A member of the OSCA/TMEM63 family of mechanosensitive calcium channels participates in cell wall integrity maintenance in Aspergillus nidulans

The calF7 mutation in Aspergillus nidulans causes hypersensitivity to the cell wall compromising agents Calcofluor White (CFW) and Congo Red. In this research we demonstrate that the calF7 mutation resides in gene AN2880, encoding a predicted member of the OSCA/TMEM63 family of transmembrane glycoproteins. Those members of the family whose physiological functions have been investigated have been shown to act as mechanosensitive calcium transport channels. Deletion of AN2880 replicates the CFW hypersensitivity phenotype. Separately, we show that CFW hypersensitivity of calF deletion strains can be overcome by inclusion of elevated levels of extracellular calcium ions in the growth medium, and, correspondingly, wild type strains grown in media deficient in calcium ions are no longer resistant to CFW. These observations support a model in which accommodation to at least some forms of cell wall stress is mediated by a calcium ion signaling system in which the AN2880 gene product plays a role. The genetic lesion in calF7 is predicted to result in a glycine-to-arginine substitution at position 638 of the 945-residue CalF protein in a region of the RSN1_7TM domain that is highly conserved amongst filamentous fungi. Homology modeling predicts that the consequence of a G638R substitution is to structurally occlude the principal conductance pore in the protein. GFP-tagged wild type CalF localizes principally to the Spitzenkörper and the plasma membrane at growing tips and forming septa. However, both septation and hyphal morphology appear to be normal in calF7 and AN2880 deletion strains, indicating that any role played by CalF in normal hyphal growth and cytokinesis is dispensable.

The Aspergillus nidulans IQGAP orthologue SepG is required for constriction of the contractile actomyosin ring

In this research we report that the sepG1 mutation in Aspergillus nidulans resides in gene AN9463, which is predicted to encode an IQGAP orthologue. The genetic lesion is predicted to result in a G-to-R substitution at residue 1637 of the 1737-residue protein in a highly conserved region of the RasGAP-C-terminal (RGCT) domain. When grown at restrictive temperature, strains expressing the sepG^G1637R (sepG1) allele are aseptate, with reduced colony growth and aberrantly formed conidiophores. The aseptate condition can be replicated by deletion of AN9463 or by downregulating its expression via introduced promoters. The mutation does not prevent assembly of a cortical contractile actomyosin ring (CAR) at putative septation sites, but tight compaction of the rings is impaired and the rings fail to constrict. Both GFP::SepG wild type and the GFP-tagged product of the sepG1 allele localize to the CAR at both permissive and restrictive temperatures. Downregulation of myoB (encoding the A. nidulans type-II myosin heavy chain) does not prevent formation of SepG rings at septation sites, but filamentous actin is required for CAR localization of SepG and MyoB. We identify fourteen probable IQ-motifs (EF-hand protein binding sites) in the predicted SepG sequence. Two of the A. nidulans EF-hand proteins, myosin essential light chain (AnCdc4) and myosin regulatory light chain (MrlC), colocalize with SepG and MyoB at all stages of CAR formation and constriction. However, calmodulin (CamA) appears at septation sites only after the CAR has become fully compacted. When expression of sepG is downregulated, leaving MyoB as the sole IQ-motif protein in the pre-compaction CAR, both MrlC and AnCdc4 continue to associate with the forming CAR. When myoB expression is downregulated, leaving SepG as the sole IQ-motif protein in the CAR, AnCdc4 association with the forming CAR continues but MrlC fails to associate. This supports a model in which the IQ motifs of MyoB bind both MrlC and AnCdc4, while the IQ motifs of SepG bind only AnCdc4. Downregulation of either mrlC or Ancdc4 results in an aseptate phenotype, but has no effect on association of either SepG or MyoB with the CAR.

