Thesis (Ph.D.)--Baylor University, 2008. / Includes bibliographical references (p. 121-133)

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 131-132). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 131-132). Also available on the Internet.

Thesis (M.A.(MHS))-University of Pretoria, 1999. / Summary in English and Afrikaans.

Thesis (Ph.D.)--University of Wollongong, 2008. / Typescript. Includes bibliographical references.

Thesis--University of Oklahoma. / Bibliography: leaves 59-65.

Thesis (M. Sc.(Agric.))( Animal Science)--University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (MSc (Genetics. Plant Biotechnology))--University of Stellenbosch, 2007. / Despite numerous attempts involving a variety of target genes, the identity of the key regulatory genes of sucrose metabolism in sugarcane is still illusive. To date, genomic research into sucrose accumulation in sugarcane has focused on genes that are expressed in association with stalk development/maturation, with the aim of identifying key regulatory steps in sucrose metabolism. The identification of possible controlling points, however, is complicated by the polyploid nature of sugarcane. Although these studies have yielded extensive annotated gene lists and correlative data, the identity of key regulatory genes remains elusive. A close relative of sugarcane, Sorghum bicolor, is diploid, has a small genome size and accumulates sucrose in the stalk parenchyma. The main aim of the work presented in this thesis was to use S. bicolor as a model to identify genes that are differentially expressed during sucrose accumulation in the stalk of low and high sucrose genotypes. In the first part of the study, a macroarray protocol for identification of differentially expressed genes during sorghum development was established. Firstly, the macroarray sensitivity of probe-target hybridisation was optimised with increasing amounts of target DNA i.e. 0.005-0.075 pmol. The hybridisation signal intensity increased as expected with increasing amounts of probe until the hybridisation signals reached maximum levels at 0.05 pmol. As a result, to ensure quantitative cDNA detection, probes were arrayed at 0.05 pmol when 1 μg target cDNA was used. Secondly, intra-array and inter-array membrane reproducibility was found to be high. In addition, the protocol was able to detect species of mRNA at the lowest detection limit tested (0.06%) and permits the detection of an eight-fold variation in transcript levels. The conclusion was therefore that the protocol was reproducible, robust and can reliably detect changes in mRNA levels. In the second part of the study, sugar accumulation levels in the immature and maturing internodal tissues of sorghum GH1 and SH2 genotypes were compared during the boot and softdough stages. Sugars (i.e. fructose, glucose and sucrose) accumulated differently in the immature and maturing internodes in both sorghum genotypes during the boot and softdough stages, with sucrose being the dominant sugar in both stages. Based on these differences in sugar accumulation patterns, immature and maturing internodal tissues of sorghum genotypes were compared for differentially expressed genes. A number of genes were found to be significantly differentially expressed during both stages. In order to validate the reliability of the macroarray analysis, fourteen genes were arbitrarily selected for semi-quantitative RT-PCR. Seven genes (50%) revealed a similar pattern of transcript expression, confirming the macroarray results. The other seven genes, however, showed a different expression trend compared with the macroarrays. In this study, ESTs from rice and sugarcane were used for probing sorghum. The probability of cross-hybridisation between the probes and various isoforms of the homologous sorghum sequences is thus high, potentially leading to the identification of false positives. In addition, variation in expression patterns could have been introduced by technical and biological variation. Lastly, to verify that changes in the levels of a transcript are also reflected in changes in enzyme activity, seven candidates were tested for enzyme activity. Only three i.e. soluble acid invertase (SAI), sucrose synthase (SuSy) and alcohol dehydrogenase (ADH), out of these seven genes showed enzyme activity levels reflective of the relative transcript expression. We concluded that changes in transcript levels may or may not immediately lead to similar changes in enzyme activity. In addition, enzyme activity may be controlled at transcriptional and at posttranscriptional levels. In conclusion, sugar accumulation in low (GH1) and high (SH2) sucrose sorghum genotypes is influenced by differences in gene expression. In addition, the power of macroarrays and confirmation with semi-quantitative RT-PCR for identification of differentially expressed genes in sorghum genotypes was demonstrated. Moreover, the transcript and enzyme activity patterns of SAI, SuSy and ADH genes showed expression patterns similar to those of sugarcane during sucrose accumulation. Therefore, using sorghum as a model promises to enhance and refine our understanding of sucrose accumulation in sugarcane.

