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W Engel

Publications and source records attributed to W Engel.

At least 145 records · Page 8Linked to original sources
PubMed1992

The genes for protamine 1 and 2 (PRM1 and PRM2) and transition protein 2 (TNP2) are closely linked in the mammalian genome.

The genes for two protamines (PRM1 and PRM2) and for two transition proteins (TNP1 and TNP2) have been characterized in several mammalian species. In the human, boar, and bull, the genes for PRM1, PRM2, and TNP2 are closely linked over a stretch of DNA 13-15 kb long. Although similar data are not yet available for the mouse and rat, our results suggest that the three genes are similarly linked in these species. The gene for TNP1 in all species studied is located on another chromosome.

Animals↗
PubMed1992

Characterization of four genes encoding basic proteins of the porcine spermatid nucleus and close linkage of three of them.

Protamines and transition proteins (TNP) play a major role during spermatogenesis and spermatid differentiation. By screening a porcine genomic library with the corresponding cDNAs, we isolated the genomic clones for porcine protamines 1 and 2 as well as for transition proteins 1 and 2. Analysis and comparison of exon-intron structure, 5' and 3' untranslated regions and transcription start points revealed features common to their counterparts in other mammals. In contrast to TNP2 the gene for TNP1 is well conserved among species, indicating a non species-specific function in the chromatin condensation of the spermatid nucleus. Furthermore, Southern blot hybridization of digested phage DNA demonstrated close linkage between both protamine genes and the gene for transition protein 2 in a 13-kb stretch of DNA. Our observations support the hypothesis that these genes may have evolved by gene duplication.

Amino Acid Sequence↗
PubMed1992

Nucleotide sequence and exon-intron structure of the bovine transition protein 1 gene.

The nucleotide sequence and exon-intron structure of the bovine transition protein 1 gene was determined. It consists of 2 exons (E1, 139 bp; E2, 29 bp) and a single intron (220 bp). The position of the transcription initiation site was determined 30 nucleotides upstream of ATG. TAAATA- and CAAT-boxes were found 60 and 121 bp upstream of the ATG-translation start point, respectively. It was observed that transition protein 1 is highly conserved in mammals at the nucleotide as well as at the amino acid level.

Amino Acid Sequence↗
PubMed1992

Expression of a histone H1 gene (H1.1) in human testis and Hassall's corpuscles of the thymus. Expression of a histone H1 gene (H1.1).

The expression of a H1 gene (H1.1) was studied in several human tissues. Northern blot analysis revealed that this gene is expressed in testis and thymus, but not in other human tissues like liver, spleen, lung, brain, thyroid gland and skin fibroblasts. Furthermore in situ hybridization on tissue sections revealed a cell type specific expression of histone H1.1 gene in the Hassall's corpuscles of the thymus.

Gene Expression↗
PubMed1991

Rat sperm acrosin: cDNA sequence, derived primary structure and phylogenetic origin.

Rat preproacrosin primary structure as predicted from a 1431 nucleotide (nt) cDNA indicates that the molecule is synthesized as a preproenzym consisting of a putative 19 amino acid signal sequence, a 23 amino acid light chain and finally a 395 amino acid heavy chain. Functional domains like the catalytic triad (His-70, Asp-124, Ser-222) are highly conserved not only between the available acrosin primary structures of different mammals but also in comparison with other serine proteinases. Number of amino acid exchanges and the degree in amino acid identity between the different serine proteinases and rat acrosin leads to the assumption that acrosin is one of the early descendants within the phylogenetic tree of the serine proteinase superfamily.

Acrosin↗
PubMed1991

Subzonal microinjection of mouse spermatozoa: insufficient sperm motility might induce phagocytosis.

Acrosome-reacted CB6F1 mouse spermatozoa with slight flagellar motility were microinjected under the zona pellucida of CB6F1 mouse oocytes. Electron microscopy revealed the presence of swollen and decondensed sperm heads in the oocyte cytoplasm. Sixty-one percent of the microinjected oocytes reached a morphologically apparent two-cell stage, but chromosomal analysis demonstrated only haploid chromosomal complements in all cases. The exposure of microinjected oocytes to suspensions of spermatozoa of mice homozygous for a 2,4 reciprocal translocation resulted in normal fertilization and embryonic development with a maternally as well as a paternally derived haploid genome. Identical results were obtained with oocytes microinjected with medium and subjected to in vitro fertilization thereafter. Thus it can be suggested that the microinjected spermatozoa with insufficient flagellar motility are incorporated into the oocyte cytoplasm by phagocytosis. These spermatozoa do not induce a polyspermy block but induce the oocyte to parthenogenetic development.

