Genotypic Analysis of Heading Time on an Indica Rice Cultivar, Nanjing 11

In this paper, the genotype of heading time in Nanjing 11, an indica variety, was analyzed bycrossing with tester varieties, Akihikari ( e1e1 e2e2 e3e3 Se1eSe1e ), Koshihikari ( E1E1E2E2 e3e3 Se1eSe1e ), Nipponbare(E1E1 e2e2 e3e3 Se1Se1 )and Hinohikari(E1E1 E2E2 e3e3 Se1Se1 ), of which the genotypes of headingtime were well known. The results showed genotype of heading time in Nanjing 11 was E1E1 e2e2 E3E3 Se1Se1and also included a recessive inhibitor I-Se1 for photoperiod-sensitivity as well. Meanwhile, the two photoperiod-sensitive genes, E1 and Se1, in Nanjing 11 were also identified by crossing with QTL nearly isogenic lines of Nipponbare, NIL( Hd1 )and NIL( Hd4 )which have complementary effects.     

Impact of earthen waste storage on nitrate concentration of surface water

In 1992 and 2002, investigations on the water quality and hydrology were carried out in a small agricultural catchment where swine waste was stored in earthen waste storage. The in-stream nitrogen loads and the nitrogen inputs on a sub-catchment scale were estimated and compared between 1992 and 2002. For the entire catchment, the estimated nitrogen inputs increased from 22.5 to 32.9 ton year⁻¹ (from 406 to 594 kg ha⁻¹ year⁻¹), whereas the nitrate nitrogen concentration at the outlet was constant—27 mg l⁻¹. In a sub-catchment (area C) with earthen waste storages, the nitrate nitrogen concentrations at the outlet were high, 42–51 mg l⁻¹. In a sub-catchment (area A) with an earthen waste storage, which was not in service since 1990, although the nitrogen inputs were maintained at 390 kg year⁻¹ (53 kg ha⁻¹ year⁻¹), the nitrate nitrogen concentrations at the outlet decreased from 26 to 4.9 mg l⁻¹. With assuming that the nitrogen transport rates for sources except swine waste are equal to the rates estimated for a sub-catchment without earthen waste storage, the in-stream nitrogen loads for area A were estimated to decrease from 1,334 to 94 kg year⁻¹ and the transport rates for area A were estimated to decrease from 3.95 to 0.73. These results suggest that the effluent from earthen waste storage has affected surface water quality two years after the storage was out of service and its effect largely decreased after a decade.     

Effects of vertically transferred 3,3',4,4',5-pentachlorobiphenyl on gene expression in the ovaries of immature Sprague-Dawley rats

We have previously shown that 3,3',4,4',5-pentachlorobiphenyl (PCB-126) vertically transferred from dams potentially exerts a direct effect on the ovaries of offspring and adversely affects female puberty. To investigate its toxicological targets in ovarian tissues, mRNAs encoding representative peptides that regulate follicular development in granulosa cells, theca cells, and oocytes were quantified using ovaries collected on postnatal days (PND) 5, 15, and 24 from the offspring of dams administered oral doses of 0, 1 or 3 microg/kg PCB-126 starting 2 weeks prior to mating and continuing until 20 days after delivery. Quantification using the real-time RT-PCR method revealed that PCB-126 lowered the amounts of mRNAs that encoded the inhibin alpha- and inhibin/activin beta A-subunits from PND 15 onwards; the amounts of mRNAs for inhibin/activin beta B-subunit, follicle-stimulating hormone (FSH) receptor, and aromatase on PND 15; and the amounts of luteinizing hormone receptor mRNA on PND 24 compared with those of the age-matched controls. In contrast, no differences were noted for mRNAs encoding c-kit, growth differentiation factor-9, bone morphogenetic protein-15, or kit ligand for any of the age groups examined. The serum FSH level on PND 24 was higher than that in the control. Since the earliest effects on the mRNAs in the rat ovaries were observed in those expressed in the granulosa cells of the growing follicles after the antral follicles had developed, molecules in granulosa cells but not in oocytes during the early stages of the antral follicles might be the primary targets of vertically transferred PCB-126.     

Effect of group culture and embryo-culture conditioned medium on development of bovine embryos

We investigated the effect of group culture on bovine embryo development, and also investigated the effect of embryo-culture conditioned medium on developmental competence of individually cultured bovine embryos. Slaughterhouse-derived bovine oocytes were matured and fertilized in vitro. The presumptive zygotes were cultured individually or cultured in groups of 2 to 5 embryos with a constant culture density (5 mul/embryo). After 7 days of culture, the rates of embryos developed to the blastocyst stage were significantly higher (P < 0.05) in group cultures of more than 3 embryos/drop than for embryo culture of 1 or 2 embryos/drop. These results suggest a beneficial effect of group culture may be exerted by possible growth promoting factors secreted by embryos. In the next experiment, we investigated the effect of timing of fresh medium replacement on the development of embryos cultured in groups. The blastocyst formation rate was lower when culture medium was replaced freshly on days 2-4 after fertilization than on days 5-6. The blastocyst formation rates of single-cultured embryos were significantly (p < 0.05) increased by the addition of conditioned medium derived from multiple-embryo culture. These results indicate that group culture promotes embryo development and that embryo culture-derived conditioned medium is effective for supporting development of single cultured embryos.     

