Identification of a novel homozygous nonsense mutation in EYS in a Chinese family with autosomal recessive retinitis pigmentosa

<p>Abstract</p> <p>Background</p> <p>Retinitis pigmentosa is the most important hereditary retinal degenerative disease, which has a high degree of clinical and genetic heterogeneity. More than half of all cases of retinitis pigmentosa are autosomal recessive (arRP), but the gene(s) causing arRP in most families has yet to be identified. The purpose of this study is to identify the genetic basis of severe arRP in a consanguineous Chinese family.</p> <p>Methods</p> <p>Linkage and haplotype analyses were used to define the chromosomal location of the pathogenic gene in the Chinese arRP family. Direct DNA sequence analysis of the entire coding region and exon-intron boundaries of <it>EYS </it>was used to determine the disease-causing mutation, and to demonstrate that the mutation co-segregates with the disease in the family.</p> <p>Results</p> <p>A single nucleotide substitution of G to T at nucleotide 5506 of EYS was identified in the Chinese arRP family. This change caused a substitution of a glutamic acid residue at codon 1,836 by a stop codon TAA (p.E1836X), and resulted in a premature truncated EYS protein with 1,835 amino acids. Three affected siblings in the family were homozygous for the p.E1836X mutation, while the other unaffected family members carried one mutant allele and one normal EYS allele. The nonsense mutation p.E1836X was not detected in 200 unrelated normal controls.</p> <p>Conclusions</p> <p>The <it>EYS </it>gene is a recently identified disease-causing gene for retinitis pigmentosa, and encodes the orthologue of <it>Drosophila </it>spacemaker. To date, there are only eight mutations in <it>EYS </it>that have been identified to cause arRP. Here we report one novel homozygous nonsense mutation of <it>EYS </it>in a consanguineous Chinese arRP family. Our study represents the first independent confirmation that mutations in <it>EYS </it>cause arRP. Additionally, this is the first <it>EYS </it>mutation identified in the Chinese population.</p

The Expression of a Xylanase Targeted to ER-Protein Bodies Provides a Simple Strategy to Produce Active Insoluble Enzyme Polymers in Tobacco Plants

Background Xylanases deserve particular attention due to their potential application in the feed, pulp bleaching and paper industries. We have developed here an efficient system for the production of an active xylanase in tobacco plants fused to a proline-rich domain (Zera) of the maize storage protein γ-zein. Zera is a self-assembling domain able to form protein aggregates in vivo packed in newly formed endoplasmic reticulum-derived organelles known as protein bodies (PBs). Methodology/Principal Findings Tobacco leaves were transiently transformed with a binary vector containing the Zera-xylanase coding region, which was optimized for plant expression, under the control of the 35S CaMV promoter. The fusion protein was efficiently expressed and stored in dense PBs, resulting in yields of up to 9% of total protein. Zera-xylanase was post-translationally modified with high-mannose-type glycans. Xylanase fused to Zera was biologically active not only when solubilized from PBs but also in its insoluble form. The resistance of insoluble Zera-xylanase to trypsin digestion demonstrated that the correct folding of xylanase in PBs was not impaired by Zera oligomerization. The activity of insoluble Zera-xylanase was enhanced when substrate accessibility was facilitated by physical treatments such as ultrasound. Moreover, we found that the thermostability of the enzyme was improved when Zera was fused to the C-terminus of xylanase. Conclusion/Significance In the present work we have successfully produced an active insoluble aggregate of xylanase fused to Zera in plants. Zera-xylanase chimeric protein accumulates within ER-derived protein bodies as active aggregates that can easily be recovered by a simple density-based downstream process. The production of insoluble active Zera-xylanase protein in tobacco outlines the potential of Zera as a fusion partner for producing enzymes of biotechnological relevance. Zera-PBs could thus become efficient and low-cost bioreactors for industrial purposes.This work was mainly supported by ERA Biotech (www.erabiotech.com). Additional support was supplied by grant SGR 2009/703 funded by the Generalitat de Catalunya (www10.gencat.net) and grants CDS2007/00036 of Consolider Ingenio program and TRA 2009/0124 of TRACE program funded by Ministerio de Ciencia e Inovación (MICINN, www.micinn.es). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

The Hazard Exposure of the Maltese Islands

International comparisons of disaster risk frequently classify Malta as being one of the least hazard exposed countries. Such rankings may be criticised because: (1) they fail to take into account historic increases in population and its seasonal variation; (2) they are based on inadequately researched and incomplete historical catalogues of damaging events and (3), for small island states like Malta, they do not take into account the implications of restricted land area, which can be disproportionately impacted by even small hazardous events. In this paper, we draw upon a variety of data to discuss disaster risk in the Maltese Islands. In particular, the notion that Malta is one of the ‘safest places on earth’ is not only misleading, but also potentially dangerous because it engenders a false sense of security amongst the population. We argue that Malta is exposed to a variety of extreme events, that include: the distal effects of major earthquakes originating in southern Italy and Greece, plus their associated tsunamis; major ash producing eruptions of Mount Etna (Sicily), and their putative impacts on air transport; storm waves; coastal/inland landslides; karstic collapse; flooding and drought. In criticising international rankings of the islands’ exposure, we highlight the issues involved in formulating hazard assessments, in particular incomplete catalogues of extreme natural events. With Malta witnessing swelling resident, seasonal (i.e. tourist) plus foreign-born populations, and increases in the urban area, further research into hazards is required in order to develop evidence-based policies of disaster risk reduction (DRR)

Approach to cataract surgery in glaucoma patients

As both glaucoma and cataract are increasingly frequent with increasing age, glaucoma patients undergoing cataract surgery are common. These patients require a carefully planned approach to achieve not only a successful cataract extraction outcome but, more importantly, long-term control of their glaucoma