Bacterial succession in the colon during childhood and adolescence: molecular studies in a Southern Indian village

Background: The colonic bacterial flora, largely anaerobic, is believed to establish and stabilize in the first 2 y of life. Objective: This study was undertaken to determine whether the bacterial flora of the colon undergoes further changes (succession) during childhood and adolescence. Design: This cross-sectional study examined fecal samples from 130 healthy children and adolescents in the age group 2-17 y and from 30 healthy adults (median age: 42 y) residing in a single village in southern India. DNA was extracted and subjected to 16S rDNA-targeted real-time polymerase chain reaction to determine the relative predominance of Bifidobacterium genus, Bacteroides-Prevotella-Porphyromonas group, Lactobacillus acidophilus group, Eubacterium rectale, and Faecalibacterium prausnitzii. Results: Bifidobacterium species and Bacteroides-Prevotella group were dominant fecal bacteria overall. E. rectale and Lactobacillus species were considerably less abundant. Clear age-related differences emerged, with a steep decline in Bifidobacterium species in adults (P < 0.0001), a steep decline of Lactobacillus species >5 y of age (P < 0.0001), an increase in Bacteroides during late adolescence and in adults (P = 0.0040), an increase in E. rectale during childhood and adolescence followed by a steep decline in adults (P < 0.0001), and a late childhood peak of F. prausnitzii with decline in adolescents and adults (P < 0.0001). Conclusions: Changes in the bacterial flora occur during childhood and adolescence characterized by reduction in Lactobacillus and Bifidobacterium species and an increase in Bacteroides, E rectale, and F. prausnitzii peaked during late childhood in this population

Molecular studies of fecal anaerobic commensal bacteria in acute diarrhea in children

Background and Objective: The commensal bacterial flora of the colon may undergo changes during diarrhea, owing to colonization of the intestine by pathogens and to rapid intestinal transit. This study used molecular methods to determine changes in the composition of selected commensal anaerobic bacteria during and after acute diarrhea in children. Materials and Methods: Fecal samples were obtained from 46 children with acute diarrhea in a rural community during an episode of acute diarrhea, immediately after recovery from diarrhea, and 3 months after recovery. DNA was extracted and quantitative polymerase chain reaction using SYBR green and genus- and species-specific primers targeting 16S rDNA were undertaken to quantitate the following groups of bacteria: Bifidobacterium spp., Bifidobacterium longum group, Bacteroides-Prevotella group, Bacteroides fragilis, Lactobacillus acidophilus group, Faecalibacterium prauznitzii, and Eubacterium rectale, relative to amplification of universal bacterial domain 16S rDNA. Results: Bacteria belonging to the Bacteroides-Prevotella-Porphyromonas group, E rectale, L acidophilus, and F prauznitzii groups were low during acute diarrhea compared with their levels after recovery from diarrhea. The pattern was similar in rotavirus diarrhea and nonrotavirus diarrhea. Administration of amylase-resistant maize starch as adjuvant therapy was associated with lower levels of F prauznitzii at the time of recovery but did not lead to other changes in the floral pattern. Conclusions: Specific classes of fecal bacteria are lower during episodes of acute diarrhea in children than during periods of normal gastrointestinal health, suggesting specific alterations in the flora during diarrhea

Energy extraction from the biologic battery in the inner ear

Endocochlear potential (EP) is a battery-like electrochemical gradient found in and actively maintained by the inner ear [superscript 1, 2]. Here we demonstrate that the mammalian EP can be used as a power source for electronic devices. We achieved this by designing an anatomically sized, ultra-low quiescent-power energy harvester chip integrated with a wireless sensor capable of monitoring the EP itself. Although other forms of in vivo energy harvesting have been described in lower organisms [superscript 3, 4, 5], and thermoelectric [superscript 6], piezoelectric [superscript 7] and biofuel [superscript 8, 9] devices are promising for mammalian applications, there have been few, if any, in vivo demonstrations in the vicinity of the ear, eye and brain. In this work, the chip extracted a minimum of 1.12 nW from the EP of a guinea pig for up to 5 h, enabling a 2.4 GHz radio to transmit measurement of the EP every 40–360 s. With future optimization of electrode design, we envision using the biologic battery in the inner ear to power chemical and molecular sensors, or drug-delivery actuators for diagnosis and therapy of hearing loss and other disorders.Focus Center Research Program. Focus Center for Circuit & System Solutions. Semiconductor Research Corporation. Interconnect Focus CenterNational Institutes of Health (U.S.) (Grant K08 DC010419)National Institutes of Health (U.S.) (Grant T32 DC00038)Bertarelli Foundatio

Conservation of the S10-spc-α Locus within Otherwise Highly Plastic Genomes Provides Phylogenetic Insight into the Genus Leptospira

