847 research outputs found
Mycobacterium smegmatis RNase J is a 5’-3’ exo-/endoribonuclease and both RNase J and RNase E are involved in ribosomal RNA maturation
No full textThe presence of very different sets of enzymes, and in particular the presence of RNase E and RNase J, has been used to explain significant differences in RNA metabolism between the two model organisms Escherichia coli and Bacillus subtilis. However, these studies might have somewhat polarized our view of RNA metabolism. Here, we identified a RNase J in Mycobacterium smegmatis that has both 5'-3' exo- and endonucleolytic activity. This enzyme coexists with RNase E in this organism, a configuration that enabled us to study how these two key nucleases collaborate. We demonstrate that RNase E is responsible for the processing of the furA-katG transcript in M.smegmatis and that both RNase E and RNase J are involved in the 5' end processing of all ribosomal RNAs. In contrast to B.subtilis, the activity of RNase J, although required in vivo for 23S rRNA maturation, is not essential in M.smegmatis. We show that the pathways for ribosomal RNA maturation in M.smegmatis are quite different from those observed in E.coli and in B.subtilis. Studying organisms containing different combinations of key ribonucleases can thus significantly broaden our view of the possible strategies that exist to direct RNA metabolism
Mittag–Leffler Functions in Discrete Time
No full textIn this paper, we give an efficient way to calculate the values of the Mittag–Leffler (h-ML) function defined in discrete time hN, where h>0 is a real number. We construct a matrix equation that represents an iteration scheme obtained from a fractional h-difference equation with an initial condition. Fractional h-discrete operators are defined according to the Nabla operator and the Riemann–Liouville definition. Some figures and examples are given to illustrate this new calculation technique for the h-ML function in discrete time. The h-ML function with a square matrix variable in a square matrix form is also given after proving the Putzer algorithm
Linear ODEs: an Algebraic Perspective
No full textThis booklet was intended to provide a minimum of ready-to-use references for the minicourse given by the author during the XXII E ́scola de Algebra (40 Anos), held in Salvador de Bahia (July 2012). It wishes to bring to the fore a number of relationships with other branches of mathematics. Examples include the theory of symmetric functions, the theory of universal decomposition algebras associated to a polynomial, derivations of the exterior algebra of a free module, D-modules, Schubert calculus for the complex Grassmannian, boson-fermion correspondence in the representation theory of the Heisenberg algebr
mRNA degradation and maturation in prokaryotes : the global players
No full textInternational audienc
Reference Scenario and Target Identification for Autonomous Active Space Debris Removal Methods
No full textTo alleviate the threat of space debris, a combination of
debris mitigation measures and debris environment re-
mediation techniques with regard to long-term environ-
ment stability is required. Hereby, active space debris
removal (ADR), which is subject to this paper, addresses
the latter. To evolve a concept for autonomous ADR on a
representative foundation, a reference scenario placed in
the current Low Earth Orbit environment has been gen-
erated. Due to cost-effectiveness, a single mission to dis-
pose multiple targets is addressed. The filtering process is
presented and a glance on the autonomy concept of cog-
nitive automation is given
Remarks on Mittag-Leffler Discrete Function and Putzer Algorithm for Fractional h-Difference Linear Equations
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