Performance of Bangladesh indigenous rice in a weed infested field and separation of allelopathy from resource competition

This study aimed to identify the potential allelopathic indigenous rice (Oryza sativa L. ssp. indica) varieties from Bangladesh using a performance study in a weed‐infested field and to assess the extent of allelopathic interference relative to resource competition in a glasshouse experiment. Six varieties – namely, “Boterswar,” “Goria,” “Biron” and “Kartiksail” as the most allelopathic, “Hashikolmi” as weakly allelopathic and “Holoi” as nonallelopathic – were raised following a nonweed control method. The infestation levels of weed species were calculated using Simpson's Diversity Index (SDI), which ranged from 0.2 to 0.56. However, a significant correlation coefficient (0.87, P < 0.001) was obtained from these field data compared with the root inhibition percentage from the laboratory bioassay, and the “Boterswar” variety was the most allelopathic. The interactions between the allelopathic variety “Boterswar,” weakly allelopathic variety “Hashikolmi” and Echinochloa oryzicola via a target (rice)‐adjacent (E. oryzicola) cogrowth culture were determined in a hydroponic arrangement. The relative competitive intensity (RCI) and the relative neighbor effect (RNE) values showed that the crop–weed interaction was facilitation for “Boterswar” and competition for “Hashikolmi” and E. oryzicola in rice/E. oryzicola cogrowth cultures. The allelopathic effects of “Boterswar” were much higher than the resource competition in rice/E. oryzicola cogrowth cultures. The converse was observed for “Hashikolmi.” Moreover, the mineral content of E. oryzicola was severely affected by “Boterswar”/E. oryzicola cogrowth cultures’ exudate solution. Therefore, the allelopathic potential of “Boterswar” variety might be useful for developing the weed‐suppressing capacity of rice, which will likely have a significant influence on paddy weed control.     

Genetic analysis for sow stayability at different parities in purebred Landrace and Large White pigs

Genetic parameters for sow stayability were estimated from farrowing records of 10,295 Landrace sows and 8192 Large White sows. The record for sow stayability from parity k to parity k + 1 (k = 1, …, 6) was 0 when a sow had a farrowing record at parity k but not at parity k + 1, and 1 when a sow had both records. Heritability was estimated by using single-trait linear and threshold animal models. Genetic correlations among parities were estimated by using two-trait linear–linear and single-trait random regression linear animal models. Genetic correlations with litter traits at birth were estimated by using a two-trait linear–linear animal model. Heritability estimates by linear model analysis were low (0.065–0.119 in Landrace & 0.061–0.157 in Large White); those by threshold model analysis were higher (0.136–0.200 & 0.110–0.283). Genetic correlations among parities differed between breeds and models. Genetic correlation between sow stayability and number born alive was positive in many cases, implying that selection for number born alive does not reduce sow stayability. The results seem to be affected by decisions on culling made by farmers.     

Changes in rat uterine and cervical phospholipase A2 activity following progesterone agonist or antagonist administration at term

Our previous study revealed that a fall in plasma progesterone (P(4)) level was associated with a transient increase in cytosolic phospholipase A(2) (PLA(2)) activity and prostaglandin F(2)alpha level in the rat uterus and cervix during natural parturition. This study determined the changes in the PLA(2) activities during modulated occurrence of delivery by P(4) antagonist or agonist late in pregnancy. In rats undergoing P(4) antagonist-induced preterm delivery, the PLA(2) activities of both uterine and cervical cytosol significantly decreased 12 h after the challenge and tended to be attenuated within 72 h. The plasma P(4) level altered in a similar pattern. Blockade of delivery by chronic treatment with P(4) agonist was not associated with changes in uterine PLA(2) activity compared with that in normally delivering rats, although there was a persistent rise in cervical PLA(2) activity. The obtained data indicates that the PLA(2) activities in rat uterine and cervical cytosol are not regulated solely by P(4) and that delivery can occur without activation of this enzyme.     

Detection of canine distemper virus antigen in canine serum and its application to diagnosis

Canine distemper virus (CDV) antigen was detected in the serum of dogs by an ELISA and the results of this assay were compared with an anti-CDV immunoglobulin M (IgM) antibody test. In paired sera from 26 naturally infected dogs, the antigen-positive rate was 26.9 per cent at the first examination and 11.5 per cent at the second examination two to three weeks later. The antigen was detected in three of the 10 dogs which were negative for anti-CDV IgM antibody at the first examination. It could also be detected in the serum of between eight and two of 40 specific pathogen-free dogs vaccinated against CDV, for up to four weeks after they were vaccinated.     

Detection of DNA restriction fragment polymorphisms in Streptococcus equi

Large-restriction-fragment (LRF) polymorphisms in Streptococcus equi (S equi subspecies equi) were studied by pulsed-field gel electrophoresis. Five or six chromosomal fragments of between 194 and 915 kb were separated by digestion with the restriction endonuclease Notl. All 20 isolates of S equi, including 12 from independent Japanese outbreaks, four from independent American outbreaks, two from a single Irish outbreak, us vaccine strain F43, and type strain NCTC 9682 were successfully typed. Seven distinctive, reproducible and stable types were identified. The 12 Japanese isolates collected between 1992 and 1998 were of LRF type II suggesting that they were derived from the same source. The remaining eight isolates were of six types. The results indicate that LRF typing should be a useful technique for investigating the source and transmission of S equi.     

