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《Journal of biological dynamics》2013,7(2):117-130
We address several conjectures raised in Cantrell et al. [Evolution of dispersal and ideal free distribution, Math. Biosci. Eng. 7 (2010), pp. 17–36 [9]] concerning the dynamics of a diffusion–advection–competition model for two competing species. A conditional dispersal strategy, which results in the ideal free distribution of a single population at equilibrium, was found in Cantrell et al. [9]. It was shown in [9] that this special dispersal strategy is a local evolutionarily stable strategy (ESS) when the random diffusion rates of the two species are equal, and here we show that it is a global ESS for arbitrary random diffusion rates. The conditions in [9] for the coexistence of two species are substantially improved. Finally, we show that this special dispersal strategy is not globally convergent stable for certain resource functions, in contrast with the result from [9], which roughly says that this dispersal strategy is globally convergent stable for any monotone resource function. 相似文献
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Dagmara Baraniak Piotr Ruszkowski Daniel Baranowski Grzegorz Framski Jerzy Boryski 《Nucleosides, nucleotides & nucleic acids》2013,32(12):980-1005
AbstractTwo series of novel fluorinated nucleosides dimers with an unnatural 1,2,3-triazole linkage were synthesized. The obtained molecules were prepared using “click” chemistry approach based on copper(I) catalyzed Huisgen azide–alkyne cycloaddition. It was performed between 3′- and 5′-azido-nucleosides as the azide components, and the 3′-O- and 5′-O-propargyl-nucleosides as the alkyne components. Based on analysis of the 3JHH, 3JH1′C2 and 3JH1′C6 we estimated conformational preferences of sugar part and orientation around glycosidic bond. All described nucleosides dimers analogs were characterized by spectroscopic methods and evaluated for their in vitro cytotoxicity in three human cancer cell lines: cervical (HeLa), oral (KB) and breast (MCF-7). 相似文献
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Cajus Diedrich 《Ichnos》2013,20(3-4):215-228
This article examines the high-resolution track horizon stratigraphy at the outcrop Obernkirchen. Massive sandstones, products of marine sand bar and fluviatile environments are present at the tracksite. Recently two track beds were examined in the outcrop. One new track slab of the lower track bed is described exposing well-preserved quadrupedal iguanodontid tracktypes of Iguanodontipus Sarjeant, Delair, and Lockley, 1998, and bipedal theropod tracks Megalosauropus Kaever and Lapparent, 1974. The ichnogenus Iguanodontipus is discussed and the diagnosis extended. The tracksite Obernkirchen belongs to a megatracksite of the ancient coastline of the marginal marine Hercynic Basin of the Lower Cretaceous of Europe, including the four well-known sites Obernkirchen, Bad Rehburg, Münchehagen, and Bückeburg of Northwest Germany. Three different tracktypes of huge sauropods, theropods, and ornithopods are abundant at basal Lower Cretaceous siliciclastic coastlines in different regions in Spain, Portugal, England, Germany, and Switzerland. Dinosaur tracks are also present in carbonate platform environments of northern Italy and Istria. 相似文献
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Abstract Hydrochus ignicollis Motschulsky, 1860 is recorded from Iran (Gilan Province) for the first time. In addition, new Iranian provincial records are provided for two species: H. nodulifer Reitter, 1897 (Zanjan Province) and H. farsicus Hidalgo-Galiana, Jäch, and Ribera, 2010 (Kohgiluyeh and Boyer-Ahmad Province). Photographs of the habitus, the male genitalia and the habitat of H. ignicollis are provided. 相似文献
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《Biodemography and social biology》2013,59(1):42-66
