Automobile Reliance Among the Elderly: Race and Spatial Context Effects     

Brigitte Waldorf 《Growth and change》2003,34(2):175-201

Abstract Mobility is a necessary condition for the social and emotional well‐being of older people. To meet their mobility needs, the elderly assign pivotal importance to the automobile despite the potential challenge of driving cessation and searching for alternatives to automobile transportation. Older persons’ generally strong reliance on the automobile varies, however, by land use patterns (density) as well as by demographic and socioeconomic characteristics. This paper analyzes the effects of spatial context and personal attributes on automobile reliance among the elderly. Using the 1995 Nationwide Personal Transportation Survey (NPTS) trip data, two models of automobile reliance among elderly (65+) trip makers are estimated. The results show that spatial context effects of automobile reliance vary by demographic characteristics; in particular, they are more pronounced for black than for white elderly. Moreover, race variation in automobile reliance is strongest in urban locations rather than less dense spatial contexts. Finally, the differentiation between being a passenger rather than a driver is salient in order to understand locational and racial variations in automobile reliance among the elderly.  相似文献   

Sexual and somatic hybridization in the genus Lactuca     

Brigitte Maisonneuve  Marie Christine Chupeau  Yannick Bellec  Yves Chupeau 《Euphytica》1955,85(1-3):281-285

Summary Various genes for disease resistance identified in wild Lactuca are difficult, even impossible to exploit in lettuce breeding, due to sexual incompatibility between L. sativa and wild Lactuca sp. We adapted two cellular biology techniques to overcome these interspecific barriers: in vitro embryo rescue and protoplast fusion. In vitro rescue of immature embryos was used successfully for sexual hybridization between L. sativa and L. virosa. Vigorous hybrid plants were produced between L. sativa and seven accessions of L. virosa. Protoplast fusion permitted the regeneration of somatic hybrids between L. sativa and either L. tatarica or L. perennis. Hybrids between L. sativa and L. tatarica were backcrossed to L. sativa.  相似文献   

Effect of mannitol pretreatment to improve green plant regeneration on isolated microspore culture in Triticum turgidum ssp. durum cv. 'Jennah Khetifa'     

Z. Labbani    J. de Buyser    E. Picard 《Plant Breeding》2007,126(6):565-568

The use of doubled haploids improves the efficiency of cultivar development in many crops and can be helpful in genetic and molecular studies. The major problem with this approach is the low efficiency of green plant regeneration. We describe here an efficient method for inducing embryos and regenerating green plants directly from isolated microspores of durum wheat cv. ‘Jennah Khetifa’. Tillers from donor plants were pretreated in 0.3 m mannitol and were stored at 4°C at various times: 3, 5, 6, 7, 8, 10 and 12 days. Our results showed clearly that the novel pretreatment combined mannitol 0.3 m and cold for 7 days had a strong effect on the number of embryos produced and regenerated green plants. Under this condition 13 475 mature embryos were produced from 2 693 500 microspores. Moreover, 85 green plants were obtained. High green plants regeneration frequency was recorded. As an average 11.55 green plants were produced per 100 000 microspores (about the equivalent of six plants per spike). Therefore, this study showed clearly that our results are the best ones published until now in durum wheat.  相似文献   

Kinetics of chromium(III)‐oxidation in topsoils     

Brigitte Bhm  Walter R. Fischer 《植物养料与土壤学杂志》2004,167(1):22-23

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Analysis of photoperiod sensitivity within a collection of tropical maize populations   总被引：4，自引：0，他引：4  

Brigitte?GouesnardEmail author  Cécile?Rebourg  Claude?Welcker  Alain?Charcosset 《Genetic Resources and Crop Evolution》2002,49(5):471-481

We analyzed the variability of a large maize (Zea mays L.) collection of152 tropical populations for photoperiod sensitivity and grain productivityunder long-day conditions to investigate their potential adaptation to temperateconditions. A multilocal experimental design was used: one location withshort-day conditions (Guadeloupe), one location with medium-day conditions (latesowing in the south of France) and two locations with long-day conditions (earlysowing in both the North and South of France). The photoperiod sensitivity wasestimated by the slope of the regression of thermal time from sowing to 50%anthesis on photoperiod. We found highly significant effects of latitude andaltitude of the collecting site of the population on photoperiod sensitivity anda significant but small interaction between these two factors. Populationsoriginated from low altitudes and low latitudes are highly sensitive tophotoperiod, whereas highland populations never display a high photoperiodsensitivity, whatever the latitude of origin. Grain productivity under long-dayconditions was not highly correlated with photoperiod sensitivity. Andeanpopulations were little sensitive to photoperiod and exhibited poor grainproduction under long-day conditions. In contrast, some populations from theCaribbean such as populations from Cuban Flint and Early Caribbean racesexhibited a good grain production although sensitive to photoperiod. The goodadaptation of some Caribbean material to temperate conditions is consistent withthe hypothesis of the successful introduction of Caribbean germplasm in southernregions of the Old World.  相似文献   

