Contribution of the type II secretion system in systemic infectivity of <Emphasis Type="Italic">Ralstonia </Emphasis><Emphasis Type="Italic">solanacearum</Emphasis> through xylem vessels

Ralstonia solanacearum strain OE1-1 (OE1-1) systemically invades tobacco plants and causes bacterial wilt. A type II secretion system (T2SS)-deficient mutant of OE1-1, derived from EZ::TN<KAN-2>transposon-insertion, retained the ability of the parent strain to produce exopolysaccharide in vitro and grow in intercellular spaces immediately after invasion of host plants, but lost the ability to systemically infect the host. With transmission electron microscopy, the mutant was not observed in xylem vessels. These findings suggest that the T2SS contributes to systemic infection by enabling the bacteria to invade xylem vessels.     

Use of a regression method to partition sources of ecosystem respiration in an alpine meadow

The partitioning of ecosystem respiration (ER) into plant respiration (PR), aboveground-part respiration (AGR), root respiration (RR), and microbial respiration (MR) components is crucial for understanding the responses of carbon cycling in terrestrial ecosystems to climate change. Here, we present the ER-PB/AGB regression method, which is a modification of the SR-BGB method (PB, plant biomass; AGB, aboveground biomass; SR, soil respiration; BGB, belowground biomass) and is based on the assumption of a linear relationship between biomass and respiration rate for the partitioning of ER into PR, AGR, RR, and MR. Diurnal measurements of CO₂ flux and biomass analysis were conducted in three Kobresia (Kobresia pygmaea, Kobresia humilis, and Kobresia tibetica) meadows on the Qinghai-Tibetan Plateau. We found significant linear relationships between ER and PB/AGB in the three meadows. However, the relationships between measured SR and BGB were either not significant or lower than those between ER and PB/AGB. The relative contributions of respiration components (AGR, RR, MR) to ER decreased consistently in the order AGR > MR > RR in the three Kobresia meadows. The contributions of RR and MR to SR calculated by the proposed ER-PB/AGB method differed widely among the three meadows and were consistently higher (RR) and lower (MR) than those by the SR-BGB method in all three meadows. Compared with the SR-BGB technique, our ER-PB/AGB regression method proved capable of determining more accurately the temporal changes in a larger number of respiration components.     

Three-dimensional common-feature hypotheses of inhibitors of calling behaviour and in vitro [14C]acetate incorporation by pheromone glands of Plodia interpunctella

Some octopamine (OA) agonists were found to suppress the calling behaviour and pheromone biosynthesis in vitro of the Indian meal moth, Plodia interpunctella (Hübner), a stored-product pest. Compounds were screened using a calling behaviour bioassay of female P interpunctella. Three active derivatives, with activity at the nanomolar level, were identified. In order of decreasing pheromonostatic activity these were: 2-(2-ethyl-6-methylanilino)oxazolidine > 2-(2,6-diethylanilino)thiazolidine > 2-(2,6-diethylanilino)oxazolidine. These compounds showed also in vitro inhibitory activities in de novo pheromone biosynthesis. Three-dimensional pharmacophore hypotheses were built from a set of 19 compounds. Among the ten common-featured models generated by the program Catalyst/HipHop, a hypothesis including a ring aromatic group (RA), a positive ionizable group (PI) and two hydrophobic aliphatic (HpA1) features was considered to be essential for inhibitory activity in the calling behaviour and pheromone biosynthesis in vitro. Active compounds mapped well onto all the RA, PI and HpA1 features of the hypothesis. Less-active compounds were shown not to achieve the energetically favourable conformation which was found in the active molecules in order to fit the 3-D common-feature pharmacophore models. The present studies demonstrate that inhibition of calling behaviour and PBAN-stimulated incorporation of radioactivity is by OA-agonistic activity.     

Novel polymorphism of the canine dopamine receptor D4 gene intron II region

Various dog breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of these characteristics are under genetic control. However, little is known about genes related to behavioral traits in canine species. In humans, it has been reported that the dopamine receptor D4 gene (DRD4) includes polymorphism at several regions that relate to personality or psychiatric disorders. In an earlier study by the authors of the present study, the polymorphisms in canine DRD4 exon III and exon I regions were reported. In the present study, a novel polymorphism in canine DRD4 intron II was found based on a 17 base pair insertion/deletion, and the two alleles detected were named P (shorter allele) and Q (longer allele). The allelic distribution in 28 breeds of dog, including a total of 1114 unrelated individuals, were then investigated. Both P and Q alleles were detected in most of the breeds investigated; however, the frequencies of P and Q differed greatly between breeds. With respect to classification based on breed origin, P and Q alleles were frequent in Occidental and Oriental breeds, respectively. Furthermore, two subspecies of wolves, the ancestors of dogs, were analyzed for the comparison of allele frequencies with dogs, and the P allele was predominant in both European and Chinese wolves.     

