Effect of salts on the Hill reaction in sonicated spinach chloroplasts

KC1 stimulated the ferricyanide-Hill reaction at pH higher than6.0 and at ferricyanide concentrations lower than 1 mM in sonicatedspinach chloroplasts. However, KCl did not affect on the DCIP-Hillreaction at all. We concluded that Cl^- is not an essential factor,but only a stimulator of the oxygen-evolving reaction of chloroplasts. (Received March 7, 1974; )     

Phosphoglycolate Phosphatase-Defident Mutants of Chlamydomonas reinhardtii Capable of Growth under Air

Mutants deficient in phosphoglycolate phosphatase (PGPase) requireelevated levels of CO₂ for growth in the light and cannot growwhen photorespiration occurs. Revertants, namely, double mutantscapable of growth under air without restoration of the missingPGPase activity, might be expected to have secondary mutationsthat reduce or eliminate photorespiration. Nineteen revertantswere selected from a culture of a PGPase-deficient mutant ofChlamydomonas reinhardtii (pgp-1-18-7F) after a second mutagenesisthat involved treatment with 5-fluorodeoxyuridine and ethylmethanesulfonate. There were significant differences in thephotosynthetic affinity for CO₂ among revertant cells grownunder 5% CO₂. Eight revertants had five times higher photosyntheticaffinity for CO₂ than that of wild type 2137 cells grown under5% CO₂, resembling air-adapted wild-type cells, whereas fourrevertants had less than half the affinity for CO₂ of the wildtype. In all of the revertant cells with higher affinity grownin 5% CO₂, the rates of photosynthesis under levels of CO₂ belowthose in air were apparently higher than that of the wild type,whereas the rates under CO₂-saturating conditions were lowerthan that of wild type, indicating that the efficiency of photosynthesisunder air was significantly improved in these revertants. Inaddition, some revertants had a photosynthetic capacity anda growth rate higher than those of the wild type, without anyincreased photosynthetic affinity for CO₂. (Received July 7, 1994; Accepted November 5, 1994)     

Changes in the Number and Size of Chloroplasts during Senescence of Primary Leaves of Wheat Grown under Different Conditions

Changes in the number and size of chloroplasts in mesophyllcells were investigated in primary leaves of wheat from fullexpansion to yellowing under different growth conditions. Thenumber of chloroplasts per cell decreased slowly, although thedecrease was steady and statistically significant, until thelast stage of leaf senescence, when rapid degradation of chloroplaststook place. Rates of leaf senescence, or the decline in thenumber of chloroplasts, varied greatly among plants grown atdifferent seasons of the year, but about 20% of chloroplastsalways disappeared during the phase when steady loss of chloroplastsoccurred. The area of chloroplast disks also decreased graduallybut significantly, with a rapid decrease late in senescence.Thus, the total quantity of chloroplasts per mesophyll celldecreased substantially during leaf senescence. Yellowed leavescontained numerous structures that resemble oil drops but nochloroplasts. Decreases in rates of photosynthesis that occurduring senescence may, therefore, be largely due to decreasesin the quantity of chloroplasts. However, a better correlationwas found between the decrease in the maximum capacity for photosynthesisand the degradation of RuBP carboxylase. When plants had beengrown with a sufficient supply of nutrients, the number of chloroplastsdecreased steadily but at a reduced rate and the reduction inthe area of chloroplast disks was strongly suppressed. Thus,the quantitative decrease in chloroplasts in senescing leavesappears to be regulated by the requirements for nutrients (nitrogen)of other part of the plant. ³Present address: Department of Biology, Faculty of Science,Toho University, Miyama, Funabashi, Chiba, 274 Japan     

Immunological detection of the GerA spore germination proteins in the spore integuments of Bacillus subtilis using scanning electron microscopy

Abstract To clarify the molecular mechanisms that trigger spore germination of Bacillus subtilis , the location of GerA proteins (GerAA, GerAB and GerAC), which were reported to be putative gene products of a receptor for one of the germinants, l-alanine, was investigated by immunological techniques using anti-GerA peptide antibodies. Four antibodies were raised against the corresponding epitopes, two in GerAA, one in GerAB and the other in GerAC molecules. The binding of all four antibodies to the inner surface of the cortex-less spore coat fragments could be seen by scanning immunoelectron microscopy with colloidal gold particles. The result agreed with the fact, previously reported, that the colloidal gold particles were visualized just inside the spore coat layer by transmission immunoelectron microscopy using another anti-GerAB peptide antibody.     

