Mobile Host mRNAs Are Translated to Protein in the Associated Parasitic Plant Cuscuta campestris

Cuscuta spp. are obligate parasites that connect to host vascular tissue using a haustorium. In addition to water, nutrients, and metabolites, a large number of mRNAs are bidirectionally exchanged between Cuscuta spp. and their hosts. This trans-specific movement of mRNAs raises questions about whether these molecules function in the recipient species. To address the possibility that mobile mRNAs are ultimately translated, we built upon recent studies that demonstrate a role for transfer RNA (tRNA)-like structures (TLSs) in enhancing mRNA systemic movement. C. campestris was grown on Arabidopsis that expressed a β-glucuronidase (GUS) reporter transgene either alone or in GUS-tRNA fusions. Histochemical staining revealed localization in tissue of C. campestris grown on Arabidopsis with GUS-tRNA fusions, but not in C. campestris grown on Arabidopsis with GUS alone. This corresponded with detection of GUS transcripts in Cuscuta on Arabidopsis with GUS-tRNA, but not in C. campestris on Arabidopsis with GUS alone. Similar results were obtained with Arabidopsis host plants expressing the same constructs containing an endoplasmic reticulum localization signal. In C. campestris, GUS activity was localized in the companion cells or phloem parenchyma cells adjacent to sieve tubes. We conclude that host-derived GUS mRNAs are translated in C. campestris and that the TLS fusion enhances RNA mobility in the host-parasite interactions.

POTENSI PENGGUNAAN MOBILE AD-HOC NETWORK (MANET) SEBAGAI ALAT KOMUNIKASI DATA PADA TRANSPORTASI DI INDONESIA

Ad Hoc Network adalah jaringan wireless yang terdiri dari kumpulan node bersifat dinamik yang dapat saling berkomunikasi. Node tidak hanya berfungsi sebagai pengirim dan penerima informasi data tetapi juga berfungsi sebagai jalur jaringan tempat informasi data yang terkirim. Mobile Ad Hoc Network (MANET) adalah kumpulan dari beberapa wireless node yang dapat diatur secara dinamis di lokasi manapun dan tidak terbatas waktu tanpa menggunakan infrastruktur jaringan yang ada. MANET tidak memerlukan pusat administrasi dan infrastruktur kabel. MANET pada mobile host yang terhubung dengan wireless dapat bergerak bebas dan juga berperan sebagai router. Makalah ini memberikan wawasan tentang karakteristik MANET, aplikasi potensi dalam memanfaatkan teknologi MANET sebagai Alat Komunikasi Data Transportasi di Indonesia.

Distributed Identifier-Locator Mapping Management in Mobile ILNP Networks

In the Identifier Locator Network Protocol (ILNP) networks, the existing mobility control schemes based on the centralized entity, called the Dynamic Domain Name Service (DDNS) server, such that all the control traffic is processed at the DDNS server. However, the centralized mobility schemes have significant limitations, such as control traffic overhead at the server and large handover delay. In order to resolve these issues, we propose a new mobility control scheme for ILNP networks, which manages the identifier-locators (ID-LOCs) in the fully distributed manner. In our scheme, each domain has a dedicated mobile DDNS (m-DDNS) server at the site border router (SBR). The m-DDNS server maintains two databases; i.e., home host register (HHR) and visiting host register (VHR), to support the roaming of mobile hosts. When a mobile host roams into a domain, the m-DDNS server in the visiting domain registers the host’s ID-LOC in the VHR and requests the update of HHR to the m-DDNS server in the home domain. Since the m-DDNS servers communicate each other directly, the ID-LOC mappings are managed without involvement of any central entities. We analyzed our proposed mobility scheme via numerical analysis and compared its performance with those of existing schemes. Numerical results showed that our scheme outperforms the existing mobility control schemes substantially in terms of control traffic overhead at the servers, total transmission delay and handover delay.

