Department of Molecular Biology and Biotechnology
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Browsing Department of Molecular Biology and Biotechnology by Author "Buriyo, Amelia S."
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Item Assessment of Native Agar Gels Extracted from Gracilaria debilis and Gracilaria salicornia Harvested Along the Tanzanian Coast for Culturing Microorganisms(2008) Kivaisi, A.; Buriyo, Amelia S.Native agar gels extracted from Gracilaria debilis and G. salicornia harvested during the rainy and dry seasons, were assessed for culturing the microorganisms Micrococcus luteus, Saccharomyces cerevisiae and Pleurotus flabellatus. Agars extracted from plants harvested during the rainy season were suitable for culturing bacteria, and yeast cells using the ‘Pour Plate’ method, and for mushroom tissue culture. Agar extracted from G. debilis harvested during the dry season could be used for culturing bacterial cells by the ‘Spreading and Streaking’ method. The potential for laboratory applications and for mushroom spawn production using agar extracted from Tanzanian seaweeds is discussed.Item Cultivation and Utilisation Of Red Seaweeds in the Western Indian Ocean (WIO) Region(Springer, 2014) Msuya, Flower E.; Buriyo, Amelia S.; Omari, Isabel; Pascal, Benjamin; Narrain, Koushul; Ravina, Joseph J. M.; Mrabu, Elisha; Wakibia, Joseph G.Seaweed farming in the Western Indian Ocean (WIO) Region is carried out in a number of countries, most of them farming Eucheuma denticulatum, Kappaphycus alvarezii and Kappaphycus striatum. These species are farmed mostly in Tanzania with limited production in Madagascar, Mozambique and Kenya; current production (2012) stands at 15,966 t (dry weight) year−1 of Eucheuma and Kappaphycus, valued at US$ 4.2 million with 95 % of this tonnage coming from Tanzania. Other countries in the region have limited or no seaweed production owing to problems of epiphytes, ice ice and markets. The problem of epiphytes coupled with ice ice that WIO countries are facing causes die-off of Kappaphycus which is the preferred species in foreign markets for its thicker gel, kappa carrageenan (vs. the weaker iota carrageenan from Eucheuma). New efforts are put to curb these problems including moving seaweed farms to deeper waters and cultivation trials of other carrageenophytes as well as agar-producing species, agarophytes. Research work has been initiated to evaluate Gracilaria and Hypnea farming and processing in Tanzania, the Republic of Mauritius and Mayotte. Gracilaria farming is at experimental stages as a biofilter of fishpond effluents and as potential species for the production of agar with growth rates of 1.5–1.9 % day−1. Hypnea farming is only being initiated in Mauritius and Mayotte at present. Other innovations including value addition by making various seaweed products and encouraging the consumption of seaweed as food at least in Tanzania and Mauritius are increasing further the importance of the seaweed farming and processing industry in the WIO Region.Item The Effect of Seasons on Yield And Quality of Carrageenan from Tanzanian Red Alga Eucheuma Denticulatum (Gigartinales, Rhodophyta)(Elsevier, 2001-09) Buriyo, Amelia S.; Semesi, A. K.; Mtolera, Matern S. P.Samples were collected monthly from Oyster Bay, Dar es Salaam. Light, temperature, salinity, pH, seawater nitrogen and phosphorus were determined on each sampling period. Mean carrageenan yield was significanlly higher during the SE monsoon period (t = 6.15, P<0.05). Gef strength was significantly higher during NE monsoon period (t = 2.61, P<0.05) and lower during the start of the rainy season particularly in March.Item Extensive Spread of Farmed Seaweeds Causes A Shift from Native to Non-Native Haplotypes in Natural Seaweed Beds(Springer, 2015) Tano, S. A.; Halling, C.; Lind, E.; Buriyo, Amelia S.; Wikström, S. A.Seaweed farming has been the cause of introductions of non-indigenous seaweed species and genotypes throughout the world. In Zanzibar, Tanzania, foreign genotypes of Eucheuma denticulatum were introduced for farming purposes in 1989, and in recent years a spread of nonindigenous haplotypes has been reported. The current study aimed to investigate the presence and extent of introduced and native