Rbec: a tool for analysis of amplicon sequencing data from synthetic microbial communities

Synthetic microbial communities (SynComs) constitute an emerging and powerful tool in biological, biomedical, and biotechnological research. Despite recent advances in algorithms for the analysis of culture-independent amplicon sequencing data from microbial communities, there is a lack of tools specifically designed for analyzing SynCom data, where reference sequences for each strain are available. Here we present Rbec, a tool designed for the analysis of SynCom data that accurately corrects PCR and sequencing errors in amplicon sequences and identifies intra-strain polymorphic variation. Extensive evaluation using mock bacterial and fungal communities show that our tool outperforms current methods for samples of varying complexity, diversity, and sequencing depth. Furthermore, Rbec also allows accurate detection of contaminants in SynCom experiments.

Reference-based error correction of amplicon sequencing data from synthetic communities

MotivationSynthetic microbial communities (SynComs) constitute an emergent and powerful tool in biological, biomedical, and biotechnological research. Despite recent advances in algorithms for analysis of culture-independent amplicon sequencing data from microbial communities, there is a lack of tools specifically designed for analysing SynCom data, where reference sequences for each strain are available.ResultsHere we present Rbec, a tool designed for analysing SynCom data that outperforms current methods by accurately correcting errors in amplicon sequences and identifying intra-strain polymorphic variation. Extensive evaluation using mock bacterial and fungal communities show that our tool performs robustly for samples of varying complexity, diversity, and sequencing depth. Further, Rbec also allows accurate detection of contaminations in SynCom experiments.AvailabilityRbec is freely available as an open-source R package and can be downloaded at: https://github.com/PengfanZhang/Microbiome.

Captivating color: evidence for optimal stimulus design in a polymorphic prey lure

Araneid spiders use abstract color patterns to attract prey. The chromatic properties of these displays vary extensively, both within and across species, and they are frequently polymorphic. Variation is often expressed in terms of signal hue (color per se), but it is unclear precisely how attractiveness scales with this property. We assessed captures among color-manipulated females of the dimorphic jeweled spider Gasteracantha fornicata in their natural webs. The manipulation magnified the natural variation in stimulus hue independently of chroma (saturation) across a range spanning most of the color spectrum. Catch rate varied across treatments in simple accordance with how greatly stimulus hue deviated from either of the two extant phenotypes. Predictions based upon fly-perceived background contrast were unsupported despite dipterans constituting ~60 % of prey. This study isolates the importance of stimulus hue and supports the premise that extant phenotypes reside in an optimal spectral range for prey attraction.

Serotonin Receptor 1A Variation Is Associated with Anxiety and Agonistic Behavior in Chimpanzees

Serotonin is a neurotransmitter that plays an important role in regulating behavior and personality in humans and other mammals. Polymorphisms in genes coding for the serotonin receptor subtype 1A (HTR1A), the serotonin transporter (SLC6A4), and the serotonin degrading enzyme monoamine oxidase A (MAOA) are associated with anxiety, impulsivity, and neurotic personality in humans. In primates, previous research has largely focused on SLC6A4 and MAOA, with few studies investigating the role of HTR1A polymorphic variation on behavior. Here, we examined variation in the coding region of HTR1A across apes, and genotyped polymorphic coding variation in a sample of 214 chimpanzees with matched measures of personality and behavior. We found evidence for positive selection at three amino acid substitution sites, one in chimpanzees-bonobos (Thr26Ser), one in humans (Phe33Val), and one in orangutans (Ala274Gly). Investigation of the HTR1A coding region in chimpanzees revealed a polymorphic site, where a C/A single nucleotide polymorphism changes a proline to a glutamine in the amino acid sequence (Pro248Gln). The substitution is located in the third intracellular loop of the receptor, a region important for serotonin signal transduction. The derived variant is the major allele in this population (frequency 0.67), and is associated with a reduction in anxiety, decreased rates of male agonistic behavior, and an increase in socio-positive behavior. These results are the first evidence that the HTR1A gene may be involved in regulating social behavior in chimpanzees and encourage further systematic investigation of polymorphic variation in other primate populations with corresponding data on behavior.

Huntington’s disease onset is determined by length of uninterrupted CAG, not encoded polyglutamine, and is modified by DNA maintenance mechanisms

SUMMARYThe effects of variable, glutamine-encoding, CAA interruptions indicate that a property of the uninterrupted HTT CAG repeat sequence, distinct from huntingtin’s polyglutamine segment, dictates the rate at which HD develops. The timing of onset shows no significant association with HTT cis-eQTLs but is influenced, sometimes in a sex-specific manner, by polymorphic variation at multiple DNA maintenance genes, suggesting that the special onset-determining property of the uninterrupted CAG repeat is a propensity for length instability that leads to its somatic expansion. Additional naturally-occurring genetic modifier loci, defined by GWAS, may influence HD pathogenesis through other mechanisms. These findings have profound implications for the pathogenesis of HD and other repeat diseases and question a fundamental premise of the “polyglutamine disorders”.