Frequency-dependent selection
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Studies of parasite population dynamics in natural systems are crucial for our understanding of host-parasite coevolutionary processes. Some field studies have reported that host genotype frequencies in natural populations change over time according to parasite-driven negative frequency-dependent selection. However, the temporal patterns of parasite genotypes have rarely been investigated. Moreover, parasite-driven negative frequency-dependent selection is contingent on the existence of genetic specificity between hosts and parasites. In the present study, the population dynamics and host-genotype specificity of the ichthyosporean Caullerya mesnili, a common endoparasite of Daphnia water fleas, were analysed based on the observed sequence variation in the first internal transcribed spacer (ITS1) of the ribosomal DNA. The Daphnia population of lake Greifensee (Switzerland) was sampled and subjected to parasite screening and host genotyping during C. mesnili epidemics of four consecutive years. The ITS1 of wild-caught C. mesnili-infected Daphnia was sequenced using the 454 pyrosequencing platform. The relative frequencies of C. mesnili ITS1 sequences differed significantly among years: the most abundant C. mesnili ITS1 sequence decreased and rare sequences increased over the course of the study, a pattern consistent with negative frequency-dependent selection. However, only a weak signal of host-genotype specificity between C. mesnili and Daphnia genotypes was detected. Use of cutting edge genomic techniques will allow further investigation of the underlying micro-evolutionary relationships within the Daphnia-C. mesnili system.
- MeSH
- časové faktory MeSH
- Daphnia genetika parazitologie MeSH
- genotyp MeSH
- hostitelská specificita MeSH
- interakce hostitele a parazita genetika imunologie MeSH
- Mesomycetozoea genetika fyziologie MeSH
- mezerníky ribozomální DNA MeSH
- selekce (genetika) MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The expression of alternative reproductive tactics can be plastic and occur simultaneously depending on cues that vary spatially or temporally. For example, variation in resources and sexual selection intensity is expected to influence the pay-off of each tactic and shape the decision of which tactic to employ. Males of the nuptial gift-giving spider Pisaura mirabilis can adopt three tactics: offering a genuine prey gift, a 'worthless' non-nutritious gift or no gift. We hypothesized that resources and/or male body condition, and mating opportunity and sexual selection intensity, vary over the course of the mating season to shape the co-existence of alternative traits. We measured these variables in the field over two seasons, to investigate the predictions that as the mating season progresses, (i) males become more likely to employ a gift-giving tactic, and (ii) the likelihood of switching from worthless to genuine gifts increases. Prey availability increased over the season and co-varied with the propensity of males to employ the gift-giving tactic, but we found no support for condition-dependent gift giving. Males responded to an increase in female availability by increasing their mating effort (gift production). Furthermore, the frequency of genuine gift use increased with sexual selection intensity, consistent with the assumption that sperm competition intensity increases with time. Our results suggest that the frequency of alternative tactics is shaped by seasonal changes in ecological factors and sexual selection. This leads to relaxed selection for the gift-giving tactic early in the season when females are less choosy and resources more scarce, and increased selection for genuine gifts later in the season driven by mating opportunity and risk of sperm competition.
- MeSH
- pavouci genetika fyziologie MeSH
- selekce (genetika) MeSH
- sexuální chování zvířat fyziologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Extremely high variability in genes of the major histocompatibility complex (MHC) in vertebrates is assumed to be a consequence of frequency-dependent parasite-driven selection and mate preferences based on promotion of offspring heterozygosity at MHC, or potentially, genome-wide inbreeding avoidance. Where effects have been found, mate choice studies on rodents and other species usually find preference for MHC-dissimilarity in potential partners. Here we critically review studies on MHC-associated mate choice in humans. These are based on three broadly different aspects: (1) odor preferences, (2) facial preferences and (3) actual mate choice surveys. As in animal studies, most odor-based studies demonstrate disassortative preferences, although there is variation in the strength and nature of the effects. In contrast, facial attractiveness research indicates a preference for MHC-similar individuals. Results concerning MHC in actual couples show a bias towards similarity in one study, dissimilarity in two studies and random distribution in several other studies. These vary greatly in sample size and heterogeneity of the sample population, both of which may significantly bias the results. This pattern of mixed results across studies may reflect context-dependent and/or life history sensitive preference expression, in addition to higher level effects arising out of population differences in genetic heterogeneity or cultural and ethnic restrictions on random mating patterns. Factors of special relevance in terms of individual preferences are reproductive status and long- vs. short-term mating context. We discuss the idea that olfactory and visual channels may work in a complementary way (i.e. odor preference for MHC-dissimilarity and visual preference for MHC-similarity) to achieve an optimal level of genetic variability, methodological issues and interesting avenues for further research.
