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Biomedical subjects

W Schleger

Publications and source records attributed to W Schleger.

At least 37 records · Page 2Linked to original sources
PubMed1987

Offspring of a trisomic cow.

A cow, trisomic for chromosome 22, became pregnant and gave birth to a karyotypically normal and healthy calf. Thus, a second example of reproductive capability in autosomal trisomies in mammals, in addition to trisomy 21 in man, is provided.

Animals↗
PubMed1987

An extended chicken karyotype, including the NOR chromosome.

Chicken chromosomes were identified up to No. 18 by a sequential counterstain-enhanced fluorescence technique. A heterochromatin characterization of macro- and microchromosomes was performed; in general, the microchromosomes were GC-rich, but with a high degree of variation. The NORs are localized on chromosome No. 17.

Animals↗
PubMed1986

Species-specific non-expression of ribosomal RNA genes in a mammalian hybrid, the mule.

The expression of nucleolus organizer activity in diploid cells was investigated in a model system for mammalian hybrids, the horse-ass cross (mule), by means of sequential Ag-NOR and chromomycin A3/distamycin A-DAPI (CDD) staining in lectin-stimulated peripheral blood lymphocytes (PBL). As a rule we found species-specific non-expression of the horse-derived NOR chromosomes in the mule, whereas the ass-derived NOR chromosomes were active. The results of PBL interphase studies were compatible with the data gained from mitotic metaphase analyses.

Animals↗
PubMed1986

Heterochromatin composition and nucleolus organizer activity in four canid species.

Sequential staining with a counterstain-contrasted fluorescent banding technique (chromomycin A3-distamycin A-DAPI) revealed the occurrence of distamycin A-4,6-diamidino-2-phenylindole (DA-DAPI) staining heterochromatin in the centromeric regions of chromosomes 33, 36, 37, and 38 in the wolf (Canis lupus pallipes) and of chromosomes 13, 16, and 23 in the blue fox (Alopex lagopus). The red fox (Vulpes vulpes) lacked such regions. Staining with DAPI--actinomycin D produced a QFH-type banding pattern with clearcut differences in the staining behaviour of DA-DAPI positive regions between these three canid species. Staining with the fluorochrome D 287/170 did not preferentially highlight any of the DA-DAPI positive regions in any of them. Counterstain-enhanced chromomycin A3 R-banding and studies of nucleolus organizer region location and activity confirmed a close relationship between the karyotype of the wolf and the domestic dog. Few heterochromatic marker bands were encountered in these two species, but heterochromatin polymorphism was evident in the blue fox.

Animals↗
PubMed1986

Genetic characterisation of the mithun (Bos frontalis) and studies of spermatogenesis, blood groups and haemoglobins of its hybrids with Bos indicus.

The mithun (Bos frontalis) and its hybrids with Bos indicus were studied to provide further cytogenetic information which might throw light on the mechanisms of the male hybrid infertility and facilitate the establishment of a stable crossbreed. It was shown that compared with conventional cattle the mithun has a homozygous, species specific 2/27 centric fusion which reduced the diploid chromosome number from 60 to 58. This provided further proof that Robertson translocation-type rearrangements have been the major source of interspecies karyotype differences in the evolution of the Bovidae. In the mithun there was also significant polymorphism between centromeres of non-homologous chromosomes and there was heteromorphism between several homologous chromosomes which could possibly serve as useful genetic markers for breeding programmes. In F1 hybrids spermatogenesis progressed to a relatively advanced stage, without going so far as to produce spermatozoa. In back crosses to B indicus spermatogenesis progressed further so that spermatozoa could be seen, though not as numerous as in normal bulls. In most hybrids there were haemoglobin bands which corresponded either to Hb A or Hb B of cattle but were much wider. It was shown that these were a combination of Hb Mi derived from the mithun and Hb A or Hb B derived from B indicus. In a few hybrids there were only Hb Mi. In these cases Hb Mi had been present in both parents and proved that the dam was not a pure siri. The possible mechanism of hybrid male infertility is discussed including faults in the epistatic gene effect between chromosomes and changes in the degree of association of centromeric regions in interspecies hybrids. It is suggested that additional cytogenetic examination of blood lymphocytes and especially of testicles would help the understanding of the fertility barriers of hybrid males and would make a breeding programme for a stable crossbreed possible.

Animals↗
PubMed1985

Levels of conservation and variation of heterochromatin and nucleolus organizers in the Bovidae.

