Estimation of the fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using minirhizotrons

We estimated fine root biomass in a Japanese cedar (Cryptomeria japonica) plantation using a min-irhizotron technique. Since data obtained from minirhizo-trons are limited to the length and diameter of fine roots observed on minirhizotron tubes, data conversion is necessary to determine the fine root biomass per unit soil volume or unit stand area. We first examined the regression between diameter squared and weight per unit length of fine roots in soil core samples, and calculated the fine root biomass on minirhizotron tubes from their length and diameter. Then we determined conversion factors based on the ratio of the fine root biomass in soil core samples to that on minirhizotron tubes. We examined calculation methods, using a single conversion factor for total fine root biomass in the soil for depths of 0–40cm (Cal1), or using four conversion factors for fine roots in the soil at 10-cm intervals (Cal2). Cal1 overestimated fine root biomass in the lower soil or underestimated that in the upper soil, while fine root biomass calculated using Cal2 better matched that in soil core samples. These results suggest that minirhizotron data should be converted separately for different soil depths to better estimate fine root biomass.     

Lateral resistance of anchor-bolt joints between timber sills and foundations III: numerical simulations of the effect of sill thickness on the effective lateral resistance of multiple anchor-bolt joints

Effective lateral resistance of multiple anchorbolt joints was estimated by considering sill thickness or length/diameter ratios of anchor bolts. Load-slip relationships of single anchor bolt joints were analyzed by the stepwise linear approximation based on the generalized theory of a beam on an elastic foundation and the criterion of “fracture bearing displacement” for several sill thicknesses or length/diameter ratios of anchor bolts. Monte Carlo simulations of the effective lateral resistance of multiple anchor-bolt joints were conducted using the analyzed load-slip curves of single anchor-bolt joints. Effective resistance ratios of multiple anchor-bolt joints were simulated for some combinations of length/diameter ratios of anchor bolts, lead-hole clearances, and number of anchor bolts. The simulated results are: (1) the influence of lead-hole clearance becomes more apparent as length/diameter ratios of single anchor-bolt joints decrease; (2) there is no obvious effect of number of anchor-bolts over the range of 5 to 15; (3) average effective resistance ratios can be adopted for allowable stress design; and (4) reduction of effective resistance ratios should be considered particularly for small length/diameter ratios of anchor-bolt joints.     

Effective sampling method for estimating bending strength distribution of Japanese larch square-sawn timber

Information on the strength distribution of timbers and other wood products seems to have become more important for users and producers after revision of the Japan architectural standard in 1998, which emphasizes the performance requirements of structures. Because there is no way other than expensive destructive tests to collect strength data, many researchers have proposed many inspecting methods for predicting strength by nondestructive evaluation. The most popular method for structural timber is the mechanical grading method based on the relation between Young's modulus (E) and strength () with some linear regression models. On the other hand, it is well known that the proof loading test is superior for obtaining information on the lower tail of distribution. If the E distribution of the objective timbers is known approximately, selecting timbers nearest to the projected E values saves timbers for destructive tests. We examined the alternative sampling method using the reported e- data sets of Japanese larch square-sawn timber. The simulated results showed that the estimated lower tail of the bending strength distribution by the alternative method was a better approximation of the experimental distribution than that derived from the conventional linear regression model.Part of this paper was presented at the 47th Annual Meeting of the Japan Wood Research Society, Kochi, April 1997     

Differential invasion by Sendai virus of abdominal parenchymal organs and brain tissues in cortisone- and cyclophosphamide-based immunosuppressed mice