olně prodejná (OTC) analgetika dělíme dle klinického účinku na analgetika – antipyretika (kyselina acetylsalicylová, paracetamol, propyfenazon) a analgetika-antiflogistika (ibuprofen, naproxen, diklofenak, dexketoprofen) a dle počtu látek na jednosložková a kombinovaná analgetika. OTC analgetika užíváme v léčbě migrény, tenzního typu bolesti hlavy a nezávažných sekundárních bolestí hlavy. Výběr léku je závislý na intenzitě bolesti, na přítomnosti doprovodných příznaků, na ostatní užívané medikaci (např. warfarin, kyselina acetylsalicylová, další nesteroidní antiflogistika, kortikosteroidy, antidepresiva, perorální antidiabetika) a komplikujících onemocněních (vředová choroba žaludku a dvanácterníku, arteriální hypertenze, ischemická choroba srdeční, bronchiální astma, onemocnění jater a ledvin). U polymorbidních osob je vysoké riziko lékových interakcí OTC analgetik s další užívanou medikací. U osob s vyšší frekvencí bolestí hlavy a podezřením na nadužívání analgetik je nutné doporučit neurologické vyšetření.
Over-the-counter (OTC) analgesics are divided according to their clinical effect structure to analgesics – anti-inflammatory drugs (ibuprofen, naproxen, diclofenac, dexketoprofen) – antipyretics (acetylsalicylic acid, paracetamol, propyphenazone), and analgesics and according to the number of substances to simple and combined analgesics. OTC analgesics are used in the treatment of migraine, tension-type headache and minor secondary headaches. The choice of the drug depends on the intensity of pain, the presence of associated symptoms, other used medications (warfarin, aspirin, other nonsteroidal anti-inflamatory drugs, corticosteroids, antidepressants, oral antidiabetic drugs) and complicating diseases (stomach and duodenal ulcers, arterial hypertension, coronary artery disease, bronchial asthma, disease of liver and kidney). Polymorbid persons have higher risk of interactions OTC analgesics with other frequent medication. Neurological examination should be recomended to people with a higher frequency of headaches and suspected abuse of analgesics.
- Klíčová slova
- kombinovaná analgetika,
- MeSH
- analgetika aplikace a dávkování farmakologie klasifikace terapeutické užití MeSH
- antiflogistika nesteroidní aplikace a dávkování klasifikace terapeutické užití MeSH
- antipyretika aplikace a dávkování klasifikace terapeutické užití MeSH
- bolesti hlavy * farmakoterapie MeSH
- fixní kombinace léků MeSH
- léky bez předpisu * aplikace a dávkování farmakologie terapeutické užití MeSH
- lidé MeSH
- polypharmacy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Volně prodejná (OTC) analgetika dělíme dle klinického účinku na analgetika-antiflogistika (ibuprofen, naproxen, diklofenak, dexketoprofen) a analgetika-antipyretika (kyselina acetylsalicylová, paracetamol, propyfenazon) a dle počtu látek na jednosložková a kombinovaná analgetika. OTC analgetika užíváme v léčbě migrény, tenzního typu bolesti hlavy a nezávažných sekundárních bolestí hlavy. Výběr léku je závislý na intenzitě bolesti, na přítomnosti doprovodných příznaků, na ostatní užívané medikaci (např. warfarin, kyselina acetylsalicylová, další nesteroidní antiflogistika, kortikosteroidy, antidepresiva, perorální antidiabetika) a komplikujících onemocněních (vředová choroba žaludku a dvanácterníku, arteriální hypertenze, ischemická choroba srdeční, bronchiální astma, onemocnění jater a ledvin). U polymorbidních osob je vysoké riziko lékových interakcí OTC analgetik s další užívanou medikací. U osob s vyšší frekvencí bolestí hlavy a podezřením na nadužívání analgetik je nutné doporučit lékařské vyšetření.
Over-the-counter (OTC) analgesics are divided according to their clinical effect structure to analgesics – anti-inflammatory drugs (ibuprofen, naproxen, diclofenac, dexketoprofen) and analgetics–antipyretics (acetylsalicylic acid, paracetamol, propyphenazone), and according to the number of substances to simple and combined analgesics. OTC analgesics are used in the treatment of migraine, tension- type headache and minor secondary headaches. The choice of the drug depends on the intensity of pain, the presence of associated symptoms, other used medications (warfarin, aspirin, other nonsteroidal anti-inflamatory drugs, corticosteroids, antidepressants, oral antidiabetic drugs) and complicating diseases (stomach and duodenal ulcers, arterial hypertension, coronary artery disease, bronchial asthma, disease of liver and kidney). Polymorbid persons have higher risk of interactions OTC analgesics with other frequent medication. Medical examination should be recomended to people with a higher frequency of headaches and suspected abuse of analgesics.
