Yeast Expression Systems: Overview and Recent Advances.

Yeasts are outstanding hosts for the production of functional recombinant proteins with industrial or medical applications. Great attention has been emerged on yeast due to the inherent advantages and new developments in this host cell. For the production of each specific product, the most appropriate expression system should be identified and optimized both on the genetic and fermentation levels, considering the features of the host, vector and expression strategies. Currently, several new systems are commercially available; some of them are private and need licensing. The potential for secretory expression of heterologous proteins in yeast proposed this system as a candidate for the production of complex eukaryotic proteins. The common yeast expression hosts used for recombinant proteins' expression include Saccharomyces cerevisiae, Pichia pastoris, Hansenula polymorpha, Yarrowia lipolytica, Arxula adeninivorans, Kluyveromyces lactis, and Schizosaccharomyces pombe. This review is dedicated to discuss on significant characteristics of the most common methylotrophic and non-methylotrophic yeast expression systems with an emphasis on their advantages and new developments.

Sclerosing Mucoepidermoid Carcinoma of the Parotid Gland.

INTRODUCTION: Mucoepidermoid carcinoma represents one of the most common malignant salivary gland tumors. However, the sclerosing morphologic variant is extremely rare with only 23 reported cases in the English-language literature since it was discovered in 1987. CASE REPORT: Herein, we describe another case that was diagnosed in a 25-year-old woman presenting with a posterior auricular mass, as well as a review of the literature, which demonstrates that this is an extremely rare malignancy with no strict protocol for treatment. CONCLUSION: Pathologists must be aware of recognizing low grade sclerosing mucoepidermoid carcinoma which has metastatic potential and is frequently misdiagnosed as a benign lesion.