Adolescent athletes of this era are more pressurized than adolescents of previous generations to perform at an optimum level (Micheli & Jenkins 2001, p49). The importance of winning can result in adolescent athletes developing inappropriate nutritional practices such as neglecting hydration and consuming insufficient carbohydrate (Micheli & Jenkins 2001, p57). Consuming insufficient fluid leads to dehydration which reduces a soccer player’s ability to continue training. Consuming inadequate carbohydrate reduces performance and blood glucose levels during training. This study aimed to determine the hydration status, fluid and carbohydrate intake of male, adolescent soccer players during training. A cross-sectional study was conducted among 122 amateur male, adolescent soccer players (mean age = 15.8 ± 0.8 years; mean BMI = 20.4 ± 2.0 kg/m2). The players’ hydration status before and after training, was measured using urine specific gravity and percent loss of body weight. Their carbohydrate intake, as well as the type and amount of fluid consumed, were assessed before, during and after training. A questionnaire was administered to determine the players’ knowledge regarding the importance of fluid and carbohydrate for soccer training. The study had an 87.1% response rate. The mean environmental conditions did not predispose players to heat illness. However, the players were at risk of developing heat illness during six of the 14 training sessions. Although the mean urine specific gravity indicated that players were slightly dehydrated before and after training, 43.8% of players were very or extremely dehydrated before training and 53.6% after training. A few (3.3%) were extremely hyperhydrated before training and after training (7.0%). On average players lost less than 1% of body weight during training and less than 3% of players dehydrated more than 2%. Players consumed mainly water before (289.17 ± 206.37 ml), during (183.20 ± 158.35 ml) and after (259.09 ± 192.29 ml) training. More than 90% stated that water was the most important fluid to consume before, during and after training. Very few (4.7%) correctly stated that carbohydrate should be consumed before, during and after training. Players were found to be slightly dehydrated before and after training and therefore were not consuming enough fluids during training. Players consumed inadequate amounts and types of fluid and carbohydrate. This not only compromises their performance but also health. Players were not aware of the importance of fluid and carbohydrate for soccer training. This study is unique in that it focused on the carbohydrate and hydration practices of socioeconomically disadvantaged adolescent soccer players during training. The study sample therefore represents a high risk group about which there is limited published data both locally and internationally. This study generated important baseline information which was lacking before on the hydration status, fluid and carbohydrate intake of adolescent soccer players in South Africa. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

The physiological benefits of flaxseed against pathological disturbances, such as cancers and heart diseases, are mainly attributed to its high lignan content. This study (Experiment 1) examined the application of pressurized low polarity water (PLPW) for extraction of lignans, proteins and carbohydrates from defatted flaxseed meal. Key processing conditions included temperature (130, 160, 190°C), solvent pH (4, 6.5 and 9), solvent to solid ratio (S/S) (90, 150 and 210 mL/g) and introduction of co-packing material (0 and 3 g glass beads). The addition of 3 g glass beads as co-packing material facilitated extraction by enhancing surface contact between the liquid and solid thus shortening extraction time. Elevated temperature accelerated the extraction rate by increasing the solid diffusion coefficient thereby reducing the extraction time. The maximum yield of lignans (99 %) was obtained at temperatures ranging from 160°C to 190°C, with solvent volume of 180 mL (90 mL/g meal) at pH 9. Optimal conditions for protein extraction (70 %) were pH 9, extraction volume of 420 mL (210 mL/g meal) and 160°C. Total carbohydrates yield was maximized at 50% recovery at pH 4 and 160°C with 420 mL solvent (210 mL/g meal). Increased temperature accelerated extraction, thus reducing solvent volume and time to reach equilibrium. For the extraction of proteins, however, a temperature of 130-160°C is recommended, as proteins are vulnerable to thermal degradation due to heat decomposition. The effects of flow rate and geometric dimensions for extraction of lignans and other flaxseed meal bioactives were further investigated in Experiment 2, based on the variables optimized in the previous experiment. Defatted flaxseed meal was extracted with pH 9 buffered water with meal to co-packing glass beads ratio of 1:1.5 at 5.2 MPa (750 psi) and 180°C. The aqueous extracts were analyzed for lignan, protein and carbohydrate using HPLC and colorimetric methods. The optimal extraction yields for lignan, protein and carbohydrate were found at flow rates of 1 to 2 mL/min with bed depth between 20 and 26 cm and a S/S ratio of 40 to 100 mL/g. The combination of low flow rate and high bed depth allowed the use of lower S/S ratio with reduced total solvent volume consumption. This study also evaluated the mass transfer kinetics governing the process of lignan extraction from flaxseed meal in a fixed bed extraction cell. Diffusion of solute into the continuously flowing solvent was mainly responsible for the mass transfer mechanism as flow rate did not increase proportionally with the yield and rate of extraction. The extraction kinetics were studied on the basis of two approaches: Fick’s diffusion equation and a two-site exponential kinetic model. The proposed two-site exponential kinetic model corresponding to the two-stage extraction (rapid and slow phases) successfully described the experimental data. Diffusivities attained from Fick’s diffusion model ranged from 2 x 10-13 to 9 x 10-13 m2s-1 while mass transfer coefficients were between 4.5 x 10-8 and 2.3 x 10-7 ms-1 for extraction of lignans at 180°C, pH 9 with 1:1.5 meal to co-packing material ratio.

