Two sex-linked loci in the leopard frog, Rana pipiens

Crosses involving one heterozygous parent were performed to test the inheritance of enzymes in the leopard frog, Rana pipiens. After metamorphosis, offspring were sexed and tissue extracts from them were analyzed by gel electrophoresis. Enzyme genotype and sex showed independent assortment for 10 of 12 enzymes heterozygous in the male parent. However, among the offspring of males heterozygous for peptidase C (Pep-C) or superoxide dismutase 1 (SOD-1), male progeny tend to inherit one allele, whereas female progeny tend to inherit the other. Data from several different crosses yield recombination frequencies of 8.6% between sex and SOD-1, 6.9% between SOD-1 and Pep-C and 12.1% between sex and Pep-C. When the female parent is heterozygous for these enzymes no significant difference is seen, in the offspring, between male and female homozygotes and heterozygotes. These results confirm that males are the heterogametic sex in R. pipiens and suggest that sex is determined by a small number of genes on otherwise identical X and Y chromosomes.

Peptidase isozymes of the leopard frog Rana pipiens: properties and genetics

The substrate specificity of five peptidases in tissues of the leopard frog, Rana pipiens, corresponds to mammalian peptidases (Pep) A, B, C, D, and S. The inheritance of electrophoretic variants of Pep A, B, C, and D verifies the genetic basis of the variants and the control of the enzymes by separate genetic loci. Electrophoretic patterns of heterozygotes suggest that Pep A, B, and D are dimers, whereas Pep C has a monomer structure. The tissue distribution and developmental patterns suggest that frog peptidases are subject to cellular regulation. Tests of genetic linkage show independent assortment for Pep A and Pep C and for Pep C and Pep D. Pep C is closely linked to superoxide dismutase-1 (6.87% recombination), and Pep B is linked to mannose phosphate isomerase (30.4% recombination).

Inheritance of enzymes and blood proteins in the leopard frog, Rana pipiens: three linkage groups established

Individuals from natural populations of the leopard frog, Rana pipiens, were analyzed for electrophoretic differences in blood proteins and enzymes from an amputated digit. The proteins examined represent products of 72 loci. Presumptive heterozygotes at multiple loci were selected for experimental crosses. Mendelian inheritance of 18 protein variations were demonstrated in the offspring. Tests for linkage or independent assortment were performed for 75 locus pairs. Three linkage groups were established. Linkage group 1 contains two loci, aconitase-1 (Acon 1) and serum albumin (Alb), with a 19% recombination frequency between them. Linkage group 2 contains four loci, glyoxalase (Gly), acid phosphatase-1 (Ap1), acid phosphatase-2 (AP2), and esterase-5 (Est5). The data show the relationships Gly-21.1%-AP1-0%-AP2-6.3%-Est5, and Gly-25.6%-Est5. Linkage group 3 consists of four closely linked esterase loci. The data, Est1-5.1%-Est6, Est6-1.8%-Est10-1.9%-Est4 and Est6-3.0%-Est4, do not establish a complete order but suggest that Est10 is between Est4 and Est6. These results, with data demonstrating apparent independent assortment of 67 other locus pairs, provide a foundation for establishing the frog genetic map.

Pyridone analogues of tetrahydroisoquinolines and protoberberines from mimosine and mimosinamine

Several pyrido[1,2-a]piperazines and their N-methyl derivatives have been prepared. These pyridine analogues of the 1,2,3,4-tetrahydroisoquinolines were formed by condensation of carbonyl compounds with mimosine and mimosinamine in the absence of an acid catalyst. A Mannich reaction converted one of these compounds, 1-(3,4-dimethoxybenzyl)-9-hydroxy-1,2,3,4-tetrahydro-8H-pyrido[1,2-a]- pyrazin-8-one, into a pyridone analogue of the tetrahydroprotoberberine caseadine.

The occurrence of diploid ova in Rana pipiens

All 12 Rana pipiens females tested from three populations produced diploid ova. These were identified by the development of from 0.15 to 35 percent per clutch of normal diploid-like embryos among large numbers of haploid embryos following activation of R. pipiens eggs with irradiated R. clamitans sperm. Their diploid nuclear constitution was demonstrated by diploid cell size at Shumway Stage 19, and by the diploid number of chromosomes both as embryos and as mature frogs, and was confirmed by the occurrence of triploid embryos among normally fertilized progeny from the same female parents. Although the precise cytogenetic events leading to the origin of these diploid ova were not directly determined, we were led to conclude that, although diploid ova may result from polynucleate oocytes, the diploidy reported here was an expression of abnormal meiosis that occurred under genetic control. Such anomalies, at the orders of frequency we observed in R. pipiens, have important consequences for all studies using Anuran model systems.

Synthesis of certain 4'-substituted nucleosides

We have developed general methods for the synthesis of 4'-fluoro- and 4'-methoxynucleosides by addition of iodinemonofluoride or iodine and methanol across the double bond of suitably protected 4',5'-unsaturated pyrimidine and purine nucleosides. The structures of these adducts have been determined by a combination of chemical, spectroscopic, and electrophoretic methods. The 4'-methoxy- and the uridine analogs of nucleocidin have been synthesized from the corresponding 4'-fluorouridine and 4'-methoxyadenosine derivatives.

Regeneration of digits and forelimbs in the Kenyan reed frog Hyperolius viridiflavus ferniquei

Newly metamorphosed individuals of the Kenyan reed frog, Hyperolius viridiflavus ferniquei, are able completely to regenerate amputated digits, including the morphologically complex digital pad. The sequence of morphological events is very similar to that seen in the typical epimorphic regeneration of amphibian extremities. Amputated forearms typically produce hypomorphic spike regenerates. Despite the lack of underlying hand and digital structures, an apical "digital" pad commonly differentiates.

Mass spectrometric studies. X. Phenacylpyridinium enol-betaines

Phenylpyridinium enol-betaines have mass spectra containing abundant molecular ions which decompose by loss of a hydrogen atom to give intense M- 1 species. Both ions eliminate CO and CHO units, and the courses of the various decompositions have been established by making use of deuterium labelling. The ion at m/e 92 in the spectrum of the parent compound is best described by an azatropylium structure.