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No obvious difference was noted in the composition of pteridine granule membrane proteins among several oily larval mutants. The protein content of the membranes was 61-68%, the lipid content 29-33%, and the carbohydrate content 0.2-1.1%. The amino acid composition of the membrane structural protein obtained from normal larvae was very similar to that from oily larval mutants.SDS-urea polyacrylamide gel electrophoresis of the SDS-urea-treated granule membrane proteins obtained from several oily larval mutants revealed multiple protein bands, unlike that of the granule membrane protein from normal larvae. Moreover, these electrophoretic patterns showed significant differences among several oily larval mutants. The cause of this electrophoretic variation of the membrane proteins (as well as lipid and carbohydrate) from oily larval mutants is discussed.An ultracentrifugal examination of granule membrane protein obtained from the woh mutant demonstrated its heterogeneity. Immunological differences found among granule membrane proteins of w3, wa and wb by the Ouchterlony double diffusion test suggest that the variation is due to some genetic changes in the primary structure of the membrane protein. It is therefore proposed that the structural gene for the membrane protein subunit of pteridine granules may be located at the w3 locus on the 10th chromosome.

1. 黄色致死系 B1 と正常との交雑 F1, F2 の分離の結果から, leml(ly-2) は ly-1 と同様に単純劣性遺伝子であると考えられる.2. 黄色致死系と黄体色系との F1 9区中6蛾区では, 正常蚕と黄体色蚕との 1:1 の比に分離した.3. F1 の正常同志を交配した F2 には正常:黄体色が 3:1 の比に現われ, その子孫に黄色致死蚕は現われない.4. F1 の黄体色同志を交配せる F2 はすべて黄体色蚕のみを生じ, 第1眠起黄色致死蚕は分離しない. しかし特徴ある死卵が総卵数の約1/4現われる. この卵中には黄褐色の蟻蚕を生じているが, これは卵殼を食い破れないため餓死する. この卵を仮に黄色死卵と名付けた.5. F1 黄体色蚕の F3, F4 などの後代には黄体色蚕のみを生じ, leml ホモの個体はすべて卵内にて致死し黄色死卵となる.6. 正常 (+/leml) と黄体色 (lem/leml) との交雑では正逆交雑により, leml ホモの個体の致死時期が判然と異なり, 正常を母体とすれば第1眠起黄色致死蚕が分離し, 黄体色を母体とすれば黄色死卵を分離する. すなわち黄色致死は致死時期に関し母親遺伝をなす.7. +lem, lem, leml の3遺伝子は複対立遺伝子群を構成し, これらの優劣関係は +lem>lem> leml の如くである.8. 黄色致死の原因および黄色致死の母親遺伝の機構には, キサントプテリン B, メラニン, 尿酸などの代謝の間の因果関係, さらにメラニン形成と外皮硬化との因果関係などが重要な要素となつていることが考えられ, これらに関する生化学的な実験を目下続けている.

A number of larvae showing the Nl phenotype were obtained by irradiation of EHEKp/EHEKp individuals. The three Nl types, Nl, Nl1 and Nl2, were investigated. From crossing experiments, it is assumed that Nl mutants are caused by deficiencies in the part of the 14th chromosome which includes the oa locus and that the order of their relative lengths for the three types is Nl>Nl1>Nl2.It was observed that embryos homozygous for Nl1 die at a far more advanced stage than embryos homozygous for Nl and that the development of the embryos homozygous for Nl2 advances still a little further. Thus, the difference in the extent of the deficiency in each of the three Nl mutants relates to the stage at which the respective homozygous embryos die.Spontaneous Nl type mutation occurs very rarely. However, it may be said from the present experiment that the frequency of the mutation increases strikingly as a result of irradiation with X-rays and that the extent of the deficiency in each of the Nl type mutants is not always the same.

1. A number of spherical granules containing yellow pigments and isoxanthopterin are found in the hypodermal cells of the lemon and the dilute lemon larvae.2. The yellow-colored granules have been purified by a new method described in the present study. The chromogranules obtained from the lemon and the dilute lemon larvae show almost the same shape, an irregularly spherical one. The granules obtained from the lemon larvae are much more dense yellow in color than those from the dilute lemon larvae.3. Similarly shaped granules containing isoxanthopterin but smaller in size than those of the lemon and the dilute lemon larvae are present in the hypodermal cells of normal larvae.4. The protein composition of the three types of chromogranules obtained from normal, lemon and dilute lemon larvae has been examined by paper electrophoresis, and characteristic differences have been found in their electrophoretic mobility.5. After the dialysis of the three samples with a visking membrane, the samples have been digested with trypsin and their peptide composition has been examined by high voltage paper electrophoresis and a modified finger printing method. Characteristic differences have been found in the peptide composition of the three types of granules.6. In the lemon larvae, two supernumeray peptides have been found in addition to the common peptides which occur in the three types of chromoprotein. In the dilute lemon larvae, only one additional peptide has been detected and its Rf value differs from that of the supernumery peptide produced by the 2-P of the lemon sample.7. The two supernumerary peptides found in the lemon larvae are believed to be components of the specific protein that has the ability to combine with yellow pigments. The single supernumerary peptide found in the dilute lemon larvae is probably an altered specific protein.8. The specific and the altered specific proteins are apparently produced under the control of the +d-lem and the d-lem gene action, respectively, in the presence of yellow pigments.

