Analysis of the Role of EIF5A in Mammalian Translation

MYC is a critical growth-promoting gene that is subject to tight post-transcriptional control. However, the genes and mechanisms that mediate this regulation at the mRNA level are poorly understood. In order to identify regulators of MYC that function through the 5' UTR of the transcript, we performed a fluorescent reporter-coupled genome-scale CRISPR/Cas9-mediated loss of function screen. Analysis of screening data identified eukaryotic initiation factor 5A (EIF5A) as novel regulator of MYC translation. eIF5A is a highly conserved translation factor that has been demonstrated to relieve ribosome pauses during translation elongation at 'difficult to translate' peptide sequences in yeast and bacteria. We observed that eIF5A regulates protein isoform distribution of MYC, and that loss of function of this gene results in enhanced upstream non-canonical translation initiation on this transcript. Upon performing ribosome profiling in cells where eIF5A or its upstream activating enzyme were ablated, we discovered that the protein's function as a ribosome pause relief factor is conserved in mammalian cells. Importantly, analysis of ribosome profiling data under conditions of eIF5A depletion revealed not only evidence of enhanced ribosome pausing within coding sequences at elongation stall sites, but also an increase in non-canonical/sub-optimal translation initiation events in 5' UTRs in both yeast and human cells. These data lead us to formulate and test the hypothesis that ribosome pausing resulting from loss of eIF5A increases non-canonical translation initiation at pause-proximal upstream sub-optimal initiation codons. We present data from ribosome profiling experiments in yeast and human cells, as well as luciferase reporter assays that are consistent with this model. Thus, we propose a novel role for the translation elongation factor eIF5A in maintaining appropriate start codon selection during initiation in eukaryotic cells

Approximate Analysis of Open Network of GE/GE/m/N Queues with Transfer

In this paper we describe an approximate method for the analysis of an open network of finite capacity queues. Finite buffer capacities at the nodes introduce blocking of jobs that finish service at a node and find that the destination node is full at that time. When this happens, we assume that the blocked job is held at the server of the queue where it just completed service, blocking that server until the destination can accommodate it. This is called transfer blocking or blocking after service. We also assume that an external arrival that finds a full queue is lost

The Queueing Network Analysis Tool (QNAT)

In this paper we describe QNAT, a software tool developed at Indian Institute of Technology, Kanpur, India, for the analysis and simulation of queueing networks. Arbitrary configurations of open or closed networks of multiserver queues with infinite or finite capacity, fork-join queues with or without synchronization queues can be analyzed or simulated using QNAT . Queueing Networks with multiple classes of customers may be specified with each class being a closed or an open class independently. If there are finite capacity queues in the system, the type of blocking mechanism - transfer, repetitive service or rejection, can also be specified. For the applications where the accuracy of the results is important, an option to simulate the network is also provided. QNAT has proved to be a useful tool for the design of telecommunication systems, computer networks, modeling of industrial systems, design of banking systems, teaching courses and research on queueing theory etc

Analysis of Two Outbreaks of Scrub Typhus in Rajasthan : A Clinico-epidemiological Study

Abstract Aims and Objectives : To describe the diversity of clinical manifestations, laboratory findings and outcome of scrub typhus in hospitalised patients of SMS Hospital, Jaipur during 2012 and 2013. Material and Methods : All the cases of febrile illness with thrombocytopenia diagnosed as scrub typhus were analysed. Diagnosis was made by ELISA based IgM serology. Observations and Results : A total of 125 patients were studied. All of them presented with fever; the other major symptoms were headache, cough, dyspnoea and myalgias. On examination, patients had hepatosplenomegaly, lymphadenopathy and eschar. On investigation elevated SGOT, SGPT with normal or elevated bilirubin levels were the most common findings. Other laboratory findings were thrombocytopenia and deranged renal function tests. Most common X-ray finding observed in these patients was bilateral lung infiltrates. Other complications were MODS, ARDS, hypotension and meningoencephalitis. Majority responded to doxycycline. Conclusion : Scrub typhus though prevalent is under-reported in our country. It should be considered as an important differential diagnosis in a febrile patient with thrombocytopenia, deranged liver or renal functions, and B/L chest opacities. Early diagnosis and appropriate treatment is rewarding and prevents morbidity and mortality