A RhoA-FRET Biosensor Mouse for Intravital Imaging in Normal Tissue Homeostasis and Disease Contexts

The small GTPase RhoA is involved in a variety of fundamental processes in normal tissue. Spatiotemporal control of RhoA is thought to govern mechanosensing, growth, and motility of cells, while its deregulation is associated with disease development. Here, we describe the generation of a RhoA-fluorescence resonance energy transfer (FRET) biosensor mouse and its utility for monitoring real-time activity of RhoA in a variety of native tissues in vivo. We assess changes in RhoA activity during mechanosensing of osteocytes within the bone and during neutrophil migration. We also demonstrate spatiotemporal order of RhoA activity within crypt cells of the small intestine and during different stages of mammary gestation. Subsequently, we reveal co-option of RhoA activity in both invasive breast and pancreatic cancers, and we assess drug targeting in these disease settings, illustrating the potential for utilizing this mouse to study RhoA activity in vivo in real time.

European-American Children's and Adolescents' Evaluations of Interracial Exclusion

No research, to date, has investigated the role of ethnic school composition (and intergroup contact) on European-American youth's use of stereotypes to explain interracial discomfort in the context of peer exclusion. In this study European-American 4th, 7th and 10th grade students (N = 414), attending low and high ethnically diverse public schools (with low and high self-reports of cross-race/ethnic friendships, respectively) evaluated three contexts of interracial exclusion (at lunch time, at a school dance, and at a sleepover). In addition to age and context effects, participants enrolled in high diversity schools were less likely to use stereotypes to explain racial discomfort, more likely to view racial exclusion as wrong, and more likely to estimate that racial exclusion occurs, than were participants enrolled in low diversity schools. These findings have implications for the role of social experience on racial attitudes and judgments about exclusion.

Fairness or stereotypes? Young children's priorities when evaluating group exclusion and inclusion

Seventy-two children (35 4 1/2-year-olds and 37 5 1/2-year-olds), nearly evenly divided by gender, from European American (71%), Asian American (17%), and African American (12%) middle-class backgrounds, were individually interviewed about straightforward exclusion and inclusion for two gender-stereotypic peer-group contexts: activities (doll and truck play) and role-play (teacher and firefighter). All children evaluated straightforward exclusion based on gender (e.g., girls excluding a boy from doll play) as wrong and used moral reasons. Preliminary inclusion decisions in the activity contexts (choosing a boy or a girl to join the group) were based on stereotypic expectations, particularly for younger children. Given the opportunity to weigh alternative considerations, however, all children gave priority to fairness over stereotypic expectations in both multifaceted inclusion peer-group contexts.

Fairness or stereotypes? Young children's priorities when evaluating group exclusion and inclusion

Seventy-two children (35 4 1/2-year-olds and 37 5 1/2-year-olds), nearly evenly divided by gender, from European American (71%), Asian American (17%), and African American (12%) middle-class backgrounds, were individually interviewed about straightforward exclusion and inclusion for two gender-stereotypic peer-group contexts: activities (doll and truck play) and role-play (teacher and firefighter). All children evaluated straightforward exclusion based on gender (e.g., girls excluding a boy from doll play) as wrong and used moral reasons. Preliminary inclusion decisions in the activity contexts (choosing a boy or a girl to join the group) were based on stereotypic expectations, particularly for younger children. Given the opportunity to weigh alternative considerations, however, all children gave priority to fairness over stereotypic expectations in both multifaceted inclusion peer-group contexts.

Children's social reasoning about inclusion and exclusion in gender and race peer group contexts

This study investigated whether children's and adolescents' judgments about exclusion of peers from peer group activities on the basis of their gender and race would differ by both age level and the context in which the exclusion occurred. Individual interviews about exclusion in several different contexts were conducted with 130 middle-class, European American children and adolescents. Younger children were expected to reject exclusion, by using judgments based on moral reasoning, regardless of the potential cost to group functioning, whereas older children were expected to condone exclusion on the basis of group membership in cases in which the inclusion of these children might interrupt effective group functioning. On measures of judgments, justifications for those judgments, and ratings of the appropriateness of exclusion, the vast majority of children used moral reasoning and rejected exclusion in contexts in which only the presence of a stereotype justified it. As expected, however, older children (13 years) were more likely to allow exclusion than younger children (7 and 10 years) when group functioning was threatened, and they justified this exclusion by using appeals to effective group functioning.

Young children's evaluations of exclusion in gender-stereotypic peer contexts

This study investigated how 50 preschool children (25 girls, 25 boys) evaluated the appropriateness of excluding boys and girls from two types of activities (doll play, truck play) and two types of future roles (playing a teacher, playing a firefighter) across different exclusion contexts. Children judged straight-forward exclusion from activities on the basis of gender as wrong, even if the child's gender was stereotypical of the activity. Furthermore, they justified these decisions on the basis of moral reasons, such as equality and unfairness. Children used a mixture of moral and social conventional reasoning (including stereotypes), however, to evaluate multifaceted situations that called for judgments about both inclusion and exclusion and that included information about the children's past experience with the activity.

The catalytic subunit of telomerase is expressed in developing brain neurons and serves a cell survival-promoting function

Telomerase, a specialized reverse transcriptase (RT) linked to cell immortalization and cancer, has been thought not to be expressed in postmitotic cells. We now report that telomerase activity and its essential catalytic subunit, telomerase reverse transcriptase (TERT), are expressed in neurons in the brains of rodents during embryonic and early postnatal development, and are subsequently downregulated. Suppression of TERT expression in cultured embryonic hippocampal neurons increases their vulnerability to apoptosis and excitotoxicity. Overexpression of TERT in PC12 cells suppresses apoptosis induced by trophic factor withdrawal. TERT exerts its anti-apoptotic action at an early stage of the cell death process prior to mitochondrial dysfunction and caspase activation. TERT may serve a neuron survival-promoting function in the developing brain, and downregulation of TERT in the adult brain may contribute to increased neuronal vulnerability in various age-related neurodegenerative disorders.

