An alternative bioassay using Anabas testudineus (Climbing perch) cholinesterase for metal ions detection

Climbing Perch or its scientific name, Anabas testudineus is one of the freshwater fish belonging to the family of Anabantidae. It is widely distributed in ponds, swamps and estuaries in Asia. In this study, cholinesterase (ChE) was partially purified from the liver of A. testudineus through ion exchange chromatography. This purification method provided a recovery yield of 5.36% with a purification fold of 6.6. The optimum conditions for ChE assay were identified to be 2.5 mM of butyrylthiocholine iodide (BTC) with pH 8.0 in Tris-HCl buffer at 40°C. Substrate specificity profile also indicated that ChE favours BTC as substrate because it records the highest catalytic efficiency (V/K). Protein analysis through Native-PAGE showed that ion exchange chromatography is an effective method to partially purify ChE. Metal ion inhibition tests were conducted and mercury (Hg) was found to show the highest inhibition effect (87.30%) whereas lead (Pb) shows the lowest inhibition effect (28.01%). All these findings showed that partially purified ChE from the liver of A. testudineus is suitable to be used as a bioindicator to detect the presence of metal ions

A unique DNA binding domain converts T-cell factors into strong Wnt effectors.

Wnt regulation of gene expression requires binding of LEF/T-cell factor (LEF/TCF) transcription factors to Wnt response elements (WREs) and recruitment of the activator beta-catenin. There are significant differences in the abilities of LEF/TCF family members to regulate Wnt target genes. For example, alternatively spliced isoforms of TCF-1 and TCF-4 with a C-terminal "E" tail are uniquely potent in their activation of LEF1 and CDX1. Here we report that the mechanism responsible for this unique activity is an auxiliary 30-amino-acid DNA interaction motif referred to here as the "cysteine clamp" (or C-clamp). The C-clamp contains invariant cysteine, aromatic, and basic residues, and surface plasmon resonance (SPR) studies with recombinant C-clamp protein showed that it binds double-stranded DNA but not single-stranded DNA or RNA (equilibrium dissociation constant = 16 nM). CASTing (Cyclic Amplification and Selection of Targets) experiments were used to test whether this motif influences WRE recognition. Full-length LEF-1, TCF-1E, and TCF-1E with a mutated C-clamp all bind nearly identical WREs (TYYCTTTGATSTT), showing that the C-clamp does not alter WRE specificity. However, a GC element downstream of the WRE (RCCG) is enriched in wild-type TCF-1E binding sites but not in mutant TCF-1E binding sites. We conclude that the C-clamp is a sequence-specific DNA binding motif. C-clamp mutations destroy the ability of beta-catenin to regulate the LEF1 promoter, and they severely impair the ability of TCF-1 to regulate growth in colon cancer cells. Thus, E-tail isoforms of TCFs utilize two DNA binding activities to access a subset of Wnt targets important for cell growth

A unique DNA binding domain converts T-cell factors into strong Wnt effectors.

Wnt regulation of gene expression requires binding of LEF/T-cell factor (LEF/TCF) transcription factors to Wnt response elements (WREs) and recruitment of the activator beta-catenin. There are significant differences in the abilities of LEF/TCF family members to regulate Wnt target genes. For example, alternatively spliced isoforms of TCF-1 and TCF-4 with a C-terminal "E" tail are uniquely potent in their activation of LEF1 and CDX1. Here we report that the mechanism responsible for this unique activity is an auxiliary 30-amino-acid DNA interaction motif referred to here as the "cysteine clamp" (or C-clamp). The C-clamp contains invariant cysteine, aromatic, and basic residues, and surface plasmon resonance (SPR) studies with recombinant C-clamp protein showed that it binds double-stranded DNA but not single-stranded DNA or RNA (equilibrium dissociation constant = 16 nM). CASTing (Cyclic Amplification and Selection of Targets) experiments were used to test whether this motif influences WRE recognition. Full-length LEF-1, TCF-1E, and TCF-1E with a mutated C-clamp all bind nearly identical WREs (TYYCTTTGATSTT), showing that the C-clamp does not alter WRE specificity. However, a GC element downstream of the WRE (RCCG) is enriched in wild-type TCF-1E binding sites but not in mutant TCF-1E binding sites. We conclude that the C-clamp is a sequence-specific DNA binding motif. C-clamp mutations destroy the ability of beta-catenin to regulate the LEF1 promoter, and they severely impair the ability of TCF-1 to regulate growth in colon cancer cells. Thus, E-tail isoforms of TCFs utilize two DNA binding activities to access a subset of Wnt targets important for cell growth

The Role of Assessment Feedback in Developing Academic Buoyancy

This research focuses on the everyday challenge in academic learning of assessment, and argues that academic buoyancy is a key factor in academic success. To scaffold students’ learning and effectively support academic buoyancy, there is arguably a need for a better understanding of: (i) what students find most and least useful in their assessment feedback; (ii) how students use feedback to approach future assessments; and (iii) how students respond to feedback in terms of what they think, feel and do. Key findings from survey responses of 91 undergraduate students were that students use their feedback more than anticipated and look for specific information to help their future performance. In addition, five indicators of academically buoyant behaviour were identified: an internal locus of control, understanding the grade, being forward looking, being improvement focused and being action orientated. These indicators suggested a distinction between students who were academically buoyant because they were constructive in their response to feedback, and those who appeared less so because they were not action orientated, but more focused on their emotional response. These findings have implications for the provision of assessment feedback in higher education and offer insight into opportunities for the development of academic buoyancy

The high-affinity HSP90-CHIP complex recognizes and selectively degrades phosphorylated tau client proteins

A primary pathologic component of Alzheimer’s disease (AD) is the formation of neurofibrillary tangles composed of hyperphosphorylated tau (p-tau). Expediting the removal of these p-tau species may be a relevant therapeutic strategy. Here we report that inhibition of Hsp90 led to decreases in p-tau levels independent of heat shock factor 1 (HSF1) activation. A critical mediator of this mechanism was carboxy terminus of Hsp70–interacting protein (CHIP), a tau ubiquitin ligase. Cochaperones were also involved in Hsp90-mediated removal of p-tau, while those of the mature Hsp90 refolding complex prevented this effect. This is the first demonstration to our knowledge that blockade of the refolding pathway promotes p-tau turnover through degradation. We also show that peripheral administration of a novel Hsp90 inhibitor promoted selective decreases in p-tau species in a mouse model of tauopathy, further suggesting a central role for the Hsp90 complex in the pathogenesis of tauopathies. When taken in the context of known high-affinity Hsp90 complexes in affected regions of the AD brain, these data implicate a central role for Hsp90 in the development of AD and other tauopathies and may provide a rationale for the development of novel Hsp90-based therapeutic strategies