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Pesticides employed worldwide for crop protection easily reach aquatic systems, which act as the main reservoirs, and become a risk factor for aquatic fauna. Fipronil is a broad-spectrum insecticide acting on the insect nervous system; however, other effects and systems unrelated to this mechanism could be affected in non-target organisms. Thus, the present study aimed to assess the impact of fipronil on the suborganismal response (gene expression and enzymatic activity) of Chironomus riparius larvae as a model organism in ecotoxicology. To this end, short-term toxicity tests were carried out with fourth-instar larvae exposed to 0.001, 0.01, and 0.1 µg L-1 of fipronil for 24 and 96 h. Messenger RNA levels of 42 genes related to diverse metabolic pathways were analyzed by real-time polymerase chain reaction, complemented with catalase (CAT), glutathione S-transferase (GST), and acetylcholinesterase (AChE) activities. Few effects were observed at 24 h; however, after longer exposure (96 h), genes involved in the endocrine, detoxification, stress, and immune response pathways were altered. Moreover, fipronil at 96 h increased CAT and GST activity at 0.01 µg L-1 and AChE at the highest concentrations. The results demonstrate that even low environmentally relevant fipronil concentrations can modulate the molecular response of several cellular pathways in C. riparius after short-term exposure. These results bring new information about the underlying response of fipronil and its mode of action on a key aquatic invertebrate. Despite no effects on mortality, strong modulation at the suborganismal level emphasizes the advantage of biomarkers as early damage responses and the harmful impact of this pesticide on freshwater organisms. Environ Toxicol Chem 2024;43:405-417. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

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Rumen fermentation and methanogenesis are vital metabolic processes in cattle and are carried out by microbial populations that are affected by dietary factors such as secondary metabolites, nutritional composition and degradability. The aim of this study was to monitor populations of total bacteria, total methanogens and Butirivibrio fibrisolvens in the rumen of Lucerne heifers fed on diets typical of intensive silvopastoral systems (ISS) or of a traditional (control) system. Rumen contents (RC) were collected orally from eight heifers consuming 100% Cynodon plectostachyus (control) and 76% C. plectostachyus + 24% Leucaena leucocephala (ISS) following a crossover design and DNA was extracted and quantified by quantitative PCR. Populations [Log10 (ng g-1 RC)] were 5.6 and 5.8 for total bacteria (p = 0.5343), 3.6 and 3.5 for B. fibrisolvens (p = 0.4742) and 5.0 and 5.3 for total methanogens (p = 0.2661) respectively in control and ISS diets. However, when measured in a separate parallel study, enteric methane emissions (g kg-1 of fermented dry matter) were significantly reduced with the inclusion of L. leucocephala. This fact indicated the importance of investigating the structure, function and interactions of populations beyond quantitative analysis to determine how diet affects rumen microbial populations and their function.(AU)

A fermentação ruminal e metanogênisis são processos metabólicos vitais para os rumianteso e são realizados por populações microbianas afetados por fatores dietéticos, como a presença de metabólitos secundários, composição nutricional e degradabilidade. O objetivo deste estudo foi monitorar as populações de bactérias totais, metanogênicas e Butyrivibrio fibrisolvens no rúmen de novilhas Lucerna alimentadas com dietas típicas de sistemas silvopastoris intensivos (SSI) ou de um sistema tradicional (controle). Conteúdo do rúmen (CR) foram recolhidos por via oral de oito novilhas consumindo 100% Cynodon plectostachyus (controle) e 76% C. plectostachyus + 24% Leucaena leucocephala (SSI), após um estudo cruzado o DNA foi extraído e quantificado por PCR quantitativo. Populações [Log10 (ng g-1 CR)] foram de 5,6 e 5,8 para as bactérias totais (p = 0,5343), 3,6 e 3,5 para B. fibrisolvens (p = 0,4742) e 5,0 e 5,3 para o total metanogênicas (p = 0,2661) para o controle e dietas ISS, respectivamente. No entanto, quando medida em um estudo paralelo, as emissões de metano entérico (g kg-1 de matéria seca fermentada) foram significativamente reduzidas com a inclusão de leucena. Isso indica a importância de investigar a estrutura, função e interações de populações além da análise quantitativa para determinar como a dieta afeta populações microbianas no rúmen e sua função.(AU)

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Rumen fermentation and methanogenesis are vital metabolic processes in cattle and are carried out by microbial populations that are affected by dietary factors such as secondary metabolites, nutritional composition and degradability. The aim of this study was to monitor populations of total bacteria, total methanogens and Butirivibrio fibrisolvens in the rumen of Lucerne heifers fed on diets typical of intensive silvopastoral systems (ISS) or of a traditional (control) system. Rumen contents (RC) were collected orally from eight heifers consuming 100% Cynodon plectostachyus (control) and 76% C. plectostachyus + 24% Leucaena leucocephala (ISS) following a crossover design and DNA was extracted and quantified by quantitative PCR. Populations [Log10 (ng g-1 RC)] were 5.6 and 5.8 for total bacteria (p = 0.5343), 3.6 and 3.5 for B. fibrisolvens (p = 0.4742) and 5.0 and 5.3 for total methanogens (p = 0.2661) respectively in control and ISS diets. However, when measured in a separate parallel study, enteric methane emissions (g kg-1 of fermented dry matter) were significantly reduced with the inclusion of L. leucocephala. This fact indicated the importance of investigating the structure, function and interactions of populations beyond quantitative analysis to determine how diet affects rumen microbial populations and their function.

A fermentação ruminal e metanogênisis são processos metabólicos vitais para os rumianteso e são realizados por populações microbianas afetados por fatores dietéticos, como a presença de metabólitos secundários, composição nutricional e degradabilidade. O objetivo deste estudo foi monitorar as populações de bactérias totais, metanogênicas e Butyrivibrio fibrisolvens no rúmen de novilhas Lucerna alimentadas com dietas típicas de sistemas silvopastoris intensivos (SSI) ou de um sistema tradicional (controle). Conteúdo do rúmen (CR) foram recolhidos por via oral de oito novilhas consumindo 100% Cynodon plectostachyus (controle) e 76% C. plectostachyus + 24% Leucaena leucocephala (SSI), após um estudo cruzado o DNA foi extraído e quantificado por PCR quantitativo. Populações [Log10 (ng g-1 CR)] foram de 5,6 e 5,8 para as bactérias totais (p = 0,5343), 3,6 e 3,5 para B. fibrisolvens (p = 0,4742) e 5,0 e 5,3 para o total metanogênicas (p = 0,2661) para o controle e dietas ISS, respectivamente. No entanto, quando medida em um estudo paralelo, as emissões de metano entérico (g kg-1 de matéria seca fermentada) foram significativamente reduzidas com a inclusão de leucena. Isso indica a importância de investigar a estrutura, função e interações de populações além da análise quantitativa para determinar como a dieta afeta populações microbianas no rúmen e sua função.

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OBJECTIVES: The aim of the present study was to determine the Chlamydia trachomatis prevalence and to identify the demographic, behavioural and clinical factors associated with C. trachomatis in human immunodeficiency virus infected men. STUDY: This was a cross-sectional study of C. trachomatis prevalence among human immunodeficiency virus-infected men enrolled at the Outpatient clinic of acquired immunodeficiency syndrome of the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado in Manaus, Amazonas, Brazil. C. trachomatis deoxyribonucleic acid from urethral samples was purified and submitted to real time polymerase chain reaction to identify the presence of C. trachomatis. RESULTS: A total of 276 human immunodeficiency virus-infected men were included in the study. The prevalence of C. trachomatis infection was 12% (95% confidence interval 8.1%-15.7%). The mean age of the participants was 34.63 (standard deviation 10.80) years. Of the 276 human immunodeficiency virus-infected men, 93 (56.2%) had more than one sexual partner in the past year and 105 (38.0%) reported having their first sexual intercourse under the age of 15 years. Men having sex with men and bisexuals amounted to 61.2% of the studied population. A total of 71.7% had received human immunodeficiency virus diagnosis in the last three years and 55.1% were using antiretroviral therapy. Factors associated with C. trachomatis infection in the logistic model were being single (p<0.034), men having sex with men (p<0.021), and having previous sexually transmitted diseases (p<0.001). CONCLUSION: The high prevalence of C. trachomatis infection among human immunodeficiency virus-infected men highlights that screening human immunodeficiency virus-infected men for C. trachomatis, especially among men having sex with men, is paramount to control the spread of C. trachomatis infection. .

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OBJECTIVES: The aim of the present study was to determine the Chlamydia trachomatis prevalence and to identify the demographic, behavioural and clinical factors associated with C. trachomatis in human immunodeficiency virus infected men. STUDY: This was a cross-sectional study of C. trachomatis prevalence among human immunodeficiency virus-infected men enrolled at the Outpatient clinic of acquired immunodeficiency syndrome of the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado in Manaus, Amazonas, Brazil. C. trachomatis deoxyribonucleic acid from urethral samples was purified and submitted to real time polymerase chain reaction to identify the presence of C. trachomatis. RESULTS: A total of 276 human immunodeficiency virus-infected men were included in the study. The prevalence of C. trachomatis infection was 12% (95% confidence interval 8.1%-15.7%). The mean age of the participants was 34.63 (standard deviation 10.80) years. Of the 276 human immunodeficiency virus-infected men, 93 (56.2%) had more than one sexual partner in the past year and 105 (38.0%) reported having their first sexual intercourse under the age of 15 years. Men having sex with men and bisexuals amounted to 61.2% of the studied population. A total of 71.7% had received human immunodeficiency virus diagnosis in the last three years and 55.1% were using antiretroviral therapy. Factors associated with C. trachomatis infection in the logistic model were being single (p<0.034), men having sex with men (p<0.021), and having previous sexually transmitted diseases (p<0.001). CONCLUSION: The high prevalence of C. trachomatis infection among human immunodeficiency virus-infected men highlights that screening human immunodeficiency virus-infected men for C. trachomatis, especially among men having sex with men, is paramount to control the spread of C. trachomatis infection.

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