Thesis (MScAgric)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Protea cut flowers are exported worldwide but the vase life of some species and cultivars is considerably shortened by post-harvest leaf blackening. Research has established carbohydrate depletion to be positively correlated with this disorder. Consequently, a study had been made of the carbohydrate status of various species and cultivars, as well as the effect of supplemental glucose (pre and post-storage) on leaf blackening. Glucose, fructose, sucrose and starch concentrations of various Protea species and cultivars held in water were measured at harvest, and again at leaf blackening initiation. All measured carbohydrates declined significantly in 'Carnival', 'Pink Ice' and 'Sheila'. In 'Cardinal' all carbohydrate concentrations decreased significantly, except the sucrose concentration in the inflorescence. 'Susara' and 'Ivy' had very high initial carbohydrate concentrations in the leaves which decreased significantly. The very high initial carbohydrate concentrations in the inflorescence of 'Ivy' declined significantly. 'Brenda' differed from the other cultivars and species in that glucose concentrations increased over time. Carbohydrate concentrations of most of the tested proteas declined significantly from harvest to the initiation of leaf blackening. This highlighted the dependence of the leaves and inflorescence on the carbohydrate reserves, further substantiating the carbohydrate depletion theory. The inflorescences were characterized by high fructose and glucose concentrations and low sucrose concentrations when compared to the leaves. It was hypothesized that glucose pulsing and cold storage at 1°C for three weeks would significantly reduce leaf blackening. 'Brenda', 'Cardinal', 'Carnival', 'Pink Ice', 'Susara ' and 'Sylvia' had significantly less leaf blackening with glucose treatments of 4 and 10%. Leaf blackening of 'Sheila', P. cynaroides and P. grandiceps was not significantly reduced by glucose pulsing. P. magnifica showed a small, but significant, reduction in leaf blackening in response to the 3, 6 and 9% treatments after 10 days only, but despite this, leaf blackening was unacceptably high. 'Pink Ice' harvested at the soft tip stage had less leaf blackening than those harvested open or closed. Toxicity symptoms on the leaves, and in some instances flowers, were observed at higher glucose concentrations (8 and 10%) onP. grandiceps, P. cynaroides, 'Cardinal' and 'Sheila'. All glucose treatments resulted in toxicity symptoms on P. magnifica. A decrease in nonstructural carbohydrates post-harvest apparently occurs in all proteas but it appears that only members of the Ligulatae respond to glucose. Glucose pulsing followed by cold storage at 1°C for three weeks in combination with post-storage glucose vase solutions, significantly reduced leaf blackening of some Protea cultivars. Glucose (1 and 2%), with hypochlorite, significantly delayed leaf blackening in 'Cardinal' and 'Sylvia' after seven days. Leaf blackening of 'Brenda', 'Carnival', 'Pink Ice' and 'Susara' was not significantly reduced by the glucose vase solutions. Other disinfectants, in combination with the sugar treatments, need to be evaluated since the hypochlorite treatment had a dehydrating effect on all the cultivars and resulted in increased leaf blackening. Carbohydrate supplementation of protea flowers with glucose, pre and post-storage, will help meet the post-harvest carbohydrate requirements of certain Protea cultivars and species to an extent. Glucose treatments must be seen in conjunction with maintaining the cold chain and when combined with cold chain maintenance, can extend the storage and vase life. / AFRIKAANSE OPSOMMING: Protea snyblomme word wêreldwyd uitgevoer alhoewel die vaasleeftyd van sommige spesies en kultivars beduidend verkort word deur na-oes loof verbruining. Navorsing het koolhidraatverbruik positief gekorreleer met hierdie probleem. Gevolglik is 'n studie gemaak van die koolhidraatstatus van verskeie spesies en kultivars asook die effek van addisionele glukose (voor en na opberging) op loofverbruining. Glukose, fruktose, sukrose en stysel konsentrasies van verskeie Protea spesies en kultivars wat in water gehou is, is bepaal met oes en weer met die eerste tekens van loofverbruining. Al die gemete koolhidraatkonsentrasies het beduidend afgeneem in 'Carnival', 'Pink Ice' en 'Sheila'. In 'Cardinal' het al die koolhidraatkonsentrasies beduidend afgeneem, behalwe vir die sukrosekonsentrasie in die blom. 'Susara' en 'Ivy' het baie hoë begin koolhidraatkonsentrasies in die blare wat beduidend afneem. Die baie hoë inisiële koolhidraatkonsentrasies in die blom van 'Ivy' neem beduidend af met tyd. 'Brenda' verskil van die ander kultivars en spesies deurdat die glukosekonsentrasies toeneem met tyd. Koolhidraatkonsentrasies van die meeste getoetste proteas neem beduidend af vanaf oes totdat die eerste tekens van loofverbruining verskyn. Dit het die afhanklikheid van die blare en blom op die koolhidraatreserwes beklemtoon en daardeur verder die koolhidraatteorie ondersteun. Die blomme is gekarakteriseer deur hoë fruktose- en glukosekonsentrasies en lae sukrosekonsentrasies wanneer dit met die blare vergelyk is.Die hipotese is gestel dat die voorsiening van glukose, vir 'n aantal ure, gekombineerd met koue opberging by 1°C vir drie weke loofverbruining beduidend sal verminder. 'Brenda', 'Cardinal', 'Carnival', 'Pink lee', 'Susara' en 'Sylvia' het beduidend minder loofverbruining met glukose behandelings tussen 4 en 10%. Loofverbruining van 'Sheila', P. cynaroides en P. grandiceps is nie beduidend verminder deur glukose behandelings nie. P. magnifica het 'n klein, maar beduidende verlaging in loofverbruining getoon met die 3, 6 en 9% behandelings na 10 dae, maar ten spyte hiervan was loofverbruining onaanvaarbaar hoog. 'Pink lee' is geoes by die sagte punt stadium en het minder loofverbruining gehad as blomme wat oop of toe geoes is. Toksisiteitsimptome op die blare, en in sommige gevalle blomme, is waargeneem met hoër glukose konsentrasies (8 en 10%) op P. grandiceps, P. cynaroides, 'Cardinal' en 'Sheila'. Alle glukosebehandelings het toksisiteitsimptome tot gevolg gehad op P. magnifica. 'n Afname in nie-strukturele koolhidrate na oes kom waarskynlik voor in alle proteas maar dit wil voorkom of slegs lede van die Ligulatae positief reageer op glukose. Glukosebehandeling gevolg deur koue opberging by 1°C vir drie weke in kombinasie met na-stoor glukose vaasoplossings het loofverbruining van sommige Protea kultivars beduidend verminder. Glukose (l en 2%), saam met hipoehloriet, het loofverbruining beduidend verminder in 'Cardinal' en 'Sylvia' na sewe dae. Loofverbruining van 'Brenda', 'Carnival', 'Pink lee' en 'Susara' is nie beduidend verminder deur die glukose vaasoplossings nie. Ander ontsmettingsmiddels in kombinasie met die suikerbehandelings moet geëvalueer word aangesien die hipoehlorietbehandeling 'n dehidrerende effek op al die kultivars gehad het en 'n toename in loofverbruining tot gevolg gehad het. Byvoeging van glukose by proteablomme, voor en na opberging, sal tot 'n mate help om in die na-oes koolhidraatbehoeftes van sekere Protea kultivars en spesies te voorsien. Glukosebehandelings moet saam met die beheer van die koueketting gesien word en wanneer gekombineerd met koueketting beheer kan dit opberg en vaasleeftyd verleng.

