Effect of Soy Protein Subunit Composition on the Rheological Properties of Soymilk during Acidification

The effect of soy protein subunit composition on the acid-induced aggregation of soymilk was investigated by preparing soymilk from different soybean lines lacking specific glycinin and β-conglycinin subunits. Acid gelation was induced by glucono-δ-lactone (GDL) and analysis was done using diffusing wave spectroscopy and rheology. Aggregation occurred near pH 5.8 and the increase in radius corresponded to an increase in the elastic modulus measured by small deformation rheology. Diffusing wave spectroscopy was also employed to follow acid gelation, and data indicated that particle interactions start to occur at a higher pH than the pH of onset of gelation (corresponding to the start of the rapid increase in elastic modulus). The protein subunit composition significantly affected the development of structure during acidification. The onset of aggregation occurred at a higher pH for soymilk samples containing group IIb (the acidic subunit A₃) of glycinin, than for samples prepared from Harovinton (a commercial variety containing all subunits) or from genotypes null in glycinin. The gels made from lines containing group I (A₁, A₂) and group IIb (A₃) of glycinin resulted in stiffer acid gels compared to the lines containing only β-conglycinin. These results confirmed that the ratio of glycinin/β-conglycinin has a significant effect on gel structure, with an increase in glycinin causing an increase in gel stiffness. The type of glycinin subunits also affected the aggregation behavior of soymilk.     

Costs and benefits of female-biased natal philopatry in the common goldeneye

Sex-biased natal dispersal in long-lived species may resultin interactions between parents and mature young of the philopatricsex. To investigate the evolutionary basis of natal philopatryin a noncooperative species, the common goldeneye Bucephalaclangula, we studied possible costs and benefits of simultaneousbreeding of females and philopatric daughters. We did not find any fitness consequences of a daughter's breeding on their mother'sbreeding in terms of nest-site selection, body weight, clutchsize, hatching date, or hatching success. Our results, therefore,did not support the assumption of the local resource competitionhypothesis, that the natally philopatric sex should be morecostly to a breeding parent. As possible benefits for daughters returning to their natal area, we tested inheritance of nestsites from mothers and explored whether daughters utilize thepresence of their mother by parasitically sneaking into hermother's nest. Daughters' nest-site selection was not associatedwith the presence of their mothers. A comparison between daughtersand control females revealed that daughters chose their nestsite closer to their natal nest than expected by nest-siteavailability alone. Daughters could not expect to inherit anest site from their mother, and we did not find other indicationsof cooperation between relatives either. The mother's clutchsize did not increase in the year breeding with the daughter, indicating daughters do not parasitize their mother's nest.We suggest that benefits such as decreased nest predation riskassociated with nesting close to the natal nest site may beimportant in the natal philopatric behavior of the species.     

Development and characterization of wheat-Psathyrostachys huashanica partial amphiploids for resistance to stripe rust

Two partial amphiploid lines, B113 (32 plants) and B21 (13 plants), derived from a wheat-Psathyrostachys huashanica intergeneric cross were characterized by Giemsa C-banding and SDS-PAGE and evaluated for stripe rust resistance. All 15 partial amphiploid plants were aneuploids with either 50 (8 plants), 51 (6 plants) or 54 (1 plant) chromosomes. Some showed regular meiosis and all the P. huashanica chromosomes were included, although not in a single plant. Of 45 plants 34 showed specific bands on SDS-PAGE representing high molecular weight glutenin subunit (HMW-GS) and 41 had bands representing P. huashanica low molecular weight glutenin subunit (LMW-GS), including two new subunits. All 45 plants were highly resistant (10) or immune (35) to stripe rust mixed races CYR-30, CYR-31, Shuiyuan 7 and Shuiyuan 14. These amphiploid plants could be useful germplasm for enhancing stripe rust resistance and might improve wheat grain quality.     