The physiological benefits of flaxseed against pathological disturbances, such as cancers and heart diseases, are mainly attributed to its high lignan content. This study (Experiment 1) examined the application of pressurized low polarity water (PLPW) for extraction of lignans, proteins and carbohydrates from defatted flaxseed meal. Key processing conditions included temperature (130, 160, 190°C), solvent pH (4, 6.5 and 9), solvent to solid ratio (S/S) (90, 150 and 210 mL/g) and introduction of co-packing material (0 and 3 g glass beads). The addition of 3 g glass beads as co-packing material facilitated extraction by enhancing surface contact between the liquid and solid thus shortening extraction time. Elevated temperature accelerated the extraction rate by increasing the solid diffusion coefficient thereby reducing the extraction time. The maximum yield of lignans (99 %) was obtained at temperatures ranging from 160°C to 190°C, with solvent volume of 180 mL (90 mL/g meal) at pH 9. Optimal conditions for protein extraction (70 %) were pH 9, extraction volume of 420 mL (210 mL/g meal) and 160°C. Total carbohydrates yield was maximized at 50% recovery at pH 4 and 160°C with 420 mL solvent (210 mL/g meal). Increased temperature accelerated extraction, thus reducing solvent volume and time to reach equilibrium. For the extraction of proteins, however, a temperature of 130-160°C is recommended, as proteins are vulnerable to thermal degradation due to heat decomposition. The effects of flow rate and geometric dimensions for extraction of lignans and other flaxseed meal bioactives were further investigated in Experiment 2, based on the variables optimized in the previous experiment. Defatted flaxseed meal was extracted with pH 9 buffered water with meal to co-packing glass beads ratio of 1:1.5 at 5.2 MPa (750 psi) and 180°C. The aqueous extracts were analyzed for lignan, protein and carbohydrate using HPLC and colorimetric methods. The optimal extraction yields for lignan, protein and carbohydrate were found at flow rates of 1 to 2 mL/min with bed depth between 20 and 26 cm and a S/S ratio of 40 to 100 mL/g. The combination of low flow rate and high bed depth allowed the use of lower S/S ratio with reduced total solvent volume consumption. This study also evaluated the mass transfer kinetics governing the process of lignan extraction from flaxseed meal in a fixed bed extraction cell. Diffusion of solute into the continuously flowing solvent was mainly responsible for the mass transfer mechanism as flow rate did not increase proportionally with the yield and rate of extraction. The extraction kinetics were studied on the basis of two approaches: Fick’s diffusion equation and a two-site exponential kinetic model. The proposed two-site exponential kinetic model corresponding to the two-stage extraction (rapid and slow phases) successfully described the experimental data. Diffusivities attained from Fick’s diffusion model ranged from 2 x 10-13 to 9 x 10-13 m2s-1 while mass transfer coefficients were between 4.5 x 10-8 and 2.3 x 10-7 ms-1 for extraction of lignans at 180°C, pH 9 with 1:1.5 meal to co-packing material ratio.