Animals↗
PubMed1991

Detection of human spermatid-specific transcripts in peripheral blood lymphocytes of males and females.

We describe the detection of ectopic ("illegitimate") transcripts of the proacrosin and protamine 2 genes, which are specific for human spermatogenesis, in non-cultured peripheral blood lymphocytes. After specifically-primed reverse transcription of total lymphocyte RNA, these rare transcripts can be directly visualised after two rounds of polymerase chain reaction with nested primers. Sequence and restriction analyses of the corresponding fragments have confirmed that transcripts of proacrosin and protamine 2 are present in the lymphocytes not only of males, but also of adult females.

Acrosin↗
PubMed1991

Acrosin, the peculiar sperm-specific serine protease.

The sperm enzyme acrosin has long been known as one of the key enzymes in the mammalian fertilization process. Elucidation of primary structures of preproacrosin from various species have allowed a deeper insight into the structural organization and the complex evolution of the sperm proteinase acrosin. In addition to the typical elements of serine proteases, the acrosin molecule possesses one novel domain that might convey DNA-binding properties.

Acrosin↗
PubMed1991

Physical mapping of two Xp markers DXS16 and DXS143.

Lymphocyte karyotyping of an infant girl with the clinical features of microphthalmia, iridoschisis, goiter, hip joint dysplasia, labium synechia and craniotabes revealed an Xp deletion. The lymphocyte karyotypes of the parents were normal. Bromodeoxyuridine incorporation studies showed that, in 42 out of 43 metaphases, the deleted X chromosome was late replicating. In one metaphase, the normal X chromosome was observed to be allocyclic. Using DNA markers from the Xp22 region, the breakpoint was assigned distal to DXS16 (pXUT23) and proximal to DXS143 (dic56). Dosage intensity measurements confirmed that the STS gene and the DNA marker DXS31 were involved in the deleted area. Restriction fragment length polymorphism analysis revealed that the paternally derived X-chromosome was deleted.

Abnormalities, Multiple↗
PubMed1991

Historical perspective and current trends in emission microscopy, mirror electron microscopy and low-energy electron microscopy. An introduction to the proceedings of the Second International Symposium and Workshop on Emission microscopy and Related Techniques.

Emission microscopes and related instruments comprise a specialized class of electron microscopes that have in common an acceleration field in combination with the first stage of imaging (i.e., an immersion objective lens, also called a cathode lens or emission lens). These imaging techniques include photoelectron emission microscopy (PEEM or PEM), electron emission induced by heat, ions, or neutral particles, mirror electron microscopy (MEM), and low-energy electron microscopy (LEEM), among others. In these instruments the specimen is placed on a flat cathode or is the cathode itself. The low-energy electrons that are emitted, reflected, or backscattered from the specimen are first accelerated and then imaged by means of an electron lens system resembling that of a transmission electron microscope. The image is formed in a parallel mode in all of the above instruments, in contrast to the image in scanning electron microscopes, where the information is collected sequentially by scanning the specimen. A brief history and introduction to emission microscopy, MEM, and LEEM is presented as a background for the Proceedings of the Second International Symposium and Workshop on this subject, held in Seattle, Washington, August 16-17, 1990. Current trends in this field gleaned from the presentations at that meeting are discussed.

China↗
PubMed1991

Mouse proacrosin gene: nucleotide sequence, diploid expression, and chromosomal localization.

Acrosin is a serine proteinase located in the acrosome of the sperm in a zymogen form, proacrosin. As deduced from the cDNA sequences of human, boar, and mouse proacrosin, the enzyme is synthesized as a preproenzyme, preproacrosin, which contains a hydrophobic leader sequence of 15 to 18 amino acid residues. We have isolated the gene coding for mouse proacrosin from a mouse cosmid library, using cDNA clones as probes. The gene comprises six exons, and one of the five introns is located in the 5'-untranslated region. The transcription initiation site of the preproacrosin mRNA could be assigned to the residue T, 581 nucleotides upstream of the translation initiation codon ATG, with primer extension analysis. TATA and CAAT boxes could be identified at positions -26 and -97, respectively. Similar to other serine proteases, the coding sequence encompasses five exons and the three active-site residues His, Asp, and Ser are encoded by three different exons (E2, E3, E5). The proline-rich domain, which is a characteristic feature of the proacrosin polypeptide, is encoded in exon 5 with the serine active-site residue. The gene is located on chromosome 15 of the mouse genome, bands E/F, and is a member of a syntenic group that was mapped on human chromosome 22, q13-qter. During spermatogenesis the proacrosin gene in the mouse is expressed diploid, in contrast to a haploid expression observed in bull, boar, and rat.