1. A silkworm strain showing dilute yellow larval color was found and the genetic constitution of this strain was confirmed to be lem/lem; d-lem/d-lem, whereas that of lemon strain was lem/lem; +d-lem/+d-lem. The d-lem gene belongs to the 2nd linkage group, and is allelic to the i-lem gene.2. For the purpose of studying the manifestation mechanism of dilute lemon gene (d-lem) experiments were carried out.3. The amounts of yellow pigment obtained from lemon larvae is about three times as large as that from dilute lemon larvae.4. The amount of isoxanthopterin obtained from lemon larvae as well as from dilute lemon larvae is much smaller than that obtained from the normals. Furthermore, it was found that the hypodermis of dilute lemon larvae contains a smaller amount of isoxanthopterin than that of lemon larvae.5. None or very weak pterine reductase activity could be detected in dilute lemon larvae like in lemon larvae. Thus, no significant difference has been found in the activity of pterine reductase between lemon and dilute lemon strains.6. To test whether or not inhibition occurs at the step from a precursor to yellow pigment, a cross between normal and dilute lemon strains was carried out and the amount of isoxanthopterin contained in normal larvae which segregated in the F2 generation was determined by single measuring method. No clear-cut evidence of inhibition of pteridine metabolism by d-lem gene could be obtained.7. It is inferred from the experimental results that the following explanation is most plausible. Though the yellow pigment is normally produced, a large part of it is lost from the hypodermal cells owing to a defect caused by the d-lem gene in the system which keeps this compound within the cells. It is inferred that a certain protein is an important factor in combining with yellow pigments and keeping them within hypodermal cells.

1. In the pteridine metabolism of the silkworm, pteridine reductase acts specifically on the reaction step leading from dihydropterin to tetrahydropterin.2. The enzyme activity of the several tissues was examined in normal animals and in the mutants, lem and leml. In the integument of normal larvae the enzyme activity is strong but in that of the lemon larvae it is weak to very weak. Moreover, the integument of the lethal lemon larvae almost completely lacks this enzyme.3. In the reciprocal crosses between the +lem/leml individuals and the lem/leml individuals the maternal effect of the gene +lem on pterine reductase could be demonstrated.4. It is inferred from the experimental results of mutual transplantation of ovaries between normal and lemon larvae that the enzyme activity of the eggs is not determined by the genotype of the eggs but by that of the female in whose body the eggs develop.5. The maternal effect of +lem on the stage of death of the lethal yellow larvae is discussed.

Fifth-instar larve with genotypes +/leml and lem/leml, which had segregated from a cross between +/leml and lem/leml, were used as material. The ovaries of the larvae of both types were exchanged. Of 630 larvae thus operated upon, only 3 survived and had offspring.The female moths produced from these larvae were mated with male moths of the genotype lem/leml. The eggs laid were incubated and larvae homozygous for leml gene were examined.When the +/leml larvae were implanted with ovaries of lem/leml, the homozygous leml embryos which developed from the transplanted eggs hatched out, as the apparently normal ones do, as black-coloured larvae, but they changed into distinctly yellowish larvae which died immediately after the first moulting.On the other hand, the leml homozygous larvae emerging from eggs laid by the lem/leml moth which had received a +/leml ovary by transplantation developed into yellowish-brown young larvae, then died within the egg.From these results it may be concluded that the stage of death of the lethal larvae is not determined by the genotype of the embryo (+/leml or lem/leml) but by that of the mother's body in which the eggs develop.

The albino gene (al) is a simple recessive gene. Embryos homozygous for al develop normally to young larvae which are able to hatch out by chewing up the egg chorion and grow normally during the 1st instar. Their lethality appears immediately after the 1st molting.The phenotype of lethal albino larvae resembles that of lethal lemon larvae. Neither can chew up mulberry leaves owing to insufficient sclerotization of the hypodermal cuticle.Abnormal pteridine metabolism was found in the lethal albino larvae. It is assumed that a step of sepiapterin formation is blocked in their main pteridine metabolic activities.It was found that al/al larval extracts have a lower activity of phenol oxidase than. +al/+al larval extracts.It was suggested that al/al larval extracts have also a lower activity of phenylalaine hydroxylation than +al/+al larval extracts.It seems that in the lethal albino larvae abnormal pteridine metabolism has some close relation to a defective phenylalanine metabolism.Maternal effects of +al gene may explain why young al/al larvae do not show their lethal phenotype inside the eggs.

