Main Effect Of Strain Research Articles

Effects of Rhizobium Inoculation and P Fertilizer Levels on Selected Soil Properties, Yield, and Yield Components of Faba Bean (Vicia faba L.): The Case of Abuna Gindeberat, West Shewa Zone, Ethiopia

Poor soil fertility status and inappropriate agronomic practices are the major factors for low crop productivity like legumes. Thus, the experiment was conducted to evaluate the effect of the P fertilizer rate and rhizobium inoculation on selected soil properties and yield of faba bean. In order to achieve this objective, a field experiment was laid out in a randomized complete block design in a factorial arrangement with replication. The treatments consisted of five P levels (0, 23, 46, 69, and 92 kg P2O5 ha−1) and two rhizobium inoculants (Fb17 and Fb18). Faba bean (Moti variety) was used as the test crop. Soil samples were collected before and after planting for laboratory analysis. All soil and agronomic data were subjected to the analysis of variance (ANOVA) using statistical analysis software version 9.2. The main effect of strain positively improved soil porosity, but soil bulk density was negatively influenced. Soil chemical parameters such as organic carbon, total N, available P, available sulfur, Ca, Mg, and K were positively influenced. The interaction effects of the P fertilizer rate and rhizobium inoculation significantly influenced organic carbon, total N, available P, and yield parameters (pod per plant, numbers of nodules per plant, biomass yield, straw yield, and grain yields). The combined application of 69 kg P2O5 ha−1 and Fb18 rhizobium inoculants gave the highest grain yield (4.4 t ha−1) of faba bean. Thus, the integrated application of strain and P2O5 fertilizer improved soil fertility and faba bean crop yield. Therefore, reducing soil fertility constrains of the soils through the integrated application of strain and P2O5 fertilizer could be a possible option to reduce the yield gap seen between smallholder farmers and experimental fields. So as to maintain soil fertility and sustain faba bean crop production, farmers of the study area are advised to make integrated use of strain type Fb18 and P2O5 fertilizer at 69 kg/ha−1 with appropriate agronomic practices.

Breathing and Respiratory Muscle Function in Senescent Wild‐type and Ts65Dn Male Mice

Down Syndrome (DS) results from trisomy 21 and is the most common cause of mental retardation in the US. People with DS display reduced muscle tone and cardiorespiratory complications that may contribute to breathing disturbances. Ts65Dn (Ts) mice, a model of DS, exhibit increased apnea frequency at 3 months of age (7±9 vs. 36±28; wild‐type (WT) vs. Ts) that persists at 6 (19± 7 vs. 77±58) and 12 months (5±6 vs. 64±77; p<0.001 for age, strain, and age by strain). People with DS have increased life expectancy and it is unknown how breathing changes across the lifespan in this population. We tested the hypothesis that ~20‐month‐old Ts mice would have altered ventilation compared to age‐matched WT mice. To test this hypothesis, unrestrained barometric plethysmography was used to quantify breathing frequency (breaths/min), tidal volume (VT; mL), VT/inspiratory time (VT/Ti; mL/sec), minute ventilation (VE; mL/min) and ventilatory equivalent for CO2 (VE/VCO2) in 18 to 22‐month‐old male WT (n=12) and Ts (n=13) mice. Data Sciences International Ponemah software was used to analyze flow tracings during exposure to air (20.93% O2, balanced N2). Data are expressed as mean±S.D., WT vs. Ts. A main effect of strain was uncovered using MANOVA (p=0.033). Breathing frequency (171±33 vs. 136±41 breaths/min; p=0.025) and VE (74.6±25.7 vs. 50.3±15.5 mL/min; p=0.010) approached the a priori cutoff (Bonferroni correction, p<0.01). VT (0.439±0.112 vs. 0.377±0.075 mL/breath; p=0.123) and the ratio of VE/VCO2 (45.5 ±22.0 vs. 42.4±19.8; p=0.715) were not different. VT/Ti (3.65±1.03 vs. 2.49±0.759 mL/sec; p=0.004) was reduced in Ts vs. WT, which suggests Ts mice have a reduced ventilatory drive. Since people with DS demonstrate evidence of muscle weakness, we examined diaphragm (DIA) and sternohyoid (SH; representative pharyngeal dilator) muscle function in WT (DIA n=10, SH n=9) and Ts (DIA n=7, SH n=7) mice. Twitch (2.2±1.1 vs 2.3±1.0 N/cm2; p=0.835) and tetanic (11.2±7.3 vs. 11.6±4.8 N/cm2; p=0.900) force, and the force frequency‐relationship (p=.766) for SH muscle were equivalent between groups. Similarly, no differences were observed for DIA twitch (6.0±2.7 vs. 5.2±2.1 N/cm2; p=0.438) and tetanic (20.7±6.0 vs. 19.9±2.8 N/cm2; p=0.758) force, or the force‐frequency relationship (p=0.339). Diaphragm function was preserved in aged Ts mice which is in line with similar VT between groups. These data reveal the increased propensity for apnea in Ts mice is independent of upper airway muscle weakness and may alternatively be of neural origin. Current studies are examining motor control of the upper airway in Ts mice.Support or Funding InformationThis work was funded by 1R15HD076379 (LRD), 3R15HD076379 (LRD). Additional support was granted by the Le Moyne College McDevitt Center Undergraduate Research Fellowship in Natural Science (MS‐N, MR), and the Le Moyne College Biological Sciences Department.

Effect of Mouse Strain on Dietary CLA and Coconut Oil‐Induced Lipolysis

Dietary conjugated linoleic acid (CLA)‐induced lipolysis and body fat loss are enhanced in mice fed coconut oil (CO); however, differences between mouse strains have been observed. This study was designed to evaluate the response to CLA and oil source in 4 common mouse strains. Male CF‐1, ICR, NIH, and Swiss Webster mice (3‐wk‐old, n = 24 per strain) were fed diets containing either soy oil (SO) or CO for 6 weeks, followed by 0 or 0.5% CLA (replacing base oil w/w) for 12 days. Tissue weights were measured for the calculation of a body fat index (BFI): epididymal + retroperitoneal fat pads/body weight*100. Epididymal and retroperitoneal fat pads were pooled and used for ex vivo lipolysis analysis and real time RT‐PCR. We detected an oil*CLA interaction (P = 0.03) on BFI where SO‐fed mice were the fattest and CO+CLA‐fed mice were the leanest, and a main effect of strain (P < 0.001) where Swiss Webster mice were the fattest and NIH mice the leanest, but no diet by strain interactions. Lipolysis was stimulated by both CO (P < 0.001) and CLA (P = 0.002) with no effect of strain. No differences in the mRNA expressions of UCP1, UCP2, UCP3, or CPT1 were detected but UCP1 expression was positively correlated (r = 0.26, P = 0.01) with lipolysis. As expected, the BFI was negatively correlated (r = ‐0.43, P < 0.001) with lipolysis but positively correlated (r = 0.35, P = 0.001) with serum NEFA. In conclusion, we found that mouse strain does not significantly impact the response to CLA and/or CO and no evidence of increased UCP expression in the adipose tissue of CLA‐fed mice.

Sexual dimorphism of vascular mechanics in rats

The purpose of this study was to test the hypotheses that male and female rats would exhibit dimorphic mechanical properties of the hindlimb vasculature and that these differences would persist in hypertension. Vascular resistance (R), compliance (C), and tissue viscoelasticity (K) of the hindlimb vascular bed were quantified from concurrent femoral artery blood flow and pressure waveforms (lumped Windkessel model) in age‐matched Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR) male (n=10 each) and female (n=6 each). Female WKY rats displayed greater R (15.4±5.7 vs 7.7±3.3mmHg/mL/min; P<0.05) and K (3.4±2.4 vs 1.1±2.7mmHg/mL/min; P<0.05) with lower C (3.4E‐3±0.8E‐3 vs 4.9E‐3±0.9E‐3mL/mmHg/g; P<0.05) compared to males, respectively. Similarly, female SHRs had higher R (31.5±8.5 vs 17.6±7.8mmHg/mL/min; P<0.05) and K (7.3±2.5 vs 2.9±1.0mmHg/mL/min; P<0.05) with lower C (4.8E‐3±2.0E‐3 vs 6.8E‐3±3.5E‐3mL/mmHg/g; P<0.05) than their male counterparts. Main effects of strain and sex were observed for each of R, K and C variables (all P<0.05). Therefore, sex differences are apparent in the indices of steady state (R) and oscillatory (K and C) hindlimb vascular mechanics and these persist in hypertension.Supported by CIHR.

