The effects of manipulation medium, culture system and recipient cytoplast on in vitro development of intraspecies and intergeneric felid embryos.

The aim of this study was to investigate if reconstructed felid embryos obtained by intraspecies or intergeneric cloning can develop in vitro. Fibroblast cells (f) from a domestic cat (DCf), marbled cat (MCf) and bovine (Bf) were used as donor cells, and oocytes (o) from domestic cats (DCo) and bovine (Bo) were used as recipient cytoplasts. There were two intraspecies (donor cell + recipient cytoplast: DCf + DCo and Bf + Bo) and three intergeneric (MCf + DCo, DCf + Bo and MCf + Bo) cloning groups in the study. In Experiment 1, the effects of manipulation media, modified TCM-199 (199H) or Emcare holding medium (EHM), on in vitro development of DCf + DCo embryos were investigated. The blastocyst formation rate (BFR) of the embryos manipulated in EHM (33.3%) was higher (P<0.05) compared with those manipulated in 199H (18.1%). In Experiment 2, DCf + DCo and MCf + DCo embryos were cocultured with or without domestic cat oviductal epithelium cells. Irrespective of coculture, the same BFR was obtained for DCf + DCo embryos (44.4 vs. 38.0%), while MCf + DCo embryos could not develop beyond the morula stage. In experiment 3, although the development of MCf + DCo and DCf + Bo embryos was arrested at the morula stage, 8.6% of MCf + Bo embryos were able to develop to the blastocyst stage. These results demonstrated that EHM was superior to 199H as an embryo manipulation medium and that the DCo and Bo could support the early embryonic development of intergeneric cloned marbled cat embryos up to the morula stage. However, postimplantation development still needs to be investigated.

Assessment of basic seminal characteristics, sperm cryopreservation and heterologous in vitro fertilisation in the fishing cat (Prionailurus viverrinus).

Conservation of the fishing cat, a threatened south-east Asian felid, could benefit from effective ex situ genetic management and breeding programmes, including the use of assisted reproduction. The aims of the present study were to: (1) characterise basal seminal traits of fishing cats in Thailand zoos; and (2) investigate the effect of cryopreservation on sperm motility, acrosomal integrity and in vitro function. Seminal traits were evaluated in electroejaculates collected from eight males. Spermatozoa were diluted in n-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid Tris (TEST)-yolk buffer (TYB) without glycerol, then diluted further with TYB with glycerol (4% final concentration) at either 25 degrees C or after slow cooling to 5 degrees C and frozen in straws over liquid nitrogen vapour. After thawing, sperm function was assessed by insemination of viable domestic cat oocytes. Fishing cat ejaculates averaged (+/- s.e.m.) 43.6 +/- 14.2 x 10(6) motile spermatozoa with 33.5 +/- 6.8% normal sperm morphology. Semen processing had a negligible effect (P > 0.05) on sperm motility and acrosomal integrity, but values were reduced (P < 0.05) after thawing. All thawed samples fertilised domestic cat oocytes, with 62.1% (36/58) of mature oocytes cleaving. Glycerol addition at 5 degrees C resulted in higher (P < 0.05) post-thaw motility and intact acrosomes than glycerol addition at 25 degrees C. In conclusion, good-quality ejaculates can be obtained from Thai fishing cats and their spermatozoa exhibit adequate function after cryopreservation for in vitro fertilisation procedures.

Seroprevalence of Toxoplasma gondii in captive felids in Thailand.

The prevalence of antibodies against Toxoplasma gondii was investigated by commercial latex agglutination test kit (Toxocheck-MT 'Eiken') in captive felids maintained at zoos and a wildlife breeding center in different geographic regions of Thailand. Sera from a total of 136 captive felids of 12 species was obtained between 2002 and 2004. The overall seroprevalence of T. gondii was found in 21 of 136 (15.4%) felids. The titers varied from 1:64 (eight samples) to 1:8192 (one sample). The seroprevalence in different geographic regions were from 0% in the northern area to 23% in the southern area. This study suggested a widespread exposure of captive felids to T. gondii in Thailand and this is the first report of serologic analysis for T. gondii in captive felids in Southeast Asia.

Segregation of donor cell mitochondrial DNA in gaur-bovine interspecies somatic cell nuclear transfer embryos, fetuses and an offspring.

The fate of foreign mitochondrial DNA (mtDNA) following somatic cell nuclear transfer (SCNT) is still controversial. In this study, we examined the transmission of the heteroplasmic mtDNA of gaur donor cells and recipient bovine oocytes to an offspring and aborted and mummified fetuses at various levels during the development of gaur-bovine interspecies SCNT (iSCNT) embryos. High levels of the donor cell mtDNA were found in various tissue samples but they did not have any beneficial effect to the survival of iSCNT offspring. However, the factors on mtDNA inheritance are unique for each iSCNT experiment and depend on the recipient oocyte and donor cell used, which might play an important role in the efficiency of iSCNT.

Full-term development of gaur-bovine interspecies somatic cell nuclear transfer embryos: effect of trichostatin A treatment.

Trichostatin A (TSA) has previously been used in somatic cell nuclear transfer (SCNT) to improve the cloning efficiency in several species, which led our team to investigate the effects of TSA on the full-term development of bovine SCNT and gaur-bovine interspecies SCNT (gaur iSCNT; gaur somatic cells as donors and bovine oocytes as recipients) embryos. Treatment with 50 nM TSA for 10 h after fusion had no positive effects on the rates of fusion, cleavage, or the development to eight-cell or morula stages in both bovine SCNT and gaur iSCNT embryos. However, TSA treatment significantly enhanced the blastocyst formation rate in bovine SCNT embryos (44 vs. 32-34% in the TSA-treated and TSA-untreated groups, respectively), but had no effects on gaur iSCNT embryos. The fresh blastocysts derived from bovine SCNT and gaur iSCNT embryos (fresh groups), as well as vitrified bovine SCNT blastocysts (vitrified group), were transferred to bovine recipients. We found that TSA treatment increased the pregnancy rates only in recipients receiving fresh bovine SCNT embryos. In recipients receiving TSA-treated bovine SCNT embryos, three cloned calves from the fresh group and twin cloned calves from the vitrified group were delivered; however, no calf was born from the TSA-untreated bovine SCNT embryos. In contrast, one gaur iSCNT calf was born from a recipient receiving blastocysts from the TSA-untreated group. In summary, TSA improved the preimplantation development and pregnancy rates of bovine SCNT embryos, but did not have any beneficial effect on gaur iSCNT embryos. However, one gaur iSCNT calf reached full-term development.