The aim of this study was to investigate the possible toxicity of the flavonoid-containing plant, Artemisia afra and especially establish the safety of the aqueous extract of this plant after acute and chronic administration to mice and rats respectively.

Magister Scientiae - MSc / The aim of this study was to investigate the possible toxicity of the flavonoid-containing plant, Artemisia afra and especially establish the safety of the aqueous extract of this plant after acute and chronic administration to mice and rats respectively. / South Africa

MENVSC / Department of Ecology and Resource Management / Rodents can quickly respond to land use changes whether the change positively or negatively influences their life. In the case of positive influence, rodents exploit the additional food resources and increase their numbers to potential pest level, especially in the absence of predators. Such a population increase can potentially be harmful to humans due to the diseases that rodents carry and the costs due to damage to crops, stored foods and personal possessions that they may cause to small holder farmers. Small holder farmers live in a mixed landscape that is constantly changing. Such changes are changes in land use and they do not only affect rodent population dynamics and species composition, but also their ecosystem services and integrity. Understanding how rodents respond to these land use changes (crop, grazing and settlement) will not only improve the implementation of Ecologically Based Rodent Management (EBRM), but might also enable the monitoring of ecosystem integrity. Rodent trapping was conducted in two different study sites which experience different rainfalls during wet and dry season. A 70 m x 70 m grid was set in three different land uses (crops, grazing and settlement) per study site. A mark-recapture technique was applied and all captures were processed on a temporal station on site. In all grids at a distance of 30 m a line of 20 snap traps were set. With the tapping effort of 1470 trap nights per season for both seasons in this study we captured 839 rodents and 2 shrews, which represented 469 individual rodents and 1 individual shrew. At Vyeboom, cropping land use had the highest number capture (210) and the highest in species richness (9) rodent species and 1 shrew. The settlement land use was second at 144 captures for 8 rodent species and lastly the grazing land use at 80 captures with 7 rodent species. On the other hand, at Ka-Ndengeza also cropping land use had the highest capture (186) with highest richness at 7 rodent species. When it comes to settlement and grazing, settlement was second (129) to cropping in terms of the number of capture but last in terms of richness (5) whilst grazing was last in terms of number of captures 92 and second in terms of richness (6). Despite the high diversity of rodents, only Mastomys natalensis, Gerbilliscus leucogaster, Steatomys pratensis and Rattus rattus were captured in meaningful sample sizes to allow for robust density estimation. Similarly there were strong seasonal effects on rodent captures, with almost no captures during the wet season.

A Caatinga é um ecossistema brasileiro análogo as savanas africanas apresentando escassez de chuvas e temperaturas altas. O mocó apresenta, importantes adaptações ao microambiente dos afloramentos rochosos. Esse roedor caviomorfo, abandonou o hábito pastador comum a outros roedores cavíneos, como preá e a capivara, pela capacidade de escalar árvores e se alimentar de folhas e frutos. Alongou o período de gestação e adotou o cuidado paterno. Interessados em entender de que forma a comunicação acústica teria se ajustado ao ambiente isolado dos rochedos da caatinga, gravamos e analisamos as emissões sonoras dos mocós. Foram 90 dias de trabalho de campo nas Fazendas Tamanduá e São Francisco, na cidade de Patos, Paraíba. Capturamos 13 animais (6 machos e 7 fêmeas) e fizemos registros em áudio e vídeo em três situações: 1) pareamentos em caixa teste, nas condições macho x macho, macho x fêmea e fêmea x fêmea, 2) animais em grupo em cativeiro, e 3) animais em vida livre. Encontramos um repertório de 11 sinais sonoros, registrados em 3 categorias amplas de comportamento: (1) Exploração/Forrageamento: Có de contato, Estalido, Chorinho e Drrr; (2) Alerta: Assobio de alarme, Drrr e Silvo; (3) Interação Agonística: Ganido, Grito, Ronco, Arfar, Assobio de alarme e o Baterdedentes. O repertório mostrouse mais rico do que o de outros caviomorfos, como o preá. Discutimos esse resultado em relação ao tipo de vida social da espécie em comparação com a de outros caviníneos e à vida nos rochedos da caatinga. Também sugerimos que o Assobio de alarme seja um comportamento compartilhado entre o mocó e outras espécies de roedores 10 de rochedos. Há uma perspectiva de continuidade da pesquisa em busca de uma maior compreensão da função biológica desse sinal e da riqueza desse repertório acústico / The environment of Brazilian Caatinga ecosystem is similar to African Savannah with low level of rain and high temperature. The Moco shows important adaptation at the microenvironment of rock outcrops. This caviomorph rodent abandoned grazing habit, commom at others Caviinae species such as the Cavy and the Capybara for the capacity of climbing trees feeding of leaves and fruits. It also lengthened the gestation period and adopted paternal care. Interested in understanding how acoustic communication would have adjusted to the isolated environment of Caatinga rock piles, we recorded and analyzed the signals songs of Moco. Past through 90 days in field at Fazenda Tamanduá and Sítio São Francisco located at Patos city Paraiba State in Brazil. We captured 13 animals (6 males and 7 females), acquired audio and video of animals in three different situations: 1) paired in tests boxes under conditions: male x male, female x male and female x female; 2) captivity group and 3) Living free. We found a repertoire with 11 acoustic signals registered in 3 broad behavioral categories: (1) Exploration/ Foraging: Contact call, Co, Clicking (Estalido), Whine (Chorinho) and Drrr call, (2) Warning: Alarm whistle, Drrr call and Silvo, (3) Agonistic Interaction: yelp (Ganido), scream (Grito), grunt (Ronco), a breathless like sound (Arfar), Alarm Whistle and ToothChatter. This repertoire showed more rich that other caviomorph as a cavy. eu escreveria esse parágrafo dessa forma: This repertoire seemed better than other caviomorph as a Cavy. We discussed those results comparing the social life of species with social life of others Caviinae and the life at the rock piles of Caatinga. We also suggested that the Alarm whistle is shared between the 12 Moco and others rock rodents. There is a perspective to continue this research looking for a better comprehension of the biologic function of this signal and acoustic repertoire richness

