Electron microscope studies on the vegetative cellular life cycle of Chlamydomonas reinhardi Dangeard in synchronous culture I. Some characteristics of changes in subcellular structures during the cell cycle, especially in formation of giant mitochondria

Changes in subcellular structures during the entire vegetativecell cycle of Chlamydomonas reinhardi Dangeard in synchronousculture were followed with an electron microscope. Giant mitochondriaof various shapes were temporarily formed, probably by fusionof smaller mitochondria, in the algal cells at an intermediatestage of the growth phase of the cell cycle. Formation of giantmitochondria was accompanied by a marked decrease in the oxygen-uptakeactivity of cells. Giant mitochondria divided into smaller formsconcurrently with a re-increase in the oxygen-uptake activityof cells. Some characteristics of changes in the structuresof chloroplast, the nucleus, the endoplasmic reticula, flagellaand dictyosomes are described. ¹ This work was reported in part at the 35th Annual Meetingof the Botanical Society of Japan, October 1970. (Received October 13, 1971; )     

Active Oxygen Contributes to the Major Part of Chromosomal Aberrations in V79 Chinese Hamster Cells Exposed to N-Hydroxy-2-Naphthylamine

N-hydroxy-2-naphthylamine (NOH-2NA). an active metabolite of human occupational bladder carcinogens, induced, in V79 Chinese hamster cells. chromosomal aberrations which were suppressed in the presence of catalase and/or superoxide dismutase. The induction of the aberrations was more efficient in a more basic pH in parallel with the generation of hydrogen peroxide from NOH-2NA. The possible role of the oxidation product of NOH-2NA in the induction of the aberrations is discussed.     

A relaxed (rel) mutant of Streptomyces coelicolor A3(2) with a missing ribosomal protein lacks the ability to accumulate ppGpp, A-factor and prodigiosin

A relaxed (rel) mutant was found among 70 thiopeptin-resistant isolates of Streptomyces coelicolor A3(2) which arose spontaneously. The ability of the rel mutant to accumulate ppGpp during Casamino acid deprivation was reduced 10-fold compared to the wild-type. Analysis of the ribosomal proteins by two-dimensional PAGE revealed that the mutant lacked a ribosomal protein, tentatively designated ST-L11. It was therefore classified as a relC mutant. The mutant was defective in producing A-factor and the pigmented antibiotic prodigiosin, in both liquid and agar cultures, but produced agarase normally. Production of actinorhodin, another pigmented antibiotic, was also abnormal; it appeared suddenly in agar cultures after 10 d incubation. Although aerial mycelium still formed, its appearance was markedly delayed. Whereas liquid cultures of the parent strain accumulated ppGpp, agar cultures accumulated only trace amounts. Instead, a substance characterized only as an unidentified HPLC peak accumulated intracellularly in the late growth phase, just before aerial mycelium formation and antibiotic production. This substance did not accumulate in mutant cells. It was found in S. lividans 66 and S. parvulus, but not in seven other Streptomyces species tested. The significance of these observations, and the relationship of the mutant to earlier rel isolates of Streptomyces is discussed.     

Variations in concentrations of bacterial metabolites, enzyme activities, moisture, pH and bacterial composition between and within individuals in faeces of seven healthy adults

Variations between and within individuals, and correlations between concentrations of bacterial metabolites, including putrefactive products, ammonia and short chain fatty acids (SCFAs), enzyme activities, moisture and pH, as well as bacterial composition, were studied in faecal samples from seven healthy adults over a period of 7 months. Large variations, both between and within individuals, were observed in concentrations of putrefactive products. Although values for ammonia, SCFAs, enzyme activities, moisture and pH were generally variable, significant person-to-person differences were observed.
While ranges of log viable counts of the predominant bacteria such as eubacteria, bifidobacteria and bacteroides in each subject remained between 0·2 and 1·3, those of enterobacteria, streptococci (including enterococci) and lecithinase-negative clostridia varied between 0·4 and 3·0. Levels of bifidobacteria, enterobacteria, streptococci and total aerobic bacteria showed inter-individual variations. Correlations were found among certain of the parameters: moisture correlated negatively with p -cresol ( r = -0·707), pH ( r = -0–671) and β-glucosidase activity (GS) ( r = -0·608), and positively with acetic acid ( r = 0·621), while negative correlations were observed in pH with acetic and butyric acids ( r = -0·690 and -0·623, respectively).
No significant correlations were found between bacterial compositions, and other faecal factors such as pH, moisture, metabolic enzyme activities and concentrations of putrefactive products.     

