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Contents The mammalian mitochondrial genome encodes for 37 genes which are involved in a broad range of cellular functions. The mitochondrial DNA (mtDNA) molecule is commonly assumed to be inherited through oocyte cytoplasm in a clonal manner, and apparently species-specific mechanisms have evolved to eliminate the contribution of sperm mitochondria after natural fertilization. However, recent evidence for paternal mtDNA inheritance in embryos and offspring questions the general validity of this model, particularly in the context of assisted reproduction and embryo biotechnology. In addition to normal mt DNA haplotype variation, oocytes and spermatozoa show remarkable differences in mtDNA content and may be affected by inherited or acquired mtDNA aberrations. All these parameters have been correlated with gamete quality and reproductive success rates. Nuclear transfer (NT) technology provides experimental models for studying interactions between nuclear and mitochondrial genomes. Recent studies demonstrated (i) a significant effect of mtDNA haplotype or other maternal cytoplasmic factors on the efficiency of NT; (ii) phenotypic differences between transmitochondrial clones pointing to functionally relevant nuclear–cytoplasmic interactions; and (iii) neutral or non-neutral selection of mtDNA haplotypes in heteroplasmic conditions. Mitochondria form a dynamic reticulum, enabling complementation of mitochondrial components and possibly mixing of different mtDNA populations in heteroplasmic individuals. Future directions of research on mtDNA in the context of reproductive biotechnology range from the elimination of adverse effects of artificial heteroplasmy, e.g. created by ooplasm transfer, to engineering of optimized constellations of nuclear and cytoplasmic genes for the production of superior livestock. [ABSTRACT FROM AUTHOR]

Contents Early embryonic development, implantation and maintenance of a pregnancy are critically dependent on an intact embryo-maternal communication. So far, only few signals involved in this dialogue have been identified. In bovine and other ruminants, interferon tau is the predominant embryonic pregnancy recognition signal, exhibiting antiluteolytic activity. However, this is just one aspect of the complex process of embryo-maternal signalling, and a number of other systems are more likely to be involved. To gain a more comprehensive understanding of these important mechanisms, integrated projects involving specialists in embryology, reproductive biotechnology and functional genome research are necessary to perform a systematic analysis of interactions between pre-implantation stage embryos and oviduct or uterine epithelial cells, respectively. State-of-the-art transcriptomic and proteomic technologies will identify reciprocal signals between embryos and their maternal environment and the respective downstream reaction cascades. For in vivo studies, the use of monozygotic twins as recipient animals provides elegant model systems, thus eliminating genetic variability as a cause of differential gene expression. In addition, suitable systems for the co-culture of oviduct epithelial or endometrium cells with the respective embryonic stages need to be established for functional validation of candidate genes potentially involved in the dialogue between embryos and their maternal environment. The knowledge of these mechanisms should help to increase the pregnancy rate following embryo transfer and to avoid embryonic losses. Candidate genes involved in embryo-maternal communication will also be used to define new quality criteria for the selection of embryos for transfer to recipients. Another application is the supplementation of embryotrophic factors or components of embryo-maternal signalling in optimized formulations, such as bioartificial matrices. As a... [ABSTRACT FROM AUTHOR]

Genes determining the bovine erythrocyte antigens were mapped by linkage analysis. In total 9591 genotypes of 20 grandsire families with 1074 sires from a grand-daughter design were elucidated for the genes determining the erythrocyte antigens EAA , EAB , EAC , EAF , EAJ , EAL , EAM , EAN ′, EAR ′, EAS , EAT ′, and EAZ according to standard paternity testing procedures in the blood typing laboratories. Linkage analyses were performed with 248 microsatellite markers, eight SSCP markers and four polymorphic proteins and enzymes covering the 29 autosomes and the pseudoautosomal region of the sex chromosomes. The number of informative meioses for the blood group systems ranged from 76 to 947. Blood group systems EAM and EAT ′ were non-informative. Most of the erythrocyte antigen loci showed significant linkage to a single chromosome and were mapped unequivocally. The genes determining erythrocyte antigen EAA , EAB , EAC , EAL , and EAS were mapped to chromosomes 15, 12, 18, 3, and 21, respectively. Lod-score values ranged from 11.43 to 107.83. Moreover, the EAF system could be mapped to chromosome 17. However, the EAN ′ system previously known as part of the EAF system could be mapped to chromosome 5. In addition, the blood group systems EAJ , the new EAN ′, EAR ′, and EAZ , showed significant linkage to microsatellite markers on various chromosomes and also to other blood groups. The appearance of a single blood group system might be therefore either dependent on the existence of other blood group systems or because of an interaction between different loci on various chromosomes as is known in humans and in pigs. [ABSTRACT FROM AUTHOR]