A Caatinga é um ecossistema brasileiro análogo as savanas africanas apresentando escassez de chuvas e temperaturas altas. O mocó apresenta, importantes adaptações ao microambiente dos afloramentos rochosos. Esse roedor caviomorfo, abandonou o hábito pastador comum a outros roedores cavíneos, como preá e a capivara, pela capacidade de escalar árvores e se alimentar de folhas e frutos. Alongou o período de gestação e adotou o cuidado paterno. Interessados em entender de que forma a comunicação acústica teria se ajustado ao ambiente isolado dos rochedos da caatinga, gravamos e analisamos as emissões sonoras dos mocós. Foram 90 dias de trabalho de campo nas Fazendas Tamanduá e São Francisco, na cidade de Patos, Paraíba. Capturamos 13 animais (6 machos e 7 fêmeas) e fizemos registros em áudio e vídeo em três situações: 1) pareamentos em caixa teste, nas condições macho x macho, macho x fêmea e fêmea x fêmea, 2) animais em grupo em cativeiro, e 3) animais em vida livre. Encontramos um repertório de 11 sinais sonoros, registrados em 3 categorias amplas de comportamento: (1) Exploração/Forrageamento: Có de contato, Estalido, Chorinho e Drrr; (2) Alerta: Assobio de alarme, Drrr e Silvo; (3) Interação Agonística: Ganido, Grito, Ronco, Arfar, Assobio de alarme e o Baterdedentes. O repertório mostrouse mais rico do que o de outros caviomorfos, como o preá. Discutimos esse resultado em relação ao tipo de vida social da espécie em comparação com a de outros caviníneos e à vida nos rochedos da caatinga. Também sugerimos que o Assobio de alarme seja um comportamento compartilhado entre o mocó e outras espécies de roedores 10 de rochedos. Há uma perspectiva de continuidade da pesquisa em busca de uma maior compreensão da função biológica desse sinal e da riqueza desse repertório acústico / The environment of Brazilian Caatinga ecosystem is similar to African Savannah with low level of rain and high temperature. The Moco shows important adaptation at the microenvironment of rock outcrops. This caviomorph rodent abandoned grazing habit, commom at others Caviinae species such as the Cavy and the Capybara for the capacity of climbing trees feeding of leaves and fruits. It also lengthened the gestation period and adopted paternal care. Interested in understanding how acoustic communication would have adjusted to the isolated environment of Caatinga rock piles, we recorded and analyzed the signals songs of Moco. Past through 90 days in field at Fazenda Tamanduá and Sítio São Francisco located at Patos city Paraiba State in Brazil. We captured 13 animals (6 males and 7 females), acquired audio and video of animals in three different situations: 1) paired in tests boxes under conditions: male x male, female x male and female x female; 2) captivity group and 3) Living free. We found a repertoire with 11 acoustic signals registered in 3 broad behavioral categories: (1) Exploration/ Foraging: Contact call, Co, Clicking (Estalido), Whine (Chorinho) and Drrr call, (2) Warning: Alarm whistle, Drrr call and Silvo, (3) Agonistic Interaction: yelp (Ganido), scream (Grito), grunt (Ronco), a breathless like sound (Arfar), Alarm Whistle and ToothChatter. This repertoire showed more rich that other caviomorph as a cavy. eu escreveria esse parágrafo dessa forma: This repertoire seemed better than other caviomorph as a Cavy. We discussed those results comparing the social life of species with social life of others Caviinae and the life at the rock piles of Caatinga. We also suggested that the Alarm whistle is shared between the 12 Moco and others rock rodents. There is a perspective to continue this research looking for a better comprehension of the biologic function of this signal and acoustic repertoire richness

