Reproducibility of artificial intelligence-enabled plaque measurements between systolic and diastolic phases from coronary computed tomography angiography.

OBJECTIVES: Current coronary CT angiography (CTA) guidelines suggest both end-systolic and mid-diastolic phases of the cardiac cycle can be used for CTA image acquisition. However, whether differences in the phase of the cardiac cycle influence coronary plaque measurements is not known. We aim to explore the potential impact of cardiac phases on quantitative plaque assessment. METHODS: We enrolled 39 consecutive patients (23 male, age 66.2 ± 11.5 years) who underwent CTA with dual-source CT with visually evident coronary atherosclerosis and with good image quality. End-systolic and mid- to late-diastolic phase images were reconstructed from the same CTA scan. Quantitative plaque and stenosis were analyzed in both systolic and diastolic images using artificial intelligence (AI)-enabled plaque analysis software (Autoplaque). RESULTS: Overall, 186 lesions from 39 patients were analyzed. There were excellent agreement and correlation between systolic and diastolic images for all plaque volume measurements (Lin's concordance coefficient ranging from 0.97 to 0.99; R ranging from 0.96 to 0.98). There were no substantial intrascan differences per patient between systolic and diastolic phases (p > 0.05 for all) for total (1017.1 ± 712.9 mm3 vs. 1014.7 ± 696.2 mm3), non-calcified (861.5 ± 553.7 mm3 vs. 856.5 ± 528.7 mm3), calcified (155.7 ± 229.3 mm3 vs. 158.2 ± 232.4 mm3), and low-density non-calcified plaque volume (151.4 ± 106.1 mm3 vs. 151.5 ± 101.5 mm3) and diameter stenosis (42.5 ± 18.4% vs 41.3 ± 15.1%). CONCLUSION: Excellent agreement and no substantial differences were observed in AI-enabled quantitative plaque measurements on CTA in systolic and diastolic images. Following further validation, standardized plaque measurements can be performed from CTA in systolic or diastolic cardiac phase. CLINICAL RELEVANCE STATEMENT: Quantitative plaque assessment using artificial intelligence-enabled plaque analysis software can provide standardized plaque quantification, regardless of cardiac phase. KEY POINTS: • The impact of different cardiac phases on coronary plaque measurements is unknown. • Plaque analysis using artificial intelligence-enabled software on systolic and diastolic CT angiography images shows excellent agreement. • Quantitative coronary artery plaque assessment can be performed regardless of cardiac phase.

Genealogical structure of the Colombian Romosinuano Creole cattle.

The Romosinuano cattle breed is one of the most important Creole genetic resources in Colombia, and interesting traits like adaptation or reproductive efficiency have promoted its use in different countries in America. To consolidate the genealogical historical records, the review of very first yield records in this population was used to reconstruct the genealogy of the breed since the first animals incorporated to the in vivo germplasm bank and estimate different demographic parameters. The complete genealogy comprises 17,136 animals with 5.8 years of generation interval for two pathways. The estimated average inbreeding for the population and inbred animals was 2.53% and 6.32% respectively, with a progressive increase of inbred animals across the generations. Almost 48% of the total animals presented some level of consanguinity. Effective population size (Ne) based on the inbreeding rate estimated by regression in all generations was 120 animals whereas Ne estimated by equivalent generations was 69 animals. Effective number of founders (Fe), effective number of ancestors (Fa), and ancestors explaining 50% of variability were 75, 48, and 22, respectively. The relation between Fa/Fe of 64% indicates a genetic bottleneck effect in the population studied.

Protocolo para la certificación por conformidad genética de clones en jardines de propagación de caucho (Hevea brasiliensis) / Protocol for the certification by genetic conformity of clones in rubber propagation gardens (Hevea brasiliensis)

