The Occurrence and Infectivity of Arbuscular Mycorrhizal Fungi in Inoculated and Uninoculated Rhizosphere Soils of Two-year-old Commercial Grapevines

Arbuscular mycorrhizal (AM) fungal populations present in the rhizosphere of vine roots in the vineyards of a commercial farm in the Stellenbosch Region were investigated using microscopic analyses. AM root colonisation levels of between 70% and 90% were found in both grapevine roots that were previously artificially inoculated with commercial AM inocula, and in uninoculated (control) grapevine roots. The AM fungal isolates in the rhizosphere soil, identified using morphological criteria, belonged to the genera Acaulospora, Gigaspora, Glomus, Sclerocystis and Scutellospora.  The majority of species found was not present in the commercial inocula and was either indigenous to the vineyard or originated from the nursery where the vines were obtained. Isolates of Glomus and Acaulospora appeared to be the most abundant. The AM fungal species occurred at a soil phosphorus (P) concentration of up to 80 mg/kg P and a soil pH (KCl) that ranged between 5.63 and 6.10. Total spore counts ranged between 1 000 and 3 779 spores/100 g dry soil. In accordance with literature, lower spore concentrations were recorded for the heavier soil types with no cover crop system, compared with the sandy soil type on which cover crops were sown annually

Incisors as digging tools in molerats (Bathyergidae)

The angle at which the incisors project forward and the amount of enamel per incisor is greater in molerats that use their incisors for digging (genera Georychus and Cryptomys), than in those molerats that do not use the incisors for digging (genus Bathyergus)

Characterisation of two desiccation-stress related cDNAs TrDr1 and TrDr2 in the resurrection moss Tortula ruralis11The nucleotide sequence reported in this paper appears in EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers AI304977 (TrDr1) and AI305064 (TrDr2)

Two EST-derived cDNAs TrDr1 and TrDr2 from Tortula ruralis were identified with significant similarity to psbI encoding the PSII 10kDa protein and the desiccation stress-related cDNA pcC3-06, respectively. RNA blot hybridisation using both total and polysomal RNA fractions was used to analyse TrDr1 and TrDr2 mRNA abundance in response to a desiccation/rehydration cycle. TrDr1 and TrDr2 steady-state transcript levels increased in response to desiccation and preferentially accumulated within the polysomal mRNA fraction. The data suggest that TrDR1 and TrDR2 play a role in vegetative desiccation- tolerance

Nest temperature fluctuations in a cavity nester, the southern ground-hornbill

Southern ground-hornbills Bucorvus leadbeateri inhabit savanna and bushveld regions of South Africa. They nest in the austral summer, which coincides with the wet season and hottest daytime temperatures in the region. They are secondary cavity nesters and typically nest in large cavities in trees, cliffs and earth banks, but readily use artificial nest boxes. Southern ground-hornbills are listed as Endangered in South Africa, with reintroductions into suitable areas highlighted as a viable conservation intervention for the species. Nest microclimate, and the possible implications this may have for the breeding biology of southern ground-hornbills, have never been investigated. We used temperature dataloggers to record nest cavity temperature and ambient temperature for one artificial and 11 natural southern ground-hornbill tree cavity nests combined, spanning two breeding seasons. Mean hourly nest temperature, as well as mean minimum and mean maximum nest temperature, differed significantly between southern ground-hornbill nests in both breeding seasons. Mean nest temperature also differed significantly from mean ambient temperature for both seasons. Natural nest cavities provided a buffer against the ambient temperature fluctuations. The artificial nest provided little insulation against temperature extremes, being warmer and cooler than the maximum and minimum local ambient temperatures, respectively. Nest cavity temperature was not found to have an influence on the breeding success of the southern ground-hornbill groups investigated in this study. These results have potentially important implications for southern ground-hornbill conservation and artificial nest design, as they suggest that the birds can tolerate greater nest cavity temperature extremes than previously thought.The Ford Wildlife Foundation and the First Rand Foundation (Project reference : 033391).http://www.elsevier.com/locate/jtherbio2018-05-31hb2017Veterinary Tropical Disease

Nicotiana glauca poisoning in ostriches (Struthio camelus)

Putative Nicotiana glauca (wild tobacco) poisoning was diagnosed in a flock of ostriches near Oudtshoorn, South Africa. Post mortem examinations (n = 7) were performed on ostriches (Struthio camelus) that had died. Suspicious leaf remnants (weighing 80–770 g), packed in a layer on top of other plant material, were carefully separated from the proventricular content and submitted for chemical determination of anabasine, the major toxic principle contained by this plant. A standard solid phase extraction method was used followed by an optimised liquid chromatography-mass spectrometry procedure. Anabasine was detected in the leaf remnants (114–177 μg/g dry weight) removed from the proventriculus of the ostriches that succumbed as well as in control N. glauca leaves (193 μg/g dry weight). The analytical methods used in this study revealed the presence of anabasine in the suspicious leaf remnants, indicating that the birds had been exposed to N. glauca and had died of this poisoning.http://www.journals.co.za/ej/ejour_savet.htm

Cobalt silicide formation on a Si(1 0 0) substrate in the presence of an interfacial (Fe90Zr10) interlayer

