Nucleotide sequence at the 5' end of ovalbumin messenger RNA from chicken.

DNA-sequence analysis of 300 nucleotides from the region of cloned, double-stranded ovalbumin cDNA corresponding to the 5' end of ovalbumin messenger RNA was accomplished using the technique of Maxam and Gilbert (Proc. Nat. Acad. Sci. USA (1977) 74,560-564). The AUG initiation codon was located 52 nucleotides from the AT linkers used in cloning and immediately adjacent to the amino terminal peptide of ovalbumin, indicating the absence of a "signal peptide" in this protein. The nucleotide sequence coding for a phosphorylated peptide from ovalbumin was also found. These results demonstrate that the coding portion of mRNAov begins near the 5' end of the molecule leaving some 600 nucleotides of noncoding information at the 3' end

Determination of secondary structure in the initiation region of ovalbumin mRNA.

We have analyzed the secondary structure in the region surrounding the initiation codons of both cellular and synthetic versions of ovalbumin mRNA. RNase V1 cleavage sites and structure-dependent, chemically modified bases in cellular ovalbumin mRNA were determined by reverse transcription of hen poly A(+) RNA using ovalbumin-specific, synthetic DNA primers. These results indicate an extensive region of unpaired nucleotides preceding the initiation codon and a region of base-paired nucleotides including and following the initiation codon. A synthetic ovalbumin mRNA (SP65.OV) was prepared by run-off transcription of a cloned ovalbumin cDNA (pSP65.OV). Identical regions of hen ovalbumin and SP65.OV mRNAs gave identical patterns of structure-dependent base modifications. A computer program for determining RNA secondary structure was used to find a 5'-region structure for ovalbumin mRNA that is consistent with our data

“No-touch” DMEK surgical technique

Descemet membrane endothelial keratoplasty (DMEK) has become an increasingly popular first line treatment for patients with corneal endothelial disorders and corneal decompensation. The standard surgical technique, and alternative unfolding techniques and their rationales will be discussed

Endothelial keratoplasty: is Descemet membrane endothelial keratoplasty the Holy Grail of lamellar surgery? No

Posterior lamellar surgery has transformed the management of corneal endothelial disease due to faster visual rehabilitation, minimal refractive change, and maintenance of the ocular structural integrity compared full thickness keratoplasty. Although Descemet’s membrane endothelial keratoplasty (DMEK) appears to offer an anatomical repair for endothelial pathology, replacing only endothelium and Descemet’s membrane without any posterior stroma,1 it has yet to supersede Descemet’s stripping endothelial keratoplasty (DSEK) and its variations; ultrathin Descemet’s stripping automated endothelial keratoplasty (UT-DSAEK),2,3 thin manual Descemet stripping keratoplasty (TMDSEK),4 and pre-Descemet’s endothelial keratoplasty (PDEK)5 as the mainstay the treatment of Fuchs endothelial dystrophy or bullous keratopathy. The main reason for this is that DMEK is technically more challenging, requiring prolonged surgical time, associated with a steeper learning curve and possibly more potential complications.6,7<br/