Browsing by Author "Ameka, G.K."
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Item A checklist of rheophytes of Cameroon(PhytoKeys, 2019-05-09) Ameka, G.K.; Kuetegue, F.; Sonké, B.Rivers in Cameroon were surveyed to collect and document rheophytic plants. Rheophytes are the dominant aquatic macrophytes in tropical river systems, where they are adapted to extreme environments of rushing water (e.g., river rapids, waterfalls and flash floods). Rheophytic plants are useful indicators of river health. However, their habitats are threatened by human activities such as agriculture, plantation development, alluvial mining and dam construction, particularly in tropical countries. In this survey we documented 66 rheophytic species in 29 genera and 16 families. Two ferns, 8 monocotyledons and 56 dicotyledons were listed. Apart from the Podostemaceae family in which all species are rheophytic, the other 15 families have few species which are rheophytic. Five of these families have up to four species and the remaining 10 have only one member as a rheophytic species. The conservation status of each species is assessed and discussed. This work urges botanists, conservationists, and policy makers to do more to protect the habitats of rheophytes and put in place strategies and action plans for the conservation of this important biological group. KeywordsItem Comparative morphology and molecular systematics of African Podostemaceae-Podostemoideae, with emphasis on Dickaeanthus and Ledermanniella from Cameroon(International Journal of Plant Sciences, 2007-02) Moline, P.; Thiv, M.; Ameka, G.K.; Ghogue, J.P.; Pfeifer, E.; Rutishauser, R.The Podostemaceae (eudicots, Malpighiales) are adapted to rivers that exhibit distinct high-low water seasonality, mainly in the tropics. They attach to submerged rocks with ribbonlike or crustose green roots that cover the substrate like a carpet. Pronounced root dorsiventrality resulted in disklike crusts lacking root caps. African Podostemoideae show a bewildering array of forms not known from other flowering plants, such as (i) foliage leaves having a basis with two sheaths (e.g., Ledermanniella linearifolia), (ii) modular shoot construction with repeated stem cups (Ledermanniella ledermannii), (iii) endogenous origin of flowers along stems (Dicraeanthus africanus), and (iv) epiphyllous flowers (Ledermanniella letouzeyi). Important morphological transformations specific to African podostemoids include a shift from erect to inverted flowers in the spathella and unilocular ovaries arising via septum loss. New matK sequence data and new morphological data for eight African Podostemaceae species of the genera Dicraeanthus, Djinga, and Ledermanniella are combined with previously published sequences representing all major groups to test the placement of the African taxa in the family. All podostemoids studied from continental Africa form a clade that is sister to the Madagascan genera Endocaulos and Thelethylax. The sister of this African-Madagascan lineage is the clade comprising all Asian podostemoids and the American genus Podostemum, whereas all other New World podostemoids and the subfamily Tristichoideae are more basal. © 2007 by The University of Chicago. All rights reserved.Item Developmental morphology of Ledermanniella bowlingii (Podostemaceae) from Ghana(Plant Systematics and Evolution, 2003-01) Ameka, G.K.; Clerk, G.C.; Pfeifer, E.; Rutishauser, R.Ledermanniella (c. 44 species) is the largest podostemoid genus in Africa. This paper deals with the structure and development of the Ghanaian species Ledermanniella bowlingii (J.B. Hall) C. Cusser (subgenus Ledermanniella). Characters typical for L. bowlingii include: green ribbon-like roots with exogenous lateral roots and endogenous shoots up to 120 cm; most leaves 3-7 times forked, with intrapetiolar stipules; flowers solitary or in clusters, borne on elongate stems or directly on roots; each flower bud inverted within a spathella; flowers unistaminate; tricolpate pollen in dyads; ovary mainly unilocular but bilocular at the base due to a rudimentary septum; mature capsule with eight ribs, 1.0-1.8 mm long, containing 12-34 seeds, dehiscing by two equal valves; capsule stalk with pedicel (10 mm) and gynophore (2 mm); silica bodies absent in all plant parts. Several characters of L. bowlingii are described here for the first time. The paper shows that accurate morphological analyses of African Podostemaceae are badly needed.Item DNA Barcoding as a Tool for Sustainable Harvesting of Medicinal Plants used in the Treatment of