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Eggs are sources of protein, fats and micronutrients that play an important role in basic nutrition. However, eggs are traditionally associated with adverse factors in human health, mainly due to their cholesterol content. Nowadays, however, it is known that the response of cholesterol in human serum levels to dietary cholesterol consumption depends on several factors, such as ethnicity, genetic makeup, hormonal factors and the nutritional status of the consumer. Additionally, in recent decades, there has been an increasing demand for functional foods, which is expected to continue to increase in the future, owing to their capacity to decrease the risks of some diseases and socio-demographic factors such as the increase in life expectancy. This work offers a brief overview of the advantages and disadvantages of egg consumption and the potential market of functional eggs, and it explores the possibilities of the development of functional eggs by technological methods.

Germ-line mutations in the tumor suppressor gene Brca1 confer increased susceptibility to breast and ovarian cancers. BRCA1 is a 1863-amino acid protein with roles in transcriptional regulation and the cellular responses to DNA damage. Given its function in these nuclear processes, the subcellular localization of BRCA1 is an important issue and has been the object of recent controversy. BRCA1 contains two nuclear localization signals and is most frequently detected in the cell nucleus by immunofluorescence microscopy. In this study, we show that BRCA1 is a nuclear-cytoplasmic shuttling protein, capable of both entering and exiting the nucleus. We identified a functional Rev-type nuclear export sequence ( 81 QLVEELLKIICAFQLDTGL) near the amino terminus of BRCA1 that facilitates export via the CRM1/exportin pathway. Mutational inactivation of this nuclear export sequence, or treatment of cells with the CRM1-specific export inhibitor leptomycin B, induced nuclear accumulation of ectopic full-length BRCA1. Moreover, overexpression of the CRM1 export receptor resulted in decreased nuclear localization of endogenous BRCA1. The unexpected ability of BRCA1 to shuttle between nucleus and cytoplasm may have implications for the regulation and function of this tumor suppressor.Approximately 50% of inherited breast cancers and up to 90% of the familial cases of breast and ovarian cancer are linked to germ-line mutations of the tumor suppressor gene Brca1, the first susceptibility gene linked to these malignancies (1, 2). Although the biological basis for its tumor suppressive function is not yet clearly understood, mounting evidence suggests that Brca1 is a type of "caretaker" gene, whose inactivation renders cells prone to the accumulation of genetic abnormalities (reviewed in Ref.3). The increased mutation rate because of loss of BRCA1 may in turn induce alterations in other cancer-related genes and thereby lead to tumor formation.The human Brca1 gene encodes a 1863-amino acid protein involved in a variety of cellular processes. These include transcriptional activation (4, 5) and, supporting its proposed role as a caretaker, the cellular response to DNA damage (6). BRCA1 contains a carboxyl-terminal tandem of BRCT BRCA1 carboxyl-terminus repeats (7), a motif shared by several proteins involved in DNA repair and cell cycle checkpoint regulation (8). Apart from the BRCT motifs, BRCA1 homology to other known proteins is limited to an amino-terminal RING finger domain (9), which mediates protein-protein interactions, and two nuclear localization signals (NLSs), 1 which facilitate nuclear import of BRCA1 (10 -12).Full-length BRCA1 is predominantly located within the nucleus (13-15), but there are BRCA1 splice variants, such as the commonly expressed isoforms BRCA1⌬11b (11) or BRCA1⌬672-4095 (12), that lack the NLSs and are localized to the cytoplasm. Given the role of BRCA1 in critical nuclear processes, its localization within the cell is an important issue. In this regard, a series of conflicting reports on BRCA1 mislocaliza...