Spoilage and the presence of pathogens, such as Listeria monocytogenes and Salmonella, are among the most common reasons for shrimp product detentions and recalls. In addition, both listeriosis and salmonellosis have been associated with the consumption of shrimp. For these reasons, there is interest in reducing Listeria and Salmonella contamination of shrimps. A review of literature indicated no detailed study that described the attachment of Listeria and Salmonella onto shrimps and their resulting persistence. In addition, information related to the control of these two pathogens on fresh shrimps is also limited. The work reported in this thesis aims to partially fill these gaps. These aims were met through four studies. In the first study, the initial attachment and colonization of Listeria and Salmonella onto fresh and cooked shrimp carapaces and tissue was examined. The chitinolytic activity and the physicochemical properties namely cellular surface charge (CSC), hydrophobicity and electron donor/acceptor potential were also determined for all the strains. CSC was determined using zeta potential measurements. Hydrophobicity was determined using three hydrophobicity determination methods, while microbial adhesion to solvents was used to determine the electron donor/acceptor potential. Attachment and colonization of Listeria and Salmonella were demonstrated. Abdominal carapaces showed higher levels of bacterial attachment (p<0.05) than head carapaces while Listeria consistently exhibited greater attachment (p<0.05) than Salmonella on all surfaces. Chitinase activity of all strains was tested and found not to occur at the three temperatures (10°, 25° and 37°C) tested. Salmonella had significantly (p<0.05) more positive CSC than Listeria. A significant difference (p<0.05) in surface roughness between abdominal and head carapaces was noted. From the results obtained, it is possible to conclude that certain bacterial physicochemical properties and carapace roughness were involved in the attachment to carapaces but not attachment to tissue or colonization to carapace and tissue. The influence of attachment and colonization of Listeria and Salmonella onto shrimp surfaces on the resistance against environmental stress was investigated in the second study. Planktonic, attached and colonized cells of Listeria and Salmonella were challenged with high (50°, 60° and 70°C) and low (4°C) temperature, 100 ppm sodium hypochlorite solution, and acetic, hydrochloric and lactic acids (pH 4.0). Attached and colonized Listeria and Salmonella showed significantly greater (p<0.05) resistance to heat (~1.3-2.6 fold increase in D-values), hypochlorite (~6.6->40.0 fold) and acids (~4.0-9.0 fold) than their planktonic counterparts. There were no significant differences (p>0.05) in the survival of planktonic, attached or colonized cells of Listeria and Salmonella stored under refrigerated conditions. The increase in resistance observed in attached and colonized cells could have an important implication for shrimp product’s safety in general. In the third study, bilimbi (Averrhoa bilimbi L.) and tamarind (Tamarindus indica L.) juices were used to reduce Listeria monocytogenes Scott A and Salmonella Typhimurium ATCC 14028 populations on raw shrimps after washing and during storage (4ºC). The uninoculated raw shrimps and those inoculated with L. monocytogenes Scott A and S. Typhimurium ATCC 14028 were washed (dipped or rubbed) in sterile distilled water (SDW) (control), bilimbi or tamarind juice. Naturally occurring aerobic bacteria (APC), L. monocytogenes Scott A and S. Typhimurium ATCC 14028 counts of washed shrimps were determined on days 0, 3 and 7 of storage. Compared to SDW, bilimbi and tamarind juice significantly (p<0.05) reduced APC, L. monocytogenes Scott A and S. Typhimurium ATCC 14028 numbers on day 0. There was a significant difference (p<0.05) in bacterial reduction between the dipping and rubbing methods. Regardless of washing treatments or methods, populations of S. Typhimurium ATCC 14028 decreased slightly while populations of L. monocytogenes Scott A and APC increased significantly during refrigerated storage. These results suggest that consumable household items could be adopted as a natural method of decontaminating shrimps just before preparation and consumption. In the final study, use of nisin alone and in combinations with EDTA and salts of organic acids (potassium sorbate, sodium benzoate, or sodium diacetate) to control L. monocytogenes, Salmonella and native microflora on fresh shrimps were evaluated. Uninoculated, and Listeria monocytogenes or Salmonella inoculated, shrimps were dipped in treatment solutions, vacuum packaged and stored at 4ºC for 7 days. Listeria monocytogenes, Salmonella and native microflora counts were determined on days 0, 3 and 7. Nisin-EDTA-potassium sorbate and nisin-EDTA-sodium diacetate significantly reduced (p<0.05) L. monocytogenes numbers by 0.94-1.20 and 1.07-1.29 log CFU/g respectively, as compared to the control. All treatments failed to reduce (p>0.05) Salmonella counts on shrimps. At the end of storage, the native microflora counts on all nisin-EDTA-organic acids salts treated shrimps were significantly lower (p<0.05) than the control. The results suggest that some of the treatments can be used to improve shrimp microbial safety and shelf-life. Through achieving the aforementioned aims the present thesis was able to enhance the knowledge and literature available concerning the initial attachment of Listeria and Salmonella on shrimps, their persistence as well as methods to control them

