Identification and quantification of some elements in the hog roundworm, Ascaris lumbricoides suum, and certain tissues of its host

Atomic absorption spectrophotometric and fluorometric analyses were utilized for the determination of several elements in the whole bodies of both male and female Ascaris lumbricoides suum and from the muscle and kidney of the swine host. Concentrations of cadmium, calcium, copper, lead, magnesium, manganese, iron, selenium, potassium, and zinc in these tissues are reported. Statistical analysis (Tukey's procedure) of the data indicated no differences in metal concentrations between male and female ascarids. There were three instances in which the metal concentrations were statistically different in worm tissues and both hog tissues.     

Potential Use of Uniola paniculata Rhizome Fragments for Dune Restoration

Abstract Uniola paniculata (sea oats) rhizomes uprooted by hurricanes and deposited as wrack could be salvaged and replanted in dune restoration. To test this unexplored technique, percent tiller emergence was observed for 4 years from U. paniculata rhizomes replanted after submersion in seawater; air exposure of 0, 1, 3, 5, 7, and 11 days; freshwater rinse; and reburial in pots (watered) or on the beach (with or without supplemental water). In addition, U. paniculata rhizomes uprooted by Hurricane Georges were experimentally planted, and effects of soil salinity and moisture on emergence were tested in the greenhouse. Tiller emergence declined with increasing length of air exposure and decreasing size of rhizome. Tiller survival was enhanced by rainfall, rinsing with salt or fresh water during exposure and immediately after planting or supplemental beach watering. Although emergence was not reduced by soil salinity of 1,800 μS/cm, emergence was reduced by soil salinity of 5,800 μS/cm. Across the 4 years of the study tiller emergence from treated rhizomes varied considerably. U. paniculata rhizomes lost bud viability after 3–5 days of beach exposure, unless fresh water from rainfall, wet burlap storage, or watering was applied within 3 days. Bud viability was extended through 11 days when supplied with water. Thus, reburial within 3–11 days after a storm is a viable restoration technique.     

Pollination mechanisms in sixCampanula species (Campanulaceae)

Pollination mechanisms within the genusCampanula were studied. Tests were undertaken to examine whether in vitro culture of pollen grains can serve as a useful tool for understanding the self- and cross-pollination mechanisms among species. Characteristics of pollen germination were interpreted in relation to mating system and floral biology. Four annual species (Campanula kremeri, C. dichotoma, C. afra, C. lusitanica), and two perennial species (C. rotundifolia andC. persicifolia) were investigated. In the annual species pollen germinability is controlled by (1) the age of pollen and/or (2) in what position pollen is deposited around the style. Correlations were found between pollen germinability and mating system in three of the four annual species. No correlations were found either between germinability and age of pollen or position on the style in the perennial species. Pollen germinability reached its maximum in the middle of the male phase in all species, except forC. dichotoma, which had a decreasing germinability throughout anthesis. The germinability was lowest at the time of stigma receptivity for all species except forC. persicifolia, where the stigma did not develop as long as pollen remained on the style. The pollen collecting hairs and pollen removal have been found to play an important role controlling the stigma development, thus affecting self-pollination. This was especially pronounced inC. persicifolia. Further studies will be undertaken to elucidate factors influencing pollination within the genusCampanula.     

Regulatory Role of the GTP-Binding Protein, Go, in the Mechanism of Exocytosis in Adrenal Chromaffin Cells

To elucidate the possible involvement of GTP-binding proteins (G proteins) in the mechanism of exocytosis, we studied effects of pertussis toxin (PTX), guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S), and antibodies against the G proteins (Gi and G(o)) on the secretory function of bovine adrenal chromaffin cells. Pretreatment of chromaffin cells with PTX resulted in an increase in acetylcholine-evoked catecholamine release. High K(+)-, histamine-, or gamma-aminobutyric acid-evoked catecholamine release was also potentiated by PTX pretreatment. The concentration of extracellular Ca2+ required for maximal release by 10(-4) M acetylcholine was decreased significantly in PTX-treated cells. In digitonin-permeabilized cells, PTX pretreatment resulted in a decrease of the half-maximal concentration (Km) of Ca2+ required for exocytosis with no significant change in the maximal stimulation (Vmax). Exposure of permeabilized cells to GTP-gamma-S (a nonhydrolyzable GTP analogue) inhibited Ca(2+)-dependent exocytosis by reducing the affinity for Ca2+. The effects of PTX pretreatment were mimicked by treatment of permeabilized cells with polyclonal antibodies selective for the alpha subunit of the PTX-sensitive G protein, G(o). Treatment with similar antibodies against the alpha subunit of Gi had no effect. These findings suggest that G(o) directly controls the Ca(2+)-triggered process in the machinery of exocytosis by lowering the affinity of the unknown target for Ca2+.     

