The red egg gene as a novel effective egg color marker for silkworm transgenesis.

Ommochromes are major pigments involved in coloration of eggs, eyes, and epidermis of arthropods. The recessive homozygous of egg and eye color mutant of Bombyx mori, red egg (re), exhibits red eggs and dark red eyes instead of normal purplish-brown eggs and black eyes, due to a defect in ommochrome pigment synthesis. The gene responsible for the re mutant is a major facilitator superfamily transporter gene, Bm-re.

Mutations in a β-group of solute carrier gene are responsible for egg and eye coloration of the brown egg 4 (b-4) mutant in the silkworm, Bombyx mori.

The brown egg 4 (b-4) is a recessive mutant in the silkworm (Bombyx mori), whose egg and adult compound eyes exhibit a reddish-brown color instead of normal purple and black, respectively. By double digest restriction-site associated DNA sequencing (ddRAD-seq) analysis, we narrowed down a region linked to the b-4 phenotype to approximately 1.1 Mb that contains 69 predicted gene models.

A Major Facilitator Superfamily protein encoded by TcMucK gene is not required for cuticle pigmentation, growth and development in Tribolium castaneum.

Insect cuticle pigmentation and sclerotization (tanning) are vital physiological processes for insect growth, development and survival. We have previously identified several colorless precursor molecules as well as enzymes involved in their biosynthesis and processing to yield the mature intensely colored body cuticle pigments. A recent study indicated that the Bombyx mori (silkmoth) gene, BmMucK, which encodes a protein orthologous to a Culex pipiens quiquefasciatus (Southern house mosquito) cis,cis, muconate transporter, is a member of the "Major Facilitator Superfamily" (MFS) of transporter proteins and is associated with the appearance of pigmented body segments of naturally occurring body color mutants of B.

Efficient TALEN construction for Bombyx mori gene targeting.

Engineered nucleases are artificial enzymes able to introduce double stranded breaks at desired genomic locations. The double stranded breaks start the error-prone repair process of non-homologous end-joining (NHEJ), which eventually leads to the induction of mutations at target sites. We showed earlier that ZFNs and TALENs are able to induce NHEJ mutations in the B.

Large scale full-length cDNA sequencing reveals a unique genomic landscape in a lepidopteran model insect, Bombyx mori.

The establishment of a complete genomic sequence of silkworm, the model species of Lepidoptera, laid a foundation for its functional genomics. A more complete annotation of the genome will benefit functional and comparative studies and accelerate extensive industrial applications for this insect. To realize these goals, we embarked upon a large-scale full-length cDNA collection from 21 full-length cDNA libraries derived from 14 tissues of the domesticated silkworm and performed full sequencing by primer walking for 11,104 full-length cDNAs.

A visible dominant marker for insect transgenesis.

Transgenesis of most insects currently relies on fluorescence markers. Here we establish a transformation marker system causing phenotypes visible to the naked eye due to changes in the color of melanin pigments, which are widespread in animals. Ubiquitous overexpression of arylalkylamine-N-acetyl transferase in the silkworm, Bombyx mori, changes the color of newly hatched first-instar larvae from black to a distinctive light brown color, and can be used as a molecular marker by directly connecting to baculovirus immediate early 1 gene promoter.

Identification of the Bombyx red egg gene reveals involvement of a novel transporter family gene in late steps of the insect ommochrome biosynthesis pathway.

Ommochromes are one of the major pigments involved in coloration of eggs, eyes, and body surface of insects. However, the molecular mechanisms of the final steps of ommochrome pigment synthesis have been largely unknown. The eggs of the silkworm Bombyx mori contain a mixture of ommochrome pigments, and exhibit a brownish lilac color.

Coevolution of telomeric repeats and telomeric repeat-specific non-LTR retrotransposons in insects.

In the telomeres of the silkworm Bombyx mori, telomeric repeat-specific non-long terminal repeat (LTR) retrotransposon SARTBm1 is accumulated in the TTAGG telomeric repeats. Here, we identify novel telomeric repeat-specific non-LTR retrotransposons, SARTTc family, from the red flour beetle Tribolium castaneum in the unconventional TCAGG telomeric repeats. To compare the sequence specificity of SARTBm1 and SARTTc1, we developed a comparable ex vivo retrotransposition assay.

Unique functions of repetitive transcriptomes.

Repetitive sequences occupy a huge fraction of essentially every eukaryotic genome. Repetitive sequences cover more than 50% of mammalian genomic DNAs, whereas gene exons and protein-coding sequences occupy only ~3% and 1%, respectively. Numerous genomic repeats include genes themselves.

Genome-wide screening and characterization of transposable elements and their distribution analysis in the silkworm, Bombyx mori.

To elucidate the contribution of transposable elements (TEs) to the silkworm genome structure and evolution, we have conducted genome-wide analysis of TEs using the newly released genome assembly. The TEs made up 35% of the genome and contributed greatly to the genome size. Non-long terminal repeat retrotransposons (non-LTRs) and short interspersed nuclear elements (SINEs) were the predominant TE classes.