Diarrhoea and Male Sexual Weakness in Ghana(University of Ghana, 2013-07) Thomas, G.; Ameka, G.K.; Annang, T.Y.Due to high poverty levels coupled with high patients to doctor ratio in Ghana, most people especially the urban poor and rural dwellers resort to herbal medicines which are quite cheap for their primary healthcare. Developing measures to maximize the medicinal potentials of indigenous plants will reduce the number of lives lost through diseases. A major setback is that most herbal products sold in public places lack scientific evidence for safety, quality and efficacy. As the safety of herbal medicine depends on the ability to correctly identify the plants used in their preparation, this study sought to use DNA barcoding as (i) an identification tool in the authentication of herbal medicines and (ii) their sustainable management in southern Ghana. Silica- dried leaves samples from thirty seven different medicinal tree species covering 24 families, used in the treatment of diarrhoea and male sexual weakness from three different conservation areas: Ankasa, Bia and Kakum, were sequenced at the rbcL gene region. A success sequence rate of 94.59% was achieved for the rbcL gene region. To verify the authenticity of the reference DNA database produced from the thirty five medicinal tree sequences in the proper identification of medicinal plants species, silica-dried samples of eleven tree species from farmlands within the Akuapem North district of the Eastern region (specifically around Aburi and its environs) were sequenced in the rbcL gene region. All the eleven tree species had their counterparts successfully sequenced in the reference DNA database. A sequence success rate of 90.91% was achieved, and each of the sequences in the verification data perfectly matched their counterparts in the reference database implying that DNA barcoding can be used in the identification of all medicinal plants species to ensure the safety of herbal medicines in Ghana. The study also sought to find out: (i) the medicinal tree species used in the treatment of diarrhoea, male sexual weakness or both, (ii) how herbalists identify the plants species they use, (iii) their availability, distribution abundance, (iv) the quantity of medicinal plants used in the treatment of diarrhoea and male sexual weakness per month, (v) the parts and sources of the plants species used and (vi) the awareness of forest conservation in southern Ghana. Structured questionnaire and interview guides were used to seek information from a purposive group including herbalists, commercial medicinal plants collectors and sellers in two different markets; Kasoa and Nyanyano, and the communities around the three selected conservation areas; Ankasa, Bia and Kakum. The traditional method of identification was the only available method used for identification of medicinal plant species by both practicing herbalists and commercial plant collectors. Seventy three plants species were found to be effective for the treatment of diarrhoea and male sexual weakness or both. Roots were the commonly used part of the plants in herbal medicine preparation. The parts of plants used, and the rate of collection of some medicinal plants were found to affect the survival of some plants species. There was a hundred percent level of awareness of forest conservations in southern Ghana. DNA barcoding is the best identification tool for medicinal plants species which when accepted for use will completely eliminate misidentification and help in the proper documentation of medicinal plants species. This will inform on the proper conservation and management options for the protection of threatened species as well as the controlled harvesting and trade in vulnerable and important medicinal plants.Item Dna Barcoding in Sustainable Harvesting of Tree Species and Safety of Herbal Medicines Used in The Treatment of Malaria in Southern Ghana(University of Ghana, 2014-12) Appiah, C.O.; Ameka, G.K.; Annang, T.Y.; University of Ghana, College of Basic and Applied Sciences, Institute for Environment and Sanitation StudiesHerbal medicines continue to be used in every country around the world in healthcare delivery, however, due to poverty and high doctor to patient ratio; about 75% of the population of the developing world solely rely on herbal medicine for their primary health care. It is thus imperative to develop measures to maximize the medicinal potentials of indigenous plants to reduce the number of lives lost through diseases. However, most herbal products sold in public places lack scientific evidence for safety, quality and efficacy, and as the safety of herbal medicine depends on the ability to correctly identify the plants used in their preparation, this study sought to use DNA Barcoding to authenticate the identity of medicinal plants species used in the preparations of herbal medicines used to treat malaria and their sustainable management in southern Ghana. Leaf samples of 50 different plant species were collected in duplicate from three biodiversity hotspots; Bia Biosphere Reserve, Ankasa Resource Reserve and Kakum National Park and their DNA extracted and sequenced at the rbcLa gene region to serve as a background database for identification of those species. A success rate of 80% was achieved. A cladogram was then generated from these sequences together with sequences of other tree species from Ghana in the Gene Bank of Consortium for the Barcode of Life Database for comparison. Each of the sequences correctly matched their counterpart which means that DNA barcoding can be used in the identification of all medicinal plants species. The study also sought to find out the medicinal tree species used in the treatment of malaria, and how herbalists identify the plant species they use. Structured questionnaire and interview guides were used to seek information from herbalists, commercial herbal plants collectors and sellers in two different markets; Kasoa and Nyanyano, and the communities around three biodiversity hotspots; Ankasa, Bia and Kakum. Morphological identification was the only available method used for identification of medicinal plant species. Fifty plant species were found to be effective for the treatment of malaria in southern Ghana. Roots, bark and leaves were the commonly used part of the plants in herbal medicine preparation. The parts of plants used can affect the survival of some plants species. There was a hundred percent level of awareness of forest conservation in southern Ghana. DNA barcoding is the best identification tool for medicinal plant species which when accepted for use will completely eliminate misidentification and help in the proper documentation of medicinal plant species. This will inform on the proper conservation and management options for the protection of vulnerable species as well as the controlled harvesting and trade in vulnerable and important medicinal plants.Item DNA barcoding of african podostemaceae (river-weeds): A test of proposed barcode regions(Taxon, 2010-02) Kelly, L.J.; Ameka, G.K.; Chase, M.W.DNA barcoding has the possibility for application in many fields, ranging from biological inventory and species discovery to forensics and quality control. Barcoding could have great utility within the aquatic angiosperm family Podostemaceae, as these plants can be extremely difficult to identify on the basis of morphological characters alone, but are important components of tropical rivers and face threats from increased water pollution. Several potential barcodes for land plants have been suggested, including two 3-locus combinations proposed by the Plant Working Group of the Consortium for the Barcode of Life. These loci, matK, rpoB, rpoC1, and trnH -psbA, were tested for their potential utility in African members of the Podostemaceae. Our results show that although the rpoC1 region performs best in terms of universality of amplification and sequencing, the superior resolving power of matK makes it the most promising of the regions for use in barcoding. In the light of these results, we discuss the potential to apply barcoding to Podostemaceae of Africa and make suggestions for the directions of future work to exploit the full potential of this new technology in this group of plants.Item Enigmatic morphology of Djinga felicis (Podostemaceae - Podostemoideae), a badly known endemic from northwestern Cameroon(Botanical Journal of the Linnean Society, 2009-05) Ghogue, J.P.; Ameka, G.K.; Grob, V.; Huber, K.A.; Pfeifer, E.; Rutishauser, R.Djinga is a monotypic genus restricted to the Cameroon Ridge ('Dorsale Camerounaise') of NW Cameroon. Besides the type locality Mount Djinga (Adamawa Province, near Tignère), it also grows in waterfalls near Mount Oku (NW Province). This paper describes the structure and development of Djinga felicis using scanning electron microscopy and microtome sections. Cusset's protologue is enriched considerably. Roots are green, dorsiventrally flattened and adherent to submerged rocks. They are broad ribbons or crusts (up to 1 cm broad) which branch exogenously. Root-borne shoots (up to 17 cm) have filamentous