TASK DEFINITION: In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.
PROBLEM: The mammalian A-type cyclin family consists of two members, cyclin A1 (encoded by Ccna1) and cyclin A2 (encoded by Ccna2). Cyclin A2 promotes both G1/S and G2/M transitions, and targeted deletion of Ccna2 in mouse is embryonic lethal. Cyclin A1 is expressed in mice exclusively in the germ cell lineage and is expressed in humans at highest levels in the testis and certain myeloid leukaemia cells. To investigate the role of cyclin A1 and possible redundancy among the cyclins in vivo, we generated mice bearing a null mutation of Ccna1. Ccna1-/- males were sterile due to a block of spermatogenesis before the first meiotic division, whereas females were normal. Meiosis arrest in Ccna1/ males was associated with increased germ cell apoptosis, desynapsis abnormalities and reduction of Cdc2 kinase activation at the end of meiotic prophase. Cyclin A1 is therefore essential for spermatocyte passage into the first meiotic division in male mice, a function that cannot be complemented by the concurrently expressed B-type cyclins.

SOLUTION: Cyclin A1 is required for meiosis in the male mouse

PROBLEM: The TCR:CD3 complex transduces signals that are critical for optimal T cell development and adaptive immunity. In resting T cells, the CD3 cytoplasmic tail associates with the plasma membrane via a proximal basic-rich stretch (BRS). In this study, we show that mice lacking a functional CD3-BRS exhibited substantial reductions in thymic cellularity and limited CD4- CD8- double-negative (DN) 3 to DN4 thymocyte transition, because of enhanced DN4 TCR signaling resulting in increased cell death and TCR downregulation in all subsequent populations. Furthermore, positive, but not negative, T cell selection was affected in mice lacking a functional CD3-BRS, which led to limited peripheral T cell function and substantially reduced responsiveness to influenza infection. Collectively, these results indicate that membrane association of the CD3 signaling domain is required for optimal thymocyte development and peripheral T cell function.

SOLUTION: Membrane association of the CD3 signaling domain is required for optimal T cell development and function.

PROBLEM: BACKGROUND The aim of this study was to examine the clustering of four major lifestyle risk factors (smoking, heavy drinking, lack of fruit and vegetables consumption, and lack of physical activity), and to examine the variation across different socio-demographic groups in the English adult population.
METHODS The study population was derived from the 2003 Health Survey for England (n=11,492). Clustering was examined by comparing the observed and expected prevalence of the different possible combinations. A multinomial multilevel regression model was conducted to examine the socio-demographic variation in the clustering of the four risk factors.
RESULTS The study found that, when using British health recommendations, a majority of the English population have multiple lifestyle risk factors at the same time. Clustering was found at both ends of the lifestyle spectrum and was more pronounced for women than for men. Overall, multiple risk factors were more prevalent among men, lower social class households, singles, and people who are economically inactive, but less prevalent among home owners and older age groups.
CONCLUSIONS The clustering of multiple risk factors provides support for multiple-behavior interventions as opposed to single-behavior interventions.

SOLUTION:
The prevalence and clustering of four major lifestyle risk factors in an English adult population.