Orientador: Heraldo César Gonçalves / Banca: Ciniro Costa / Banca: Renata Helena Branco Arnandes / Resumo: Foram utilizadas 20 cabras Alpinas primíparas e multíparas com aproximadamente 80 dias em lactação, alojadas individualmente em gaiolas metálicas e distribuídas de acordo com a produção de leite em cinco quadrados latinos 4 x 4. As dietas experimentais utilizadas apresentaram relação concentrado: volumoso 65:35. Os tratamentos foram caracterizados por níveis crescentes 0, 33, 67 e 100% de silagem de grãos úmidos de milho (SGUM) em substituição ao grão seco de milho (GSM). As médias do consumo de matéria seca (1,64 kg/dia, 3,9 %PV ou 99,35 g/PM), proteína bruta (0,20 kg/dia) e matéria orgânica (1,53 kg/dia) não foram influenciadas pelos níveis de SGUM. Entretanto as medias para o consumo de extrato etéreo (0,067 kg/dia), fibra em detergente neutro (0,82 kg/dia ou 49,51 g/PM), carboidratos não estruturais (0,45 kg/dia), nutrientes digestíveis totais (1,20 kg/dia) e energia líquida (1,66 Mcal/dia) foram significativos (P<0,05) para os diferentes níveis de SGUM. A digestibilidade aparente da matéria seca (73,51 %), matéria orgânica (74,77%) e dos nutrientes, proteína bruta (71,30%), extrato etéreo (82,03%), fibra em detergente neutro (65,88%), carboidrato não fibroso (85,09%) foram afetados pelos diferentes níveis de SGUM (P<0,05). Conclui-se que a SGUM não alterou o consumo de MS e melhorou as digestibilidade dos nutrientes, podendo ser usada em substituição parcial ou total ao GSM na alimentação de cabras Alpinas. / Abstract: Twenty primiparous and multiparous Alpine goats (11-12 weeks in lactation) were individually housed in metallic cages and assigned according to milk production in five 4 x 4 Latin square arrangement. All experimental diets presented 65:35 concentrate to forage ratio. Treatments were considered the graded replacement levels (0, 33, 67 and 100%) of high moisture corn silage (HMCS) by corn grain (CG). Average values of dry matter intake (1.64 kg/day, 3.9 %LW or 99.35 g/MW), crude protein (0.20 kg/day) and organic matter (1.53 kg/day) were not influenced by HMCS dietary levels. However, intakes of ether extract (0.067 kg/day), neutral detergent fiber (0.82 kg/day or 49.51 g/MW), non-structural carbohydrates (0.45 kg/day), total digestible nutrients (1.20 kg/day) and liquid energy (1.66 Mcal/day) were different (P<0.05) respective to the dietary treatments. Apparent digestibility of dry matter (73.51%), organic matter (74.77%), crude protein (71.30%), ether extract (82.03%), neutral detergent fiber (65.88%), non-fiber carbohydrates (85.09%) showed differences respective to the dietary HMCS levels (P<0.05). It is concluded that the SGUM did not modify the MS consumption and improved the digestibilidade of the nutrients, being able to be used in partial or total substitution to the GSM in the feeding of Alpine goats / Mestre