leaves with sheaths and (occasionally) attached stipules. Flowers are borne as part of reproductive short shoots which arise exogenously along the stems and endogenously along the roots. Djinga shows non-axillary stem branching. Reproductive shoots along the main stem usually stay short. They arise from the abaxial side of double-sheathed leaves, a key innovation of Podostemoideae. These short shoots shift into pocket-like stem positions clearly below their associated leaves. Each flower bud inside a spathella is erect, but with an inclined ovary. The flowers are unistaminate with a broad connective. Unlike many other Podostemoideae, the tricolpate pollen grains are arranged in both dyads and monads. The ovary is globular and unilocular. The mature 8-ribbed capsule dehisces by two slightly unequal valves, releasing 40-50 seeds. © 2009 The Linnean Society of London.Item Pesticides Bioconcentration Potential of Aquatic Plants in the Volta Lake(West African Journal of Applied Ecology, 2018) Koranteng, S.S.; Darko, D.A.; Nukpezah, D.; Ameka, G.K.The Volta Lake is known for the proliferation of numerous aquatic plants in its shallow waters. A major cause for the presence of the luxuriant vegetation is the intensive agricultural activities along the banks. These activities are heavily dependent on agrochemicals including fertilizers, which eventually get into the aquatic ecosystem via water ways. In this study, two aquatic plants; Ceratophyllum demersum and Nymphaea lotus were investigated in a pilot study to determine their bioconcentration of pesticides. Levels of organochlorine (OCs) and synthetic pyrethroids (SPs) were analysed using gas chromatograghy equipped with electron capture detector while gas chromatography equipped with pulse flame photometric detector was used for the organophosphorus pesticides (OPs) determination in the plant tissues. The ambient concentrations of these pesticides in the aqueous medium were also determined and the ratios of pesticide concentration in the plant and water samples estimate bioconcentration potential of the plants. Out of 38 detected pesticides, 22 (representing 58%) were bioconcentrated by the aquatic weeds. The Bioconcentration Factor (BCF) range for Ceratophyllum demersum was 1.06 – 4,470 and that for Nymphaea lotus was 1.27 – 800. By the standard of the European Union regulation for registration of chemicals, levels of diazinon and chlorpyrifos in Ceratophyllum demersum fulfilled the ‘bioaccumulation’ criterion (i.e BCF > 2000) while fenitrothion, with BFC of 5500 in the same plant fulfilled ‘very bioaccumulation’ criterion (BCF ≥ 5000). This study shows that aquatic weeds in their natural ecosystem have the remediation potential, though to varying degrees and hence play a role in the improvement of water quality.Item A review of biopolymer (Poly-β-hydroxybutyrate) synthesis in microbes cultivated on wastewater(Science of the Total Environment, 2021) Amadu, A.A.; Qiu, S.; Ge, S.; Addico, G.N.D.; Ameka, G.K.; Yu, Z.; Xia, W.; Abdul-Wahab, A.; Shao, D.; Champagne, P.The large quantities of non-degradable single use plastics, production and disposal, in addition to increasing amounts ofmunicipal and industrialwastewaters areamong themajor global issues known today. Biodegradable plastics from biopolymers such as Poly-β-hydroxybutyrates (PHB) produced by microorganisms are potential substitutes for non-degradable petroleum-based plastics. This paper reviews the current status of wastewatercultivated microbes utilized in PHB production, including the various types of wastewaters suitable for either pure or mixed culture PHB production. PHB-producing strains that have the potential for commercialization are also highlighted with proposed selection criteria for choosing the appropriate PHB microbe for optimization of processes. The biosynthetic pathways involved in producing microbial PHB are also discussed to highlight the advancements in genetic engineering techniques. Additionally, the paper outlines the factors influencing PHB production while exploring other metabolic pathways and metabolites simultaneously produced along with PHB in a bio-refinery context. Furthermore, the paper explores the effects of extraction methods on PHB yield and quality to ultimately facilitate the commercial production of biodegradable plastics. This reviewuniquely discusses the developments in research on microbial biopolymers, specifically PHB and also gives an overview of current commercial PHB companies making strides in cutting down plastic pollution and greenhouse gases.