fimA-folD genes linkage in Salmonella identifies a putative junctional site of chromosomal rearrangement in the enterobacterial genome

Abstract Analysis of the Salmonella chromosomal region located upstream of the fimA gene (coding for the major type 1 fimbrial subunit) showed a close linkage of this gene to the folD gene (coding for the enzyme 5,10-methylenetetrahydrofolate dehydrogenase/5, 10-methenyltetrahydrofolate cyclohydrolase), indicating that the fim gene cluster of Salmonella , unlike that of Escherichia coli , has no regulatory genes located upstream of fimA and apparently terminates with this gene. The respective locations of the fim and folD genes in the E. coli and Salmonella genetic maps suggests that the fimA-folD intergenic region of Salmonella encompasses a junctional site of a genetic rearrangement that probably originated from the different chromosomal location of the fim genes in these species.     

Fluctuations of grass pollen content in the atmosphere of East Perugia and meteorological correlations (year 1989)

Summary Gramineae pollination from a pollen monitoring station located in the eastern suburb of Perugia and meteorological correlations are reported. The data refers to the year 1989. Grass pollen peak pollination was from May to July; in this period the influence of relative humidity and of temperature on pollen concentration was very high. Phenological observations, to identify the time of maximum stamen extension in the most common genera in the area, are also reported. During the period of investigation the counts of pollen grains over four-hour periods showed a regular diurnal rhythm with peaks of concentration in the four-hour period 16.00–20.00. Aerosporological data and meteorological data related to four-hour periods were correlated following different criteria.     

Nutrient and chlorophyll a temporal patterns in eutrophic mountain ponds with contrasting macrophyte coverage

Hydrobiologia - In shallow lakes, macrophytes have important effects on food webs, community structure and nutrient dynamics. For this reason they play a significant role in the restoration of...     

Inhibition of the hydrosmotic response to antidiuretic hormone by 3,3'-diallyldiethylstilbestrol (DADES)

3,3'-diallyldiethylstilbestrol (DADES), a blocker of the facilitated diffusion of glucose, was found to interfere markedly with the hydrosmotic response to antidiuretic hormone and its related agonists. Frog urinary bladders were isolated and monitored for transmural net water flow. DADES was added either to the serosal or to the apical medium at concentrations ranging from 10(-4) M to 10(-6) M. Pretreatment for 30 min with apical 10(-4) M DADES drastically reduced the subsequent hydrosmotic response: (a) to oxytocin (4.4 x 10(-8) M) by 91.7 +/- 17.6% versus 6.2 +/- 7.8 in control; (b) to 8-bromo 3',5'-cyclic AMP by 93.5 +/- 19.4% versus 19.4 +/- 11.4%; (c) to serosal hyperosmolarity (mannitol 220 mOsm) by 99.3 +/- 0.5% versus 12.3 +/- 18.2%. This effect was dose-dependent. Inhibitory action of DADES was more effective on the apical side than on the serosal side (97.0 +/- 1.5 versus 45.8 +/- 10.8). Freeze-fracture studies revealed a modified distribution of the particles and unusual endocytotic pits and vesicles in the apical membrane of both granular and mitochondria-rich epithelial cells. These observations point to multiple and complex effects of the drug. Thus, it seems that DADES has numerous effects on urinary epithelium, which makes it a nonspecific inhibitor of water permeation. Conclusions on its use should therefore be drawn with suitable caution.