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Cheung, C., Akiyama, T. E., Ward, J. M., Nicol, C. J., Feigenbaum, L., Vinson, C., et al. (2004). Diminished hepatocellular proliferation in mice humanized for the nuclear receptor peroxisome proliferator-activated receptor alpha. Cancer Res, 64(11), 3849–3854.
Abstract: Lipid-lowering fibrate drugs function as agonists for the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha). Sustained activation of PPARalpha leads to the development of liver tumors in rats and mice. However, humans appear to be resistant to the induction of peroxisome proliferation and the development of liver cancer by fibrate drugs. The molecular basis of this species difference is not known. To examine the mechanism determining species differences in peroxisome proliferator response between mice and humans, a PPARalpha-humanized mouse line was generated in which the human PPARalpha was expressed in liver under control of the tetracycline responsive regulatory system. The PPARalpha-humanized and wild-type mice responded to treatment with the potent PPARalpha ligand Wy-14643 as revealed by induction of genes encoding peroxisomal and mitochondrial fatty acid metabolizing enzymes and resultant decrease of serum triglycerides. However, surprisingly, only the wild-type mice and not the PPARalpha-humanized mice exhibited hepatocellular proliferation as revealed by elevation of cell cycle control genes, increased incorporation of 5-bromo-2'-deoxyuridine into hepatocyte nuclei, and hepatomegaly. These studies establish that following ligand activation, the PPARalpha-mediated pathways controlling lipid metabolism are independent from those controlling the cell proliferation pathways. These findings also suggest that structural differences between human and mouse PPARalpha are responsible for the differential susceptibility to the development of hepatocarcinomas observed after treatment with fibrates. The PPARalpha-humanized mice should serve as models for use in drug development and human risk assessment and to determine the mechanism of hepatocarcinogenesis of peroxisome proliferators.
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Cheng, K. (2004). K.J. Jeffery (ed) The neurobiology of spatial behaviourOxford University Press, Oxford, 2003. Anim. Cogn., .
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Cheng, K. (2004). K.J. Jeffery (ed) The neurobiology of spatial behaviour. Anim. Cogn., 7(3), 199–200.
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Cheney, D. l., & Seyfarth, R. M. (2004). Social complexity and the information acquired during eavesdropping by primates and other animals. In P. K. McGregor (Ed.), Animal Communication networks. Cambridge, Massachusetts: Cambridge University Press.
Abstract: In many of the studies reviewed in this book, eavesdropping takes the
following form: a subject has the opportunity to monitor, or eavesdrop upon, an
interaction between two other animals,Aand B. The subject then uses the information
obtained through these observations to assess A`s and B`s relative dominance
or attractiveness as a mate (e.g. Mennill et al., 2002; Ch. 2). For example, Oliveira
et al. (1998) found that male fighting fish Betta splendens that had witnessed two
other males involved in an aggressive interaction subsequently responded more
strongly to the loser of that interaction than the winner. Subjects-behaviour could
not have been influenced by any inherent differences between the two males, because
subjects responded equally strongly to the winner and the loser of competitive
interactions they had not observed. Similarly, Peake et al. (2001) presented
male great tits Parus major with the opportunity to monitor an apparent competitive
interaction between two strangers by simulating a singing contest using two
loudspeakers. The relative timing of the singing bouts (as measured by the degree
of overlap between the two songs) provided information about each “contestants”
relative status. Following the singing interaction, one of the “contestants” was
introduced into the male`s territory. Males responded significantly less strongly
to singers that had apparently just “lost” the interaction (see also McGregor &
Dabelsteen, 1996; Naguib et al., 1999; Ch. 2).
What information does an individual acquire when it eavesdrops on others?
In theory, an eavesdropper could acquire information of many different sorts:
about A, about B, about the relationship between A and B, or about the place of
Animal Communication Networks, ed. Peter K. McGregor. Published by Cambridge University Press.
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Cambridge University Press 2005.
