Basal area growth and mortality of Betula maximowicziana affected by crown dieback in a secondary forest in Hokkaido, northern Japan

Since the late 1990s, decline of B. maximowicziana Regel has been observed in mature secondary forests in various parts of Hokkaido, northern Japan. To develop a method of thinning for large-timber production of B. maximowicziana, we measured basal area growth and the mortality of 217 trees during a four-year period (1999–2003) in a 90-year-old secondary forest with serious tree damage. We analyzed growth and mortality in relation to the degree of crown dieback (DC), symmetric and asymmetric competition from neighbors, and initial tree size. Individual basal area growth decreased with increasing DC, with increasing symmetric (two-sided) competition, and with decreasing initial tree size. During the four-year period, 4.1% of the observed trees died. Logistic regression analysis revealed that mortality rate increased with increasing DC and with increasing symmetric competition. These results suggest that both growth and mortality rates were affected by the same factors (i.e., DC and symmetric competition). We concluded that the resource for which individuals were competing at the study site was underground, most likely water. Modeled growth and mortality rates can be used to improve the management of damaged forests. A management plan for the damaged study site is proposed.     

First report of plum pox virus infecting Japanese apricot (<Emphasis Type="Italic">Prunus mume</Emphasis> Sieb. et Zucc.) in Japan

For the first time, plum pox virus (PPV) has been detected in commercial Japanese apricot (Prunus mume) trees in Tokyo, Japan. These trees had ringspot or mottle on leaves, color breaking of petals and, occasionally, mild ringspots and malformation on fruits. The virus was identified based on the morphology of virus particles, serology, and RT-PCR. The amplified nucleotide fragment shared 100% identity with a partial coat protein gene of PPV-D isolates.     

Lignification in developing culms of bamboo <Emphasis Type="Italic">Sinobambusa tootsik</Emphasis>

Bamboos are among the largest woody grasses and grow very rapidly. Although lignin is a crucial factor for the utilization of bamboo biomass, the lignification mechanism of bamboo shoots is poorly understood. We studied lignification in the bamboo Sinobambusa tootsik during culm development. Elongation growth began in May and ended in late-June, when the lignin content was approximately half that in mature culms. Thioacidolysis analysis indicated that p-hydroxyphenyl units in lignin formed even at late stages of lignification. The syringyl/guaiacyl ratio varied during culm development. Various lignin precursors were detected in developing culms by liquid chromatography–mass spectrometry. The ferulic acid content decreased from May to June, indicating that ferulic acid was utilized in early stages of cell wall formation. Monolignol glucosides were detected at early stages of lignification, whereas the contents of monolignols, coniferaldehyde, sinapaldehyde, p-coumaric acid, and ferulic acid peaked at later stages of lignification. Therefore, lignin precursors may be supplied differentially during the lignification process. In August, the rate of lignification decreased, although the contents of various lignin precursors peaked, implying that the rate-limiting step in the cessation of lignification in bamboo is transport or polymerization of lignin precursors, rather than their biosynthesis.     

Muscle fiber types,growth and development in the whole myotome of cultured Pacific bluefin tuna Thunnus orientalis

Following the successful development of Pacific bluefin tuna (PBT) aquaculture, it is of considerable importance to determine the muscle fiber types and their growth patterns for future development. Muscle fiber profiles of dorsal ordinary, lateral ordinary (LO) and dark muscles and their growth patterns in PBT from 3.0 to 54.3 kg body weight were studied. Muscle fibers were histochemically stained for NADH-diaphorase and myosin adenosine triphosphatase activity (mATPase), and immunohistochemically stained with S-58 slow-muscle myosin antibody. All muscle fibers in dorsal and LO muscles showed low NADH-diaphorase activity, and acid-labile (pH 4.0 or 4.3) and alkali-stable mATPase activity. In LO muscle adjacent to dark muscle, three intensities of mATPase activity were observed after acid pre-incubation at pH 4.5 or 5.0, and the activity was related to the muscle fiber diameter. In dark muscle, all small and some large fibers stained intensely for NADH-diaphorase activity, related to their high aerobic metabolism. The high-active fibers with NADH-diaphorase in dark muscle were positive for S-58 antibody. Some large fibers in dark muscle showed intermediate NADH-diaphorase activity and high mATPase activity after alkali pre-incubations. These are fast-twitch oxido-glycolytic fibers in dark muscle and transformed to red muscle fibers with increasing body weight.     

Hpa1 secretion via type III secretion system in <Emphasis Type="Italic">Xanthomonas oryzae</Emphasis> pv. <Emphasis Type="Italic">oryzae</Emphasis>

In many Gram-negative plant pathogenic bacteria the type III secretion system (TTSS), encoded by hrp genes, is essential for pathogenicity in the host and induction of a hypersensitive reaction (HR) in nonhost plants. The expression of hrp genes has been suggested to be repressed in complex media, whereas it is induced in planta and under certain in vitro conditions. We recently reported that XOM2 medium allows efficient hrp expression by Xanthomonas oryzae pv. oryzae. In this study, we investigated hrp-dependent secretion of proteins by the bacteria in vitro. Using modified XOM2, in which bovine serum albumin was added and the pH was lowered to 6.0, we detected at least 10 secreted proteins and identified one as Hpa1. This is the first evidence of protein secretion via TTSS in X. oryzae pv. oryzae.     

