Fast Retrograde Access to Projection Neuron Circuits Underlying Vocal Learning in Songbirds.

Understanding the structure and function of neural circuits underlying speech and language is a vital step toward better treatments for diseases of these systems. Songbirds, among the few animal orders that share with humans the ability to learn vocalizations from a conspecific, have provided many insights into the neural mechanisms of vocal development. However, research into vocal learning circuits has been hindered by a lack of tools for rapid genetic targeting of specific neuron populations to meet the quick pace of developmental learning.

Soluble BAFF levels inversely correlate with peripheral B cell numbers and the expression of BAFF receptors.

The TNF family member protein BAFF/BLyS is essential for B cell survival and plays an important role in regulating class switch recombination as well as in the selection of autoreactive B cells. In humans, increased concentrations of soluble BAFF are found in different pathological conditions, which may be as diverse as autoimmune diseases, B cell malignancies, and primary Ab deficiencies (PAD). Because the mechanisms that regulate BAFF levels are not well understood, we newly developed a set of mAbs against human BAFF to study the parameters that determine the concentrations of soluble BAFF in circulation.

BAFF-R expression correlates with positive selection of immature B cells.

The interaction between BAFF and BAFF-R is crucial for the development of mature B cells. Here, we report that the expression of BAFF-R is first detectable on a fraction of mouse CD19(+) CD93(+) IgM(+) CD23(-) and human CD19(+) CD10(+) IgM(+) BM B cells. This BAFF-R(+) BM B-cell population shows higher levels of surface IgM expression and decreased RAG-2 transcripts than BAFF-R(-) immature B cells.

Crucial role for BAFF-BAFF-R signaling in the survival and maintenance of mature B cells.

Defects in the expression of either BAFF (B cell activating factor) or BAFF-R impairs B cell development beyond the immature, transitional type-1 stage and thus, prevents the formation of follicular and marginal zone B cells, whereas B-1 B cells remain unaffected. The expression of BAFF-R on all mature B cells might suggest a role for BAFF-R signaling also for their in vivo maintenance. Here, we show that, 14 days following a single injection of an anti-BAFF-R mAb that prevents BAFF binding, both follicular and marginal zone B cell numbers are drastically reduced, whereas B-1 cells are not affected.

Increasing Flt3L availability alters composition of a novel bone marrow lymphoid progenitor compartment.

We have recently described a CD19(-) B220(+)CD117(low) bone marrow subpopulation with B, T, and myeloid developmental potential, which we have called "early progenitors with lymphoid and myeloid potential" or EPLM. These cells also expressed Fms-like tyrosine kinase 3, Flt3, or CD135. Treatment of mice with the corresponding ligand, Flt3L, showed a 50-fold increase in EPLM.

The Drosophila melanogaster condensin subunit Cap-G interacts with the centromere-specific histone H3 variant CID.

The centromere-specific histone H3 variant CENP-A plays a crucial role in kinetochore specification and assembly. We chose a genetic approach to identify interactors of the Drosophila CENP-A homolog CID. Overexpression of cid in the proliferating eye imaginal disk results in a rough eye phenotype, which is dependent on the ability of the overexpressed protein to localize to the kinetochore.