Introductory gestures before songbird vocal displays are shaped by learning and biological predispositions.

Numerous animal displays begin with introductory gestures. For example, lizards start their head-bobbing displays with introductory push-ups, and many songbirds begin their vocal displays by repeating introductory notes (INs) before producing their learned song. Among songbirds, the acoustic structure and the number of INs produced before song vary considerably between individuals in a species. While similar variation in songs between individuals is a result of learning, whether variations in INs are also due to learning remains poorly understood. Here, using natural and experimental tutoring with male zebra finches, we show that mean IN number and IN acoustic structure are learned from a tutor. Interestingly, IN properties and how well INs were learned, were not correlated with the accuracy of song imitation and only weakly correlated with some features of songs that followed. Finally, birds artificially tutored with songs lacking INs still repeated vocalizations that resembled INs, before their songs, suggesting biological predispositions in IN production. These results demonstrate that INs, just like song elements, are shaped both by learning and biological predispositions. More generally, our results suggest mechanisms for generating variation in introductory gestures between individuals while still maintaining the species-specific structure of complex displays like birdsong.

RNA-Seq mediated root transcriptome analysis of Chlorophytum borivilianum for identification of genes involved in saponin biosynthesis.

Chlorophytum borivilianum is an important species of liliaceae family, owing to its vital medicinal properties. Plant roots are used for aphrodisiac, adaptogen, anti-aging, health-restorative and health-promoting purposes. Saponins, are considered to be the principal bioactive components responsible for the wide variety of pharmacological properties of this plant. In the present study, we have performed de novo root transcriptome sequencing of C. borivilianum using Illumina Hiseq 2000 platform, to gain molecular insight into saponins biosynthesis. A total of 33,963,356 high-quality reads were obtained after quality filtration. Sequences were assembled using various programs which generated 97,344 transcripts with a size range of 100-5,216 bp and N50 value of 342. Data was analyzed against non-redundant proteins, gene ontology (GO), and enzyme commission (EC) databases. All the genes involved in saponins biosynthesis along with five full-length genes namely farnesyl pyrophosphate synthase, cycloartenol synthase, ß-amyrin synthase, cytochrome p450, and sterol-3-glucosyltransferase were identified. Read per exon kilobase per million (RPKM)-based comparative expression profiling was done to study the differential regulation of the genes. In silico expression analysis of seven selected genes of saponin biosynthetic pathway was validated by qRT-PCR.

De Novo transcriptome sequencing reveals important molecular networks and metabolic pathways of the plant, Chlorophytum borivilianum.

Chlorophytum borivilianum, an endangered medicinal plant species is highly recognized for its aphrodisiac properties provided by saponins present in the plant. The transcriptome information of this species is limited and only few hundred expressed sequence tags (ESTs) are available in the public databases. To gain molecular insight of this plant, high throughput transcriptome sequencing of leaf RNA was carried out using Illumina's HiSeq 2000 sequencing platform. A total of 22,161,444 single end reads were retrieved after quality filtering. Available (e.g., De-Bruijn/Eulerian graph) and in-house developed bioinformatics tools were used for assembly and annotation of transcriptome. A total of 101,141 assembled transcripts were obtained, with coverage size of 22.42 Mb and average length of 221 bp. Guanine-cytosine (GC) content was found to be 44%. Bioinformatics analysis, using non-redundant proteins, gene ontology (GO), enzyme commission (EC) and kyoto encyclopedia of genes and genomes (KEGG) databases, extracted all the known enzymes involved in saponin and flavonoid biosynthesis. Few genes of the alkaloid biosynthesis, along with anticancer and plant defense genes, were also discovered. Additionally, several cytochrome P450 (CYP450) and glycosyltransferase unique sequences were also found. We identified simple sequence repeat motifs in transcripts with an abundance of di-nucleotide simple sequence repeat (SSR; 43.1%) markers. Large scale expression profiling through Reads per Kilobase per Million mapped reads (RPKM) showed major genes involved in different metabolic pathways of the plant. Genes, expressed sequence tags (ESTs) and unique sequences from this study provide an important resource for the scientific community, interested in the molecular genetics and functional genomics of C. borivilianum.

Characterization of Squalene synthase gene from Chlorophytum borivilianum (Sant. and Fernand.).

Saponins are important group of secondary metabolites known for their pharmacological properties. Chlorophytum borivilianum contains high amount of saponins and is thus, recognized as an important medicinal plant with aphrodisiac properties. Though the plant is well known for its pharmaceutical properties, there is meager information available about the genes and enzymes responsible for biosynthesis of saponins from this plant. Squalene synthase (SqS) is the key enzyme of saponin biosynthesis pathway and here, we report cloning and characterization of SqS gene from C. borivilianum. A full-length CbSqS cDNA consisting of 1,760 bp was cloned which contained an open reading frame (ORF) of 1,233 bp, encoding a protein of 411 amino acids. Analysis of deduced amino acid sequence of CbSqS predicted the presence of conserved isoprenoid family domain and catalytic sites. Phylogenetic analysis revealed that CbSqS is closer to Glycine max and monocotyledonous plants. 3D structure prediction using various programs showed CbSqS structure to be similar to SqS from other species. C-terminus truncated recombinant squalene synthase (TruncCbSqS) was expressed in E. coli M15 cells with optimum expression induced with 1 mM IPTG at 37 °C. The gene expression level was analyzed through semi-quantitative RT-PCR and was found to be higher in leaves as compared to the roots.

Differentially expressed transcripts from leaf and root tissue of Chlorophytum borivilianum: a plant with high medicinal value.

Chlorophytum borivilianum is one of the important medicinal plants used for treating different health problems such as diabetes, arthritis, physical weakness, etc. Saponins present in C. borivilianum are the primary source of its significant medicinal properties and are synthesized by mevalonate and non-mevalonate pathways in plants. However, the biosynthesis of these compounds at molecular level is not studied in C. borivilianum. Cloning and sequencing of genes involved in metabolic processes are prerequisite to study the gene expression, their regulation and genetic engineering experiments. Expressed sequence tags (ESTs) provide a quick insight into various genes and their tissue specific expression. Suppression subtractive hybridization (SSH) libraries were constructed using mRNA from leaf and root tissues of C. borivilianum. High quality non-redundant 506 and 303 ESTs were generated from leaf and root specific libraries respectively. These sequences were analyzed using bioinformatics tools and grouped into different categories based on their similarity and cellular functions such as photosynthesis, metabolism, transcription factors, cell signaling, defense, stress response etc. ESTs also showed similarity with genes involved in saponins biosynthesis such as squalene synthase, squalene epoxidase, cytochrome p450, glycosyltransferase, etc. Semi-quantitative analysis of some of the ESTs involved in saponins biosynthesis confirmed their differential regulation in leaves and roots. These ESTs will provide an efficient resource to accelerate gene discovery in C. borivilianum and will help in determining promising targets for genetic engineering of saponins pathway.