Idiopathic hypereosinophilic syndrome in 3 Rottweilers.

Three Rottweilers with marked peripheral eosinophilia and infiltration of the liver, spleen, lungs, and bone marrow with eosinophils were diagnosed with idiopathic hypereosinophilic syndrome (IHES). Mean serum immunoglobulin E concentrations were markedly high. On cytogenetic analysis, no evidence of karyotypic abnormalities was found in bone marrow aspirates. Despite an extensive search, no underlying cause for the eosinophilia could be identified. In this study, cytogenetic analysis and measurement of serum IgE concentrations were used to differentiate IHES and eosinophilic leukemia.

Cytogenetic survey of Holstein bulls at a commercial artificial insemination company to determine prevalence of bulls with centric fusion and chimeric anomalies.

OBJECTIVE: To determine prevalence of Holstein bulls with chromosomal anomalies, particularly the 1/21 centric fusion (CF), at a commercial artificial insemination (AI) company in the United States. DESIGN: Cross-sectional cytogenetic prevalence study. ANIMALS: All 606 Holstein bulls at a commercial AI company were cytogenetically screened to detect CF, chimerism, and other chromosomal abnormalities. PROCEDURE: Lymphocytes from heparinized blood samples were cultured by standard cytogenetic techniques, and chromosome spreads were prepared for microscopic examination. Chromosomal abnormalities were detected by examining 10 chromosome spreads per bull. Pedigree analysis was performed. RESULTS: None of the bulls had any type of CF. However, 6 bulls were identified as chimeras (i.e., contained lymphocytes with male [XY] and female [XX] chromosomes). One bull was sire or maternal grandsire to 85 of the bulls tested, and 739 of 1,212 (61%) sire and maternal-grandsire possibilities were accounted for by just 18 bulls. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results supports previous indications that CF is extremely rare in Holstein bloodlines available commercially via AI in the United States. However, chimeric bulls are more common, and they reportedly have decreased reproductive performance. Therefore, identification of chimeric sires in the AI facility reported here and the possibility of de novo onset of CF at any time indicates that early cytogenetic screening should be encouraged for prospective bulls intended for use in AI programs.

XX/XY chimerism and freemartinism in a female llama co-twin to a male.

A 20-month-old female llama was examined because at the time of mating, the male llama was apparently unable to achieve intromission. The female llama had been born co-twin to a male. On physical examination, the vaginal vestibule appeared to end in a blind pouch, and the uterus, cervix, and ovaries could not be identified during transrectal palpation or ultrasonography. Karyotyping was done, and 43% of blood lymphocytes had 2 X chromosomes, and 57% had 1 X and 1 Y chromosome. All skin fibroblasts had 2 X chromosomes. A diagnosis of freemartinism and XX/XY chimerism was made. Because conception of twins may be more common in llamas than birth of twins, it is possible that freemartinism could develop in singleton females, if, for instance, a male twin was conceived and died after the placentas had anastomosed. More widespread use of karyotyping in llamas with congenital defects of the reproductive tract will help to define the incidence of freemartinism.

Characterization of a swine chromosome-specific centromeric higher-order repeat.

The centromeric region of swine chromosomes is comprised of tandemly repeated, divergent DNA monomer units. Here we report that these divergent DNA monomer sequences are organized into higher-order repeats, analogous to the hierarchical organization of alpha-satellite monomers in human centromeres. In this study, a centromeric cosmid clone was shown to be comprised entirely of a 3.3-kb higher-order repeat, with independent copies of this higher-order repeat more than 99% identical to each other. This higher-order repeat is composed of ten divergent monomer units of approximately 340 bp. The ten monomers are on average 79% identical, and all ten monomers are arranged in the same 5' to 3' orientation. In FISH analysis, a cloned 3.3-kb higher-order repeat hybridized to the centromere of Chromosome (Chr) 9 in metaphase spreads and detected two discrete foci in interphase nuclei, demonstrating that this swine higher-order repeat is chromosome-specific. The Chr 9 centromeric array spanned approximately 2.2 Mb as determined by pulsed-field gel electrophoresis. Moreover, the swine Chr 9 centromere is highly polymorphic, because an EcoRI restriction site polymorphism was detected. Thus, the assembly of divergent satellite sequences into chromosome-specific higher-order repeats appears to be a common organizational feature of both the human and swine centromere and suggests that the evolutionary mechanism(s) that create and maintain higher-order repeats is conserved between their genomes.

