[Identication of pearl powder and conch powder from different origins by differential scanning calorimetry].

The paper is aimed to establish a methods for identication of pearl powder and conch powder from different origins. Hermetic aluminum pan was used to encapsulate samples. The optimal testing conditions were: heating rate 10 degrees C x min(-1), sample weight 3 mg and nitrogen gas flow rate 40 mL x min(-1). The enthalpy values of pearl powder and conch powder was obvious different. Identication of pearl powder and conch powder by DSC is a practical method for its accuracy, convenience and practificality.

Development and subsequent cryotolerance of domestic cat embryos cultured in serum-free and serum-containing media.

The objectives of this study were to examine the effects of the presence or absence of serum during the in vitro culturing period of domestic cat embryos on their developmental potential into blastocysts as well as their tolerance to cryopreservation using a slow-freezing method. In vitro-fertilized cat oocytes were incubated in a modified synthetic oviduct fluid (mSOF) containing 4 mg/mL bovine serum albumin (BSA) throughout culturing (BSA group) or in mSOF containing 4 mg/mL BSA for the first 3 days followed by mSOF containing 5% fetal bovine serum (FBS group). The developmental potential of the embryos to the blastocyst and expanded blastocyst stages was evaluated 7 days after in vitro fertilization. The blastocysts were frozen-thawed by the slow-freezing method and cultured for 3 days to examine their viability in vitro. There were no differences in the formation rates of blastocysts or expanded blastocysts, or number of cells in the embryos between the two groups. After cryopreservation, the hatching rates of the expanded blastocysts in the BSA group were significantly higher (P<0.05) than those of the FBS group. The postthaw viability of blastocysts was lower than that of expanded blastocysts irrespective of culture medium. These results indicate that the developmental potential of cat embryos cultured in serum-free medium is comparable to those cultured in serum-containing medium. Furthermore, expanded blastocysts produced without serum exhibit better postthaw viability than those produced with serum.

Combination of the somatic cell nuclear transfer method and RNAi technology for the production of a prion gene-knockdown calf using plasmid vectors harboring the U6 or tRNA promoter.

By combining RNAi technology with SCNT method, we attempted to produce transgenic calves with knocked down bPRNP for technological assessments. The respective utilities of type II (tRNA) and type III (hU6) Pol III promoters in mediating plasmid vector-based RNAi for the production of a bPRNP-knockdown calf were compared. Plasmid harboring DNA for siRNA expression was introduced stably into the genome of primary cultured bovine cells. By inserting the transgenic cell into an enucleated bovine egg, SCNT embryos were produced. The ability for SCNT embryos to develop to blastocysts was higher in hU6 based vector groups (44-53%) than in a tRNA group (32%). In all, 30 hU6-embryos and 12 tRNA-embryos were transferred to 11 recipients. Only tRNA-embryos were able to impregnate recipients (6 out of 11 transfers), resulting in four aborted fetuses, one stillbirth, and one live-born calf. The expression of EGFP, a marker, was detected in all six. The bPRNP transcript levels in the nervous tissues (brain, cerebellum, spinal bulb, and spinal cord) from the calf, which was killed 20 days after birth, were reduced to 35% of those of the control calf on average, as determined by qRT-PCR. The PrPC levels, as estimated by western blot were reduced to 86% on average in the nervous tissues. These findings suggest that SCNT technology remains immature, that the tRNA promoter is useful, and that RNAi can significantly reduce PRNP mRNA levels, but insufficient reduction of PrPC levels exists in cattle under these conditions.

[Isolation and nuclear transfer of ES-like cells colonies derived from embryos being cloning of bovine somatic].

In this experiment, it was designed to carry out proliferous culture of bovine blastocysts(day 7) derived from embryos cloned through bovine somatic cell nuclear transfer, isolating and passaging of ES cells. The cells of blastocysts, which were planted on feeder layer, formed small colonies within 24 h. The nest-shape colonies occurred after culturing for 2-3 days. After the colonies in the same shape were isolated and passaged 4-5 times, many different size colonies with monolayer of multi-cells appeared. The colonies that had been passaged 4-5 times were planted into 4-wells multi-dishes without feeder layer. The colonies with monolayer of multi-cells appeared after 24 h, spread all over the bottom of the dishes, emerged epidermis-like cells that appeared reticulate after 4-7 days. These cells were used as donor cells to carry out nuclear transfer. The results showed that 80% (40/50) of the reconstructed embryos cleaved, 5% (2/40) and 2.5% (1/40) of them developed to the morulaes and blastocyst stage, respectively. It revealed that ES-like cells derived embryos constructed through somatic cell nuclear transfer have the developmental potentials.