Índice de CMP em leite pasteurizado comercializado em Minas Gerais, Brasil, durante os anos de 2011 a 2017 / Caseinomacropeptide index in pasteurized milk retailed in Minas Gerais, Brazil from 2011 to 2017

Cheese whey is a nutritious byproduct in the dairy industry, however, due to low commercial value, its use as a milk adulterant is a common practice not easily detected by routine analysis. In Brazil, quantification of caseinomacropeptide (CMP) index, using High Performance Liquid Chromatography (HPLC), is officially used to investigate illegal cheese whey addition to milk. Milk with CMP index above 30mg/L is considered not suitable for human consumption. The objective of this research was to report the CMP index in 185 samples of pasteurized milk, representing 73 commercial brands produced in 51 counties and ten mesoregions of the state of Minas Gerais, from 2011 to 2013 (58 samples) and 2015 to 2017 (127 samples). CMP index was considered normal (up to 30mg/L) in 75.1% of the samples. However, 21.1% presented CMP index above 75mg/L and 3.8% from 31 to 75mg/L. CMP index above 75mg/L was found in 17.4% of the samples produced during the dry season (April to September) and in 24.7% during the rainy season (October to March). These data point to the need of more efficient monitoring and inspection processes to hinder adulteration with cheese whey addition to milk.(AU)

Identification and characterization of the Drosophila tau homolog.

A pathological hallmark of neurodegenerative tauopathies, including Alzheimer's disease and a group of clinically heterogeneous frontotemporal dementias, is the presence of intracellular neurofibrillary protein lesions (reviewed in Spillantini and Goedert, TINS 10 (1998) 428). The principal component of these structures is the microtubule-associated protein tau. Although tau is normally a highly soluble protein enriched in axons, in these deposits, it is abnormally hyperphosphorylated, insoluble, and redistributed to the somatodendritic compartments of neurons. Through ultrastructual analyses, it has been determined that the tau protein in these lesions is filamentous and organized into paired-helical filaments, straight filaments, or ribbon-like filaments (Goedert et al., The Molecular and Genetic Basis of Neurological Disease (1997) 613). By the dynamic binding of microtubules, tau is thought to promote the structural stability of axons, but whether tau aggregates contribute to neurodegeneration through a direct toxicity on normal cellular functions such as organelle transport or an indirect effect on microtubule stability, is currently unknown. The identification of mutations in the tau locus in patients with familial frontotemporal dementia and Parkinsonism linked to chromosome 17 has demonstrated that mutations in tau are sufficient to cause neurodegenerative disease (Poorkaj et al., Ann. Neurol. 43 (1998) 815; Hutton et al., Nature 393 (1998) 702). To elucidate the mechanisms by which tau dysfunction contributes to neuronal loss, we have sought to model human tauopathies in a genetically tractable organism. Here we describe the isolation of a Drosophila tau cDNA (GenBank accession number AY032977), the production of antibodies that recognize the encoded protein, and their use in determining the expression and subcellular localization of the fly tau protein.

Notch and presenilin: a proteolytic mechanism emerges.

Presenilins are needed for proteolytic processing of transmembrane proteins of the Notch/Lin-12 family and for cleavage of the amyloid precursor protein. Accumulating evidence now strongly implicates Presenilin as the catalytic core of a multiprotein complex that executes an unusual intramembranous cleavage of its substrates. In the case of amyloid precursor protein, this cleavage contributes to the generation of small, toxic amyloid peptides that trigger the pathological development of Alzheimer's disease. In the Notch/Lin-12 pathway, Presenilin-mediated cleavage of the receptor is a crucial feature of ligand-induced receptor activation and signal transduction. In this pathway, the Presenilins perform a regulated cleavage event that follows additional processing steps during receptor maturation and ligand-induced ectodomain removal.

Proteolysis and developmental signal transduction.

Regulated proteolysis is a critical feature of many intercellular signalling pathways that control cell-fate specification and tissue patterning during metazoan development. The roles of proteolysis in three different pathways, the Toll, Hedgehog, and Notch pathways, are described to illustrate the importance of specific protein cleavages in both extracellular ligand-receptor interactions and intracellular signal transduction. An emerging principle is the use of proteolysis to control the maturation and activation of receptors, to limit the spatial diffusion of their ligands, and to modulate the subcellular localization or transcriptional activity of DNA-binding factors in response to receptor-ligand interactions at the cell surface.

Comparative genomics of the eukaryotes.

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.

Modeling human neurodegenerative diseases in Drosophila: on a wing and a prayer.

The ability of Drosophila genetics to reveal new insights into human neurodegenerative disease is highlighted not only by mutants in flies that show neuronal cell loss, but also by targeted expression of human disease genes in the fly. Moreover, study of Drosophila homologs of various human disease genes provides new insight into fundamental aspects of protein function. These recent findings confirm the remarkable homology of gene function in flies when compared with humans. With the advent of complete genomic sequencing on the horizon, Drosophila will continue to be an outstanding model system in which to unravel the complexities, causes and treatments for human neural degeneration.