Recent adaptationist accounts of human mental and physical health have reinvigorated the debate over the evolution of human intelligence. In the tradition of strong inference the current study was developed to determine whether either Miller's (1998, 2000a) Fitness Indicator Theory or Rushton's (1985, 2000) Differential-K Theory better accounts for general intelligence (“g”) in an undergraduate university population (N = 192). Owing to the lengthy administration time of the test materials, a newly developed 18-item short form of the Ravens Advanced Progressive Matrices (APM-18; Sefcek, Miller, and Figueredo 2007) was used. A significant, positive relationship between K and F (r = .31, p < .001) emerged. Contrary to predictions, no significant relationships were found between “g” and either K or F (r = –.09, p ≥ .05 and r = .11, p ≥ .05, respectively). Though generally contrary to both hypotheses, these results may be explained in relation to antagonistic pleiotropy and a potential failure to derive correct predictions for within-species comparisons directly from the results of between-species comparisons. 相似文献
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Shuqian Zhang 《Molluscan research.》2015,35(1):17-23
The species of genus Antillophos Woodring, 1928 from the China seas are studied. Six species, Antillophos liui n. sp., Antillophos lucubratonis Fraussen & Poppe, 2005, Antillophos monsecourorum Fraussen & Poppe, 2005, Antillophos pyladeum (Kato, 1995), Antillophos roseatus (Hinds, 1844) and Antillophos sp., are described and illustrated.http://zoobank.org/urn:lsid:zoobank.org:pub:51481997-A841-4F37-8E15-B753DC99CB4D 相似文献
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Ilya V. Buynevich 《Ichnos》2013,20(4):189-191
Recognition and sampling of traces in unconsolidated sands present a major challenge for ichnologists. This can be partially remedied through the application of high-resolution geophysical techniques, such as ground-penetrating radar (GPR or georadar), which uses electromagnetic impulse for continuous imaging of shallow subsurface. It addition to geological applications, GPR imaging has been used in several studies focused on animal traces as related to conservation of endangered fossorial species (Kinlaw et al., 2007; Martin et al., 2011), slope and levee stability (Nichol et al., 2003; Di Prinzio et al., 2010), and mapping of fossil tracks (Matthews et al., 2006; Aucoin and Hasbargen, 2010) and tracking surfaces (Webb, 2007). Few efforts have been dedicated specifically to characterizing burrow and track characteristics (Stott, 1996; Sensors & Software Inc., 2010 [compilation on geophysical projects related to animal burrows]; Buynevich and Hasiotis, 2011; Buynevich et al., 2011; Martin et al., 2011) and most of the above studies are published in journals not routinely accessed by ichnologists. 相似文献
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Phylloicus Müller, 1880 and Banyallarga Navás, 1916 are endemic Neotropical genera of Calamoceratidae. Currently, Phylloicus has 55 extant species, 19 of which are recorded from Brazil, and a fossil species from Dominican amber. In this paper, a new species of Phylloicus is described and illustrated from specimens collected in Amazonas State, Brazil. This new species has peculiar hind wing venation, with vein R4 attached basally to the base of R2+3. Therefore, a modified diagnosis to the genus is presented to include Phylloicus dumasi sp. nov. The new species is somewhat similar to P. paprockii Prather, 2003, but can be distinguished from these and other Phylloicus species by the atypical hind wing venation, uniform colouration, and male genitalia with tergum IX produced posteriorly into two wide lobes. 相似文献
