Large individual differences in cooperative contributions are common within animal societies such as cooperative breeders, where helpers care for offspring which are not their own. Understanding this variation has been a major focus in behavioural ecology and while evidence has shown that individuals are capable to adaptively adjust their cooperative behaviours, the physiological mechanisms underlying such adjustments remain poorly understood. Steroid hormones are prominent candidates to regulate cooperative behaviours due to their ability to integrate internal physiological state and environmental stimuli to produce an adaptive behavioural response. In this thesis, I investigate the effects of two steroid hormones, Cortisol (CORT) and Testosterone (T), in the regulation of cooperative behaviours in the Damaraland mole-rat (Fukomys damarensis). Because these hormones are susceptible to both modulate and be modulated by cooperative contributions, I experimentally tested both sides of this relationship. I show that, despite the absence of correlation between CORT and T and cooperative contributions, experimental increases of cooperative contributions elevate CORT levels, but not T (Chapter 3). Additionally, experimental increases of CORT levels in female helpers raised their cooperative contributions by more than one half demonstrating the regulatory effect of CORT on cooperative behaviours (Chapter 4). As breeding opportunities are likely to affect cooperative contributions and because T is a likely candidate to mediate a trade-off between future reproduction and current cooperation, I tested the effects of experimental increases of T levels in female helpers. I show that such elevations have no measurable effect of aggression, dispersal tendencies (both important to attain a breeding position) or cooperative contributions (Chapter 5). Taken together, the results of this thesis demonstrate that CORT can both respond to and regulate cooperative behaviours and suggest that this hormone may play a major role in the adaptive regulation of cooperative behaviour.

Social behavior of some species of African mole-rats makes them interesting object of study. Members of multigenerational families were only one pair breeds collectively work on building of their burrow system and obtaining food. Distribution of activity during the day in individual family members may give us a clue of how they manage their work. However, studies monitoring mole-rats in their natural environment are scarce and usually carried out on low number of individuals. Present study deals with outside-nest activity of 16 free-living Ansell´s mole-rats using data obtained by automatic radio-telemetry - method which was used in radio-tracking of mole-rats for the first time. It reveals differences in activity pattern of individual mole-rats and examines how they relate to body mass, sex, reproductive status and affiliation to a family and test whether individuals of the same family tend to be synchronized in their outside nest activity.

Master of Science / Department of Grain Science and Industry / X. Susan Sun / One of the leading causes of death following traumatic injury is exsanguination. The body addresses bleeding through the process of hemostasis which includes the formation of a fibrin mesh structure that holds a blood clot together. During traumatic injury, hemostasis may be unable to stop excess bleeding. Fibrin based hemostatic agents have been developed, however, these studies often use fibrin obtained from biological sources, which poses risk of infection. A novel amphiphilic peptide (h9e) has been studied to form three dimensional nanofibers networks. In this research, we studied the ability to form a synthetically produced, fibrin-mimic, hemostatic material from the h9e peptide sequence. The objective of this study was to determine the blood gelation strength of the h9e peptide necessary to arrest bleeding in the Wistar Rat model. Commercial mouse blood was used for blood gelation in vitro studies. Dynamic rheometer was used to determine the gelation kinetics at varied h9e peptide concentrations ranging from 1-5% wt. By directly mixing the h9e peptide with blood, we observed that the blood gelation strength right after mixing increased as the h9e peptide weight % concentration increased, from 67 to 1086 Pascals in the peptide concentration from 1 to 5%, respectively. After 24 hours, final gelation strength of all concentrations with commercial mouse blood was lower than the instantaneous strength but consistent throughout testing. Similar testing was conducted using commercial Wistar Rat blood with weight % concentrations of 1, 3, and 5% of h9e peptide. The gelation strength was 500, 1665, and 1914 Pascals, respectively. We also determined the gelation strength of Wistar Rat blood components, such as red blood cells, serum, and plasma with 1% h9e peptide. We observed the gelation response induced with individual blood components; however, the strength is weaker than whole blood. In vivo, we applied the cut-tail method by dipping the cut-tail of Wistar Rats into the h9e peptide solutions for 10 seconds and then took it out for blood lost collection. We observed that h9e peptide solution at 1, 3, and 5% weight concentrations can all generate hemostatic function. The h9e peptide solution at 5% weight concentration (1914 Pa) was able to outperform a commercial hemostatic material (Moore Medical CELOX* Hemostatic Granules), significantly reducing both bleeding time and blood lost: h9e peptide at 5% had a bleeding time of 94 sec and 0.75 mL blood lost, while the Celox hemostatic granules had a bleeding time of 225 sec and 1.5 mL blood lost. Transmission Electron Microscopy and Spinning Disk Confocal Microscope imaging indicated a blood component reinforced, web-like, h9e nanofiber structure similar to the structure formed by fibrin in a blood clot. This study showed that h9e peptide has the potential to be used to induce hemostasis.

