Evaluation of pollen tube growth ability in Petunia species having different style lengths.

Pollen tube growth is essential for the fertilization process in angiosperms. When pollen grains arrive on the stigma, they germinate, and the pollen tubes elongate through the styles of the pistils to deliver sperm cells into the ovules to produce the seeds. The relationship between the growth rate and style length remains unclear. In previous studies, we developed a liquid pollen germination medium for observing pollen tube growth. In this study, using this medium, we examined the pollen tube growth ability in Petunia axillaris subsp. axillaris, P. axillaris subsp. parodii, P. integrifolia, and P. occidentalis, which have different style lengths. Petunia occidentalis had the longest pollen tubes after 6 h of culture but had a relatively shorter style. Conversely, the pollination experiments revealed that P. axillaris subsp. parodii, which had the longest style, produced the longest pollen tubes in vivo. The results revealed no clear relationship between the style lengths and the growth rate of pollen tubes in vitro. Interspecific pollinations indicated that the styles affected pollen tube growth. We concluded that, in vitro, the pollen tubes grow without being affected by the styles, whereas, in vivo, the styles significantly affected pollen tube growth. Furthermore, interspecific pollination experiments implied that the pollen tube growth tended to be suppressed in the styles of self-incompatibility species. Finally, we discussed the pollen tube growth ability in relation to style lengths.

Pid3-I1 is a race-specific partial-resistance allele at the Pid3 blast resistance locus in rice.

KEY MESSAGE: The rice blast resistance QTL detected on chromosome 6 in MC276 is Pid3-I1, one of the multiple alleles at the Pid3 locus. Pid3-I1 shows race-specific partial resistance. Many of the quantitative trait loci (QTLs) for rice blast resistance reported to date remain unidentified. In the present study, we focused on qBRM6.2, a known blast-resistance QTL in experimental resistant rice line MC276. A CO39 near-isogenic line (NIL) carrying qBRM6.2 from MC276 was developed here, and we showed that qBRM6.2 resistance was partial but race specific to Japanese blast isolates using the NIL. Because defense genes in the NIL were expressed sooner than those in CO39 after inoculation with a blast isolate, qBRM6.2 resistance appeared to be an induced resistance. Next, we demonstrated that qBRM6.2 was located within a 123-kb interval on chromosome 6. Among the six genes annotated in the interval, only four genes appeared to be functional. Among these four, a polymorphism between CO39 and the NIL for qBRM6.2 at the amino acid sequence level was detected only in Os06g0330400 that encodes a fatty acid hydroxylase domain-containing protein and in Os06g0330100, the blast resistance locus Pid3, that encodes a nucleotide-binding site-leucine-rich repeat protein. Moreover, the allele at the Pid3 locus in the NIL was Pid3-I1, originally identified as a complete blast resistance gene in Kasalath. To clarify whether Pid3-I1 is qBRM6.2, we investigated the resistance phenotype of Pid3-I1 to Japanese isolates using Nipponbare transgenic lines that express Pid3-I1. The results showed that Pid3-I1 was a race-specific but partial-resistance allele at the Pid3 locus, suggesting strongly that Pid3-I1 is qBRM6.2. The discrepancy in the phenotype of Pid3-I1 between the present and previous reports is also discussed.

Plasma leptin levels in patients with burn injury: a preliminary report.

The purpose of this study was to investigate the relationship between the plasma leptin level and clinical parameters in patients with burn injury. Six patients with burn injury were admitted to the Emergency and Critical Care Medicine Center of St. Marianna University Hospital within 1h after injury. Plasma levels were monitored for leptin, proinflammatory cytokines (interleukin (IL)-1 beta, IL-6, tumor necrosis factor alpha (TNF alpha)), stress-related parameters (adrenocorticotropic hormone (ACTH), cortisol, and C-reactive protein (CRP)). The change in individual plasma leptin levels did not show similar pattern in all these patients. However, leptin levels remained within the normal range, except in a patient (Case 1) complicated with severe hypovolemic shock. Plasma ACTH and cortisol levels were also elevated in most of the patients. Examination of relationships among plasma leptin, proinflammatory cytokines, and stress-related parameters revealed a significant positive correlation between the plasma leptin level and IL-1 beta or IL-6. These results suggest that the plasma leptin level may have some relations to plasma proinflammatory cytokines in pathophysiologic responses to critical conditions of burn injury.

Weekly pulse therapy of methotrexate improves survival compared with its daily administration in MRL/lpr mice.

The purpose of this study was to determine whether weekly pulse therapy was superior to daily administration of methotrexate in MRL/lpr mice. Oral methotrexate was given to 6-week-old MRL/lpr mice at doses of 0.3, 1.0, or 3.0 mg/kg 5 days a week or at a dose of 15.0 mg/kg once a week until 35 weeks of age. The effects of methotrexate on physical, serological, and pathological findings were assessed. The survival rate and articular destruction on X-ray films were also evaluated. Both weekly pulse therapy and daily administration of methotrexate at the same weekly dose improved nephropathy and articular destruction of MRL/lpr mice when compared with control. However, weekly pulse therapy with methotrexate prolonged the survival of MRL/lpr mice when compared with the daily administration of the same weekly dose of methotrexate and control. Methotrexate did not suppress the increase in anti-DNA antibody and rheumatoid factor. Daily administration of methotrexate reduced the red and white blood cell counts, whereas weekly pulse therapy caused little reduction. In conclusion, weekly pulse therapy was superior to daily administration of methotrexate with respect to the survival rate, possibly due to a reduction in toxicity.