Domain interactions within Fzo1 oligomers are essential for mitochondrial fusion

Mitofusins are conserved GTPases essential for the fusion of mitochondria. These mitochondrial outer membrane proteins contain a GTPase domain and two or three regions with hydrophobic heptad repeats, but little is known about how these domains interact to mediate mitochondrial fusion. To address this issue, we have analyzed the yeast mitofusin Fzo1p and find that mutation of any of the three heptad repeat regions (HRN, HR1, and HR2) leads to a null allele. Specific pairs of null alleles show robust complementation, indicating that functional domains need not exist on the same molecule. Biochemical analysis indicates that this complementation is due to Fzo1p oligomerization mediated by multiple domain interactions. Moreover, we find that two non-overlapping protein fragments, one consisting of HRN/GTPase and the other consisting of HR1/HR2, can form a complex that reconstitutes Fzo1p fusion activity. Each of the null alleles disrupts the interaction of these two fragments, suggesting that we have identified a key interaction involving the GTPase domain and heptad repeats essential for fusion

The WD40 protein Caf4p is a component of the mitochondrial fission machinery and recruits Dnm1p to mitochondria

The mitochondrial division machinery regulates mitochondrial dynamics and consists of Fis1p, Mdv1p, and Dnm1p. Mitochondrial division relies on the recruitment of the dynamin-related protein Dnm1p to mitochondria. Dnm1p recruitment depends on the mitochondrial outer membrane protein Fis1p. Mdv1p interacts with Fis1p and Dnm1p, but is thought to act at a late step during fission because Mdv1p is dispensable for Dnm1p localization. We identify the WD40 repeat protein Caf4p as a Fis1p-associated protein that localizes to mitochondria in a Fis1p-dependent manner. Caf4p interacts with each component of the fission apparatus: with Fis1p and Mdv1p through its NH2-terminal half and with Dnm1p through its COOH-terminal WD40 domain. We demonstrate that mdv1{Delta} yeast contain residual mitochondrial fission due to the redundant activity of Caf4p. Moreover, recruitment of Dnm1p to mitochondria is disrupted in mdv1{Delta} caf4{Delta} yeast, demonstrating that Mdv1p and Caf4p are molecular adaptors that recruit Dnm1p to mitochondrial fission sites. Our studies support a revised model for assembly of the mitochondrial fission apparatus

Two-sample Bayesian Nonparametric Hypothesis Testing

In this article we describe Bayesian nonparametric procedures for two-sample hypothesis testing. Namely, given two sets of samples $\mathbf{y}^{\scriptscriptstyle(1)}\;$\stackrel{\scriptscriptstyle{iid}}{\s im}$\;F^{\scriptscriptstyle(1)}$ and $\mathbf{y}^{\scriptscriptstyle(2 )}\;$\stackrel{\scriptscriptstyle{iid}}{\sim}$\;F^{\scriptscriptstyle( 2)}$, with $F^{\scriptscriptstyle(1)},F^{\scriptscriptstyle(2)}$ unknown, we wish to evaluate the evidence for the null hypothesis $H_0:F^{\scriptscriptstyle(1)}\equiv F^{\scriptscriptstyle(2)}$ versus the alternative $H_1:F^{\scriptscriptstyle(1)}\neq F^{\scriptscriptstyle(2)}$. Our method is based upon a nonparametric P\'{o}lya tree prior centered either subjectively or using an empirical procedure. We show that the P\'{o}lya tree prior leads to an analytic expression for the marginal likelihood under the two hypotheses and hence an explicit measure of the probability of the null $\mathrm{Pr}(H_0|\{\mathbf {y}^{\scriptscriptstyle(1)},\mathbf{y}^{\scriptscriptstyle(2)}\}\mathbf{)}$.Comment: Published at http://dx.doi.org/10.1214/14-BA914 in the Bayesian Analysis (http://projecteuclid.org/euclid.ba) by the International Society of Bayesian Analysis (http://bayesian.org/

Metabolomic study of the LDL receptor null mouse fed a high-fat diet reveals profound perturbations in choline metabolism that are shared with ApoE null mice

