Biomedical subjects

J Altarriba

Publications and source records attributed to J Altarriba.

12 recordsLinked to original sources

PubMed2006

Association of polymorphisms in the bovine FASN gene with milk-fat content.

Fatty acid synthase (FASN) is a multifunctional protein that carries out the synthesis of fatty acids so it plays a central role in de novo lipogenesis in mammals. Previously, we defined the genetic structure and expression of the bovine FASN gene. Our mapping studies placed FASN on BTA19 (19q22) where several quantitative trait loci (QTL) affecting milk-fat content and related traits have been described. This study was conducted to identify polymorphisms in the bovine FASN gene and to study their association with milk-fat content. The bovine FASN gene was screened for polymorphisms in two cattle breeds. Sequence analysis revealed several single nucleotide polymorphisms (SNPs), and two of them were analysed: a G>C substitution in the untranslated exon 1 (g.763G>C), altering a potential Sp1 transcription factor-binding site, and an A>G substitution in exon 34 (g.16009A>G), which determines a non-conservative substitution of threonine by alanine. Allele-specific amplification of the SNPs in FASN revealed significant frequency differences for both polymorphisms in Holsteins with high and low breeding values for milk-fat content. The intragenic haplotypes comprising exon 1 (alleles G and C) and exon 34 (alleles A and G) polymorphisms were studied, and the existence of linkage disequilibrium between these SNPs was found (D(CG) = 0.048, P < 0.001). Our results suggest that the FASN gene polymorphisms contribute to variation in milk-fat content. We propose that the bovine FASN gene is a candidate gene for a milk-fat content QTL.

Alleles↗

PubMed2002

Prediction of fertility by centrifugal countercurrent distribution (CCCD) analysis: correlation between viability and heterogeneity of ram semen and field fertility.

The prediction of the fertilizing ability of a sire or a given insemination dose is a primary aim in the field of artificial insemination. Centrifugal countercurrent distribution analysis (CCCD) was used to determine the relationship between some sperm parameters and the in vivo fertility rate obtained with the same sample after cervical artificial insemination. A total of 522 ewes from 26 different farms was inseminated with 53 ejaculates obtained from 25 mature Rasa aragonesa rams. Semen was diluted to 1.6 x 10(9) cells ml-1 and doses of 0.25 ml were prepared and kept at 15 degrees C until used for insemination. The same ejaculates were used for analysis of standard semen parameters and CCCD analysis. Sperm motility, concentration and viability were determined before and after CCCD. Post-CCCD parameters were derived from the analysis of the profile obtained after CCCD. The recovered viability showed the highest correlation with fertility, especially in the central chambers (V2), r = 0.415, P < 0.005). The ejaculate heterogeneity also showed a positive correlation with field fertility (r = 0.23), with a tendency towards significance (P < 0.1). The mean fertility value of all ejaculates used in this study was 46.75%, ranging from 12.5% to 75.0%. Ejaculates were classified into two categories according to their fertility: higher and lower than the mean value. Only the viability recovered in the central chambers (V2) was a parameter with a predictive capacity to discriminate between the two groups (P < 0.05). A predictive equation for field fertility with a correlation coefficient r = 0.488 and a very high level of significance (P < 0.005) was deduced by multiple analysis: PF = 6.02 + 0.069V2 + 0.315H (where PF is predictive fertility, V2 is the recovered viability in the CCCD profile central chambers and H is heterogeneity).

Animals↗

PubMed2001

Semantic codes are not used in integrating information across eye fixations in reading: evidence from fluent Spanish-English bilinguals.

The question of whether meaning can be extracted from unidentified parafoveal words was examined using fluent Spanish-English bilinguals. In Experiment 1, subjects fixated on a central cross, and a preview word was presented to the right of fixation in parafoveal vision. During the saccade to the parafoveal preview word, the preview was replaced by the target word, which the subject was required to name. In Experiment 2, subjects read sentences containing the target word, and, as in the naming task, a preview word was replaced by the target word when the subject's saccade crossed a boundary location. In both experiments, preview words were identical to the target word, translations, orthographic controls for the translations, or unrelated words in the opposite language. In both experiments, the preview benefit from the translation conditions was no greater than would be predicted by the orthographic similarity of the preview to the target. Hence, the data indicated that subjects obtained no useful semantic information from words seen parafoveally that enabled them to identify them more quickly on the subsequent fixation.

