Search results for "PREY"
showing 10 items of 117 documents
Evolution of tissue-specific keratins as deduced from novel cDNA sequences of the lungfish Protopterus aethiopicus.
2005
Lungfishes are possibly the closest extant relatives of the land vertebrates (tetrapods). We report here the cDNA and predicted amino acid sequences of 13 different keratins (ten type I and three type II) of the lungfish Protopterus aethiopicus. These keratins include the orthologs of human K8 and K18. The lungfish keratins were also identified in tissue extracts using two-dimensional polyacrylamide gel electrophoresis, keratin blot binding assays and immunoblotting. The identified keratin spots were analyzed by peptide mass fingerprinting which assigned seven sequences (inclusively Protopterus K8 and K18) to their respective protein spot. The peptide mass fingerprints also revealed the fac…
Sequence, evolution and tissue expression patterns of an epidermal type I keratin from the shark Scyliorhinus stellaris.
2004
From the shark Scyliorhinus stellaris we cloned and sequenced a cDNA encoding a novel type I keratin, termed SstK10. By MALDI-MS peptide mass fingerprinting of cytoskeletal proteins separated on polyacrylamide gels, we assigned SstK10 to a 46-kDa protein which is the major epidermal type I (“IE”) keratin in this fish and is specifically expressed in stratified epithelia. In a phylogenetic tree based on type I keratin sequences and with lamprey keratins applied as outgroup, SstK10 branches off in a rather basal position. This tree strongly supports the concept that teleost keratins and tetrapod keratins resulted from two independent gene radiation processes. The only exception is human K18 b…
Genes coding for intermediate filament proteins closely related to the hagfish "thread keratins (TK)" alpha and gamma also exist in lamprey, teleosts…
2005
The "thread keratins (TK)" alpha and gamma so far have been considered highly specialized intermediate filament (IF) proteins restricted to hagfish. From lamprey, we now have sequenced five novel IF proteins closely related to TKalpha and TKgamma, respectively. Moreover, we have detected corresponding sequences in EST and genomic databases of teleosts and amphibians. The structure of the TKalpha genes and the positions of their deduced amino acid sequences in a phylogenetic tree clearly support their classification as type II keratins. The genes encoding TKgamma show a structure typical for type III IF proteins, whereas their positions in phylogenetic trees favor a close relationship to the…
Vitellogenin from female and estradiol-stimulated male river lampreys (Lampetra fluviatilis L.)
2001
The influence of estradiol-17β (E2) on vitellogenesis is well documented for a number of oviparous craniates. We have examined the role that estradiol-17β plays in the induction and regulation of vitellogenin synthesis in the maturing European river lamprey, Lampetra fluviatilis. In both females and males the estradiol-17β concentrations in the plasma reached comparable maximum values in March, only a few weeks before spawning. Throughout the spawning run, the vitellogenin titer in the blood of females remains rather constant while the ovary volume increases. In contrast, we never found circulating VTG in untreated male lampreys. The synthesis and secretion of the yolk precursor molecule ca…
Competing species system as a qualitative model of radiation therapy
2016
To examine complex features of tumor dynamics we analyze a competing-species lattice model that takes into account the competition for nutrients or space as well as interaction with therapeutic factors such as drugs or radiation. Our model might be interpreted as a certain prey–predator system having three trophic layers: (i) the basal species that might be interpreted as nutrients; (ii) normal and tumor cells that consume nutrients, and (iii) therapeutic factors that might kill either nutrient, normal or tumor cells. Using a wide spectrum of parameters we examined survival of our species and tried to identify the corresponding dynamical regimes. It was found that the radiotherapy influence…
Coexistence of Mediterranean tits: A multidimensional approach
2013
[EN] Differential traits (e.g., feeding at different heights in trees) have evolved to allow the coexistence of putative competitors; such traits have been well studied in small passerines (e.g., Paridae), mainly during the winter. However, few studies have been carried out during the breeding season, when competition could be more intense. We applied here a multidimensional approach, examining ecological (prey type and size, and nesting habitat characteristics) and life history (timing of maximum nestling food demand) traits that might help to explain the coexistence of great (Parus major), crested (Lophophanes cristatus), and coal (Periparus ater) tits breeding in a Mediterranean pine for…
Experiments on Concurrent Artificial Environment
2001
We show how the simulation of concurrent system is of interest for both behavioral studies and strategies of learning applied on prey-predator problems. In our case learning studies into unknown environment have been applied to mobile units by using genetic algorithms (GA). A set of trajectories, generated by GA, are able to build a description of the external scene driving a predators to a prey. Here, an example of prey-predator strategy,based on field of forces, is proposed. The evolution of the corespondent system can be formalized as an optimization problem and, for that purpose, GA can be use to give the right solution at this problem. This approach could be applied to the autonomous r…
Social information use by predators : expanding the information ecology of prey defences
2022
Social information use is well documented across the animal kingdom, but how it influences ecological and evolutionary processes is only just beginning to be investigated. Here we evaluate how social transmission may influence species interactions and potentially change or create novel selection pressures by focusing on predator-prey interactions, one of the best studied examples of species coevolution. There is extensive research into how prey can use social information to avoid predators, but little synthesis of how social transmission among predators can influence the outcome of different stages of predation. Here we review evidence that predators use social information during 1) encount…
Strong antiapostatic selection against novel rare aposematic prey
2001
The evolution of aposematism, a phenomenon where prey species conspicuously advertise their unprofitability to predators, is puzzling. How did conspicuousness evolve, if it simultaneously increased the likelihood of an inexperienced predator to detect the prey and presumably kill it? Antiapostatic selection, where rare prey is predated relatively more often, is considered as another major difficulty for aposematism to evolve. However, the risk of being conspicuous in low frequencies has not been experimentally tested. We designed an experiment to test how frequency (4%, 12%, 32%) of conspicuous aposematic prey and its dispersion type (solitary vs. aggregated) affect an initial predation ri…
L'influence de l'hyperthyroidisation expérimentale sur le plumage des oiseaux carnivores: (note préliminaire) [Gaļas ēdāju putnu spalvojuma atkarība …
1931
Teksts franču valodā, kopsavilkums latviešu valodā.