RESUMEN A partir de visualización por electroforesis capilar de 9 regiones micro-satélites amplificadas con cebadores fluoromarcados se determinó el polimorfismo de los marcadores Hmct5, 102, HV 30, 548, HV 15, 416, m574, 103 y 358 identificados en el ADN de muestras de tejido foliar de 12 clones de caucho (Hevea brasiliensis) conservados en jardines clonales de AGROSAVIA en Colombia y 25 clones en jardines clonales de origen en Brasil. Con base en los resultados del análisis se consolidó una base de datos que permite corroborar la identidad por conformidad de clones de caucho a partir de muestras foliares. El protocolo establecido consiste en una aproximación metodológica para la amplificación de dichas regiones micro-satélites por PCR punto final y la visualización de los fragmentos obtenidos de este procedimiento por electroforesis capilar multiplexada, reduciendo costos y optimizando el tiempo en laboratorio. Adicionalmente se encontraron discrepancias entre el perfil electroforético obtenido del clon FX 3864 muestreado en Colombia con el obtenido en Brasil. Se propone considerar la necesidad de corroborar la identidad de los clones reproducidos en jardines clonales para su comercialización en Colombia, utilizando metodologías sensibles y reproducibles, como la estandarizada en este estudio.

ABSTRACT The polymorphism of 9 regions identified in the DNA of leaf tissue sampled from 12 rubber clones conserved in clonal gardens of AGROSAVIA in Colombia and 25 clones in clonal gardens of origin in Brazil was visualized by capillary electrophoresis after amplification with the fluorolabeled primer microsatellite markers Hmct5, 102, HV 30, 548, HV 15, 416, m574, 103 and 358. Upon the results analysis, a database was consolidated that allows to corroborate the genetical identity by conformity with 37 rubber clones from leaf samples. The established protocol is a methodological approach using end-point PCR towards the amplification by multiplexed capillary electrophoresis of micro-satellite regions and their visualization, reducing costs and optimizing time in the laboratory. Additionally, discrepancies were found between the electrophoretic profile obtained from clone FX 3864 sampled in Colombia with that obtained in Brazil. It is proposed to consider the need to corroborate the identity of the clones reproduced in clonal gardens for their commercialization in Colombia, using sensitive and reproducible methodologies, such as the one standardized in this study.

Genetic parameters and trends for growth traits in Blanco Orejinegro cattle.

Since 1940, efforts have been made to preserve the Blanco Orejinegro (BON) cattle breed by maintaining gene banks. Nine years ago, a BON genetic improvement program was implemented to increase genetic gain based on control of productivity and the use of performance tests, polygenic and genomic evaluations, and selection indices. The objective of this study was to estimate genetic parameters and trends for growth traits by using polygenic (PM) and genomic-polygenic (GPM) models. Productive information from the years 1980 to 2019 was used. The following data were used: 7,304 birth weight (BW) records, 1,281 records of body weight adjusted to 120 days (W120), 4,791 records of weight adjusted to 240 days (W240), 3,339 records of weight adjusted to 480 days (W480), and 1,364 records of weight adjusted to 720 days (W720). The relationship matrix included 13,612 pure animals belonging to the Colombian Corporation for Agricultural Research - AGROSAVIA and the Producer Network program. A total of 1,224 individuals were genotyped with chips of different densities and all were imputed up to 50,932 SNPs. Polygenic and genomic-polygenic models were used to estimate genetic parameters and correlations between the genetic values estimated by each model. A generalized additive model with smoothing was used to estimate trends of genetic values from 1980 to 2019. Heritabilities between 0.29 and 0.40, genetic correlations between 0.13 and 0.94, and phenotypic correlations between 0.23 and 0.72 were observed. Close-to-zero genetic growth was observed for BW and W120. Genetic trends for the other traits were positive, with higher growth in the last 7 years. The heritabilities observed in this population indicate that the traits measured would respond to selection. Greater genetic progress can be achieved in W240, W480, and W720 by continuing with genetic evaluations and developing performance tests and strategies to make genetic material readily available to producers.

Using near-infrared spectroscopy to determine intramuscular fat and fatty acids of beef applying different prediction approaches.

This study aimed to predict fat and fatty acids (FA) contents in beef using near-infrared spectroscopy and prediction models based on partial least squares (PLS) and support vector machine regression in radial kernel (R-SVR). Fat and FA were assessed in 200 longissimus thoracis samples, and spectra were collected in reflectance mode from ground meat. The analyses were performed for PLS and R-SVR with and without wavelength selection based on genetic algorithms (GAs). The GA application improved the error prediction by 15% and 68% for PLS and R-SVR, respectively. Models based on GA plus R-SMV showed a prediction ability for fat and FA with an average coefficient of determination of 0.92 and ratio performance deviation of 4.8.

