Matrix metalloproteases (MMPs) are endogenous proteases that are responsible for degradation of extracellular matrix (ECM) proteins and cell surface antigens. The breakdown of ECM participates in the local invasion and distant metastases of malignant tumors. Canine transmissible venereal tumor (CTVT) is a naturally occurring contagious round cell neoplasm of dogs that affects mainly the external genitalia of both sexes. CTVT generally is a locally invasive tumor, but distant metastases also are common in puppies and immunocompromised dogs. We investigated the immune expressions and activities of MMP-2 and MMP-9 in CTVT. The presence of these enzymes in tumor cells and tissue homogenates was demonstrated by immunohistochemistry and western blotting. We used gelatin substrate zymography to evaluate the activities of MMP-2 and MMP-9 enzymes in tumor homogenates. We found that tumor cells expressed both MMP-2 and MMP-9. Electrophoretic bands corresponding to MMP-9 and MMP-2 were identified in immunoblots and clear bands that corresponded to the active forms of MMP-2 and MMP-9 also were detected in gelatin zymograms. Our study is the first detailed documentation of MMPs in CTVT.
IntroductionTurkey, which has a great number of endemic species, has an important share in the genetic resources of the earth (1). Kivircik, a sheep breed native to Turkey, has important social and economic value as genetic resources in livestock. Since 1991, the total number of sheep in Turkey has decreased dramatically. While in 1991 there were 39,000,000 head of sheep in Turkey, this number decreased to 25,000,000 in 2012 (2). Therefore, there is a need to develop strategies and methodologies to preserve and support the sustainability of native sheep breeds. Cryopreserved embryos might enable us to bring back sheep from a lost breed. Cryopreserving healthy germ cells and embryos may help to eradicate animal health problems and make use of specific genes in native breeds that might emerge in the future, as well (3,4). Developed countries have sought to preserve threatened breeds by offering financial incentives in the form of grants for the collection and cryopreservation of gametes and embryos (5).Superovulation is the most important step in the conservation of animal genetic resources via in vivo production. Multiple ovulation and embryo transfer (MOET) can be applied to gain extra genetic yield through the production of embryos obtained from selected females and males (6).These programs in small ruminants are limited to the natural breeding season because small ruminants have seasonal cyclic activity patterns. In sheep, the breeding season lasts from August to November in temperate northern latitudes (7). Extending the application of these techniques outside of the breeding season would allow ewes involved in genetic improvement programs to undergo embryo recovery procedures throughout the year (8).However, conflicting results have been reported in studies designed to determine the effect of the season in MOET protocols. Some studies of superovulation application in ewes from high latitudes have reported seasonal differences in the rates of ovulation (9), fertilization, and embryo quality (8). Such differences are not present or are smaller in tropical and Mediterranean areas (10).
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