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29 result(s) for "Archidiacono, Nicoletta"
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Color Stabilization of Apulian Red Wines through the Sequential Inoculation of Starmerella bacillaris and Saccharomyces cerevisiae
Mixed fermentation using Starmerella bacillaris and Saccharomyces cerevisiae has gained attention in recent years due to their ability to modulate the qualitative parameters of enological interest, such as the color intensity and stability of wine. In this study, three of the most important red Apulian varieties were fermented through two pure inoculations of Saccharomyces cerevisiae strains or the sequential inoculation of Saccharomyces cerevisiae after 48 h from Starmerella bacillaris. The evolution of anthocyanin profiles and chromatic characteristics were determined in the produced wines at draining off and after 18 months of bottle aging in order to assess the impact of the different fermentation protocols on the potential color stabilization and shelf-life. The chemical composition analysis showed titratable acidity and ethanol content exhibiting marked differences among wines after fermentation and aging. The 48 h inoculation delay produced wines with higher values of color intensity and color stability. This was ascribed to the increased presence of compounds, such as stable A-type vitisins and reddish/violet ethylidene-bridge flavonol-anthocyanin adducts, in the mixed fermentation. Our results proved that the sequential fermentation of Starmerella bacillaris and Saccharomyces cerevisiae could enhance the chromatic profile as well as the stability of the red wines, thus improving their organoleptic quality.
Epigenetic origin of evolutionary novel centromeres
Most evolutionary new centromeres (ENC) are composed of large arrays of satellite DNA and surrounded by segmental duplications. However, the hypothesis is that ENCs are seeded in an anonymous sequence and only over time have acquired the complexity of “normal” centromeres. Up to now evidence to test this hypothesis was lacking. We recently discovered that the well-known polymorphism of orangutan chromosome 12 was due to the presence of an ENC. We sequenced the genome of an orangutan homozygous for the ENC, and we focused our analysis on the comparison of the ENC domain with respect to its wild type counterpart. No significant variations were found. This finding is the first clear evidence that ENC seedings are epigenetic in nature. The compaction of the ENC domain was found significantly higher than the corresponding WT region and, interestingly, the expression of the only gene embedded in the region was significantly repressed.
Eight million years of maintained heterozygosity in chromosome homologs of cercopithecine monkeys
In the Cercopithecini ancestor two chromosomes, homologous to human chromosomes 20 and 21, fused to form the Cercopithecini specific 20/21 association. In some individuals from the genus Cercopithecus, this association was shown to be polymorphic for the position of the centromere, suggesting centromere repositioning events. We set out to test this hypothesis by defining the evolutionary history of the 20/21 association in four Cercopithecini species from three different genera. The marker order of the various 20/21 associations was established using molecular cytogenetic techniques, including an array of more than 100 BACs. We discovered that five different forms of the 20/21 association were present in the four studied Cercopithecini species. Remarkably, in the two Cercopithecus species, we found individuals in which one homolog conserved the ancestral condition, but the other homolog was highly rearranged. The phylogenetic analysis showed that the heterozygosity in these two species originated about 8 million years ago and was maintained for this entire arc of time, surviving multiple speciation events. Our report is a remarkable extension of Dobzhansky’s pioneering observation in Drosophila concerning the maintenance of chromosomal heterozygosity due to selective advantage. Dobzhansky’s hypothesis recently received strong support in a series of detailed reports on the fruit fly genome. Our findings are first extension to primates, indeed to Old World monkeys phylogenetically close to humans of an analogous situation. Our results have important implications for hypotheses on how chromosome rearrangements, selection, and speciation are related.
The 14/15 association as a paradigmatic example of tracing karyotype evolution in New World monkeys
Fluorescence in situ hybridization (FISH), especially chromosome painting, has been extensively exploited in the phylogenetic reconstruction of primate evolution. Although chromosome painting is a key method to map translocations, it is not effective in detecting chromosome inversions, which may be up to four times more frequent than other chromosomal rearrangements. BAC-FISH instead can economically delineate marker order and reveal intrachromosomal rearrangements. However, up to now, BAC-FISH was rarely used to study the chromosomes of New World monkeys partly due to technical difficulties. In this paper, we used BAC-FISH to disentangle the complex evolutionary history of the ancestral 14/15 association in NWMs, beginning from the squirrel monkey ( Saimiri boliviensis ). To improve the hybridization efficiency of BAC-FISH in NWMs, we “translated” the human BACs into Callithrix jacchus (CJA) BACs, which yielded much higher hybridization efficiencies on other NWM species than human BACs. Our results disclosed 14 synteny blocks in squirrel monkeys, 7 more than with chromosome painting. We then applied a subset of CJA BACs on six other NWM species. The comparison of the hybridization pattern of these species contained phylogenetic information to discriminate evolutionary relationships. Notably Aotus was found to share an inversion with Callithrix , thus definitely assigning the genus Aotus to Cebidae. The present study can be seen as a paradigmatic approach to investigate the phylogenetics of NWMs by molecular cytogenetics.
Rapid emergence of independent “chromosomal lineages” in silvered-leaf monkey triggered by Y/autosome translocation
Sex/autosome translocations are rare events. The only known example in catarrhines is in the silvered-leaf monkey. Here the Y chromosome was reciprocally translocated with chromosome 1. The rearrangement produced an X 1 X 2 Y 1 Y 2 sex chromosome system. At least three chromosomal variants of the intact chromosome 1 are known to exist. We characterized in high resolution the translocation products (Y 1 and Y 2 ) and the polymorphic forms of the intact chromosome 1 with a panel of more than 150 human BAC clones. We showed that the translocation products were extremely rearranged, in contrast to the high level of marker order conservation of the other silvered-leaf monkey chromosomes. Surprisingly, each translocation product appeared to form independent “chromosome lineages”; each having a myriad of distinct rearrangements. We reconstructed the evolutionary history of the translocation products by comparing the homologous chromosomes of two other colobine species: the African mantled guereza and the Indian langur. The results showed a massive reuse of breakpoints: only 12, out of the 40 breaks occurred in domains never reused in other rearrangements, while, strikingly, some domains were used up to four times. Such frequent breakpoint reuse if proved to be a general phenomenon has profound implications for mechanisms of chromosome evolution.