Adult↗

PubMed2000

Novel popout and familiar popout in a brightness discrimination task.

A single novel word among several familiarized words may be localized more effectively than the familiarized words (novel popout). Early demonstrations of novel popout attributed the effect to the capture of attentional resources by novel stimuli. Christie and Klein (1995, 1996) argued that differential recollection of novel versus familiar words could alternatively account for the popout effect. In the present experiments, participants judged which of four locations contained a physically brighter word. A bright novel word was localized significantly better than a bright familiar word in one-novel/three-familiar arrays, inconsistent with a retrievability account of novel popout. However, a bright familiar word was also localized better than a bright novel word in three-novel/one-familiar arrays, inconsistent with the mismatch theory proposed by Johnston and Hawley (1994). The results suggest that familiarity and novelty provide a perceptual segregation of the odd item; superior brightness discrimination at that location may be due either to attentional capture or to locational ambiguity within the larger group.

Attention↗

PubMed1999

Concreteness, context availability, and imageability ratings and word associations for abstract, concrete, and emotion words.

Normative values on various word characteristics were obtained for abstract, concrete, and emotion words in order to facilitate research on concreteness effects and on the similarities and differences among the three word types. A sample of 78 participants rated abstract, concrete, and emotion words on concreteness, context availability, and imagery scales. Word associations were also gathered for abstract, concrete, and emotion words. The data were used to investigate similarities and differences among these three word types on word attributes, association strengths, and number of associations. These normative data can be used to further research on concreteness effects, word type effects, and word recognition for abstract, concrete, and emotion words.

Adult↗

PubMed1998

Bayesian inference of variance components for litter size in Rasa Aragonesa sheep.

Variance components were estimated for litter size in Rasa Aragonesa sheep, a meat breed from northern Spain, to determine whether selective breeding for litter size is a reasonable strategy to improve reproductive performance. We assumed an animal mixed effect threshold model with a binary response variable. Marginal estimates of the genetic parameters were obtained in the underlying scale using Bayesian inference, implemented via the Gibbs sampling procedure and a data augmentation approach. Posterior marginal means of heritability and repeatability were .077 and .141, respectively. Moreover, the 95% highest marginal posterior density region of heritability ranged from .051 to .101. Therefore, we conclude that litter size is a trait that could be selected for in breeding programs. The effect of the loss of pedigree information, a common feature of sheep production, on the estimation of the genetic parameters was also studied using simulation. The results indicate that the lack of pedigree information has little effect on our estimates of heritability.

Animals↗

PubMed1998

Bayesian analysis of Wood's lactation curve for Spanish dairy cows.

A Bayesian procedure is presented to analyze test day performances in the scope of Wood's lactation function: atb (exp (-ct)), where a, b, and c = parameters, and t = time-dependent variable. The procedure has been applied to 148,557 test day controls corresponding to records for 15,349 first lactations of Spanish dairy cows. The procedure uses all available information and reduces the presence of atypical lactations. Moreover, the posterior marginal distribution of (co)variance components, breeding values, and systematic effects for the underlying variables of Wood's function are provided. The posterior means of the heritabilities were 0.43, 0.17, 0.40, and 0.29 for the parameters a (initial milk yield), b (ascent to peak), c (descent from peak), and total milk yield, respectively. Selection for total milk yield implies a great effect on the initial milk yield (a) but only minor effects on ascent to peak (b) and descent from peak (c).

Aging↗

PubMed1998

Novel popout without novelty.

