Lack of invaginations of the plasma membrane during budding and cell division of Saccharomyces cerevisiae and Schizosaccharomyces pombe

Abstract The plasma membrane of Saccharomyces cerevisiae and Schizosaccharomyces pombe in stationary phase had abundant invaginations. A round uninvaginated area emerged before budding when S. cerevisiae cells were given fresh medium. Middle-sized buds had some invaginations, whereas the neck between the bud and mother had very few. S. pombe which has neither the neck nor the predetermined position to divide had no uninvaginated ring area even in long cells during elongation in fresh medium. However, an uninvaginated ring area emerged as the earliest noticeable stage of cytokinesis. The uninvaginated state of the plasma membrane appeared to be correlated with budding and cell division.     

Cloning and nucleotide sequences of the linear DNA killer plasmids from yeast.

The linear DNA killer plasmids (pGKL1 and pGKL2) isolated from a Kluyveromyces lactis killer strain are also maintained and expressed its killer character in Saccharomyces cerevisiae. After these killer plasmid DNAs isolated from S. cerevisiae were treated with alkali, four terminal fragments from each plasmid DNAs were cloned separately. Using these and other cloned DNA fragments, the terminal nucleotide sequences of pGKL2 and the complete nucleotide sequence of pGKL1 were determined. The inverted terminal repetitions of 202 bp and 182 bp were found in pGKL1 and pGKL2, respectively. The pGKL1 sequence showed an extremely high A + T content of 73.2% and it contained five large open reading frames. The largest of these open reading frame was suggested to code for a membrane-bound precursor of glycoprotein subunit of the killer toxin.     

Effects of taurine and γ-aminobutyric acid on akinesia and analgesia induced by D-Ala2-Met-enkephalinamide in rats

Effects of taurine or γ-aminobutyric acid (GABA) on akinesia and analgesia induced by D-Ala²-Met-enkephalinamide were investigated in rats. Administration of taurine (dose range: 2.375×10^?2 M–9.5×10^?2 M/10 μl) into the left lateral ventricle 10 min prior to the injection of D-Ala²-Met-enkephalinamide (50 μg/10 μl) produced a dose-dependent reduction in the duration of akinesia and to some extent of analgesia, as estimated at 30 min and 60 min following the enkephalinamide injection; at the first estimation-time (10 min), taurine did not alter the duration of akinesia or that of analgesia. The median effective dose (ED₅₀) for akinesia determined at 60 min after D-Ala²-Met-enkephalinamide was 5 times greater and that for analgesia assessed at the same time was 1.7 times greater in taurine-treated rats than the respective doses in control animals. Administration of GABA under similar experimental conditions produced a dose-dependent reduction in the duration of analgesia from the initial estimation time (10 min) following the injection of D-Ala²-Met-enkephalinamide. The ED₅₀ for analgesia determined at 30 min after D-Ala²-Met-enkephalinamide was 3 times greater in GABA-treated rats than in control animals. Unlike the effects of taurine, GABA did not alter the duration of akinesia. Neither the duration of akinesia nor that of analgesia was modified by taurine or GABA alone in rats tested 9 min after the injection of each amino acid. These findings suggest that taurine may promote a recovery from both akinesia and analgesia, while GABA decreases only the analgesia induced by D-Ala²-Met-enkephalinamide.     

Persistence of genomes of both herpesvirus of turkeys and Marek's disease virus in a chicken T-lymphoblastoid cell line

A cell line tentatively designated as MDCC-BO1(T), was established from spleen cells of an apparently healthy chicken inoculated with herpesvirus of turkey (HVT). BO1(T) cells were T lymphoblastoid cells and the more than 95% of them had Marek's disease (MD) tumor-associated surface antigen (MATSA). However, no viral internal antigens or membrane antigens could be demonstrated in them by immunofluorescence tests using chicken anti-HVT and -MD virus (MDV) sera. The virus could be rescued from BO1(T) cells by co-cultivation with chick embryo fibroblasts (CEF). The DNA of the rescued virus was characterized as HVT DNA by its sedimentation profile in a neutral glycerol gradient and its endonuclease Hind III cleavage-pattern. Ultrastructural studies on CEF infected with the rescued virus revealed the presence of HVT-like virions. However, DNA-DNA reassociation kinetics showed that the BO1(T) cells contained a few copies of NVT and also MDV genomes.     

Further morphological characterization and structural proteins of infectious bursal disease virus.

An outer layer surrounding the capsid of infectious bursal disease virus was evident from electron micrographs of intact virus particles having diameters of 62 to 63 nm. The capsid was found to be composed of large morphological units or capsomeres, measuring about 12 nm in diameter. The architecture of the capsid appears to be that of T = 3 symmetry, with a probable 32 morphological units by rotational enhancement of image detail. Structural proteins of infectious bursal disease virus consist of seven species, two major and five minor polypeptides. These are P1 to P7, with molecular weights of 133 x 10(3), 124 x 10(3), 98 x 10(3), 51 x 10(3), 33 x 10(3), 26 x 10(3), and 23 x 10(3), respectively.     