Aquaculture represents a sustainable alternative to natural fisheries for provision of high quality, animal protein. Crustaceans make a significant contribution to global aquaculture production, of which decapods are the most economically important group. Among freshwater crayfish, the genus Cherax includes several species that have emerged as important culture species. A suite of favourable biological attributes, including fast growth and an omnivorous feeding habit, have contributed to establishment of successful culture of Cherax quadricarinatus (redclaw) in many countries. Aspects of redclaw production, however, remain relatively undeveloped, in particular feed formulation. To better understand the digestive processes and nutritional requirements of redclaw, this study examined the relationship between diet composition and digestive enzyme activity, growth performance and diet digestibility coefficients. The extent to which redclaw can efficiently utilise complex polysaccharides, such as cellulose, has been speculated on by authors who reported endogenous cellulase activity in this species. I evaluated the use of insoluble α-cellulose by redclaw, demonstrated that high dietary levels (30%) can significantly reduce the specific activity of selected digestive enzymes (amylase and cellulase), while also lowering apparent digestibility coefficients. Inclusion of α-cellulose above 12% also significantly reduced survival rate, specific growth rate and feeding efficiency in this organism which corresponds with low tolerance for insoluble fibre by other decapods. Even though redclaw possess endogenous cellulases, they appear to have only a limited capacity to utilise insoluble fibre in their diets. Further, I assessed the impact of different nutrient profiles on digestive enzyme activity, growth and tail muscle composition in redclaw. Purified diets containing varying levels of dietary protein significantly affected activity of digestive enzymes (protease, amylase and cellulase) and the composition of the tail muscle tissue. Redclaw have a relatively low protein requirement, which was reflected here, as little significant difference was observed in growth rates and the feed conversion ratio was only significantly affected by the lowest protein diet. Manipulation of the non-protein energy component in purified diets (protein to lipid ratio) had no effect on growth performance indices in redclaw. Digestive enzyme activity (protease) was however, strongly influenced by both the amount of protein and lipid in the diet and a significant correlation was observed between protease activity and growth performance indices. The findings here, provide preliminary data for consideration of digestive enzymes such as proteases as potential growth indicators for freshwater crayfish. These enzymes are already recognised as reliable biological indicators for comparison of digestive efficiency and potential growth rate in fish. The relationship between diet composition and digestive enzyme expression observed here, stress the need for further empirical evaluation of specific ingredients in artificial diets for redclaw. A range of single cell, plant and animal-based, agricultural products were assessed for their potential use in diets formulated for redclaw. Analysis of dietary supplements revealed that apparent digestibility of crude protein was generally higher for diets containing plant-based ingredients. A similar outcome was observed for digestibility coefficients of test ingredients. Ingredient type also had a significant effect on digestive enzyme activity. Importantly, a significant correlation was observed for enzyme activity and apparent digestibility coefficients. It appears that redclaw have the capacity to utilise nutrients from a broad range of dietary ingredients successfully including animal, single cell and in particular, plant matter in their diet. Taken together, the results presented here demonstrate that digestive enzyme activities in redclaw are significantly influenced by diet composition. I show clearly that the ability of redclaw to utilise various nutrients (measured as digestibility coefficients) is highly correlated with digestive enzyme activity. Finally, protease activity demonstrated a potential for use as an indicator of redclaw growth performance. The data presented here will contribute to development of better and cheaper feed formulations for use in redclaw aquaculture and have broader applications to freshwater crustacean culture. In particular, the potential for use of plant-based ingredients in aqua-feeds for redclaw will contribute to a more economically and environmentally sustainable redclaw culture.

Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xi, 126 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 93-115).

