Einfluss von "Stress inoculation" und "Resilience" auf die alters- und geschlechtsspezifische Entwicklung des Angst-, Lern- und Sozialverhaltens von Degus (Octodon degus) und Ratten (Rattus norvegicus)

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2014

Ectoparasitos de roedores da região urbana de Belo Horizonte, MG: II. Oscilações dos índices de infestação em Rattus norvegicus norvegicus

Os índices de infestação proporcionados pelo ácaro Echinolaelaps echidninus e Laelaps nuttalli, pelo piolho Polyplax spinulosa e pela pulga Xenopsylla cheopis, obtidos mensalmente no período de junho de 1980 a setembro de 1982, em Rattus norvegicus da região urbana de Belo Horizonte, Minas Gerais, Brasil, foram relacionados com períodos estacionais, sexo dos hospedeiros e áreas de captura. Acaros e insetos apresentaram comportamento diferente face a estas variáveis, já que apenas as pulgas e os piolhos exibiram associações significativas entre a infestação nos roedores e os períodos estacionais, ou entre a infestação e o sexo dos roedores, ou ainda uma variação da distribuição pelas áreas onde as capturas foram mais freqüentes. Enquanto as pulgas infestaram um maior número de roedores na estação chuvosa-quente (outubro a março), a infestação proporcionada pelo piolho foi mais intensa na estação seca-fria. Os fatores climáticos mais relacionados com a infestação nos hospedeiros foram, em ordem decrescente, a precipitação pluviométrica, a temperatura e a umidade relativa do ar. Tanto pulgas como piolhos apresentaram infestações preferenciais por roedores machos, sendo a proporcionada por X. cheopis, altamente significativa.

Ectoparasitos de roedores da região urbana de Belo Horizonte, MG: III. Indices pulicidianos, anoplurianos e acarianos em Rattus Norvegicus norvegicus

Indices pulicidianos, anoplurianos e acarianos, globais e específicos foram determinados para os ectoparasitos de Rattus norvegicus norvegicus capturados em zona urbana de Belo Horizonte, Minas Gerais, Brasil, no período de junho de 1980 a setembro de 1982. Tendo-se em vista os valores limites ou críticos atribuídos aos índices pulicidianos, sobretudo ao índice "cheopis" e propostos por diversos autores como medida complementar de vigilância epidemiológica para peste bubônica, a comunidade de Belo Horizonte poderia ter estado exposta a esta infecção, uma vez que os índices globais anuais de 0,3 a 2,4 e a pulga prevalente foi Xenopsylla cheopis (99,2%), com os maiores índices coincidindo com o final da estação seca-fria. Em duas ocasiões, a comunidade poderia ter permanecido altamente exposta à infecção, já que os índices-limites tolerados foram suplantados: 8,8 (outubro 1980) e 6,2 (setembro 1982). Sugere-se que medidas profiláticas como anti-ratização e desinsetização sejam eficazmente aplicadas ao final da estação seca-fria, ou anteriormente à chegada das chuvas, sendo sucedidas pela desratização. Informações sobre índices anoplurianos e acarianos são importantes para que se possa, no exclusivas de roedores

Prevalence of Trypanosoma lewisi in Rattus norvegicus from Belo Horizonte, State of Minas Gerais, Brazil

From April 1984 to March 1985, a Trypanosoma lewisi prevalence of 21.7% was found in 429 Rattus norvegicus trapped in Belo Horizonte, State of Minas Gerais, Brazil. The infection rates were higher in male and young rats and could be attributed to ecological and behavioral factors. T. lewisi was observed in rats measuring between 60 and 250 mm. Data about monthly T. lewisi infections throughout the year are presented for the first time in Brazil, with the highest prevalences observed in the warm-rainy season (October to March).

Larval recovery of Toxocara canis in organs and tissues of experimentally infected Rattus norvegicus

The aim of this note was to record for the first time the recovery of Toxocara canis larvae from tissues and organs of Rattus norvegicus (Berkenhout, 1769), Wistar strain, until the 60th day after experimental infection. Rats were orally infected with embryonated T. canis eggs, killed on days 3, 5, 8, 10, 15, 30, and 60 after inoculation and larvae were recovered from liver, lungs, kidneys, brain, and carcass after acid digestion, showing a pattern of migration similar of that previously observed in mice.

