Structural Abnormalities of the X-chromosome in a Heifer P. Genest and P. Guay*
A three month old pure bred Holstein female was hospitalized with a chronic tympanism syndrome. After examination Structural chromosome abnormalities, some and tentative treatments the condition was of them unusual, were found in 18 (36%) of judged to arise from a dysfunction of the 50 photomicrographed mitotic cells of a blood cardia and the owner decided to send this lymphocyte culture from a three month old calf to slaughter. Among the routine laboratory analyses, Holstein heifer affected with chronic tympaa lymphocyte short-term culture for chronism of the rumen. The aberrations involved more specifically the X-chromosome. The etio- mosome examination was performed on logy of the anomalies and the cause of their heparinized blood collected from the cocX-chromosome propension are of unknown cygian vein. Fifty well-spread metaphases were photomicrographed and three karyonature. types were made. Most of the cells had a normal female complement, 60,XX, nine cells were hypodiploid with various chromosome losses of mechanical origin and RESUME one was tetraploid. Gaps, breaks, fragments and radial configurations were found in 18 cells affecting 24 chromosomes, 11 Les auteurs ont decele des anomalies chro- of these were X-chromosomes (Table I, mosomiques structurales, quelques-unes d'en- Fig. 1). An attempt to make a follow-up tre elles de type inusitk, dans 18 (36%) des analysis of this heifer was unsuccessful 50 cellules mitotiques microphotographiees because the animal had been sent to d'une culture de lymphocytes sanguins prove- slaughter. Chromosome examination of a nant d'une genisse de race Holstein, agee de blood lymphocyte culture from the mother trois mois et souffrant de tympanisme chroni- showed four structural two que. Les anomalies affectaient plus particu- of which, a gap and a abnormalities, chromatid break, lierement le chromosome X. L'etiologie de ces involved the X-chromosome. It was imposaberrations et la cause de leur plus grande sible to study the chromosomes of the frequence sur le chromosome X demeurent heifer's sire. inconnues. Chromosome abnormalities like gap and chromatid break may have little significance since they are usually produced Chromosome abnormalities of the radio- during the cell cultures. Chromosome breaks mimetic type are uncommon on the X-chro- and particularly complex rearrangements mosomes. El-Nahass et al (1) described a such as radial configurations are more mosaic aberration (breaks, deletions and indicative of defective cell activity. Furgaps) within the long arm of the X-chro- thermore, chromosome exchanges such as mosome in a sterile two year old heifer of tri-and quadri-radial figures are exceedingHolstein type. ly rare and found usually in individuals affected with severe systemic conditions or congenital malformations of chromosome *Centre de Recherche en Reproduction animale, Faculte origin. Radial configurations have been de Medecine veterinaire, Universite de Montreal, C.P. found by the senior author in less than 5000, Saint-Hyacinthe, Quebec J2S 7C6. Present address of senior author: Departement de Pathologie, half a dozen blood lymphocyte cultures durFaculte de Mdecine, Universit6 de Laval, Quebec, Quebec G1K 7P4. ing chromosome analysis of over 4000 human beings during the past 15 years. Submitted April 24, 1978. ABSTRACT
110
Can. J. comp. Med.
TABLE I. Chromosome Abnormalities Observed in Cell Preparations from a Short-term Blood Lymphocyte Culture
Chromosomes
54 1
57
1 Cells 1 Gaps Breaks Fragment T.C. 1 Total anomalies "T.C. = triradial configuration -
58 1 2
-
59
60
6 2 -
40 10 6
3
2 18
1
-
2
Fig. 1. A 60,XX chromosome metaphase from the blood configurations (Tr), one of which affecting an X-chromosome, a chromatid break on one autosome (bold arrow), a chromosome break on the second X (bold arrow) and also a chromatid gap (light arrow). Approximate magnification X1400.
