Isolation of a Highly Thermal Stable Lama Single Domain Antibody Specific for Staphylococcus aureusEnterotoxin B

Abstract Background Camelids and sharks possess a unique subclass of antibodies comprised of only heavy chains. The antigen binding fragments of these unique antibodies can be cloned and expressed as single domain antibodies (sdAbs). The ability of these small antigen-binding molecules to refold after heating to achieve their original structure, as well as their diminutive size, makes them attractive candidates for diagnostic assays. Results Here we describe the isolation of an sdAb against Staphyloccocus aureus enterotoxin B (SEB). The clone, A3, was found to have high affinity (Kd = 75 pM) and good specificity for SEB, showing no cross reactivity to related molecules such as Staphylococcal enterotoxin A (SEA), Staphylococcal enterotoxin D (SED), and Shiga toxin. Most remarkably, this anti-SEB sdAb had an extremely high Tm of 85°C and an ability to refold after heating to 95°C. The sharp Tm determined by circular dichroism, was found to contrast with the gradual decrease observed in intrinsic fluorescence. We demonstrated the utility of this sdAb as a capture and detector molecule in Luminex based assays providing limits of detection (LODs) of at least 64 pg/mL. Conclusion The anti-SEB sdAb A3 was found to have a high affinity and an extraordinarily high Tm and could still refold to recover activity after heat denaturation. This combination of heat resilience and strong, specific binding make this sdAb a good candidate for use in antibody-based toxin detection technologies. </jats:sec

Polymorphisms influencing the shovel-shaped incisors phenotype in Puerto Rico

Puerto Ricans phenotypic traits are a combination of the admixture of their ancestors Taínos with Europeans and Africans. Shovel-shaped incisors are a common trait among Taínos’ skeletons and are still present in the Puerto Rican population. It is a phenotypic trait derived from its ancestors in Asia, and has been almost exclusive to that population for thousands of years. It has been reported that a SNP in Ectodysplasin A-receptor (EDAR), rs3827760, is a genetic determinant for the phenotype but it might not be the only one. In the present study we aimed to find other SNPs that are also determinant for shovel-shaped incisors, and to examine if the EDAR region has undergone positive selection in the Puerto Rican population. We collected maxillary plaster casts from Puerto Ricans to determine shoveling grade and saliva samples to genotype candidate SNPs. We also genotyped the SNP rs3827760 in 452 representative samples of the Puerto Rican population to determine its allelic frequency. We found that the SNP rs3827760 explains 39% of the variance and that for each copy of the allele 1540C the shoveling grade increases 0.9 in the shoveling grade scale. The allelic frequency for this SNP was 13%, and this allowed us to estimate the Native American frequency in the EDAR locus at 16%. By comparing this estimated frequency to the 15.2% frequency of the Native American throughout the genome as a whole for the same sample set, we conclude that the EDAR region has not been positively selected in Puerto Ricans.Los rasgos fenotípicos de los puertorriqueños son una mezcla de sus ancestros Taínos con europeos y africanos. Los incisivos diente de pala son un rasgo común entre las osamentas de Taínos, y están aún presentes en la población puertorriqueña. Es un rasgo fenotípico derivado de sus ancestros en Asia y ha sido casi exclusivo de esa población por miles de años. Ha sido reportado que un polimorfismo de un nucleótido en el gen Ectodysplasin A-receptor (EDAR), rs3827760, es un determinante genético para este fenotipo pero podría no ser el único. Uno de los objetivos en el presente estudio fue encontrar otros polimorfismos que también sean determinantes para los incisivos diente de pala, y examinar si la región para EDAR ha pasado por una selección positiva en la población puertorriqueña. Colectamos moldes de yeso maxilares de puertorriqueños para determinar el grado de diente de pala y muestras de saliva para genotipar polimorfismos candidatos. También genotipamos el polimorfismo rs3827760 en 452 muestras representativas de la población puertorriqueña para determinar su frecuencia alélica. Encontramos que el polimorfismo rs3827760 explica el 39% de la varianza y por cada copia del alelo 1540C el grado de diente de pala aumenta en un 0.9 en la escala de gradación de pala. La frecuencia alélica para este polimorfismo fue 13%, lo que permite estimar la frecuencia indígena en el locus de EDAR en 16%. Al comparar este porciento con la frecuencia indígena global para la misma muestra, que fue 15.2%, concluimos que la región de EDAR no ha sido seleccionada positivamente entre los puertorriqueños.201

