Acute kidney injury induced by protein-overload nephropathy down-regulates gene expression of hepatic cerebroside sulfotransferase in mice, resulting in reduction of liver and serum sulfatides

Sulfatides, possible antithrombotic factors belonging to sphingoglycolipids, are widely distributed in mammalian tissues and serum. We recently found that the level of serum sulfatides was significantly lower in hemodialysis patients than that in normal subjects, and that the serum level closely correlated to the incidence of cardiovascular disease. These findings suggest a relationship between the level of serum sulfatides and kidney function; however, the molecular mechanism underlying this relationship remains unclear. In the present study, the influence of kidney dysfunction on the metabolism of sulfatides was examined using an established murine model of acute kidney injury, protein-overload nephropathy in mice. Protein-overload treatment caused severe proximal tubular injuries within 4 days, and this treatment obviously decreased both serum and hepatic sulfatide levels. The sphingoid composition of serum sulfatides was very similar to that of hepatic ones at each time point, suggesting that the serum sulfatide level is dependent on the hepatic secretory ability of sulfatides. The treatment also decreased hepatic expression of cerebroside sulfotransferase (CST), a key enzyme in sulfatide metabolism, while it scarcely influenced the expression of the other sulfatide-metabolizing enzymes, including arylsulfatase A, ceramide galactosyltransferase, and galactosylceramidase. Pro-inflammatory responses were not detected in the liver of these mice; however, potential oxidative stress was increased. These results suggest that down-regulation of hepatic CST expression, probably affected by oxidative stress from kidney injury, causes reduction in liver and serum sulfatide levels. This novel mechanism, indicating the crosstalk between kidney injury and specific liver function, may prove useful for helping to understand the situation where human hemodialysis patients have low levels of serum sulfatides.     

Memory retention capacity using two different training methods,appetitive and aversive learning,in juvenile red sea bream Chrysophrys major

Memory retention based on appetitive and aversive learning was studied in juvenile red sea bream Chrysophrys major. The fish were individually trained via appetitive and aversive learning. In general, they retained appetitive memories for 30 days, but not for 60 days. Conversely, aversive memory endured for 1 day, but not for 3 days or longer. Analyses at the individual level revealed that some fish retained appetitive memories for 60 days, whereas others lost it within 3 days; this suggests considerable variability in memory retention capacity among individual fish. The memory duration for aversive learning was remarkably short, which should be considered when releasing trained fish into the wild for stock enhancement. Furthermore, the high inter-individual variability suggests that evaluating memory retention capacity through group experiments might lead to overestimation of fishes’ ability.     

Immunological risks of adult T-cell leukemia at primary HTLV-I infection

A small percentage of human T-cell leukemia virus type-I (HTLV-I)-infected individuals develop adult T-cell leukemia (ATL). In animal experiments, inoculation of HTLV-I via the oral route, which is the main route of mother-to-child viral transmission in humans as a result of breastfeeding, induced host HTLV-I-specific T-cell unresponsiveness and resulted in increased viral load. This strongly suggested that the known epidemiological risk factors for ATL (i.e. vertical HTLV-I infection and elevated viral load) are linked by an insufficient HTLV-I-specific T-cell response. Recent findings on the anti-tumor effects of Tax-targeted vaccination in rats and the reactivation of Tax-specific T cells in ATL patients as a result of hematopoietic stem cell transplantation imply promising immunological approaches for the prophylaxis and therapy of ATL.     

Mechanism of DNA chain growth: XV. RNA-linked nascent DNA pieces in Escherichia coli strains assayed with spleen exonuclease

