Real-time algorithm for Poissonian noise reduction in low-dose fluoroscopy: performance evaluation.

BACKGROUND: Quantum noise intrinsically limits the quality of fluoroscopic images. The lower is the X-ray dose the higher is the noise. Fluoroscopy video processing can enhance image quality and allows further patient's dose lowering. This study aims to assess the performances achieved by a Noise Variance Conditioned Average (NVCA) spatio-temporal filter for real-time denoising of fluoroscopic sequences. The filter is specifically designed for quantum noise suppression and edge preservation. It is an average filter that excludes neighborhood pixel values exceeding noise statistic limits, by means of a threshold which depends on the local noise standard deviation, to preserve the image spatial resolution. The performances were evaluated in terms of contrast-to-noise-ratio (CNR) increment, image blurring (full width of the half maximum of the line spread function) and computational time. The NVCA filter performances were compared to those achieved by simple moving average filters and the state-of-the-art video denoising block matching-4D (VBM4D) algorithm. The influence of the NVCA filter size and threshold on the final image quality was evaluated too. RESULTS: For NVCA filter mask size of 5 × 5 × 5 pixels (the third dimension represents the temporal extent of the filter) and a threshold level equal to 2 times the local noise standard deviation, the NVCA filter achieved a 10% increase of the CNR with respect to the unfiltered sequence, while the VBM4D achieved a 14% increase. In the case of NVCA, the edge blurring did not depend on the speed of the moving objects; on the other hand, the spatial resolution worsened of about 2.2 times by doubling the objects speed with VBM4D. The NVCA mask size and the local noise-threshold level are critical for final image quality. The computational time of the NVCA filter was found to be just few percentages of that required for the VBM4D filter. CONCLUSIONS: The NVCA filter obtained a better image quality compared to simple moving average filters, and a lower but comparable quality when compared with the VBM4D filter. The NVCA filter showed to preserve edge sharpness, in particular in the case of moving objects (performing even better than VBM4D). The simplicity of the NVCA filter and its low computational burden make this filter suitable for real-time video processing and its hardware implementation is ready to be included in future fluoroscopy devices, offering further lowering of patient's X-ray dose.

Risk factors for difficult thyroidectomy and postoperative morbidity do not match: retrospective study from an endocrine surgery academic referral centre.

Hyperthyroidism, goiter and thyroiditis have been associated with complex thyroidectomy. Difficult thyroidectomies may implicate longer operating times and higher complication rates, while literature on quantification and prediction of difficulty in thyroidectomy is scant. We aim at assessing the impact of preoperative and intraoperative factors on the technical difficulty of total thyroidectomy (TT) and on the incidence of postoperative complications. We conducted a retrospective study on 197 TT from 343 thyroidectomies performed with intraoperative neuromonitoring between October 2019 and June 2022 (excluding lobectomies, nodal dissection, extra-thyroidal procedures). Operating time (surrogate of TT difficulty), postoperative hypocalcaemia, recurrent laryngeal nerve palsy and postoperative bleeding were assessed in relation to pre- and intraoperative characteristics. Vocal fold palsy(VFP) was defined as recovering < 12 months postoperatively. There were 87 thyroid cancers and 110 multinodular goiters (21 hyperfunctioning, 51 mediastinal). Median operating time was 136 min (range 51-310). Within 17.4 months overall median follow-up we recorded two transient VFPs and 12% symptomatic transient hypocalcaemia. At univariable analysis male sex (p = 0.005), BMI (p < 0.001), thyroiditis (p < 0.05), hypervascular goiter (p = 0.003) and thyroid adhesions to surrounding anatomical structures (p < 0.001) were associated with longer operating time. At multivariable analysis male male sex (p = 0.01), obesity (p = 0.001) and thyroid adhesions (p = 0.008) were factors for prolonged operating time. Above-normal anti-thyroid peroxidase antibodies correlated to transient symptomatic hypocalcemia (p < 0.001). Risk factors for complex TT were identified and did not correlate with morbidity rates. Results from this study may help optimizing operating room schedule and inform case selection criteria for training programs in thyroid surgery. Further research is required to confirm these findings.