Factors affecting species number and density of dabbling duck guilds in North Europe

We addressed how species number and pair density in guilds of co-existing species is related to habitat structure, and to the abundance and diversity of food resources using the assemblage of seven species of dabbling ducks (genus Anas ) breeding in 60 lakes distributed over six regions in temperate north Europe
Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey We found no effect of lake size or prey size diversity on species richness Pair density was correlated with the percentage of shoreline with horsetails ( Equisetum ), by habitat structural diversity and by the abundance of emergent invertebrate prey Neither prey size diversity nor abundance of aquatic prey correlated with pair density Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability     

Molecular analysis of glycinin genes in soybean mutants for development of gene-specific markers

Soybean mutant lines that differ in 11S glycinin and 7S β-conglycinin seed storage protein subunit compositions were developed. These proteins have significant influence on tofu quality. The molecular mechanisms underlying the mutant lines are unknown. In this study, gene-specific markers for five of the glycinin genes (Gy1 to Gy5) were developed using three 11S null lines, two A₄ null Japanese cultivars, Enrei and Raiden, and a control cultivar, Harovinton. Whereas gene-specific primers produced the appropriate products in the control cultivar for the Gy1, Gy2, Gy3 and Gy5 genes, they did not amplify in mutants missing the A_1aB₂, A₂B_1a, A_1b B_1b, and A₃B₄ subunits. However, ecotype targeting induced local lesions in genomes (EcoTILLING) and sequencing analysis revealed that the absence of the A₄ peptide in the mutants is due to the same point mutation as that in Enrei and Raiden. Selection efficiency of the gene-specific primer pairs was tested using a number of breeding lines segregating for the different subunits. Primer pairs specific to each of the Gy1, Gy2, Gy3, and Gy5 genes can be used to detect the presence or absence of amplification in normal or mutant lines. The Gy4 null allele can be selected for by temperature-switch PCR (TS-PCR) for identification of the A₄ (G4) null genotypes. In comparison to protein analysis by SDS-PAGE, gene-specific markers are easier, faster and more accurate for analysis, they do not have to use seed, and can be analyzed at any plant growth stage for marker-assisted selection.     

Mapping genes conferring resistance to Phytophthora root rot of soybean, Rps1a and Rps7.

A linkage map was constructed for two Phytophthora sojae Kauf. +Gerd. root rot resistance genes, Rps1a and Rps7, in soybean (Glycine max (L.) Merr.) using microsatellite or simple sequence repeat (SSR) markers. An F2 population consisting of 81 individuals derived from a cross between OX281, which carries Rps7, and Mukden, which carries Rps1a, was used as the mapping population. A linkage map consisting of 10 SSR markers was first constructed using the computer software MapMaker/EXP 3.0. Rps1a and Rps7 were then placed at two different loci in the same linkage group with LOD scores of 2.88 and 9.16, respectively. Rps1a and Rps7 were linked at a distance of 13.8 cM. Rps1a was flanked by Satt159 (0.7 cM) and Satt009 (3.2 cM). Rps7 was flanked by Satt009 (10.6 cM) and Satt125 (29.1 cM).     

Pyramided QTL underlying tolerance to Phytophthora root rot in mega-environments from soybean cultivars ‘Conrad’ and ‘Hefeng 25’