Ultrastructural study on scab resistance expressed in epidermal pectin layers of pear leaves

Proliferation and collapse of subcuticular hyphae of Venturia nashicola race 1 were studied ultrastructurally, after inoculation of susceptible Japanese pear cv. Kousui, resistant Japanese pear cv. Kinchaku, resistant Asian pear strain Mamenashi 12 and nonhost European pear cv. Flemish Beauty leaves, to understand the nature of the resistance mechanism. After cuticle penetration by the pathogen, the hyphae were observed at lower frequency in epidermal pectin layers and middle lamellae of leaves of the three resistant plants than in those of susceptible ones. This result suggested that fungal growth was suppressed in the incompatible interaction between pear and V. nashicola race 1. In the pectin layers of all inoculated plants, some hyphae had modifications such as breaks in the plasmalemma with plasmolysis, necrotic cytoplasm and degraded cell walls. More hyphae had collapsed in the leaves of the three resistant plants than in those of the susceptible cv. Kousui. In collapsed hyphae, the polymerized cell walls broke into numerous fibrous and amorphous pieces, showing that the scab resistance might be associated with cell wall-degrading enzymes from pear plants.     

Neutrophilic nodules in the intestinal walls of Japanese monkeys associated with the neutrophil chemotactic activity of larval extracts and secretions of Oesophagostomum aculeatum

High neutrophil chemotactic activity was detected in the culture medium from Oesophagostomum aculeatum larvae in vitro using blind-well chambers with Millipore filters, and guinea pig leucocytes as indicator cells. Neutrophil chemotactic activity was also detected in the extract from larval worms in a dose dependent fashion. This activity was detected in the low molecular weight fractions adjacent to a sodium chloride marker by gel filtration on Sephadex G200. These results were further confirmed with monkey neutrophils. The possible role of this activity in the formation of granulomatous lesions rich in neutrophils found in O aculeatum infections in the Japanese monkey is discussed.     

Cultivation of shiitake in sugi wood meal II: effects of seasoning treatment for wood meal on mycelial growth

The effects of seasoning treatment for fresh sugi wood meal on the mycelial growth of shiitake was investi-gated. The mycelial growth of shiitake in sugi wood meal increased to the same level as that in extract-free sugi wood meal on the 12th day and to approximately 70% of that in konara wood meal on the 28th day of the seasoning treatment. A drastic decrease in extracts of fresh sugi wood meal occurred during the early stage of treatment, and the neutral fraction of methanol extracts decreased to less than 2%. The drainage of sugi wood meal media significantly increased during the later stage of treatment. No changes in the chemical components of sugi wood meal were detected during the seasoning treatment. The mycelial growth of shiitake in the fully seasoned sugi wood meal, which was prepared for commercial mushroom cultivation, was at almost the same level as that in the extract-free sugi wood meal. All of the seasoned sugi wood meals contained a neutral fraction of less than 1%. These results suggested that seasoning treatment can promote mycelial growth of shiitake in sugi wood meal by eliminating inhibitors and improving the physical properties of sugi wood.Part of this paper was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Somatic embryo culture for propagation,artificial seed production,and conservation of sawara cypress (<Emphasis Type="Italic">Chamaecyparis pisifera</Emphasis> Sieb. et Zucc.)

 Somatic embryogenesis in Chamaecyparis pisifera Sieb. et Zucc. was initiated from immature seeds collected from the end of June to early July. Mass propagation through adventitious shoot bud production from somatic embryo culture on Woody Plant (WP) medium and artificial seed production using sodium alginate was achieved. A high bud forming index value (25.8) was obtained on medium supplemented with 1 μM 6-benzylaminopurine. The conversion rates from artificial seeds under aseptic and nonaseptic conditions were 60%–100% and 10%–12%, respectively. For germplasm conservation, somatic embryos and embryogenic cells were successfully stored at 4°C (medium-term storage) and in liquid nitrogen for long-term storage. Received: December 21, 2001 / Accepted: August 1, 2002 Acknowledgments This work was supported in part by the Japan Science and Technology Corporation and in part by a Grant for Research for the Future Program from the Japan Society for the Promotion of Science. Correspondence to:E. Maruyama     

Liquid culture and transformation of hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.)

Hinoki cypress (Chamaecyparis obtusa) is one of the most important timber resource forest trees in Japan. Because seed production from a seed orchard of hinoki cypress is not constant every year, micropropagation from a limited amount of material is useful. Up to now, the conventional tissue culture method using solid medium has been used. Here a new method using liquid culture in tubes rotated vertically is described. Shoot primordium of hinoki cypress was inoculated in Campbell and Durzan’s (CD) liquid medium containing different cytokinins (6-benzylaminopurine (BAP), Zeatin, thidiazurone (TDZ)), and the container tubes were rotated vertically around the axis at 2 times / min. Culture room temperature was 25°C and light condition was 16 h photoperiod per day of fluorescent lamps. Zeatin at 1μM concentration was the best for maintaining the shoot primordium production and TDZ induced callus on the surface of the shoot primordia. After shoot primordium multiplication in the liquid culture, they were transplanted to agar medium for shoot elongation. A high concentration of agar (up to 16 g/L) or AVF (anti vitrification factor from Dr. Nairn, 1995) was effective to prevent vitrification of the shoots. Transformation of shoot primordium was done using particle bombardment with vectors containingβ-glucuronidase (GUS) gene or herbicide resistance gene (bar). Positive result for transient transformation was observed with the histo-chemical study for transformation with GUS. Integration of a useful herbicidebar gene into the shoot primordium culture system was also tried and stably transformed plants were obtained. This is the first report of stable transformation of Japanese conifer using practically useful gene. The generous supply of AVF-B from Dr. B.J. Nairn, Tasman Forestry, NZ is also appreciated.