Thermal energetics of the New-Guinean moss-forest rat (Rattus niobe) in comparison with other tropical murid rodents.

The thermal energetics of rodents from cool, wet tropical highlands are poorly known. Metabolic rate, body temperature and thermal conductance were measured in the moss-forest rat, Rattus niobe (Rodentia), a small murid endemic to the highlands of New Guinea. These data were evaluated in the context of the variation observed in the genus Rattus and among tropical murids. In 7 adult R. niobe, basal metabolic rate (BMR) averaged 53.6±6.6mLO2h(-1), or 103% of the value predicted for a body mass of 42.3±5.8g. Compared to other species of Rattus, R. niobe combines a low body temperature (35.5±0.6°C) and a moderately low minimal wet thermal conductance cmin (5.88±0.7mLO2h(-1)°C(-1), 95% of predicted) with a small size, all of which lead to reduced energy expenditure in a constantly cool environment. The correlations of mean annual rainfall and temperature, altitude and body mass with BMR, body temperature and cmin were analyzed comparatively among tropical Muridae. Neither BMR, nor cmin or body temperature correlated with ambient temperature or altitude. Some of the factors which promote high BMR in higher latitude habitats, such as seasonal exposure to very low temperature and short reproductive season, are lacking in wet montane tropical forests. BMR increased with rainfall, confirming a pattern observed among other assemblages of mammals. This correlation was due to the low BMR of several desert adapted murids, while R. niobe and other species from wet habitats had a moderate BMR.

O etil-2-cianoacrilato como selante após ressecção parcial de ceco em rattus norvegicus albinus

OBJETIVO: Avaliar a utilização do etil-2-cianoacrilato no tratamento de uma lesão provocada em um segmento parcialmente excluso do intestino do rato: o ceco. MÉTODOS: Utilizaram-se 45 ratos machos da linhagem Wistar, distribuidos em três grupos iguais, sendo que foi realizada a ressecção parcial do ceco. Os grupos foram denominados como: Grupo 1: a lesão foi tratada com aplicação de etil-2-cianoacrilato; Grupo 2: sutura e aplicação de etil-2-cianoacrilato; Grupo 3: sutura em bolsa. Os animais foram acompanhados no pós-operatório e metade de cada grupo foi necropsiada no 14º e restante no 28º pós-operatório. Dessa forma, foram submetidos à avaliação macroscópica, sendo coletadas amostras do ceco para avaliação histológica e, por fim, realizou-se a análise estatística RESULTADOS: O ganho de peso pós-experimento foi diferente nos grupos (p=0,028). A presença de microabcessos foi maior no 28º dia de pós-operatório no grupo 2, em comparação com o grupo 3 (p=0,003). A deposição de colágeno no 28º dia de pós-operatório foi maior no grupo 1 (p=0,036) e a intensidade da inflamação no 14º dia de pós-operatório foi maior no grupo 1 (p=0,045). Nos demais parâmetros avaliados, não ocorreu diferença estatística. CONCLUSÃO: A utilização do etil-2-cianoacrilato foi efetiva no tratamento do coto cecal excluso de ratos frente à avaliação macroscópica, microscópica e evolução pós-operatória.