Pneumotropic virus invasion of parenchymal organs in mice with immunosuppressants is worth studying from an etiopathogenetic viewpoint as an animal model of a compromised host. This study analyzed the invasion by Sendai virus (SeV) of mouse organs in immunosuppressive states induced by cortisone (CO) and cyclophosphamide (CY). After subcutaneous inoculation of CO or CY, or both, in mice infected intra-nasally with SeV, the SeV invasion was investigated by detecting viremia and viral antigen in organs. SeV Nagoya strain and one treatment of CO or CY caused viremia at 18 hr or 3 d, respectively, with infection in tracheal lymph nodes, but not in untreated mice. SeV invaded hepatocytes and splenolymphocytes on days 10 and 5-10, respectively, after infection. CO or CY treatment, three times, induced viral invasion of brain tissues or serious respiratory infection, respectively, but progressive invasion of abdominal parenchymal organs was not different between treated groups. One CO and two CY treatments intensified viral invasion into many organs, maintaining seronegativity. Cerebral blood vessels had the highest incidence of viral antigen in the brain. Astroglial sheets, choroid plexuses, pia maters, and ventricular epithelia tested positive; test-positive neurons were few. SeV MN strain caused progressive invasion of the brain with gliosis and neuronophagy. Blood-brain barrier disruption was caused by virulence of the MN strain. Half the infected mice in two groups treated with CO once and CY twice succumbed to delayed hypersensitivity, suggested by cerebro-microvascular nodulation.     

Traumatic intracerebral hematoma in a dog: MR images and clinical findings

A nine-year-old, male, mongrel dog was unsteady after falling down a set of stairs. The dog exhibited a mildly abnormal gait 2 days after injury, and was not able to stand, with spasticity of the right limbs, 4 days after injury. MR imaging revealed a clearly demarcated mass on the top of the left lateral ventricle that showed mild hyperintensity on T1-weighted images and hyperintensity on T2-weighted images. The authors diagnosed the dog as having a traumatic intracerebral hematoma. This type of case, in which the clinical signs deteriorated due to edema associated with hematoma, is extremely rare.     

Molecular epidemiological analysis of bat rabies viruses in Brazil

A molecular epidemiological analysis was performed in 19 rabies viruses (RVs) isolated from haematophagous, frugivorous and insectivorous bats, in Sao Paulo, Brazil. The authors carried out RT-PCR for amplification of the RV nucleoprotein (N) gene, and determined 1,335 nucleotide sequences of N gene by direct sequencing method. Phylogenetic analysis, which was based on the N gene of Brazilian RV isolates identified presently and previously, revealed that RVs isolated from bats were genetically divided into four lineages had a tendency to depend on the host bat species. The first lineage consisted mainly of haematophagous bat (Desmodus rotundus) isolates, including frugivorous bat (Artibeus spp.) isolates. Other three lineages consisted of insectivorous bat isolates; mainly Eptesicus spp., Molossus spp. and Nyctinomops spp. isolates, respectively. These results indicate a possibility of that there are bat species-specific RV variants in Brazil.     

The discovery of dinotefuran: a novel neonicotinoid

Dinotefuran (MTI-446: (RS)-1-methyl-2-nitro-3-(tetrahydro-3-furylmethyl)guanidine) is a new neonicotinoid commercialized by Mitsui Chemicals. Research led to this novel neonicotinoid by the removal of the chloropyridine or chlorothiazole ring that had been considered as indispensable for neonicotinoides. The research advanced as follows; (1) selection of acetylcholine for the lead compound, (2) recognition of the insecticidal advantages of 3-methoxypropyl compounds, (3) synthesis of (+/-)-tetrahydro-3-furylmethyl compounds by cyclization of the 3-methoxypropyl moiety. It resulted in dinotefuran which has a (+/-)-tetrahydro-3-furylmethyl moiety instead of a halogenated aromatic heterocyclic ring, and belongs to the third-generation neonicotinoids (sub-class: furanicotinyl compounds).     

Attempt to produce nuclear transferred primordial germ cells using electrofusion in domestic chicken

As a step to develop a somatic nuclear transfer technique for avian species, an attempt to produce somatic nuclear transferred primordial germ cells (PGC) in the domestic chicken was carried out. Primordial germ cells and embryonic blood cells (EBC) were collected from 2‐day‐old embryos and the nuclei were transferred from EBC into PGC by electrofusion. The most efficient pearl chain was developed when a 350‐V/cm AC field was applied for 60 s. Cell fusion between PGC and EBC was most effective when 4‐kV/cm DC pulses, 60 µs pulse width, were applied three times to a cell suspension dispersed in 0.2 or 0.25 mol/L saccharose solution. The present results provide basic information for the production of somatic cell nuclear transferred chickens using PGC as the nuclear recipient.