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  • 1
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    Notes on Ceramiaceae (Rhodophyta) from the Eastern Cape Province, South Africa. III. New records from the Tsitsikamma Coastal Park, with the description of Scageliopsis tsitsikammae (2000)
    In:  Blumea: Biodiversity, Evolution and Biogeography of Plants vol. 45 no. 2, pp. 485-494
    Details
    Publication Date: 2024-01-12
    Description: The first southern African records are presented of Ptilothamnion codicolum and Vickersia baccata; Scageliopsis tsitsikammae is described as new to science. The genera Scageliopsis and Vickersia have not been previously recorded in southern Africa. Morphological descriptions and illustrations are given for all three species.
    Keywords: Ceramiaceae ; Ptilothamnion ; Scageliopsis ; Vickersia ; South Africa ; taxonomy
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 2
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    The genus Ptilothamnion (Ceramiaceae, Rhodophyta) in South Africa, with the description of P. goukammae spec. nov (2002)
    In:  Blumea: Biodiversity, Evolution and Biogeography of Plants vol. 47 no. 3, pp. 581-595
    Details
    Publication Date: 2024-01-12
    Description: The genus Ptilothamnion Thur. in Le Jolis is represented in South Africa by three, or possibly four species: P. codicolum, P. polysporum, P. goukammae spec. nov., and reportedly P. subsimplex, all recorded after 1983. An earlier record of P. pluma is probably erroneous.\nThe new species differs from known representatives of the genus by producing strictly one involucral filament from the hypogenous cell and additionally one from the subhypogenous cell. Ptilothamnion is a widespread genus, but rarely with more than two species in any given regional flora. A critical comparison of the c. 12 species shows that very few characters are shared by all of them.
    Keywords: Ceramiaceae ; Ptilothamnion ; Spermothamnieae ; South Africa ; taxonomy
    Repository Name: National Museum of Natural History, Netherlands
    Type: info:eu-repo/semantics/article
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  • 3
    Electronic Resource
    Electronic Resource
    Resolution and instrument line shape effects on spectral compensation with Fourier transform infrared spectrometers (1978)
    s.l. : American Chemical Society
    Analytical chemistry 50 (1978), S. 1804-1811 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50035a023
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  • 4
    Electronic Resource
    Electronic Resource
    Errors in absorbance measurements in infrared Fourier transform spectrometry because of limited instrument resolution (1975)
    s.l. : American Chemical Society
    Analytical chemistry 47 (1975), S. 2339-2347 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60364a030
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  • 5
    Electronic Resource
    Electronic Resource
    Purinergic regulation of basal and arginine vasopressin-stimulated hydraulic conductivity in rabbit cortical collecting tubule (1985)
    Springer
    The journal of membrane biology 88 (1985), S. 277-281 
    Details
    ISSN: 1432-1424
    Keywords: vasopressin ; adenosine ; water transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary An extracellular adenosine responsive site that stimulates adenylate cyclase activity has been identified in several tissues. There is limited information on the presence and physiologic significance of adenosine receptors in well-defined segments of the mammalian nephron. We therefore examined the effect of adenosine and selected analogues on basal hydraulic conductivity in rabbit cortical collecting tubules (CCT) perfused in vitro. Adenosine and analogues with an intact ribose moiety produced a significant, sustained increase in hydraulic conductivity. No increase in hydraulic conductivity was seen in either time control CCT's or CCT's exposed to an adenosine analogue with an altered ribose moiety. These experiments are compatible with the presence of a functional adenosine receptor which requires an intact ribose moiety and acts to increase hydraulic conductivity in the mammalian CCT. An intracellular adenosine responsive site, termed the “P site,” which inhibits adenylate cyclase activity, has also been described in several tissues. We therefore examined the effect of aP site agonist on hydraulic conductivity responses to arginine vasopressin, forskolin and cAMP.P site stimulation with 2′5′ dideoxyadenosine inhibited the effect of AVP and of forskolin but not of cAMP to increase hydraulic conductivity. These results are compatible with a functionalP site in the rabbit CCT which acts at the catalytic subunit of adenylate cyclase to inhibit hydraulic conductivity. Together, these results demonstrate purinergic modulation of basal and arginine vasopressin-stimulated water flux in the mammalian collecting tubule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01871091
