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Salivary proteins such as statherin (STN) are known to be involved in enamel de/remineralisation, the inhibition of crystal growth, and spontaneous precipitation of calcium phosphate salts. The active N-terminal of STN (STN21) is involved in binding with Ca2+ and in reducing HA demineralisation. In addition, salivary Histatin-1 (HTN) inhibits crystal growth of calcium phosphate salts but does not inhibit their spontaneous precipitation. These salivary peptides do not occur as individual molecules in saliva, they are part of a complex salivary system. The aims were to investigate the effect of salivary STN, HTN and their 21 N-terminal peptides (STN21, and HTN21) individually and when in combination on the demineralisation rates of HA and enamel using scanning microradiography. In addition, to understand their effect on HA and enamel demineralisation, peptide adsorption onto HA and enamel was measured spectrophotometrically. Also, peptide aggregation, surface charge and, conformation in solution were investigated. The adsorption and demineralisation reduction of non-human STN was also investigated. STN, HTN and STN21 individually showed similar adsorption and demineralisation reduction efficacy in HA but not in enamel. HTN21 showed the lowest demineralisation reduction of all peptides. STN21 when in combination with either HTN, or HTN21, showed the greatest demineralisation reduction of all peptides. The increase in peptides demineralisation reduction efficacy when in combination suggests co-operative efficacy, which is further increased with the removal of the C-terminal. All individual peptides were found to adopt an α-helical conformation at the N-terminal, which is important in peptide adsorption onto HA surfaces. When in combination conformational changes led to peptide interaction and caused an increase in their net negative charges. In conclusion, it was found that the degree to which demineralisation is reduced by peptides is correlated with the amount of peptide adsorbed.

This study investigated some functional and biochemical characteristics of a bacteriolytic protein in the salivary glands of adult Aedes aecupti. A method for the isolation of this protein from other mosquito salivary gland components is also described. Based on some of its biochemical properties, this bacteriolytic protein can be classified as a lysozyme. This protein is strongly-linked to mosquito sugarfeeding activity because there is a statistically significant (P < 0.05) increase in the levels of lytic activity six hours before mosquitoes start to sugar feed. By its bacteriolytic action, it may function as a protective mechanism against bacteria-contaminated sugar meals. Preliminary work suggests that mosquitoes exposed to lyophilized Micrococcus lysodeikticus in their sugar meal respond by increasing the lytic activity in their salivary glands. The levels of bacteriolytic activity are apparently not affected by bloodfeeding. In the absence of feeding, as in teneral and bloodfed mosquitoes, salivary bacteriolytic activity increases to a maximum, then levels off. This suggests a regulation of the synthesis of this salivary protein that is independent of the feeding state of the adult mosquito. A combination of centrifugation, polyacrylamide gel electrophoresis (non-denaturing and denaturing), cation exchange chromatography and gel filtration, was used to isolate the protein from other mosquito salivary gland components. This salivary protein is lysozyme-like in several aspects: 1) it lyses bacterial cell walls of M. lysodeikticus, 2) it is a basic protein with a pI between 7.47 and 8.89, 3) it is thermostable at low pH, and loses its activity at high pH, and 4) it is composed of one polypeptide chain. Its molecular weight is twice that of hen egg white lysozyme. This salivary bacteriolytic protein is the first insect exocrine lysozyme to be characterized. / Graduation date: 1992

Thesis (M. Sc.)(Biochemistry)--University of Pretoria, 2008. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (Ph.D.)(Biochemistry)--University of Pretoria, 2005. / Title from opening screen (viewed March 28, 2006). Includes summary. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 197-209).

A obesidade à um tema recorrente na literatura cientÃfica da atualidade. Isso se deve ao aumento exponencial de sua prevalÃncia em todas as camadas da sociedade. A popularidade deste tema fez tambÃm com que assuntos associados a ele emergissem e ganhassem maior notabilidade em publicaÃÃes da Ãrea da saÃde. O uso da saliva como mÃtodo diagnÃstico avanÃou consideravelmente nos Ãltimos anos. DesequilÃbrios na quantidade e na qualidade da saliva podem tanto gerar afecÃÃes bucais quanto ser indicativo de alguma alteraÃÃo sistÃmica importante. Este trabalho objetivou estudar o perfil de proteÃnas salivar e saliva total humana em pacientes com sobrepeso e obesidade. A amostra foi constituÃda por sessenta pacientes com obesidade e sobrepeso (grupo experimental) e sessenta pacientes com peso adequado (grupo controle), tendo sido avaliado o fluxo salivar, o diÃrio de dieta e o perfil proteico. Saliva total nÃo estimulada foi coletada e armazenada a â 80ÂC. Posteriormente foi adicionado o inibidor enzimÃtico e as amostras foram centrifugadas a 15.000 rpm por 15 minutos a 4ÂC, sendo o sobrenadante separado para realizaÃÃo da dosagem de proteÃnas. A concentraÃÃo de proteÃnas totais salivares foi determinada pelo mÃtodo do Ãcido BicinconÃnico, usando uma curva de albumina sÃrica bovina (BSA). Ao analisar o fluxo salivar nÃo estimulado foi possÃvel observar que o grupo de estudo apresentou mÃdia menor que o grupo controle, sendo essa diferenÃa estatisticamente significante (p=0,006). O grupo controle apresentou uma mÃdia de concentraÃÃo total de proteÃnas maior que o grupo experimental, sendo essa diferenÃa estatisticamente significante (p=0,002). Os resultados deste estudo sugerem haver padrÃes diferenciados na composiÃÃo salivar entre os grupos avaliados.