X-chromosome monosomy in an infertile female llama.

A 3-year-old female llama was examined because of a history of infertility and apparent anovulation. The llama had indifferent behavior when penned with a male, but eventually would assume sternal recumbency for breeding. On examination, the llama was underweight and small in stature. The uterine horns and ovaries could not be identified during palpation or ultrasonography per rectum, and the cervix was dilated when examined with a speculum. Chromosomal preparations of lymphocytes and skin fibroblasts were performed; all cells examined had a 73, X karyotype (X-chromosome monosomy). To our knowledge, this is the first report of a chromosomal anomaly in a llama. Signs seen in this llama were similar to those seen in mares with X-chromosome monosomy. This condition should be considered in the differential diagnosis of infertility in llamas that fail to ovulate, especially if other abnormalities such as indifferent sexual behavior and short stature are present.

Mapping of microsatellite markers developed from a flow-sorted swine chromosome 6 library.

Swine Chromosome (Chr) 6-enriched libraries, generated with size-fractionated DNA isolated from chromosomes sorted by flow cytometry, have been used to develop new Chr 6 microsatellite markers. Chromosome isolation procedures were established to reproducibly prepare high quality chromosomes from phytohemagglutinin (PHA)-stimulated swine peripheral blood lymphocytes and to sort individual chromosomes after staining with Hoechst 33258 and chromomycin A3. Chromosome purity was verified by specific staining of swine Chr 6 with fluorescence in situ hybridization (FISH) by use of painting probes generated by degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR) amplification of as few as 300 sorted Chr 6. For library construction, DNA was extracted from flow-sorted pools representing Chr 6, amplified, size selected for fragments from 300 to 700 bp, and ligated into pBluescript SK II+ or Lambda ZAP Express. The libraries were then screened with a radiolabeled poly-(dCA) DNA probe. Of 107 (CA)n repeat-containing clones verified by sequencing, 21 were polymorphic and used to genotype the University of Illinois swine reference families. Linkage analysis was then performed with CRIMAP 2.4 (LOD > 3.0), and the results showed that 15 of the microsatellites mapped to swine Chr 6. At least three of these new markers map to locations where there were gaps in the consensus Chr 6 map. Another four markers, because of their PIC values, should provide more informative markers in other areas of the map. Most of the new markers can also be used for automated genotyping with fluorescent labeling. This set of 15 new Chr 6 markers will, therefore, be useful in helping to define QTL associated with swine Chr 6.

Development and use of a microdissected swine chromosome 6 DNA library.

To facilitate the identification of microsatellite genetic markers from a single swine chromosome, chromosome microisolation and microcloning have been used to generate a swine chromosome 6-specific DNA library. Ten copies of swine chromosome 6 were scraped from metaphase spreads, ligated to custom-prepared adaptors, and amplified by PCR. The purity of the amplified product was verified by fluorescent in situ hybridization. The utility of the chromosome painting probe for heterologous painting was demonstrated and confirmed that swine chromosome 6 is syntenic to human chromosomes 1p and 19q. A small insert genomic library of 1.39 x 10(6) clones was generated from the PCR-amplified chromosome 6 genomic DNA and screened for (GT)n microsatellite genetic markers. Nine (GT)n microsatellite markers were developed and genotyped on a Yorkshire x Meishan swine reference family. All nine markers genetically mapped to chromosome 6, confirming the purity of the microisolation method. The method used here should be adaptable to the microdissection of subchromosomal regions of not only the swine genome but also other livestock genomes.

XX male syndrome in a cryptorchid stallion.

A bilateral cryptorchid stallion with mild development of mammary glands was identified as an XX male by karyotyping. Necropsy revealed underdeveloped accessory sex organs and hypoplastic, inguinally located testes that were deficient of spermatogonia. Evaluation of routine hormonal profiles (without karyotyping) would have failed to diagnose this syndrome.

Diagnosis of freemartinism in cattle: the need for clinical and cytogenic evaluation.

