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C Gehrig

Publications and source records attributed to C Gehrig.

24 records · Page 2Linked to original sources
PubMed1997

Chromosome Y microsatellites: population genetic and evolutionary aspects.

By means of a multicenter study, a large number of males have been characterized for Y-chromosome specific short tandem repeats (STRs) or microsatellites. A complete summary of the allele frequency distributions for these Y-STRs is presented in the Appendix. This manuscript describes in more detail some of the population genetic and evolutionary aspects for a restricted set of seven chromosome Y STRs in a selected number of population samples. For all the chromosome Y STRs markedly different region-specific allele frequency distributions were observed, also when closely related populations were compared. Haplotype analyses using AMOVA showed that when four different European male groups (Germans, Dutch, Swiss, Italians) were compared, less than 10% of the total genetic variability was due to differences between these populations. Nevertheless, these pairwise comparisons revealed significant differences between most population pairs. Assuming a step-wise mutation model and a mutation frequency of 0.21%, it was estimated that chromosome Y STR-based evolutionary lines of descent can be reliably inferred over a time-span of only 1950 generations (or about 49,000 years). This reduces the reliability of the inference of population affinities to a historical, rather than evolutionary time scale. This is best illustrated by the construction of a human evolutionary tree based on chromosome Y STRs in which most of the branches connect in a markedly different way compared with trees based on classical protein polymorphisms and/or mtDNA sequence variation. Thus, the chromosome Y STRs seem to be very useful in comparing closely related populations which cannot probably be separated by e.g. autosomal STRs. However, in order to be used in an evolutionary context they need to be combined with more stable Y-polymorphisms e.g. base-substitutions.

Biological Evolution↗
PubMed1997

Assembly of A- and B-type lamins studied in vivo with the baculovirus system.

We have expressed an A-type lamin (Xenopus lamin A), a probable A-type lamin (Drosophila lamin C), two B-type lamins (Xenopus lamin LI, Drosophila lamin Dmo), and two mutants of Xenopus lamin A in Sf9 cells. All proteins were synthesized at high levels resulting in formation of paracrystals with an axial repeat of 18.5-20.0 nm by A-type lamins; in contrast B-type lamins assembled into aggregates with a fibrillar ultrastructure. Of the four wild-type proteins analyzed only lamin Dmo was found in the nuclear compartment of Sf9 cells in association with the lamina whereas the three other lamins assembled into polymers localized in the cytoplasm as well as the nucleoplasm. The Xenopus lamin A mutant lacking the complete carboxy-terminal tail assembled in the cytoplasm into long filament bundles consisting of fibrils of less than 6 nm diameter. In vitro the non-helical amino-terminal head domain of lamins is required for the formation of 'head-to-tail' polymers. A lamin A mutant lacking this domain could be efficiently extracted from Sf9 cells with physiological buffers containing Triton X-100, demonstrating the importance of this domain for lamin assembly in vivo.

Animals↗
PubMed1997

Effects of toluidine blue and destaining reagents used in sexual assault examinations on the ability to obtain DNA profiles from postcoital vaginal swabs.

Toluidine blue is an important tool to detect and document genital and perianal injuries following sexual assault. Application of toluidine blue dye and its subsequent removal from unstained areas by means of a destaining reagent, such as diluted acetic acid or a lubricant has been shown to increase the detection rate of posterior fourchette lacerations from 16% to 40% in adult rape victims. Currently, limited information on toluidine blue positive findings in sexually active control groups imposes some limitation on the interpretation of these injuries. Because injuries could otherwise be attributed to improper handling of an examination speculum or the improper insertion of the examining finger, the toluidine blue test should be performed prior to any digital or speculum examination and thus prior to the collection of forensic evidence. For forensic DNA identity testing, it becomes pertinent to determine whether toluidine blue and the destaining reagents used in a sexual assault examination have an adverse effect on the recovery of high molecular weight DNA from postcoital vaginal swabs and thereby have an impact on restriction fragment length polymorphism (RFLP) analysis or PCR-based tests. It is known that some of the lubricants used can have a destructive effect on sperm motility. In order to investigate the potential effects, postcoital vaginal swabs were taken 6 h after sexual intercourse and exposed directly to 1% toluidine blue in aqueous solution, 1-10% acetic acid, and various surgical and vaginal lubricants. Subsequently, the DNA was isolated and DNA identity typing (RFLP and PCR-based) was performed. The results demonstrate, that these reagents have no negative effect on the ability to obtain DNA profiles, either RFLP or PCR-based, from shallow and deep vaginal swabs. The quantity and quality of extractable high molecular weight DNA obtained was comparable with that from uncontaminated postcoital vaginal swabs. RFLP patterns and PCR-based typing results on the D1S80, HUMTH01, TPOX, and CSF1PO loci were consistent with the uncontaminated control swabs and the corresponding whole blood samples of the donors. Therefore, evidentiary material inadvertently contaminated with these reagents can be successfully typed.

Adult↗
PubMed1996

HLA-DQA1 subtyping data in the Swiss population.

Allele- and genotype frequencies for the polymerase chain reaction-based DNA genetic marker HLA-DQA1 were determined previously in a Swiss sample population (n = 200). In this study we subtyped the allele 4 in the same Swiss Caucasian population sample (distinguishing the 4.1 allele from the 4.2 and 4.3 alleles) using the AmpliType PM+ DQA1 PCR Amplification and Typing Kit. No deviations from Hardy-Weinberg equilibrium could be observed. The power of discrimination (Pd) of the HLA-DQA1 locus without subtyping the 4 allele for Swiss Caucasians was 0.931, when subtyping the 4 allele the value is 0.938. The frequency data can be used in forensic analyses to estimate the frequency of a HLA-DQA1 profile in the Swiss population.

Alleles↗
PubMed1991

Dynamical search for bis-penicillamine enkephalin conformations.

Quenched molecular dynamics is used as a conformational search technique for the constrained cyclic analog [D-Pen2,D-Pen5]enkephalin (DPDPE) in a continuum solvent. The results show a Gaussianlike distribution of conformations as a function of energy, unlike the distributions found for simple liquids which have sharp bands for different crystal forms and broad glasslike states are found. The lowest energy conformers have structural features in common with those obtained from constrained searches based on energy minimization. (Hruby, V. J., L-.F. Kao, B. M. Pettitt, and M. Karplus. 1988. J. Am. Chem. Soc. 110:3351-3359). Many of the low energy configurations are amphiphilic with the carbonyl groups on one surface and the hydrophobic groups on the other. This supports the conclusions from the previous modeling study, which yielded amphiphilic structures as the most probable conformations of DPDPE when NOE data were included.

Calorimetry↗