Made available in DSpace on 2014-06-11T19:27:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-22Bitstream added on 2014-06-13T19:36:18Z : No. of bitstreams: 1 pascotto_vm_me_botfm.pdf: 1234125 bytes, checksum: 1d563b2c7f6645fcba3865762f9c46c7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente projeto objetivou investigar os efeitos da combinação, em baixas doses, de cinco praguicidas (dieldrin, dicofol, endosulfan, diclorvos e permetrina) sobre o sistema reprodutor de ratas Sprague-Dawley, Wistar e Lewis. Ratas de cada linhagem, com seis semanas de idade, foram randomizadas em três grupos: GI: controle negativo; GII: praguicidas adicionados à ração em doses de NOEL (mg/Kg/dia) - diclorvos (0,23), dicofol (0,5), dieldrin (0,025); endosulfan (0,7), permetrina (5); GIII: praguicidas adicionados à ração em doses de LOEL (mg/Kg/dia) - diclorvos (2,3), dicofol (2,1), dieldrin (0,05), endosulfan (3,8), permetrina (25). A eutanásia foi realizada entre a 10ª e a 12ª semana experimental, na fase de estro. Os parâmetros de avaliação foram: peso de fígado, útero e ovários; análise histológica qualitativa de fígado, útero e ovários; morfometria do endométrio; avaliação do ciclo estral; dosagem de LH, FSH e progesterona; e contagem de folículos ovarianos. Animais das três linhagens tratados com a LOEL apresentaram toxicidade sistêmica, evidenciada pela diminuição de peso corpóreo e aumento de peso de fígado. A análise qualitativa de útero e ovários, assim como a avaliação do ciclo estral e níveis hormonais não indicaram sinais de toxicidade reprodutiva exercida pelas misturas. A contagem de folículos ovarianos indicou ausência de resposta dose dependente e alta variabilidade entre os animais de mesmo grupo experimental. Desta forma concluímos que, embora os resultados tenham mostrado diminuição de algumas populações foliculares nas doses de NOEL e LOEL, este parâmetro não pode ser utilizado isoladamente como indicativo de toxicidade reprodutiva. Estes achados remetem à necessidade de maiores estudos para o esclarecimento dos efeitos destes compostos nas populações foliculares / This project aimed to investigate the effects of the combination, in low doses, of five pesticides (dieldrin, dicofol, endosulfan, dichlorvos and permethrin) on the reproductive system of Sprague- Dawley, Wistar and Lewis rats. Six-weeks-old rats from each strain were randomized into three groups: GI: negative control; GII: pesticides added to the feed at NOEL doses (mg/kg/day) - dichlorvos (0.23), dicofol (0.5), dieldrin (0.025), endosulfan (0.7), permethrin (5), GIII: pesticides added to the feed at LOEL doses (mg / kg / day) – dichlorvos (2.3), dicofol (2.1), dieldrin (0.05), endosulfan (3.8), permethrin (25). Euthanasia was performed between the 10th and 12th experimental week, in the estrous stage. The evaluation parameters were: weight of liver, uterus and ovaries; qualitative histological analysis of liver, uterus and ovaries; endometrium morphometry; estrous cycle assessment; dosage of LH, FSH and progesterone; and counting of ovarian follicles. Animals from all three strains showed systemic LOEL toxicity, as evidenced by decreased body weight and increased liver weight. Qualitative analysis of the uterus and ovaries, as well as estrous cycle and hormone levels evaluations indicated no signs of reproductive toxicity exerted by the mixtures. Counting of ovarian follicles indicated lack of dose-dependent response and high variability among animals from the same experimental group. Hence, we concluded that, although our results have shown a decrease of some follicular populations at the NOEL and LOEL doses, this parameter can not be used alone as an indicator of reproductive toxicity. These findings underscore the need for more studies to clarify the effects of these compounds on follicular populations

