phenotypic plasticity Dotaz Zobrazit nápovědu
Vývojový aspekt přináší informace o faktorech růstu a modulace a o základních mechanismech zapojování nervových funkcí. Na druhé straně je ontogenetický výzkum ztížen trvalou proměnlivostí a mimořádnou dynamičností vývoje nervového systému. Přitom při činnosti nervového systému hraje důležitou úlohu jeho plasticita, kterou definujeme jako specifickou schopnost nervového systému se vyvíjet, reagovat na změny zevního a vnitřního prostředí, popř. se jim přizpůsobit a to za fyziologických i patologických situací.
The developmental aspect brings information on factors of growth and modulation, and about the basic mechanisms of the onset of functions. Contrary to it, ontogenetical research is complicated by factors of variability and large dynamism in the development of the nervous system.At the same time, in the activity of the nervous systeman important role plays plasticity, which is defined as a specific feature of the nervous system to develop or to respond to changes of the external and internal environment or to adjust to them both under physiological and pathological conditions.
- MeSH
- biologická evoluce MeSH
- fyziologická adaptace MeSH
- lidé MeSH
- mozek růst a vývoj MeSH
- neuroplasticita MeSH
- Check Tag
- lidé MeSH
Untangling the relationships between morphology and phylogeny is key to building a reliable taxonomy, but is especially challenging for protists, where the existence of cryptic or pseudocryptic species makes finding relevant discriminant traits difficult. Here we use Hyalosphenia papilio (a testate amoeba) as a model species to investigate the contribution of phylogeny and phenotypic plasticity in its morphology. We study the response of H. papilio morphology (shape and pores number) to environmental variables in (i) a manipulative experiment with controlled conditions (water level), (ii) an observational study of a within-site natural ecological gradient (water level), and (iii) an observational study across 37 European peatlands (climate). We showed that H. papilio morphology is correlated to environmental conditions (climate and water depth) as well as geography, while no relationship between morphology and phylogeny was brought to light. The relative contribution of genetic inheritance and phenotypic plasticity in shaping morphology varies depending on the taxonomic group and the trait under consideration. Thus, our data call for a reassessment of taxonomy based on morphology alone. This clearly calls for a substantial increase in taxonomic research on these globally still under-studied organisms leading to a reassessment of estimates of global microbial eukaryotic diversity.
Phenotypic plasticity is a common defensive strategy in species experiencing variable predation risk, such as habitat generalists. Larvae of generalist dragonflies can elongate their abdominal spines in environments with fish, but long spines render larvae susceptible to invertebrate predators. Long-spined specialists adapted to fish-heavy habitats are not expected to have phenotypic plasticity in this defence trait, but no empirical studies have been undertaken. Moreover, in comparison to prey responding to multiple predators that induce similar phenotypes, relatively little is known regarding how species react to combinations of predators that favour opposing traits. We examined plasticity of larval dragonfly Sympetrum depressiusculum, a long-spined habitat specialist. In a rearing experiment, larvae were exposed to four environments: (i) no predator control, (ii) fish cues (Carassius auratus), (iii) invertebrate cues (Anax imperator), as well as (iv) a combination of (ii) and (iii). Compared with the control, fish but not invertebrate cues resulted in longer spines for two (one lateral, one dorsal) of the six spines measured. Interestingly, the combined-cue treatment led to the elongation of all four dorsal spines compared with the fish treatment alone, whereas lateral spines showed no response. Our experiment provided evidence of morphological plasticity in a long-spined specialist dragonfly. We showed that nearly all spines can elongate, but also react differently under specific predator settings. Therefore, while spine plasticity evolved in direct response to a single predator type (fish), plasticity was maintained against invertebrate predators as long as fish were also present. Selective spine induction under the combined condition suggests that S. depressiusculum can successfully survive in environments with both predators. Therefore, phenotypic plasticity may be an effective strategy for habitat generalists and specialists. Although more studies are necessary to fully understand how selection shapes the evolution of phenotypic plasticity, we demonstrated that in dragonflies, presence or absence of a specific predator is not the only factor that determines plastic defence responses.