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Two new sites with mammalian footprints in the early Oligocene of southeastern France are described here. They represent one of the best preserved and more numerous record of tracks and trackways in the world with more than 320 ichnites. Many of those are arranged in trackways and sometimes show pes-manus impressions, a quite rare feature in mammalian ichnology. The ichnotaxonomic study indicates the presence of perissodactyls tracks referred to as Rhinoceripeda voconcense (Demathieu et al., 1984), artiodactyls footprints referred to as Megapecoripeda velox (Demathieu et al., 1984) and a carnivore footprint referred to as Bestiopeda sp. Vialov (1966). They can be attributed to early Rhinocerotids, Lophiomerycids and/or Entelodonts and Mustelid-like carnivore, respectively. This study also aims at homogenizing the ichnotaxonomy used for mammal tracks where several genera were erected without a full review of the literature. All this taken together reveals a rich mammalian ichnofauna at a time period when no other fossils of mammals are known in the area and represents a good opportunity to provide state-of-the-art concerning the worldwide known sites that yielded mammalian footprints. 相似文献
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Shraddha Thakkar Nisha Nanaware-Kharade Guillermo Gonzalez III Reha Celikel Eric Peterson 《Journal of biomolecular structure & dynamics》2013,31(1):112-113
Methamphetamine (METH) abuse is a major threat in the USA and worldwide without any FDA approved medications. Anti-METH antibody antagonists block or slow the rate of METH entry into the brain and have shown efficacy in preclinical studies (Peterson, Laurenzana, Atchley, Hendrickson, & Owens, 2008).?A key determinant of the antibody’s efficacy is its affinity for METH and we attempted to enhance the efficacy by designing mutations to alter the shape or the electrostatic character of the binding pocket. Towards this goal, we developed a single chain anti-METH antibody fragment (scFv6H4) from a parent IgG (1). The crystal structure of scFv-6H4 in complex with METH was determined (Celikel, Peterson, Owens, & Varughese, 2009). Based on its elucidated binding interactions, we designed point mutations in the binding pocket to improve its affinity for METH and amphetamine (AMP), the active metabolite of METH. The mutants, scFv-S93T,-I37?M and -Y34?M were cloned, expressed in yeast and tested for affinity against METH and AMP. Two mutants showed enhanced binding affinity for METH: scFv-I37?M by 1.3-fold and scFv-S93T by 2.6-fold. Additionally, all the mutants showed increase in affinity for AMP: scFv-I37?M by 56-fold, scFv-S93T by 17-fold and scFvY34?M by 5-fold. Crystal structure for one of the high-affinity mutant, scFv-S93T, in complex with METH was determined (Figure 1). Binding pocket of the mutant is more hydrophobic in comparison with the wild type. ScFv-6H4 binds METH in a deep pocket containing two water molecules. The substitution of a serine residue by a threonine leads to the expulsion of a water molecule (Figure 2), relieving some unfavorable contacts between the hydrocarbon atoms of METH and the water molecule and increasing the affinity to sub-nanomolar range. Therefore, the present study shows that efficacy could be enhanced by altering the hydrophobicity or the shape of the binding pocket. 相似文献
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This paper contains a taxonomic study of the Permian tetrapod ichnofauna from the Carapacha Basin. Tetrapod traces are analyzed in their environmental context and compared with similar faunas from Europe and North America. This ichnofauna is particularly relevant because of the scarcity of Permian tetrapod tracks from South America and also of Permian tetrapod fossils from Argentina. Ephemeral fluvial and shallow lacustrine deposits compose the sedimentary succession of the basin, which is represented by the Carapacha Formation. Most of the tracks have been collected from the upper member of the formation (Urre-Lauquen Member), mainly from freshwater ephemeral lake deposits as well as from playa-lake mudflats. The deposits of this member have been attributed to the early Late Permian on the basis of a Glossopteris fossil flora. Ichnotaxonomic designations of tetrapod traces are made on the basis of morphologic features that reflect the anatomy of the producer and special attention has been paid to extramorphologic deformations observed in the track assemblage. A total of four footprint ichnotaxa have been recognized, namely Batrachichnus salamandroides (Geinitz, 1861), Hyloidichnus bifurcatus