Dissertation (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Introduction Despite advances in insulin therapy, the side effects associated with diabetes mellitus still remain. Pancreas transplantation has benefited diabetics with end-stage renal failure by reversing the diabetic state and preventing or reversing the progression of diabetes associated diseases. Currently the side effects associated with lifelong immunosuppression preclude pancreas transplantation as a viable treatment option for both type I and II diabetics. In the laboratory, transplanted rat foetal pancreata have been shown to be able to reverse the clinical signs of streptozotocin-induced diabetes in an isogeneic model. Reversal of diabetes by allogeneic foetal rat pancreas transplantation, although possible has proved to be more difficult due to fierce rejection of the grafts and the diabetogenic effects of conventional immunosuppressants. Aims One of the goals, focus and intentions of this laboratory study in rodents, is to contribute new information to the scientific literature. The potential to “reverse” the diabetic state by allogeneic foetal pancreatic transplantation, was the main stimulus for this study. Methods Foetal pancreata of 16-18 days gestation were transplanted into a surgically prepared renal subcapsular space. Immunosuppressive protocols used to prevent rejection of the allogeneic foetal rat pancreata included donor specific transfusion (DST), cyclosporine [a calcineurin inhibitor (CsA)], mycophenolate mofetil [a purine syntase inhibitor (MMF)], and a mouse anti-rat CD4 monoclonal antibody (W3/25). Immunosuppressants were used as monotherapies and in combination. Results Isogeneic foetal rat pancreas transplantation resulted in the growth and development of mature insulin producing islets of Langerhans at the site of engraftment. Allogeneic foetal pancreatic transplantation without immunosuppression resulted in complete rejection of the grafts at 14 days post-transplantation. Histological assessment of allografts at 14 and 30 days post-transplantation showed that CsA was able to prevent acute rejection in our rat models although graft scores and survival were improved if CsA was combined with MMF. Intraperitoneal anti-CD4 monoclonal injections were well tolerated, and if given daily effectively prolonged graft survival up to 30 days. Combining DST with anti-CD4 and CsA induction therapy provided long-term graft survival without daily immunosuppression. This combination, together with allogeneic foetal rat pancreas transplantation, was effective in reversing the clinical signs of experimentally induced diabetes. To my knowledge these are the first published results in which reversal of streptozotocin induced diabetes was achieved by fully MHC mismatched foetal rat pancreatic transplantation. Conclusion Foetal rat pancreatic transplantation is a potential source of endocrine replacement, which, with effective immunosuppression allows for the development of functional islets able to reverse the clinical signs of experimentally induced diabetes in an allogeneic rat model. An unique immunosuppressive protocol, with potential clinical relevance in the human, combines anti-CD4 mAb, CsA and DST induction therapy, which alleviates the burden of daily immunosuppression and associated side effects. / AFRIKAANSE OPSOMMING: Inleiding Ten spyte van die vordering met modeme insulienterapie bly die newe-effekte, waarmee diabetes mellitus geassosieer is, steeds ‘n probleem vir diabete. Diabetiese pasiente met eindstadium nierversaking trek geweldig voordeel uit nier-pankreasoorplantings wat die diabetes omkeer en die progressie van diabetesverwantesiektes voorkom of selfs omkeer. Die newe-effekte van lewenslange immuunonderdrukking skakel pankreasoorplanting uit as ‘n lewensvatbare behandelingsopsie vir tipe I of II diabete. In ‘n streptozotosien-gei'nduseerde diabetiese rotmodel kan isogenei'ese fetale pankreasoorplanting die kliniese tekens van diabetes omkeer. Die omkering van streptozotosien-gei'nduseerde diabetes deur allogeneiese fetale pankreasoorplanting behoort moontlik te wees indien verwerping en die diabetogeniese newe-effekte van konvensionele immuunonderdrukkers oorkom word. Doelstellings Een van die mikpunte, fokusse en oogmerke van hierdie laboratorium studie in knaagdiere, is om ‘n betekenisvolle bydrae tot nuwe kennis in die wetenskaplike literatuur, te maak. Die potensiaal om die diabetiese toestand deur allogeneiese fetale pankeasoorplanting om te keer, was die hoof stimulus vir die studie. Metodes Fetale rotpankreata van 16-18 dae gestasie was in ‘n chirurgies voorbereide spasie onder die nierkapsel oorgeplant. Immuunonderdrukkende protokolle, vir die voorkomming van verwerping van die allogeneiese fetale pankreasoorplantings, het donorspesifiekeoortappings (DST), siklosporien [‘n kalsineurien inhibitor (CsA)], mikofenolaat mofetiel [‘n purien sintase inhibitor (MMF)] en ‘n anti-rot CD4 monoklonale antiliggaam (W3/25) ingesluit. Die immuunonderdrukkers is as mono- of as kombinasieterapie gebruik. Resultate IsogeneTese fetale rotpankreasoorplanting het tot die ontwikkeling van volwasse insulienproduseerende eilande van Langerhans gelei, wat die kliniese tekens van streptozotosien-gei'nduseerde diabetes kon omkeer. Allogenei'ese fetale rotpankreasoorplanting sonder immuunonderdrukking het tot algehele verwerping van die oorplanting binnel4 dae na oorplanting gelei. Histologiese beoordeling van die oorplantings 14 en 30 dae na oorplanting het getoon dat CsA akute verwerping van fetale pankreasoorplantings in die rotmodelle voorkom. Indien CsA met MMF gekombineer word, word die oorplantings-telling en oorlewing verbeter. Intraperitoneale anti-CD4 monoklonale inspuitings was goed verdra, en indien daagliks toegedien, het dit die oorlewing van die pankreasoorplantings effektief tot 30 dae verleng. Die kombinasie van DST, anti-CD4 en CsA induksieterapie het tot langtermyn oorlewing van die pankreasoorplantings gelei sonder verdere daaglikse immuunonderdrukking. Die induksieterapie in kombinasie met allogenei'ese fetale pankreasoorplanting was effektief in die omkering van die kliniese tekens van streptozotosien-gei'nduseerde diabetes in die rot. Hierdie is, sover ek weet, die eerste keer dat omkering van streptozotosien-gei'nduseerde diabetes suksesvol met ‘n volledige MHC onverenigbare allogenei'ese fetale pankreasoorplanting behaal is. Gevolgtrekkings Fetale rotpankreasoorplanting is ‘n potensiele bron vir endokrien vervangingsterapie, wat met effektiewe immuunonderdrukking tot die ontwikkeling van funksionele eilande van Langerhans lei, wat die vermoe het om die kliniese tekens van experimenteel-ge'induseerde diabetes in ‘n allogeneiese rotmodel om te keer. ‘n Unieke immuunonderdrukkingsprotokol, met kliniese relevansie, kombineer DST met anti-CD4 mAb en CsA induksieterapie wat die las van daaglikse immuunonderdrukking en die geassosieerde newe-effekte van konvensionele immuunonderdrukking verlig.

published_or_final_version / Anatomy / Master / Master of Philosophy

published_or_final_version / Diagnostic Radiology / Doctoral / Doctor of Philosophy

Positive frequency-dependent predation (FDP) has been proposed as a species coexistence mechanism and theoretical models have shown how it may function. In positive FDP a rare species receives a temporary reprieve from predation pressure allowing an increase to its population growth rate and a chance for it to recover from rarity. This study tests for frequency-dependent foraging by granivorous desert rodents on the seeds of three species of winter annual plants that grow in the Sonoran Desert. While the preference for one species is much higher than the other two, preferences for each species are higher when common than when rare showing an asymmetric form of positive FDP. This study is the first empirical test for positive FDP on winter annual plants and by granivorous desert rodents and one of few to use more than two prey species, native prey species, or asymmetrically preferred prey species.

Alcohol use disorders are a public health issue related to adverse effects for individuals and society. A low level of response, or decreased sensitivity, to alcohol has been identified as a heritable risk factor for development of alcohol use disorders. One method for researching level of response to alcohol is through the use of rodent models, which are developed to mimic human conditions while eliminating barriers to conducting research with people. Current rodent models used to evaluate effects of ethanol on motor performance have been criticized for not being well matched to human tasks that measure level of change in body sway after alcohol consumption. This study looks at oromotor behavior as a potential alternative to gross motor performance in hopes of increasing correspondence between human and rodent measures of intoxication. To evaluate rodent oromotor performance a force transducer lickometer is used to measure several dimensions of licking behavior after administration of different concentrations of ethanol solution via gavage. Results show that force of licking is not sensitive to dose of ethanol. The total number of licks per session show dose related decreases and licking rhythm, evaluated by the length and distribution of interlick intervals, either increased or decreased for three of the four subjects. Recommendations are made for procedural modifications in order to reduce variability in data and further investigate oromotor performance and level of response to alcohol.