What does the movement of the Phloem-mobile symplastic tracer, 5,6-carboxyfluorescein in shoots of Pisum Sativum L. Indicate - the existence of a symplastic transport system? - a bid to answer some puzzling questions
- Ade-Ademilua, Omobolanle Elizabeth, Botha, Christiaan E J
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6492 , http://hdl.handle.net/10962/d1004475 , http://dx.doi.org/10.3923/ajpp.2006.127.131
- Description: Like other members of the Fabaceae, the minor veins of Pisum are categorized as a closed system termed type 2 minor vein configuration due to the presence of few or no plasmodesmal connections between the sieve element-transfer cell complex (SE-TCC) and the adjacent cells (Gamalei, 1989; van Bel and Gamalei, 1991) Pisum is classified further into the category of type 2 b minor vein configuration due to the presence of transfer cells with the characteristic wall ingrowths in the minor vein phloem (Gamalei, 1989). According to van Bel et al. (1992), there is a correlation between minor vein configuration and phloem loading. However, by reason of low plasmodesmal frequency, the pathway of the flow of assimilates in plants with type 2 minor vein configuration is considered to be apoplasmic (Gamalei, 1989; van Bel and Gamalei, 1991). Therefore, present reports on the movement of phloem-mobile 5,6-carboxyfluorescein, a known symplamically transported compound between pea leaflets raises some doubts on the accession that transport within the phloem in pea is strictly apoplasmic. In this study we look at different points of arguments and try to offer our explanation and conclusions on the transport pathways that are likely to exist in Pisum.
- Full Text: false
- Date Issued: 2006
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6492 , http://hdl.handle.net/10962/d1004475 , http://dx.doi.org/10.3923/ajpp.2006.127.131
- Description: Like other members of the Fabaceae, the minor veins of Pisum are categorized as a closed system termed type 2 minor vein configuration due to the presence of few or no plasmodesmal connections between the sieve element-transfer cell complex (SE-TCC) and the adjacent cells (Gamalei, 1989; van Bel and Gamalei, 1991) Pisum is classified further into the category of type 2 b minor vein configuration due to the presence of transfer cells with the characteristic wall ingrowths in the minor vein phloem (Gamalei, 1989). According to van Bel et al. (1992), there is a correlation between minor vein configuration and phloem loading. However, by reason of low plasmodesmal frequency, the pathway of the flow of assimilates in plants with type 2 minor vein configuration is considered to be apoplasmic (Gamalei, 1989; van Bel and Gamalei, 1991). Therefore, present reports on the movement of phloem-mobile 5,6-carboxyfluorescein, a known symplamically transported compound between pea leaflets raises some doubts on the accession that transport within the phloem in pea is strictly apoplasmic. In this study we look at different points of arguments and try to offer our explanation and conclusions on the transport pathways that are likely to exist in Pisum.
- Full Text: false
- Date Issued: 2006
Professionalism and training for mass communication: challenges and opportunities for Southern Africa
- Authors: Berger, Guy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6332 , http://hdl.handle.net/10962/d1008477
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Closely linked to a critical media citizenry that can demand better of the media, is the challenge of professionalism and training in the region. Professor Guy Berger illuminates the challenges that the region faces in this regard, a key one being the ability to to match the inputs with the outcomes ... where measuring whether the quality of media products is directly linked to the inputs in training needs to be explored further.
- Full Text:
- Date Issued: 2006
- Authors: Berger, Guy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6332 , http://hdl.handle.net/10962/d1008477
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Closely linked to a critical media citizenry that can demand better of the media, is the challenge of professionalism and training in the region. Professor Guy Berger illuminates the challenges that the region faces in this regard, a key one being the ability to to match the inputs with the outcomes ... where measuring whether the quality of media products is directly linked to the inputs in training needs to be explored further.
