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101.
102.
The question of a common receptor for colicins E1, E2 and E3 was studied by comparing the kinetics of their action in different colicin mixtures with that of each colicin alone.The rate of specific adsorption of colicins was studied in two ways: by assaying the decreasing amount of free colicin in the solution (direct) and by determining the numbers of surviving colony-forming bacteria (indirect). At the same multiplicity, the rate of adsorption and inhibitory effect varied for each colicin tested (E1, E2, E3 and K).These differences were the basis of our study on the inhibitory effects of mixtures of two colicins added either simultaneously or successively.The results were conclusive: E1 and K bind to receptor sites different from a common receptor site for colicins E2 and E3. Thus colicin E1 should be excluded from the E group. It is suggested to sign it J as previously.The authors wish to thank Dr. B. marda for his mathematical advice. 相似文献
103.
Taxonomy and biogeography of Bunopus spatalurus (Reptilia; Gekkonidae) from the Arabian Peninsula 下载免费PDF全文
Philip de Pous Luis Machado Jan Červenka Lukáš Kratochvíl Nefeli Paschou Tomáš Mazuch Jiří Šmíd Marc Simó‐Riudalbas Delfi Sanuy Salvador Carranza 《Journal of Zoological Systematics and Evolutionary Research》2016,54(1):67-81
In the last decade, taxonomic studies have drastically increased the number of species known to inhabit the Arabian deserts. While ongoing phylogenetic studies continue to identify new species and high levels of intraspecific genetic diversity, few studies have yet explored the biogeographic patterns in this arid region using an integrative approach. In the present work, we apply different phylogenetic methods to infer relationships within the Palearctic naked‐toed geckos. We specifically address for the first time the taxonomy and biogeography of Bunopus spatalurus Anderson, 1901, from Arabia using multilocus concatenated and species tree phylogenies, haplotype networks and morphology. We also use species distribution modelling and phylogeographic interpolation to explore the phylogeographic structure of Bunopus spatalurus hajarensis in the Hajar Mountains and the roles of climatic stability and possible biogeographic barriers on lineage occurrence and contact zones in this arid mountain endemism hot spot. According to the inferred topology recovered using concatenated and species tree methods, the genus ‘Bunopus’ is polyphyletic. Bunopus tuberculatus and B. blanfordii form a highly supported clade closely related to Crossobamon orientalis, while the two subspecies of ‘Bunopus’ spatalurus branch together as an independent highly supported clade that diverged during the Miocene according to our estimations. Within B. s. hajarensis, three geographically structured clades can be recognized that according to our estimations diverged during the Late Miocene to Pliocene. The paleodistribution models indicate climatic stability during the Late Pleistocene and the lineage occurrence, and predicted contact zones obtained from phylogeographic interpolation therefore probably result from the older splits of the groups when these lineages originated in allopatry. As demonstrated by the results of the multilocus molecular phylogenetic analyses and the topological test carried out in this study, the genus ‘Bunopus’ is not monophyletic. To resolve this, we resurrect the genus Trachydactylus Haas and Battersby, 1959; for the species formerly referred to as Bunopus spatalurus. Considering the morphological differences, the high level of genetic differentiation in the 12S mitochondrial gene and the results of the phylogenetic and the cmos haplotype network analysis, we elevate Trachydactylus spatalurus hajarensis to the species level Trachydactylus hajarensis (Arnold, 1980). 相似文献
104.
V práci byly studovány rozdíly v ú?innosti kyseliny β-(3-pyridyl)-propionové (VIII) a β-(3-pyridyl)-akrylové (IX) v závislosti na stupni nenasycení pobo?ného ?etězce. Obě kyseliny inhibují r?st ko?ene i hypokotyluSinapis alba L. a zp?sobují inhibici sukcinátdehydrogenázového enzymového systému. Kyselina IX inhibuje zmíněný systém p?ibli?ně na dvojnásobek inhibice kyseliny VIII. Cytochromoxydázový systém z?stává témě? neovlivněn. Na základě experimen tálních výsledk? byla zp?esněna strukturní podmínka fytotoxické aktivity modelových slou?enin typu I v tom smyslu, ?e v?echny slou?eniny této struktury inhibují kromě r?stu také aktivitu sukcinátdehydrogenázového systému. 相似文献
105.
Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 μmol m−2 s−1) or medium irradiance (MI, 200 μmol m−2 s−1) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these
dry lichens were exposed to high irradiance (HI, 1 000 μmol m−2 s−1) for 60 h. After this HI treatment, the maximal photochemical quantum yield (FV/FM) and the de-epoxidation state of xanthophyll cycle pigments (DEPS) were highest in thalli preconditioned to MI. Hence irradiance
in the last hydrated period before sampling is significant for the physiological state of lichens. A standardized irradiance
pre-treatment before start of experiments is recommended. 相似文献
106.
107.
In this paper, we report the results of a systematic attempt to relate the intrinsic plasma membrane fluidity of three different
cell lines to their electroporation behaviour, which consists of reversible and irreversible electroporation. Apart from electroporation
behaviour of given cell lines the time course required for membrane resealing was determined in order to distinguish the effect
of resealing time from the cell’s ability to survive given electric pulse parameters. Reversible, irreversible electroporation
and membrane resealing were then related to cell membrane fluidity as determined by electron paramagnetic resonance spectroscopy
and computer characterization of membrane domains. We found that cell membrane fluidity does not have significant effect on
reversible electroporation although there is a tendency for the voltage required for reversible electroporation to increase
with increased membrane fluidity. Cell membrane fluidity, however, may affect irreversible electroporation. Nevertheless,
this effect, if present, is masked with different time courses of membrane resealing found for the different cell lines studied.
The time course of cell membrane resealing itself could be related to the cell’s ability to survive. 相似文献
108.
S. M. Stanis˘ić Stojić L. M. Ignjatović S. Popov S. Škrivanj A. R. Đorđević A. Stojić 《Plant biosystems》2016,150(1):104-110
An experiment was undertaken to evaluate the effect of liquid manure amendment on heavy metal accumulation in wheat and barley. For this purpose, both kinds of seedlings were grown simultaneously in a Petri dish, while wheat seedlings were also grown in pots containing unpolluted agricultural soil. All of the seedlings were irrigated with one of the three prepared solutions: artificial rainwater solution, heavy metal solution and liquid manure solution containing NH4NO3, H3PO4 and KOH along with equal amounts of heavy metals as in the second solution. Twenty days later, 1 g of plant tissue was digested with the mixture of HNO3 and H2O2 for ICP-OES/HG-ICP-OES analysis. The results showed that the uptake of arsenic and mercury was highest for both plants grown in a Petri dish. Furthermore, the wheat grown in a Petri dish also had a high content of nickel, cadmium and copper, while the pot-grown wheat contained high amounts of iron and manganese, probably due to the adsorption of nickel, cadmium, copper and mercury on soil phases. The lower uptake of all heavy metals was observed after the amendment of liquid manure, with the exception of manganese in wheat and mercury in all plants. 相似文献
109.
Maintenance of genomic stability is of crucial importance for all living organisms. It is no surprise that during evolution,
a series of highly selective and efficient systems to detect DNA damage and control its repair have evolved. To this end,
signal transduction pathways are involved in pausing the cell division cycle to provide time for repair, and ultimately releasing
the cell cycle from arrest. Genetic components of the damage and replication checkpoints have been identified and a working
model is beginning to emerge. This area of biological inquiry has received a great deal of attention in the past decade with
the realization that the underlying regulatory mechanisms controlling the cell cycle are conserved throughout eukaryotic evolution.
Many of the key players in this response have structural and functional counterparts in species as diverse as yeast and human.
In recent years attention has also been paid to the plant kingdom suggesting that checkpoint controls have been highly conserved
during evolution. The unicellular green alga Chlamydomonas reinhardtii is a suitable model organism for the study of basic cellular processes including cell cycle regulation and DNA repair. To
investigate how algal cells accomplish these tasks, we have isolated mutants in the recognition and repair of DNA damage or
in the response to DNA damage.
Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia. 相似文献
110.
A methodology is proposed for assessing the ecological value of streams in the catchment of the Moravská Dyje River. It is concluded that by using a wide range of parameters that a more objective assessment is achieved than if only one were used. The landscape of the catchment studied contains excessive amounts of nutrients and, in comparison to its natural state, has become too uniform. 相似文献