abstract: This thesis presents a novel, thorough approach to the application of low frequency electromagnetic (EM) wave wireless communication in marine environment. This investigation is both theoretical and experimental, and is oriented towards marine sensor network applications. Different solutions within the underwater low frequency EM communication area are compared on the basis of their feasibility and practicality, especially in relation to scientific environmental monitoring applications. As a result, this thesis gathers a coordinated series of application oriented analyses of devices, such as antennas, transmitters, receivers, and of propagation issues, like signal attenuation and antenna positioning. The concluding step in this analysis is constituted by experimental field tests. As a final outcome, this works provides facts, guidelines and prototype designs related to the application of EM communication in shallow water environment, and demonstrates this communication technique is convenient for shallow water sensor networks implementation. The process followed in this analysis starts from practical considerations regarding the characteristics required by scientific equipment used in environmental monitoring. A case study is presented where a hybrid (partially wired) marine sensor network is deployed in Moreton Bay, Queensland. Strengths and weaknesses of this system are analysed, and, based on this experience, new requirements and constraints are set for a prospective improved fully wireless sensor network. In particular, the shallow water marine environment is recognized as the most likely target for scientific investigation because of its biological, economical and social importance. Firstly, various underwater communication techniques are analysed and compared. This is done on the basis of two factors: the first one is the final use of the sensor network, and the second one is the peculiar nature of the shallow water marine environment. From this analysis, it emerges that EM communication may be, in the shallow water environment, a viable and good alternative to acoustic- and optical-based techniques. From this point on, this work is aimed to prove this possibility. The next step undertaken is the theoretical analysis of EM propagation in the shallow water environment, which is modelled as a stratified lossy dielectric. The outcome of theoretical calculations is that, within a certain distance, and for a given transmitter power, low frequency EM waves are a communication channel exploitable by underwater wireless sensor networks. This is particularly true when the required data rate is low, as it is in the case of monitoring variables such as temperatures or concentrations of dissolved substances in the sea. Following this, the electric dipole and the loop antenna are studied and compared when immersed in a lossy medium such as seawater. In particular, the comparison is drawn in terms of antenna size, with absorbed power and radiated field level held equal. This, together with other practical considerations, allows the choice of the electric dipole – with some variations with respect to free space applications – as the preferred transmitting and receiving antenna. Theoretical results are verified and completed by simulations, and final prototype design guidelines are presented, together with best deployment practice suggestions. Finally, measurements are conducted in order to verify the previous calculations and considerations. In addition to them, a sensor network prototype that uses EM underwater communication is presented and tested. The field tests verify, in a real situation and at several frequencies, the maximum distance coverable with a 100 mW power source. Moreover, the same test is also conducted in fresh water, and results are compared. The instruments used for the measurements are thoroughly described, as it is the wireless sensor prototype presented. The main feature of this design is its simplicity, demonstrating that shallow water EM communication is easily achievable and that it meets the standards required by a local area marine sensor network. It can be concluded that this work offers a thorough theoretical analysis of EM propagation in shallow water environment: in parallel with this, a synthesis of practical issues that are encountered in the design of EM communication devices for underwater sensor networks is also presented. In particular, EM underwater propagation, antennas, transmitters and receiver circuits and deployment issues are thoroughly covered. Aspects such as the application of advanced signal modulations and communication protocols, however, are intentionally left open to further investigation. In fact, the range of research topics opened by this work is very wide, and they could not be all covered within this work: they span from energy harvesting to communication protocols, from antenna design to power management. All these areas are well covered by literature for terrestrial sensor networks, but they are not covered for underwater sensor networks that use EM communication: these latter are, in fact, a novelty by themselves. The problems related to this particular application have been, therefore, thoroughly exposed and opened to future research.

