Expression of <Emphasis Type="Italic">PEG11</Emphasis> and <Emphasis Type="Italic">PEG11AS</Emphasis> transcripts in normal and callipyge sheep

Background  

The callipyge mutation is located within an imprinted gene cluster on ovine chromosome 18. The callipyge trait exhibits polar overdominant inheritance due to the fact that only heterozygotes inheriting a mutant paternal allele (paternal heterozygotes) have a phenotype of muscle hypertrophy, reduced fat and a more compact skeleton. The mutation is a single A to G transition in an intergenic region that results in the increased expression of several genes within the imprinted cluster without changing their parent-of-origin allele-specific expression.     

p53 Represses the Mevalonate Pathway to Mediate Tumor Suppression

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Costs of reproduction in male lizards, Sceloporus virgatus

Models of life history evolution typically assume a balance between the benefits of current reproductive activity and the costs to future reproductive success or survivorship, but empirical studies often find positive correlations between such components of fitness in undisturbed animal populations. I examined possible survivorship costs of reproduction in free-ranging male lizards, Sceloporus virgatus , and found that males with low levels of mating success were less likely to survive to the following breeding season. I also investigated two possible indicators of reproductive effort, increase in ectoparasite load and decrease in body weight during the breeding season. Levels of parasitism with trombiculid mites at the end of the breeding season were not associated with any measure of fitness or body condition (mating success, survivorship to the following year, relative weight loss). Yearling males (which have low levels of mating success) usually gained weight during the breeding season, while older males generally lost weight during this period. This suggests that young males may have postponed reproduction in favor of body growth and that seasonal weight loss of older males might reflect reproductive effort. Within the group of older males, individuals with the highest levels of mating success did not have high levels of either weight loss or mortality. Mate guarding behavior, an alternative to the aggressive territorial behavior typical of many lizard species, may allow certain males to obtain mates without expending large amounts of energy or exposing themselves to great mortality risks.     

The Discovery of a Reciprocal Relationship between Tyrosine-Kinase Signaling and Cullin Neddylation

While neddylation is known to activate cullin (CUL)-RING ubiquitin ligases (CRLs), its role in regulating T cell signaling is poorly understood. Using the investigational NEDD8 activating enzyme (NAE) inhibitor, MLN4924, we found that neddylation negatively regulates T cell receptor (TCR) signaling, as its inhibition increases IL-2 production, T cell proliferation and Treg development in vitro. We also discovered that loss of CUL neddylation occurs upon TCR signaling, and CRLs negatively regulate IL-2 production. Additionally, we found that tyrosine kinase signaling leads to CUL deneddylation in multiple cell types. These studies indicate that CUL neddylation is a global regulatory mechanism for tyrosine kinase signaling.     

Life history focus on a malaria parasite: linked traits and variation among genetic clones

Life history theory has long been a major campaign in evolutionary ecology, but has typically focused only on animals and plants. Life history research on single-celled eukaryotic protists such as malaria parasites (Plasmodium) will offer new insights into the theory’s general utility as well as the parasite’s basic biology. For example, parasitologists have described the Plasmodium life cycle and cell types in exquisite detail, with little discussion of evolutionary issues such as developmental links between traits. We measured 10 life history traits of replicate single-genotype experimental Plasmodium mexicanum infections in its natural lizard host to identify groups of linked traits. These 10 traits formed 4 trait groups: “Rate/Peak” merges measures of growth rate and maximum parasitemia of infections; “Timing” combines time to patency and maximum parasitemia; “Growth Shape” describes the fit to an exponential growth curve; and “Sex Ratio” includes only the gametocyte sex ratio. Parasite genotype (clone) showed no effect on the life history trait groups, with the exception of gametocyte sex ratio. Therefore, variation in most life history traits among infections appears to be driven by environmental (individual host) effects. The findings support the model that life history traits are often linked by developmental constraints. Understanding why life history traits of Plasmodium are linked in this way would offer a new window into the evolution of the parasites, and also should inform public health efforts to control infection prevalence.     