Evolutionary Formation of New Centromeres in Macaque
A systematic fluorescence in situ hybridization comparison of macaque and human synteny organization disclosed five additional macaque evolutionary new centromeres (ENCs) for a total of nine ENCs. To understand the dynamics of ENC formation and progression, we compared the ENC of macaque chromosome 4 with the human orthologous region, at 6q24.3, that conserves the ancestral genomic organization. A 250-kilobase segment was extensively duplicated around the macaque centromere. These duplications were strictly intrachromosomal. Our results suggest that novel centromeres may trigger only local duplication activity and that the absence of genes in the seeding region may have been important in ENC maintenance and progression.
Organization and Evolution of Primate Centromeric DNA from Whole-Genome Shotgun Sequence Data
The major DNA constituent of primate centromeres is alpha satellite DNA. As much as 2%-5% of sequence generated as part of primate genome sequencing projects consists of this material, which is fragmented or not assembled as part of published genome sequences due to its highly repetitive nature. Here, we develop computational methods to rapidly recover and categorize alpha-satellite sequences from previously uncharacterized whole-genome shotgun sequence data. We present an algorithm to computationally predict potential higher-order array structure based on paired-end sequence data and then experimentally validate its organization and distribution by experimental analyses. Using whole-genome shotgun data from the human, chimpanzee, and macaque genomes, we examine the phylogenetic relationship of these sequences and provide further support for a model for their evolution and mutation over the last 25 million years. Our results confirm fundamental differences in the dispersal and evolution of centromeric satellites in the Old World monkey and ape lineages of evolution.
The common marmoset genome provides insight into primate biology and evolution
Kim Worley and colleagues report the whole-genome sequence of the common marmoset, Callithrix jacchus , the first New World monkey to be sequenced. We report the whole-genome sequence of the common marmoset ( Callithrix jacchus ). The 2.26-Gb genome of a female marmoset was assembled using Sanger read data (6×) and a whole-genome shotgun strategy. A first analysis has permitted comparison with the genomes of apes and Old World monkeys and the identification of specific features that might contribute to the unique biology of this diminutive primate, including genetic changes that may influence body size, frequent twinning and chimerism. We observed positive selection in growth hormone/insulin-like growth factor genes (growth pathways), respiratory complex I genes (metabolic pathways), and genes encoding immunobiological factors and proteases (reproductive and immunity pathways). In addition, both protein-coding and microRNA genes related to reproduction exhibited evidence of rapid sequence evolution. This genome sequence for a New World monkey enables increased power for comparative analyses among available primate genomes and facilitates biomedical research application.
A 76-kb Duplicon Maps Close to the BCR Gene on Chromosome 22 and the ABL Gene on Chromosome 9: Possible Involvement in the Genesis of the Philadelphia Chromosome Translocation
A patient with a typical form of chronic myeloid leukemia was found to carry a large deletion on the derivative chromosome 9q+ and an unusual BCR-ABL transcript characterized by the insertion, between BCR exon 14 and ABL exon 2, of 126 bp derived from a region located on chromosome 9, 1.4 Mb 5′ to ABL. This sequence was contained in the bacterial artificial chromosome RP11-65J3, which in fluorescence in situ hybridization experiments on normal metaphases was found to detect, in addition to the predicted clear signal at 9q34, a faint but distinct signal at 22q11.2, where the BCR gene is located, suggesting the presence of a large region of homology between the two chromosomal regions. Indeed, Blast analysis of the RP11-65J3 sequence against the entire human genome revealed the presence of a stretch of homology, about 76 kb long, located approximately 150 kb 3′ to the BCR gene, and containing the 126-bp insertion sequence. Evolutionary studies using fluorescence in situ hybridization identified the region as a duplicon, which transposed from the region orthologous to human 9q34 to chromosome 22 after the divergence of orangutan from the human-chimpanzee-gorilla common ancestor about 14 million years ago. Recent sequence analyses have disclosed an unpredicted extensive segmental duplication of our genome, and the impact of duplicons in triggering genomic disorders is becoming more and more apparent. The discovery of a large duplicon relatively close to the ABL and BCR genes and the finding that the 126-bp insertion is very close to the duplicon at 9q34 open the question of the possible involvement of the duplicon in the formation of the Philadelphia chromosome translocation.
Initial sequence of the chimpanzee genome and comparison with the human genome
Here we present a draft genome sequence of the common chimpanzee ( Pan troglodytes ). Through comparison with the human genome, we have generated a largely complete catalogue of the genetic differences that have accumulated since the human and chimpanzee species diverged from our common ancestor, constituting approximately thirty-five million single-nucleotide changes, five million insertion/deletion events, and various chromosomal rearrangements. We use this catalogue to explore the magnitude and regional variation of mutational forces shaping these two genomes, and the strength of positive and negative selection acting on their genes. In particular, we find that the patterns of evolution in human and chimpanzee protein-coding genes are highly correlated and dominated by the fixation of neutral and slightly deleterious alleles. We also use the chimpanzee genome as an outgroup to investigate human population genetics and identify signatures of selective sweeps in recent human evolution.