Developmental Stages of the Society Finch, Lonchura striata var. dornestica.

The society finch, a little passerin, was purposed to be utilized in embryological studies. Under control of the breeding cycle in 20 pairs, 4 to 6 eggs were used to be laid daily for several repeating week in a year. Average incubation time was 17 days in contrast to 21 in the domestic fowl. The eggs weighed 1.1 g in average and expected smallness of the embryo was regarded as favorable for morphological studies including the scanning electron microscopy. We present the first report of the complete development of the society finch. A number of embryological characteristics are described with special reference to the peculiarity of the altricial finch as compared with the precocial domestic fowl.     

Timers in Early Development of Sea Urchin Embryos

To elucidate the timing mechanisms in the early development of sea urchin embryos, we measured the times of initiation of the first four cleavages, of ciliary movement, of primary mesenchyme cell ingression, and of gastrulation at four temperatures ranging from 11 to 20°C. The times of cleavage and of initiation of ciliary movement showed similar temperature dependency, indicating that these events may be controlled by a common timer (the first timer). Although batches of eggs often showed variation in the period between fertilization and the first cleavage, their subsequent cleavages were more regular. This indicates that the first timer may not start at fertilization. The ingression of mesenchyme cells and the onset of gastrulation showed similar temperature dependency that was higher than that of other events, suggesting the existence of a second timer. Temperature shift experiments indicate that the second timer starts at the mid-blastula (the 8–9th cleavage) stage when divisions of blastomeres become asynchronous.     

Metabolism of Round Spermatids: A Possible Regulation of Hexose Transport

Round spermatids (steps 1–8) were isolated from rat testes and glucose transport into the cells was examined. The exposure of spermatids to glucose resulted in an extremely low level of ATP. In contrast, the level of ATP remained constant in the presence of pyruvate. Transport of a glucose analogue, 2-deoxy-D-[³H]glucose ([³H]dGlc) into spermatids was correlated with intracellular levels of ATP and was much greater in cells with higher rather than lower levels of ATP. [³H]dGlc transport into spermatids with low levels of ATP was partially reversed when the cells were incubated with pyruvate. Inhibition of [³H]dGlc transport was exerted on Vmax and not on Km. Moreover, glucose acted as a competitive inhibitor of [³H]dGlc uptake (Km increased; Vmax unaltered). These results suggest that glucose transport into spermatids is active in vitro and probably regulated by the intracellular level of ATP.     

Tissue- and Stage-Specific Expression of Sericin Genes in the Middle Silk Gland of Bombyx mori

Sericin gene expression in the middle silk glands during Bombyx mori larval development was analyzed using probes from a genomic DNA clone for 10.5 kb sericin mRNA. The 10.5 kb mRNA, the most abundant in the fifth instar, is not detected in the third feeding, fourth feeding and fourth moulting stages. It becomes detectable at 2 days of the fifth instar, and accumulates rapidly. The second major mRNA in the late fifth instar, a 9.0 kb component having a similar sequence to the 10.5 kb mRNA, becomes detectable only at 6 and 7 days of the instar by use of the repetitious coding sequence probe of the sericin clone. Using the same probe about 20 kb RNAs with a fainter intensity than that of the major mRNAs are detected. They are present extremely faintly in the third and fourth feeding stages, disappear in the fourth moulting stage, and increase in the fifth instar. Two other faint poly(A)⁺ RNA components are detected by a DNA probe containing the 5' end sequence of the sericin clone. One is 4.3 kb, and appears in the third, fourth and fifth feeding stages but not in the fourth moulting stage. The other is 3.0 kb, and it becomes detectable after 1 day of the fifth instar.     

Protein Synthesis during Photocontrolled Progression of the Cell Cycle in Single-celled Protonemata of the Fern Adiantum Capillus-veneris

Protein synthesis during photoinduced, synchronous progression of the cell cycle in single-celled protonemata of the fern Adiantum capillus-veneris was studied by tracer techniques. Nuclei of the protonemata were labelled with ³H-thymidine during spore germination so that the amount of ³H incorporated into the TCA-insoluble fraction of the cells could be used as a measure of the cell number in each sample. The rate of the incorporation of ¹⁴C-amino acids into TCA-insoluble materials was not significantly varied at different stages of the cell cycle or by treatment with blue light. Extracts of cells labelled with ³⁵S-methionine at various times after the transfer from red light condition (G₀) to darkness (G₁ to S) were analyzed by two-dimensional gel electrophoresis. At least 3 of about 200 spots showed significant changes in intensity on fluorograms. Spot A (molecular weight 20,000, isoelectric point 6.3) was detectable only in early G₁, whereas spot B (molecular weight 19,500, isoelectric point 6.3) was found only in the late G₁ and S phases. When the cells were exposed to blue light before the dark incubation, the times of disappearance of spot A and appearance of spot B were advanced depending upon the progression of the cell cycle but not upon the clock time.     

FURTHER NOTES ON THE GROWTH AND CHLOROPHYLL FORMATION OF CHLORELLA PROTOTHECOIDES

1. Using area of a fixed concentration as a nitrogen source,cells of Chlorella protothecoides were grown in the presenceof various carbon compounds. Magnitudes of growth of the cellswere widely different depending on the carbon sources used;glucose and fructose being most favourable substrates and galactose,glycerol and acetate coming next. But the amounts of chlorophyllformed in the cells during the experimental period were almost,the same irrespective of the different carbon sources, withsome exceptions. The similarity of the chlorophyll level observedin these experiments seemed to indicate that the formation ofchlorophyll was limited largely by the nitrogen source but notby the carbon source. 2. Strong bleaching effect was recognized with glucose and fructoseat their high concentration, which produced totally chlorophyll-lesscells. On the other hand, a stimulating effect on chlorophyllformation was observed with galactose at the different concentrationsexamined. 3. Effects of glycine and ammonium carbonate as the nitrogensource on the algal growth and pigmentation were studied insome details. The results were similar to those previously obtainedwith urea, confirming our previous conclusion that the algalpigmentation is profoundly affected by the concentration balancebetween glucose and nitrogen source. ¹Present address: Tokyo Research Laboratories, Tanabe SeiyakuCo., Toda-machi, Saitama.     