An important issue in quantitative trait loci (QTL) detection is the use of phenotypic measurement as a dependent variable. Daughter yield deviations (DYDs) as the unit of choice are not available for all traits of interest. The use of de-regressed proofs (DRPFs) of estimated breeding values (EBVs) is an alternative to using daughter yield deviations. The objective of this study was to examine possible differences between DYDs and DRPFs within the use of QTL detection. The pedigree used was part of the granddaughter design of the German QTL effort. Consisting marker maps for livestock species were derived from all available data of 16 German Holstein paternal half-sib families with a total of 872 sires. The number of progeny ranged from 19 to 127. A whole genome scan was performed using weighted and unweighted multimarker regression with DYDs, DRPFs and EBVs as dependent variables for the traits milk, fat and protein yields. Results were compared with respect to the number of QTL detected. A similar number of QTL was detected with DRPFs and DYDs. Also, when dependent variables were weighted according to the variance of the trait, a higher number of QTL was detected at the desired level of significance as compared to using unweighted variables. [ABSTRACT FROM AUTHOR]

Morphologische Ähnlichkeiten zwischen Hausschafrassen und bestimmten Subspezies des Ovis ammon L. 1758 können nicht als zwingender Beweis einer Domestikation der betreffenden Unterart gelten, da Einkreuzungen fremder Wildschafformen in Hausschafe anderer genetischer Herkunft gleichfalls als Ursache von Übereinstimmungen anerkannt werden müssen. Das Heranziehen des maternal vererbten mitochondrialen Genoms eröffnet jedoch die Möglichkeit, heutige Schafrassen – trotz domestikationsbedingter morphologischer Veränderungen und Einkreuzungen u. a. m. – über zahlreiche Generationen bis zu domestizierten Wildschafformen zurückzuverfolgen, sofern diese nicht bereits ausgestorben sind. Mittels haplogruppenspezifischen polymorphen HinfI-Fragmenten von mtDNA und Proteinpolymorphismen bei Tieren verschiedener Bergschafrassen, die maternal als Torfschaf-Abkömmlinge gelten, sowie auch von zur Gruppe der Zaupel gehörenden Waldschafen, sollte geklärt werden, ob der in Europa vorwiegend auftretende Haupt-mtDNA-Haplotyp B mit dem ältesten Hausschaf in Europa, dem Torfschaf (Ovis aries palustris RÜTIMEYER 1862) in Zusammenhang gebracht werden kann. Die Stichproben aus Steinschafbeständen slowenischer und bayerischer Herkunft, weißen und braunen Bergschafen, Brillenschafen aus Bayern und Villnösserschafen weisen einheitlich den Haupt-mtDNA-Haplotyp B auf, wie dies auch bei einem zusätzlich untersuchten Bergamaskerbock der Fall ist. Allerdings wurde in der Waldschafgruppe bei mehr als der Hälfte der Tiere dieser Stichprobe der Typ A festgestellt, was zeigt, daß nicht alle Zaupelschaf – Nachkommen auf die gleiche Wildschaf – Unterart wie die Steinschaf – Nachkommen zurückgeführt werden können. Im Hämoglobin (HBB) kommen die Varianten HBBA und HBBB in allen untersuchten Rassen in ausgeglichener Frequenz vor,... [ABSTRACT FROM AUTHOR]