Aspergillus nidulans protein kinase C forms a complex with the formin SepA that is involved in apical growth and septation

The Aspergillus nidulans orthologue of Protein kinase C (PkcA) and the A. nidulans formin SepA participate in polarized growth. PkcA localizes to growing hyphal apices and septation sites, and amino acid sequences within PkcA that are required for PkcA to localize to these sites of cell wall synthesis have been identified. SepA is associated with the contractile actomyosin ring (CAR), and it localizes at hyphal tips in association with the Spitzenkörper (SPK) and as an apical dome. A mutation in the sepA gene (sepA1) renders A. nidulans aseptate at elevated temperature. Progress towards understanding the spatiotemporal relationship between PkcA and SepA during polarized growth is presented here. Fluorescent chimeras of PkcA and SepA strongly overlapped in some hyphal tips in a dome pattern, while other tips displayed SepA SPK and PkcA dome localization within the same tip. At septation sites PkcA and SepA consistently colocalized through late stages of CAR constriction. Bimolecular fluorescence complementation experimental results provide evidence that SepA and PkcA are both present in complexes at both hyphal tip domes and at cortical rings. A Gal4-based yeast two-hybrid analysis confirmed the physical interaction between SepA and PkcA, and indicted that the FH2 domain of SepA is involved in its physical interaction with PkcA. A functional interaction between PkcA and SepA was shown through complementation of the pkcA calC2 mutant's hypersensitivity to cell wall perturbing agents by overexpressed sepA and by the ability of the sepA1 mutation to block PkcA's ability to form cortical rings. Taken together these results suggest that a PkcA/SepA complex is involved in polarized growth. Through experiments using the actin disrupter latrunculin B, evidence is presented suggesting that actin plays a role in the PkcA/SepA complex.

Two amino acid sequences direct Aspergillus nidulans protein kinase C (PkcA) localization to hyphal apices and septation sites

The Aspergillus nidulans ortholog of protein kinase C (pkcA) is involved in the organism's putative cell wall integrity (CWI) pathway, and PkcA also is highly localized at growing tips and forming septa. In the present work we identify the regions within PkcA that are responsible for its localization to hyphal tips and septation sites. To this end, we used serially truncated pkcA constructs and expressed them as green fluorescent protein (GFP) chimeras and identified two regions that direct PkcA localization. The first region is a 10 amino-acid sequence near the carboxyl end of the C2 domain that is required for localization to hyphal tips. Proteins containing this sequence also localize to septation sites. A second region between C2 and C1B (encompassing C1A) is sufficient for localization to septation sites but not to hyphal tips. We also report that localization to hyphal tips and septation sites alone is not sufficient for truncated constructs to complement hypersensitivity to the cell wall compromising agent calcofluor white in a strain bearing a mutation in the pkcA gene. Taken together, these results suggest that localization and stress response might be independent.

A mutation in the converter subdomain of Aspergillus nidulans MyoB blocks constriction of the actomyosin ring in cytokinesis

We have identified a mutant allele of the Aspergillus nidulans homologue of myosin II (myoB; AN4706), which prevents normal septum formation. This is the first reported myosin II mutation in a filamentous fungus. Strains expressing the myoB(G843D) allele produce mainly aberrant septa at 30 °C and are completely aseptate at temperatures above 37 °C. Conidium formation is greatly reduced at 30 °C and progressively impaired with increasing temperature. Sequencing of the myoB(G843D) allele identified a point mutation predicted to result in a glycine-to-aspartate amino acid substitution at residue 843 in the myosin II converter domain. This residue is conserved in all fungal, plant, and animal myosin sequences that we have examined. The mutation does not prevent localization of the myoB(G843D) gene product to contractile rings, but it does block ring constriction. MyoB(G843D) rings at sites of abortive septation disassemble after an extended period and dissipate into the cytoplasm. During contractile ring formation, both wild type and mutant MyoB::GFP colocalize with actin--an association that begins at the pre-ring "string" stage. Down-regulation of wild-type myoB expression under control of the alcA promoter blocks septation but does not prevent actin from aggregating at putative septation sites--the actin rings, however, do not fully coalesce. Both septation and targeting of MyoB are blocked by disruption of filamentous actin using latrunculin B. We propose a model in which myosin assembly at septation sites depends upon the presence of F-actin, but assembly of the actin component of contractile rings depends upon normal levels of myosin only for the final stages of ring compaction.

