American Association of Physicists in Medicine Radiation Therapy Committee Task Group 53: Quality assurance for clinical radiotherapy treatment planning

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134846/1/mp8373.pd

Contrasting Patterns of Sequence Evolution at the Functionally Redundant bric à brac Paralogs in Drosophila melanogaster

Genes with overlapping expression and function may gradually diverge despite retaining some common functions. To test whether such genes show distinct patterns of molecular evolution within species, we examined sequence variation at the bric à brac (bab) locus of Drosophila melanogaster. This locus is composed of two anciently duplicated paralogs, bab1 and bab2, which are involved in patterning the adult abdomen, legs, and ovaries. We have sequenced the 148 kb genomic region spanning the bab1 and bab2 genes from 94 inbred lines of D. melanogaster sampled from a single location. Two non-coding regions, one in each paralog, appear to be under selection. The strongest evidence of directional selection is found in a region of bab2 that has no known functional role. The other region is located in the bab1 paralog and is known to contain a cis-regulatory element that controls sex-specific abdominal pigmentation. The coding region of bab1 appears to be under stronger functional constraint than the bab2 coding sequences. Thus, the two paralogs are evolving under different selective regimes in the same natural population, illuminating the different evolutionary trajectories of partially redundant duplicate genes

GPCR Genes Are Preferentially Retained after Whole Genome Duplication

One of the most interesting questions in biology is whether certain pathways have been favored during evolution, and if so, what properties could cause such a preference. Due to the lack of experimental evidence, whether select gene families have been preferentially retained over time after duplication in metazoan organisms remains unclear. Here, by syntenic mapping of nonchemosensory G protein-coupled receptor genes (nGPCRs which represent half the receptome for transmembrane signaling) in the vertebrate genomes, we found that, as opposed to the 8–15% retention rate for whole genome duplication (WGD)-derived gene duplicates in the entire genome of pufferfish, greater than 27.8% of WGD-derived nGPCRs which interact with a nonpeptide ligand were retained after WGD in pufferfish Tetraodon nigroviridis. In addition, we show that concurrent duplication of cognate ligand genes by WGD could impose selection of nGPCRs that interact with a polypeptide ligand. Against less than 2.25% probability for parallel retention of a pair of WGD-derived ligands and a pair of cognate receptor duplicates, we found a more than 8.9% retention of WGD-derived ligand-nGPCR pairs–threefold greater than one would surmise. These results demonstrate that gene retention is not uniform after WGD in vertebrates, and suggest a Darwinian selection of GPCR-mediated intercellular communication in metazoan organisms

The Role of bZIP Transcription Factors in Green Plant Evolution: Adaptive Features Emerging from Four Founder Genes

BACKGROUND: Transcription factors of the basic leucine zipper (bZIP) family control important processes in all eukaryotes. In plants, bZIPs are regulators of many central developmental and physiological processes including photomorphogenesis, leaf and seed formation, energy homeostasis, and abiotic and biotic stress responses. Here we performed a comprehensive phylogenetic analysis of bZIP genes from algae, mosses, ferns, gymnosperms and angiosperms. METHODOLOGY/PRINCIPAL FINDINGS: We identified 13 groups of bZIP homologues in angiosperms, three more than known before, that represent 34 Possible Groups of Orthologues (PoGOs). The 34 PoGOs may correspond to the complete set of ancestral angiosperm bZIP genes that participated in the diversification of flowering plants. Homologous genes dedicated to seed-related processes and ABA-mediated stress responses originated in the common ancestor of seed plants, and three groups of homologues emerged in the angiosperm lineage, of which one group plays a role in optimizing the use of energy. CONCLUSIONS/SIGNIFICANCE: Our data suggest that the ancestor of green plants possessed four bZIP genes functionally involved in oxidative stress and unfolded protein responses that are bZIP-mediated processes in all eukaryotes, but also in light-dependent regulations. The four founder genes amplified and diverged significantly, generating traits that benefited the colonization of new environments

A journey to serve : a Chinese American woman’s service in the Canadian Armed Forces during World War II

In July 1943, my 19 year old mother, May Yee (aka May Toy Shiu), attempted to enter Canada through Windsor, Ontario intending to join the Canadian Army Auxiliary Corps. Denied entry because she lacked proof of her US citizenship, she returned to Chicago, Illinois where she appeared on July, 23, 1943, before the District Director of Immigration and Naturalization who determined that she was indeed, born in Chicago, Illinois on December 28, 1923 to Chinese immigrant parents. Initially, she sought to join the US Armed Forces but was denied because of her age. However, a Canadian recruiter informed her that women could serve in the Canadian Armed Forces at 18 years of age and recruited her to serve. Thus, began a journey that would cross geographic borders, intersect with the anti-Chinese immigration policies of both the US and Canada, and where she would participate in the little told story of minority women’s service in WW II on behalf of both Canada and the United States. This paper presents her narrative of service. Embedded in this narrative is her triumph over gender bias, reflected in her personal story of birth as an ill-fated Chinese daughter and the tenacious strength of a young Chinese American woman who sought first to serve her country of birth, the United States, and subsequently, Canada during WWII. Through the narrative construction of her story, this paper examines the broader themes of Chinese women in the Americas: gender identity and power; changing patterns of kinship influenced by immigration and the policies that shaped acculturation to different social norms, and the liminality of a gendered, ethnic minority self that was challenged to balance multiple social worlds.Non UBCUnreviewedFacult