Extended cytogenetic maps of sheep chromosome 1 and their cattle and river buffalo homoeologues: comparison with the OAR1 RH map and human chromosomes 2, 3, 21 and 1q.

Cytogenetic maps are useful tools for several applications, such as the physical anchoring of linkage and RH maps or genome sequence contigs to specific chromosome regions or the analysis of chromosome rearrangements. Recently, a detailed RH map was reported in OAR1. In the present study, we selected 38 markers equally distributed in this RH map for identification of ovine genomic DNA clones within the ovine BAC library CHORI-243 using the virtual sheep genome browser and performed FISH mapping for both comparison of OAR1 and homoeologous chromosomes BBU1q-BBU6 and BTA1-BTA3 and considerably extending the cytogenetic maps of the involved species-specific chromosomes. Comparison of the resulting maps with human-identified homology with HSA2q, HSA3, HSA21 and HSA1q reveals complex chromosome rearrangements differentiating human and bovid chromosomes. In addition, we identified 2 new small human segments from HSA2q and HSA3q conserved in the telomeric regions of OAR1p and homoeologous chromosome regions of BTA3 and BBU6, and OAR1q, respectively. Evaluation of the present OAR1 cytogenetic map and the OAR1 RH map supports previous RH assignments with 2 main exceptions. The 2 loci BMS4011 and CL638002 occupy inverted positions in these 2 maps.

A new and unusual reciprocal translocation in cattle: rcp(11;25)(q11;q14-21).

A new and unusual reciprocal translocation was detected in a heifer of the Agerolese cattle breed during a routine cytogenetic screening carried out on 13 animals (2 males and 11 females) kept at the ConSDABI Conservation Center in Benevento (Southern Italy). The 13 animals investigated had a normal karyotype except for a 1-year-old female, which carried one autosome smaller than the smallest normal bovine autosomes. This small autosome showed very little C-banding in comparison to the other autosomes, while another medium-sized autosome showed 2 distinct and prominent C-bands. RBA-banding and karyotype analysis revealed that these 2 chromosomes were the result of a reciprocal translocation between chromosomes 11 and 25. FISH analysis with BAC142G06 mapping to the proximal (subcentromeric) region of both BTA25 and der11, BAC513H08 (ELN) mapping to BTA25q22dist and der25, and BAC533C11 mapping to the proximal region of BTA11 and der11 confirmed the localization of the breakpoints on band q11 (centromere) of chromosome 11 and q14-21 of chromosome 25. Ag-NOR and sequential RBA/Ag-NOR techniques detected the presence of NORs on both BTA11 and BTA25 and both der11 and der25. To our knowledge, this is the first report of a reciprocal translocation event in cattle with the breakpoint located in the centromeric region.

A rare case of centric fission and fusion in a river buffalo (Bubalus bubalis, 2n = 50) cow with reduced fertility.

A 5-year-old river buffalo cow underwent cytogenetic investigation since it had only one male offspring, apparently with normal body constitution, which died one month after birth. The female carrier had normal body conformation and internal sex adducts, as revealed by rectal palpation performed by a specialist veterinary practitioner. The cow was found to carry a complex and rare chromosome abnormality. Indeed, a centric fission of one river buffalo (BBU) chromosome 1 with a subsequent (or simultaneous) centric fusion of BBU1p with BBU23 was revealed by both RBA-banding and specific molecular markers of BBU1p (DEFB1) and BBU23 (ACTA2). CBA-banding revealed a pale, very small C-band in the der1 (BBU1q) and a prominent C-band on the new biarmed chromosome originated by rob(1p;23). Both telomeric probes and AgNOR staining confirmed the Robertsonian translocation (rob), both FITC-signals and the NORs (BBU23) being telomerically located. Furthermore, telomeric signals on der1 (BBU1q) indicate that these 2 chromosomal events may be the result of a reciprocal translocation which occurred between BBU1 and BBU23.

Chromosome fragility in dairy cows exposed to dioxins and dioxin-like PCBs.

In this study, we compared cross-bred dairy cows in the Susa Valley (Piedmont, northern Italy), reared either near a high-temperature steel production plant (Farms A and B) or in an industry-free area (control). Exposed cows (n = 36) were selected based on mean bulk milk toxic equivalent values of polychlorodibenzodioxins (PCDDs) and dioxin-like (DL) polychlorobiphenyls (PCBs) and polychlorodibenzofurans (PCDFs) equal to 18.56 pg/g fat and 8.56 pg/g of fat in dairy cows from Farms A and B, respectively, exceeding both those permitted by the legislation in force (6 pg/g fat PCDDs and DL-PCDFs/PCBs), and those measured in dairy cows (n = 19) of the farm used as control (1.75 pg/g of fat PCDDs and DL-PCDFs/PCBs). Two types of peripheral blood cell cultures were performed: without (normal cultures for the chromosome abnormality (CA)-test: gaps, chromatid breaks, chromosome breaks and fragments) and with addition of bromodeoxyuridine [for the sister chromatid exchange (SCE)-test]. Both tests revealed a significant (P ≤ 0.05) higher chromosome fragility in the exposed cattle compared to controls: CA/cell mean values (without gaps) were 0.65 ± 0.91, 0.51 ± 0.81 and 0.13 ± 0.39 in Farms A, B and controls, respectively, while SCE/cell mean values were 7.00 ± 2.88, 6.39 ± 2.80 and 5.29 ± 2.51. Although the role of other pollutants (e.g. heavy metals) in the genesis of the recorded chromosome alterations cannot be ruled out, our results confirm the findings of previous research into dioxin-exposed sheep.

Indocyanine Green Fluorescence Angiography Can Guide Intraoperative Localization During Parathyroid Surgery.

BACKGROUND AND AIMS: Intraoperative localization of pathologic parathyroid glands is of major importance for the hyperparathyroidism treatment. Based on the small size and the anatomic variability, the localization can be very challenging. The current practice is to compare preoperative ultrasonography with Technetium-99m sestamibi scintigraphy (MIBI) and plan the resection accordingly. In this study, we implemented indocyanine green angiography for the intraoperative localization of parathyroid glands. MATERIALS AND METHODS: This is a retrospective analysis of 37 patients with primary, secondary, or tertiary hyperparathyroidism who were operated using indocyanine green angiography for the intraoperative localization of pathological parathyroid glands. An indocyanine green solution of 2.5 mg was were intravenously administered for parathyroid gland visualization. Different fluorescence scores were correlated with changes in postoperative parathyroid hormone levels. RESULTS: Patients were divided into two groups depending on the presence of uniglandular or multiglandular disease. Sixty-four lesions were resected, and the final histopathologic analysis confirmed the parathyroid origin in 62 of them (96.8%). None of the patients with uniglandular disease developed postoperative hypoparathyroidism, whereas three patients in the multiglandular group developed temporary hypoparathyroidism symptoms. Indocyanine green imaging had higher sensitivity for the intraoperative detection of parathyroid glands compared with ultrasonography and MIBI (p < 0.001). CONCLUSION: Indocyanine green angiography indicated high sensitivity for the intraoperative identification of pathologic parathyroid glands leading to a resection rate of 95.16%. The modality was useful, especially in cases of revisional surgery or ectopic parathyroid glands. Randomized trials have already proven the value of indocyanine green imaging in predicting postoperative hypocalcemia. Our results support the regular use of this method during parathyroid surgery.

Genomic characterization and chromosomal mapping of 5 river buffalo skeletal muscle differentiation master genes.