Mutations in proteins of the Conserved Oligomeric Golgi Complex affect polarity, cell wall structure, and glycosylation in the filamentous fungus Aspergillus nidulans

We have described two Aspergillus nidulans gene mutations, designated podB1 (polarity defective) and swoP1 (swollen cell), which cause temperature-sensitive defects during polarization. Mutant strains also displayed unevenness and abnormal thickness of cell walls. Un-polarized or poorly-polarized mutant cells were capable of establishing normal polarity after a shift to a permissive temperature, and mutant hyphae shifted from permissive to restrictive temperature show wall and polarity abnormalities in subsequent growth. The mutated genes (podB=AN8226.3; swoP=AN7462.3) were identified as homologues of COG2 and COG4, respectively, each predicted to encode a subunit of the multi-protein COG (Conserved Oligomeric Golgi) Complex involved in retrograde vesicle trafficking in the Golgi apparatus. Down-regulation of COG2 or COG4 resulted in abnormal polarization and cell wall staining. The GFP-tagged COG2 and COG4 homologues displayed punctate, Golgi-like localization. Lectin-blotting indicated that protein glycosylation was altered in the mutant strains compared to the wild type. A multicopy expression experiment showed evidence for functional interactions between the homologues COG2 and COG4 as well as between COG2 and COG3. To date, this work is the first regarding a functional role of the COG proteins in the development of a filamentous fungus.

Two GDP-mannose transporters contribute to hyphal form and cell wall integrity in Aspergillus nidulans

In order to identify novel genes affecting cell wall integrity, we have generated mutant strains of the filamentous fungus Aspergillus nidulans that show hypersensitivity to the chitin-binding agent Calcofluor White (CFW). Affected loci are designated cal loci. The phenotype of one of these alleles, calI11, also includes shortened hyphal compartments and increased density of branching in the absence of CFW, as well as reduced staining of cell walls by the lectin FITC-Concanavalin A (ConA), which has strong binding affinity for mannosyl residues. We have identified two A. nidulans genes (AN8848.3 and AN9298.3, designated gmtA and gmtB, respectively) that complement all aspects of the phenotype. Both genes show strong sequence similarity to GDP-mannose transporters (GMTs) of Saccharomyces and other yeasts. Sequencing of gmtA from the calI11 mutant strain reveals a G to C mutation at position 943, resulting in a predicted alanine to proline substitution at amino acid position 315 within a region that is highly conserved among other fungi. No mutations were observed in the mutant strain's allele of gmtB. Meiotic mapping demonstrated a recombination frequency of under 1 % between the calI locus and the phenA locus (located approximately 9.5 kb from AN8848.3), confirming that gmtA and calI are identical. A GmtA-GFP chimera exhibits a punctate distribution pattern, consistent with that shown by putative Golgi markers in A. nidulans. However, this distribution did not overlap with that of the putative Golgi equivalent marker CopA-monomeric red fluorescent protein (mRFP), which may indicate that the physically separated Golgi-equivalent organelles of A. nidulans represent physiologically distinct counterparts of the stacked cisternae of plants and animals. These findings demonstrate that gmtA and gmtB play roles in cell wall metabolism in A. nidulans similar to those previously reported for GMTs in yeasts.

The protein kinase C orthologue PkcA plays a role in cell wall integrity and polarized growth in Aspergillus nidulans

The calC2 mutation in Aspergillus nidulans causes hypersensitivity to Calcofluor White, along with other drug sensitivities that indicate a defect in cell wall integrity. We have cloned CalC by complementation, isolating the A. nidulans orthologue of protein kinase C (PkcA). The pkcA allele of the calC2 strain contains a mutation predicted to introduce a charged arginine residue in place of neutral glycine at a conserved site located immediately beside the C1B regulatory domain. Both PkcA and calC2 map to the same region of chromosome VIII. A PkcA::GFP chimera localizes to hyphal apices and growing septa, as well as to the conidiogenous apices of phialides, indicating a role for PkcA in polarized cell wall growth. These observations support the hypothesis that the role of PkcA in A. nidulans, is comparable to that played by Pkc1p in the Saccharomyces cerevisiae cell wall integrity pathway.

