Factors Influencing the Frequency of Pregnancy Loss among Thoroughbred Mares in Hidaka,Japan

Pregnancy loss in mares is thought to be a main problem associated with reproductive efficiency. To clarify the situation of pregnancy loss in Thoroughbred mares in Japan, the occurrence of pregnancy loss before and after 35 days of gestation was investigated with 1,476 Thoroughbred mares in Hidaka, Japan, from 2007 to 2009. Pregnancy loss on days 17-35 was determined by ultrasound examination between 17 and 35 days after the last mating. Follow-up surveys were conducted between 35 days and foaling to determine pregnancy loss on day 35 until foaling in 843 of these mares. Using multiple logistic regression analysis, we assessed the influence of mare age, reproductive status, twin pregnancy reduction, body condition score (BCS), estrus type in foaling mares (foal heat or not), progesterone therapy, and endometrial cysts on pregnancy loss rates on days 17-35 and on day 35 until foaling in this population of mares. The pregnancy loss rates on days 17-35 and on day 35 until foaling were 5.8% and 8.7%, respectively. The overall pregnancy loss rate (day 17 until foaling, including parturient losses) was 14.7%. Risk factors for pregnancy loss included decrease in BCS between 17 and 35 days, <5 BCS at day 35, mating during foal heat, and endometrial cysts. In all, 14.7% of pregnancies were lost between day 17 and birth, contributing significantly to reduced reproductive efficiency in Thoroughbred mares in Japan. These observations indicate that mares should be maintained at high BCS and should be prevented from mating in foal heat to decrease the pregnancy loss rates.     

Effect of Addition of Al Hydroxides on Changes in Dispersibility and Charge Characteristics of Soils

Using a soil from a newly reclaimed area where high dispersibility of fine particles had led to poor physical properties in the field, changes in dispersibility and charge characteristics after artificial precipitation of Al hydroxides onto the soil were investigated. Al hydroxides were precipitated by neutralization with NaOH of an acidic A1C1₃ solution in which the soil samples were placed.

When the titration rates were changed, no significant differences in dispersibility were observed in the resultant soils. In the systems with the addition of 2 g kg^-1 or less of A1(OH)₃, dispersion ratios of clays were almost identical with those of blank samples although the specific surface areas were reduced. In the systems with 5 g kg^-1 or more of A1(OH)₃, considerable effects of Al hydroxides on reduction of clay dispersibility were recognized (e.g. 10 g kg^-1 addition yielded less than one-third of the original ratio of the clay dispersion). A slightly larger decrease in dispersion was observed by the addition of 15 g kg^-1 or more. As the amount of added Al increased, the amount of negative charges of the soil decreased while that of positive charges increased. The charge characteristics of the system with the addition of 20 g kg^-1 of A1(OH)₃ were closer to those of the adjacent forest soil which was characterized by a very low dispersibility. It was inferred that added Al hydroxides polymerized to form Al polycation species that were not readily exchangeable, neutralizing negative charges of clays, and acting as interparticle bonding between the clays. On the other hand, forest soils were considered to have acquired a physical stability against the dispersion of fine particles as free Al oxides had been accumulated in the process of natural weathering. It was concluded that charge characteristics primarily determined the dispersion and flocculation behavior of soils and that Al hydroxides were important modifiers of charge characteristics of soils.     

Studies on organic acids in paddy field soils with reference to their inhibitory effects on the growth of rice plants

Many Studies (1) have been made on the physiological diseases of rice plants caused by root rot which develops during the plant growth. The view that organic acids; accumulatted in rice paddy soil may be one of the factors impeding the function of roots began only recently to be expressed concerning the low productive paddy fidds. However, studies on the metabolism of these organic acids, especially of saturated lower fatty acids, are mostly fragmental except for a series of studies made by Takai and others (2). To deal with the problem of root injuries and diseases of rice plants, we must establish the magnitude of the organic acid production in relation to the differences in character of soils.     

Selective determination and formation of elemental selenium in soils

A selective method for the determination of elemental selenium in soil was developed and was applied to the study of elemental selenium in soil. (1) Elemental selenium extracted with carbon disulfide from soil was selectively transformed into selenocyanate ion by reacting with potassium cyanide in carbon disulfide. The selenocyanate ion formed was recovered into an aqueous solution and the amount of selenium in the aqueous solution was determined. This method was specific to elemental selenium and did not interfere with the other selenium compounds and soil components. The method was also highly sensitive and enable to determine more than 0.1 μg kg^-1 of elemental selenium in soil. (2) The formation of elemental selenium was confirmed, when a soil was submerged and the redox potential of the soil decreased. The amount of elemental selenium formed was proportional to the selenite content of the soil, indicating that elemental selenium is transformed from selenite upon its reduction.     

Cadmium contamination of soils and rice plants caused by zinc mining IV. Use of soil amendment materials for the control of Cd uptake by plants

In view of the difficulty in practicing water management as a measure to prevent the production of high Cd rice, alkaline or calcareous soil amendment materials were examined, concerning their pH effect on the availability of soil heavy metals.

