Introduction of mitochondrial DNA from <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> into <Emphasis Type="Italic">Pleurotus pulmonarius</Emphasis> by interspecific protoplast fusion

Interspecific protoplast fusion between two monokaryotic strains (a methionine auxotrophic and chloramphenicol-resistant Pleurotus ostreatus strain and a wild-type strain of Pleurotus pulmonarius) was carried out to introduce mitochondrial DNA (mtDNA) from P. ostreatus into P. pulmonarius. Because mycelial colonies regenerated on minimum medium containing chloramphenicol only after the treatment of protoplast electrofusion, the regenerants were regarded as protoplast fusants. The fusants isolated from regenerated colonies were uninucleate, and their resistance of chloramphenicol seemed to be a stable trait. The fusants mated with P. pulmonarius but not with P. ostreatus, and showed almost identical random amplified polymorphic DNA (RAPD) patterns to that of the parental P. pulmonarius monokaryon. The sizes of mitochondrial genomes were estimated to be 81.5 kb for P. ostreatus monokaryon, 54.9 kb for P. pulmonarius monokaryon, and 84.5 or 86.0 kb for the fusants. BamHI and EcoRI digest patterns of the fusant mtDNAs were almost the same as the parental P. ostreatus monokaryon. From the above results, the fusants seemed to carry nuclei derived from the monokaryon of P. pulmonarius and mtDNA including the chloramphenicol-resistance gene from the P. ostreatus monokaryon, suggesting that the P. ostreatus mtDNA had been introduced into P. pulmonarius cells by interspecific protoplast fusion. Contribution No. 383 of the Tottori Mycological Institute     

Comparison of behavioral characteristics of dogs in the United States and Japan

This study examined the difference in dog owning between Japan and the United States, and the effect of these differences on dogs’ behavioral characteristics. Behavioral evaluations of privately-owned dogs were obtained by using online questionnaire. We compared background and demographic information from the two countries and analyzed the effects of these differences on behavioral characteristics in dogs. The results indicated that there was a bias in the dog breeds kept in Japan compared to the United States and that Japanese dogs’ body weight was lower than the US dogs. The main source of dog acquisition was pet stores in Japan and breeders and/or shelters in the United States. Multiple linear regression analysis found that Japanese dogs showed more aggression to household members and higher energy, restlessness and fear of non-social stimuli than US dogs, while US dogs showed more fear of unfamiliar persons, separation-related behavior and excitability. US dogs also showed higher levels of trainability and attachment to owners. The lower dog’s body weight was, the higher the behavioral scores except for trainability were. When dogs that were obtained under 3 months of age were analyzed, the younger the dogs were when their owners obtained them, the higher the scores on some behavioral problem factors were. The higher rates of problem behaviors among Japanese dogs compared with US dogs suggest that the preference for small breed dogs and poor early development environment influenced the behavioral characteristics of dogs.