River buffalo (Bubalus bubalis, 2n = 50, BBU) is a species of economic relevance in a number of countries. This species shows a very peculiar biology and a great capacity for environmental adaptation. There has been an increasing economic interest as well as a growing demand for a more detailed knowledge of molecular features in this species. From this perspective we report a genomic, transcriptional and cytogenetic analysis of 5 master genes involved in skeletal muscle development. Of these 5 genes, MYOD1, MYF5, MYF6 and MYOG belong to the basic helix-loop helix protein family while MSTN belongs to the TNF-B protein family. In mammals, these genes are involved in the early stages of skeletal muscle differentiation, development and regeneration. These pivotal biological functions are finely regulated in a tissue- and temporal-specific manner. We used a comparative genomic approach to obtain the buffalo specific sequences of MYOD1 and MYF6. The nucleotide sequence similarity and the protein domain conservation of the newly obtained sequences are analysed with respect to bovine and other mammalian species showing sequence similarity. The presence of a polymorphism in MYOD1 coding sequence is described and its possible effect discussed. Using a quantitative PCR approach, we compared the level of the 5 transcripts in adult and fetal muscle. These genes were physically localised on river buffalo R-banded chromosomes by FISH using bovine genomic BAC-clones. Here, we present a genomic and cytogenetic analysis which could offer a background to better characterise the buffalo genes involved in muscle function and which may be responsible for buffalo-specific meat features.

Molecular cytogenetics and comparative mapping in goats (Capra hircus, 2n = 60).

Few goat genome analysis projects have been developed in the last 10 years. The aim of this review was to compile and update all available cytogenetic mapping data, according to the last goat chromosome nomenclature, as well as human and cattle whole genome sequences. In particular, human regions homologous to most of the FISH-mapped microsatellites were identified in silico. This new goat cytogenetic map made it possible to refine delineation of conserved segments relative to the human and cattle genomic sequence. These improvements did not lead to detection of major new rearrangements within ruminants but confirmed the good conservation of synteny and the numerous intrachromosomal rearrangements observed between goats and humans.

FISH-mapping comparison between river buffalo chromosome 7 and sheep chromosome 6: assignment of new loci and comparison with HSA4.

Synchronized peripheral blood lymphocytes from both river buffalo (BBU) and sheep (OAR) were treated for late incorporation of both BrdU and H-33258 to obtain R-banded preparations to be used for FISH-mapping. Ovine BAC-clones were hybridized for three days on slides pre-exposed to UV light after H-33258 staining. The following loci were mapped: GPR103 (BBU7q13, OAR6q13), TRAM1L1(OAR6q13dist), PPP3CA (BBU7q21, OAR6q15), SNCA (OAR6q17), PPARGC1A(BBU7q23, OAR6q17), UGDH (BBU7q25prox, OAR6q22prox), KDR (BBU7q27, OAR6q22), CNOT6L (BBU7q32prox, OAR6q32prox), NUP54 (BBU7q32, BBU6q32), DMP1 (BBU7q34dist-q36prox, OAR6q34dist-q36prox), QDPR (BBU7q36, OAR6q36). All loci mapped in homoeologous chromosomes and chromosome bands of the two species and their locations are in agreement with the previous RH-mapping performed on BBU7 with some difference in the distal region of BBU7. However, the present cytogenetic map better anchors the RH-map on specific river buffalo chromosome bands. In addition, eleven loci were assigned for the first time in sheep to OAR6, noticeably extending the cytogenetic map on this important chromosome which encodes caseins. Two loci (TRAM1L1 and SNCA) mapped in sheep were unmapped in river buffalo in three different FISH experiments. Comparisons between integrated cytogenetic maps of BBU7/OAR6 (and BTA6) with human chromosome 4 (HSA4) revealed complex chromosome rearrangements differentiating these chromosomes.

Classical and molecular cytogenetics of disorders of sex development in domestic animals.

