Catalase formation in Rhodotorula mucilaginosa in relation to the effect of glucose and antibiotics

The developmental pattern of the catalase activity in Rhodotorulamucilaginosa, an obligate aerobe, was investigated in relationto its growth. The pattern of catalase activity does not runin a manner comparable with that of a respiratory capacity,because catalase activity takes a continual rise after the middleof the logarithmic growth, while a respiratory pattern runsa constant level during the corresponding growth phase. Additionof antimycin A to cells with a minimum catalase activity doesnot block the increase in the catalase activity. Chloramphenicoldoes not exert any recognizable effect on the catalase formationwhereas cycloheximide does create an intense inhibitory effect,regardless of addition times on the course of growth. Theseresults show that the synthesizing sites of yeast catalase aredifferent from mitochondria. ¹Present address: Department of Biology, Japan Women's University,Tokyo, Japan (Received February 18, 1970; )     

Reconstitution of Embryo-Like Structures from Sea Urchin Embryo Cells: Distinction Between Cell-Cell and Cell-Substrate Associations

Sea urchin embryos can be dissociated into a suspension of single cells that reconstitute embryo-like structures. When reconstitution is conducted in stationary cultures the first step is attachment of the cells to the culture plate, which requires calcium and metabolic energy but not protein synthesis. We have found that protease treated cells form cell-cell associations in stationary cultures without attaching to the culture plates, and that cell-plate attachments are unaffected by inhibition of protein synthesis. These data suggest that cell surface proteins are needed for cell-plate attachment and that these proteins are present on freshly dissociated cells. We also demonstrated that butanol extracted cells attach to the plates, but do not form functional cell-cell associations unless the butanol extracted material is restored to them. We conclude that sea urchin embryo cells contain two classes of attachment components. The first class functions in the cell-plate attachments, is protease sensitive, and not extracted by butanol; the second class is necessary for cell-cell associations, is protease insensitive, and extracted by butanol. Since protease treated cells reconstitute embryo-like structures without attaching to the culture plates, only the second class of attachment components is necessary for embryo reconstitution.     

Suppression of Cdc27B expression induces plant defence responses

Non-host resistance is the most general form of disease resistance in plants because it is effective against most phytopathogens. The importance of hypersensitive responses (HRs) in non-host resistance of Nicotiana species to the oomycete Phytophthora is clear. INF1 elicitin, an elicitor obtained from the late-blight pathogen Phytophthora infestans , is sufficient to induce a typical HR in Nicotiana species. The molecular mechanisms that underlie the non-host resistance component of plant defence responses have been investigated using differential-display polymerase chain reaction (PCR) in a model HR system between INF1 elicitin and tobacco BY-2 cells. Differential-display PCR has revealed that Cdc27B is down-regulated in tobacco BY-2 cells after treatment with INF1 elicitin. Cdc27B is one of 13 essential components of the anaphase-promoting complex or cyclosome (APC/C)-type E3 ubiquitin ligase complex in yeast. This APC/C-type E3 ubiquitin ligase complex regulates G2-to-M phase transition of the cell cycle by proteolytic degradation. In this study, we investigated the roles of this gene, NbCdc27B , in plant defence responses using virus-induced gene silencing. Suppression of NbCdc27B in Nicotiana benthamiana plants induced defence responses and a gain of resistance to Colletotrichum lagenarium fungus. Elicitin-induced hypersensitive cell death (HCD) was inhibited mildly in plants silenced with tobacco rattle virus::Cdc27B. Cdc27B could manage the signalling pathways of plant defence responses as a negative regulator without HCD.     

How does flowering magnitude affect seed survival in Shorea pilosa (Dipterocarpaceae) at the predispersal stage in Malaysia?

General flowering (GF), a supra-annual, irregular fluctuation in flowering and seeding at the community level, is a phenomenon unique to the tropical rainforests of South-East Asia. To test the animal pollination and predator satiation hypotheses, which are the main hypotheses that attempt to explain the ultimate cause of GF, we conducted a bagging experiment after the flowering of Shorea pilosa (Dipterocarpaceae). Seed survival at the predispersal stage was divided into two stages (1–30 days and > 30 days after flowering) and we compared the results between treatments and between GF and non-GF periods using a survival analysis. Survival during the GF period at both stages was significantly higher than during non-GF periods, suggesting that both hypotheses were supported and that synchronous flowering with GF benefits the reproductive success of S. pilosa .     

