Applicability of best linear unbiased prediction (BLUP) for the selection of ortets in Eucalyptus hybrid populations

The prediction of the performance of hybrid plants as production material is complicated by the genetic structure of the hybrid population. Fundamental quantitative genetic concepts are defined with respect to disomic, randomly fertilized populations which are in linkage and Hardy-Weinberg equilibrium. Hybrid populations of crosses are, however, in disequilibrium and do not meet these assumptions of quantitative genetic theory. The theory of inheritance in hybrid populations has not been fully developed and the complex models that have been developed have not reached a stage where they have been implemented to adapt selection practices for hybrid populations. Therefore in practice hybrids are often selected using selection methodology that has been developed for pure species despite large differences in the underlying genetic properties of the populations. It is not known to which extent such selections are able to predict the performance of progeny or clones in hybrid populations. This study was based on historical data and investigated the efficiency of BLUP in hybrid populations. As a case study the selection of ortets in three hybrid Eucalyptus populations was investigated. Ortet selection in E. grandis × E. saligna, E. grandis × E. urophyllaand E. grandis × E. camaldulensis populations was compared with selection in E. grandis populations. Clonal performance was predicted from a series of hybrid family trials whereas realised clonal performance was assessed in clonal trials. The predicted and realised clonal performances were correlated to assess the efficiency of the predictions. A series of constructed indices was created that placed a range of weights on family versus individual tree performances to obtain an indication of the range of correlations that could be expected from the data. Different BLUP methods were compared including selection for breeding and various forward selections for clonal forestry (“clonal forward selection”). The clonal forward selections were based on different estimates of the proportion of total genetic variance that is ascribed to non-additive genetic variance. The results of the study indicated that there were no observable differences in the efficiency of the BLUP predictions in the studied hybrids in comparison to prediction in E. grandis There was, however, a decrease in the correlations between predicted and realised clonal performances with increasing genetic distance between the parents. Furthermore, the genetic values were better predictors of clonal performance than breeding values and genetic values which were based on higher assumptions of non-additive genetic variances (37% of total genetic variance) were more efficient than those based on assumptions of lower proportions (20%). This study indicates that BLUP methods may be efficient in predicting the clonal performance in the three hybrid populations that were investigated. CopyrightDissertation (MSc)--University of Pretoria, 2009.Geneticsunrestricte

A Structural Model of the Staphylococcus aureus ClfA–Fibrinogen Interaction Opens New Avenues for the Design of Anti-Staphylococcal Therapeutics

The fibrinogen (Fg) binding MSCRAMM Clumping factor A (ClfA) from Staphylococcus aureus interacts with the C-terminal region of the fibrinogen (Fg) γ-chain. ClfA is the major virulence factor responsible for the observed clumping of S. aureus in blood plasma and has been implicated as a virulence factor in a mouse model of septic arthritis and in rabbit and rat models of infective endocarditis. We report here a high-resolution crystal structure of the ClfA ligand binding segment in complex with a synthetic peptide mimicking the binding site in Fg. The residues in Fg required for binding to ClfA are identified from this structure and from complementing biochemical studies. Furthermore, the platelet integrin αIIbβ3 and ClfA bind to the same segment in the Fg γ-chain but the two cellular binding proteins recognize different residues in the common targeted Fg segment. Based on these differences, we have identified peptides that selectively antagonize the ClfA-Fg interaction. The ClfA-Fg binding mechanism is a variant of the “Dock, Lock and Latch” mechanism previously described for the Staphylococcus epidermidis SdrG–Fg interaction. The structural insights gained from analyzing the ClfANFg peptide complex and identifications of peptides that selectively recognize ClfA but not αIIbβ3 may allow the design of novel anti-staphylococcal agents. Our results also suggest that different MSCRAMMs with similar structural organization may have originated from a common ancestor but have evolved to accommodate specific ligand structures

