.
Title Acquisition of dominance status affects maze learning in mice Type Journal Article
Year 2002 Publication Behavioural Processes Abbreviated Journal Behav. Process.
Volume 60 Issue 1 Pages 53-59
Keywords (up) Social status; Learning; Radial maze; Mouse
Abstract Learning is likely to be costly and thus subject to trade-off with other components of life history. An obvious prediction, therefore, is that investment in learning, and thus learning performance, will vary with individual life history strategy and the reproductive value of the learning outcome. We tested this idea in the context of social dominance in male laboratory mice, using a simple radial maze paradigm to compare the ability of high- and low-ranking male mice to track changing food location. We tested animals in randomly selected pairs before and after establishing aggressive rank relationships to distinguish intrinsic differences in learning ability from those attributable to acquiring high or low rank. There was no difference in learning between later dominants and subordinates prior to establishing rank relationships. After pairing, however, dominants showed a significantly greater percentage of correct responses, with the difference being greatest earlier in a sequence of trials. The percentage of correct responses also increased with the amount of aggression initiated during pairing. The results thus appeared to reflect a state-dependent change in learning associated with the aggressive social relationships formed during pairing.
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Call Number Serial 2075
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Author Seaman, S.C.; Davidson, H.P.B.; Waran, N.K.
Title How reliable is temperament assessment in the domestic horse (Equus caballus)? Type Journal Article
Year 2002 Publication Applied Animal Behaviour Science Abbreviated Journal Appl. Anim. Behav. Sci.
Volume 78 Issue 2-4 Pages 175-191
Keywords (up) Temperament assessment; Behavioural tests; Horses; Active and passive copers; Factor analysis
Abstract Differences in behavioural characteristics between individuals of the same species are often described as being due to the temperament of the individuals. These differences can have enormous implications for welfare with some individuals apparently being able to adapt to environmental challenge more easily than others. Such differences have resulted in animals often being described as either `active' copers, which try to escape from or remove an aversive stimulus, or `passive' copers, which show no outward signs of a situation being aversive, thus, appearing to be unaffected. Tests previously developed to assess the temperament of animals have been criticised for several reasons. Behaviour is often recorded and categorised using methods that are not objective and tests are generally carried out once with no consideration of whether or not behavioural responses are consistent over time. This study takes these factors into account. The behaviour of 33 horses was recorded in three types of test--an arena test, response to a person and response to an object. In order to test whether or not responses were consistent over time, the tests were repeated three times with an average of 9 days between trials. Test results were validated using responses from questionnaires completed by the farm team leader. The data were analysed using an initial principal component analysis (PCA) and factor analysis. The horses were found to behave consistently over the three trials in their responses in the arena test. The responses to the person test and the object test were similar to each other; however, these responses were not consistent over trials. The behaviour in the arena test was unable to be used to make a prediction of behaviour in the person and object tests and vice versa. The responses shown by the horses did not enable them to be categorised as either active or passive copers. Behavioural responses in the tests were not predictive of the response to a startle test (water spray), nor could they be used to predict status or response to being reintroduced to the group after testing. There was no relationship between the responses in the tests and the ratings given by the farm team leader. It was concluded that horses vary widely in their responses to artificial behavioural tests, with only the responses to an open-field arena test being consistent over time, and therefore, the only type of test which can indicate some core factor of temperament.
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Call Number refbase @ user @ Serial 520
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