Characterization of Mendelian and Non-Mendelian Mutant Strains by Micronuclear Transplantation in Paramecium tetraurelia

ABSTRACT. Mutant strain d48 and d12 cannot express serotype A. In d48, the A i-antigen gene is present in the micronucleus, but not in the macronucleus. It has recently been shown that d12 contains the A gene in its micronucleus, but its macronucleus lacks the gene. Micronuclear transplantations into enucleated cells were performed to analyze those mutants. Reciprocal transplantation between wild type and d48 confirmed that d48 contains the A gene in the micronucleus and its cytoplasm is defective. Wild type 51 enucleated cells into which were transplanted d12 micronuclei could not express A. Amiccronucleate d12 cells into which were transplanted normal micronuclei from 51 or d48 showed no expression of A. These results show that even if the micronucleus of d12 contains the A gene, it must be abnormal, and its cytoplasm is also defective the same as d48. Genetic analysis showed that heterozygote of d12 and wild type 51 or d48 caused a cure of the cytoplasmic defect of d48 and d12 during the development of macronuclei.     

Is Geomagnetic Sensitivity Real? Replication of the Walker-Bitterman Magnetic Conditioning Experiment in Honey Bees

Although the presence of geomagnetic sensitivity has been suspectedfor a long time in a variety of marine and terrestrial animals,many responses reported in the literature have been based onextensive statistical analysis of orientation results or relyon obscure behavioral activities (like cetacean strandings orhoney bee waggle dances.) None of these reports have yet approachedthe level of clarity and simplicity displayed in experimentswith the magnetotactic bacteria, which is the best example ofgeomagnetic sensitivity in any living organism. Furthermore,claims of magnetic effects on living organisms pervade the literatureof biomagnetism, but many have failed subsequent attempts atreplication. We need to develop simple and easily replicatedexperiments for marine and terrestrial animals which can bemodified to answer basic questions concerning the psychophysicsof any geomagnetic sensory system which might be present. Inthis paper, we report the first replication of the Walker-Bittermanmagnetic anomaly conditioning experiment in honey bees, as wellas one of our attempts to slightly alter their basic protocol.We also report our attempts to condition honey bees to magneticdirection in simple maze experiments, and the initial resultsof a pulse-remagnetization experiment designed to test the ferromagnetictransduction hypothesis. We conclude honey bees are sensitiveto the geomagnetic field, that the signal processing for itis more complex than previously thought, and that a ferromagnetictransducer is compatible with all known behavioral data.     

Accumulation and Spatial Distribution of Poly(A)+RNA in Oocytes and Early Embryos of Drosophila melanogaster

We describe the accumulation and distribution of poly (A)⁺RNA during oogenesis and early embryogenesis as revealed by in situ hybridization with a radio-labeled poly (U) probe. The amount of poly (A)⁺RNA in nurse cell cytoplasm continuously increased untill mid-vitellogenic stage (st. 10), then decreased with the rapid increase of poly (A)⁺RNA in the oocyte (st. 11). The localization of poly (A)⁺RNA at stage 10 was in the anterior region of the oocyte, where it is connected by cytoplasmic bridge to the nurse cells. These observations indicate that most of the poly (A)⁺RNA synthesized in the nurse cells is transferred to the oocyte through the cytoplasmic bridges at stage 10–11. During the remainder of oogenesis (st. 11–14) and during preblastodermal embryogenesis, poly (A)⁺RNA was evenly distributed over the cytoplasm of oocytes and embryos. At blastoderm stage, poly(A)⁺RNA became concentrated in the peripheral region of embryos. Though the somatic nuclei of the blastoderm contained a detectable amount of poly (A)⁺ RNA, the pole cell nuclei did not. The cytoplasmic RNA visualised by acridine orange staining and the poly (A)⁺RNA detected by hybridization with [³H]poly (U) exhibited identical distributions during oogenesis and early embryogenesis. These observations provide a basis to assess the unique distributions of specific RNA sequences involved in early development.     

Maternal Messenger RNA as a Determinant of Pole Cell Formation in Drosophila Embryos

Some polar plasm components are UV-sensitive. Messenger RNA extracted from oocytes or cleavage embryos can to induce pole cells in embryos that have been deprived of ability to form pole cells by UV-irradiation. This article reviews studies on the role of this mRNA in the developmental pathway leading to germ cell formation.     

