Some Effects of Yellow Rust (Puccinia striiformis) on 14Carbon Assimilation and Translocation in Wheat

A well-developed infection of Yellow Rust on a leaf of springwheat (Jufy I) caused the assimilation of ¹⁴CO₂ by that leafto decrease to 43.5 per cent of that of an uninfected leaf.Over a period of three hours translocation of ¹⁴C from an infectedleaf was only 0.87 per cent of that from a control leaf. Whencontrol plants were kept in the light for periods up to 16 hoursafter assimilating ¹⁴CO₂ translocation continued at a steadyrate, whereas there was only negligible translocation from infectedleaves after the first few hours. The retention of labelledassimilates in the infected leaf could be partly, but not completely,accounted for by a conversion of assimilates to an alcohol-insolubleform. Rust infection had no effect on the distribution patternof ¹⁴C to other leaves from one which had assimilated ¹⁴CO₂.In contrast to the marked retention of assimilate by an infectedleaf, such a leaf was unable to distort the normal distributionby attracting assimilates from the other leaves.     

Interet diagnostique d’une injection intracaverneuse de 20 μg de Prostaglandine E1 dans l’impuissance

Intracavernous injection of 20 μg of prostaglandin E1 (PGE1) was carried out in 130 impotent patients. The erectile response was compared to the results of arteriological investigations including nocturnal penile tumescence and rigidity monitoring (NPTR) in 59 patients. The response of 60 patients positively categorized as exclusively psychogenic or vasculogenic was also compared to the pattern of the response to 80 mg of papaverine observed in a previous study by the same authors. The PGE1 test may not discriminate psychogenic from wholly organic patients since its results are not correlated to those of NPTR. It helps for the screening of vasculogenic impotence. Lack of response or a partly rigid response is consistent with this actiology but is not specific for it. A fully response makes it unlikely. Compared to papaverine, PGE1 induces less non rigid responses in psychogenic patients (15% versus 35% with papaverine) and more fully rigid responses in vasculogenic patients (respectively 12% and 5 %). Consequently the specificity of the PGE1 test is higher but its sensitivity lower than that of papaverine so that there is no clear difference in the effectiveness of the tests. Nevertheless the PGE1 test should be preferred, because it is safer. Prolonged erections occured in only 5 patients, and all ceased spontaneously. However 4 presented severely painful erections.     

Influence of Photoperiod, Daylength, and Feeding Schedule on Tadpole Growth and Development

The metamorphic rate of Rana pipiens tadpoles was studied under different photoperiods, daylengths, and feeding schedules. Tail resorption and hindlimb growth and development induced by immersion in 30 μg/l thyroxine (T₄) were accelerated under longer photoperiods and continuous light when 6L: 18D, 12L: 12D, 18L: 6D, and 24L regimes were compared. Constant light exposure did not produce faster development than an 18 hr photoperiod, and initially was less effective. The rate of spontaneous and T₄-induced metamorphosis was greater the shorter the day on 9L:9D, 12L: 12D, or 15L: 15D cycles, although all groups received the same overall amount of light, but in different dosages. When feeding schedule but not the LD cycle was varied, groups of tadpoles fed on 18, 24, or 30 hr regimes showed no differences in growth and development rate on 19L: 5D, and only random variations under continuous light. Differences in metamorphic rate on 18, 24, or 30 hr days are not due to the feeding schedules, but to the LD cycles. From these experiments we conclude that illumination, particularly the length and frequency of the photoperiod, affects the utilization of T₄. Development rates independent of the total amount of illumination, but related to daylength and light schedule, suggest interaction of light with an endogenous timing mechanism.     

Mendelian randomization supports causality between maternal hyperglycemia and epigenetic regulation of leptin gene in newborns

Leptin is an adipokine that acts in the central nervous system and regulates energy balance. Animal models and human observational studies have suggested that leptin surge in the perinatal period has a critical role in programming long-term risk of obesity. In utero exposure to maternal hyperglycemia has been associated with increased risk of obesity later in life. Epigenetic mechanisms are suspected to be involved in fetal programming of long term metabolic diseases. We investigated whether DNA methylation levels near LEP locus mediate the relation between maternal glycemia and neonatal leptin levels using the 2-step epigenetic Mendelian randomization approach. We used data and samples from up to 485 mother-child dyads from Gen3G, a large prospective population-based cohort. First, we built a genetic risk score to capture maternal glycemia based on 10 known glycemic genetic variants (GRS₁₀) and showed it was an adequate instrumental variable (β = 0.046 mmol/L of maternal fasting glucose per additional risk allele; SE = 0.007; P = 7.8 × 10⁻¹¹; N = 467). A higher GRS₁₀ was associated with lower methylation levels at cg12083122 located near LEP (β = −0.072 unit per additional risk allele; SE = 0.04; P = 0.05; N = 166). Direction and effect size of association between the instrumental variable GRS₁₀ and methylation at cg12083122 were consistent with the negative association we observed using measured maternal glycemia. Lower DNA methylation levels at cg12083122 were associated with higher cord blood leptin levels (β = −0.17 log of cord blood leptin per unit; SE = 0.07; P = 0.01; N = 170). Our study supports that maternal glycemia is part of causal pathways influencing offspring leptin epigenetic regulation.     