Dose-response relations for dicentric yields in G0 lymphocytes on man and crab-eating monkey following acute and chronic γ-irradiations

A comparison has been made of dicentric yields in G₀ lymphocytes between man and crab-eating monkey, Macaca fascicularis, after acute and chronic γ-irradiations. With acute irradiation (49.6 rad/min) there was no significant difference between them, but for the chronic irradiation (17.1 rad/h) a significant difference was observed between the species. When the dose-response relations were fitted to the linear-quadratic model (Y = αD + βD²), the species-difference observed for chronic irradiation was almost entirely due to change in the value of β. In addition, after chronic irradiation the β-value for monkey was almost negligible, but that for man was significant. Post-irradiation incubation experiment showed that cells with dicentrics were partly eliminated during the course of chronic irradiation, because there were appreciable reductions of dicentric yields (ca. 25% for both man and monkey at 400 rad) together with mitotic indices (ca. 30% and 60% for man and monkey, respectively, at 400 rad). Accordingly, it would be reasonable to postulate that G₀ repair for dicentrics other than selection mechanism must play a major role in the effects of low dose rate. It can be further suggested that G₀-repair capacity for chromosal damages leading to dicentrics may be different among different primate species.     

Dicentric yields induced by gamma-radiation and chromosome arm number in primates.

To evaluate the effect of the chromosome arm number on the yield of dicentric chromosomes, frequencies of gamma-ray-induced chromosome aberrations were examined with peripheral lymphocytes from three different primate species, Saimiri sciureus (arm number, 77), Macaca fascicularis (arm number, 83) and Nycticebus coucang (arm number, 99). Irradiated blood samples were cultured by the same standard technique as that commonly used for human lymphocytes. The yields of dicentrics and dicentrics plus rings at doses of 100, 200 and 300 rad of gamma-irradiation were not significantly different among the three species, in spite of the difference in the chromosome arm number. Furthermore, dose-response relationships for these species were consistent with that for man. Statistical analysis indicated that the expected dicentric yields calculated from the arm number model were significantly different from the observed yields at 200 and 300 rad doses (P less than 0.01). From these results it can be pointed out that there is no correlation between the yield of dicentrics and the effective chromosome arm number, and that the chromosomal radiosensitivity of these primates is essentially the same as that of man, at least in the lymphocyte system.     

Regional replication of the bacterial chromosome induced by derepression of prophage lambda

Summary Derepression of prophage in E. coli strain K12 results in constitutive synthesis of the enzymes directed by the nearby bacterial operon, gal (escape synthesis). Phage 82 fails to cause escape synthesis despite that it lysogenizes the strain K12 at the site identical to that of on the host chromosome. The reason for the observed difference between 82 and is studied in the light of the recent finding that escape synthesis in -lysogen is closely associated to phage-promoted replication of bacterial chromosome contiguous to the prophage including gal operon (escape replication). Excision-defective mutants from 82, 82int or 82xis, do initiate escape synthesis, suggesting that the prophage 82 is normally excised too quickly after induction to allow sufficient escape replication. In support of this, much more DNA hybridizable to bacterial DNA contained in gal accumulates after induction of 82int than after induction of 82. Studies with various hybrid phages between 82 and have suggested: 1. The occurrence of gal escape synthesis depends on the nature of the region between b2 and N in the map. 2. Regions of the 82 genome on both sides of the attachment site contribute independently to prevent gal escape synthesis. Implications of these results are discussed with regard to the factors involved in the prophage excision.The IIIrd article of this series is in Molec. Gen. Genet. 159, 185–190 (1978)     

Cyclin B in fish oocytes: its cDNA and amino acid sequences, appearance during maturation, and induction of p34cdc2 activation.

Under the influence of maturation-inducing hormone (MIH) secreted from follicle cells, oocyte maturation is finally triggered by maturation-promoting factor (MPF), which consists of a homolog of the cdc2+ gene product of fission yeast (p34cdc2) and cyclin B. Two species of cyclin B clones were isolated from a cDNA library constructed from mature goldfish oocytes. Sequence comparisons revealed that these two clones are highly homologous (95%) and were found to be similar to Xenopus cyclin B1. Using monoclonal antibodies against Escherichia coli-produced goldfish cyclin B and the PSTAIR sequence of p34cdc2, we examined the levels of cyclin B and p34cdc2 proteins during goldfish oocyte maturation induced in vitro by 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-DP), a natural MIH in fish. Protein p34cdc2 was found in immature oocyte extracts and did not remarkably change during oocyte maturation. Cyclin B was not detected in immature oocyte extracts and appeared when oocytes underwent germinal vesicle breakdown. Cyclin B that appeared during oocyte maturation was labelled with [35S]methionine, indicating its de novo synthesis. Introduction of E. coli-produced cyclin B into immature oocyte extracts induced p34cdc2 (MPF) activation. Although the possibility that immature goldfish oocytes contain an insoluble cyclin B is not completely excluded, these results strongly suggest that 17 alpha, 20 beta-DP induces oocytes to synthesize cyclin B, which in turn activates preexisting p34cdc2, forming active MPF.     

A three-dimensional computerized reconstruction of the rectum, anus and surrounding muscles of the rat fetus at the 20th gestation day

Using fetuses of Wistar/I rats on the 20th gestation day. We designed a three-dimensional computerized reconstruction of the rectum, anus and the surrounding muscles. The tissues were fixed in Bouin's solution sagittally sectioned serially were stained with hematoxylin-eosin. Light microscopic pictures at 40 x magnification were subjected to the analysis using a three-dimensional image processing system, consisting of a drum-scanner, a general purpose computer (Micro VAX II), and a color image processor. The results showed that this system clearly reconstructed the three-dimensional image of the rectum, anus and the surrounding muscles and suggested the presence of the puborectal muscle sling.