Showing 141 - 150 of 2039 Items

Swarm-based path creation in dynamic environments for search and rescue

Date: 2012-01-01

Creator: William K. Richard

Stephen M. Majercik

Access: Open access



Statement by Therese Cahill Low collected by Rachel George on November 4, 2014

Date: 2014-11-04

Creator: Therese Cahill Low

Access: Open access



Statement by Shawn Yardley collected by Rachel George on June 27, 2014

Date: 2014-06-27

Creator: Shawn Yardley

Access: Open access



Statement by Alivia Moore collected by Heather Westleigh on November 4, 2014

Date: 2014-11-04

Creator: Alivia Moore

Access: Open access



Statement by Lucille Atwell collected by Rachel george on June 25, 2014

Date: 2014-06-25

Creator: Lucille Atwell

Access: Open access



Statement by Mikhu Paul collected by Rachel George on December 18, 2014

Date: 2014-12-18

Creator: Mikhu Paul

Access: Open access



Fgf signaling is required for zebrafish tooth development

Date: 2004-10-01

Creator: William R. Jackman

Bruce W. Draper

David W. Stock

Access: Open access

We have investigated fibroblast growth factor (FGF) signaling during the development of the zebrafish pharyngeal dentition with the goal of uncovering novel roles for FGFs in tooth development as well as phylogenetic and topographic diversity in the tooth developmental pathway. We found that the tooth-related expression of several zebrafish genes is similar to that of their mouse orthologs, including both epithelial and mesenchymal markers. Additionally, significant differences in gene expression between zebrafish and mouse teeth are indicated by the apparent lack of fgf8 and pax9 expression in zebrafish tooth germs. FGF receptor inhibition with SU5402 at 32 h blocked dental epithelial morphogenesis and tooth mineralization. While the pharyngeal epithelium remained intact as judged by normal pitx2 expression, not only was the mesenchymal expression of lhx6 and lhx7 eliminated as expected from mouse studies, but the epithelial expression of dlx2a, dlx2b, fgf3, and fgf4 was as well. This latter result provides novel evidence that the dental epithelium is a target of FGF signaling. However, the failure of SU5402 to block localized expression of pitx2 suggests that the earliest steps of tooth initiation are FGF-independent. Investigations of specific FGF ligands with morpholino antisense oligonucleotides revealed only a mild tooth shape phenotype following fgf4 knockdown, while fgf8 inhibition revealed only a subtle down-regulation of dental dlx2b expression with no apparent effect on tooth morphology. Our results suggest redundant FGF signals target the dental epithelium and together are required for dental morphogenesis. Further work will be required to elucidate the nature of these signals, particularly with respect to their origins and whether they act through the mesenchyme. © 2004 Elsevier Inc. All rights reserved.


The 'obligate diploid' Candida albicans forms mating-competent haploids

Date: 2013-02-07

Creator: Meleah A. Hickman

Guisheng Zeng

Anja Forche

Matthew P. Hirakawa

Darren, Abbey

Benjamin D. Harrison

Yan Ming Wang

Ching Hua Su

Richard J. Bennett

Yue Wang

Judith Berman

Access: Open access

Candida albicans, the most prevalent human fungal pathogen, is considered to be an obligate diploid that carries recessive lethal mutations throughout the genome. Here we demonstrate that C. albicans has a viable haploid state that can be derived from diploid cells under in vitro and in vivo conditions, and that seems to arise through a concerted chromosome loss mechanism. Haploids undergo morphogenetic changes like those of diploids, including the yeast-hyphal transition, chlamydospore formation and a white-opaque switch that facilitates mating. Haploid opaque cells of opposite mating type mate efficiently to regenerate the diploid form, restoring heterozygosity and fitness. Homozygous diploids arise spontaneously by auto-diploidization, and both haploids and auto-diploids show a similar reduction in fitness, in vitro and in vivo, relative to heterozygous diploids, indicating that homozygous cell types are transient in mixed populations. Finally, we constructed stable haploid strains with multiple auxotrophies that will facilitate molecular and genetic analyses of this important pathogen. © 2013 Macmillan Publishers Limited. All rights reserved.


Global divergence of the human follicle mite Demodex folliculorum: Persistent associations between host ancestry and mite lineages

Date: 2015-12-29

Creator: Michael F. Palopoli

Daniel J. Fergus

Samuel Minot

Dorothy T. Pei

W. Brian, Simison

Iria Fernandez-Silva

Megan S. Thoemmes

Robert R. Dunn

Michelle Trautwein

Access: Open access

Microscopic mites of the genus Demodex live within the hair follicles of mammals and are ubiquitous symbionts of humans, but little molecular work has been done to understand their genetic diversity or transmission. Here we sampled mite DNA from 70 human hosts of diverse geographic ancestries and analyzed 241 sequences from the mitochondrial genome of the species Demodex folliculorum. Phylogenetic analyses recovered multiple deep lineages including a globally distributed lineage common among hosts of European ancestry and three lineages that primarily include hosts of Asian, African, and Latin American ancestry. To a great extent, the ancestral geography of hosts predicted the lineages of mites found on them; 27% of the total molecular variance segregated according to the regional ancestries of hosts. We found that D. folliculorum populations are stable on an individual over the course of years and that some Asian and African American hosts maintain specific mite lineages over the course of years or generations outside their geographic region of birth or ancestry. D. folliculorum haplotypes were much more likely to be shared within families and between spouses than between unrelated individuals, indicating that transmission requires close contact. Dating analyses indicated that D. folliculorum origins may predate modern humans. Overall, D. folliculorum evolution reflects ancient human population divergences, is consistent with an out-of-Africa dispersal hypothesis, and presents an excellent model system for further understanding the history of human movement.


Religion and science in the Eastern mediterranean

Date: 2016-09-01

Creator: Robert Morrison

Access: Open access

“Science and Orthodox Christianity: An Overview” is an ambitious survey that reminds scholars of science in Islamic societies that the conversation between Islam and science is really a conversation between Islam and science in different contexts and that conversations between Islam and science can be found with less renowned scientific developments such as prophetic medicine. This response points out parallels in how Greek Orthodox and Ottoman Muslim scholars mediated new developments in Western European science and in how both Greek Orthodox and some Ottoman Muslim scholars propounded a mathematical humanism. Finally, it argues that the account of post-1453 scientific exchange is more complex than “Science and Orthodox Christianity” intimates. At the least, if there was no scholarly exchange between Greek Orthodox Christians, on the one hand, and, on the other hand, Muslims and Jews—who, in turn, enjoyed scholarly exchange with the West well after 1453—there are clearly two different Easts.