http://hdl.handle.net/2144/1000 Sun, 19 May 2013 01:39:57 GMT 2013-05-19T01:39:57Z http://hdl.handle.net/2144/3142 Does Coevolution Promote Species Richness in Parasitic Cuckoos? Krüger, Oliver; Sorenson, Michael D.; Davies, Nicholas B. Why some lineages have diversified into larger numbers of species than others is a fundamental but still relatively poorly understood aspect of the evolutionary process. Coevolution has been recognized as a potentially important engine of speciation, but has rarely been tested in a comparative framework. We use a comparative approach based on a complete phylogeny of all living cuckoos to test whether parasite-host coevolution is associated with patterns of cuckoo species richness. There are no clear differences between parental and parasitic cuckoos in the number of species per genus. However, a cladogenesis test shows that brood parasitism is associated with both significantly higher speciation and extinction rates. Furthermore, subspecies diversification rate estimates were over twice as high in parasitic cuckoos as in parental cuckoos. Among parasitic cuckoos, there is marked variation in the severity of the detrimental effects on host fitness; chicks of some cuckoo species are raised alongside the young of the host and others are more virulent, with the cuckoo chick ejecting or killing the eggs/young of the host. We show that cuckoos with a more virulent parasitic strategy have more recognized subspecies. In addition, cuckoo species with more recognized subspecies have more hosts. These results hold after controlling for confounding geographical effects such as range size and isolation in archipelagos. Although the power of our analyses is limited by the fact that brood parasitism evolved independently only three times in cuckoos, our results suggest that coevolutionary arms races with hosts have contributed to higher speciation and extinction rates in parasitic cuckoos. Wed, 19 Aug 2009 00:00:00 GMT http://hdl.handle.net/2144/3142 2009-08-19T00:00:00Z http://hdl.handle.net/2144/3143 Impact of Methoxyacetic Acid on Mouse Leydig Cell Gene Expression Bagchi, Gargi; Zhang, Yijing; Waxman, David J BACKGROUND. Methoxyacetic acid (MAA) is the active metabolite of the widely used industrial chemical ethylene glycol monomethyl ether, which is associated with various developmental and reproductive toxicities, including neural toxicity, blood and immune disorders, limb degeneration and testicular toxicity. Testicular toxicity is caused by degeneration of germ cells in association with changes in gene expression in both germ cells and Sertoli cells of the testis. This study investigates the impact of MAA on gene expression in testicular Leydig cells, which play a critical role in germ cell survival and male reproductive function. METHODS. Cultured mouse TM3 Leydig cells were treated with MAA for 3, 8, and 24 h and changes in gene expression were monitored by genome-wide transcriptional profiling. RESULTS. A total of 3,912 MAA-responsive genes were identified. Ingenuity Pathway analysis identified reproductive system disease, inflammatory disease and connective tissue disorder as the top biological functions affected by MAA. The MAA-responsive genes were classified into 1,366 early responders, 1,387 mid-responders, and 1,138 late responders, based on the time required for MAA to elicit a response. Analysis of enriched functional clusters for each subgroup identified 106 MAA early response genes involved in transcription regulation, including 32 genes associated with developmental processes. 60 DNA-binding proteins responded to MAA rapidly but transiently, and may contribute to the downstream effects of MAA seen for many mid and late response genes. Genes within the phosphatidylinositol/phospholipase C/calcium signaling pathway, whose activity is required for potentiation of nuclear receptor signaling by MAA, were also enriched in the set of early MAA response genes. In contrast, many of the genes responding to MAA at later time points encode membrane proteins that contribute to cell adhesion and membrane signaling. CONCLUSIONS. These findings on the progressive changes in gene expression induced by MAA in a cultured Leydig cell model may help elucidate signaling pathways that lead to the testicular pathophysiological responses induced by MAA exposure and may identify useful biomarkers of MAA toxicity. Fri, 18 Jun 2010 00:00:00 GMT http://hdl.handle.net/2144/3143 2010-06-18T00:00:00Z http://hdl.handle.net/2144/3144 Global Anesthesia Workforce Crisis: A Preliminary