The hnRNP C proteins contain a nuclear retention sequence that can override nuclear export signals.

Nascent pre-mRNAs associate with the abundant heterogeneous nuclear RNP (hnRNP) proteins and remain associated with them throughout the time they are in the nucleus. The hnRNP proteins can be divided into two groups according to their nucleocytoplasmic transport properties. One group is completely restricted to the nucleus in interphase cells, whereas the other group, although primarily nuclear at steady state, shuttles between the nucleus and the cytoplasm.

Signal-mediated nuclear export pathways of proteins and RNAs.

Although it has been known for several years that most nuclear-encoded RNAs and some patients can be exported from the nucleus to the cytoplasm, the molecular mechanisms of these transport processes have been poorly understood. Recently, signals that can induce the rapid and active nuclear export of macromolecules have been identified in the HIV-1 Rev protein, the inhibitor of cAMP-dependent protein kinase (PKI) and the hnRNP A1 protein. Thus, nuclear export appears to be mechanistically similar to nuclear import that it requires specific signal-receptor systems.

A novel nuclear structure containing the survival of motor neurons protein.

Spinal muscular atrophy (SMA) is a common, often fatal, autosomal recessive disease leading to progressive muscle wasting and paralysis as a result of degeneration of anterior horn cells of the spinal cord. A gene termed survival of motor neurons (SMN), at 5q13, has been identified as the determining gene of SMA (Lefebvre et al., 1995).

Growth modification of Euglena gracilis Klebs after 2-benzamido-5-nitrothiazole derivatives application.

The toxic effect of 2-benzamido-5-nitrothiazole (BNT) and 11 of its derivatives on the growth of Euglena gracilis was studied in vitro and compared with that of niclosamide. These compounds inhibit proliferation of algae or, at low concentrations, stimulate proliferation. BNT and all its derivatives had an inhibiting effect that was less pronounced, however, than with niclosamide in most instances.

Specific sequences in the fragile X syndrome protein FMR1 and the FXR proteins mediate their binding to 60S ribosomal subunits and the interactions among them.

Fragile X syndrome, the most common form of hereditary mental retardation, usually results from lack of expression of the FMR1 gene. The FMR1 protein is a cytoplasmic RNA-binding protein. The RNA-binding activity of FMR1 is an essential feature of FMR1, as fragile X syndrome can also result from the expression of mutant FMR1 protein that is impaired in RNA binding.

Distinct domains in ribosomal protein L5 mediate 5 S rRNA binding and nucleolar localization.

Ribosomal protein L5, a 34-kDa large ribosomal subunit protein, binds to 5 S rRNA and has been implicated in the intracellular transport of 5 S rRNA. By immunofluorescence microscopy, L5 is detected mostly in the nucleolus with a fainter signal in the nucleoplasm, and it is known to also be a component of large ribosomal subunits in the cytoplasm. 5 S rRNA is transcribed in the nucleoplasm, and L5 is thought to play an important role in delivering 5 S rRNA to the nucleolus.

The Effect of Parasitism by Fasciola hepatica and Muellerius capillaris on the Nerve Ganglia of Lymnaea truncatula.

Morphometric and histopathological studies were performed in Lymnaea truncatula experimentally infected by Fasciola hepatica or Muellerius capillaris between Days 30 and 60 postinfection. In the pedal ganglia, snail parasitism had a significant influence on the decrease in length and the increase in width in the M. capillaris group.

The molluscicidal activity of two 2-benzamido-5-nitrothiazole bihalogenated derivatives and niclosamide. Influence of some environmental factors on their toxicity.

Two synthetic molluscicides, 3,4-dichloro-2-benzamido-5-nitrothiazole (3,4-dichloro-BNT) and 3,5-dichloro-BNT, were studied to determine their efficacy against the snail Lymnaea glabra. Results were compared with those of a reference molluscicide, niclosamide. Snail exposure to these chemicals markedly increased overall snail mortality during the experiment (96 h).

Paramphistomum daubneyi and Fasciola hepatica: the redial burden and cercarial shedding in Lymnaea truncatula subjected to successive unimiracidial cross-exposures.

The development of redial burden and cercarial shedding were studied in two groups of Lymnaea truncatula subjected to successive cross-exposures to one miracidium of Paramphistomum daubneyi and one of Fasciola hepatica per snail, or vice versa. The results were compared with those obtained in controls subjected to two unimiracidial exposures to the same trematode species. The infection rate was 61% in the group cross-exposed to P.

The development of tissue lesions in the snail Lymnaea glabra exposed to a sublethal dose of molluscicide.

Histological examinations were undertaken in adult Lymnaea glabra to determine whether tissue lesions develop in snails that survived exposure to a molluscicidal agent and thus impair survival or reproduction capacities of remaining snails. The snails were exposed for 4 days to sublethal doses of niclosamide (0.21 mg/L), 3,4-dichloro-2-benzamido-5-nitrothiazole (0.

A nuclear export signal in hnRNP A1: a signal-mediated, temperature-dependent nuclear protein export pathway.