Isolation of cell wall mutants in Aspergillus nidulans by screening for hypersensitivity to Calcofluor White

As a first step toward identifying novel genes of wall metabolism in filamentous fungi, we have screened a collection of Aspergillus nidulans mutants for strains exhibiting hypersensitivity toward the chitin binding agent Calcofluor White (CFW). This strategy has been used previously to identify cell wall mutants in Saccharomyces cerevisiae. We have identified 10 mutants representing eight loci, designated calA through calH, for Calcofluor hypersensitivity. All cal mutants are impaired for sporulation at 30 C or 42 C or both, and in eight of the 10 mutations this sporulation defect shows at least partial osmotic remediability. All cal mutants show elevated sensitivity to one or more of the following agents: Caspofungin, Nikkomycin, Tunicamycin, Congo red and SDS, which are recognized wall-compromising agents or have been shown to be inhibitory to wall integrity mutants in yeast. Seven of the 10 cal mutants show swelling at elevated temperature, which in most cases is osmotically remediable. Spore swelling also can be induced at 30 C in all but one of the cal mutants by germination in the presence of one or more of the following: Caspofungin, Nikkomycin or Tunicamycin. Analysis of wall sugars showed no major changes in mutant strains. We also report that the chitin synthase inhibitor Nikkomycin induces excessive spore swelling during germination in all tested strains that have wild type cell wall metabolism (GR5, A4, A28 and AH12) at 42 C but not at 30 C. This effect mimics that of certain temperature-sensitive swollen cell (swo) mutations.

The Interaction of the Atmosphere of Enceladus with Saturn's Plasma

During the 14 July 2005 encounter of Cassini with Enceladus, the Cassini Plasma Spectrometer measured strong deflections in the corotating ion flow, commencing at least 27 Enceladus radii (27 x 252.1 kilometers) from Enceladus. The Cassini Radio and Plasma Wave Science instrument inferred little plasma density increase near Enceladus. These data are consistent with ion formation via charge exchange and pickup by Saturn's magnetic field. The charge exchange occurs between neutrals in the Enceladus atmosphere and corotating ions in Saturn's inner magnetosphere. Pickup ions are observed near Enceladus, and a total mass loading rate of about 100 kilograms per second (3 x 10(27) H(2)O molecules per second) is inferred.

Composition and Dynamics of Plasma in Saturn's Magnetosphere

During Cassini's initial orbit, we observed a dynamic magnetosphere composed primarily of a complex mixture of water-derived atomic and molecular ions. We have identified four distinct regions characterized by differences in both bulk plasma properties and ion composition. Protons are the dominant species outside about 9 RS (where RS is the radial distance from the center of Saturn), whereas inside, the plasma consists primarily of a corotating comet-like mix of water-derived ions with approximately 3% N+. Over the A and B rings, we found an ionosphere in which O2+ and O+ are dominant, which suggests the possible existence of a layer of O2 gas similar to the atmospheres of Europa and Ganymede.

The Aspergillus fumigatus cell wall is organized in domains that are remodelled during polarity establishment

Aspergillus fumigatus is a life-threatening and increasingly frequent pathogen of the immunocompromised. Like other filamentous fungi A. fumigatus grows in a highly polar manner, adding new cell wall to the apical region of hyphae. mAbs were raised against isolated A. fumigatus cell walls. Fifteen antibodies bound reproducibly to isolated cell walls in ELISAs and to the walls of intact cells in immunofluorescence experiments. Surprisingly, individual mAbs showed distinct patterns of localization. Six antibodies labelled exclusively conidial or basal regions, seven labelled apical regions and a single antibody labelled both basal and apical regions of hyphae. Ten antibodies did not label the walls adjacent to septa. In double labelling experiments with representative mAbs there was little or no overlap between epitopes recognized. These labelling patterns suggest that the wall is made up of basal and apical domains that differ in composition or organization and that the wall region flanking septa differs from other regions of the lateral wall. In time-course experiments of early A. fumigatus growth, mAb16C4 failed to label isotropically expanding cells and labelled emerging germ tubes and branches. The same mAb failed to label the Aspergillus nidulans swoC mutant, which is defective in polarity establishment. However, mAb16C4 did label the A. nidulans swoA mutant, which completes polarity establishment, but is defective in polarity maintenance. Thus, mAb16C4 appears to recognize a cell wall change that occurs during polarity establishment. In immunogold labelling and transmission electron microscopy (TEM) experiments, conidia, basal regions and apical regions of thin-sectioned cells labelled with mAb16C4. That only apical regions labelled in intact cells (immunofluorescence) while conidial, basal and apical regions labelled in thin-sectioned cells (TEM) suggests that the 16C4 epitope is present along the whole hypha, but is masked everywhere except the tip until polarity establishment. That is to say, some remodelling of the wall during polarity establishment exposes the 16C4 epitope. The 16C4 epitope was partially purified from A. fumigatus total protein by passage through hydrophobic interaction and anion-exchange columns. The resulting single ELISA-positive fraction showed relatively few bands by SDS-PAGE and silver staining and a strong band by Western blotting with the16C4 mAb. Sequencing of the fraction yielded a predicted peptide with a 6-amino acid exact match to a region of the Cat1 protein previously identified as an immunodominant A. fumigatus catalase that localizes to the cell wall and is secreted to the medium. Experiments are under way to determine if mAb16C4 recognizes Cat1 or another protein that co-purifies with Cat1.

Isolation and characterization of an endo-(1,4)-{beta}-glucanase secreted by Achlya ambisexualis

Models of wall loosening in fungi and other walled eukaryotes require the action of proteins able to reduce the degree of linkage between components of the wall. In the oomycete Achlya ambisexualis, such a role has been proposed for a suite of endoglucanases that are secreted during branching and during the measurable wall softening associated with osmotic stress. We report here the isolation and characterization of one of these isoenzymes. The enzyme has a molecular weight of 32 kDa, a pH optimum of 6.75, a pI of 4.5, and a temperature optimum of 35 C. It is partially inhibited by sulfhydryl-binding reagents and completely inhibited by the tryptophan-binding reagent NBS. The enzyme has an endohydrolytic mode of action with substrate specificity towards glucans that contain β-(1,4) linkages, either alone (carboxymethyl cellulose) or as mixed linkage (1,4-1,3)-β-glucans (e.g., Avena glucan). It does not, however, degrade amorphous insoluble (phosphoric acid swollen) cellulose. Most significantly, the enzyme can also hydrolyze linkages in an Achlya cell wall fraction previously shown to consist of a mixed-linkage (1,4-1,3)-β-glucan. This property is consistent with the long-standing hypothesis that the branching-related endoglucanases of oomycetes play a role in cell wall loosening.

Proteolytic release of membrane-bound endo-(1,4)-beta-glucanase activity associated with cell wall softening in Achlya ambisexualis

Branching and other cell wall softening events in fungi and oomycetes are thought to involve the activity of secreted enzymes, which are packaged in membrane vesicles and delivered to sites of cell expansion, there to work in a carefully regulated manner upon the structure of the wall. Here we demonstrate a latent endo-(1,4)-beta-glucanase activity in a mixed membrane fraction of the oomycete Achlya ambisexualis, which can be released by cysteine proteases with an increase of apparent activity. In addition, a similar endogenous process is strongly inhibited by the cysteine protease inhibitor iodoacetamide, while inhibitors of other types of proteases have a much smaller effect. Detergent treatment of membranes releases two glucanases detectable by electrophoretic activity staining, with apparent molecular masses of about 164 and 35 kDa. Proteolysis produces several activity bands, with major species having apparent molecular masses of about 149, 133, 48, 35, and 25 kDa. The ca. 35- and 25-kDa bands migrate in parallel with glucanases secreted during wall softening in vivo. We propose that the initiation of wall softening in Achlya involves the proteolytic processing and solubilization of at least some secreted endoglucanases. We also propose that the solubilization component of this process functions not just to provide the enzymes with access to wall matrix substrates but also may provide a mechanism for the eventual termination of their biological function.

Molecular characterization and influence on fungal development of ALP2, a novel serine proteinase from Aspergillus fumigatus

