Analysis of the sequence of a new cryptic plasmid, pRJF2, from a rumen bacterium of the genus Butyrivibrio: Comparison with other Butyrivibrio plasmids and application in the development of a cloning vector

Abstract A small cryptic plasmid, pRJF2, from Butyrivibrio fibrisolvens strain OB157 was isolated and sequenced. The plasmid is similar in organisation to the previously sequenced Butyrivibrio plasmid, pRJF1, with two open reading frames, ORF1 and ORF2, flanking a region tentatively identified as the replication origin, and a region of unknown function defined by terminal 79 bp invert repeats. The sequences of ORF1, ORF2, and the presumptive replication origin are highly conserved. The sequence between the 79 bp invert repeats is not, and is therefore presumed to be of lesser functional significance, although the 5' and 3' termini are still highly conserved. The functional importance for plasmid replication of these regions was tested by constructing potential shuttle vectors, each lacking one or more of the regions of interest. When the region between the invert repeats was deleted and replaced by the erythromycin resistance gene from pAM β1 together with pUC18, to produce the 7.9 kb chimaeric plasmid pYK4, the construct was successfully transformed into E. coli and B. fibrisolvens by electroporation, and was stably maintained in both hosts. Both ORF1 and ORF2 were required for successful transformation of B. fibrisolvens .     

Low-pressure microwave-induced helium plasma emission spectrometry: Vaporization characteristics of metal chlorides,nitrates, and sulfates

A low-pressure microwave-induced helium plasma serves as an excitation source for metal chlorides, nitrates, and sulfates vaporized from a filament, resulting in fractional vaporization and differential sensitivities of detection of the elements depending on the vapor pressures of their salts. The shapes of the single emission peaks, which are simple in the presence of potassium chloride, become complex and may double in number.     

Effects of different light intensities during the forenoon on the afternoon thermal sensation in mild cold

1. 1. The study aimed at knowing whether thermal sensation during afternoon cool exposure could be influenced by bright light (4000 lx) or dim light (200 lx) in the forenoon.

2. 2. The subjects felt cooler after exposure to dim light than to bright light.

3. 3. Melatonin in the urine was significantly higher in bright light than in dim light at 10:30 h and at noon.