Semen characteristics of genetically identical male cats cloned via somatic cell nucleus transfer

We investigated the sperm characteristics of four cloned male cats (Felis catus) to assess their reproductive potential. Fresh and frozen-thawed sperm were assessed for motility, viability, and morphology, and their functional competence was evaluated by in vitro fertilization (IVF) of domestic cat oocytes. All fresh semen characteristics varied among cats and collection times. Sperm concentration (x 10(6)/mL) of Cat A (512+/-140, range 368 to 685) was significantly higher, whereas that of Cat C (335+/-92, range 274 to 469) was significantly lower than that of Cloned B (459+/-159, range 336 to 510) and control cats (680+/-452, range 360 to 479). After thawing, motility and progressive motility of sperm from Cat B were significantly lower than that of the other cloned and control cats. The curvilinear, straight line, and average path velocities of sperm from Cat B were significantly higher, whereas the straightness was lower, than that of the other cloned and control cats. Frozen sperm from Cats A, B, and C successfully fertilized oocytes (cleavage=74.4%, 71.4%, and 86.2%, respectively) and produced embryos that developed to the blastocyst stage after IVF/In vitro culture (IVC) (34.4%, 26.7%, and 48.0%) at frequencies similar to the cleavage rate (82.0%) and blastocyst rate (43.9%) obtained with sperm from the control male. In conclusion, seminal characteristics of cloned male cats did not differ markedly from those of our noncloned, control male cats.

302 CONFIRMATION OF GERM-LINE TRANSMISSION OF RED FLUORESCENCE PROTEIN TRANSGENIC MALE CAT

Production of transgenic animals is highly desirable for biotechnology and basic research. Therefore, a method of producing genetically modified cats through genetic engineering is important for generating biomedical models of human diseases. We investigate reproductive ability of red fluorescence protein (RFP) transgenic cloned male cat (RFP TG cat) in natural mating with domestic female cat. One domestic female cat in natural mating with RFP TG cat delivered 6 kittens of which 3 (2 female and 1 male) showed RFP expression of parental line. Among the 3 RFP expressing kittens, 1 died at day 5 and were subjected to PCR analysis for confirmation of RFP gene expression. Red fluorescence protein gene was detected in tissue samples including liver, muscle, brain, large intestine, bladder, spleen, sexual organ, small intestine, kidney, heart, stomach, pancreas, lungs, and skin of the kitten. These results indicated that RFP transgenic cloned male cat have normal reproductive fertility, and the stability of transmission of the RFP transgene through the germ line and its normal expression in offspring. Supported by KOSEF (M10525010001-05N2501-00110). S. J. Cho, Y. S. Lee, E. G. Choi, and J. I. Bang were supported by a scholarship from the Post BK21 Program, the Ministry of Education, Science and Technology, Korea.

63 PRODUCTION OF CLONED TRANSGENIC RED CATS

A method for engineering and producing genetically modified cats is important for generating biomedical models of human diseases. Because the feline gene map displays a higher level of systemic conservation with the human genome than with rodents or other laboratory mammals, cats may offer a more appropriate model in which to study potential therapies for human diseases. A second point of application is the production of transgenic cats, genetically engineered designer pets with favorable attributes, such as allergen-free cats. Mature oocytes from superovulated cat ovaries were collected. Donor fibroblasts were obtained from an ear-skin biopsy of a white maleTurkish Angora cat, cultured for one to two passages, and then subjected to transduction with a retrovirus vector designed to transfer and express the red fluorescent protein (RFP) gene. Single donor cells emitting red fluorescence were selected under an inverted microscope equipped with an RFP filter set. For somatic cell nuclear transfer (SCNT), denuded oocytes were treated with 0.2 µg m L–1 demecolcine for 1 h, and the protruding first polar body and chromatin plate were removed by micromanipulation. A single donor cell was transferred into each enucleated oocyte. In total, 176 RFP cloned embryos were transferred into 11 surrogate mothers (mean = 16 � 7.5 per recipient). Three of eleven surrogate mothers (S) were successfully impregnated (27.3%). Surrogate S-2 delivered one liveborn and one stillborn kitten at 65 days of gestation while S-3 delivered one liveborn kitten at 66 days of gestation. Microsatellite analysis revealed that all kittens were genetically identical to the donor cat. Presence of the RFP gene in the transgenic cat genome was confirmed by PCR and Southern blot analyses. Whole body red fluorescence was detected 60 days after birth in the liveborn transgenic (TG) cats, but not in the non-TG cats under excitation emission filter sets. The expression pattern of the RFP transgene was determined in several tissues taken from TG stillborn and non-TG cats. Although expression in the heart was detected more weakly than in other organs, red fluorescence was present in all tissue samples tested, but not in those from the non-TG cat. This is the first report of the successful production of a cloned transgenic cat expressing an exogenous gene. Our nuclear transfer procedure using genetically modified somatic cells would be useful for the efficient production of transgenic cats. The application of the SCNT procedure to produce genetically modified cats would be valuable for biomedical modeling of human disease, as well as for the production of designer pets. This work was supported by a Korea Science and Engineering Foundation (KOSEF) grant funded by the Korean government (MOST) (grant # M10525010001-05N2501-00110).