A novel subtilisin-related serine proteinase (ALP2) [EC 3.4.21.48] with a broad range of activity between pH 4.5 and 11.0 was released from a cell wall fraction of Aspergillus fumigatus by an alkaline pH shift. The enzyme which was not detected in the culture supernatant was partially purified by phenylbutylamine agarose chromatography. The N-terminal sequence revealed that ALP2 is the same protein identified as the major allergen of A. fumigatus in patients suffering from extrinsic bronchial asthma (Shen et al. 1999, Int. Arch. Allergy Immunol. 119, 259-264). Based on this N-terminal sequence and on a conserved region of fungal subtilisins, a specific PCR probe was generated and the ALP2 genomic and cDNA were isolated from corresponding phage libraries. ALP2 shares a 49% identity with the vacuolar proteinase B (PrB) of Saccharomyces cerevisiae. In addition there is a 78% identity with PEPC, a serine proteinase which has been described in Aspergillus niger. Targeted disruption of the ALP2-encoding gene resulted in a slightly decreased speed of vegetative growth and in a more than 80% reduction of sporulation in the alp2-negative mutants, correlated with an approximately 50% reduction of the median diameter of conidiophore vesicles. The requirement of ALP2 for regular sporulation, in addition to its role in allergic asthma, raises further interest in cellular proteinases in respect to morphogenesis and pathogenesis in A. fumigatus.

Regulation of extracellular proteases in Achlya ambisexualis

The use of proteins as a nutrient source by Achlya ambisexualis was investigated, using media containing defined and undefined sources of carbon, nitrogen, and (or) sulfur. Release of extracellular proteases occurred during growth on all proteins and protein hydrolysates tested, but not during growth on yeast extract or in defined medium. In gelatin-containing media, three major bands of extracellular protease activity were detected by electrophoresis, with estimated molecular mass of 26, 48, and 58 kDa. Growth on gelatin was stimulated to a much greater degree by the addition of glucose to the medium than by additions of glutamic acid or methionine. This and the release of ammonia during growth indicate that gelatin is less effective in meeting metabolic needs for carbon than it is in meeting the needs for nitrogen and sulfur. Protease secretion is only partially regulated by glucose, whereas glucose, methionine, and glutamic acid in combination cause almost complete repression. The pattern of regulation indicated by these results is most consistent with one of induction + derepression. Key words: oomycetes, proteinases, regulation, secreted enzymes.

Electrophoretic characterization of endo-(1,4)-β-glucanases secreted during assimilative growth and antheridiol-induced branching inAchlya ambisexualis

Secreted endo-(1,4)-β-glucanases ("cellulases") of Achlya ambisexualis were analyzed by a technique that permits visualization of enzyme activity in situ after electrophoresis in gels containing sodium dodecyl sulfate. Catalytic polypeptides with molecular masses of about 97, 74, 36, 29, and 25 kDa were observed in media from young cultures, though progressively fewer bands were observed as cultures aged. Based on size estimations of native enzymes with gel exclusion chromatography, the 97- and 36-kDa polypeptides were concluded to be subunits of a 245-kDa holoenzyme and the 25-kDa polypeptides were concluded to be subunits of a second holoenzyme of about 92 kDa. The data were insufficient to allow similar assignments for the more ephemeral 74- and 29-kDa polypeptides. The endoglucanases secreted during branch induction by antheridiol or 0.2% peptone comigrated in electrophoretic gels with enzymes secreted during normal assimilative growth. No endoglucanases specific to induced branching were observed.Key words: oomycetes, cell walls, endoglucanases, cellulases, antheridiol.

Orthotic effect on metatarsophalangeal joint extension. A preliminary study

The authors evaluated the effect of modified Root orthoses on first metatarsophalangeal joint extension. Motion within the joint was measured dynamically following the insertion of bone markers into the first metatarsal and the hallux. Extension at the joint was greatest when the subjects were barefoot, the mean angle being 62 degrees. Plimsolls restricted extension of the joint to a mean angle of 57 degrees, while orthoses further reduced the angle of metatarsophalangeal joint extension to a mean angle of 55 degrees. The marginal reduction in first metatarsophalangeal joint extension caused by functional orthoses may be of therapeutic value in the early stages of hallux rigidus, when restricting motion at the joint may slow or prevent development of subchondral sclerosis.

Odorant identification in rats: an update

In a previous report, Youngentob et al. (8) described a new and substantially different type of animal psychophysical procedure in which rats were trained to differentially report (i.e., identify) five different odorants. The present study confirms and extends the usefulness of the cross-modal association paradigm as an effective means for developing an extensive nonverbal "vocabulary" with which an animal can communicate multiple changes in sensory stimuli. Given the appropriate nonverbal means of communication, a rat has the channel capacity to differentially report (i.e., identify), at least ten different odorants. The expansion to a ten odorant identification task is discussed with respect to the analytic capabilities of the animal model for the study of olfactory quality perception.