haplotypes of E. denticulatum as well as their relative frequencies, to obtain the severity of the spread of cultivated seaweed and the current state of the native populations. The results show that all investigated sites are dominated by the introduced South-east Asian haplotypes, even where seaweed farming has never occurred. As the frequencies of East African haplotypes are remarkably low, this shows a shift from native to introduced E. denticulatum. This shift may, at least in part, be caused by earlier overharvest of natural seaweed populations, and indicates a cryptic invasion of the introduced haplotypes at the potential cost of the recovery of the native haplotype populationsItem Gracilariopsis Mclachlanii Sp. Nov. and Gracilariopsis Persicasp. Nov. of the Gracilariaceae (Gracilariales, Rhodophyceae) from the Indian Ocean(Wiley, 2008-07-30) Bellorin, Alexis M.; Buriyo, Amelia S.; Sohrabipour, Jelveh; Oliveira, Mariana C.; Oliveira, Eurico C.Two new species of Gracilariopsis from the Indian Ocean are proposed—Gracilariopsis (Gp.) mclachlanii Buriyo, Bellorin et M. C. Oliveira sp. nov. from Tanzania and Gracilariopsis persica Bellorin, Sohrabipour et E. C. Oliveira sp. nov. from Iran—based on morphology and DNA sequence data (rbcL gene and SSU rDNA). Both species fit the typical features of Gracilariopsis: axes cylindrical throughout, freely and loosely ramified up to four orders, with an abrupt transition in cell size from medulla to cortex, cystocarps lacking tubular nutritive cells and superficial spermatangia. Nucleotide sequence comparisons of rbcL and SSU rDNA placed both species into the Gracilariopsis clade as distinct species from all the accepted species for this genus, forming a deeply divergent lineage together with some species from the Pacific. The new species are very difficult to distinguish on morphological grounds from other species of Gracilariopsis, stressing the importance of homologous molecular marker comparisons for the species recognition in this character-poor genus.Item A New Strategy for Treating Nets. Part 1: Formulation and Dosage(Wiley, 1999-03) Miller, J. E.; Buriyo, Amelia S.; Karugila, A.; Lines, J. D.The conventional dosages of pyrethroid insecticides on mosquito nets assume that nets will be retreated at6–12 month intervals. However, dosage should be related to washing of nets; if nets are only washed once ortwice a year, their dosage requirements will be different to those which are washed fortnightly. A ‘low-dose, fre-quent-wash’ retreatment system might be technically more appropriate and more affordable where nets arewashed frequently, as they are in Dar es Salaam. Moreover, for use as a domestic insecticide, water-based for-mulations of pyrethroid are preferable to the more commonly used emulsifiable concentrates (ECs). This paperreports laboratory evaluations of three formulations (ECs, Flowable, CS) of three pyrethroids (deltamethrin,lambdacyhalothrin, permethrin). Insecticidal activity was tested using serial bioassays at a range of dosagesusing Anopheles gambiae. The water-based formulations were no less effective than the ECs, even at the lowestdosages. Nets treated with 3 mg/m2and then repeatedly washed and retreated after each wash with either3 mg/m2or 1 mg/m2were subjected to gas chromatography analysis. This showed that the amounts ofpyrethroid in the nets accumulated rapidly over the first few wash-retreatment cycles and then remained fairlystable over subsequent cycles. These nets gave consistently high bioassay mortalities throughout the experi-ment, while the mortality declined rapidly after several washes with the nets that were treated at 3 mg/m2butnot retreated. Experimental huts were used to compare the effectiveness of these 2 net retreatment regimes andnets which were not retreated. All nets caused high mortality rates amongst Anopheles females, but had negligi-ble effects on culicines; either in killing them or in preventing feeding. Therefore use of a high ‘loading’ dose forinitial treatment with lower ‘maintenance’ doses for retreatment may be preferable to ensure that net userspromptly perceive the benefits of the insecticide against culicines.Item Seaweed Farming in Chwaka Bay: A Sustainable Alternative in Aquaculture?