Transposon Insertions, Structural Variations, and SNPs Contribute to the Evolution of the Melon Genome.

The availability of extensive databases of crop genome sequences should allow analysis of crop variability at an unprecedented scale, which should have an important impact in plant breeding. However, up to now the analysis of genetic variability at the whole-genome scale has been mainly restricted to single nucleotide polymorphisms (SNPs). This is a strong limitation as structural variation (SV) and transposon insertion polymorphisms are frequent in plant species and have had an important mutational role in crop domestication and breeding. Here, we present the first comprehensive analysis of melon genetic diversity, which includes a detailed analysis of SNPs, SV, and transposon insertion polymorphisms. The variability found among seven melon varieties representing the species diversity and including wild accessions and highly breed lines, is relatively high due in part to the marked divergence of some lineages. The diversity is distributed nonuniformly across the genome, being lower at the extremes of the chromosomes and higher in the pericentromeric regions, which is compatible with the effect of purifying selection and recombination forces over functional regions. Additionally, this variability is greatly reduced among elite varieties, probably due to selection during breeding. We have found some chromosomal regions showing a high differentiation of the elite varieties versus the rest, which could be considered as strongly selected candidate regions. Our data also suggest that transposons and SV may be at the origin of an important fraction of the variability in melon, which highlights the importance of analyzing all types of genetic variability to understand crop genome evolution.

Characterization of the porcine nutrient and taste receptor gene repertoire in domestic and wild populations across the globe.

BACKGROUND: The oral GPCR nutrient/taste receptor gene repertoire consists of the Tas1r family (sweet and umami tastes), the Tas2r family (bitter taste) as well as several other potential candidate sensors of amino acids, peptones and fatty acids. Taste/nutrient receptors play a fundamental role in survival through the identification of dietary nutrients or potentially toxic compounds. In humans and rodents some variations in taste sensitivity have been related to receptor polymorphisms. Some allelic variants, in turn, have been linked to the adaptation to specific geographical locations and dietary regimes. In contrast, the porcine taste/nutrient receptor repertoire has been only partially characterized and limited information on genetic variation across breeds and geographical location exists. The present study aims at filling this void which in turn will form the bases for future improvements in pig nutrition. RESULTS: Our results show that the pig oral repertoire of taste/nutrient receptors consists of at least 28 receptor genes with significant transcription measured for 27. When compared to humans and rodents, the porcine gene sequences encoding sensors for carbohydrates, amino acids and fatty acids were highly conserved whilst the bitter taste gene family (known as Tas2rs) showed high divergence. We identified 15 porcine Tas2rs of which 13 are orthologous to human sequences. The single nucleotide polymorphism (SNP) sequence analysis using 79 pig genomes, representing 14 different breeds/populations, revealed that the Tas2r subset had higher variability (average π =2.8 × 10-3) than for non-bitter taste genes (π =1.2-1.5 × 10-3). In addition, our results show that the difference in nutrient receptor genes between Asian and European breeds accounts for only a small part of the variability, which is in contrast with previous findings involving genome wide data. CONCLUSIONS: We have defined twenty-eight oral nutrient sensing related genes for the pig. The homology with the human repertoire is high for the porcine non-bitter taste gene repertoire and low for the porcine Tas2r repertoire. Our data suggests that bitter taste is a plastic trait, possibly associated with the ability of pigs to adapt to diverse environments and that may be subject to balancing selection.

Incremental value of diagonal earlobe crease to the Diamond-Forrester classification in estimating the probability of significant coronary artery disease determined by computed tomographic angiography.

