We developed high-yield degumming methods for preparing sericin from the cocoons of the mulberry silkworm Bombyx mori and the non-mulberry silkworms of Antheraea yamamai, and Cricula trifenestrata. We achieved sericin yields of 54%-55% from B. mori cocoons extracted in 0.24% NaOH, from A. yamamai cocoons extracted in 0.025% NaOH + 0.475% Na2CO3, and from C. trifenestrata cocoons extracted in 0.5% Na2CO3. In all three extracts, analysis of amino acid compositions indicated a high degree of sericin purity and Tricine–SDS-PAGE analysis indicated degradation to heterogeneous polypeptides. Thus, sericin prepara-tions produced from the cocoons of silkworms by high-yield degumming methods offer promise for biomedical and industrial ap-plications.
Silkworms, Bombyx mori larvae, detect phytochemicals in host and nonhost plant leaves via gustatory receptor neurons (GRNs) expressing gustatory receptors (BmGrs). Expression of BmGrs facilitates detection of phytochemicals by GRNs, which is the basis of the molecular mechanism of host selection in silkworms. However, it is unclear which BmGr(s) are expressed in a single GRN. Here, we established a method to isolate a bundle of GRNs in a gustatory sensillum and a single GRN using micromanipulation and laser-capture microdissection to investigate the gustatory receptor expression pattern in a bundle of GRNs and a single GRN in an epipharyngeal sensillum. Our results suggested that several putative sugar- and deterrent BmGrs are expressed in a myo-inositol neuron and a deterrent neuron, respectively, in the epipharyngeal sensillum; these findings provide the basis for future studies of the involvement of BmGrs and GRNs in the mechanism of oligophagy. Moreover, we present evidence that BmGr10, which has been reported to be a myo-inositol receptor, expresses and functions in an epipharyngeal myo-inositol neu-ron.