Phytophthora root rot (PRR) of soybean (Glycine max (L.) Merr.) is the second most important cause of yield loss by disease in North America, surpassed only by soybean cyst nematode (Wrather et al. in Can J Plant Pathol 23:115–121, 2001). Tolerance can provide economically useful disease control, conditioning partial resistance of soybean to PRR. The aims of this study were to identify new quantitative trait loci (QTL) underlying tolerance to PRR, and to evaluate the effects of pyramided or stacked loci on the level of tolerance. A North American cultivar ‘Conrad’ (tolerant to PRR) was crossed with a northeastern China cultivar ‘Hefeng 25’ (tolerant to PRR). Through single-seed descent, 140 F_2:5 and F_2:6 recombinant inbred lines were advanced. A total of 164 simple sequence repeat (SSR) markers were used to construct a genetic linkage map. The percentage of seedling death was measured over 2 years (2007 and 2008) in the field at four naturally infested locations in Canada and China following additional soil infestation and in the greenhouse following inoculation with Phytophthora sojae isolate. A total of eight QTL underlying tolerance to PRR were identified, located in five linkage groups (F, D1b+w, A2, B1, and C2). The phenotypic variation contributed by the loci ranged from 4.24 to 27.98%. QPRR-1 (anchored in the interval of SSR markers Satt325 and Satt343 of LG F), QPRR-2 (anchored in the interval of Satt005 and Satt600 of LG D1b+w), and QPRR-3 (anchored in the interval of Satt579 and Sat_089 of LG D1b+w) derived their beneficial allele from ‘Conrad’. They were located at chromosomal locations known to underlie PRR tolerance in diverse germplasm. Five QTL that derived beneficial alleles from ‘Hefeng 25’ were identified. The QTL (QPRR-1 to QPRR-7) that were detected across at least three environments were selected for loci stacking and to analyze the relationship between number of tolerance loci and disease loss percentage. The accumulation of tolerance loci was positively correlated with decreases in disease loss percentage. The pyramid of loci underlying tolerance to PRR provided germplasm useful for crop improvement by marker-assisted selection and may provide durable cultivar tolerance against the PRR disease.     

Development and characterization of simple sequence repeat (SSR) markers and their use in determining relationships among Lycopersicon esculentum cultivars

The simple sequence repeat (SSR) or microsatellite marker is currently the preferred molecular marker due to its highly desirable properties. The aim of this study was to develop and characterize more SSR markers because the number of SSR markers currently available in tomato is very limited. Five hundred DNA sequences of tomato were searched for SSRs and analyzed for the design of PCR primers. Of the 158 pairs of SSR primers screened against a set of 19 diverse tomato cultivars, 129 pairs produced the expected DNA fragments in their PCR products, and 65 of them were polymorphic with the polymorphism information content (PIC) ranging from 0.09 to 0.67. Among the polymorphic loci, 2-6 SSR alleles were detected for each locus with an average of 2.7 alleles per locus; 49.2% of these loci had two alleles and 33.8% had three alleles. The vast majority (93.8%) of the microsatellite loci contained di- or tri-nucleotide repeats and only 6.2% had tetra- and penta-nucleotide repeats. It was also found that TA/AT was the most frequent type of repeat, and the polymorphism information content (PIC) was positively correlated with the number of repeats. The set of 19 tomato cultivars were clustered based on the banding patterns generated by the 65 polymorphic SSR loci. Since the markers developed in this study are primarily from expressed sequences, they can be used not only for molecular mapping, cultivar identification and marker-assisted selection, but for identifying gene-trait relations in tomato.     

Conspecific nest parasitism is associated with inequality in nest predation risk in the common goldeneye (Bucephala clangula)

Previous studies of the role of nest predation in conspecificnest parasitism have not taken into account the possibilitythat predation risk may not be randomly distributed among nestsites and that breeding individuals may use different cues toassess the risk and adjust their reproductive tactic betweenyears accordingly. Especially in cavity-nesting species, therole of nest predation in conspecific nest parasitism has beendownplayed, while the role of nest site limitation has beenhighlighted. Using both observational and experimental data,I show that in the common goldeneye (Bucephala clangula), acavity-nesting species in which conspecific nest parasitism iscommon, predation risk varies considerably between nest sitesand does not follow a random expectation. The inequality inpredation risk between nest sites also showed up in the occurrenceof parasitized nests in an experimental setup. Nests parasitizedin year t were more frequent in those nest sites that were notdepredated during the previous nesting attempt in year t - nthan in nest sites that were depredated and in control nestsites that had not been used for nesting before. A nest siteaddition experiment revealed that conspecific nest parasitismwas not associated with nest site limitation. My findings givesupport for the hypothesis that nest predation is an importantecological factor explaining conspecific nest parasitism ingoldeneyes.