Gemechis D. Djira

Abiotic stresses modulate expression of major intrinsic proteins in barley (Hordeum vulgare)

In one of the most important crops, barley (Hordeum vulgare L.), gene expression and physiological roles of most major intrinsic proteins (MIPs) remained to be elucidated. Here we studied expression of five tonoplast intrinsic protein isoforms (HvTIP1;2, HvTIP2;1, HvTIP2;2, HvTIP2;3 and HvTIP4;1), a NOD26-like intrinsic protein (HvNIP2;1) and a plasma membrane intrinsic protein (HvPIP2;1) by using the quantitative real-time RT-PCR. Five-day-old seedlings were exposed to abiotic stresses (salt, heavy metals and nutrient deficiency), abscisic acid (ABA) and gibberellic acid (GA) for 24 h. Treatment with 100 mM NaCl, 0.1 mM ABA and 1 mM GA differentially regulated gene expression in roots and shoots. Nitrogen and prolonged P-deficiency downregulated expression of most MIP genes in roots. Intriguingly, gene expression was restored to the values in the control three days after nutrient supply was resumed. Heavy metals (0.2 mM each of Cd, Cu, Zn and Cr) downregulated the transcript levels by 60-80% in roots, whereas 0.2 mM Hg upregulated expressions of most genes in roots. This was accompanied by a 45% decrease in the rate of transpiration. In order to study the physiological role of the MIPs, cDNA of three genes (HvTIP2;1, HvTIP2;3 and HvNIP2;1) have been cloned and heterologous expression was performed in Xenopus laevis oocytes. Osmotic water permeability was determined by a swelling assay. However, no water uptake activity was observed for the three proteins. Hence, the possible physiological role of the proteins is discussed.

Expression of estrus before fixed-time AI affects conception rates and factors that impact expression of estrus and the repeatability of expression of estrus in sequential breeding seasons

Expression of estrus after PG and before fixed-time AI has been reported to change the uterine environment, increase accessory sperm numbers, fertilization rates, and overall embryo survival. Thus, expression of estrus can strongly impact overall pregnancy success. Because of variation in percentage of beef females detected in estrus and number of animals per study, it can be difficult to detect a significant effect of estrus on pregnancy success. Thus, a meta-analysis was conducted using data from 10,116 beef females in 22 studies that utilized variations of the 5 most common fixed-time AI protocols (CO-Synch, 7-day CO-Synch+CIDR, 5-day CIDR, PG 6-day CIDR, and the 14-day CIDR protocols) to examine the effect of detection in standing estrus on subsequent fixed-time AI pregnancy success. A random-effects model was used to combine the studies/herds. The overall model indicated a positive effect of estrus on conception rates with cows detected in estrus before fixed-time AI having a 27% greater (P<0.05; 95% CI=22-32%) conception rate compared with those not detected in estrus. Next we determined factors that influenced expression of estrus. Data were available on 547 cows synchronized with a CIDR based fixed-time AI protocols and observed for estrus before AI during 2-4 breeding seasons. Analysis of these cows indicated that days postpartum (P=0.22) did not impact estrous expression. In contrast, BCS influenced estrous expression (P=0.04) with cows in a BCS of ≤4 (51±5%) having decreased expression of estrus compared to cows with a BCS>4 (≥70±4%). Initiation of estrous cycles before the breeding season also influenced estrous expression (P=0.03), with anestrous cows having greater expression of estrus compared with estrus-cycling cows (78±5% vs. 70±5%, respectively). In conclusion, among all currently recommended fixed-time AI protocols, cows detected in estrus before fixed-time AI had improved conception rates, with BCS and estrus-cycling status having the greatest influence on expression of estrus.

Prevalence of thermoduric bacteria and spores in nonfat dry milk powders of Midwest origin

Samples of nonfat dry milk powder were analyzed for the presence of heat-resistant bacteria. The samples were collected from Midwest manufacturing companies and were evaluated for the presence of spores, thermoduric bacteria, and the total bacterial count. Three companies were included in this study, and results showed differences between each of the companies in the heat-resistant microbial groups tested. Company 3 had the highest levels of total spores and thermoduric bacteria: 3.6±0.14 and 3.5±0.13 log cfu/g, respectively. Interestingly, this company did not have the highest total bacterial count but rather the second lowest total bacterial count for the group, perhaps because of the higher proportion of thermophiles present in the powders from this company. The average level of total bacterial counts was 2.57±0.07 log cfu/g. Isolates obtained from the samples were identified by mass spectrometry, and all of the companies showed Bacillus licheniformis as the most prevalent bacterial species identified.

Relative Potency Estimation in Parallel-Line Assays - Method Comparison and Some Extensions

Relative potency estimations in both multiple parallel-line and slope-ratio assays involve construction of simultaneous confidence intervals for ratios of linear combinations of general linear model parameters. The key problem here is that of determining multiplicity adjusted percentage points of a multivariate t-distribution, the correlation matrix R of which depends on the unknown relative potency parameters. Several methods have been proposed in the literature on how to deal with R . In this article, we introduce a method based on an estimate of R (also called the plug-in approach) and compare it with various methods including conservative procedures based on probability inequalities. Attention is restricted to parallel-line assays though the theory is applicable for any ratios of coefficients in the general linear model. Extension of the plug-in method to linear mixed effect models is also discussed. The methods will be compared with respect to their simultaneous coverage probabilities via Monte Carlo simulations. We also evaluate the methods in terms of confidence interval width through application to data on multiple parallel-line assay.