Changes in Protein Content and in the Structure and Number of Chloroplasts during Leaf Senescence in Rice Seedlings

Two types of experiment were carried out to examine whetheror not the inactivation of photosynthesis is related to lossof chloroplasts during foliar senescence of rice seedlings.Levels of both soluble and insoluble leaf proteins decreasedduring senescence, the loss of the soluble proteins being fasterthan that of the insoluble ones. There was a good positive correlationbetween the rate of oxygen evolution and the level of solubleproteins. The inactivation of photosynthesis was also linearlyrelated to the loss of a major fraction of insoluble proteins.Thus, the loss of photosynthetic ability is ascribable to thedegradation of relevant proteins and enzymes during leaf senescence.Electron microscopy revealed that senescence caused the disorientationof the grana and stroma thylakoids, a decrease in the numberof starch granules, and an increase in the size and number ofplastoglobuli. Large grana consisting 20 to 30 thylakoids appearedin aged leaves. In addition to these changes in ultrastructure,there was a significant decrease in the size of chloroplasts.Furthermore, the number of chloroplasts in mesophyll cells wasalso notably reduced during senescence. Thus, the loss of leafproteins and inactivation of photosynthesis are both relatedto the decrease in the total mass of chloroplasts during senescenceof rice seedlings. ³Present address: Department of Botany, Faculty of Science,University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113 Japan. (Received January 4, 1989; Accepted April 19, 1989)     

Investigation of the changes in the prostate,bladder, and rectal wall sizes during external beam radiotherapy

Aim and backgroundThe change in the prostate size for radiotherapy has not yet been elucidated. The coverage of radiation dose is affected by changes in the prostate size. We evaluated the changes in the prostate, rectum, and bladder wall sizes during IMRT of fraction 2 Gy/day using MRI.Materials and methodsTwenty-four patients with prostate cancer were enrolled in this study. MRI was performed at three time points. While the initial MRI was performed before the start of radiotherapy (RT), the second MRI was performed at 38 Gy (range: 36–40 Gy), which represented the halfway point of the RT course. The last MRI was performed on the day of completion of the RT course (76 Gy; range: 74–78 Gy). We estimated the prostate, rectum, and bladder wall sizes at three time points.ResultsWe observed no significant difference between the estimated sizes of the prostate during RT in all three phases. In addition, the volume of the rectal wall remained unchanged in all phases. However, the volume of the bladder wall significantly decreased from the initial to the last time points. Furthermore, the standard deviation (SD) obtained by subtracting the final size from the initial one was large (mean, 30.1; SD, 10.1).ConclusionsThe volume of the bladder wall decreased during IMRT. The range of subtraction of the volume of the bladder wall was extensive. Thus, the estimation of the bladder wall may be useful to reduce the inter-fraction variation.     

Fecal IgA antibody responses after oral poliovirus vaccination in infants and elder children

We investigated fecal IgA antibody responses after oral polyvalent poliovirus vaccination. Infants were given vaccines twice with an interval of 6 weeks. Specific IgA antibodies in the feces were determined by enzyme-linked immunosorbent assay, and viruses were isolated in tissue cultures. We found that, after the first vaccination, antibody responses seemed to be elicited only against the serotypes of isolated viruses. After the second vaccination, however, antibodies were detected to all three serotypes with higher titers, suggesting that the first vaccination induced the immunologic memory. The IgA antibodies had virus-neutralizing activity, and existed in the feces as both intact 11S and fragmented 4S molecules. Next, children were given the third vaccination 3 or 9 years later. Fecal IgA antibody responses were found to be poorer in elder children, while they responded with high serum neutralization titers. The secretory IgA memory seemed to last much shorter the serum IgG memory.     

Limb regenerative capacity of four species of Japanese frogs of the families hylidae and ranidae

The regenerative capacity of limbs was investigated by amputation of limbs at the zeugopodium in postmetamorphic froglets and adults of various sizes in four species of Japanese frogs, all of which showed some regeneration at these ages. In Hyla arborea japonica and Rana brevipoda porosa most young froglets regenerated their limbs well; however, the rate of regeneration decreased with the age of amputation, and the limb became nonregenerative in adults. Limbs of adults in Rana rugosa and R. japonica, on the other hand, exhibited good regeneration. All of the regenerates in the four species were heteromorphic, consisting histologically of well-developed cartilaginous rods surronded by connective tissue and skin. Limited development of muscle was appartment in regenerates of the three ranid species. The relations between body size, innervation of limbs, and regenerative capacity are discussed.