Regulation of HIF-1α and p53 in stress responses in the subterranean rodents Lasiopodomys mandarinus and Lasiopodomys brandtii (Rodentia: Cricetidae)

The response mechanism and interaction patterns of HIF-1α and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1α and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1α and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1α and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1α and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus. Correlation analysis revealed that HIF-1α expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii, both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii. We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1α in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.

Regulation of HIF-1 and p53 in stress responses in the subterranean rodents Lasiopodomys mandarinus and Lasiopodomys brandtii (Rodentia: Cricetidae)

ABSTRACT The response mechanism and interaction patterns of HIF-1 and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1 and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1 and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1 and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1 and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus. Correlation analysis revealed that HIF-1 expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii, both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii. We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1 in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.

Regulation of HIF-1α and p53 in stress responses in the subterranean rodents Lasiopodomys mandarinus and Lasiopodomys brandtii (Rodentia: Cricetidae)

The response mechanism and interaction patterns of HIF-1α and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1α and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1α and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1α and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1α and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus. Correlation analysis revealed that HIF-1α expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii, both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii. We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1α in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.(AU)

No fitness costs are induced by Spiroplasma infections of Aphis citricidus reared on two different host plants / Custo adaptativo induzido por Spiroplasma em Aphis citricidus em duas plantas hospedeiras

Aphids can harbor several secondary symbionts that alter important aphid-related ecological traits, such as defense against natural enemies, heat tolerance and host plant utilization. One of these secondary symbionts, Spiroplasma, is well known in Drosophila as a sex modulator and by interacting with the host immune system. However, little is known on the effects of Spiroplasma on aphids, such as its influence on the host immune defense against fungi and on host plant utilization. Aphid infections by Spiroplasma are known to be low and few aphid species were reported to be infected with this secondary symbiont, however aphids belonging to the genus Aphis in neotropical regions show high infection rates by Spiroplasma. Thus, we investigated the association of Spiroplasma with the tropical aphid Aphis citricidus through comparative biology experiments on two host plants with different nutritional value to the aphid. We demonstrate Spiroplasma induced no significant fitness costs to A. citricidus on either host plant as no changes in the fitness traits we assessed were observed. Spiroplasma infection only induced sutle changes on host longevity and fecundity. Therefore, we concluded Spiroplasma established a neutral interaction with A. citricidus under the selection pressure we tested, and argue on stress conditions that could better demonstrate the role of Spiroplasma in A. citricidus bioecology and associated costs involved.(AU)

Pulgões podem abrigar vários simbiontes secundários que alteram características ecológicas importantes, como defesa contra inimigos naturais, tolerância ao calor e utilização da planta hospedeira. Um desses simbiontes secundários, Spiroplasma, é estudado em Drosophila por alterar a razão sexual e interagir com o sistema imunológico do hospedeiro. No entanto, pouco se sabe sobre os efeitos do Spiroplasma em pulgões, como sua influência na defesa contra fungos entomopatogénicos ou na utilização da planta hospedeira, por exemplo. Spiroplasma foi identificado em poucas espécies de pulgão e geralmente em baixa densidade, contudo pulgões pertencentes ao gênero Aphis em regiões neotropicais apresentam altas taxas de infecção por Spiroplasma. Assim, investigamos a associação entre Spiroplasma e o pulgão neotropical Aphis citricidus por meio de biologia comparativa em duas plantas hospedeiras com diferentes valores nutricionais para o pulgão. Spiroplasma não causou custo adaptativo significativo para A. citricidus em ambas planta hospedeira. A infecção por Spiroplasma induziu apenas pequenas mudanças na longevidade e fecundidade do hospedeiro. Portanto, concluímos que Spiroplasma estabeleceu uma interação neutra com A. citricidus sob ausência de pressão de seleção. Entretanto, discutimos sobre condições de estresse que possam demonstrar o papel de Spiroplasma na bioecologia de A. citricidus e os possíveis custos envolvidos.(AU)

No fitness costs are induced by Spiroplasma infections of Aphis citricidus reared on two different host plants

Abstract Aphids can harbor several secondary symbionts that alter important aphid-related ecological traits, such as defense against natural enemies, heat tolerance and host plant utilization. One of these secondary symbionts, Spiroplasma, is well known in Drosophila as a sex modulator and by interacting with the host immune system. However, little is known on the effects of Spiroplasma on aphids, such as its influence on the host immune defense against fungi and on host plant utilization. Aphid infections by Spiroplasma are known to be low and few aphid species were reported to be infected with this secondary symbiont, however aphids belonging to the genus Aphis in neotropical regions show high infection rates by Spiroplasma. Thus, we investigated the association of Spiroplasma with the tropical aphid Aphis citricidus through comparative biology experiments on two host plants with different nutritional value to the aphid. We demonstrate Spiroplasma induced no significant fitness costs to A. citricidus on either host plant as no changes in the fitness traits we assessed were observed. Spiroplasma infection only induced sutle changes on host longevity and fecundity. Therefore, we concluded Spiroplasma established a neutral interaction with A. citricidus under the selection pressure we tested, and argue on stress conditions that could better demonstrate the role of Spiroplasma in A. citricidus bioecology and associated costs involved.

Resumo Pulgões podem abrigar vários simbiontes secundários que alteram características ecológicas importantes, como defesa contra inimigos naturais, tolerância ao calor e utilização da planta hospedeira. Um desses simbiontes secundários, Spiroplasma, é estudado em Drosophila por alterar a razão sexual e interagir com o sistema imunológico do hospedeiro. No entanto, pouco se sabe sobre os efeitos do Spiroplasma em pulgões, como sua influência na defesa contra fungos entomopatogénicos ou na utilização da planta hospedeira, por exemplo. Spiroplasma foi identificado em poucas espécies de pulgão e geralmente em baixa densidade, contudo pulgões pertencentes ao gênero Aphis em regiões neotropicais apresentam altas taxas de infecção por Spiroplasma. Assim, investigamos a associação entre Spiroplasma e o pulgão neotropical Aphis citricidus por meio de biologia comparativa em duas plantas hospedeiras com diferentes valores nutricionais para o pulgão. Spiroplasma não causou custo adaptativo significativo para A. citricidus em ambas planta hospedeira. A infecção por Spiroplasma induziu apenas pequenas mudanças na longevidade e fecundidade do hospedeiro. Portanto, concluímos que Spiroplasma estabeleceu uma interação neutra com A. citricidus sob ausência de pressão de seleção. Entretanto, discutimos sobre condições de estresse que possam demonstrar o papel de Spiroplasma na bioecologia de A. citricidus e os possíveis custos envolvidos.

No fitness costs are induced by Spiroplasma infections of Aphis citricidus reared on two different host plants

Abstract Aphids can harbor several secondary symbionts that alter important aphid-related ecological traits, such as defense against natural enemies, heat tolerance and host plant utilization. One of these secondary symbionts, Spiroplasma, is well known in Drosophila as a sex modulator and by interacting with the host immune system. However, little is known on the effects of Spiroplasma on aphids, such as its influence on the host immune defense against fungi and on host plant utilization. Aphid infections by Spiroplasma are known to be low and few aphid species were reported to be infected with this secondary symbiont, however aphids belonging to the genus Aphis in neotropical regions show high infection rates by Spiroplasma. Thus, we investigated the association of Spiroplasma with the tropical aphid Aphis citricidus through comparative biology experiments on two host plants with different nutritional value to the aphid. We demonstrate Spiroplasma induced no significant fitness costs to A. citricidus on either host plant as no changes in the fitness traits we assessed were observed. Spiroplasma infection only induced sutle changes on host longevity and fecundity. Therefore, we concluded Spiroplasma established a neutral interaction with A. citricidus under the selection pressure we tested, and argue on stress conditions that could better demonstrate the role of Spiroplasma in A. citricidus bioecology and associated costs involved.

Resumo Pulgões podem abrigar vários simbiontes secundários que alteram características ecológicas importantes, como defesa contra inimigos naturais, tolerância ao calor e utilização da planta hospedeira. Um desses simbiontes secundários, Spiroplasma, é estudado em Drosophila por alterar a razão sexual e interagir com o sistema imunológico do hospedeiro. No entanto, pouco se sabe sobre os efeitos do Spiroplasma em pulgões, como sua influência na defesa contra fungos entomopatogénicos ou na utilização da planta hospedeira, por exemplo. Spiroplasma foi identificado em poucas espécies de pulgão e geralmente em baixa densidade, contudo pulgões pertencentes ao gênero Aphis em regiões neotropicais apresentam altas taxas de infecção por Spiroplasma. Assim, investigamos a associação entre Spiroplasma e o pulgão neotropical Aphis citricidus por meio de biologia comparativa em duas plantas hospedeiras com diferentes valores nutricionais para o pulgão. Spiroplasma não causou custo adaptativo significativo para A. citricidus em ambas planta hospedeira. A infecção por Spiroplasma induziu apenas pequenas mudanças na longevidade e fecundidade do hospedeiro. Portanto, concluímos que Spiroplasma estabeleceu uma interação neutra com A. citricidus sob ausência de pressão de seleção. Entretanto, discutimos sobre condições de estresse que possam demonstrar o papel de Spiroplasma na bioecologia de A. citricidus e os possíveis custos envolvidos.

RESPOSTAS ECOTOXICOLÓGICAS EM CHIRONOMIDAE (DIPTERA): UMA ABORDAGEM FISIOLÓGICA E EVOLUTIVA

A sobrevivência é o maior desafio enfrentado por organismos que habitam ambientes constantemente degradados pela ação antrópica, muitos deles o vencem porém com custos biológicos da exposição. O objetivo da tese foi avaliar as respostas de larvas de Chironomidae sob desafios da sobrevivência em degradação ambiental através de biomarcadores. Primeiramente bioensaios de toxicidade crônica foram realizados em larvas de Chironomus sancticaroli expostas a sedimentos provindos de 5 rios e 5 reservatórios do estado de São Paulo, nessas larvas foram avaliados as respostas de biomarcadores como AChE (Acetilcolinesterase), EST- (Esterase alfa), EST- (Esterase beta), GST (Glutationa S-transferase), CAT (Catalase), SOD (Superóxido-dismutase), LPO (lipoperoxidação) e alterações histológicas. Além disso, larvas de Chironomus dilutus foram expostas em um respirômetro por 6 horas a 4 concentrações de arsênio e oxigênio dissolvido e suas combinações resultando em 16 tratamentos. Nesses organismos além do consumo de oxigênio em exposição ao arsênio, foi avaliado para todas as combinações a expressão gênica das hemoglobinas A, B, C, D e a enzima GST. Por fim, 12 espécies distribuídas em Chironomus, Dicrotendipes e Goeldichironomus foram expostas por 48 horas ao malathion e ao propuxur, nesses organismos foi mensurado a atividade das enzimas AChE, EST- e EST-. Com a resposta enzimática foi aplicado as métricas K e para detecção de sinal filogenético, juntamente com uma filogenia baseada no COI (citocromo oxidase I), além disso respostas de espécies iguais coletadas em locais diferentes foram comparadas para verificar o efeito da pressão de seleção. Para C. sancticaroli exposta ao sedimentos, todas as enzimas apresentaram alterações em relação ao grupo controle, além de estresse oxidativo e a histologia demonstrou efeitos principalmente no corpo gorduroso visceral. Em C. dilutus houve um aumento no consumo de oxigênio em exposição ao arsênio e aumento na expressão da HbA na exposição ao arsênio, HbB em arsênio e hipóxia, Hb A, D e GST na combinações das duas condições. Nas 13 espécies de Chironomidae expostas a pesticidas, não existe sinal filogenético para a respostas da enzimas, mas para as espécies de Chironomus foi observado uma tendência para as enzimas AChE e EST-. A pressão de seleção se mostrou o principal direcionador das respostas enzimáticas já que mesmas espécies coletadas em locais diferentes, apresentaram níveis diferenciados de atividade. Larvas de Chironomidae possuem uma considerável plasticidade fisiológica que permite-os sobreviver nesse ambientes desafiadores, mesmo sem mortalidade, alterações foram detectadas demonstrando desequilíbrios da homeostase. Mesmo com a pressão de seleção que esses organismos sofrem no ambiente natural, eles se mantém vivos e resistentes, esse quadro pode refletir em algum custo no fitness das espécies a longo prazo.

Survival is the biggest challenge faced by organisms inhabiting environments constantly degraded by anthropic activities. Several organisms can thrive but they have biological costs of exposure. The aim of the thesis was evaluate the chironomids larvae responses under survival challenges of environmental degradation using biomarkers. First, chronic bioassays were carried out in Chironomus sancticaroli larvae exposed to sediments of 5 rivers and 5 reservoirs from São Paulo State. It was measured in these larvae biomarkers as AChE (Acetylcholinesterase), EST- (alpha-esterase), EST- (beta-esterase), GST (Glutathione S-transferase), CAT (Catalase), SOD (Superoxide-dismutase), LPO (lipid peroxidation) and histopathologies. In addition, Chironomus dilutus larvae were exposed in a respirometer for 6 hours to 4 concentrations of arsenic and dissolved oxygen and their combinations resulting in 16 treatments. Beyond oxygen consumption in arsenic exposure, in the combinations were measured gene expression of A, B, C, D hemoglobins and GST enzyme. Finally, 12 species of Chironomus, Dicrotendipes, and Goeldichironomus were exposed for 48 hours to malathion and propoxur pesticides. The activity of AChE, EST- e EST- was measured, and in the results was applied K and metrics to phylogenetic signal detection also using a phylogeny based in COI gene (cytochrome oxidase I). The responses from same species collected in different sites were compared to verify selection pressure influence. In C. santicaroli exposed to sediments, all enzymes showed alterations comparing with control group, also was detected oxidative stress and tissues changes in visceral fat body. In C. dilutus there was an increase of oxygen consumption in arsenic exposure, also was observed increase of HbA expression (arsenic exposure), HbB (arsenic and hypoxia) and HbA, D, GST in combinations of both conditions. Throughout of 13 chironomids species exposed to pesticides, there was no phylogenetic signal to enzymes responses, but to Chironomus species there was a trend to AChE and EST- enzymes. Selection pressure showed the main driver of enzymatic responses due to the fact same species collected in different sites had no similar levels of activity. Chironomidae larvae have a remarkable physiological plasticity that allows them to survive in challenging environments, even mortality being not observed changes were detected demonstrating homeostasis imbalance. In the environment, even suffering with selection pressure, chrinomids are alive and resistants, this status can reflect in some fitness cost of this species in a long-term.