Influence of Temperature of Incubation and Type of Growth Medium on Pigmentation in Serratia marcescens

Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 mug/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.     

Phylogeny of Greya (Lepidoptera: Prodoxidae), based on nucleotide sequence variation in mitochondrial cytochrome oxidase I and II: congruence with morphological data

The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from nucleotide sequence variation across a 765-bp region in the cytochrome oxidase I and II genes of the mitochondrial genome. Most parsimonious relationships of 25 haplotypes from 16 Greya species and two outgroup genera (Tetragma and Prodoxus) showed substantial congruence with the species relationships indicated by morphological variation. Differences between mitochondrial and morphological trees were found primarily in the positions of two species, G. variabilis and G. pectinifera, and in the branching order of the three major species groups in the genus. Conflicts between the data sets were examined by comparing levels of homoplasy in characters supporting alternative hypotheses. The phylogeny of Greya species suggests that host-plant association at the family level and larval feeding mode are conservative characters. Transition/transversion ratios estimated by reconstruction of nucleotide substitutions on the phylogeny had a range of 2.0-9.3, when different subsets of the phylogeny were used. The decline of this ratio with the increase in maximum sequence divergence among taxa indicates that transitions are masked by transversions along deeper internodes or long branches of the phylogeny. Among transitions, substitutions of A-->G and T-->C outnumbered their reciprocal substitutions by 2-6 times, presumably because of the approximately 4:1 (77%) A+T-bias in nucleotide base composition. Of all transversions, 73%-80% were A<-->T substitutions, 85% of which occurred at third positions of codons; these estimates did not decrease with an increase in maximum sequence divergence of taxa included in the analysis. The high frequency of A<-->T substitutions is either a reflection or an explanation of the 92% A+T bias at third codon positions.      

Experimental murine hypersensitivity pneumonitis

To establish a model of experimental hypersensitivity pneumonitis (EHP) in mice and to examine the influence of genetic background on the pulmonary inflammatory response to Micropolyspora faeni, we determined the responses of C57BL/6, SJL/J, and C3H/HeJ mice to intratracheal (i.t.) injections of M. faeni. Recipient animals received lymph node cells (LNC), peritoneal exudate cells (PEC), and spleen cells (SC) from sensitized mice cultured in vitro with M. faeni. Controls included serum containing anti-M. faeni antibody; uncultured SC from M. faeni-sensitized donors, and M. faeni-cultured SC from ovalbumin (OA)-sensitized donors. Recipients were challenged i.t. with M. faeni or normal saline 48 hr after the cell or serum transfer. We developed a model of EHP in mice. Increasing amounts of i.t. M. faeni were associated with increasing extent of pulmonary inflammation with no difference between the mouse strains. There was substantial increase of the extent of pulmonary abnormalities in the animals receiving cultured SC. The number of transferred cells and the M. faeni concentration correlated with the extent of pulmonary histologic abnormalities. Cultured PEC and LNC could transfer EHP in C3H/HeJ mice only. Serum containing anti-M. faeni antibody, cultured SC from OA-sensitized donors, and noncultured SC from sensitized donors could not transfer EHP. We conclude that it is possible to adoptively transfer EHP.