A new method for the detection and assay of RNA-linked nascent DNA pieces has been developed. The method relies on selective degradation by spleen exonuclease of radioactive 5′-OH terminated DNA produced from the pulse-labelled nascent pieces upon alkaline hydrolysis. Analysis with this method in wild type Escherichia coli has shown relatively high proportions of the RNA-linked molecules after shorter pulses and in the smaller pieces, supporting the transient nature of the RNA attachment to the nascent pieces. The RNA-linked nascent DNA pieces are accumulated by both E. coli polAex1 (defective in 5′ → 3′ exonuclease of DNA polymerase I) and E. coli polA12 and polA1 (defective in polymerase of DNA polymerase I), suggesting the requirement of the concerted action of both 5′ → 3′ exonuclease and polymerase of DNA polymerase I for the removal of the RNA attached to the nascent pieces. Most of the nascent DNA pieces accumulated by E. coli ligts7 (defective in DNA ligase) are not linked to RNA, as expected from the direct role of DNA ligase in joining of the pieces. The analysis also has shown that a large portion of the nascent DNA pieces present in the cell under the normal steady-state conditions are not linked to RNA and that the level of the RNA-free DNA pieces is also increased in polA mutants. These findings suggest that the removal of RNA from the nascent pieces is a relatively rapid process and the joining reaction is a rate-limiting step that requires the concurrent action of DNA polymerase and DNA ligase.     

Growth and sesquiterpenoid production by Calypogeia granulata inoue cells in suspension culture

Growth and the production of volatile sesquiterpenoids by a chlorophyllous cell suspension culture from gametophytes of C. granulata, a leafy liverwort, were examined. Glucose was more effective than 2,4-dichlorophenoxyacetic acid for callus induction, and elimination of glucose from the medium resulted in prompt redifferentiation of plantlets. The cells grew photoheterotrophically, but not in the dark. 1,4-Dimethylazulene, a trinorsesquiterpenoid, was produced as the major volatile sesquiterpenoid in the cultured cells; bicyclogermacrene, compound II, an indene-type aldehyde (a trinorsesquiterpenoid aldehyde), compound I and tetrahydro-1,4-dimethylazulene (a trinorsesquiterpenoid) followed in decreasing order. The azulene was produced both in light and the dark, and its yield was proportional to the growth in light. The yield in light was four times higher than that in the dark. The content of 1,4-dimethylazulene was 0.9–10.% and that of total essential oils was 2.0–3.3% of the dry werght of the cultured cells. The quantity, quality, and proportions of the volatile sesquiterpenoids of the cell culture were almost equal to those of intact (original) plants and redifferentiated plantlets. Previous name: Institute of Food Chemistry     

Biomass-dependent emission of environmental DNA in jack mackerel Trachurus japonicus juveniles

Environmental DNA (eDNA) from juvenile jack mackerel Trachurus japonicus was detected in tanks with 1, 3, 10, or 30 individuals per tank. Quantitative PCR using a set of species-specific primers and a probe revealed that the concentration of eDNA increased almost linearly with the density of fish. The coefficient of determination (R²) in the linear regression was lower than values previously reported for freshwater fishes in similar settings.     

Cytoplasmic expression of the JM403 antigen GlcA-GlcNH 3 + on heparan sulfate glycosaminoglycan in mammary carcinomas—a novel proliferative biomarker for breast cancers with high malignancy

The expressions of heparan sulfate glycosaminoglycans (HSGAGs) in breast carcinoma specimens from 60 patients were immunohistochemically investigated using monoclonal antibodies (mAbs) that recognized different epitopes of the glycan structure. Cytoplasmic expression of GlcA-GlcNH ₃ ⁺ on HSGAG was detected in carcinomas at high frequency (58.3%) using mAb JM403, whereas it was almost undetectable in normal breast ducts. This cytoplasmic expression was confirmed using confocal laser scanning microscopy. The expression of JM403 antigen in invasive carcinomas significantly correlated with nuclear atypia score (p?=?0.0004), mitotic counts score (p?=?0.0018), nuclear grade (p?=?0.0061) and the incidence of metastasis to axillary lymph nodes (p?=?0.0061). Furthermore, its expression was significantly correlated with the Ki67-labeling index in 55 invasive carcinomas (p?p? ₃ ⁺ was also expressed in the cytoplasm of normal crypt epithelial cells where Ki67 protein was expressed in the cell nuclei in the proliferative compartment of the human small intestines. To date, HSGAGs have generally been found to exist on cell surface membranes and in extracellular matrices as components of HS proteoglycans, and the negatively-charged sulfated domains on HSGAGs are considered to be important for their functions. However, our present findings indicate that the cytoplasmic expression of the JM403 antigen GlcA-GlcNH ₃ ⁺ on positively charged, non-sulfated HSGAG may be involved in cell proliferation and associated with increased degrees of malignancy. The unordinary carbohydrate antigen of GlcA-GlcNH ₃ ⁺ on HSGAGs recognized by mAb JM403 may represent a novel proliferative biomarker for highly malignant mammary carcinomas.     

