RADX controls RAD51 filament dynamics to regulate replication fork stability.

The RAD51 recombinase forms nucleoprotein filaments to promote double-strand break repair, replication fork reversal, and fork stabilization. The stability of these filaments is highly regulated, as both too little and too much RAD51 activity can cause genome instability. RADX is a single-strand DNA (ssDNA) binding protein that regulates DNA replication. Here, we define its mechanism of action. We find that RADX inhibits RAD51 strand exchange and D-loop formation activities. RADX directly and selectively interacts with ATP-bound RAD51, stimulates ATP hydrolysis, and destabilizes RAD51 nucleofilaments. The RADX interaction with RAD51, in addition to its ssDNA binding capability, is required to maintain replication fork elongation rates and fork stability. Furthermore, BRCA2 can overcome the RADX-dependent RAD51 inhibition. Thus, RADX functions in opposition to BRCA2 in regulating RAD51 nucleofilament stability to ensure the right level of RAD51 function during DNA replication.

Replication fork uncoupling causes nascent strand degradation and fork reversal.

Genotoxins cause nascent strand degradation (NSD) and fork reversal during DNA replication. NSD and fork reversal are crucial for genome stability and are exploited by chemotherapeutic approaches. However, it is unclear how NSD and fork reversal are triggered. Additionally, the fate of the replicative helicase during these processes is unknown. We developed a biochemical approach to study synchronous, localized NSD and fork reversal using Xenopus egg extracts and validated this approach with experiments in human cells. We show that replication fork uncoupling stimulates NSD of both nascent strands and progressive conversion of uncoupled forks to reversed forks. Notably, the replicative helicase remains bound during NSD and fork reversal. Unexpectedly, NSD occurs before and after fork reversal, indicating that multiple degradation steps take place. Overall, our data show that uncoupling causes NSD and fork reversal and elucidate key events that precede fork reversal.

Effect of Dietary Supplementation of Bacillus subtilis on Growth Performance, Organ Weight, Digestive Enzyme Activities, and Serum Biochemical Indices in Broiler.

This study was conducted to investigate the effects of supplementing Bacillus subtilis and an antibiotic (Zinc bacitracin) in the diet of broilers on growth performance, organ weight, blood metabolites, and digestive enzymes of broiler chickens. A total of 600 1-d Arbor Acres broilers were randomly allotted to five treatments. Each treatment consisted of six replicates with four pens, and each pen had five birds. The chicks were fed (1) the basal diet (control), (2) the basal diet with 500 mg/kg Zinc bacitracin (APZ), (3) the basal diet with B. subtilis at 1 × 108 CFU/g (B.Sut-1), (4) the basal diet with B. subtilis at 3 × 108 CFU/g (B.Sut-3), and (5) the basal diet with B. subtilis at 5 × 108 CFU/g (B.Sut-5). The experiment lasted for 42 days. In this study, the supplementation of diets with B. subtilis (B.Sut-3 and B.Sut-5 groups) increased body weight gain from 1 to 21 days compared with control (p < 0.05). Additionally, the B.Sut-3 group had a significantly heavier bursa of Fabricius than control at 21 days (p < 0.05). Serum total protein, albumin, and high-density lipoprotein concentrations were increased in B.Sut-5 and APZ groups (p < 0.05) over the whole period. Serum low-density lipoprotein, very low-density lipoprotein, triglyceride, and total cholesterol concentrations were decreased in B.Sut-5 and APZ groups at 21 and 42 days (p < 0.05). Chicks in the B.Sut-5 and APZ groups had higher serum lipase, pepsin, and amylase activities (p < 0.05) at 21 and 42 days. From the results obtained from the study, it can be concluded that Bacillus subtilis ATCC19659 at 5 × 108 CFU/g could be applied as an alternative to antibiotics in poultry diets.

Efficient VANET safety message delivery and authenticity with privacy preservation.

