Biomedical subjects

Maria De Luca

Publications and source records attributed to Maria De Luca.

11 recordsLinked to original sources

PubMed2006

A functional interplay between Aurora-A, Plk1 and TPX2 at spindle poles: Plk1 controls centrosomal localization of Aurora-A and TPX2 spindle association.

Aurora-A and Plk1 are centrosomal kinases involved in centrosome maturation and spindle assembly. The microtubule-binding protein TPX2 interacts with, and activates, Aurora-A. Here we have used RNA interference-mediated inactivation to investigate whether Aurora-A, Plk1 and TPX2 act independently or are part of one signaling cascade in spindle formation in mammalian cells. We have identified both specific, and over- lapping, roles of each single regulator in centrosome maturation and spindle formation: (1) Aurora-A and TPX2 are required for centriole cohesion and spindle bipolarity; (2) TPX2, besides its known role in microtubule organization, is also involved in centrosome maturation; (3) finally, Plk1 controls the localization of Aurora-A to centrosomes, as well as TPX2 recruitment to microtubules. Based on these results therefore a hierarchical functional relation between Plk1 and the Aurora-A/TPX2 pathway emerges.

Aurora Kinases↗

PubMed2006

Naming speed and visual search deficits in readers with disabilities: evidence from an orthographically regular language (Italian).

The study examined rapid automatized naming (RAN) in 42 children with reading disabilities and 101 control children-all native speakers of Italian, a language with shallow orthography. Third-, 5th- and 6th-grade children were given a RAN test that required rapid naming of color, object, or digit matrices. A visual search test using the same stimulus material (but not requiring a verbal response) and an oral articulation test were also given. Readers with disabilities performed worse than controls on the RAN test. This effect was larger in higher grades than in lower ones. Readers with disabilities were also slower than controls in performing the visual search test. The pattern of results for the RAN test held constant when the visual search performance was partialed out by covariance analysis, indicating the independence of the 2 deficits. The 2 groups did not differ for articulation rate. Finally, analysis of the pattern of intercorrelations indicated that reading speed was most clearly related to RAN, particularly in the group with reading disabilities. The results extend observations of RAN effects on reading deficits to Italian, an orthographically shallow language.

Attention↗

PubMed2006

Polymorphism in the transcription factor 7-like 2 (TCF7L2) gene is associated with reduced insulin secretion in nondiabetic women.

Recently, the transcription factor 7-like 2 (TCF7L2) gene on chromosome 10q25.2 has been linked with type 2 diabetes among Caucasians, with disease associations noted for single nucleotide polymorphisms (SNPs) rs12255372 and rs7903146. To investigate mechanisms by which TCF7L2 could contribute to type 2 diabetes, we examined the effects of these SNPs on clinical and metabolic traits affecting glucose homeostasis in 256 nondiabetic female subjects (138 European Americans and 118 African Americans) aged 7-57 years. Outcomes included BMI, percent body fat, insulin sensitivity (S(i)), acute insulin response to glucose (AIR(g)), and the disposition index (DI). Homozygosity for the minor allele (TT) of SNP rs12255372 occurred in 9% of individuals and was associated with a 31% reduction in DI values in a recessive model. The at-risk allele TT was also associated with lower AIR(g) adjusted for S(i) in both ethnic groups, whereas rs12255372 genotype was not associated with measures of adiposity or with S(i). The T allele of rs12255372 was also associated with increased prevalence of impaired fasting glucose. Genotypes at rs7903146 were not associated with any metabolic trait. Lower S(i) and higher AIR(g) observed in the African-American compared with the European-American subgroup could not be explained by the TCF7L2 genotype. Our data suggest that the TCF7L2 gene is an important factor regulating insulin secretion, which could explain its association with type 2 diabetes.

Adult↗

PubMed2005

Mapping quantitative trait loci affecting variation in Drosophila triacylglycerol storage.