In search of a maize ideotype for cell wall enzymatic degradability using histological and biochemical lignin characterization   总被引：1，自引：0，他引：1  

Méchin V  Argillier O  Rocher F  Hébert Y  Mila I  Pollet B  Barriére Y  Lapierre C 《Journal of agricultural and food chemistry》2005,53(15):5872-5881

Grass cell wall degradability is conventionally related to the lignin content and to the ferulic-mediated cross-linking of lignins to polysaccharides. To better understand the variations in degradability, 22 maize inbred lines were subjected to image analyses of Fasga- and M?ule-stained stem sections and to chemical analyses of lignins and p-hydroxycinnamic acids. For the first time, the nearness of biochemical and histological estimates of lignin levels was established. Combination of histological and biochemical traits could explain 89% of the variations for cell wall degradability and define a maize ideotype for cell wall degradability. In addition to a reduced lignin level, such an ideotype would contain lignins richer in syringyl than in guaiacyl units and preferentially localized in the cortical region rather than in the pith. Such enrichment in syringyl units would favor wall degradability in grasses, contrary to dicots, and could be related to the fact that grass syringyl units are noticeably p-coumaroylated. This might affect the interaction capabilities of lignins and polysaccharides.  相似文献   

Microinjection of a conserved peptide sequence of p34cdc2 induces a Ca2+ transient in oocytes   总被引：3，自引：0，他引：3  

A Picard  J C Cavadore  P Lory  J C Bernengo  C Ojeda  M Dorée 《Science (New York, N.Y.)》1990,247(4940):327-329

The product of the yeast cell cycle control gene cdc2, and its homologs in higher eukaryotes (p34cdc2), all contain a perfectly conserved sequence of 16 amino acids that has not been found in any other protein sequence. Microinjection of this peptide triggers a specific increase in the concentration of intracellular free Ca2+ that originates from intracellular stores in both starfish and Xenopus oocytes. Thus, p34cdc2 might interact through its conserved peptide domain with some component of the Ca2(+)-regulatory system.  相似文献   

Signal transduction and transcriptional regulation by glucocorticoid receptor-LexA fusion proteins   总被引：35，自引：0，他引：35  

P J Godowski  D Picard  K R Yamamoto 《Science (New York, N.Y.)》1988,241(4867):812-816

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Crystal structure of the malaria vaccine candidate apical membrane antigen 1     

Pizarro JC  Vulliez-Le Normand B  Chesne-Seck ML  Collins CR  Withers-Martinez C  Hackett F  Blackman MJ  Faber BW  Remarque EJ  Kocken CH  Thomas AW  Bentley GA 《Science (New York, N.Y.)》2005,308(5720):408-411

Apical membrane antigen 1 from Plasmodium is a leading malaria vaccine candidate. The protein is essential for host-cell invasion, but its molecular function is unknown. The crystal structure of the three domains comprising the ectoplasmic region of the antigen from P. vivax, solved at 1.8 angstrom resolution, shows that domains I and II belong to the PAN motif, which defines a superfamily of protein folds implicated in receptor binding. We also mapped the epitope of an invasion-inhibitory monoclonal antibody specific for the P. falciparum ortholog and modeled this to the structure. The location of the epitope and current knowledge on structure-function correlations for PAN domains together suggest a receptor-binding role during invasion in which domain II plays a critical part. These results are likely to aid vaccine and drug design.  相似文献   

RNA- and DNA-based profiling of soil fungal communities in a native Australian eucalypt forest and adjacent Pinus elliotti plantation     

Brigitte A. Bastias  Zhihong Xu 《Soil biology & biochemistry》2007,39(12):3108-3114

Total and active soil fungal communities in a native eucalypt forest and first rotation Pinus elliotti plantation were investigated by direct extraction of DNA and RNA from soil. Terminal restriction fragment length polymorphism (T-RFLP) analysis of internal transcribed spacer (ITS) and 18S rRNA profiles indicated that total and active fungal communities differed significantly in both forest types. This was supported by DGGE profile analysis on an individual plot basis for both forest types and when groups in the canonical analysis were redefined to allow comparison between forest types. Analyses of both ITS and 18S T-RFLP profiles indicated that conversion from native eucalypt forest to P. elliottii plantation may significantly alter total and active soil fungal communities. ITS DGGE (DNA) and 18S (RNA) profiles also suggested differences in fungal communities in the two forest types. No significant separation of the fungal communities in the two forest types was observed, however, when ITS DGGE (RNA) profiles were compared. Overall, the data suggest that conversion from native eucalypt forest to P. elliottii plantation at the Beerburrum State Forest in subtropical Australia has significantly altered soil fungal communities.  相似文献