The reaction between a thin film (126 nm) of Co and Si has been studied at 450 C for 24 h under high vacuum conditions, in the presence of a FeZr barrier layer. Without a diffusion barrier layer between Co and Si, Co2Si forms at 350 C as the initial phase while CoSi2 forms at 550 C. The FeZr barrier layer changed the flux of atoms arriving at the reaction interface. Co reacted with the Si from the substrate and formed a mixed layer of CoSi and CoSi2 in the interlayer region. The use of the FeZr diffusion barrier has been demonstrated to lower the temperature formation of CoSi2 to 450 C. The reactions were characterised by Rutherford backscattering spectrometry, Auger electron spectroscopy depth profiling, X-ray diffraction using CoKa radiation and scanning electron microscopy.http://www.elsevier.com/locate/nimb2016-09-30hb201

Heat treatment of glassy carbon implanted with cesium at room and high temperatures

The effect of annealing temperature on the surface morphology and on the diffusion of cesium ions implanted into glassy carbon (Sigradur® G) is reported. The samples were implanted with 360 keV cesium ions to a fluence of 2 × 1016 ions/cm2 at room temperature, at 350 and at 600 °C. The room temperature implanted samples were isochronally vacuum annealed for 1 h at temperatures from 200 to 600 °C. All samples were studied by Rutherford backscattering scattering (RBS) and scanning electron microscopy (SEM). During implantation a strong redistribution of the cesium ions towards the surface is observed, which occurs already at room temperature and enhances at elevated temperatures. However, almost no cesium ions are lost in that process. Contrary, annealing at elevated temperatures results not only in a diffusion and redistribution of cesium, but also in a significant sublimation/evaporation of cesium into the vacuum. This suggests that during implantation some meta-stable compound is formed which prevents a cesium loss. SEM pictures of the samples show that implantation and subsequent annealing strongly influence the surface structure of the glassy carbon.Financial support of the National Research Foundation and the Bundesministerium für Bildung und Forschung (Germany) is gratefully acknowledged.http://www.elsevier.com/locate/nimbhb2013ai201

SEM analysis of ion implanted SiC

SiC is a material used in two future energy production technologies, firstly as a photovoltaic layer to harness the UV spectrum in high efficient power solar cells, and secondly as a diffusion barrier material for radioactive fission products in the fuel elements of the next generation of nuclear power plants. For both applications, there is an interest in the implantation of reactive and non-reactive ions into SiC and their effects on the properties of the SiC. In this study 360 keV Ag+, I+ and Xe+ ions were separately implanted into 6H–SiC and in polycrystalline SiC at various substrate temperatures. The implanted samples were also annealed in vacuum at temperatures ranging from 900 C to 1600 C for various times. In recent years, there had been significant advances in scanning electron microscopy (SEM) with the introduction of an in-lens detector combined with field emission electron guns. This allows defects in solids, such as radiation damage created by the implanted ions, to be detected with SEM. Cross-sectional SEM images of 6H–SiC wafers implanted with 360 keV Ag+ ions at room temperature and at 600 C and then vacuum annealed at different temperatures revealed the implanted layers and their thicknesses. A similar result is shown of 360 keV I+ ions implanted at 600 C into 6H–SiC and annealed at 1600 C. The 6H–SiC is not amorphized but remained crystalline when implanting at 600 C. There are differences in the microstructure of 6H–SiC implanted with silver at the two temperatures as well as with reactive iodine ions. Voids (bubbles) are created in the implanted layers into which the precipitation of silver and iodine can occur after annealing of the samples. The crystallinity of the substrate via implantation temperature caused differences in the distribution and size of the voids. Implantation of xenon ions in polycrystalline SiC at 350 C does not amorphize the substrate as is the case with room temperature heavy ion bombardment. Subsequent annealing of the implanted polycrystalline samples leads to increased thermal etching effects such as grain boundary grooving. Damage due to channelling (or non-channelling) in the different crystallites resulted also in differences in thermal etching in the crystallites.http://www.elsevier.com/locate/nimbhb201

Scanning electron microscopy of the surfaces of ion implanted SiC

This paper gives a brief review of radiation damage caused by particle (ions and neutrons) bombardment in SiC at different temperatures, and its annealing, with an expanded discussion on the effects occurring on the surface. The surface effects were observed using SEM (scanning electron microscopy) with an inlens detector and EBSD (electron backscatter diffraction). Two substrates were used, viz. single crystalline 6H-SiC wafers and polycrystalline SiC, where the majority of the crystallites were 3C-SiC. The surface modification of the SiC samples by 360 keV ion bombardment was studied at temperatures below (i.e. room temperature), just at (i.e. 350 C), or above (i.e. 600 C) the critical temperature for amorphization of SiC. For bombardment at a temperature at about the critical temperature an extra step, viz. postbombardment annealing, was needed to ascertain the microstructure of bombarded layer. Another aspect investigated was the effect of annealing of samples with an ion bombardment-induced amorphous layer on a 6H-SiC substrate. SEM could detect that this layer started to crystalize at 900 C. The resulting topography exhibited a dependence on the ion species. EBSD showed that the crystallites forming in the amorphized layer were 3C-SiC and not 6H-SiC as the substrate. The investigations also pointed out the behaviour of the epitaxial regrowth of the amorphous layer from the 6H-SiC interface.http://www.elsevier.com/locate/nimb2016-07-31hb201