Matching Items (50)
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Description
The F1Fo ATP synthase is required for energy conversion in almost all living organisms. The F1 complex is a molecular motor that uses ATP hydrolysis to drive rotation of the γ–subunit. It has not been previously possible to resolve the speed and position of the γ–subunit of the F1–ATPase as

The F1Fo ATP synthase is required for energy conversion in almost all living organisms. The F1 complex is a molecular motor that uses ATP hydrolysis to drive rotation of the γ–subunit. It has not been previously possible to resolve the speed and position of the γ–subunit of the F1–ATPase as it rotates during a power stroke. The single molecule experiments presented here measured light scattered from 45X91 nm gold nanorods attached to the γ–subunit that provide an unprecedented 5 μs resolution of rotational position as a function of time. The product of velocity and drag, which were both measured directly, resulted in an average torque of 63±8 pN nm for the Escherichia coli F1-ATPase that was determined to be independent of the load. The rotational velocity had an initial (I) acceleration phase 15° from the end of the catalytic dwell, a slow (S) acceleration phase during ATP binding/ADP release (15°–60°), and a fast (F) acceleration phase (60°–90°) containing an interim deceleration (ID) phase (75°–82°). High ADP concentrations decreased the velocity of the S phase proportional to 'ADP-release' dwells, and the F phase proportional to the free energy derived from the [ADP][Pi]/[ATP] chemical equilibrium. The decreased affinity for ITP increased ITP-binding dwells by 10%, but decreased velocity by 40% during the S phase. This is the first direct evidence that nucleotide binding contributes to F1–ATPase torque. Mutations that affect specific phases of rotation were identified, some in regions of F1 previously considered not to contribute to rotation. Mutations βD372V and γK9I increased the F phase velocity, and γK9I increased the depth of the ID phase. The conversion between S and F phases was specifically affected by γQ269L. While βT273D, βD305E, and αR283Q decreased the velocity of all phases, decreases in velocity due to βD302T, γR268L and γT82A were confined to the I and S phases. The correlations between the structural locations of these mutations and the phases of rotation they affect provide new insight into the molecular basis for F1–ATPase γ-subunit rotation.
ContributorsMartin, James (Author) / Frasch, Wayne D (Thesis advisor) / Chandler, Douglas (Committee member) / Gaxiola, Roberto (Committee member) / Yan, Hao (Committee member) / Arizona State University (Publisher)
Created2012
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Description
Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most common cancers. Therefore, vaccines against HCV are under intense study

Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most common cancers. Therefore, vaccines against HCV are under intense study in order to prevent HCV from harming people's health. The envelope protein 2 (E2) of HCV is thought to be a promising vaccine candidate because it can directly bind to a human cell receptor and plays a role in viral entry. However, the E2 protein production in cells is inefficient due to its complicated matured structure. Folding of E2 in the endoplasmic reticulum (ER) is often error-prone, resulting in production of aggregates and misfolded proteins. These incorrect forms of E2 are not functional because they are not able to bind to human cells and stimulate antibody response to inhibit this binding. This study is aimed to overcome the difficulties of HCV E2 production in plant system. Protein folding in the ER requires great assistance from molecular chaperones. Thus, in this study, two molecular chaperones in the ER, calreticulin and calnexin, were transiently overexpressed in plant leaves in order to facilitate E2 folding and production. Both of them showed benefits in increasing the yield of E2 and improving the quality of E2. In addition, poorly folded E2 accumulated in the ER may cause stress in the ER and trigger transcriptional activation of ER molecular chaperones. Therefore, a transcription factor involved in this pathway, named bZIP60, was also overexpressed in plant leaves, aiming at up-regulating a major family of molecular chaperones called BiP to assist protein folding. However, our results showed that BiP mRNA levels were not up-regulated by bZIP60, but they increased in response to E2 expression. The Western blot analysis also showed that overexpression of bZIP60 had a small effect on promoting E2 folding. Overall, this study suggested that increasing the level of specific ER molecular chaperones was an effective way to promote HCV E2 protein production and maturation.
ContributorsHong, Fan (Author) / Mason, Hugh (Thesis advisor) / Gaxiola, Roberto (Committee member) / Chang, Yung (Committee member) / Chen, Qiang (Committee member) / Arizona State University (Publisher)
Created2011
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Description
22q11.2 Deletion Syndrome (22q11.2DS) is one of the most frequent chromosomal microdeletion syndromes in humans. This case study focuses on the language and reading profile of a female adult with 22q11.2 Deletion Syndrome who was undiagnosed until the age of 27 years old. To comprehensively describe the participant's profile, a

22q11.2 Deletion Syndrome (22q11.2DS) is one of the most frequent chromosomal microdeletion syndromes in humans. This case study focuses on the language and reading profile of a female adult with 22q11.2 Deletion Syndrome who was undiagnosed until the age of 27 years old. To comprehensively describe the participant's profile, a series of assessment measures was administered in the speech, language, cognition, reading, and motor domains. Understanding how 22q11.2DS has impacted the life of a recently diagnosed adult will provide insight into how to best facilitate long-term language and educational support for this population and inform future research.
ContributorsPhilp, Jennifer Lynn (Author) / Scherer, Nancy (Thesis director) / Peter, Beate (Committee member) / Department of Speech and Hearing Science (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Description
The purpose of the present study was to determine if vocabulary knowledge is related to degree of hearing loss. A 50-question multiple-choice vocabulary test comprised of old and new words was administered to 43 adults with hearing loss (19 to 92 years old) and 51 adults with normal hearing (20

The purpose of the present study was to determine if vocabulary knowledge is related to degree of hearing loss. A 50-question multiple-choice vocabulary test comprised of old and new words was administered to 43 adults with hearing loss (19 to 92 years old) and 51 adults with normal hearing (20 to 40 years old). Degree of hearing loss ranged from mild to moderately-severe as determined by bilateral pure-tone thresholds. Education levels ranged from some high school to graduate degrees. It was predicted that knowledge of new words would decrease with increasing hearing loss, whereas knowledge of old words would be unaffected. The Test of Contemporary Vocabulary (TCV) was developed for this study and contained words with old and new definitions. The vocabulary scores were subjected to repeated-measures ANOVA with definition type (old and new) as the within-subjects factor. Hearing level and education were between-subjects factors, while age was entered as a covariate. The results revealed no main effect of age or education level, while a significant main effect of hearing level was observed. Specifically, performance for new words decreased significantly as degree of hearing loss increased. A similar effect was not observed for old words. These results indicate that knowledge of new definitions is inversely related to degree of hearing loss.
ContributorsMarzan, Nicole Ann (Author) / Pittman, Andrea (Thesis director) / Azuma, Tamiko (Committee member) / Wexler, Kathryn (Committee member) / Department of Speech and Hearing Science (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
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Description
Language acquisition is a phenomenon we all experience, and though it is well studied many questions remain regarding the neural bases of language. Whether a hearing speaker or Deaf signer, spoken and signed language acquisition (with eventual proficiency) develop similarly and share common neural networks. While signed language and spoken

Language acquisition is a phenomenon we all experience, and though it is well studied many questions remain regarding the neural bases of language. Whether a hearing speaker or Deaf signer, spoken and signed language acquisition (with eventual proficiency) develop similarly and share common neural networks. While signed language and spoken language engage completely different sensory modalities (visual-manual versus the more common auditory-oromotor) both languages share grammatical structures and contain syntactic intricacies innate to all languages. Thus, studies of multi-modal bilingualism (e.g. a native English speaker learning American Sign Language) can lead to a better understanding of the neurobiology of second language acquisition, and of language more broadly. For example, can the well-developed visual-spatial processing networks in English speakers support grammatical processing in sign language, as it relies heavily on location and movement? The present study furthers the understanding of the neural correlates of second language acquisition by studying late L2 normal hearing learners of American Sign Language (ASL). Twenty English speaking ASU students enrolled in advanced American Sign Language coursework participated in our functional Magnetic Resonance Imaging (fMRI) study. The aim was to identify the brain networks engaged in syntactic processing of ASL sentences in late L2 ASL learners. While many studies have addressed the neurobiology of acquiring a second spoken language, no previous study to our knowledge has examined the brain networks supporting syntactic processing in bimodal bilinguals. We examined the brain networks engaged while perceiving ASL sentences compared to ASL word lists, as well as written English sentences and word lists. We hypothesized that our findings in late bimodal bilinguals would largely coincide with the unimodal bilingual literature, but with a few notable differences including additional attention networks being engaged by ASL processing. Our results suggest that there is a high degree of overlap in sentence processing networks for ASL and English. There also are important differences in regards to the recruitment of speech comprehension, visual-spatial and domain-general brain networks. Our findings suggest that well-known sentence comprehension and syntactic processing regions for spoken languages are flexible and modality-independent.
ContributorsMickelsen, Soren Brooks (Co-author) / Johnson, Lisa (Co-author) / Rogalsky, Corianne (Thesis director) / Azuma, Tamiko (Committee member) / Howard, Pamela (Committee member) / Department of Speech and Hearing Science (Contributor) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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Description
An increasing number of military veterans are enrolling in college, primarily due to the Post-9/11 GI Bill, which provides educational benefits to veterans who served on active duty since September 11, 2001. With rigorous training, active combat situations, and exposure to unexpected situations, the veteran population is at a higher

An increasing number of military veterans are enrolling in college, primarily due to the Post-9/11 GI Bill, which provides educational benefits to veterans who served on active duty since September 11, 2001. With rigorous training, active combat situations, and exposure to unexpected situations, the veteran population is at a higher risk for traumatic brain injury (TBI), Post Traumatic Stress Disorder (PTSD), and depression. All of these conditions are associated with cognitive consequences, including attention deficits, working memory problems, and episodic memory impairments. Some conditions, particularly mild TBI, are not diagnosed or treated until long after the injury when the person realizes they have cognitive difficulties. Even mild cognitive problems can hinder learning in an academic setting, but there is little data on the frequency and severity of cognitive deficits in veteran college students. The current study examines self-reported cognitive symptoms in veteran students compared to civilian students and how those symptoms relate to service-related conditions. A better understanding of the pattern of self-reported symptoms will help researchers and clinicians determine the veterans who are at higher risk for cognitive and academic difficulties.
ContributorsAllen, Kelly Anne (Author) / Azuma, Tamiko (Thesis director) / Gallagher, Karen (Committee member) / Department of Speech and Hearing Science (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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Description
The purpose of this study was to examine swallowing patterns using ultrasound technology subsequent to the implementation of two therapeutic interventions. Baseline swallow patterns were compared to swallows after implementation of therapeutic interventions common in both feeding therapy (FT) and orofacial myofunctional therapy (OMT). The interventions consist of stimulation of

The purpose of this study was to examine swallowing patterns using ultrasound technology subsequent to the implementation of two therapeutic interventions. Baseline swallow patterns were compared to swallows after implementation of therapeutic interventions common in both feeding therapy (FT) and orofacial myofunctional therapy (OMT). The interventions consist of stimulation of the tongue by z-vibe and tongue pops. Changes in swallowing patterns are described, and similarities of interventions across the two professions are discussed. Ultrasound research in the realm of swallowing is sparse despite having potential clinical application in both professions. In using ultrasound, this study outlines a protocol for utilization of a hand-held probe and reinforces a particular protocol described in the literature. Real-time ultrasound recordings of swallows for 19 adult female subjects were made. Participants with orofacial myofunctional disorder are compared to a group with typical swallowing and differences in swallowing patterns are described. Three stages of the oral phase of the swallow were assigned based on ultrasonic observation of the tongue shape. Analysis involves total duration of the swallow, duration of the three stages in relation to the total duration of the swallow, and the number of swallows required for the bolus to be cleared from the oral cavity. No significant effects of either intervention were found. Swallowing patterns showed a general trend to become faster in total duration subsequent to each intervention. An unexpected finding showed significant changes in the relationship between the bolus preparation stage and the bolus transportation stage when comparing the group classified as having a single swallow and the group classified as having multiple swallows.
ContributorsMckay, Michelle Diane (Author) / Weinhold, Juliet (Thesis director) / Scherer, Nancy (Committee member) / Department of Speech and Hearing Science (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
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Description
Overexpression of AVP1 (Arabidopsis vacuolar pyrophosphatase), a type I H+ pyrophosphatase, results in greater biomass, possibly due to a function in sucrose transport within the phloem. Overexpression of the phloem lipid-associated family protein (PLAFP) was shown to increase the number of vascular bundles in Arabidopsis. Could these two phenotypes complement