A Trust Based Secured Routing Protocol for Mobile Adhoc Network

Mobile Ad hoc Network (MANET) is a group of wireless mobile nodes that dynamically creates a network without the support of central management. The mobile hosts of MANET network are not restricted to move freely in any direction and thus linking with any other mobile host can be easily done. Without giving any notification to other hosts in the network, they can be switched on or off. Each mobile host must forward traffic, unrelated to its own use and therefore acts as a router. Because of the mobility of wireless nodes, each node must have the capability of managing an autonomous system, or a routing function without requiring any centralized administration. This mobility and autonomy of the wireless nodes along with the transient nature of the end hosts and intermediate host in a communication path creates a dynamic topology of the network. These mobile hosts are connected in an arbitrary manner and as they are highly mobile, the topology changes take place frequently. The rate of change is based on the velocity of the nodes and the challenge is these devices are small and the available transmission power is limited. In this Trust Based Secured Routing Protocol for MANET (TSRPM), certain changes have been made in the design of secure ad hoc routing protocols. First, a modified Diffie Hellman algorithm is implemented; secondly a trust based model has been developed.

Determinants of parasite distribution in Arctic charr populations: catchment structure versus dispersal potential

Parasite distribution patterns in lotic catchments are driven by the combined influences of unidirectional water flow and the mobility of the most mobile host. However, the importance of such drivers in catchments dominated by lentic habitats are poorly understood. We examined parasite populations of Arctic charr Salvelinus alpinus from a series of linear-connected lakes in northern Norway to assess the generality of lotic-derived catchment-scale parasite assemblage patterns. Our results demonstrated that the abundance of most parasite taxa increased from the upper to lower catchment. Allogenic taxa (piscivorous birds as final host) were present throughout the entire catchment, whereas their autogenic counterparts (charr as final hosts) demonstrated restricted distributions, thus supporting the theory that the mobility of the most mobile host determines taxa-specific parasite distribution patterns. Overall, catchment-wide parasite abundance and distribution patterns in this lentic-dominated system were in accordance with those reported for lotic systems. Additionally, our study highlighted that upper catchment regions may be inadequate reservoirs to facilitate recolonization of parasite communities in the event of downstream environmental perturbations.

LIFT: a Local IPSec-aware Freezing Protocol to improve TCP Performance in Satellite Networks

In this paper a protocol, local to the satellite link, is defined in order to boost TCP performance in mobile integrated wired-satellite Internet. It has been conceived to help to overcome the well known retransmissions competition problem that arises when a satellite reliable link layer protocol is used to face satellite link errors. This protocol, called Local IPSec-aware Freezing proTocol (LIFT), has been designed to allow the satellite gateway, even in the presence of communications secured by IPSec, to freeze the TCP sender when it perceives a possible delay due to satellite channel conditions. The effectiveness of LIFT has been evaluated, using the ns-2 tool, in terms of Web page download mean time for a satellite mobile host. Simulation results have shown that the adoption of LIFT protocol provides substantial improvements in TCP performance.

Mobility Analysis for Passive Reservations in Vehicular Cellular Networks Based on Dynamic Programming and Roads Compression

The employment of an appropriate Bandwidth Management Scheme (BMS) is needed in wireless networking, given that the main desire of end-users is to take advantage of satisfactory services, in terms of Quality of Service (QoS), especially when a particular charge is paid to meet the requirement. In this paper the authors are interested in investigating how the continuity of services can be guaranteed in QoS networks, when users move from a cell to another one, under an infrastructure cellular coverage. The only way to face this issue is represented by the employment of in-advance bandwidth reservations, although it leads the system to waste bandwidth resources, since they are not used until the mobile host enters the coverage cell where the passive request has been made. A new scheme for predicting user movements is proposed, taking the advantage of the dynamic programming approach, that is able to reduce the number of possible roads to be considered and thereby increasing/decreasing the accuracy/redundancy of the proposed model. Several simulation runs have been carried out in order to assess the effectiveness of the proposed idea.