Survey Revealing Shortages Contributing to Undesirable Outcomes and Unsafe Practices Dubowitz, Gerald; Detlefs, Sarah; Kelly McQueen, K. A. BACKGROUND. The burden of disease, disability, and mortality that could be averted by surgery is growing. However, few low and middle income countries (LMICs) have the infrastructure or capacity to provide surgical services to meet this growing need. Equally, few of these countries have been assessed for key infrastructural capacity including surgical and anesthesia providers, equipment, and supplies. These assessments are critical to revealing magnitude of the evolving surgical and anesthesia workforce crisis, related morbidity and mortality, and necessary steps to mitigate the impact of the crisis. METHODS. A pilot Internet-based survey was conducted to estimate per-capita anesthesia providers in LMICs. Information was obtained from e-mail respondents at national health care addresses, and from individuals working in-country on anesthesia-related projects. RESULTS. Workers from 6 of 98 countries responded to direct e-mail inquiries, and an additional five responses came from individuals who were working or had worked in-country at the time of the survey. The data collected revealed that the per-capita anesthesia provider ratio in the countries surveyed was often 100 times lower than in developed countries. CONCLUSIONS. This pilot study revealed that the number of anesthesia providers available per capita of population is markedly reduced in low and lower middle income countries compared to developed countries. As anesthesia providers are an integral part of the delivery of safe and effective surgical care, it is essential that more data is collected to fully understand the deficiencies in workforce and capacity in low and middle income countries. Thu, 01 Oct 2009 00:00:00 GMT http://hdl.handle.net/2144/3144 2009-10-01T00:00:00Z http://hdl.handle.net/2144/3137 Global Conservation Significance of Ecuador's Yasun National Park Bass, Margot S.; Finer, Matt; Jenkins, Clinton N.; Kreft, Holger; Cisneros-Heredia, Diego F.; McCracken, Shawn F.; Pitman, Nigel C. A.; English, Peter H.; Swing, Kelly; Villa, Gorky; Di Fiore, Anthony; Voigt, Christian C.; Kunz, Thomas H. BACKGROUND. The threats facing Ecuador's Yasuní National Park are emblematic of those confronting the greater western Amazon, one of the world's last high-biodiversity wilderness areas. Notably, the country's second largest untapped oil reserves-called "ITT"-lie beneath an intact, remote section of the park. The conservation significance of Yasuní may weigh heavily in upcoming state-level and international decisions, including whether to develop the oil or invest in alternatives. METHODOLOGY/PRINCIPAL FINDINGS. We conducted the first comprehensive synthesis of biodiversity data for Yasuní. Mapping amphibian, bird, mammal, and plant distributions, we found eastern Ecuador and northern Peru to be the only regions in South America where species richness centers for all four taxonomic groups overlap. This quadruple richness center has only one viable strict protected area (IUCN levels I-IV): Yasuní. The park covers just 14% of the quadruple richness center's area, whereas active or proposed oil concessions cover 79%. Using field inventory data, we compared Yasuní's local (alpha) and landscape (gamma) diversity to other sites, in the western Amazon and globally. These analyses further suggest that Yasuní is among the most biodiverse places on Earth, with apparent world richness records for amphibians, reptiles, bats, and trees. Yasuní also protects a considerable number of threatened species and regional endemics. CONCLUSIONS/SIGNIFICANCE. Yasuní has outstanding global conservation significance due to its extraordinary biodiversity and potential to sustain this biodiversity in the long term because of its 1) large size and wilderness character, 2) intact large-vertebrate assemblage, 3) IUCN level-II protection status in a region lacking other strict protected areas, and 4) likelihood of maintaining wet, rainforest conditions while anticipated climate change-induced drought intensifies in the eastern Amazon. However, further oil development in Yasuní jeopardizes its conservation values. These findings form the scientific basis for policy recommendations, including stopping any new oil activities and road construction in Yasuní and creating areas off-limits to large-scale development in adjacent northern Peru. Tue, 19 Jan 2010 00:00:00 GMT http://hdl.handle.net/2144/3137 2010-01-19T00:00:00Z