Panic-like defensive behavior but not fear-induced antinociception is differently organized by dorsomedial and posterior hypothalamic nuclei of Rattus norvegicus (Rodentia, Muridae)

The hypothalamus is a forebrain structure critically involved in the organization of defensive responses to aversive stimuli. Gamma-aminobutyric acid (GABA)ergic dysfunction in dorsomedial and posterior hypothalamic nuclei is implicated in the origin of panic-like defensive behavior, as well as in pain modulation. The present study was conducted to test the difference between these two hypothalamic nuclei regarding defensive and antinociceptive mechanisms. Thus, the GABA A antagonist bicuculline (40 ng/0.2 µL) or saline (0.9% NaCl) was microinjected into the dorsomedial or posterior hypothalamus in independent groups. Innate fear-induced responses characterized by defensive attention, defensive immobility and elaborate escape behavior were evoked by hypothalamic blockade of GABA A receptors. Fear-induced defensive behavior organized by the posterior hypothalamus was more intense than that organized by dorsomedial hypothalamic nuclei. Escape behavior elicited by GABA A receptor blockade in both the dorsomedial and posterior hypothalamus was followed by an increase in nociceptive threshold. Interestingly, there was no difference in the intensity or in the duration of fear-induced antinociception shown by each hypothalamic division presently investigated. The present study showed that GABAergic dysfunction in nuclei of both the dorsomedial and posterior hypothalamus elicit panic attack-like defensive responses followed by fear-induced antinociception, although the innate fear-induced behavior originates differently in the posterior hypothalamus in comparison to the activity of medial hypothalamic subdivisions.

Padronização da avaliação da função renal de ratos (Rattus norvegicus) Wistar do biotério da Universidade Federal de Juiz de Fora

Introdução: Há grande interesse na utilização de modelos animais na pesquisa da fisiopatologia renal, que requer padronização dos parâmetros analisados. Objetivo: Padronizar avaliação da função renal de ratos da colônia do biotério do Centro de Biologia da Reprodução da Universidade Federal de Juiz de Fora. Métodos: Foram utilizados 30 ratos Wistar e realizadas dosagens de creatinina (sérica e urinária), ureia sérica e proteinúria. Foram avaliados: o intervalo de coleta de urina nas gaiolas metabólicas (24 horas ou 12 horas); a necessidade de jejum de 12 horas; a necessidade de desproteinização das amostras de urina e soro para dosagens de creatinina; necessidade de desproteinização do soro de animais com injúria renal aguda (IRA) para leitura em espectrofotômetro e ELISA, além da comparação da proteinúria de 24 horas (PT 24 horas) com a relação proteína/creatinina (rP/C). Os resultados foram comparados pelos teste t de Student, correlação de Pearson, gráfico de Bland-Altman para concordância e modelo de regressão linear para estimar a PT 24 horas a partir da rP/C. Resultados: A diurese de 24 horas foi maior do que a de 12 horas, interferindo na depuração da creatinina. No grupo em jejum, houve menor ingestão hídrica e menor creatinina urinária. Houve grande variabilidade para o soro desproteinizado e as leituras realizadas nos dois equipamentos foram semelhantes. Houve forte correlação entre PT 24 horas e rP/C e foi gerada a equação: PT 24 horas = (8,6113 x rP/C) + 1,0869. Conclusão: Foi padronizada: coleta de urina em 24 horas sem jejum. A desproteinização não mostrou benefício. As dosagens foram realizadas com confiabilidade em espectrofotômetro. Foi gerada uma fórmula prática para estimar PT 24 horas por meio da rP/C.

Anticoagulant resistance in Norway rats (Rattus norvegicus Berk.) in Kent - a VKORC1 single nucleotide polymorphism, tyrosine139phenylalanine, new to the UK

A sample of 10 Norway rats (Rattus norvegicus) was taken for DNA resistance testing from an agricultural site in Kent where applications of the anticoagulant rodenticide bromadiolone had been unsuccessful. All animals tested were homozygous for the single nucleotide VKORC1 polymorphism tyrosine139phenylalanine, or Y139F. This is a common resistance mutation found extensively in France and Belgium but not previously in the UK. Y139F confers a significant level of resistance to first-generation anticoagulants, such as chlorophacinone, and to the second-generation compound bromadiolone. Another compound widely used in the UK, difenacoum, is also thought to be partially resisted by rats which carry Y139F. A silent VKORC1 mutation was also found in all rats tested. The presence of a third important VKORC1 mutation which confers resistance to anticoagulant rodenticides in widespread use in the UK, the others being Y139C and L120Q, further threatens the ability of pest control practitioners to deliver effective rodent control.