The association of abnormal chromosome constitutions and disorders of sex development in domestic animals has been recorded since the beginnings of conventional cytogenetic analysis. Deviated karyotypes consisting of abnormal sex chromosome sets (e.g. aneuploidy) and/or the coexistence of cells with different sex chromosome constitutions (e.g. mosaicism or chimerism) in an individual seem to be the main causes of anomalies of sex determination and sex differentiation. Molecular cytogenetics and genetics have increased our understanding of these pathologies, where human and mouse models have provided a substantial amount of knowledge, leading to the discovery of a number of genes implicated in mammalian sex determination and differentiation. Additionally, other genes, which appeared to be involved in ovary differentiation, have been found by investigations in domestic species such as the goat. In this paper, we present an overview of the biology of mammalian sex development as a scientific background for better understanding the body of knowledge of the clinical cytogenetics of disorders of sex development in domestic animals. An attempt to summarize of what has been described in that particular subject of veterinary medicine for each of the main mammalian domestic species is presented here.

The 450-band resolution G- and R-banded standard karyotype of the donkey (Equus asinus, 2n = 62).

Donkey chromosomes were earlier characterized separately by C-, G- and R-banding techniques. However, direct comparisons between G- and R-banding patterns have still not been carried out in this species. The present study reports this comparison at the 450-band level by using replication G- and R-banding patterns. Two sets of synchronized lymphocyte cultures were set up to obtain early (GBA+CBA-banding) and late (RBA-banding) BrdU incorporation. Slides were stained with acridine orange and observed under a fluorescence microscope. Reverse GBA+CBA- and RBA-banded karyotypes at the 450-band level were constructed. To verify G- and R-banding patterns in some acrocentric chromosomes, sequential GBA+CBA/Ag-NORs and RBA/Ag-NORs were also performed. The results of CBA-banding patterns obtained in 12 animals from 2 breeds showed a pronounced polymorphism of heterochromatin, especially in EAS1q-prox. Ideogrammatic representations of G- and R-banded karyotypes were constructed using only one common G- and R-banding nomenclature. In the present study both G- and R-banding patterns and relative ideograms are presented as standard karyotype for this species at the 450-band level.

Molecular cytogenetics and gene mapping in sheep (Ovis aries, 2n = 54).

The development of a completely annotated sheep genome sequence is a key need for understanding the phylogenetic relationships and genetic diversity among the many different sheep breeds worldwide and for identifying genes controlling economically and physiologically important traits. The ovine genome sequence assembly will be crucial for developing optimized breeding programs based on highly productive, healthy sheep phenotypes that are adapted to modern breeding and production conditions. Scientists and breeders around the globe have been contributing to this goal by generating genomic and cDNA libraries, performing genome-wide and trait-associated analyses of polymorphism, expression analysis, genome sequencing, and by developing virtual and physical comparative maps. The International Sheep Genomics Consortium (ISGC), an informal network of sheep genomics researchers, is playing a major role in coordinating many of these activities. In addition to serving as an essential tool for monitoring chromosome abnormalities in specific sheep populations, ovine molecular cytogenetics provides physical anchors which link and order genome regions, such as sequence contigs, genes and polymorphic DNA markers to ovine chromosomes. Likewise, molecular cytogenetics can contribute to the process of defining evolutionary breakpoints between related species. The selective expansion of the sheep cytogenetic map, using loci to connect maps and identify chromosome bands, can substantially contribute to improving the quality of the annotated sheep genome sequence and will also accelerate its assembly. Furthermore, identifying major morphological chromosome anomalies and micro-rearrangements, such as gene duplications or deletions, that might occur between different sheep breeds and other Ovis species will also be important to understand the diversity of sheep chromosome structure and its implications for cross-breeding. To date, 566 loci have been assigned to specific chromosome regions in sheep and the new cytogenetic map is presented as part of this review. This review will also summarize the current cytogenomic status of the sheep genome, describe current activities in the sheep cytogenomics research sector, and will discuss the cytogenomics data in context with other major sheep genomics projects.

Comparative mapping and genomic annotation of the bovine oncosuppressor gene WWOX.