Failure to express or expression of dysfunctional low-density lipoprotein receptors (LDLR) causes familial hypercholesterolemia in humans, a disease characterized by elevated blood cholesterol concentrations, xanthomas, and coronary heart disease, providing compelling evidence that high blood cholesterol concentrations cause atherosclerosis. In this study, we used 1H nuclear magnetic resonance spectroscopy to examine the metabolic profiles of plasma and urine from the LDLR knockout mice. Consistent with previous studies, these mice developed hypercholesterolemia and atherosclerosis when fed a high-fat/cholesterol/cholate-containing diet. In addition, multivariate statistical analysis of the metabolomic data highlighted significant differences in tricarboxylic acid cycle and fatty acid metabolism, as a result of high-fat/cholesterol diet feeding. Our metabolomic study also demonstrates that the effect of high-fat/cholesterol/cholate diet, LDLR gene deficiency, and the diet-genotype interaction caused a significant perturbation in choline metabolism, notably the choline oxidation pathway. Specifically, the loss in the LDLR caused a marked reduction in the urinary excretion of betaine and dimethylglycine, especially when the mice are fed a high-fat/cholesterol/cholate diet. Furthermore, as we demonstrate that these metabolic changes are comparable with those detected in ApoE knockout mice fed the same high-fat/cholesterol/cholate diet they may be useful for monitoring the onset of atherosclerosis across animal models

Public Perceptions of the Midwest’s Pavements: Policies and Thresholds

A 5-year, pooled fund study with the Iowa, Minnesota, and Wisconsin departments of transportation assessed the public\u27s perceptions of pavement improvement strategies and developed thresholds of satisfaction using the departments\u27 physical indices, such as pavement ride and condition on rural, two-lane highways in the states. Approximately 3,600 drivers in the three states were involved in the three phases of the project, which included 18 focus groups, 400 statewide surveys in each state, and 2,300 targeted surveys across the three states. A multidisciplinary team from Marquette University and a mass media survey lab conducted the studies. A summary of focus group methods and purposes and a three-state summary of policy and improvement issues are provided. More than 450 highway segments were surveyed in Phase III, with input from 2,300 drivers through a two-step recruitment and postdrive interview. Thresholds of International Roughness Index and condition indices are summarized for the three states. The study found a high degree of trust in the three departments of transportation and public support for building longer-lasting pavements and minimizing delay. A three-step methodology is recommended for other state studies. Physical data thresholds using both public satisfaction and the agreement to improve are presented for each state\u27s physical pavement indices (ride and condition)

Public Perceptions of Wisconsin’s Pavements and Tradeoffs in Pavement Improvement

Findings are reported from Phase II of a three-phase pooled-fund project in Wisconsin, Iowa, and Minnesota to determine perceptions of drivers regarding pavement of rural two-lane highways. Among the survey topics were drivers\u27 trust in the state department of transportation (DOT), pavement improvement trade-offs, and pavement evaluation. Results of the Wisconsin portion of the survey data are the focus of this study. The survey questionnaire was based in part on Phase I focus groups conducted to gauge beliefs about pavements as well as the language describing ruts, tining, and other pavement characteristics. Phase II entailed a statewide telephone survey of at least 400 randomly selected drivers in each of the three states. Although the focus here is on Wisconsin results, survey responses across the three states were very consistent. Included in the findings discussed are perceptions of pavement and the state DOT and pavement improvement options relating to construction, travel time, and delays. Results disclose key public perceptions of priorities with regard to spending limited funds. Also discussed are statistically significant relationships providing additional insights into public perceptions and pavement improvement on rural two-lane highways

Public Perceptions of the Midwest’s Pavements - Minnesota - Executive Summary

This report summarizes Minnesota results of a five year, Pooled Fund study involving the Wisconsin, Iowa, and Minnesota DOTs designed to 1) assess the public\u27s perceptions of the departments’ pavement improvement strategies and 2) to develop customer-based thresholds of satisfaction with pavements on rural two lane highways in each state as related to the Departments’ physical indices, such as pavement ride and condition. The primary objective was to seek systematic customer input to improve the Departments’ pavement improvement policies by 1) determining how drivers perceive the departments’ pavements in terms of comfort and convenience but also in terms of other tradeoffs departments had not previously considered, 2) determining relationships between perceptions and measured pavement condition thresholds (including a general level of tolerance of winter ride conditions in two of the states), and 3) identifying important attributes and issues that may not have been considered in the past. Secondary objectives were 1) to provide a tool for systematic customer input in the future and 2) provide information which can help structure public information programs. A University of Wisconsin-Extension survey lab conducted the surveys under the direction of a multi-disciplinary team from Marquette University. Approximately 4500 drivers in the three states participated in the three phases of the project. Researchers conducted six focus groups in each state, approximately 400 statewide telephone interviews in each state and 700-800 targeted telephone interviews in each state. Approximately 400 winter ride interviews were conducted in Wisconsin and Minnesota. A summary of the method for each survey is included. In Phase I, focus groups were conducted with drivers to get an initial indication of what the driving public believes in regards to pavements and to frame issues for inclusion in the more representative state-wide surveys of drivers conducted in Phase II of the project. Phase II interviews gathered information about improvement policy trade-off issues and about preliminary thresholds of improvement in terms of physical pavement indices. In Phase III, a two-step recruitment and post-drive interview procedure yielded thresholds of ride and condition index summarized for each state. Results show that, in general, the driving public wants longer lasting pavements and are willing to pay for them. They want to minimize construction delay, improve entire sections of highway at one time but they dislike detours, and prefer construction under traffic even if it stretches out construction time. Satisfaction with pavements does not correlate directly to a high degree with physical pavement indices, but was found instead to be a complex, multi-faceted phenomenon. A psychological model (after Fishbein/Ajzen) was applied to explain satisfaction to a respectable degree (R2 of .67) for the social sciences. Results also indicate a high degree of trust in the three DOTs which is enhanced when the public is asked for input on specific highway segments. Conclusions and recommendations include a three-step methodology for other state studies. Physical data thresholds based on both public satisfaction and the agreement to improve are presented for each state\u27s physical pavement indices (ride and condition). Recommendations for changes to the quality ranges of the physical indices where appropriate are also made

