In vitro progesterone production of corpus luteum in pregnant Mongolian gerbils (Meriones unguiculatus)

The present study was conducted to determine the in vitro progesterone (P₄) production by Mongolian gerbil (Meriones unguiculatus) corpus luteum (CL) on days 9, 18 and 22 of pregnancy in comparison with rat CL on days 9 and 16. The culture medium of one CL per well of a 96‐well plate was changed after 4 h incubation and the CL were further cultured for 24 h. The P₄ in serum and in the medium were measured by enzyme immunoassay system. Gerbil CL weight measured after 24 h incubation was at the same level for all 3 days of pregnancy and significantly different from that of the rat CL for the 2 days of pregnancy. The serum P₄ level in gerbils was high in early pregnancy and decreased in advanced days of pregnancy. In contrast, the P₄ in rats was higher in the latter half of pregnancy. In vitro P₄ production by a single CL after 4 h incubation decreased significantly during the days of pregnancy in both the gerbil and the rat. P₄ values produced by the gerbil CL for 24 h incubation were significantly higher than after 4 h incubation in all 3 days of pregnancy, however, there was no difference between the two incubation time groups in the rat. In vitro P₄ production by CL correlated well with the serum P₄ level on the 3 days of pregnancy in the gerbil. In the rat, however, the relationship was inversed between the two parameters. The correlation in this experiment suggested that CL is the sole source of P₄ for the maintenance of the gerbil pregnancy, with the result of abortion after an ovariectomy on day 20 of pregnancy as described in our previous report.     

Polyoxin Resistance of Reddish Brown Laboratory Mutants of Cochliobolus heterostrophus

Six reddish brown polyxin-resistant mutants of Cochliobolus heterostrophus were isolated after ethyl methanesul-phonate and N-nitroquinoline oxide mutageneses followed by selection on polyoxin. All the mutants were highly resistant to polyoxin (MIC > 1600 μg/ml). When mutants were crossed with the wild-type strain, all crosses had a 1 : 1 ratio of mutant (reddish brown pigmentation and polyoxin resistance) : wild type (non-reddish brown pigmentation and polyoxin sensitivity), indicating that the phenotypes in these strains were due to alteration at a single gene locus in each strain. Allelism tests revealed the existence of two loci, Pol2 and Pol5. The results of the crossing and mutation-rate studies suggest that the each gene was pleiotropic for the reddish brown color and polyoxin resistance. Received 19 September 2001/ Accepted in revised form 25 December 2001     

Effect of Harpin from Four Pathovars of Pseudomonas syringae on Pea Defense Responses

To investigate the role of the proteinaceous elicitor, harpin, on host and nonhost plants, we isolated the harpin-coding gene, hrpZ, from Pseudomonas syringae pvs. pisi, glycinea, tabaci and tomato. Effects of the recombinant harpin proteins on pea plants were analyzed and compared with the effects of the corresponding bacterial treatment. After inoculation of pea with pea pathogen P. syringae pv. pisi, the bacterial population increased and the accumulation of PAL-mRNA and pisatin was inhibited. The nonpathogenic pathovars, glycinea, tabaci and tomato induced both defense responses in pea. However, none of the harpins induced the hypersensitive reaction or accumulation of PAL-mRNA and pisatin in pea. Harpins from P. syringae pvs. glycinea, tomato and pisi did induce these defense responses in tobacco, however, suggesting that externally applied harpins either are not recognized or are nonfunctional in pea plants. Received 27 June 2000/ Accepted in revised form 21 February 2001     

Effects of Susceptibility of Test Plants on Modes of Cucumovirus Transmission by Myzus persicae

In sequential transmission tests of Peanut stunt virus S (PSV-S) and Cucumber mosaic virus V (CMV-V) using Myzus persicae, these viruses behave as a semipersistent virus in Phaseolus vulgaris, but as a nonpersistent virus in Nicotiana tabacum, regardless of the species of plant used as the virus source. In addition, viruliferous aphids retained virus infectivity and transmitted it to P. vulgaris, even after they lost infectivity to N. tabacum. Apparently, the mode of transmission by the aphids differs depending on the plant species used for the assay. After mechanical inoculation with purified PSV-S or CMV-V, P. vulgaris appeared more susceptible to PSV-S than N. tabacum. However, the susceptibility to CMV-V appeared similar in both assay plants. Received 22 May 2000/ Accepted in revised form 14 September 2000     

Study on aquifer hydraulic properties using tidal response method for future groundwater development

Paddy and Water Environment - The hydraulic properties of an island’s aquifers were studied using a tidal response method. Groundwater is the principal water resource on the studied island,...     

Pathogenicity of Plasmodiophora brassicae populations from small, spheroid, resistant-type clubroot galls on roots of clubroot-resistant cultivars of Chinese cabbage (Brassica rapa L. subsp. pekinensis)

A resistant type of small, spheroid clubroot galls (SSGs) containing resting spores formed on the root surface of clubroot-resistant (CR) cultivars of Chinese cabbage (Brassica rapa L. subsp. pekinensis) inoculated with an avirulent population of Plasmodiophora  brassicae. Populations isolated from the SSGs severely affected a common (susceptible) cultivar but did not have the typical pathogenicity on CR cultivars, indicating similarity in pathogenicity between SSG and original spore populaions. Populations pathogenic on CR cultivars were not detected from SSGs. Therefore, the ability of the avirulent population among the SSGs to form resting spores may need to be considered to achieve clubroot control in common cultivars of crucifers.     

Simultaneous detection of <Emphasis Type="Italic">Japanese yam mosaic virus</Emphasis> and <Emphasis Type="Italic">Yam mild mosaic virus</Emphasis> from yam leaves using a tube capture reverse transcription-polymerase chain reaction assay

To detect Japanese yam mosaic virus (JYMV) and Yam mild mosaic virus (YMMV) in yam plants in Japan, we developed a duplex RT-PCR assay consisting of a tube-capture procedure followed by one-step RT-PCR with two primer pairs. A 241-bp fragment of the coat protein region of JYMV and a 174-bp fragment of the nuclear inclusion protein b region of YMMV were amplified, thus identifying the two viruses from yam plants cultivated in Yamaguchi Prefecture in 2007. All water yam plants examined were infected with YMMV alone. All the Japanese yam and Chinese yam plants were infected with either JYMV alone or both JYMV and YMMV, suggesting that YMMV and JYMV are prevalent among field-grown yam plants.