Effects of applied gibberellins and uniconazole-P on gravitropism and xylem formation in horizontally positionedFraxinus mandshurica seedlings

The present study deals with the effects of gibberellins (GA₃ GA₄) and uniconazole-P, an inhibitor of gibberellin biosynthesis, on negative gravitropism and xylem formation in the stems of horizontally positioned, 2-year-oldFraxinus mandshurica Rupr. var.japonica Maxim. seedlings. Each growth regulator (100 g) dissolved in 5 l acetone (50%) was applied to the basal node of the current shoot on May 24, 1995. The same treatment was repeated five times weekly until June 28. Five seedlings were used for each treatment. The seedlings were positioned horizontally 24h after the first application on May 25. Within 5 weeks the horizontal stem of control and GA-treated seedlings exhibited negative gravitropism. In contrast, the application of uniconazole-P inhibited negative gravitropic stem bending. The application of GAs increased the number of gelatinous fibers having thickened cell walls on the upper side of stems. The uniconazole-P application decreased xylem cell formation but did not inhibit the formation of gelatinous fibers. These results indicate that not only the differentiation of gelatinous fibers but also xylem increment is important in the negative gravitropism of horizontally positionedF. mandshurica seedlings. These results also suggest that GAs may be involved in xylem cell :formation rather than the differentiation of gelatinous fibers in this species.Part of this research was reported at the 23rd annual meeting of the Plant Growth Regulation Society of America, Calgary, Canada, July 1996     

An outbreak of teat papillomatosis in cattle caused by bovine papilloma virus (BPV) type 6 and unclassified BPVs

Out of 700 heifers at a local farm in Hokkaido, the Northern island of Japan, 560 (80%) were found to have benign teat tumors. All of the analyzed tumors were macroscopically of the flat-and-round type, and no other types such as rice-grain or frond epithelial type were found. The lesions were characterized by epithelial hyperplasia, acanthosis and hyperkeratosis. Unlike in typical fibropapilloma, fibroplasia of the underlying dermis was not observed. Bovine papilloma virus (BPV) capsid antigen and virus particles were found in basophilic intranuclear inclusions of the stratum granulosum of the epidermis by immunohistochemistry and electron microscopy, respectively. BPV-specific DNA was also detected in the lesions. By means of the polymerase chain reaction (PCR) and DNA sequencing of the PCR products, the viruses causing this outbreak were identified mainly as BPV-6 (64%), partly as unclassified BPVs (14%) and their co-infections (21%). Our findings suggest that this outbreak of benign teat tumors was associated with several BPV types.     

Neurotropism of the 1997 Hong Kong H5N1 influenza virus in mice

The direct transmission of H5N1 influenza A viruses from chickens to humans in Hong Kong in 1997 emphasized the need to have information on the pathogenesis of avian influenza virus infection in mammals. H5N1 influenza viruses isolated from patients during the incident killed experimentally infected mice. The principal lesions of the mice were broncho-interstitial pneumonia and nonsuppurative encephalitis. Infectious viruses and/or viral antigens were detected in the brain as well as in the trigeminal and vagal ganglia but not in the blood of the mice. These findings suggest that the virus reached the brain through the vagus and/or trigeminal nerves following replication in the respiratory mucosa. The results imply that neurotropism of the H5N1 virus in mice is a novel characteristic in the pathogenesis of infection by human influenza virus isolates.     

