Identification of T-cell receptor V β deletion mutant mouse strain AU/ssJ (H-2 q ) which is resistant to collagen-induced arthritis

Our laboratory is involved in investigating the role of T-cell receptor (Tcr) in collagen-induced arthritis (CIA). During these studies we found AU/ssJ (H-2 ^q ) mice to be resistant to CIA like SWR (H-2 ^q ), as compared with other H-2 ^q strains with wild-type Tcr like DBA/1 and B 10. Q. Upon screening with monoclonal antibodies F23.1 and KJ23a, AU/ssJ was found to be F23.1 negative (V 8 Tcr negative) and KJ23a positive (V 17a Tcr positive). Southern blot analysis on liver DNA using specific Tcr-V probes confirmed the deletion of V 8 gene family and also showed that AU/ssJ mice have deletions of V 9, V 13, V 12, and V 11 genes of Tcr. Further, these mice show a restriction fragment length polymorphism pattern with V 10, V 6, and V 17 probes similar to SWR mice as compared with 1310 mice. Since SWR and AU/ssJ are from different backgrounds, these studies indicate that specific variable region chain genes of Tcr are crucial for susceptibility to CIA in mice. Furthermore, these studies identify an additional inbred strain which has also deleted 50% of its Tcr-V genes.     

Assignment of 1H, 13C, and 15N chemical shift resonances of P2 C-repressor protein

This note presents the ¹H, ¹³C, and ¹⁵N resonances assignment of the 22 kDa, dimeric, C-repressor protein from the P2 bacteriophage. The C-repressor controls the genetic switch that determines if the temperate P2 phage should exist in the lytic or lysogenic lifemode.     

Small-molecule inhibition of HIV-1 Vif

The HIV-1 protein Vif, essential for in vivo viral replication, targets the human DNA-editing enzyme, APOBEC3G (A3G), which inhibits replication of retroviruses and hepatitis B virus. As Vif has no known cellular homologs, it is an attractive, yet unrealized, target for antiviral intervention. Although zinc chelation inhibits Vif and enhances viral sensitivity to A3G, this effect is unrelated to the interaction of Vif with A3G. We identify a small molecule, RN-18, that antagonizes Vif function and inhibits HIV-1 replication only in the presence of A3G. RN-18 increases cellular A3G levels in a Vif-dependent manner and increases A3G incorporation into virions without inhibiting general proteasome-mediated protein degradation. RN-18 enhances Vif degradation only in the presence of A3G, reduces viral infectivity by increasing A3G incorporation into virions and enhances cytidine deamination of the viral genome. These results demonstrate that the HIV-1 Vif-A3G axis is a valid target for developing small molecule-based new therapies for HIV infection or for enhancing innate immunity against viruses.     

Intragenic suppressors of temperature-sensitive rne mutations lead to the dissociation of RNase E activity on mRNA and tRNA substrates in Escherichia coli

RNase E of Escherichia coli is an essential endoribonuclease that is involved in many aspects of RNA metabolism. Point mutations in the S1 RNA-binding domain of RNase E (rne-1 and rne-3071) lead to temperature-sensitive growth along with defects in 5S rRNA processing, mRNA decay and tRNA maturation. However, it is not clear whether RNase E acts similarly on all kinds of RNA substrates. Here we report the isolation and characterization of three independent intragenic second-site suppressors of the rne-1 and rne-3071 alleles that demonstrate for the first time the dissociation of the in vivo activity of RNase E on mRNA versus tRNA and rRNA substrates. Specifically, tRNA maturation and 9S rRNA processing were restored to wild-type levels in each of the three suppressor mutants (rne-1/172, rne-1/186 and rne-1/187), while mRNA decay and autoregulation of RNase E protein levels remained as defective as in the rne-1 single mutant. Each single amino acid substitution (Gly→Ala at amino acid 172; Phe → Cys at amino acid 186 and Arg → Leu at amino acid 187) mapped within the 5′ sensor region of the RNase E protein. Molecular models of RNase E suggest how suppression may occur.     

Mutations of ESRRB encoding estrogen-related receptor beta cause autosomal-recessive nonsyndromic hearing impairment DFNB35

In a large consanguineous family of Turkish origin, genome-wide homozygosity mapping revealed a locus for recessive nonsyndromic hearing impairment on chromosome 14q24.3-q34.12. Fine mapping with microsatellite markers defined the critical linkage interval to a 18.7 cM region flanked by markers D14S53 and D14S1015. This region partially overlapped with the DFNB35 locus. Mutation analysis of ESRRB, a candidate gene in the overlapping region, revealed a homozygous 7 bp duplication in exon 8 in all affected individuals. This duplication results in a frame shift and premature stop codon. Sequence analysis of the ESRRB gene in the affected individuals of the original DFNB35 family and in three other DFNB35-linked consanguineous families from Pakistan revealed four missense mutations. ESRRB encodes the estrogen-related receptor beta protein, and one of the substitutions (p.A110V) is located in the DNA-binding domain of ESRRB, whereas the other three are substitutions (p.L320P, p.V342L, and p.L347P) located within the ligand-binding domain. Molecular modeling of this nuclear receptor showed that the missense mutations are likely to affect the structure and stability of these domains. RNA in situ hybridization in mice revealed that Esrrb is expressed during inner-ear development, whereas immunohistochemical analysis showed that ESRRB is present postnatally in the cochlea. Our data indicate that ESRRB is essential for inner-ear development and function. To our knowledge, this is the first report of pathogenic mutations of an estrogen-related receptor gene.     

Evaluation of anthelmintic activity of Iris hookeriana against gastrointestinal nematodes of sheep

The objective of this study was to evaluate the anthelmintic efficacy of Iris hookeriana Linn. rhizome against gastrointestinal nematodes of sheep. A worm motility inhibition assay was used for in vitro study and a faecal egg count reduction assay was used for an in vivo study. The in vitro study revealed anthelmintic effects of crude aqueous extracts and crude ethanolic extracts on live Trichuris ovis worms (P < or = 0.05) as evident from their paralysis and/or death at 8 h after exposure. The aqueous extracts of I. hookeriana resulted in a mean worm motility inhibition of 54.0%, while ethanolic extracts resulted in a mean worm motility inhibition of 84.6%. The mean mortality index of aqueous extracts was 0.55, while for ethanolic extracts it was 0.85. The lethal concentration 50 for aqueous extracts was 0.45 mg ml- 1 and for ethanolic extracts it was 0.15 mg ml- 1. The in vivo anthelmintic activity of aqueous and ethanolic extracts of I. hookeriana in sheep naturally infected with mixed species of gastrointestinal nematodes demonstrated a maximum (45.62%) egg count reduction in sheep treated with ethanolic extracts at 2 g kg- 1 body weight on day 10 after treatment, closely followed by ethanolic extracts at 1 g kg- 1 body weight on day 10 after treatment (43.54% egg count reduction). The aqueous extracts resulted in a maximum of 31.53% reduction in faecal egg counts on day 10 after treatment with 1 g kg- 1 body weight. Thus ethanolic extracts exhibited greater anthelmintic activity under both in vitro and in vivo conditions; this could be due to the presence of alcohol-soluble active ingredients in I. hookeriana. From the present study it can be suggested that I. hookeriana rhizome exhibited significant anthelmintic activity against gastrointestinal nematodes of sheep and has the potential to contribute to the control of gastrointestinal nematode parasites of small ruminants.     

Modulation of prefrontal cortex with anodal tDCS prevents post-exercise facilitation interference during dual task

In this study we aimed to investigate whether transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) reduces interference effects of a dual task (DT) on post-exercise facilitation (PEF) of the motor evoked potentials. Anodal tDCS reversed the DT interference on PEF after a non-fatiguing isometric contraction. We conclude that anodal DLPFC tDCS improves the ability to allocate attentional resources and modulates plastic adaptations across brain systems.