Combined Elevation of Temperature and CO2 Levels Impacts the Production and Sugar Composition of Aphid Honeydew

Honeydew is the keystone of many interactions between aphids and their predators, parasitoids, or mutualistic partners. Despite the crucial importance of honeydew in the aphid-ant mutualism, very few studies have investigated the potential impact of climate change on its production and composition. Here, we quantified changes in the sugar compounds and in the amount of honeydew droplets released by Aphis fabae reared on Vicia faba plants, under elevated levels of temperature and/or CO2. A combined elevation of these two abiotic factors increased honeydew production as well as the total amount in sugars, in particular the concentration of fructose and melezitose. Increased amount of sugars in phloem sap under elevated CO2 conditions, along with a raise of aphid metabolism and sap ingestion to compensate for water loss under elevated temperatures might explain these observed changes increase in honeydew production and sugar content. A higher amount of excreted honeydew coupled with a higher concentration in melezitose and fructose are expected to enhance both the feeding behavior and the laying of a recruitment trail by ant foragers, thereby reinforcing the ant-homopteran mutualism under a scenario of elevated temperature and CO2 levels. We discuss about the enhancing and counteracting effects of climate change on other biological agents (gut microorganisms, predators, parasitoids) that interact with aphids in a complex multitrophic system.

Nano-La2O3 Induces Honeybee (Apis mellifera) Death and Enriches for Pathogens in Honeybee Gut Bacterial Communities

Honeybees (Apis mellifera) can be exposed via numerous potential pathways to ambient nanoparticles (NPs), including rare earth oxide (REO) NPs that are increasingly used and released into the environment. Gut microorganisms are pivotal in mediating honeybee health, but how REO NPs may affect honeybee health and gut microbiota remains poorly understood. To address this knowledge gap, honeybees were fed pollen and sucrose syrup containing 0, 1, 10, 100, and 1000mgkg−1 of nano-La2O3 for 12days. Nano-La2O3 exerted detrimental effects on honeybee physiology, as reflected by dose-dependent adverse effects of nano-La2O3 on survival, pollen consumption, and body weight (p<0.05). Nano-La2O3 caused the dysbiosis of honeybee gut bacterial communities, as evidenced by the change of gut bacterial community composition, the enrichment of pathogenic Serratia and Frischella, and the alteration of digestion-related taxa Bombella (p<0.05). There were significant correlations between honeybee physiological parameters and the relative abundances of pathogenic Serratia and Frischella (p<0.05), underscoring linkages between honeybee health and gut bacterial communities. Taken together, this study demonstrates that nano-La2O3 can cause detrimental effects on honeybee health, potentially by disordering gut bacterial communities. This study thus reveals a previously overlooked effect of nano-La2O3 on the ecologically and economically important honeybee species Apis mellifera.

The Gut Microbiome Modifies the Association between a Mediterranean Diet and Diabetes in US Hispanic / Latino Population

Context The interrelationships among the gut microbiome, the MedDiet and a clinical endpoint of diabetes is unknown. Objectives To identify gut microbial features of a MedDiet and examine whether the association between MedDiet and diabetes varies across individuals with different gut microbial profiles. Methods This study included 543 diabetes, 805 prediabetes and 394 normoglycemic participants from a cohort study of US Hispanic/Latino men and women. Fecal samples were profiled using 16S rRNA gene sequencing. Adherence to MedDiet was evaluated by an index based on two 24-hour dietary recalls. Results A greater MedDiet adherence was associated with higher abundances of major dietary fiber metabolizers (e.g., Faecalibacterium Prausnitzii, FDR-adjusted p [q] =0.01), and lower abundances of biochemical specialists (e.g., Parabacteroides, q =0.04). The gut microbiomes of participants with greater MedDiet adherence were enriched for functions involved in dietary fiber degradation but depleted for those related to sulfur reduction and lactose and galactose degradation. The associations between MedDiet adherence and diabetes prevalence were significantly stronger among participants with depleted abundance of Prevotella (p interaction =0.03 for diabetes, 0.02 for prediabetes/diabetes, and 0.02 for prediabetes). A one-standard deviation increment in the MedDiet index was associated with 24% [odds ratio (OR) =0.76; 95% confidence interval (CI), 0.59-0.98] and 7% (OR =0.93; 95% CI, 0.72-1.20) lower odds of diabetes in Prevotella non-carriers and carriers, respectively. Conclusions Adherence to MedDiet is associated with diverse gut microorganisms and microbial functions. The inverse association between the MedDiet and diabetes prevalence varies significantly depending on gut microbial composition.

The role of the gut microbiota in the dietary niche expansion of fishing bats

Background Due to its central role in animal nutrition, the gut microbiota is likely a relevant factor shaping dietary niche shifts. We analysed both the impact and contribution of the gut microbiota to the dietary niche expansion of the only four bat species that have incorporated fish into their primarily arthropodophage diet. Results We first compared the taxonomic and functional features of the gut microbiota of the four piscivorous bats to that of 11 strictly arthropodophagous species using 16S rRNA targeted amplicon sequencing. Second, we increased the resolution of our analyses for one of the piscivorous bat species, namely Myotis capaccinii, and analysed multiple populations combining targeted approaches with shotgun sequencing. To better understand the origin of gut microorganisms, we also analysed the gut microbiota of their fish prey (Gambusia holbrooki). Our analyses showed that piscivorous bats carry a characteristic gut microbiota that differs from that of their strict arthropodophagous counterparts, in which the most relevant bacteria have been directly acquired from their fish prey. This characteristic microbiota exhibits enrichment of genes involved in vitamin biosynthesis, as well as complex carbohydrate and lipid metabolism, likely providing their hosts with an enhanced capacity to metabolise the glycosphingolipids and long-chain fatty acids that are particularly abundant in fish. Conclusions Our results depict the gut microbiota as a relevant element in facilitating the dietary transition from arthropodophagy to piscivory.