Surviving Drosophila eye development: integrating cell death with differentiation during formation of a neural structure.

Normal differentiation requires an appropriately orchestrated sequence of developmental events. Regulation of cell survival and cell death is integrated with these events to achieve proper cell number, cell type, and tissue structure. Here we review regulation of cell survival in the context of a precisely patterned neural structure: the Drosophila compound eye. Numerous mutations lead to altered differentiation and are frequently accompanied by altered patterns of cell death. We discuss various critical times of normal eye development, highlighting how inappropriate regulation of cell death contributes to different mutant phenotypes associated with genes that specify the entire eye primordia, others that pattern the retina, and those that eliminate extraneous cells to refine the precise pigment cell lattice. Finally, we address how the Drosophila eye may allow identification of additional mechanisms that contribute to the normal integration of cell survival with appropriate events of cellular differentiation.

Genetic characterization of cytological region 77A-D harboring the presenilin gene of Drosophila melanogaster.

We performed a systematic lethal mutagenesis of the genomic region uncovered by Df(3L)rdgC-co2 (cytological interval 77A-D) to isolate mutations in the single known Presenilin (Psn) gene of Drosophila melanogaster. Because this segment of chromosome III has not been systematically characterized before, inter se complementation testing of newly recovered mutants was carried out. A total of 79 lethal mutations were isolated, representing at least 17 lethal complementation groups, including one corresponding to the Psn gene. Fine structure mapping of the genomic region surrounding the Psn transcription unit by transgenic rescue experiments allowed us to localize two of the essential loci together with Psn within an approximately 12-kb genomic DNA region. One of these loci, located 3' to Psn, encodes a Drosophila protein related to the yeast 60S ribosomal protein L10 precursor. We also determined which of the newly recovered lethal mutant groups correspond to previously isolated lethal P-element insertions, lethal inversion breakpoints, and lethal polo gene mutants. Point mutations were identified in all five recovered Psn alleles, one of which results in a single amino acid substitution G-E at a conserved residue in the C-terminal cytoplasmic tail of the protein, suggesting an important functional role for this C-terminal domain of Presenilin. In addition, some viable mutations were recovered in the screen, including new alleles of the clipped and inturned loci.

Ca(2+)-ATPase function is required for intracellular trafficking of the Notch receptor in Drosophila.

Maintaining high Ca(2+) concentrations in the lumen of the endoplasmic reticulum is important for protein synthesis and transport. We identified a lethal complementation group recovered in a screen for mutations that reduce Notch activity as loss-of-function alleles of the Drosophila Ca(2+)-ATPase gene Ca-P60A. Analysis of Ca-P60A mutants indicates that Ca(2+)-ATPase is essential for cell viability and tissue morphogenesis during development. Cultured cells treated with Ca(2+)-ATPase inhibitors exhibit impaired Notch cleavage and receptor trafficking to the cell surface, explaining the genetic interaction between Ca(2+)-ATPase and Notch. Notch and several other transmembrane proteins are mislocalized in tissue clones homozygous for Ca-P60A mutations, demonstrating a general effect on membrane protein trafficking caused by a deficiency in Ca(2+)-ATPase.

Genetic analysis of the role of the drosophila fat facets gene in the ubiquitin pathway.

The Drosophila fat facets gene encodes a deubiquitinating enzyme required during eye development to limit the number of photoreceptors in each facet to eight. Ubiquitin is a small polypeptide that targets proteins for degradation by the proteasome. Deubiquitinating enzymes cleave ubiquitin-protein bonds. In order to investigate the role of FAT FACETS in the ubiquitin pathway, genetic interactions between fat facets and the Drosophila UbcD1 gene were assessed. In addition, three yeast deubiquitinating enzyme genes were tested for their ability to substitute for fat facets in the developing Drosophila eye and for their effects on eye morphology. The results of these experiments support the hypothesis that FAT FACETS activity antagonizes that of the proteolytic machinery. The implications of these results for the specificity of FAF and yeast UBPs are discussed as well.

Apoptotic activities of wild-type and Alzheimer's disease-related mutant presenilins in Drosophila melanogaster.

Mutant human presenilins cause early-onset familial Alzheimer's disease and render cells susceptible to apoptosis in cultured cell models. We show that loss of presenilin function in Drosophila melanogaster increases levels of apoptosis in developing tissues. Moreover, overexpression of presenilin causes apoptotic and neurogenic phenotypes resembling those of Presenilin loss-of-function mutants, suggesting that presenilin exerts a dominant negative effect when expressed at high levels. In Drosophila S2 cells, Psn overexpression leads to reduced Notch receptor synthesis affecting levels of the intact approximately 300-kD precursor and its approximately 120-kD processed COOH-terminal derivatives. Presenilin-induced apoptosis is cell autonomous and can be blocked by constitutive Notch activation, suggesting that the increased cell death is due to a developmental mechanism that eliminates improperly specified cell types. We describe a genetic model in which the apoptotic activities of wild-type and mutant presenilins can be assessed, and we find that Alzheimer's disease-linked mutant presenilins are less effective at inducing apoptosis than wild-type presenilin.

