The 'in vivo lifestyle' of bile acid 7α-dehydroxylating bacteria: comparative genomics, metatranscriptomic, and bile acid metabolomics analysis of a defined microbial community in gnotobiotic mice

The formation of secondary bile acids by gut microbes is a current topic of considerable biomedical interest. However, a detailed understanding of the biology of anaerobic bacteria in the genus Clostridium that are capable of generating secondary bile acids is lacking. We therefore sought to determine the transcriptional responses of two prominent secondary bile acid producing bacteria, Clostridium hylemonae and Clostridium hiranonis to bile salts (in vitro) and the cecal environment of gnotobiotic mice. The genomes of C. hylemonae DSM 15053 and C. hiranonis DSM 13275 were closed, and found to encode 3,647 genes (3,584 protein-coding) and 2,363 predicted genes (of which 2,239 are protein-coding), respectively, and 1,035 orthologs were shared between C. hylemonae and C. hiranonis. RNA-Seq analysis was performed in growth medium alone, and in the presence of cholic acid (CA) and deoxycholic acid (DCA). Growth with CA resulted in differential expression (>0.58 log₂FC; FDR < 0.05) of 197 genes in C. hiranonis and 118 genes in C. hylemonae. The bile acid-inducible operons (bai) from each organism were highly upregulated in the presence of CA but not DCA. We then colonized germ-free mice with human gut bacterial isolates capable of metabolizing taurine-conjugated bile acids. This consortium included bile salt hydrolase-expressing Bacteroides uniformis ATCC 8492, Bacteroides vulgatus ATCC 8482, Parabacteroides distasonis DSM 20701, as well as taurine-respiring Bilophila wadsworthia DSM 11045, and deoxycholic/lithocholic acid generating Clostridium hylemonae DSM 15053 and Clostridium hiranonis DSM 13275. Butyrate and iso-bile acid-forming Blautia producta ATCC 27340 was also included. The Bacteroidetes made up 84.71% of 16S rDNA cecal reads, B. wadsworthia, constituted 14.7%, and the clostridia made up <.75% of 16S rDNA cecal reads. Bile acid metabolomics of the cecum, serum, and liver indicate that the synthetic community were capable of functional bile salt deconjugation, oxidation/isomerization, and 7α-dehydroxylation of bile acids. Cecal metatranscriptome analysis revealed expression of genes involved in metabolism of taurine-conjugated bile acids. The in vivo transcriptomes of C. hylemonae and C. hiranonis suggest fermentation of simple sugars and utilization of amino acids glycine and proline as electron acceptors. Genes predicted to be involved in trimethylamine (TMA) formation were also expressed.

Chemical composition and free radical-scavenging, anticancer and anti-inflammatory activities of the essential oil from Ocimum kilimandscharicum

OBJECTIVE

The essential oil from the leaves of Ocimum kilimandscharicum (EOOK), collected in Dourados-MS, was investigated for anticancer, anti-inflammatory and antioxidant activity and chemical composition.

MATERIALS AND METHODS

The essential oil was extracted by hydrodistillation, and the chemical composition was performed by gas chromatography-mass spectrometry. The essential oil was evaluated for free radical-scavenging activity using the DPPH assay and was tested in an anticancer assay against ten human cancer cell lines. The response parameter (GI50) was calculated for the cell lines tested. The anti-inflammatory activity was evaluated using carrageenan-induced pleurisy in mice.

RESULTS

The chemical composition showed 45 components with a predominance of monoterpenes, such as camphor (51.81%), 1,8 cineole (20.13%) and limonene (11.23%). The EOOK exhibited potent free radical-scavenging activity by the DPPH assay with a GI50 of 8.31 μg/ml. The major constituents, pure camphor (IC50=12.56 μg/ml) and mixture of the limonene: 1, 8 cineole (IC50=23.25 μg/ml) displayed a potent activity. The oral administration of EOOK (at 30 and 100 mg kg(-1)), as well as the pure camphor or a mixture of 1,8 cineole with limonene, significantly inhibited the carrageenan (Cg) induced pleurisy, reducing the migration of total leukocytes in mice by 82 ± 4% (30 mg kg(-1) of EOOK), 95 ± 4% (100 mg kg(-1) of EOOK), 83 ± 9% (camphor) and 80 ± 5% (mixture of 1,8 cineole:limonene 1:1). In vitro cytotoxicity screening against a human ovarian cancer cell line displayed high selectivity and potent anticancer activity with GI50=31.90 mg ml(-1). This work describes the anti-inflammatory, anticancer and antioxidant effects of EOOK for the first time.