Skeletal muscle ECF pH error signal for exercise ventilatory control

Evans, Allison B., Larry W. Tsai, David A. Oelberg, HomayounKazemi, and David M. Systrom. Skeletal muscle ECF pH error signalfor exercise ventilatory control. J. Appl.Physiol. 84(1): 90-96, 1998.An autonomic reflexlinking exercising skeletal muscle metabolism to central ventilatorycontrol is thought to be mediated by neural afferents having freeendings that terminate in the interstitial fluid of muscle. Todetermine whether changes in muscle extracellular fluid pH(pH_e) can provide an errorsignal for exercise ventilatory control,pH_e was measured duringelectrically induced contraction by³¹P-magnetic resonancespectroscopy and the chemical shift of a phosphorylated, pH-sensitivemarker that distributes to the extracellular fluid (phenylphosphonicacid). Seven lightly anesthetized rats underwentunilateral continuous 5-Hz sciatic nerve stimulation in an 8.45-Tnuclear magnetic resonance magnet, which resulted in a mixed lacticacidosis and respiratory alkalosis, with no net change in arterial pH.Skeletal muscle intracellular pH fell from 7.30 ± 0.03 units atrest to 6.72 ± 0.05 units at 2.4 min of stimulation and then roseto 7.05 ± 0.01 units (P < 0.05), despite ongoing stimulation and muscle contraction.Despite arterial hypocapnia, pH_eshowed an immediate drop from its resting baseline of 7.40 ± 0.01 to 7.16 ± 0.04 units (P < 0.05)and remained acidic throughout the stimulation protocol. During the on-and off-transients for 5-Hz stimulation, changes in the pH gradientbetween intracellular and extracellular compartments suggestedtime-dependent recruitment of sarcolemmal ion-transport mechanisms.pH_e of exercising skeletal musclemeets temporal and qualitative criteria necessary for a ventilatorymetaboreflex mediator in a setting where arterial pH doesnot.

     

Climate change amplifies gross nitrogen turnover in montane grasslands of Central Europe in both summer and winter seasons

The carbon‐ and nitrogen‐rich soils of montane grasslands are exposed to above‐average warming and to altered precipitation patterns as a result of global change. To investigate the consequences of climatic change for soil nitrogen turnover, we translocated intact plant–soil mesocosms along an elevational gradient, resulting in an increase of the mean annual temperature by approx. 2 °C while decreasing precipitation from approx. 1500 to 1000 mm. Following three years of equilibration, we monitored the dynamics of gross nitrogen turnover and ammonia‐oxidizing bacteria (AOB) and archaea (AOA) in soils over an entire year. Gross nitrogen turnover and gene levels of AOB and AOA showed pronounced seasonal dynamics. Both summer and winter periods equally contributed to cumulative annual N turnover. However, highest gross N turnover and abundance of ammonia oxidizers were observed in frozen soil of the climate change site, likely due to physical liberation of organic substrates and their rapid turnover in the unfrozen soil water film. This effect was not observed at the control site, where soil freezing did not occur due to a significant insulating snowpack. Climate change conditions accelerated gross nitrogen mineralization by 250% on average. Increased N mineralization significantly stimulated gross nitrification by AOB rather than by AOA. However, climate change impacts were restricted to the 2–6 cm topsoil and rarely occurred at 12–16 cm depth, where generally much lower N turnover was observed. Our study shows that significant mineralization pulses occur under changing climate, which is likely to result in soil organic matter losses with their associated negative impacts on key soil functions. We also show that N cycling processes in frozen soil can be hot moments for N turnover and thus are of paramount importance for understanding seasonal patterns, annual sum of N turnover and possible climate change feedbacks.     

Influence of antimicrobial feed additives on broiler commensal posthatch gut microbiota development and performance

The effects of avilamycin, zinc bacitracin, and flavophospholipol on broiler gut microbial community colonization and bird performance in the first 17 days posthatch were investigated. Significant differences in gut microbiota associated with gut section, dietary treatment, and age were identified by terminal restriction fragment length polymorphism (T-RFLP), although no performance-related differences between dietary treatments were detected. Similar age-related shifts in the gut microbiota were identified regardless of diet but varied between the ilea and ceca. Interbird variabilities in ileal bacterial communities were reduced (3 to 7 days posthatch) in chicks fed with feed containing antimicrobial agents. Avilamycin and flavophospholipol had the most consistent effect on gut microbial communities. Operational taxonomic units (OTU) linked to changes in gut microbiota in birds on antimicrobial-supplemented diets were characterized and identified. Some OTUs could be identified to the species level; however, the majority could be only tentatively classified to the genus, family, order, or domain level. OTUs 140 to 146 (Lachnospiraceae), OTU 186/188 (Lactobacillus johnsonii), OTU 220 (Lachnospiraceae), OTUs 284 to 288 (unclassified bacterial spp. or Ruminococcaceae), OTU 296/298 (unclassified bacterium or Clostridiales), and OTU 480/482 (Oxalobacteraceae) were less prevalent in the guts of chicks fed antimicrobial-supplemented diets. OTU 178/180 (Lactobacillus crispatus), OTU 152 (Lactobacillus reuteri or unclassified Clostridiales), OTU 198/200 (Subdoligranulum spp.), and OTU 490/492 (unclassified bacterium or Enterobacteriaceae) were less prevalent in the gut of chicks raised on the antimicrobial-free diet. The identification of key bacterial species influenced by antimicrobial-supplemented feed immediately posthatch may assist in the formulation of diets that facilitate beneficial gut microbial colonization and, hence, the development of alternatives to current antimicrobial agents in feed for sustainable poultry production.