In order to identify polymorphic positions and to determine their frequency in the human mitochondrial D-loop containing region, the mitochondrial DNA (mtDNA) control region of 200 unrelated individuals from Germany were amplified and directly sequenced. Sequence comparison led to the identification of 190 mitochondrial lineages as defined by 202 variable positions. The most frequently occurring lineage comprised 5 individuals, whereas 186 types of D-loop sequences were observed in only one individual. Of the sequences studied 7% are not unique but show at least one counterpart with an identical haplotype. The majority (61%) of the control regions investigated showed between four and eight nucleotide positions deviating from the reference sequence. The maximum number of deviations observed in a single control region was 18. The majority of the variable positions in the D-loop region (88%) are located within three hypervariable regions. Sequence variations are caused by nucleotide substitutions, insertions or deletions. As compared to insertions and deletions, nucleotide substitutions make up the vast majority of the mutations (90%). We have predominantly found transitions (75%) and a significantly lower frequency of transversions (15%) whereas insertions (6%) as well as deletions (4%) are rather rare. Upon sequencing the mitochondrial control region from 200 German Caucasians the genetic diversity was estimated at 0.99. The probability of two randomly selected individuals from a population having identical mtDNA types is 0.6%.

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Two cases are presented in order to emphasize the importance of mitochondrial DNA in forensic medicine. The first case involved a charred body which could not be identified by morphological means because of severe destruction of all tissues. The parallel use of PCR methods using genomic DNA and sequencing of the mitochondrial d-loop region produced unequivocal and reproducible results. In the second case, various parts of a highly decomposed body were investigated. The application of standard PCR methods for genomic DNA proved unsuitable to answer the question whether the body parts belonged to the same body. However, when sequencing of mitochondrial DNA segments amplified from tissue and bone samples was performed, clearly interpretable results were obtained.

The second hypervariable segment of the human mtDNA control region contains a homopolymeric tract of cytidines between nucleotides (nt) 303 and 315, interrupted by a thymidine at position 310, according to the Cambridge reference sequence. By direct sequencing, some individuals show blurred sequence chromatograms in this region which are not caused by a sequencing artefact but by high levels of length heteroplasmy. With respect to this length heteroplasmy ten maternally related individuals and two unrelated probands were examined. The relative proportions of length variants in the homopolymeric tract in selected individuals were determined by cloning and sequencing of multiple independent clones. All ten family members examined were heteroplasmic while the proportions of each genotype varied widely in different individuals. The size of a possible mitochondrial bottleneck during embryonic development of the offspring is discussed with respect to the changes in mitochondrial haplotypes within mother-offspring pairs. Our data are consistent with both slow and rapid segregation of mtDNAs between the generations, which would implicate a tight as well as a wide bottleneck. Therefore, a common bottleneck size in all individuals from this lineage seems to be very unlikely.

Enantiomerentrennung durch Gaschromatographie in wenigen Minuten und bei Temperaturen zwischen 45 und 130°C ist nun für Verbindungen, die keine H‐Brücken bilden können, möglich. An peralkylierten oder partiell alkylierten und acylierten Cyclodextrinen wurden Trennfaktoren zwischen 1.021 und 1.279 erreicht. Die Enantioselektivität der stationären Phase beruht – zumindest teilweise – auf Inclusionseffekten.

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The carcinoembryonic antigen (CEA) family consists of a large group of evolutionarily and structurally divergent glycoproteins. The murine CEACAM9 and CEACAM11-related proteins as well as the pregnancyspecific glycoproteins (PSG) are secreted members of the CEA family which are differentially expressed in fetal trophoblast cell populations during placental development. PSG are essential for a successful pregnancy, possibly by protecting the semiallotypic fetus from the maternal immune system. In contrast, Ceacam10 mRNA, coding for a protein identical in structure with CEACAM11-related proteins, is expressed in the maternal decidua surrounding the implantation site of the conceptus only during early stages of gestation between day 6.5 and day 10.5 postcoitum. To determine its role during murine development, we inactivated Ceacam10. Ceacam10؊/؊ mice developed, like the previously established Ceacam9 ؊/؊ mice, indistinguishably from wildtype littermates with respect to sex ratio, weight gain, and fertility. However, a small but significant reduction of the litter size by 23% was observed in Ceacam10 ؊/؊ matings. Furthermore, combining the Ceacam9 and Ceacam10 null alleles, both located on chromosome 7, by meiotic recombination and subsequent mating of heterozygotes carrying both knockout alleles on one chromosome yielded wild-type and double knockout offspring at the expected Mendelian ratio. Taken together, both Ceacam10 and Ceacam9, alone or in combination, are not essential for either murine placental and embryonic development or for adult life.

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