Class of 2012 Abstract / Specific Aims: The goal of this project was to evaluate the use of a preparation of the brainstem and spinal cord of neonatal rats that has been widely used for observing and quantifying central nervous activity, as well as the response to pharmacological manipulation. To achieve this, we specifically aimed to remove the intact brainstem and spinal cord of newborn rats, and develop a preparation that would maintain physiological function and allow for recording of electrical activity. Methods: Multiple dissections were performed on neonatal rats. Conditions during the dissections were controlled to maintain physiological function. Once removed, the intact brainstem and spinal cord was placed in a preparation that allowed for manipulation and access to nerve rootlets. Finally, glass suction electrodes were used to record electrical activity directly from the nerve rootlets. Once recorded, the data were stored on a hard drive for further analysis. Main Results: We were successful in isolating the intact brainstem and spinal cord in neonatal rats while maintaining physiological conditions and nervous activity. The preparation allowed for easy access to nerve roots as well as customization for different experiments. We were also successful in recording nerve activity in the preparation and collection of data for use in future experiments Conclusions: We conclude that the brainstem spinal cord preparation described in this study is a valuable tool that allows for recording and analysis of nerve activity, and specifically for measurement of respiratory motor output. This is a preparation that can be used in a variety of experiments that attempt to observe or quantify the activity of central nerve cells and allows for pharmacological interventions that could be applied in various experiments.

No description available.

African mole-rats (Bathyergidae) are subterranean hystricomorph rodents offering an excellent system with which to test theories relating to the evolution and maintenance of sociality in mammals. The aridity food distribution hypothesis (AFDH) suggests that, within the bathyergids, sociality has evolved in response to patterns of rainfall, its effects on food distribution, and the subsequent costs and risks of foraging and dispersal. Here, in the first detailed study of burrow architecture in a social mole-rat species, with data from 32 burrows, we show that in the giant mole-rat Fukomys mechowii, burrow fractal dimension increases with colony size and is higher during the rainy season than during the dry season. The mass of food in the burrow increases with fractal dimension and is higher during the rainy season than during the dry season. These results link for the first time colony size, burrow architecture, rainfall and foraging success and provide support for two assumptions of the AFDH, namely that (1) in arid conditions burrowing may be severely constrained by the high costs of digging; and (2) the potential risks of failing to locate food may be mitigated by increases in colony size. It was also fundamental in this study to assess whether the Fukomys mechowii is (1) An aseasonal or seasonal breeder (2) To investigate whether non-reproductive female giant mole-rats exhibit induced or spontaneous ovulation and finally (3) To estimate the age variation and sexual dimorphism of this little studied giant mole-rat species. Thus in a field study that involved the complete excavation of 32 burrow systems with a mean colony size of 9.9 individuals (range 7-16), it was evident that Fukomys mechowii is a cooperatively breeding mole-rat exhibiting a reproductive division of labour in which usually one, or occasionally two, females are responsible for procreation. Pregnant reproductive females were found throughout the study period (September 2005 until June 2006), supporting preliminary evidence that reproduction occurs throughout the year. Of the 32 colonies sampled, 14 of 18 (87.5%) in which the reproductive female could be identified as pregnant contained a single reproductive female, while four (12.5%) had two females breeding simultaneously (plural breeding). The population sex ratio was skewed towards females at 1:1.46. Autopsy of pregnant reproductive females (n=18) revealed that the production of two (10/18 pregnancies) or three (7/18) offspring was the norm, with one case of four embryos being present. These new data increase our fragmentary knowledge of the natural history of this little studied species. Six non-reproductive females were removed from their natal colonies and housed individually without a male for a period of 12 weeks as a control group. They were then subsequently housed for a further 6 weeks as experiment 1, on their own before being allowed non-physical contact in experiment 2, with a mature adult male for a further 6 weeks. The non-reproductive females were given a further period of isolation for a month prior to being physically paired with vasectomized males, in experiment 3. Urine was collected every second day for all three experiments and urinary progesterone profiles