(2012) Eklöf, Johan S.; Msuya, Flower E.; Lyimo, Thomas J.; Buriyo, Amelia S.In Chwaka Bay, aquaculture (the farming of aquatic organisms) is represented by a small-scale but much debated activity; farming of marine macroalgae, or seaweed farming. Aquaculture as a whole dates back several millennia in areas like South-East Asia, but has during the last decades become heavily promoted as an alternative livelihood in developing countries to (i) reduce pressure on overharvested natural resources (e.g. fish stocks) and (ii) supply cheap food and income (Tacon 2001). Many promises of this “Blue Revolution” have, however, not been fulfilled, because technical know-how and experience is often lacking (Dadzie 1992; Machena and Moehl 2001), and because some of the hitherto dominating forms (for example farming of giant shrimp/prawns) have been riddled with huge sustainability problems of their own (Deb 1998; Bryceson 2002).Item Standing Stock, Agar Yield and Properties of Gracilaria salicornia Harvested along the Tanzanian Coast(2004) Buriyo, Amelia S.; Kivaisi, Amelia K.Seasonal biomass variation and agar yield of G. salicornia (C. Ag.) Dawson from Oyster Bay, Dar es Salaam, and Chwaka Bay, Zanzibar, were determined, and some properties of the agar examined. Mean biomass and canopy cover values ranged from 21–60 g/m2 and 7– 20 %, respectively. The highest mean biomass and cover values were obtained during the SE monsoon. Agar yield varied from 13.7 to 30.2 % (dry weight) and was highest during the dry NE monsoon period. Alkali treatment generally reduced agar yield by 25–56 %. Gel strength of the agar gels ranged between 118 and 251 g/cm2 and was significantly higher during the NE monsoon period (t = 2.2; P = 0.04 and t = 8.9; P << 0.05) for samples collected from Oyster Bay and Chwaka Bay respectively). Mean gel strengths of native agar samples (205 ± 45 g/cm2) was about 42 % of that of the standard agar used. The 3,6-anhydrogalactose content was highest during the rainy season (37.4–44.3 %) and tended to coincide with low gel strengths. Sulphate content varied between 0.5 and 2.8 % in both populations. It was concluded that the best period for harvesting G. salicornia for agar production in Tanzania is the dry (NE monsoon) period.Item Studies on Tanzanian Hypneaceae: Seasonal Variation in Content and Quality of Kappa-Carrageenan from Hypnea musciformis (Gigartinales : Rhodophyta)(2005) Mtolera, Matern S. P.; Buriyo, Amelia S.Seasonal effects on yield and quality of kappa-carrageenan from the red alga Hypnea musciformis were investigated in samples collected from natural populations in Oyster Bay, Dar es Salaam during June 1996May 1997. The mean annual carrageenan yield, gel strength (after treatment with 0.1 M KCl) gelling and melting temperature (±standard deviation) were 25.24 ±4.44 % dry weight, 171.72 ±41.42 g/cm2, 54.66 ±3.12 C and 68.62 ±0.60 C, respectively. Carrageenan yield and quality (gel strength) during the SE and NE monsoon seasons were not significantly different (t = 0.55, p > 0.05) and (t = 1.91, p > 0.05), respectively. The reported carrageenan yield and gel strength values were, respectively, about 50% and 40% those of carrageenan from Kappaphycus alvarezii. Although the carrageenan properties from H. musciformis were promising, its natural populations are generally insufficient to sustain the pressure of economic harvesting. Moreover, the extent to which its carrageenan yield and properties could be improved is not known. Suitable methods for mariculture are therefore needed before the resource can be exploited economically.Item Taxonomic Challenges and Distribution of Gracilarioid Algae (Gracilariales, Rhodophyta) in Tanzania(2004) Buriyo, Amelia S.; Oliveira, E. C.; Mtolera, M. S. P.; Kivaisi, A. K.This paper reviews the taxonomical literature of the gracilarioid algae from Tanzania, and provides information about their ecology and distribution based on an intensive regime of local collection. Its aim was to provide names, even if on a preliminary basis, for local gracilarioid taxa. Our revision shows that species misidentification is widespread and that some species are in need of further critical taxonomic study. Nine species of Gracilaria are reported in the region, including one unidentified Gracilaria or Gracilariopsis.