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Despite numerous attempts involving a variety of target genes, the successful transgenic manipulation of sucrose accumulation in sugarcane remains elusive. It is becoming increasingly apparent that enhancing sucrose storage in the culm by molecular means may depend on the modification of the activity of a novel gene target. One possible approach to identify target genes playing crucial coarse regulatory roles in sucrose accumulation is to assess gene expression during the developmental transition of the culm from active growth to maturation. This study has resulted in the successful optimisation of a mRNA hybridisation technique to characterise the expression of 90 carbohydrate metabolism-related genes in three developmentally distinct regions of sugarcane culm. A further goal of this work was to extend the limited knowledge of the regulation of sucrose metabolism in sugarcane, as well as to complement existing data from physiological and biochemical studies. Three mRNA populations derived from the different culm regions were assayed and their hybridisation intensities to the immobilised gene sequences statistically evaluated. The relative mRNA transcript abundance of 74 genes from three differing regions of culm maturity was documented. Genes exhibiting high relative expression in the culm included aldolase, hexokinase, cellulase, alcohol dehydrogenase and soluble acid invertase. Several genes (15) were demonstrated to have significantly different expression levels in the culm regions assessed. These included UDP-glucose pyrophosphorylase and UDP-glucose dehydrogenase, which were down-regulated between immature and mature internodes. Conversely, sucrose phosphate synthase, sucrose synthase and neutral invertase exhibited up-regulation in maturing internodal tissue. A variety of sugar transporters were also found to be up-regulated in mature culm, indicating a possible control point of flux into mature stem sink tissues. Combined with knowledge of the levels of key metabolites and metabolic intermediates this gene expression data will contribute to identifying key control points of sucrose accumulation in sugarcane and assist in the identification of gene targets for future manipulation by transgenic approaches. / AFRIKAANSE OPSOMMING: Ondanks verskeie pogings, waartydens verskeie gene geteiken is, is daar nog weinig sukses behaal om sukrose-akkumulering te verhoog. Toenemend wil dit voorkom asof suksesvolle genetiese manipulering van sukroseberging in die stingel van die verandering van ‘n nuwe geen afhanklik sal wees. Een van die moontlike benaderings wat gevolg kan word om potensiële teiken gene wat ‘n belangrike rol in die beheer van sukrose-opberging speel te identifiseer, is om geen uitdrukkingspatrone in die stingel tydens die omskakeling van aktiewe groei tot volwassenheid te karakteriseer. In hierdie studie is ‘n metode gebaseer op die hibridisering van mRNA geoptimiseer en suksesvol aangewend om die uitdrukkingspatrone van 90 verskillende geselekteerde gene, wat vir sleutelensieme in die beheer van koolhidraatmetabolisme kodeer, te bestudeer. Die doel met die ondersoek was om die beperkte kennis oor die regulering van koolhidraatmetabolisme uit te brei en om die bestaande inligting afgelei van fisiologiese en biochemiese-studies aan te vul. Drie verskillende mRNApopulasies, verkry uit verskillende dele van die stingel, is ontleed deur verskillende peilers te gebruik. Die gegewens is statisties ontleed en dit het afleidings oor die verandering in uitdrukking van hierdie gene moontlik gemaak. Die relatiewe konsentrasies van 74 verskillende gene is gedokumenteer. Gene wat sterk uitgedruk word het aldolase, heksokinase, sellulase, alkoholdehidrogenase en ongebonde suurinvertase ingesluit. Die uitdrukkingspatrone van 15 gene het tussen die verkillende weefsels gevarieer. Gene waarvan die uitdrukking tydens die oorgang na volwassenheid verlaag sluit in UDP-glukose pirofosforilase en UDP-glukose dehidrogenase en waarvan die uitdrukking verhoog sukrosefosfaatsintase, sukrosesintase en neutrale invertase in. Die uitdrukking van verskeie suikertransporter gene verhoog tydens volwassewording. Hierdie inligting te same met die huidige kennis oor heersende metabolietvlakke sal bydrae tot die identifisering van geenteikens vir toekomstige genetiese manupulering.

