Epibiotic microorganisms associated with microcrustaceans in overlying water of Philippine paddy fields

Epibiotic microorganisms associated with micro crustaceans in the overlying water of Philippine paddy fields were examined by scanning electron microscopy, and their associations were compared with those observed in Japanese paddy fields (Soil Sci. Plant Nutr., 43, 633-641, 651-664, 1997). Various types of microorganisms, including bacteria, protozoa, and algae, colonized microcrustaceans and their kinds and colonizing patterns varied depending on the kinds of microcrustaceans. Common associations between epibionts and respective micro crustaceans were observed in the Philippines and in Japan: e.g., rodshaped bacteria on Cyclopidae and Cypridopsidae; no microorganisms on Simocephalus spp.     

K/Ca and NH4/Ca selectivity of hydroxyaluminum-interlayered vermiculite and montmorillonite: Contribution from regular and frayed edge exchange sites

Cation distribution in adsorbed and solution phases and their mobility in the soil profile are largely influenced by the cation exchange capacity and selectivity coefficient of the soil. Vermiculites (Vt) and montmorillonites (Mt) in acid soils and sediments are frequently interlayered by hydroxyaluminum (HyA). Such interlayering causes significant changes in various properties of Vt and Mt. We evaluated the contribution of HyA-induced frayed edge sites (FES) in Vt and Mt to the overall selectivity of K/Ca and NHJCa. A more preferential adsorption and exchange of K to Ca was observed in the case of Vt in contrast to Mt. The overall K/Ca selectivity of Vt increased markedly by HyA-interlayering, whereas that of Mt was slightly affected. An increased overall K/Ca selectivity, especially of Vt was also observed due to the larger amount of HyA adsorption at higher initial basicity of the HyA ionic solution. Selective adsorption of K and NH₄ predominantly occurred on the FES. Interlayering substantially enhanced such FES contribution. The overall K/Ca and NH₄/Ca selectivity coefficients did not indicate any striking competitiveness of NH₄ with K, unlike that for the natural micaceous clay minerals. However, the parameter of FES contribution suggested that NH₄ could be slightly more competitive with K for the FES. The relative abundance of FES on different clay specimens determining K/Ca and NH₄/Ca selectivity and a slightly higher preference of NH₄ to K on FES played a major role at low K or NH₄-saturation.     

Biosafety assessment of transgenic poplars overexpressing xyloglucanase (AaXEG2) prior to field trials

We performed biosafety assessments of transgenic poplars prior to field trials. Constitutive expression of the Aspergillus aculeatus xyloglucanase in Populus alba increased the cellulose content and specific gravity of its stem, the leaves of which were visibly greener, thicker, and smaller than those of the wild-type plant. Although the young transgenic poplars grew faster than the wild type in a growth chamber, there was no distinguishable difference in growth between the poplars when they were placed in a special screened greenhouse. Allelopathic tests showed that the transgenic poplars do not produce harmful substances. Based on all the biosafety assessments and the scientific literature on poplar species, we came to the conclusion that transgenic poplars probably do not disturb the biological diversity of the surrounding environment, even when they are submitted to field trials.     

Effects of β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin in β‐carotene‐deficient Japanese Black cows

Data from 18 β‐carotene‐deficient Japanese Black cows were collected to clarify the effects of feeding β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin (Ig) in cows. Cows were assigned to control or carrot groups from 3 weeks before the expected calving date to parturition, and supplemental β‐carotene from dry carrots was 138 mg/day in the carrot group. Plasma β‐carotene concentrations in the control and carrot groups at parturition were 95 and 120 μg/dL, and feeding dry carrots slightly improved plasma β‐carotene at parturition. Feeding dry carrots increased colostral IgA concentrations in cows and tended to increase colostral IgG₁, but colostral IgM, IgG₂, β‐carotene and vitamin A were not affected by the treatment. Feeding dry carrots had no effects on plasma IgG₁, IgA and IgM concentrations in cows, but plasma IgG₁ concentrations decreased rapidly from 3 weeks before the expected calving date to parturition. These results indicate that feeding β‐carotene‐enriched dry carrots is effective to enhance colostral IgA and IgG₁ concentrations in β‐carotene‐deficient cows.     

Presence of chlorogenic acid during in vitro maturation protects porcine oocytes from the negative effects of heat stress

Chlorogenic acid (CGA) is known to protect oocytes from oxidative stress. Here we investigated the effects of CGA on porcine oocyte maturation under heat stress and subsequent embryonic development after parthenogenetic activation. For in vitro maturation (IVM) at 41.0°C (hyperthermic condition), supplementation of the maturation medium with 50 μM CGA significantly improved the percentage of matured oocytes and reduced the rate of apoptosis relative to oocytes matured without CGA (p < .05). CGA treatment of oocytes during IVM under hyperthermia tended to increase (p < .1) percentage of blastocyst formation after parthenogenesis and significantly increased (p < .05) the total cell number per blastocyst relative to oocytes matured without CGA. For IVM at 38.5°C (isothermic condition), CGA significantly improved the rate of blastocyst development compared with oocytes matured without CGA (p < .05), but did not affect oocyte maturation, apoptosis rate or the number of cells per embryo. Omission of all antioxidants from the IVM medium significantly reduced the rate of oocyte maturation, but the rate was restored upon addition of CGA. These results demonstrate that CGA is a potent antioxidant that protects porcine oocytes from the negative effects of heat stress, thus reducing the frequency of apoptosis and improving the quality of embryos.     

Effects of duration of electric pulse on in vitro development of cloned cat embryos with human artificial chromosome vector

The current applications for cat cloning include production of models for the study of human and animal diseases. This study was conducted to investigate the optimal fusion protocol on in vitro development of transgenic cloned cat embryos by comparing duration of electric pulse. Cat fibroblast cells containing a human artificial chromosome (HAC) vector were used as genetically modified nuclear donor cells. Couplets were fused and activated simultaneously with a single DC pulse of 3.0 kV/cm for either 30 or 60 μs. Low rates of fusion and embryo development to the blastocyst stage were observed in the reconstructed HAC‐transchromosomic embryos, when the duration of fusion was prolonged to 60 μs. In contrast, the prolongation of electric pulse duration improved the embryo development and quality in the reconstructed control embryos without HAC vector. Our results suggested that the optimal parameters of electric pulses for fusion in cat somatic cell nuclear transfer vary among the types used for donor cells.