Baseline isotopic data for Wolffia spp.: another option for tracing N-loading in freshwater systems?
- Authors: Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68721 , vital:29308 , https://0-doi.org.wam.seals.ac.za/10.1086/696126
- Description: δ15N values of aquatic plants can reflect anthropogenic N loading. Recent work suggests the duckweed Spirodela spp. effectively maps N loading in freshwater ecosystems, but its use may be complicated by a cyanobacterium–duckweed symbiosis that could reduce its utility in low-nutrient environments. I aimed to evaluate the potential of a 2nd duckweed species Wolffia spp., which lacks a cyanobacterial symbiosis, for use in pollution monitoring in freshwater ecosystems. I used a series of laboratory experiments to investigate δ15N equilibration rates and concentration-level effects of single-source N solutions in plant tissue over 16 d to provide baseline data for sewage-plume mapping with Wolffia spp. I also tested concentration-level effects in multisource solutions to investigate the effects of mixed-source inputs. Wolffia reflected environmental N sources with a 12- to 16-d isotopic equilibration time and showed enriched and depleted δ15N ratios for manure and KNO3 solutions, respectively, but distinguished poorly between lower concentrations of manure. Fractionations at isotopic equilibrium were opposite to expectations and decreased with increasing [N]. Wolffia showed a consistent preference for NH3 in mixed-source treatments, regardless of the proportion or concentration of NH3 or NO3– available, and a capacity for N storage, which may complicate mapping of N-loading in natural environments. Wolffia is likely to be a less useful bioindicator than the previously tested Spirodela. Future research should focus on field applications of Spirodela spp. to test its capacity for sewage-plume mapping of freshwater ecosystems in a natural environment.
- Full Text: false
Baseline isotopic data for Wolffia spp.: another option for tracing N-loading in freshwater systems?
- Authors: Hill, Jaclyn M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68721 , vital:29308 , https://0-doi.org.wam.seals.ac.za/10.1086/696126
- Description: δ15N values of aquatic plants can reflect anthropogenic N loading. Recent work suggests the duckweed Spirodela spp. effectively maps N loading in freshwater ecosystems, but its use may be complicated by a cyanobacterium–duckweed symbiosis that could reduce its utility in low-nutrient environments. I aimed to evaluate the potential of a 2nd duckweed species Wolffia spp., which lacks a cyanobacterial symbiosis, for use in pollution monitoring in freshwater ecosystems. I used a series of laboratory experiments to investigate δ15N equilibration rates and concentration-level effects of single-source N solutions in plant tissue over 16 d to provide baseline data for sewage-plume mapping with Wolffia spp. I also tested concentration-level effects in multisource solutions to investigate the effects of mixed-source inputs. Wolffia reflected environmental N sources with a 12- to 16-d isotopic equilibration time and showed enriched and depleted δ15N ratios for manure and KNO3 solutions, respectively, but distinguished poorly between lower concentrations of manure. Fractionations at isotopic equilibrium were opposite to expectations and decreased with increasing [N]. Wolffia showed a consistent preference for NH3 in mixed-source treatments, regardless of the proportion or concentration of NH3 or NO3– available, and a capacity for N storage, which may complicate mapping of N-loading in natural environments. Wolffia is likely to be a less useful bioindicator than the previously tested Spirodela. Future research should focus on field applications of Spirodela spp. to test its capacity for sewage-plume mapping of freshwater ecosystems in a natural environment.
- Full Text: false
Development of an LCT-Based MOOC Taxonomy
- Authors: Motara, Yusuf, M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428972 , vital:72550 , https://doi.org/10.1145/3289406.3289411
- Description: Codecademy is an example of a successful and disruptive player in the online education space. This work describes the structure, content, and experience of working through a Codecademy Pro Intensive module and compares it to the offline approach in a similar domain. Existing taxonomies are insufficiently general to explain its success, and a new taxonomy based on Legitimation Code Theory is developed to compensate. This taxonomy is arguably more meaningful and more general than those presently in use.
- Full Text:
- Authors: Motara, Yusuf, M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428972 , vital:72550 , https://doi.org/10.1145/3289406.3289411
- Description: Codecademy is an example of a successful and disruptive player in the online education space. This work describes the structure, content, and experience of working through a Codecademy Pro Intensive module and compares it to the offline approach in a similar domain. Existing taxonomies are insufficiently general to explain its success, and a new taxonomy based on Legitimation Code Theory is developed to compensate. This taxonomy is arguably more meaningful and more general than those presently in use.
- Full Text:
Digital Inclusion: A model for e-Infrastructure and e-Services in Developing Countries
- Terzoli, Alfredo, Siebörger, Ingrid, Tsietsi, Mosiuoa, Gumbo, Sibukelo
- Authors: Terzoli, Alfredo , Siebörger, Ingrid , Tsietsi, Mosiuoa , Gumbo, Sibukelo
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430973 , vital:72733 , https://doi.org/10.1007/978-3-319-98827-6_7
- Description: A large portion of the South African population is still not connected in a productive manner to the Internet, despite the existence of a govern-ment plan for public broadband, ‘SA Connect’. One reason for this could be the lack of an appropriate model, through which connectivity can be diffused in a meaningful way through all areas of South Africa. This paper presents the model developed over more than a decade of experimentation in real life settings in the Siyakhula Living Lab, a joint venture between the universities of Rhodes and Fort Hare, South Afri-ca. The model proposes the ‘Broadband Island’ as basic e-infrastructure unit, which clusters nearby points-of-presence hosted in schools. In each Broadband Island is located an applications integra-tion platform, TeleWeaver, which monetizes channels of access to the local community, to support the e-infrastructure while providing useful services to the population and the Government.
- Full Text:
- Authors: Terzoli, Alfredo , Siebörger, Ingrid , Tsietsi, Mosiuoa , Gumbo, Sibukelo
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430973 , vital:72733 , https://doi.org/10.1007/978-3-319-98827-6_7
- Description: A large portion of the South African population is still not connected in a productive manner to the Internet, despite the existence of a govern-ment plan for public broadband, ‘SA Connect’. One reason for this could be the lack of an appropriate model, through which connectivity can be diffused in a meaningful way through all areas of South Africa. This paper presents the model developed over more than a decade of experimentation in real life settings in the Siyakhula Living Lab, a joint venture between the universities of Rhodes and Fort Hare, South Afri-ca. The model proposes the ‘Broadband Island’ as basic e-infrastructure unit, which clusters nearby points-of-presence hosted in schools. In each Broadband Island is located an applications integra-tion platform, TeleWeaver, which monetizes channels of access to the local community, to support the e-infrastructure while providing useful services to the population and the Government.
- Full Text:
Genetic analysis reveals harvested Lethrinus nebulosus in the Southwest Indian Ocean comprise two cryptic species
- Healey, Amy J E, Gouws, Gavin, Fennessy, Sean T, Kuguru, Baraka, Sauer, Warwick H H, Shaw, Paul W, McKeown, Niall J
- Authors: Healey, Amy J E , Gouws, Gavin , Fennessy, Sean T , Kuguru, Baraka , Sauer, Warwick H H , Shaw, Paul W , McKeown, Niall J
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124538 , vital:35626 , https://doi.10.1093/icesjms/fsx245
- Description: This study initially aimed to investigate the genetic population/stock structuring of Lethrinus nebulosus in the Southwest Indian Ocean (SWIO) to inform management practices in light of emerging evidence of overharvesting of this species throughout its distribution. Adult samples were genotyped for 14 nuclear microsatellites and by sequencing fragments of the mtDNA control region and COI gene. A salient feature of the data was the congruent cyto-nuclear partitioning of samples into two high divergent, reciprocally monophyletic groups. This indicates that despite no a priori evidence, hitherto described L. nebulosus in the SWIO comprises two cryptic species that co-occur among southern samples. This intermingling indicates that, at least in southern samples, both species are being indiscriminately harvested, which may severely compromise sustainability. Limited microsatellite differentiation was detected within both species, though there was some evidence of isolation in the Mauritian population. In contrast, mtDNA revealed a pattern consistent with chaotic genetic patchiness, likely promoted by stochastic recruitment, which may necessitate a spatial bet-hedging approach to management to satisfy fishery management and conservation goals.
- Full Text:
- Authors: Healey, Amy J E , Gouws, Gavin , Fennessy, Sean T , Kuguru, Baraka , Sauer, Warwick H H , Shaw, Paul W , McKeown, Niall J
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124538 , vital:35626 , https://doi.10.1093/icesjms/fsx245
- Description: This study initially aimed to investigate the genetic population/stock structuring of Lethrinus nebulosus in the Southwest Indian Ocean (SWIO) to inform management practices in light of emerging evidence of overharvesting of this species throughout its distribution. Adult samples were genotyped for 14 nuclear microsatellites and by sequencing fragments of the mtDNA control region and COI gene. A salient feature of the data was the congruent cyto-nuclear partitioning of samples into two high divergent, reciprocally monophyletic groups. This indicates that despite no a priori evidence, hitherto described L. nebulosus in the SWIO comprises two cryptic species that co-occur among southern samples. This intermingling indicates that, at least in southern samples, both species are being indiscriminately harvested, which may severely compromise sustainability. Limited microsatellite differentiation was detected within both species, though there was some evidence of isolation in the Mauritian population. In contrast, mtDNA revealed a pattern consistent with chaotic genetic patchiness, likely promoted by stochastic recruitment, which may necessitate a spatial bet-hedging approach to management to satisfy fishery management and conservation goals.
- Full Text:
Genomic analysis reveals multiple mismatches between biological and management units in yellowfin tuna (Thunnus albacares)
- Mullins, Rachel B, McKeown, Niall J, Sauer, Warwick H H, Shaw, Paul W
- Authors: Mullins, Rachel B , McKeown, Niall J , Sauer, Warwick H H , Shaw, Paul W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124549 , vital:35627 , https://doi.10.1093/icesjms/fsy102
- Description: The South African (SAF) yellowfin tuna (Thunnus albacares) fishery represents a potential example of misalignment between management units and biological processes. The SAF fishery spans an operational stock with a boundary at 20_E, either side of which fish are considered part of Atlantic or Indian Ocean regional stocks. However, the actual recruitment of fish from Atlantic and Indian Ocean spawning populations into SAF waters is unknown. To address this knowledge gap, genomic analysis (11 101 SNPs) was performed on samples from Atlantic and Indian Ocean spawning sites, including SAF sites spanning the current stock boundary. Outlier loci conferred high discriminatory power to assignment tests and revealed that all SAF fish were assigned to the Indian Ocean population and that no Atlantic Ocean fish appeared in the SAF samples. Additionally, several Indian Ocean migrants were detected at the Atlantic spawning site demonstrating asymmetric dispersal and the occurrence of a mixed-stock fishery in Atlantic waters. This study highlights both the spatial inaccuracy of current stock designations and a misunderstanding of interactions between the underlying biological units, which must be addressed in light of local and global declines of the species. Specifically, the entire SAF fishery must be managed as part of the Indian Ocean stock.
- Full Text:
- Authors: Mullins, Rachel B , McKeown, Niall J , Sauer, Warwick H H , Shaw, Paul W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124549 , vital:35627 , https://doi.10.1093/icesjms/fsy102
- Description: The South African (SAF) yellowfin tuna (Thunnus albacares) fishery represents a potential example of misalignment between management units and biological processes. The SAF fishery spans an operational stock with a boundary at 20_E, either side of which fish are considered part of Atlantic or Indian Ocean regional stocks. However, the actual recruitment of fish from Atlantic and Indian Ocean spawning populations into SAF waters is unknown. To address this knowledge gap, genomic analysis (11 101 SNPs) was performed on samples from Atlantic and Indian Ocean spawning sites, including SAF sites spanning the current stock boundary. Outlier loci conferred high discriminatory power to assignment tests and revealed that all SAF fish were assigned to the Indian Ocean population and that no Atlantic Ocean fish appeared in the SAF samples. Additionally, several Indian Ocean migrants were detected at the Atlantic spawning site demonstrating asymmetric dispersal and the occurrence of a mixed-stock fishery in Atlantic waters. This study highlights both the spatial inaccuracy of current stock designations and a misunderstanding of interactions between the underlying biological units, which must be addressed in light of local and global declines of the species. Specifically, the entire SAF fishery must be managed as part of the Indian Ocean stock.
- Full Text:
Homology modeling and docking of AahII-Nanobody complexes reveal the epitope binding site on AahII scorpion toxin
- Ksouri, Ayoub, Ghedira, Kais, Abderrazek, Rahma Ben, Shankar, B A Gowri, Benkahla, Alia, Tastan Bishop, Özlem, Bouhaouala-Zahar, Balkis
- Authors: Ksouri, Ayoub , Ghedira, Kais , Abderrazek, Rahma Ben , Shankar, B A Gowri , Benkahla, Alia , Tastan Bishop, Özlem , Bouhaouala-Zahar, Balkis
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124604 , vital:35637 , https://doi.10.1016/j.bbrc.2018.01.036
- Description: Scorpion envenoming and its treatment is a public health problem in many parts of the world due to highly toxic venom polypeptides diffusing rapidly within the body of severely envenomed victims. Recently, 38 AahII-specific Nanobody sequences (Nbs) were retrieved from which the performance of NbAahII10 nanobody candidate, to neutralize the most poisonous venom compound namely AahII acting on sodium channels, was established. Herein, structural computational approach is conducted to elucidate the Nb-AahII interactions that support the biological characteristics, using Nb multiple sequence alignment (MSA) followed by modeling and molecular docking investigations (RosettaAntibody, ZDOCK software tools). Sequence and structural analysis showed two dissimilar residues of NbAahII10 CDR1 (Tyr27 and Tyr29) and an inserted polar residue Ser30 that appear to play an important role. Indeed, CDR3 region of NbAahII10 is characterized by a specific Met104 and two negatively chargedresidues Asp115 and Asp117. Complex dockings reveal that NbAahII17 and NbAahII38 share one common binding site on the surface of the AahII toxin divergent from the NbAahII10 one's. At least, a couple of NbAahII10 e AahII residue interactions (Gln38 e Asn44 and Arg62, His64, respectively) are mainly involved in the toxic AahII binding site. Altogether, this study gives valuable insights in the design and development of next generation of antivenom.
- Full Text:
- Authors: Ksouri, Ayoub , Ghedira, Kais , Abderrazek, Rahma Ben , Shankar, B A Gowri , Benkahla, Alia , Tastan Bishop, Özlem , Bouhaouala-Zahar, Balkis
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124604 , vital:35637 , https://doi.10.1016/j.bbrc.2018.01.036
- Description: Scorpion envenoming and its treatment is a public health problem in many parts of the world due to highly toxic venom polypeptides diffusing rapidly within the body of severely envenomed victims. Recently, 38 AahII-specific Nanobody sequences (Nbs) were retrieved from which the performance of NbAahII10 nanobody candidate, to neutralize the most poisonous venom compound namely AahII acting on sodium channels, was established. Herein, structural computational approach is conducted to elucidate the Nb-AahII interactions that support the biological characteristics, using Nb multiple sequence alignment (MSA) followed by modeling and molecular docking investigations (RosettaAntibody, ZDOCK software tools). Sequence and structural analysis showed two dissimilar residues of NbAahII10 CDR1 (Tyr27 and Tyr29) and an inserted polar residue Ser30 that appear to play an important role. Indeed, CDR3 region of NbAahII10 is characterized by a specific Met104 and two negatively chargedresidues Asp115 and Asp117. Complex dockings reveal that NbAahII17 and NbAahII38 share one common binding site on the surface of the AahII toxin divergent from the NbAahII10 one's. At least, a couple of NbAahII10 e AahII residue interactions (Gln38 e Asn44 and Arg62, His64, respectively) are mainly involved in the toxic AahII binding site. Altogether, this study gives valuable insights in the design and development of next generation of antivenom.
- Full Text:
In vitro antimalarial, antitrypanosomal and HIV-1 integrase inhibitory activities of two Cameroonian medicinal plants: Antrocaryon klaineanum (Anacardiaceae) and Diospyros conocarpa (Ebenaceae)
- Fouokeng, Y, Feusso, H M Feumo, Noundou, Xavier S, Krause, Rui W M, Teinkela, Jean E Mb, Wintjens, R, Hoppe, Heinrich C, Azebaze, Anatole G B, Vardamides, Juliette C, Isaacs, Michelle
- Authors: Fouokeng, Y , Feusso, H M Feumo , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E Mb , Wintjens, R , Hoppe, Heinrich C , Azebaze, Anatole G B , Vardamides, Juliette C , Isaacs, Michelle
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126653 , vital:35908 , https://doi.org/10.1016/j.sajb.2018.10.008
- Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value
- Full Text:
- Authors: Fouokeng, Y , Feusso, H M Feumo , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E Mb , Wintjens, R , Hoppe, Heinrich C , Azebaze, Anatole G B , Vardamides, Juliette C , Isaacs, Michelle
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126653 , vital:35908 , https://doi.org/10.1016/j.sajb.2018.10.008
- Description: Antiplasmodial, antitrypanosomal and anti-HIV-1 activities of crude extracts, fractions and some isolated compounds from two Cameroonian medicinal plants: Antrocaryon klaineanum Pierre (Anacardiaceae) and Diospyros conocarpa Gürke ex K. Schum. (Ebenaceae) were assessed. The phytochemical studies led to the isolation of eight compounds (1–8) from Diospyros conocarpa and six compounds (6, 9–13) from Antrocaryon klaineanum. These compounds were identified as mangiferolic acid (1), 3β, 22(S)-dihydroxycycloart-24E-en-26-oic acid (2), lupeol (3), aridanin (4), betulin (5), betulinic acid (6), bergenin (7), D-quercitol(8), entilin C(9), entilin A(10), antrocarine A(11), 7R,20(S)-dihydroxy-4,24(28)-ergostadien-3-one(12) and stigmasterol glucoside (13). The criteria for activity were set as follows: an IC50 value
- Full Text:
Kowieria alveoformis gen. nov. sp. nov., a new heterosporous lycophyte from the Latest Devonian of Southern Africa
- Gess, Robert W, Prestianni, Cyrille
- Authors: Gess, Robert W , Prestianni, Cyrille
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73894 , vital:30239 , https://doi.org/10.1016/j.revpalbo.2017.10.002
- Description: A new lycopsid, Kowieria alveoformis gen. et sp. nov., is described from the FamennianWitpoort Formation, Grahamstown, South Africa. It possesses spirally arranged elongated falcate vegetative leaves. Terminal bisporangiate strobili are present and show loosely grouped micro- and megasporophylls. Sporophylls are similar in shape to the vegetative leaves though somewhat wider with a marked expansion to house the sporangium. One sporangium is attached directly to the adaxial surface of the lamina. Each megasporangium contains up to four heavily ornamented hologulate megaspores of the Lagenicula type. The combination of both basal and derived characters within this plant places it at an interesting position at the base of the phylogenetic tree of rhizomorphic lycopsids.
- Full Text:
- Authors: Gess, Robert W , Prestianni, Cyrille
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73894 , vital:30239 , https://doi.org/10.1016/j.revpalbo.2017.10.002
- Description: A new lycopsid, Kowieria alveoformis gen. et sp. nov., is described from the FamennianWitpoort Formation, Grahamstown, South Africa. It possesses spirally arranged elongated falcate vegetative leaves. Terminal bisporangiate strobili are present and show loosely grouped micro- and megasporophylls. Sporophylls are similar in shape to the vegetative leaves though somewhat wider with a marked expansion to house the sporangium. One sporangium is attached directly to the adaxial surface of the lamina. Each megasporangium contains up to four heavily ornamented hologulate megaspores of the Lagenicula type. The combination of both basal and derived characters within this plant places it at an interesting position at the base of the phylogenetic tree of rhizomorphic lycopsids.
- Full Text:
Limitations of the random response technique and a call to implement the ballot box method for estimating recreational angler compliance using surveys:
- Bova, Christopher S, Aswani, Shankar, Farthing, Matthew W, Potts, Warren M
- Authors: Bova, Christopher S , Aswani, Shankar , Farthing, Matthew W , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145359 , vital:38431 , DOI: 10.1016/j.fishres.2018.06.017
- Description: Accurate estimation of the levels of non-compliance to fishing regulations is crucial in ensuring that long term sustainability goals of fisheries are met. When requesting information regarding sensitive behaviour, such as an angler’s non-compliance to regulations through direct questioning methods (DQM), their responses can be influenced by social desirability bias (SDB). Literature in human dimensions research on methods for controlling this bias is limited. There has been an emerging prevalence in the use of the random response technique (RRT), which is a method aimed at reducing SDB in questions regarding sensitive behaviour, although it has never been validated against observed data in an environmental resource use context. An alternative to the RRT, the use of a ballot box method (BBM) has been successfully implemented to reduce SDB in contingent valuation studies and is introduced in this paper as a method for reducing SDB in face-to-face survey responses regarding sensitive behaviour.
- Full Text:
- Authors: Bova, Christopher S , Aswani, Shankar , Farthing, Matthew W , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145359 , vital:38431 , DOI: 10.1016/j.fishres.2018.06.017
- Description: Accurate estimation of the levels of non-compliance to fishing regulations is crucial in ensuring that long term sustainability goals of fisheries are met. When requesting information regarding sensitive behaviour, such as an angler’s non-compliance to regulations through direct questioning methods (DQM), their responses can be influenced by social desirability bias (SDB). Literature in human dimensions research on methods for controlling this bias is limited. There has been an emerging prevalence in the use of the random response technique (RRT), which is a method aimed at reducing SDB in questions regarding sensitive behaviour, although it has never been validated against observed data in an environmental resource use context. An alternative to the RRT, the use of a ballot box method (BBM) has been successfully implemented to reduce SDB in contingent valuation studies and is introduced in this paper as a method for reducing SDB in face-to-face survey responses regarding sensitive behaviour.
- Full Text:
Synthesis, antiplasmodial and antitrypanosomal evaluation of a series of novel 2-oxoquinoline-based thiosemicarbazone derivatives
- Darrell, Oliver T, Hulushe, Siyabonga T, Mtshare, Thanduxolo Elihle, Beteck, Richard M, Isaacs, Michelle, Laming, Dustin, Khanye, Setshaba D, Hoppe, Heinrich C, Krause, Rui W M
- Authors: Darrell, Oliver T , Hulushe, Siyabonga T , Mtshare, Thanduxolo Elihle , Beteck, Richard M , Isaacs, Michelle , Laming, Dustin , Khanye, Setshaba D , Hoppe, Heinrich C , Krause, Rui W M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123117 , vital:35407 , https://doi.org/10.17159/0379-4350/2018/v71a25
- Description: Herein a series of novel thiosemicarbazones (TSCs) derived from 2-oxoquinoline scaffold is reported, and the target compounds have been successfully synthesized and characterized using standard spectroscopic techniques. The in vitro biological activities of synthesized molecules were evaluated against Plasmodium falciparum malaria parasites (strain 3D7), Trypanosoma brucei brucei parasites (strain 427) and HeLa cells. All the compounds displayed modest or no activity at a concentration of 20 μM and percentage viability of >50 % was often observed. Except for compound 9o, none of the final compounds exhibited cytotoxic effects against HeLa cells at 20 μM.
- Full Text:
- Authors: Darrell, Oliver T , Hulushe, Siyabonga T , Mtshare, Thanduxolo Elihle , Beteck, Richard M , Isaacs, Michelle , Laming, Dustin , Khanye, Setshaba D , Hoppe, Heinrich C , Krause, Rui W M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123117 , vital:35407 , https://doi.org/10.17159/0379-4350/2018/v71a25
- Description: Herein a series of novel thiosemicarbazones (TSCs) derived from 2-oxoquinoline scaffold is reported, and the target compounds have been successfully synthesized and characterized using standard spectroscopic techniques. The in vitro biological activities of synthesized molecules were evaluated against Plasmodium falciparum malaria parasites (strain 3D7), Trypanosoma brucei brucei parasites (strain 427) and HeLa cells. All the compounds displayed modest or no activity at a concentration of 20 μM and percentage viability of >50 % was often observed. Except for compound 9o, none of the final compounds exhibited cytotoxic effects against HeLa cells at 20 μM.
- Full Text:
The determination of CHARMM force field parameters for the Mg2+ containing HIV-1 integrase:
- Musyoka, Thommas M, Tastan Bishop, Özlem, Lobb, Kevin A, Moses, Vuyani
- Authors: Musyoka, Thommas M , Tastan Bishop, Özlem , Lobb, Kevin A , Moses, Vuyani
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148139 , vital:38713 , DOI: 10.1016/j.cplett.2018.09.019
- Description: The HIV integrase enzyme is a validated drug target. However, its potential has remained largely unexploited until recently due to lack of structural and mechanistic information. Its catalytic core domain (CCD) is crucial for the viral-human DNA integration making integrase an ideal target for inhibitor design. However, in order to do so, force field parameters for the integrase magnesium ion need to be established. Quantum mechanical calculations were used to derive force field parameters which were validated through molecular dynamics studies. Our results show that the parameters determined accurately maintain the integrity of the metal pocket of the integrase CCD.
- Full Text:
- Authors: Musyoka, Thommas M , Tastan Bishop, Özlem , Lobb, Kevin A , Moses, Vuyani
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148139 , vital:38713 , DOI: 10.1016/j.cplett.2018.09.019
- Description: The HIV integrase enzyme is a validated drug target. However, its potential has remained largely unexploited until recently due to lack of structural and mechanistic information. Its catalytic core domain (CCD) is crucial for the viral-human DNA integration making integrase an ideal target for inhibitor design. However, in order to do so, force field parameters for the integrase magnesium ion need to be established. Quantum mechanical calculations were used to derive force field parameters which were validated through molecular dynamics studies. Our results show that the parameters determined accurately maintain the integrity of the metal pocket of the integrase CCD.
- Full Text:
Three new pentacyclic triterpenoids from twigs of Manniophyton fulvum (Euphorbiaceae)
- Mbeunkeu, Ahri B D, Noundou, Xavier S, Krause, Rui W M, Teinkela, Jean E M, Laatsch, Hartmut, Azebaze, Anatole G B, Vardamides, Juliette C, Tala, Michel F
- Authors: Mbeunkeu, Ahri B D , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E M , Laatsch, Hartmut , Azebaze, Anatole G B , Vardamides, Juliette C , Tala, Michel F
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126782 , vital:35922 , https://doi.org/10.1016/j.phytol.2018.06.019
- Description: Phytochemical investigation of the methanol extracts of the twigs of Manniophyton fulvum has led to the isolation and characterization of three new pentacyclic triterpenoids, designated as 3α,28-dihydroxyfriedelan-1-one (1), manniotaraxerol A (3) and manniotaraxerol B (4), along with fourteen known compounds, 3α-hydroxy-1-oxofriedelane (2), betulinic acid (5), friedelin (S1), taraxerol (S2), a mixture of stigmasterol (S3) and β-sitosterol (S4), herranone (S5), docosanoic acid (S6), ursolic acid (S7), nasutin B (S8), bergenin (S9), stigmasterol-3-O-β-Dglucopyranoside (S10), 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-D-quinovopyranosyl)glycerol (S11), and aridanin (S12). The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI and ESI-MS). 3α,28-Dihydroxyfriedelan-1-one (1), 3α-hydroxy-1-oxofriedelane (2), manniotaraxerol A (3), manniotaraxerol B (4), and betulinic acid (5) were evaluated against HeLa (human cervix adenocarcinoma) cancer cells. Manniotaraxerol A (3) showed weak in vitro cytotoxicity with a cell viability value of 49.3%. Betulinic acid (5) also showed significant cytotoxicity against HeLa cell with a cell viability value of 4.0%; the other compounds were inactive in this test.
- Full Text:
- Authors: Mbeunkeu, Ahri B D , Noundou, Xavier S , Krause, Rui W M , Teinkela, Jean E M , Laatsch, Hartmut , Azebaze, Anatole G B , Vardamides, Juliette C , Tala, Michel F
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126782 , vital:35922 , https://doi.org/10.1016/j.phytol.2018.06.019
- Description: Phytochemical investigation of the methanol extracts of the twigs of Manniophyton fulvum has led to the isolation and characterization of three new pentacyclic triterpenoids, designated as 3α,28-dihydroxyfriedelan-1-one (1), manniotaraxerol A (3) and manniotaraxerol B (4), along with fourteen known compounds, 3α-hydroxy-1-oxofriedelane (2), betulinic acid (5), friedelin (S1), taraxerol (S2), a mixture of stigmasterol (S3) and β-sitosterol (S4), herranone (S5), docosanoic acid (S6), ursolic acid (S7), nasutin B (S8), bergenin (S9), stigmasterol-3-O-β-Dglucopyranoside (S10), 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-D-quinovopyranosyl)glycerol (S11), and aridanin (S12). The structures of all compounds were determined by comprehensive spectroscopic analyses (1D and 2D NMR, EI and ESI-MS). 3α,28-Dihydroxyfriedelan-1-one (1), 3α-hydroxy-1-oxofriedelane (2), manniotaraxerol A (3), manniotaraxerol B (4), and betulinic acid (5) were evaluated against HeLa (human cervix adenocarcinoma) cancer cells. Manniotaraxerol A (3) showed weak in vitro cytotoxicity with a cell viability value of 49.3%. Betulinic acid (5) also showed significant cytotoxicity against HeLa cell with a cell viability value of 4.0%; the other compounds were inactive in this test.
- Full Text:
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