• 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.41 no.1
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• pp.20-28
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• 1999

Color qualities investigated on the basis of Munsell code and Korean standard color code for the cocoons from various strain of mulberry silkworm, Bombyx mori. 16 of different color qualities were identified from 21 of original silworm strains, and determinated international name with the revision of Korean color name for cocoon. The various cocoon color confirmed on the sphere from 567 to 593 nm wavelength, 78% of those located at the region about 580 nm (575~584) of sensitive "color difference limen". Y gene engaged broad ranges of wavelength (575~593 nm) in the color expression, by contrast with other genes of Pk (593 nm), F (584~593), Grc and relative G group (567~570 nm), on the transmission of carotenoid or flavonoid color substance. YC gene expression by original silk worm strain was also distinguished by those variation of specific yellow than other colors from Grc, GaGb, Gc, and YPkF. Appearance of chrome yellow cocoon was dominant than other yellow in the cross among vivid yellow group. F1 of pin${\times}$green produced the cocoon of yellow such as "additive mixture" as color light, however, most of the hybrid between yellow cocoon showed the color similar to "subtractive mixture" as a mixture of dyestuff. Hybrid cocoons among yellow or green colors were decreased their hue, value, and chroma, than those of parent. Diallel cross among the strain of various green cocoon suggest the existence of Grc, Ga, Gb, Gc genes. Cream colored cocoon of B. mandarina was differed from other yellow cocoon of Bobyx mori B. mori. Y$^A$ with Ymc showed the similar role of Y with C, therefore, segregated yellow cocoon from the B. mori${\times}$B. mandarina (+$^YC/Y^AYmc$). YC expression of $Y^AY$mc genes might be suppressed by deficiency of outer layer sericin on the middle division of silk giand in the B. mandarina.

• International Journal of Industrial Entomology and Biomaterials
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• v.24 no.1
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• pp.1-5
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• 2012

A newly developed silkworm variety, GoldenSilk makes bright yellow cocoon. In this article, the basic characteristics of GoldenSilk cocoon were examined through color analysis, degumming characteristics and UV spectrophotometer. The colorant of GoldenSilk cocoon was not distributed evenly throughout the cocoon layer but existed in the outer layer of the cocoon. The colorant has not good resistance against sunlight. The degumming loss percentage of GoldenSilk cocoon was 29.2%, which is relatively higher than that of the authorized one. UV spectrophotometer showed specific absorption band around 400 to 500 nm, which is the specific yellow colorant of the GoldenSilk cocoon extracted to the degumming solution during the degumming process.

• 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.

• International Journal of Industrial Entomology and Biomaterials
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• v.32 no.2
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• pp.54-59
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• 2016

All of silkworm varieties reared in farmhouses are first generation hybrids, for the production of these hybrid silkworms precise and labor-saving sex discrimination is necessary. The new variety "Hanbyeolnue" is biparental sex-limited larval marking yellow cocoon variety which was bred from biparental sex-limited strain of Japanese originated Jam 319 and Chinese originated Jam 320. Productivity test of Hanbyeolnue in 2015 showed high healthiness and short larval period. The Hanbyeolnue was evaluated as an excellent variety which can be utilized for special purpose silkworm such as male pupae or Cordyceps production.

• International Journal of Industrial Entomology and Biomaterials
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• v.38 no.2
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• pp.51-55
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• 2019

The structure and properties of silk polymers (fibroin and sericin) can be satisfactorily controlled by choosing a suitable silkworm variety and, hence, this parameter (i.e., silkworm variety) has attracted increasing attention. A previous study reported that the crystallinity of white colored silkworm cocoons depends on the silkworm variety. In the present study, sixteen yellow colored silkworm variety cocoons were produced and their molecular conformation and crystallinity were investigated. The conformation of the silkworm cocoons varied with the silkworm variety. Most cocoons exhibited ${\beta}$-sheet conformation, although random coil and ${\beta}$-sheet conformations co-existed in some cocoons (e.g., 21 and D90). The crystallinity of the silkworm cocoons varied with the silkworm variety and the measurement position of the cocoon (i.e., outer surface or inner surface). However, the difference in the crystallinity indices of the outer and inner surfaces comprising the cocoons varied with the silkworm variety, but was <2% for all cocoons, except for MAL.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.89-93
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• 2004