WWOX (WW domain-containing oxidoreductase) is the gene mapping at FRA16D HSA16q23.1, the second most active common fragile site in the human genome. In this study we characterized at a detailed molecular level WWOX in the bovine genome. First, we sequenced cDNA from various tissues and obtained evidence in support of a 9-exon structure for the gene, similar to the human gene. Then, we recovered BACs using exon tags and annotated the gene to a >1-Mb genomic region of BTA18 using the Btau 4.0 genome assembly as a reference, thus resolving an issue related to exon 9, which is not included in the genomic annotation of the gene in the Entrez database. Finally, BACs spanning WWOX were used as FISH probes to obtain comparative mapping of the gene in Bos taurus, Bubalus bubalis, Ovis aries and Capra hircus to BTA18q12.1, BBU18q13, OAR14q12.1 and CHI18q12.1, respectively. Our data show that the chromosomal location of WWOX is conserved between man and 4 major domesticated species. Moreover, the annotation of the bovine gene also suggests a highly conserved genomic arrangement, including number and size of introns.

X-Y sperm aneuploidy in 2 cattle (Bos taurus) breeds as determined by dual color fluorescent in situ hybridization (FISH).

The present study was undertaken to investigate aneuploidy rates in the sperm populations of 2 cattle (Bos taurus) breeds by using dual color fluorescent in situ hybridization (FISH) with Xcen and Y chromosome-specific painting probes, obtained by chromosome microdissection and DOP-PCR. Frozen semen from 10 Italian Friesian and 10 Italian Brown testing bulls was used for the investigation. For each bull, more than 5,000 sperm were analyzed, for a total of 52,586 and 51,342 sperm cells for the 2 breeds, respectively. The present study revealed - in both breeds - a preponderance of the Y-bearing sperm compared to the X-bearing sperm. Within each breed, a statistically significant variation in the various classes of aneuploidy (XX, YY and XY) was found: differences were found in the Friesian breed among the 3 diploidy classes, and in the Brown breed, among the 3 disomy classes (p < 0.05) as well as among the 3 diploidy classes (p < 0.01). However, the 2 breeds did not differ significantly in the overall mean rates of X-Y aneuploidy (disomy + diploidy) which amounts to 0.162% in the Italian Friesian and 0.142% in the Italian Brown. When meiosis I (MI) and II (MII) errors were compared, statistically significant differences (p < 0.01) were found in the disomy classes and in both breeds, whereas the differences between diploidy classes were not significant. Compared to humans, a lower level of aneuploidy has been found in the domestic species analyzed so far. The present study contributes to the establishment of a baseline level of aneuploidy in the sperm populations of 2 cattle breeds which could be used for monitoring future trends of reproductive health, especially in relation to environmental changes and mutagens.

Clinical, cytogenetic and molecular evaluation in a dog with bilateral cryptorchidism and hypospadias.

The aim of this study was to estimate prognostic factors in a Dalmatian dog with bilateral cryptorchidism and hypospadias. Cytogenetic and molecular analyses revealed a normal karyotype (2n = 78,XY) and the presence of SRY, INSL3 and RXFP2 genes with a normal DNA sequence for SRY and RXFP2, while the INSL3 sequence differed slightly from the normal one due to a heterozygous nucleotide change involving amino acid 22 of the INSL3 dog precursor protein. Levels of plasmatic testosterone were only 0.01 ng/ml, while FSH and LH serum levels were not detectable. After the human chorionic gonadotropin (hCG) test, the serum testosterone level was 0.01 ng/ml. Therefore, the phenotypic aetiology of this subject can not be well-defined because cryptorchidism and hypospadias were frequent clinical features with high genetic heterogeneity.

Frequency and distribution of rob(1;29) in eight Portuguese cattle breeds.

Cytogenetic investigations performed in eight Portuguese cattle breeds revealed the presence of rob(1;29) in both heterozygous and homozygous conditions in all, and five breeds, respectively, with variable percentages of carriers as follows: 41.0% in Arouquesa, 69.9% in Barrosa, 39.4% in Maronesa, 2.8% in Mirandesa, 8.5% in Marinhoa, 1.8% in Mertolenga, 21.3% in Raca Brava and 21.5% in Alentejana. CBA- and RBA-banding were performed to ascertain the chromosomes involved in the chromosome abnormality. A total of 1,626 animals were investigated. Reproductive parameters (number of calves per 100 cows) were higher in Mirandesa (80%) when compared with both Maronesa (75%) and Barrosa (70%) breeds, underlining that rob(1;29) reduces fertility in the carriers.