Interactive effects of age, sex, and strain on apparent ileal amino acid digestibility of soybean meal and an animal by-product blend in broilers

The objectives of this study were to determine if age, sex, and strain of broilers affect the apparent ileal amino acid digestibility (AID) of soybean meal and an animal by-product blend. Chicks from 2 broiler strains, 1 commercially available and the other in the test phase, were obtained from a common hatchery, feather-sexed, and placed into floor pens. The birds received common diets while on floor pens. Birds were transferred to metabolism crates for 2 ileal digestibility trials conducted at 3 and 6 wk of age. Two semipurified diets were formulated with each of the feed ingredients providing all of the amino acids (AA) in the diets. Diets were formulated to contain 20% CP, with chromic oxide added to the diet at 0.30% as the indigestible marker. The experimental diets were fed for a 72-h period after an overnight fast to 8 replicate cages of 5 birds per cage. Upon completion of the experimental periods (i.e., d 22 and 43), birds were euthanized and ileal digesta samples were collected and pooled by pen, frozen, lyophilized, and analyzed for AA and chromium concentrations. For soybean meal, no main effects were observed for age, sex, or strain; however, significant (P ≤ 0.05) 3-way interactions were observed for several dispensable and indispensable AA. Statistical analyses of these interactions indicate the AID of soybean meal may be different for 42-d males of the test strain. For the animal by-product blend, only main effects were significant for each AA, with the exception of Ile and Tyr. Main effect of strain was observed for most of the AA, showing that the commercially available strain had higher AID than the test strain. Also, significant main effect of age indicated that the AID for animal by-product blend was higher at 42 d than at 21 d. Evaluation of these 2 ingredients showed that age, sex, and strain may affect digestibility of feedstuffs and should be considered independently or interactively, for some cases, in future investigations as sources of variation in AA digestibility.

First principles calculation of electron-phonon and alloy scattering in strained SiGe

First-principles electronic structure methods are used to predict the mobility of n-type carrier scattering in strained SiGe. We consider the effects of strain on the electron-phonon deformation potentials and the alloy scattering parameters. We calculate the electron-phonon matrix elements and fit them up to second order in strain. We find, as expected, that the main effect of strain on mobility comes from the breaking of the degeneracy of the six Δ and L valleys, and the choice of transport direction. The non-linear effects on the electron-phonon coupling of the Δ valley due to shear strain are found to reduce the mobility of Si-like SiGe by 50% per % strain. We find increases in mobility between 2 and 11 times that of unstrained SiGe for certain fixed Ge compositions, which should enhance the thermoelectric figure of merit in the same order, and could be important for piezoresistive applications.

Strain differences in delay discounting using inbred rats

A heightened aversion to delayed rewards is associated with substance abuse and numerous other neuropsychiatric disorders. Many of these disorders are heritable, raising the possibility that delay aversion may also have a significant genetic or heritable component. To examine this possibility, we compared delay discounting in six inbred strains of rats (Brown Norway, Copenhagen, Lewis, Fischer, Noble and Wistar Furth) using the adjusting amount procedure, which provides a measure of the subjective value of delayed rewards. The subjective value of rewards decreased as the delay to receipt increased for all strains. However, a main effect of strain and a strain x delay interaction indicated that some strains were more sensitive to the imposition of delays than others. Fitting a hyperbolic discount equation showed significant strain differences in sensitivity to delay (k). These data indicate that there are significant strain differences in delay discounting. All strains strongly preferred the 10% sucrose solution (the reinforcer in the delay discounting task) over water and the amount of sucrose consumed was correlated with sensitivity to delay. Locomotor activity was not correlated with delay discounting behavior. Additional research will be required to disentangle genetic influences from maternal effects and to determine how these factors influence the underlying association between heightened delay discounting and neuropsychiatric disorders.

