Mature silkworm of Bombyx mori is known to contain various functional materials. However, it is too hard to chew or digest for humans when it is cooked or lyophilized. In Korea, the Rural Development Administration recently developed and patented a method for making mature silkworms edible. In this study, therefore, we examined the effects of a larval powder of steamed mature silkworm (SMSP) on skin pigmentation and melanogenesis. For elucidating the depigmenting activity, lightness of a designated site on the murine dorsal skin was measured in vivo. During the experiment, hyperpigmentation was induced on the skin by cumulative exposure to ultraviolet B (UVB) irradiation. At the end of the experiment, melanin production on the skin was visualized by Fontana-Masson staining. Orally administered SMSP of pistachio cocoon strain for at least a month or longer significantly and reduced abnormal pigmentation caused by UVB on the murine dorsal skin. SMSP also showed a potential anti-melanogenic efficacy in modulating UVB-induced hyperpigmentation. Taken together, SMSP was identified as a potential candidate for a novel anti-melanogenic agent, which showed depigmenting efficacy against UVB-induced hyperpigmentation in vivo when administered orally.

The mature silkworms of Bombyx mori L. have recently been regarded as a potential health supplement due to gainingtheir edibility for humans by a newly-developed steaming method. Therefore, this study was conducted to investigate theeffects of steamed and lyophilized mature silkworm powder (SMSP) on skin pigmentation and melanogenesis. Orally administeredSMSP significantly and dose-dependently reduced abnormal pigmentation caused by ultraviolet B (UVB) on the murinedorsal skin. SMSP also showed a potential anti-melanogenic efficacy in modulating UVB-induced melanogenesis. Takentogether, SMSP was identified as a potential candidate for a novel anti-melanogenic agent, which showed hypo-pigmentingefficacy against UVB-induced melanogenesis in vivo when administered orally.

Serine proteases and serine protease homologs are involved in the prophenoloxidase (proPO)-activating system leadingto melanization.The Bombyx mori serine protease homolog BmSPH-1 regulates nodule melanization. Here, we show the dualrole of BmSPH-1 in the development and immunity of B. mori. BmSPH-1 was expressed in hemocytes after molting andduring the larval-pupal transformation in normal development. In contrast, following infection, BmSPH-1 was expressed inhemocytes and activated in the hemolymph, which resulted in the induction of PO activity. Moreover, BmSPH-1 was activatedin the cuticle during the larval-pupal transformation and early pupal stages. In BmSPH-1 RNAi-treated silkworms, the reducedBmSPH-1 mRNA levels during the spinning stage or the prepupal stage resulted in the arrest of pupation or pupal cuticularmelanization, respectively. The binding assays revealed that BmSPH-1 interacts with B. mori immulectin, proPO, andproPO-activating enzyme. Our findings demonstrate that BmSPH-1 is responsible for the larval-pupal transformation, pupalcuticular melanization and innate immunity of silkworms, illustrating the dual role of BmSPH-1 in development and immunity.

In insects, serine proteases are involved in a variety of physiological processes including digestion, development, and immunity. Bombyx mori serine protease homolog BmSPH-1 regulates nodule melanization and is recruited into nodules from the hemolymph by B. mori lipopolysaccharide-binding protein. Here, we show the dual role of BmSPH-1 in development and immunity of B. mori. BmSPH-1 was expressed in the hemocytes during larval-pupal transformation and localized to the cuticle of silkworms, which indicates that BmSPH-1 is secreted from hemocytes and then transported to the cuticle via the hemolymph. BmSPH-1 was proteolytically activated in the cuticle during larval-pupal transformation and the early pupal stage. BmSPH-1 RNAi resulted in the arrest of larval-pupal transformation and pupal cuticular melanization. Furthermore, the expression of BmSPH-1 was up-regulated in the hemocytes during infection. Taken together, we found that BmSPH-1 is involved in larval-pupal transformation and pupal cuticular melanization as well as the innate immunity of silkworms, which indicates that BmSPH-1 is responsible for either development or immunity.

Hepatocellular carcinoma (HCC) is a representative inflammation-associated cancer and known to be the most frequent tumor. However, the preventive agents for hepatocarcinogenesis are unsatisfactorily identified. We investigated the protective effect of steamed and freeze-dried mature silkworm larval powder (SMSP) on diethylnitrosamine (DEN)-induced hepatotoxicity in mice and compared the effect of three silkworm varieties: white-jade, golden-silk, and light-green strains. The mice were fed with diet containing 0.1, 1, and 10 g/kg of three types of SMSP for two weeks while DEN (100 mg/kg, i.p.) was injected 18 h before the end of this experiment. Liver toxicity was determined as serum indicator, histopathological examination, and expression of inflammatory enzyme. Pretreatment with SMSP reduced necrotic and histopathological changes induced by DEN in the liver. The measurement of serum biochemical indicators showed that pretreatment with SMSP also decreased DEN-induced hepatotoxicity, the levels of alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). In addition, SMSP inhibited the expressions of inflammatory enzymes, cyclooxygenase-2 and inducible nitric oxide synthase. White-jade SMSP showed the most effective hepatoprotective results against hepatotoxicity among the three silkworm strains used in this study. SMSP may have a protective effect against acute liver injury by inhibiting necrosis and inflammatory response in DEN-treated mice.

