CTG repeats at the myotonic protein kinase gene in a healthy Chilean population sample.

OBJECTIVES: To study the variability at the myotonic dystrophy protein kinase (DMPK) gene in a Chilean sample of healthy people. DM1 is an autosomal dominant disorder caused by an expansion of a (CTG) repeat at the 3'-UTR of the gene DMPK. Healthy individuals have alleles under 35 repeats and diseased individuals have over 50. METHODS: Genotyping the number of (CTG) repeats at this gene in a sample of healthy Chilean people. RESULTS: Allele frequencies were significantly different from those of other populations. The most frequent allele was with five repeats. The frequency of larger alleles (>18 CTG repeats) was 11%, close to the European frequency (12%) and higher than the Japanese (8%) and Aboriginal Pehuenche samples (8%). CONCLUSIONS: Allelic frequencies in the Chilean sample studied were intermediate between those of the two ancestral populations (European and Pehuenche).

Allele frequencies for 12 autosomal short tandem repeat loci in two Bolivian populations.

Two hundred and sixty unrelated subjects who asked for paternity testing at two Bolivian Laboratories in La Paz and Santa Cruz were studied. The loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, TH01, TPOX, and CSF1PO were typed from blood samples, amplifying DNA by polymerase chain reactions and electrophoresis. Allele frequencies were estimated by simple counting and the unbiased heterozygosity was calculated. Hardy-Weinberg equilibrium was studied and gene frequencies were compared between the two samples. All loci conformed to the Hardy-Weinberg law and allele frequencies were similar in samples from the two cities. The Bolivian gene frequencies estimated were significantly different from those described for Chile and the United States Hispanic-Americans for most of the loci.

Allele frequencies for 12 autosomal short tandem repeat loci in two bolivian populations

Two hundred and sixty unrelated subjects who asked for paternity testing at two Bolivian Laboratories in La Paz and Santa Cruz were studied. The loci D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820, TH01, TPOX, and CSF1PO were typed from blood samples, amplifying DNA by polymerase chain reactions and electrophoresis. Allele frequencies were estimated by simple counting and the unbiased heterozygosity was calculated. Hardy-Weinberg equilibrium was studied and gene frequencies were compared between the two samples. All loci conformed to the Hardy-Weinberg law and allele frequencies were similar in samples from the two cities. The Bolivian gene frequencies estimated were significantly different from those described for Chile and the United States Hispanic-Americans for most of the loci.

DYS19 and DYS199 loci in a Chilean population of mixed ancestry.

The current Chilean population originated from admixture between aboriginal populations (Amerindians) and Spanish conquerors of European origin. Consequently, the unions that gave rise to the Chilean population were chiefly between Spanish males and aboriginal females, and not the converse. To test the hypothesis that the Y chromosome of the Chilean population is mainly of Spanish origin, while the other chromosomes are from mixed (European and aboriginal) origin, we studied the DYS19 and DYS199 loci in two samples. One sample was obtained from a high socioeconomic stratum, while a second sample was from a low stratum. We studied male blood donors (N = 187) from Santiago, the capital of the country. Subjects were typed for the autosomal ABO and Rh (locus D) blood groups, and for the Y-linked DYS19 and the DYS199 loci, reported as Y-chromosome haplotypes. The aboriginal admixture was estimated for each genetic marker. The percentage of aboriginal admixture was 38.17% for the ABO system and 31.28% for the Rh system in the low socioeconomic stratum and 19.22% and 22.5%, respectively, in the high stratum. Y-chromosome haplotype frequencies constructed from the DYS19 and DYS199 loci demonstrated that the main haplotypes were DYS19*14/DYS199 C, as is often the case with many European populations, and DYS19*13/DYS199 C. The aboriginal admixture from Y-haplotype frequencies was estimated to be 15.83% in the low socioeconomic stratum and 6.91% in the high stratum. These values are lower than the values found using autosomal genetic markers, and are consistent with the historical background of the population studied. This study highlights the population genetic consequences of the asymmetric pattern of genome admixture between two ancestral populations (European and Amerindian).

