Variable response of growth and arbuscular mycorrhizal colonization of maize plants to preceding crops in various types of soils

The effects of the preceding crops, sunflower (mycorrhizal host) and mustard (nonhost), on arbuscular mycorrhizal (AM) colonization and growth of succeeding maize were examined in 17 soils in an attempt to clarify the influence of soil characteristics on the effects of preceding crops. Shoot weight and P uptake of maize planted after sunflower were much higher than those after mustard in 14 soils, although the preceding crop had little effect on soil-P availability. AM colonization of maize after sunflower was much higher than that after mustard. The effect of the preceding crop was eliminated by soil sterilization. These results suggested that the differences in maize growth were caused by differences in the AM colonization. Correlation analysis of the effect of the preceding crop and soil properties showed that the difference in the effects on maize growth could not be explained by soil chemical properties, but only by the AM colonization of the preceding sunflower crop. In one of the 17 soils, however, the effect was not evident despite the higher AM colonization of sunflower. This soil was sterilized, and the effect of inoculation by AM fungi (AMF) on maize was examined. However, it was found that the inoculation increased AM colonization but did not improve maize growth at any P level, suggesting that the effect of AMF was unusually inhibited in this soil by unknown soil physicochemical properties. In most soils, however, the preceding mycorrhizal host crop, sunflower, improved the growth and AM colonization of maize depending on the AM colonization of sunflower.     

Impact of nutrient enrichment in a waterchestnut ecosystem at Takahama-iri Bay of Lake Kasumigaura,Japan

Waterchestnut was shown to be one of the most efficient agents to yield photosynthetic products among aquatic plants in littoral vegetation. Though the plant can be an agent to remove nutrient in agricultural and domestic wastes directly through its waterroots to some extent, waterchestnut plays a great role in removing nutrients through its roots from lake sediments to watercolumn of the lake. Waterchestnut can be choked to death when its leaves are covered completely by the heavy blue-green algal bloom typical in hypereutophic lakes.     

Effect of rapid oligotrophication by an aquatic treatment pilot plant on the microbial community of a mesotrophic Bog

Rapid oligotrophication by the operation of the ‘Bio-filter system’ has changed Doh-Hoh-Numa Bog from a moderate mesotrophic system to the oligotrophic end of such a system. However, the population growth rate of the bacterioplankton community was little affected, and continued to be controlled primarily by the DOC concentration even after the system operation. This DOC concentration was higher during the operation period, although environmental factors relevant to primary production were shifted to the direction of oligotrophication. The natural bacterioplankton community in the bog was shown to modify its physiological kinetics to maintain the growth rate at the optimal level, even when it was exposed to oligotrophication processes with the operation of the ‘Bio-filter system’.     

Paraticulate metals in waters of a typical irrigation river: The River Sakuragawa,Japan

The particulate metallic elements in waters of a water system of the River Sakuragawa and Lake Kasumigaura were measured by the multielement analyses using particle-induced X-ray emission. The heavy metal particulates for environmental standards were less than 0.0001 ppm for Cd, 0.00037 ppm for Cr, and 0.00078 ppm both for Hg and Pb in the river waters. The predominant metal particles in the waters were Fe, Mn, and Zn.     

Gastric adenocarcinoma with ossification in a ferret (Mustela putorius furo)

A 6-year-old female ferret had a firm mass 2 cm in diameter in the pyloric region of the stomach. Histopathologically, the mass was composed of neoplastic proliferation of well-differentiated epithelial cells, showing tubular or glandular growth patterns. Osseous metaplastic foci were often found in the tumor. Tumor cells showed a positive reaction for immunohistochemistry against bone morphogenetic protein-6, an osteogenic factor. A diagnosis of gastric adenocarcinoma with ossification was made.     

Distributive and phagocytic characteristics of hepatic macrophages in five cetaceans belonging to Delphinidae and Ziphiidae

Details of morphology and distribution of hepatic macrophages in cetaceans were investigated using the immunohistochemistry with an antibody (SRA-E5) generated against human macrophage scavenger receptor antigen. Liver samples were obtained from five species of cetaceans (Baird's beaked whales, short-finned pilot whales, Risso's dolphins, bottlenose dolphins, and pantropical spotted dolphins). Except for two species of whales, the number of SRA-E5-positive Kupffer cells was greatest in the perivenous zone (zone 3), followed by the mid-zonal (zone 2) and periportal (zone 1) zones; this distribution pattern was different from that in cattle examined here and previously reported rodents with the highest number in zone 1. The frequency of Kupffer cell in each of zones was significantly different among species, and interestingly, the total mean of the Kupffer cell number in three zones increased as the body-length of species was small. In cetaceans, Kupffer cells in zone 1 appeared larger and more stellate in shape, whereas those in zone 3 were smaller and rounder. All cetaceans but Baird's beaked whales had the black pigment-containing Kupffer cells, with the greatest number in zone 3, and macrophages with the similar pigments were also seen in the hepatic intermediate septa, indicating an active phagocytosis. Most of the black pigments were considered to be lipofuscin and such pigments were not seen in the bovine livers. These results indicate that cetacean hepatic macrophages show differences in the distribution and phagocytosis among hepatic lobular zones, or between cetacean species and terrestrial animals.     

Study of migration of neural crest cells to adrenal medulla by three-dimensional reconstruction

Adrenal medullary cells are derived from the neural crest. To study the formation process of the adrenal medulla in the embryonic period, we visualized chromaffin cells of rat embryos at 13 to 17 days of gestation using anti-tyrosine hydroxylase (TH) antiserum, and created three-dimensional images from serial tissue sections. Between 13 and 15 days of gestation, TH-positive cells (chromaffin cells) migrated from a group of TH-positive cells present dorsal to the adrenal primordium via the medial cranial end of the adrenal primordium into the adrenal primordium. At or after 16 days of gestation, the adrenal capsule was formed except on the ventral aspect of the cranial end of the adrenal gland, from which TH-positive cells penetrated into the adrenal gland. The reconstructed images showed that TH-positive cells were present contiguously from the sympathetic chain ganglia through a group of TH-positive cells ventral to the adrenal gland into the adrenal cortex, and that the group of TH-positive cells ventral to the adrenal gland communicated with the preaortic ganglion present ventral and caudal to the adrenal gland. These results suggest that neural crest cells use the same pathway to migrate to the sympathetic chain ganglia dorsal to the adrenal gland, to the adrenal gland, and to the preaortic ganglion.     

Use of monoclonal antibodies for analyses of Coxiella burnetii major antigens

Monoclonal antibodies (MAbs) to major antigens of Coxiella burnetii were produced. Some of the MAbs to a 62-kDa protein antigen, peptidoglycan protein complex and lipopolysaccharide (LPS) O-chains reacted with other bacteria whereas none of the MAbs to outer membrane proteins and LPS outer-core did. The LPS outer-core and OMPs may be useful antigens for specifically detecting antibodies to C. burnetii.