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Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 149-163).

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In our study, we examined the polymorphism of gene Ser2 from domesticated silkmoth Bombyx mori and its closest wild relative B. mandarina. As a starting material for our work, we used the restriction map of allele C isolated from hybrid lineages 200 and 300 of European silkmoth B. mori (Michaille et al. 1990a). We also used the published sequence of allele D which was isolated from {\clq}qDaizo`` p50 strain of B. mori (Kludkiewicz et al 2009). Based on the published sequence, we designed PCR primers and performed sequence analysis of 4 different alleles of gene Ser2, including the almost complete genomic sequence of allele C (except for two short regions containing repetitive DNA). We then compared the sequences and found that the alleles differ significantly not only in intron lengths and the sizes of exon 9, but also in exon arrangements. While the allele C contains 12 exons (1, 2, 3, 4, 5, 6, 7, 8a, 9, 10, 11, 8b), the alelle D and other alleles analysed have 13 exons (1, 2, 3, 4, 5, 6, 7, 8, 9a, 10a, 9b, 10b, 11). Allele C showed very unique arrangement of exons, which suggested that it may represent an ancestral form of Ser2 gene. We analysed the arrangment of exons located at the 3´end of the Ser2 gene by PCR and electrophoresis in 70 available strains of B. mori and B. mandarina. We also tried to find a similar allele to the allele C and we amplified and sequenced 2 kb region from 55 Bombyx strains. Phyllogenetic analysis of gene Ser2 gene suggested that the C allele of now probably extinct European silkmoth hybrids 200 and 300 does not seem to be an ancestral form of Ser2 gene, but it rather seems to be the result of complex secondary rearrangements.

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No / Runt-related (RUNX) transcription factors are evolutionarily conserved either in vertebrate or invertebrate. Lozenge (Lz), a members of RUNX family as well as homologue of AML-1, functions as an important transcription factor regulating the hemocytes differentiation. In this paper, we identified and characterized RUNX family especially Lz in silkworm, which is a lepidopteran model insect. The gene expression analysis illustrated that BmLz was highly expressed in hemocytes throughout the whole development period, and reached a peak in glutonous stage. Over-expression of BmLz in silkworm accelerated the melanization process of hemolymph, and led to instantaneously up-regulation of prophenoloxidases (PPOs), which were key enzymes in the melanization process. Further down-regulation of BmLz expression by RNA interference resulted in the significant delay of melanization reaction of hemolymph. These findings suggested that BmLz regulated the melanization process of hemolymph by inducing PPOs expression, and played a critical role in innate immunity defense in silkworm.

Yes / As an important economic insect, Bombyx mori is also a useful model organism for lepidopteran insect. Integrins are evolutionarily conserved fromsponges to humans, and play vital roles inmany physiological and pathological processes. To explore their diverse functions of integrins in insect, eleven integrins including sixα and five β subunitswere cloned and characterized fromsilkworm. Our results showed that integrins fromsilkwormown more family members compared to other invertebrates. Among those α subunits, integrins α1, α2, and the other four subunits belong to PS1, PS2, and PS3 groups, respectively. The β subunits mainly gather in the insect βν group except the β1 subunit which belongs to the insect β group. Expression profiles demonstrated that the integrins exhibited distinct patterns, but were mainly expressed in hemocytes. α1 and β2 subunits are the predominant ones either in the embryogenesis or larva stages. Interestingly, integrins were significantly up-regulated after stimulated by 20-hydroxyecdysone (20-E) in vivo. These results indicate that integrins performdiverse functions in hemocytes of silkworm. Overall, our results provide a newinsight into the functional and evolutionary features of integrins. / National Basic Research Programof China (No. 2012cb114603), the Research Fund for the Doctoral Program of Higher Education of China (20130182110003), the Natural Science Foundation of Chongqing (cstc2013jcyjys0007), and the Fundamental Research Funds for the Central Universities (SWU111014).