abstract: This thesis presents a novel, thorough approach to the application of low frequency electromagnetic (EM) wave wireless communication in marine environment. This investigation is both theoretical and experimental, and is oriented towards marine sensor network applications. Different solutions within the underwater low frequency EM communication area are compared on the basis of their feasibility and practicality, especially in relation to scientific environmental monitoring applications. As a result, this thesis gathers a coordinated series of application oriented analyses of devices, such as antennas, transmitters, receivers, and of propagation issues, like signal attenuation and antenna positioning. The concluding step in this analysis is constituted by experimental field tests. As a final outcome, this works provides facts, guidelines and prototype designs related to the application of EM communication in shallow water environment, and demonstrates this communication technique is convenient for shallow water sensor networks implementation. The process followed in this analysis starts from practical considerations regarding the characteristics required by scientific equipment used in environmental monitoring. A case study is presented where a hybrid (partially wired) marine sensor network is deployed in Moreton Bay, Queensland. Strengths and weaknesses of this system are analysed, and, based on this experience, new requirements and constraints are set for a prospective improved fully wireless sensor network. In particular, the shallow water marine environment is recognized as the most likely target for scientific investigation because of its biological, economical and social importance. Firstly, various underwater communication techniques are analysed and compared. This is done on the basis of two factors: the first one is the final use of the sensor network, and the second one is the peculiar nature of the shallow water marine environment. From this analysis, it emerges that EM communication may be, in the shallow water environment, a viable and good alternative to acoustic- and optical-based techniques. From this point on, this work is aimed to prove this possibility. The next step undertaken is the theoretical analysis of EM propagation in the shallow water environment, which is modelled as a stratified lossy dielectric. The outcome of theoretical calculations is that, within a certain distance, and for a given transmitter power, low frequency EM waves are a communication channel exploitable by underwater wireless sensor networks. This is particularly true when the required data rate is low, as it is in the case of monitoring variables such as temperatures or concentrations of dissolved substances in the sea. Following this, the electric dipole and the loop antenna are studied and compared when immersed in a lossy medium such as seawater. In particular, the comparison is drawn in terms of antenna size, with absorbed power and radiated field level held equal. This, together with other practical considerations, allows the choice of the electric dipole – with some variations with respect to free space applications – as the preferred transmitting and receiving antenna. Theoretical results are verified and completed by simulations, and final prototype design guidelines are presented, together with best deployment practice suggestions. Finally, measurements are conducted in order to verify the previous calculations and considerations. In addition to them, a sensor network prototype that uses EM underwater communication is presented and tested. The field tests verify, in a real situation and at several frequencies, the maximum distance coverable with a 100 mW power source. Moreover, the same test is also conducted in fresh water, and results are compared. The instruments used for the measurements are thoroughly described, as it is the wireless sensor prototype presented. The main feature of this design is its simplicity, demonstrating that shallow water EM communication is easily achievable and that it meets the standards required by a local area marine sensor network. It can be concluded that this work offers a thorough theoretical analysis of EM propagation in shallow water environment: in parallel with this, a synthesis of practical issues that are encountered in the design of EM communication devices for underwater sensor networks is also presented. In particular, EM underwater propagation, antennas, transmitters and receiver circuits and deployment issues are thoroughly covered. Aspects such as the application of advanced signal modulations and communication protocols, however, are intentionally left open to further investigation. In fact, the range of research topics opened by this work is very wide, and they could not be all covered within this work: they span from energy harvesting to communication protocols, from antenna design to power management. All these areas are well covered by literature for terrestrial sensor networks, but they are not covered for underwater sensor networks that use EM communication: these latter are, in fact, a novelty by themselves. The problems related to this particular application have been, therefore, thoroughly exposed and opened to future research.