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584 D. L. Cheney & R. M. Seyfarth
A`s and B`s relationship in a larger social framework. The exact information acquired
will probably reflect the particular species social structure. For example,
songbirds like great tits live in communities in which six or seven neighbours
surround each territory-holding male. Males appear to benefit from the knowledge
that certain individuals occupy specific areas (e.g. Brooks & Falls, 1975), that
competitive interactions between two different neighbours have particular outcomes,
and that these outcomes are stable over time. We would, therefore, expect
an eavesdropping great tit not only to learn that neighbour A was dominant to
neighbour B, for example, but also to form the expectation that A was likely to
defeat B in all future encounters. More speculatively, because the outcome of territorial
interactions are often site specific (reviewed by Bradbury & Vehrencamp,
1998), we would expect eavesdropping tits to learn further that A dominates B
in some areas but B dominates A in others. In contrast, the information gained
from monitoring neighbours interactions would unlikely be sufficient to allow
the eavesdropper to rank all of its neighbours in a linear dominance hierarchy,
because not all neighbouring males would come into contact with one another.
Such information would be difficult if not impossible to acquire; it might also be
of little functional value.
In contrast, species that live in large, permanent social groups have a much
greater opportunity to monitor the social interactions of many different individuals
simultaneously. Monkey species such as baboons Papio cynocephalus, for
example, typically live in groups of 80 or more individuals, which include several
matrilineal families arranged in a stable, linear dominance rank order (Silk et al.,
1999). Offspring assume ranks similar to those of their mothers, and females maintain
close bonds with their matrilineal kin throughout their lives. Cutting across
these stable long-term relationships based on rank and kinship are more transient
bonds: for example, the temporary associations formed between unrelated
females whose infants are of similar ages, and the “friendships” formed between
adult males and lactating females as an apparent adaptation against infanticide
(Palombit et al., 1997, 2001). In order to compete successfully within such groups, it
would seem advantageous for individuals to recognize who outranks whom, who
is closely bonded to whom, and who is likely to be allied to whom (Harcourt, 1988,
1992; Cheney & Seyfarth, 1990; see below). The ability to adopt a third party`s perspective
and discriminate among the social relationships that exist among others
would seem to be of great selective benefit.
In this chapter, we review evidence for eavesdropping in selected primate
species and we consider what sort of information is acquired when one individual
observes or listens in on the interactions of others. We then compare eavesdropping
by primates with eavesdropping in other animal species, focusing on both
potential differences and directions for further research
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Chappell, J., & Kacelnik, A. (2004). Selection of tool diameter by New Caledonian crows Corvus moneduloides. Anim. Cogn., 7(2), 121–127.
Abstract: One important element of complex and flexible tool use, particularly where tool manufacture is involved, is the ability to select or manufacture appropriate tools anticipating the needs of any given task-an ability that has been rarely tested in non-primates. We examine aspects of this ability in New Caledonian crows-a species known to be extraordinary tool users and manufacturers. In a 2002 study, Chappell and Kacelnik showed that these crows were able to select a tool of the appropriate length for a task among a set of different lengths, and in 2002, Weir, Chappell and Kacelnik showed that New Caledonian crows were able to shape unfamiliar materials to create a usable tool for a specific task. Here we examine their handling of tool diameter. In experiment 1, we show that when facing three loose sticks that were usable as tools, they preferred the thinnest one. When the three sticks were presented so that one was loose and the other two in a bundle, they only disassembled the bundle when their preferred tool was tied. In experiment 2, we show that they manufacture, and modify during use, a tool of a suitable diameter from a tree branch, according to the diameter of the hole through which the tool will have to be inserted. These results add to the developing picture of New Caledonian crows as sophisticated tool users and manufacturers, having an advanced level of folk physics.
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Chappell J, & Kacelnik A. (2004). Selection of tool diameter by New Caledonian crows. Anim. Cogn., 7, 121.
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Cerutti, D. T., & Staddon, J. E. R. (2004). Immediacy versus anticipated delay in the time-left experiment: a test of the cognitive hypothesis. J Exp Psychol Anim Behav Process, 30(1), 45–57.
