Dans l’enfance, la décision d’un régime à vie dès le diagnostic ne devrait pas être systématique mais autant que possible adaptée à chacun au cours d’une prise en charge régulière, attentive et ...prolongée jusqu’à l’âge adulte. L’enfant cœliaque ne courant pas les mêmes risques que l’adulte, il n’est pas logique d’avoir la même attitude préventive à cinq ans qu’à 50ans. Les indications suivantes apparaissent actuellement raisonnables : chez l’enfant et l’adulte, régime sans gluten au diagnostic d’une maladie symptomatique, pour plusieurs années au moins chez le premier, à vie chez le second ; chez l’enfant (devenu) « silencieux » (aucun symptôme clinique ni biologique de malnutrition), le maintien d’un régime normal ou le retour à celui-ci pourrait être discuté à l’absolue condition d’une surveillance rigoureuse et de la reprise, vers 25ans, ou de toute façon avant une grossesse, du régime d’exclusion pour prévenir les risques spécifiques à la maladie chez l’adulte ; surveillance prolongée pour les adolescents ou jeunes adultes dont la maladie n’est plus que « latente ».
Children with celiac disease do not share the same risks as adults, and should have an adapted diet and a prolonged follow-up until adulthood. The following indications seem reasonable: in symptomatic children and adults, gluten free diet during several years in children and for the entire life in adults; in children becoming “silent”, without any clinical or biological signs of malnutrition, discussion of coming back to normal diet, under the condition a strict follow-up and restarting gluten free diet at age of 25 and/or in case of pregnancy, to prevent the complications of celiac disease in adulthood; prolonged follow-up for adolescents and young adults returned to a “latent” disease.
The way predators control their prey populations is determined by the interplay between predator hunting mode and prey antipredator behavior. It is uncertain, however, how the effects of such ...interplay control ecosystem function. A 3-year experiment in grassland mesocosms revealed that actively hunting spiders reduced plant species diversity and enhanced aboveground net primary production and nitrogen mineralization rate, whereas sit-and-wait ambush spiders had opposite effects. These effects arise from the different responses to the two different predators by their grasshopper prey--the dominant herbivore species that controls plant species composition and accordingly ecosystem functioning. Predator hunting mode is thus a key functional trait that can help to explain variation in the nature of top-down control of ecosystems.
Plant breeding has traditionally relied on combining the genetic diversity present within a species to develop combinations of alleles that provide desired traits. Epigenetic diversity may provide ...additional sources of variation within a species that could be captured or created for crop improvement. It will be important to understand the sources of epigenetic variation and the stability of newly formed epigenetic variants over generations to fully use the potential of epigenetic variation to improve crops. The development and application of methods for widespread epigenome profiling and engineering may generate new avenues for using the full potential of epigenetics in crop improvement.
Climate change ecology has focused on climate effects on trophic interactions through the lenses of temperature effects on organismal physiology and phenological asynchronies. Trophic interactions ...are also affected by the nutrient content of resources, but this topic has received less attention. Using concepts from nutritional ecology, we propose a conceptual framework for understanding how climate affects food webs through top-down and bottom-up processes impacted by co-occurring environmental drivers. The framework integrates climate effects on consumer physiology and feeding behavior with effects on resource nutrient content. It illustrates how studying responses of simplified food webs to simplified climate change might produce erroneous predictions. We encourage greater integrative complexity of climate change research on trophic interactions to resolve patterns and enhance predictive capacities.
When studying the responses of food web dynamics to climate change, shifts in resource nutrient content are frequently overlooked, although they generally occur along with shifts in consumer physiology and behavior
Studying the simultaneous effects of both processes on food webs is necessary because they are interdependent and have the potential to produce ecological surprises
Nutritional ecology (NE) provides a convenient organizing principle on which to build understanding of the interdependent nature of the two processes because NE allows one to track the macronutrient connections between trophic levels
By integrating top-down (shifts in consumer physiology and behavior) and bottom-up (shifts in resource nutrient content) responses to climate change into one conceptual framework, we can improve the realism of climate change ecology experiments and predictive accuracy
Spontaneous epimutations in plants Johannes, Frank; Schmitz, Robert J.
New phytologist,
February 2019, Letnik:
221, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Heritable gains or losses of cytosine methylation can arise stochastically in plant genomes independently of DNA sequence changes. These so-called ‘spontaneous epimutations’ appear to be a byproduct ...of imperfect DNA methylation maintenance and epigenome reinforcement events that occur in specialized cell types. There is continued interest in the plant epigenetics community in trying to understand the broader implications of these stochastic events, as some have been shown to induce heritable gene expression changes, shape patterns of methylation diversity within and among plant populations, and appear to be responsive to multi-generational environmental stressors. In this paper we synthesized our current knowledge of the molecular basis and functional consequences of spontaneous epimutations in plants, discuss technical and conceptual challenges, and highlight emerging research directions.
The process of nutrient transfer through an ecosystem is an important determinant of production, food-chain length, and species diversity. The general view is that the rate and efficiency of nutrient ...transfer up the food chain is constrained by herbivore-specific capacity to secure N-rich compounds for survival and production. Using feeding trials with artificial food, we show, however, that physiological stress-response of grasshopper herbivores to spider predation risk alters the nature of the nutrient constraint. Grasshoppers facing predation risk had higher metabolic rates than control grasshoppers. Elevated metabolism accordingly increased requirements for dietary digestible carbohydrate-C to fuel-heightened energy demands. Moreover, digestible carbohydrate-C comprises a small fraction of total plant tissue-C content, so nutrient transfer between plants and herbivores accordingly becomes more constrained by digestible plant C than by total plant C:N. This shift in herbivore diet to meet the altered nutrient requirement increased herbivore body C:N content, the C:N content of the plant community from which grasshoppers select their diet, and grasshopper fecal C:N content. Chronic predation risk thus alters the quality of animal and plant tissue that eventually enters the detrital pool to become decomposed. Our results demonstrate that herbivore physiology causes C:N requirements and nutrient intake to become flexible, thereby providing a mechanism to explain context dependence in the nature of trophic control over nutrient transfer in ecosystems.
We present a framework to explain how prey stress responses to predation can resolve context dependency in ecosystem properties and functions such as food chain length, secondary production, ...elemental stoichiometry, and cycling. We first describe the major nonspecific physiological stress mechanisms and their ecologically relevant consequences. We next synthesize the evidence for prey physiological responses to predation risk and demonstrate that they are similar across taxa and fit well within the general stress paradigm. We then illustrate the utility of our idea by applying our understanding of the ecological consequences of stress to explain how herbivore‐prey physiological antipredator responses affect ecosystem dynamics. We hypothesize that stressed herbivores should forage on plant species with higher digestible carbohydrates than should unstressed herbivores to meet heightened energy demands. Increased consumption of carbohydrate‐rich plants should reduce their relative abundance in the community, hence altering the quantity and quality of plant litter entering the detrital pool. We further hypothesize that stress should change the elemental composition and energy content of prey excreta, egesta, and carcasses that enter the detrital pool. Finally, prey stress should lower energy and nutrient conversion efficiency and hence the transfer of materials and energy up the food chain, which should, in turn, weaken the association between ecosystem productivity and food chain length.
Chemical modification of nucleotide bases in DNA provides one mechanism for conveying information in addition to the genetic code. 5-methylcytosine (5mC) represents the most common chemically ...modified base in eukaryotic genomes. Sometimes referred to simply as DNA methylation, in eukaryotes 5mC is most prevalent at CpG dinucleotides and is frequently associated with transcriptional repression of transposable elements. However, 5mC levels and distributions are variable across phylogenies, and emerging evidence suggests that the functions of DNA methylation may be more diverse and complex than was previously appreciated. We summarize the current understanding of DNA methylation profiles and functions in different eukaryotic lineages.
Although DNA methyltransferase content is generally conserved across eukaryotes, there is extensive variation in how this modified base is used for a variety of cellular processes.The manner in which DNA methyltransferases are recruited to target sequences leads to a diversity of genome-wide DNA methylation patterns across eukaryotes.Continued exploration of DNA methylation patterns and DNA methyltransferase content in diverse eukaryotic lineages will lead to an expanded understanding of the mechanism by which the modified base functions in genomes.
Prevention and early detection of prostate cancer Cuzick, Jack, Prof; Thorat, Mangesh A, MBBS; Andriole, Gerald, Prof ...
Lancet oncology/Lancet. Oncology,
10/2014, Letnik:
15, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Summary Prostate cancer is a common malignancy in men and the worldwide burden of this disease is rising. Lifestyle modifications such as smoking cessation, exercise, and weight control offer ...opportunities to reduce the risk of developing prostate cancer. Early detection of prostate cancer by prostate-specific antigen (PSA) screening is controversial, but changes in the PSA threshold, frequency of screening, and the use of other biomarkers have the potential to minimise the overdiagnosis associated with PSA screening. Several new biomarkers for individuals with raised PSA concentrations or those diagnosed with prostate cancer are likely to identify individuals who can be spared aggressive treatment. Several pharmacological agents such as 5α-reductase inhibitors and aspirin could prevent development of prostate cancer. In this Review, we discuss the present evidence and research questions regarding prevention, early detection of prostate cancer, and management of men either at high risk of prostate cancer or diagnosed with low-grade prostate cancer.
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