were generated. The progesterone values measured during the first part of Experiment 2 and 3 were markedly higher than those measured during the first part of Experiment 1 (Z= -2.201, p=0.028 for both comparisons), however, this was not significant after Bonferroni correction. Similarly progesterone values tended to be elevated during the second phase of Experiment 2 and 3 but not significantly so (Experiment 1 vs. 2: Z=-1.782, p=0.075, Experiment 1 vs. 3: Z=-2.201, p=0.028). Thus, chemical or physical stimulation by a male does not appear to be necessary for ovulation in female giant mole-rats. The giant mole-rat is a spontaneous ovulator. Due to difficulties in estimating absolute age in mammals, different methods for its estimation have been proposed, and among these, the degree of molar eruption and wear are considered to be one of the most reliable indicators of relative age. Consequently, maxillary molar tooth-row eruption and wear were used to assign individuals of the giant mole-rat, Fukomys mechowii (Peters, 1881) from two geographically proximal and ecologically similar localities in the Copper-belt Province of Zambia to 9 relative age classes. These were in turn used to assess the nature and extent of sexual dimorphism and age variation in this little-studied social mole-rat based on cranial morphometric data, reference to body mass and a series of both univariate and multivariate statistical analyses. Both univariate and multivariate analyses showed morphological differences between individuals of age classes 1–3 and those of age classes 5–9, while individuals of age class 4 were intermediate between these age class groupings, suggesting that this age class lies at a point on a hypothetical growth curve where it begins to stabilize. The analysis of the nature and extent of sexual dimorphism revealed its absence in the younger individuals of age classes 1–4 and its presence in older age classes 5–9. These results may allow an insight into our understanding of the population social structure, and reproductive strategies in the giant mole-rat. In conclusion, it is worth mentioning that; (1) A number of studies have examined burrow architecture, although not necessarily fractal dimensions in the Bathyergidae but the majority of these have concentrated on solitary species in which when there is plural occupancy it is during the breeding season or when the mother has a litter. This study is thus the first to examine in detail the dynamic nature of social mole-rat burrows, with respect to seasonal changes. The burrow fractal dimension is a good indication of the mole-rats ability to burrow to find food and thus results support the critical assumption which underlies the aridity food distribution hypothesis. The results accord well with previous data in social mole-rats indicating that larger colonies have greater survival and link colony size, burrow architecture and foraging success for the first time; (2) the giant mole-rat is an aseasonal breeder which in a few instances can have two queens per colony; (3) the giant mole-rat is a spontaneous ovulator and finally (4) the giant mole-rat Fukomys mechowii exhibits a sexual dimorphism amongst its older age classes 5-9. Suggesting that there are different growth curves in males versus females, whereby males attain much larger size (skull size and body mass) than females after puberty and finally intimating that opportunistic mating competition among males is very high. / Thesis (PhD)--University of Pretoria, 2011. / Zoology and Entomology / Unrestricted

Psychopharmacological studies have implicated the mesolimbic dopamine (DA) system in the mediation of cost/benefit evaluations about effort-related costs associated with larger rewards. However, the role of DA in risk-based decision making remains relatively unexplored. The present study investigated how systemic manipulations of DA transmission affect risky choice assessed with a probabilistic discounting task. Over discrete trials, rats between two levers; a press on the “small/certain” lever always delivered one reward pellet, whereas a press on the other, “large/risky” lever delivered four pellets, but the probability of receiving reward decreased across the four trial blocks (100%, 50%, 25%, 12.5%). In separate groups of well-trained rats we assessed the effects of the DA releaser amphetamine, as well as receptor selective agonists and antagonists. Amphetamine consistently increased preference for