- Full Text:
- Date Issued: 2006
Evaluation of Bacillus thuringiensis Berliner as an alternative control of small hive beetles, Aethina tumida Murray (Coleoptera: Nitidulidae)
- Buchholz, S, Neumann, Peter, Neumann, K, Hepburn, H Randall
- Authors: Buchholz, S , Neumann, Peter , Neumann, K , Hepburn, H Randall
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6929 , http://hdl.handle.net/10962/d1011945
- Description: Small hive beetles, Aethina tumida Murray, are parasites and scavengers of honeybee colonies, Apis mellifera L., and have become an invasive species that can cause considerable damage in its new distribution areas. An effective subspecies of Bacillus thuringiensis Berliner (=Bt) would provide an alternative to chemical control of this pest. Therefore, we tested three different Bt strains [B. thuringiensis, var. aizawai (B401®), B. thuringiensis var. kurstaki (Novodor®) and B. thuringiensis var. San Diego tenebrionis (Jackpot®)] and Perizin® (3.2% coumaphos), each applied on combs with a pollen diet fed to pairs of adult beetles. This evaluates the products for the suppression of successful small hive beetle reproduction. While none of the tested Bt strains showed a significant effect on the number of produced wandering larvae, we could confirm the efficacy of coumaphos for the control of small hive beetles. We further show that it is also efficient when applied with a lower concentration as a liquid on the combs. We suggest the continued search for efficient Bt strains naturally infesting small hive beetles in its endemic and new ranges, which may become a part of the integrated management of this pest.
- Full Text:
- Date Issued: 2006
- Authors: Buchholz, S , Neumann, Peter , Neumann, K , Hepburn, H Randall
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6929 , http://hdl.handle.net/10962/d1011945
- Description: Small hive beetles, Aethina tumida Murray, are parasites and scavengers of honeybee colonies, Apis mellifera L., and have become an invasive species that can cause considerable damage in its new distribution areas. An effective subspecies of Bacillus thuringiensis Berliner (=Bt) would provide an alternative to chemical control of this pest. Therefore, we tested three different Bt strains [B. thuringiensis, var. aizawai (B401®), B. thuringiensis var. kurstaki (Novodor®) and B. thuringiensis var. San Diego tenebrionis (Jackpot®)] and Perizin® (3.2% coumaphos), each applied on combs with a pollen diet fed to pairs of adult beetles. This evaluates the products for the suppression of successful small hive beetle reproduction. While none of the tested Bt strains showed a significant effect on the number of produced wandering larvae, we could confirm the efficacy of coumaphos for the control of small hive beetles. We further show that it is also efficient when applied with a lower concentration as a liquid on the combs. We suggest the continued search for efficient Bt strains naturally infesting small hive beetles in its endemic and new ranges, which may become a part of the integrated management of this pest.
- Full Text:
- Date Issued: 2006
Urban-rural contrasts in Arbor Week in South Africa
- Guthrie, G, Shackleton, Charlie M
- Authors: Guthrie, G , Shackleton, Charlie M
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6631 , http://hdl.handle.net/10962/d1006823
- Description: Trees provide people with environmental benefits. Greening projects have been implemented worldwide, but many of them have frustratingly low participation levels. In South Africa, tree-planting campaigns such as the national Arbor Week are generally aimed at schools. Because of the remoteness of rural schools, there are urban / rural disparities in standards of education, infrastructure and support provided at schools, and hence we hypothesized that these disparities would be mirrored in tree-planting activities associated with national Arbor Week. In the study reported here, 236 urban and rural schools were assessed by means of postal surveys and subsampled via direct interviews, as to their participation in Arbor Week activities, the provision of trees, constraints to participation, and the perceived benefits of planting trees. Very few urban schools had never participated in any Arbor Week activities, whereas one-fifth of rural ones had never participated in any way. Urban schools participated in a greater number of Arbor Week activities than rural schools, including tree-planting, displaying posters and having speeches. Thus, overall information about Arbor Week is lacking in rural areas compared to urban ones. Rural schools derived more benefits from planting trees, with shade and education being the primary benefits overall. Rural schools were supplied with trees by NGOs, whereas urban schools received trees from individual or company donations. The major constraints to tree-planting are livestock damage, water shortages, vandalism and theft. These obstacles need to be addressed in a holistic fashion in order to improve the participation and success of National Arbor Week as a vehicle for tree-planting and environmental awareness.
- Full Text:
- Date Issued: 2006
- Authors: Guthrie, G , Shackleton, Charlie M
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6631 , http://hdl.handle.net/10962/d1006823
- Description: Trees provide people with environmental benefits. Greening projects have been implemented worldwide, but many of them have frustratingly low participation levels. In South Africa, tree-planting campaigns such as the national Arbor Week are generally aimed at schools. Because of the remoteness of rural schools, there are urban / rural disparities in standards of education, infrastructure and support provided at schools, and hence we hypothesized that these disparities would be mirrored in tree-planting activities associated with national Arbor Week. In the study reported here, 236 urban and rural schools were assessed by means of postal surveys and subsampled via direct interviews, as to their participation in Arbor Week activities, the provision of trees, constraints to participation, and the perceived benefits of planting trees. Very few urban schools had never participated in any Arbor Week activities, whereas one-fifth of rural ones had never participated in any way. Urban schools participated in a greater number of Arbor Week activities than rural schools, including tree-planting, displaying posters and having speeches. Thus, overall information about Arbor Week is lacking in rural areas compared to urban ones. Rural schools derived more benefits from planting trees, with shade and education being the primary benefits overall. Rural schools were supplied with trees by NGOs, whereas urban schools received trees from individual or company donations. The major constraints to tree-planting are livestock damage, water shortages, vandalism and theft. These obstacles need to be addressed in a holistic fashion in order to improve the participation and success of National Arbor Week as a vehicle for tree-planting and environmental awareness.
- Full Text:
- Date Issued: 2006
Interactions of fishes with particular reference to coelacanths in the canyons at Sodwana Bay and the St Lucia Marine Protected Area of South Africa
- Heemstra, Phillip C, Frickle, H, Hissmann, K
- Authors: Heemstra, Phillip C , Frickle, H , Hissmann, K
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7130 , http://hdl.handle.net/10962/d1011771
- Description: The deep demersal fish fauna at depths of 100–400min canyons off the St Lucia Marine Protected Area along the north coast of KwaZulu-Natal is compared with similar fish communities at the Comoro Islands and in the Indo-Pacific region. Fifty-four fish species were seen or photographed from the submersible Jago or by the discovery team of scuba divers in the coelacanth, Latimeria chalumnae, habitat of the canyons off Sodwana Bay. An additional 94 fish species known from depths of 100–200 m along the coast of northern KwaZulu-Natal are likely to occur in the canyon habitat. The fish fauna of the Sodwana canyons shares at least 18 species with the deep demersal fish community off tropical coral reefs of the Indo-Pacific region. Thirty-seven of the Sodwana canyon fishes are also known from the coelacanth habitat in the Comoros.
- Full Text:
- Date Issued: 2006
- Authors: Heemstra, Phillip C , Frickle, H , Hissmann, K
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7130 , http://hdl.handle.net/10962/d1011771
- Description: The deep demersal fish fauna at depths of 100–400min canyons off the St Lucia Marine Protected Area along the north coast of KwaZulu-Natal is compared with similar fish communities at the Comoro Islands and in the Indo-Pacific region. Fifty-four fish species were seen or photographed from the submersible Jago or by the discovery team of scuba divers in the coelacanth, Latimeria chalumnae, habitat of the canyons off Sodwana Bay. An additional 94 fish species known from depths of 100–200 m along the coast of northern KwaZulu-Natal are likely to occur in the canyon habitat. The fish fauna of the Sodwana canyons shares at least 18 species with the deep demersal fish community off tropical coral reefs of the Indo-Pacific region. Thirty-seven of the Sodwana canyon fishes are also known from the coelacanth habitat in the Comoros.
- Full Text:
- Date Issued: 2006
Editorial: tracing actors, actants and relational dynamics in environmental education research
- Authors: Lotz-Sisitka, Heila
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67400 , vital:29084 , https://www.ajol.info/index.php/sajee/article/view/122719
- Description: publisher version , Introduction: This edition of the EEASA Journal provides insight into a range of relationships in the field of environmental education, and the complexities that exist around them, as reflected in the combination of papers. This Editorial picks up on the methodological ‘note’ (or is it a challenge?) provided by Godwell Nhamo in his paper in this edition of the journal. He provides a description of the possibilities that actor network theory provides for describing and explaining environmental policy processes, and recommends that environmental educators consider this methodology in their analyses. In particular, he refers environmental educators to applications of actor network theory for tracing relational dynamics between actors (i.e., environmental education practitioners) and actants which are non-human referents (e.g., the UN Decade of Education for Sustainable Development and UNESCO’s (2005) International Implementation Scheme). In response to his paper, I have chosen to ‘pick up’ on this methodological discussion in this Editorial, by considering aspects of this theoretical perspective in describing the ‘happenings’ that occur across the pages of this edition of the EEASA Journal. In doing so, I highlight (in part) the diversity of actors and actants that are influencing the field of environmental education, their subject matter and contexts, and I highlight the relational dynamics that become evident when one accepts a methodology that aims to trace such dynamics. In particular, this Editorial considers how ‘The language of actors, actants and actor/actant-networks brings to the fore the relationships and complexities that exist around them’ (Nhamo, this edition).
