African Journals On-line
African Journal of Biotechnology

Volume 2 Number 9 September 2003
ABSTRACTS

Mycotoxins in food in West Africa: current situation and possibilities of controlling it

S.A. Bankole* and A. Adebanjo

Department of Biological Sciences, Olabisi Onabanjo University, PMB 2002, Ago-Iwoye, Ogun State, Nigeria.

*Correspondence author: E-mail: [email protected]  or  [email protected]. 

Abstract

This review presents the different mycotoxins (aflatoxins, fumonisins and ochratoxin A) produced in agricultural crops in the West African sub-region. The acute and chronic toxic effects of the various mycotoxins are presented. Maize and groundnuts have been found to be excellent substrate for aflatoxin contamination, while fumonisins are widely distributed in maize. Other food products for which mycotoxin contamination has been reported in the sub-region include dried yam chips, tiger nut, melon seeds and stored herbal plants. Mycotoxin contamination is favoured by stress factors during plant growth, late harvesting of crops, high ambient humidity preventing thorough drying, unscientific storage practices and lack of awareness. Control measures include education of the populace on the danger of mycotoxin contaminated diet, early harvesting, rapid drying, sorting, sanitation, use of improved storage structures, smoking, insect control, the use of botanicals and synthetic chemicals as storage protectants, fumigation, biological control, the use of resistant varieties and detoxification of mycotoxin contaminated grains.

Key words: Mycotoxins, aflatoxins, food, fumonisins, ochratoxin A, surveillance, toxicology, prevention, control, West Africa.

Mevastatin-induced inhibition of cell growth in avocado suspension cultures and reversal by isoprenoid compounds

Dudley I. Mitchell and A. Keith Cowan*

Research Centre for Plant Growth and Development, School of Agricultural Sciences and Agribusiness, University of Natal-Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa.

*Corresponding author; Current Address: Nutra-Park Inc., 3225 Deming Way, Suite 140, Middleton, WI 53562, USA, Phone: (608) 662 0167, Fax: (608) 662 8259, E-mail: [email protected]. 

Abstract 

Cell suspension cultures were established using soft, friable callus derived from nucellar tissue of ‘Hass’ avocado (Persea americana Mill.) seed from fruit harvested 190 days after full bloom. Cell cultures were maintained in liquid medium supplemented with naphthalene acetic acid (NAA), isopentenyl adenine (iP) and sucrose and sub-cultured at 14 day intervals. Growth was typically sigmoidal with a lag phase of 7 days followed by an exponential phase of approximately 14 days. Mevastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC 1.1.1.34) was used to probe the contribution of metabolites of the isoprenoid pathway for avocado cell growth. Treatment with mevastatin inhibited cell growth and caused loss of cell viability. Inhibition of cell growth was transient and at all concentrations of mevastatin tested, recovery was evident within 17 days. The arrest of cell growth by 1 and 40 μmol/L mevastatin was negated when this inhibitor of HMGR was supplied in the presence of either mevalonolactone (MVL) or farnesyl diphosphate (FDP). By comparison, co-treatment of cells supplied 1 μmol/L mevastatin with stigmasterol showed little or no response whereas at 40 μmol/L mevastatin, stigmasterol induced partial recovery of cell growth. The results indicate a requirement for mevalonic acid (MVA) and cytosolic isoprenoid biosynthesis, in particular FDP, for avocado cell growth and support the hypothesis that appearance of the small-fruit phenotype in ‘Hass’ is inextricably linked to activity of HMGR.

Key words: Avocado, cell suspensions, farnesyl diphosphate, HMGR, mevalonic acid, Persea americana.

Phylogenetic and molecular evolutionary analyses of gypsy group retrotransposon families in the Egyptian cotton Gossypium barbadense

Abdel Ghany A. Abdel Ghany¹ and Essam A. Zaki²*

¹Institute of Efficient Productivity, Zagazig University, El Zagazig, Egypt.

²Genetic Engineering & Biotechnology Research Institute, GEBRI, Research Area, Borg El Arab, Post Code 21934, Alexandria, Egypt.

*Corresponding author; Essam A. Zaki, Current Address: Department of Biological Sciences, 1392 Lilly Hall of Life Sciences, West Lafayette, IN 47907-1392, Phone (765) 494-9837 Fax (765) 496-1496, E-mail: [email protected]. 

