Fleeting Identities: Perishable Material Culture in Archaeological Research

Fleeting Identities: Perishable Material Culture in Archaeological Research. Penelope Ballard Drooker. ed. Carbondale, 1L: Center for Archaeological Investigations, 2001.410 pp.     

Cardiovascular dynamics inCrocodylus porosus breathing air and during voluntary aerobic dives

Summary Pressure records from the heart and out-flow vessels of the heart ofCrocodylus porosus resolve previously conflicting results, showing that left aortic filling via the foramen of Panizza may occur during both cardiac diastole and systole. Filling of the left aorta during diastole, identified by the asynchrony and comparative shape of pressure events in the left and right aortae, is reconciled more easily with the anatomy, which suggests that the foramen would be occluded by opening of the pocket valves at the base of the right aorta during systole. Filling during systole, indicated when pressure traces in the left and right aortae could be superimposed, was associated with lower systemic pressures, which may occur at the end of a voluntary aerobic dive or can be induced by lowering water temperature or during a long forced dive. To explain this flexibility, we propose that the foramen of Panizza is of variable calibre. The presence of a right-left shunt, in which increased right ventricular pressure leads to blood being diverted from the lungs and exiting the right ventricle via the left aorta, was found to be a frequent though not obligate correlate of voluntary aerobic dives. This contrasts with the previous concept of the shunt as a correlate of diving bradycardia. The magnitude of the shunt is difficult to assess but is likely to be relatively small. This information has allowed some new insights into the functional significance of the complex anatomy of the crocodilian heart and major blood vessels.Abbreviations bpm beats per minute - LAo left aorta (aortic) - LV left ventricle (ventricular) - PA pulmonary artery - RAo right aorta (aortic) - RV right ventricle (ventricular) - SC subclavian artery Deceased     

Investigations on circumferential microfilament bundles in rat retinal pigment epithelium

The presence of contractile proteins in normal rat retinal pigment epithelium has been studied using fluorescence and electron microscopy. Investigations using the F-actin binding toxin, phallacidin, coupled to the fluorochrome nitrobenzoxadiazole, revealed a band of fluorescence at or near the cell membrane. Immunofluorescent observations with anti-myosin and anti-alpha-actinin antisera gave similar results. Electron microscopy employing glutaraldehyde-8% tannic acid fixation revealed the presence of a circumferential microfilament band beneath the pigment epithelial apical surface that is closely associated with the plasma membrane and junctional complexes. Freeze-fracture studies confirmed the relationship of this band to the junctional complexes. The microfilament band measures approximately 0.5 micron +/- 0.2 micron in width and is composed of numerous 6 to 7 nm filaments. Some microtubules are seen in regions around the band, but no organelles appear to be associated with this structure. In en face sections through the zonula adherens, the circumferential microfilament band is associated with 30-nm electron-dense particles that are bound to the internal side of the membrane. Morphological evidence suggests that these may serve in anchoring the band to the membrane and assist in aligning the microfilament bands of adjoining cells. In the subapical cytoplasm, a microfilament bundle network was detected that interfaced with the circumferential microfilament band. In some cases, pigment epithelium was incubated in media-199 containing 25 to 50 ng/ml phallacidin prior to fixation. Circumferential microfilament bands of tissues treated in this manner exhibited a striated appearance.     

Photoproduction of amino acids by mutant strains of N2-fixing cyanobacteria

Summary Mutant strains of the N₂-fixing cyanobacterium bacterium Anabaena variabilis resistant to 6-fluorotryptophan or to ethionine were isolated. Many of these strains liberated amino acids into their media in the absence of 6-fluorotryptophan and ethionine. Nitrogenase activity was higher in mutant strains than in the parent strain. Mutant strains were immobilised in calcium alginate and sustained photoproduction of amino acids has been demonstrated.Abbreviations ETH ethionine - FT 6-fluorotryptophan - Hepes 4-(2-hydroxyethyl)-1, piperazine ethanesulphonic acid - PEP phosphoenolpyruvate - DAHP 3-deoxy-d-arabinoheptulosonate 7-phosphate - chl a chlorophyll a     

Environmental factors influencing the occurrence of juvenile fish in the mangroves of Pagbilao,Philippines

128 fish species belonging to 54 families were collected from the mangroves of Pagbilao. Ambassis kopsi (Ambassidae) was the most abundant species.Fourteen environmental factors were correlated to the catch per unit time for some species. The occurrence of A. kopsi was positively correlated to nitrate in the water, carbon in the sediments and litter fall. Out of the 8 species investigated, 6 were positively correlated to litter fall. Three species showed positive correlation to phosphate in the water, two to organic carbon in the sediments, nitrate, silicate and pH, and one to salinity and carotenoids in water. The biomass of the total catch was correlated to carbon in the sediments and litter fall.     

Overexpression of the dnaA gene in Escherichia coli B/r: chromosome and minichromosome replication in the presence of rifampin.