The Diamond-Forrester (DF) algorithm overestimates the likelihood of significant coronary artery disease (≥50% stenosis, CAD50). The aim of the present study was to evaluate whether the addition of a diagonal earlobe crease (DELC) enhances the predictive ability of DF to detect CAD50 by coronary computed tomographic angiography (CTA). We evaluated 430 patients referred for CTA for symptoms, cardiovascular risk factors, and CAD50 likelihood using DF. Observers blinded to CTA findings evaluated the presence of DELC. The diagnostic accuracy and relation of DF, DELC, and DF + DELC for predicting CAD50 in patients with chest pain were evaluated using receiver operating characteristics curve (area under curve) analyses and multivariate logistic regression analyses. In 199 patients with chest pain, the sensitivity and specificity for CAD50 were 96% and 20% for DF (AUC 0.59, p = 0.59), 91% and 32% for DELC (AUC 0.62, p = 0.03), and 91% and 41% for DF + DELC (AUC 0.66, p = 0.004). On multivariate analyses DELC was the only independent predictor of CAD50 (odds ratio 3.6, 95% confidence interval 1 to 12.9, p = 0.048). DF + DELC increased the predictive ability to detect CAD50 above cardiovascular risk factors (odds ratio 5.6, 95% confidence interval 1.6 to 19.8, p = 0.007). In patients with chest pain, the presence of DELC is related to CAD50 beyond DF. A combined variable of DF + DELC provides superior discriminatory ability for detecting CAD50 than either method alone.

Low radiation coronary calcium scoring by dual-source CT with tube current optimization based on patient body size.

BACKGROUND: Reducing tube voltage from 120 kV to 100 kV during noncontrast CT for the detection of coronary artery calcium reduces patient radiation exposure. OBJECTIVE: We investigated whether coronary calcium scoring by multidetector row CT can be performed at reduced tube current, resulting in lower radiation dose to the patient. METHODS: Sixty-six outpatients were scanned on the same visit by dual-source CT (DSCT) with a standard protocol (120 kVp, 150 mAs), followed by a scan with reduced tube current: 85 mAs for patients with body mass index (BMI) ≤ 30 kg/m(2) and weight ≤ 85 kg, and 120 mAs for patients with BMI > 30 kg/m(2) or weight > 85 kg. Low-dose scans were scored by an experienced reader blinded to the standard scan. RESULTS: Agatston scores (ASs) and calcium volume for standard versus low-dose scans were 236 ± 581 versus 234 ± 586 (P = 0.65, NS), and 189 ± 460 mm(3) versus 184 ± 455 mm(3) with excellent correlation (r = 1.0, P < 0.0001), and no significant difference (P = 0.14, NS). Effective radiation dose for the low-dose protocol (1.0 ± 0.2 mSv) was significantly lower than for the standard protocol (1.7 ± 0.2 mSv; P < 0.0001). Image noise was higher for the low-dose scan (18.8 ± 5.5 HU vs 15.2 ± 4.8 HU; P < 0.0001), but both were within target limits. CONCLUSION: Noncontrast CT for measurement of coronary artery calcium with lower tube current optimized for patient body size is equivalent to standard methods at 40% lower radiation dose, indicating that radiation dose can be lowered for coronary calcium scanning.

Relation of diagonal ear lobe crease to the presence, extent, and severity of coronary artery disease determined by coronary computed tomography angiography.

Controversy exists concerning the relation between diagonal ear lobe crease (DELC) and coronary artery disease (CAD). We examined whether DELC is associated with CAD using coronary computed tomography (CT) angiography. We studied 430 consecutive patients without a history of coronary artery intervention who underwent CT angiography on a dual-source scanner. Presence of DELC was agreed by 2 blinded observers. Two blinded readers evaluated CT angiography images for presence of CAD and for significant CAD (≥50% stenosis). Chi-square and t tests were used to assess demographic differences between subgroups with and without DELC and the relation of DELC to 4 measurements of CAD: any CAD, significant CAD, multivessel disease (cutoff ≥2), and number of segments with plaque (cutoff ≥3). Multivariable logistic regression was performed to adjust for CAD confounders: age, gender, symptoms, and CAD risk factors. Mean age was 61 ± 13 and 61% were men. DELC was found in 71%, any CAD in 71%, and significant CAD in 17% of patients. After adjusting for confounders, DELC remained a significant predictor of all 4 measurements of CAD (odds ratio 1.8 to 3.3, p = 0.002 to 0.017). Sensitivity, specificity, and positive and negative predictive values for DELC in detecting any CAD were 78%, 43%, 77%, and 45%. Test accuracy was calculated at 67%. Area under the receiver operator characteristic curve was 61% (p = 0.001). In conclusion, in this study of patients imaged with CT angiography, finding DELC was independently and significantly associated with increased prevalence, extent, and severity of CAD.

Genetic diversity and population structure of the Guinea pig (Cavia porcellus, Rodentia, Caviidae) in Colombia.