Effects of Azoxystrobin on Mycotoxin Production in a Carbendazim-Resistant Strain ofFusarium sporotrichioides

Carbendazim-resistant (RS) and control (CS) strains ofFusarium sporotrichioides Sherb., previously developed in our laboratory, were exposed to graded concentrations of azoxystrob in in broth media under shake-culture conditions for 2, 3, 4 and 8 days. Azoxystrobin concentrations were 0, 1, 10 and 100 mg 1-1 broth and cultures were incubated at a constant 25°C. Mycelial growth was significantly affected by strain (P 0.05) at all three doses of azoxystrobin. Significant (P<0.05 or better) strain-fungicide interactions were recorded in trichothecene production following exposure to azoxystrobin. At 4 and 8 days of incubation, the 10 mg 1-1 addition of azoxystrobin stimulated T-2 toxin synthesis (P<0.05) only in RS cultures. In contrast, T-2 toxin enhancement in CS cultures occurred only on day 8 but at a lower level of azoxystrobin (1 mg1-1). Thus, the stimulation of T-2 toxin synthesis depended upon strain and azoxystrobin level. Production of diocetoxyscirpenol (DAS) was affected by a more complex set of interactions. Overall means showed that, in comparison with initial values (on day 2 or 3), DAS output maximized significantly(P<0.05) on day 4 in RS cultures and on day 8 in CS. Marked strain effects were observed on exposure to the 10 mg 1-1 level of azoxystrobin. At this level, DAS production was enhanced in RS only after 4 (P<0.01 ) and 8 (P<0.05) days of incubation, while in contrast, CS reduced DAS production. As with T-2 toxin, DAS production in CS was stimulated (P<0.05 or better) only at low exposure levels of azoxystrobin. In the case of neosolaniol (NEO), however, the main effect of strain was significant (P<0.05), with CS producing consistently more of the mycotoxin than RS on day 4 of the experiment. At this point, the NEO:T-2 toxin ratio was also higher in CS (0.63) than in RS (0.12), a feature reported by us previously. In conclusion, the present investigation has shown for the first time that the development of resistance to one fungicide can affect trichothecene production inF. sporotrichioides on exposure to a second fungicide. These results have been incorporated into a new classification scheme for fungicide efficacy which is also presented in this paper.

Gestational retinoic acid exposure in the rat: effects of sex, strain and exposure period

Effects of gestational exposure to all- trans retinoic acid (RA) were assessed in the Long–Evans (hooded) and Sprague–Dawley (albino) rat strains. Two exposure periods were evaluated against vehicle controls. Both involved three consecutive daily per os doses of either 2.5 mg/kg RA on gestational days (GD) 11 through 13 or 10 mg/kg RA on GD 14 through 16. All assessments were conducted on at least one male and one female per litter. Substantial main effects of sex, strain and treatment were obtained, but with few significant interactions. Main effects of strain were found on surface righting, neonatal mortality, litter weight and postnatal day (PND) 35 regional brain weight. Among strain effects, the most interesting was the finding that weights of whole brain, frontal cortex, brainstem and cerebellar vermis were lower in hooded than in albino rats. These strain effects seldom interacted with treatment. Among the treatment effects was the finding that GD 11–13 but not GD 14–16 RA exposure impaired the righting reflex in both strains. Moreover, GD 11–13 exposure reduced weight of the cerebellar vermis more than did GD 14–16 RA exposure, while GD 14–16 RA exposure had greater impact on the weight of the cerebellar hemispheres than did GD 11–13 exposure. Covariate analysis suggested that these effects were independent of reductions in body weight. It is concluded that there are few strain or sex differences in the effects of gestational RA exposure, at least for the rat strains evaluated in this study.