OBJECTIVE: Recent genetic studies indicate that Drosophila melanogaster could be a powerful model to identify genes involved in mammalian adipocyte differentiation and fat storage. The objective of our study was to identify quantitative trait loci (QTLs) that contribute to variation in triacylglycerol (TAG) storage in two D. melanogaster laboratory strains. RESEARCH METHODS AND PROCEDURES: We used two genetic mapping procedures to identify loci with main and epistatic effects on TAG storage. First, using 68 recombinant inbred lines derived from the unrelated Oregon R and Russian 2b strains, we mapped the location of QTLs affecting TAG storage using both composite interval mapping and Bayesian epistatic methods. Second, we used the quantitative deficiency mapping procedure to identify candidate genes affecting this trait within one of the QTLs identified on the second chromosome. For both mapping experiments, flies were cultured in standard conditions. TAG content of 4- to 5-day-old flies, adjusted for live body mass and total proteins, was used as the phenotypic measure. RESULTS: Multiple QTLs associated with variation in TAG storage were identified by the genome-wide recombination mapping method, and some of them were sex-specific. The QTLs had main effects, but a male-specific epistatic interaction between two QTLs was also found. Finally, two closely linked QTLs were detected by deficiency mapping at 57E1-57E3 and 57E4-57F1 on chromosome 2, the first of which causes female-specific variation in TAG between the Oregon R and 2b strains. DISCUSSION: Our results suggest that variation in TAG storage in D. melanogaster is controlled by different genetic mechanisms and different sets of QTLs in male and female flies.

Adipogenesis↗

PubMed2005

Rapid naming, not cancellation speed or articulation rate, predicts reading in an orthographically regular language (Italian).

This study examined the influence of rapid automatization naming (RAN) measures on various parameters of reading performance in children who were native speakers of a language with a shallow orthography (Italian). Participants included 281 children enrolled in first-to-sixth grade. They were given a Naming test, in which they had to name rapidly matrices of colors, objects, or digits, a Cancellation test, using the same stimulus materials, and an oral Articulation test. Performance on all tests improved steadily across ages tested. Performance on the Naming test, but not on the Cancellation and Articulation tests, predicted speed and accuracy in reading; none of these measures reliably predicted the reading comprehension measure. Data on a Blending test were also available for a subsample of first- and third-graders. Both RAN and phonological ability contributed independently to the prediction of reading ability (accuracy and speed) in these participants. The results extend observations on RAN to an orthographically shallow language (Italian) and suggest an element of continuity between languages with opaque and transparent orthographies.

Awareness↗

PubMed2005

Drosophila nutrigenomics can provide clues to human gene-nutrient interactions.

Nutrigenomics refers to the complex effects of the nutritional environment on the genome, epigenome, and proteome of an organism. The diverse tissue- and organ-specific effects of diet include gene expression patterns, organization of the chromatin, and protein post-translational modifications. Long-term effects of diet range from obesity and associated diseases such as diabetes and cardiovascular disease to increased or decreased longevity. Furthermore, the diet of the mother can potentially have long-term health impacts on the children, possibly through inherited diet-induced chromatin alterations. Drosophila is a unique and ideal model organism for conducting nutrigenomics research for numerous reasons. Drosophila, yeast, and Caenorhabditis elegans all have sophisticated genetics as well as sequenced genomes, and researchers working with all three organisms have made valuable discoveries in nutrigenomics. However, unlike yeast and C. elegans, Drosophila has adipose-like tissues and a lipid transport system, making it a closer model to humans. This review summarizes what has already been learned in Drosophila nutrigenomics (with an emphasis on lipids and sterols), critically evaluates the data, and discusses fruitful areas for future research.

Aging↗

PubMed2005

Length effect in word naming in reading: role of reading experience and reading deficit in italian readers.

Vocal reaction times (RTs) in naming 3- to 8-letter words were measured in proficient and dyslexic readers (Study 1). In proficient readers, RTs were independent of word length up to 5-letter words, indicating parallel processing. In the 5- to 8-letter range, RTs increased linearly, indicating sequential processing. Reading experience was associated with both faster discrimination of individual elements and parallel processing of increasingly large word parts. In dyslexics, RTs increased linearly with increasing length indicating reliance on sequential decoding. Individual analysis indicated 2 profiles of RTs (Types A and B). In Study 2, the distinction between A and B dyslexics was not associated with the use of different reading procedures. However, a more marked speed deficit characterized Type B dyslexics.