Go, a GTP-Binding Protein: Immunochemical and Immunohistochemical Localization in the Rat

The tissue and cellular distribution of a GTP-binding protein, Go, was investigated in the rat by immunochemical and immunohistochemical methods. Because the specific antibody for the alpha subunit of bovine Go (Go alpha) cross-reacted with rat Go alpha, an enzyme immunoassay method developed for bovine Go alpha was applied for measuring the tissue concentration of Go alpha in the rat. Go alpha was detected in all tissues examined except blood cells. The concentration of Go alpha was highest in the CNS (approximately 7.7 and 4.4 nmol/g in the cerebrum and cerebellum, respectively), followed by the pituitary gland and sciatic nerve. Among the other peripheral tissues, relatively high concentrations of Go alpha were observed in the urinary bladder, stomach, and intestines; however, these values were less than 2% of the concentration in the cerebrum. Go alpha in the intestine was located mostly in the muscle layer. Immunohistochemical study showed that Go alpha was associated mostly with the neural elements but not with cells particular to each peripheral organ. Go alpha was also present in the membranes of neuroendocrine cells, including glandular cells in the anterior lobe of the pituitary gland, chromaffin cells in the medulla of the adrenal gland, islets cells in the pancreas, and parafollicular cells in the thyroid. These results indicate that Go is localized exclusively in the nervous tissues and neuroendocrine cells.     

Accumulation of 8-nitroguanine in human gastric epithelium induced by Helicobacter pylori infection

Helicobacter pylori infection causes chronic inflammation, which can lead to gastric carcinoma. A double immunofluorescence labeling study demonstrated that the level of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) apparent in gastric gland epithelium was significantly higher in gastritis patients with H. pylori infection than in those without infection. A significant accumulation of proliferating cell nuclear antigen, a prognostic factor for gastric cancer, was observed in gastric gland epithelial cells in patients with H. pylori infection as compared to those without infection, and its accumulation was closely correlated with the formation of 8-nitroguanine and 8-oxodG. These results suggest that nitrosative and oxidative DNA damage in gastric epithelial cells and their proliferation by H. pylori infection may lead to gastric carcinoma. 8-Nitroguanine could be not only a promising biomarker for inflammation but also a useful indicator of the risk of gastric cancer development in response to chronic H. pylori infection.     

Expansion of human T-cell leukemia virus type 1 (HTLV-1) reservoir in orally infected rats: inverse correlation with HTLV-1-specific cellular immune response

Adult T-cell leukemia (ATL) occurs in a small population of human T-cell leukemia virus type 1 (HTLV-1)-infected individuals. Although the critical risk factor for ATL development is not clear, it has been noted that ATL is incidentally associated with mother-to-child infection, elevated proviral loads, and weakness in HTLV-1-specific T-cell immune responses. In the present study, using a rat system, we investigated the relationships among the following conditions: primary HTLV-1 infection, a persistent HTLV-1 load, and host HTLV-1-specific immunity. We found that the persistent HTLV-1 load in orally infected rats was significantly greater than that in intraperitoneally infected rats. Even after inoculation with only 50 infected cells, a persistent viral load built up to considerable levels in some orally infected rats but not in intraperitoneally infected rats. In contrast, HTLV-1-specific cellular immune responses were markedly impaired in orally infected rats. As a result, a persistent viral load was inversely correlated with levels of virus-specific T-cell responses in these rats. Otherwise very weak HTLV-1-specific cellular immune responses in orally infected rats were markedly augmented after subcutaneous reimmunization with infected syngeneic rat cells. These findings suggest that HTLV-1-specific immune unresponsiveness associated with oral HTLV-1 infection may be a potential risk factor for development of ATL, allowing expansion of the infected cell reservoir in vivo, but could be overcome with immunological strategies.