Regulation of beta-endorphin and ACTH in brain by estradiol

The effect of estradiol on the brain concentration of immunoreactive beta-endorphin (beta-EP) and C-terminal ACTH (CLIP) was studied in ovariectomized rats. Dopamine, a known inhibitor of pituitary intermediate lobe pro-opiomelanocortin (POMC), was examined as a possible mediator of the estradiol induced changes in brain POMC. Animals were treated for 1 or 3 weeks with either 1) saline; 2) silastic estradiol implants; or 3) estradiol implants plus haloperidol 1 mg/kg/day. After one week of treatment no significant change in hypothalamic beta-EP content was noted in any group compared to the control level of 4.13 +/- .33 (SEM) pmoles although in the neurointermediate lobe beta-EP increased from 566 +/- 72 to 942 +/- 73 pmoles after haloperidol (p less than .005). After 3 weeks, however, hypothalamic beta-EP decreased from 3.96 +/- .28 to 2.74 +/- .19 pmoles (p less than .005) and C-terminal ACTH decreased from 3.78 +/- .33 to 2.82 +/- .18 pmoles (p less than .02) in the estradiol treated rats. This estradiol induced decrease in the hypothalamic content of beta-EP and C-terminal ACTH was not blocked by haloperidol. We conclude that estradiol lowers the hypothalamic content of beta-EP and CLIP and that this effect does not appear to be mediated by dopamine.     

Growth and survival of Bordetella bronchiseptica in natural waters and in buffered saline without added nutrients

Bordetella bronchiseptica showed increases in viable count when incubated in phosphate-buffered saline (PBS), in reagent-grade water, and in local lake and pond waters, all without added nutrients. Within 48 to 72 h at 37 degrees C in PBS and in lake and pond waters, stationary-phase populations of around 2.7 x 10(6) CFU/ml developed from washed B. bronchiseptica inocula of around 2 x 10(3) CFU/ml. Increases in CFU on the order of five- and eightfold, respectively, were observed in reagent-grade water and in seawater from the same sizes of inocula. The organisms remained viable for at least 3 weeks in PBS and in lake waters at 37 degrees C. The possibility that carry-over of nutrients was responsible for growth was discounted by showing serial transfer of B. bronchiseptica in PBS under conditions in which Escherichia coli tested in parallel rapidly died out.     

IgG-dependent generation of platelet-activating factor by normal and low density human eosinophils

We have compared normal and low density human eosinophils for their ability to generate platelet activating factor (PAF) in response to IgG-dependent and nonimmunologic stimulation. After 45 min incubation with IgG-coated Sepharose beads the concentrations of cell-associated PAF recovered from normal density eosinophils were significantly greater than from low-density eosinophils or neutrophils. Moreover, eosinophils stimulated with calcium ionophore A23187 had a considerably greater capacity to generate PAF than had previously been described. Although the quantities of cell-associated PAF recovered from normal and low density eosinophils and neutrophils after A23187 stimulation were similar, the amounts of extracellular PAF recovered from both eosinophil populations were significantly greater than from neutrophils. The amounts of PAF recovered from the low density eosinophils may not reflect the full synthetic capacity of these cells, because PAF-turnover was found to be more rapid than that observed with normal density eosinophils. When exogenous [3H]PAF was added to the two stimulated eosinophil populations subsequent analysis of the [3H]PAF metabolites by DIOL-HPLC revealed that low density eosinophils incorporated PAF into the phosphatidylcholine (PC) pool more rapidly than did normal density eosinophils or neutrophils. Alkaline hydrolysis of the PC fraction from whole cell extracts followed by treatment with acetic anhydride resulted in all the PC-associated radioactivity being converted to [3H]PAF, confirming PAF incorporation to PC via this pathway. These findings suggest that the contribution of eosinophils to inflammatory processes through the generation of PAF may be greater than previously appreciated, and that Ig-mediated stimulation may be important in initiating generation of the mediator. Low density eosinophils, that are presumed to be similar to tissue eosinophils, may have a role in regulating PAF concentrations in tissues through their enhanced rate of metabolism.     

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.      

The quantity and quality of overwintered larvae in five species of Myrmica (Hymenoptera: Formicidae)

The numbers of queens, workers and larvae were recorded for a sample of hibernating colonies from five different species of Myrmica. The larvae were divided into three size classes. The frequencies and distribution of larvae within these size classes have been compared between species and between queened and queenless colonies. A sample of each larval class was reared to the pupal stage and the resulting castes were recorded. The Discussion compares all the species with Myrmica rubra and attempts to explain the differences observed for the different species.