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1.
Differential expression of two linked selection genes (HSVI-tk and Eco.gpt) in transformed teratocarcinoma and in L cells 总被引:1,自引:0,他引:1
C Lasserre J Thillet C Besnard D Bucchini R Pictet J Jami 《Journal of cellular physiology》1985,124(1):37-42
Upon transfection of (TK-)F9 teratocarcinoma stem-cells and (TK-)L fibroblasts with a plasmid carrying two selection genes, Eco.gpt and HSVI-tk, selection for gpt gene yielded ten times fewer colonies than selection for tk. Only the transformed clones selected for gpt had measurable xanthine guanine phosphoribosyltransferase (XGPRT) activity (Jami et al., 1983). Eco.gpt coding for XGPRT was under the control of simian virus 40 (SV40) early genes' regulating sequences (SV-gpt). In the present study, it was verified that the low efficiency of gpt selection in mouse cells was not due to the eucaryotic controlling sequences added to the bacterial gene. The transformed clones selected for tk that had no XGPRT activity possessed at least one uninterrupted copy of the composite SV-gpt gene and as many copies of the transforming plasmid as the cells selected for gpt expression. In a further test, the gpt gene was placed under the control of tk-regulating sequences and inserted with the tk gene in the same vector. Under these conditions, expression of XGPRT in the transformed clones selected for tk was improved, even though relative selection for gpt remained low. 相似文献
2.
The effects of cold exposure on calcitonin (CT) secretion were evaluated in young rats. Acute cold exposure (5 h to 5 degrees C) induced a rise in plasma CT concentrations and a decrease in thyroidal CT stores without change in total and ionized plasma calcium levels. The cold activation of sympathico-adrenomedullary axis and the inhibition of CT response to cold after beta-antagonist treatment might suggest that endogenous catecholamines can enhance CT secretion in young rats. Cold adaptation (3 weeks to 5 degrees C) induced a fall in plasma calcium concentration and a rise in thyroidal CT stores without change in plasma CT levels. The high plasma glucocorticoid levels which are known to occur during chronic cold exposure could be involved in the rise of thyroidal CT content in cold adapted rats. 相似文献
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Capsule Woodpigeon Columba palumbus nest-tree selection is affected by human disturbance, grazing and tree characteristics. Aims To determine the characteristics of trees used for nesting by Woodpigeons under two levels of grazing and disturbance in a Holm oak Middle Atlas forest, Morocco. Methods Woodpigeon nest-tree selection was investigated in highly disturbed and less-disturbed sites over two years (2010 and 2011). The features of nest-tree characteristics were determined by comparing the characteristics of trees used for nesting to those of randomly selected trees. Results Tree physical characteristics, grazing intensity and level of human disturbance were the main factors determining selection for nest-trees. Woodpigeons chose nesting trees that were greater in height, larger in DBH, lower in base of the live crown, in denser stands and at greater distance from tracks. Conclusions Forest management for Woodpigeon nest habitat selection should focus on controlling the access of vehicles especially trucks, introducing a rotating system of forest utilization for grazing and maintaining (without extending) the cereal crops. These recommendations may assist land managers to plan for continued persistence of this species in Middle Atlas forests. 相似文献
5.
Matheus E. Bianconi Luke T. Dunning Emma V. Curran Oriane Hidalgo Robyn F. Powell Sahr Mian Ilia J. Leitch Marjorie R. Lundgren Sophie Manzi Maria S. Vorontsova Guillaume Besnard Colin P. Osborne Jill K. Olofsson Pascal-Antoine Christin 《Proceedings. Biological sciences / The Royal Society》2020,287(1938)
C4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C4 and non-C4 populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata. We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C4 lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C4 phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C4 physiology away from its region of origin. 相似文献
6.
