Background

Identification and characterization of molecular controls that regulate mammary stem and progenitor cell homeostasis are critical to our understanding of normal mammary gland development and its pathology.

Results

We demonstrate that conditional knockout of Sox9 in the mouse mammary gland results in impaired postnatal development. In short-term lineage tracing in the postnatal mouse mammary gland using Sox9-CreER driven reporters, Sox9 marked primarily the luminal progenitors and bipotent stem/progenitor cells within the basal mammary epithelial compartment. In contrast, long-term lineage tracing studies demonstrate that Sox9+ precursors gave rise to both luminal and myoepithelial cell lineages. Finally, fate mapping of Sox9 deleted cells demonstrates that Sox9 is essential for luminal, but not myoepithelial, lineage commitment and proliferation.

Conclusions

These studies identify Sox9 as a key regulator of mammary gland development and stem/progenitor maintenance.

Visual experiences increase our ability to discriminate environmentally relevant stimuli (native stimuli, e.g., human faces) at the cost of a reduced sensitivity to irrelevant or infrequent stimuli (non-native stimuli, e.g., monkey/ape faces)-a developmental progression known as perceptual narrowing. One possible source of the reduced sensitivity in distinguishing non-native stimuli (e.g., one ape face vs. another ape face) could be underspecified attentional search templates (i.e., working memory representations). To determine whether perceptual narrowing stems from underspecified attentional templates for non-native exemplars, this study used ERP (the N2pc component) and behavioral measures in a visual search task, where the target was either an exemplar (e.g., a specific ape face) or a category (e.g., any ape face). The N2pc component, an ERP marker of early attentional selection emerging at 200 msec poststimulus, is typically modulated by the specificity of the target and, therefore, by the attentional template-the N2pc is larger for specific items versus categories. In two experiments using both human and ape faces (i.e., native and non-native stimuli), we found that perceptual narrowing affects later response selection (i.e., manual RT and accuracy), but not early attentional selection relying on attentional templates (i.e., the N2pc component). Our ERP results show that adults deploy exemplar level attentional templates for non-native stimuli (as well as native stimuli), despite poor downstream behavioral performance. Our findings suggest that long-term previous experience with reduced exemplar level judgments (i.e., perceptual narrowing) does not appear to eliminate early attentional selection of non-native exemplars.

T cells bearing gamma/delta antigen receptors comprise a resident population of intraepithelial lymphocytes in organs such as skin, gut, and lungs, where they are strategically located to contribute to the initial defense against infection. An important unsolved question about antigen-driven gamma/delta T cell responses regards the breadth of their T cell receptor (TCR) repertoire, since many specific epithelial compartments in mice display limited diversity. We have examined the diversity of TCR delta gene expression among human gamma/delta T cells from skin lesions induced by intradermal challenge with Mycobacterium leprae. We show that the vast majority of gamma/delta cells from M. leprae lesions use either V delta 1-J delta 1 or V delta 2-J delta 1 gene rearrangements and, within a given region of the lesion, display limited junctional diversity. This contrasts markedly with the extensive diversity of gamma/delta T cells from peripheral blood of these same individuals, as well as skin from normal donors. These results indicate that the gamma/delta response to M. leprae involves the selection of a limited number of clones from among a diverse repertoire, probably in response to specific mycobacterial and/or host antigens.

Background

The association between illness perceptions and the effectiveness of patients' illness-management strategies has been supported across a range of medical and psychiatric disorders. Few studies have examined these variables or their association in bipolar disorder (BD). This study examined the main and interactive associations between illness perceptions and one important illness management strategy - social rhythms stability on mood symptom severity in adults with BD.

Methods

A cross-sectional study with 131 patients with BD in Taiwan was conducted using clinician- and patient-rated mood symptoms, self-reported illness perceptions, and a measure of daily and nightly social rhythms.

Results

Illness perceptions were associated with mood symptom severity, but social rhythms were not. Unfavorable illness perceptions (e.g., beliefs of experiencing more BD symptoms, having stronger emotional responses to the illness) were associated with more severe mood symptoms. Favorable illness perceptions (e.g., beliefs of being able to understand and control the illness) were associated with less severe mood symptoms, with personal control as the strongest correlate of mood symptom severity. Finally, social rhythm stability moderated the relationship between unfavorable illness perceptions and clinician-rated manic symptoms.

Limitations

The cross-sectional design limits our ability to make causal conclusions. Also, the effects pertain to patients in remission and may not generalize to more severely ill or hospitalized bipolar patients.

Conclusions

This study indicates that in patients with BD, illness perceptions are associated with symptom severity. Interventions to enhance favorable IPs and reduce unfavorable IPs may improve mood outcomes, particularly when patients have adopted regular social rhythms.

