Functional expression of an antimicrobial peptide, belonging to halocin C8 family, from Natrinema sp. RNS21 in Escherichia coli.

Halocins, the proteinaceous antimicrobial agents produced by haloarchaea, may be used for the preservation of salted foods and the treatment of diseases. For their application and function explanation, it is necessary to produce the active recombinants. In this work, a haloarchaeal strain producing halocin was isolated from the salt-fermented shrimp and identified as Natrinema sp. RNS21 by 16S rRNA gene sequence analysis. From 1 L of RNS21 culture, about 0.32 mg of halocin with 96% purity was obtained. Based on the molecular weight, stability and amino acid sequence alignment, the antimicrobial peptide belonged to the halocin C8 (HalC8) family. HalC8 was expressed by fusion with glutathione-S-transferase (GST) in E. coli, followed by affinity purification and enterokinase (EK) cleavage. About 6.2 mg of recombinant HalC8 with 95% purity was obtained from 1 L of E. coli culture. MALDI-TOF-MS and RP-HPLC analysis indicated that the molecular weight and folding pattern of purified recombinant HalC8 were the same as those of native HalC8. Recombinant HalC8 showed obvious inhibitory activity against Haloferax volcanii. Contrast to native HalC8, the active recombinant HalC8 could be easily produced in a short time with a high yield.

A New Cache Update Scheme Using Reinforcement Learning for Coded Video Streaming Systems.

As the demand for video streaming has been rapidly increasing recently, new technologies for improving the efficiency of video streaming have attracted much attention. In this paper, we thus investigate how to improve the efficiency of video streaming by using clients' cache storage considering exclusive OR (XOR) coding-based video streaming where multiple different video contents can be simultaneously transmitted in one transmission as long as prerequisite conditions are satisfied, and the efficiency of video streaming can be thus significantly enhanced. We also propose a new cache update scheme using reinforcement learning. The proposed scheme uses a K-actor-critic (K-AC) network that can mitigate the disadvantage of actor-critic networks by yielding K candidate outputs and by selecting the final output with the highest value out of the K candidates. The K-AC exists in each client, and each client can train it by using only locally available information without any feedback or signaling so that the proposed cache update scheme is a completely decentralized scheme. The performance of the proposed cache update scheme was analyzed in terms of the average number of transmissions for XOR coding-based video streaming and was compared to that of conventional cache update schemes. Our numerical results show that the proposed cache update scheme can reduce the number of transmissions up to 24% when the number of videos is 100, the number of clients is 50, and the cache size is 5.

Position Tracking Techniques Using Multiple Receivers for Anti-Drone Systems.

The need for drone traffic control management has emerged as the demand for drones increased. Particularly, in order to control unauthorized drones, the systems to detect and track drones have to be developed. In this paper, we propose the drone position tracking system using multiple Bluetooth low energy (BLE) receivers. The proposed system first estimates the target's location, which consists of the distance and angle, while using the received signal strength indication (RSSI) signals at four BLE receivers and gradually tracks the target based on the estimated distance and angle. We propose two tracking algorithms, depending on the estimation method and also apply the memory process, improving the tracking performance by using stored previous movement information. We evaluate the proposed system's performance in terms of the average number of movements that are required to track and the tracking success rate.

Viral envelope protein 53R gene highly specific silencing and iridovirus resistance in fish Cells by AmiRNA.

