Bombyx mandarina (Lepidoptera: Bombycidae), the presumed ancestor of the domesticated silkworm B. mori, has long been a subject of study to illustrate the geographic relationships in connection with origin of B. mori. We sequenced 100 mitochondrial genomes of B. mandarina collected from South Korea and Japan and these were combined with public data. Phylogenetic and population genetic analyses showed that all individuals collected in South Korea, except one individual from Inje, formed a strong group together with northern China and some individuals of southern China. This group was placed as the sister group to B. mori strains, suggesting that this group could have been served as an immediate progenitor for B. mori. For further robust inference more analysis is underway.

Bombyx mandarina (Lepidoptera: Bombycidae), the presumed ancestor of B. mori, has long been a subject of study to illustrate the geographic relationships in connection with origin of B. mori. We report 97 mitochondrial genome (mitogenome) sequences of B. mandarina collected from Korea and Japan. Phylogenetic and population genetic analyses showed that all individuals of B. mandarina collected in Korean localities formed a strong group together with all individuals originated from northern China (mainly north of the Qinling-Huaihe line) and some of southern China. This group was placed as the sister group to B. mori strians suggesting that this group had been served as an immediate progenitor for B. mori.

To verify the progenitor of B. mori, we sequenced 14 B. mori strains preserved in Korea and one B. mandarina collected in Korea and conducted phylogenetic analysis of Bombycidae using maximum-likelihood method and concatenated sequences of 13 PCGs and 2 rRNA genes. All B. mori strains, regardless of their origin, formed a strong monophyletic group, with the highest nodal support. This B. mori group was placed as the sister to the two B. mandarina collected each from Korea and Shandong, China with the highest nodal support. Finally, the remaining two B. mandarina, which were collected in Japan were independently placed as the most basal lineage of B. mori and B. mandarina group. These results appear to indicate that an immediate ancestor for the domestic silkworm strains may have been originated from China and Korea.

Bombyx mandarina (Lepidoptera: Bombycidae) is generally regarded as the ancestor of the domesticated B. mori. Recently, over 40 mitochondrial genomes (mitogenomes) mainly from B. mori strains preserved in China and wild individuals of B. mandarina were sequenced to verify the progenitor of B. mori. At this point, we also were curious about the origin and the relationships of Korean silkworms to foreign B. mandarina and B. mori. As a first step, we sequenced the complete mitogenome of the B. mandarina collected in Korea and compared it to pre-exsiting data (37 strains of B. mori and 14 individuals of B. mandarina). The complete mitogenome of B. mandarina was 15,694-bp long, consisted of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and one non-coding region. The 494-bp long A+T-rich region possessed the highest A/T content (95.3%) than any other region of the genome. Overall, the general mitogenome characteristics of the genus Bombyx species have an identical gene arrangement, similar A/ T content (average 82.3%) and so on. Phylogenetic analysis, however, showed that B. mori and B. mandarina formed a distant group each with the highest nodal support. For more findings of mitogenome characteristics of Bombyx including the Korean B. mandarina and those preserved in Korea more mitogenomes, particularly from Korea, might be needed.

멧누에나방(Bombyx mandarina) 난각유전자의 형질발현기구를 규명하기 위한 연구의 일환으로 각형성과정에 있어서 난각단백질의 합성과정을 분석하였다. 난각단백질의 합성과정을 여포세포의 기난관배양에 의한 in vitro합성계에 의하여 분석한 결과, 합성과정은 8단계로 나눌 수 있었으며 SDS-PAGE 분석에 의해 17개 이상의 단백질 band로 분리되었다. 멧누에 난각단백질은 합성시기에 따라 3단계로 구분되며 초기에는 비교적 고분자 성분이, 합성의 중후기에는 비교적 저분자성분이 합성되는 등 난각단백질의 합성은 시기특이적으로 조절되었다.

초 록 멧누에는 실내에서의 대량사육이 곤란한 것으로 알려져 왔으나 부화에서부터 100%가까운 다습상태와 전후의 고온사육조건에서 간단히 사육할 수 있었다. 실내사육결과 전령경과일수는 15~25일의 범위이며 대부분의 유충은 17일 전후이었다. 용화비율은 약40%이며 용기간은 암수모두 13~25일 사이였다. 또한 암수모두 2개의 우화최고점을 가지며 수컷이 암컷에 비해 2~3일정도 빨리 우화하였다.

한국산 멧누에(Bomdyx mandarina)chorion 유전자의 형질 발현기구를 규명하기 위한 연구의 일환으로 본 실험을 실시했다. 멧누에의 난각구조를 주사형 전자현마경에 의해 관찰한 결과 매우 특이적인 구조가 인정되었다. 즉 원추상의 불규칙 돌기에 의한 돌기구조층과 이 돌기 구조층을 덮고 있는 한 층의 얇은 덮개 구조층이 그것이다. 2차원 전기영동법에 의해 chorion 단백질을 분석한 결과, 난각을 구성하는 주요 단백질 성분은 등전점 4~6, 분자량 6~30 kd로 밝혀졌다. 특히 특이난각구조와 관련된 특이단백질 성분을 검출하였으며 이들의 대부분은 고cysteine 단백질인 것으로 추정했다. 이상의 연구결과에 의해 멧누에 난각의 특이 구조 형성에 따른 유전자발현기구 규명을 위한 기초자료가 얻어졌다.