- Full Text:
- Date Issued: 2006
- Authors: Lotz-Sisitka, Heila
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67400 , vital:29084 , https://www.ajol.info/index.php/sajee/article/view/122719
- Description: publisher version , Introduction: This edition of the EEASA Journal provides insight into a range of relationships in the field of environmental education, and the complexities that exist around them, as reflected in the combination of papers. This Editorial picks up on the methodological ‘note’ (or is it a challenge?) provided by Godwell Nhamo in his paper in this edition of the journal. He provides a description of the possibilities that actor network theory provides for describing and explaining environmental policy processes, and recommends that environmental educators consider this methodology in their analyses. In particular, he refers environmental educators to applications of actor network theory for tracing relational dynamics between actors (i.e., environmental education practitioners) and actants which are non-human referents (e.g., the UN Decade of Education for Sustainable Development and UNESCO’s (2005) International Implementation Scheme). In response to his paper, I have chosen to ‘pick up’ on this methodological discussion in this Editorial, by considering aspects of this theoretical perspective in describing the ‘happenings’ that occur across the pages of this edition of the EEASA Journal. In doing so, I highlight (in part) the diversity of actors and actants that are influencing the field of environmental education, their subject matter and contexts, and I highlight the relational dynamics that become evident when one accepts a methodology that aims to trace such dynamics. In particular, this Editorial considers how ‘The language of actors, actants and actor/actant-networks brings to the fore the relationships and complexities that exist around them’ (Nhamo, this edition).
- Full Text:
- Date Issued: 2006
Karyology of the redfin minnows, genus Pseudobarbus Smith, 1841 (Teleostei: Cyprinidae): one of the evolutionarily tetraploid lineages of South African barbines
- Naran, D, Skelton, Paul H (Paul Harvey), Villet, M H (Martin Herrer)
- Authors: Naran, D , Skelton, Paul H (Paul Harvey) , Villet, M H (Martin Herrer)
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6770 , http://hdl.handle.net/10962/d1008063
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
- Authors: Naran, D , Skelton, Paul H (Paul Harvey) , Villet, M H (Martin Herrer)
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6770 , http://hdl.handle.net/10962/d1008063
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
Karyology of the redfin minnows, genus Pseudobarbus Smith, 1841 (Teleostei: Cyprinidae): one of the evolutionarily tetraploid lineages of South African barbines
- Naran, D, Skelton, Paul H, Villet, Martin H
- Authors: Naran, D , Skelton, Paul H , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6961 , http://hdl.handle.net/10962/d1012024
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
- Authors: Naran, D , Skelton, Paul H , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6961 , http://hdl.handle.net/10962/d1012024
- Description: The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
- Full Text:
- Date Issued: 2006
Critical media literacy: a design for the future
- Authors: Prinsloo, Jeanne
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6331 , http://hdl.handle.net/10962/d1008476
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Professor Jeanne Prinsloo notes in her article that "In fact, it has been argued that the significance of the media in people’s lives has increased to the extent that it has been described as their primary curriculum, thereby recasting formal education as the secondary curriculum." This therefore requires an incestment in media literacy; people's ability to to understand the world around them, as represented in the media. Thus, Professor Prinsloo argues for critical media literacy, citing the role that the media played in fuelling the genocide in Rwanda, as an illustrative case in point. She states that "While we can not attribute all blame in the Rwandan scenario to the radio use, it is clear that the media mattered." She indicates that "media representations and engagements play a significant role in the way we understand the world, its people and events, and ourselves therein." As such, societies should invest in building a critical citizenry that can read and deconstruct the various ideologies that are often carries in and through the media.
- Full Text:
- Date Issued: 2006
- Authors: Prinsloo, Jeanne
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6331 , http://hdl.handle.net/10962/d1008476
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Professor Jeanne Prinsloo notes in her article that "In fact, it has been argued that the significance of the media in people’s lives has increased to the extent that it has been described as their primary curriculum, thereby recasting formal education as the secondary curriculum." This therefore requires an incestment in media literacy; people's ability to to understand the world around them, as represented in the media. Thus, Professor Prinsloo argues for critical media literacy, citing the role that the media played in fuelling the genocide in Rwanda, as an illustrative case in point. She states that "While we can not attribute all blame in the Rwandan scenario to the radio use, it is clear that the media mattered." She indicates that "media representations and engagements play a significant role in the way we understand the world, its people and events, and ourselves therein." As such, societies should invest in building a critical citizenry that can read and deconstruct the various ideologies that are often carries in and through the media.
- Full Text:
- Date Issued: 2006
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