RESUMO
The breakdown of self-incompatibility, which could result from the accumulation of non-functional S-haplotypes or competitive interaction between two different functional S-haplotypes, has been studied extensively at the molecular level in tetraploid Rosaceae species. In this study, two tetraploid Chinese cherry (Prunus pseudocerasus) cultivars and one diploid sweet cherry (Prunus avium) cultivar were used to investigate the ploidy of pollen grains and inheritance of pollen-S alleles. Genetic analysis of the S-genotypes of two intercross-pollinated progenies showed that the pollen grains derived from Chinese cherry cultivars were hetero-diploid, and that the two S-haplotypes were made up of every combination of two of the four possible S-haplotypes. Moreover, the distributions of single S-haplotypes expressed in self- and intercross-pollinated progenies were in disequilibrium. The number of individuals of the two different S-haplotypes was unequal in two self-pollinated and two intercross-pollinated progenies. Notably, the number of individuals containing two different S-haplotypes (S1- and S5-, S5- and S8-, S1- and S4-haplotype) was larger than that of other individuals in the two self-pollinated progenies, indicating that some of these hetero-diploid pollen grains may have the capability to inactivate stylar S-RNase inside the pollen tube and grow better into the ovaries.
Assuntos
Diploide , Haplótipos , Pólen/genética , Prunus/genética , Tetraploidia , Alelos , Sequência de Aminoácidos , Clonagem Molecular , Cruzamentos Genéticos , Regulação da Expressão Gênica de Plantas , Dados de Sequência Molecular , Especificidade de Órgãos/genética , Mapeamento Físico do Cromossomo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Ribonucleases/química , Ribonucleases/genética , Alinhamento de SequênciaRESUMO
Catecholamines, such as dopamine and noradrenaline, play important roles as neuromuscular transmitters and modulators in all parasitic helminthes, including Schistosoma japonicum. S. japonicum tyrosine hydroxylase (SjTH) was amplified by rapid amplification of cDNA ends polymerase chain reaction that shows strong homology to Schistosoma mansoni tyrosine hydroxylase, the enzyme that catalyzes the first and rate-limiting step in the biosynthesis of catecholamines. The SjTH transcripts encoded the protein of 463 amino acids and a predicted size of 54 kDa. Purified recombinant SjTH as an N-terminal histidine fusion protein expressed in Escherichia coli showed catalytic activity that was confirmed with (3)H tyrosine uptake. The purified enzyme was found to have the same absolute requirement for a tetrahydrobiopterin cofactor and similar sensitivity to be inhibited by high concentration of the substrate, tyrosine, as the mammalian enzyme. Also, purified SjTH showed characteristic inhibition by catecholamine products. The phosphorylated peptide from SjTH could interact with Sj14-3-3 signal protein. This evidence indicates that SjTH encodes a functional tyrosine hydroxylase that has catalytic properties similar to those of the mammalian hosts' enzyme, and its catalytic activity could be regulated by a phosphorylated or dephosphorylated form. This demonstration of SjTH further suggests that the parasites have the enzymatic capacity to synthesize catecholamines endogenously.