Quantitative structure—activity studies of some octopaminergic agonists against Periplaneta americana

The quantitative relationship between the structure of 2-(arylimino) thiazolidines (AITs), arylethanolamines (AEAs) and 2-(arylalkylamino)-2-thi-azolines (AATs) and their octopamine (OA)-agonist activities against the ventral nerve cord of American cockroach, Periplaneta americana L., was analysed using reported physicochemical parameters and regression analysis. The electronic nature of a substituent was the most important factor for AAT, followed by the hydrophobic effects: the more electron-donating and the more hydrophobic the substituent, the greater the activity. The hydrophobic nature of a substituent in AEA was the most important factor, followed by the steric effects: the more hydrophobic the substituent, the greater the activity. The more electron-donating the substituent of AIT, the greater the activity.     

Amyloidosis in two Stejneger's beaked whales (Mesoplodon stejnegeri) stranded at the Sea of Japan.

Amyloidosis is a disease characterized by the tissue deposition of autologous extracellular fibrillar proteins that can result in compression of adjacent tissues. Amyloidosis is well-recognized in a wide variety of animals, including mammals, birds, and reptiles. However, to date, there is only one report of amyloidosis in cetaceans. During 1999 and 2000, among 12 Stejneger's beaked whales (Mesoplodon stejnegeri) that were stranded along the Sea of Japan's coast, amyloidosis was found in two whales (case 1, 498 cm, male; case 2, 520 cm, female). For this study population, the prevalence rate of amyloidosis was approximately 17%. These two animals were considered physically and sexually mature based on body length, external features, gonad characteristics, and skeletal features. Livers were notably swollen, fragile, and pale (brownish yellow) on gross examination. A large deposit of amyloid was found in Disse's spaces along with marked atrophy of the hepatocytes. Numerous granulomas, including many nematodes (Crassicauda sp.), were found along with amyloid deposition in the kidneys. Amyloid was also detected in the heart, spleen, adrenal gland, and pancreas. Amyloid in both cases was identified by typical morphology on H&E and Congo red staining. Electron microscopy displayed a typical network of fine fibrils measuring about 11 nm in diameter. This is the first report of amyloidosis in two Stejneger's beaked whales stranded on the coast of the Sea of Japan.     

Effect of dairy manure type and supplemental synthetic fertilizer on methane and nitrous oxide emissions from a grassland in Nasu,Japan

Abstract

It is well known that some fungal species are remarkably tolerant of high copper concentration, although copper is toxic to most fungi (Garraway and Evans 1984). Bedford (1936) and Jurkowska (1952) reported that Penicillium and Aspergillus species can grow in liquid media saturated or nearly saturated with copper sulfate. Okamoto and Fuwa (1974) isolated Penicillium ochro-chloron from the laboratory air, and found that the fungus was able to grow in a medium saturated with copper sulfate.     

Climate change and interspecific interactions drive species alternations between anchovy and sardine in the western North Pacific: Detection of causality by convergent cross mapping

The abundance and recruitment of anchovy Engraulis spp. and sardine Sardinops spp. alternate in a synchronized way across the Pacific. Convergent cross mapping (CCM) indicated that climate change drives the alternation of the two species in the California Current System. However, climate indices patterns in the western North Pacific contrast with those in the eastern North Pacific, despite synchronous species alternations occurring. Therefore, it is of great interest to clarify whether climate change, or any other factors, affects the population dynamics of Japanese anchovy and Japanese sardine in the western North Pacific. Using CCM, we tested whether climate change and interspecific interactions affect the population dynamics of these two species. We found that climate change affected recruitment, and we clarified the spatiotemporal pattern of this effect. This result supports the existing hypotheses that population dynamics are regulated by climate change in the western North Pacific. The present study also detected interspecific interactions between sardine and anchovy, which might promote the alternation of the two species, and has not been reported in other regions.     

Mechanism of disease development caused by a multihost plant bacterium, Pseudomonas cichorii, and its virulence diversity

Pseudomonas cichorii causes rot on lettuce leaves, distinct from the necrotic spots of infected eggplant leaves. On lettuce leaves, P. cichorii invades intercellular spaces through stomata and grows vigorously, causing rot on the leaves. Surprisingly, P. cichorii does not produce pectate lyase, the most important enzyme for degrading plant cell walls. Alternatively, infection with P. cichorii causes heterochromatin condensation and DNA laddering in lettuce cells, followed by induced cell death, which results in disease symptoms. Thus, apoptotic programmed cell death (PCD) is associated with the symptoms on lettuce leaves. Although PCD in P. cichorii-infected eggplant leaves is also associated with necrotic spots caused by the bacteria, there are differences in the responses of the two hosts. P. cichorii harbors the N-acetyltransferase family gene (pat) and the hrp genes (hrp) encoding a type III secretion system, adjacent to an aldehyde dehydrogenase gene (aldH). The virulence of P. cichorii is hrp-dependent in eggplant, but not in lettuce. Furthermore, hrp, pat and aldH are implicated in the diversity of P. cichorii virulence on susceptible Asteraceae species. The involvement of hrp, aldH and pat in bacterial virulence on the respective species has no relationship with the phylogeny of the plants species. When these results are considered together, P. cichorii has multiple virulence determinants. The involvement of not only hrp but also aldH and pat in P. cichorii virulence arose after species diversification of host plants. Host responses implicated in symptom development have been responsible for the development of virulence determinants of P. cichorii.