T-maze spontaneous alternation rate is decreased in S100 beta transgenic mice

S100 beta, a calcium-binding brain specific protein, may affect both brain development and hippocampal long-term potentiation. S100 beta levels are elevated in Down syndrome (DS), and the gene for S100 beta is located on chromosome 21, which is duplicated in DS. To test the hypothesis that, elevated levels of S100 beta cause behavioral alterations in a mammalian system, 3 transgenic mouse lines with multiple copies of the human gene for S100 beta were derived and behaviorally tested. The spontaneous alteration behavior of transgenic and normal littermate mice were compared in a T maze during a 15-trial test. The overall alteration rate was found to be significantly decreased in the transgenic mice compared with their normal littermates. The S100 beta transgenic mouse model offers one of the first opportunities to investigate the relation between overexpression of a human chromosome 21 gene product and abnormal behavior and brain function.

Female specific hyperactivity in S100 beta transgenic mice does not habituate in open-field

S100 beta, a calcium-binding brain specific protein, may affect brain development and long-term potentiation. Its gene maps to a region of chromosome 21 duplicated in Down's Syndrome (DS), and its levels are elevated in DS. To test the hypothesis that elevated S100 beta levels cause brain dysfunction in a mammalian system, transgenic mice carrying multiple copies of the human S100 beta gene have been generated and their locomotory patterns are analyzed in open field situations. Female-specific hyperactivity was observed in 2-month-old and in 12-month-old transgenic mice, which rules out the previous speculation that postmenopausal hormonal changes constitute a necessary factor in this behavioral abnormality. Analysis of temporal patterns of activity showed a profound abnormality in transgenic females: the initially elevated activity quickly habituated in males and in normal females, however, its level remained high in the transgenic females throughout the 9-min recording session. These observations are compatible with the suggestion that hippocampal function is abnormal in the females of S100 beta transgenic mice.

Female transgenic mice carrying multiple copies of the human gene for S100 beta are hyperactive

Down syndrome (DS) (trisomy 21) is the most frequent genetic cause of mental retardation in man. The gene coding for the beta subunit of human S100 protein (S100 beta) has been mapped to chromosome 21. The dimeric form of S100 beta may function as a neurotrophic factor in the CNS and may also influence the establishment of hippocampal long-term potentiation (LTP). To study the behavioral consequences of overexpression of S100 beta in an animal model, we derived four lines of transgenic mice carrying multiple copies of the human S100 beta gene. The human S100 beta gene was expressed in the brain of these mice in a cell-specific and gene-dose-dependent manner. The motor and posture patterns of 16-month-old transgenic mice and their control (non-transgenic) littermates were studied in two tests, open field and bar-crossing, in order to examine novelty induced exploratory activities. Transgenic female mice were significantly hyperactive in both tests in comparison with their female control littermates. These differences were independent of the line of origin of the mice suggesting a causal relationship between the observed hyperactivity and the presence of multiple copies of the integrated human S100 beta gene. In contrast, transgenic males were not hyperactive in comparison with controls. Neither male nor female transgenic mice displayed any coordination defects. We speculate about how an interaction between the effects of elevated S100 beta levels and female specific hormonal changes could have resulted in the observed female restricted hyperactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Learning to find the opponent: an ethological analysis of the behavior of paradise fish (Macropodus opercularis) in intra- and interspecific encounters

In Experiment 1, 15 behavior patterns of male paradise fish (Macropodus opercularis; n = 72) toward a male conspecific, a male of another species, or no stimulus were recorded, both in home and novel situations. In Experiment 2, the same behaviors were recorded in a runway, and the same stimuli were used as reinforcers in the goal box (n = 18). A typical learning curve was seen when the subject found a male paradise fish in the goal box, learning was followed by apparent extinction when another species was found in the goal box, and few signs of learning were seen when the goal box was empty. Performance of the fish in both experiments can be accounted for by a strong aggressive motivation, a less strong but clear general curiosity, and habituation to the experimental procedure. In contrast to recent assertions in the literature, we conclude that aggressive behavior clearly can serve as a reinforcer in an instrumental learning situation.

Inheritance of species-specific behaviors in the paradise fish (Macropodus opercularis): a diallel study

Species-specific elements of the paradise fish's ethogram were recorded in one familiar and three different unfamiliar environments, which were designed to model certain features of this species' natural habitat: (1) a densely vegetated home range, (2) a novel open field, (3) a small novel place, and (4) a small novel place with a predator. The inheritance of the behavioral elements was investigated employing a five-times-replicated diallel cross among three inbred strains. A detailed Hayman analysis of variance and a variance-covariance analysis were performed to uncover the genetic architectures of these phenotypes. Additive genetic effects and/or ambidirectional dominance was found to be characteristic of most species-specific behavioral elements studied, suggesting an evolutionary history of stabilizing selection.

Genotype-environment interaction and the correlation structure of behavioral elements in paradise fish (Macropodus opercularis)

Three inbred strains and all their possible F1 crosses were monitored in one familiar and three unfamiliar situations. Their behavior was described by species-specific elements of the ethogram. Genetic variability was demonstrated both for behavioral elements and for factors extracted by Principal Components Analyses (PCA). We studied how the behavior of genetically different fish changed across situations and examined the interrelations both among variables measured in one situation and between those measured in different ones. Behavioral changes across situations proved to be different for certain strains and crosses, that is, genotype-environment interaction was found. The PCA's carried out for the 4 situations separately yielded unlike factor structures. Another PCA, in which all the variables were included, proved that there was correlation among certain variables measured in different situations. In general, it seems that the corresponding behavioral elements do not always represent the same phene in different situations. We discuss how the genotype-environment interactions can be interpreted, try to define behavioral strategies using the extracted factor structures, and construct a model for the organization of Macropodus behavior.