In vitro progesterone production of corpus luteum in pregnant Mongolian gerbils (Meriones unguiculatus)

The present study was conducted to determine the in vitro progesterone (P₄) production by Mongolian gerbil (Meriones unguiculatus) corpus luteum (CL) on days 9, 18 and 22 of pregnancy in comparison with rat CL on days 9 and 16. The culture medium of one CL per well of a 96‐well plate was changed after 4 h incubation and the CL were further cultured for 24 h. The P₄ in serum and in the medium were measured by enzyme immunoassay system. Gerbil CL weight measured after 24 h incubation was at the same level for all 3 days of pregnancy and significantly different from that of the rat CL for the 2 days of pregnancy. The serum P₄ level in gerbils was high in early pregnancy and decreased in advanced days of pregnancy. In contrast, the P₄ in rats was higher in the latter half of pregnancy. In vitro P₄ production by a single CL after 4 h incubation decreased significantly during the days of pregnancy in both the gerbil and the rat. P₄ values produced by the gerbil CL for 24 h incubation were significantly higher than after 4 h incubation in all 3 days of pregnancy, however, there was no difference between the two incubation time groups in the rat. In vitro P₄ production by CL correlated well with the serum P₄ level on the 3 days of pregnancy in the gerbil. In the rat, however, the relationship was inversed between the two parameters. The correlation in this experiment suggested that CL is the sole source of P₄ for the maintenance of the gerbil pregnancy, with the result of abortion after an ovariectomy on day 20 of pregnancy as described in our previous report.     

New strategies of boar sperm cryopreservation: Development of novel freezing and thawing methods with a focus on the roles of seminal plasma

Cryopreservation of boar spermatozoa offers an effective means of long‐term storage of important genetic material. Many researchers have investigated how to improve reproductive performance by artificial insemination (AI) using cryopreserved boar spermatozoa. Recently, we and other groups reported that high conception rates (70–80%) can be achieved by AI with frozen‐thawed boar spermatozoa using a modified temperature program during freezing, or a novel cryopreservation extender to improve sperm quality (including sperm survivability, motility, membrane status and fertilization ability) after thawing, or a novel sperm infusion method, deep intra uterine insemination. However, these techniques have not yet been used for commercial pig production. The variation in sperm freezability among boars or among ejaculations in an identical boar is one of the main reasons for this problem. In our previous study, it was revealed that some components of seminal plasma have a negative effect on the freezability of boar sperm. One of these factors is bacteria‐released endotoxin (lipopolysaccharide: LPS). LPS binds to Toll‐like receptor‐4 (TLR‐4) expressed on the sperm surface, resulting in induction of apoptosis. On the other hand, seminal plasma suppresses cryo‐capacitation induced by thawing stress. On the basis of these findings, we designed a novel protocol of AI using frozen‐thawed boar sperm.     

Impaired postnatal development in C/EBPbeta-deficient mice

Tail DNA genotyping of fetal and neonatal mice from C/EBPbeta heterozygous parents was performed to determine whether the decreased number of surviving C/EBPbeta mutants was caused by prenatal or postnatal death. Eighty-four 3-week-old mice born of heterozygous parents had significantly lower numbers of C/EBPbeta-deficient offspring than the expected Mendelian ratio (29.8%+/+, 65.5%+/-, 4.76%-/-, P<0.05). The genotypes of 72 fetal mice from intercrossed heterozygotes showed approximately the expected 1:2:1 Mendelian ratio (18.1% +/+, 52.8% +/-, 29.2% -/-, P>0.05). No difference in the proportions by sex could be detected in these perinates. This data indicates that C/EBPbeta-deficient mice have unknown lethal problems between the embryonic stage and weaning.     