98 BLASTOCYST DEVELOPMENT RATE OF CLONED CAT EMBRYOS USING SERIAL CLONING

Domestic cats are a useful research model to develop assisted reproductive technologies for the conservation of endangered felids. Previously, we produced cloned offspring derived from somatic cell nuclear transfer of ear skin fibroblasts obtained from a deaf, odd-eyed, male Turkish Angora. The aim of this study was to assess the cloning efficiency of the fibroblasts derived from a cloned cat. Fibroblast cell lines were established from 6-mm skin biopsies taken from a deaf, odd-eyed, male Turkish Angora and his clone. The protocol for nuclear transfer was described previously (Yin et al. 2005 Reproduction 129, 245–249). Briefly, cumulus cells were removed from the ova by gently pipetting them into TCM-199 supplemented with 0.1% hyaluronidase. The denuded oocytes were then cultured in TCM-199 supplemented with 0.2 �g mL-1 demecolcine for 1 h and placed into TCM-199 containing 5 �g mL-1 cytochalasin B and 0.2 �g mL-1 demecolcine. The first polar body and protruded chromatin plate were removed with a beveled micropipette. Micromanipulation was used to place a single donor cell nucleus into the perivitelline space of enucleated ova. The ovum-cell couplets were fused and pulse activated. The activated couplets were cultured in 500 �L of CRI medium supplemented with 0.3% BSA for 2 days. The cleaved embryos were cultured in CRII medium supplemented with 10% FBS for 5 days. The cleavage and blastocyst development rates were 38.5% and 3.5% for second generation cloned embryos. A total of 310 second generation cloned embryos were transplanted to 9 surrogates, and 2 pregnancies at 30 days were determined by ultrasonography. One pregnancy was aborted at 40 days of gestation; the second pregnancy continued. These results indicate that the serial cloning of a cat can be generated efficiently up until pregnancy. This work was supported by KOSEF (grant #M10525010001-05N2501-00110).

30 GROWTH AND REPRODUCTIVE SUCCESS OF CLONED MALE CATS DERIVED FROM ADULT SOMATIC CELL NUCLEAR TRANSFER

There have been very few published reports on the normal growth and fertility of cloned cats derived from adult somatic cell nuclear transfer (SCNT). Here, we report studies investigating the growth and fertility of cloned male cats produced by SCNT. This study was designed to investigate the reproductive success by natural breeding of cloned male cats with domestic female cats and to measure endocrine hormone profiles related to male reproduction such as testosterone, LH, and FSH. Clones A, B, and C produced 3, 2, and 4 kittens, respectively, after natural mating with 4 domestic female cats, and clone D produced 5 kittens, in spite of being further into puberty than the other cloned male cats. All of the females delivered at 64 to 66 days after natural mating. The results obtained are presented as the mean � SEM. Sexual hormones were analyzed by ANOVA. All statistical analysis was conducted with SAS (SAS Institute Inc., Cary, NC, USA), and P < 0.05 was considered significant. Three of the 14 kittens expressed an odd eye color, which was produced from 1 clone A and 2 clone B cats. The eye color of other F1 kittens varied from brown to blue. Body weight at birth ranged from 72.9 to 134 g. Although clone D had a lower libido and entered puberty later than the other cloned males, it produced gonadal hormones within the average range. Four cloned male cats had normal fertility and were free from any reproductive problems. All of the cloned male cats were similar to two control and donor cats with respect to concentration of gonadal hormones. However, the concentration of testosterone in a castrated donor cat was significantly lower than that from clones A, B, C, D, and control cats (0.4 � 0.1 vs. 5.99 � 5.68; 3.46 � 2.81; 6.41 � 2.17; 3.75 � 0.34; 4.0 � 3.63 ng mL-1; P < 0.05). The concentrations of LH and FSH were not significantly different among any of the cats. A total of 14 kittens, 7 male and 7 female, were produced by the natural breeding of cloned male cats with 4 domestic female cats. These results indicate that cloned male cats have normal reproductive success and lie within the normal range of gonadal hormone production. All of the F1 kittens were produced by natural breeding, delivery, demonstrated normal growth, and are still alive and healthy. This work was supported by KOSEF (grant M10525010001-05N2501-00110).

