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<p> The blood and sugars, on which adult black-flies fed, stimulated the buccal sensilla so that blood. went directly to the midgut and sugars to the crop. Agglutinin and anticoagulant were found in the salivary glands of female simuliids. </p> <p> The sequence of peritropbic membrane formation and disappearance are discussed in relation to blood digestion. </p> <p> Digestive enzymes, such as that of trypsin and invertase activity occurred in the midgut of both sexes of several black-fly species unfed or fed on sucrose, but an increase in enzyme Activity was stimulated in females by a blood meal. A weak amylase-like activity was found in the midgut, but the activity was not stimulated by blood- feeding. A greater amylase activity was found in the residual fluid (haemolymph). Trypsin activity in females, but not in males, increased also after feeding blood-sucrose mixtures. Blackfly invertase promoted oligosaccharide synthesis. Trypsin, amylase and invertase showed pH optima of 8.4, 6.5 and 6.2 respectively. </p> / Thesis / Doctor of Philosophy (PhD)

The present thesis examined the relative contribution of dopamine (DA) receptors in the brain and periphery in the control of sucrose intake. Intraperitoneal (ip) administration of pimozide, an antagonist at peripheral and brain DA receptors, suppressed both sham and real sucrose intake in a dose-related manner. In contrast, ip injections of the peripheral DA antagonist domperidone affected neither sham nor real sucrose intake. The inability of domperidone to influence sucrose intake did not result from a lack of biological activity because doses of domperidone that did not alter sucrose intake significantly inhibited gastric acid secretion. The results indicate that central, but not peripheral DA receptors are involved in the control of feeding of sucrose solutions and that sham sucrose intake appears to be more sensitive to disruption of DA activity than real sucrose intake. / Thesis / Master of Science (MSc)

Soybean [Glycine max (L.) Merr] is one of the U.S.'s most economically important crops due to the protein and oil content of seeds. The major storage form of phosphorus in soybean seeds is found in the form of phytate, but because of its negative nutritional and environmental impacts, seed phytate and raffinosaccharide content have been a recent focus of breeders and molecular geneticists. The soybean line CX1834 is a low phytate mutant known to have two low phytate QTLs on linkage groups (LGs) L and N. The first objective of this research was to determine the genetic basis of the low phytate trait in CX1834. By using the whole genome sequence, we identified two candidate multidrug resistance-associated (MRP) ABC transporter genes. Sequencing the genes from CX1834 and comparing them to the reference genome sequence revealed a single nucleotide polymorphism (SNP) in the MRP gene located on LG N (causing a stop codon), and a SNP mutation in the MRP gene located on LG L (causing an amino acid change from arginine to lysine). One major concern with low phytate soybeans is the low seedling emergence. The second objective was to undertake a population-wide study of emergence in the recombinant inbred population CX1834 x V99-3337, over two years and two locations. We found a positive correlation between phytate level and emergence, and that variation among year, location, genotypic class, year x genotypic class, and year x location interactions were significantly affecting emergence. V99-5089, in addition to being low phytate, has high sucrose and low raffinosaccharide content. This phenotype of V99-5089 has been previously determined to be due to a SNP mutation in its myo-inositol phosphate synthase (MIPS) gene located on LG B1. The third objective was to use the recombinant inbred population derived from CX1834 x V99-5089 to observe the combinations of all three mutations to see how the different alleles impact phytate and raffinosaccharide content. The individuals with all three mutations, as well as those with the two MRP mutations together had lower phytate than the other genotypic classes. However, these lines (all three mutations) had unexpectedly high stachyose. / Ph. D.

A sacarose sintetase pode ser extraída de bananas pré-climatéricas cisteína (0,02M), em tampão tris-HCl pH 8,0 (0,05M), contendo EDTA (O,OlM), PVP (1%) e bissulfito de sódio (0,02M) na proporção de 1:4 (massa de banana/volume desolução f extratora). O seu isolamento pode ser efetuado por precipitação com sulfato de amônio, cromatografia por peneira molecular seguida de troca iônica ou, alternativ~ente, por cromatografia apenas em troca iônica. Obtém-se assim preparações com atividade específica entre 0,42 e 6,11 e grau de purificação de 5 a 18 vezes. A enzima purificada tem elevada afinidade por UDPG (Km = 0,67), UDP (Km = O, 17) , frutose (Km = 0,31) e reduzida afinidade para a sacarose (Km = 22,7). A enzima está presente durante a fase de desenvolvimento do fruto até o período préclimatérico, quando sua atividade sintética e hidrolítica tende a desaparecer a medida que aumenta o tempo decorrido após a colheita. Contrariamente, a sacarose fosfato sintetase não é detectada nas fases iniciais de desenvolvimento do fruto, mas tem sua atividade aumentada durante o amadurecimento, concomitantemente ao desaparecimento do amido. A sacarose fosfato sintetase e não a sacarose sintetase pode estar envolvida na transformação amido-sacarose durante o amadurecimento. / Banana sucrose synthetase can be purified almost to homogeneity by extraction with tris-HCl pH 8.0 (0.05M) buffer containing cystein (0.02M), EDTA (O.OlM), PVP (1%) and NaHS03 (O.O2M), ammonium sulfate precipitation, followed by cromatography on DEAE-cellulose (or alteratively on Sepharose-6B followed by DEAE-cellulose). The purified enzyme activities has high affinity for UDPG (Km = 0.67), UDP (Km = 0.17), fructose (Km = 0.31) and low affinity for sucrose (Km = 22.7). The sucrose synthetase is present during all stages of fruit development until the climateric when its activity tends to disappear, as the time after harvesting decurs contrarily the activity of sucrose phosphate synthetase is not detected in the initial stages of development but its activity increases during ripening following starch desappearance. Sucrose phosphate synthetase instead of sucrose synthetase may be involved in starch-sucrose conversion in post-harvest bananas.