A new silkworm variety, Kumhwangjam, with a sex-limited cocoon color for spring rearing season is F$_1$ hybrid between Jam 309, a Japanese race bred from Y1/9153, and Jam 310, a Chinese race from Y1/8586. In the local adaptability test performed at 8 local areas in spring rearing season of 2003, major characteristics of Kumhwangjam were mainly similar to those of the check variety Kumokjam. The new silkworm variety, Kumhwangjam, showed a sex-limited cocoon color: yellow for female and white for male with elliptical cocoon shape. This sex-limited cocoon color can be used as a valuable marker for discrimination between female and male for various purposes.

• Journal of Sericultural and Entomological Science
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• v.39 no.2
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• pp.169-173
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• 1997

The behavior of tyrosine(Tyr.) residue of Bombyx mori silk fiber from yellow fluorescent cocoon has been examined for the dependence of pH in aqueous silk solution under the presence of orange II salt. Through the peak separation of angular dependence of spectral pattern of 15N-Tyr. and [1-13C]-Tyr. between the fiber axis and the molecular bond direction, N-H bond in fiber as well as the orientation distribution around the fiber axis were analyzed. Also, and sericin component was obtained from these angular dependence of oriented spectral pattern. The pH dependence of the 13C NMR chemical shift of B. mori silk fibroin was examined in aqueous solution in the presince of orange II are broad at pH$\geq$7.0. However, these become sharper at pH$\geq$8.0 and remain sharp at higher pH. In these higher pH range, a chemical shift change occurs due to the deprotonation of the Tyr. side group of fibroin. At higher pH. such a hydrophobic cluster is destroyed because of the electrostatic interaction according to the deprotonation of the Tyr-OH group.

• Journal of Sericultural and Entomological Science
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• v.42 no.1
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• pp.10-13
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• 2000

The objective of this research was to characterize of the silkworm that might be recognized to the Korean native strains. The eleven strains of Korean race used in this study, which is cultured in Korea and Japan seri-cultural research organs. Most of Korean varieties were three molting and univoltine, comparatively longer larval duration than the trimolter general. The egg characters of varieties showed short-eliptic shape and dark brown egg color except for a few varieties which shows greenish dark brown. Also, most of varieties were showed the plain(p) and moricaud( $p_{M}$) in larval markings. Moric marking of the varieties also consist of innumerable dark grayish brown lines and dots, though somewhat darker and lighter than that of the wild silkworm, Bombyx mandarina. Cocoon characters variations of varieties were seen in the size, color and shape. 8 varieties were colored cocoon, i.e., yellow, greenish yellow and light green etc., the others were white cocon. The shape of cocons were consisted of constricted shallowly in the middle and attenuated at one or both ends of cocoon, i.e., spindle. The results of this study is sufficient evidence that Korean strains were shown as the one of regional origin strain of domesticated silkworm such as the Chinese and Japanese etc.c.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.101-103
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• 2001

The wild silkmoth, Samia cynthia pryeri, was firstly collected at Miryang, Korea. The development and quantitative characters of S. cynthia preyri in the laboratory condition were analysed. The larval body color of dark yellow green or light yellow green of the S. cynthia pryeri was changed into white color during the molting period, and the yellowish bristles in younger larvae were changed into fade green color in advanced stage larvae. Aralia elata and Zanthoxylum piperitum were newly identified as host plants to S. cynthia pryeri. Cocoon weight and cocoon shell percentage were average 2.14 g and 12.3 %, respectively. In addition, the morphology of the silkgland was different from that of the domestic silkworm,Bombyx mori, but was identical with that of the wild silkmoth, Antheraea yamamai.