Abstract. Although the diagnosis of canine leukemia and lymphoma in advanced stages is usually uncomplicated, some presentations of the disease can be a diagnostic challenge. In certain situations, lymphoma and leukemia can be difficult to distinguish from a benign reactive proliferation of lymphocytes. Because clonality is the hallmark of malignancy, we have developed an assay that uses the polymerase chain reaction to amplify the variable regions of immunoglobulin genes and T-cell receptor genes to detect the presence of a clonal lymphocyte population. The assay detected clonally rearranged antigen receptor genes in 91% of the 77 dogs with lymphoid malignancy. Of the 24 dogs tested, that were either healthy or had clearly defined conditions not related to lymphoid malignancy, a clonally rearranged antigen receptor gene was found in one (a dog with Ehrlichia canis infection). Gene rearrangement was appropriate for the immunophenotype (immunoglobulin gene rearrangement in B-cell leukemias and T-cell receptor gene rearrangement in T-cell leukemias). Dilution analysis showed that the clonal rearrangement could be detected when 0.1-10% of the DNA was derived from neoplastic cells, depending on the source tissue. Potential applications of this assay include the diagnosis of lymphoma or leukemia in biopsy samples, cavity fluids, fine needle aspirates, bone marrow and peripheral blood; the determination of lineage (B or T cell); staging of lymphoma; and detection of residual disease after chemotherapy.Key words: Dogs; gene rearrangement; genes-immunoglobulin; leukemia; lymphoma; myeloma; receptorsantigen-T-cell.Detection of canine lymphocytic malignancies relies on the cytologic assessment of circulating lymphocytes or lymphoid tissue or on the histologic examination of the lymphoid tissue. The diagnosis is often straightforward but there are situations that present a diagnostic challenge. These include the early stages of lymphoma that may be difficult to distinguish from lymphoid hyperplasia; cavity fluids that contain large numbers of small, mature-appearing lymphocytes; cases with chronic or mild lymphocytosis; cases diagnosed by biopsy where the biopsy does not fully represent the lesion; and the finding of a small number of atypical lymphocytes in a fine needle aspirate or cavity fluid. In addition, mass aspirates can be limited by inadequate cell numbers or by aspirating a site that does not represent the lesion. Therefore, more sensitive and objective assays are desirable for detecting lymphoid malignancies in dogs.Because all lymphomas, lymphocytic leukemias, and myelomas are clonal expansions of lymphocytes, 1 Present address: Center for Cancer Causation and Prevention, AMC Cancer Research Center, Denver, CO. each particular neoplasm contains DNA regions that are unique in both length and sequence. The CDR3 region of both immunoglobulin and T-cell receptor (TCR) genes encodes the antigen-binding region of the respective receptor and contains the majority of this unique sequence. In B cells, CDR3 is produced ...

The dog was the first domesticated animal but it remains uncertain when the domestication process began and whether it occurred just once or multiple times across the Northern Hemisphere. To ascertain the value of modern genetic data to elucidate the origins of dog domestication, we analyzed 49,024 autosomal SNPs in 1,375 dogs (representing 35 breeds) and 19 wolves. After combining our data with previously published data, we contrasted the genetic signatures of 121 breeds with a worldwide archeological assessment of the earliest dog remains. Correlating the earliest archeological dogs with the geographic locations of 14 so-called "ancient" breeds (defined by their genetic differentiation) resulted in a counterintuitive pattern. First, none of the ancient breeds derive from regions where the oldest archeological remains have been found. Second, three of the ancient breeds (Basenjis, Dingoes, and New Guinea Singing Dogs) come from regions outside the natural range of Canis lupus (the dog's wild ancestor) and where dogs were introduced more than 10,000 y after domestication. These results demonstrate that the unifying characteristic among all genetically distinct so-called ancient breeds is a lack of recent admixture with other breeds likely facilitated by geographic and cultural isolation. Furthermore, these genetically distinct ancient breeds only appear so because of their relative isolation, suggesting that studies of modern breeds have yet to shed light on dog origins. We conclude by assessing the limitations of past studies and how next-generation sequencing of modern and ancient individuals may unravel the history of dog domestication.genomics | phylogeography D arwin speculated about the origins of several domestic animals and suggested that, given the vast morphological variation across numerous breeds, dogs must have had more than one wild ancestor (1). Recent genetic studies, however, support the notion that dogs are descended exclusively from the gray wolf (Canis lupus) (2).Beyond questions regarding wild ancestry, geneticists and generations of archeologists have investigated not only how and why dogs were domesticated, but also when, where, and how many times it may have occurred. Unique among all domestic animals, the first unambiguous domestic dogs precede the appearance of settled agriculture in the archeological record by several thousand years. Identifying the earliest dogs is difficult, however, because key morphological characters established by zooarcheologists to differentiate domestic animals from their wild wolf ancestors (e.g., size and position of teeth, dental pathologies, and size and proportion of cranial and postcranial elements) were not yet fixed during the initial phases of the domestication process. Furthermore, the range of natural variation among these characters in ancient wolf populations and the time it took for these traits to appear in dogs are unknown. Free-ranging wolves attracted to the refuse generated by human camps most likely followed a commensal pathway to domestica...

Osteosarcomas are sarcomas of the bone, derived from osteoblasts or their precursors, with a high propensity to metastasize. Osteosarcoma is associated with massive genomic instability, making it problematic to identify driver genes using human tumors or prototypical mouse models, many of which involve loss of Trp53 function. To identify the genes driving osteosarcoma development and metastasis, we performed a Sleeping Beauty (SB) transposon-based forward genetic screen in mice with and without somatic loss of Trp53. Common insertion site (CIS) analysis of 119 primary tumors and 134 metastatic nodules identified 232 sites associated with osteosarcoma development and 43 sites associated with metastasis, respectively. Analysis of CIS-associated genes identified numerous known and new osteosarcoma-associated genes enriched in the ErbB, PI3K-AKT-mTOR and MAPK signaling pathways. Lastly, we identified several oncogenes involved in axon guidance, including Sema4d and Sema6d, which we functionally validated as oncogenes in human osteosarcoma.