1. In the experiment conducted on the contaminated paddy field, the essential Cd uptake by the plant occurred after the ear-forming stage and was reduced remarkably by a basal application of the amendment materials followed by top application, depending on the activity of raising the soil pH. Combined use of calcium silicate and fused magnesium phosphate for a basal dressing was most effective on Cd uptake, producing rice of the lowest Cd content, one fifth of the control.

2. The content of Cu in rice also decreased with the treatment to an extent second to Cd, while that of Zn and Pb decreased in straw but hardly changed in rice. Cu seemed fastest in the straw-to-grain movement which was also promoted by the treatments.

3. Soil Cd and Cu were less soluble in 0.1 N HCl solutions than were Zn and Pb, with the application of fused phosphate. Soil Cd became more insoluble in the incubated soil in a submerged condition and its solubility appeared to be depressed by the addition of ammonium sulfate.

4. Based on the good results for the control of high Cd rice obtained through three years' survey in the problem area, it was recommended that these materials be used in sufficient quantity to raise soil pH, taking care not to cause delay in the first growth.     

Disparities in activity levels and learning ability between Djungarian hamster (Phodopus sungorus) and Roborovskii hamster (Phodopus roborovskii)

The Djungarian hamster and the Roborovskii hamster belong to the same genus of Phodopus. However, the Djungarian hamster is tame and shows sedative behavior, while Roborovskii hamster is not tame and shows high levels of locomotor activity. Hyperactivity occurs in animals with tameless behavior. Tameness or tamelessness behavior is very important because tameness helps for breeding and controlling as well as it enables a strong human‐animal bond. In the present study, we examined the relationships between activity levels and cognitive function in Djungarian and Roborovskii hamsters. Three types of behavioral tests were performed to analyze their activity levels, memory and leaning ability. The levels of L‐ and D‐amino acids and monoamines in the brain were then determined. Roborovskii hamsters showed significantly higher locomotor activity than Djungarian hamsters. Memory ability was not significantly different between the two hamsters, but Roborovskii hamsters showed lower learning ability. Brain levels of D‐serine which is related to enhancement in memory and learning ability, were significantly higher in Djungarian hamsters, but the reverse was true for brain dopamine and serotonin levels. These results suggest that these differences in brain metabolism may be related to the behavioral differences between the two hamsters.     

Charge state distribution and hydrogen/deuterium exchange of alpha-lactalbumin and beta-lactoglobulin preparations by electrospray ionization mass spectrometry

Charge state distribution (CSD) and hydrogen/deuterium (H/D) exchange of preparations of alpha-lactalbumin (alpha-Lac) and beta-lactoglobulin (beta-Lg) were investigated using electrospray ionization mass spectrometry (ESI-MS). Storage of alpha-Lac at pH 3 resulted in substantial changes in its CSD, with the emergence of new ion species and shifts toward higher charge state, indicating less stable conformation. ESI spectra of alpha-Lac kept at pH 5.5 for 4 days showed stable conformation; however, extending the storage period resulted in substantial changes in CSD and a decrease in the stability of holo-alpha-Lac (Ca(2+)-bound form). In comparison to apo-alpha-Lac, the relative intensity of holo-alpha-Lac was higher at pH 6.8 but lower at pH 8 during the storage period. beta-Lg showed stable CSD at pH 3, substantial changes at pH 5.5, and minor changes at pH 6.8 and 8 during storage. The H/D exchange results demonstrate that the conformation of holo-alpha-Lac was more stable than that of apo-alpha-Lac and that the conformation of beta-Lg variant B was more stable than that of the beta-Lg variant A. Kinetics of H/D exchange indicated that alpha-Lac and beta-Lg fractions obtained from whey protein preparations have the same or improved conformational stabilities compared to those of alpha-Lac and beta-Lg standards. The presence of four or more hexose residues in alpha-Lac enhanced its conformational stability; the presence of two hexose residues in beta-Lg resulted in a less stable conformation.     

Histological study of granulated metrial gland (GMG) cells in beige (DA-bg/bg) rats

To clarify the roles of granulated metrial gland (GMG) cells for successful pregnancy in rats, GMG cells in beige rats (genotype: DA-bg/bg), whose NK cells show lysosomal dysfunction because of abnormalities in cytoplasmic granules, were examined in mid- and late-pregnancy by light and electron microscopies. The GMG cells of beige rats were significantly less in number than those of the two controls (genotypes: DA-bg/+ and DA-+/+) in mid- and late-pregnancy, and this accompanied a low reproductive performance in the beige rats. The size of intracellular granules in the GMG cells of the beige rats was larger than for the two controls on each corresponding day of pregnancy. These results suggest that the activity of rat GMG cells and peripheral NK cells might be influenced by the beige gene, which is involved in reproductive performance.