19 research outputs found
Sex Differences in Social Interaction Behavior Following Social Defeat Stress in the Monogamous California Mouse (Peromyscus californicus)
Stressful life experiences are known to be a precipitating factor for many mental disorders. The social defeat model induces behavioral responses in rodents (e.g. reduced social interaction) that are similar to behavioral patterns associated with mood disorders. The model has contributed to the discovery of novel mechanisms regulating behavioral responses to stress, but its utility has been largely limited to males. This is disadvantageous because most mood disorders have a higher incidence in women versus men. Male and female California mice (Peromyscus californicus) aggressively defend territories, which allowed us to observe the effects of social defeat in both sexes. In two experiments, mice were exposed to three social defeat or control episodes. Mice were then behaviorally phenotyped, and indirect markers of brain activity and corticosterone responses to a novel social stimulus were assessed. Sex differences in behavioral responses to social stress were long lasting (4 wks). Social defeat reduced social interaction responses in females but not males. In females, social defeat induced an increase in the number of phosphorylated CREB positive cells in the nucleus accumbens shell after exposure to a novel social stimulus. This effect of defeat was not observed in males. The effects of defeat in females were limited to social contexts, as there were no differences in exploratory behavior in the open field or light-dark box test. These data suggest that California mice could be a useful model for studying sex differences in behavioral responses to stress, particularly in neurobiological mechanisms that are involved with the regulation of social behavior
Plant vascular development: from early specification to differentiation.
Vascular tissues in plants are crucial to provide physical support and to transport water, sugars and hormones and other small signalling molecules throughout the plant. Recent genetic and molecular studies have identified interconnections among some of the major signalling networks that regulate plant vascular development. Using Arabidopsis thaliana as a model system, these studies enable the description of vascular development from the earliest tissue specification events during embryogenesis to the differentiation of phloem and xylem tissues. Moreover, we propose a model for how oriented cell divisions give rise to a three-dimensional vascular bundle within the root meristem
The Phytoene synthase gene family of apple (Malus x domestica) and its role in controlling fruit carotenoid content
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Search for meteoritic GEMS I: Comparison of amorphous silicates in Paris and Acfer 094 chondrite matrices and in anhydrous chondritic interplanetary dust particles
Amorphous silicates in meteoritic samples are significant as potential surviving interstellar dust from the formation of the Solar System. Amorphous silicate-rich grains called GEMS, glass with embedded metal and sulfides, are abundant in anhydrous interplanetary dust particles and some ultracarbonaceous Antarctic micrometeorites that have high presolar grain abundances. Some GEMS within these objects have been confirmed to be presolar. GEMS-like material, consisting of amorphous silicate with opaque inclusions, has been identified in the matrices of some primitive meteorites. We use specialized thin specimen preparation and transmission electron microscopy methods to compare the GEMS-like material in Paris (CM) and Acfer 094 (ungrouped) chondrites with GEMS in anhydrous, chondritic interplanetary dust particles. Specifically, we compared the amorphous silicate morphology, degree of partial ordering, elemental composition and dominant iron oxidation state. We find that the amorphous silicates in the GEMS-like materials in Paris and Acfer 094 show incipient ordering and are Fe-rich and highly oxidized, while those in GEMS are fully amorphous, Fe-poor, and anhydrous. From examination of various formation routes for the amorphous silicates, we conclude that the GEMS-like material in Paris and Acfer 094 is not GEMS and that it is unlikely that GEMS-like material accreted as primary amorphous material that retained its original amorphous structure since accretion. We also conclude that the presence of GEMS-like amorphous silicates in chondrite matrix is not a reliable indicator for high degrees of primitivity or pristinity since even mild, complex alteration processes may significantly alter silicate structure. Finally, we propose searches for presolar amorphous silicates in chondrite matrix samples that have been precharacterized by transmission electron microscopy methods to enable direct comparisons of presolar amorphous silicate abundances
Legacy effects of short-term intentional weight loss on total body and thigh composition in overweight and obese older adults
The Phytoene synthase gene family of apple (Malus x domestica) and its role in controlling fruit carotenoid content
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