The Agnathan Enteropancreatic Endocrine System: Phylogenetic and Ontogenetic Histories, Structure, and Function

The extant jawless fishes (Agnatha) include the hagfishes andlampreys whose ancestry can be traced through a conserved evolutionto the earliest of vertebrates. This review traces the studyof the enteropancreatic (EP), endocrine cells and their productsin hagfishes and lampreys over the past two centuries. ErikaPlisetskaya is one of several prominent comparative endocrinologistswho studied the development, distribution or function of theagnathan EP system. Her physiological studies in Russia laidthe foundation for her subsequent isolation in North Americaof the first lamprey EP peptides (insulin and somatostatin)and providing the first homologous radioimmunoassay for agnathan(lamprey) insulin. This review also emphasizes the nature andthe method of development of the agnathan endocrine pancreas(islet organ), for it reflects the earliest vertebrate endocrinepancreas originating from intestinal and/or bile-duct epithelia.The lamprey life cycle includes a protracted larval period anda metamorphosis when the adult EP system develops. Differencesin morphogenesis during metamorphosis of southern- and northern-hemispherelampreys dictate that a single cranial mass (islet organ) appearin the former and both a cranial and a caudal principal isletcomprises most of the islet organ in holarctic species. Thereare differences in distribution of cell types and in the primarystructure of the peptides in the definitive islet organ of hagfishesand lampreys. The primary structures of insulin, somatostatins,glucagons, glucagon-like peptide, and peptide tyrosine tyrosineare now available for three lamprey species representing threegenera and two of the three families. Differences in structureof peptides within, and between, families is providing supportfor earlier views on the time of divergence of the familiesand the different genera. It is concluded that due to the ancientlineage and successful habitation of lampreys and hagfishes,and the importance of the EP system to their survival, thattheir EP systems should be a research focus well into the nextcentury.     

Potential phylogenetic utility of the low-copy nuclear gene pistillata in dicotyledonous plants: comparison to nrDNA ITS and trnL intron in Sphaerocardamum and other Brassicaceae.

We report the potential phylogenetic utility of DNA sequence data from the last 700 bp of a ca. 1-kb intron of the MADS-box gene pistillata from a sampling of Sphaerocardamum species and other Brassicaceae. These results are compared with nrDNA ITS and the chloroplast trnL intron for the same taxa to demonstrate the potential phylogenetic utility of this pistillata intron and to identify potential historically independent sequences for an ongoing study of relationships within Sphaerocardamum. Analyses of the DNA sequence data for Brassicaceae indicated that pairwise divergences and potentially informative characters were higher in the pistillata intron (0.6-30.8%, 284 characters) and ITS (0-24%, 94 characters) than in the chloroplast trnL intron (0-4.2%, 17 characters). A comparison of Sphaerocardamum sequences identified low divergences and numbers of informative characters for trnL intron (0-2.4%, 1 character) and nrDNA ITS (0-2.5%, 2 characters) and substantially more variation among the pistillata sequences (0.15-3.7%, 19 characters). Phylogenetic analyses of these pistillata sequences fully resolve ingroup relationships without character conflict. Results of pistillata PCR amplifications from a broader dicot sample showed that some primers may be useful in amplifying orthologous pistillata sequences. Ultimately this pistillata intron may be a valuable source of phylogenetic characters at lower taxonomic levels.     

Multigenic polymorphism as a source of adaptively restricted population variability

Among 400 Drosophila melanogaster flies individually analysed for nine gene–enzyme systems, a total of 160 different genotypes were found: 78 were repeatedly observed in two to 22 individuals, and 82 appeared only once. An increase in the frequency of rare alleles could be observed in such groups of genotypes that were less frequent. Among 24 most frequent genotypes (in 189 individuals) only four different combinations of five third-chromosomal genes are present, and 12 different combinations of three second-chromosomal genes. Among 82 unique genotypes these combinations were much more versatile: 29 at the third, 22 at the second, and three at the first chromosomes. The proportion of heterozygotes was increasing from most frequent toward unique genotypes (1.5–2.1 ± 0.1), primarily due to heterozygosity in five third-chromosomal loci (0.4–1.1 ± 0.06). When the number of genotypes in 100, 200, 300 and 400 sampled flies was extrapolated to larger samples, it became clear that this increase has an asymptotic character. It must be assumed that for our nine-loci model a total of approximately 200–220 different genotypes may exist in a population of a few thousands individuals, which means that adaptive variation for such a complex gene–enzyme system must be very much limited.     

Determination of the inorganic degradation products sulfate and sulfamate in the antiepileptic drug topiramate by capillary electrophoresis

A capillary electrophoresis (CE) method has been developed as an alternative method for the determination of the inorganic degradation products sulfate and sulfamate in topiramate drug product and drug substance, currently performed by ion chromatography. The anions are separated in a background electrolyte containing potassium chromate and boric acid, followed by indirect UV detection. By adding tetradecyltrimethylammonium bromide to the electrolyte, analysis is performed under co-electroosmotic flow conditions. Variations in injection volumes and migration times are compensated for by use of an internal standard. The validation of the method, which was performed according to ICH guidelines (International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use) [1], comprises specificity, accuracy, linearity, precision, sensitivity and robustness. In addition, the results of an actual tablet sample analysis obtained by this CE method are statistically shown to be in close agreement with those obtained by an ion chromatographic method.     

Thienopyrimidine-based P2Y12 platelet aggregation inhibitors

Herein we describe the design and synthesis of a novel series of potent thienopyrimidine P2Y₁₂ inhibitors and the negative impact protein binding has on the inhibition of platelet aggregation.