In particular, maternal prostacyclin (PGI2) is critical for embryo implantation and the action of PGI2 is not mediated via its G protein-coupled membrane receptor, IP, but its nuclear receptor, peroxisome proliferator-activated receptor δ (PPARδ). Recently, several studies have shown that PGI2 enhances blastocyst development and/or hatching rate in vitro, and subsequently implantation and live birth rates in mice. However, the mechanism by which PGI2 improves preimplantation embryo development in vitro remains unclear. Using molecular, pharmacologic and genetic approaches, we show that PGI2-induced PPARδ activation accelerates blastocyst hatching in mice. mRNAs for PPARδ, RXRs (heterodimeric partners of PPARδ) and PGI2 synthase are temporally induced after zygotic gene activation and their expression reaches maximum levels at the blastocyst stage, suggesting that functional complex of PPARδ can be formed in the blastocyst. Carbaprostacyclin (cPGI, a stable analogue of PGI2) and GW501516 (a PPARδ selective agonist) significantly accelerated blastocyst hatching but did not increase total cell number of cultured blastocysts. Whereas U51605 (a PGIS inhibitor) interfered with blastocyst hatching, GW501516 restored U51605-induced retarded hatching. In contrast to improvement of blastocyst hatching by PPARδ agonists, PPAR antagonists significantly inhibited blastocyst hatching. Furthermore, deletion of PPARδ at early stages of preimplantation mouse embryos caused delay of blastocyst hatching, but did not impair blastocyst development. Taken together, PGI2-induced PPARδ activation accelerates blastocyst hatching in mice.

“Jokyoung”, a new bread making wheat cultivar, was developed from the cross between “Seri 82”, a hard white wheat from CIMMYT, Mexico and “Keumkang”, a hard white wheat with high milling rate and early maturing from Korea by National Institute of Crop Sci

A recombinant inbred lines (RILs) consisting of 231 lines, derived from a japonica (Suweon365) and a japonica (Chu-cheongbyeo) rice, was used to investigate the genetic factors affecting cooking and eating quality of rice. Alkali digestion valueloci (QTLs

The elite rice cultivar, Suweon365, shows high level of leaf blast resistance. The number and chromosomal locations of genes conferring the resistance were detected by linkage analysis using DNA markers in the RILs from the cross between Suweon365 and Chu

Genetic diversity of 94 japonica rice was assessed using 81 simple sequence repeat (SSR). All 81 SSR markers generated a total of 351 alleles. The number of alleles ranged from 1 to 16 with a mean of 4.3 alleles per SSR marker. Six of 81 SSR markers showe

Resistance genes to the blast pathogen (Pyricularia grisea Sacc.) were mapped using a recombinant inbred population consisting of 231 lines derived from a cross between the japonica parents, ‘Suwon365’ and Chucheongbyeo. Phenotypic analysis showed that Su

To verify the accuracy of the numerical experiment of Part I, measurements at the matured rice canopy located around Junam reservoir were performed at August 14, 1995. According to the measured data, the foliage temperature recorded the highest value, and the ground temperature was the lowest around noon, and these results coincided with those of the numerical experiment using the combined model of Part I. From the estimation using measured data, the maximum value of the latent heat flux was 380 Wm2, the highest value among energy balance terms, and the energy redistribution ratio of the latent heat flux was averaged as 0.5, the highest values among redistribution ratios. These results are the same as those of the numerical experiment in tendency, but they reveals a little lower in the absolute values than those from the numerical experiment.

To estimate the thermal effect of the vegetation canopy on the surface sublayer environment numerically, we used the combined model of Pielke's1) single layer model for vegetation and Deardorff's2) Force restore method(FRM) for soil layer. Application of present combined model to three surface conditions, ie., unsaturated bare soil, saturated bare soil and saturated vegetation canopy, showed followings; The diurnal temperature range of saturated vegetation canopy is only 20K, while saturated bare soil and unsaturated bare soil surface are 30K, 35K, respectively. The maximum temperature of vegetation canopy occurs at noon, about 2 hours earlier than that of the non-vegetation cases. The peak latent heat fluxes of vegetation canopy is simulated as a 600Wm2 a at 1300 LST. They have higher values during afternoon than beforenoon. Furthermore, the energy redistribution ratios to latent heat fluxes also increased in the late afternoon. Therefore, oasis effect driving from the vegetation canopy is reinforced during late afternoon compared with the non-vegetated conditions.

In order to discuss the differences among the SMAP(Surface Moisture Availability Parameter), by previous researchers on the basis of their own theoretical and empirical background, we assessed the SMAP according to the soil types and volumetric soil water contents. The results are as follows. There are differences among all the five SMAPs. There`s a tendency that the larger grain size, the higher value of parameters. And they divided into two groups for their value: one group has parameters with exponential function and the other with cosine and linear function. The maximum difference between the two groups appears when the volumetric soil water contents are 0.07㎥m^-3 for sand, 0.11㎥m^-3 for loam, 0.12 for clay, and 0.13㎥m^-3 for silt loam. So, these differences must be considered when we estimate the surface evaporation rate. From field data, the paddy field soil around Junam reservoir is classified as a silt, has high wetness, 0.56. So, the parameter obtained from the field measurement is much higher than that of Clapp and Hornberger(1978)`s Table. This study treated the SMAP for a certain point of time in winter season. But if we measured the soil water contents continuously, we could obtain better time-dependent parameter.

It is very important to assess accurately the terms which are included in the heat budget equation of soil surface because they are used in the GCM and meso-scale circulation modeling as well as in the micrometeorological studies. Each terms in the heat budget equation change according to the soil moisture content. So, it is necessary to specify clearly the relations between soil moisture content and these terms. Special experiment with ricrometeorological measurements was executed to study these relations at Environmental Research Center of Tsukuba University, Japan. The results are as follow: 1. The soil moisture contents of 1 ㎝ and 4 ㎝ depth are oscillated with one day period in drying process and the amplitude of variation of l cm depth is greater than that of 4 ㎝. 2. Increase in soil moisture contents due to precipitation result in decrease of albedo with step function. 3. Sensible heat is in reverse proportion to the soil moisture content and latent heat is in direct proportion to it. Latent heat is more sensitive than sensible heat according to the soil moisture variation. Net long wave radiation have high correlation with soil moisture. 4. Comparing with the radiative term with the flux term in wetting process due to precipitation, the energy transfer of the aero and thermodynamic flux is greater than that of the radiative heat flux.