Abstract: In the time-left experiment (J. Gibbon & R. M. Church, 1981), animals are said to compare an expectation of a fixed delay to food, for one choice, with a decreasing delay expectation for the other, mentally representing both upcoming time to food and the difference between current time and upcoming time (the cognitive hypothesis). The results of 2 experiments support a simpler view: that animals choose according to the immediacies of reinforcement for each response at a time signaled by available time markers (the temporal control hypothesis). It is not necessary to assume that animals can either represent or subtract representations of times to food to explain the results of the time-left experiment.
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Cassiat, G., Pourcelot, P., Tavernier, L., Geiger, D., Denoix, J. M., & Degueurce, D. (2004). Influence of individual competition level on back kinematics of horses jumping a vertical fence. Equine Vet J, 36(8), 748–753.
Abstract: REASONS FOR PERFORMING STUDY: The costs and investments required for the purchase and training of showjumpers justify the need to find selection means for jumping horses. Use of objective kinematic criteria correlated to jumping ability could be helpful for this assessment. OBJECTIVES: To compare back kinematics between 2 groups of horses of different competition levels (Group 1, competing at high level; Group 2 competing at low level) while free jumping over a 1 m vertical fence. METHODS: Three-dimensional recordings were performed using 2 panning cameras. Kinematic parameters of the withers and tuber sacrale (vertical displacement, vertical and horizontal velocities), backline inclination and flexion-extension motion of the 3 main dorsal segments (thoracic, thoracolumbar and lumbosacral) were analysed. RESULTS: Group 2 horses had a lower displacement of their withers and tuber sacrale from the end of the last approach stride until the first departure stride (P<0.05). As a result, they increased the flexion of their thoracolumbar and lumbosacral junctions during the hindlimb swing phase before take-off (P<0.05). However, withers and tuber sacrale velocities were slightly modified. Group 1 horses pitched their backline less forward during the forelimb stance phase before take-off and straightened it more after landing (P<0.05), probably indicating a more efficient strutting action of their forelimbs. CONCLUSIONS AND POTENTIAL RELEVANCE: Because significant differences in back motion were found between good and poor jumpers when jumping a 1 m high fence, criteria based on certain back kinematics can be developed that may help in the selection of talented showjumpers.
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Caro, T. M., Graham, C. M., Stoner, C. J., & Vargas, J. K. (2004). Adaptive significance of antipredator behaviour in artiodactyls. Anim. Behav., 67(2), 205–228.
Abstract: We used comparative data to test functional hypotheses for 17 antipredator behaviour patterns in artiodactyls. We examined the literature for hypotheses about auditory and visual signals, defensive behaviour and group-related antipredator behaviour in this taxon and derived a series of predictions for each hypothesis. Next, we documented occurrences of these behaviour patterns and morphological, ecological and behavioural variables for 200 species and coded them in binary format. We then pitted presence of an antipredator behaviour against presence of an independent variable for cervids, bovids and all artiodactyls together using nonparametric tests. Finally, we reanalysed the data using Maddison's (1990, Evolution, 44, 539-557) concentrated-changes tests and a consensus molecular and taxonomic phylogeny. We found evidence that snorting is both a warning signal to conspecifics and a pursuit-deterrent signal, lack of evidence that whistling alerts conspecifics and indications that foot stamping is a visual signal to warn group members. Evidence suggested that tail flagging was a signal to both conspecifics and predators, that bounding, leaping and stotting were used both as a signal and to clear obstacles and that prancing functioned similarly to foot stamping. Analyses of tail flicking, zigzagging and tacking were equivocal. We confirmed that inspection occurs in large groups, freezing enhances crypticity, and species seeking refuge in cliffs tend to be small. Entering water and attacks on predators had few correlates. Finally, group living, a putative antipredator adaptation, was associated with large body size and species living in open habitats, confirming Jarman's (1974, Behaviour, 48, 215-267) classic hypothesis. Bunching and group attack apparently deter predators. Despite limitations, comparative and systematic analyses can bolster adaptive hypotheses and raise new functional explanations for antipredator behaviour patterns in general.
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Cameron, E. Z. (2004). Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism. Proc Biol Sci, 271(1549), 1723–1728.
Abstract: Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios.
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