Bovine herpesvirus-1 (BoHV-1) is an important pathogen of cattle associated with respiratory and reproductive disease and is the most common viral agent implicated in the bovine respiratory disease complex (BRDC). BRDC is an economically significant multifactorial disease of feedlot cattle estimated to cost Australian feedlot producers $AU60 million/year in lost production, therapeutics and disease management. Worldwide BRDC is attributed to cost $US2 billion to cattle industries. In an effort to limit the associated economic costs and enhance animal health and welfare of feedlot cattle, the concerted use of vaccination and diseased animal management are practiced. Numerous vaccines are available in North America and Canada however, in Australia, feedlot producers are reliant on three vaccines. These vaccines target either the bacterial or viral agents of the BRDC and encompass antibody, subunit and attenuated live BoHV-1 preparations. Live attenuated vaccines are developed by numerous methods including, deletion or disruption of certain genes. The development of an attenuated live virus vaccine was traditionally a laborious task requiring numerous rounds of in vitro purification. Contrastingly, technological advances introduced this decade, allowing the stable maintenance of the complete herpesvirus genome in bacteria as a bacterial artificial chromosome (BAC), has advanced herpes virology exponentially in that investigation and manipulation of the herpesvirus genome can be conducted independent of a cell culture system. With respect to BRDC and the generation of vaccines to combat the disease, the tools to fully utilise the potential of BoHV-1 as a live vaccine vector are now routine. It is now possible to vii construct BoHV-1 as a delivery vector by inserting appropriate antigens of those bacterial and viral pathogens implicated in the BRDC into a BAC maintained BoHV-1 genome. However, there is a significant lack of genetic information regarding BoHV-1 and inserting several antigenic sequences would expand the genome of BoHV-1 inducing non-viability. Therefore, to further develop BoHV-1 as a vaccine vector, a study was conducted to identify the essential and nonessential genes required for the in vitro viability of BoHV-1. Identifying the essential and nonessential genes will establish which genes may be preferentially deleted or replaced with exogenous antigenic sequences in a BoHV-1 derived vaccine vector. To define the requirement of genes encoded by BoHV-1, random-insertion mutagenesis utilising a Tn5 transposition system and targeted gene deletion catalysed by GET recombination was employed to construct gene disruption and gene deletion libraries, respectively, of an infectious clone of BoHV-1. Transposon insertion position and confirmation of gene deletion was determined by direct sequencing. with the essential or nonessential requirement of either transposed or deleted open reading frames (ORFs) assessed by transfection of respective BoHV- 1 BAC DNA into host cells. Of the 73 recognised ORFs encoded by the BoHV-1 genome, 33 were determined to be essential and 36 to be nonessential for virus viability in cell culture with the requirement of the two dual copy ORFs inconclusive. The majority of ORFs were shown to conform to the in vitro requirements of BoHV-1 homologues encoded by Human herpesvirus 1. However, ORFs encoding for glycoprotein K (UL53), regulatory, membrane, tegument and capsid proteins (UL54, UL49.5, UL49, UL35, UL20, UL16 and UL7) were shown to differ in requirement when compared to Human herpesvirus-1 encoded homologues. Further analysis of clones encompassing restriction digestion profiling, one-step growth and replication kinetic analysis defined the genetic constitution and replicative capacity of the mutant clones. Thirty-three individual ORFs of the 36 defined nonessential ORF were identified as being amenable to deletion without causing significant replicative detriment to a potential BoHV-1 vaccine vector. This study has provided the foundational information required for the future development of BoHV-1 as a multivalent vaccine vector for the protection of feedlot cattle from BRDC. Furthermore, the genetic information generated in this study contributes to the general knowledge of the prototype ruminant herpesvirus, BoHV-1, and contributes to the comparative study of gene function between the large and diverse family that is Herpesviridae.

Bovine herpesvirus-1 (BoHV-1) is an important pathogen of cattle associated with respiratory and reproductive disease and is the most common viral agent implicated in the bovine respiratory disease complex (BRDC). BRDC is an economically significant multifactorial disease of feedlot cattle estimated to cost Australian feedlot producers $AU60 million/year in lost production, therapeutics and disease management. Worldwide BRDC is attributed to cost $US2 billion to cattle industries. In an effort to limit the associated economic costs and enhance animal health and welfare of feedlot cattle, the concerted use of vaccination and diseased animal management are practiced. Numerous vaccines are available in North America and Canada however, in Australia, feedlot producers are reliant on three vaccines. These vaccines target either the bacterial or viral agents of the BRDC and encompass antibody, subunit and attenuated live BoHV-1 preparations. Live attenuated vaccines are developed by numerous methods including, deletion or disruption of certain genes. The development of an attenuated live virus vaccine was traditionally a laborious task requiring numerous rounds of in vitro purification. Contrastingly, technological advances introduced this decade, allowing the stable maintenance of the complete herpesvirus genome in bacteria as a bacterial artificial chromosome (BAC), has advanced herpes virology exponentially in that investigation and manipulation of the herpesvirus genome can be conducted independent of a cell culture system. With respect to BRDC and the generation of vaccines to combat the disease, the tools to fully utilise the potential of BoHV-1 as a live vaccine vector are now routine. It is now possible to vii construct BoHV-1 as a delivery vector by inserting appropriate antigens of those bacterial and viral pathogens implicated in the BRDC into a BAC maintained BoHV-1 genome. However, there is a significant lack of genetic information regarding BoHV-1 and inserting several antigenic sequences would expand the genome of BoHV-1 inducing non-viability. Therefore, to further develop BoHV-1 as a vaccine vector, a study was conducted to identify the essential and nonessential genes required for the in vitro viability of