Gilmore, 1927, cf. Amphisauropus isp. and cf. Varanopus isp. These track taxa are associated with two forms of vertebrate swimming traces (Characichnos isp. and type A swimming trace) and a possible fish trail. Invertebrate trace fossils include abundant arthropod locomotion traces and Scoyenia isp. The ichnofauna is composed of six tetrapod ichnocoenoses that are dominated by tiny amphibian tracks attributed to Temnospondyli (Batrachichnus and type A swimming trace) and Seymouriamorpha (Amphisauropus), and also contain the footprints of small reptiles, mostly Captorhinomorpha and possibly Pelycosauria (Hyloidichnus and Varanopus). Even if the ichnofauna of the Carapacha Basin is slightly younger than typical examples from the literature of the Early Permian “red bed ichnofacies” (Hunt et al., 1995b), a comparison is made. However, further detailed case studies are needed to formally define this “red bed ichnofacies” and its prospective subdivisions. 相似文献
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Sunil Kumar Dixit Durga Prasad Hota Parvathy Rajan Dr Prasanta Kumar K Mishra Tapas Kumar Goswami Manish Mahawar 《Preparative biochemistry & biotechnology》2017,47(2):137-142
Intraphagocytic survival of Salmonella Typhimurium (ST) depends (at least in part) upon its ability to repair oxidant-damaged macromolecules. Met residues either free or in protein bound form are highly susceptible to phagocyte-generated oxidants. Oxidation of Mets leads to Met-SO formation, consequently loss of protein functions that results in cell death. Methionine sulfoxide reductase (Msr) reductively repairs Met-SO to Met in the presence of thioredoxin (trx) and thioredoxin reductase (trxR). Earlier we reported that methionine sulfoxide reductase A (msrA) gene deletion strain of ST suffered oxidative stress.[1] Thioredoxin system of ST comprises of two thioredoxins (trxA and trxC) and one thioredoxin reductase (trxB). Preferred trx utilized in MsrA-mediated repair of Met-SO is not known. In current study, we cloned, expressed, and purified ST TrxA, TrxB, TrxC, and MsrA in recombinant forms. The migration of TrxA, TrxB, TrxC, and MsrA proteins was approximately 10, 36, 16, and 26?kDa on SDS-gels. The nicotinamide adenine dinucleotide phosphate hydrogen (NADPH)-linked reductase assays interpreted that MsrA utilized two times more NADPH for the reduction of S-methyl p-tolyl sulfoxide when TrxA was included in the assays as compared to TrxC. 相似文献
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Maxim Nabozhenko 《Zoology in the Middle East.》2013,59(1):64-68
Five species of the genus Catomus Allard, 1876 are known from Iran. Catomus fragilis (Ménétriés, 1848) is recorded from Iran for the first time. Lectotypes of C. persicus Allard, 1876 (type species of the genus) and C. semiruber Allard, 1876 are designated. These species are also redescribed and figured. A key to the species of Catomus in the Iranian fauna is given. 相似文献
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Srinivas Gopu Vuradi Ravi kumar Kotha Laxma Reddy Putta Venkat Reddy 《Nucleosides, nucleotides & nucleic acids》2019,38(5):349-373
A novel ligand BOPIP (BOPIP?=?{2-(4-(benzyloxy)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline}) and its mononuclear Ru(II) polypyridyl complexes [Ru(phen)2 BOPIP]2+(1) (phen?=?1,10-Phenanthrolene), [Ru(bpy)2 BOPIP]2+(2) (bpy?=?2,2′ bipyridyl), [Ru(dmb)2 BOPIP]2+(3) (dmb?=?4, 4′ -dimethyl 2, 2′ -bipyridine), [Ru(Hdpa)2 BOPIP]2+(4) (Hdpa?=?2,2′dipyridylamine) have been synthesized successfully and characterized by elemental analysis, UV-vis, IR, 1H, 13C-NMR, and ESI-MS Spectroscopy. The interaction of these complexes with CT-DNA was studied using absorption, emission techniques, viscosity measurements and molecular docking studies. The docking study also supports the binding ability of complexes obtained through the absorption and emission techniques. These studies reveal that the Four Ru(II) polypyridyl complexes bind to DNA predominantly by intercalation. The Antimicrobial activity and cytotoxicity of these complexes are also reported. 相似文献