Interploid crossing overcomes plastome-nuclear genome incompatibility in intersubgeneric hybridization between evergreen and deciduous azaleas

Appearance of albino seedlings caused by plastome-nuclear genome incompatibility was avoided by using polyploid parents in intersubgeneric hybridization between evergreen azaleas and deciduous Rhododendron japonicum f. flavum. Intra- and interploid crosses of 2x or 4x evergreen azaleas with 2xR. japonicum f. flavum showed high capsule set, but their reciprocal crosses failed to set capsules. Green and albino hybrids were obtained from 2x evergreen azaleas × 2xR. japonicum f. flavum crosses where ptDNAs of the green and albino plants were derived from R. japonicum f. flavum (paternal parent) and evergreen azaleas (maternal parents), respectively. All the progenies from the crosses of 4x evergreen azaleas × 2xR. japonicum f. flavum were green triploids with evergreen azalea-specific ptDNA. The efficiency of obtaining green hybrids in interploid crosses was higher than that in intraploid crosses. These results suggest that interploid crosses of 4x evergreen azaleas × 2xR. japonicum f. flavum can overcome plastome-nuclear genome incompatibility between evergreen azalea-specific plastome and the nuclear genome in the resulting hybrid.     

Water-soluble organic materials in paddy soil ecosystem

Abstract

A column experiment was conducted to analyse the composition of organic materials in the leachate from the plow layer and their fate in the subsoil. Water-soluble organic materials in the leachate were fractionated by insoluble polyvinylpyrrolidone (PVP) and ion exchange resins. The content of total organic carbon (TOC) in the leachate increased by the addition of rice straw (RS) to the plow layer soil sample. The leachate contained a constant amount of PVP-adsorbed Fraction, while that of the PVP-non-adsorbed Fraction changed during the 45 day incubation period. In the fractionation using ion exchange resins, the fraction adsorbed onto the anion exchange resin was the major one.

By the connection of a subsoil column to the plow layer soil column with RS, the TOC content in the leachate decreased by percolation into the subsoil sample. In the Anjo soil sample (Yellow Soil), the decrease occurred throughout the incubation period, and about 90% of the PVP-adsorbed Fraction in the leachate decreased by percolation into the subsoil sample. In the Fukushima soil sample (Gray Lowland Soil), the TOC content decreased in the early and middle periods of incubation, while in the late period the decrease was negligible. This decrease of the TOC content by percolation into the subsoil sample was mainly due to retention in the subsoil sample of the Anjo soil, while in the Fukushima soil sample it was due to decomposition and retention. It was considered that easily decomposable organic materials like organic acids were decomposed in the early to middle periods of incubation, while in the late period the contents of such substances in the leachate from the plow layer soil sample with RS were small and the decrease of TOC was negligible.     

Vasculature of the ophthalmic rete in night herons (Nycticorax nycticorax): scanning electron microscopy of corrosion casts

Vasculature of the ophthalmic rete (rete ophthalmicum) in the night heron (Nycticorax nycticorax) was studied using scanning electron microscopy of vascular corrosion casts and light microscopy on tissue sections. Most blood to the eyeball and a lesser volume of blood to the brain passed through the ophthalmic rete via the external ophthalmic artery. The collateral retial arterioles originated from the external ophthalmic artery forming a flat and fusiform-shaped arterial network at the ventrotemporal region of the eyeball. The arterial network was intermixed with a similar complex of the veins from the eye. The ophthalmotemporal artery, which supplied the eyeball posteriorly, and supraorbital and infraorbital arteries, which supplied the eyeball anteriorly, originated from the rete. Blood from the eye, which is a site of potential heat loss, drained into the ophthalmic rete via the ophthalmotemporal vein. On the casts of retial arterioles, slit-like cleavages at branching sites representing flap valves, which might play a role as sluice valves, were seen. In addition, marks of circularly running grooves, which might represent tufts of smooth muscle cells and might contribute to a sphincter activity, were observed. These anatomical specializations of the avian ophthalmic rete, involving parallel arrangement of arteries and veins, may function to facilitate counter-current heat exchange and to regulate blood pressure and volume to the eye and the brain.     

