No description available.

The anthropogenic alteration of riverine ecosystems has led to declines in the abundance and diversity of freshwater mussels (Bivalvia: Unionoida) worldwide. Central Texas is home to a diverse freshwater mussel fauna including three candidates for federal listing under the Endangered Species Act. Surveys conducted over the last few decades suggest many of the endemic freshwater mussel species in Texas exist in small isolated populations that may be vulnerable to the deleterious effects of genetic diversity loss. Microsatellite primers from two closely related species were used to identify a set of genetic markers that functioned in the Golden Orb (Quadrula aurea). Microsatellite markers were then applied to document the population genetic structure of Q. aurea within and among three connected river drainages in southeastern Texas. Gene flow within existing Q. aurea populations appears high indicating little potential for genetic issues stemming from isolation and inbreeding. Two weakly divergent admixed populations were identified occupying the San Antonio and Guadalupe/San Marcos rivers. Population genetic structure was related to river basin affiliation, but results for environmental factors were unresolved. Current effective population size estimates are large for the Guadalupe/San Marcos drainage and moderately large for the San Antonio drainage and there is no clear genetic evidence of contemporary population declines. Transport in the glochidial phase by a highly mobile host fish, the channel catfish (Ictalurus punctatus), may provide a mechanism for maintaining connectivity among spatially discrete mussel beds and deserves further study. Information on the occurrence and habitat associations of Q. aurea and two other threatened freshwater mussel species was documented. Quantification of the population genetic structure for Q. aurea provides important information needed for the management of this species, a baseline for understanding future changes, and insight into the factors that shape the population genetic structure of other threatened unionids in Texas.

Fusarium head blight (FHB), caused by Fusarium graminearum, is a serious disease of wheat and barley that has caused several billion dollars in crop losses over the last decade in the United States. Spores of F. graminearum are released from corn and small grain residues left-over from the previous growing season and are transported long distances in the atmosphere before being deposited.  Current risk assessment tools consider environmental conditions favorable for disease development, but do not include spore transport. Long distance transport models have been proposed for a number of plant pathogens, but many of these models have not been experimentally validated. In order to predict the atmospheric transport of F. graminearum, the potential source strength (Qpot) of inoculum must be known.  We conducted a series of laboratory and field experiments to estimate Qpot from a field-scale source of inoculum of F. graminearum.  Perithecia were generated on artificial (carrot agar) and natural (corn stalk) substrates.  Artificial substrate (carrot agar) produced 15±0.4 perithecia cm-2, and natural substrate (corn stalk) produced 44±2 perithecia cm-2.  Individual perithecia were excised from both substrate types and allowed to release ascospores every 24 hours.  Perithecia generated from artificial (carrot agar) and natural (corn stalk) substrates released a mean of 104±5 and 276±16 ascospores, respectively.  A volumetric spore trap was placed inside a 3,716 m2 clonal source of inoculum in 2011 and 2012.  Results indicated that ascospores were released under field conditions predominantly (>90%) during the night (1900 to 0700 hours).  Estimates of Qpot for our field-scale sources of inoculum were approximately 4 billion ascospores per 3,716 m2.  Release-recapture studies were conducted from a clonal field-scale source of F. graminearum in 2011 and 2012. Microsatellites were used to identify the released clone of F. graminearum at distances up to 1 km from the source. Dispersal kernels for field observations were compared to results predicted by a Gaussian dispersal-based spore transport model.  In 2011 and 2012, dispersal kernel shape coefficients were similar for both results observed in the field and predicted by the model, with both being dictated by a power law function, indicating that turbulence was the dominant transport factor on the scale we studied (~ 1 km).  Model predictions had a stronger correlation with the number of spores being released when using a time varying q0 emission rate (r= 0.92 in 2011 and r= 0.84 in 2012) than an identical daily pattern q0 emission rate (r= 0.35 in 2011 and r= 0.32 in 2012).  The actual numbers of spores deposited were 3 and 2000 times lower than predicted if Qpot were equal to the actual number of spores released in 2011 and 2012, respectively. Future work should address estimating the actual number of spore released from an inoculated field during any given season, to improve prediction accuracy of the model.  This work should assist in improving current risk assessment tools for FHB and contribute to the development of early warning systems for the spread of F. graminearum. / Ph. D.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19545号 / 理博第4205号 / 新制||理||1603(附属図書館) / 32581 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 村山 美穂, 教授 幸島 司郎, 教授 伊谷 原一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

付記する学位プログラム名: 霊長類学・ワイルドライフサイエンス・リーディング大学院 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24471号 / 理博第4970号 / 新制||理||1709(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 村山 美穂, 教授 伊谷 原一, 教授 平田 聡 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

No description available.