the large/risky lever; an effect that was blocked or attenuated by co-administration of either D₁ (SCH23390) or D₂ (eticlopride) receptors antagonists. Blockade of either of these receptors alone induced risk aversion. Conversely, stimulation of D₁ (SKF81297) or D₂ (bromocriptine) receptors also increased risky choice. In contrast, activation of D₃ receptors with PD128,907 induced risk aversion. Likewise, D₃ antagonism with nafadotride potentiated the amphetamine-induced increase in risky choice. Blockade or stimulation of D₄ receptors did not reliably alter patterns of choice. These findings indicate that DA plays a critical role in mediating risk-based decision making, where increased activation of D₁ and D₂ receptors biases choice towards larger, probabilistic rewards, whereas D₃ receptors appear to exert opposing effects on this form of decision making. / Arts, Faculty of / Psychology, Department of / Graduate

This work attempts to establish some phenomenon of a rise in titer of C'3 and C'4 due to antigenic stimulation. Normal level of complement is established and compared to other workers as well as against guinea pig levels. Young rats were bled to establish normal levels of complement. The animals were then injected with an antigenic substance and after a period of seven days were bled again to determine the level of complement. Various antigenic and non-antigenic substances were used as well as normal saline injections for control.

Orientador: Wilma de Grava Kempinas / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-07T11:02:16Z (GMT). No. of bitstreams: 1 Arena_ArielleCristina_D.pdf: 6263469 bytes, checksum: 65be2ee6efd96baa2f00b966ad068e99 (MD5) Previous issue date: 2006 / Resumo: O fenvalerato é um inseticida piretróide sintético amplamente utilizado na agricultura para o controle de pragas. Embora seja considerado de baixa toxicidade para os mamíferos, trabalhos têm demonstrado que certos piretróides podem apresentar atividade estrogênica e atuar como desreguladores endócrinos, acarretando disfunções reprodutivas importantes no sexo masculino. Está documentado na literatura que a exposição de ratas prenhes ao fenvalerato reduziu os níveis plasmáticos de testosterona e os pesos da vesícula seminal e do ducto deferente dos filhotes machos na idade adulta, além de alterações no comportamento sexual desses animais. Também foi observado que ratos adultos expostos à formulação de fenvalerato, por inalação, exibiram uma redução significativa no peso dos testículos e na contagem espermática no epidídimo. Até o momento pouco se sabe sobre os mecanismos pelos quais o fenvalerato exerce sua ação na reprodução, assim, o objetivo do presente trabalho foi investigar a atividade estrogênica e os efeitos do inseticida piretróide fenvalerato sobre o sistema reprodutor masculino e fertilidade de ratos machos adultos. Para tanto, ratos machos adultos (90 dias de idade) receberam durante 30 dias consecutivos, por gavage (via oral), 40 mg/kg/dia de fenvalerato (grau técnico; 96,8% de pureza). O grupo controle recebeu apenas o veículo (óleo de milho), segundo o mesmo protocolo experimental. No final do tratamento, foram avaliados os seguintes parâmetros: peso corporal; peso absoluto de órgãos da reprodução, fígado e rins; níveis plasmáticos de testosterona; contagem de células germinativas no testículo e no epidídimo; morfologia espermática; estudo da fertilidade através de cruzamentos naturais e inseminação artificial in utero; contagem de espermatozóides ejaculados no útero; avaliação do comportamento sexual; análises do testículo e epidídimo em nível de microscopia óptica e eletrônica e avaliação da possível atividade estrogênica de diferentes doses do fenvalerato (0,4; 1,0; 4,0; 8,0 e 40 mg/kg) através do teste uterotrófico. A quantificação de resíduos de fenvalerato por Cromatografia Líquida de Alta Precisão (HPLC) em órgãos reprodutores e vitais e análises de proteínas espermáticas e epididimárias também foram realizadas. Os resultados foram comparados pelos testes ¿t¿ de Student e Mann-Whitney, dependendo da natureza da distribuição dos dados, enquanto os resultados do teste uterotrófico comparados pela ANOVA seguida pelo teste de Tukey. Os resultados da quantificação de fenvalerato revelaram que o piretróide foi retido em órgãos reprodutores (testículo e epidídimo) e vitais (cérebro e fígado). O tratamento com fenvalerato reduziu os pesos absolutos do testículo e do epidídimo. Além disso, o tratamento