Guillaume Besnard Pierre‐Olivier Cheptou Malik Debbaoui Pierre Lafont Bernard Hugueny Julia Dupin Djamel Baali‐Cherif 《Ecology and evolution》2020,10(4):1876-1888
Self‐incompatibility (SI) is the main mechanism that favors outcrossing in plants. By limiting compatible matings, SI interferes in fruit production and breeding of new cultivars. In the Oleeae tribe (Oleaceae), an unusual diallelic SI system (DSI) has been proposed for three distantly related species including the olive (Olea europaea), but empirical evidence has remained controversial for this latter. The olive domestication is a complex process with multiple origins. As a consequence, the mixing of S‐alleles from two distinct taxa, the possible artificial selection of self‐compatible mutants and the large phenological variation of blooming may constitute obstacles for deciphering SI in olive. Here, we investigate cross‐genotype compatibilities in the Saharan wild olive (O. e. subsp. laperrinei). As this taxon was geographically isolated for thousands of years, SI should not be affected by human selection. A population of 37 mature individuals maintained in a collection was investigated. Several embryos per mother were genotyped with microsatellites in order to identify compatible fathers that contributed to fertilization. While the pollination was limited by distance inside the collection, our results strongly support the DSI hypothesis, and all individuals were assigned to two incompatibility groups (G1 and G2). No self‐fertilization was observed in our conditions. In contrast, crosses between full or half siblings were frequent (ca. 45%), which is likely due to a nonrandom assortment of related trees in the collection. Finally, implications of our results for orchard management and the conservation of olive genetic resources are discussed. 相似文献
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Audrey Boulamery Gais Kadra Nicolas Simon Thierry Besnard 《Chronobiology international》2013,30(5):961-968
There are no studies indicating a possible modification of imipenem pharmacokinetics related to the hour (i.e., circadian time) of its administration. The aim of this study was to evaluate the influence of different times of intramuscular imipenem administration on its disposition in Wistar AF EOPS rats. Four groups of eight animals were given a single intramuscular injection of 140 mg/kg of imipenem either at 10∶00, 16∶00, 22∶00, or 04∶00 h. Blood samples were collected 0.5, 1, 2, 3, 4, 6, and 8 h after drug injection, and the main pharmacokinetic parameters determined were Cmax, Tmax, elimination half‐life (t1/2), area under the concentration‐versus‐time curve (AUC), total serum clearance (CL/F), and volume of distribution (V/F). Circadian variation of Cmax (49%), Tmax (92%), and AUC (19%) was observed leading to variability of imipenem exposure. Clearance and volume of distribution were modified according to the circadian time of drug injection but did not reach statistical significance. The results suggest that varying the time of administration induces intra‐individual variability. 相似文献
9.
Capsule The nesting success of the Woodpigeon Columba palumbus in oak forests in Morocco is affected by human disturbance and nest-site characteristics. Aims To determine factors affecting the nesting success of Woodpigeons subject to two levels of disturbance in a holm oak Middle Atlas forest. Methods Woodpigeon nests were monitored in highly disturbed (n?=?30) and less-disturbed sites (n?=?60) over two years (2010–11). Logistic-exposure models were used to estimate daily nest-survival rate and evaluate mechanisms (altitude, temporal factors, nest location, nest-site habitat and degree of human influence) affecting nest survival. Results Daily nest-survival rate was higher in less-disturbed sites (0.987; 95% CL: 0.980–0.991) than in high-disturbance sites (0.967; 95% CL: 0.949–0.978). Increasing density of trees surrounding nest sites and distance from the nest tree to the closest track increased daily nest-survival rate. Conclusions Less-disturbed sites confer better nesting conditions than highly disturbed ones. Management measures should control the access of vehicles, especially trucks, in the forest of the Middle Atlas and introduce a grazing regime that will allow the forest regeneration, which would improve Woodpigeon nesting success by increasing the density of holm oak trees. 相似文献
10.
Adam Ahanchédé José E. F. Alfaya L. W. Andersen Didier Azam Ma. Anita M. Bautista Anne‐Laure Besnard Gregorio Bigatti Anthony Bouétard Marie‐Agnès Coutellec Eben‐Ezer B. K. Ewédjè Reiko Fuseya Ricardo GarcÍa‐Jiménez M. Haratian Olivier J. Hardy L.‐E. Holm Casey W. Hoy Eriko Koshimizu V. Loeschcke Violeta López‐Márquez Carlos A. Machado Annie Machordom C. Marchi Andrew P. Michel Claire Micheneau Omprakash Mittapalli Takahiro Nagai Nobuaki Okamoto Ying Pan F. Panitz N. Safaie Takashi Sakamoto B. Sharifnabi En‐Wei Tian Hui Yu 《Molecular ecology resources》2013,13(1):158-159
This article documents the addition of 83 microsatellite marker loci and 96 pairs of single‐nucleotide polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Bembidion lampros, Inimicus japonicus, Lymnaea stagnalis, Panopea abbreviata, Pentadesma butyracea, Sycoscapter hirticola and Thanatephorus cucumeris (anamorph: Rhizoctonia solani). These loci were cross‐tested on the following species: Pentadesma grandifolia and Pentadesma reyndersii. This article also documents the addition of 96 sequencing primer pairs and 88 allele‐specific primers or probes for Plutella xylostella. 相似文献