BoHV-1. Identifying the essential and nonessential genes will establish which genes may be preferentially deleted or replaced with exogenous antigenic sequences in a BoHV-1 derived vaccine vector. To define the requirement of genes encoded by BoHV-1, random-insertion mutagenesis utilising a Tn5 transposition system and targeted gene deletion catalysed by GET recombination was employed to construct gene disruption and gene deletion libraries, respectively, of an infectious clone of BoHV-1. Transposon insertion position and confirmation of gene deletion was determined by direct sequencing. with the essential or nonessential requirement of either transposed or deleted open reading frames (ORFs) assessed by transfection of respective BoHV- 1 BAC DNA into host cells. Of the 73 recognised ORFs encoded by the BoHV-1 genome, 33 were determined to be essential and 36 to be nonessential for virus viability in cell culture with the requirement of the two dual copy ORFs inconclusive. The majority of ORFs were shown to conform to the in vitro requirements of BoHV-1 homologues encoded by Human herpesvirus 1. However, ORFs encoding for glycoprotein K (UL53), regulatory, membrane, tegument and capsid proteins (UL54, UL49.5, UL49, UL35, UL20, UL16 and UL7) were shown to differ in requirement when compared to Human herpesvirus-1 encoded homologues. Further analysis of clones encompassing restriction digestion profiling, one-step growth and replication kinetic analysis defined the genetic constitution and replicative capacity of the mutant clones. Thirty-three individual ORFs of the 36 defined nonessential ORF were identified as being amenable to deletion without causing significant replicative detriment to a potential BoHV-1 vaccine vector. This study has provided the foundational information required for the future development of BoHV-1 as a multivalent vaccine vector for the protection of feedlot cattle from BRDC. Furthermore, the genetic information generated in this study contributes to the general knowledge of the prototype ruminant herpesvirus, BoHV-1, and contributes to the comparative study of gene function between the large and diverse family that is Herpesviridae.

Adiponectin is an adipose-derived protein (adipocytokine) that is secreted by adipose tissue. It has insulin-sensitizing, anti-inflammatory and cardio-protective properties, and is thought to be protective against obesity-related diseases such as type 2 diabetes. Humans and cats are two species that commonly develop type 2 diabetes associated with insulin resistance, impaired beta cell function and spontaneous islet amyloid deposition. The domestic cat (Felis catus) has recently been proposed as an animal model for human type 2 diabetes. However, little is known about the physiology of adiponectin in cats. Therefore, we set out to investigate the association of adiponectin profiles with dietary carbohydrate intake, feeding, body weight, fat mass, and insulin sensitivity in healthy young adult cats (n=32; 2-4 years old; gender ratio 1:1; body condition 4-5/9). Cats were fed a moderate carbohydrate diet (37% ME) at maintenance energy requirements for four weeks. Cats were then assigned to either receive a low (19% ME) or high (52% ME) carbohydrate diet and fed at maintenance energy requirements for another four weeks, followed by ad-libitum feeding for eight weeks to facilitate weight gain. Adiponectin profiles including total circulating adiponectin and its distribution [low molecular weight (LMW) and high molecular weight (HMW) adiponectin], and proportion of adiponectin that is HMW (SA) were measured by ELISA and velocity sedimentation using sucrose gradients, followed by Western blotting, respectively. We demonstrated inter-animal variation in total adiponectin concentration at baseline (0.6 to 15.0 g/mL), with the adiponectin present in both LMW and HMW forms. Feeding with a high carbohydrate diet for four weeks at maintenance energy requirements resulted in increased total adiponectin concentration, which was associated with an increased concentration of LMW adiponectin. In contrast, feeding with a low carbohydrate diet for four weeks at maintenance energy requirements resulted in increased concentration of HMW adiponectin, decreased LMW adiponectin concentration, and increased SA, without a change in total adiponectin concentration. In cats fed the high carbohydrate diet, total adiponectin and HMW adiponectin concentrations become lower at six hours after feeding, as compared to the fasting concentrations. This phenomenon was not observed in cats fed a low carbohydrate diet, indicating a diet-dependent postprandial effect. There was no effect of gender on any of the adiponectin profiles in cats. Unlike other studies in humans and mice in which adiponectin concentrations decreased as fat mass increased, our data indicate that a moderate weight gain achieved by ad libitum feeding of a low carbohydrate diet for eight weeks correlated with increased adiponectin concentrations. Total adiponectin concentration (mirrored by HMW adiponectin) was positively correlated with body weight gain and fat mass gain (but not absolute fat mass) in our overweight cats. Furthermore, the fat mass-related increases in plasma adiponectin over eight weeks correlated with insulin sensitivity (higher adiponectin concentration corresponded to greater insulin sensitivity in overweight cats). These data hint at the possibility that in overweight animals, adiponectin is similar to other adipokines that rise concomitantly with increased of moderate fat mass gain and thus increases insulin sensitivity. Overall, the knowledge in this study therefore provides useful information to veterinarians and cat food manufacturers, and forms a foundation for future studies to extend our knowledge of adiponectin in cats. Data gathered in cats may also be applicable to humans and could therefore inform research using cats as an animal model of human obesity and type 2 diabetes.