lymphocyte culture of the heifer. Note two triradial
German (2) is probably the first to report and discuss the significance of such chromatid exchanges present in culture from five individuals: a patient with Bloom's syndrome, a true hermaphrodite, two patients with macroglobulinemia of Waldenstrom and one patient with carcinoma who had received body irradiation 28 days earlier. In animals, reports are scanty. Halnan (3) describes as triad configuration, associations between two or three autosomes encountered in a low percentage of mitotic cells in cultures from one bull and in three out of 33 of his progeny. No evidence of correlation with disease is found. Structural aberrations affecting prefer-
Volume 43
-
January, 1979
Total X-chromosome Tetraploidy Cells Involved 1 50 11 8 5 2 1 1 1 18 11
entially the X-chromosome is also an unusual observation. In the present cases, abnormalities were found in 10.7% of the X-chromosome while 0.44% only of the autosomes also showed anomalies. El-Nahass et al (1) report the presence of chromatid breaks, deletions and gaps within one long arm of the X-chromosome in 20.8% of metaphases of a two year old heifer which had been slaughtered for sterility. In man, association between structurally aberrant X-chromosome and sterility is well documented but those alterations are of deletion, translocation or isochromosomy type and inheritably transmitted or of de novo origin. The various abnormalities described in the index case are produced usually by external agents such as ionizing radiations, viruses and chemicals but then they are randomly distributed, not selectively as in this case. Furthermore, clinical investigation did not reveal that mutant agents were involved. There is also no evidence that Xchromosome anomalies found in the present case are inherited. If El-Nahass (1) hypothesis is correct, then the selective X-chromosome abnormalities detected in this animal should have been associated with gonadal dysfunction that circumstances did not permit to be ascertained.
REFERENCES
1. EL-NAHASS, E., A. SYRJALLA, H. W. MICHELMANN und S. PAUFLER. Mosaik einer X-Chromosomen-Aberration als wahrscheinliche Ursache der SterilitWt bei einem Rind. Dt. tierarztl. Wschr. 81: 405-406. 1974. 2. GERMAN, J. Cytological evidence for crossing-over in vitro in human lymphoid cells. Science 144: 298-301.
1964. 3. HALNAN, C. R. E. A cytogenetic survey of 1101 Australian cattle of 25 different breeds. Ann. G6n6t. S4I. anim. 8: 131-139. 1976.
A three month old pure bred Holstein female was hospitalized with a chronic tympanism syndrome. After examination Structural chromosome abnormalities, some and tentative treatments the condition was of them unusual, were found in 18 (36%) of judged to arise from a dysfunction of the 50 photomicrographed mitotic cells of a blood cardia and the owner decided to send this lymphocyte culture from a three month old calf to slaughter. Among the routine laboratory analyses, Holstein heifer affected with chronic tympaa lymphocyte short-term culture for chronism of the rumen. The aberrations involved more specifically the X-chromosome. The etio- mosome examination was performed on logy of the anomalies and the cause of their heparinized blood collected from the cocX-chromosome propension are of unknown cygian vein. Fifty well-spread metaphases were photomicrographed and three karyonature. types were made. Most of the cells had a normal female complement, 60,XX, nine cells were hypodiploid with various chromosome losses of mechanical origin and RESUME one was tetraploid. Gaps, breaks, fragments and radial configurations were found in 18 cells affecting 24 chromosomes, 11 Les auteurs ont decele des anomalies chro- of these were X-chromosomes (Table I, mosomiques structurales, quelques-unes d'en- Fig. 1). An attempt to make a follow-up tre elles de type inusitk, dans 18 (36%) des analysis of this heifer was unsuccessful 50 cellules mitotiques microphotographiees because the animal had been sent to d'une culture de lymphocytes sanguins prove- slaughter. Chromosome examination of a nant d'une genisse de race Holstein, agee de blood lymphocyte culture from the mother trois mois et souffrant de tympanisme chroni- showed four structural two que. Les anomalies affectaient plus particu- of which, a gap and a abnormalities, chromatid break, lierement le chromosome X. L'etiologie de ces involved the X-chromosome. It was imposaberrations et la cause de leur plus grande sible to study the chromosomes of the frequence sur le chromosome X demeurent heifer's sire. inconnues. Chromosome abnormalities like gap and chromatid break may have little significance since they are usually produced Chromosome abnormalities of the radio- during the cell cultures. Chromosome breaks mimetic type are uncommon on the X-chro- and particularly complex rearrangements mosomes. El-Nahass et al (1) described a such as radial configurations are more mosaic aberration (breaks, deletions and indicative of defective cell activity. Furgaps) within the long arm of the X-chro- thermore, chromosome exchanges such as mosome in a sterile two year old heifer of tri-and quadri-radial figures are exceedingHolstein type. ly rare and found usually in individuals affected with severe systemic conditions or congenital malformations of chromosome *Centre de Recherche en Reproduction animale, Faculte origin. Radial configurations have been de Medecine veterinaire, Universite de Montreal, C.P. found by the senior author in less than 5000, Saint-Hyacinthe, Quebec J2S 7C6. Present address of senior author: Departement de Pathologie, half a dozen blood lymphocyte cultures durFaculte de Mdecine, Universit6 de Laval, Quebec, Quebec G1K 7P4. ing chromosome analysis of over 4000 human beings during the past 15 years. Submitted April 24, 1978. ABSTRACT
110
Can. J. comp. Med.