Frequency of the hypervariable DNA loci D18S849, D3S1744, D12S1090 and D1S80 in a mixed ancestry population of Chilean blood donors

Blood donors (N = 150) at San José Hospital (Santiago, Chile) were typed for one VNTR locus (D1S80) and three STR loci (D18S849, D3S1744, D12S1090). A questionnaire was used to determine the socioeconomic level of the donors, because it is known that some genetic markers (e.g., the ABO and Rh groups) are differentially distributed between different socioeconomic strata. This methodology revealed that two of the three socioeconomic strata distinguishable in Santiago were present in our sample of blood donors, with stratum II representing the middle strata and stratum III the low strata. Allele frequency was determined for each locus and socioeconomic stratum, and it was found that the allele distributions of each locus in socioeconomic strata II and III were statistically similar. All loci conformed to the Hardy-Weinberg law and there was no evidence for association between the alleles of the four loci, allelic frequencies being similar to those found in North American Hispanic populations. The results support the view that the analysis of these loci may have useful applications in population genetics as well as in identity tests

Frequency of the hypervariable DNA loci D18S849, D3S1744, D12S1090 and D1S80 in a mixed ancestry population of Chilean blood donors.

Blood donors (N = 150) at San José Hospital (Santiago, Chile) were typed for one VNTR locus (D1S80) and three STR loci (D18S849, D3S1744, D12S1090). A questionnaire was used to determine the socioeconomic level of the donors, because it is known that some genetic markers (e.g., the ABO and Rh groups) are differentially distributed between different socioeconomic strata. This methodology revealed that two of the three socioeconomic strata distinguishable in Santiago were present in our sample of blood donors, with stratum II representing the middle strata and stratum III the low strata. Allele frequency was determined for each locus and socioeconomic stratum, and it was found that the allele distributions of each locus in socioeconomic strata II and III were statistically similar. All loci conformed to the Hardy-Weinberg law and there was no evidence for association between the alleles of the four loci, allelic frequencies being similar to those found in North American Hispanic populations. The results support the view that the analysis of these loci may have useful applications in population genetics as well as in identity tests.

[Study of 3 hypervariable loci in a mixed Chilean population]. / Estudio de tres loci hipervariables en población mixta chilena.

BACKGROUND: Genetic markers are useful to study evolution parameters in populations and to determine kinship. AIM: To characterize three short tandem repeat loci in a sample of Chilean subjects and compare them with Caucasian and Hispanic populations. MATERIAL AND METHODS: Three hundred ninety three unrelated subjects that were sent for genetic studies from courts of justice, were studied. The loci FESFPS, F13A01 and vWA in blood samples, were typified amplifying DNA by polymerase chain reactions. RESULTS: The three studied loci were highly polymorphic. F13A01 and FESFPS were in Hardy-Weinberg genetic equilibrium. A significant excess of heterozygotes was detected for vWA locus. There were no differences in allele frequencies, according to ethnic origins of last names. Allele frequencies for F13A01 and vWA loci were similar to those of Hispanic populations of Unites States and FESFPS loci was different. CONCLUSIONS: All three loci had a high efficiency for genetic identification tests according to the estimated a priory exclusion probability.

Macroscopic growth of filamentous fungi on solid substrate explained by a microscopic approach.

A quantitative model predicting biomass growth on solid media has been developed. The model takes into account steric interactions between hyphae and tips at the microscopic level (competition for substrate and tip-hypha collisions). These interactions effect a slowing down of the hyphal, population-averaged extension rate and are responsible, at the microscopic level, for the distribution of tip orientations observed at the colony border. At the macroscopic level, a limiting value of the colony radial extension rate is attained. A mathematical model that combines hyphal branching, tip diffusion, and biomass growth was proposed to explain such behavior. Experiments using Gibberella fujikuroi were performed to validate the model; good agreement between experiments and simulations was achieved. Most parameters can be measured by simple image analysis on the peripheral growth zone, and they have clear physical meaning; that is, they correspond to properties of single, leading hyphae. The model can be used to describe two-dimensional (2D) solid media fermentation experiments under varying culture conditions; the model can also be extended to consider growth in three-dimensional (3D), complex geometry substrates.

Paternity analysis when the putative father is missing: first case in Chile.

Genetic marker analysis is a powerful tool for solving paternity-related problems when the putative father is missing. This report describes the first time this approach was employed in Chile to solve such a problem. In the case presented, the alleged father was missing as a result of the political detentions that took place in Chile during 1973. It was not possible to obtain any biological sample from him because he was missing. Thus, the case was resolved by means of genetic marker analysis of the alleged father's close relatives.

[Paternity analysis using four DNA markers amplified by polymerase chain reaction]. / Análisis de paternidad utilizando cuatro marcadores de DNA amplificados mediante la reacción en cadena de polimerasa.

