QTLs associated with dry matter intake,metabolic mid-test weight,growth and feed efficiency have little overlap across 4 beef cattle studies

Background

The identification of genetic markers associated with complex traits that are expensive to record such as feed intake or feed efficiency would allow these traits to be included in selection programs. To identify large-effect QTL, we performed a series of genome-wide association studies and functional analyses using 50 K and 770 K SNP genotypes scored in 5,133 animals from 4 independent beef cattle populations (Cycle VII, Angus, Hereford and Simmental × Angus) with phenotypes for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake.

Results

A total of 5, 6, 11 and 10 significant QTL (defined as 1-Mb genome windows with Bonferroni-corrected P-value <0.05) were identified for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake, respectively. The identified QTL were population-specific and had little overlap across the 4 populations. The pleiotropic or closely linked QTL on BTA 7 at 23 Mb identified in the Angus population harbours a promising candidate gene ACSL6 (acyl-CoA synthetase long-chain family member 6), and was the largest effect QTL associated with dry matter intake and mid-test body weight explaining 10.39% and 14.25% of the additive genetic variance, respectively. Pleiotropic or closely linked QTL associated with average daily gain and mid-test body weight were detected on BTA 6 at 38 Mb and BTA 7 at 93 Mb confirming previous reports. No QTL for residual feed intake explained more than 2.5% of the additive genetic variance in any population. Marker-based estimates of heritability ranged from 0.21 to 0.49 for residual feed intake across the 4 populations.

Conclusions

This GWAS study, which is the largest performed for feed efficiency and its component traits in beef cattle to date, identified several large-effect QTL that cumulatively explained a significant percentage of additive genetic variance within each population. Differences in the QTL identified among the different populations may be due to differences in power to detect QTL, environmental variation, or differences in the genetic architecture of trait variation among breeds. These results enhance our understanding of the biology of growth, feed intake and utilisation in beef cattle.     

Multivalent DNA and nucleosome acidic patch interactions specify VRK1 mitotic localization and activity

A key role of chromatin kinases is to phosphorylate histone tails during mitosis to spatiotemporally regulate cell division. Vaccinia-related kinase 1 (VRK1) is a serine–threonine kinase that phosphorylates histone H3 threonine 3 (H3T3) along with other chromatin-based targets. While structural studies have defined how several classes of histone-modifying enzymes bind to and function on nucleosomes, the mechanism of chromatin engagement by kinases is largely unclear. Here, we paired cryo-electron microscopy with biochemical and cellular assays to demonstrate that VRK1 interacts with both linker DNA and the nucleosome acidic patch to phosphorylate H3T3. Acidic patch binding by VRK1 is mediated by an arginine-rich flexible C-terminal tail. Homozygous missense and nonsense mutations of this acidic patch recognition motif in VRK1 are causative in rare adult-onset distal spinal muscular atrophy. We show that these VRK1 mutations interfere with nucleosome acidic patch binding, leading to mislocalization of VRK1 during mitosis, thus providing a potential new molecular mechanism for pathogenesis.     

Biochemistry of nitrate respiration in Pseudomonas stutzeri. I. Aerobic and nitrate respiration routes of carbohydrate catabolism

Spangler, W. J. (Oregon State University, Corvallis), and C. M. Gilmour. Biochemistry of nitrate respiration in Pseudomonas stutzeri. I. Aerobic and nitrate respiration routes of carbohydrate catabolism. J. Bacteriol. 91:245-250. 1966.-The metabolic pathways of glucose catabolism were studied in Pseudomonas stutzeri under aerobic conditions and under conditions of nitrate respiration. Studies on both glucose and gluconate catabolism, by the radiorespirometric method, indicated that these substrates are degraded in the same manner, i.e., the Entner-Doudoroff and pentose phosphate pathways. There appeared to be no major shift in primary metabolic pathways when nitrate was used as the terminal hydrogen acceptor in nitrate respiration as opposed to aerobic respiration with free molecular oxygen. It was shown that glucose is not degraded to any appreciable extent under anaerobic conditions in the absence of nitrate. Tentative evidence suggests that the tricarboxylic acid cycle functions under both conditions of oxygen relationships and that the rate of carbon oxidation via the tricarboxylic acid cycle is slower with nitrate respiration than under aerobic conditions.     

Low‐carbohydrate High‐fat Diets: Regulation of Energy Balance and Body Weight Regain in Rats

The aim of the current investigations was to examine the effects of a low‐carbohydrate high‐fat diet (LC‐HFD) on body weight, body composition, growth hormone (GH), IGF‐I, and body weight regain after stopping the dietary intervention and returning the diet back to standard laboratory chow (CH). In study one, both adolescent and mature male Wistar rats were maintained on either an isocaloric LC‐HFD or CH for 16 days before having their diet switched. In study two, mature rats were maintained on either LC‐HFD or CH for 16 days to determine the effects of the LC‐HFD on fat pad weight. LC‐HFD leads to body weight loss in mature rats (P < 0.01) and lack of body weight gain in adolescent rats (P < 0.01). Despite less body weight, increased body fat was observed in rats maintained on LC‐HFD (P < 0.05). Leptin concentrations were higher (P < 0.05), and IGF‐I (P < 0.01) concentrations were reduced in the LC‐HFD rats. When the diet was returned to CH following LC‐HFD, body weight regain was above and beyond that which was lost (P < 0.01). The LC‐HFD resulted in increased body fat and had a negative effect upon both GH and IGF‐I concentrations, which might have implications for the accretion and maintenance of lean body mass (LBM), normal growth rate and overall metabolic health. Moreover, when the LC‐HFD ceases and a high‐carbohydrate diet follows, more body weight is regained as compared to when the LC‐HFD is consumed, in the absence of increased energy intake.     

Dynamic properties of polyelectrolyte calcium membranes

Summary Shashoua observed spontaneous oscillations in a polyelectrolyte membrane formed by interfacial precipitates of polyacid and polybase. We have here undertaken experimental and theoretical studies of polyglutamic acid-Ca⁺⁺ membrane in order to clarify the processes involved in this dynamic behavior. We find a region of distinct hysteresis in the voltage current curve for this system. A sharp transition from a state of low membrane resistance to one of high resistance occurs at a current density different from that of inverse transition.This membrane system is modeled as a two layer structure: a negatively charged layer made of ionized polyelectrolyte in series with a neutral region in which the polymeric ionic sites are masked by calcium ion. This structure results in a difference in the transference number for the mobile ions, causing salt accumulation at the interfacial region during a current flow in the to direction. This altered salt concentration induces a change of polymeric conformation, which in turn affects the membrane permeability and the rate of accumulation. Based upon nonequilibrium thermodynamic flow equations, and a two-state representation of membrane macromolecular conformation, this model displays a region of hysteresis in the current range of experimental observations.     

The cholinesterase inhibitor, phenserine, improves Morris water maze performance of scopolamine-treated rats

Male Fischer-344 rats (n = 38) at 5 months old were tested in a Morris water maze to determine if treatment with the cholinesterase inhibitor, phenserine (PHEN), would overcome a learning impairment induced by scopolamine (SCOP), a muscarinic cholinergic receptor antagonist. Each rat was randomly assigned to one of five groups to receive two intraperitoneal injections 60 and 30 min, prior to testing, respectively, as follows: (1) saline-saline (SAL); (2) saline-1.0 mg/kg (SCOP); (3) 2 mg/kg PHEN- SCOP (PHEN2); (4) 4 mg/kg PHEN-SCOP (PHEN4); and (5) 1 mg/kg PHEN-SAL (PHEN1). Maze testing occurred across 5 days with 4 days of acquisition trials (4 trials per day) and a fifth day consisting of a single 120 sec probe trial. PHEN1 and SAL were combined into one control (CON) group for purposes of statistical analysis for both acquisition and probe trials as comparison of the two groups revealed that they did not significantly differ on any measure. SCOP-treated rats were significantly impaired compared to CON in learning the location of the submerged platform as measured by latency to locate the platform and the distance traversed to find the platform across days of testing. The PHEN4 group had significantly lower latencies and traveled a shorter distance to reach the submerged platform when compared to SCOP on the fourth day of trials while the PHEN2 group traveled more directly to the submerged platform but did not have shorter latencies than the SCOP group. For probe trials, CON rats swam closer to the target area (a measure of proximity to the removed platform) than did all other groups, and the PHEN4 group swam in an area more proximate to the target area than did the SCOP-treated group. These findings demonstrate the ability of this drug to improve learning when cholinergic function has been impaired in a spatial memory task.     

Interpersonal content of dreams in relation to the process and outcome of single sessions using the Hill Dream Model.

The authors coded 67 dreams into 5 categories for interpersonal content (7 positive, 20 negative, 9 agency, 16 nightmares, and 15 noninterpersonal); an additional 90 dreams were excluded because they had multiple or ambiguous interpersonal themes. The authors then compared the process (client involvement and therapist competence) and outcome (insight gains, action gains, session evaluation, and change in target problems) of dream sessions in which therapists used the Hill model for the 5 different types of dreams. Process and outcome were better for clients who presented positive, agency, and noninterpersonal dreams than for clients who presented negative dreams and nightmares. Implications for practice and research are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)