CONCLUSIONS

The essential oil exhibited marked anti-inflammatory, antioxidant and anticancer effects, an effect that can be attributed the presence of majorital compounds, and the response profiles from chemical composition differed from other oils collected in different locales.

Random amplified polymorphic DNA profiles as a tool for the characterization of Brazilian keratitis isolates of the genus Acanthamoeba

The genus Acanthamoeba comprises free-living amebae identified as opportunistic pathogens of humans and other animal species. Morphological, biochemical and molecular approaches have shown wide genetic diversity within the genus. In an attempt to determine the genetic relatedness among isolates of Acanthamoeba we analyzed randomly amplified polymorphic DNA (RAPD) profiles of 11 Brazilian isolates from cases of human keratitis and 8 American type culture collection (ATCC) reference strains. We found that ATCC strains belonging to the same species present polymorphic RAPD profiles whereas strains of different species show very similar profiles. Although most Brazilian isolates could not be assigned with certainty to any of the reference species, they could be clustered according to pattern similarities. The results show that RAPD analysis is a useful tool for the rapid characterization of new isolates and the assessment of genetic relatedness of Acanthamoeba spp. A comparison between RAPD analyses and morphological characteristics of cyst stages is also discussed.

Influence of marrow on ultrasonic velocity and attenuation in bovine trabecular bone

Measurements of ultrasonic velocity and specific differential attenuation (SDA) were obtained on 24 bovine trabecular bone specimens from the femoral condyles. The measurements were obtained using two pairs of ultrasonic transducers, one with a low nominal center frequency (500 kHz) and the other pair with a high nominal center frequency (1 MHz). The ultrasonic velocity and specific differential attenuation associated with the bone samples were determined both with and without marrow, i.e., replacing the marrow with water in the pores of the trabecular bone. Significant increases (2.1% and 2.9%) in the velocity of ultrasound were observed after removal of the marrow, for the low and high frequency transducer pairs, respectively. In contrast, significant decreases (-6.5% and -8.8%) in SDA were observed after removal of the marrow, for the low and high frequency transducer pairs, respectively. The bone densities (BD) of the samples were also determined using single photon absorptiometry (SPA). Correlations between ultrasonic parameters and bone densities for samples both with and without marrow were found to be similar. For example, for the 1 MHz transducer pair, the correlation between BD and velocity was r = 0. 86 with marrow, and r = 0.89 without marrow. This study also compared the results obtained using a contact (no water bath) technique and an insertion (with a water bath) technique of ultrasonic measurements. For the high frequency transducer pair, the correlation coefficients between the two methods were r = 0.99 and r = 0.93, for the velocity and specific differential attenuation, respectively. Similar results were found for the low frequency transducer pair as well. In addition, approximately equal correlations between BD and ultrasonic velocity and SDA were also found, indicating that contact and insertion measurements provide essentially equivalent information.

Ultrasonic assessment of human and bovine trabecular bone: a comparison study

A comparison study is reported on the ultrasonic assessment of human trabecular and bovine trabecular bone samples. Both ultrasonic velocity and ultrasonic attenuation were evaluated through a transmission insertion technique and correlated with bone mineral density as determined with single photon absorptiometry. For a 1-MHz ultrasonic transducer pair and the human cancellous bone samples the correlations were 0.91 and 0.89 between density and velocity and attenuation, respectively. For a 500-kHz ultrasonic transducer pair the correlations were 0.89 and 0.81 between density and velocity and attenuation, respectively. For the bovine bone samples, the correlations were 0.90 and -0.31 for the velocity and attenuation, respectively, for the 1 MHz transducer pair. For the 500-kHz transducers, the correlations were 0.85 and -0.17 for the velocity and attenuation, respectively. By combining both velocity and attenuation in a multivariate regression, an improvement was achieved in the estimation of bone density in the human samples for both the 500-kHz and 1-MHz transducer pairs. No significant improvement was achieved in the multivariate regressions for the bovine bone samples. In conclusion, the results indicate that ultrasonic measurements are in general highly correlated with bone mineral density in trabecular bone samples. This correlation is more consistent and strong in relatively low density human samples compared with the higher density bovine samples.