Localization of a novel word in an array with several familiar words is typically enhanced relative to localization in an all-novel array (between-array novel popout) and sometimes enhanced relative to familiar words in one-novel arrays (within-array novel popout). Christie and Klein (1996) have questioned the reality of the latter effect, suggesting that it may be an artifact of guessing bias. The present Experiment 1 replicated within-array novel popout with the novel word probed at chance (i.e., on only one quarter of trials). Experiments 2 and 3 demonstrated a similar popout effect for a categorically unrelated word among three categorically related words, despite superior performance on all-related arrays relative to all-unrelated arrays. Repetition of constant sets of words within the experimental context is therefore unnecessary for a popout effect, contrary to assertions by Johnston and Hawley (1994). Interitem associations appear to be sufficient to produce a popout effect; as such, "novel popout" appears to be a misnomer for a phenomenon that does not depend on novelty.

Adult↗

PubMed1996

The influence of lexical and conceptual constraints on reading mixed-language sentences: evidence from eye fixations and naming times.

In two experiments, we explored the degree to which sentence context effects operate at a lexical or conceptual level by examining the processing of mixed-language sentences by fluent Spanish-English bilinguals. In Experiment 1, subjects' eye movements were monitored while they read English sentences in which sentence constraint, word frequency, and language of target word were manipulated. A frequency x constraint interaction was found when target words appeared in Spanish, but not in English. First fixation durations were longer for high-frequency Spanish words when these were embedded in high-constraint sentences than in low-constraint sentences. This result suggests that the conceptual restrictions produced by the sentence context were met, but that the lexical restrictions were not. The same result did not occur for low-frequency Spanish words, presumably because the slower access of low-frequency words provided more processing time for the resolution of this conflict. Similar results were found in Experiment 2 using rapid serial visual presentation when subjects named the target words aloud. It appears that sentence context effects are influenced by both semantic/conceptual and lexical information.

Adult↗

PubMed1996

Repetition blindness and bilingual memory: token individuation for translation equivalents.

The repetition blindness effect (RB) occurs when individuals are unable to recall a repeated word relative to a nonrepeated word in a sentence or string of words presented in a rapid serial visual presentation task. This effect was explored across languages (English and Spanish) in an attempt to provide evidence for RB at a conceptual level using noncognate translation equivalents (e.g., nephew-sobrino). In the first experiment, RB was found when a word was repeated in an English sentence but not when the two repetitions were in different languages. In the second experiment, RB was found for identical repetitions in Spanish and in English using word lists. However, the cross-language condition produced significant facilitation in recall, suggesting that although conceptual processing had taken place, semantic overlap was not sufficient to produce RB. The results confirm Kanwisher's (1987) token individuation hypothesis in the case of translation equivalents.

Adult↗

PubMed1989

Constraints on priming in spatial memory: naturally learned versus experimentally learned environments.

In four experiments, we explored constraints on priming in spatial memory. In Experiments 1 and 2, subjects who were familiar with the locations of buildings on the Vanderbilt campus participated in a recognition test. The subjects' task was to decide whether or not named buildings were on the campus. Foils in this recognition test were realistic but fictional names of buildings. In principle, the subjects could have performed this task without using spatial knowledge; in fact, they must not have used spatial knowledge, because there was no evidence of priming in recognition as a function of the spatial relations between buildings on the campus. This result differs from those obtained in earlier experiments that have examined memory of spatial layouts learned in laboratory settings. In Experiment 3, the fictional foils were replaced by names of buildings in an area of the campus separated geographically from the main campus. Evidently, this change induced subjects to retrieve spatial knowledge, because the spatial priming effect materialized. A fourth experiment replicated the above findings in a single experiment and demonstrated that spatial priming could be obtained when the configuration of buildings was learned experimentally. These results are explained by appealing to the "decontextualization" that takes place in memory over time.

Adult↗

PubMed1983

Computer methodology for simulation and prediction of alloimmune responses: expected antibody specificities.

The methodology presented here was developed for simulating planned alloimmunization results, with regard to the type and number of expected antibody specificities. The computer program designed for this purpose was adapted to an immunogenetic model using Boolean algebra. It was written to help immunogeneticists avoid handling routine data preceding selection of donor-recipient pairs, specially concerning blood type alloimmunizations in animals: all of the donor-recipient combinations and the expected antibody specificities (their limit number being specified in each particular immunization program) are provided in the print-out.

Animals↗