• International Journal of Industrial Entomology and Biomaterials
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• v.40 no.1
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• pp.6-15
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• 2020

Silk has attracted the attention of numerous research groups because of its unique properties as a biomedical material. Recently, studies on the biomedical application of silk cocoon, such as membranes for guided bone regeneration, have been conducted. As a preliminary study on silkworm cocoons, the morphological structure and crystallinity of cocoon of nine silkworm varieties with different sides are examined in this study. The morphological structure of the silkworm cocoon is shown to be dependent on silkworm variety and the cocoon layer (i.e. outside or inside). It is also shown that the silk filaments of the out layer are more bent and twisted compared to those of the inner layer. Furthermore, the crystallinity of the outer surface of all silkworm cocoons is found to be higher than that of the inner surface, regardless of the silkworm variety. Lastly, it is shown that the crystallinity index of the cocoon depends on the silkworm variety, implying that the structure of the cocoon varies with silkworm variety.

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.22-29
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• 1997

Ultraviolet weavelength (UV) of 366 nm produced clearer fluorescent dolor than that of 254 nm for the inspection of silkworm cocoons. Fluorescent color of silkworm cocoons varied in color, appears no relationship with the natural color under the normal light. Uniformity of fluorescent color was improved by selection of blue or yellow line from wild types. Blue and yellow, located at the opposite poles on the color solid and L*a*b* color system, confirmed as pure standard of fluorescent color in the silkworm races for commercial white cocoons. the cocoons with blue fluorescence occupied as high as 1.7 to 8.6 times than those with yellow in the Japanese silkworm races. Fluorescence of silkworm cocoon was not affected by forced flow dry at 70$^{\circ}C$ for 6 hrs. While the Japanese races revealed no sexual difference in fluorescent color, sex-dependence of the color was common in the Chinese races for commercial white cocoon. The fluorescence of cocoon shell of Chinese races showed clear separation of blue of median color. Silkworm strain of Dc20 and Fc24 were sexualy segregated 98.8${\pm}$1.20%, 99.0${\pm}$1.00% by cocoon fluorescence, as that of 99.3${\pm}$0.44% by typical larval marking of sex-limited inheritance. Specific expression of cocoon fluorescence, applicable to breeding of simple discrimination of sex for Chinese races, inspected thoroughly on the surface and inner layer of cocoon shell.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.57-61
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• 1965

In the silkworm fed on ginseng, the body weight and the cocoon weight were not only heavier, but also the ratio of a cocoon layer to a cocoon weight was higher than those in the control. Especially, the heavier pupae were appeared. The ginseng may be therefor available in silkworm improvement.

• Journal of Sericultural and Entomological Science
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• v.28 no.2
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• pp.28-34
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• 1986

The general combining ability (GCV), the specific combining ability (SCA) and the reciprocal combining ability (RCA) effects wereobtained by 8$\times$8 diallel crosses of the silkworms with four Japanese races and four Chinese races, total eight lines. The result are as follows ; 1. The general combining ability (GVA) effects appeared high significant level in the total and the fifth instar periods (TP, FP), a female and a male cocoon weights (FW, MW), a female and a male cocoon layer weights (FL, ML) and a female and a male cocoon layer ratios (FR, MR). Only the reciprocal combining ability (RCA) effects appeared high significant level in the total and the fifth instar periods (TP, FP). 2. The Japanese original silkworm lines varied in the general combining ability effects from -0.864 to 0.578, and the Chinese original silkworm lines did in ones from -0.570 to 1.018. 3. The specific combining ability effects of the silkworm lines made in order of the crossing types of JL (Japanese lines) $\times$CL (Chinese lines)>CL$\times$JL>JL$\times$JL> CL$\times$CL in a total cocoon weights and a cocoon layer weights. 4. The reciprocal combining ability effects of the silkworm lines was in order of the crossing types of JL$\times$CL>JL$\times$JL> CL$\times$CL>CL$\times$JL in a total cocoon weights and cocoon layer weights.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.96-102
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• 2016

Recently silk polymer produced by Bombyx mori silkworm has been considered as biological macromolecules. Silk polymer was extracted in PBS solution at $37^{\circ}C$ for 72 h or $72^{\circ}C$ for 24 h. The effect of EtOH treatment on the cocoon extraction was also examined. The extraction yield of cocoon was less than 1 wt% regardless of extraction conditions. UV spectroscopy showed that the experimental extracts have absorption bands at 280 nm. There is no cytotoxicity effect on the mouse fibroblast L929 cell. The phenotype of L929 cell was not changed under the experimental conditions. The proliferation behavior of L929 cell was not affected by the addition of cocoon extract. Therefore, cocoon extract might be cytocompatible and can be used as promising biomaterials.