Adiponectin is an adipose-derived protein (adipocytokine) that is secreted by adipose tissue. It has insulin-sensitizing, anti-inflammatory and cardio-protective properties, and is thought to be protective against obesity-related diseases such as type 2 diabetes. Humans and cats are two species that commonly develop type 2 diabetes associated with insulin resistance, impaired beta cell function and spontaneous islet amyloid deposition. The domestic cat (Felis catus) has recently been proposed as an animal model for human type 2 diabetes. However, little is known about the physiology of adiponectin in cats. Therefore, we set out to investigate the association of adiponectin profiles with dietary carbohydrate intake, feeding, body weight, fat mass, and insulin sensitivity in healthy young adult cats (n=32; 2-4 years old; gender ratio 1:1; body condition 4-5/9). Cats were fed a moderate carbohydrate diet (37% ME) at maintenance energy requirements for four weeks. Cats were then assigned to either receive a low (19% ME) or high (52% ME) carbohydrate diet and fed at maintenance energy requirements for another four weeks, followed by ad-libitum feeding for eight weeks to facilitate weight gain. Adiponectin profiles including total circulating adiponectin and its distribution [low molecular weight (LMW) and high molecular weight (HMW) adiponectin], and proportion of adiponectin that is HMW (SA) were measured by ELISA and velocity sedimentation using sucrose gradients, followed by Western blotting, respectively. We demonstrated inter-animal variation in total adiponectin concentration at baseline (0.6 to 15.0 g/mL), with the adiponectin present in both LMW and HMW forms. Feeding with a high carbohydrate diet for four weeks at maintenance energy requirements resulted in increased total adiponectin concentration, which was associated with an increased concentration of LMW adiponectin. In contrast, feeding with a low carbohydrate diet for four weeks at maintenance energy requirements resulted in increased concentration of HMW adiponectin, decreased LMW adiponectin concentration, and increased SA, without a change in total adiponectin concentration. In cats fed the high carbohydrate diet, total adiponectin and HMW adiponectin concentrations become lower at six hours after feeding, as compared to the fasting concentrations. This phenomenon was not observed in cats fed a low carbohydrate diet, indicating a diet-dependent postprandial effect. There was no effect of gender on any of the adiponectin profiles in cats. Unlike other studies in humans and mice in which adiponectin concentrations decreased as fat mass increased, our data indicate that a moderate weight gain achieved by ad libitum feeding of a low carbohydrate diet for eight weeks correlated with increased adiponectin concentrations. Total adiponectin concentration (mirrored by HMW adiponectin) was positively correlated with body weight gain and fat mass gain (but not absolute fat mass) in our overweight cats. Furthermore, the fat mass-related increases in plasma adiponectin over eight weeks correlated with insulin sensitivity (higher adiponectin concentration corresponded to greater insulin sensitivity in overweight cats). These data hint at the possibility that in overweight animals, adiponectin is similar to other adipokines that rise concomitantly with increased of moderate fat mass gain and thus increases insulin sensitivity. Overall, the knowledge in this study therefore provides useful information to veterinarians and cat food manufacturers, and forms a foundation for future studies to extend our knowledge of adiponectin in cats. Data gathered in cats may also be applicable to humans and could therefore inform research using cats as an animal model of human obesity and type 2 diabetes.