Hypercalcemia in a dog with resolution of iatrogenic Cushing's syndrome

A six-year-old spayed Pug was presented with crust formation and ulcer on the skin. The patient had received long-term glucocorticoid therapy for treatment of tentatively diagnosed panniculitis. Severe calcification and pyoderma was observed and the patient was diagnosed with iatrogenic Cushing's syndrome and predonisolone was gradually withdrawn. After the withdrawal, the patient developed marked hypercalcemia (15.3 mg/dl) and finally died from renal failure. It is postulated that the eluted calcium from the calcified lesions may have contributed to the high serum calcium level as the underlying disease was not identified on necropsy.     

Phylogenetic analysis of the hemagglutinin (H) gene of canine distemper viruses isolated from wild masked palm civets (Paguma larvata)

Hemagglutinin (H) gene of two CDV isolates, the Haku93 and Haku00 strains, from masked palm civets was molecularly analyzed. H genes of both two CDVs contained one open reading frame encoding 607 amino acids. Nucleotide and predicted amino acid sequences of H gene of the CDV Haku93 and Haku00 revealed high similarity to those of recent field isolates such as the Yanaka and Tanu96, while they showed limited identity to those of old vaccine strains. Potential N-linked glycosylation sites in both Haku93 and Haku00 were identical to other recent CDV isolates. Phylogenetic analysis revealed that the CDV strains derived from masked palm civets were classified into the group of recent Japanese CDV isolates.     

Follicular microvasculature and angiogenic factors in the ovaries of domestic animals

The genetic and molecular mechanisms that control the development of capillary blood vessels during follicular development are beginning to be elucidated. Ovarian follicles contain and produce angiogenic factors that may act alone or in concert to regulate the process of thecal angiogenesis. These factors are ultimately controlled by endocrine, paracrine and autocrine regulation. A recent study indicated that vascular endothelial growth factor (VEGF) plays an important role in the process of thecal angiogenesis during follicular development. We are developing a novel technology for the induction of follicular development using the technique of in vivo gene administration. Here, we summarize the recent progress of our research.     

Melanin biosynthesis as a prerequisite for penetration by appressoria of Colletotrichum lagenarium: Site of inhibition by melanin-inhibiting fungicides and their action on appressoria

Melanin biosynthesis by appressoria was studied in relation to their penetrating ability using tricyclazole [5-methyl-1,2,4-triazolo(3,4-b)benzothiazole], pp 389 [4,5-dihydro-4-methyltetra-zolo(1,5-a)quinazolin-5-one], and pyroquilon [1,2,5,6-tetrahydropyrrolo(3,2,1-i,j)quinolin-4-one], and color mutants of Colletotrichum lagenarium. Tricyclazole at 100 μM inhibited melanin biosynthesis by appressoria of C. lagenairum 104-T, and caused accumulation of 3,4-dihydro-4,8-dihydroxy-1(2H)naphthalenone (DDN) in the culture medium. By contrast, DDN was not detected in culture media of tricyclazole-treated mutant 8015, which is defective in the enzyme involved in the conversion of scytalone to 1,3,8-trihydroxynaphthalene (1,3,8-THN). Vermelone restored melanization of appressoria of albino mutant 79215 and of the parent strain 104-T treated with tricyclazole, pp 389, and pyroquilon; however, scytalone restored melanization only in appressoria of albino mutant 79215. These results indicate that tricyclazole, pp 389, and pyroquilon inhibit the conversion of 1,3,8-THN to vermelone in the melanin biosynthetic pathway of appressoria of C. lagenarium. Colorless appressoria formed in the presence of the three melanin-inhibiting chemicals germinated laterally on nitrocellulose membranes and rarely penetrated the membranes. On the other hand, when pigmented appressoria were restored by application of vermelone in the presence of the three chemicals, lateral germination of the appressoria was largely suppressed, and the membranes were effectively penetrated. From these results, it is concluded that the major effect of tricyclazole, pp 389, and pyroquilon on appressoria of C. lagenarium, causing failure of penetration, is the inhibition of melanization. Effects of the chemicals on other metabolic functions can be precluded as significant factors affecting the penetration process.     

Canine PHA-stimulated adherent cell enhance interferon-gamma production and proliferation of autologous peripheral blood mononuclear cells

Dendritic cells are specialized antigen‐presenting cells with immuno‐modulating functions that are attractive for clinical applications for cancer immunotherapy. This study examined immunostimulatory functions of phytohemagglutinin (PHA)‐stimulated adherent cells (PHA‐Ad cells) from peripheral blood mononuclear cells (PBMCs) in dogs. PHA‐Ad cells enhanced interferon‐γ from autologous PBMC in vitro. PHA‐Ad cells also stimulated antigen‐independent proliferation of peripheral blood lymphocytes. These results suggest that PHA‐Ad cells from PBMC possess a stimulatory function to evoke anti‐tumour immunity and that they demonstrate potential for therapeutic applications in dogs.