1. +×H/Kp の交雑において組換により, HKp/++ の個体をえた. 組換価は0.7%であつた. H+/Kp と HKp/++ との表現型は異なる.2. +×HKp/++ の交雑においても, 組換により僅かながら H と Kp とが分離する. この場合の組換価も亦0.7%であつた.3. HKp/++ 同志の交配により, HKp/HKp, HKp/++ および正常の個体が分離する. HKp ホモの個体の表現型は HKp ヘテロの個体のそれと異なり, 「い形」斑紋が第4, 5, 6環節に重複して現われる.4. +×HKp/HKp の交雑では HKp ヘテロの個体のみを生ずる.5. HKp/++ の表現型が H/Kp のそれと異なつているのは, 遺伝子の位置効果によるものと見做される.6. いわゆる E 複対立遺伝子群は真の複対立遺伝子群ではなく擬似対立遺伝子群に属するものと考えられる.7. H と Kp とのいずれが第VI染色体の端部に座位するかを見るため, 両遺伝子と Nc との組換価を調べたが, H と Nc との交叉価の算定が困難なため, 目的を達しえなかつた.

Electron-microscopical studies of the inner structure of Paramecium caudatum have been carried out by means of ultra-thin sections. The results of the observations are summarized as follows.1. Each cilium is provided with a basal granule (kinetosome), but exceptionally two cilia grow from one kinetosome.2. The cilium has a fibrillar structure, and consists of a bundle of fibrils extending through its full length.3. The macronucleus is filled with granular or filamentous bodies, with many more minute granules scattered among them. These granules may be found particularly in abundance near the periphery of the nucleus, and show an appearance to be migrating into the cytoplasm through the nuclear membrane.4. The micronucleus is filled with small granules or filamentous bodies, but large granules like those observed in the macronucleus are missing.5. A great number of mitochondria-like granules, spherical, oval or filamentous in appearance, are scattered in the cytoplasm. The ectoplasm immediately beneath the pellicle consists of filamentous bodies forming a fibrous layer.6. The granules have a kind of limiting membrane and some internal structure.7. Staining reactions of the granules in the fixed as well as in the living materials are identical with those of mitochondria in the cells of higher organisms. Furthermore, the granules isolated by ultra-centrifuge show their intimate relation to the respiratory enzymes. From these facts it may be safely said that the granules are of the same nature as the mitochondria of higher organism.8. Two types of food vacuoles are present.

An electron-microscopical study of the fine structure of the nuclei of Paramecium caudatum has been carried out by means of ultra-thin sections.The results of the observations are summarized as follows:1) The macronucleus is surrounded by thin nuclear membrane.2) Throughout the whole macronucleus many globular bodies connected by thin strands of bead-like structures are distributed. They measured about 0.1 to 0.2μ in diameter.3) It is inferred that bead-like structures are related to chromosomes.4) In the micronucleus a stage resembling a prophase of nuclear division could be observed.5) Spherical granules which measure 1μ or more in diameter are scat-tered here and there in the macronucleus, and we suppose these granules are nucleoli. These granules are often fused into two or more large vacuolated masses.Some of the nucleoli in the macronucleus have fine-grained centers and densely osmiophilic perimeters.

The lethal lemon and the lethal albino larvae1) show some phenotypical resemblance. In both, the lem and the al larvae, the mandibular cuticle does not develop properly, so that they cannot chew mulberry leaves and starve to death immediately after the first moulting. The lethal lemon larva contains in its epidermis a large amount of yellowish pigment which gives the body a yellowish color, while the lethal albino larva has a light brown color.It has been confirmed in my previous experiments2), 3), 4) that +, lem and leml form a multi-allelic series. In order to investigate the genetical relation between the al and the leml genes, cross experiments between the two strains and between lemon strain (lem/lem) and albino strain were carried out. From the experimental results it was found that al gene does not locate on chromosome III. However, the linkage group to which al gene belongs has not yet been clarified, although linkage tests of al to several genes of the known other linkage groups were tried.In another experiment5) it has been proved that the lethal lemon and lethal albino are different in their metabolic physiology. The gene leml is mainly responsible for abnormal pterin formation, while the gene al has a weaker capacity to form melanin. These physiological abnormalities have secondarily effects upon other metabolic processes such as abnormal formation of the cuticular layer of the hypodermis and produce somewhat similar expression.