The degradation of RNA in the cyclically perfused rat liver was determined from the release of labeled cytidine from RNA that had been previously labeled with 6-14Corotic acid in vivo. Because ...cytidine is not appreciably degraded in rat liver (its deamination to uridine is virtually nil) or produced in significant amounts from free 5'-nucleotides, its release will directly reflect net RNA breakdown. This conclusion was substantiated by the fact that the specific radioactivity of released cytidine equaled that of CMP in RNA and remained unchanged for 180 min of perfusion. The initial rate of 14Ccytidine accumulation was slow, but after 10-20 min it increased abruptly by more than 4-fold and remained virtually constant. The addition of 0.5 mM unlabeled cytidine effectively prevented the reutilization of label and increased the rate of labeled cytidine release by an amount representing 13% of the maximal rate of cytidine accumulation. Rates of RNA degradation, measured between 20 and 60 min in the presence of 0.5 mM unlabeled cytidine, averaged 1.00 +/- 0.05 mg h-1 liver-1 (100-g rat), the equivalent of 65% of total RNA per day. This accelerated value, which was about 4-fold larger than the initial rate, is believed to be the direct consequence of amino acid deprivation since, in separate experiments, the increase was completely suppressed by the addition of plasma amino acids (Lardeux, B. R., and Mortimore, G. E. (1987) J. Biol. Chem. 262, 14514-14519). These findings demonstrate the potential value of cytidine as a marker for following moment-to-moment regulatory alterations in RNA degradation in the isolated liver or hepatocyte preparation.
Binding of human polymeric IgA ligand to its epithelial cell polymeric Ig receptor, pIgR, has been shown to stimulate pIgR apical transcytosis in an in vitro system, based on polarized confluent MDCK ...cells expressing rabbit pIgR. The present study aimed at testing whether such a stimulation also occurs in vivo. Transcytosis of pIgR was monitored by rat liver output of total secretory component (SC) into bile, measured by radial immunodiffusion as the sum of free SC and pIgA-bound SC. Whereas in the perfused rat liver system addition of pIgA to the perfusate showed no effect, i.v. injection of human and rat pIgA, but not of monomeric IgA nor PBS, in living rats significantly increased total bile SC output for more than 1 h. Furthermore, depletion of the normal pIgA level circulating in the liver before injecting more pIgA was not required to show the stimulation. Our data thus strongly suggest that stimulation of liver pIgR transcytosis by pIgA ligand binding is physiologically relevant, helping to quickly adjust pIgA transport into bile to increase circulating pIgA levels, without need for increased SC/pIgR synthesis.
Attempts were made to use pteridine fluorescence levels as a tool for aging individual Aedes polynesiensis Marks and Culex quinquefasciatus Say mosquitoes. Fluorescent pigments were extracted and ...quantified with techniques and apparatus (i.e., a spectrofluorometer) that can be used in developing countries or in field laboratories, and that has already given consistent results in similar studies on other insect groups. However, for Ae. polynesiensis as well as Cx. quinquefasciatus, individual fluorescence measurements were mostly below the spectrofluorometer white noise level. With batches of Aedes or Culex of the same age, significant fluorescence levels were recorded but not in relation to their calendar ages. The low content of pteridines in mosquitoes suggests that standard spectrofluorometry is not sufficiently sensitive for such studies.
Hepatitis B and C viruses, two inducers of hepatocarcinomas, have been shown to activate AP-1, NF-kappa B and STAT in vitro, but no detailed information on the activity of these transcription factors ...in vivo have been provided.
We have measured the DNA binding activity of these transcription factors in the peri-tumoral and the tumoral parts of 15 primary liver cancers, of viral or non-viral etiologies, and in five hepatic metastases using electrophoretic mobility shift assays.
AP-1, NF-kappa B and STAT binding activities were increased in the peritumoral tissue, compared with histologically normal livers in 73, 87 and 70%, respectively, of the cases. A further activation of AP-1, NF-kappa B, but not STAT binding in the tumoral parts was detected in 40 and 80%, respectively, of the cases. A close correlation was found between JunD and c-Jun levels and AP-1 binding activity at the tumoral stage. By contrast, AP-1 and NF-kappa B binding activities were low or only slightly elevated in the peri-tumoral and the tumoral tissue of metastases.
Early activation of AP-1, NF-kappa B and STAT contributes probably to the acquisition of a transformed phenotype during hepatocarcinogenesis, whatever the etiology.
A new representative of the incertae sedis Cornulitidae is described from the Devonian of the western part of the Armorican massif (rade de Brest, Kerdreolet Formation, upper Emsian, patulus Zone). ...Reticornulites reticulatus n. gen., n. sp. is distinguished by a curved and flexuous conical shell, free of attachment(?), with a very typical reticulate ornamentation with predominant transverse rings and fine longitudinal striae. Specimens preserved as internal moulds and external casts; structure and microstructure unknown.Original Abstract: Une nouvelle forme de Cornulitidae (incertae sedis) provenant du Devonien du Massif armoricain (rade de Brest, Formation de Kerdreolet, Emsien superieur, zone a patulus) est decrite. Reticornulites reticulatus n. gen., n. sp., preserve a laetat daempreintes et de moules internes, est principalement caracterise par une coquille conique, courbe et flexueuse, apparemment libre daattache, pourvue daune ornementation treillissee a anneaux transversaux dominants. La structure et la microstructure de la coquille demeurent inconnues.
On Tereia Island, Rangiroa Atoll, 14,321 land crab burrows were treated with the copepod Mesocyclops aspericornis from January to June 1986, to control larvae of Aedes polynesiensis marks. In October ...1987, the entire island of Tereia was retreated (17,300 burrows), and the neighboring island, Voisin, was left untreated as a control. From 5 to 15 mo after treatment, burrows with M. aspericornis contained an average of 2 Ae. polynesiensis immatures compared with 97 immatures from untreated burrows. Long-term larval control was successful in low-lying areas where burrows remained wet or were reflooded. Although there may have been other contributing factors, the major reason for lack of persistence of M. aspericornis in burrows over the entire island appeared to be poor resistance to desiccation. From all treated burrows in October 1987, M. aspericornis subsequently was found in 89.5, 39.1, and 24.1% of burrows sampled 5, 8, and 15 mo after treatment, respectively. The broad-scale results for Tereia indicated that there was no reduction of adult biting indices when compared with Voisin. Mark-release experiments on four occasions indicated that Ae. polynesiensis had a limited flight range and that the probability for interisland movement was low
Non stationary operator selection with island models Candan, Caner; Goëffon, Adrien; Lardeux, Frédéric ...
Proceedings of the 15th annual conference on Genetic and evolutionary computation,
07/2013
Conference Proceeding
The purpose of adaptive operator selection is to choose dynamically the most suitable variation operator of an evolutionary algorithm at each iteration of the search process. These variation ...operators are applied on individuals of a population which evolves, according to an evolutionary process, in order to find an optimal solution. Of course the efficiency of an operator may change during the search and therefore its application should be precisely controlled. In this paper, we use dynamic island models as operator selection mechanisms. A sub-population is associated to each operators and individuals are allowed to migrate from one sub-population to another one. In order to evaluate the performance of this adaptive selection mechanism, we propose an abstract operator representation using fitness improvement distributions that allow us to define non stationary operators with mutual interactions. Our purpose is to show that the adaptive selection is able to identify not only good operators but also suitable sequences of operators.
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