식용곤충은 대체 식량자원으로 관심이 증가되고 있다. 본 연구의 목적은 누에나방 번데기 분말 섭취 유무에 따른 저항성운동 훈련(등장성 수축)이 ICR 마우스의 근육량 증가에 미치는 영향을 분석하였다. 이를 위하여 ICR 마우스 28마리를 대조군(CON), 저항성운동 훈련군(EX), 누에나방 번데기 분말 섭취군(SP), 누에나방 번데기분말 섭취 저항성운동 훈련군(SPEX)으로 그룹 당 각각 7마리씩 분류하였다. 체중증가율은 EX와 SPEX가 CON과 SP에 비해 유의하게 억제되었다. 혈중 총 단백질 농도는 SPEX가 다른 그룹에 비하여 가장 높았다. 알부민 농도 변화는 운동훈련 병행 시에만 증가하였다. 혈액 GOT와 GPT 수준은 유의차가 없었다. Akt와 Gsk-3β의 단백질 발현의 유의차는 없었다. 그러나 번데 기 분말 섭취 시 Akt 증가 및 Gsk-3β의 감소 경향이 나타났다. 비복근 근육 양은 저항성 운동 훈련을 하였을 때만 증가하였다. 그리고 또한, 번데 기 분말 섭취 시 근육량은 유의차가 없었으나 증가하는 경향을 보였다. 이러한 결과는 저항성 운동훈련과 누에나방 번데기 분말 섭취는 간독성을 유발하지 않고 근육량을 증가시킬 수 있다는 점을 시사한다. 그러나 보다 상세한 결과를 제시하기 위해 부가적인 연구가 필요할 것이다.

Insect cuticular melanization is regulated by the prophenoloxidase (proPO)-activating system, which is a component of innate immunity. However, the differentiation between cuticular melanization and innate immunity is not well defined. Here, we demonstrate that the proPO-activating system regulates cuticular melanization in the silkworm pupae using a different mechanism. Our results indicate that the differential and spatial regulation of key components, such as the proPO-activating factor, tyrosine hydroxylase, proPOs, and immulectin, primes the proPO-activating system for either cuticular melanization or innate immunity. This dual strategy for cuticular melanization in development and innate immunity upon infection demonstrates a two-pronged defense mechanism mediated by the priming of the proPO system.

Insect cuticular melanization is regulated by the prophenoloxidase (proPO)- activating system, which is also involved in the innate immune reaction. Here, we demonstrate how the differentiation of the proPO-activating system is regulated toward a cuticular melanization or innate immunity function in silkworm (Bombyx mori) pupae. Our results indicate that the differential and spatial regulation of key components, such as the proPO-activating factor, tyrosine hydroxylase, and porPOs, primes the proPO-activating system for either cuticular melanization or innate immunity. This dual strategy for cuticular melanization in development and innate immunity upon infection demonstrates a two-pronged defense mechanism that is mediated by the priming of the proPO system.

It is true that the proper environmental risk assessments for many GM insects almost have not been executed in Korean research situation. Therefore, we tested the environmental risk assessment of GM silkworms if there is any difference between GM and non-GM silkworms by three. First, we measured their mobility in the breeding environment conditions with food and without food. Secondly, we measured their viability at the Korean artificial extreme environmental conditions (temperature, humidity, food) after escaping from their breeding environments. We observed the egg productivity and the hatchability between non-GM silkworm and transgenic silkworms with four different pair experiments. The mobility of non-GM silkworms and GM silkworms statistically did not differ and the egg production and hatchability was not also different. The hatchability by couple of GM female silkworm and non-GM male silkworm was lower than by non-GM male and female couple. We observed their viability (High Temp., wet and with food: p=0.0434; High Temp., wet and without food p=0.0430; High Temp., dry and with food: p=0.0005; High Temp., dry, without food: p=0.0479) between the GM silkworm and non-GM silkworm, and there was statistically different. Relatively, the viability of GM silkworm was lower than non-GM silkworms. We could not exactly test for viability of silkworm in low temperature conditions because of their hibernating. Although there was any difference in viability and hatchability between GM silkworm and non-GM silkworm, the all ability of GM silkworm was lower than non-GM silkworm. Conclusively, risk of GM silkworm was lower than non-GM silkworm.