- Klíčová slova
- kombinovaná analgetika,
- MeSH
- analgetika * aplikace a dávkování farmakologie klasifikace terapeutické užití MeSH
- antiflogistika nesteroidní * aplikace a dávkování klasifikace terapeutické užití MeSH
- antipyretika * aplikace a dávkování klasifikace terapeutické užití MeSH
- bolesti hlavy * farmakoterapie MeSH
- fixní kombinace léků MeSH
- léky bez předpisu aplikace a dávkování farmakologie terapeutické užití MeSH
- lidé MeSH
- polypharmacy MeSH
- Check Tag
- lidé MeSH
Extrakorporální litotrypse (Extracorporeal Shock Wave Lithotripsy, ESWL) od jejího uvedení do urologické praxe v roce 1980 zcela změnila tehdejší invazivní léčebné postupy u pacientů s urolitiázou. Až 90 % pacientů s urolitiázou je v dnešní době léčených pomocí ESWL. Z množstva publikovaných prací o této metodě lze extrahovat a identifikovat některé významné faktory ovlivňující léčebný výsledek a na tyto prognostické faktory myslet v klinických indikacích. Cílem této práce je poukázat na existenci a význam nejdůležitějších faktorů ovlivňujících výsledky ESWL. Důraz byl kladen zejména na faktory na straně pacienta (lokalizace konkrementu v močových cestách, velikost a počet konkrementů, hodnota denzity konkrementu při počítačové tomografii, chemické složení, vzdálenost konkrementu od kůže pacienta, body mass index (BMI), přítomnost stentu, věk, vrozené a získané anomálie ledvin a močových cest, použití medikamentózní expulzní terapie) a faktory na straně přístroje a jeho obsluhy (frekvence rázové vlny, typ a konstrukce litotryptoru, přítomnosti bublin v kontaktním médiu, anestezie a zkušeností operatéra)
Since its invention in the 1980s and subsequent introduction into clinical practice, Extracorporeal Shock Wave Lithotripsy (ESWL) has dramatically changed the previous, rather invasive, approach to the treatment of urinary stones. Up to 90 % of patients with kidney stones now undergo ESWL. There has been a lot of data published on this topic over the past twenty-nine years. From this amount of evidence, we can identify the specific prognostic factors, which can be used to predict the clinical outcome of the shock wave lithotripsy, thus providing for the better selection of patients. Two main groups of factors are thought to have the strongest prediction value: patient-dependent and the machine and operator/dependent factors. Patient factors include: location, size, stone burden, computerized tomography (CT) density and chemical composition, stone-to-skin distance, body mass index (BMI), presence of a JJ-stent, age, congenital or acquired urinary tract anomalies and use of medical expulsion drugs. Machine-dependent factors are: shock wave frequency, type of lithotripter, bubbleless coupling, type of anaesthesia and operator experience.
BACKGROUND: Darwin's evolutionary theory could easily explain the evolution of adaptive traits (organs and behavioral patterns) in asexual but not in sexual organisms. Two models, the selfish gene theory and frozen plasticity theory were suggested to explain evolution of adaptive traits in sexual organisms in past 30 years. RESULTS: The frozen plasticity theory suggests that sexual species can evolve new adaptations only when their members are genetically uniform, i.e. only after a portion of the population of the original species had split off, balanced on the edge of extinction for several generations, and then undergone rapid expansion. After a short period of time, estimated on the basis of paleontological data to correspond to 1-2% of the duration of the species, polymorphism accumulates in the gene pool due to frequency-dependent selection; and thus, in each generation, new mutations occur in the presence of different alleles and therefore change their selection coefficients from generation to generation. The species ceases to behave in an evolutionarily plastic manner and becomes evolutionarily elastic on a microevolutionary time-scale and evolutionarily frozen on a macroevolutionary time-scale. It then exists in this state until such changes accumulate in the environment that the species becomes extinct. CONCLUSION: Frozen plasticity theory, which includes the Darwinian model of evolution as a special case--the evolution of species in a plastic state, not only offers plenty of new predictions to be tested, but also provides explanations for a much broader spectrum of known biological phenomena than classic evolutionary theories. REVIEWERS: This article was reviewed by Rob Knight, Fyodor Kondrashov and Massimo Di Giulio (nominated by David H. Ardell).
