Genome sequencing and assembly of Indian golden silkmoth, Antheraea assamensis Helfer (Saturniidae, Lepidoptera).

Muga silkworm (Antheraea assamensis), one of the economically important wild silkmoths, is unique among saturniid silkmoths. It is confined to the North-eastern part of India. Muga silk has the highest value among the other silks. Unlike other silkmoths, A. assamensis has a low chromosome number (n = 15), and ZZ/ZO sex chromosome system. Here, we report the first high-quality draft genome of A. assamensis, assembled by employing the Illumina and PacBio sequencing platforms. The assembled genome of A. assamensis is 501.18 Mb long, with 2697 scaffolds and an N50 of 683.23 Kb. The genome encompasses 18,385 protein-coding genes, 86.29% of which were functionally annotated. Phylogenetic analysis of A. assamensis revealed its divergence from other Antheraea species approximately 28.7 million years ago. Moreover, an investigation into detoxification-related gene families, CYP450, GST, and ABC-transporter, revealed a significant expansion in A. assamensis as compared to the Bombyx mori. This expansion is comparable to Spodoptera litura, suggesting adaptive responses linked to the polyphagous behavior observed in these insects. This study provides valuable insights into the molecular basis of evolutionary divergence and adaptations in muga silkmoth. The genome assembly reported in this study will significantly help in the functional genomics studies on A. assamensis and other Antheraea species along with comparative genomics analyses of Bombycoidea insects.

Release of Mediator Enzyme ß-Hexosaminidase and Modulated Gene Expression Accompany Hemocyte Degranulation in Response to Parasitism in the Silkworm Bombyx mori.

In insects infections trigger hemocyte-mediated immune reactions including degranulation by exocytosis; however, involvement of mediator enzymes in degranulation process is unknown in insects. We report here that in silkworm Bombyx mori, infection by endoparasitoid Exorista bombycis and microsporidian Nosema bombycis activated granulation in granulocytes and promoted degranulation of accumulated structured granules. During degranulation the mediator lysosomal enzyme ß-hexosaminidase showed increased activity and expression of ß-hexosaminidase gene was enhanced. The events were confirmed in vitro after incubation of uninfected hemocytes with E. bombycis larval tissue protein. On infection, cytotoxicity marker enzyme lactate dehydrogenase (LDH) was released from the hemocytes illustrating cell toxicity. Strong positive correlation (R2 = 0.71) between LDH activity and ß-hexosaminidase released after the infection showed parasitic-protein-induced hemocyte damage and accompanied release of the enzymes. Expression of ß-hexosaminidase gene was enhanced in early stages after infection followed by down regulation. The expression showed positive correlation (R2 = 0.705) with hexosaminidase activity pattern. B. mori hexosaminidase showed 98% amino acid similarity with that of B. mandarina showing origin from same ancestral gene; however, 45-60% varied from other lepidopterans showing diversity. The observation signifies the less known association of hexosaminidase in degranulation of hemocytes induced by parasitic infection in B. mori and its divergence in different species.

Molecular characterization and functional analysis of the vitellogenin receptor from eri silkworm, Samia ricini.

The vitellogenin receptor (VgR) plays a critical role in egg development by mediating endocytosis of the major yolk protein precursor vitellogenin (Vg). Therefore, identifying the VgR of beneficial insects and its characterization could lead to the development of novel egg production strategies to enhance their commercial values. Here, we present the cloning, expression, and functional characterization of the VgR from an economically important eri silkworm, Samia ricini. The complete mRNA sequence was 6002 bp with an ORF of 5484 bp, encoding a protein of 1827 amino acids. Sequence analyses revealed that the SrVgR contained all of the conservative structural motifs characteristics of LDLR family members. The SrVgR was specifically expressed in the ovary, and the mRNA level increased steadily in pupal stages, reached its peak on day 9, and then declined to a bare minimum in adults. RNA interference (RNAi) clearly reduced the VgR transcript levels, disrupted the ovarian development resulting in malformed ovarioles and abnormal development of eggs. Taken together, these data provide conclusive evidence for the essential roles of VgR in insect reproduction.

The Intra-familial Relationships of Pentaphylacaceae s.l. as Revealed by DNA Sequence Analysis.

During the past three decades, molecular taxonomy has made considerable changes in the systematic delimitations of several families in the order Ericales which were formed earlier based on morphology. For instance, the Pentaphylacaceae s.l. has been treated differently by both modern and traditional taxonomists. Modern molecular taxonomists constituted this family by combining the traditionally defined Pentaphylacaceae s.s. (Pentaphylax), Sladeniaceae s.s. (Sladenia), the subfamily Ternstroemioideae with 11 genera of Theaceae s.l. and the genus Ficalhoa. There are also treatments placing the genus Pentaphylax with Ternstroemioideae in Pentaphylacaceae and Ficalhoa with Sladenia in Sladeniaceae. Because most of these genera are poorly studied, investigations on all aspects are important to understand the phylogeny to settle the issues surrounding the treatment of the 14 genera in this family. In the present study, DNA sequences of nrITS and trnL-F genes from species of 11 genera from these 14 genera were generated and analyzed together with sequences from other closely related members of Ericales. The results suggested existence of four distinct lineages viz., Sladenia, Pentaphylax, and tribes Frezierieae (9 genera) and Ternstroemieae (2 genera). Further, it demonstrated that within the biggest lineage, Frezierieae, the Visnea remained sister to the clades Adinandra+Cleyera, Euryodendron+Symplococarpon, Freziera, and finally, Eurya. Based on the evidence, it can be concluded that Sladeniaceae and Pentaphylacaceae are very close to each other and the proposal of merging them into a mega family Pentaphylacaceae s.l. with four tribes, i.e., Sladenieae, Pentaphylaceae, Ternstroemieae, and Freziereae should be considered seriously.

Molecular taxonomy of Camellia (Theaceae) inferred from nrITS sequences.

Camellia, comprising more than 200 species, is the type genus of the family Theaceae. Currently, the interspecies relationship of the economically important genus is still a matter of great debate and controversy. In an attempt to help settle this dispute using molecular phylogeny, we analyzed ITS sequences of 112 species of Camellia. The maximum parsimony and Bayesian trees grouped these species into eight major clades and four isolates. The current study supported the monophyly of sections Thea and Furfuracea, a merged section of Theopsis and Eriandra and the formation of section Oleifera by H, -t. Chang (Flora of Reipulicae Popularis Sinicae. Tomus 49 (3), Science Press, China). The study suggested the polyphyletic nature of the sections Camellia, Paracamellia, Pseudocamellia, and Tuberculata and the paraphyletic nature of the section Chrysantha but did not support the sectional status of the three small sections, Archecamellia, Piquetia, and Sterocarpus. We also discuss the results in terms of morphology, geographic distribution and the results from an earlier molecular phylogeny analysis.