Effects of fumigation with methyl iodide or methyl bromide/ethylene oxide mixed gas against biological specimen DNA were examined using dried samples of spinach leaf, muscle and bone marrow of chicken, mushroom and yeast. The condition of fumigated DNA varied, depending on species, tissue, extraction method, and fumigant. Fumigation caused a decrease in the yield of high molecular weight DNA, and sometimes smears of degraded DNA were observed on electrophoresis gels. However, PCR amplification and direct sequencing of fumigated DNA was hardly affected: there was no difference in the DNA sequence of all PCR products. Methyl iodide had less effect on DNA when compared with methyl bromide/ethylene oxide mixed gas. Fumigation caused protein denaturation and changed protein solubility. In addition, DNA degradation increased when extracted by kits without chloroform treatment. We conclude that the decrease of high molecular weight DNA yield is caused mainly by denatured proteins obstructing DNA extraction, rather than direct degradation of DNA during fumigation.
Carex persistens Ohwi var. watanabei Ohwi was described in "New Flora of Japan" (Ohwi & Kitagawa 1983) on the basis of the material from Fukui Pref. with perigynia patently hairy. This name is, however, nomenclaturally invalid because the Latin description was not given in the protologue. In order to clarify whether this variety is acceptable as a taxon, we examined its original material and many herbarium specimens of related taxa, C. persistens including var. takeuchii Ohwi, and also made field survey. The result showed that hair density on perigynia continuously varied from glabrous to densely setaceous. The glabrous form had the widest distribution range, and the forms with more hairy perigynia were restricted in the northern Kinki district and Fukui Pref. However, even in the area where the hairy forms are distributed, the glabrous form is commonly found, and any ecological differences were not detected in their habitat. Therefore we concluded that C. persistens should be treated as a variable species without recognizing any infraspecific taxa based on the hairiness of perigynia such as var. takeuchii or var. watanabei.
Although all recent Japanese floras had recognized Potamogton cristatus Regel et Maack as a species distributed in Honshu and Kyushu but not in Hokkaido, we found this species in Kamihoromui, Iwamizawa city of central Hokkaido in 2000. A careful reexamination of early floristic reports and herbarium specimens clarified that P. cristatus was once collected at Sapporo city of central Hokkaido by Dr. K. Miyabe in 1901 and its presence in Hokkaido was reported by Miyabe and Kudo (1931). Thus, the present report is a rediscovery of P. cristatus in Hokkaido after about a century. Other previous floristic reports which admitted the presence of this species in Hokkaido, were not based on any reliable herbarium specimens.