Acrosin↗
PubMed1991

Chromosomal assignment of four rat genes coding for the spermatid-specific proteins proacrosin (ACR), transition proteins 1 (TNP1) and 2 (TNP2), and protamine 1 (PRM1).

The genes for proacrosin, protamines, and transition proteins are exclusively expressed in haploid spermatogenic cells. From the analysis of mouse x rat cell hybrids which segregate rat chromosomes, the rat gene for proacrosin (ACR) was assigned to chromosome 7, that for transition protein 1 (TNP1) to chromosome 9, and the genes for transition protein 2 (TNP2) and protamine 1 (PRM1) to chromosome 10.

Acrosin↗
PubMed1991

Characterization of a gene encoding a basic protein of the spermatid nucleus, TNP2, and its close linkage to the protamine genes in the bull.

During elongation and condensation of the spermatid nucleus, histones are replaced by spermatid-specific transition proteins (TNP). TNP1 is well characterized at the cDNA and at the genomic level and was found to be highly conserved during mammalian evolution (similarity between 83 to 98%). We here describe for the first time the nucleotide sequence and organization of the gene for TNP2. The gene was isolated from a bull cosmid library and was found to contain a single intron of 910 bp. The coding sequence consists of 390 bp and has a similarity of about 70% to that of the TNP2 cDNAs of mouse and rat. At the basis of amino-acid sequences, the bull TNP2 is 14 and 15 amino acids longer than that of mouse and rat, respectively, and the similarity is only 45% between bull and mouse and 42% between bull and rat. However, the evolutionary divergence has not occurred at the cost of basic amino acids which are of functional importance in DNA-protein interaction in the condensing spermatid nucleus. The TNP2 gene is closely linked to the protamine genes in the bull genome.

Aging↗
PubMed1991

Exon-intron structure and nucleotide sequence of the rat proacrosin gene.

The nucleotide sequence and exon-intron organization of the proacrosin gene was determined. It consists of 6 exons and 5 introns of which one is located in the 5' untranslated region. The transcription initiation site was determined at position 471 (564 nucleotides upstream of ATG), TATA- and TAAT-boxes were found 588 and 656 bp upstream of the ATG-translation start point, respectively.

Acrosin↗
PubMed1990

Nucleotide sequence and exon-intron organization of the human proacrosin gene.

Acrosin is a serine proteinase and located in a zymogen form, proacrosin, in the acrosome of the sperm. As deduced from the cDNA sequences for human and boar proacrosin, the enzyme is synthesized as a preproenzyme, preproacrosin, which contains a hydrophobic leader sequence. Using cDNA clones as probes, we have isolated the gene coding for human proacrosin from a human leucocyte genomic library and a human cosmid library, respectively. The gene contains four introns between 0.2 kb--4.5 kb in length. Similar to other serine proteinases, the coding sequence of the preproacrosin gene is spread over all the five exons of the gene and the three activesite residues His, Asp and Ser are encoded by three different exons. According to the exon-intron structure, preproacrosin is suggested to be closely related to the serine proteinase subfamily containing trypsin and kallikrein. However, the light chain of proacrosin seems to be similar to that of chymotrypsin. The coding of the serine active-site residue together with the proacrosin-specific proline-rich domain in one exon, namely exon E5, let us assume that the nucleotide sequence for the proline-rich domain was generated during evolution by intron-exon transfer from a foreign gene with subsequent intron excision. By primer extension analysis, the transcription initiation site of the preproacrosin mRNA could be assigned to the residue C at -74 nucleotides upstream from the translation initiation codon ATG. In contrast to most other eucaryotic genes, including the known testis-specific genes, typical TATA and CAAT box sequences in convential distances from the 5' end of the transcription start site could not be evaluated in the proacrosin gene.

Acrosin↗