não provocou diminuição nos níveis plasmáticos de testosterona. Verificou-se também que os ratos tratados apresentaram redução na produção espermática no testículo e no número de espermatozóides no epidídimo. No entanto, não foi observado comprometimento na fertilidade desses machos quando acasalados com fêmeas controles. As análises morfológicas do testículo e epidídimo assim como as análises de proteínas espermáticas e epididimárias não mostraram alterações. Além disso, o fenvalerato, nas doses testadas, não apresentou atividade estrogênica in vivo. Concluiu-se que o fenvalerato, nestas condições experimentais, foi retido em órgãos reprodutores e vitais. O fenvalerato foi espermatotóxico, visto que reduziu tanto a produção quanto as reservas espermáticas dos animais tratados. No entanto, apesar dessa alteração, a fertilidade dos animais tratados não foi comprometida, uma vez que o rato tem uma grande eficiência reprodutiva, diferentemente do que acontece com o ser humano / Abstract: Fenvalerate is a synthetic pyrethroid insecticide widely used in agriculture to control a variety of insects. Although it is considered to be of low acute toxicity to mammals, studies have showed that pyrethroids can have estrogenic activity and can act as endocrine disruptors, causing important reproductive impairment in males. It is documented in the literature that the exposure of pregnant rats to fenvalerate decreased plasma testosterone levels and weights of seminal vesicle and vas deferens in male pups during adult life, besides alterations in their sexual behavior. It was also observed that adult rats exposed to formulated fenvalerate,by inhalation, exhibited a significant reduction in the testis weight and epididymal sperm count. Little is known about the mechanisms by which fenvalerate exerts its action on reproduction; thus, the objective of the present study was to investigate the estrogenic activity and the effects of fenvalerate on the reproductive system and fertility of adult male rats. For this, adult male rats (aged 90 days) received, for 30 consecutive days, by oral gavage, 40 mg/kg/day of fenvalerate (technical grade; 96.8% purity). The control group received only the vehicle (corn oil), in the same experimental conditions. At the end of the treatment, the following parameters were analyzed: body weight; absolute weight of reproductive organs, liver and kidneys; plasma testosterone levels; germ cell count in the testis and epididymis; sperm morphology; fertility tests by natural matings and artificial insemination in utero; ejaculated sperm counts in uterus; sexual behavior; analysis of testis and epididymis at the optical and electron microscopic levels, and evaluation of possible estrogenic activity of different doses (0.4; 1.0; 4.0; 8.0 and 40 mg/kg) of fenvalerate by the uterotrophic test. Fenvalerate residues were quantified using High Performance Liquid Chromatography (HPLC) in reproductive and vital organs; sperm and epididymal protein were also realized. The results were compared by Student-t and Mann-Whitney tests, according to the characteristics of each variable, while the results of the uterotrophic test were compared by ANOVA followed by the Tukey test. The results of fenvalerate quantification revealed that the pyrethroid was retained in reproductive (testis and epididymis) and vital organs (brain and liver). The treatment with fenvalerate decreased the absolute weights of testis and epididymis. Furthermore, the treatment did not provoke reduction of plasma testosterone levels. It was also verified that the treated rats presented a reduction in daily sperm production and in epididymal sperm number. The fertility tests did not reveal differences related to the treatment. The results of the fenvalerate quantification revealed high concentrations of insecticide residues in the epididymis, testis, brain and liver. The histopathology of the testis and epididymis as well as analysis of sperm and epididymal proteins did not show alterations. Moreover, fenvalerate, at the tested doses, did not present estrogenic activity in vivo. It was concluded that fenvalerate, in these experimental conditions, was retained in reproductive organs and was spermatotoxic, since it reduced sperm production and storage, but this alteration was not sufficient to compromise fertility by virtue of the high reproductive efficiency of rodents in contrast with humans / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural