Specific gut bacterial responses to natural diets of tropical birds

The composition of gut bacterial communities is strongly influenced by the host diet in many animal taxa. For birds, the effect of diet on the microbiomes has been documented through diet manipulation studies. However, for wild birds, most studies have drawn on literature-based information to decipher the dietary effects, thereby, overlooking individual variation in dietary intake. Here we examine how naturally consumed diets influence the composition of the crop and cloacal microbiomes of twenty-one tropical bird species, using visual and metabarcoding-based identification of consumed diets and bacterial 16S rRNA microbiome sequencing. We show that diet intakes vary markedly between individuals of the same species and that literature-based dietary guilds grossly underestimate intraspecific diet variability. Furthermore, despite an effect of literature-based dietary guild assignment of host taxa, the composition of natural diets does not align with crop and cloacal microbiome similarity. However, host-taxon specific gut bacterial lineages are positively correlated with specific diet items, indicating that certain microbes associate with different diet components in specific avian hosts. Consequently, microbiome composition is not congruent with the overall consumed diet composition of species, but specific components of a consumed diet lead to host-specific effects on gut bacterial taxa.

Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium Microcystis

Cyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manipulation experiments to investigate the combined effects of dietary PUFA and warming on the proportions of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) in Chironomus riparius. The experimental diet consisted of a nontoxic cyanobacterium Microcystis, which contained C20 PUFA: 20:3n-3, 20:4n-3, and 20:3n-6, but no EPA or ARA. Additionally, we used TetraMin® fish flakes as a control treatment. A temperature increase from 20 °C to 25 °C decreased the proportion of n-3 C20 PUFA and the n-3/n-6 ratio in Microcystis. Diet manipulation experiments indicated that Chironomus desaturated dietary C20 precursors to EPA and ARA, but warming decreased this bioconversion and resulted in lower levels of EPA and ARA in Chironomus. Warming did not alter the proportions of EPA and ARA in Chironomus larvae if these PUFA were readily available in the diet (TetraMin® control treatment). In conclusion, warming and cyanobacteria dominance may decrease the production and trophic transfer of physiologically important PUFA in freshwaters by (1) decreasing the n-3/n-6 ratio and the abundance of n-3 C20 precursors in Microcystis, and (2) decreasing the bioconversion of n-3 and n-6 C20 precursors to EPA and ARA in chironomids. These changes may have cascading effects throughout the food web and decrease the content of EPA in fish, potentially affecting its availability to humans.

Utilização de Aditivos para Bovinos de Corte em Confinamento

Diante de grandes avanços em técnicas de nutrição, manejo, sanidade e melhoramento animal, o Brasil se consolidou líder em exportações de carnes. Assim, pesquisadores, técnicos e produtores têm procurado trabalhar em prol de melhorar a eficiência da fermentação ruminal, para aumentar a produção de propionato, e diminuir a metanogênese, a proteólise e a desaminação das proteínas do alimento no rúmen. Estas mudanças levam, positivamente, a melhoria na eficiência produtiva dos ruminantes. Essa eficiência pode ser alcançada através de melhorias nos índices zootécnicos, utilização e avaliação de raças mais produtivas aos diversos sistemas de produção utilizados no Brasil e, ainda, técnicas como a utilização de aditivos que são usados para melhorar a eficiência dos alimentos, estimulando o crescimento, e engorda dos animais dispostos, ou apenas para beneficiar, de alguma forma, a saúde e o metabolismo dos animais. Tentativas para alcançar a melhor eficiência são realizadas com técnicas de manipulação da dieta, assim, durante as últimas décadas, certo número de aditivos alimentares tem sido descoberto, e quando usados na alimentação dos ruminantes esses podem satisfazer alguns ou quase todos os objetivos em pesquisas. Sendo assim, a elaboração deste estudo se mostra necessária, buscando elucidar todos estes fatores preponderantes para a melhoria dos processos produtivos na nutrição de ruminantes. Palavras-chave: Nutrição de Ruminantes. Monoenzimas. Ionóforos. Abstract Considering major advances in nutrition, management techniques, and improving animal health, Brazil is a consolidated leader in meat exports. Thus, researchers, technicians and producers have sought to work towards improving the efficiency of ruminal fermentation, to increase the production of propionate, and decrease methanogenesis, proteolysis and the proteins deamination in food. This efficiency can be achieved through improvements in zootechnical indices, utilization and evaluation of more productive breeds to the various production systems used in Brazil, as well as techniques such as the use of additives that are used to improve food efficiency, stimulating growth, and fattening animals, or just to somehow benefit the animals’ health and metabolism. These changes lead, positively, to the improvement in ruminants’ production efficiency. Attempts to achieve the best efficiency are made with diet manipulation techniques, during the last decades a number of food additives have been discovered, and when used in the ruminants’ feeding can satisfy some or almost all the research objectives. Thus, this study is necessary, seeking to elucidate all these factors for the improvement of the production processes in ruminant nutrition. Keywords: Nutrition of Ruminants. Monoenzymes. Ionophores.

Flexibility and resilience of great tit (Parus major) gut microbiomes to changing diets

Background Gut microbial communities play important roles in nutrient management and can change in response to host diets. The extent of this flexibility and the concomitant resilience is largely unknown in wild animals. To untangle the dynamics of avian-gut microbiome symbiosis associated with diet changes, we exposed Parus major (Great tits) fed with a standard diet (seeds and mealworms) to either a mixed (seeds, mealworms and fruits), a seed, or a mealworm diet for 4 weeks, and examined the flexibility of gut microbiomes to these compositionally different diets. To assess microbiome resilience (recovery potential), all individuals were subsequently reversed to a standard diet for another 4 weeks. Cloacal microbiomes were collected weekly and characterised through sequencing the v4 region of the 16S rRNA gene using Illumina MiSeq. Results Initial microbiomes changed significantly with the diet manipulation, but the communities did not differ significantly between the three diet groups (mixed, seed and mealworm), despite multiple diet-specific changes in certain bacterial genera. Reverting birds to the standard diet led only to a partial recovery in gut community compositions. The majority of the bacterial taxa that increased significantly during diet manipulation decreased in relative abundance after reversion to the standard diet; however, bacterial taxa that decreased during the manipulation rarely increased after diet reversal Conclusions The gut microbial response and partial resilience to dietary changes support that gut bacterial communities of P. major play a role in accommodating dietary changes experienced by wild avian hosts. This may be a contributing factor to the relaxed association between microbiome composition and the bird phylogeny. Our findings further imply that interpretations of wild bird gut microbiome analyses from single-time point sampling, especially for omnivorous species or species with seasonally changing diets, should be done with caution. The partial community recovery implies that ecologically relevant diet changes (e.g., seasonality and migration) open up gut niches that may be filled by previously abundant microbes or replaced by different symbiont lineages, which has important implications for the integrity and specificity of long-term avian-symbiont associations.

Diet manipulation and post-moulting responses in caged commercial laying hens

Two hundred and fifty caged commercial laying hens were induced to moult through a 15-day feed "and water withdrawal programme. Immediate and subsequent effects on egg production and follicular developments were monitored. Results showed that moulted hens attained over 60% egg production after 6 weeks of feeding with increasing egg weight, Post-moulting egg quality values were similar bul globulin were significantly increased (P<0.05). Changes in liver and oviduct weights were significant (P<0.05) while gizzard, heart, lung and kidney showed no significant (P>0.05) effects. Fasting produced alretic follicles even though follicular number was not appreciably influenced. Follicles were larger with a yellow-yolky appearance during laying than at the fasting period. Mortality of 2.4% was recorded throughout the experimental period. Moulting is a feasible strategy for maintaining egg production in aged, low-producing commercial layers.

Importance of Redox Equilibrium in the Pathogenesis of Psoriasis—Impact of Antioxidant-Rich Diet

Psoriasis is a common, chronic, hyperproliferative, inflammatory skin disease occurring in most ethnic groups in the world. The disease is hereditary but the process of its inheritance is complex and still not fully understood. At the same time, it has been observed that psoriatic lesions may be triggered by certain prooxidative external factors: using narcotics, smoking, drinking alcohol, physical and mental stress, as well as bacterial infections and injury. Since the main physiological marker of psoriasis relates to disorders in the organism’s antioxidative system, it is necessary to develop a well-balanced combination of pharmaceuticals and dietary antioxidants to facilitate the effective treatment and/or prevention of the disease. The dietary sources of antioxidants must be adequate for chronic use regardless of the patient’s age and be easily available, e.g., as ingredients of regular food or dietary supplements. Diet manipulation is a promising therapeutic approach in the context of modulating the incidence of chronic diseases. Another potentially viable method entails the use of nutrigenomics, which guarantees a multiaspectual approach to the problem, including, in particular, analyses of the genetic profiles of psoriasis patients with the view to more accurately targeting key problems. The present paper pertains to the significance of redox equilibrium in the context of psoriasis. Based on information published in worldwide literature over the last decade, the impact of dietary exogenous antioxidants on the course of this chronic disease was analysed.

Flexibility and resilience of Great tit (Parus major) gut microbiomes to changing diets

Background: Gut microbial communities play important roles in nutrient management and can change in response to host diets. The extent of this flexibility and the concomitant resilience is largely unknown in wild animals. To begin untangling the dynamics of avian-gut microbiome symbiosis associated with diet changes, we exposed Parus major (Great tits) fed with a standard diet (seeds and mealworms) to either a mixed (seeds, mealworms and fruits), a seed, or a mealworm diet for four weeks, and examined the flexibility of gut microbiomes to these compositionally different diets. To assess microbiome resilience (recovery potential), all individuals were subsequently reversed to a standard diet for another four weeks. Cloacal microbiomes were collected weekly and characterised through sequencing the v4 region of the 16S rRNA gene using Illumina MiSeq. Results: Initial microbiomes changed significantly with the diet manipulation but the communities did not differ significantly between the three diet groups (mixed, seed and mealworm), despite multiple diet-specific changes of specific bacterial genera. Reverting birds to the standard diet led to only a partial recovery in gut community compositions. The majority of the bacterial taxa that increased significantly during diet manipulation decreased in relative abundances after reversion to the standard diet; however, bacterial taxa that decreased during the manipulation rarely increased after diet reversal.Conclusions: The gut microbial response and partial resilience to dietary changes support that gut bacterial communities of P. major play a role in accommodating dietary changes experienced by wild avian hosts. This may be a contributing factor to the relaxed association between microbiome composition and bird phylogeny. Our findings further imply that interpretations of wild bird gut microbiome analyses from single-time point sampling, especially for omnivorous species or species that have changing seasonal diets, should be done with caution. The partial community recovery implies that ecologically relevant diet changes (e.g., seasonality and migration) open up gut niches that may be filled by previously abundant microbes or replaced by different symbiont lineages, which has important implications for the integrity and specificity of long-term avian-symbiont associations.

Fatty acid metabolism and modifications in Chironomus riparius

A priori knowledge of fatty acid modifications in consumers is essential for studies using fatty acids as biomarkers. We investigated fatty acid metabolism and possible modification pathways in benthic invertebrate Chironomus riparius larvae (Diptera). We conducted diet manipulation experiments using natural food sources (two chlorophyte algae, a diatom and a non-toxic cyanobacterium). We also did a diet-switch experiment on two different resources, fish food flakes TetraMin ® and cyanobacterium Spirulina , to study fatty acid turnover in Chironomus . Results of the diet manipulation experiments indicate that Chironomus larvae have a strong tendency to biosynthesize 20:5n-3 and 20:4n-6 from precursor fatty acids, and that the dietary availability of polyunsaturated fatty acids (PUFA) does not control larval growth. Fatty acid modifications explain why low dietary availability of PUFA did not significantly limit growth. This has ecologically relevant implications on the role of benthic chironomids in conveying energy to upper trophic level consumers. A diet-switch experiment showed that the turnover rate of fatty acids in Chironomus is relatively fast––a few days. The compositional differences of algal diets were large enough to separate Chironomus larvae into distinct groups even if significant modification of PUFA was observed. In summary, fatty acids are excellent dietary biomarkers for Chironomus , if modifications of PUFA are considered, and will provide high-resolution data on resource use. This article is part of the theme issue ‘The next horizons for lipids as ‘trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.

Mediterranean Diet Reduces Monocyte Inflammatory Gene Expression and Influences Social Behavior in Nonhuman Primates

Western diet consumption is associated with inflammation, cardiometabolic disease, and mortality in humans, while Mediterranean diet consumption confers protective effects. One likely pathway for this association is through environmentally induced changes in monocyte function, yet the underlying mechanisms remain elusive. We conducted the first randomized, long-term diet manipulation in a non-human primate model to determine whether Western- or Mediterranean-like diets alter monocyte polarization and health. Monocyte gene expression profiles differed markedly between the two diet groups, with significant differences in over 40% of expressed genes. The Western diet induced a more proinflammatory monocyte phenotype overall and upregulated specific monocyte polarization genes. Diet also disrupted the coexpression of numerous gene pairs, including small RNAs and transcription factors associated with metabolism and adiposity in humans. Diet altered affiliative and anxiety-associated behaviors and mediation analysis showed that the diet-altered behaviors contributed significantly (∼50% of the effect of diet on gene expression) to 25% of the differentially expressed genes, suggesting that diet effects on central mechanisms also modulate monocyte gene expression. Together, these results identify both behavioral and molecular mechanisms underlying the health benefits of a Mediterranean diet regimen.Significance StatementSome of our largest public health burdens are driven by dietary changes associated with industrialization, but we still know very little about the molecular mechanisms underlying this link. Characteristic “Western diets” have been associated with increased risk for diseases related to chronic inflammation, while Mediterranean diets have anti-inflammatory benefits. Here, we identify causal effects of diet on inflammatory gene expression where consumption of the Mediterranean diet reduced inflammatory gene expression in monocytes. Additionally, our diet manipulation induced behavioral changes associated with anxiety and social integration, where Mediterranean-fed animals exhibited more positive affiliative behaviors and reduced anxiety. These behaviors were associated with 25% of the diet-affected genes, suggesting an important behavioral route through which diet can impact immune function.