Degree of RNA silencing and the ability of a viral suppressor vary depending on the cell species in a protoplast system

RNA silencing is a sequence-specific defense mechanism against viruses. As a counterdefense, viruses evolved silencing suppressors to interfere with host silencing. In analyses using protoplasts prepared from cultured cells (BY-2) and mesophyll cells of Nicotiana tabacum and N. benthamiana, viral suppressors differentially functioned in different cell types. This phenomenon has not been discussed in earlier papers on protoplast systems and RNA silencing. In investigations of the cellular activities of viral suppressors and their role in the RNA-silencing pathway, assays with host protoplasts offer many advantages and can complement other in planta assays such as Agrobacterium-mediated transient expression.     

Watercore in Japanese pear (Pyrus serotina Rehder var. ‘Culta’ Rehder). I. Description of the disorder and its relation to fruit maturity

Out of 119 Japanese pear cultivars and selections and 12 Chinese ones and their 9 hybrids, 30 cultivars and selections showed a physiological disorder in the flesh of the fruit while still on the tree. The affected tissues were generally watery and translucent, and tasted sweet, but in some cultivars the area was slightly brown and tasted bitter. Cavities and/or pithiness developed in these areas both on the tree and during storage. Distribution of affected tissues on a transversely cut surface at the equator of the fruits showed 5 different types of appearance. In most cases the affected tissues were observed near or around the vascular bundles.In the most susceptible selection ‘93-3’, a higher percentage of affected fruits and severer symptoms were observed in the later-picked fruits. Greater severity of disorder was also found in the softer and more yellowed fruits with the more soluble solids. Because of several properties common to both the watercore of apples and this disorder, the term ‘Watercore in Japanese pear’ was chosen to describe it.     

Maternal exposure of low dose of TCDD modulates the expression of estrogen receptor subunits of male gonads in offspring

We have analyzed the effects of low-dose transplacental and lactational exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gene expression relating to the dioxin and sexual hormone cascade, and demonstrated the effects on testicular growth and sexual maturation in male offspring rats. TCDD (10 ng/kg) was administered to dams on Days 7 and 14 of gestation, and on Days 0, 7 and 14 after delivery. Gene expression of cytochrome P450 family 1 subfamily A polypeptide 1 (CYP1A1) in the liver of 17-day-old rats was significantly increased compared with controls. Furthermore, expression of estrogen receptors (ER)alpha and ERbeta was significantly increased at 17 and 42 days old, respectively in the testis of TCDD-administered rats compared with controls. Although testicular weight and the seminiferous tubule diameter were increased in 17-day-old rats, there was no difference in the number of germ cells between TCDD-treated and control animals. The expressions of androgen receptor and inhibin subunit genes were not significantly changed. These findings suggest that low-dose exposure of TCDD leads to unusual development of the testis by perturbation of steroid hormone homeostasis.     

Automated ribotyping, a rapid typing method for analysis of Erysipelothrix spp. strains

Automated ribotyping classified 70 Erysipelothrix species strains, previously classified into 14 RAPD patterns and into 63 PFGE patterns, into 27 ribogroups. Twenty-three strains of the 70 analyzed and classified into 13 ribogroups were previously classified into six ribotypes by the traditional ribotyping method. Moreover, automated ribotyping differentiated seven strains that were not differentiated by PFGE. Therefore, automated ribotyping was more sensitive than RAPD and traditional ribotyping, and it might be a useful method for a rapid screening in epidemiological study of strains of this genus, and more accurate results can be obtained when this method is used together with PFGE.     

Spleen-Specific Development of Germinal Centers in Rats Treated with Antithyroid Drugs

The antithyroid drugs (ATDs) methimazole (MMI) and propylthiouracil (PTU) have been used for treatment of hyperthyroidism for more than several decades, despite the fact that they are associated with adverse drug reactions that are thought to be autoimmune mediated. We therefore examined histopathologic responses in the immune system in male and female rats given MMI (2, 20 and 200 mg/kg/day, p.o., in experiment 1; 200 mg/kg/day, p.o., in experiment 3) or PTU (25 and 250 mg/kg/day, p.o., in experiment 2; 200 mg/kg/day, p.o., in experiment 3) for two weeks. In experiments 1 and 2, highest doses of MMI and PTU induced histopathologic changes in the spleen consistent with those in experiment 3 without any changes in the other peripheral lymphoid organs and tissues. In experiment 3, histopathological evaluation of the spleen along with hematological and bone marrow examinations were performed. In both male and female rats, MMI or PTU induced histopathological changes in the spleen characterized by development of germinal centers and an increase in the number of IgG-positive plasma cells in the red pulp; these changes were most prevalent in the MMI-treated female rats. Total red and white blood cell counts were decreased in the MMI-treated male and female rats; lymphocytes and monocytes were lower in male and female rats, respectively. Bone marrow nucleated cells were significantly lower in the MMI-treated males. This is the first study to demonstrate that ATDs induce spleen specific B-cell reactions in rats