The Role of Endogenous Metal Nanoparticles in Biological Systems

The blood and tissues of vertebrate animals and mammals contain small endogenous metal nanoparticles. These nanoparticles were observed to be composed of individual atoms of iron, copper, zinc, silver, gold, platinum, and other metals. Metal nanoparticles can bind proteins and produce proteinaceous particles called proteons. A small fraction of the entire pool of nanoparticles is usually linked with proteins to form proteons. These endogenous metal nanoparticles, along with engineered zinc and copper nanoparticles at subnanomolar levels, were shown to be lethal to cultured cancer cells. These nanoparticles appear to be elemental crystalline metal nanoparticles. It was discovered that zinc nanoparticles produce no odor response but increase the odor reaction if mixed with an odorant. Some other metal nanoparticles, including copper, silver, gold, and platinum nanoparticles, do not affect the responses to odorants. The sources of metal nanoparticles in animal blood and tissues may include dietary plants and gut microorganisms. The solid physiological and biochemical properties of metal nanoparticles reflect their importance in cell homeostasis and disease.

The Microbiota-Gut-Brain Axis as a Key to Neuropsychiatric Disorders: A Mini Review

The central nervous system (CNS) is closely related to the gastrointestinal tract, mainly through regulating its function and homeostasis. Simultaneously, the gut flora affects the CNS and plays an essential role in the pathogenesis of neurologic and neuropsychological disorders such as Parkinson’s and Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis or autism spectrum disorder. The population of gut microorganisms contains more than one billion bacteria. The most common are six phyla: Proteobacteria, Actinomyces, Verucomicrobia, Fusobacteria, and dominant Bacteroides with Firmicutes. The microbiota–gut–brain axis is a bidirectional nervous, endocrine, and immune communication between these two organs. They are connected through a variety of pathways, including the vagus nerve, the immune system, microbial metabolites such as short-chain fatty acids (SCFAs), the enteric nervous system, and hormones. Age, diet, antibiotics influence the balance of gut microorganisms and probably lead to the development of neurodegenerative disorders. In this article, a review is presented and discussed, with a specific focus on the changes of gut microbiota, gut–brain axis, related disorders, and the factors that influence gut imbalance.

Induction of Gut Microbial Tryptamine by SARS-CoV-2 in Nonhuman Primate Model Consistent with Tryptamine-Induced Model of Neurodegeneration

The author discussed recently the possible molecular mechanisms that cause the COVID-19 disease symptoms. Here the analysis of the recent experimental data supports the hypothesis that production of the gut microbial tryptamine can be induced by the SARS-CoV-2 fecal viral activity due to the selective pressure or positive selection of tryptamine-producing microorganisms. In this report, the author suggests that the mechanism of microbial selection bases on the abilities of tryptamine to affect the viral nucleic acid. In other words, the gut microorganisms producing tryptamine are more resistant to SARS-CoV-2 fecal viral activity than microorganisms producing no tryptamine. Earlier we demonstrated the induction of neurodegeneration by tryptamine in human cells and mouse brain. Furthermore, we were able to uncover the human gut bacteria associated with Alzheimer’s disease (AD) using PCR testing of human fecal samples with the new-designed primers targeting the tryptophan-tryptamine pathway. Likely, SARS-CoV-2 is one of the selective pressure factors in the cascade accelerating the neurodegenerative process in AD. This suggestion is consistent with a higher proportion of AD patients among COVID-19 related victims. Gut microbial tryptamine increase due to the viral infection-induced dysbiosis can synergize and potentiate the tryptamine cytotoxicity, necrotizing ability and other properties as a virulence factor.

Lactobacillus intestinalis YT2 restores the gut microbiota and improves menopausal symptoms in ovariectomized rats

There are many studies focusing on the alleviation of menopausal symptoms; however, little is known about the role of gut microorganisms in menopausal symptoms. Ovariectomized (OVX) rats were administered a novel strain (YT2) of Lactobacillus intestinalis (a species with significantly reduced abundance in OVX rats) and the potential probiotic effect on the improvement of menopausal symptoms was evaluated. Of note, the gut microbial composition completely shifted after ovariectomy in rats. Treatment with L. intestinalis YT2 significantly alleviated menopausal symptoms, such as increased fat mass, decreased bone mineral density, increased pain sensitivity, depression-like behaviour, and cognitive impairment. Additionally, the administration of L. intestinalis YT2 restored the intestinal microbial composition, including an increased Firmicutes/Bacteroides ratio. L. intestinalis YT2 also promoted gut barrier integrity by increasing the mRNA levels of tight junction-related markers. In conclusion, L. intestinalis YT2 treatment alleviated menopausal symptoms via the modulation of the gut microbiota. Importantly, these results suggest that L. intestinalis YT2 should be considered as a therapeutic probiotic agent for menopausal women.

Gut Coaching: How Immune Cells Become Superheroes…or Villains!

The gut is home to millions of microscopic organisms, which together are called the gut microbiota. Most of these microorganisms live in peace with the rest of our cells, help us get energy from food, and give us essential nutrients that we cannot make ourselves. The cells lining the gut’s surface keep these microorganisms separated from the rest of the body, like the “Great Wall” of our kingdom. On the inside of this Great Wall, the heroes of the mighty immune system watch over and protect us. But how can the immune system tell the difference between our own cells and the gut microorganisms? Or between helpful microorganisms and disease-causing ones? It is an amazing storey, full of secrets. In this article, we will explain how the gut coaches the immune system to recognise enemies, and how some aspects of modern life might be interfering with this process.