Effects of nutritional status on hormone concentrations of the somatotropin axis and metabolites in plasma and colostrum of Japanese Black cows

We aimed to determine the effects of nutritional status on concentrations of somatotropic axis hormones (growth hormone (GH) and insulin‐like growth factor 1 (IGF‐1)), insulin and metabolites (glucose, total protein and nonesterified fatty acids (NEFA)) in the plasma and colostrum in late antepartum cows. Eight pregnant Japanese Black cows were randomly assigned to two experimental groups (n = 4 per group). Control cows (CON) received 100% of their nutritional requirements until parturition, whereas restricted group cows (RES) received 60% of their nutritional requirements. Blood samples were taken during the antepartum period, and blood and colostrum samples were collected on days 0, 1, and 3 after calving. Compared to the CON group, the RES group had higher concentrations of GH and NEFA in plasma, but significantly lower concentrations of glucose and insulin in plasma. The concentrations of GH in plasma after calving were significantly higher, but total plasma protein was significantly lower in RES than in CON cows. Compared to the CON group, the RES group had significantly higher concentrations of GH in colostrum, but significantly lower total concentrations of protein in colostrum. Concentrations of IGF‐1 were not different between the two groups. These findings suggest that maternal nutritional status during late gestation influences concentrations of GH and total protein in the blood and colostrum of Japanese Black cows.     

Effect of Harpin from Four Pathovars of Pseudomonas syringae on Pea Defense Responses

To investigate the role of the proteinaceous elicitor, harpin, on host and nonhost plants, we isolated the harpin-coding gene, hrpZ, from Pseudomonas syringae pvs. pisi, glycinea, tabaci and tomato. Effects of the recombinant harpin proteins on pea plants were analyzed and compared with the effects of the corresponding bacterial treatment. After inoculation of pea with pea pathogen P. syringae pv. pisi, the bacterial population increased and the accumulation of PAL-mRNA and pisatin was inhibited. The nonpathogenic pathovars, glycinea, tabaci and tomato induced both defense responses in pea. However, none of the harpins induced the hypersensitive reaction or accumulation of PAL-mRNA and pisatin in pea. Harpins from P. syringae pvs. glycinea, tomato and pisi did induce these defense responses in tobacco, however, suggesting that externally applied harpins either are not recognized or are nonfunctional in pea plants. Received 27 June 2000/ Accepted in revised form 21 February 2001     

Properties and classification of selected volcanic ash soils from Abashiri,Northern Japan—transition of Andisols to Mollisols

Abstract

Properties and classification of four selected volcanic ash soils from Abashiri, Hokkaido were studied and the transition of Andisols to Mollisols was discussed. Two of the four pedons (Brown Andosol and Cumulic Andosol)¹ showed morphological, clay mineralogical, physical, and chemical properties common to most Andisols in Japan. However, the properties of the other two pedons (Acid Brown Forest soil and Brown Forest soil)¹ were considerably different from those of common Andisols in Japan. It was found that the changes in the andic soil properties or transition of Andisols to Mollisols was closely related to the progression of clay weathering, mainly the transformation of noncrystalline clay materials to halloysite. One of the four pedons (Brown Forest soil)¹had the clay fraction dominated by halloysite from the uppermost horizon down to the bottom of the profile and satisfied both andic and mollic requirements. Thus we concluded that the pedon is a transitional soil between Andisols and Mollisols and that the transition is closely related to the duration of surface weathering under relatively weak leaching conditions. The four pedons were classified according to the Andisol Proposal (Leamy et al. 1988, New Zealand Soil Bureau) as follows:

Pedon 1: Medial, amorphic (allophane/imogolite), frigid Typic Hapludand (Brown Andosol).¹ Pedon 2: Medial, amorphic (allophane/imogolite), frigid Typic Melanudand (Cumulic Andosol).¹ Pedon 3: Medial, amorphic (allophane/ imogolite), over kandic, frigid Typic Melanudand (Acid Brown Forest soil).¹ Pedon 4: Medial, kandic, frigid Typic Hapludand (Brown Forest soil).¹