Macrophage Activation by Tetrahymena pyriformis II. Active Protein Fractions from Tetrahymena

ABSTRACT. Water-soluble and 0.6 M KCl-soluble protein fractions prepared from Tetrahymena pyriformis , when inoculated into mice, could effectively induce activated macrophages having the ability to kill Toxoplasma gondii in vitro. This effect was not induced by other proteins tested, such as bovine serum albumin, pepsin from porcine stomach mucosa and chicken egg-white lysozyme, nor by muramyl dipeptide (MDP), a potent immunoadjuvant. Five fractions obtained by DEAE-Sephadex chromatography of the water-soluble protein fraction were compared with regard to induction of toxoplasmacidal activity in macrophages. The first peak was most effective for activation of macrophages. Five fractions obtained by chromatography of the 0.6 M KCl-soluble protein fraction were also examined and it was found that the first peak had the activity. No marked difference in activity was observed between the active fractions of water-soluble and 0.6 M KCl-soluble protein fractions. For practical use, we focused on the water-soluble active fraction. The minimum effective dose of the active fraction was 100 μg and the fraction could activate macrophages directly in vitro. Four fractions obtained by gel filtration of the active fraction on Sephadex G-200 were compared and the first peak had the activity. The first peak contained a single protein, revealed by SDS-polyacrylamide gel electrophoresis; its apparent molecular weight was 64,000.     

Effects of Host Cell Density on Cell Infection Level in Antheraea eucalypti (Lepidoptera: Saturniidae) Cell Cultures Persistently Infected with Nosema bombycis (Microsporida: Nosematidae)

ABSTRACT. Spores of Nosema bombycis Y9101, isolated from the beet armyworm, Spodoptera exigua , were primed with an alkaline solution and inoculated into Antheraea eucalypti cell cultures. Infected cells were subcultured every five days at three cell densities (2.5 × 10³, 5.0 × 10³, and 1.0 × 10⁴ cells/cm²). A difference was observed in the spread of N. bombycis Y9101 infection between low-density and higher-density cultures of host cells. The host cell density did not affect the productivity of secondary infective forms of the parasite. The principal factor determining the rate of microsporidian infection in vitro was the number of host cells existing within the reach of extruded short-coiled polar tubes from spores germinated intracellularly.     

Inhibitory Action of Blue and Far-Red Light in the Flowering of Lemna paucicostata

In a new strain of short-day duckweed (Lemna paucicostata T-101), blue and far-red light-induced inhibition of flowering was investigated. Flowering of this strain failed to be induced under a short-day photoperiod of blue and far-red light, although it responded as a typical short-day plant in red and white light. When the short-day photoperiod of blue or far-red light was terminated by a 15 min red light pulse, flowering recovered completely. This inducing effect of red light was reversed by subsequent exposure to far-red light. Furthermore, it could be demonstrated that 30 min of blue light completely reversed the flowering inductive effect of 5 min red light and vice versa. Evidence is presented suggesting that the inhibitory action of blue and far red light may be due to the lowering of phytochrome P_fr levels below those required to start the dark reactions which lead to flowering. These results are discussed in relation to the time measurement system of photoperiodism.     

Cytokinin Activity of Benzoylaminodeazapurines, Pentanoylaminodeazapurines and their Corresponding Purine Analogs in Five Bioassays

Cytokinin activities of 6-benzoylamino-1, 6-benzoylamino-3-, 6-pentanoylamino-1- and 6-pentanoylamino-3-deazapurines and their corresponding purine analogs, 6-benzoylaminopurine and 6-pentanoylaminopurine, were examined using five bioassay systems, tobacco callus growth, bud formation on tobacco callus, lettuce seed germination, fresh weight increase of radish cotyledons and retardation of chlorophyll degradation in radish cotyledons. 6-Benzoylamino- and 6-pentanoylamino-1-deazapurines showed stronger cytokinin activity than their corresponding purine analogs in all bioassays used. In tobacco callus growth, 6-benzoylamino-1-deazapurine was nearly as active as zeatin, one of the most active adenylate cytokinins. On the other hand, 6-benzoylamino- and 6-pentanoylamino-3-deazapurines were as active as or less active than corresponding purine analogs.     

Studies on the metabolism of a sulfur-oxidizing bacterium IV.1 Growth and oxidation of sulfur compounds in Thiobacillus thiooxidans

By immersing a few small cellophane bags containing BaCO³ powderin STARKEY's medium, the duration of lag phase in the growthof Thiobacillus thiooxidans is minimized and the yield of cellsis increased ten times that of the previous method. The activitiesof oxidation for sulfur and sulfite change with growth. Sulfiteis oxidized at a comparable rate to that of sulfur oxidationat pH values between 6.0 and 6.5. In the presence of cysteineor glutathione, thiosulfate can be oxidized at a pH above 5.0.At pH values below 4.5, apparent oxidation of thiosulfate andtetrathionate to sulfate is observed. This result is accountedfor by the facts that thiosulfate is decomposed to sulfur andsulfite under the acidic condition at pH values below 4.5, andthat tetrathionate is reduced to thiosulfate enzymatically.In the oxidation of tetrathionate, oxygen uptake begins aftera lag phase, the duration of which depends on the concentrationsof cells and of tetrathionate. Cysteine is oxidized to cystine.The oxidation is strongly inhibited by metal-chelating agents.The cysteine oxidizing activity is, however, quite stable andis not lost by treating cells with organic solvents, sonic oscillation,by heating or lyophilization. ¹III=References (11). ²Partly supported by a grant from the Ministry of Education.