Ultrastructural study on interaction between a sterile,white endophytic fungus and eggplant roots

Eggplant roots colonized by a sterile, white mycelial endophyte (SWM) were previously found to become highly resistant to Verticillium wilt. SWM alone, however, caused no visible, disease symptoms, such as wilting or necrosis. The mechanism of the symptomless infection by SWM was investigated in this study. Electron microscopy revealed that hyphae of SWM were abundant on and inside the root epidermal cells 2 weeks after inoculation. Many terminal appressoria formed from apical tips of hyphae, and heavy degradation of the host cell walls was evident where hyphae accumulated. By 4 weeks following inoculation, penetration pegs easily breached epidermal cells, and the infection hyphae penetrated outer cortical cells. In response to the hyphal ingress, numerous tubule-like vesicles and membrane-bound, multivesicular bodies accumulated in cortical cytoplasm near the infection sites of the outer cortical cells, but no visible signs of the host reactions were seen in the epidermal cells. Papillae developed at the spaces between cell walls and plasma membranes at the infection sites. The penetration hyphae often grew out of the papillae, but further hyphal ingress was halted in the middle cortical cell layer. By 8 weeks following inoculation, papillae that developed in these cells contained larger amounts of highly electron-dense material and were reinforced by multilamellate, fibrous elements. Hyphae that entered such papillae were confined to them, and the hyphal cytoplasm degenerated. As the result of the activated resistance reactions, root vascular cylinders remained intact, and the host plants did not wilt.     

Visualization of 15O-water flow in tomato and rice in the light and dark using a positron-emitting tracer imaging system (PETIS)

Abstract

¹⁵P-water flow from the roots to the top in tomato (Lycopersicon esculentum Mill.) and rice (Oryza sativa L.) plants was visualized with time using a positron-emitting tracer imaging system (PETIS). The ¹⁵O-water flow was switched on by light and completely stopped in the dark. The flow rate in the stem of tomato and the shoot of rice at a light intensity of 500 μmol·m^?2·s^?1 was 1.9 and 0.4 cm min^?1, respectively.     

The specific antibody to Brachyspira aalborgi in serum obtained from a patient with intestinal spirochetosis

Serum obtained from a patient histopathologically diagnosed as intestinal spirochetosis was investigated serodiagnostically by agglutination test. B. aalborgi which is a human intestinal spirochete reacted strongly with the human serum, while B. pilosicoli which has potential pathogenicity to humans reacted with the serum, but as strongly and its titer was different than the other three species. On the other hand, intestinal spirochetes (Matsumoto isolates) were isolated from the biopsy samples of the patient. The morphological, biochemical, and genetic characteristics of the isolates were very similar to those of B. aalborgi. Furthermore, the protein profiles of the Matsumoto isolates were also similar to those of B. aalborgi but were different than those of B. pilosicoli and B. hyodysenteriae. The reaction profiles of the Matsumoto isolates in immunoblotting were relatively similar to those of B. aalborgi except for a 74 kDa band but were different from those of B. pilosicoli and B. hyodysenteriae. Therefore, we identified the Matsumoto isolates as B. aalborgi and diagnosed the patient with a B. aalborgi infection.     

Canopy structure and productivity of Festuca avundinacea Schreb. swards during vegetative and reproductive growth

Canopy structure, productivity and their relationships were examined in 2-year-old swards of fourteen tall fescue ( Festuca arundinacea Schreb.) strains during the vegetative and reproductive growth stages. During the vegetative growth stage morphological characters, particularly tiller size, were closely associated with productivity. Swards with large tillers showed an effective distribution of the incoming light energy within the canopy and hence low extinction coefficient ( K ) value and high productivity at complete light interception. On the other hand, although there was no apparent correlation between K and the productivity or the whole crop during the reproductive growth stage, the productivities of the reproductive and vegetative tillers were positively and negatively related to K respectively. Leaf area index of the reproductive tillers and their position in the canopy had marked effects on the distribution of the incoming light energy within the canopy and on the productivity of both types of tillers. The productivity of the vegetative and the reproductive tillers is discussed in terms of the effect of the competition for incoming light energy between both types of tillers.     

GnRHa-induced spawning of wild-caught jack mackerel Trachurus japonicus

The jack mackerel Trachurus japonicus is a key commercially exploited fish species in Japan. The rearing experiment often provides information that is useful for understanding the reproductive characteristics of wild stocks; however, there has been no study on spawning in captive T. japonicus. In the study reported here, we induced spawning in T. japonicus caught in the wild by hook and line. Females with fully vitellogenic oocytes and males during spermiation were selected by gonadal biopsy and injected with gonadotropin-releasing hormone analog (GnRHa) mixed in molten coconut butter. This treatment was performed four times in different groups of four females and five to eight males, and each group was maintained in a 3-m³ concrete tank. We observed the first spawning at 1 or 2 days post-injection and collected between 41,690 and 149,450 eggs. Spawning was recorded on 18 consecutive days in one experiment and for 3 days continuously in the other experiments. In the former, spawning ended when the water temperature reached 23 °C and occurred mainly between 2100 and 2400 hours. These results indicate that GnRHa-induced spawning may be useful for evaluating the reproductive characteristics of T. japonicus and obtaining fertilized eggs to conduct larval experiments.     

Free polyamine concentrations in coastal seawater during phytoplankton bloom

SUMMARY: Polyamines are widely distributed in nature and known to have many roles in living organisms. We investigated the concentrations of polyamines together with inorganic nutrients during a summer bloom period in the Seto Inland Sea of Japan. Putrescine and spermidine were the major polyamines in the coastal seawater. The concentrations at 1 m depth varied widely during the sampling period and ranged from 2.0 to 32.6 nM and 1.0 to 14.1 nM. Spermine concentrations were much lower than putrescine and spermidine. In addition, other polyamines (diaminopropane, cadaverine, norspermidine, homospermidine, norspermine) were also detected. Putrescine and spermidine seemed to be significant compounds in dissolved organic nitrogen in coastal seawater.     

Immunoblot analysis of specific antigen bands predictable for Dirofilaria immitis infection in cats

Serial sera from four mongrel cats experimentally inoculated with infectious larvae of Dirofilaria immitis were analyzed by immunoblot patterns against a phosphate buffered saline-extract of D. immitis. Antigen-specific protein bands detected indicate that the low molecular weight bands of 36, 32, 22, 19 and 14 kDa, are predictable for positive adult worm infection, suggesting diagnostic usefulness for adult D. immitis infection in cats.     

Changes in the expression of pituitary gonadotropin subunits during reproductive cycle of multiple spawning female chub mackerel Scomber japonicus

The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively. We applied a quantitative real-time PCR assay to quantify the mRNA expression levels of these GtH subunits. During the seasonal reproductive cycle, FSHβ mRNA levels remained high during the vitellogenic stages, while GPα and LHβ mRNA levels peaked at the end of vitellogenesis. The expression of all three GtH subunits decreased during the post-spawning period. These results suggest that follicle-stimulating hormone (FSH) is involved in vitellogenesis, while luteinizing hormone (LH) functions during final oocyte maturation (FOM). Both GPα and FSHβ mRNA levels remained high during the FOM stages of the spawning cycle and increased further just after spawning. Thus, FSH synthesis may be strongly activated just after spawning to accelerate vitellogenesis in preparation for the next spawning. Alternatively, LHβ mRNA levels declined during hydration and then increased after ovulation. This study demonstrates that chub mackerel are a good model for investigating GtH functions in multiple spawning fish.