A novel transgenic chimaeric mouse system for the rapid functional evaluation of genes encoding secreted proteins

A major challenge of the post-genomic era is the functional characterization of anonymous open reading frames (ORFs) identified by the Human Genome Project. In this context, there is a strong requirement for the development of technologies that enhance our ability to analyze gene functions at the level of the whole organism. Here, we describe a rapid and efficient procedure to generate transgenic chimaeric mice that continuously secrete a foreign protein into the systemic circulation. The transgene units were inserted into the genomic site adjacent to the endogenous immunoglobulin (Ig) κ locus by homologous recombination, using a modified mouse embryonic stem (ES) cell line that exhibits a high frequency of homologous recombination at the Igκ region. The resultant ES clones were injected into embryos derived from a B-cell-deficient host strain, thus producing chimaerism-independent, B-cell-specific transgene expression. This feature of the system eliminates the time-consuming breeding typically implemented in standard transgenic strategies and allows for evaluating the effect of ectopic transgene expression directly in the resulting chimaeric mice. To demonstrate the utility of this system we showed high-level protein expression in the sera and severe phenotypes in human EPO (hEPO) and murine thrombopoietin (mTPO) transgenic chimaeras

P301S Mutant Human Tau Transgenic Mice Manifest Early Symptoms of Human Tauopathies with Dementia and Altered Sensorimotor Gating

Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal tau protein leading to cognitive and/or motor dysfunction. To understand the relationship between tau pathology and behavioral impairments, we comprehensively assessed behavioral abnormalities in a mouse tauopathy model expressing the human P301S mutant tau protein in the early stage of disease to detect its initial neurological manifestations. Behavioral abnormalities, shown by open field test, elevated plus-maze test, hot plate test, Y-maze test, Barnes maze test, Morris water maze test, and/or contextual fear conditioning test, recapitulated the neurological deficits of human tauopathies with dementia. Furthermore, we discovered that prepulse inhibition (PPI), a marker of sensorimotor gating, was enhanced in these animals concomitantly with initial neuropathological changes in associated brain regions. This finding provides evidence that our tauopathy mouse model displays neurofunctional abnormalities in prodromal stages of disease, since enhancement of PPI is characteristic of amnestic mild cognitive impairment, a transitional stage between normal aging and dementia such as Alzheimer's disease (AD), in contrast with attenuated PPI in AD patients. Therefore, assessment of sensorimotor gating could be used to detect the earliest manifestations of tauopathies exemplified by prodromal AD, in which abnormal tau protein may play critical roles in the onset of neuronal dysfunctions

Effects of Population Density on Growth, Behavior and Levels of Biogenic Amines in the Cricket, Gryllus bimaculatus

We examined quantitative changes in biogenic amines in relation to effects of population density on growth and behavior in the cricket Gryllus bimaculatus, which were reared in two different densities, completely isolated solitary and 40 crowded insects. In the crowded animals, the rate of increase in body weight was slow, and also the day of imaginal moult was late, when compared to the isolated ones. Development and growth were thus suppressed in the crowded group. The body color of isolated ones was darker than that of crowded ones. Behavioral tests indicated that the isolated crickets were significantly more aggressive than the crowded ones. The levels of biogenic amines, their precursors and metabolites were examined in the brain, corpora allata, corpora cardiaca and frontal ganglion of isolated and crowded crickets using high-performance liquid chromatography with electrochemical detection. The brains of crowded crickets contained significantly higher amounts of octopamine, dopamine, and 5-hydroxytryptamine (5-HT) than those in the isolated ones. On the contrary, the level of N-acetyldopamine in the isolated crickets was significantly higher than that in the crowded ones. In crowded animals the corpora allata contained significantly higher levels of 5-HT, and the corpora cardiaca contained more octopamine. These results indicate that high population density affects aminergic systems which in turn modulate various biological events, such as development, growth and behavior

The Levels of Biogenic Amines in the Corpora Allata, Corpora Cardiaca and Frontal Ganglion in the Cricket, Gryllus bimaculatus

Secretory activity of the corpora allata (CA) and corpora cardiaca (CC) in the parsintercerebralis complex has been suggested to be controlled by biogenic amines, despite a lack of quantitative information. The situation is similar to the frontal ganglion (FG), a member of the same complex. Hence, the levels of biogenic amines and related substances in these organs were measured in cricket, Gryllus bimaculatus, by high performance liquid chromatography with electrochemical detection. All organs examined contained considerable amounts of major biogenic amines, such as octopamine (OA), dopamine, and 5-hydroxytryptamine (5-HT). They also included epinephrine. The amounts of OA and 5-HT were higher than those of other biogenic amines whose presence was detected in the examined organs. The distributional patterns of biogenic amines were different among the CA, CC and FG, e.g., the highest content of OA in the CC. The presence of precursors and metabolites indicates that biogenic amines are synthesized and metabolized in neuronal elements in the examined organs. It is probable that they are functional and also involved in the neural control of hormone secretion in CA and CC, because their turnover rates estimated from the present analysis are comparable to those in the nervous system