ETS2 repressor factor (ERF) is involved in T lymphocyte maturation acting as regulator of thymocyte lineage commitment.

Thymocyte differentiation and lineage commitment is regulated by an extensive network of transcription factors and signaling molecules among which Erk plays a central role. However, Erk effectors as well as the molecular mechanisms underlying this network are not well understood. Erf is a ubiquitously expressed transcriptional repressor regulated by Erk-dependent phosphorylation. Here, we investigated the role of Erf in T cell maturation and lineage commitment, using a double-fluorescent Erf-floxed mouse to produce thymus-specific Erf knockouts. We observed significant accumulation of thymocytes in the CD4/CD8 DP stage, followed by a significant reduction in CD4SP cells, a trend for lower CD8SP cell frequency, and an elevated percentage of γδ expressing thymocytes in Erf-deficient mice. Also, an elevated number of CD69+ TCRß+ cells indicates that thymocytes undergoing positive selection accumulate at this stage. The expression of transcription factors Gata3, ThPOK, and Socs1 that promote CD4+ cell commitment was significantly decreased in Erf-deficient mice. These findings suggest that Erf is involved in T cell maturation, acting as a positive regulator during CD4 and eventually CD8 lineage commitment, while negatively regulates the production of γδ T cells. In addition, Erf-deficient mice displayed decreased percentages of CD4+ and CD8+ splenocytes and elevated levels of IL-4 indicating that Erf may have an additional role in the homeostasis, differentiation, and immunologic response of helper and cytotoxic T cells in the periphery. Overall, our results show, for the first time, Erf's involvement in T cell biology suggesting that Erf acts as a potential regulator during thymocyte maturation and thymocyte lineage commitment, in γδ T cell generation, as well as in Th cell differentiation.

Field validation of predictive models for the growth of lactic acid bacteria in acidic cheese-based Greek appetizers.

A microbial model was developed for spoilage of two acidic Greek appetizers, namely, tyrosalata (TS) and tyrokafteri (TK), with pH values of 4.34 to 4.50 and 4.22 to 4.38, respectively. The specific spoilage organisms of these products were lactic acid bacteria (LAB), which dominated during storage, while yeasts, whenever present, remained at low levels (1 to 2 log CFU/g). Correlations of LAB populations with changes in pH and sensory characteristics indicated that the spoilage level of LAB ranged from 8.1 to 8.6 log CFU/g for both products. TK showed a relatively higher microbial stability than did TS. The growth of LAB was modeled with the Baranyi model, while their maximum specific growth rates were further modeled as a function of temperature with square-root model and Arrhenius equations for each appetizer. The validation of the model was performed under nonisothermal conditions in the laboratory and in a field validation trial with temperature logging during distribution of individual packages in the chill supply chain, including transportation from the plant to the distribution center, retail display, and household refrigerators. Models for both appetizers showed satisfactory agreement with data, with a slight tendency of overprediction of LAB in TS. The field validation process also confirmed the higher stability of TK over TS. The developed models may serve as a useful tool for monitoring the microbiological quality of such complex products and manage their distribution. Furthermore, depending on the seasonal variation of chill chain conditions, reassessment of shelf life may be performed.