Bakgrund: Fetma är ett ökande problem i dagens samhälle. Laparoskopiskt Gastric bypass (LGBP) utförs för att hjälpa personer med fetma till viktminskning och det är vanligt att dessa patienter upplever postoperativt illamående, buksmärta och huvudvärk efter ett operativt ingrepp. Det råder meningsskiljaktigheter i tidigare studier hur väl preoperativ näringsdryck kan ha ett samband gällande det postoperativa förloppet.Syfte: Syftet var att jämföra tre olika preoperativa dryckers effekt på postoperativt illamående, buksmärta och huvudvärk efter LGBP under de 24 första timmarna.Metod: En randomiserad studie med kvantitativ design utfördes på en av Nordens största kliniker inom fetmakirurgi. Totalt tillfrågades n=90 kvinnor och tilldelades slutna kuvert med antingen kolhydratdryck, proteindryck eller kranvatten.Resultat: Illamående toppade ca åtta timmar efter operation, det vill säga kl.19.00 på kvällen, för att sedan under natten återgå till preoperativa värden uppmätta kl.06.00. Skillnad mellan kolhydratrik- och proteinberikadryck gav p= 0, 2046 och för kolhydratrikdryck och kranvatten p= 0.8722. Buksmärtan var som högst vid ankomst till uppvakningsavdelningen och stabiliserades två timmar senare och minskade något under natten men försvann inte helt. Huvudvärk låg stabilt i alla grupperna med en ökning runt kl. 19:00 på kvällen för att sedan plana ut under natten. Inga skillnader mellan buksmärta och huvudvärk, p= 0,1569. Det sågs ingen statistisk signifikans hos någon av grupperna i de olika variablerna.Slutsats: Preoperativ vätskebehandling med kolhydratdryck, proteindryck eller kranvatten inför en LGBP operation påverkar inte signifikant illamående, buksmärta och huvudvärk efter operation. / Background: Obesity is a growing problem in today’s society. Laparoscopic Gastric bypass is performed to help people with obesity lose weight and it is common for these patients to experience postoperative nausea, stomach pains, and headaches after a surgical procedure. There are differences in opinion in earlier studies as to the extent that preoperative nutritional beverages can correlate to the postoperative process.Aim: The aim of this paper was to compare three different preoperative beverages’ effect on postoperative nausea, stomach pains, and headaches after LGBP during the first 24 hours after surgery.Method: A randomised study of quantitative design was performed on one of the Nordic countries’ largest clinics specializing in obesity surgery. A total tally of n=90 women were asked to participate and each received sealed packages containing either carbohydrate beverage, protein beverage, or tap water.Results: Nausea peaked eight hours after surgery, at 7.00 PM, and then returned during the night to preoperative values measured at 6.00 AM. The difference between the carbohydrate and protein beverages is expressed as p=0.2046, and the difference between the carbohydrate beverage and the tap water is expressed as p=0.8722. Stomach pains peaked at arrival to the recovery ward and stabilized two hours later, followed by a slight drop-off during the night but without subsiding entirely. Headache was experienced at stable values in all groups, with some increase at 7.00 PM only to level out during the night. There were no differences between stomach pains and headaches, as expressed by p=0.1569. No statistical significance was observed in any group in the different variables.Conclusion: Preoperative fluid treatment with carbohydrate beverages, protein beverages, or tap water before a LGBP surgery does not significantly affect nausea, stomach pain, or headache after the surgery.

The thesis inquires the specific and advantageous applications of Raman optical activity (ROA) in wide range of diverse structural and conformational studies of biomolecules and other biologically important molecules. Our investigation was focused on several interconnected topics covering the fields of methodology, basic and applied research. The combination of experimental and theoretical approaches facilitated deeper understanding of studied phenomena, and allowed for the effects of solute-solvent interactions. High-quality spectra of model molecules in the C-H stretching region, acquired as a result of successful extension of ROA measurements to the whole region of fundamental molecular vibrations, enabled verification and further development of methods for ROA spectra simulations encompassing anharmonic corrections. Utilizing spirodilactams with highly nonplanar amide groups, we have traced the specific ROA spectral manifestations of amide nonplanarity. In case of antimicrobial peptide lasiocepsine, we have successfully simulated ROA signals of S-S stretching vibrations which contrary to current belief do not seem to reflect sense of the S-S group torsion. In larger molecular systems, we have better understood the process of the formation of stable polyproline II conformation and proved that ROA may...

