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1.
Attila Virág 《Journal of morphology》2012,273(12):1406-1423
The chequered pattern (often called Schreger pattern), which can be seen by unaided eye on transverse profiles of several proboscidean tusks and which can be emphasized by the spreading pattern of the cracks or by mineral discoloration, is an autapomorph feature of the clade Elephantoidea. The pattern differs among proboscidean taxa; therefore, it allows the coarse differentiation of elephants, mammoths, and some other basal groups. Such identification methods could facilitate efforts concerned with protection of the remaining elephant populations through ivory trade restrictions, since the tooth dentine from extinct Mammuthusprimigenius and from extant Loxodontaafricana and Elephasmaximus are the most common raw materials of the ivory carvings. The aim of this study was to show the internal structure of proboscidean ivory and to revise the existing theories on the aforementioned pattern of the elephantoids with reflections on the events which lead to the development of this microstructure. Thin sections and natural crack surfaces with various orientations of M.primigenius, Elephasantiquus, Prodeinotherium, and Deinotherium tusk fragments were used to produce a three‐dimensional model which explains the features on all profiles. The “phase shift” model is introduced, which assumes a sinusoid undulation of the dentinal tubules in radial profiles in the case of elephantoids. The model was confirmed by photomicrographs, scanning electron microscopic images, interpretation of natural crack surfaces, and radial displacement analysis of the dentinal tubules. The latter proved that the adjacent waves are not in the same phase. Several new nondestructive distinguishing methods are described here on the basis of the correlation between some microscopic and macroscopic features related to the Schreger pattern. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc. 相似文献
2.
Yasutaka Kakui Tomonari Sunaga Kunio Arai James Dodgson Liang Ji Attila Csikász-Nagy Rafael Carazo-Salas Masamitsu Sato 《Open biology》2015,5(6)
Integration of an external gene into a fission yeast chromosome is useful to investigate the effect of the gene product. An easy way to knock-in a gene construct is use of an integration plasmid, which can be targeted and inserted to a chromosome through homologous recombination. Despite the advantage of integration, construction of integration plasmids is energy- and time-consuming, because there is no systematic library of integration plasmids with various promoters, fluorescent protein tags, terminators and selection markers; therefore, researchers are often forced to make appropriate ones through multiple rounds of cloning procedures. Here, we establish materials and methods to easily construct integration plasmids. We introduce a convenient cloning system based on Golden Gate DNA shuffling, which enables the connection of multiple DNA fragments at once: any kind of promoters and terminators, the gene of interest, in combination with any fluorescent protein tag genes and any selection markers. Each of those DNA fragments, called a ‘module’, can be tandemly ligated in the order we desire in a single reaction, which yields a circular plasmid in a one-step manner. The resulting plasmids can be integrated through standard methods for transformation. Thus, these materials and methods help easy construction of knock-in strains, and this will further increase the value of fission yeast as a model organism. 相似文献
3.
A preparation method has been described to obtain a relatively pure and functionally intact fragmented sarcoplasmic reticulum (SR) vesicles fraction from normal and atrophied muscles. Purified SR preparations from rabbit gastrocnemius muscle atrophied by disuse showed similar protein composition (gel electrophoresis; Laemmli 1970) and similar vanadate induced crystallization (Dux and Martonosi 1983) properties of Ca2+-ATPase as those of control preparations. In the early period of atrophy (1-2 weeks) both the Ca2+-ATPase activity and Ca2+ uptake showed a 2-3-fold increase (from 3.42 +/- 0.24 to 7.34 +/- 0.25 mumol Pi X mg-1 prot X min-1 and from 1.26 +/- 0.10 to 3.36 +/- 0.22 mumol/l Ca2+ X min-1 X mg-1 prot. respectively). 相似文献
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5.
Evangelia G. Kranias Ramesh C. Gupta Gyorgyi Jakab Hae Won Kim Nancy A. E. Steenaart Stephen T. Rapundalo 《Molecular and cellular biochemistry》1988,82(1-2):37-44
Summary Canine cardiac sarcoplasmic reticulum is phosphorylated by adenosine 3,5-monophosphate (cAMP)-dependent and by calcium · calmodulin-dependent protein kinases on a 27 000 proteolipid, called phospholamban. Both types of phosphorylation are associated with an increase in the initial rates of Ca2+ transport by SR vesicles which reflects an increased turnover of elementary steps of the calcium ATPase reaction sequence. The stimulatory effects of the protein kinases on the calcium pump may be reversed by an endogenous protein phosphatase, which can dephosphorylate both the CAMP-dependent and the calcium · calmodulin-dependent sites on phospholamban. Thus, the calcium pump in cardiac sarcoplasmic reticulum appears to be under reversible regulation mediated by protein kinases and protein phosphatases. 相似文献
6.