• Journal of Sericultural and Entomological Science
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• v.31 no.1
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• pp.25-36
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• 1989

In this experiment, gene action were analyzed for seven silkworm varieties in order to obtain basic information on their genetic improvement by diallel crosses. The results obtained were summarized as follows : In F1 generation, over-dominance was shown by Vr-Wr graphic analysis in four characters such as cocoon length in female, bave weight, cocoon weight and boiling off ratio in both male and female, and partial dominance in four characters such as fifth instar period, cocoon layer weight, cocoon layer ratio and bave length. In F2 generation, the partial dominance in all characters were obtained. Components of genetic variance analyzed for five characters such as fifth instar period, cocoon width, cocoon layer weight, cocoon layer ratio and fibroin contents in F1 generation, and for four characters such as cocoon width, cocoon layer weight, cocoon layer ratio and frbroin contents in F2 generation showed that addition effects were higher than dominant effects.

• Journal of Sericultural and Entomological Science
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• v.10
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• pp.67-72
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• 1969

In order to analyse the correlation between the parents and their hybrids in the silkworm, which were reared in spring, the author has surveyed the various quantitative characters which are significant in genetics, and the hybrid vigor rate. The duration of larvae life is shorter in F1 Value an in the mid parents value, cocoon size biffer, pupa rate, cocoon crop from ten thousand silkworms just molted in the fourth instar, total cocoon weight and cocoon layer weight increases in comparison with the mid parents value. Although cocoon layer ratio only shows increasing by 0.3％ or so, it is too little to admit the effect. F1 value is nearly equal to parent value and there is no correlation between F1 hybrids value and their mid parents value.

• International Journal of Industrial Entomology and Biomaterials
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• v.35 no.2
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• pp.71-76
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• 2017

The cocoon's color of silkworm, Bombyx mori L. is usually white. But some are yellow, flesh and green colors because of modified characteristics. The yellow and flesh cocoons depend on carotenoid pigments, green cocoons are determined by flavonoid pigments. The cocoon's color is affected by the genes controlling penetration process from midgut to coelom and silk gland. Y (Yellow blood, 2-25.6) and I (Yellow-inhibitor, 9-16.2) genes are involved in the penetration process of carotenoid pigments from midgut to coelom, C (Outer-layer yellow cocoon, 12-7.2) and F (Flesh, 6-13.6) genes from coelom to silk gland. Therefore, the carotenoid cocoon's color depends on the genotype Y, I, C and F genes and their combination. Among them, C gene is sympathetic gene, which are known as C, CI and CD. C (Outer-layer yellow cocoon) genes make yellow cocoons on outer-layer and white cocoons on inter-layer, and CI (Inner-layer yellow cocoon) genes do yellow cocoons on inter-layer and dilute yellow cocoons on outer-layer. CD gene is known as making dilute yellow cocoons all layer. In this study, we have checked the dominance relation of C sympathetic genes among carotenoid genes for color cocoons by using strains related to the genes for color cocoons and investigated the aspect that pigments were penetrated in silk gland by action of each gene.

• Journal of Sericultural and Entomological Science
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• v.28 no.1
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• pp.24-29
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• 1986

A set of 21 crosses of F1 generation by diallel crosses from seven parent silkworm, Bombyx mori L. were used as materials to estimate genetic parameters such as gene action and combining ability. Experiments were conducted in 1985, and three characters, which are weight of cocoon, weight of cocoon layer and ration of cocoon layer, were observed. The data were analyzed for each character by Jinks', Hayman's and Griffing's methods. The result obtained are summarized as follows : 1. In Vr-Wr graphical analyses, weight of cocoon was found to be inherited in over dominance, and weight of cocoon layer and ration of cocoon layer were observed as partial dominance. 2. Estimate of additive component of variance(D) was greater than those of dominance component of variance(H) for weight of cocoon layer and ratio of cocoon layer, and positive values of F were observed for all characters. 3. Mean squares of general combining ability were higher than those of specific combining ability. 4. Variety Jam 107 was expressed as the highest GCA effects for three characters, and high SCA effects for all characters were observed in combinations of 113 $\times$Jung 14 and Jam 107 $\times$Jung 14.

• Journal of Sericultural and Entomological Science
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• v.14 no.2
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• pp.113-123
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• 1972

The authors studied on the effect of silkworm eggs collected from the whole silkworm egg producers in Korea to know the cocoon crops, and the results are as follows. There was no remarkable correlation on the effect of silkworm eggs quality for the cocoon crops but can be concluded as follows. 1) There was a weak correlation between the hatching ratio and economical hatching ratio but no correlation between economical hatching ratio and cocoon crops. In other word, hatching ratio couldn't be influenced for the silkworm health. 5) Non-hybrid ratio (miss-crossing ratio) influenced to the amount of reelable cocoons and pupation ratio but on this experiment, there was a little influence for the cocoon crops. The authors found that there is no difference between origin and its F$_1$crops under the more suitable conditions. Non-hybrid ratio can be determined the silkworm eggs quality, but notice that the ratio decrease only when used pure origin. 3) There is some correlation between harvesting amounts of reelable cocoon and pupation ratio. In general, the eggs which harvest small amounts of reelable cocoon are lower on the pupation ratio. 4) The influence of cocoon layer ratio is based on the variety absolutely but cocoon crops also has a little influence on the cocoon layer ratio.