<title>Abstract</title> <italic>Drosophila</italic> first instar (L1) larval brains (LBs) contain frequent quiescent neural stem cells (qNSCs) as well as activated neuroblasts, making them favorable for studying stem cell quiescence and activation. However, the small size of LBs at the L1 stage necessitates the use of modified methods to prepare the LBs for immunofluorescence microscopy (IFM). The protocol described here allows efficient collection of embryos and maturation of larvae to the mid-L1 stage, followed by dissection, fixation and processing of LBs through the antibody staining steps for IFM. The entire procedure can be completed in ~3-5 days. Methods are also described for use in preparing L1 brains for live imaging experiments, including a file to create accessible and cost-effective 3D printed slides that can be fit with an O<sub>2</sub>-permeable membrane for live imaging.
ABSTRACT The blastema is a mass of progenitor cells responsible for regeneration of amputated salamander limbs and fish fins. Previous studies have indicated that resident cell sources producing the blastema contribute lineage-restricted progeny to regenerating tissue. However, these studies have labeled general cell types rather than granular cell subpopulations, and they do not explain the developmental transitions that must occur for distal structures to arise from cells with proximal identities in the appendage stump. Here, we find that regulatory sequences of tph1b, which encodes an enzyme that synthesizes serotonin, mark a subpopulation of fibroblast-like cells restricted to the joints of uninjured adult zebrafish fins. Amputation stimulates serotonin production in regenerating fin fibroblasts, yet targeted tph1b mutations abrogating this response do not disrupt fin regeneration. In uninjured animals, tph1b-expressing cells contribute fibroblast progeny that remain restricted to joints throughout life. By contrast, upon amputation, tph1b+ joint cells give rise to fibroblasts that distribute across the entire lengths of regenerating fin rays. Our experiments visualize and quantify how incorporation into an appendage blastema broadens the progeny contributions of a cellular subpopulation that normally has proximodistal restrictions.
BackgroundCDC data show that the prevalence of obesity (BMI>95% for age) in the US is 18-20% in children and adolescents. Similarly, in New York City 17% of school children are obese. Intriguingly, even in children with IBD the rates of overweight/obesity were reported to be as high as 10-30%. Our goal was to examine the change in overweight/obesity rates among our diverse population of inner-city IBD patients after 1 year of therapy, and to evaluate the role of steroid therapy in accelerating obesity rates in IBD patients.
Many hematologic malignancies are associated with recurrent cytogenetic abnormalities. Often these rearrangements result in gene fusion, leading to altered gene expression and/or activity. As the gene affected by these rearrangements are characterized at the molecular level, one particular group, the DNA binding transcriptional regulatory genes, are becoming more prominent. In this communication, we review how these genetic rearrangements effect the structure and expression of transcriptional regulatory proteins, and discuss how these abnormalities may be used quantitative diagnostic markers to analyze disease activity.