The genomic signature of an organism captures the characteristics of repeated oligonucleotide patterns in its genome 1, such as oligomer frequencies, GC content, and differences in codon usage. Viruses, however, are obligate intracellular parasites that are dependent on their host cells for replication, and information about genomic signatures in viruses has hitherto been sparse.Here, we investigate the presence and specificity of genomic signatures in 2,768 eukaryotic viral species from 105 viral families, aiming to illuminate dependencies and selective pressures in viral genome evolution. We demonstrate that most viruses have highly specific genomic signatures that often also differ significantly between species within the same family. The species-specificity is most prominent among dsDNA viruses and viruses with large genomes. We also reveal consistent dissimilarities between viral genomic signatures and those of their host cells, although some viruses present slight similarities, which may be explained by genetic adaptation to their native hosts. Our results suggest that significant evolutionary selection pressures act upon viral genomes to shape and preserve their genomic signatures, which may have implications for the field of synthetic biology in the construction of live attenuated vaccines and viral vectors.
BACKGROUND: Type 2 diabetes is a growing health problem globally; however, awareness about diabetes remains low. AIM: To assess the public perception of diabetes--how much does the public know about it? What are the beliefs about this challenging issue? METHODS: A public opinion survey was performed in April 2012. Interviews with a random sample of 1,002 residents of Lithuania aged 16-74 were conducted in the households of the respondents. This sample took into account age, sex, education, employment, family status, and the size of the residential location. The topics covered by the 15-item questionnaire used for these interviews concerned the perceived severity of different health conditions and the respondents' knowledge of diabetes risk factors and normal glycemic indicators as well as their perceptions related to diabetes and insulin. RESULTS: More than half (56.3%) of respondents had previously undergone the glycemic control test, 33.8% of study participants were familiar with the normal parameters of glycemia. Diabetes was ranked fourth among 13 health problems (the top three were attributed to malignancies, AIDS and mental illnesses). The highest score of all risk factors for developing diabetes was attributed to obesity; however, obesity was never mentioned in associating with diabetes by participants. The perceptions people had about diabetes revealed marginally medicalized images of this health condition. CONCLUSIONS: Study findings suggest the potential social stigmatization of diabetes and encourage looking for new ways in approaching the community as well as individual diabetic patients in regard to the issue of diabetes.
- MeSH
- charakteristiky bydlení MeSH
- diabetes mellitus 2. typu epidemiologie MeSH
- dospělí MeSH
- krevní glukóza MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- průřezové studie MeSH
- rizikové faktory MeSH
- senioři MeSH
- sexuální faktory MeSH
- socioekonomické faktory MeSH
- uvědomování si * MeSH
- věkové faktory MeSH
- veřejné mínění * MeSH
- zdraví - znalosti, postoje, praxe * MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mladiství MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Litva MeSH
BACKGROUND: In this study we compared levels of selected adipokines between patients with type 2 diabetes (T2D) and healthy individuals and we determined their relationship with early vascular damage markers. METHODS: Seventy-seven subjects: 56 patients with T2D (34 men and 22 women) and 21 healthy controls (8 men and 13 women) were examined in this cross-sectional study. Selected adipokines [adiponectin, adipocyte fatty acid-binding protein (A-FABP), fibroblast growth factor 21 (FGF-21), C1q/TNF-related protein 9 (CTRP-9), and allograft inflammatory factor-1 (AIF-1)] with possible cardiovascular impact were measured in all participants. To identify markers of vascular damage von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1) and arterial stiffness parameters were examined in all the subjects. RESULTS: When compared with healthy controls, T2D had significantly higher levels of A-FABP [50.0 (38.1-68.6) vs. 28.6 (23.6-32.9) ng/mL, P < 0.0001] and lower levels of adiponectin [5.9 (4.3-9.0) vs. 11.3 (8.7-14.8) μg/mL, P < 0.0001]. Differences in other adipokines were not statistically significant. Adiponectin level correlated negatively with vWF levels (ρ = -0.29, P < 0.05) and PAI-1 (ρ = -0.36, P < 0.05) and A-FABP positively with vWF (ρ = 0.61, P < 0.05) and PAI-1 (ρ = 0.47, P < 0.05) and augmentation index (ρ = 0.26, P < 0.05). Multivariate regression analysis showed independent association between A-FABP and vWF (b = 0.24, P < 0.05). CONCLUSIONS: Patients with T2D have significantly higher levels of A-FABP and lower levels of adiponectin. These adipokines correlate with indicators of vascular damage and could contribute to cardiovascular risk in patients with T2D. A-FABP may participate in direct endothelium damage.
- MeSH
- adipokiny krev MeSH
- adiponektin krev MeSH
- biologické markery krev MeSH
- diabetes mellitus 2. typu krev komplikace MeSH
- diabetické angiopatie krev MeSH
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- metabolický syndrom MeSH
- proteiny vázající mastné kyseliny krev MeSH
- průřezové studie MeSH
- rizikové faktory MeSH
- tuhost cévní stěny MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
