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Hybrid Formation (hybrid + formation)

Distribution by Scientific Domains

Life Sciences	60%

Selected Abstracts

Emulsifying properties of gelatin conjugated to pectin under alkaline conditions

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2005
Nickolaos G Diftis
Abstract Gelatin,pectin mixed solution incubated under mild alkaline conditions for a period of 4 h exhibited an improvement of emulsion stability in terms of both droplet coalescence and serum separation. Application of SDS,PAGE provided evidence for gelatin,pectin hybrid formation possibly due to amide bonds between the lysine group residues of protein and the esterified carboxyl groups of the polysaccharide. The superior stabilizing properties of the heat-treated protein,polysaccharide conjugate is attributed to the enhancement of the repulsive steric forces operating between emulsion oil droplets, as a result of conjugate adsorption through their protein moiety. Copyright © 2004 Society of Chemical Industry [source]

Reciprocal hybrid formation of Spartina in San Francisco Bay

MOLECULAR ECOLOGY, Issue 6 2000
C. K. Anttila
Abstract Diversity in the tRNALEU1 intron of the chloroplast genome of Spartina was used to study hybridization of native California cordgrass, Spartina foliosa, with S. alterniflora, introduced to San Francisco Bay , 25 years ago. We sequenced 544 bases of the tRNALEU1 intron and found three polymorphic sites, a pyrimidine transition at site 126 and transversions at sites 382 and 430. Spartina from outside of San Francisco Bay, where hybridization between these species is impossible, gave cpDNA genotypes of the parental species. S. foliosa had a single chloroplast haplotype, CCT, and this was unique to California cordgrass. S. alterniflora from the native range along the Atlantic coast of North America had three chloroplast haplotypes, CAT, TAA, and TAT. Hybrids were discriminated by random amplified polymorphic DNA (RAPD) phenotypes developed in a previous study. We found one hybrid that contained a cpDNA haplotype unknown in either parental species (TCT). The most significant finding was that hybridization proceeds in both directions, assuming maternal inheritance of cpDNA; 26 of the 36 hybrid Spartina plants from San Francisco Bay contained the S. foliosa haplotype, nine contained haplotypes of the invading S. alterniflora, and one had the cpDNA of unknown origin. Furthermore, cpDNA of both parental species was distributed throughout the broad range of RAPD phenotypes, suggesting ongoing contributions to the hybrid swarm from both. The preponderance of S. foliosa cpDNA has entered the hybrid swarm indirectly, we propose, from F1s that backcross to S. foliosa. Flowering of the native precedes by several weeks that of the invading species, with little overlap between the two. Thus, F1 hybrids would be rare and sired by the last S. foliosa pollen upon the first S. alterniflora stigmas. The native species produces little pollen and this has low viability. An intermediate flowering time of hybrids as well as pollen that is more vigourous and abundant than that of the native species would predispose F1s to high fitness in a vast sea of native ovules. Thus, spread of hybrids to other S. foliosa marshes could be an even greater threat to the native species than introductions of alien S. alterniflora. [source]

Transferability and genome specificity of a new set of microsatellite primers among Brassica species of the U triangle

MOLECULAR ECOLOGY RESOURCES, Issue 1 2002
Andrew J. Lowe
Abstract We present a new set of 12 highly polymorphic simple sequence repeat primer sequences for use with Brassica species. These new primers, and four from A.K.S. SzewcMcFadden and colleagues, were tested in four Brassica species (B. rapa, B. napus, B. oleracea and B. nigra). Most primers successfully amplified products within all species and were polymorphic. Due to the risk of gene flow from GM oilseed rape to its wild relatives, hybrid formation in the Brassicaceae is of great interest. We identify six primer pairs as specific to the A, B or C genomes that could be used to identify such hybrids. [source]

Breeding behavior and its possible consequences for gene flow in Taraxacum sect.

PLANT SPECIES BIOLOGY, Issue 2 2010
Erythrosperma (H. Lindb.) Dahlst.
Abstract Studies of pollen, seed set and experimental hybridizations were carried out to clarify breeding behavior and gene flow pathways in Taraxacum sect. Erythrosperma. Seeds from hybridization (106 samples), open pollinated (34) and bagged (43) capitula were analyzed for breeding system using a flow,cytometric seed screen. In the section Erythrosperma, diploids are obligate sexuals, mostly allogamous; however, autogamy also occurs (in 28% of unpollinated capitula). Triploids are apomicts with residual sexuality (in 13% of capitula pollinated by pollen of diploids). Pollen of diploids in Taraxacum is usually approximately the same size (regular pollen). In our study, in the section Erythrosperma, many diploids (24%) produced pollen grains of different sizes (irregular pollen) and one plant produced no pollen. The pollen of triploids is either irregular (33%) or the triploids produce no pollen (67%). Consequently, the method of ploidy level assessment on the basis of pollen characteristics is not suitable for Taraxacum sect. Erythrosperma. Low potential for polyploid hybrid formation between diploid maternal plants and polyploid pollen donors, considerable tendency to autogamy and no evidence of the formation of diploid progeny by polyploid maternal plants (facultative apomixis) indicates low intensity of gene flow within Taraxacum sect. Erythrosperma. This, together with a lower population density and spatial isolation of ploidy levels, is expected to result in a lower rate of formation of new apomictic lineages. Thus, Taraxacum sect. Erythrosperma appears evolutionarily more stable and taxonomically less complicated than sect. Ruderalia. The present study supports the agamospecies concept of Taraxacum sect. Erythrosperma. [source]

Thermodynamic characterization of hybrid polymer blend systems

POLYMER ENGINEERING & SCIENCE, Issue 6 2009
Amos Ophir
A thermodynamic model was used to predict the morphology of hybrid multicomponent polymer blend systems. Two systems were studied, both including two noncompatible polymers, a third compatibilizer polymer and layered, organo-treated clays. The polar and nonpolar contributions of the surface energies of the components of the systems were calculated using measurements of the contact angles. The morphology of the multicomponent systems and the relative position of the organo-clays within them, were predicted by calculating the interaction energies between the different components of the system and evaluating these values according to the Vaia and Giannelis thermodynamic model for polymer melt intercalation in organically modified layered silicates. The experimental results show good correlation with the prediction that the organo-clays will have higher affinity to the compatibilizer polymer component situated at the interface between the two noncompatible blend components. In addition, the presence of the organo-clays in this interface was found to have a significant additional compatibilizing effect between the two polymer phases. The results presented in this work support the idea that hybrid formation via polymer melt intercalation depends mostly on energetic factors that can be determined from surface energies of polymers and organo-modified layered silicates, also in the case of multiphase polymer system. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]