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271.
272.
Wouter Coppieters Juliette Riquet Juan-José Arranz Paulette Berzi Nadine Cambisano Bernard Grisart Latifa Karim Fabienne Marcq Laurence Moreau Carine Nezer Patricia Simon Pascal Vanmanshoven Danny Wagenaar Michel Georges 《Mammalian genome》1998,9(7):540-544
A whole genome scan was undertaken in a granddaughter design comprising 1158 progeny-tested bulls in order to map QTL influencing
milk yield and composition. In this paper we report the identification of a locus on the centromeric end of bovine Chromosome
(Chr) 14, with major effect on fat and protein percentage as well as milk yield. The genuine nature of this QTL was verified
using the grand2-daughter design, that is, by tracing the segregating QTL alleles from heterozygous grandsires to their maternal grandsons
and confirming the predicted QTL allele substitution effect.
Received: 30 December 1997 / Accepted: 21 February 1998 相似文献
273.
Brigitte Huss Bruno Tinland François Paulus Bernard Walter Léon Otten 《Plant molecular biology》1990,14(2):173-186
The ubiquitous grapevine-associated octopine/cucumopine Ti plasmids of biotype III Agrobacterium tumefaciens strains carry two T regions, TA and TB, with a complex oncogene arrangement. Within the octopine/cucumopine group, two main strain types were identified: large TA strains with a TA region resembling the TL region of the biotype I octopine strain Ach5 and small TA strains with a similar T region organization as the large TA strains but with a large internal TA deletion. Structural and functional studies of the representative large TA strain Tm4 revealed six oncogenes. Each oncogene was inserted in a disarmed vector and tested for biological activity using the corresponding oncogenes of Ach5 as standards. Five Tm4 oncogenes, TA-iaaM, T-ipt, T-6b, TB-iaaH and TB-iaaM, were shown to be active, the IS-interrupted TA-iaaH gene was inactive. To study the role of each gene in the pTiTm4 context, several single and multiple pTiTm4 mutations were constructed. It was shown that whereas TA-iaaM and TB-iaaH are essential for tumour formation on grapevine, T-ipt, T-6b and TB-iaaM are not. The avirulence of the TA-iaaM
-
mutant was shown to be due to an inhibitory effect of the T-ipt gene, since a TA-iaaM
-
/T-ipt
-
double mutant was fully virulent. We conclude that the TA-iaaM gene of large TA strains is specifically required to counteract the tumour growth inhibiting activity of the T-ipt gene. Both TA-iaaM and T-ipt are absent from the small TA strains. A model on the roles and interactions of the different oncogenes in large TA and small TA strains is presented. 相似文献
274.
275.
Most studies of behaviour examine traits whose proximate causes include sensory input and neural decision-making, but conflict and collaboration in biological systems began long before brains or sensory systems evolved. Many behaviours result from non-neural mechanisms such as direct physical contact between recognition proteins or modifications of development that coincide with altered behaviour. These simple molecular mechanisms form the basis of important biological functions and can enact organismal interactions that are as subtle, strategic and interesting as any. The genetic changes that underlie divergent molecular behaviours are often targets of selection, indicating that their functional variation has important fitness consequences. These behaviours evolve by discrete units of quantifiable phenotypic effect (amino acid and regulatory mutations, often by successive mutations of the same gene), so the role of selection in shaping evolutionary change can be evaluated on the scale at which heritable phenotypic variation originates. We describe experimental strategies for finding genes that underlie biochemical and developmental alterations of behaviour, survey the existing literature highlighting cases where the simplicity of molecular behaviours has allowed insight to the evolutionary process and discuss the utility of a genetic knowledge of the sources and spectrum of phenotypic variation for a deeper understanding of how genetic and phenotypic architectures evolve. 相似文献
276.
Melissa Hughes Stephen Nowicki Bernard Lohr 《Ethology : formerly Zeitschrift fur Tierpsychologie》1998,104(3):232-249
The role of learning in the development of bird vocalizations other than territorial song is not well studied. The well-known role of direct imitation in the development of territorial song potentially masks the effects of other processes in the development of vocal behaviour. The ‘chick-a-dee’ call of black-capped chickadees is a good system in which to investigate more subtle developmental processes because this call is composed of a small number of distinctive note types. These note types may be classified objectively based on a simple set of acoustic variables, allowing for a quantitative assessment of vocal learning. We raised four groups of black-capped chickadees under different degrees of social and acoustic isolation. We then used a multivariate analysis of the acoustic structure of the introductory call notes (‘A-’ ‘B-’ and ‘C-notes’) to determine how similar the notes produced by these hand-reared birds were to the notes of wild birds. Hand-reared chickadees with greater exposure to normal phonology produced notes of all three note types that were more similar to those of wild birds. Regardless of experience, however, all birds produced A-notes that fell within the normal range of those produced by wild birds. By contrast, the development of normal B- and C-notes appears to be more dependent upon experience. These data suggest that learning may play a different role in the development of different phonological units within one vocalization. Our results also illustrate the importance of considering processes other than simple imitation in the development of avian vocalizations. 相似文献
277.
Eric Le Cam Dominique Coulaud Etienne Delain Patrice Petitjean Bernard P. Roques Dominique Grard Elena Stoylova Constance Vuilleumier Stoyl P. Stoylov Yves Mly 《Biopolymers》1998,45(3):217-229
NCp7, the nucleocapsid protein of the human immunodeficiency virus type 1, induces an ordered aggregation of RNAs, a mechanism that is thought to be involved in the NCp7-induced promotion of nucleic acid annealing. To further investigate this aggregation, the morphology and the properties of the NCp7-induced aggregates of the model RNA homoribopolymer, polyA, were investigated by electron microscopy in various conditions. In almost all the tested conditions, the aggregates were spherical and consisted of a central dense core surrounded by a less dense halo made of NCp7-covered polyA molecules. The formation of these aggregates with a narrow distribution of sizes constitutes a distinctive feature of NCp7 over other single-stranded nucleic acid binding proteins. In most conditions, at the shortest times that can be reached experimentally, all the polyA molecules were already incorporated in small aggregates, suggesting that the nucleation step and the first aggregation events took place rapidly. The aggregates then orderly grew with time by fusion of the smaller aggregates to give larger ones. The aggregate halo was important in the fusion process by initiating the bridging between the colliding aggregates. In the presence of an excess of protein, the aggregates grew rapidly but were loosely packed and dissociated easily, suggesting adverse protein-protein interactions in the aggregates obtained in these conditions. In the presence of an excess of nucleotides, the presence of both amorphous nonspherical and slowly growing spherical aggregates suggested some changes in the mechanism of aggregate growth due to an incomplete covering of polyA molecules by NCp7. Finally, we showed that in the absence of added salt, the aggregate fusions were unfavored but not the initial events giving the first aggregates, the reverse being true in the presence of high salt concentrations (≥300 mM). © 1998 John Wiley & Sons, Inc. Biopoly 45: 217–229, 1998 相似文献
278.
Beatris Mastelic Nathalie Garçon Giuseppe Del Giudice Hana Golding Marion Gruber Pieter Neels Bernard Fritzell 《Biologicals》2013,41(6):458-468
Vaccination represents one of the greatest public health triumphs; in part due to the effect of adjuvants that have been included in vaccine preparations to boost the immune responses through different mechanisms. Although a variety of novel adjuvants have been under development, only a limited number have been approved by regulatory authorities for human vaccines. This report reflects the conclusions of a group of scientists from academia, regulatory agencies and industry who attended a conference on the current state of the art in the adjuvant field. Held at the U.S. Pharmacopeial Convention (USP) in Rockville, Maryland, USA, from 18 to 19 April 2013 and organized by the International Association for Biologicals (IABS), the conference focused particularly on the future development of effective adjuvants and adjuvanted vaccines and on overcoming major hurdles, such as safety and immunogenicity assessment, as well as regulatory scrutiny. More information on the conference output can be found on the IABS website, http://www.iabs.org/. 相似文献
279.