Cytonuclear equilibrium following interspecific introgression in a turtle lacking sex chromosomes

When reproductive barriers break down, interspecific hybridization can lead to gene flow between evolutionarily distinct species. Studying the fate of these introgressing elements can offer valuable insights into the factors contributing to reproductive isolation. We have identified a population of false map turtles (Graptemys pseudogeographica) that hybridized historically with the common map turtle (Graptemys geographica), but were subsequently isolated from interbreeding for several generations by unique geological events. Although many studies conclude that genic interactions involving sex chromosomes impact the introgression of mitochondrial or nuclear genomes, Graptemys turtles have environmental sex determination, and thus introgression can be explored while controlling for the effects of sex‐specific heterogameity. We identified and sequenced a species‐specific mitochondrial control region marker, as well as two nuclear markers (ODC and HNFAL), in turtles from across the ranges of these species. We found both nuclear and mitochondrial introgression in our study population, and present evidence consistent with the proposed time range of reproductive contact and isolation. We also report an absence of cytonuclear or linkage disequilibrium among markers, indicating that some important pre‐ and postzygotic barriers to gene flow that characterize other systems are absent in Graptemys. Finally, we show that Graptemys turtles have a complex molecular evolutionary history, and that leaks in reproductive barriers probably occur frequently. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 405–417.     

siRNA against presenilin 1 (PS1) down regulates amyloid β42 production in IMR-32 cells

Background  

One of the pathological hallmarks of Alzheimer's disease (AD) is the deposition of the ~4 kDa amyloid β protein (Aβ) within lesions known as senile plaques. Aβ is also deposited in the walls of cerebral blood vessels in many cases of AD. A substantial proportion of the Aβ that accumulates in the AD brain is deposited as Amyloid, which is highly insoluble, proteinaceous material with a β-pleated-sheet conformation and deposited extracellularly in the form of 5-10 nm wide straight fibrils. As γ-secretase catalyzes the final cleavage that releases the Aβ42 or 40 from amyloid β -protein precursor (APP), therefore, it is a potential therapeutic target for the treatment of AD. γ-Secretase cleavage is performed by a high molecular weight protein complex containing presenilins (PSs), nicastrin, Aph-1 and Pen-2. Previous studies have demonstrated that the presenilins (PS1 and PS2) are critical components of a large enzyme complex that performs γ-secretase cleavage.     

Revisions of Rump Fat and Body Scoring Indices for Deer,Elk, and Moose

Abstract: Because they do not require sacrificing animals, body condition scores (BCS), thickness of rump fat (MAXFAT), and other similar predictors of body fat have advanced estimating nutritional condition of ungulates and their use has proliferated in North America in the last decade. However, initial testing of these predictors was too limited to assess their reliability among diverse habitats, ecotypes, subspecies, and populations across the continent. With data collected from mule deer (Odocoileus hemionus), elk (Cervus elaphus), and moose (Alces alces) during initial model development and data collected subsequently from free-ranging mule deer and elk herds across much of the western United States, we evaluated reliability across a broader range of conditions than were initially available. First, to more rigorously test reliability of the MAXFAT index, we evaluated its robustness across the 3 species, using an allometric scaling function to adjust for differences in animal size. We then evaluated MAXFAT, rump body condition score (rBCS), rLIVINDEX (an arithmetic combination of MAXFAT and rBCS), and our new allometrically scaled rump-fat thickness index using data from 815 free-ranging female Roosevelt and Rocky Mountain elk (C. e. roosevelti and C. e. nelsoni) from 19 populations encompassing 4 geographic regions and 250 free-ranging female mule deer from 7 populations and 2 regions. We tested for effects of subspecies, geographic region, and captive versus free-ranging existence. Rump-fat thickness, when scaled allometrically with body mass, was related to ingesta-free body fat over a 38–522-kg range of body mass (r² = 0.87; P < 0.001), indicating the technique is remarkably robust among at least the 3 cervid species of our analysis. However, we found an underscoring bias with the rBCS for elk that had >12% body fat. This bias translated into a difference between subspecies, because Rocky Mountain elk tended to be fatter than Roosevelt elk in our sample. Effects of observer error with the rBCS also existed for mule deer with moderate to high levels of body fat, and deer body size significantly affected accuracy of the MAXFAT predictor. Our analyses confirm robustness of the rump-fat index for these 3 species but highlight the potential for bias due to differences in body size and to observer error with BCS scoring. We present alternative LIVINDEX equations where potential bias from rBCS and bias due to body size are eliminated or reduced. These modifications improve the accuracy of estimating body fat for projects intended to monitor nutritional status of herds or to evaluate nutrition's influence on population demographics.