Thesis (M. Sc.)--University of Hong kong, 1973. / Typewritten.

Thesis (M. Sc.)--University of Hong Kong, 1974. / Typescript.

Pallid sturgeon (Scaphirhynchus albus) is a native North American fish that was listed as a federally endangered species in 1990 due to failure in spawning and recruitment, perhaps as a result of human modifications to their habitat. The upper Missouri River basin pallid sturgeon have been shown to be genetically distinct from other pallid sturgeon. Since there has been no natural recruitment in the upper Missouri River for several decades, perpetuation of this genetically distinct unit is reliant on propagation using remaining wild fish as broodstock. The expense associated with acquiring unique individuals from the remaining wild broodstock is causing wild collection to become a less viable option each year. It has been proposed that rearing progeny of wild broodstock fish in a hatchery setting as captive broodstock may be feasible alternative to wild collections. The genetic risks associated with the creation of a captive broodstock need to be investigated and a captive management plan needs to be developed prior to the implementation of a captive broodstock program. The relatedness values and the effective population size for the wild caught founders were determined by genotyping wild upper Missouri River pallid sturgeon at 16 previously developed microsatellite loci. The founding wild broodstock were shown to encompass an ample amount of genetic variation and a sufficiently large effective population size. The broodstock currently housed as Gavin's Point National Fish Hatchery can be exclusively used for the propagation of pallid sturgeon to be stocked in the upper Missouri River with the caveat that descendents from each wild fish will be spawned in the future and that the reproductive variance of the broodstock be controlled to maximize Ne and thus reduce inbreeding.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The generally low concentrations of P and N in the soil, causes most plants to experience nutrient deficiency during their life cycle. Lupins can rely on both cluster roots and nodules for P acquisition and biological nitrogen fixation (BNF) respectively. The legume Lupinus albus is able to survive under low nutrient conditions, because it has two specialized belowground organs for the acquisition of N and P. In this regard, cluster roots increase P uptake and root nodules acquire atmospheric N2 via biological nitrogen fixation (BNF). Although these organs normally tolerates low P conditions, very little is known about their physiological and metabolic flexibility during variations in P supply. Furthermore, the resource allocation (C, N and P) between cluster roots and nodules has also been largely understudied. The aim of this investigation was therefore to determine the resource allocation, physiological and metabolic flexibility of these organs during variations in P supply. Although variation on P supply had no effect on the total biomass, there were significant differences in specialised below-ground organ allocation to cluster roots and nodule formation. Cluster root formation and the associated C-costs increased during low P supply. In contrast to the cluster root decline at high P supply, there was an increase in nodule growth allocation and corresponding C-costs. Since cluster roots were able to increase P acquisition under low P conditions, this below-ground investment may also have benefited the P nutrition of nodules. These findings provide evidence that when lupins acquire N via BNF in their nodules, there may be a trade-off in resource allocation between cluster roots and nodules. The short-term elevated P supply, caused an increased allocation of C and respiratory costs to nodules, at the expense of cluster roots. This alteration was also reflected in the increase in nodule enzyme activities related to organic acid synthesis, such as Phosphoenol-pyruvate Carboxylase (PEPC), Pyruvate Kinase (PK), Malate Dehydrogenase (NADH-MDH) and Malic Enzyme (ME). In cluster roots, the elevated P conditions, caused a decline in these organic acid synthesizing enzymes. This suggests that during short-term elevated P supply, there is a great degree of physiological and metabolic flexibility in the lupin nutrient acquiring structures. / AFRIKAANSE OPSOMMING: Die algemeen lae konsentrasies van fosfaat en stikstof in die grond , veroorsaak dat die meeste plante voedingstekorte ervaar tydens hul lewensiklus. Lupiene kan staatmaak op beide groep-wortels en wortel-knoppies vir P verkryging en biologiese stikstofbinding onderskeidelik. Die peulplant Lupinus albus is in staat om te oorleef onder lae voedings toestande , as gevolg van die twee gespesialiseerde ondergrondse organe vir die verkryging van stikstof en fosfaat. In hierdie verband verhoog groep-wortels fosfaat opname en wortel-knoppies verkry atmosferiese stikstof via biologiese stikstofbinding. Alhoewel hierdie organe normaalweg lae fosfaat toestande verdra , is baie min bekend oor hul fisiologiese en metaboliese buigsaamheid tydens variasies in fosfaat aanwending. Daar is verder ‘n tekort aan die studie van hulpbron toekenning tussen groep-wortels en wortel-knoppies. Die doel van hierdie ondersoek was dus om die toekenning van hulpbronne , fisiologiese en metaboliese buigsaamheid van hierdie organe tydens variasies in fosfaat aanwending te bepaal. Variesie in fosfaat verskaffing het geen invloed op die totale plant biomassa gehad nie, maar daar was wel ‘n beduidende verskil in gespesialiseerde ondergrondse toekenning tussen groep- wortels en wortel-knoppies. Groep-wortel vorming en die gepaardgaande koolstof koste het toegeneem met lae fosfaat verskaffing. In teenstelling met die groep-wortel daling met hoë fosfaat verskaffing, was daar 'n toename in groei van wortel-knoppies en die ooreenstemmende koolstof koste daarvan. Aangesien groep-wortels in staat was om fosfaat verkryging te verhoog onder lae fosfaat toestande, mag hierdie ondergrondse belegging bygedra het tot die voeding van wortel-knoppies . Hierdie bevindings bewys dat lupiene afhanklik van wortel-knoppies ‘n wisselwerking in toekenning van hulpbronne, tussen groep-wrotels en wortel-knoppies handaaf. Kort termyn verhoogde fosfaat aanwending veroorsaak 'n verhoogde toekenning van koolstof en respiratoriese energie na wortel-knoppiess, ten koste van groep-wortels . Hierdie verandering is ook weerspieël in die toename in wortel-knoppie ensiem aktiwiteit in verband met organiese suur sintese (PEPC PK,MDH,ME) . In groep-wortels, het die verhoogde P toestande verder 'n afname in die organiese suur produserende ensieme veroorsaak. Dit dui aan dat tydens kort termyn verhoogde P aanwending, daar 'n groot mate van fisiologiese en metaboliese buigsaamheid in die lupiene voedingstowwe verkryging strukture plaasvind.

Thesis (M. Phil.)--University of Hong Kong, 1989.

Chitinases are a diverse family of proteins occurring in plants. Their function varies considerably, with certain chitinases having been associated with development. The majority however, are pathogenesis related (PR) proteins that have been shown to play a role during plant pathogen interactions. This has lead to many investigations on the use of chitinases in providing transgenic disease resistance. These studies are usually done using a constitutive expression system. This however stands in contrast with the natural defense system were PR gene expression is usually only upregulated when the plant is exposed to abiotic and/or biotic stress factors. The constitutive expression is therefore not ideal as it increases ‘cost’ penalties due to the energy being spent expressing the gene. In this study however, an inducible expression system was applied using a stress inducible promoter AtGSTF6 derived from Arabidopsis thaliana, to drive Lupinus albus IF3 chitinase expression when the plants are under pathogen attack. The construct AtGSTF6-IF3 was inserted into the binary vector pCAMBIA 2300 and transformed into Nicotiana Tabacum cv JR6 by Agrobacterium-mediated transformation. To demonstrate the functionality of such a construct, an expression study was done on transgenic N. Tabacum to determine transcription and in vitro chitinase enzyme activity. The data revealed that IF3 chitinase gene transcription from lupin plants was achieved in N. Tabacum. Nine of the twelve lines that tested positive for chitinase gene transcription after hydrogen peroxide treatment, showed increased chitinase activity. With the success of showing increased chitinase activity, these lines were subjected to a detached leaf assay with Rhizoctonia solani AG2, which causes leaf target spot disease. The assay showed that six of the nine lines identified as having increased chitinase activity showed reductions in lesion areas. More specifically, three of the four lines showing more than a five-fold increase in chitinase activity compared to the untransformed N. Tabacum, showed significant lesion reduction. The AtGSTF6-IF3 construct can therefore be recommended to increase disease resistance in N. Tabacum towards Rhizoctonia solani AG2 after showing both expression and increased disease resistance in certain transgenic lines. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Plant Science / unrestricted

L’étude proposée s’inscrit dans un contexte de contamination croissante de la pédosphère et fait le choix d’appréhender cette problématique via une approche centrée sur la rhizospère et sur les mécanismes gouvernant son évolution. Ces travaux s'intéressent à la relation entre l’uranium – un métal naturel ubiquiste non-essentiel – et le citrate – un acide organique de faible poids moléculaire exsudé par certaines espèces végétales poussant sur un milieu pauvre en phosphore. Parmi ces espèces particulières le lupin blanc (Lupinus albus) fait office de plante modèle. Un sol naturellement riche en uranium prélevé à l’affleurement d’une veine de pechblende a été étudié. L’objectif du travail a été de savoir si l’activité racinaire est suffisante pour provoquer la remobilisation de l’uranium dans la solution du sol et favoriser son transfert. Le système sol/plante a été étudié sur rhizotest et de manière découplée en hydroponie et en réacteurs fermés. Il a été démontré que la présence d’uranium dans un milieu contrôlé (hydroponie) stimule l’exsudation de citrate chez les lupins blancs qui ne sont pas carencés en phosphore et que cette exsudation de citrate favorise la solubilisation de l’uranium dans la solution du sol en réacteurs fermés. Ces résultats ont été confirmés par les observations faites sur rhizotest même si les valeurs obtenues dans ce cas étaient plus nuancées. Ceci justifie les approches utilisées et met en évidence leur complémentarité. Les résultats obtenus ont également permis d’apporter des informations concernant la toxicité de l’uranium, son internalisation dans les cellules racinaires ainsi que sur son transfert des racines aux parties aériennes. / The present study is related to the context of pedosphere contamination increasing and chose to consider this issue through a focus on rhizosphere and mechanisms that govern its evolution. This work is oriented on the relation between uranium – a non-essential ubiquitous metal – and citrate – a low molecular weight organic acid exudated by specific species when grown on a phosphorus-deficient environment. Among these particular species white lupine (Lupinus albus) is considered as a model species. Furthermore, a natural soil containing huge amounts of uranium has been collected at the outcrop of a pitchblende vein and used during some experiments. The main aim of this PhD thesis was to determine if the root activity of white lupine is sufficient to cause the remobilization of uranium into soil solution and so to promote the transfer of this contaminant to the plant. The soil/plant system has been studied with rhizotests and by combining datas obtained with hydroponics experiments and batches tests. It has been demonstrated that the presence of uranium in a controlled growth medium (hydropony) stimulates citrate exudation in P-sufficient white lupine. More, this citrate exudation enhances uranium solubilization in soil solution in batches. These results have been confirmed by observations on rhizotest even if the values in this case were more nuanced. This justifies the employed approaches and highlights their coherence and complementarity. The results also allowed to provide additional information concerning uranium toxicity, its internalization in root cells as well as its transfer from roots to aerial parts.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-11-23T17:01:38Z No. of bitstreams: 1 2013 - L?lian Guimar?es de Almeida.pdf: 713686 bytes, checksum: 57c134f17845f669da63a2f32063c483 (MD5) / Made available in DSpace on 2018-11-23T17:01:38Z (GMT). No. of bitstreams: 1 2013 - L?lian Guimar?es de Almeida.pdf: 713686 bytes, checksum: 57c134f17845f669da63a2f32063c483 (MD5) Previous issue date: 2013-07-22 / CAPES / The objective of this study was to evaluate the imbibition and white lupine seeds physiological quality as affected by the pre-sowing treatments using immersion on the solutions with distinct micronutrients. The experimental design was conducted in a completely randomized in factorial (3 lots x 7 treatments) with four replications, by period of evaluation (start and after four months of storage). There were used three white lupine seed lots and seven distinct pre-sowing treatments (soaked or not soaked seeds on distilled water and in solution of boric acid (H3BO3), zinc sulphate (ZnSO4), manganese sulphate (MnSO4), copper sulphate (CuSO4), and molybdic acid (H2MoO4)). The seeds were evaluated to the imbibition and subsequently were submitted to the germination and vigor tests (first count of germination and electrical conductivity, dry weight and length of seedlings), as well the determinate of the seeds nutrients content. From the results it can be concluded that there was decreased speed of water absorption in the seed lot with lower physiological quality in the presence of manganese and molybdenum. Seed treatment by immersion in distilled water and in solutions of micronutrients favored physiological seed quality of three lots of white lupine. / O objetivo do trabalho foi avaliar a embebi??o e a qualidade fisiol?gica de sementes de tremo?o branco ap?s terem sido submetidas ao tratamento de pr?-semeadura por imers?o em solu??es de micronutrientes. O delineamento experimental adotado foi o inteiramente casualizado, em esquema fatorial (3 lotes x 7 tratamentos), com quatro repeti??es, por per?odo de avalia??o (inicial e ap?s quatro meses de armazenamento). Foram utilizados tr?s lotes de sementes de tremo?o branco e sete distintos tratamentos de pr?-semeadura (sementes imersas ou n?o em ?gua destilada e em solu??o contendo ?cido b?rico (H3BO3), sulfato de zinco (ZnSO4), sulfato de mangan?s (MnSO4), sulfato de cobre (CuSO4) e ?cido mol?bdico (H2MoO4)). As sementes foram avaliadas quanto ? embebi??o e, em seguida, submetidas aos testes de germina??o e de vigor (primeira contagem e condutividade el?trica, comprimento e massa de pl?ntulas) bem como ? avalia??o do teor de nutrientes. Pelos resultados pode-se concluir que houve diminui??o da velocidade de absor??o de ?gua nas sementes do lote com menor qualidade fisiol?gica inicial, na presen?a de mangan?s e molibd?nio. O tratamento de sementes via imers?o em ?gua destilada e em solu??es de micronutrientes favoreceu a qualidade fisiol?gica das sementes dos tr?s lotes de tremo?o branco.

published_or_final_version / Zoology / Master / Master of Philosophy

Στόχος της παρούσας εργασίας ήταν η διερεύνηση της δυνατότητας παραγωγής υδρογόνου από καθαρές καλλιέργειες του μικροοργανισμού Ruminococcus albus εστιάζοντας κυρίως στο μηχανισμό της διεργασίας. Ο R. albus είναι ένα ετερότροφο, αυστηρά αναερόβιο βακτήριο που διαβιεί στο πρώτο διαμέρισμα του τετραμερούς στομάχου των μηρυκαστικών, τον κεκρύφαλο (rumen). Αναπτύσσεται καταναλώνοντας τους σύνθετους υδατάνθρακες που φτάνουν εκεί μέσω της πρόσληψης τροφής από το μηρυκαστικό, αφού πρώτα τους υδρολύσει μέσω εξωκυτταρικών ενζύμων που παράγει. Τα προϊόντα της υδρόλυσης είναι απλοί υδατάνθρακες που ζυμώνονται περαιτέρω προς παραγωγή λιπαρών οξέων, αιθανόλης, διοξειδίου του άνθρακα και υδρογόνου. Η ικανότητα παραγωγής υδρογόνου και η τελική απόδοση εξαρτώνται από τις συνθήκες υπό τις οποίες πραγματοποιείται η ανάπτυξη. Ο R. albus πιστεύεται ότι είναι πολλά υποσχόμενος για την παραγωγή υδρογόνου από αγροτικά υπολείμματα που είναι πλούσια σε λιγνοκυτταρινούχα υλικά καθώς και ενεργειακά φυτά , όπως είναι το γλυκό σόργο. Οι βλαστοί του γλυκού σόργου είναι πλούσιοι σε σάκχαρα, κυρίως σακχαρόζη σε ποσοστό έως και 55% επί ξηρής μάζας και γλυκόζη (3.2% επί ξηρής μάζας) που απομακρύνονται εύκολα μέσω της διεργασίας εκχύλισης με νερό. Οι βλαστοί του γλυκού σόργου περιέχουν επίσης μεγάλο ποσοστό κυτταρίνης (12.4%) και ημικυτταρίνης (10.2%). Προκειμένου να μελετηθεί ο μεταβολισμός του βακτηρίου και να υπολογιστούν οι κινητικές σταθερές πραγματοποιήθηκαν πειράματα σε αντιδραστήρες διαλείποντος έργου και αντιδραστήρες συνεχούς τροφοδοσίας (CSTR). Ως πηγές άνθρακα χρησιμοποιήθηκαν διάφορα απλά υδατανθρακικά υποστρώματα καθώς και βιομάζα από το ενεργειακό φυτό Sorghum bicolor (γλυκό σόργο). Τα κύρια προϊόντα που ανιχνεύτηκαν σε όλες τις περιπτώσεις ήταν τα οξέα οξικό και μυρμηκικό, η αιθανόλη και το υδρογόνο. Η απόδοση σε υδρογόνο ήταν γενικά μεγαλύτερη στα πειράματα διαλείποντος έργου. Ειδικότερα για τα πειράματα με γλυκόζη, η απόδοση κυμαινόταν μεταξύ των τιμών 2 και 2.6 mol H2/mol γλυκόζης στις καλλιέργειες διαλείποντος έργου, ενώ η βέλτιστη απόδοση από τις συνεχείς καλλιέργειες ήταν 1.07± 017 mol H2/mol γλυκόζης για υδραυλικό χρόνο παραμονής 42 h. Η τελική τιμή απόδοσης παρουσίαζε εξάρτηση από τη μερική πίεση υδρογόνου στην αέρια φάση των καλλιεργειών, το αναγωγικό μέσο για την εξασφάλιση αναγωγικών συνθηκών καθώς και την ποσότητα παραγόμενης αιθανόλης. Η κινητική μικροβιακής ανάπτυξης και παραγωγής υδρογόνου μελετήθηκε μέσω των πειραμάτων με γλυκόζη και η δεύτερη συνδέθηκε μέσω κινητικών εξισώσεων με την διάσπαση του μυρμηκικού οξέος και την παραγωγή αιθανόλης. Άλλα απλά υποστρώματα που μελετήθηκαν είναι οι πεντόζες D- και L-αραβινόζη και η D-ξυλόζη, οι δισακχαρίτες κελλοβιόζη και σακχαρόζη, για τα οποία υπολογίστηκαν οι κινητικές ανάπτυξης του μικροοργανισμού και βέβαια η βιομάζα σόργου, το εκχύλισμα σόργου και τα υπολείμματα σόργου μετά την εκχύλισή του. Οι αποδόσεις σε υδρογόνο ήταν πολλά υποσχόμενες σε όλες τις περιπτώσεις. / The aim of the present work was to investigate the process of hydrogen production using pure cultures of fibrolytic bacterium Ruminococcus albus, focusing mainly on the mechanism of the activity. R. albus is an important fibrolytic bacterium of the rumen, where it cohabits with other