New coumarin-benzotriazole based hybrid molecules as inhibitors of acetylcholinesterase and amyloid aggregation

A novel series of triazole tethered coumarin-benzotriazole hybrids based on donepezil skeleton has been designed and synthesized as multifunctional agents for the treatment of Alzheimer’s disease (AD). Among the synthesized compounds 13b showed most potent acetylcholinesterase (AChE) inhibition (IC₅₀ = 0.059 μΜ) with mixed type inhibition scenario. Structure-activity relationship revealed that three-carbon alkyl chain connecting coumarin and triazole is well tolerable for inhibitory potential. Hybrids obtained from 4-hydroxycoumarin and 1-benzotriazole were most potent AChE inhibitors. The inhibitory potential of all compounds against butyrylcholinesterase was also evaluated but all showed negligible activity suggesting that the hybrid molecules are selective AChE inhibitors. 13b (most potent AChE inhibitor) also showed copper-induced Aβ_1-42 aggregation inhibition (34.26% at 50 μΜ) and chelating properties for metal ions (Cu²⁺, Fe^2+, and Zn²⁺) involved in AD pathogenesis along with DNA protective potential against degenerative actions of OH radicals. Molecular modelling studies confirm the potential of 13b in blocking both PAS and CAS of AChE. In addition, interactions of 13b with Aβ_1-42 monomer are also streamlined. Therefore, hybrid 13b can act as an effective hit lead molecule for further development of selective AChE inhibitors as multifunctional anti-Alzheimer’s agents.     

Genetic variation,inheritance, and quaternary structure of malic enzyme in brook trout (Salvelinus fontinalis)

Electrophoretic variation is described for malic enzyme (ME) for the first time in brook trout (Salvelinus fontinalis). Since the quaternary structure of ME was not clear from examination of banding patterns in brook trout alone, ME phenotypes in rainbow trout (Salmo gairdneri) × brook trout hybrids as well as in esocid species demonstrated that ME is tetrameric. A model of two duplicated loci is proposed to account for the observed variation. One locus (ME-2) is fixed and one locus (ME-1) is variable with three electrophoretically distinct alleles; the protein products of ME-1 are reduced in activity relative to the protein products of ME-2. Joint segregation was examined between ME-1 and ten other biochemical loci in brook trout, and between ME-1, ME-2, and nine other biochemical loci in a splake—lake trout (Salvelinus namaycush) × brook trout hybrid—backcross. All pairwise examinations showed random assortment except ME-2 with an isocitrate dehydrogenase locus (IDH-3), which showed complete linkage in the splake backcross. This may be due to a chromosomal aberration.Authorized for publication as Paper No. 5599 in the Journal Series of The Pennsylvania Agricultural Experiment Station, University Park, Pennsylvania, in cooperation with the Benner Spring Fish Research Station, The Pennsylvania Fish Commission, Bellefonte, Pennsylvania. M.S. was supported by an NSF Graduate Fellowship.     

Triploidy permits survival of an inviable amphibian hybrid

Hybrids between species frequently arrest early in development. In the frog hybrid Rana catesbeiana female × Rana clamitans male, the embryo shows a characteristic development to an exogastrula which dies. This hybrid can be rescued by pressure suppression of the second polar body, which results in the addition of another haploid set of R catesbeiana chromosomes to the embryo. The triploid hybrid expresses genes from both species and can develop normally through metamorphosis. The results show that an R catesbeiana egg containing a full haploid set of R clamitans chromosomes is capable of development and that the usual developmental arrest caused by the R clamitans genome responds to chromosomal dosage.     

Genetic characterization and relationships of Populus alba,P. tremula,and P. x canescens,and their clones

Summary Isozyme analysis was conducted on individuals of Populus alba L., P. tremula L., and P. × canescens Smith to genetically characterize and differentiate species, hybrids, and individuals, and to determine genetic relationships among them. Thirty gene loci, with 71 alleles, coding for 15 enzymes were observed. Individuals could be identified on the basis of their multilocus genotypes. There were 21 unique multilocus genotypes among 23 P. alba clones. Five P. alba clones from Canada were genetically distinct from each other. Each of the 18 P. tremula and 15 P. × canescens clones had unique multilocus genotypes. Thirteen clones had a unique genotype at a single locus. Percentage of polymorphic loci, average number of alleles per locus, and mean observed heterozygosity were, respectively, 50.0, 1.86, and 0.085 in P. alba, 51.7, 1.66, and 0.096 in P. tremula, and 51.7, 1.86, and 0.157 in P. × canescens. Populus alba and P. tremula were genetically distinct from each other and could be distinguished by mutually exclusive alleles at Aco-3, P. tremula-specific gene Mdh-3, and allele frequency differences at 6 loci. Populus × canescens had allele contributions of P. alba and P. tremula. However, their allele frequencies were closer to those of P. alba than being truly intermediate. The mean genetic identity was 0.749 between P. alba and P. tremula, 0.987 between P. alba and P. × canescens, and 0.817 between P. tremula and P. × canescens. Canonical discriminant analysis of multilocus genotypes separated P. alba, P. tremula, and P. × canescens into three distinct groups and portrayed similar interspecific relationship as above. Our results suggested that the putative P. × canescens individuals consisted of a mixture of F₁ hybrids of P. alba and P. tremula and their backcrosses to P. alba.Presently with the University of Alberta, and BioGenetica Inc., P.O. Box 8261, Edmonton, Alberta, Canada T6H 4P1     