Optimization of fir-tree-type turbine blade roots using photoelasticity

Thesis (MEng.) -- University of Stellenbosch, 1992.ENGLISH ABSTRACT: The large variety of turbo-machinery blade root geometries in use in industry prompted the question if a optimum geometry could be found. An optimum blade root was defined as a root with a practical geometry which, when loaded, returns the minimum fillet stress concentration factor. A literature survey on the subject provided guidelines but very little real data to work from. An initial optimization was carried out using a formula developed by Heywood to determine loaded projection fillet stresses. The method was found to produce unsatisfactory results, prompting a photoelastic investigation. This experimental optimization was conducted in two stages. A single tang defined load stage and a single tang in-rotor stage which modeled the practical situation. The defined load stage was undertaken in three phases. The first phase was a preliminary investigation, the second phase was a parameter optimization and the third phase was a geometric optimization based on a material utilization optimization. This material optimization approach produced good results. From these experiments a practical optimum geometry was defined. A mathematical model which predicts the fillet stress concentration factor for a given root geometry is presented. The effect of expanding the single tang optimum to a three tang root was examined.AFRIKAANSE OPSOMMING: Die groot verskeidenheid lemwortelgeometrieë wat in turbomasjiene gebruik word het die vraag na 'n optimum geometrie laat ontstaan. Vir hierdie ondersoek is 'n optimum geometrie gedefineer as 'n praktiese geometrie wat, as dit belas word, die mimimum vloeistukspanningskonsentrasiefaktor laat ontstaan. 'n Literatuur studie het riglyne aan die navorsing gegee maar het wynig spesifieke en bruikbare data opgelewer. Die eerste optimering is met die Heywood formule, wat vloeistukspannings in belaste projeksies bepaal, aangepak. Die metode het nie bevredigende resultate opgelewer nie. 'n Fotoelastiese ondersoek het die basis vir verdere optimeering gevorm. Hierdie eksperimentele optimering is in twee stappe onderneem. 'n Enkelhaak gedefineerde lasgedeelte en 'n enkelhaak in-rotor gedeelte het die praktiese situasie gemodeleer. Die gedefineerde lasgedeelte is in drie fases opgedeel. Die eerste fase was n voorlopige ondersoek. Die tweede fase was 'n parameter optimering. 'n Geometrie optimering gebasseer op 'n materiaal benuttings minimering het die derde fase uitgemaak. Die materiaal optimerings benadering het goeie resultate opgelewer. Vanuit hierdie eksperimente is 'n optimum praktiese geometrie bepaal. 'n Wiskundige model is ontwikkel, wat die vloeistukspanningskonsentrasiefaktor vir 'n gegewe wortelgeometrie voorspel. Die resultaat van 'n geometriese uitbreiding van die enkelhaaklemwortel na 'n driehaaklemwortel op die spanningsverdeling is ondersoek

Easter Sunday service

This item is a Moravian sermon written by Seigfried Hettasch for Easter Sunday Service, 1941.Record title

Moravian sermon for Festival Day

This item is a sermon written by Seigfried Hettasch for service on November 16, 1963 at Makkovik. It concerns the Moravian Church's acknowledgement of November 13, 1741 as the day it formally accepted Jesus Christ as the Chief Elder of the Church.Title based on the contents of the record

Preparation for Holy Communion

This item is a sermon given for the preparation of the Holy Communion during a November 13, 1979 Moravian Church service.Title based on the contents of the record

Leucadendrons are short-day plants: a preliminary report.

Please help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Moravian sermon, November 11

This item is a sermon written by Moravian missionary, Seigfried Hettasch, for Armistice Day, 1975.Title based on the contents of the record