The aim was to establish the genetic diversity and population structure of three guinea pig lines, from seven production zones located in Nariño, southwest Colombia. A total of 384 individuals were genotyped with six microsatellite markers. The measurement of intrapopulation diversity revealed allelic richness ranging from 3.0 to 6.56, and observed heterozygosity (Ho) from 0.33 to 0.60, with a deficit in heterozygous individuals. Although statistically significant (p < 0.05), genetic differentiation between population pairs was found to be low. Genetic distance, as well as clustering of guinea-pig lines and populations, coincided with the historical and geographical distribution of the populations. Likewise, high genetic identity between improved and native lines was established. An analysis of group probabilistic assignment revealed that each line should not be considered as a genetically homogeneous group. The findings corroborate the absorption of native genetic material into the improved line introduced into Colombia from Peru. It is necessary to establish conservation programs for native-line individuals in Nariño, and control genealogical and production records in order to reduce the inbreeding values in the populations.

Genetic diversity and population structure of the Guinea pig (Cavia porcellus, Rodentia, caviidae) in Colombia

The aim was to establish the genetic diversity and population structure of three guinea pig lines, from seven production zones located in Nariño, southwest Colombia. A total of 384 individuals were genotyped with six microsatellite markers. The measurement of intrapopulation diversity revealed allelic richness ranging from 3.0 to 6.56, and observed heterozygosity (Ho) from 0.33 to 0.60, with a deficit in heterozygous individuals. Although statistically significant (p < 0.05), genetic differentiation between population pairs was found to be low. Genetic distance, as well as clustering of guinea-pig lines and populations, coincided with the historical and geographical distribution of the populations. Likewise, high genetic identity between improved and native lines was established. An analysis of group probabilistic assignment revealed that each line should not be considered as a genetically homogeneous group. The findings corroborate the absorption of native genetic material into the improved line introduced into Colombia from Peru. It is necessary to establish conservation programs for native-line individuals in Nariño, and control genealogical and production records in order to reduce the inbreeding values in the populations.

Coronary artery calcium scoring using a reduced tube voltage and radiation dose protocol with dual-source computed tomography.

BACKGROUND: Technical advances to minimize radiation exposure because of imaging are in accord with the "as low as reasonably achievable" principle. OBJECTIVE: We aimed to determine whether coronary calcium scoring (CCS) by multidetector CT at a tube voltage of 100 kVp yields comparable results to the standard 120-kVp protocol while reducing radiation dose. METHODS: Sixty consecutive outpatients were scanned with a dual-source CT scanner with both the120- and 100-kVp protocols. The calcium threshold was 130 Hounsfield units (HUs) for 120 kVp and 147 HU for 100 kVp, as determined from phantom data. All 100-kVp scans were scored by an experienced reader blinded to 120-kVp data. RESULTS: Image quality was comparable for 100- and 120- kVp scans. Mean Agatston scores for 100 and 120 kVp were 189 +/- 484 and 189 +/- 498 (P = 0.92), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -36 to 37; bias, 0.6). Mean coronary calcium volume scores for 100 and 120 kVp were 143 +/- 370 mm(3) and 149 +/- 392 mm(3) (P = 0.26), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -35 to 32 mm(3); bias, -1.4 mm(3)). The mean absolute difference for Agatston scores between the protocols was 16.9, with excellent agreement (kappa = 0.95; P < 0.0001). Mean effective radiation dose for the 100-kVp protocol was significantly lower (1.17 mSv versus 1.70 mSv; P < 0.0001). CONCLUSION: A reduced tube current protocol using 100 kVp gives equivalent CCS results at reduced radiation exposure compared with a standard protocol at 120 kVp.

Predicting success of prospective and retrospective gating with dual-source coronary computed tomography angiography: development of selection criteria and initial experience.

