Evolution of honest reward signal in flowers.

Some flowering plants signal the abundance of their rewards by changing their flower colour, scent or other floral traits as rewards are depleted. These floral trait changes can be regarded as honest signals of reward states for pollinators. Previous studies have hypothesized that these signals are used to maintain plant-level attractiveness to pollinators, but the evolutionary conditions leading to the development of honest signals have not been well investigated from a theoretical basis. We examined conditions leading to the evolution of honest reward signals in flowers by applying a theoretical model that included pollinator response and signal accuracy. We assumed that pollinators learn floral traits and plant locations in association with reward states and use this information to decide which flowers to visit. While manipulating the level of associative learning, we investigated optimal flower longevity, the proportion of reward and rewardless flowers, and honest- and dishonest-signalling strategies. We found that honest signals are evolutionarily stable only when flowers are visited by pollinators with both high and low learning abilities. These findings imply that behavioural variation in learning within a pollinator community can lead to the evolution of an honest signal even when there is no contribution of rewardless flowers to pollinator attractiveness.

Eradication of breast cancer xenografts by hyperthermic suicide gene therapy under the control of the heat shock protein promoter.

To investigate the usefulness of heat shock protein (HSP) promoter for breast cancer gene therapy, hyperthermia and HSV thymidine kinase (tk) suicide gene combination therapy was examined with mouse mammary cancer cell line FM3A. HSP promoter activity was markedly increased after heat shock (41-45 degrees C), with maximum activation (about 400-fold) at 3 hr. An in vitro cytotoxic assay showed that HSP-tk-transduced FM3A cells became more sensitive (more than 50,000 times) to ganciclovir (GCV) with heat shock, but untreated cells showed no increased cytotoxic sensitivity to GCV compared with control FM3A cells. In addition to promoter-oriented selective cell killing, a "chemosensitization effect" as a bystander effect was demonstrated by hyperthermia and suicide gene combination therapy, using a non-heat-inducible promoter. Immunohistochemical analysis revealed that this synergistic killing effect was dependent on apoptotic cell death with upregulation of both Fas and FasL (Fas ligand) expression. We also examined the efficacy of HSP-tk gene therapy in vivo by implanting breast cancer in subcutaneous and intraperitoneal models of BALB/c nude mice targeted by the HVJ-anionic liposome method. Significant tumor regression was observed in HSP-tk-transduced tumors followed by hyperthermia therapy, but no such inhibition was noted in either the mock vector transfection or hyperthermia group compared with control tumor-bearing mice. Our results demonstrate that this combination system is synergistically effective in mediating Fas-dependent apoptosis for a specific gene therapy targeting HSP-expressing mammary carcinomas, even in advanced and heat-resistant breast cancer.

Autocrine response of Schizosaccharomyces pombe haploid cells to mating pheromones.

The mating response of the fission yeast Schizosaccharomyces pombe is mediated by mating pheromones, M-factor and P-factor, produced by h- and h+ cells, respectively. When the M-factor receptor (Map3) was ectopically expressed in h- cells lacking the P-factor receptor (Mam2), they acquired mating competence in response to M-factor which they secreted. The autocrine response to P-factor in h- cells was so weak that mating competence was not acquired, although expression of the pheromone-responsive gene matl-Pm was detected. These observations support the notion that the intensity of cellular response to mating phermones is different between h- and h+ cells, although downstream pathways of the pheromone receptors are shared by the two mating types.

The use of tears for diagnosis of GM1 gangliosidosis.

The properties of beta-galactosidase of tears were investigated and the standard assay system was accomplished. The pH optimum was 4.2. The enzyme had a KM of 8.3 X 10(-4) M. The activity was stimulated by chloride ions and slightly stabilized by bovine serum albumin. The activities of normal individuals were 205 +/- 80 (S.D.) nmol/h/ml. The activity in the tears of the patient with GM1 gangliosidosis decreased to about 20% of normal control and this disease could be diagnosed by the assay of beta-galactosidase in tears.

Comparative clinical study of cefcapene pivoxil and cefteram pivoxil in chronic respiratory tract infections by a double-blind method.

In a double-blind study, the efficacy and safety of the novel cephem antibiotic cefcapene pivoxil (CFPN-PI; 450 mg/day) was compared with cefteram pivoxil (CFTM-PI; 600 mg/day) in 171 patients with chronic respiratory tract infections. There was no significant difference between the clinical efficacy of the two drugs (80.2% for CFPN-PI versus 78.9% for CFTM-PI). There was no significant difference in the rate of elimination of the causative bacteria (60.5% for CFPN-PI versus 65.9% for CFTM-PI). Side-effects were observed in 6.0% of patients treated with CFPN-PI compared with 6.4% of patients treated with CFTM-PI. There were no significant differences in incidence of abnormal laboratory findings following treatment with the two drugs (13.9% for each), and none of the side-effects was severe. We conclude that CFPN-PI (450 mg/day) was as effective and as well tolerated as CFTM-PI (600 mg/day) in the treatment of chronic respiratory tract infections.