Analysis of caecal microbiota in rats fed with genetically modified rice by real-time quantitative PCR

Structural and quantitative alterations of gut microbiota in experimental small bowel obstruction

OBJECTIVE

To investigate structural and quantitative alterations of gut microbiota in an experimental model of small bowel obstruction.

METHOD

A rat model of small bowel obstruction was established by using a polyvinyl chloride ring surgically placed surrounding the terminal ileum. The alterations of gut microbiota were studied after intestinal obstruction. Intraluminal fecal samples proximal to the obstruction were collected at different time points (24, 48 and 72 hours after obstruction) and analyzed by 16s rDNA high-throughput sequencing technology and quantitative PCR (qPCR) for target bacterial groups. Furthermore, intestinal claudin-1 mRNA expression was examined by real-time polymerase chain reaction analysis, and serum sIgA, IFABP and TFF3 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Small bowel obstruction led to significant bacterial overgrowth and profound alterations in gut microbiota composition and diversity. At the phylum level, the 16S rDNA sequences showed a marked decrease in the relative abundance of Firmicutes and increased abundance of Proteobacteria, Verrucomicrobia and Bacteroidetes. The qPCR analysis showed the absolute quantity of total bacteria increased significantly within 24 hours but did not change distinctly from 24 to 72 hours. Further indicators of intestinal mucosa damage and were observed as claudin-1 gene expression, sIgA and TFF3 levels decreased and IFABP level increased with prolonged obstruction.

CONCLUSION

Small bowel obstruction can cause significant structural and quantitative alterations of gut microbiota and induce disruption of gut mucosa barrier.

The food safety of DP-356Ø43 soybeans on SD rats reflected by physiological variables and fecal microbiota during a 90-day feeding study

Soybean is an important food resource for the eastern countries and herbicide-tolerant genetically modified soybeans (GMS) were widely developed to deal with weeds problems. Unprocessed soybean flour instead of dehulled and defatted soybean meal was used to reflect the safety of soybean food in whole. Rats were given formulated diets containing DP-356Ø43 or non-GM soybean JACK at an incorporation rate of 7.5%, 15%, or 30% (w/w), respectively for 90 days. Targeted traditional toxicological response variables were measured to reflect the holistic health of animals. No treatment-related adverse or toxic effects were observed based on an examination of the daily clinical signs, body weight, food consumption, hematology, serum biochemistry, and organ weight or based on gross and histopathological examination. The results demonstrate that the soybean DP-356Ø43 is as safe for consumption as conventional soybean JACK. In the current study, the effect of a herbicide-tolerant GMS DP-356043 on identified intestinal microbiota was evaluated in a rodent feeding study compared with its conventional control JACK. Feces samples from rats consuming different diets were collected before the start of the experiment (time 0) and at monthly intervals (at the end of the 1st, 2nd and 3rd months) over the course of 90 days. Six types of bacterias shared by humans and rats were detected with Q-PCR. The results of QPCR indicated that the GMS 356Ø43 had a comparable effect on the abundance of Bifidobacterium group, Clostridium perfringens subgroup, Escherichia coli, and Bacteroides-Prevotella group as the non-GMS JACK.

Published GMO studies find no evidence of harm when corrected for multiple comparisons

A number of widely debated research articles claiming possible technology-related health concerns have influenced the public opinion on genetically modified food safety. We performed a statistical reanalysis and review of experimental data presented in some of these studies and found that quite often in contradiction with the authors' conclusions the data actually provides weak evidence of harm that cannot be differentiated from chance. In our opinion the problem of statistically unaccounted multiple comparisons has led to some of the most cited anti-genetically modified organism health claims in history. We hope this analysis puts the original results of these studies into proper context.

A comparison of two real-time polymerase chain reaction assays using hybridization probes targeting either 16S ribosomal RNA or a subsurface lipoprotein gene for detecting leptospires in canine urine

Leptospires are excreted in the urine of infected animals, and the prompt detection of leptospiral DNA using polymerase chain reaction (PCR) is increasingly being used. However, contradictory data has emerged concerning the diagnostic accuracy of the most popular PCR assays that target either the 16S ribosomal RNA ( rrs) or the subsurface lipoprotein ( LipL32) genes. In order to clarify the effect of the gene target, a novel hydrolysis probe–based, quantitative real-time PCR (qPCR) assay targeting the LipL32 gene was developed, validated, and then compared directly to the previously described rrs hydrolysis probe–based qPCR using a convenience collection of canine urine samples. The novel LipL32 qPCR assay was linear from 5.9 × 106 to 59 genome equivalents per reaction. Both the LipL32 and the rrs qPCR assays showed a limit of detection of 10 target copies per reaction indicating an approximately equivalent analytical sensitivity. Both assays amplified all 20 pathogenic leptospiral strains tested but did not amplify a representative collection of bacteria commonly found in voided canine urine. When the field samples were assayed, 1 and 5 out of 184 samples yielded an amplification signal in the LipL32 and rrs assays, respectively. Nevertheless, when the limit of detection was considered as the cutoff for interpreting findings, the 4 discordant cases were judged as negative. In conclusion, our study confirmed that both LipL32 and rrs are suitable targets for qPCR for the detection of leptospiral DNA in canine urine. However, the rrs target requires the mandatory use of a cutoff value in order to correctly interpret spurious amplifications.

Effect of (D)-fagomine on excreted Enterobacteria and weight gain in rats fed a high-fat high-sucrose diet

OBJECTIVE

Becoming overweight has been related to elevated levels of Enterobacteriales in the gut. d-Fagomine is an iminosugar that has been shown to selectively agglutinate Enterobacteriales in vitro. The goal of this work is to establish whether d-fagomine exerts a similar effect in vivo and whether this has any downstream consequences on weight gain.

METHODS

The rats were fed a high-fat high-sucrose diet (HFHS) supplemented with d-fagomine (or not; for comparison) or a standard diet for 5 weeks. The levels of total bacteria, Enterobacteriales and Escherichia coli were determined in fecal samples by performing quantitative real-time polymerase chain reactions on DNA.

RESULTS

Whereas the total levels of bacteria were independent of the diet, rats fed HFHS (without d-fagomine) excreted significantly higher proportions of Enterobacteriales and E. coli than those fed a standard diet. The levels of Enterobacteriales and E. coli of the rats given HFHS with d-fagomine were similar to those of the rats fed a standard diet. Compared to the standard group, rats fed HFHS with d-fagomine gained significantly less weight (15.3%) than those fed HFHS (20.9%).

CONCLUSION

d-Fagomine reduces the amount of Enterobacteriales excreted by rats fed HFHS and this may help to avert becoming obese.