A total of 727 blood samples from female calves born co-twin to male calves were examined cytogenetically for freemartinism between 1978 and 1992. Six hundred calves (82.5%) were determined to be freemartins, and 127 (17.5%) were determined not to be freemartins. The percentage of calves determined not to be freemartins was substantially higher than the 8% reported for an unselected population of female co-twins. We concluded that some obvious freemartins were eliminated prior to submission of samples for confirmatory cytogenetic diagnosis, and that only a small percentage of the estimated 93,000 female calves born co-twin to male calves annually are so examined. Therefore, probably a large number of female co-twins that are not truly freemartins are sold to slaughter every year. We propose that obvious freemartins be identified by use of the vaginal-length test and that the remaining clinically questionable calves be differentiated cytogenetically. This combination of procedures could prevent unnecessary economic losses and preserve important genetic material. Three animals with chromosomal anomalies were found during examination of samples for freemartinism. Cytogenetic evaluation for freemartinism thus offers the added value of simultaneous surveillance for cytogenetic aberrations in male and female cells of a sample.

Stallion karyotype variability and lack of association with abortion: a case report.

Karyotype analysis was done on a stallion that impregnated 23 mares during the 1991 breeding season, of which 14 aborted between 2 and 4 mo fo gestation. Lymphocytes examined contained a 64,XY complement of normal appearing sex chromosomes and autosomes, except for slight dimorphism of the centric heterochromatin of chromosome No. 1. A skin biopsy was procured form the stallion for karyotype analysis, and the stallion was bred to 11 mares. Three mares were detected pregnant 16, 35, 45 d after breeding. The fetuses were recovered transcervically using curved intestinal forceps 47 (n=2) and 49 (n=1) d after breeding. Fetal tissue was rinsed and packed in culture media, transported overnight in a chilled container, cultured by standard tissue culture techniques, and prepared for karyotype analysis. No abnormalities were found in standard karyotypes from those cultures. One fetal karyotype revealed slight dimorphism of the heterochromatin of chromosome No. 1. Chromosome spreads obtained from the stallion's skin biopsy revealed a normal karyotype with no difference in the amount of heterochromatin present in No. 1 chromosomes. During the 1992 breeding season, the stallion impregnated 23 of 25 mares bred. Only 1 mare aborted, at 8 mo of gestation. Apparently, the amount of heterochromatin of No. 1 horse chromosomes can vary, and caution should be used in diagnosing this as a cause of pregnancy failure.

A chromosomal reciprocal translocation (1q+; 14q-) in a boar siring reduced litter sizes.

In our initial cytogenetic surveillance of boars one of 15 was found to be hypoprolific. It averaged 7.1 piglets per litter in over 51 monospermic matings with sows which, with other boars averaged 10.8 piglets per litter. Cytogenetic evaluations revealed only the hypoprolific boar to have an abnormal karyotype, namely {38XY, t(1;14) (q2.12, q2.2)}. This represents a new type of 1;14 reciprocal translocation, and also the first report of a reciprocal translocation for swine in the United States.

Prevalence of the 14/20 centric fusion chromosomal aberration in US Simmental cattle.

Cytogenetic evaluation was made on 353 Simmental cattle (166 male, 187 female) from 113 herds in 26 states. One hundred thirty-eight (39%) were found to be heterozygous-positive for the 14/20 centric fusion chromosomal translocation, including 41 (25%) males and 97 (52%) females. One submitted heparinized blood sample from a Simbrah bull was found to be positive for 14/20 and 1/29 centric fusions. Sampling, which was based on requests, was highly selective. Thus, the 39% prevalence found was not representative of 14/20 centric fusion in the national Simmental breed. On the basis of our findings, cytogenetic evaluation of breeding stock was consistent with modern management practice.

Prolonged proestrus in a bitch with X chromosomal monosomy (77,XO).

A stunted Miniature American Eskimo bitch that had signs of proestrus, which persisted for almost 8 months, had a 77,XO karyotype. Despite signs of proestrus, the ovaries were small and fibrous, and there was no evidence of ovarian follicle development or corpora lutea. Except for its juvenile appearance, the rest of the reproductive tract was grossly normal. Clinical signs in this bitch were similar to those in human beings with Turner's syndrome.