310 NUCLEAR AND MICROTUBULE REMODELING AND IN VITRO DEVELOPMENT OF NUCLEAR TRANSFERRED CAT OOCYTES WITH SKIN FIBROBLASTS OF DOMESTIC CAT AND LEOPARD CAT

The leopard cat (Prionailurus bengalensis), a member of the felidae family, is a threatened animal in South Korea. In terms of endangered felids, nuclear transfer is a potentially valuable technique for assuring the continuation of species with dwindling numbers. The protocol for nuclear transfer has been described previously (Yin et al. 2005 Reproduction 129, 245-249). In this experiment we evaluated nuclear and microtubule remodeling and the in vitro developmental potential of enucleated cat oocytes reconstructed with nuclei from either domestic cat fibroblasts (DCF) or leopard cat fibroblasts (LCF). Microtubule aster was allocated to decondensed chromatin at 6 h post-activation following nuclear transfer of fibroblast cells from both DCF and LCF (3/3 in DCF, 2/3 in LCF), suggesting the introduction of a somatic cell centrosome (Kim et al. 1996 Mol. Reprod. Dev. 43, 248-255; Park et al. 2004 Mol. Reprod. Dev. 68, 25-34). At 12 h following nuclear transfer, the nucleus swelled into a large pronucleus-like structure in most reconstructed oocytes (5/9 in DCF and 4/6 in LCF), which showed further enlargement until 18 h after nuclear transfer (4/6 in DCF, 4/6 in LCF). Two microtubule asters were seen near the swollen nucleus. At 18 h following nuclear transfer, the mitotic metaphase (1/6 in DCF) or two cell divisions (1/6 in DCF, 2/6 in LCF) were observed. The percentage of blastocyst formation from nuclear transfer embryos derived from DCF (4/46, 8.6%) was not significantly different from that for nuclear transfer embryos constructed with LCF (4/52, 7.6%). Statistical significance was established at the P < 0.05 level by a X2-test (SAS; SAS Institute, Inc., Cary, NC, USA). These results indicate that nuclear and microtubule remodeling processes and in vitro developmental ability are similar in cat oocytes reconstructed with both domestic cat and leopard cat nuclei. This work was supported by KOSEF (grant # M10525010001-05N2501-00110).

Cats cloned from fetal and adult somatic cells by nuclear transfer

This work was undertaken in order to study the developmental competence of nuclear transfer (NT) into cat embryos using fetal fibroblast and adult skin fibroblast cells as donor nuclei. Oocytes were recovered by mincing the ovaries in Hepes-buffered TCM199 and selecting the cumulus oocyte complexes (COCs) with compact cumulus cell mass and dark color. Homogenous ooplasm was cultured for maturation in TCM199+10% fetal bovine serum (FBS) for 12 h and used as a source of recipient cytoplast for exogenous somatic nuclei. In experiment 1, we evaluated the effect of donor cell type on the reconstruction and development of cloned embryos. Fusion, first cleavage and blastocyst developmental rate were not different between fetal fibroblasts and adult skin cells (71.2 vs 66.8; 71.0 vs 57.6; 4.0 vs 6.1% respectively; P < 0.05). In experiment 2, cloned embryos were surgically transferred into the oviducts of recipient queens. One of the seven recipient queens was delivered naturally of 2 healthy cloned cats and 1 stillborn from fetal fibroblast cells of male origin 65 days after embryo transfer. One of three recipient queens was delivered naturally of 1 healthy cloned cat from adult skin cells of female origin 65 days after embryo transfer. The cloned cats showed genotypes identical to the donor cell lines, indicating that adult somatic cells can be used for feline cloning.