A Conserved Developmental Patterning Network Produces Quantitatively Different Output in Multiple Species of Drosophila

Differences in the level, timing, or location of gene expression can contribute to alternative phenotypes at the molecular and organismal level. Understanding the origins of expression differences is complicated by the fact that organismal morphology and gene regulatory networks could potentially vary even between closely related species. To assess the scope of such changes, we used high-resolution imaging methods to measure mRNA expression in blastoderm embryos of Drosophila yakuba and Drosophila pseudoobscura and assembled these data into cellular resolution atlases, where expression levels for 13 genes in the segmentation network are averaged into species-specific, cellular resolution morphological frameworks. We demonstrate that the blastoderm embryos of these species differ in their morphology in terms of size, shape, and number of nuclei. We present an approach to compare cellular gene expression patterns between species, while accounting for varying embryo morphology, and apply it to our data and an equivalent dataset for Drosophila melanogaster. Our analysis reveals that all individual genes differ quantitatively in their spatio-temporal expression patterns between these species, primarily in terms of their relative position and dynamics. Despite many small quantitative differences, cellular gene expression profiles for the whole set of genes examined are largely similar. This suggests that cell types at this stage of development are conserved, though they can differ in their relative position by up to 3–4 cell widths and in their relative proportion between species by as much as 5-fold. Quantitative differences in the dynamics and relative level of a subset of genes between corresponding cell types may reflect altered regulatory functions between species. Our results emphasize that transcriptional networks can diverge over short evolutionary timescales and that even small changes can lead to distinct output in terms of the placement and number of equivalent cells

Disputing the Subject of Sex: Sexual Identity and School Controversy, New York State, 1986-1993

226 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.This dissertation examines discussions of sexual identity's place in public education, arguing that it has been constrained by two structural problems: the notion that curricula themselves must reflect local values, even if those values are discriminatory; and the failure of curricula to historicize meanings and definitions of sexuality. I examine New York State's Instructional Guide for AIDS Education K-12, New York City's "Children of the Rainbow" gay-inclusive multicultural curriculum guide, New York City's "Abstinence Oath" for AIDS educators, and the "Sex Respect" curriculum to critique school policy's definitions of sex and attendant definitions of identity. In the first section of the dissertation, I survey three broad philosophical conceptions of identity. Liberalism and communitarianism, particularly expressed in school curricular debates, tend not to interrogate the varied forms of sexuality and gender. Following critiques of these two theories, I turn to postmodern theorists who address the complexity and contingency of sex, sexuality and sexual identity. In the second section, I examine New York State AIDS educational policy and highlight the problematic exclusionary identities within the text of the curricular guide and the plans for its implementation. I contend that this policy offers students very specific definitions of sex, identity, and community, and that the meanings offered are simplistic and discriminatory. In the third section, I analyze how controversies about curricular definitions of sex themselves complicate notions of identity, inadvertently opening new public spaces to articulations of sexual identity.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD