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Investigations into insect-induced plant responses of water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub.) (Pontederiaceae)
No full textThe water hyacinth (Eichhornia crassipes (Mart.) Solms-Laub (Pontederiaceae)) biological
control programme makes use of tight plant-insect interactions to control the weed, by reestablishing
the interactions between the plant and its natural enemies. Since the beginning
of the water hyacinth biological control initiative, the impact of biological control agent
herbivory on water hyacinth’s population growth and fitness have been well documented;
however, very few investigations have been conducted to determine whether herbivory
elicits insect-induced responses by water hyacinth.
Studies were conducted to determine the presence and function of water hyacinth insectinduced
responses, using the plant activator, BION®, in attempt to determine the plant
hormone-mediated pathways regulating the final expressions of insect-induced defences in
response to herbivory by the phloem-feeder, Eccritotarsus catarinensis (Carvalho)
(Hemiptera: Miridae) and the leaf chewer, Neochetina bruchi Hustache (Coleoptera:
Curculionidae). BION® (Syngenta, acibensolar-S-methyl (benzothiadiazole)) is a
dissolvable, granular formulation that contains a chemical analogue of the plant hormone,
salicylic acid (SA), which typically regulates defences against pathogens. The application of
BION® results in the induction of the SA-mediated defence pathways in plants (activation of
defences against pathogens), and consequently the inhibition of the jasmonic acid (JA)-
mediated defence pathways (de-activation of defences against insect herbivores).
To test for induced defence responses in water hyacinth, plants treated with BION® and then
subjected to herbivory, were compared to un-treated plants that were also subjected to
herbivory, BION®-only treated plants and control plants. The application of BION® did not
confer resistance against the two insect herbivores, as herbivory, reductions in chlorophyll
content and plant growth (leaf production and second petiole lengths) significantly increased
in comparison to non-BION® treated plants. Furthermore, palatability indices significantly
increased (>1.00) in BION® treated plants, reflecting increased weevil preferences for SAinduced
water hyacinth plants. This concluded that SA-mediated defences are not effective
against insect herbivory in water hyacinth plants, but are in fact palatable to insect
herbivores, which reflects ecological and physiological costs of SA-mediated defences
(pathogen defences) in water hyacinth. Biochemical analyses of leaves exhibited increases in nitrogen content in BION® treated
plants. These elevated levels of nitrogenous compounds account for the increases in mirid
and weevil preferences for BION® treated plants. The increases in nitrogenous compounds
are probably structural proteins (e.g. peroxidises), because leaves treated with BION®
increased in toughness, but only when exposed to herbivory. Regardless, insect herbivory
was elevated on these leaves, probably because the nitrogenous compounds were
nutritionally viable for the insects
Reinforced Concrete & Masonry Design: SDEB3/0
No full textSupplementary Examination on Reinforced Concrete & Masonry Design: SDEB3/0, Jan 201
The diversity of root fungi associated with Erica species occurring in the Albany Centre of Endemism
No full textSouth Africa has the highest species diversity of ericaceous plants belonging to the Erica genus. There are over 850 identified species in the Cape Floral Region. The Albany Centre of Endemism (ACOE) is located within this region and is a hotspot of diversity consisting of various plant genera. The success of Erica plants is ubiquitously attributed to mycorrhizal relationships they engage in with a diverse group of fungi. This symbiosis is known as the ericoid mycorrhizal (ERM) association. The overall aim of this study was to establish the diversity of root fungi associated with Erica plants using morphological, molecular and 454 pyrosequencing techniques.
Six Erica species were identified using leaf and flower morphology according to taxonomic keys. The identified plants were Erica cerinthoides, Erica demissa, Erica chamissonis, Erica glumiflora, Erica caffra and Erica nemorosa. Roots from sampled plants were stained and examined microscopically to determine their mycorrhizal status. Ericoid mycorrhizal associations together with dark septate endophyte (DSE) structures and hyphae that did not form any specific structure were observed in all the roots. In addition arbuscular mycorrhizal (AM) structures in the form of vesicles were detected in E. glumiflora and E. cerinthoides. In order to identify the culturable fungi associated with the respective hosts, sterilised roots were placed on various culture media for cultivation. Thereafter isolated fungi were morphologically classified into 67 morphotypes. These were mostly sterile and darkly pigmented. Non-sporulating mycelia of variable colouration such as white, cream-yellowish, beige, green and brown were also observed. Further identification was carried out using molecular techniques. DNA was extracted separately from pure cultures and amplified using ITS1 and ITS4 primers in a polymerase chain reaction (PCR). Thereafter sequencing and Basic Local Alignment Search Tool (BLAST) were used to identify the isolates to generic level. The fungi were taxonomically classified into 54 operational taxonomic units and 94 percent were Ascomycetes and Helotiales was the dominant order. Unclassified Helotiales with affinities to fungi currently identified as Epacrid root fungus was common in all hosts. Other isolates that were identified included Oidiodendron, Meliniomyces, Phialocephala, Cadophora, Lachnum, Leohumicola Cryptosporiopsis, Chaetomium, Acremonium and Epicoccum species. Basidiomycetes were represented by two OTUs belonging to the genus Mycena. Four OTUs comprised fungi that had no significant alignments in the reference databases. Direct root DNA extraction together with 454 pyrosequencing was used to detect the diversity of culturable and unculturable fungi associated with the identified hosts. The ITS2 region was targeted for sequencing. Although Ascomycetes remained the dominant phyla, Basidiomycetes were also detected in all host plants. Glomeromycota was present in E. caffra and E. cerinthoides. Helotiales was dominant in all Erica plants with the exception of E. cerinthoides and E. chamissonis which were dominated by the order Chaetothyriales. The OTUs identified to genus level included Epacris pulchella root fungus, Oidiodendron cf. maius, Acremonium implicatum, Leohumicola, Lachnum, Capronia and Mycena species. Culture-based techniques and pyrosequencing detected similar fungal composition comprising Ascomycetes, while, pyrosequencing was able to detect Glomeromycetes and Basidiomycetes
Experiences of HIV positive clients defaulting isoniazid preventive therapy (IPT) in King Williams town area under the Buffalo City municipality in the Eastern Cape Province.
No full textThis qualitative study using a phenomenological design, aimed at exploring and describing and exploring the experiences of HIV positive clients defaulting Isoniazid Preventive Therapy services in the Bhisho Primary Health Care Services. The emphasis was on the factors leading clients to default.
An in- depth unstructured face to face interviews were done on 14 participants from 4 clinics or facilities under Bhisho Primary Health Care Services. From the respondents’ responses it can be noted that work and family related issues, ignorance of patients, side effects, and negligence of nurses and denial of HIV status were identified as reasons for defaulting. Having knowledge about the treatment and health providers’ attitudes to patients also played a role in patients defaulting their treatment.
Many suggestions were then put forward by the respondents to curb defaulting among patients. These included the use of text message reminders, not to discrimination HIV patients because of their status, to use consulting rooms for privacy and also nurses and caregivers to control their attitudes when dealing with patients
Investigation into the characteristicsand possible applications of biomassgasification by-products from a downdraft gasifier system
No full textBiomass gasification has attracted the interest of researchersbecause it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the byproducts whichcan be used for various application depending on quality.The study conducted at Melani village in Alice in the EasternCape of South Africa was aimedat investigating the possible applications of the gasificationbyproducts instead of being thrown away. Pine wood was employed asthe parentfeedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar(condensate), char, soot and resin. These materials were also blended to produce strong materials.The essence of the blending was to generate ideal material that is strong but light at the same time.The elemental analysis of the samplesperformed by CHNS analyserrevealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end productsof lignocellulosegasification. SEM gave the sticky images of resin as well as porous char structures. Char showeda higher heating value of 35.37MJ/Kg when compared to other by-products samples
A preliminary study on the effects of elevated CO2 on aphid resistance of Tugela Dn and the population dynamics of the Russian wheat aphid (Homoptera: Aphididae), Diuraphis noxia
No full textFood security is of major importance due to the increasing world population with 8.9 billion people expected by 2050 (Cohen, 2003). Diuraphis noxia (RWA), have caused aggravating, massive losses to wheat farmers in many areas of the world. If unchecked, RWA are able to destroy plants resulting in major economic impacts (Botha, 2013). Due to ineffective use of other control methods, the Small Grains Institute in Bethlehem, South Africa, have therefore developed resistant cultivars to the known RWA subtypes over the past decades through intensive breeding programmes (Tolmay et al., 2006). Climate change has however become a major factor threatening food security especially with the observed increase in CO2 from less than 300 ppm in pre-industrial period to the current 385 ppm and is predicted to reach 550 ppm by 2050 (IPCC, 2007; Meehl et al., 2007). Elevated CO2 concentration may affect individual species of a community hence the need to understand the wheat-aphid interactions.
In this study, population growth rates and virulence of RWA SA1 at ambient (385 ppm) and elevated (450 ppm) CO2 concentration were evaluated on two wheat cultivars: Tugela Dn (resistant) and Scheepers (susceptible). Fluorescence microscopy techniques using aniline blue were used to investigate feeding related damage caused by RWA SA1 through an examination of callose deposition at the two CO2 concentration. A two-dimensional gel electrophoresis method was developed in order to determine the effect of RWA SA1 on the wheat cultivars proteome at the two CO2 concentration. Differentially expressed proteins that were up or down regulated more than two fold were identified using PDQuestTM Basic 2D Gel analysis software.
Populations of RWA SA1 increased significantly on the two wheat cultivars at both CO2 concentration. Although the population growth rate for RWA SA1 on both cultivars was generally exponential at all treatments, growth at elevated CO2 concentration was noticeably faster with populations increasing 3 fold in 14 days as compared to the 2 times at ambient CO2 concentration. Hence, both cultivars provided a better quality host for RWA SA1 at 450 ppm than 385 ppm. There was no significant difference between RWA SA1 population on Tugela Dn and on Scheepers at elevated CO2 concentration on day 14 after infestation which means there was a change in the resistance mechanism in Tugela Dn at this condition. Approximately 70% of the total leaf showed chlorosis by 21 days of aphid infestation for both cultivars although the susceptible cultivar was more vulnerable. There was low callose deposition in the controls (uninfested plants) but heavy callose in infested plants due to aphid feeding.
A proteomics approach was used as a pilot study to investigate whether it would be possible to identify the changes in the resistance mechanism during aphid infestation under elevated CO2 levels. The major changes in the proteome of the control group (uninfested Tugela Dn at ambient versus elevated CO2 concentration) occurred in the early events (day 1-7) in the molecular weight range of approximately 25 kDa to 55 kDa are mainly within the basic to neutral pH range. This was suggested to be a result of mechanisms to adjust to the CO2 concentration. Elevated CO2 results in instant higher photosynthetic rates and C:N ratios as well as changes in expression levels of SA-dependant defense genes (Lindroth 1995; Hughes and Bazzaz, 2001; Sun et al., 2013). Because most of these changes are directly regulated by proteins, it is expected that the most differential protein expression will occur immediately after the atmospheric changes (early events) as was shown in the study.
Infested plants under elevated and ambient conditions showed that the stress conditions gave rise to differentially regulated proteins within the wheat proteome. Most changes occurred elevated CO2 levels. It can be suggested that the changes were a result of differentially regulated plant defence proteins which fall in this range (25 kDa - 80 kDa) such as peroxidases, chitinases and β-1.3-glucanases as well as protein kinases, heat-shock proteins and photosynthetic proteins. These results indicate that there has been changes in the resistance due to elevated CO2 because of the evident changes in the proteome.
If so, then the results will be similar to those documented by Louw (2007) where up-regulation was due to putative storage proteins, proteins involved in photosynthesis, heat shock proteins and defense proteins. Of course, the pI value and molecular mass of the proteins and the identification of the proteins in these spots, must be determined in future work to specifically identify whether these suggestions are authentic. However, Louw (2007) also reports that the susceptible Betta wheat cultivar, displayed a defence response similar to the HR although it was unable to up-regulate specific defensive proteins against RWA infestation but proteins for broad resistance. Although the changes in the proteins in infested Tugela Dn under elevated CO2 concentration were not accurately identified, the defense mechanism is similar to that portrayed by the susceptible Betta wheat cultivar which shows that the resistance mechanism had been overcome. Because this was a pilot study and preliminary results were obtained due to limited funding and time constraints, suggestions were made on how to further develop the method to obtain statistically significant results
Photophysical and nonlinear optical studies of tetraakynyl zincphthalocyanine and its “clicked” analogue
No full textWe report here for the first time on the photophysical and nonlinear optical behavior of tetra-substituted alkynyl zinc phthalocyanine and its “clicked” analogue (4 and 5). The compounds exhibited high triplet quantum yields in dimethylsulphoxide (DMSO). Nonlinear optical (NLO) properties were also evaluated for the two compounds at 532 nm and 10 ns in DMSO. We observed two-photon absorption (2PA) and strong reverse saturable absorption (RSA) as the dominant mechanisms at nanosecond laser excitation. The presence of electron acceptor groups fused with triazole linkers in the peripheral positions of 4 provide excellent coexistent features, such as enhanced triplet quantum yields and lifetimes compared to 5. Large third-order susceptibility (2.09 × 10−11 and 3.53 × 10−9 esu) and hyperpolarizability (1.09 × 10−30 and 9.13 × 10−29 esu) were estimated for complexs 4 and 5, respectively.Original publication is available at http://dx.doi.org/10.1016/j.molstruc.2015.01.04
Physicochemical and photodynamic antimicrobial chemotherapy studies of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines
No full textThe synthesis and photophysicochemical properties of mono- and tetra-pyridyloxy substituted indium(III) phthalocyanines (InPcs) are presented in this study. General trends are described for quantum yields of fluorescence, triplet, singlet oxygen and photodegradation as well as lifetimes of fluorescence and triplet state of these compounds. The complexes exhibited high singlet oxygen quantum yields (ФΔ) ranging from 0.44 to 0.66 in DMF, and from 0.44 to 0.69 in DMSO and ФΔ = 0.31 for the quartenized tetra substituted InPc which is soluble in water. The triplet quantum yields (ФT) ranged from 0.77 to 0.95 in DMF and from 0.77 to 0.94) in DMSO. The tetra substituted photosensitizers do not differ in their inactivation of bacteria with over 8 log reduction of viable bacteria when compared with the mono substituted photosensitizer which could only manage a 1 log reduction.Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2014.12.01
A comparative photophysicochemical study of phthalocyanines encapsulated in core–shell silica nanoparticles
No full textOriginal publication is available at http://dx.doi.org/10.1016/j.saa.2014.08.06
Photophysical properties and photodynamic therapy effect of zinc phthalocyanine-spermine-single walled carbon nanotube conjugate on MCF-7 breast cancer cell line
No full textThe present study shows improved photodynamic therapy (PDT) effect of zinc mono carboxy phenoxy phthalocyanine (ZnMCPPc (1)) upon conjugation to spermine (via amide bond) as a targeting molecule on MCF-7 breast cancer cells. The ZnMCPPc-spermine (2) conjugate was adsorbed onto single walled carbon nanotubes (represented as ZnMCPPc-spermine-SWCNT (3)). There was no change in the fluorescence quantum yield of complex 1 following formation of 2 or 3. Complexes 2 and 3 showed improved photophysical properties; with over 50% increases in triplet and singlet oxygen quantum yields compared to 1. Complexes 1, 2 and 3 were relatively not toxic to MCF-7 cancer cells when incubated with 5–40 μM of each complex for 24 h in the dark. The PDT results showed that at 40 μM complex 1 resulted in only 64% decrease in cell viability, while 2 and 3 improved the PDT effect of 1 to 97% and 95% decrease in cell viability at 40 μM respectively.Original publication is available at http://dx.doi.org/10.1016/j.synthmet.2015.03.01