Microbiota In Midgut Research Articles

Effects of short-term florfenicol exposure on the gene expression pattern, midgut microbiota, and metabolome in the lepidopteran model silkworm (Bombyx mori)

Florfenicol (FF), an alternative veterinary antibiotic for chloramphenicol, has been widely utilized in livestock breeding to prevent and treat bacterial diseases. However, the toxicological effects of FF have yet to be fully disclosed. The domesticated silkworm (Bombyx mori), a lepidopteran model, was selected to assess the toxicological effects of FF dietary exposure with multi-omics. The findings showed that high-dose (250 μg/L) FF exposure increased the whole cocoon weight. High-dose FF exposure affected the species richness and community diversity of the microbiota in the silkworm midgut. Biochemical processes and innate immunity were impacted by FF exposure. The KEGG pathways impacted by the midgut microbiota and their metabolites were compared, and several pathways were found to be related to the two ecosystems. In addition, the innate immunity and lipid metabolism pathways were impacted, and some of the differentially expressed genes were enriched in these pathways. These related pathways may involve crosstalk between the midgut microbiota shift, midgut biological functions, and global gene expression. Therefore, our study also advances the application of the silkworm larval model in assessing antibiotic metabolic toxicity and provides novel insights into the potential risks of FF.

Multi-kingdom microbiota and functions changes associated with culture mode in genetically improved farmed tilapia (Oreochromis niloticus).

Genetically improved farmed tilapia (GIFT, Oreochromis niloticus) are intensively farmed in China, where most of the yield derives from the pond culture system (PCS). The in-pond raceway system (IPRS) is a new type of highly efficient aquaculture mode, and has been recommended as a novel system for GIFT farming. To determine the effects of these culture modes on the gut microbiome of GIFT, we conducted a 90-days experiment in IPRS and PCS units. A 16S rRNA gene profile analysis showed that the composition of gut microbiota in GIFT under IPRS and PCS conditions gradually separated as rearing progressed, with divergent responses by the midgut and hindgut bacteria. The α-diversity in hindgut decreased significantly by day 90, as compared with on day 7 (p < 0.05), with a significantly greater decrease in PCS-reared fish than in IPRS fish (p < 0.05). The α-diversity of microbiota in midgut remained stable (p > 0.05). The overall dominant gut bacteria were Bacteroidetes, Proteobacteria, and Firmicutes. Rearing mode affected the taxonomic profile of the gut bacteria; in midgut, IPRS samples had more Firmicutes and Fusobacteria compared with PCS samples, but less Proteobacteria, Verrucomicrobia, and Actinobacteria. Firmicutes was enriched in IPRS hindgut, and Fusobacteria was enriched in PCS hindgut. Using random-forest models and LEfSe, we also screened core taxa that could discriminate between the gut microbial communities under IPRS and PCS conditions. The genus Cetobacterium (of family Fusobacteriaceae) was significantly enriched in midgut in IPRS fish, and enriched in hindgut in PCS fish. The genus Clostridium sensu stricto (of family Clostridiaceae 1) was significantly enriched in both IPRS midgut and hindgut. Analysis with PICRUSt2 software revealed that the culture modes were similar in their effects on the gut microbial metabolic functions. The predicted pathways were significantly enriched in the metabolism class (level 1). Further, the relative abundance of functions related to amino acid metabolic, carbohydrate metabolic, energy metabolic, and metabolic of cofactors and vitamins were high at hierarchy level 2, as the metabolic activity of intestinal bacteria is especially active. Overall, this study enhances our understanding of the characteristics of gut microbiota in GIFT under IPRS and PCS culture modes. Moreover, our findings provide insights into the microecological balance in IPRS units, and a theoretical reference for further development of this culture system.

Comparative analysis of midgut bacterial community under Vibrio splendidus infection in Apostichopus japonicus with hindgut as a reference

Animal gut harbors diverse microbes in the protection against pathogen invasion and the regulation of host immune responses. In our previous work, we found that environmental factors destroy hindgut intestinal flora to promote pathogen infection in sea cucumber. Midgut microbiota could protect host from pathogen infection via producing of antibiotics and enzymes in human and insect. To address the function role of midgut microbiota, the bacterial community in the midgut of Apostichopus japonicus was assessed using 16S rRNA sequencing technology, as well as following the Vibrio splendidus infection in this study. Results showed that the relative abundance of Actinobacteria in the midgut under V. splendidus infection was lower compared to the normal midgut, and the Clostridiaceae, Ruminococcaceae and Lachnospiraceae were increased under pathogen infection in the midgut at the family level. Notably, the abundance of V. splendidus was significantly lower in the midgut than hindgut in both healthy and diseased conditions. Function analysis indicated that the basal metabolic pathways were significantly higher in midgut than hindgut under diseased condition, while, the signaling molecules and interaction, xenobiotics biodegradation and metabolism pathways with the bacteria were lower in midgut than hindgut under V. splendidus infection. Less cooperative interactions were dominant in the hindgut in response to pathogen infection, but more cooperative and complex interactions predominated in the microbial community in the midgut under diseased condition. Among them, the interaction with Vibrionaceae was significantly decreased in the midgut compared with the hindgut under V. splendidus infection. All our results suggested the difference function role of the microbiota in midgut and hindgut of sea cucumber, in which V. splendidus was more likely to colonized in the hindgut and promote the occurrence and development of skin ulceration syndrome, rather than the midgut.

Immune resistance and tolerance strategies in malaria vector and non-vector mosquitoes

BackgroundThe Anopheles gambiae complex consists of species that vary greatly in their capacity to transmit malaria. The mosquito immune system has been identified as a key factor that can influence whether Plasmodium infection establishes within the mosquito vector. This study was designed to investigate the immune responses of An. coluzzii, An. arabiensis and An. quadriannulatus mosquitoes. The first two mosquito species are major vectors of malaria in sub-Saharan Africa, while the third is thought to be a non-vector.MethodsAll three mosquito species were reared in mixed cultures. Their capacity to eliminate P. berghei and regulate midgut bacteria was examined.ResultsOur results revealed large differences in mosquito resistance to P. berghei. In all three mosquito species, immune reactions involving the complement system were triggered when the number of parasites that mosquitoes were challenged with exceeded a certain level, i.e. immune tolerance threshold. This threshold was markedly lower in An. quadriannulatus compared to An. coluzzii and An. arabiensis. We also demonstrated that the level of immune tolerance to P. berghei infection in the haemolymph is inversely correlated with the level of immune tolerance to microbiota observed in the midgut lumen after a blood meal. The malaria non-vector mosquito species, An. quadriannulatus was shown to have a much higher level of tolerance to microbiota in the midgut than An. coluzzii.ConclusionsWe propose a model whereby an increased tolerance to microbiota in the mosquito midgut results in lower tolerance to Plasmodium infection. In this model, malaria non-vector mosquito species are expected to have increased immune resistance in the haemocoel, possibly due to complement priming by microbiota elicitors. We propose that this strategy is employed by the malaria non-vector mosquito, An. quadriannulatus, while An. coluzzii has reduced tolerance to bacterial infection in the midgut and consequently reduced immune resistance to Plasmodium infection at the haemocoel level. An in-depth understanding of the molecular mechanisms regulating immune tolerance versus resistance in different mosquito vectors of malaria could guide the design of new vector and disease control strategies.