Children's evaluations of morality in the context of peer, teacher-child, and familial relations

The purpose of this study was to investigate how children evaluate moral transgressions (rule violations that do not involve conflicts) and conflicts (stories involving peer, teacher-child, and familial relations) and how children weigh different issues and re-evaluate their decisions after hearing new information about the conflict. Results showed that children at all ages supported decisions by authorities (peer and adult) to ignore social order violations to prevent harm or a failure to share. Decisions to give preference to interpersonal relations were made for issues about harm but not about sharing resources. The findings demonstrate that children give priority to the prevention of harm and a failure to share for some, but not all types of moral conflicts, and that the salience of moral consequences influences their overall evaluation.

Granulocyte-macrophage precursor cell and colony-stimulating factor responses of mice infected with Salmonella typhimurium

The response of granulocyte-macrophage progenitor cells (in vitro colony-forming cells) and of colony-stimulating (CS) factor in serum were studied in mice infected intraperitoneally with 10(3) viable Salmonella typhimurium. Increases in the number of colony-forming cells in marrow and spleen and increases in the serum level of CS factor occurred during the infection. There was no evidence to suggest that progressive infection was associated with failure of macrophage production. Medium rich in CS factor increased the bactericidal activity of macrophages in vitro and it was suggested that CS factor could be involved in macrophage activation.

Granulocyte-macrophage precursor cell responses in mice of different strain, sex and age

Mice inoculated with Freund's complete adjuvant show an increase in the number of granulocyte-macrophage precursor cells (colony-forming cells) in haemopoietic tissues. This effect is most marked in spleen and reaches a maximum 7 days after inoculation.

The magnitude of the cellular response was measured in five mouse strains (C57B1, CBA, VSBS, TO and HR) and some significant differences were found, although no differences in the level of serum regulating factors were apparent. Colony-forming cell responses were weaker in young adult males than in females and were also weaker in mice at extremes of age.

It was suggested that differences in the magnitude of cellular responses could reflect differences in the responsiveness of target cells to the same stimulus and that broad parallels may exist between myelopoietic and immunological responsiveness.

The effects of an inhibiting factor (interferon) on the in vitro growth of granulocyte-macrophage colonies

Incorporation of preparations of mouse interferon in stimulated cultures of normal mouse bone marrow results in a decrease in the number of colonies developing, and in the appearance of unusual cells in colonies. These unusual cells have the granular, vacuolated cytoplasm of the macrophage, but lobed nuclei more typical of cells of the granulocytic series. The evidence suggests that interferon inhibits the normal multiplication and differentiation of mouse granulocyte-macrophage precursors in vitro.

Suppression of immune and hemopoietic cellular responses by methisazone

The antiviral drug methisazone (N-methylisatin beta-thiosemicarbazone) was tested for its effect on immune responses to sheep erythrocytes and on hemopoietic colony-forming cell (granulocyte-macrophage progenitor cell) responses to complete Freund's adjuvant in mice. Suppressive activity was demonstrated in both systems, the immune system being more readily and more consistently susceptible. Evidence is presented which suggests that the insoluble particulate form of the drug has both stimulatory and suppressive effects on the colony-forming cell system, whereas the soluble form is only suppressive. Methisazone increased the mortality from ectromelia in adjuvant-treated animals.

The effect of synthetic double-stranded polyribonucleotides on haemopoietic colony-forming cells in vivo

Intraperitoneal inoculation of 100 μg Poly I—Poly C resulted in an an eight-fold increase in spleen colony forming cells by the sixth day after inoculation. The same dose of Poly AU resulted in a negligible cellular response and no increase in the level of colony stimulating factor in the serum. The colony stimulating activity of serum after inoculation of Poly I—Poly C was increased, but assay of this increase in early sera was complicated by the presence of a colony inhibitor. Some properties of inhibitor-containing sera were investigated and consideration given to the possibility that the colony inhibitor is related to interferon.

Role of hemopoietic colony-forming cell responses in the pathogenesis of ectromelia

Intraperitoneal injection of complete Freund's adjuvant which caused an extensive cellular response in the reticuloendothelial system greatly increased the severity of infection which resulted from footpad inoculation of ectromelia virus in mice. The mortality was greatest during the proliferative phase of the cellular response, indicated by the colony-forming cell response. Exposure of colony-forming cells to virus in vitro showed that those from normal bone marrow were much less susceptible to virus than those from the bone marrow of adjuvant-treated mice and more particularly those from the spleen of adjuvant-treated mice. Severe bleeding to induce anemia and a consequent erythropoietic response did not increase the mortality from ectromelia. Previous results were interpreted on the basis of these findings and a more general application of them to the pathogenesis of poxvirus infection was discussed.

Hemopoietic colony-forming cell responses in mice infected with ectromelia virus

The responses of in vitro colony-forming cells (granulocyte-macrophage progenitor cells) were studied in the bone marrow, spleen, and blood of mice after intraperitoneal injection of 10(3) plaque-forming units of ectromelia virus. This study showed that a colony-forming cell response occurred during infection and was accompanied by an increase in the serum level of colony-stimulating factor and, at a later stage, colony-inhibiting factor. Changes in the proportions of colony-forming cells were not due to relative changes in other cell populations. The relationships between colony-forming cell responses and levels of infection were complex, higher levels of infection being associated with good colony-forming cell responses in bone marrow and apparently poor colony-forming cell responses in blood and spleen.