Studies of the vegetative development of Protea cv. Sylvia and Cardinal

Thesis (M.Sc Agric.) -- University of Stellenbosch, 1999.ENGLISH SUMMARY: The high establishment cost of growing proteas under intensive cultivation has necessitated young plant management to attain an economically viable crop as soon as possible after planting. Rooted cuttings of Protea cv. Sylvia (P. eximia x P. susannae) were planted and shoots were pinched and topped at various growth stages to increase the vegetative complexity of the plants during the first growing season. During the second growing season, one-year-old plants of Protea cv. Sylvia were pruned in early spring, and the resultant regrowth thinned to between three and six shoots per bearer or left unthinned. Plants which were not pinched or topped during the first growing season, grew a single stem; pinching after the spring flush resulted in an average of 4.34 shoots forming while not pinching the spring flush, but topping after the summer flush resulted in an average of 6.82 shoots forming by late summer. Pinching both the spring and summer flushes resulted in an average of 8.84 shoots per plant. One-year-old Sylvia plants, pruned in early spring, produced an average of 5.5 shoots per bearer. Where all the shoots were left, some became dominant and the remainder became weak, spindly, non-flowering shoots. Thinning the sprouts on the bearers in the spring to 3, 4 or 5 shoots per bearer, did not result in longer shoots or a higher percentage of flowering shoots than leaving 6 shoots per bearer. Whole shoots of Protea cv. Sylvia (P. eximia x P. susannae) and Pro tea cv. Cardinal (P. eximia x P. susannae) plants were sampled at the conclusion of each successive growth flush over a period of one growing season. The dry mass of leaves and stems of each flush was measured separately and a sample analysed for total sugars and starch concentrations. Total dry mass of both stems and leaves of 'Sylvia' and 'Cardinal' remained similar during growth of the spring and first summer flushes and then increased significantly during the formation of the second summer flush and the autumn flush. The concentration of carbohydrates (total sugars and starch combined) in the leaves and stems of the whole shoot, increased significantly from one flush to the next, up to and including the second summer flush. The concentration of carbohydrates in the leaves of the whole shoot was significantly reduced after the winter, while in the stems the concentration remained similar. Total sugars and starch concentrations in the leaves of both 'Sylvia' and 'Cardinal' were significantly higher than in the stems on all flushes. The dry mass, concentration of starch and concentration of total sugars of different plant parts of Protea cv. Sylvia were measured at two sampling dates. Plants were grown for two years in 101 bags in a nursery. During July and September, whole plants were sampled, dissected into leaves, shoots, stem (trunk) and roots and laboratory analysed for dry mass, starch and sugars. The two sampling dates corresponded to the end of active vegetative shoot growth in early winter and its resumption in spring. In all plant parts monitored, dry mass did not increase significantly from one sampling date to the next. Tissue content of both total sugars and starch in the leaves represented half the amount of the total plant at both sampling dates. Significant increases in the concentration and tissue content of total sugars were noted in the leaves, shoots and roots between the first and second sampling dates. In the case of starch a significant increase in concentration and tissue content was noted in the leaves and a decrease in the stem.AFRIKAANSE OPSOMMING: Die hoe vestigings kostes betrokke by die intensiewe verbouing van proteas noodsaak jong plant bestuur om 'n ekonomies betekenisvolle oes te behaal so gou moontlik na plant. Bewortelde steggies van Protea cv. Sylvia (P. eximia x P. susannae) is geplant en die lote se groeipunte is op verskillende groei stadia getop of terug gesny om vegetatiewe kompleksiteit van die plante in die eerste groeiseisoen te verhoog. Gedurende die tweede groeiseisoen is een-jaar-oue plante van Protea cv. Sylvia in die vroee lente gesnoei en die nuwe groei is dan uitgedun na tussen drie en ses lote per draer, of dit is ongedun gelos. Plante wat nie getop of terug gesny was in die eerste groei seisoen nie, het 'n enkele loot geproduseer; lote wat na die lente groeistuwing getop is het 'n gemiddeld van 4.34 lote geproduseer terwyl lote waar die lente groeistuwing nie getop is nie, maar wat weI terug gesny is na die somer groeistuwing het gemiddeld 6.82 lote geproduseer teen laat somer. Waar beide die lente en somer groeistuwings getop is, het die plante gemiddeld 8.84 lote geproduseer. Een-jaar-oue Sylvia plante wat in die vroee lente gesnoei is het gemiddeld 5.5 lote per draer geproduseer. Waar al die lote behou is, het sommig het 'n enkele loot geproduseere lote dominant geraak en ander was swak, nie blommende lote. Uitdun van die knoppe in die vroee lente na 3, 4 of 5 per draer, het nie gelei tot langer lote of 'n hoer persentasie blommende lote as waar 6 lote gelos is nie. Intakte lote van Pro tea cv. Sylvia (P. eximia x P. susannae) en Protea cv. Cardinal (P. eximia x P. susannae) plante is versamel aan die einde van elke opeenvolgende groeistuwing oor 'n periode van een groei seisoen. Die droee massa van die blare en stele van elke groeistuwing is apart gemeet en 'n monster is geanaliseer vir totale suiker en stysel konsentrasie. Totale droee massa van beide stele en blare van 'Sylvia' en 'Cardinal' het eeners gebly gedurende die lente en eerste somer groeistuwings en het dan betekenisvol toegeneem met die ontwikkeling van die tweede somer groeistuwing en die herfs groeistuwing. Die konsentrasie koolhidrate (totale suikers en stysel gekombineer) in die blare en stele van intakte lote het betekenisvol toegeneem van een groeistuwing na die volgende, tot en met die tweede somer groeistuwing. Die konsentrasie van koolhidrate in die blare van die hele lote was betekenisvol minder in die winter, terwyl die konsentrasie in die stele dieselfde gebly het. Totale suikers en stysel in die blare van beide 'Sylvia' en 'Cardinal' was by al die flushes betekenisvol hoer as in die stele. Die droee massa, konsentrasie stysel en konsentrasie totale suiker van die verskillende plant dele van Protea cv. Sylvia is bepaal op twee datums. Plante is twee jaar lank· gekweek in 101 sakke in 'n kwekery. Gedurende Julie en September, is intakte plante versamel, opgedeel in blare, stele, starn en wortels en geanaliseer vir droee massa, stysel en suikers. Die twee datums het ooreengestem met die einde van aktiewe vegetatiewe lootgroei in die vroee winter en die begin van lootgroei in die lente. In al die plant dele wat gemonitor is het droee massa nie betekenisvol toegeneem tussen die twee datums nie. Die inhoud van beide totale suikers en stysel in die blare het die helfde van die totale hoeveelheid in die plant verteenwoordig by albei datums. Betekenisvolle toenames is getoon in die konsentrasie en totale inhoud van totale suikers in die blare, stele en wortels tussen die eerste en die tweede datums. In die geval van stysel is 'n betekenisvolle toename in die konsentrasie en totale inhoud van blare opgemerk, asook 'n afname in die starn.Maste