Neurogenic phenotypes and altered Notch processing in Drosophila Presenilin mutants.

Presenilin proteins have been implicated both in developmental signalling by the cell-surface protein Notch and in the pathogenesis of Alzheimer's disease. Loss of presenilin function leads to Notch/lin-12-like mutant phenotypes in Caenorhabditis elegans and to reduced Notch1 expression in the mouse paraxial mesoderm. In humans, presenilins that are associated with Alzheimer's disease stimulate overproduction of the neurotoxic 42-amino-acid beta-amyloid derivative (Abeta42) of the amyloid-precursor protein APP. Here we describe loss-of-function mutations in the Drosophila Presenilin gene that cause lethal Notch-like phenotypes such as maternal neurogenic effects during embryogenesis, loss of lateral inhibition within proneural cell clusters, and absence of wing margin formation. We show that presenilin is required for the normal proteolytic production of carboxy-terminal Notch fragments that are needed for receptor maturation and signalling, and that genetically it acts upstream of both the membrane-bound form and the activated nuclear form of Notch. Our findings provide evidence for the existence of distinct processing sites or modifications in the extracellular domain of Notch. They also link the role of presenilin in Notch signalling to its effect on amyloid production in Alzheimer's disease.

Characterization of Drosophila Presenilin and its colocalization with Notch during development.

Mutant Presenilin proteins cause early-onset familial Alzheimer's disease in humans and Caenorhabditis elegans Presenilins may facilitate Notch receptor signaling. We have isolated a Drosophila Presenilin homologue and determined the spatial and temporal distribution of the encoded protein as well as its localization relative to the fly Notch protein. In contrast to previous mRNA in situ studies, we find that Presenilin is widely expressed throughout oogenesis, embryogenesis, and imaginal development, and generally accumulates at comparable levels in neuronal and nonneuronal tissues. Double immunolabeling with Notch antibodies revealed that Presenilin and Notch are coexpressed in many tissues throughout Drosophila development and display partially overlapping subcellular localizations, supporting a possible functional link between Presenilin and Notch.

Analysis of dominant enhancers and suppressors of activated Notch in Drosophila.

The Notch receptor controls cell fate decisions throughout Drosophila development. Truncated, ligand-independent forms of this protein delay or block differentiation. We have previously shown that expression of the intracellular domain of the receptor under the control of the sevenless enhancer/promoter induces a rough eye phenotype in the adult fly. Analysis of the resultant cellular transformations suggested that this form of Notch acts as a constitutively activated receptor. To identify gene products that interact with Notch, a second-site mutagenesis screen was performed to isolate enhancers and suppressors of the eye phenotype caused by expression of these activated Notch molecules. We screened 137,000 mutagenized flies and recovered 290 dominant modifiers. Many new alleles of previously identified genes were isolated, as were mutations defining novel loci that may function in the Notch signaling pathway. We discuss the data with respect to known features of Notch receptor signaling and Drosophila eye development.

Notch signaling.

The Notch/Lin-12/Glp-1 receptor family mediates the specification of numerous cell fates during development in Drosophila and Caenorhabditis elegans. Studies on the expression, mutant phenotypes, and developmental consequences of unregulated receptor activation have implicated these proteins in a general mechanism of local cell signaling, which includes interactions between equivalent cells and between different cell types. Genetic approaches in flies and worms have identified putative components of the signaling cascade, including a conserved family of extracellular ligands and two cellular factors that may associate with the Notch Intracellular domain. One factor, the Drosophila Suppressor of Hairless protein, is a DNA-binding protein, which suggests that Notch signaling may involve relatively direct signal transmission from the cell surface to the nucleus. Several vertebrate Notch receptors have also been discovered recently and play important roles in normal development and tumorigenesis.

The suppressor of hairless protein participates in notch receptor signaling.

In a genetic screen for mutations that attenuate Notch signaling in the developing Drosophila eye, we isolated rare, gain-of-function alleles of Suppressor of Hairless (Su(H)), the fly homolog of the mammalian C promoter-binding factor 1 (CBF1) gene. Su(H) exhibits numerous allele-specific genetic interactions with Notch as well as with Delta, deltex, and mastermind. In cultured Drosophila cells, the Su(H) protein is sequestered in the cytoplasm when coexpressed with Notch protein and is translocated to the nucleus when Notch binds to its ligand Delta. Cytoplasmic retention of Su(H) requires the intracellular cdc10/ankyrin repeats of Notch, which associate with Su(H) protein in the yeast interaction trap assay. These results indicate that Notch activity may regulate nuclear events by controlling the activity of a DNA-binding protein.