A model of the daily carbon balance of a black spruce/feathermoss boreal forest ecosystem was developed and results compared to preliminary data from the 1994 BOREAS field campaign in northern Manitoba, Canada. The model, driven by daily weather conditions, simulated daily soil climate status (temperature and moisture profiles), spruce photosynthesis and respiration, moss photosynthesis and respiration, and litter decomposition. Model agreement with preliminary field data was good for net ecosystem exchange (NEE), capturing both the asymmetrical seasonality and short-term variability. During the growing season simulated daily NEE ranged from -4 g C m-2 d-1 (carbon uptake by ecosystem) to + 2 g C m-2 d-1 (carbon flux to atmosphere), with fluctuations from day to day. In the early winter simulated NEE values were + 0.5 g C m-2 d-1, dropping to + 0.2 g C m-2 d-1 in mid-winter. Simulated soil respiration during the growing season (+ 1 to + 5 g C m-2 d-1) was dominated by metabolic respiration of the live moss, with litter decomposition usually contributing less than 30% and live spruce root respiration less than 10% of the total. Both spruce and moss net primary productivity (NPP) rates were higher in early summer than late summer. Simulated annual NEE for 1994 was -51 g C m-2 y-1, with 83% going into tree growth and 17% into the soil carbon accumulation. Moss NPP (58 g C m-2 y-1) was considered to be litter (i.e. soil carbon input; no net increase in live moss biomass). Ecosystem respiration during the snow-covered season (84 g C m-2) was 58% of the growing season net carbon uptake. A simulation of the same site for 1968-1989 showed ≈ 10-20% year-to-year variability in heterotrophic respiration (mean of + 113 g C m-2 y-1). Moss NPP ranged from 19 to 114 g C m-2 y-1; spruce NPP from 81 to 150 g C m-2 y-1; spruce growth (NPP minus litterfall) from 34 to 103 g C m-2 y-1; NEE ranged from +37 to -142 g C m-2 y-1. Values for these carbon balance terms in 1994 were slightly smaller than the 1969-89 means. Higher ecosystem productivity years (more negative NEE) generally had early springs and relatively wet summers; lower productivity years had late springs and relatively dry summers. © 1996 Blackwell Science Ltd.

Background

In animals with heteromorphic sex chromosomes, dosage compensation of sex-chromosome genes is thought to be critical for species survival. Diverse molecular mechanisms have evolved to effectively balance the expressed dose of X-linked genes between XX and XY animals, and to balance expression of X and autosomal genes. Dosage compensation is not understood in birds, in which females (ZW) and males (ZZ) differ in the number of Z chromosomes.

Results

Using microarray analysis, we compared the male:female ratio of expression of sets of Z-linked and autosomal genes in two bird species, zebra finch and chicken, and in two mammalian species, mouse and human. Male:female ratios of expression were significantly higher for Z genes than for autosomal genes in several finch and chicken tissues. In contrast, in mouse and human the male:female ratio of expression of X-linked genes is quite similar to that of autosomal genes, indicating effective dosage compensation even in humans, in which a significant percentage of genes escape X-inactivation.

Conclusion

Birds represent an unprecedented case in which genes on one sex chromosome are expressed on average at constitutively higher levels in one sex compared with the other. Sex-chromosome dosage compensation is surprisingly ineffective in birds, suggesting that some genomes can do without effective sex-specific sex-chromosome dosage compensation mechanisms.

Background

Songbirds hold great promise for biomedical, environmental and evolutionary research. A complete draft sequence of the zebra finch genome is imminent, yet a need remains for application of genomic resources within a research community traditionally focused on ethology and neurobiological methods. In response, we developed a core set of genomic tools and a novel collaborative strategy to probe gene expression in diverse songbird species and natural contexts.

Results

We end-sequenced cDNAs from zebra finch brain and incorporated additional sequences from community sources into a database of 86,784 high quality reads. These assembled into 31,658 non-redundant contigs and singletons, which we annotated via BLAST search of chicken and human databases. The results are publicly available in the ESTIMA:Songbird database. We produced a spotted cDNA microarray with 20,160 addresses representing 17,214 non-redundant products of an estimated 11,500-15,000 genes, validating it by analysis of immediate-early gene (zenk) gene activation following song exposure and by demonstrating effective cross hybridization to genomic DNAs of other songbird species in the Passerida Parvorder. Our assembly was also used in the design of the "Lund-zfa" Affymetrix array representing approximately 22,000 non-redundant sequences. When the two arrays were hybridized to cDNAs from the same set of male and female zebra finch brain samples, both arrays detected a common set of regulated transcripts with a Pearson correlation coefficient of 0.895. To stimulate use of these resources by the songbird research community and to maintain consistent technical standards, we devised a "Community Collaboration" mechanism whereby individual birdsong researchers develop experiments and provide tissues, but a single individual in the community is responsible for all RNA extractions, labelling and microarray hybridizations.

Conclusion

Immediately, these results set the foundation for a coordinated set of 25 planned experiments by 16 research groups probing fundamental links between genome, brain, evolution and behavior in songbirds. Energetic application of genomic resources to research using songbirds should help illuminate how complex neural and behavioral traits emerge and evolve.