BACKGROUND: Prospectively gated coronary computed tomographic angiography (CCTA) with dual-source CT allows substantial reduction of radiation exposure but requires prospective single-phase selection and assessment of likelihood of adequate image quality. OBJECTIVE: We developed and tested the model for predicting success of prospectively gated CCTA. METHODS: Retrospectively gated CCTA was acquired with dual-source CT in 162 patients. Two cardiologists assessed by consensus whether diagnostic quality images could have been obtained in a single predefined phase, 70% of R-R interval (70P), thereby identifying patients in whom a prospectively gated scan at 70P would have been successful. Logistic regression models were built with and without a coronary calcium scan. The obtained criteria were applied on 42 additional patients. RESULTS: By logistic regression, heart rate before CCTA of >or=70 beats/min, maximal heart rate variation before CCTA of >or=10 beats/min, coronary calcium score >or= 400 U, and body mass index (in kg/m(2)) >or= 30 were independent predictors of unsuccessful prospectively gated CCTA using 70P. Excluding coronary calcium score from the model, these same variables in addition to age > 65 years were found to be predictors of unsuccessful prospectively gated CCTA. Applying this model to 42 additional patients, using prospective gating, only 5 segments in 4 patients were nondiagnostic. Mean radiation dose for prospectively gated CCTA was 2.2 +/- 0.8 mSv. CONCLUSION: Prospectively gated CCTA with dual-source CT can be successfully implemented with consideration of prescan heart rate, heart rate variability, body mass index, and coronary calcium score.

Algorithm for radiation dose reduction with helical dual source coronary computed tomography angiography in clinical practice.

BACKGROUND: Strategies to reduce the radiation dose of coronary computed tomography angiography (CCTA), while maintaining diagnostic image quality, are imperative for cardiac CT. OBJECTIVE: We aimed to reduce radiation dose during helical dual-source CCTA by combining lower tube voltage, shortest possible full tube current (FTC) window, and minimal tube current outside the FTC window, and to develop a patient-based algorithm for applying these dose-reduction components. METHODS: We compared FTC at 70% of the cardiac cycle (FTC70) to a 45% to 75% window (FTC45-75) using both 100 and 120 kVp (N=118). FTC70 was used in patients with heart rates <70 beats/min, no arrhythmia, age <65 years; 100 kVp was used in patients with body mass index (BMI) <30, a low coronary calcium score (CCS), and no stents. Objective and subjective image quality were assessed. RESULTS: Compared with FTC45-75 at 120 kVp, radiation dose was reduced by 66% for FTC70 at 100 kVp (mean radiation dose: 4.4 +/- 0.9 mSv) and by 43% for FTC70 at 120 kVp. 99% of 780 segments in the FTC70 group were of diagnostic quality. Noise, signal-to-noise ratio, and contrast-to-noise ratio were comparable between FTC70 and FTC45-75 for both 100 and 120 kVp. BMI, CCS and maximal heart rate variation were predictors of image quality. Tube voltage, FTC window width, scan length, and average heart rate were predictors of radiation dose. CONCLUSIONS: A successful patient-based algorithm for radiation dose reduction during helical CCTA using DSCT has been developed and validated in clinical practice.

Caracterización molecular de tres líneas de Cavia porcellus mediante la aplicación de AFLP / Molecular characterization of three populations of Cavia porcellus with AFLP markers

Los marcadores moleculares son una herramienta eficaz para determinar variabilidad genética entre y dentro de poblaciones, pero en el caso de Cavia porcellus, no existen reportes referentes al uso de estas técnicas. Con los marcadores moleculares AFLP´s (Amplified Fragment Length Polimorphism), se analizaron tres poblaciones, dos criollas y una mejorada genéticamente, sometida a selección durante varias generaciones y obtenida a partir del cruzamiento entre animales peruanos y nativos de Nariño. Para obtener los marcadores moleculares AFLP´s (Amplified Fragment Lenght Polimorphism), se utilizaron en total cinco combinaciones de cebadores, tres combinaciones recomendadas para el orden Rodenthia y dos por la casa fabricante del Kit, de las cuales sólo una de ellas, con 116 loci, permitió establecer diferencias entre las poblaciones estudiadas, de acuerdo con el valor de distancia genética insesgada de Nei (p<0.01). Las dos poblaciones criollas constituyeron un grupo estrechamente relacionado y distante de la población mejorada genéticamente, lo que indica que los animales importados absorbieron al criollo. De acuerdo con los valores de heterocigosidad promedio, que variaron entre 0.48% y 14.48%, y el porcentaje de polimorfismo que osciló entre 0.00% y 39.65%, se deduce una baja variabilidad intrapoblacional, siendo la población mejorada genéticamente la más polimórfica. La baja variabilidad entre los animales mejorados, se explica por la intensa selección a la que han sido sometidos, mientras que en los núcleos criollos este fenómeno puede atribuirse al bajo tamaño efectivo en las dos poblaciones. Los resultados de esta investigación sugieren un replanteamiento de los programas de mejoramiento genético y conservación de los recursos genéticos autóctonos en la región.

