Dysfunction of erythropoietin-producing interstitial cells in the kidneys of ICR-derived glomerulonephritis (ICGN) mice

Anemia is a major secondary symptom in chronic renal disorder (CRD), but the precise cause of insufficient production of erythropoietin (EPO) remains unclear owing to the controversial localization of EPO-producing cells in the kidneys. The ICR-derived glomerulonephritis (ICGN) mouse, a new hereditary nephrotic mouse, is an appropriate model of anemia associated with CRD. By using an amplified in situ hybridization technique, we detected and counted the renal EPO-producing cells under both normoxic and hypoxic conditions. The expression levels of renal EPO mRNA were quantified and oxygen gradients were also assessed immunohistochemically. Amplified in situ hybridization clarified that EPO-producing cells were peritubular interstitial cells in the middle region of renal cortex in both ICR and ICGN mice. Hypoxia (7% O2) induced low oxygen tension in proximal tubular epithelial cells of renal cortex, and increased the expression of EPO mRNA and the number of EPO-producing cells in both ICR and ICGN mice. However, hypoxia did not increase the serum EPO levels in ICGN mice. The ICGN mouse is a good model for anemia associated with CRD, and the suppression of EPO protein production in the renal EPO-producing cells is considered to be a potential cause of anemia associated with CRD.     

Association between changes in plasma calcium concentration and plasma tartrate-resistant acid phosphatase activity in periparturient cows

Eight periparturient Holstein Friesian cows were examined for plasma tartrate-resistant acid phosphatase (TRAP) activity to assess the degree of bone metabolic activity and to evaluate the association between the change in calcium (Ca) concentration and bone metabolism during the periparturient period. Milk fever occurred in 1 of 8 cows just after parturition. Plasma TRAP activities did not markedly change in 5 of 8 cows during the experimental period. The changing rate of Ca between preparturition and just after parturition was under -20% in 3 of 8 cows, and low TRAP activities were observed in 2 of these 3 cows. This study suggests that cows with a low TRAP activity are at risk of developing milk fever in comparison to cows with high TRAP activity. Temporary increases of parathyroid hormone were observed in 7 cows, but not in the cow with milk fever.     

Invasion and colonization of mature apple fruit by Erwinia amylovora tagged with bioluminescence genes

Invasion and colonization of mature apple fruit by a transformant of Erwinia amylovora tagged with bioluminescence genes from Vibrio fischeri was examined. The transformant was deposited on cut surfaces of fruit stems, wounds on the shoulders and calyces, injured fruit-bearing twigs of harvested apple fruit, and cut fruit flesh. After incubation in closed stainless steel or plastic boxes at 25°C, fruit were periodically observed with a two-dimensional luminometer. The presence of the transformant in luminous areas was confirmed by isolating it on selective media. E. amylovora, when deposited in fruit stems: (1) can invade mature as well as immature apple fruit; (2) vertically and horizontally spreads and colonizes along vascular bundles, increasing its population; (3) reaches the calyx end and the flesh just under the exocarp within 3–4 days after inoculation; (4) when deposited on cut fruit flesh, irrespective of its maturity, can easily increase its population and survive 2–4 weeks or more at 25°C; and (5) even at the time of fruit maturation, can migrate within twigs rapidly and reaches the abscission layers between fruit-bearing twigs and fruit stems.     

Characterization of the 16S-23S rRNA intergenic spacer regions among strains of the Fusobacterium necrophorum cluster

The 16S-23S rRNA intergenic spacer regions (ISRs) of Fusobacterium necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme were characterized. Products of two sizes, about 360 bp (small) and 530 bp (large), were generated by PCR amplification from the 16S-23S rRNA ISR of all the strains tested. The large and small 16S-23S rRNA ISRs of F. necrophorum exhibited a level of sequence similarity of 93.9% to 99.7% and 94.2% to 98.6% homologies within the species, respectively. Only the large spacer regions in these bacteria contained one or two tRNA genes. F. necrophorum subsp. necrophorum contains the isoleucine and alanine tRNA gene, whereas F. necrophorum subsp. funduliforme contains the isoleucine tRNA gene.     

Determination of the distribution and reaction of polysaccharides in wood cell walls by the isotope tracer technique VII: Double radiolabeling of xylan and pectin in magnolia (Magnolia kobus DC) and comparison of their behaviors during kraft pulping by radiotracer technique

myo-Inositol-[2-³H] and d-glucuronic acid-[6-¹⁴C] were administered simultaneously to a growing stem of magnolia (Magnolia kobus DC) to label xylan and pectin, respectively, in the cell wall. Determination of the radioactivity of nitrobenzene oxidation products and sulfuric acid hydrolysates of the newly formed xylem indicated that xylan and pectin were labeled with ³H and ¹⁴C, respectively. The doubly labeled wood tissue was treated to kraft pulping, and the radioactivity of the pulping black liquor and treated wood tissue were determined at various stages of the pulping to compare the dissolving behavior between pectin and xylan during the pulping. The results showed that pectin was not dissolved as easily as xylan and was not redeposited on pulp fiber at the late stage of the pulping.Part of this report was presented at the 40th Lignin Symposium at Tsukuba, October 1995     

Changes in the strategy of a small-scale jigging fishery for Japanese flying squid Todarodes pacificus off northeastern Japan

Fisheries Science - Long-term fluctuations in the strategy of a small-scale squid jigging fishery for Japanese flying squid Todarodes pacificus off northeastern Japan were evaluated based on time...     

Immunohistochemical characterization of hepatoblastomas in B6C3F1 mice treated with diethylnitrosamine and sodium phenobarbital.

Hepatoblastomas (HBs) were induced in B6C3F1 male mice by diethylnitrosamine (DEN) and sodium phenobarbital (PB). Six-week-old mice received a single intraperitoneal dose of DEN followed by a continuous treatment with PB in diet at a concentration of 0 (group 1) or 500 (group 2) ppm for 50 weeks. HBs were observed in 13 of 21 (62%) group 2 mice, with typical histologic features as reported previously, while no such tumors were observed in group 1. Seven of 13 (54%) HBs were found in and/or adjacent to hepatocellular adenomas (HCAs) or hepatocellular carcinomas (HCCs). Immunohistochemically, all HBs were positive for S-100 protein but negative for keratin, alpha-fetoprotein (AFP), albumin (ALB) and vimentin, while HCC cells occasionally reacted positively for AFP with a mosaic pattern. HCC and HCA cells were occasionally positive for ALB. Non-neoplastic hepatocytes and normal bile ducts were positively stained for ALB and keratin/S-100 protein, respectively. S-100 protein is known to be expressed in many mesenchymal tissues and neoplasms including neuroectodermal elements but negative in cells of the hepatic lineage. Thus, the present immunohistochemical results suggested that mesenchymal differentiation occurs in mouse HB cells as observed in human HBs, one of the most frequent infant liver tumors in humans. Although the susceptibility of mouse HBs to PB-promotion suggests a hepatocytic histogenesis, the present immunohistochemical results support the hypothesis that the mouse HB is derived from pluripotent endodermal stem-like cells.