Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows.

The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle was tested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectal ultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detected follicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P4; EB + P4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P4 and no CR (n = 9); EB + P4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P4 injections were given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P4 were compared to the EB + P4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P4 injection (10.6 +/- 1.2 d) than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size of ovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P4, and the subsequent luteal phase length was increased in animals that were administered EB + P4.     

Involvement of a host erythrocyte sialic acid content in Babesia bovis infection

Host sialic acid (SA) has recently been suggested to play an important role in erythrocyte (RBC) infection by Babesia spp. The present study attempted to further determine the specific type of SAs important in the RBC invasion. Bovine RBC was found to bear abundant alpha2-3-linked SA residues but not alpha2-6-linked SA in nature, confirmed by flow cytometric analysis of the neuraminidase (Nm)-treated RBCs. Lectin-blot analyses revealed the removal of alpha2-3-linked SAs from the 97-, 33-, and 31-kDa bands by the Nm treatment. Addition of the Nm-treated RBCs into an in vitro culture of B. bovis resulted in a decreased population of the parasitized RBCs. The thin smear samples from the cultures were then observed under a confocal laser scanning microscope after staining with the alpha2-3-linked SA-specific lectin: a selective invasion of B. bovis was found only in the intact RBCs bearing the SAs, but not in the desialylated RBCs. Furthermore, a significant reduction of the parasitized RBCs was also observed in the culture supplemented with exogenous 3'-sialyllactose containing the alpha2-3-linked SAs. However, the complete inhibition of parasite proliferation was not achieved in the culture. These findings indicate that while the alpha2-3-linked SA-dependent pathway is needed for highly efficient invasion of host RBCs by B. bovis, there might also be other potential alternative pathways.     

Spindle formation and microtubule organization during first division in reconstructed rat embryos produced by somatic cell nuclear transfer

The present study was conducted to demonstrate the spindle formation and behavior of chromosomes and microtubules during first division in reconstructed rat embryos produced by somatic cell nuclear transfer (SCNT) with cumulus cell nuclei. To demonstrate the effect of oocyte aging after ovulation on the cleavage of SCNT embryos, micromanipulation was carried out 11, 15 and 18 h after injection of hCG. SCNT oocytes were activated by incubation in culture medium supplemented with 5 microM ionomycin for 5 min followed by treatment with 2 mM 6-dimethylaminopurine (6-DMAP) in mR1ECM for 2-3 h. For immunocytochemical observation, the SCNT embryos were incubated with monoclonal anti-alpha-tubulin antibody and then fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Cleavage rates were significantly higher for oocytes collected after 15 and 18 h rather than for those collected 11 h after injection of hCG (56 and 53%, respectively vs. 28%; P<0.05). Premature chromosome condensation occurred before activation of the SCNT oocytes, but adequate spindle formation was only rarely observed. The distribution of microtubules in SCNT embryos after activation was different from those of fertilized and parthenogenic oocytes, i.e., a dense microtubule organization shaped like a ring was observed. Eighteen to 20 h post-activation, most SCNT embryos were in the 2-cell stage, but no nucleoli were clearly visible, which was quite different from the fertilized oocytes. In addition, first division with and without small cellular bodies containing DNA was observed in the rat SCNT embryos in some cases. The present study suggests that reorganization of transferred nuclei in rat SCNT embryos may be inadequate in terms of formation of the mitotic assembly and nucleolar reorganization.     

Comparison of flower color with anthocyanin composition patterns in evergreen azalea

In evergreen azaleas, major anthocyanins were detected from petals of wild species and cultivars by HPLC analysis. Depending on flower color, all samples were divided into three groups: red, purple or white, using the Japan color standard for horticultural plants. The chromatic components a* and b* values of red group samples showed a convergent distribution, whereas those of purple group samples showed a wider distribution. According to the HPLC analysis, red group samples had two to four major anthocyanins, and those of the purple group had two to six major ones. In contrast, no anthocyanins were detected in the white group petals, although anthocyanidins were detected. These results suggest that the anthocyanin constitution of the purple group flowers is more varied than that of the red group flowers, and this wider variety among purple flowers contributes to extending the diversity of flower color in evergreen azalea.     

Varietal differences in phenolic content and astringency in skin and flesh of hardy kiwifruit resources in Japan

Varietal differences in the total phenolic content and astringency in the skin and flesh were determined among the cultivars and local collections of hardy kiwifruit with a ploidy variance found in Japan. The average values of the total phenolic content in the skin and flesh were 2.66 and 0.18 g 100 g⁻¹ FW, respectively. There were large varietal differences in the total phenolic content in the skin in the range of 1.3–5.0 g 100 g⁻¹ FW. Kochi (tetraploid), while Gassan and ‘Mitsuko’ (hexaploid) contained a larger amount of total phenolics. High astringency was found in Gassan, ‘Mitsuko’ and ‘Hoko’ (hexaploids) and Kochi. HPLC analysis showed that the major components of phenolics in the flesh were (+)-catechin, chlorogenic acid, rutin, (−)-epicatechin and quercetin.     

Plantlet regeneration from leaf protoplasts ofPopulus euphratica

Protoplasts were isolated from the leaves of sterile plants ofPopulus euphratica Oliv. by using 1% Cellulase “Onozuka” RS and 0.25% Pectolyase Y-23 in 0.6m of mannitol solution. Protoplasts were cultured in modified Murashige and Skoog's (MS) medium which contained no ammonium ions but was supplemented with BAP (6-benzylaminopurine), 2,4-D (2,4- dichlorophenoxy-acetic acid), and 1% sucrose at the cell density of 9×10⁴/ml. Cell divisions occurred in every culture medium, especially in the medium containing 0.5 mg/l of BAP and 0.1 mg/l of 2,4-D, in which callus was successfully induced by successive culture through cell cluster formation. Shoots were regenerated from the callus, and their growth was enhanced on 1/2 MS medium containing 0.8 mg/l of BAP. Finally, shoots were rooted and plantlets were regenerated on 1/2 MS medium without a hormone. A part of this paper was presented at the 106th Annual Meeting of the Jpn. For. Soc. (1995).     

Evaluating the durability of wood-based panels using internal bond strength results from accelerated aging treatments

In this study, the durability of wood-based panels was evaluated by comparing the internal bond (IB) strength retention after five different laboratory-based accelerated aging tests with the IB retention after 5 years of outdoor exposure in Shizuoka City. In each accelerated aging test, the IB retention of MDI-bonded panels showed high retention compared to other panels. Outdoor exposure in Shizuoka City resulted in an IB retention value for particleboard (PF) and oriented strandboard (aspen) of less than 10% after the 5-year exposure period. Medium-density fiberboards maintained their initial IB strength over the same period. Calculation of the mean IB retention for all board types allowed comparison of the severity of aging between the accelerated test methods and outdoor exposure. The ASTM six-cycle test method was the most severe among the standard treatment cycles applied.