There have been numerous studies of seeking evidence for common mechanisms of aging. Study of Caenorhabditis elegans has provided much information and breakthrough techniques for gerontologists. The influence of genome on life span is clearly observable, and several genes have been defined in the last decade. These genes also seem to govern resistance to oxidative stress involving aging process. In this review we survey the ways in which genetical investigations have done among gerontologists in the last decade, some of the consequences of the genes which are responsible for life span, and some of prospects for life span determination mechanism and aging process control mechanism in C. elegans.

View full abstract

In order to use random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) for the identification of ten Meloidogyne species in Japan, experiments were conducted on the screening of primers and on the extraction of template DNA. Of 120 random sequence 10-mer primers (OPA, OPB, OPC, OPD, OPF, and OPG kits; Operon Technologies) tested, primer OPA-01 alone was successful in the species identification of M. inocgonita, M. arenaria, M. javanica, M. hapla, M. suginamiensis, M. marylandi, M. mali, M. camelliae, M. sp. resemble to M. arenaria, and M. sp. resemble to M. mali. When the primer OPA-01 and the template DNA extracted with lysis buffer (DNA extraction buffer) from a single individuals of the 2nd-stage juvenile (J2) or of adult male were used, PCR amplification yielded reproducible RAPD patterns which differentiated the ten Meloidogyne species examined. The difference was also recognized among the RAPD patterns, especially of M. arenaria and M. javanica, by using the template DNA extracted from many adult females with the extraction method of highly pure DNA and by using that from a single J2 with the lysis buffer. The RAPD patterns were presumed to be considerably affected by the magnesium concentration in template DNA.

View full abstract

Three species of the genus Mononchus were collected from wet soil in Gunma prefecture, central Japan: Mononchus truncatus BASTIAN, 1865, M. aquaticus COETZEE, 1968, and M. tunbridgensis BASTIAN, 1865. M. aquaticus and M. truncatus were always collected together from the same paddy field soil. These two species were differentiated by the stoma length, position of transverse rib and dorsal tooth apex, and tail shape. M. truncatus from the stream around mountains tends to have a longer stoma and tail than that from paddy fields. M. truncatus was found from 40 sites, M. aquaticus from six sites, and M. tunbridgensis from 26 sites out of 57 sites examined. Three males of M. truncatus and one of M. tunbridgensis were the new records from Japan. Their dimensions and distribution maps were indicated.

View full abstract

RAPD-PCR was applied to analyze genetic diversity of 15 isolates of Aphelenchus avenae collected from seven prefectures of Kyushu district, Okinawa, Ibaraki, and Fukushima prefectures in Japan. Forty ten-mer primers were screened for this purpose. Analysis of 106 polymorphic bands generated by 12 primers showed 77.5- 100 % similarity among the 15 isolates. Hierarchical cluster analysis of RAPD patterns resulted in the arrangement of the 15 isolates into four clusters. However, their genetic diversity did not correlate with their geographical distribution nor with such traits as preference to host fungi and/or temperature or male occurrence. The amplified PCR products of two ITS regions and 5.8S gene of the ribosomal DNA were approximately 0.9 kb for the 15 isolates. Digestion patterns of the amplified products with seven restriction enzymes revealed no intraspecific variations.

View full abstract

Using polyacrylamide gel electrophoresis, non - specific esterase isozyme phenotypes characterized 15 isolates of Aphelenchus avenae: 12 isolates from seven prefectures of Kyushu, one each from Okinawa, Ibaraki, and Fukushima prefectures in Japan. Twelve highly reproducible esterase isozyme bands were detected. Many of them were common for all isolates examined, while some were common only in a few isolates. The results of present study and those of our previous PCR-RAPD analysis were fairly compatible. Cluster analysis of isozyme phenotypes showed no correlation with geographic distribution and host/temperature preference of A. avenae. The nematode preference to host fungi and temperature was regarded as the results of adaptation.

View full abstract

[in Japanese]

View full abstract