The replication of chromosomes and minichromosomes in Escherichia coli B/r was examined under conditions in which the dnaA gene product was overproduced. Increased levels of the DnaA protein were achieved by thermoinduction of the dnaA gene, under the control of the lambda pL promoter, or by cellular maintenance of multicopy plasmids carrying the dnaA gene under the control of its own promoters. Previous work has shown that overproduction of DnaA protein stimulates replication of the chromosomal origin, oriC, but that the newly initiated forks do not progress along the length of the chromosome (T. Atlung, K. V. Rasmussen, E. Clausen, and F. G. Hansen, p. 282-297, in M. Schaechter, F. C. Neidhardt, J. L. Ingraham, and N. O. Kjeldgaard, ed., The Molecular Biology of Bacterial Growth, 1985). In the present study, it was found that overproduction of DnaA protein caused both a two- to threefold increase in the amount of residual chromosome replication and an extended synthesis of minichromosome DNA in the presence of rifampin. The amount of residual chromosome replication was consistent with the appearance of functional replication forks on the majority of the chromosomes. Since the rate of DNA accumulation and the cellular DNA/mass ratios were not increased significantly by overexpression of the dnaA gene, we concluded that the addition of rifampin either enabled stalled replication forks to proceed beyond oriC or enabled new forks to initiate on both chromosomes and minichromosomes, or both.     

Comparison of the tissue-specific expression and developmental regulation of two closely linked rodent genes encoding cytosolic retinol-binding proteins

Cellular retinol-binding protein (CRBP) and cellular retinol-binding protein II (CRBP II) are two highly homologous cytoplasmic proteins that bind all-trans-retinol. We have recently demonstrated that the mouse genes encoding CRBP and CRBP II are closely linked on chromosome 9 and that both human genes are located on chromosome 3 (Demmer, L.A., Birkenmeier, E.H., Sweetser, D.A., Levin, M.S., Zollman, S., Sparkes, R.S., Mohandas, T., Lusis, A.J., and Gordon, J.I. (1987) J. Biol. Chem. 262, 2458-2467). We have now used RNA blot hybridization analysis to assess the degree to which these genes are coordinately expressed in fetal, suckling, weaning, and adult rat tissues. Both genes exhibit different developmental patterns of expression in liver, intestine, lung, kidney, testes, and placenta. In the intestine, CRBP mRNA was detected during the 16th day of gestation--prior to the development of a well-differentiated absorptive epithelium--and remained essentially unchanged throughout the peri- and postpartum periods. By contrast, the pattern of intestinal CRBP II mRNA accumulation closely parallels the times of first appearance, and subsequent proliferation, of the intestinal absorptive columnar epithelium, supporting the hypothesis that CRBP II is involved in the intestinal uptake or intracellular trafficking of this hydrophobic vitamin. In the fetal liver, both genes were expressed by gestational day 16. Whereas the concentration of hepatic CRBP mRNA increased markedly during the suckling and early weaning periods, CRBP II mRNA levels fell abruptly immediately after birth. These peripartum changes were not paralleled by remarkable alterations in the steady state levels of hepatic retinol. Marked changes in the expression of CRBP in the liver and of CRBP II in the intestine were also documented in pregnant and lactating female rats. These differences in CRBP/CRBP II gene expression strongly suggest that their proteins serve different physiological functions. The peripartum liver may provide a useful model for dissecting the relative roles played by these homologous proteins in retinoid metabolism as well as the factors which modulate activation and repression their genes.     

Biochemical characterization of hepatic microsomal leukotriene B4 hydroxylases

omega-Hydroxylation of leukotriene B4 (LTB4) has been reported in human and rodent polymorphonuclear leukocytes; preliminary information indicates that this metabolism is cytochrome P-450 dependent. Therefore, these studies were initiated to characterize the cytochrome P-450-dependent metabolism of LTB4 in other tissues. LTB4 was metabolized by rat hepatic microsomes to two products, 20-hydroxy(omega)-LTB4 and 19-hydroxy(omega-1)-LTB4. The formation of these metabolites was both oxygen and NADPH dependent indicating that a monooxygenase(s) was responsible for these reactions. The apparent Km and Vmax for LTB4 omega-hydroxylase were 40.28 microM and 1202 pmol/min/mg of protein, respectively. In contrast, the apparent Km and Vmax for LTB4 (omega-1)-hydroxylase were 61.52 microM and 73.50 pmol/min/mg of protein, respectively. Both LTB4 omega- and (omega-1)-hydroxylases were inhibited by metyrapone in a concentration-dependent fashion. However, SK&F 525A inhibited LTB4 (omega-1)- but not omega-hydroxylase. In contrast, alpha-naphthoflavone decreased LTB4 omega- but not (omega-1)-hydroxylase activities. The differences in the Km apparent for substrate as well as the differential inhibition by inhibitors of cytochrome P-450 suggest that the omega- and (omega-1)-hydroxylations of LTB4 in hepatic microsomes are mediated by different isozymes of P-450. Furthermore, several additional characteristics of LTB4 hydroxylases indicate that these isozymes of P-450 may be different from those which catalyze similar reactions on medium-chain fatty acids, such as laurate and prostaglandins.