SummaryThe aim of this paper is to present the construction of a male genetic linkage map as a result of the bovine genome mapping project, which is a common effort of the German cattle breeding federation (ADR), four animal breeding institutes, three blood group laboratories and two animal data and breeding value evaluation centres. In total 20 grandsires with 1074 sires were provided from the German cattle population as reference families, 16 of these paternal half-sib groups are German Holstein families (DH), three are German Simmental (ST) families, and one is a Brown Swiss family (BS). Of 265 markers included in the linkage map, 248 were microsatellite markers, five were bovine blood group systems, eight SSCP markers and four proteins and enzymes. More than 239 000 genotypes resulted from typing the offspring for the respective markers and these were used for the construction of the map. On average 478 informative meioses were provided from each marker of the map. The summarized map length over all chromosomes was 3135.1 cM with an average interval size of 13.34 cM. About 17, 35.7 and 79.1% of the map intervals showed a maximum genetic distance between the adjacent markers of 5, 10 and 20 cM, respectively. The number of loci ranged from two (pseudoautosomal region of the sex chromosome, BTAY) to 15 (BTA23) with an average of 8.8 markers per chromosome. Comparing the length of the chromosomes shows variation from 49.6 cM for BTA26 to 190.5 cM for BTA1 with a mean of 107.7 cM for all autosomes of the genetic linkage map. It was possible to identify chromosomal discrepancies in locus order and map intervals by comparison with other published maps. The map provided sufficient marker density to serve as a useful tool for a scan of segregating quantitative trait loci. [ABSTRACT FROM AUTHOR]

Two mitochondrial DNA molecules which represent major Ovis aries mtDNA haplogroups were cloned and comparatively sequenced to assess the degree of intraspecific variation. A total of 9623 bp that correspond to 58% of both mitochondrial genomes were determined. The control region, the Cytb , ND2, ND3, ND4L, COIII and 12 tRNA genes, including the origin of L-strand replication, were completely characterized. Partial sequence information was obtained from the 12S and 16S rRNA and an additional six protein coding and six tRNA genes. The control regions of the two mtDNAs showed a nucleotide divergence of 4·34% while coding regions differed by 0·44%. The number of sheep coding region substitutions was similar to values observed in intraspecific comparisons of mitochondrial DNAs that represent remote points in genealogical trees of mice and humans. However, replacement substitutions were only observed at ∼30% of the rate in mice and ∼20% of the rate in humans. Nucleotide substitutions with a potential for phenotypic effects were found in the 12S and 16S rRNA and in the ND1 and COIII genes. [ABSTRACT FROM AUTHOR]

Reports on the occurrence of single nucleotide polymorphisms in the pig. Mutations of the alpha-inhibin gene; Comparison of gene sequences derived from wild boar, white Meishan and Pietrain pig breeds; Gene segregation; Chromosomal localization.

Two major Ovis aries mitochondrial DNA (mtDNA) haplogroups have been described in independent studies. HinfI RFLP data of mitochondrial genomes from a large sample set (n = 239) indicated an ancient mutation which differentiates between the two mtDNA types. A completely determined sheep mtDNA sequence was used to assign this mutation to the COI gene and to develop a PCR based assay discriminating between the two phylogenetic branches. The haplogroup specificity of the mutation was further investigated in 26 randomly selected individuals. The animals were unequivocally assigned to their respective groups on the basis of the developed test and their complete control region sequences. The assay provides a rapid and economic means of discriminating between both major domestic sheep mtDNAs. [ABSTRACT FROM AUTHOR]

A cosmid clone containing the complete sheep inhibin subunit beta B gene (INHBB) was assigned to sheep and cattle homologous chromosome bands 2q31-q33 by fluorescence in situ hybridization. The assignment of INHBB in sheep excludes another candidate gene as the site of the FecB mutation.

A total of 419 individuals of four breeds with differing fecundity (Rhoenschaf, Merinolandschaf, East Friesian Milksheep, Romanov) and several wild sheep of the Ovis musimon, O. orientalis, O. vignei and O. ammon groups were screened for genetic variation at the beta A-inhibin (INHBA) locus with up to 11 enzymes. The four breeds differed significantly (P < 0.001) in TaqI allele frequencies. The frequency of the TaqI A allele coincided with the average litter size in each breed.