Polymorphisms influencing the shovel-shaped incisors phenotype in Puerto Rico

Puerto Ricans phenotypic traits are a combination of the admixture of their ancestors Taínos with Europeans and Africans. Shovel-shaped incisors are a common trait among Taínos’ skeletons and are still present in the Puerto Rican population. It is a phenotypic trait derived from its ancestors in Asia, and has been almost exclusive to that population for thousands of years. It has been reported that a SNP in Ectodysplasin A-receptor (EDAR), rs3827760, is a genetic determinant for the phenotype but it might not be the only one. In the present study we aimed to find other SNPs that are also determinant for shovel-shaped incisors, and to examine if the EDAR region has undergone positive selection in the Puerto Rican population. We collected maxillary plaster casts from Puerto Ricans to determine shoveling grade and saliva samples to genotype candidate SNPs. We also genotyped the SNP rs3827760 in 452 representative samples of the Puerto Rican population to determine its allelic frequency. We found that the SNP rs3827760 explains 39% of the variance and that for each copy of the allele 1540C the shoveling grade increases 0.9 in the shoveling grade scale. The allelic frequency for this SNP was 13%, and this allowed us to estimate the Native American frequency in the EDAR locus at 16%. By comparing this estimated frequency to the 15.2% frequency of the Native American throughout the genome as a whole for the same sample set, we conclude that the EDAR region has not been positively selected in Puerto Ricans.Los rasgos fenotípicos de los puertorriqueños son una mezcla de sus ancestros Taínos con europeos y africanos. Los incisivos diente de pala son un rasgo común entre las osamentas de Taínos, y están aún presentes en la población puertorriqueña. Es un rasgo fenotípico derivado de sus ancestros en Asia y ha sido casi exclusivo de esa población por miles de años. Ha sido reportado que un polimorfismo de un nucleótido en el gen Ectodysplasin A-receptor (EDAR), rs3827760, es un determinante genético para este fenotipo pero podría no ser el único. Uno de los objetivos en el presente estudio fue encontrar otros polimorfismos que también sean determinantes para los incisivos diente de pala, y examinar si la región para EDAR ha pasado por una selección positiva en la población puertorriqueña. Colectamos moldes de yeso maxilares de puertorriqueños para determinar el grado de diente de pala y muestras de saliva para genotipar polimorfismos candidatos. También genotipamos el polimorfismo rs3827760 en 452 muestras representativas de la población puertorriqueña para determinar su frecuencia alélica. Encontramos que el polimorfismo rs3827760 explica el 39% de la varianza y por cada copia del alelo 1540C el grado de diente de pala aumenta en un 0.9 en la escala de gradación de pala. La frecuencia alélica para este polimorfismo fue 13%, lo que permite estimar la frecuencia indígena en el locus de EDAR en 16%. Al comparar este porciento con la frecuencia indígena global para la misma muestra, que fue 15.2%, concluimos que la región de EDAR no ha sido seleccionada positivamente entre los puertorriqueños.201

After an initial Hermansky–Pudlak syndrome clinical diagnosis, molecular testing reveals variants for oculocutaneous albinism type 1B: A case report

Abstract Background Albinism is a heterogeneous condition in which patients present complete absence, reduction, or normal pigmentation in skin, hair and eyes in addition to ocular defects. One of the heterogeneous forms of albinism is observed in Hermansky–Pudlak syndrome (HPS) patients. HPS is characterized by albinism and hemorrhagic diathesis due to the absence of dense bodies in platelets. Methods In this report, we describe a case of a pair of Puerto Rican siblings with albinism that were clinically diagnosed with HPS during childhood. Since they did not harbor the founder changes in the HPS1 and HPS3 genes common in Puerto Ricans, as adults they wanted to know the type of albinism they had. We performed exome sequencing, validation by PCR, and cloning of PCR products followed by Sanger sequencing in the family members. Results We discovered no mutations that could explain an HPS diagnosis. Instead, we found the siblings were compound heterozygotes for 4 variants in the Tyrosinase gene: c.‐301C>T, c.140G>A (rs61753180; p.G47D), c.575C>A (rs1042602; p.S192Y), and c.1205G>A (rs1126809; p.R402Q). Our results show that the correct diagnosis for the siblings is OCA1B. Conclusion Our study shows the importance of molecular testing when diagnosing a rare genetic disorder, especially in populations were the disease prevalence is higher

V Congreso de educación salesiana. Asociatividad juvenil y transformación socioeducativa para el desarrollo sostenible 15-16-17 noviembre 2022

La asociatividad juvenil es uno de los pilares fundamentales de la labor educativa en la Universidad Politécnica Salesiana. El tema fue protagónico durante el V Congreso de Educación Salesiana. En él se discutieron los efectos de la asociatividad juvenil en la transformación socioeducativa, considerando el aumento de desigualdades y vulnerabilidades en el ámbito educativo, especialmente tras la pandemia, que ha afectado gravemente a la juventud en América Latina y el Caribe. Las ponencias publicadas en este volumen abordan el tema y sus consecuencias, como el aumento del abandono escolar y el desempleo juvenil, a la vez que plantean temas de incidencia del sistema preventivo, la formación ética, ecológica y espiritual y el uso de herramientas tecnológicas en el ámbito educativo

Drosophila muller f elements maintain a distinct set of genomic properties over 40 million years of evolution.

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu