Further cases of equine sex chromosome abnormalities

Sex chromosome abnormalities have been detected in a further five mares with clinical histories of small ovaries and absent or irregular oestrous cycles. Three mares had 63,XO karyotypes (X monosomy) and two were sex chromosome mosaics with karyotypes of 63,XO/64,XY and 63,XO/64,XX/64,XY respectively. A sex chromosome abnormality (X monosomy) has also been found in a filly where it was suspected because of her short stature.     

Further cases of equine sex chromosome abnormalities

Sex chromosome abnormalities have been detected in a further five mares with clinical histories of small ovaries and absent or irregular oestrous cycles. Three mares had 63,XO karyotypes (X monosomy) and two were sex chromosome mosaics with karyotypes of 63,XO/64,XY and 63,XO/64,XX/64,XY respectively. A sex chromosome abnormality (X monosomy) has also been found in a filly where it was suspected because of her short stature.     

Karyotype evaluation among young horse populations in Poland

Five hundred young horses of the following breeds: Thoroughbred, Silesian, Malopolska, Wielkopolska, Polish Konik, Hutsul, Shetland Pony, Half-bred Anglo-Arabian, Noble Half-bred, Fjord and crosses were cytogenetically investigated. Chromosome preparations obtained after lymphocyte culture were analysed using conventional Giemsa staining and CBG-banding methods. In the case of abnormalities GTG-banding as well as FISH technique were applied. In ten mares different karyotypic abnormalities were diagnosed. One mare showed chromosome chimerism (64,XX/64,XY), eight had sex chromosomal aneuploidy (one in pure line 63,X and seven in mosaic form 63,X/64,XX) and one presented autosomal aneuploidy with mosaicism (64,XX/65,XX,+31). The influence of sex chromosome abnormalities on fertility and the possible utilisation of karyotypic control in any selection programme are discussed.     

INFERTILITY IN THE HORSE ASSOCIATED WITH CHROMOSOMAL ABNORMALITIES

SUMMARY Reproductive failure was studied in 12 phenotypically normal mares (9 Arabian, 3 Quarter horses, 1 Appaloosa and 1 pony). Karyotyping was performed using lymphocytes isolated from peripheral blood by density gradient procedures, followed by standard culture methods for karyotyping. Nine mares had karyotypes of 63,XO; 1 had 63,XO/64,XX; 1 had 63,XO/64,XY and 1 had 64,XY. All mares had small, firm ovaries that when removed and examined from 4 mares, lacked germ cells and consisted of undifferentiated ovarian stroma.     

Chromosome anomalies and infertility in the mare

Nine reproductively normal mares, 25 infertile mares and one set of heterosexual twins were examined cytogenetically using conventional giemsa staining, C-banding and G-banding. It was concluded that G-banding was necessary to identify even gross anomalies. Three (12 per cent) of the infertile mares, but none of the controls, had a chromosomal anomaly. One was 63,XO, one a 63,XO/64,XX mixoploid and one a 64,XY sex reversed male. It is argued that a cytogenetic examination is a useful diagnostic technique but that routine screening of the whole population would be uneconomic.     

XO-gonadal dysgenesis in the mare (report of two cases).

TWo cases of XO-gonadal dysgenesis in the mare are presented. Case No 1 was a pure 63, XO, while Case No 2 was a mosaic with a preponderance of XX cells. The clinical picture was one of phenotypically normal female mares with small uteri and infantile ovaries. The ovaries lacked germ cells, and consisted of stroma only. This study emphasizes the importance of chromosome analysis in providing information concerning the mechanisms involved is some cases of equine infertility.     

Congenital retroflexion of the penis and inguinal cryptorchidism in a presumptive bovine twin with a 60,XY/60,XX/61,XX,+cen chromosome constitution.

Studies were carried out on a yearling Holstein with external genitalia resembling those of a freemartin whose birth and developmental history was unknown. Dissection following slaughter showed testes close to the external inguinal rings, an underdeveloped penis coiled up subcutaneously in the perineum and terminating in a deep fossa at the level of the ischial arch and no evidence of a female genital tract. Chromosome analyses showed 60,XY cells in the blood and 60,XX and 61,XX,+cen cells in other tissues. It is postulated that the animal had a basic 60,XX/61,XX+cen mixoploid chromosome constitution, that the centric fragment functioned as a Y chromosome or as an autosomal modifier of the X chromosome in sex determination which accounted for the animal's Klinefelter syndrome-like abnormalities, and that animal was also twin to a bull which accounted for the presence of 60,XY cells in the blood.     