Sex chromosome abnormalities and sterility in river buffalo.

Thirteen male river buffaloes, 119 females with reproductive problems (which had reached reproductive age but had failed to become pregnant in the presence of bulls) and two male co-twins underwent both clinical and cytogenetic investigation. Clinical analyses performed by veterinary practitioners revealed normal body conformation and external genitalia for most females. However, some subjects showed some slight male traits such as large base horn circumference, prominent withers and tight pelvis. Rectal palpation revealed damage to internal sex adducts varying between atrophy of Mullerian ducts to complete lack of internal sex adducts (with closed vagina). All bulls had normal karyotypes at high resolution banding, while 25 animals (23 females and 2 male co-twins) (20.7%) with reproductive problems were found to carry the following sex chromosome abnormalities: X monosomy (2 females); X trisomy (1 female); sex reversal syndrome (2 females); and free-martinism (18 females and 2 males). All female carriers were sterile.

Chromosomal expression and localization of aphidicolin-induced fragile sites in the standard karyotype of river buffalo (Bubalus bubalis).

The present study reports on the chromosomal expression and localization of aphidicolin-induced fragile sites in the standard karyotype of river buffalo (Bubalus bubalis, 2n = 50) with the aim of establishing a 'fragile site map' of the species. Totally, 400 aphidicolin-induced breakages were analyzed from eight young and clinically healthy animals, four males and four females; these breakages were localized in 106 RBG-negative chromosome bands or at the band-interband regions. The number of breakages per chromosome did not vary statistically 'among' the animals investigated but the differences among individual chromosomes were highly significant thus indicating that the chromosomal distribution of the breakages is not random and appears only partially related to chromosome length. Fragile sites were statistically determined as those chromosomal bands showing three or more breakages. In the river buffalo karyotype, 51 fragile sites were detected and localized on the standardized ideogram of the species. The most fragile bands were as follows: 9q213 with 24 breakages out of 400; 19q21 with 16, 17q21 and inacXq24 with 15, 15q23 with 13 and 13q23 with 12 breaks, respectively. Previous gene mapping analysis in this species has revealed that the closest loci to these fragile sites contain genes such as RASA1 and CAST (9q214), NPR3 and C9 (19q19), PLP and BTK (Xq24-q25), OarCP09 (15q24), and EDNRB (13q22) whose mutations are responsible for severe phenotypic malformations and immunodeficiency in humans as well as in mice and meat quality in pigs. Further cytogenetic and molecular studies are needed to fully exploit the biological significance of the fragile sites in karyotype evolution of domestic animals and their relationships with productive and reproductive efficiency of livestock.

Comparative FISH-mapping of twelve loci in river buffalo and sheep chromosomes: comparison with HSA8p and HSA4q.

Twelve loci (11 of type I and 1 of type II) previously FISH-mapped in cattle were comparatively FISH-mapped in both river buffalo chromosome 1p (BBU1p) and homologous chromosome 26 of sheep (OAR26), extending the cytogenetic maps in both chromosome species and providing a more precise localization of these loci in single chromosome bands than previous locations on BTA27. Bovine BAC clones containing DCTD, C4orf20, CASP3, TLR3, MSR1, FAT, LONRF1, DLC1, C8orf41, CSSM036, LSM1 and EIF4EBP1 were used for FISH on RBPI-banded chromosomes. All loci were located on the same homologous chromosome bands (R-band positive) of both species further confirming the high degree of banding and gene (order of loci) homologies among bovids. Detailed cytogenetic maps of OAR26 and BBU1p were performed and compared with that of BTA27 as well as with those of both HSA8p and HSA4q, revealing complex chromosome rearrangements differentiating OAR26/BBU1p/BTA27 from human chromosomes.