Chromomycin A3 banding of the mitotic sets of 10 species of Bovidae (cattle, wisent, yak, banteng, gaur, red buffalo, swamp buffalo, sheep, mufflon, and goat) serves to demarcate both centromeric constitutive heterochromatin and R-banding patterns capable of identifying all the chromosomes within a given complement. In all species significant amounts of chromomycin-bright heterochromatin are present at the centromeres of all autosomes, though there was a high degree of intra- and inter-individual variation in the size of the heterochromatic blocks. Marked interspecies differences in the centromeric patterns were evident. The X chromosomes contained appreciable amounts of centromeric heterochromatin only in the two buffaloes. All the animals studied lacked distamycin A - diamidinophenylindole type heterochromatin. AgNO3 staining was applied sequentially to detect the location of active nucleolus organizer regions (NORs). The distribution of NORs was reasonably conservative in most of the species. An exceptional situation was found in the two buffaloes, where only one NOR pair matched with the standard karyotype of the Bovidae.

Animals↗
PubMed1985

A viable calf with trisomy 22.

Karyotyping of eight malformed calves resulted in the detection of trisomy 22 in one calf. This calf had a hernia umbilicalis, a urachus fistula, and slight brachygnathia inferior. This trisomy was not associated with lethality.

Animals↗
PubMed1984

Karyotyping, red blood cell and haemoglobin typing of the mithun (Bos frontalis), its wild ancestor and its hybrids.

In Bhutan in remote parts of the Himalayas the mithun (Bos frontalis) has been used probably for centuries in an ingenious system for crossbreeding with domestic cattle which results in highly profitable hybrid females. The hybrid males are infertile and so far no stable crossbreed has been developed. Genetic analyses reported in this paper support the view that the gaur is the wild ancestor of the mithun. Both have only 58 chromosomes in contrast to 60 in cattle and also different, hitherto undescribed haemoglobins and blood groups which would justify the revision of the present classification of the subfamily Bovinae. If, with the aid of modern genetic methods, a stable crossbreed could be developed, dairy and beef production in Bhutan and many climatically similar areas could benefit greatly. Because of its remarkable size the mithun may, in the hands of enterprising breeders, also make a useful genetic contribution to beef production elsewhere.

Animals↗
PubMed1983

Characterization of the canine karyotype by counterstain-enhanced chromosome banding.

The application of the counterstain-contrasted fluorescent banding technique to canine chromosomes provided an improved capability to highlight specific heterochromatic regions and to produce well defined banding patterns both on mitotic and meiotic chromosomes. Triple staining with chromomycin A3 - distamycin A - DAPI revealed the occurrence of DA - DAPI positive heterochromatin in chromosomes 33, 36, 37, and 38. Pachytene nuclei present more favourable material for the detection of very small amounts of DA - DAPI material than mitotic division stages. Counterstain-enhanced chromomycin R-banding greatly facilitated chromosome identification. A standard R-band karyotype of Canis familiaris is proposed and described in some detail. DAPI - actinomycin D staining produced a QFH-type banding pattern and enhanced differentiation of some polymorphic regions.

Animals↗
PubMed1982

Circulating immune cells and immune complexes in peripheral blood of healthy and of bovine leukemia virus-infected cows and lymphosarcomatous calves.

The peripheral blood (lymphocytes and immune complexes (IC) from 20 healthy cows, 5 healthy calves, 10 bovine leukemia virus-infected cows and 4 lymphosarcomatous calves was investigated using 4 different immunological techniques. A highly significant increase in the percentage of surface immunoglobulin (SIg)-bearing peripheral blood lymphocytes of persistent lymphocytosis-cows could be demonstrated while the percentage was decreased in the lymphosarcomatous calves. Percentages of spontaneous sheep red blood cells(SRBC)-rosettes (E-rosettes) were not elevated. Antibodies to bovine leukemia virus-antigen were detected in the sera (immuno-diffusion test) of all the leukotic cows but not of the lymphosarcomatous calves. Although there seems to be an increased level of IC in the advanced stage, as compared to the beginning of the disease, there was no statistically significant difference in comparison with the control individuals. In the lymphosarcomatous calves as well as in the leukemic cows there was no statistical difference in the IC values between diseased animals and controls.

Animals↗
PubMed1981

The silver-staining technique--a tool for characterizing lymphocyte populations in mammalian peripheral blood.

Nucleolus organizer regions (NORs) of the peripheral blood lymphocytes (PBL) of 9 mammalian species were analyzed by means of a silver-staining procedure. Species-specific NOR patterns were demonstrated. The number of NOR chromosomes was positively correlated with the nucleolar coefficient, and negatively correlated with the relative frequencies of uninucleolar cells in PBL interphase.

Animals↗
PubMed1981

Lectin-induced lymphocyte stimulation in pigs--a kinetic study of NORs.

Early reactions of rRNA-cistrons in lectin-stimulated PBL cultures of domestic pigs are shown. Interphases showing 3 or more clusters of stained areas were attributed mainly to cells after first division. Clear differences are shown between PHA- and ConA-induced NOR-expression patterns compared to the patterns in PW-stimulated cultures.

Animals↗