Synthesis, morphology and cytogenetics of Raphanofortii (TTRR, 2n = 38): a new amphidiploid of hybrid Brassica tournefortii (TT, 2n = 20) ×Raphanus caudatus (RR, 2n=18)

Amphidiploid Raphanofortii was synthesized by colchicinization of the F₁ hybrid Brassica tournefortii (TT, 2n = 20)×Raphanus caudatus (RR, 2n = 18). The crossability between these two species, and the cytomorphology of the F₁ plants and the amphidiploids were investigated. Intergeneric hybrids between the species were obtained only when B. tournefortii was involved as female parent. The hybrid plants were intermediate for most of the morphological attributes and showed very low pollen fertility compared to the parents. Although a majority of the pollen mother cells of the dihaploid hybrid (TR, 2n = 19) harboured univalents, a maximum of six bivalents were also observed. Of the 37 colchicine-treated F₁ plants analyzed cytologically, 21 were found to be true amphidiploids (2n = 38), whereas seven were mixoploids. Meiosis in the amphidiploids was characterized by the occurrence of 19 bivalents, though multivalents and univalents were also observed in a few cells. Most of the amphidiploid plants exhibited a fairly high pollen and seed fertility, which was further enhanced with the advancement of generations. Out of 69 plants investigated in the A₂ generation, 64 were euploids while the remaining five were aneuploids (2n = 36, 37, 39, 40 and 42). The newly synthesized Raphanofortii has great potential as a new commercial crop, as well as a bridge species for the transfer of economically important attributes of both the species to other Brassicas. Received: 2 November 1999 / Accepted: 26 March 2000     

Inheritance of RAPD molecular makers in lake trout Salvelinus namaycush

Inheritance patterns of randomly amplified polymorphic DNA (RAPD) phenotypes were tested in 13 full-sib families of lake trout Salvelinus namaycush . Single-pair matings of parents with known phenotypes were made, and up to 20 progeny of each mating were used to test inheritance patterns. Seven RAPD primers amplified 13 polymorphic bands. With the exception of one family, expected segregation ratios for dominant Mendelian genetic traits were observed. Our results support previously reported findings that RAPD markers can be considered Mendelian traits and therefore could be used for analysis of genetic population structure.     

Cytogenetics of the trigeneric hybrid, (Hordeum vulgare ×Triticum aestivum) ×Secale cereale

Summary Chromosome pairing was studied in hybrids of (Hordeum vulgare ×Triticum aestivum) ×Secale cereale. Chiasma frequency per cell varied from 1.94 to 3.16 between the different hybrids. This variation was attributed to genetic variability in rye parents which affected homoeologous pairing. The pairing of rye chromosomes as revealed by Giemsa C-banding was a combination of nonhomologous association between rye chromosomes and associations with chromosomes of wheat and barley. Contribution No. 634 Ottawa Research Station     

Localization of the human fibronectin (FN) gene on chromosome 8 by a specific enzyme immunoassay

The fibronectin produced by clonal murine-human hybrid cell lines containing various complements of human chromosomes was measured. Human and murine fibronectins were assayed by specific immunoassay, and the production of human fibronectin was correlated with karyology and isozyme markers for specific human chromosomes. The data show a 100% concordance between the expression of human fibronectin and glutathione reductase, a marker for human chromosome 8, indicating that chromosome 8 codes for the fibronectin polypeptide.     

Comparative aspects of biochemical polymorphism in the blood of Caprinae species and their hybrids

Biochemical variation at 14 blood loci was reviewed, and specific features compared experimentally in sheep Ovis aries, mouflon Ovis musimon, goat Capra hircus, aoudad Ammotragus lervia and in 2 stillborn aoudad × goat hybrids. Variation at 3 loci was also studied in dall sheep Ovis dalli, bighorn sheep Ovis canadensis and rocky mountain goat Oreamnos americanus. Haemoglobin C production in an anaemic Hb AB mouflon and in mouflon × sheep hybrids was examined. Mouflon differ from domestic sheep in that synthesis of both Hb β^AHb β^Bchains is switched off during Hb C production. The mouflon × sheep hybrids switched off one or both chains depending on whether they had inherited sheep or mouflon Hb β chain genes. In general aoudad showed a closer affinity to goats than to sheep.