A picnodisostose à uma displasia esquelÃtica caracterizada por baixa estatura, osteoclerose, acrosteÃlise, deformidades crÃnio-faciais e fragilidade Ãssea. Aproximadamente 200 casos foram descritos em diferentes grupos Ãtnicos, estimando-se uma incidÃncia de 1,7: 1.000.0000 de nascidos. O uso da saliva como um mÃtodo de diagnÃstico avanÃou exponencialmente nos Ãltimos anos. DesequilÃbrios na quantidade e composiÃÃo da saliva podem gerar afecÃÃes bucais tais como cÃries e doenÃa periodontal, alÃm de ser indicativo de alteraÃÃo sistÃmica importante. Esse trabalho objetivou estudar parÃmetros de saliva total humana em pacientes portadores de picnodisostose (PYCN). A amostra consistiu em 04 indivÃduos com PYCN (grupo experimental) e 04 indivÃduos nÃo-sindrÃmicos (grupo controle), tendo sido avaliado fluxo salivar, pH e perfil protÃico. Saliva total nÃo estimulada foi coletada e centrifugada; o sobrenadante foi retido, liofilizado, armazenado a -20ÂC e analisado para contagem de proteÃnas totais e eletroforese bidimensional. Foi possÃvel detectar diferenÃas estatisticamente significativas entre os grupos (p<0,05) para os parÃmetros salivares analisados. Quando comparados com o grupo controle, portadores de PYCN apresentaram reduÃÃo no fluxo salivar; pH com valores aumentados; reduÃÃo na concentraÃÃo total de proteÃnas e bandas protÃicas com expressÃo diferenciadas. Os resultados desse estudo sugerem haver padrÃes diferenciados na composiÃÃo salivar entre os grupos avaliados. / Picnodysostosis (PKND) is a skeletal displasia characterized by short stature, osteosclerosis, acrosteolisis, craniofacial deformities and bone fragility. Approximately 200 cases have been described among different ethnic groups, with an estimated incidence of 1.7: 1.000.000 live births. The use of saliva as a diagnostic tool has advanced exponentially within recent years. Unbalance in the amount and composition of saliva may generate oral diseases such as dental caries and periodontitis, and may also indicate important systemic alterations. This study has aimed to investigate the parameters of human whole saliva in patients with PKND. Our study sample consisted of 4 individuals with PKND (experimental group) and 4 healthy individuals without PKND (control group). Salivary flow rate, pH and protein profile were evaluated in this population. Non stimulated whole saliva was collected and centrifuged. The supernatant was separated and lyophilized and stored at -20ÂC for posterior total protein and bidimensional electroforetic analysis. Statistically significant differences were observed between groups (p<0,05) for the analyzed salivary parameters. When compared to the control group, individuals with PKND presented reduced salivary flow rate, lower pH values, reduced total protein concentration, and protein bands with differentiated expression. The results of this study suggest the existence of a differentiated pattern of salivary composition between groups.

Please read the abstract in the section 00front of this document / Thesis (PhD (Biochemistry))--University of Pretoria, 2002. / Biochemistry / unrestricted

Master of Science / Department of Chemistry / Christopher T. Culbertson / The study of aphid salivary secretome has practical importance on understanding interactions of aphids and their host plants. Around 250 species of aphids out of the identified 4000 aphid species are considered as serious pests. The experiments were performed with pea aphids (Acyrthosiphon pisum) that were feeding on bean plants (Vivia fabe). Pea aphids feed on plant phloem sap by probing their stylet into the sieve elements of the plant and secreting saliva for external digestion. In order to collect aphid salivary proteins from the secreted saliva, small scale and large scale sample collection methods were carried out. The small scale sample method was performed in microfluidic devices using 10-25 aphids. Aphids were able to feed on the artificial diet by probing through a stretched ParafilmTM and survived for 2-3 days in the microfluidic devices. The experiments proved that the aphid survival and feeding rate could be improved with the factors such as ventilation, light intensity and increasing diet volume. However it was difficult to collect sufficient amounts of aphid saliva for detection using small scale devices. The large scale sample collection method was performed by feeding 8000 aphids in large screened chamber for 24/48h. The collected salivary samples after undergone a concentration process was capable of collecting detectable aphid salivary secretions. The experimental conditions were adjusted to obtain optimized HPLC separations. Finally, LC/MS/MS followed by peptide sequence database searching were able to identify potential aphid salivary proteins.