Effects of photoperiod,temperature, food and relative humidity on the induction of diapause in the predatory miteAmblyseius potentillae

Aspects of the induction of diapause were studied in a Dutch strain of the phytoseiid miteAmblyseius potentillae. The photoperiodic response curve was of the long-day type, with a sharply defined critical daylength of 14.5 h. Critical daylength varied only little at temperatures between 15.0 and 22.5°C.All post-embryonic and possibly even late-embryonic stages of development were found to be sensitive to photoperiod; sensitivity appeared to be maximal during the protonymphal stage.It is shown that -carotene is necessary for some early step in the physiological mechanism of photoperiodic induction, and not (or not exclusively) for the expression of the diapause response.Two points of sensitivity to light could be demonstrated in the nights ofld 1311 andld 1212 long-night regimes, using 1-h night interruptions. These results are similar to those obtained in lightbreak experiments with spider mites and insects. However, no effect was found with light interruptions applied during the dark phase of anld 1014 long-night regime.In resonance experiments with a constant photophase (12 h) and a variable scotophase, a weak rhythmic response was found at 22.5°C; at 19.0°C this effect was completely absent.The relative humidity experienced by the mites during diapause induction as well as during diapause development influenced the rate of diapause completion under long days (ld 168). Diapause duration appeared to be shortest when the mites experienced low relative humidity (35±5%) during diapause induction and high relative humidity (75±5%) during diapause termination, and longest under the reverse conditions.     

Spindel und kinetochoren in der Mitose und Meiose der Baumwollwanze Dysdercus intermedius (Heteroptera)

In spermatogonial mitoses of Dysdercus intermedius, chromosomal spindle microtubules insert in discrete kinetochores. The latter consist of two electron dense plates of about 0,3 m diameter located at opposite sites at the poleward surfaces of the daughter chromatids. The evidence presented permits the interpretation that a localized kinetochore owes its layered substructure to successive binding sites for kinetochore material at the ends of bundled microtubules. A working hypothesis, based upon different distributions of genetic loci for kinetochore material in species with localized and diffuse kinetochores is proposed. In Dysdercus, holokinetic chromosome behavior in mitotic anaphase movement is not due to truly diffuse kinetochores but to chromosomal interconnections which are established at prometaphase. Such interconnections are absent in the first meiotic division when each bivalent is enclosed by a sheath of endoplasmic reticulum. Spindle microtubules penetrate through terminal openings in this sheath and end singly in dense spots of kinetochore material.     

Surface antigens of Paramecium primaurelia : Membrane-bound and soluble forms

The surface antigens of Paramecium constitute a family of high molecular weight (ca 300 kD) iso-proteins whose alternative expression, adjusted to environmental conditions, involves both intergenic and interallelic exclusion. Since the surface antigen molecules had previously been shown to play a key role in the control of their own expression, it seemed important to compare the structural particularities of different surface antigens: the G and D antigens of P. primaurelia expressed at different temperatures, and which are coded by two unlinked loci. Here we demonstrate that in all cases a given surface antigen presents two biochemically distinct basic forms: a soluble form recovered from ethanolic extraction of whole cells, and a membrane-bound form recovered from ciliary membranes solubilized by detergent. The membrane-bound form differs from the soluble one by its mobility on SDS gels and by an electrophoretic mobility shift in the presence of anionic or cationic detergents. Furthermore, two 40-45 kD polypeptides sharing common determinants with soluble antigens were found exclusively in ethanolic extracts but not in ciliary membranes: the cross-reactivity of these light polypeptides with ethanol-extracted antigens could be demonstrated only after beta-mercaptoethanol treatment. Immunological comparisons between allelic and non-allelic soluble antigens demonstrate that allelic antigens share a great number of surface epitopes, most of which are not accessible in vivo, while non-allelic antigens appear to share essentially sequence-antigenic determinants. The significance of these results is discussed in relation to the mechanism of antigenic variation.     

Interaction of cholesterol,phospholipid and apoprotein in high density lipoprotein recombinants

To examine the effect of incorporation of cholesterol into high density lipoprotein (HDL) recombinants, multilamellar liposomes of ³H cholesterol/¹⁴C dimyristoyl phosphatidylcholine were incubated with the total apoprotein (apoHDL) and principal apoproteins (apoA-1 and apoA-2) of human plasma high density lipoprotein. Soluble recombinants were separated from unreacted liposomes by centrifugation and examined by differential scanning calorimetry and negative stain electron microscopy. At 27°C, liposomes containing up to approx. 0.1 mol cholesterol/mol dimyristoyl phosphatidylcholine (DMPC) were readily solubilized by apoHDL, apoA-1 or apoA-2. However, the incorporation of DMPC and apoprotein into lipoprotein complexes was markedly reduced when liposomes containing a higher proportion of cholesterol were used. For recombinants prepared from apoHDL, apoA-1 or apoA-2, the equilibrium cholesterol content of complexes was approx. 45% that of the unreacted liposomes. Electron microscopy showed that for all cholesterol concentrations, HDL recombinants were predominantly lipid bilayer discs, approx. $\text{160 × 55}\text{A}\text{?}$. Differential scanning calorimetry of cholesterol containing recombinants of DMPC/cholesterol/apoHDL or DMPC/cholesterol/apoA-1 showed, with increasing cholesterol content, a linear decrease in the enthalpy of the DMPC gel to liquid crystalline transition, extrapolating to zero enthalpy at 0.15 cholesterol/DMPC. The enthalpy values were markedly reduced compared to control liposomes, where the phospholipid transition extrapolated to zero enthalpy at approx. 0.45 cholesterol/DMPC. The calorimetric and solubility studies suggest that in high density lipoprotein recombinants cholesterol is excluded from 55% of DMPC molecules bound in a non-melting state by apoprotein.     

Absolute configuration of the benzofuranoid neolignans

The benzofuranoid neolignans, classified into structurally homogeneous groups by constitution and ORD curves, have had their relative configurations es