A New Method for Inoculation of Poor Germinator, Nosema sp. NIS M11 (Microsporida: Nosematidae), into an Insect Cell Culture

ABSTRACT. Spores of Nosema sp. NIS M11, primed with 0.1 N KOH solution, were mixed with either physiological salt solutions or IPL-41 medium, an insect cell culture medium, for germination. In the latter medium, only a few spores germinated, while high percentages of spore germination were obtained in physiological salt solutions, particularly in Rinaldini's solution. By using the salt solutions as inoculation media, KOH-primed NIS M11 spores were inoculated into the Spodoptera frugiperda SF21AEII cell line. The initial infection levels were consistently higher than that obtained by using IPL-41 medium. Among the salt solutions, Rinaldini's solution, containing KCl in place of NaCl, gave the highest percentage of initial cell infection. Increased osmolarity of salt solutions did not improve the efficiency of spore germination and infection of N. sp. NIS M11.     

BEHAVIOR OF INTERPHASE EMBRYONIC NUCLEI TRANSPLANTED IN NUCLEAR MULTIPLICATION STAGE EMBRYOS OF DROSOPHILA MELANOGASTER

Interphase nuclei were transplanted from syncytial blastoderm into early cleavage embryos of Drosophila melanogaster. The transplanted nuclei, when exposed to host cytoplasm, were initiated to mitosis. During the period from 10 to 50 min after transplantation, the implanted nuclei and host nuclei were found not synchronous in their mitotic cycles. Synchrony was restored usually by the blastoderm stage.
About 5% of eggs with transplanted nuclei developed significantly faster than control eggs, resulting in premature blastoderm formation. This finding is discussed in relation to chimera formation and to embryonic development of grandchildless mutants.     

Internalization of Embryonal Carcinoma Cells when Aggregated with Normal Mouse Embryos

In the present study, we examined in detail the process of forming chimeric blastocysts between B242g embryonal carcinoma (EC) cells and normal mouse embryos. Electron microscopic observations of the developing aggregates revealed that the embryonic cells spread over the surface of the EC cells, resulting in the internalization of EC cells in the aggregates. When a single blastomere of an 8-cell embryo was aggregated with EC cells, the blastomere spread over and engulfed the EC cells. These results strongly suggest that EC cells are segregated and become situated in the inside position as the development of an aggregate proceeds, and then they are incorporated into the ICM of a blastocyst.     

Viable Chimeras between Embryonal Carcinoma Cells and Mouse Embryos: Comparison of Aggregation and Injection Methods

An embryonal carcinoma (EC) cell line having the ability to form chimeric mice was isolated from embryo-derived teratocarcinomas experimentally induced in BALB/cCrSlc mice. This EC cell line, B242 g, was one of the 5 EC cell lines pre-selected based on the ability to incorporate into blastocysts by means of aggregating with 8-cell mouse embryos.
Using the B242g EC cells, the effectiveness of producing chimeras was compared between two currently available techniques, aggregation and injection, by examining chimerism of the midgestationally recovered conceptuses and live-born mice. The present result revealed that EC cells studied here were able to form chimeras more efficiently by injection as compared to aggregation method.     

Studies on nitrogen metabolism in tobacco plants IX. Effect of various compounds on proline biosynthesis in the green leaves

In order to obtain information on the correlation between thebiosynthesis of proline from glutamate and photosynthesis ingreen leaves, the effects of various substances on proline formationfrom ¹⁴C-glutamate have been investigated using tobacco leafdisks in the light. Inhibitors of oxygen evolution in photosynthesis,such as CMU, strongly inhibited the proline formation. The inhibitioncould not be reversed by the addition of reduced NADP, ascorbateplus 2,6-dichlorophenol-indophenol or ATP. Uncouplers or inhibitorsof photophosphorylation such as DNP, arsenate, chlorpromazineand octyl guanidine suppressed the formation of proline fromglutamate. In old leaves, the addition of ADP or ATP markedlyaccelerated proline formation, while neither of these compoundswas effective in young leaves. It was inferred that the reductionof glutamate to ¹-pyrroline-5-carboxylate in green leaves isclosely associated with noncyclic photophosphorylation. (Received August 17, 1967; )     

Ecteinascidia turbinata Extract Activates Components of Inflammatory Responses Throughout the Phylogenetic Spectrum

The tunicate Ecteinascidia turbinata contains a substance orsubstances capable of exerting a number of biological effects.Extracts of tunicate tissues have been shown to kill tumorcells in vitro and arrest tumor growth in vivo. The extractsalso suppress allograft rejection, graft-US.-host reactionsand lymphocyte proliferative responses as well as humoral responsesto immunization. By modifying the conditions, the extracts couldpotentiate antibody responses. In addition, they augment functionsof monocyte-macrophages as evidenced by in vitro phagocytosis,in vivo clearance, and cytotoxic activity against target cells.After studies in mice, we were able to demonstrate that theextracts could activate the phagocytic systems of shrimp, bluecrab, and fish (the American eel). In fish, the intraperitonealroute was superior to the intravenous route for promotion ofphagocytosis, increase in percent presentation of granulocytesand for enhancement of resistance to bacterial infection. Intrarriuscularand intraperitoneal injection led to local inflammation withaccumulation of granulocytes and macrophages.