Adolescent↗

PubMed2004

Word length effect in early reading and in developmental dyslexia.

Vocal reaction times were measured in Italian dyslexics and in proficient readers while they read single words. Three groups of control participants (for a total of 79) were tested. All were in the first, second or third grade of elementary school. Nine third graders with a low level of reading ability when assessed by standard reading procedures were also tested. Results indicated that vocal RTs of control participants were faster and less sensitive to word length as a function of age; also, there was a particularly marked change between first and second graders. Dyslexics' vocal RTs and errors were much worse than those of peer control participants and resembled those of first grade controls. It is suggested that normal readers in an orthographically transparent language (Italian) adopt a lexical strategy quite early in their learning. On the contrary, dyslexics seem unable to learn this mode of processing and continue to use a sub-lexical reading procedure.

Child↗

PubMed2003

Dopa decarboxylase (Ddc) affects variation in Drosophila longevity.

Mutational analyses in model organisms have shown that genes affecting metabolism and stress resistance regulate life span, but the genes responsible for variation in longevity in natural populations are largely unidentified. Previously, we mapped quantitative trait loci (QTLs) affecting variation in longevity between two Drosophila melanogaster strains. Here, we show that the longevity QTL in the 36E;38B cytogenetic interval on chromosome 2 contains multiple closely linked QTLs, including the Dopa decarboxylase (Ddc) locus. Complementation tests to mutations show that Ddc is a positional candidate gene for life span in these strains. Linkage disequilibrium (LD) mapping in a sample of 173 alleles from a single population shows that three common molecular polymorphisms in Ddc account for 15.5% of the genetic contribution to variance in life span from chromosome 2. The polymorphisms are in strong LD, and the effects of the haplotypes on longevity suggest that the polymorphisms are maintained by balancing selection. DDC catalyzes the final step in the synthesis of the neurotransmitters, dopamine and serotonin. Thus, these data implicate variation in the synthesis of bioamines as a factor contributing to natural variation in individual life span.

Animals↗

PubMed2002

Reading words and pseudowords: an eye movement study of developmental dyslexia.

The pattern of eye movements during reading was studied in 12 developmental dyslexics and in 10 age-matched controls. According to standard reading batteries, dyslexics showed marked reading slowness and prevalently used the sublexical procedure in reading. Eye movements were recorded while they read lists of short and long words or pseudowords. In normal readers, saccade amplitude increased with word length without a concomitant change in the number of saccades; in contrast, the number of saccades increased for long pseudowords. In dyslexics, the eye movement pattern was different. The number of saccades depended on stimulus length for both words and pseudowords while saccade amplitude remained small and constant. The sequential scanning shown by dyslexics for both words and pseudowords appears consistent with the cognitive description of the reading disorder which indicates the preferential use of the sublexical print-to-sound correspondence rules.

Adolescent↗

PubMed2002

Crowding effects on word identification in developmental dyslexia.

The effect of crowding on the identification of words was examined in normal readers and subjects with developmental dyslexia. In Experiment 1, a matching task was used. Words were presented either alone or embedded in other words. Vocal reaction times (RT) of dyslexics were slower and more sensitive to the presence of the surrounding stimuli than those of control subjects. Similar results were obtained in a control experiment using the same task for strings of symbols (isolated or crowded) instead of words. These data indicate that differences in crowding in control and dyslexic subjects arise at a pre-linguistic level. In Experiment 2, vocal RTs to word reading were measured. Two conditions putatively reducing the effect of crowding were tested: increasing inter-letter spacing and blurring. A moderate increase of inter-letter spacing produced faster vocal RTs in dyslexics, while no effect was present in normal controls. Moderate blurring of stimuli did not change dyslexics' RTs, while normal readers became slower. Group and individual results are discussed to evaluate the extent to which crowding contributes to the genesis of developmental dyslexia.

Adolescent↗