Antioxidant potential and antimicrobial efficacy of seaweed (Himanthalia elongata) extract in model food systems

Extracts from marine sources exhibit antimicrobial and antioxidant properties in vitro and there has been great interest within the food industry to move towards natural methods of food preservation. Natural extracts from seaweeds could potentially have a multiple functionality within the food industry to increase safety and enhance the quality of food products. The present study is aimed to assess the antimicrobial activity of a hydrophilic extract from the fucoid brown alga Himanthalia elongata in model food systems. Carbohydrate and protein model food systems (CMFS and PMFS, respectively) were studied at varying concentrations (1 %, 5 % and 10 %) and bacterial inhibition of the extract was investigated against Salmonella abony and Listeria monocytogenes. The extract provided up to 100 % inhibition of the bacteria with a bactericidal effect in CMFS, while a bacteriostatic effect was seen in PMFS. In general, there was a significant difference (P?<?0.05) between the efficacies of the extract against S. abony as compared to L. monocytogenes with higher inhibition for S. abony. In terms of antioxidants; the extract had a total phenolic content of 34.0 mg GAE g^?1 of extract and a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity of 139.8 mg AAE g of extract. The results of the present study are promising as it provides an insight for the inclusion of seaweed extracts into real food systems.     

Identification and cloning of the Mycobacterium avium folA gene, required for dihydrofolate reductase activity

Dihydrofolate reductase is an essential bacterial enzyme necessary for the maintenance of intracellular folate pools in a biochemically active reduced state. In this report, the Mycobacterium avium folA gene was identified by functional genetic complementation, sequenced, and expressed for the first time. It has an open reading frame of 543 bp with a G+C content of 73%. The translated polypeptide sequence shows 58% identity to the consensus sequence of the conserved regions from eight other bacterial dihydrofolate reductases. Recombinant M. avium dihydrofolate reductase was expressed actively in Escherichia coli, and SDS-PAGE analysis revealed a 20 kDa species, agreeable with that predicted from the polypeptide sequence.     

Assessing the Fecal Microbiota: An Optimized Ion Torrent 16S rRNA Gene-Based Analysis Protocol

Assessing the distribution of 16S rRNA gene sequences within a biological sample represents the current state-of-the-art for determination of human gut microbiota composition. Advances in dissecting the microbial biodiversity of this ecosystem have very much been dependent on the development of novel high-throughput DNA sequencing technologies, like the Ion Torrent. However, the precise representation of this bacterial community may be affected by the protocols used for DNA extraction as well as by the PCR primers employed in the amplification reaction. Here, we describe an optimized protocol for 16S rRNA gene-based profiling of the fecal microbiota.     

Dating the arthropod tree based on large-scale transcriptome data

Molecular sequences do not only allow the reconstruction of phylogenetic relationships among species, but also provide information on the approximate divergence times. Whereas the fossil record dates the origin of most multicellular animal phyla during the Cambrian explosion less than 540 million years ago(mya), molecular clock calculations usually suggest much older dates. Here we used a large multiple sequence alignment derived from Expressed Sequence Tags and genomes comprising 129genes (37,476 amino acid positions) and 117 taxa, including 101 arthropods. We obtained consistent divergence time estimates applying relaxed Bayesian clock models with different priors and multiple calibration points. While the influence of substitution rates, missing data, and model priors were negligible, the clock model had significant effect. A log-normal autocorrelated model was selected on basis of cross-validation. We calculated that arthropods emerged ~600 mya. Onychophorans (velvet worms) and euarthropods split ~590 mya, Pancrustacea and Myriochelata ~560 mya, Myriapoda and Chelicerata ~555 mya, and 'Crustacea' and Hexapoda ~510 mya. Endopterygote insects appeared ~390 mya. These dates are considerably younger than most previous molecular clock estimates and in better agreement with the fossil record. Nevertheless, a Precambrian origin of arthropods and other metazoan phyla is still supported. Our results also demonstrate the applicability of large datasets of random nuclear sequences for approximating the timing of multicellular animal evolution.     

The oncolytic peptide LTX-315 triggers necrotic cell death

The oncolytic peptide LTX-315 has been designed for killing human cancer cells and turned out to stimulate anti-cancer immune responses when locally injected into tumors established in immunocompetent mice. Here, we investigated the question whether LTX-315 induces apoptosis or necrosis. Transmission electron microscopy or morphometric analysis of chromatin-stained tumor cells revealed that LTX-315 failed to induce apoptotic nuclear condensation and rather induced a necrotic phenotype. Accordingly, LTX-315 failed to stimulate the activation of caspase-3, and inhibition of caspases by means of Z-VAD-fmk was unable to reduce cell killing by LTX-315. In addition, 2 prominent inhibitors of regulated necrosis (necroptosis), namely, necrostatin-1 and cycosporin A, failed to reduce LTX-315-induced cell death. In conclusion, it appears that LTX-315 triggers unregulated necrosis, which may contribute to its pro-inflammatory and pro-immune effects.     

The Thermosensitive Potassium Channel TREK-1 Contributes to Coolness-Evoked Responses of Grueneberg Ganglion Neurons

Neurons of the Grueneberg ganglion (GG) residing in the vestibule of the murine nose are activated by cool ambient temperatures. Activation of thermosensory neurons is usually mediated by thermosensitive ion channels of the transient receptor potential (TRP) family. However, there is no evidence for the expression of thermo-TRPs in the GG, suggesting that GG neurons utilize distinct mechanisms for their responsiveness to cool temperatures. In search for proteins that render GG neurons responsive to coolness, we have investigated whether TREK/TRAAK channels may play a role; in heterologous expression systems, these potassium channels have been previously found to close upon exposure to coolness, leading to a membrane depolarization. The results of the present study indicate that the thermosensitive potassium channel TREK-1 is expressed in those GG neurons that are responsive to cool temperatures. Studies analyzing TREK-deficient mice revealed that coolness-evoked responses of GG neurons were clearly attenuated in these animals compared with wild-type conspecifics. These data suggest that TREK-1 channels significantly contribute to the responsiveness of GG neurons to cool temperatures, further supporting the concept that TREK channels serve as thermoreceptors in sensory cells. Moreover, the present findings provide the first evidence of how thermosensory GG neurons are activated by given temperature stimuli in the absence of thermo-TRPs.