Longitudinal effects of fat and lean mass on bone accrual in infants

There are conflicting reports on the influence of lean and fat mass on bone accrual during childhood. No infants studies have been reported that describe the influence of changes in body composition with changes in bone accrual during the first year of life. The objective of this research was to test the hypothesis that greater gains in lean mass will have a positive effect on bone mineral content (BMC) accrual, while greater gains in fat mass will have a negative effect on BMC accrual in infants. Longitudinal data from 3 previous infant studies were used. Linear mixed models, adjusting for age, sex, dietary calcium, and length were used to investigate longitudinal and cross-sectional associations between total body BMC and lean and fat mass in the individual studies and in a combined analysis. In both individual and combined analyses, we found that lean and fat mass were positively associated with whole body BMC accrual (all, P<0.001). The cross-sectional association of BMC and dietary calcium was negative in one study (P<0.05). No differences in BMC change between sexes were observed in three studies. Our results showed positive cross-sectional and longitudinal associations between total body BMC and lean mass in infants. In contradiction to our hypothesis for fat mass, we found a positive cross-sectional and longitudinal association between total body BMC and fat mass in infants.

Modeling the Effect of Temperature and Precipitation on Crop Residue Potential for the North Central Region of the United States

In an effort to advance fuel security in this era of increasing fuel demand and climate change, crop residue can play an important role by serving as an alternative source of biofuel feedstock. Crop grain yield and residue production are tied to the changing climate over regional and global scale. Precipitation and temperature are among the prime climate variables that drive agricultural production across the globe. This study was carried out to understand the effect of temperature and precipitation on spatial distribution of crop residue yield potential at regional scale. Spatial autoregressive models were fitted for county level crop residue yield potential (as a major potential biomass feedstock) in the north central region of the United States using daily mean temperature and total precipitation during the crop growing season. The results of this observational study found the linear increasing trend in crop residue yield potential in most of the states across north central region of USA. Crop residue potential was also identified to have significant spatial variability. The influences of temperature and precipitation on crop residue yield potential exhibited significant interactions. Positive interaction effects were observed in states including Iowa, North Dakota, and Wisconsin. Negative interaction effects of daily mean temperature and total precipitation were observed in states including Illinois and Indiana. These results emphasize that the availability of crop residues for biofuels feedstocks will be sensitive to climatic variability and that these sensitivities will vary geographically.

Analyzing Factors Influencing Teaching as a Career Choice Using Structural Equation Modeling

The purpose of the study is to analyze factors influencing students’ perceptions of teaching as a career choice using structural equation modeling with the goal of shaping a teacher education recruitment program. In this study, 458 students from a Midwestern university in the United States responded to an online survey about career-related factors they value, their expectation that teaching would offer those factors, and any social-influence factors that might encourage them to choose a teaching career. The effect of 10 exogenous motivation variables (value-environment, value-intrinsic, value-extrinsic, value-altruistic, expectancy-environment, expectancy-intrinsic, expectancy-extrinsic, social-media-education, social-prior-experience, and social-suggestions) on choosing a teaching career was examined. Results of our analysis showed that the factors related to expectancy-environment, expectancy-intrinsic, social-media-education, social-prior-experience, and social-suggestions were found to be significant, whereas value-related factors and expectancy-extrinsic factors were found to be insignificant.

Structural equation modeling for analyzing erythrocyte fatty acids in Framingham.

Research has shown that several types of erythrocyte fatty acids (i.e., omega-3, omega-6, and trans) are associated with risk for cardiovascular diseases. However, there are complex metabolic and dietary relations among fatty acids, which induce correlations that are typically ignored when using them as risk predictors. A latent variable approach could summarize these complex relations into a few latent variable scores for use in statistical models. Twenty-two red blood cell (RBC) fatty acids were measured in Framingham (N = 3196). The correlation matrix of the fatty acids was modeled using structural equation modeling; the model was tested for goodness-of-fit and gender invariance. Thirteen fatty acids were summarized by three latent variables, and gender invariance was rejected so separate models were developed for men and women. A score was developed for the polyunsaturated fatty acid (PUFA) latent variable, which explained about 30% of the variance in the data. The PUFA score included loadings in opposing directions among three omega-3 and three omega-6 fatty acids, and incorporated the biosynthetic and dietary relations among them. Whether the PUFA factor score can improve the performance of risk prediction in cardiovascular diseases remains to be tested.

Perceptions of equid well being in South Dakota

ABSTRACT In South Dakota, the status of equid well being is relatively unknown. This study sought to (a) gain understanding about the current perceptions of nonhuman animal well being in South Dakota, with an emphasis on horses and other equids; (b) determine the level of care equids are reportedly receiving and the perceived challenges to equine well being in South Dakota, and (c) determine if people from diverse geographical locations (east or west of the Missouri River) have similar views on the well being of equids in South Dakota. Respondents indicated the current level of equid well being in South Dakota is sufficient, but there is room for improvement. Current challenges for the equid population of South Dakota were the high annual cost of horse care, poor horsemanship, dental problems, and whether caregivers understand basic equine care. Several significant associations arose between where a respondent lives (Western or Eastern South Dakota) and their level of agreement with various statements. The results provide a benchmark to gauge well being and help give direction for future educational needs that can continue to improve equid care.

Simultaneous Confidence Intervals for Ratios of Fixed Effect Parameters in Linear Mixed Models

In multiple comparisons of fixed effect parameters in linear mixed models, treatment effects can be reported as relative changes or ratios. Simultaneous confidence intervals for such ratios had been previously proposed based on Bonferroni adjustments or multivariate normal quantiles accounting for the correlation among the multiple contrasts. We propose Fieller-type intervals using multivariate t quantiles and the application of Markov chain Monte Carlo techniques to sample from the joint posterior distribution and construct percentile-based simultaneous intervals. The methods are compared in a simulation study including bioassay problems with random intercepts and slopes, repeated measurements designs, and multicenter clinical trials.