This thesis presents an evaluation of the effectiveness of an agroforestry extension program to smallholder farmers on Leyte Island, the Philippines. The imperative for reforestation is well recognised in the Philippines and was the impetus for this program which provided farmers with assistance to establish and silviculturally manage timber trees on their land. Because the cost-effectiveness of agroforestry extension is increased if farmers develop self-efficacy without extensive training, the extension program was offered in two regimes to test the necessity for extended assistance. In the extended assistance regime, farmers were offered on-site assistance to collect seed, grow seedlings, prepare sites and establish trees, whereas in the limited assistance regime, farmers were only offered assistance to collect seed and grow seedlings. Descriptive statistics were collected of farmers’ acceptance of technology and the manner in which technology was adapted to suit their personal circumstances. Translated conversations between farmers and extension staff also provided a rich source of data which provided insights into farmers’ motivation. Extension activities were reviewed at a mid-program workshop, a final on-site inspection and an end-of-program workshop. Farmers responded positively to the extended assistance program which helped them to grow and out-plant seedlings. The limited assistance program was relatively unsuccessful. Overall, the extension program was successful in shifting the initiative for further planting from extension staff to participating farmers. However, farmers showed little interest in applying silvicultural thinning or pruning to existing plantations of trees because extension advice was not congruent with their existing mental models of these procedures. Systems modelling of socio-economic variables which had been found to affect program outcomes was used to predict critical success factors. A key constraint to program recruitment was found to be farmers’ perception of harvest security, even when their needs for technology and planting materials are met. Modelling also cast doubt on the usefulness of written extension materials and emphasised the necessity for extended face-to-face technical assistance. Although conducted in Leyte, the findings of this research provide guidance for issues which affect the adoption of agroforestry both in the Philippines and in other countries. The research found that it was possible to recruit and motivate farmers without providing material incentives. If farmers experienced unexpected problems, providing extended face-to-face contact and assistance was critical if catastrophic losses of participating farmers were to be avoided. The failure of attempts to introduce advanced-age silviculture also indicated a need to elicit farmers’ mental models as a precursor or parallel enquiry to extension activities. In a situation where little was initially known about farmers’ understanding of agroforestry technology or the variables which affect their acceptance or rejection of extension assistance, the results of this research have shown that it is possible to build the capacity of farmers to establish timber trees. This result is in contrast to the acknowledged failure of the logging concession system in the Philippines and the difficulties faced by some industrial plantations and community-based programs. This investigation has shown that an opportunity exists to lift the level of tree planting in Leyte, provided that system variables which are either critical success factors or impediments are addressed.

Ptilotus nobilis is a short-lived perennial wildflower, native to semi-arid and arid areas of Australia. Propagation by vegetative means is constrained by the early onset and a continuous flowering habit. Despite being defined as the main barrier for vegetative propagation no published research on floral induction and initiation was found. The aim of this study is to provide the first insights into floral evocation in P. nobilis, with the general objectives being to investigate floral induction and initiation, find the means to maintain plants in the vegetative phase, enhance leaf initiation and to gain knowledge of growth and development with an emphasis on light intensity, temperature and daylength. Early experiments aimed to increase the understanding of growth and development. The main cardinal events were identified including the onset of branching (axillary stem growth), visible bud stage, first floret opening and maturity of the inflorescence. To aid future cultivation schedules, four growing degree days (GDD) and one chronological model, using days after sowing (DAS), were established and validated. All GDD models were accurate in predicting first floret opening and maturity, but not in predicting visible bud stage. Best prediction was achieved by using an upper temperature threshold of 18.2 ºC and an own base temperature of 5.0 ºC. Days after sowing were an accurate means of prediction, indicating that temperature and other variables such as light intensity regulate development. A series of defoliation treatments investigated the maintenance of P. nobilis plants in the vegetative phase. Within all treatments, reproductive structures were observed and all plants with more than two true leaves entered the reproductive phase. Plants with less than two true leaves showed a delayed floral bud appearance by up to 20 days. Floral development was affected by most defoliation treatments resulting in vegetative growth within the inflorescences. It is hypothesized that plants have a very short juvenile phase and that a constant floral stimulus may be needed for floral evocation. Using scanning electron and light microscopy a template for the transition from vegetative to reproductive phase was developed. Bract initiation was accompanied by a significant increase in meristem area and diameter, and was defined as the onset of flowering. The established template was used in a subsequent glasshouse trial, which revealed that floral initiation occurred very early and at 25 DAS all plants had entered the reproductive phase. Branching and leaf area expansion were identified as post- initiation processes. Plants were exposed to different light intensities (229.3, 398.6 and 909.3 µmol m-2 s-1) in a glasshouse. Under low light, final leaf number increased by up to three leaves, indicating that the vegetative phase was prolonged. Cardinal events were delayed but all plants reached maturity. It was concluded that a light intensity of 229.3 µmol m-2 s-1 was not low enough to prevent floral initiation and that a further decrease of light intensity in combination with temperature could be more effective. Interactions of light intensity, temperature and daylength were investigated. Plants were grown under high light and low light (< 1.2 MJ m-2) intensities, 25/10 ºC and 35/20 ºC and daylengths of 11 h and 16 h. During the trial period (42 days), low light intensity suppressed floral initiation and high temperatures maintained more plants (70%) in the vegetative phase. However daylength treatments had no effect on the time of bract initiation or the percentage of vegetative plants. After 83 days floral buds and axillary stems were observed on some plants under low light intensity, indicating the onset of the reproductive phase and showing that P. nobilis could not be maintained in the vegetative phase indefinitely. Plants under high light were harvested at maturity and effects of temperature and daylength were analysed. Final leaf number increased under 35/20 ºC supporting the previously established results that floral initiation was delayed and leaf production enhanced by high temperature. Morphological data was collected to classify the photoperiodic response of P. nobilis. Plants under 25/10 ºC and 11 h had the longest inflorescences and greatest number of buds and flowers, which was also reflected in the buds and flowers dry weight, with an increase of up to 3.4 fold under these conditions. The difficulty of classifying some plants accordingly to their photoperiodic response and the proposal that P. nobilis may be a facultative short day plant under 25/10 ºC is discussed. In summary, this study presents the first evidence that P. nobilis has a very short juvenile phase and that growth and development are mainly driven by light intensity and temperature. It was possible to enhance vegetative growth by defoliation, low light intensity and high temperatures, however this did not fully prevent flowering, which indicates that P. nobilis has a very strong flowering response or signal.