PHOTOOXIDATIVE CONSUMPTION AND PHOTOREDUCTIVE FORMATION OF ASCORBIC ACID IN GREEN LEAVES

1. From leaves of barley and spinach, cellular components wereisolated and brought together under various conditions to investigatethe fate of ascorbic acid as affected by the components in thelight and dark. 2. A new colorimetric method for assaying ascorbic acid andsome other reducing substances was devised, measuring the colorof molybdenum-blue developed by the substances in the presenceof excess amounts of phosphomolybdate and inorganic acid. 3. The photooxidation of ascorbic acid by green and yellow filtrates,prepared from green and etiolated leaves of barley, was studiedby the ordinary as well as the new colorimetric method. In thepresence of oxygen, the oxidation of ascorbic acid was foundto be accelerated by light in the green filtrate, but not inthe yellow filtrate. 4. The oxidation of the endogenous reducing substance containedin the supernatant fraction of spinach leaf extracts was studiedin the presence of washed chloroplasts (spinach). In the presenceof oxygen, the rate of oxidation in the light was markedly higherthan in the dark. From the changes in absorption spectrum accompanyingthe reaction, the endogenous reducing substance in questionwas identified as ascorbic acid. 5. The occurrence of an endogenous precursor of ascorbic acidin spinach leaf extracts was disclosed. The photoreduction ofthis precursor into ascorbic acid was studied in the precenceof spinach chloroplasts. A specific inhibition of this reactionby phosphoglycerate and glycerophosphate was discovered. 6. The experimental results obtained were discussed in connectionwith the role of ascorbic acid in photosynthesis. (Received September 13, 1960; )     

ENDOGENOUS CHANGES OF PHOTOCHEMICAL ACTIVITIES OF SPINACH LEAVES

The activities of green cell-free extracts of spinach leavesin performing photochemical transphosphorylation, photosyntheticphosphorylation, the HILL reaction and the light-induced formationof the endogenous reducing substance (ascorbic acid) were followedin parallel during the growth process of the plant. There wasa certain parallelism between the development of the activitiesof photochemical transphosphorylation, of photo-synthetic phosphorylationand of the HILL reaction, activities being low in the earlierstage of growth, reaching a maximum just before efflorescence,and showing thereafter a more or less sharp decline. The activityin the light-induced formation of endogenous reducing substancewas undetectable for the first 35 day-period of growth, reacheda maximum about one week earlier than the other three activities,and again disappeared after 60 days of growth. (Received September 9, 1960; )     

Synchronization of Mating Reactivity Rhythms in Populations of Paramecium bursaria

Cell populations of Paramecium bursaria show arhythmic mating reactivity after exposure to constant light (LL) for more than 2 wk. After this arhythmic population is exposed to darkness for 9 h, the mating reactivity rhythm of the cell population reappears. The phases of rhythms in individual cells are synchronized to each other. When the arhythmic population in constant light is exposed to dark pulses of various durations, the first peak of the recovered mating reactivity rhythm appears 6 h after the end of the dark pulse. Thus, in the case of dark pulses to cells in LL, the transition from dark to light sets the phase of the subsequent mating reactivity rhythm. When an arhythmic population in LL is transferred to constant darkness (DD), a rhythm of mating reactivity also appears and, in this case, the first peak of the rhythm occurs 18 h after the LL to DD transition. Therefore, arhythmic populations of cells in LL can be synchronized by either a dark pulse or by transition to continuous darkness. When the arhythmic populations in LL were transferred to various light/dark (LD) cycles, the mating reactivity rhythms entrained to LD cycles of 18 to 30 h in duration. Finally, mating rhythms can also be synchronized by treatment with puromycin (400 μg/ml for 6–18 h).     

蜥臀目霸王龙及有鳞目沧龙牙齿组织的微细结构

本文是利用扫描电子显微镜对陆栖恐龙tvrannosaurid与海栖渐增mosasaurid”牙齿结构进行的比较解剖学研究。化石采自加拿大RedDeerhiverValley上白里统Horse－shoeCanyon组。通过研究地层中出现的生物化石,特别是动物牙齿的组织结构,可以了解动物为了适应生活环境而发生的进化过程,也可以推测它们的系统发育关系。tyrannosaund与mosas。id都拥有锥状的同形齿,牙齿侧向扁平,且略向后弯曲。研究结果确认了tyrannosaurid的牙齿由于薄层的无柱釉质bPrismaticenamel）向齿质的侵人而造成许多的凹凸构造,此锯齿状构造沿着牙齿的前后缘,由牙齿的顶端分布至基部。因此tyrannosaurid的牙齿呈现着锐利的切缘;在这些凹凸状切缘的沟与小窝的深部可观察到有机物的沉积。但是类似的锯齿状构造只能在齿冠呈钝圆状的mosasaurid牙齿的基部附近观察到。我们以扫描电子显微镜（SEM）检索,确认两爬行类的齿质皆是属于中间型的真性齿质（intermediatetypeorthodentine）;所谓orthodentine即是细管齿质（tubulardentine）。tyrannosaurid的真性齿质的齿质小管只在齿质一釉质相接处Uentino—enamaljunction）附近放散出规则性的分歧与末枝。但mosasaurid的真性齿质的齿质J。管,在齿质的中间层与表层中,呈现着由复杂