Eukaryotic translation initiation machinery can operate in a prokaryotic-like mode without eIF2

Unlike prokaryotes, a specialized eukaryotic initiation factor 2 (eIF2), in the form of the ternary complex eIF2*GTP*Met-tRNAiMet is utilized to deliver the initiator tRNA to the ribosome within all eukaryotic cells1. Phosphorylation of eIF2 is known to be central to the global regulation of protein synthesis under stress conditions and infection2. Another distinctive feature of eukaryotic translation is scanning of mRNA 5'-leaders, whose origin in evolution may be relevant to the appearance of eIF2 in eukaryotes. Translation initiation on the hepatitis C virus (HCV) internal ribosome entry site (IRES) occurs without scanning3,4. Whether these unique features of the HCV IRES account for the formation of the final 80S initiation complex is unknown. Here we show that the HCV IRES-directed translation can occur without either eIF2 or its GTPase activating protein eIF5. In addition to the general eIF2- and eIF5-dependent pathway of 80S complex assembly, the HCV IRES makes use of a prokaryotic-like pathway which involves eIF5B, the analogue of bacterial IF25,6, instead of eIF2. This switch from a eukaryotic-like mode of AUG selection to a "bacterial" one occurs when eIF2 is inactivated by phosphorylation, a way with which host cells counteract infection. The relative resistance of HCV IRES-directed translation to eIF2 phosphorylation may represent one more line of defense used by this virus against host antiviral responses and can contribute to the well known resistance of HCV to interferon based therapy

CLASSIFICATION OF TAGGED MATERIAL IN A SET OF TOMOGRAPHIC IMAGES OF COLORECTAL REGION

method of classification of image portions corresponding to faecal residues from a tomographic image of a colorectal region, which comprises a plurality of voxels (2) each having a predetermined intensity value and which shows at least one portion of colon (6a, 6b, 6c, 6d) comprising at least one area of tagged material (10). The area of tagged material (10) comprises at least one area of faecal residue (10a) and at least one area of tissue affected by tagging (10b). The image further comprises at least one area of air (8) which comprises an area of pure air (8a) not influenced by the faecal residues. The method comprises the operations of identifying (100), on the basis of a predetermined identification criterion based on the intensity values, above-threshold connected regions comprising connected voxels (2) and identifying, within the above-threshold connected regions, a plurality of connected regions of tagged material comprising voxels (2) representing the area of tagged material (10). The method further comprises the operation of classifying (104) each plurality of connected regions of tagged material on the basis of specific classification comparison criteria for each connected region, in such a way as to identify voxels (20) corresponding to the area of faecal residue (10a) and voxels (2) corresponding to the area of tissue affected by tagging (10b)

Method of classification of tagged material in a set of tomographic images of colorectal region

A method of classification of image portions corresponding to fecal residues from a tomographic image of a colorectal region, which comprises a plurality of voxels (2) each having a predetermined intensity value and which shows at least one portion of colon (6 a, 6 b, 6 c, 6 d) comprising at least one area of tagged material (10). The area of tagged material (10) comprises at least one area of fecal residue (10 a) and at least one area of tissue affected by tagging (10 b). The image further comprises at least one area of air (8) which comprises an area of pure air (8 a) not influenced by the fecal residues. The method comprises the operations of identifying (100), on the basis of a predetermined identification criterion based on the intensity values, above-threshold connected regions comprising connected voxels (2) and identifying, within the above-threshold connected regions, a plurality of connected regions of tagged material comprising voxels (2) representing the area of tagged material (10). The method further comprises the operation of classifying (104) each plurality of connected regions of tagged material on the basis of specific classification comparison criteria for each connected region, in such a way as to identify voxels (20) corresponding to the area of fecal residue (10 a) and voxels (2) corresponding to the area of tissue affected by tagging (10 b)

Calculation of the Thermal State of the Graphite Moderator of the RBMK Reactor

This work is devoted to study the temperature field of the graphite stack of the RBMK reactor. In work was analyzed the influence of contact pressure between the components of the masonry on the temperature of the graphite moderator

Calculation of the Thermal State of the Graphite Moderator of the RBMK Reactor

This work is devoted to study the temperature field of the graphite stack of the RBMK reactor. In work was analyzed the influence of contact pressure between the components of the masonry on the temperature of the graphite moderator

Temperature Dependence of the Surface Anisotropy of Fe Ultrathin Films on Cu(001)

We report an experimental approach to separate temperature dependent reversible and irreversible contributions to the perpendicular magnetic anisotropy of Fe films grown at low temperatures on Cu(001) substrates. The surface anisotropy KS(T) is found to decrease linearly with temperature, causing a thermally induced spin reorientation into the plane. The irreversible shift of the spin reorientation transition and the coercivity of the iron films are directly correlated to the increasing Fe island size during annealing. The increased coercivity is discussed in terms of domain wall energy inhomogeneities provided by the islands

Temperature Dependence of the Surface Anisotropy of Fe Ultrathin Films on Cu(001)

We report an experimental approach to separate temperature dependent reversible and irreversible contributions to the perpendicular magnetic anisotropy of Fe films grown at low temperatures on Cu(001) substrates. The surface anisotropy KS(T) is found to decrease linearly with temperature, causing a thermally induced spin reorientation into the plane. The irreversible shift of the spin reorientation transition and the coercivity of the iron films are directly correlated to the increasing Fe island size during annealing. The increased coercivity is discussed in terms of domain wall energy inhomogeneities provided by the islands

The 5′ untranslated region of Apaf-1 mRNA directs translation under apoptosis conditions via a 5′ end-dependent scanning mechanism

AbstractWe have previously shown that translation driven by the 5′ UTR of Apaf-1 mRNA is relatively efficient in the absence of m7G-cap, but no IRES is involved. Nevertheless, it may be speculated that a “silent” IRES is activated under apoptosis conditions. Here, we show that translation of the mRNA with the Apaf-1 5′ UTR is relatively resistant to apoptosis induced by etoposide when eIF4E is sequestered by 4E-BP and eIF4G is partially cleaved. However, translation under these conditions remains governed by 5′ end-dependent scanning. We hypothesize that the observed phenomenon is based on the intrinsic low cap-dependence of the Apaf-1 5′ UTR