Natal nest locations of the Asian house rat (Rattus tanezumi) in lowland rice–coconut cropping systems: a coconut penthouse or rice bunds with water frontage?

CONTEXT. Rattus tanezumi is a serious crop pest within the island of Luzon, Philippines. In intensive flood-irrigated rice field ecosystems of Luzon, female R. tanezumi are known to primarily nest within the tillers of ripening rice fields and along the banks of irrigation canals. The nesting habits of R. tanezumi in complex rice–coconut cropping systems are unknown. AIMS. To identify the natal nest locations of R. tanezumi females in rice–coconut systems of the Sierra Madre Biodiversity Corridor (SMBC), Luzon, during the main breeding season to develop a management strategy that specifically targets their nesting habitat. METHODS. When rice was at the booting to ripening stage, cage-traps were placed in rice fields adjacent to coconut habitat. Thirty breeding adult R. tanezumi females were fitted with radio-collars and successfully tracked to their nest sites. KEY RESULTS. Most R. tanezumi nests (66.7%) were located in coconut groves, five nests (16.7%) were located in rice fields and five nests (16.7%) were located on the rice field edge. All nests were located above ground level and seven nests were located in coconut tree crowns. The median distance of nest sites to the nearest rice field was 22.5m. Most nest site locations had good cover of ground vegetation and understorey vegetation, but low canopy cover. Only one nest location had an understorey vegetation height of less than 20 cm. CONCLUSIONS. In the coastal lowland rice–coconut cropping systems of the SMBC, female R. tanezumi showed a preference for nesting in adjacent coconut groves. This is contrary to previous studies in intensive flood-irrigated rice ecosystems of Luzon, where the species nests mainly in the banks of irrigation canals. It is important to understand rodent breeding ecology in a specific ecosystem before implementing appropriate management strategies. IMPLICATIONS. In lowland rice–coconut cropping systems, coconut groves adjacent to rice fields should be targeted for the 20 management of R. tanezumi nest sites during the main breeding season as part of an integrated ecologically based approach to rodent pest management.

Population ecology of the Asian house rat (Rattus tanezumi) in complex lowland agroecosystems in the Philippines

Context. Rattus tanezumi (the Asian house rat) is the principal rodent pest of rice and coconut crops in the Philippines. Little is known about the population and breeding ecology of R. tanezumi in complex agroecosystems; thus, current methods of rodent control may be inappropriate or poorly implemented. Aims. To investigate the habitat use, population dynamics and breeding biology of R. tanezumi in complex lowland agroecosystems of the Sierra Madre Biodiversity Corridor, Luzon, and to develop ecologically based rodent management (EBRM) strategies that will target specific habitats at specific times to improve cost-efficiency and minimise non-target risks. Methods. An 18-month trapping study was conducted in rice monoculture, rice adjacent to coconut, coconut groves, coconut-based agroforest and forest habitats. Trapped animals were measured, marked and assessed for breeding condition. Key results. Five species of rodent were captured across all habitats with R. tanezumi the major pest species in both the rice and coconut crops. The stage of the rice crop was a major factor influencing the habitat use and breeding biology of R. tanezumi. In rice fields, R. tanezumi abundance was highest during the tillering to ripening stages of the rice crop and lowest during the seedling stage, whereas in coconut groves abundance was highest from the seedling to tillering stage of nearby rice crops. Peaks in breeding activity occurred from the booting stage of the rice crop until just after harvest, but >10% of females were in breeding condition at each month of the year. Conclusions. In contrast with the practices applied by rice farmers in the study region, the most effective time for lethal management based on the breeding ecology of R. tanezumi is likely to be during the early stages of the rice crop, before the booting stage. Farmers generally apply control actions as individuals. We recommend coordinated community action. Continuous breeding throughout the year may necessitate two community campaigns per rice cropping season. To limit population growth, the most effective time to reduce nesting habitat is from the booting stage until harvest. Implications. By adopting EBRM strategies, we expect a reduction in costs associated with rodent control, as well as improved yield and reduced risk to non-target species.