Plasma Motions in Planetary Magnetospheres

Before direct exploration by spacecraft, Jupiter was the only planet other than Earth that was known to have a magnetic field, as revealed by its nonthermal radio emissions. The term "magnetosphere" did not exist because there was no clear concept of such an entity. The space age provided the opportunity to explore Earth's neighborhood in space and to send instruments to seven of the other eight planets. It was found that interplanetary space is pervaded by a supersonic "solar wind" plasma and that six planets, including Earth, have magnetic fields of sufficient strength to deflect this solar wind and form a comet-shaped cavity called a magnetosphere. Comparative study of these magnetospheres aims to elucidate both the general principles and characteristics that they share in common, and the specific environmental factors that cause the important, and sometimes dramatic, differences in behavior between any two of them. A general understanding of planetary magnetospheres holds the promise of wide applicability in astrophysics, which, for the indefinite future, must rely solely on remote sensing for experimental data.

Automated computerized rat eater meter: description and application

A real-time Automated Computerized Rat Eater Meter was developed by modifying commercially available metabolic cages. Food access via a feeding tunnel was monitored by photocells. Food consumption was measured by an electronic scale. The signals thus generated were processed by a computer. This allowed us to continuously measure the spontaneous feeding behavior of free-feeding nondeprived Fischer rats for a sum total of 35 study days. Based on our data, we defined a meal as an episode of food consumption preceded and followed by at least 5 minutes of no feeding. Fischer rats showed periodic nychthemeral eating behavior. Food consumption, number of meals, meal sniffs, intermeal sniffs, and, consequently, eating activity were greater during the dark cycle than the light cycle. Meal duration, meal size, and thus food consumption rates remained constant throughout both cycles. Our modification of commercially available metabolic cages provides unique data for continuously monitoring rat feeding patterns over prolonged periods of time.

Surveillance programme for the control of foodborne infections and intoxications in Europe: the first 6 years' experience in Scotland, 1980-85

In 1979 WHO recommended the establishment of a surveillance programme in Europe for foodborne infections and intoxications that incorporated an early warning system for incidents affecting more than one country as well as a routine reporting system to record details of outbreaks of foodborne disease. The Early Warning System was introduced in Scotland in July 1979 and the Routine Reporting System in January 1980. By the end of 1985, 23 European countries were participating in the programme.The introduction of the surveillance programme in Scotland permitted the formation of a standard national reporting system for foodborne infections and intoxications. During the 6 years from 1980 to 1985, the major features of the programme in Scotland have been the introduction of compulsory pasteurization of cows' milk, in 1983, with the consequent eradication of general outbreaks of milkborne salmonellosis; the emergence of poultry meat as the major food vehicle of infections; and the development of techniques for costing foodborne disease outbreaks.

Felodipine can replace minoxidil in the treatment of refractory hypertension

In a group of 15 men with severe hypertension in a double-blind crossover trial, the new calcium antagonist felodipine has been shown to lower blood pressure as effectively as minoxidil when used in combination with a beta-blocker and a loop diuretic. Felodipine was well tolerated and may have a role in the management of severe hypertension.

Remote Sensing of the Magnetic Moment of Uranus: Predictions for Voyager

Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system.

Ethnohistory and alcohol studies

This chapter briefly outlines the development of ethnohistory in the United States and Canada and then examines the contributions that ethnohistorical studies have made to our understanding of heavy drinking in situations of acculturation. Three major models used by anthropologists and ethnohistorians to account for heavy drinking in such contexts are identified: (1) drinking as a response to sociocultural disorganization, (2) drinking as a response to deprivation, and (3) drinking as an expression of traditional values and activities. These models are evaluated in light of recent theoretical and methodological developments within anthropology and other social sciences. The discussion draws on ethnohistorical case studies to exemplify these developments. It is argued that ethnohistory 's ongoing interaction between field and archival research offers a unique and essential approach to the study of alcohol use.