Human erythrocyte glucose sugar transport displays a complexity that is not explained by available models. Sugar transport was examined in resealed red cell ghosts under equilibrium exchange conditions (intracellular [sugar] = extracellular [sugar]). Exchange 3-O-methylglucose (3MG) import and export are monophasic in the absence of cytoplasmic ATP but are biphasic when ATP is present. Biphasic exchange is observed as the rapid filling of a large compartment (66% cell volume) followed by the slow filling of the remaining cytoplasmic space. Two models for biphasic sugar transport are presented in which 3MG must overcome a sugar-specific, physical (diffusional) or chemical (anomerization) barrier to equilibrate with cell water. The anomerization model was rejected through several lines of direct experimental investigation. 1) The sizes of the fast and slow phases of sugar transport do not correlate with the equilibrium anomer distributions of all GLUT1 sugar substrates. 2) Increasing the rate of anomerization by addition of exogenous intracellular mutarotase has no effect on biphasic transport kinetics. 3) Direct measurement of initial rates of sugar uptake or exchange demonstrates that GLUT1 shows no anomer preference. The physical barrier model was further refined by the use of the counterflow condition (intracellular [sugar] >> extracellular [sugar]). The presence of a physical barrier alone was unable to explain the complex counterflow time courses observed. As a result, the model was modified to include the action of a specific sugar export that is compartmentalized from rapidly equilibrating, GLUT1-mediated uptake and exit.

Made available in DSpace on 2016-12-23T13:49:02Z (GMT). No. of bitstreams: 1 Renan Vasconcelos Santos.pdf: 2145055 bytes, checksum: 12d61fee1beb0fbd0b1b459c9f469ff6 (MD5) Previous issue date: 2013-04-02 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Since the dawn of civilization, man has used microbial fermentation to produce various consumer goods. The yeast Saccharomyces cerevisiae is undoubtedly the main factor in known fermentation processes, responsible for the production of bread, beer, wine, cachaça and bioethanol. S. cerevisiae was the first eukaryotic organism to have its genome sequenced and has been used for several decades as a model for eukaryotic cellular and molecular studies. The yeast cell wall is a robust structure composed of a structural internal layer of glucan and chitin, and an outer layer of mannoproteins covalently linked to the structural layer, which determine the bulk properties of the cell surface. The flocculation of yeast can be defined as a non-sexual, reversible and calcium-dependent aggregation of cells in multicellular masses, called flocs, with subsequent sedimentation from the medium in which they are suspended. It is a very complex process and depends on numerous factors such as the characteristics of the medium (pH and the presence of cations), conditions of fermentation (oxygenation, sugars, growth temperature, and the ethanol concentration) and the expression of genes of the FLO family. The process involves the interaction of specialized cell wall proteins called lectins, present only in cell flocculants, and carbohydrates (receptors) in the cell wall of neighboring cells. Flocculation properties specifically set may lead to an improvement in the processing of fermentation biotechnology products, such as food, beverages and biofuels. The group s previous data on the identity of flocculation profile between wild yeast strains isolated from different stills showed two strains with a characteristic profile of sedimentation (BT0510 BT0605), while two others (BT0505 and BT0601) showed no flocculation capacity. The objective of this study was to evaluate the relationship between the content of carbohydrates (glucose and mannose) and cell wall-related genes to the flocculation process in order to better understand the factors that cause the difference in behavior flocculant. Yeast cells were grown in YEPD medium and incubated at 28 ° C and 150 rpm agitation. The cell wall was extracted by a combination of sonication, vigorous agitation with glass beads and boiling in detergent solution. After extensive washing with ultrapure water, the pellet containing the cell wall was incubated at 80 ° C to complete drying and determination of dry weight. Then the samples were subjected to hydrolysis with sulfuric acid, precipitation of sulphate ions by adding Ba (OH) 2, and concentration in vacuum. The liberated monosaccharides were analyzed by HPLC on a column of REZEX-RHM, isocratic elution with ultrapure water, differential refraction detector at 60 ° C. The expression levels of FLO genes and genes related to cell wall between a flocculent strain and a non-flocculent were compared using Real Time