Master of Science / Food Science - Food, Nutrition, Dietetics and Health / Kadri Koppel / Understanding the physiological activation and genetic variation of the sweet taste receptor (T1R) can improve formula optimization for products intended for a population of genetically diverse people. Computer modeling and cell culture techniques have thoroughly described the structure and binding sites of the T1R. The structure contains two subunits (T1R2 and T1R3) with multiple domains where sweet molecules can interact. The interaction takes place between individual molecules and amino acid residues of the T1R. The residues with which individual molecules interact differs between sweeteners. Person-to-person differences in the residue sequence of the T1R can arise from variation in the genes that encode the T1R (TAS1R), potentially effecting the function of the receptor. As a result of the specificity of binding interactions, genetic variation may affect sensitivity to some sweeteners, while sensitivity to other sweeteners remains normal. Therefore, it can be hypothesized that the level of person-to-person sweetness sensitivity variation may differ for each sweetener depending on the binding site of the molecule and site of T1R variation. The T1R structure, binding sites, and genetic variation will be reviewed, as well as potential parameters to predict the degree of sensitivity variation and formulation strategies to minimize the effects of sensitivity variation.

<div><p>Wheat is among the most important cereal crops in the world today with respect to the area harvested (219 million ha), production (772 million tonnes), and productivity (3.53 tons/ha). However, global wheat production goals for the coming decades are falling short of needed increases. Among the leading factors hindering yields is abiotic stress which is present in nearly 38% of wheat acres globally. Nevertheless, many standard wheat breeding programs focus on yield and yield related traits (i.e. grain yield, plant height, and test weight) in ideal environments rather than evaluating traits that could lead to enhanced abiotic stress tolerance. In this thesis, we explore the use of root and high-throughput phenotyping strategies to aid in further development of abiotic stress tolerant varieties. </p><p>In the first three experiments, root phenotypes were evaluated in two nitrogen (N) treatments. Over a series of seedling, adult, and multiple-growth-stage destructive plant biomass measurements, above-ground and below-ground traits were analyzed in seven geographically diverse wheat accessions. Root and shoot biomass allocation in fourteen-day-old seedlings were analyzed using paper-roll-supported hydroponic culture in two Hoagland solutions containing 0.5 (low) and 4.0 (high) mM of N. Root traits were digitized using a WINRhizo platform. For biomass analysis at maturity, plants were grown in 7.5-liter pots filled with soil mix using the same concentrations of N. Traits were measured as plants reached maturity. In the third N experiment, above- and below-ground traits were measured at four-leaf stage, stem elongation, heading, post-anthesis, and maturity. At maturity, there was a ~15-fold difference between lines with the largest and smallest root dry matter. However, only ~5-fold difference was observed between genotypes for above-ground biomass. In the third experiment, root growth did not significantly change from stem elongation to maturity. </p><p>In the final experiment, two of these lines were selected for further evaluation under well-watered and drought treatments. This experiment was implemented in a completely randomized design in the Controlled Environment Phenotyping Facility (CEPF) at Purdue University. The differential water treatments were imposed at stem elongation and continued until post-anthesis, when all plants were destructively phenotyped. Image-based height and side-projected area were associated with height and shoot dry matter with correlations of r=1 and r=0.98, respectively. Additionally, 81% of the variation in tiller number was explained using convex hull and side-projected area. Image-based phenotypes were used to model crop growth temporally, through which one of the lines was identified as being relatively more drought tolerant. Finally, the use of the Munsell Color System was explored to investigate drought response.</p><p>These experiments illustrate the value of phenotyping and the use of novel phenotyping strategies in wheat breeding to increase adaptation and development of lines with enhanced abiotic tolerance.</p></div><br>

O trabalho objetivou construir um dendograma filogenético das cepas de Aspergillus flavus isoladas de amendoim recém-colhido de quatro regiões de São Paulo (Cafelândia, Jaboticabal, Rosália e Tupã), avaliar o potencial toxigênico e agrupar as cepas quanto à produção de esclerócios. A técnica de AFLP foi utilizada para caracterização genotípica. O potencial aflatoxigênico foi avaliado pelo cultivo das cepas em meio de ágar coco, extração das aflatoxinas por clorofórmio, separação por CCD e quantificação por espectrodenditômetro CS-9000. A indução da produção de esclerócios foi feita pela incubação dos isolados em meio ágar Czapeck-DOX. AFLP gerou 78 fragmentos de 27 pb a 365 pb, sendo 13% não polimórficos. O perfil genotípico revelou 31 haplótipos e de 12 grupos no dendograma. A similaridade entre os isolados variou de 37 a 90 %. O potencial aflatoxigênico revelou 91,7 % de cepas produtoras, com níveis entre 39,27 mg/Kg e 28689,61 mg/Kg para AFB1 e 1,50 mg/Kg a 9781,09 mg/Kg para AFB2. Quanto aos esclerócios, 83,9% das cepas foram produtoras, sendo todas tipo S. / This study aimed to draw a phylogenetic dendogram of Aspergillus flavus strains isolated from fresh harvested peanut from four regions of São Paulo state (Cafelândia, Jaboticabal, Rosália and Tupã), to determine the toxigenic potential and to group them regarding the sclerotia production pattern. The AFLP thecnique was used for genotypic characterization. Aflatoxin production was evaluated by inoculation of fungi in coconut agar, extraction with chloroform, TLC segregation and quantification by spectrophotometer CS-9000. Agar Czapeck-DOX was used to evaluate sclerotia production. AFLP generated 78 fragments varying from 27 pb to 365 pb, 13 % of them were not polymorphic. The genotypic profile showed 31 haplotypes and 12 groups in the dendogram. The similarity among the isolates varied from 37 to 90 %. The aflatoxigenic potential showed 91,7 % of producer strains, with levels between 39,27 mg/Kg and 28689,61 mg/Kg for AFB1 and between 1,50 mg/Kg and 9781,09 mg/Kg for AFB2. Concerning the sclerotia production, 83,9 % of the strains were producers, all were S type.