Electrophoretic heterogeneity of ribosomal protein AT-L30 among actinomycete genera.

The ribosomal proteins from 17 type strains of species belonging to various actinomycete genera were compared by two-dimensional polyacrylamide gel electrophoresis. I detected a striking variability among certain ribosomal proteins (designated AT-L30 proteins) with respect to electrophoretic mobility in the first dimension. In contrast, such variability was not observed among ribosomal L30 proteins from other bacteria, such as Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus. Although actinomycete AT-L30 proteins from different taxa exhibited considerable heterogeneity in electrophoretic mobility, within each genus the proteins had a specific mobility characteristic. On the basis of this observation, the ribosomal AT-L30 proteins from 11 type strains of species belonging to the mycolic acid-containing genera Nocardia, Rhodococcus, Gordona, and Tsukamurella were analyzed. The relative electrophoretic mobilities of AT-L30 protein preparations from these strains, as determined by two-dimensional gel electrophoresis, revealed that the genera Nocardia, Rhodococcus, Gordona, and Tsukamurella can be sharply separated from each other. My results are consistent with the previously discussed view that each of these genera merits separate genus status.     

Synthesis of desmosterol and epidesmosterol from hyodeoxycholic acid

A new synthesis of desmosterol was described using hyodeoxycholic acid (3,6-dihydroxy-5β-cholanic acid) as a starting material. Epidesmosterol (3-hydroxycholesta-5,24-diene) was also synthesized for the first time from the same starting material.     

Development of the ovarian surface and associated germ cells in the human fetus

Summary The ovarian surface and associated germ cells have been studied in human fetuses from 12 weeks of age until near term, using light, TEM and SEM techniques. The surface epithelium and related cords proliferate extensively, especially at midterm. The cords in the ovarian cortex appear to be linked with ingrowths from the surface epithelium, and both structures have a common basal lamina. Germ cells are always interspersed among the somatic cells of the surface epithelium and associated cords. These results indicate that both the proliferating cords and surface epithelium may contribute to the formation of early follicles. Furthermore, the occurrence, of elements having some of the features of primitive steroidogenic cells in the regions of cordsurface epithelium continuity, suggests that both structures (surface epithelium and cords) contribute somatic cells, which in addition to becoming granulosa cells, might also contribute to the provision of primitive interstitial cells.Gonocytes tend to migrate through the developing ovarian tissue towards the surface where they become extruded into the peritoneal cavity. This phenomenon might contribute to the reduction in the number of germ cells at birth and parallels the atretic processes within the ovary.     

Hereditary respiration deficiency in Saccharomycodes ludwigii

Saccharomycodes ludwigii, supposed to be petite-negative, gave rise to respiration-deficient mutants when acriflavine and ultraviolet irradiation, respectively, were applied to this yeast, strain IFO 1194. The frequency of such mutants was very low as compared with that in Saccharomyces cerevisiae and other petite-positive yeasts. Cytochrome composition was characterized by spectrophotometry at the temperature of liquid nitrogen. The respiratory mutants examined contained cytochrome c unaltered in quality and quantity. Cytochrome b was often present only in small amounts though never absent, while cytochrome a+a₃ was either present or absent. The respiratory mutants could form zygotes after conjugation with a wild-type culture of opposite mating type ( vs. a). The hybridization and segregation analysis of spore tetrads showed the inheritance of respiratory mutant character to be either Mendelian or non-Mendelian and similar to that of pet (nuclear) and rho^- (cytoplasmic) mutants, respectively, in Saccharomyces cerevisiae.