Development of a single-round and multiplex PCR method for the simultaneous detection of Babesia caballi and Babesia equi in horse blood

With the aim of developing more simple diagnostic alternatives, a differential single-round and multiplex polymerase chain reaction (PCR) method was designed for the simultaneous detection of Babesia caballi and Babesia equi, by targeting 18S ribosomal RNA genes. The multiplex PCR amplified DNA fragments of 540 and 392 bp from B. caballi and B. equi, respectively, in one reaction. The PCR method evaluated on 39 blood samples collected from domestic horses in Mongolia yielded similar results to those obtained from confirmative PCR methods that had been established earlier. Thus, the single-round and multiplex PCR method offers a simple tool for the differential diagnosis of B. caballi and B. equi infections in routine diagnostic laboratory settings as well as in epidemiological studies.     

Microanatomy of the terminal air spaces of Baird's beaked whale (Berardius bairdii) lungs

The terminal airways and microvasculature of five adult Baird's beaked whales (Berardius bairdii) lungs have been examined by means of light and scanning electron microscopy of corrosion casts. The respiratory system of the Baird's beaked whale has various anatomical features which allow them to attain great depths and remain submerged for long periods. The whale lung has components including hyaline cartilage and smooth muscle throughout, reaching as far as the peripheral bronchi, sphincters surrounding the terminal bronchioles, the thick alveolar septa with a connective tissue core and a bi-layer capillary bed, and a distinctive venous plexus of the pulmonary veins. The well-developed venous plexuses of the pulmonary vein are found in the interlobular connective tissue, and around the airways and pulmonary arteries with close apposition. The hyaline cartilage throughout the airways may increase the effective dead air space that accommodates most of the air forced from the collapsed alveoli during a dive. The sphincter might serve as a cock for regulating buoyancy and for trapping air in the alveoli to prevent their complete collapse and a sucking in of alveolar tissue as the dive becomes deeper. The venous plexuses might be for pooling the large volume of blood in the lung to conserve oxygen for deep and prolonged diving.     

Detection of sweet and umami taste in the absence of taste receptor T1r3

The tastes of sugars (sweet) and glutamate (umami) are thought to be detected by T1r receptors expressed in taste cells. Molecular genetics and heterologous expression implicate T1r2 plus T1r3 as a sweet-responsive receptor,and T1r1 plus T1r3,as well as a truncated form of the type 4 metabotropic glutamate receptor (taste-mGluR4),as umami-responsive receptors. Here,we show that mice lacking T1r3 showed no preference for artificial sweeteners and had diminished but not abolished behavioral and nerve responses to sugars and umami compounds. These results indicate that T1r3-independent sweet- and umami-responsive receptors and/or pathways exist in taste cells.     

Effects of double harvesting on estimated total digestible nutrient yield of forage rice

We examined the effects of cultivar (Taporuri, Mohretsu, Tachiaoba, and Hinohikari) on estimated total digestible nutrient (TDN) yield of forage rice in double harvesting. The total estimated whole-plant TDN yield (i.e., of the first crop plus second crop) of Taporuri was the highest in double harvesting. In the first crop, the estimated whole-plant TDN yield of Taporuri was the highest. In the second crop, the estimated whole-plant TDN yield of Taporuri was almost the same as those of Mohretsu and Tachiaoba but higher than that of Hinohikari. We also examined the effects of cultivation method (double harvesting or single harvesting) on estimated TDN yield of forage rice. In Taporuri and Mohretsu, the total estimated whole-plant TDN yield was similar in double harvesting and single harvesting. However, in Tachiaoba and Hinohikari, it was lower in double harvesting than in single harvesting. It is important to maximize the amount of nutrition in leaf and stem rather than panicle because the grain is not digested well by cattle. In the double harvesting, the total estimated leaf blade (leaf) TDN yield of Taporuri was higher than that of Hinohikari and almost the same as those of Tachiaoba and Mohretsu. The total estimated leaf sheath plus stem (stem) TDN yield of Taporuri was the highest. In comparison of the total TDN yield of double harvesting with that of single harvesting, the total estimated leaf and stem TDN yields were higher in double harvesting than in single harvesting in all cultivars except for Hinohikari. Thus, double harvesting of Taporuri is an effective way of reducing the overall loss of nutrition from the crop.