BACKGROUND: DNA typing in forensic analysis is a useful tool to analyze paternity due to its high discrimination power. AIM: To report the experience of Servicio Medico Legal in Santiago, resolving cases of dubious paternity. SUBJECTS AND METHODS: Four highly polymorphic loci, amplified by polymerase chain reactions, were analyzed in 153 cases of uncertain paternity. The paternity index was calculated for each case. RESULTS: The four genetic markers analyzed provided an exclusion probability of 0.933 for the general population in Santiago. Thirty-seven cases were excluded as parents. In 31 cases, the paternity index ranged from 19 to 100, considered as probable paternity and 77 cases had an index of over 100, considered as almost certain paternity. Eight cases had an index between 0.5 and 19, considered as inconclusive. All loci met Hardy-Weinberg expectations and their frequencies were similar to other data from people living in Santiago. CONCLUSIONS: The use of these genetic markers proved to be very useful, reliable and with a high exclusion power for paternity analysis.

Chilean population data on ten PCR-based loci.

Allele frequencies for ten PCR-based loci LDLR, GYPA, HBGG, D7S8, Gc, HLA-DQA1, D1S80, CSF1PO, TPOX and THO1 were determined in unrelated Chileans from Santiago. All loci except HBGG and THO1 meet Hardy-Weinberg expectations. There is little evidence for association of alleles among the ten loci. Only 3 out of 45 pairwise comparisons demonstrated departures from independence. The allelic frequency data are similar to other comparable data.

[Paternity determination in cases of incest using multiallelic loci DNA polymorphisms]. / Análisis de paternidad en casos de incesto, utilizando polimorfismos del ADN de loci multialélicos.

The analysis of genetic markers in man allows to efficiently resolve cases of dubious paternity. Lately, the use of genetic markers derived from DNA analysis allows high exclusion probabilities. A particular case are those consultations whom the progenitors are closely related, in which the criteria to attribute paternity are modified. The present report explains the analysis methods and interpretation of results in situations of doubtful paternity in cases of incest between father and daughter, using monolocus DNA polymorphisms. The method is illustrated through the analysis of four cases seen at the Servicio Médico Legal of Santiago. To be able to determine paternity in these cases of incest, at least three multiallelic loci in which mother and son have different genotypes must be examined.

Molecular cloning and sequence determination of four different cDNA species coding for alpha-subunits of G proteins from Xenopus laevis oocytes.

A cDNA library prepared from Xenopus laevis oocytes in lambda gt10 was screened with a mixture of three oligonucleotide probes designed to detect sequences found in different mammalian genes coding for alpha-subunits of G-proteins. In addition to a clone coding for a G alpha o-type subunit previously reported [(1989) FEBS Lett. 244, 188-192] four additional clones have been found coding for different G alpha protein subunits. By comparison with mammalian alpha-subunits, these oocyte cDNAs correspond to two closely related G alpha s-1a, to a G alpha i-1 and to a G alpha i-3 species. The derived amino acid sequences showed that both G alpha s species contain 379 residues, corresponding to the short species without the serine residue and with a calculated Mr of 42720. The G alpha i-1 gene encodes a 354 amino acid protein with an Mr of 39,000 and the G alpha i-3 encodes an incomplete open reading frame of 345 residues, lacking the first 9 amino acid residues at the NH2 terminus. All these G alpha-subunits showed high identity with their respective mammalian counterparts (75-80%), indicating a great degree of conservation through the evolution and the important cellular regulatory function that they play.

Molecular cloning and sequence determination of a cDNA coding for the alpha-subunit of a Go-type protein of Xenopus laevis oocytes.

Xenopus laevis oocytes are cells ideally suited to the study of signal transduction and of the G-proteins that are involved in this process. A X. laevis cDNA library in lambda gt10 has been screened with a mixture of three oligonucleotide probes designed to detect sequences found in various mammalian alpha-subunits of G-proteins. One of these clones has been purified through tertiary screening and the DNA insert has been sequenced. This clone was found to include the total sequence coding for a 354 amino acid protein that is 89% identical to the sequence of alpha-subunit of rat Go. The differences with the mammalian protein were clustered in amino acids 290-315, which have been postulated to define the region interacting with the receptor and effector molecule. The homology with the alpha-subunits of other mammalian G-proteins is lower (65-70% to Gi and 42% to Gs). On this basis, this clone can be classified as Go-like.