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Basic and neutral neurohypophyseal (NH) nonapeptides have evolved from vasotocin (VT) by a gene duplication at the base of the gnathostome lineage. In teleosts, VT and IT are the basic and neutral peptides, respectively. In the present study, VT and IT precursor genes of Heteropneustes fossilis and Clarias batrachus (Siluriformes, Ostariophysi) were cloned and sequenced. The channel catfish Icatalurus punctatus NH precursor sequences were obtained from EST database. The catfish NH sequences were used along with the available Acanthopterygii and other vertebrate NH precursor sequences to draw phylogenetic inference on the evolutionary history of the teleost NH peptides. Synteny analysis of the NH gene loci in various teleost species was done to complement the phylogenetic analysis. In H. fossilis, the NH transcripts were also sequenced from the ovary. The cloned genes and the deduced precursor proteins showed conserved characteristics of the NH nonapeptide precursors. The genes are expressed in brain and ovary (follicular envelope) of H. fossilis with higher transcript abundance in the brain. The addition of the catfish sequences in the phylogenetic analysis revealed that the VT and IT precursors of the species-rich superorders of teleosts have a distinct phylogenetic history with the Acanthopterygii VT and IT precursors sharing a less evolutionary distance and the Ostariophysi VT and IT having a greater evolutionary distance. The genomic location of VT and IT precursors, and synteny analysis of the NH loci lend support to the phylogenetic inference and suggest a footprint of fish- specific whole genome duplication (3R) and subsequent diploidization in the NH loci. The VT and IT precursor genes are most likely lineage-specific paralogs resulting from differential losses of the 3R NH paralogs in the two superorders. The independent yet consistent retention of VT and IT in the two superorders might be directed by a stringent ligand-receptor selectivity.

The present study reports the molecular cloning of a previously uncharacterised neurohypophyseal nonapeptide precursor cDNA in two catfish species: Heteropneustes fossilis and Clarias batrachus. The deduced nonapeptide is CYISNCPVG ([V8] isotocin), which has not been reported in any vertebrate till date. Phylogenetic and conserved synteny analyses showed the gene to have originated from the isotocin precursor (pro‐it) gene by fish‐specific whole genome duplication (3R). The two isotocin lineages have been designated as pro‐ita (new gene) and pro‐itb (conventional it gene). All teleost groups may not possess both pro‐ita and pro‐itb and the pattern of losses/retention was found to be lineage‐specific. Quantitative reverse transcriptase‐polymerase chain reaction studies showed the expression of the pro‐ita gene in the brain and ovary of H. fossilis. In situ hybridisation studies localised the pro‐ita transcripts in the nucleus preopticus of the hypothalamus and the follicular layer (theca‐granulosa) of oocytes, comprising tissues in which pro‐itb and vasotocin precursor (pro‐vt) mRNA expression was previously reported. The transcript levels varied with the reproductive stage and a high abundance was found in both brain and ovary during the breeding phase. The substitution of valine in place of isoleucine at the eighth position in Ita may have modified the ligand‐receptor interaction, leading to sub‐functionalisation and the retention of the gene in catfishes.

Previously, the occurrence of several simple indolic bases in the aerial portions of Desmodium gangeticum D.C. (Leguminosae : Papilionaceae) was reported by us.lSince the roots of this species find use in the ayurvedic system of medicine,= we have now investigated their alkaloidal constituents. The present communication describes the isolation and identification of seven alkaloids representing three structural types, viz. carboxylated and decarboxylated tryptamines, and ,B-phenylethylamine. The bases identified are: N,N-dimethyltryptamine, its N,-oxide, hypaphorine, hordenine, candicine, N-methyltyramine, and P-phenylethylamine. I n addition, the presence of an apparently new P-phenylethylamine alkaloid was also detected. Preliminary findings indicated that the last-mentioned alkaloid is related to halostachine, a ,B-hydroxy-,B-phenylethylamine alkaloid occurring with tryptamines in the Chenopodiaceae.3VC7hile co-occurrence of P-phenylethylamines and simple indolic bases has been known in the genus Acacia4 (Leguminosae : Mimosae), the quaternary P-phenylethylamine base, candicine, appears to have been isolated only from the Argentine c a~t u s .~ Further, the previous results1 indicated that the elaboration of alkaloids by Desmoclium gangeticum had not been restricted to the "proto alkaloids" (alkamine~)~ only, since this species also contained two P-carboline alkaloids in its aerial portions.This alkaloid versatility of D. gangeticum obviously suggests it to be a phylogenetically complex species in the subfamily Papilionaceae, different from those6 producing either the carboxylated or decarboxylated tryptamines or the ,B-phenylethylamines.Some of the curative properties ascribed2 to the root extracts of D. ga.ngeticum seem to be due to the major alkaloid, hordenine, which is known to increase the flow of urine and is a remedy for diarrhoea and dysentery.7 Pharmacological evaluation of the species is currently being done in this laboratory.

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