Molecular markers are a powerful tool to determine genetic variability within and among populations, but for the Cavia porcellus there are no reports on the use of these techniques. Three populations, two native and another one, genetically improved which was obtained by crossing native and Peruvian animals and submitted to genetic selection through several generations were analyzed by means of AFLP markers. Five primer’s combinations recommended for Rodenthia were used, but only one allowed to establish significant differences (p<0.01) according to unbiased Nei´s distance Value. Both native populations were grouped in a cluster genetically distant from the genetically improved animals. This showed that foreign animals absorbed the native populations. The average heterosigosity between 0.48% and 14.48% and the percentage of polymorphisms between 0.00% and 39.65% allow to conclude that there was a low variability between the populations, but the population genetically improved was the most polymorphic. The low variability within the improved animals it can be explained because of the intensive selection procedures use with them, whereas within the native populations can be explained because of their very low populations effective size. These results suggest that there is a need to restate the genetic improvement and preservation programs of the native Cavia porcellus in the southwest region of Colombia.

Polimorfismos en la longitud de fragmentos amplificados (AFLP´s) a partir de muestras de sangre almacenadas en tarjetas FTA®para la especie Cavia porcellus Lin. (Rodentia: Caviidae). / Amplified Fragments Length Polymorphisms (AFLP´s) from blood samples stored in FTA® cards for Cavia porcellus

Una manera eficaz de establecer el grado de variabilidad entre y dentro de poblaciones, es a través del análisis de polimorfismos de ADN con marcadores moleculares como los AFLP`s. En este artículo se presenta una metodología que combina la utilización de tarjetas de FTA® (Whatman Bioscience, Cambridge) para colección y conservación de muestras de sangre, con los procedimientos de extracción de ADN y obtención de marcadores AFLP´s, aspectos sobre los cuales no existen antecedentes para la especie Cavia porcellus. Se utilizaron muestras de ADN procedentes de tres poblaciones, dos criollas y una mejorada genéticamente obtenida a partir de un pie de cría procedente del Perú y sometida a selección en Colombia durante varias generaciones. Todos los animales procedieron de la Granja “Botana”, propiedad de la Universidad de Nariño, Pasto-Colombia. Para la detección de polimorfismos en la longitud de los fragmentos (AFLP`s) se utilizaron uno, tres y cinco discos FTA® de 1.2 mm, cada disco con aproximadamente 25 ng de ADN. Los ensayos indicaron que los mejores productos de amplificación, para la visualización de AFLP´s, se obtuvieron de muestras con tres discos de FTA por individuo, lo que sugiere que con esta metodología,75 ng de ADN por animal son suficientes para detectar polimorfismos de alta calidad en el genoma de Cavia porcellus. Se recomienda el uso de las tarjetas de FTA para el estudio genético de poblaciones de Cavia porcellus, con las modificaciones metodológicas descritas en este artículo para marcadores AFLP´s.

A methodology that includes the use of FTA® (Whatman Bioscience, Cambridge) to collect and store animals` blood samples and the procedures to extract and to get AFLP markers is presented in this paper. A review of the literature indicates that there are no reports concerning both aspects for the Cavia porcellus case. To reach our goal blood samples of three populations – Two native ones and other genetically improved- were obtained through heart puncture. This blood was stored in the FTA cards in order to extract, purify, amplify and analyze their DNA forms. All of the animals came from “Botana” farm of the Universidad de Nariño, located in Pasto, Colombia. For amplifying the AFLP one, three and five 1.2 mm FTA disks of approximately 75 ng of DNA per disk where used. The tests indicated that the best products to amplify and to visualize the AFLP where those ones obtained from samples of three FTA disks per animal. This suggests that 75 ng of DNA per animal is enough to generate AFLP of high quality in the Cavia porcellus` genome. We recommend the use of FTA cards to carry out genetic analyses in the Cavia porcellus, including the methodology modifications presented in this paper.