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  • 6
    Electronic Resource
    Electronic Resource
    Forskolin increases osmotic water permeability of rabbit cortical collecting tubule (1984)
    Springer
    The journal of membrane biology 80 (1984), S. 243-248 
    Details
    ISSN: 1432-1424
    Keywords: forskolin ; collecting tubule ; adenylate cyclase ; water permeability ; vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Forskolin is a unique diterpene that may directly activate the catalytic subunit of adenylate cyclase. We therefore examined the effect of 50 μm forskohn on osmotic water permeability in rabbit cortical collecting tubules perfusedin vitro. Forskolin increased net volume flux (J v , from 0.30 to 1.22 nl/mm/min,P〈0.02) in all tubules. The hydro-osmotic effect of forskolin was similar with respect to magnitude and time course to that produced by a maximal dose (250 μU/ml) of arginine vasopressin. An additive effect onJ v andL p was not observed when maximal concentrations of forskolin and arginine vasopressin were given simultaneously. The compound d(CH2)5Tyr(Et) VAVP, which noncompetitively inhibits the vasopressin receptor, significantly reduced collecting tubular hydro-osmotic response to arginine vasopressin. In contrast, the hydro-osmotic response to forskolin was maintained in the presence of d(CH2)5 Tyr(Et)VAVP. However, the hydro-osmotic response to forskolin could be inhibited by 1.0 μm guanine 5′-(β,γ-imido) triphosphate (GppNHp) and by the calmodulin inhibitor N-(6-amenohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). These results demonstrate that forskolin exerts an hydro-osmotic effect in the mammalian nephron which occurs independent of the vasopressin receptor. Guanine nucleotide regulatory proteins may modulate the osmotic water permeability effect of forskolin. Finally, calmodulin is required for full expression of the effect of forskolin to increase osmotic water flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868442
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  • 7
    Electronic Resource
    Electronic Resource
    A NOTE ON ECONOMIC BASE STUDIES AND REGIONAL ECONOMETRIC FORECASTING MODELS (1970)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of regional science 10 (1970), S. 0 
    Details
    ISSN: 1467-9787
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-9787.1970.tb00055.x
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  • 8
    Electronic Resource
    Electronic Resource
    Sea surface wind stress and drag coefficients: The hexos results (1992)
    Springer
    Boundary layer meteorology 60 (1992), S. 109-142 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122064
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of localised eutrophication on competition between Ulva lactuca (Ulvaceae, Chlorophyta) and a commercial resource of Gracilaria verrucosa (Gracilariaceae, Rhodophyta) (1996)
    Springer
    Hydrobiologia 326-327 (1996), S. 291-296 
    Details
    ISSN: 1573-5117
    Keywords: ammonium ; competition ; eutrophication ; Gracilaria ; seaweed ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In spring (August) 1993 a bloom of Ulva lactuca appeared for the first time in Saldanha Bay, South Africa, and persisted through summer. Ulva wash-ups contaminated the beach and part of the commercial Gracilaria beach-cast had to be discarded. The biomass and distribution of Gracilaria and Ulva are described in relation to the seasonal water chemistry of the bay. Gracilaria survives in deeper water in summer by the pulsing of nutrients on an approximately 6-day cycle of movement of the thermocline that separates nutrient-rich bottom water from warm oligotrophic surface water. Ammonium-rich fish-factory discharge into this surface layer in a sector of the bay provided localised conditions for Ulva to out-compete Gracilaria at depths of 2–5m, demonstrating the powerful disruptive effect of eutrophication in this strongly stratified system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047821
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  • 10
    Electronic Resource
    Electronic Resource
    Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa (1999)
    Springer
    Journal of applied phycology 11 (1999), S. 429-436 
    Details
    ISSN: 1573-5176
    Keywords: distribution ; harvesting ; Porphyra ; recruitment ; seasonality ; South Africa ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008173321969
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