TABLE I. Chromosome Abnormalities Observed in Cell Preparations from a Short-term Blood Lymphocyte Culture
Chromosomes
54 1
57
1 Cells 1 Gaps Breaks Fragment T.C. 1 Total anomalies "T.C. = triradial configuration -
58 1 2
-
59
60
6 2 -
40 10 6
3
2 18
1
-
2
Fig. 1. A 60,XX chromosome metaphase from the blood configurations (Tr), one of which affecting an X-chromosome, a chromatid break on one autosome (bold arrow), a chromosome break on the second X (bold arrow) and also a chromatid gap (light arrow). Approximate magnification X1400.
lymphocyte culture of the heifer. Note two triradial
German (2) is probably the first to report and discuss the significance of such chromatid exchanges present in culture from five individuals: a patient with Bloom's syndrome, a true hermaphrodite, two patients with macroglobulinemia of Waldenstrom and one patient with carcinoma who had received body irradiation 28 days earlier. In animals, reports are scanty. Halnan (3) describes as triad configuration, associations between two or three autosomes encountered in a low percentage of mitotic cells in cultures from one bull and in three out of 33 of his progeny. No evidence of correlation with disease is found. Structural aberrations affecting prefer-
Volume 43
-
January, 1979
Total X-chromosome Tetraploidy Cells Involved 1 50 11 8 5 2 1 1 1 18 11
entially the X-chromosome is also an unusual observation. In the present cases, abnormalities were found in 10.7% of the X-chromosome while 0.44% only of the autosomes also showed anomalies. El-Nahass et al (1) report the presence of chromatid breaks, deletions and gaps within one long arm of the X-chromosome in 20.8% of metaphases of a two year old heifer which had been slaughtered for sterility. In man, association between structurally aberrant X-chromosome and sterility is well documented but those alterations are of deletion, translocation or isochromosomy type and inheritably transmitted or of de novo origin. The various abnormalities described in the index case are produced usually by external agents such as ionizing radiations, viruses and chemicals but then they are randomly distributed, not selectively as in this case. Furthermore, clinical investigation did not reveal that mutant agents were involved. There is also no evidence that Xchromosome anomalies found in the present case are inherited. If El-Nahass (1) hypothesis is correct, then the selective X-chromosome abnormalities detected in this animal should have been associated with gonadal dysfunction that circumstances did not permit to be ascertained.
REFERENCES
1. EL-NAHASS, E., A. SYRJALLA, H. W. MICHELMANN und S. PAUFLER. Mosaik einer X-Chromosomen-Aberration als wahrscheinliche Ursache der SterilitWt bei einem Rind. Dt. tierarztl. Wschr. 81: 405-406. 1974. 2. GERMAN, J. Cytological evidence for crossing-over in vitro in human lymphoid cells. Science 144: 298-301.
1964. 3. HALNAN, C. R. E. A cytogenetic survey of 1101 Australian cattle of 25 different breeds. Ann. G6n6t. S4I. anim. 8: 131-139. 1976.