Hyphal tip growth in Achlya. II. Subcellular localization of cellulase and associated enzymes

The isolation and characterization of cellulase-containing membranes of Achlya ambisexualis Raper was attempted by differential and density gradient centrifugations. Maximum cellulase activity was found at an isopycnic density of 1.19 g/cm3, although some activity was found at other densities. A similar distribution of activity was shown by IDPase, ATPase, UDPG transferase, and by sedimentable carbohydrate. The coequilibration and steady enrichment of these activities during purification suggests their presence in a single type of subcellular particle. It was not possible to identify clearly the particle(s) in question from isolated fractions by electron microscopy, but when compared with the cytochemical localization of carbohydrate and IDPase in intact hypha, cytoplasmic vesicles with 150-mm diameters seem to be likely candidates.

Hyphal tip growth in Achlya. I. Cytoplasmic organization

Growing apices of Achlya ambisexualis Raper hyphae were examined by electron microscopy using cytochemical techniques. Apical vesicles can be grouped into two major classes based upon size and cytochemical reactions. Vesicles of the most prominent class are about 150 nm in diameter and possess contents which appear fibrous in thin section. This fibrous material reacts positively with the periodic acid-silver methenamine (PASM) cytochemical test for polysaccharides. Most of these same vesicles also display IDPase activity, and a smaller number display acid phosphatase activity. Vesicles of the second class are about 80 nm in diameter, and include coated vesicles and others which react positively for IDPase activity. They show a negative PASM reaction in contrast with the larger vesicles. Some of these smaller vesicles are stained by the phosphotungstic acid-chromic acid (PTA-CrO3) stain, whereas 150-nm vesicles are not. The source of at least some vesicles of both major classes appears to be the Golgi apparatus. It is proposed that the IDPase activity and carbohydrate content of the 150-nm cytoplasmic vesicles could serve as useful markers in their isolation.

Corotation Lag in Jupiter's Magnetosphere: Comparison of Observation and Theory

Voyager 1 plasma flow data are compared with a recent theory that predicted measurable departures from rigid corotation in Jupiter's magnetosphere as a consequence of rapid plasma production and weak atmosphere-magnetosphere coupling. The comparison indicates that the theory can account for the observed corotation lag, provided that the plasma mass production rate during the Voyager 1 encounter was rather larger than expected, namely approximately 10(30) atomic mass units per second.

The renal haemodynamic and excretory actions of prostacyclin and 6-oxo-PGF1 alpha in anaesthetized dogs

Intrarenal arterial (i.a.) infusions of prostacyclin (PGI2) at 30-300 ng/min to anaesthetized dogs reduced renal vascular resistance (RVR) and filtration fraction (FF), increased mean renal blood flow (MRBF) but did not alter mean arterial pressure (MAP)or glomerular filtration rate (GFR). The urinary excretion of sodium (UNaV), potassium (UKV) and chloride ions (UC1V) were increased through inhibition of net tubular ion reabsorption. PGI2 (3000 ng/min, i.a.) reduced MAP and increased heart rate. Intravenous (i.v.) infusions of PGI2 (3000 gn/min) reduced MAP, GFR, FF, urine volume and ion excretion, with elevation of heart rate. The measured variables were unaltered by 6-oxo-PGF1 alpha (10,000 ng/min i.a.). Treatment of the dogs with the PG synthetase inhibitor meclofenamic acid (2.5 mg/kg i.v.) did not antagonise the elevation of MRBF to PGI2 (300 ng/min i.a.). Thus the renal effects of PGI2 were due to a direct action rather than through conversion to 6-oxo-PGF1 alpha or through stimulation of endogenous renal PG biosynthesis and release.

Ascocarp ultrastructure of Herpomyces sp. (Laboulbeniales) and its phylogenetic implications

The asci of Herpomyces sp. (Laboulbeniales) compose a parenchymatous tissue produced by progressive cleavage of three or four meristematic ascogenous cells attached in the base of the ascocarp. Ascospores are delimited by membranes derived from an ascus vesicle, and the spore wall forms between paired prospore membranes. Dilated cisternae and epiplasmic membranes are associated with wall formation. While ascospores are developing, asci are displaced apically, their passage apparently lubricated by a matrix secreted by the peridial cells.The presence of an ascomycetous spindle pole body, septal pore with Woronin bodies, ascus vesicle, and dilated Golgi-like cisternae indicates a close relationship between Herpomyces sp. and the filamentous Ascomycetes while providing no support for theories maintaining a close relationship between Laboulbeniales and the red algae.