Application of arm-specific painting probes of horse X chromosome for karyotype analysis in an infertile Hutsul mare with 64,XX/65,XX+Xp karyotype: case report

A 5-year-old infertile Hutsul mare was subjected to cytogenetic analysis. Fluorescence in situ hybridisation (FISH) using the equine Xp and Xq chromosome painting probes was carried out on chromosome preparations obtained after blood lymphocyte culture. These probes were generated by chromosome microdissection and a large number of spreads was analysed (525). The karyotype formula of the analysed mare was 64,XX/65,XX+Xp with the ratio of the two lines being 99.4 and 0.6, respectively. The goal of the study was to apply chromosome microdissection and the FISH technique for cytogenetic diagnostics.     

CYTOGENETICAL STUDIES OF INFERTILE PIGS

Cytogenetical studies were made on 6 infertile pigs. Post-mortem examination of the reproductive organs of 5 of these pigs showed them to be intersexes. Regardless of the degree of gonadal deviation from the normal, chromosome karyotype of cultured peripheral blood lymphocytes, bone marrow, liver and kidney, revealed that 4 of the intersexes had a 38, XX constitution. One intersex exhibited sex chromosome mosaicism (38XX/38XY) in lymphocytes from the peripheral blood and bone marrow and a normal male karyotype (38XY) in cultured liver and kidney cells. The sixth pig, a phenotypically normal boar, also had a 38XX/38XY chromosome constitution.     

Detection of equine X chromosome mosaicism in a mare using an equine X whole chromosome painting probe (WCPP)--a case report

An infertile mare with hypoplastic ovaries was subjected to cytogenetic analysis. Fluorescence in situ hybridisation (FISH) using the equine X whole chromosome painting probe (WCPP) was carried out on a chromosome preparation obtained from blood lymphocyte culture. The number of analysed spreads was high (235) and in the X chromosome aneuploidy in mosaic form was diagnosed. The karyotype formula was 63,X / 64,XX / 65,XXX. The ratio of the three lines was 15%, 82% and 3%, respectively. The application of the FISH technique with WCPP is discussed.     

Repeated Early Embryonic Loss in a Thoroughbred Mare with a Chromosomal Translocation [64,XX,t(2;13)]

Peripheral blood samples from a 13-year-old Thoroughbred mare were submitted for chromosome analysis. The mare had a poor reproduction record only producing four live foals during her 10 years as a broodmare. She had remained barren or experienced early embryonic loss in the other 6 years. Chromosomal analysis revealed the mare carried a rare nonreciprocal translocation involving chromosomes 2 and 13 [64,XX,t(2;13)]. Fluorescence in situ hybridization with probes specific for horse chromosomes 2 and 13 were used to confirm the nonreciprocal translocation. Both conventional and molecular cytogenetic techniques are important for identifying and characterizing chromosomal abnormalities in horses with poor reproductive performance, particularly in mares experiencing repeated early embryonic loss.     

Further Studies on the Cell Populations of an Intersex Horse

An intersex horse exhibiting cell types of different sex chromosome constitution was subjected to further studies in order to determine whether the house was a mosaic or a chimera. Cultures of gonadal tissue and peripheral blood revealed mainly 64/XX and 64/XY cells, the former predominating in both tissues. The frequency of drumstick-bearing poly-morphonuclear neutrophils in the intersex horse was similar to that noted in normal mares. Blood type analysis using 17 naturally occurring agglutinins and hemolysins revealed partial agglutinations with three antibodies for the factors of the A system (anti-A, anti-F, and anti-I), and partial hemolysis with anti-Fr₃ suggesting erythrocyte chimerism probably resulting from intrauterine interchange of blood cell precursors as noted in other domestic animals. On the other hand, the presence of XX and XY cells in cultures of gonads which in our intersex horse were apparently devoid of germ cells, would seem to indicate wholebody chimerism resulting from double fertilization or blastocyst fusion.     

马鹿染色体核型分析

采用常规细胞遗传学分析手段，对青海省西宁动物园饲养的马鹿染色体核型进行分析，结果：马鹿染色体数目为２ｎ＝６８，染色体臂数ＮＦ＝７０（♀）、７１（）；常染色体类型为２条中（Ｍ）着丝粒，６４条近端或端（Ａ）着丝粒；性染色体类型Ｘ为近端（Ａ），Ｙ为近中（ｓＭ）着丝粒；公母鹿核型式为６８，ＸＹ和６８ＸＸ。     

Male tortoiseshell cats in the United Kingdom

A questionnaire concerning the coat colour and sex of cats being vaccinated or neutered was sent to 2585 veterinary practices; 393 (15.2 per cent) were returned and information was obtained about 9816 cats. Of 4598 males, 20 were recorded as tortoiseshell (0.43 per cent). The frequency of the orange gene was 19.7 per cent assuming that male tortoiseshell cats had two X chromosomes. The chromosome complement and/or gonadal histology of 14 male tortoiseshell cats is described. Cytogenetic analysis of 11 animals revealed six with a 38,XX/38,XY complement, two with 39,XXY, two with 38,XX, and one with a 38,XY complement.     

