Prothoracicotropic Hormone Bioassay: Pupal-Adult Bombyx Assay

Blockage of adult development by brain removal and its resumption by application of the prothoracicotropic hormone (PTTH) were studied using pupae of a racial hybrid J-122 × C-115 of Bombyx mori . A log-linear dose-response relationship was obrained after injection of a PTTH solution. The Bombyx -unit of PTTH has been defined from this dose-response curve.     

The Hill reaction and oxygen uptake in isolated pine chloroplasts

1. The Hill reaction and oxygen uptake in chloroplasts preparedfrom pine leaves were studied. Pine chloroplasts active forthe Hill reaction were isolated from mature leaves in the presenceof 25% PEG in the isolation buffer. Time courses of the Hillreaction in chloroplasts isolated from leaves at different seasonsdiffered. In chloroplasts isolated in the autumn, Hill activitydecreased rapidly with illumination time. This rapid decreaseof Hill activity was inferred to result from concomitant productionof some inhibitory substance(s) during the Hill reaction.
2. Theprotective effect of PEG on inactivation by aging of pinechloroplastswas found. In the presence of PEG, chloroplastswere stabilizedand Hill activity was maintained even afterstorage for 26 hr;whereas, in the absence of PEG inactivationby aging proceededrapidly and oxygen uptake occurred after20 hr.
3. Chloroplastsisolated without PEG had no ability of the Hillreaction; but,inversely showed pronounced oxygen uptake. Oxygenuptake wasalso observed in aged or DCMU-inhibited chloroplasts.The presenceof benzoquinone strongly suppressed oxygen uptake.

¹ Present address: Laboratory of Biology and Chemistry, Universityof Naval Architecture of Nagasaki, Nagasaki, Japan. (Received January 27, 1971; )     

Permeability of the Nitella internodal cell to organic substances as measured by the double chamber method

Permeability coefficients for the cell membrane of Nitella jlexilishave been determined for some organic substances by measuringtheir transcellular transport with the double chamber method.Benzyl alcohol is rapidly taken up in the vacuole of the cell.In the double chamber method benzyl alcohol taken up in thevacuole at one end of the cell is not as rapidly transportedto the other end as expected from the rate of protoplasmic streamingin the vacuole. This can be explained by assuming the presenceof a "non-streaming part" in the vacuole. The uptake of ureainto the streaming part of the cell is stimulated by directlyilluminating the part where the cell is immersed in urea solution. (Received March 10, 1971; )     

Population structure of wild wheat D‐genome progenitor Aegilops tauschii Coss.: implications for intraspecific lineage diversification and evolution of common wheat

Aegilops tauschii Coss. is the D‐genome progenitor of hexaploid wheat. Aegilops tauschii, a wild diploid species, has a wide natural species range in central Eurasia, spreading from Turkey to western China. Amplified fragment length polymorphism (AFLP) analysis using a total of 122 accessions of Ae. tauschii was conducted to clarify the population structure of this widespread wild wheat species. Phylogenetic and principal component analyses revealed two major lineages in Ae. tauschii. Bayesian population structure analyses based on the AFLP data showed that lineages one (L1) and two (L2) were respectively significantly divided into six and three sublineages. Only four out of the six L1 sublineages were diverged from those of western habitats in the Transcaucasia and northern Iran region to eastern habitats such as Pakistan and Afghanistan. Other sublineages including L2 were distributed to a limited extent in the western region. Subspecies strangulata seemed to be differentiated in one sublineage of L2. Among three major haplogroups (HG7, HG9 and HG16) previously identified in the Ae. tauschii population based on chloroplast variation, HG7 accessions were widely distributed to both L1 and L2, HG9 accessions were restricted to L2, and HG16 accessions belonged to L1, suggesting that HG9 and HG16 were formed from HG7 after divergence of the first two lineages of the nuclear genome. These results on the population structure of Ae. tauschii and the genealogical relationship among Ae. tauschii accessions should provide important agricultural and evolutionary knowledge on genetic resources and conservation of natural genetic diversity.     

Species Specificity of the Insect Prothoracicotropic Hormone (PITH): the Presence of Bombyx-and Samia-Specific PTTHs in the Brain of Bombyx mori

Crude extracts of Bombyx mori brains can provoke adult development when injected into brain-removed dormant pupae of Bombyx mori and Samia Cynthia ricini. From this fact the prothoracicotropic hormone (PTTH) of Bombyx has long been thought to be species-nonspecifically active on Samia. Chemical fractionation of Bombyx brain or head extracts by fractional precipitation with acetone, Sephadex G-50 gel-filtration, and DEAE-Sepharose CL-6B chromatography, however, separated the fractions which activated Bombyx brainless pupae from those which activated Samia. Those results reveal the existence of two species-specific PTTHs.     

Origins of Laboratory Mice Deduced from Restriction Patterns of Mitochondrial DNA

To determine the origins of laboratory mice, the restriction patterns of mitochondrial DNAs (mtDNAs) from various strains were compared with those of relevant subspecies and/or races of mus musculus . In most strains and substrains of laboratory mice examined (50/55), the cleavage patterns were identical to those of the European subspecies M. m. domesticus . Those that varied include two sublines of NZB, the strain NZC, and the Japanese strain RR. The NZB and NZC patterns were identical to that of the European subspecies M. m. brevirostris , which itself has restriction patterns similar to M. m. domesticus . On the other hand, the RR pattern was identical to M. m. molossinus -like mice trapped in Western China and slightly different from Japanese M. m. molossinus . These findings suggest that the strains NZB and NZC stemmed from a European founder stock which differed from the ancestral stocks of other laboratory strains and that the ancestral mice of the RR strain had been transported from China to Japan. Therefore, most laboratory strains of mice are derived from the European subspecies M. m. domesticus while M. m. brevirostris and M. m. molossinus have made minor contributions. M. m. musculus does not appear to have made any contribution.     

Quantitative Analysis of Protein Synthesis Altered by Estrogen in Cultured Xenopus Liver Parenchymal Cell

Using the primary culture system of male Xenopus laevis hepatocytes consisting of more than 95% parenchymal cells, the effect of estradiol-17 β (10⁻⁶M) on protein synthesis was quantitatively analyzed by ³H-leucine incorporation kinetics and the estimation of specific radioactivity of newly synthesized secretory protein. The cells in a well defined culture revealed high plating efficiency and very low DNA synthetic activity. The cultured cells could synthesize several secretory proteins containing serum albumin. The pattern of secreted proteins in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) did not alter with culture time but secretion rate of protein increased for 7 days, starting on the third day following inoculation. Estradiol added to the culture media extensively induced the synthesis of yolk precursor protein vitellogenin which accounted for 40–50% of the overall secretory protein synthesis and 20–30% of the total protein synthesis on day 7 of estradiol treatment. Ultimately, the total protein synthesis and secretory protein synthesis were stimulated 1.2–1.3 fold and 2.0–2.2 fold, respectively, over those of the control cells cultured in the absence of estradiol. These results indicated that the stimulation of protein synthesis was largely due to vitellogenin production. Such an estradiol-dependent stimulation of protein synthesis was also detected in the low molecular weight protein(s). On the other hand, albumin synthesis was evidently reduced by estradiol. Thus, estradiol had two different effects on protein synthesis.
The results obtained in this study will be discussed in relation to the findings o in vivo experiments.