PCR. No significant difference was found between the levels of glucose and mannose in flocculent and non-flocculent strains, which suggests that the profile of flocculation is not directly related to the concentration of cell wall carbohydrates. Analysis of relative gene expression showed a significant increase in the FLO gene family (FLO1, FLO8 and FLO10) in flocculant strain, confirming expectations. A large increase of 27 times was noted in CWP1 gene, confirming studies suggesting a major importance of this gene for the cell wall and in the flocculation process. There was also an increase in other genes related to the cell wall. Studies of cell wall proteomics, and mass spectrometry analysis may help elucidate the results, and contribute to a better understanding of flocculation in fermentation processes / Desde os primórdios da civilização, o homem utiliza as fermentações microbianas para a produção de diversos bens de consumo. A levedura Saccharomyces cerevisiae é, sem dúvida, o maior expoente dos processos fermentativos conhecidos, responsável pela fabricação do pão, da cerveja, do vinho cachaça e do bioetanol. S. cerevisiae foi o primeiro organismo eucarionte a ter seu genoma sequenciado e vem sendo utilizada há várias décadas como um modelo eucarionte para estudos celulares e moleculares. A parede celular de levedura é uma robusta estrutura composta por uma camada estrutural interna de glucanos e quitina, e uma camada externa de manoproteínas covalentemente ligadas à camada estrutural, que determinam a maior parte das propriedades de superfície da célula. A floculação de levedura pode ser definida como um processo não sexual, reversível e cálcio-dependente de agregação de células em massas multicelulares, chamadas flocos, com a subsequente sedimentação a partir do meio em que elas estão suspensas. É um processo muito complexo e depende de numerosos fatores, tais como as características do meio (pH e a presença de cátions), as condições de fermentação (oxigenação, os açúcares, a temperatura de crescimento, a concentração de etanol) e a expressão dos genes da família FLO. O processo envolve a interação de proteínas especializadas da parede celular denominadas lectinas, presentes apenas em células floculantes, e carboidratos (receptores) na parede celular das células vizinhas. Propriedades de floculação especificamente ajustadas poderia levar a uma melhoria no processamento de produtos biotecnológicos de fermentação, tais como alimentos, bebidas e biocombustíveis. Dados anteriores do grupo sobre a identificação do perfil de floculação entre cepas selvagens de levedura isoladas de diferentes alambiques mostraram duas cepas com um perfil característico de sedimentação (BT0510 e BT0605), enquanto outras duas (BT0505 e BT0601) sem capacidade de floculação. Assim, o objetivo deste trabalho foi avaliar a relação entre o conteúdo de carboidratos (glicose e manose) da parede celular e de genes relacionados à parede com o processo da floculação, a fim de melhor entender os fatores que causam a diferença no comportamento floculante. As células de levedura foram cultivadas em meio YEPD, incubadas a 28 ºC e 150 rpm de agitação. A parede celular foi extraída por combinação de sonicação, agitação vigorosa com pérolas de vidro e de ebulição em solução detergente. Após lavagem extensiva com água ultra pura, o pellet contendo a parede celular foi incubado a 80 ºC para secagem completa e determinação do peso seco. Em seguida, as amostras foram submetidas a uma hidrólise com ácido sulfúrico, precipitação de íons sulfato por adição de Ba(OH)2, e concentração a vácuo. Os monossacarídeos liberados foram analisados por HPLC na coluna REZEX-RHM, eluição isocrática com água ultra pura, detector de refração diferencial a 60 ºC. Por PCR em Tempo Real foram comparados os níveis de expressão dos genes FLO e de genes relacionados à parede celular entre uma cepa floculante e outra não-floculante. Não foi encontrada diferença significativa entre o teor de glicose e manose nas cepas floculantes e não floculantes, o que sugere que o perfil de floculação não está diretamente relacionado com a concentração de carboidratos de parede celular. A análise da expressão gênica relativa mostrou um aumento significativo dos genes da família FLO (FLO1, FLO8 e FLO10) na cepa floculante, confirmando as expectativas. Um grande aumento, de 27 vezes, foi observado no gene CWP1, corroborando com estudos que sugerem uma grande importância deste gene para a integridade da parede celular e para o processo de floculação. Também houve aumento de outros genes relacionados à parede celular. Estudos de proteômica da parede celular, além de análise em espectrometria de massas poderiam ajudar a elucidar os resultados encontrados, e contribuir para o melhor entendimento da floculação nos processos fermentativos