A survey of malformed aborted bovine fetuses, stillbirths and nonviable neonates for abnormal karyotypes.

Postmortem examinations were performed on 30 morphologically abnormal aborted bovine fetuses, stillbirths and nonviable neonates. Fibroblasts from the pericardium were cultured for chromosome analysis. Karyotypes were successfully completed on 18 animals, of which three were trisomic, one was mosaic monosomic and one was chimeric. All aneuploid calves had multisystemic anomalies. Using chromosomal banding techniques, the abnormal karyotypes were determined to be: 61,XY,+27; 61,XX,+21; 61,XY,+?; 59,XY,-?/60,XY; and 60,XX/60,XY. Bacterial contamination or nonviability of tissues prevented the growth of fibroblasts in culture and cytogenetic analysis of the other 12 animals. It was estimated that 2.0% of all late gestation abortuses and stillbirths may have chromosomal abnormalities characterized by aneuploidy. The findings of this study suggest chromosomal abnormalities characterized by aneuploidy are a significant cause of multisystemic anomalies in aborted bovine fetuses and nonviable neonates.     

大通马的核型分析

采用外周血淋巴细胞培养法，对大通马的染色体核型进行了初步分析。结果表明：大通马的染色体数目为２ｎ＝６４，公马核型为６４，ＸＹ；母马为６４，ＸＸ。该品种染色体的数目，形态与我国报道的其它马品种无明显差异。     

Determination of the correlation between stallion's age and number of sex chromosome aberrations in spermatozoa

The aim of this study was a cytogenetic analysis of stallions semen to find sex chromosome aberrations and to determine if there was an association between stallion's age and aberration frequency for the sex chromosomes. Sperm samples were collected from 22 stallions of various age from 3 to 23 years. Multicolour FISH was performed on each sample, using probes for the sex chromosomes and EGFR gene, localized on 4p12 in domestic horse. A total of 26199 sperm cells were analysed (from 1 070 to 1 532 per animal). Among the analysed cells, there were 50.318% with X chromosome, 48.543% with Y chromosome and 1.139% with aberrant chromosomes. The frequency of aberrations was: sex chromosomes nullisomy (0.466%), XY aneuploidy (0.454%), XX disomy (0.146%), YY disomy (0.041%), diploidy (0.024%) and trisomy XXY (0.008%). Additionally there was a correlation between the age of an animal and the frequency of sex chromosome aberration and a significant positive correlation between age and disomy of XY, XX, YY, trisomy of XXY, autosomal disomy was seen. A Correlation between the age of a stallion and the level of nullisomy was negative. The present study demonstrated that FISH technique is a powerful method to identify sex chromosome aberrations in equine spermatozoa and might be very helpful for a breeder during a selection for the best stallion.     

Sex Steroid Levels in XY Males and Sex‐Reversed XX Males,of Rainbow Trout (Oncorhynchus mykiss), During the Reproductive Cycle

In this study, the annual cycle of the gonadal steroids testosterone (T), 11‐ketotestosterone (11‐KT), 17β‐oestradiol (E2) and 17α, 20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) was determined using radioimmunoassay and then compared, for XY males (n = 35) and sex‐reversed XX males (n = 27) rainbow trout, to establish possible endocrinology differences. Both in XY males and sex‐reversed XX males, significant correlation was shown between body weight and T (r = 0.5046 and 0.34078, respectively; p < 0.0001) or KT (r = 0.52494 and 0.43545, respectively; p < 0.0001) concentrations. Plasma androgen levels in XY and sex‐reversed XX males were similar and showed an intense seasonal variation. The highest levels for T and 11‐KT were detected from December to April with a peak in January (51.67 ± 5.11 and 61.95 ± 4.25 ng/ml, for XY males and 57.1 ± 5.82 and 59.27 ± 4.84 ng/ml, respectively, for XX males). In addition, there was a positive correlation (p < 0.0001) between T and 11‐KT levels for XY males (r = 0.7533) and sex‐reversed XX males (r = 0.6019). Concentrations of DHP in XY males also showed seasonal variation with a peak in February (25.18 ± 12.99 ng/ml). However, DHP levels in sex‐reversed XX males were undetectable (<0.1 ng/ml) over the year. Levels of E2 were undetectable through the year in both groups of trout. In conclusion, the androgenic and oestrogenic profiles of sex‐reversed XX males were similar to those observed in XY males. The only difference in the annual gonadal steroid cycle between XY and sex‐reversed XX males was in the DHP profile.     

A 37XO chromosome complement in a kitten

In two kittens from the same litter with spina bifida and meningocoele the phenotypic male was found to have a normal 38XY chromosome complement whilst the phenotypic female had a 37XO chromosome complement. It was concluded that the spina bifida condition was due to the manx ancestry and not to the 37XO karyotype. The possible effect of the XO complement in cats is discussed.