- MeSH
- biologické modely * MeSH
- fenotyp * MeSH
- fyziologická adaptace * MeSH
- larva MeSH
- potravní řetězec * MeSH
- vážky fyziologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Jedním z nejspornějších problémů v současné biologii a medicíně je existence plasticity kmenových buněk. Experimentální biologie a medicína pracuje s kmenovými buňkami a s využitím buněčné terapie již více než 20 let. Termínem plasticita se míní fenotypový potenciál kmenových buněk, který je širší, než jsou fenotypy diferencovaných buněk jejich původních tkání. Mnoho laboratoří již podalo důkaz o existenci plasticity kmenových buněk, ale vznikla celá řada námitek k prezentovaným výsledkům. Prezentujeme některé z námitek zpochybňující údaje o plasticitě kmenových buněk. Ve sdělení chceme poukázat na některé otázky a problémy spojené s plasticitou kmenových buněk, otázkami transdiferenciace a fúze buněk. Z dosavadních experimentálních výsledků můžeme říci, že kmenové buňky budou mít klíčovou úlohu v buněčné terapii. Toto sdělení představuje určitou sondu a úvod do diskuze určené pro plasticitu kmenových buněk a buněčnou terapii.
The most controversial problem in the present biology and medicine is the existence of stem cell plasticity. Experimental biology and medicine have been working with stem cells and stem cell therapy more than twenty years. The term plasticity, as it is understood, is the potential of stem cell phenotypes that is much broader that phenotypes of differentiated cells of their original tissues. Many laboratories have documented the existence of stem cell plasticity; however, many objections to the reported results still exist. Here, we present some of these objections questioning the data on stem cell plasticity. We wish to point out some problems associated with plasticity of stem cells, transdifferentiation and cell fusion. Recent experimental results indicate that stem cells may have a key role in stem cell therapy. This review is an introductory discussion on the stem cell plasticity and stem cell therapy.
Acta physiologica Scandinavica, ISSN 0302-2994 vol. 128, suppl. 558, 1986
62 s. : il., tab., grafy ; 24 cm
Body size is a fundamental trait correlated with nearly every aspect of animal life. It is influenced by numerous genetic and non-genetic factors. Despite its central importance, proximate mechanisms of intra- and interspecific variability in body size are still not well understood even in such a largely studied group as reptiles. For our study, we concentrated on the gecko species Paroedura picta. We investigated whether differences in sexual size dimorphism and in final and asymptotic snout-vent length (induced by a range of incubation and rearing temperatures) are correlated with differences in the number of presacral vertebrae. Moreover, we tested whether changes in this number were associated with evolutionary changes in sexual size dimorphism and body size in the genus Paroedura. We found that the variation in the number of presacral vertebrae is very limited both intra- and interspecifically, ranging between 26 and 28 vertebrae with most individuals possessing the modal number of 27. We conclude that changes in the number of vertebrae do not contribute to developmental plasticity or evolutionary changes in body size nor, in contrast to some other squamate lineages, to sexual size dimorphism.
Triple-negative breast cancer (TNBC) is a subtype of breast carcinoma known for its unusually aggressive behavior and poor clinical outcome. Besides the lack of molecular targets for therapy and profound intratumoral heterogeneity, the relatively quick overt metastatic spread remains a major obstacle in effective clinical management. The metastatic colonization of distant sites by primary tumor cells is affected by the microenvironment, epigenetic state of particular subclones, and numerous other factors. One of the most prominent processes contributing to the intratumoral heterogeneity is an epithelial-mesenchymal transition (EMT), an evolutionarily conserved developmental program frequently hijacked by tumor cells, strengthening their motile and invasive features. In response to various intrinsic and extrinsic stimuli, malignant cells can revert the EMT state through the mesenchymal-epithelial transition (MET), a process that is believed to be critical for the establishment of macrometastasis at secondary sites. Notably, cancer cells rarely undergo complete EMT and rather exist in a continuum of E/M intermediate states, preserving high levels of plasticity, as demonstrated in primary tumors and, ultimately, in circulating tumor cells, representing a simplified element of the metastatic cascade. In this review, we focus on cellular drivers underlying EMT/MET phenotypic plasticity and its detrimental consequences in the context of TNBC cancer.
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Mechanizmem přirozeného výběru může docházet k evoluci adaptivních znaků pouze u nepohlavne se rozmnožujících druhů. U druhů rozmnožujících se pohlavně vzniká genotyp jedince v každé generaci náhodným namixovaním genů od obou rodičů a biologická zdatnost (fitness) jedince se zde proto nededí. Pro vysvětlení fungování adaptivní evoluce u pohlavně se rozmnožujících organizmů byla V 70. letech minulého století navržena teorie sobeckého genu. Podle ní v průběhu evoluce nesoupeří jedinci v rámci populace o co největší biologickou zdatnost, ale alely v rámci jednoho lokusu o schopnost předat co nevíce svých kopií do genofondu další generace. Tato teorie ovšem opomíjí skutečnost, že vliv jednotlivých alel na fenotyp i vliv jednotlivých fenotypových znaků na biologickou zdatnost jedince závisí na tom, jaké další alely jsou přítomny v genotypu daného jedince. Teorie evolučně stabilních strategií ukazuje, že za těchto podmínek nemohou vést selekční tlaky k dlouhodobým změnám ve fenotypu organizmů, ale pouze k vychýlení frekvencí jednotlivých alel z rovnováhy. Cim je toto vychýlení větší, tím více genofond těmto dakům vzdoruje a po přerušení selekčního tlakj^u se frekvence alel samovolně vrací na původní hodnoty. Teorie zamrzlé plasticity, publikovaná v roce 1998, ukazuje, že pohlavně se rozmnožující druhy mohou evolučně odpovídat na selekční tlaky (jsou evolučně plastické) pouze v době, kdy jsou příslušníci daných druhů geneticky uniformní, tedy například po odštěpení a následném rychlém namnožení malé části populace původního druhu. Po určité době odhadované na základě paleontologických dat na 1-2% doby trvání druhu se v genofondu nahromadí genetický polymorfizmus a nové mutace se tak v každé generaci ocitnou ve společnosti jiných alel - druh se přestane chovat jako evolučně plastický a začne se chovat jako evolučně elastický. V tomto stavu pak existuje až do doby, než se v prostředí nahromadí takové změny, že evolučně zamrzlý druh vymře. Z teorie zamrzlé plasticity vyplývá řada důsledků pro nejrůznější vědní obory, včetně psychiatrie. Vzhledem k tomu, že druh může účelně evolučně odpovídat na vlivy prostředí pouze bezprostředně po svém vzniku, je naprostá většina druhů, se kterými se v přírodě setkáváme, včetně člověka, adaptována nikoli na podmínky, ve kterých momentálně žijí jejich příslušníci, ale na podmínky, které panovaly v době jejich vzniku. Teorie zamrzlé plasticity dále ukazuje, že vznik altruistického chování je mnohem pravděpodobnější, I než jak naznačovaly předcházející evoluční teorie.
The mechanism of natural selection can lead to the evolution of adaptive traits only amongst asexually reproducing organisms. Amongst organisms that reproduce sexually, the genotype of the individual is formed in each generation through the random mixin g of the genes of the two parents and thus the biological fitness of individuals is not inherited. The theory of the selfish gene was pro- posed in the 1970’s to explain the functioning of adaptive evolution amongst asexually reproducing organisms. According to this theory, individuals do not compete for the greatest biological fitness in the framework of the population during evolution, but rather the alleles compete in the framework of a single locus for the ability to transfer the greatest number of their copies to the g ene pool of the next generation. However, this theory neglects the fact that the effect of the individual alleles on the phenotype and the effect of the individual phenotype traits on the biological fitness of individuals depend on the other alleles that are present in the ge notype of the individual. The theory of evolutionarily stable strategies indicates that, under these conditions, selection pressures can not lead to long-term changes in the phenotypes of organisms, but only to deflection of the frequency of the individual alleles from equili brium. The greater this deflection, the more the gene pool resists this pressure and, after cessation of the selection pressure, the f requency of the alleles spontaneously returns to the original values. The theory of frozen plasticity, published in 1998, shows that sexually r eproducing species can respond evolutionarily to selection pressures (they are evolutionarily plastic) only when the members of the partic ular spe- cies are genetically uniform, i.e. after splitting off and subsequent rapid multiplication of part of the population of the ori ginal species. Following a short period of time, estimated on the basis of paleontological data to correspond to 1-2% of the duration of the s pecies, genetic polymorphism accumulates in the gene pool and thus, in each generation, the new mutations are in the presence of differ ent alleles – the species ceases to behave in an evolutionarily plastic manner and begins to be evolutionarily elastic. It then exi sts in this state until such time as such changes accumulate in the environment that the evolutionarily frozen species becomes extinct. A n umber of consequences follow from the theory of frozen plasticity for various fields of science, including biological psychiatry. As a species can usefully respond evolutionarily to the effect of the environment only immediately following its formation, the vast majorit y of the species that we encounter in nature, including human beings, are adapted, not to the conditions in which its members momentaril y live, but to the conditions that existed at the time of its formation. The theory of frozen plasticity further indicates that t he formation of altruistic behaviour is far more probable than was suggested by the previous theories of evolution.
- MeSH
- finanční podpora výzkumu jako téma MeSH
- fyziologická adaptace MeSH
- klasifikace MeSH
- krysa rodu rattus MeSH
- nervový systém růst a vývoj MeSH
- neurofyziologie metody MeSH
- neuroplasticita fyziologie MeSH
- vývojová biologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- přehledy MeSH