A sacarose sintetase pode ser extraída de bananas pré-climatéricas cisteína (0,02M), em tampão tris-HCl pH 8,0 (0,05M), contendo EDTA (O,OlM), PVP (1%) e bissulfito de sódio (0,02M) na proporção de 1:4 (massa de banana/volume desolução f extratora). O seu isolamento pode ser efetuado por precipitação com sulfato de amônio, cromatografia por peneira molecular seguida de troca iônica ou, alternativ~ente, por cromatografia apenas em troca iônica. Obtém-se assim preparações com atividade específica entre 0,42 e 6,11 e grau de purificação de 5 a 18 vezes. A enzima purificada tem elevada afinidade por UDPG (Km = 0,67), UDP (Km = O, 17) , frutose (Km = 0,31) e reduzida afinidade para a sacarose (Km = 22,7). A enzima está presente durante a fase de desenvolvimento do fruto até o período préclimatérico, quando sua atividade sintética e hidrolítica tende a desaparecer a medida que aumenta o tempo decorrido após a colheita. Contrariamente, a sacarose fosfato sintetase não é detectada nas fases iniciais de desenvolvimento do fruto, mas tem sua atividade aumentada durante o amadurecimento, concomitantemente ao desaparecimento do amido. A sacarose fosfato sintetase e não a sacarose sintetase pode estar envolvida na transformação amido-sacarose durante o amadurecimento. / Banana sucrose synthetase can be purified almost to homogeneity by extraction with tris-HCl pH 8.0 (0.05M) buffer containing cystein (0.02M), EDTA (O.OlM), PVP (1%) and NaHS03 (O.O2M), ammonium sulfate precipitation, followed by cromatography on DEAE-cellulose (or alteratively on Sepharose-6B followed by DEAE-cellulose). The purified enzyme activities has high affinity for UDPG (Km = 0.67), UDP (Km = 0.17), fructose (Km = 0.31) and low affinity for sucrose (Km = 22.7). The sucrose synthetase is present during all stages of fruit development until the climateric when its activity tends to disappear, as the time after harvesting decurs contrarily the activity of sucrose phosphate synthetase is not detected in the initial stages of development but its activity increases during ripening following starch desappearance. Sucrose phosphate synthetase instead of sucrose synthetase may be involved in starch-sucrose conversion in post-harvest bananas.

Thesis (MSc (Biochemistry))--University of Stellenbosch, 2006. / This thesis is about mathematical modelling of sucrose accumulation in the storage perenchyma of Saccharum officinarum (sugarcane) In 2001, Rohwer & Botha (76) published a kinetic model that described the defining feature of this process ...

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005. / The main substrate use during shoot establishment from the lateral bud of sugarcane setts and enzymes involved in sucrose metabolism were investigated in the shoots and the internodes acting as source of carbohydrates. Radiolabelling studies were conducted to investigate the metabolism of sucrose and glucose during shoot establishment. The internode’s total dry mass over the 21-day of shoot establishment period was reduced by 25% and 30% in plants incubated in dark/light and total darkness, respectively.

The study was designed to indirectly understand muscle glycogen utilization during prolonged exercise when either glucose, fructose, or water is ingested. Eight trained adult males exercised on a cycle ergometer at 58±7% of V02 max for 2 h on 2-4 occasions. At 0 minutes of exercise and at 30-minute intervals throughout the exercise, the subjects ingested 200mL of fluid containing either glucose, fructose, or plain water in a double-blind, randomized fashion. The carbohydrate (CHO) fluid concentration was based on each subject's body weight (BW): Ig CHO X kg⁻¹ BW X L⁻¹ water and ranged from 5.8-9.2% (average=7.5%) of BW. Blood samples were collected from subjects at rest and immediately prior to fluid ingestion during exercise and analyzed for hematocrit, hemoglobin, and plasma levels of glucose, lactate, and pyridoxal 5'-phosphate (PLP). ANOVA showed no significant difference among treatments at any time of exercise for mean plasma lactate and PLP levels (p > 0.05). Although not significant, mean plasma lactate and PLP concentrations tended to be lower when glucose was consumed as compared to fructose and water. The mean plasma glucose level, however, uas significantly different among treatments at specific time points of exercise (p < 0.05). During exercise, mean plasma glucose decreased, and there was a higher plasma glucose level when glucose and fructose fluids were ingested as compared to water. At 60 minutes of exercise, this difference uas evident for both glucose and fructose ingestion (p < 0.05). At 90 and 120 minutes of exercise, fructose ingestion produced a significantly higher mean plasma glucose level than either water or glucose ingestion (p < 0.05). It is hypothesized that the higher plasma glucose levels provided a greater blood glucose supply to working muscles, thereby sparing muscle glycogen stores. The findings indicate that for the long-term exerciser, consumption of a 5.8-9.2% fructose solution may promote less muscle glycogen utilization than either glucose or water, thereby possibly increasing endurance. / Graduation date: 1986

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