Vehicular ad-hoc networks (VANETs) play an essential role in the development of the intelligent transportation system (ITS). VANET supports many types of applications that have strict time constraints. The communication and computational overheads are minimal for these computations and there are many security requirements that should be maintained. We propose an efficient message authentication system with a privacy preservation protocol. This protocol reduces the overall communication and computational overheads. The proposed protocol consists of three main phases: the group registration phase, send/receive messages phase, and the leave/join phase. For cryptography algorithms, we combined symmetric and asymmetric key algorithms. The symmetric key was generated and exchanged without using the Diffie-Hellman (DH) protocol. Furthermore, we used an efficient version of the RSA algorithm called CRT-RSA. The experimental results showed that the computational overhead in the registration phase was significantly reduced by 91.7%. The computational overhead for sending and receiving the non-safety message phase was reduced by 41.2% compared to other existed protocols. Moreover, our results showed that the time required to broadcast a safety and non-safety group message was below 100 ms and 150 ms, respectively. The average computational time of sending and receiving a one-to-one message was also calculated. The proposed protocol was also evaluated with respect to performance and security and was shown to be invulnerable to many security attacks.

Constructing a cohesive pattern for collective navigation based on a swarm of robotics.

Swarm robotics carries out complex tasks beyond the power of simple individual robots. Limited capabilities of sensing and communication by simple mobile robots have been essential inspirations for aggregation tasks. Aggregation is crucial behavior when performing complex tasks in swarm robotics systems. Many difficulties are facing the aggregation algorithm. These difficulties are as such: this algorithm has to work under the restrictions of no information about positions, no central control, and only local information interaction among robots. This paper proposed a new aggregation algorithm. This algorithm combined with the wave algorithm to achieve collective navigation and the recruitment strategy. In this work, the aggregation algorithm consists of two main phases: the searching phase, and the surrounding phase. The execution time of the proposed algorithm was analyzed. The experimental results showed that the aggregation time in the proposed algorithm was significantly reduced by 41% compared to other algorithms in the literature. Moreover, we analyzed our results using a one-way analysis of variance. Also, our results showed that the increasing swarm size significantly improved the performance of the group.

Feeding Bacillus subtilis ATCC19659 to Broiler Chickens Enhances Growth Performance and Immune Function by Modulating Intestinal Morphology and Cecum Microbiota.

This study investigated dietary supplementation with Bacillus subtilis (BS) ATCC19659 on growth performance, biochemical indices, intestinal morphology, and cecum microflora in broiler chicks. A total of 600 Arbor 1-day Acres broilers of either sex were allotted to 5 treatments: chicks were fed a corn- and soybean-based diet (CON); chicks were fed basal diet containing 500 mg ZnB/kg (ZnB); chicks were fed basal diet containing 1 × 108 CFU/g feed of BS-ATCC19659 (BS-1); chicks were fed basal diet containing 3 × 108 CFU/g feed of BS-ATCC19659 (BS-3); and chicks were fed basal diet containing 5 × 108 CFU/g feed of BS-ATCC19659 (BS-5). Each treatment comprised 6 replicates with 20 birds for each replicate pen. Chicks in the BS-5 and BS-3 groups had higher body weight at the 21st and 42nd days and average daily gain from 1 to 21 days than that in the CON group (p < 0.05). Chicks in the BS-5 and ZnB groups had higher serum antioxidant activities and immunity response than those in the CON group (p < 0.05). Compared with the CON group, the liver mRNA abundance of GHR, TGF-ß, IGF-1, IFN-γ, SOD, CAT, and GPX of chicks in three BS groups and the ileum villus length (µm) of chicks in BS-3 and ZnB groups was increased (p < 0.05). Compared with the CON group, the villus height-to-crypt depth ratio of the ileum of chicks in the BS-5 and BS-3 groups and the crypt depth and villus height-to-crypt depth ratio of the jejunum in the BS-5 and ZnB groups were increased (p < 0.05). The abundance of the Cyanobacteria phyla in the cecum decreased in response to treatment with both BS-ATCC19659 and ZnB groups (p < 0.05). Compared with the CON group, the cecum abundance of genera GCA-900066575 (Lachnospiraceae), Anaerofustis, and Papillibacter (Firmicutes phylum) in three BS groups were increased (p < 0.05); The abundance of genus Escherichia-Shigella reduced in the BS-3 group (p < 0.05). Compared with the CON group, the cecum abundance of genus Clostridia_unclassified in ZnB and BS-5 groups was decreased (p < 0.05) of broilers. Generally, Bacillus subtilis ATCC19659 as feed additive positively affected growth performance, immunity response, and cecal microflora of broilers.