Overexpression of AVP1 (Arabidopsis vacuolar pyrophosphatase), a type I H+ pyrophosphatase, results in greater biomass, possibly due to a function in sucrose transport within the phloem. Overexpression of the phloem lipid-associated family protein (PLAFP) was shown to increase the number of vascular bundles in Arabidopsis. Could these two phenotypes complement one another additively? In this work, double mutants overexpressing both AVP1 and PLAFP were characterized. These double mutants have enhanced biomass, greater leaf area, and a larger number of vascular bundles than the single mutant lines. Overexpression of PLAFP does not result in any increase in rhizosphere acidification capacity.
ContributorsWilson, Sean (Co-author) / Furstenau, Tara (Co-author) / Gaxiola, Roberto (Thesis director) / Mason, Hugh (Committee member) / Wojciechowski, Martin (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / School of Life Sciences (Contributor)
Created2014-05
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Description
This study evaluated whether the Story Champs intervention is effective in bilingual kindergarten children who speak Spanish as their native language. Previous research by Spencer and Slocum (2010) found that monolingual, English-speaking participants made significant gains in narrative retelling after intervention. This study implemented the intervention in two languages and

This study evaluated whether the Story Champs intervention is effective in bilingual kindergarten children who speak Spanish as their native language. Previous research by Spencer and Slocum (2010) found that monolingual, English-speaking participants made significant gains in narrative retelling after intervention. This study implemented the intervention in two languages and examined its effects after ten sessions. Results indicate that some children benefited from the intervention and there was variability across languages as well.
ContributorsFernandez, Olga E (Author) / Restrepo, Laida (Thesis director) / Mesa, Carol (Committee member) / Barrett, The Honors College (Contributor) / Department of Speech and Hearing Science (Contributor) / School of International Letters and Cultures (Contributor)
Created2014-05
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Description
Type I H+-PPase encoding genes, such as AVP1 (Arabidopsis thaliana), TsVP (Thellungiella halophilla), TaVP,( Triticum aestivum), and OVP1 (Oryza sativa) are highly conserved and.traditionally known to operate as vacuolar proton translocating pyrophosphatases. It is worth mentioning that Rocha-Facanha and de Meis presented in vitro evidence with tonoplast fractions of maize

Type I H+-PPase encoding genes, such as AVP1 (Arabidopsis thaliana), TsVP (Thellungiella halophilla), TaVP,( Triticum aestivum), and OVP1 (Oryza sativa) are highly conserved and.traditionally known to operate as vacuolar proton translocating pyrophosphatases. It is worth mentioning that Rocha-Facanha and de Meis presented in vitro evidence with tonoplast fractions of maize coleoptiles and seeds consistent with the reverse function of the H+-PPase (1998). These authors suggested that given the appropriate thermodynamic conditions in vivo, the H+-PPase could operate as a system of energy conservation with a role in the maintenance of cytosolic PPi levels. Further evidence in support for a PPi-synthase activity of plant H+-PPases came from work done on tonoplasts from mature oranges where PPi synthesis was demonstrated when a ΔpH of 3 units was imposed (Marsh et al. 2000).

Futher research has shown that transgenics overexpressing type I H+-PPases develop more root and shoot biomass, and have enhanced rhizosphere acidification capacity than wild types. The increased root biomass suggests that previous reports describing the response of these plants to water scarcity as drought tolerance are incomplete. Larger root systems indicate that an important component of the response is drought resistance. The enhanced rhizosphere acidification capacity has also been associated with an increase in nutrient use efficiency, conferring a growth advantage under nitrogen and phosphorous deficient conditions.
While a vacuolar localized H+-PPase easily explains the salt tolerant phenotypes, it does little to provide a mechanism for an increase in root and shoot biomass and/or an augmented rhizosphere acidification capacity. Several groups have argued that higher levels and transport of the growth hormone auxin could be responsible for the above phenotypes. An alternative model focusing on the function of a plasma membrane bound H+-PPase in sieve elements and companion cells links these phenotypes with enhanced phloem sucrose loading and transport.
The following paper reviews publications in which the H+-PPase overexpression technology has been used since 2006 in an attempt to identify cues that could help us test the compatibility of the the proposed models with the actual data.
ContributorsCoulter, Joshua (Author) / Gaxiola, Roberto (Thesis director) / Wojciechowski, Martin (Committee member) / Pizzio, Gaston (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor)
Created2014-05