Public Perceptions of the Midwest’s Pavements - Iowa - Phase III

There are several objectives to this report. The first objective is to describe the sample with regard to the physical pavement data and three measures of driver satisfaction. In this section, the proportion of respondents who are satisfied with pavements on two-lane, rural, state highways will be examined and the distribution of pavement condition and roughness indices will be presented. The second objective will be a short description of the highway segments and any differences in satisfaction found between regions and pavement types. This was done in Phase II in each state and a letter sent showing the results in all three states. That letter sets forth the revised work plan and budget for Phase III of the project. The third objective is to describe the relationship between physical pavement characteristics and driver satisfaction. This will include a description of both the magnitude of relationship as well as identifying critical International Road Index (IRI) and Pavement Condition Index (PCI) cutoffs where a majority of the sample were satisfied. This will be done for comparative purposes with the Phase II approach, using the total sample to compute cumulative percentages responding to each of the three series of satisfaction questions

Public Perceptions of the Midwest’s Pavements - Wisconsin - Executive Summary

This report summarizes Wisconsin results of a five year, Pooled Fund study involving the Wisconsin, Iowa, and Minnesota DOTs designed to 1) assess the public\u27s perceptions of the departments’ pavement improvement strategies and 2) to develop customer-based thresholds of satisfaction with pavements on rural two lane highways in each state as related to the Departments’ physical indices, such as pavement ride and condition. The primary objective was to seek systematic customer input to improve the Departments’ pavement improvement policies by 1) determining how drivers perceive the departments’ pavements in terms of comfort and convenience but also in terms of other tradeoffs departments had not previously considered, 2) determining relationships between perceptions and measured pavement condition thresholds (including a general level of tolerance of winter ride conditions in two of the states, including Wisconsin), and 3) identifying important attributes and issues that may not have been considered in the past. Secondary objectives were 1) to provide a tool for systematic customer input in the future and 2) provide information which can help structure public information programs. A University of Wisconsin-Extension survey lab conducted the surveys under the direction of a multi-disciplinary team from Marquette University. Approximately 4500 drivers in the three states participated in the three phases of the project. Researchers conducted six focus groups in each state, approximately 400 statewide telephone interviews in each state and 700-800 targeted telephone interviews in each state. Approximately 400 winter ride interviews were conducted in Wisconsin and Minnesota. A summary of the method for each survey is included. In Phase I, focus groups were conducted with drivers to get an initial indication of what the driving public believes in regards to pavements and to frame issues for inclusion in the more representative state-wide surveys of drivers conducted in Phase II of the project. Phase II interviews gathered information about improvement policy trade-off issues and about preliminary thresholds of improvement in terms of physical pavement indices. In Phase III, a two step recruitment and post-drive interview procedure yielded thresholds of ride and condition index summarized for each state. Results show that, in general, the driving public is tolerant of a poorer ride in Winter and they understand the cause. The driving public wants longer lasting pavements and are willing to pay for them. They want to minimize construction delay, improve entire sections of highway at one time but they dislike detours, and prefer construction under traffic even if it stretches out construction time. Satisfaction with pavements does not correlate directly to a high degree with physical pavement indices, but was found instead to be a complex, multi-faceted phenomenon. A psychological model (after Fishbein/Ajzen) was applied to explain satisfaction to a respectable degree (R2 of .7) for the social sciences. Results also indicate a high degree of trust in the three DOTs which is enhanced when the public is asked for input on specific highway segments. Conclusions and recommendations include a three-step methodology for other state studies. Physical data thresholds based on both public satisfaction and the agreement to improve are presented for each state’s physical pavement indices (ride and condition). Recommended changes to the quality ranges of the physical indices where appropriate are also made