Mating frequency and genetic relatedness of workers in the hornet Vespa analis (Hymenoptera: Vespidae)

Mating frequency of Vespa analis queens and the genetic relatedness of their workers was analyzed by DNA microsatellite genotyping. Of 20 colonies studied, 18 had a queen inseminated by a single male and two had queens each inseminated by two males. The estimated effective number of matings was 1.05 ± 0.037 (mean ± SE), with 75–85% of the offspring of the two multiply mated queens sired by a single male. The pedigree relatedness between nestmate workers averaged over the 20 colonies was estimated to be 0.74 ± 0.008, almost identical to the predicted value of 0.75 for colonies headed by a singly mated queen. Multiple matrilines; that is, the presence of workers not related to the current queens, were detected in six colonies, suggesting that queen replacement occurred via usurpation of the founding queens in these six colonies. These results demonstrate that the kin structure of V. analis is similar to that reported in other vespid species.     

Dihydrofolate Reductase in Starfish Oocytes and Embryos: Developmental Consequences of Its Inhibition by Methotrexate1

Dihydrofolate reductase in immature oocytes of the starfish, Asterina pectinifera, is estimated to be 12 pg per oocyte. After completion of meiosis, the quantity of the enzyme is approximately 20 pg per egg. The content of the enzyme in the egg is kept nearly constant at this value from fertilization to the beginning of blastulation. Methotrexate, an analogue of dihydrofolate, at 20 μM did not affect meiotic maturational process and fertilization, but inhibited embryonic development at the 512-cell stage which corresponds to the beginning of blastulation. Incorporation of externally supplied deoxy[³H]uridine into DNA of the embryos cultured in the continuous presence of 20 μM of methotrexate stopped at the 256-cell stage, suggesting that the cessassion of development of the embryo at the 512-cell stage was caused by inhibition of DNA synthesis at the preceding stage. Uptake of [³H]methotrexate was low at early cleavage stages but increased just before blastulation. Externally supplied 1 mM of thymidine counteracted the inhibitory effect of methotrexate at 20 μM, suggesting that the starvation of the methotrexate-treated embryo for thymidine nucleotides halted DNA synthesis at the beginning of blastulation.     

VITELLOGENIN IN THE EGGS OF THE COCKROACH, BLATTELLA GERMANICA: PURIFICATION AND CHARACTERIZATION

Vitellogenin in the eggs of Blattella germanica was solubilized with solutions at high salt concentrations and high pH. This protein was purified by ammonium sulfate precipitation, acetic acid precipitation, DEAE-cellulose chromatography, and hydroxylapatite chromatography, into a chromatographically homogeneous state. By sucrose density gradient centrifugation, the purified vitellogenin was resolved into two components. The relative amounts of the two components varied according to the pH of the solution. An equilibrium seemed to exist in the interconversion between them when the conditions of the solution were fixed. It is suggested that aggregation and disaggregation of the vitellogenin molecules may account for the apparent heterogeneity.     

AN ANALYSIS OF THE EFFECT OF "CONDITIONED MEDIUM" UPON THE CELL CULTURE AT LOW DENSITY

A favorable effect of “conditioned medium” upon outgrowth of the cell culture with low density in vitro was analysed with the cells of chicken embryos. For preparing “conditioned medium”, cultures with a large number of cells were made with muscle, kidney, lung, liver and skin, while the biological activity of the medium was assayed by using the culture of a small number of the lung secondary cells. A use of “conditioned medium” was found to be necessary for encouraging the outgrowth of the cultured cells below a critical inoculum size. Of the various types of the media tested, the medium conditioned with muscle was most effective. “Conditioned medium” contained at least two different active factors, the first to enhance the plating efficiency of the inoculated cells to the surface of the culture dish, and the second to promote further outgrowth of the plated cells. “Conditioned medium” taken out of the mass culture at its exponentially growing phase had only the second factor, while that taken out of that at its stationary phase contained both factors. An activity of the first factor was not detected, when the mass culture was kept in such condition that the collagen synthesis was inhibited. The factor for enhancing the plating efficiency was eliminated from “conditioned medium” by preincubating the cells, before assaying the effect of the medium.     

EFFECT OF GIBBERELLIC ACID ON ELONGATION AND NUCLEIC ACID SYNTHESIS IN ETIOLATED ALASKA PEA EPICOTYL

The following results were obtained using etiolated Alaska pea epicotyls. Gibberellic acid (GA) had the remarkable effect on the elongation in part I (elongating region) of epicotyls, whereas it had little effect on that in part II (mature region) of epicotyls. In cortex of part I and II of epicotyls, the cell number in longitudinal direction was hardly affected by GA. On the increase in width of epicotyls, GA was hardly effective in any parts of epicotyls. In both part I and II GA enhanced the incorporation of ³²P into all nucleic acid fractions prepared by methylated albumin kieselguhr (MAK) columns, i.e. sRNA, DNA and rRNA + mRNA. In part I the net increase in DNA and RNA content during the incubation period was slightly promoted by GA, whereas in part II the net decrease in both nucleic acids content was slightly promoted by GA. The relationship between GA-induced growth and nucleic acid synthesis is discussed.     

ACCUMULATION OF 4-O-β-D-GLUCOSIDE OF PROTOCATECHUIC ACID IN THE LEFT COLLETERIAL GLAND OF THE COCKROACH, PERIPLANETA AMERICANA. II. HORMONAL REGULATION

The amount of protocatechuic acid glucoside in the left colleterial gland changes with the reproductive cycle. Allatectomy, beheading and injection of actinomycin D cause inhibition of the accumulation of glucoside, but glucoside resumes to accumulate in the left colleterial gland with the reimplantation of corpora allata into the allatectomized cockroaches.
When ¹⁴C-glucose was injected in normal animals, radioactive glucoside was accumulated in the left colleterial gland whereas in the allatectomized cockroaches, it was not accumulated in the gland but was found abundantly in blood.
The level of protocatechuic acid glucoside synthetase activity of the fat body tissue and of the left colleterial gland was assayed. The enzyme activity in the left colleterial gland was not affected by allatectomy but that in the fat body was slightly affected.
The mechanism of accumulation of protocatechuic acid glucoside in the left colleterial gland and the endocrine control on the accumulation are discussed.     

Ammonia as an important nitrogen source for the photosynthetic growth of Rhodospirillum rubrum

The growth of Rhodospirillum rubrum strain K was poor in a glutamatemalate(G-3-X) medium under light-anaerobic conditions. The supplementof ammonia to the G-3-X medium remarkably stimulated the growth.No such stimulation by ammonia was observed under dark-aerobicconditions. The other bacterium, strain M, also showed a similartendency for the ammonia requirement, though its growth in theG-3-X medium was much more abundant as compared to that of strainK. Casamino acid was found to contain stimulating factors for growth.Among the amino acids, arginine and/or histidine were effective.The other factor in casamino acid was found to be ammonia. The crude extracts of strains K and M contained glutamic dehydrogenaseas judged by the formation of glutamate from -ketoglutarateand ammonia. The highly reduced state of the cell componentsunder lightanaerobic conditions, appears to limit the formationof ammonia from glutamate. Ammonia was a preferable nitrogensource to glutamate under the conditions employed. ¹Present address: Institute for Agricultural Research, TohokuUniversity, Sendai. ²Present address: Sanitary Engineering Research Laboratory,Sanitary Engineering Department, Sumitomo Machinery Co. Ltd.,Hiratsuka.