<p>The two papers presented in this thesis focus on population genetic study on freshwater pearl mussel populations in Sweden, using RAPD method. In paper I, I examine genetic variation within and between 5 populations in a single drainage area in south western Sweden. In paper II, I study the evolutionary relationship, and how genetic variation is related to population size, age structure and geographic isolation in 14 populations of freshwater pearl mussel in south central Sweden. In both papers I and II, I found that genetic variation was larger than found in previous studies using other techniques, and variation was larger between than within populations. I did not found any correlation between geographic and genetic distance, which indicates that mussel populations have been adapted locally to environmental factors in a relatively short time. In paper I, I found that genetic distance between populations was greater than found in other studies, despite small geographic distances. In paper II, I found that populations were highly differentiated indicating little gene flow between them. There was no significant positive relation between genetic variation and population size or age structure but there was a significant positive relation between mean age and population size indicating that many populations have gone through bottlenecks recently.</p>

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 90-119).

The two papers presented in this thesis focus on population genetic study on freshwater pearl mussel populations in Sweden, using RAPD method. In paper I, I examine genetic variation within and between 5 populations in a single drainage area in south western Sweden. In paper II, I study the evolutionary relationship, and how genetic variation is related to population size, age structure and geographic isolation in 14 populations of freshwater pearl mussel in south central Sweden. In both papers I and II, I found that genetic variation was larger than found in previous studies using other techniques, and variation was larger between than within populations. I did not found any correlation between geographic and genetic distance, which indicates that mussel populations have been adapted locally to environmental factors in a relatively short time. In paper I, I found that genetic distance between populations was greater than found in other studies, despite small geographic distances. In paper II, I found that populations were highly differentiated indicating little gene flow between them. There was no significant positive relation between genetic variation and population size or age structure but there was a significant positive relation between mean age and population size indicating that many populations have gone through bottlenecks recently.

No description available.

Previous research performed in 1999 by Harris et al. has shown that many varieties of ruminants serve as the host species for Mycobacterium avium subspecies paratuberculosis (MparaTb) infections. Gene sequencing has supported the contention that organisms isolated from different hosts harbor different gene sequences; this has been exemplified by Amonsin et al. in 2004 with the sequencing of the mfd (transcription-repair coupling factor) and by Motiwala et al. in 2005 through sequence analysis of phosphatidylethanolaminebinding proteins which reveal a host-specific correlation of isolates. Some contradicting reports from Bannantine et al. from 2003 have further claimed that MparaTb is a monogenic organism based upon sequence data from regions flanking the origin of replication and the 16s rRNA. One of the drawbacks to the techniques implemented in these reports is the extremely restricted region of the bacterial genome that was analyzed; furthermore, only a select number of isolates were analyzed. In the present studies, amplified fragment length polymorphism (AFLP) was used as a tool for a genome scale comparison of MparaTb isolates from differing isolation types as well as a comparison of MparaTb isolates to the genetically similar yet avirulent Mycobacterium avium subspecies avium isolates. AFLP data reveals the MparaTb genome to be much more plastic and polymorphic than previously thought. These polymorphic regions were identified and characterized and are shown to be unique to the organism when compared to an array of Mycobacterial isolates of differing species. These polymorphic regions were also utilized in polymerase chain reaction (PCR) based diagnostic as well as epidemiologic tests. Furthermore, AFLP comparative analysis of intracellular and fecal MparaTb isolates reveals polymorphic regions unique to each isolate type. While these genomic differences are not based upon differences in the genetic code, they are based upon epigenetic modifications such as DNA methylation. These DNA methylation patterns are unique to intracellular MparaTb isolates as opposed to isolates from fecal material. Furthermore, AFLP comparisons of fecal MparaTb isolates that were passaged through the bovine ileum revealed banding pattern differences as compared to the original inoculum.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 109-140).

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 130-160).