BACKGROUND: Envelope protein 53R was identified from frog Rana grylio virus (RGV), a member of the family Iridoviridae, and it plays an important role in the virus assembly. Although inhibition of iridovirus major capsid protein (MCP) by small hairpin RNAs (shRNAs) has been shown to cause resistance to viral infection in vitro, RNA interference (RNAi) to inhibit aquatic animal virus envelope protein gene product has not been reported. METHODOLOGY: We devised artificial microRNAs (amiRNAs) that target a viral envelope protein gene RGV 53R. By incorporating sequences encoding amiRNAs specific to 53R of RGV into pre-miRNA155 (pSM155) vectors, which use the backbone of natural miR-155 sequence and could intracellularly express 53R-targeted pre-amiRNAs. The pre-amiRNAs could be processed by the RNase III-like enzyme Dicer into 21-25 nt amiRNAs (amiR-53Rs) in fish cell lines. The levels of 53R expression were analyzed through real-time PCR and RGV virions assembly were observed by electronic microscopy in fish cells transfected with or without amiR-53Rs at 72 h of RGV infection. CONCLUSION/SIGNIFICANCE: The results argue that viral envelope protein RGV 53R can be silenced and the virions assembly was deficient by amiR-53R-1, and further identified the first amiRNA of envelope protein gene from iridovirus that was able to cause resistance to virus infection in fish cells. The data demonstrate that the viral infection is efficiently suppressed (58%) by amiR-53R-1 targeting positon 36-57 of RGV 53R. Moreover, electron microscopic observations revealed virion assembly defect or reduced virions assembly capacity was closely correlated to expression of amiR-53R-1. Based on real time PCR of the Mx gene, we found no evidence of activation of IFN by amiR-53R-1.

Effect of beta-glucan on activity of antioxidant enzymes and Mx gene expression in virus infected grass carp.

The effects of beta-glucan, an immunostimulatory agent, on the superoxide dismutase (SOD) and catalase (CAT) activities of erythrocytes and Mx gene expression were studied from grass carp that were challenged with grass carp hemorrhage virus (GCHV). The SOD and CAT activities in erythrocytes and Mx gene expression in spleen from the fish were detected by spectrophotometry and RT-PCR, respectively. Negative control fish were injected with PBS; positive control groups were injected with either beta-glucan or GCHV only; and the experimental groups were pre-injected with beta-glucan 15 days prior to injection with GCHV. The results show that the SOD and CAT activities were higher in fish injected with beta-glucan for 15 days than the negative control group injected with PBS. The SOD and CAT activities significantly decreased when the fish were challenged with GCHV, but it was higher in the group pre-treated with beta-glucan than in infected fish not pre-treated, 15 days after GCHV infection. Mx gene expression levels increased during the early stages (at 12 h and 36 h) of GCHV infection, and it remained at higher levels from the 6th till the 10th day in the beta-glucan pre-treated group, but it was falling from the 6th day in the beta-glucan untreated group. The GCHV-infected group pre-treated with beta-glucan had a higher survival rate (60%) than the group not pre-treated with beta-glucan (20%), suggesting that beta-glucan possesses or enhances anti-viral responses.

Identification and functional analysis of LsMNPV anti-apoptosis genes.

Three anti-apoptosis genes, Ls-iap2, iap3 and p49 were found in Leucania separata multiple nuclear polyhedrovirus. Amino acid sequence homology of Ls-IAP2 and Ls-IAP3 with Op-IAP2 and Op-IAP3 from Orgyia pseddotsugata MNPV were 20% and 42%, while that of Ls-P49 is 28% with Sl-P49 from Spodoptera littorolis MNPV. Ls-IAP2 contains one baculoviral IAP repeat (BIR) domain followed by a RING domain, while Ls-IAP3 contains two BIRs and a RING. Ls-P49 contains a reactive site loop, predicted cleavage site (KKLD(74) downward arrow G) that is different from Sl-P49 (TVID(94) downward arrow G). Expressed Ls-iap3 or Ls-p49 under presence of actinomycin D in SF9 cells, DNA ladder assay revealed that Ls- IAP3 or Ls-P49 could block the apoptosis of SF9 cells induced by actinomycin D. Replication of p35 deficient-mutant Autographa californica MNPV in SF9 cells was also rescued when Ls-iap3 or Ls-p49 was expressed transiently. No anti-apoptotic activity was observed for Ls-IAP2. The results showed that both of Ls-IAP3 and Ls-P49 were functional apoptotic suppressors in SF9 cells.