Missing data in two-way analysis of variance

We previously described a regression approach to analysis of variance computations that permitted analysis of unbalanced designs and experiments with missing data in two-way (or higher) analyses of variance Am. J. Physiol. 255 (Regulatory Integrative Comp. Physiol. 24): R353-R367, 1988. That approach can only be used correctly under a set of narrow, and relatively uninteresting, circumstances. In fact, in the example we worked, we extended that approach beyond its intended scope and incorrectly computed F statistics for testing hypotheses about the main effects of strain of rat and nephron site in a study of renal Na(+)-K(+)-adenosinetriphosphatase. This paper presents the correct approach, which can be generalized to most situations likely to be encountered when two-way, or higher, analyses of variance are used.

Periodicity of Wheel-Running Activity in Mice in Relation to Light-Dark Cycle; I. Strain and Age Differences

Male mice of 4 strains (C57BL/6, DBA/2, C3H/He, and I20/Se) were individually run for 24 hr in home cages with an activity wheel under normal (LD) and reversed (DL) conditions of light-dark cycle. LD condition was in light from 08 : 30 to 20 : 30, and DL condition was in light from 20 : 30 to 08 : 30, alternating with 12 hr of darkness in each condition. Brightness in the light period was about 330 lux. Each strain consisted of 4 groups (3, 5, 7, and 9 weeks of age at the beginning of the experiment) of 10 mice.As shown in Figures 1 and 2, the onset of the activities of mice in LD condition, as compared with those in DL condition, synchronized with their transition from light-on to light-off. Especially, those of the mice of DBA and I20 strains synchronized markedly. Moreover, it can be observed in the mice of all strains that transition from light-off to light-on in the time of night has a drifting effect on the onset of activity.Transformed data on the total activity for 24 hr shown in Table 1 were analyzed by 3-factorial analysis of variance. Significant values of F were obtained only in the main effects of strain (F=6. 314, df=3/288), conditions of light-dark cycle (F=13. 904, df=1/288), and age (F=3. 931, df=3/288). It can be observed from Table 2 that there are very clear differences among strains of mice in the alternation of the active and inactive periods synchronized with light-dark cycle. From these results it is suggested that the activities of DBA and I20 mice synchronize with light-dark cycle of both conditions, whereas the activities of C57BL and C3H mice do not so much synchronize with those conditions. The age-related activity changes could not be observed in the present study.We conclude from these results that the activity synchronizes with a light-dark cycle, and thus periodicity of the activity is achieved by onset response to light-off and drifting response to light-on. However, further researches are needed to determine whether the 24 hr-periodicity of activity is controlled either by light-dark cycle or by a circadian rhythmic clock.

Heart rate conditioning in mice.

Two strains of highly inbred mice were given classical conditioning with noise as CS and shock as US. Control groups for pseudoconditioning were included, and heart rate was measured before and after conditioning. Heart rate was elevated after conditioning (p<0.01) but without evidence of classical conditioning. The control procedure increased heart rate more than the classical procedure (p<0.02), indicating an anxious response, independent of the pseudoconditioned stimulus, which complicates use of this procedure as control in studying classical conditioning. The extent of the anxious response varied with strain (p=0.02). There was also a significant (p<0.01) main effect of strain on heart rate.

Spontaneous Alternation with and Without Reward in Hooded and Albino Rats

Spontaneous alternation was investigated with and without food reward in hooded and albino rats by means of a 2 × 2 factorial design with 18 Ss per cell. Neither the main effects of strain and reward nor the trend over successive trials were statistically significant. However, the interaction of strain × reward was significant, reflecting significantly more alternations by rewarded Ss within the hooded strain but a nonsignificant difference in the opposite direction within the albinos. A significant strain × training interaction probably reflected a greater decline in alternations with training by the albinos.