S. Salvadori R. Guerrini V. Forlani S. D. Bryant M. Attila L. H. Lazarus 《Amino acids》1994,7(3):291-304
Summary Analysis of deltorphin A position 4 analogues included: backbone constrained N
MeHis, spinacine (Spi), N
MePhe and the tetrahydroisoquinoline-3-carboxylic acid (Tic); spatially confined side-chain (Phg); and imidazole alkylation ofl- andd-His4 enantiomers. High selectivity was lost with the following replacements: N
MeHis4, N
MePhe4 and Phg4 reduced binding and the constrained residues also increasedµ binding; ring closure between the side-chain and amino group to yield Spi4 or Tic4 increasedµ affinity. Imidazole methylation of His4 marginally affected opioid binding and doubled selectivity; alkylatedd-His4-derivatives generally maintained selectivity in spite of decreased affinities. Thus, His4 imidazole preserves selectivity by facilitating high binding and by repulsion at theµ receptor. Several low energy conformers of deltorphin A indicated that the His4 imidazole preferred a spatial orientation parallel to the phenolic side-chain of Tyr1 suggestive that this conformation might contribute to high affinity and selectivity. 相似文献
7.
Some biochemical properties of an acyclic oligonucleotide analogue. A plausible ancestor of the DNA?
Liliane Merle Gérard Spach Yves Merle János Sági Attila Szemzö 《Origins of life and evolution of the biosphere》1993,23(2):91-103
As acyclic oligonucleotides have been suggested as a primitive model of DNA or RNA in prebiotic times, we compared some biochemical properties of these analogues to that of natural ones. Firstly, an acyclic analogue of deoxyribonucleoside triphosphates was tested as a potential substrate of enzymes intervening in nucleic acids synthesis. GlyTTP, a dTTP analogue with a missing 2-methylene group is notaccepted as a substrate by either DNA polymerase or deoxynucleotidyl terminal transferase (TdT). Secondly, themodified dodecathymidylate (GlyT)12, the racemic acyclic sugar analogue of (dT)12, proved to be anefficient primer for DNA polymerase and TdT, though the associative properties of (GlyT)12 are very weak as shown by UV spectroscopy in phosphate buffer without magnesium chloride. But (GlyT)12 has the advantage to be 500-times more stable against hydrolysis by snake venom phosphodiesterase than the corresponding oligothymidylate. 相似文献
8.
Summary The effect of propionate on the growth and 4-androstene-3, 17-dion (AD) yield was investigated in cultures of Mycobacterium sp. NRRL B-3805 growing in minimal medium containing -sitosterol as substrate for selective side chain cleavage. Although the addition of propionate (PA) resulted in a concentration-dependent inhibition of growth at the beginning of fermentation, cultures started to grow in the presence of 0.1% of propionic acid reached an AD concentration 38% higher than the cultures growing in the absence of propionate during two day cultivation. After three days of incubation, the AD yields in cultures containing 0, 0.1 and 0.2% propionate at the inoculation were 68, 79 and 73%, while the protein levels were 2.01, 2.11 and 2.60 mg/ml, respectively. Our data showed that the positive effect of PA on the AD production from sterols by Mycobacterium sp. NRRL B-3805 could be explained by the induction of the enzymes of the methylmalonate pathway. The activity of propionyl-CoA carboxylase was about 30% higher in the crude extracts from the induced cultures growing in minimal medium, after 20 hours of growth, than in those from the controls (18.2 and 14.1 mU/mg, respectively, using propionyl-CoA as substrate). The distribution of the acid-stable 14C-radioactivity which built into methylmalonate, succinate and fumarate indicated that methylmalonyl-CoA mutase was also induced. Our data demonstrated that elimination of the toxic propionyl-CoA released from the side chain of the sterol is likely the rate-determining step of the AD production, at least at the beginning of the process. 相似文献
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10.