This thesis includes two studies: The first examined patterns of neutral genetic diversity within Bromus tectorum L. across the IMW region, and uses patterns of microsatellite (SSR) genotype distribution to make inferences about the respective roles of adaptively significant genetic variation, adaptive phenotypic plasticity, and facultative outcrossing in the ongoing invasion and recent range expansion of B. tectorum. It has been previously demonstrated that, due to extremely low outcrossing rates, it is possible to characterize individual genotypes of this species using four SSR loci. We sampled 20 individuals from each of 96 B. tectorum populations (classified by region and habitat) from throughout the IMW and used these SSR markers to characterize each individual. We found 131 four-locus SSR genotypes; however, the 14 most common genotypes collectively accounted for 79.2% of the individuals sampled. Individuals with certain SSR genotypes sorted strongly into warm or salt desert habitats (stringent habitats) and flowered earlier than individuals with genotypes from more mesic habitats, providing evidence of adaptively significant genetic variation associated with these genotypes. Other SSR genotypes were found across a wide range of habitats though they tended to be less prevalent in stringent habitats, providing evidence that adaptive phenotypic plasticity may be important for the distribution of some common genotypes. We observed very few heterozygous individuals, consistent with the highly inbreeding reproductive strategy of B. tectorum. Because specialist genotypes dominating recently invaded areas within the IMW region contained unique alleles, they are not likely to have resulted from recombination, leading us to doubt the role of facultative outcrossing as a significant mechanism facilitating the current range expansion of B. tectorum in the IMW.Previous research investigating the population and ecological genetics of Bromus tectorum L. in the North American invaded range has relied on either allozyme or microsatellite (SSR) genetic analyses, both of which have proven to have shortcomings. In order to overcome the issues associated with these other marker types, in the second study of this thesis we developed single nucleotide polymorphism (SNP) markers for B. tectorum by 1) obtaining normalized cDNA, 2) sequencing normalized cDNA using 454 sequencing, 3) aligning resultant contigs and looking for SNPs, 4) designing assays for SNP validation and genotyping using KASPar, 5) converting working KASPar assays for use with the Fluidigm EP1 platform using the 96.96 Dynamic ArrayTM IFC. Sequencing resulted in 1258041 reads, which assembled into 65486 contigs (20782 large contigs exceeding 500 base pairs). Using selection criteria of at least 10x coverage and 30% of the minor allele, 3333 putative SNPs were identified. We developed KASP assays for 255 putative SNPs, which resulted in 101 working polymorphic assays. Ninety-six assays were then successfully converted for use with KASP on the Fluidigm EP1 genotyping platform using 96.96 dynamic arrays.

No description available.

Medullary carcinoma (MC) of the colon is a rare and unique histologic subtype of colorectal cancer. It is commonly associated with deficient mismatch repair proteins and has a strong association with Lynch syndrome. Diagnosis is challenging as it does not have the usual immunohistochemical stains on pathology seen in colorectal adenocarcinoma. Here, we discuss an interesting case of MC of the colon that was metastatic on presentation and constituted a diagnostic challenge.

The communal breeding system of the smooth-billed ani (Crotophaga ani) was studied at two wildlife refuges in southwest Puerto Rico. Groups ranged in size from 2 to 9 adults, and communal clutches ranged in size from 11 to more than 25 eggs. Microsatellite DNA loci were isolated and used to examine the mating system and the extent of reproductive skew in individual groups. Loci were also screened in guira cuckoos (Guira guira) to examine the relationships suggested by Quinn et al. (1994). In the four focal smooth-billed ani groups, I found suggestions of monogamy, polygamy, and incidents of intraspecific brood parasitism. In all groups, incubated clutch size and microsatellite data indicate that subordinate females are gaining some reproductive success. At one nest, evidence suggested a decrease in the intensity of reproductive skew between successive nests. Although the data are limited, they suggest that alternative strategies to monogamy may be more prevalent than previously believed, and that reproductive skew may be affected by the availability of limiting resources within the breeding season. / Thesis / Master of Science (MS)