Pre-mRNAs are associated with hnRNPs, and these proteins play important roles in the biogenesis of mRNAs. The hnRNP A1 is one of the most abundant hnRNPs, and although localized primarily in the nucleoplasm, shuttles continuously between the nucleus and the cytoplasm. A 38 amino acid domain within A1, termed M9, which bears no resemblance to classical nuclear localization signal (NLS) sequences, localizes A1 to the nucleus.

Cell type-specific expression of hnRNP proteins.

HnRNP proteins are abundant nucleoplasmic pre-mRNA-binding proteins which have important roles in the biogenesis of mRNA. Although hnRNP proteins have been extensively characterized in cultured cell lines, little is known about their expression in animal tissues. Here, we have undertaken a systematic survey of the expression of major hnRNP proteins in mouse tissue using specific monoclonal antibodies.

The fragile X mental retardation syndrome protein interacts with novel homologs FXR1 and FXR2.

Fragile X Mental Retardation Syndrome is the most common form of hereditary mental retardation, and is caused by defects in the FMR1 gene. FMR1 is an RNA-binding protein and the syndrome results from lack of expression of FMR1 or expression of a mutant protein that is impaired in RNA binding. The specific function of FMR1 is not known.

FXR1, an autosomal homolog of the fragile X mental retardation gene.

Fragile X mental retardation syndrome, the most common cause of hereditary mental retardation, is directly associated with the FMR1 gene at Xq27.3. FMR1 encodes an RNA binding protein and the syndrome results from lack of expression of FMR1 or expression of a mutant protein that is impaired in RNA binding.

In vivo and in vitro arginine methylation of RNA-binding proteins.

Heterogenous nuclear ribonucleoproteins (hnRNPs) bind pre-mRNAs and facilitate their processing into mRNAs. Many of the hnRNPs undergo extensive posttranslational modifications including methylation on arginine residues. hnRNPs contain about 65% of the total NG,NG-dimethylarginine found in the cell nucleus.

A nuclear localization domain in the hnRNP A1 protein.

The heterogeneous nuclear RNP (hnRNP) A1 protein is one of the major pre-mRNA/mRNA binding proteins in eukaryotic cells and one of the most abundant proteins in the nucleus. It is localized to the nucleoplasm and it also shuttles between the nucleus and the cytoplasm. The amino acid sequence of A1 contains two RNP motif RNA-binding domains (RBDs) at the amino terminus and a glycine-rich domain at the carboxyl terminus.

Association of the vav proto-oncogene product with poly(rC)-specific RNA-binding proteins.

We have used the yeast two-hybrid system to isolate proteins that interact with the carboxy-terminal SH3-SH2-SH3 region of Vav. One of the clones encoded heterogeneous nuclear ribonucleoprotein K (hnRNP K), a poly(rC)-specific RNA-binding protein. The interaction between Vav and hnRNP K involves the binding of the most carboxy-terminal SH3 domain of Vav to two proline-rich sequences present in the central region of hnRNP K.

Trypanosoma brucei brucei: antitrypanosomal evaluation of stilbamidinium hexachloroiridiate on the murine CNS model and iridium serum kinetics in infected sheep.

Stilbamidinium hexachloroiridiate was found trypanocidal in vitro against Trypanosoma brucei brucei IPP at 600 microM after a 1 h incubation period and 30 microM after 24 h. This activity was confirmed in mice with a subcutaneous treatment at 20 mg/kg in a single dose. It was then evaluated on T.

Comparative studies on the productivity of Fasciola gigantica and F. hepatica sporocysts in Lymnaea tomentosa that died after a cercarial shedding or without emission.

A histology study was performed on Fasciola gigantica- or F. hepatica-infected Lymnaea tomentosa that died after a cercarial shedding or without emission to compare the parasite productivity of each trematode. Degenerated rediae increased in number throughout the experiment.

Fasciola hepatica: a study of the shedding of cercariae from Lymnaea truncatula raised under constant conditions of temperature and photoperiod.

Investigations on the shedding of cercariae of Fasciola hepatica were carried out in Lymnaea truncatula in order to verify the existence of a low-frequency periodicity in the numerical distribution of metacercariae per snail and per day when the snails are raised under controlled conditions. Preadult L. truncatula were thus collected in the field, individually exposed to two miracidia, and subsequently raised until their death under constant temperature (20 degrees C) and photoperiod (12 h/12 h diurnal rhythm).

The determinants of RNA-binding specificity of the heterogeneous nuclear ribonucleoprotein C proteins.

The hnRNP C proteins (C1/C2) are tenacious nuclear pre-mRNA-binding proteins that belong to the large RNP motif family of RNA-binding proteins. This motif identifies an RNA-binding domain (RBD) that consists of a four-stranded antiparallel beta-sheet packed against two alpha-helices. Despite considerable information on the structure of the hnRNP C RBD, little is known about its RNA-binding properties.

Conserved structures and diversity of functions of RNA-binding proteins.

In eukaryotic cells, a multitude of RNA-binding proteins play key roles in the posttranscriptional regulation of gene expression. Characterization of these proteins has led to the identification of several RNA-binding motifs, and recent experiments have begun to illustrate how several of them bind RNA. The significance of these interactions is reflected in the recent discoveries that several human and other vertebrate genetic disorders are caused by aberrant expression of RNA-binding proteins.