ABSTRACT
The many-banded krait, Bungarus multicinctus, has been recorded as the animal resource of JinQianBaiHuaShe in the Chinese Pharmacopoeia. Characterization of its venoms classified chief phyla of modern animal neurotoxins. However, the evolutionary origin and diversification of its neurotoxins as well as biosynthesis of its active compounds remain largely unknown due to the lack of its high-quality genome. Here, we present the 1.58 Gbp genome of B. multicinctus assembled into 18 chromosomes with contig/scaffold N50 of 7.53 Mbp/149.8 Mbp. Major bungarotoxin-coding genes were clustered within genome by family and found to be associated with ancient local duplications. The truncation of glycosylphosphatidylinositol anchor in the 3'-terminal of a LY6E paralog released modern three-finger toxins (3FTxs) from membrane tethering before the Colubroidea divergence. Subsequent expansion and mutations diversified and recruited these 3FTxs. After the cobra/krait divergence, the modern unit-B of β-bungarotoxin emerged with an extra cysteine residue. A subsequent point substitution in unit-A enabled the β-bungarotoxin covalent linkage. The B. multicinctus gene expression, chromatin topological organization, and histone modification characteristics were featured by transcriptome, proteome, chromatin conformation capture sequencing, and ChIP-seq. The results highlighted that venom production was under a sophisticated regulation. Our findings provide new insights into snake neurotoxin research, meanwhile will facilitate antivenom development, toxin-driven drug discovery and the quality control of JinQianBaiHuaShe.
ABSTRACT
Objective: To identify Rehmanniae Radiuxand its closely related species using the ITS2 barcode and to guarantee the quality and clinical curative effect of this medical material. Method: The sequences has been ana-lyzed and assembled using corresponding software. The Kimura 2-Parameter (K2P) distances were calculated and NJ (neighbor-joining) tree was established based on the K2P methods to identify the Rehmanniae Radix. Results:The length of the ITS2 sequence of Rehmanniae Radix was 231 bp. The average intra-specific genetic distances of Rehmanniae Radix were 0.0004. The average inter-specific genetic distances between Rehmanniae Radix and its closely related species were 0.0312. The minimum inter-specific divergence is larger than the maximum intra-specific divergence. The Rehmanniae Radix can be identified using the NJ trees method. Conclusions: The ITS2 sequence can be used as DNA barcode to identify Rehmanniae Radix and its closely related species, which will lay the foundation for the clinical medication safety of Rehmanniae Radix.
ABSTRACT
The ITS/ITS2 barcodes were used to simply and effectively identify Codonopsis Radix and its adulter-ants. In this study, ITS (internal transcribed spacer of unclear ribosomal DNA) regions were amplified using PCR (polymerase chain reaction) from thirty-three samples of Codonopsis Radix and ITS2 regions were obtained from the ITS sequences using the hidden Markov model (HMMer)-based annotation methods. The sequences of ITS/ITS2 regions were aligned and the genetic distances were computed by MEGA5.0. Species identification efficiency of ITS/ITS2 sequences were evaluated using BLAST1 and nearest distance methods. The results indicated that The sequences lengths of ITS regions of Codonopsis Radix were 654-655 bp, and the lengths of ITS2 regions were 239 bp. The intraspecific genetic distances among Codonopsis Radix were obviously lower than the interspecific genetic distance between Codonopsis Radix and its adulterants. Therefore, ITS/ITS2 regions can stably and accu-rately distinguish Codonopsis Radix and its adulterants.