bacteria and protozoa. R. albus can ferment soluble sugars and also complex carbohydrates, such as cellulose and hemillulose, after breaking them down through the extracellular enzymes it produces. Regardless the initial substrate used a significant amount of hydrogen evolves from the fermentation process. Previous research with pure cultures of R. albus and whole sorghum, sorghum extract and lignocellulosic residues as substrate, lead to very promising hydrogen yields. Moreover, it was shown that sorghum biomass can be used for hydrogen production with high and similar final yields, independent on whether the process takes place in one stage, i.e. when both simple and complex carbohydrates are fermented in the same fermentor, or in two stages i.e. when sorghum extract and extraction residues are fermented separately. Therefore, it is believed that R. albus is very promising for the production of hydrogen from agricultural residues rich in lignocellulosic materials and from energy crops, such as sweet sorghum which contains soluble sugars and complex carbohydrates in almost equal amounts. Sweet sorghum is an annual C4 plant of tropical origin, well-adapted to sub-tropical and temperate regions and highly biomass-productive. Sweet sorghum stalks are rich in sugars, mainly in sucrose that amounts up to 55% of dry matter and in glucose (3.2% of dry matter). They also contain cellulose (12.4%) and hemicelluloses (10.2%). Extraction of free sugars from the stalks is easily achieved by extraction with water at 30°C. After the extraction process a liquid fraction, rich in sucrose, and a solid fraction, containing the cellulose and hemicelluloses, are obtained. The liquid fraction could be directly fermented to hydrogen, whereas the solid fraction should first be hydrolyzed in order to fully exploit the potential of the sorghum biomass for biohydrogen production In order to study the metabolism of bacterium and estimate growth and hydrogen production kinetics, batch and continuous experiments were carried out with glucose as carbon source. Besides glucose pentoses and disaccharides were tested as well, and the growth kinetics on these substrates were estimated.. The main products that were detected in all the cases were acetate, formate, ethanol and hydrogen. Hydrogen yield was generally higher in batch experiments. More specifically glucose experiments showed yields varying between the values 2 and 2.6 mol H2/mol of glucose in batch cultures, while the optimum yield in continuous cultures was 1.07± 017 mol H2/mol of glucose when the hydraulic retention time was 42h. The final hydrogen yield seemed to depend on hydrogen partial pressure, the reducing agent used and the final amount of ethanol.. The production of hydrogen was studied with glucose experiments and was connected via kinetic equations with formate breaking down acid and ethanol production. The other simple substrates that were studied were the pentoses D - and L-arabinose and the D-xylose, the disaccharides cellobiose and sucrose, for which the growth constants were calculated. Subsequently whole sorghum biomass, sorghum extract and lignocellulosic sorghum residues were tested and the experimental results were simulated. The simulations were sufficient in all cases, and hydrogen yields were very promising.