Development and application of photoautotrophic micropropagation plant system

Research has revealed that most chlorophyllous explants/plants in vitro have the ability to grow photoautotrophically (without sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is not due to poor photosynthetic ability, but to the low CO₂ concentration in the air-tight culture vessel during the photoperiod. Moreover, numerous studies have been conducted on improving the in vitro environment and investigating its effects on growth and development of cultures/plantlets on nearly 50 species since the concept of photoautotrophic micropropagation was developed more than two decades ago. These studies indicate that the photoautotrophic growth in vitro of many plant species can be significantly promoted by increasing the CO₂ concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous or porous supporting material with high air porosity instead of gelling agents such as agar. This paper reviews the development and characteristics of photoautotrophic micropropagation systems and the effects of environmental conditions on the growth and development of the plantlets. The commercial applications and the perspective of photoautotrophic micropropagation systems are discussed.     

Calorie restriction delays cardiac senescence and improves cardiac function in obese diabetic rats

Molecular and Cellular Biochemistry - The aims of this study were to investigate the impact of caloric restriction (CR) on cardiac senescence in an animal model of diabetes and examine the signal...     

A New Amino Acid Antibiotic KT–151, Produced by Streptomyces luteogriseus,Strain No. KT–151

From the results of taxonomic studies, Streptomyces sp. strain No. KT–151 isolated from a soil sample collected in Kumamoto City, was identified as a strain belonging to Streptomyces luteogriseus Schmitz, Deak, Crook and Hooper 1964. A new antibiotic, produced by this strain, was isolated as a leaflet crystal by ion-exchange chromatography and found to be an amino acid with the molecular formula, C₅H₁₂N₂O₂, and named antibiotic KT–151 (refered to as KT–151 hereinafter). The antibiotic showed antimicrobial activity against various Gram-positive and Gram-negative bacteria in a chemically defined medium but it was antagonized by several amino acids such as valine, leucine, isoleucine and threonine.     

Polysaccharide/polynucleotide complexes. Part 6: complementary-strand-induced release of single-stranded DNA bound in the schizophyllan complex

Spectroscopic properties of single-stranded DNA/schizophyllan ternary complexes (ss-DNA2s-SPG), induced by addition of either complementary or noncomplementary strands, have been investigated. The addition of the complementary strands to ss-DNA2s-SPG induced the quick release of the bound ss-DNA to the complementary strands (both DNA and RNA), whereas the ternary complex was unaffected upon addition of noncomplementary strands. Our experiments imply that SPG has complexation properties indispensable to the gene carriers. As far as we know, there is no report on exploitation of such nonviral gene carriers that can accomplish an intelligent release of the bound ss-DNA toward the complementary strands. We believe, therefore, that SPG, a natural and neutral polysaccharide, has a great potential to become a new ss-DNA carrier.     

Photoautotrophic growth of sugarcane plantlets <Emphasis Type="Italic">in vitro</Emphasis> as affected by photosynthetic photon flux and vessel air exchanges

Summary Explants of sugarcane, a C₄ plant, were cultured in vitro for 18d on Floridalite (a solid cube consisting of vermiculite and cellulose fibers) used as supporting material with sugar-free Murashige and Skoog liquid medium with double-strength KH₂PO₄, MgSO₄, FeSO₄, and Na₂-EDTA in the vessel with enhanced natural ventilation. CO₂ concentration in the culture room was kept at 1500 μmol mol⁻¹ (four times the atmospheric CO₂ concentration) during the photoperiod. A factorial experiment was designed with two levels of photosynthetic photon flux (PPF) and three levels of N (number of air exchanges of the vessel). The results were compared with those in the control treatment (photomixotrophic culture using sugar-containing agar medium under low PPF and low N). PPF and N showed significant positive effects on the growth of sugarcane plantlets in vitro. In the photoautotrophic (using sugar-free medium) treatments with relatively high PPF (200–400 μmol m⁻² s⁻¹) and high N (2–10 h⁻¹), the growth of plantlets was four to seven times greater than that in the control. Also, the culture period for multiplication and rooting was shortened from 30 d in the control to 18 d or less in the photoautotrophic, high PPF, and high N treatments. Use of porous supporting material in photoautotrophic treatments promoted rooting and plantlet growth significantly.     