S10-spc-α is a 17.5 kb cluster of 32 genes encoding ribosomal proteins. This locus has an unusual composition and organization in Leptospira interrogans. We demonstrate the highly conserved nature of this region among diverse Leptospira and show its utility as a phylogenetically informative region. Comparative analyses were performed by PCR using primer sets covering the whole locus. Correctly sized fragments were obtained by PCR from all L. interrogans strains tested for each primer set indicating that this locus is well conserved in this species. Few differences were detected in amplification profiles between different pathogenic species, indicating that the S10-spc-α locus is conserved among pathogenic Leptospira. In contrast, PCR analysis of this locus using DNA from saprophytic Leptospira species and species with an intermediate pathogenic capacity generated varied results. Sequence alignment of the S10-spc-α locus from two pathogenic species, L. interrogans and L. borgpetersenii, with the corresponding locus from the saprophyte L. biflexa serovar Patoc showed that genetic organization of this locus is well conserved within Leptospira. Multilocus sequence typing (MLST) of four conserved regions resulted in the construction of well-defined phylogenetic trees that help resolve questions about the interrelationships of pathogenic Leptospira. Based on the results of secY sequence analysis, we found that reliable species identification of pathogenic Leptospira is possible by comparative analysis of a 245 bp region commonly used as a target for diagnostic PCR for leptospirosis. Comparative analysis of Leptospira strains revealed that strain H6 previously classified as L. inadai actually belongs to the pathogenic species L. interrogans and that L. meyeri strain ICF phylogenetically co-localized with the pathogenic clusters. These findings demonstrate that the S10-spc-α locus is highly conserved throughout the genus and may be more useful in comparing evolution of the genus than loci studied previously

Comparison of Two Multilocus Sequence Based Genotyping Schemes for Leptospira Species

Two independent multilocus sequence based genotyping schemes (denoted here as 7L and 6L for schemes with 7 and 6 loci, respectively) are in use for Leptospira spp., which has led to uncertainty as to which should be adopted by the scientific community. The purpose of this study was to apply the two schemes to a single collection of pathogenic Leptospira, evaluate their performance, and describe the practical advantages and disadvantages of each scheme. We used a variety of phylogenetic approaches to compare the output data and found that the two schemes gave very similar results. 7L has the advantage that it is a conventional multi-locus sequencing typing (MLST) scheme based on housekeeping genes and is supported by a publically accessible database by which genotypes can be readily assigned as known or new sequence types by any investigator, but is currently only applicable to L. interrogans and L. kirschneri. Conversely, 6L can be applied to all pathogenic Leptospira spp., but is not a conventional MLST scheme by design and is not available online. 6L sequences from 271 strains have been released into the public domain, and phylogenetic analysis of new sequences using this scheme requires their download and offline analysis

Importance of Non-Selective Cation Channel TRPV4 Interaction with Cytoskeleton and Their Reciprocal Regulations in Cultured Cells

BACKGROUND: TRPV4 and the cellular cytoskeleton have each been reported to influence cellular mechanosensitive processes as well as the development of mechanical hyperalgesia. If and how TRPV4 interacts with the microtubule and actin cytoskeleton at a molecular and functional level is not known. METHODOLOGY AND PRINCIPAL FINDINGS: We investigated the interaction of TRPV4 with cytoskeletal components biochemically, cell biologically by observing morphological changes of DRG-neurons and DRG-neuron-derived F-11 cells, as well as functionally with calcium imaging. We find that TRPV4 physically interacts with tubulin, actin and neurofilament proteins as well as the nociceptive molecules PKCepsilon and CamKII. The C-terminus of TRPV4 is sufficient for the direct interaction with tubulin and actin, both with their soluble and their polymeric forms. Actin and tubulin compete for binding. The interaction with TRPV4 stabilizes microtubules even under depolymerizing conditions in vitro. Accordingly, in cellular systems TRPV4 colocalizes with actin and microtubules enriched structures at submembranous regions. Both expression and activation of TRPV4 induces striking morphological changes affecting lamellipodial, filopodial, growth cone, and neurite structures in non-neuronal cells, in DRG-neuron derived F11 cells, and also in IB4-positive DRG neurons. The functional interaction of TRPV4 and the cytoskeleton is mutual as Taxol, a microtubule stabilizer, reduces the Ca2+-influx via TRPV4. CONCLUSIONS AND SIGNIFICANCE: TRPV4 acts as a regulator for both, the microtubule and the actin. In turn, we describe that microtubule dynamics are an important regulator of TRPV4 activity. TRPV4 forms a supra-molecular complex containing cytoskeletal proteins and regulatory kinases. Thereby it can integrate signaling of various intracellular second messengers and signaling cascades, as well as cytoskeletal dynamics. This study points out the existence of cross-talks between non-selective cation channels and cytoskeleton at multiple levels. These cross talks may help us to understand the molecular basis of the Taxol-induced neuropathic pain development commonly observed in cancer patients