Hiroshi Doira

Gene-controlled incorporation of haemolymph protein into the ovaries of Bombyx mori

Abstract The haemolymph protein concentration in Bombyx mori decreases normally by about one-fourth during pharate adult development. In females homozygous for the small egg gene, the concentration of haemolymph protein remained constant throughout the pupal and pharate adult stages. The sm gene does not influence the synthesis of vitellogenic female protein of pupal and pharate adult haemolymph (FP). Normal ovaries transferred to the haemocoele of sm females undergo normal vitellogenesis. In the absence of normal alleles of sm , the ovaries encounter difficulties in the incorporation of FP into their oocytes from pharate adult haemolymph. These results suggest that an active translocation mechanism is involved in the transfer of haemolymph protein into the ovaries.

Synthesis and resorption of a humoral chymotrypsin inhibitor, CI-8, by fat body of the silkworm, Bombyx mori

The Bombyx mori hemolymph contains up to 16 chymotrypsin inhibitors (CIs). The present in vitro culture of tissues in Graces medium indicated that CI-8, which belongs to the largest molecular-size group of CIs with sugar moiety, is synthesized in the fat body and secreted from it during the feeding period. When the fat body from other strain which synthesizes an allelic component (CI-7) instead of CI-8 was incubated in vitro in hemolymph from the strain which has CI-8, the fat body was found to receive CI-8. Thus it was concluded that CI-8, once secreted into the hemolymph, was again sequestered into the fat body after the onset of spinning. Protein granules isolated from the pupal fat body were shown to contain CI-8, indicating that the sequestered CI-8 is present in the protein granules.

Polygonal patterns on eggshells of giant egg mutant and large eggs induced by 20-hydroxyecdysone in Bombyx mori

Abstract The polygonal network patterns, i.e. the secretory surface imprints produced by the follicular epithelial cells, on the lateral side region of eggshell in Bombyx mori were observed by scanning electron microscopy and differential interference contrast microscopy in order to characterize the giant egg ( Ge ) mutant and large eggs induced by the injection of 20-hydroxyecdysone into pupae. The area of each polygon was smaller in Ge but larger in the induced large eggs than in the normal eggs. The polygon number per unit area was much higher in Ge than in the normal eggs, but the induced large eggs exhibited the same number as the normal eggs. These results indicate that Ge is a mutant in which the number of the follicular epithelial cells is increased, whereas injected 20-hydroxyecdysone promoted hypertrophy of the follicle cells during choriogenesis.

Yolk of a “scanty vitellin” mutant, vit, of Bombyx mori is lacking in vitellin and 30 kDa proteins

A novel mutant named “scanty vitellin” (vit) of Bombyx mori, induced by N-methyl-N-nitrosourea, was analyzed for yolk proteins by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The ovary of vit/vit pupae was lacking in vitellin and the 30 kDa proteins that are yolk constituents synthesized outside the ovary. However, the vit/vit ovary had a normal amount of the egg-specific protein, a yolk component synthesized by the ovarian follicular epithelial cells. On the other hand, vitellogenin and the 30 kDa proteins, which are the precursors of yolk proteins, were abundant in the haemolymph of vit/vit female pupae. These results indicate that the mutant gene interferes with the uptake of the extraovarian yolk precursors into the oocyte.

Characteristic profiles of haemolymph proteins during larval development of molting mutants of the silkworm, Bombyx mori

Abstract 1. 1. Electrophoresis of the haemolymph from developing larvae of Bombyx mori revealed that the banding patterns of proteins could be grouped into three characteristic types. 2. 2. The young larval type exhibited at the first to the third instars (which are the phase of nutritional growth). 3. 3. The late larval type specific to the fifth instar (which is the phase of reproductive growth). 4. 4. The intermediary type shown at the fourth instar (which is the stage of switchover between the above two phases). 5. 5. The tetramolter mutant M 3 lacked the intermediary type (i.e. the feature of the fourth instar) during its development, whereas the different tetramolter mutant rt had a mixture of the late and the intermediate types at its fourth (last) instar. 6. 6. On the other hand, the mutant M 5 , which is a pentamolter, repeated the intermediary type at its fourth and fifth (penultimate) instars.

Manifestation of characters in the "Giant egg" mutant of Bombyx mori (Lepidoptera: Bombycidae). 1. Characteristics of the Ge egg.

カイコ大卵突然変異(Ge)の卵に関する性状ならびに卵形成過程における蛹体重と卵巣の発育状況,卵巣(卵)タンパク質含量の経時的変化について正常との比較分析を行った。1) Ge卵は正常に比べ卵形(卵殻の長径と短径),卵重,卵黄タンパク質含量のいずれも大であるが,卵黄タンパク質成分組成には差異は認められなかった。Ge雌成虫の造卵数は少なかった。2) Geにおける卵巣生重,卵巣(卵)タンパク質含量ならびに蛹体重に対する卵巣生重割合の経時的変化はいずれも正常のそれと同じであった。3) Geにおける卵形の大形化と卵内容物の増加は卵形成のための素材料が一定であるという制約下にあって,必然的に造卵数の減少をもたらすと考えられた。すなわち,個々の卵構成物質量と卵数とを調節する機構が強く作動しているものと判断された。

INSTABILITY OF MESSENGER AND RIBOSOMAL RNA IN A GLUE-PROTEIN MUTANT OF Bombyx mori

The mucous glands of Bombyx pupae secrete glue proteins which attach deposited eggs to the mounting sheet. A mutant of a dominant gene, named no glue (Ng), produces nonadhesive eggs which have a low capacity for glue‐protein synthesis. In the present study it was shown that the mucous glands of Ng silkworms showed rapid degradation of mRNA as well as rRNA during development; this may cause the low capacity for glue‐protein synthesis in the mutant organ. In contrast, the mucous glands of normal silkworms showed a significant increase in content of RNAs until the maximum rate of glue‐protein synthesis was achieved. The degradation of RNA in the Ng mucous gland was inhibited by actinomycin D injected into the body fluid. Thus it is supposed that the Ng gene codes for a presumptive controller RNA, which would be the mediator of RNA instability in the mucous glands of Ng pupae.

Haemolymph protein profiles in allatectomy-induced trimolters resemble those of a recessive trimolting mutant of the silkworm, Bombyx mori

Abstract Two types of artificial trimolters named A and B were induced by excising the corpora allata from the normal tetramolter of Bombyx mori at the periods before and after, respectively, the third molt. By using polyacrylamide gel electrophoresis, these trimolters were analysed for the banding patterns of haemolymph proteins at their final (fourth) instar. A feature resembling that of the last (fifth) instar of the normal tetramolter, i.e. with an increasing difference in content of the female-specific protein (FL), was found to occur. However, this was preceded by a feature of the penultimate instar of the normal tetramolter, i.e. with a low content of haemolymph proteins without sexual differences. The trimolter-B exhibited less distinct differences in FL content than the trimolter-A. These patterns of haemolymph proteins in the allatectomy-induced trimolters were similar to those of the recessive trimolter mutant rt.