Photosynthetic characteristics of coffee (Coffea arabusta) plantlets in vitro in response to different CO2 concentrations and light intensities

The photosynthetic characteristics of coffee ( Coffea arabusta) plantlets cultured in vitro in response to different CO₂ concentrations inside the culture vessel and photosynthetic photon flux (PPF) were investigated preliminarily. The estimation of net photosynthetic rate (P_n) of coffee plantlets involved three methods: (1) estimating time courses of actual P_n in situ based on measuring CO₂ concentrations inside and outside the vessel during a 45-day period, (2) estimating P_n in situ at different CO₂ concentrations and PPFs using the above measuring approach for 10-day and 30-day old in vitro plantlets, and (3) estimating P_n of a single leaf at different CO₂ concentrations and PPFs by using a portable photosynthesis measurement system for 45-day old in vitro coffee plantlets. The results showed that coffee plantlets in vitro had relatively high photosynthetic ability and that the P_n increased with the increase in CO₂ concentration inside the vessel. The CO₂ saturation point of in vitro coffee plantlets was high (4500–5000 μmol mol^-1); on the other hand, the PPF saturation point was not so high as compared to some other species, though it increased with increasing CO₂ concentration inside the vessel. This revised version was published online in June 2006 with corrections to the Cover Date.     

p51/p63, a novel p53 homologue, potentiates p53 activity and is a human cancer gene therapy candidate

BACKGROUND: p51 (p73L/p63/p40/KET), a recently isolated novel p53 homologue, binds to p53-responsive elements to upregulate some p53 target genes and has been suggested to share partially overlapping functions with p53. p51 may be a promising candidate target molecule for anti-cancer therapy. METHODS: In this study, we adenovirally transduced p51A cDNA into human lung, gastric and pancreatic cancer cells and analyzed the intracellular function of p51 in anti-oncogenesis in vitro and in vivo. RESULTS: Overexpression of p51A revealed an anti-proliferative effect in vitro in all the cancer cells examined in this study. The anchorage-dependent and -independent cell growth of EBC1 cells carrying mutations in both p51 and p53 was suppressed and significant apoptosis following adenoviral transduction with p51 and/or p53 was seen. This growth suppression was cooperatively enhanced by the combined infection with adenoviral vectors encoding both p51 and p53. Furthermore, p51 activated several, but not all, p53-inducible genes, indicating that the mechanisms controlling p51- and p53-mediated tumor suppression differed. CONCLUSIONS: Our observations indicate that, although p51 exhibited reduced anti-oncogenetic effects compared with p53, it cooperatively enhanced the anti-tumor effects of p53. Our results suggest that p51 functions as a tumor suppressor in human cancer cells in vitro and in vivo and may be useful as a potential tool for cancer gene therapy.     

Attenuated stress-induced catecholamine release in mice lacking the vasopressin V1b receptor

Vasopressin V(1b) receptor is specifically expressed in the pituitary and mediates adrenocorticotropin release, thereby regulating stress responses via its corticotropin releasing factor-like action. In the present study we examined catecholamine release in response to two types of stress in mice lacking the V(1b) receptor gene (V(1b)R(-/-) mice) vs. wild-type mice. There were no significant differences in the basal plasma levels of catecholamines between the two genotypes. In response to stress induced by forced swimming, norepinephrine (NE), but not epinephrine (E) or dopamine (DA), was increased in wild-type mice, whereas the increases in NE and DA were not observed in V(1b)R(-/-) mice. In wild-type mice, E, but not NE or DA, was increased in response to social isolation stress, whereas the increase in E was not observed in V(1b)R(-/-) mice. These results suggest that the V(1b) receptor regulates stress-induced catecholamine release. Because it has been suggested that arginine-vasopressin (AVP) is related to the development of depression, we also evaluated immobility time in the forced swimming test, and we found no significant change in V(1b)R(-/-) mice. Taken together, these findings suggest that, in addition to the previously elucidated effect on the hypothalamic-pituitary-adrenal axis, vasopressin activity via V(1b) receptors regulates stress-induced catecholamine release.     

Foot odor due to microbial metabolism and its control

To characterize foot odor, we analyzed its components by sensory tests, isolated microorganisms that produce it, and evaluated the mechanism of the occurrence of foot odor. As a result, foot odor was found to be derived from isovaleric acid, which is produced when Staphylococcus epidermidis, a resident species of the normal cutaneous microbial flora, degrades leucine present in sweat. In addition, Bacillus subtilis was detected in the plantar skin of subjects with strong foot odor, and this species was shown to be closely associated with increased foot odor. Therefore, we screened various naturally occurring substances and fragrant agents that inhibit microbial production of foot odor without disturbing the normal microbial flora of the human skin. As a result, we identified citral, citronellal, and geraniol as fragrant agents that inhibit the generation of isovaleric acid at low concentrations.