Ptilotus nobilis is a short-lived perennial wildflower, native to semi-arid and arid areas of Australia. Propagation by vegetative means is constrained by the early onset and a continuous flowering habit. Despite being defined as the main barrier for vegetative propagation no published research on floral induction and initiation was found. The aim of this study is to provide the first insights into floral evocation in P. nobilis, with the general objectives being to investigate floral induction and initiation, find the means to maintain plants in the vegetative phase, enhance leaf initiation and to gain knowledge of growth and development with an emphasis on light intensity, temperature and daylength. Early experiments aimed to increase the understanding of growth and development. The main cardinal events were identified including the onset of branching (axillary stem growth), visible bud stage, first floret opening and maturity of the inflorescence. To aid future cultivation schedules, four growing degree days (GDD) and one chronological model, using days after sowing (DAS), were established and validated. All GDD models were accurate in predicting first floret opening and maturity, but not in predicting visible bud stage. Best prediction was achieved by using an upper temperature threshold of 18.2 ºC and an own base temperature of 5.0 ºC. Days after sowing were an accurate means of prediction, indicating that temperature and other variables such as light intensity regulate development. A series of defoliation treatments investigated the maintenance of P. nobilis plants in the vegetative phase. Within all treatments, reproductive structures were observed and all plants with more than two true leaves entered the reproductive phase. Plants with less than two true leaves showed a delayed floral bud appearance by up to 20 days. Floral development was affected by most defoliation treatments resulting in vegetative growth within the inflorescences. It is hypothesized that plants have a very short juvenile phase and that a constant floral stimulus may be needed for floral evocation. Using scanning electron and light microscopy a template for the transition from vegetative to reproductive phase was developed. Bract initiation was accompanied by a significant increase in meristem area and diameter, and was defined as the onset of flowering. The established template was used in a subsequent glasshouse trial, which revealed that floral initiation occurred very early and at 25 DAS all plants had entered the reproductive phase. Branching and leaf area expansion were identified as post- initiation processes. Plants were exposed to different light intensities (229.3, 398.6 and 909.3 µmol m-2 s-1) in a glasshouse. Under low light, final leaf number increased by up to three leaves, indicating that the vegetative phase was prolonged. Cardinal events were delayed but all plants reached maturity. It was concluded that a light intensity of 229.3 µmol m-2 s-1 was not low enough to prevent floral initiation and that a further decrease of light intensity in combination with temperature could be more effective. Interactions of light intensity, temperature and daylength were investigated. Plants were grown under high light and low light (< 1.2 MJ m-2) intensities, 25/10 ºC and 35/20 ºC and daylengths of 11 h and 16 h. During the trial period (42 days), low light intensity suppressed floral initiation and high temperatures maintained more plants (70%) in the vegetative phase. However daylength treatments had no effect on the time of bract initiation or the percentage of vegetative plants. After 83 days floral buds and axillary stems were observed on some plants under low light intensity, indicating the onset of the reproductive phase and showing that P. nobilis could not be maintained in the vegetative phase indefinitely. Plants under high light were harvested at maturity and effects of temperature and daylength were analysed. Final leaf number increased under 35/20 ºC supporting the previously established results that floral initiation was delayed and leaf production enhanced by high temperature. Morphological data was collected to classify the photoperiodic response of P. nobilis. Plants under 25/10 ºC and 11 h had the longest inflorescences and greatest number of buds and flowers, which was also reflected in the buds and flowers dry weight, with an increase of up to 3.4 fold under these conditions. The difficulty of classifying some plants accordingly to their photoperiodic response and the proposal that P. nobilis may be a facultative short day plant under 25/10 ºC is discussed. In summary, this study presents the first evidence that P. nobilis has a very short juvenile phase and that growth and development are mainly driven by light intensity and temperature. It was possible to enhance vegetative growth by defoliation, low light intensity and high temperatures, however this did not fully prevent flowering, which indicates that P. nobilis has a very strong flowering response or signal.