Abstract 

Gypsy group retrotransposons in the Egyptian cotton, Gossypium barbadense, was  examined by phylogenetic and molecular evolutionary analyses. DNA sequences of gypsy group retrotransposons in two G. barbadense cultivars revealed that these sequences are heterogeneous and represent two distinct families. Sequence variation between these families seems to preserve coding information of the reverse transcriptase domain. The high ratio of synonymous to nonsynonymous changes indicates that the reverse transcriptase domain of these families is evolving under purifying selection. Our phylogenetic analysis revealed that the closest relatives of cotton retroelements are found in other plants gypsy group retrotransposons. Cotton retroelements-encoded transcripts were detected in their related respective young seedlings using RNA slot-blot hybridization, suggesting their transcriptional activity. The wide distribution of gypsy group retrotransposons and the detection of their encoded transcripts illustrate their active role in the Gossypium genome. 

Key words: Evolution, Gossypium, gypsy, retrotransposons, reverse transcriptase, substitution rates, transcription.

Effects of sulphuric acid and hot water treatments on seed germination of tamarind (Tamarindus indica L)

S. Muhammad¹* and N. A. Amusa²

¹Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto, Nigeria.

²Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M.B. 5029, Moor Plantation, Ibadan. Nigeria.

*Corresponding Author: E-mail: [email protected]. 

Abstract 

A study was carried out to investigate the effects of sulphuric acid and hot water treatments on the germination of Tamarind (Tamarindus indica L). Seeds were placed on moistened filter papers in 28 cm diameter Petri dishes under laboratory condition for germination. 330 seeds of T. indica (10 seeds per Petri dish) with three replicates each were used. The highest germination was recorded in seeds treated with 50 per cent sulphuric acid concentration with 60 min soaking period. Germination was observed to be enhanced by increase in the sulphuric acid concentration, water temperature, and soaking period in all the trials, except with absolute sulphuric acid where poor response was observed. Results of this study may serve as useful information in the production and improvement of the tree species, as knowledge on seed germination requirements is a critical factor in seedlings production.

Key words: Tamarind, Tamarindus indica, sulphuric acid, hot water, germination.

Heavy metals concentrations and burden in the bivalves (Anadara (Senilia) senilis, Crassostrea tulipa and Perna perna) from lagoons in Ghana: Model to describe mechanism of accumulation/excretion

Fred A. Otchere

Azimuth Consulting Group, 218 – 2902 West Broadway, Vancouver, British Columbia.V6K 2G8 Canada,

*Corresponding author; E-mail: [email protected];  phone: 1.604.608.4283.

Abstract 

Seasonal sampling of the bivalves: Anadara (Senilia) senilis (n = 260), Crassostrea tulipa (n = 220), from two ‘open’ lagoons (Benya and Ningo) and a ‘closed’ lagoon (Sakumo), and Perna perna (n = 170), from rocky shores adjacent to Benya and Sakumo, were analyzed for their total Cu, Zn, Fe, Mn, Cd and Hg concentrations and total body burden (that is concentration multiply by total flesh weight). Median concentrations for cockles were: 5, 38, 710, 10, 0.22 and 0.20 µg/g dw respectively. Cd and Hg levels in dry season samples were higher than those in wet season. While Zn and Fe dry season levels were lower than wet season with no variation in Cu and Mn. Median total body burden in cockles were: 3.3, 30.5, 370, 5.2, 0.28 and 0.13 µg respectively. Geographical variations observed were mostly due to size distribution rather than the ecological differences between stations. Log-transformed regression relationships between body burden and size were used to compare the species. Relationship between condition index, body burden and concentration were used to develop a model to describe mechanism of accumulation/excretion.

Key words: Heavy metals, bivalves, marine, lagoons, seasonal variation, accumulation, Ghana.

Petroleum degrading potentials of single and mixed microbial cultures isolated from rivers and refinery effluent in Nigeria

P.O. Okerentugba and O.U. Ezeronye

Department of Microbiology University of Port Harcourt Choba, Port Harcourt, Nigeria.

*Corresponding author: E-mail: [email protected]. 

Abstract

The ability of three bacterial isolates (Bacillus spp, Micrococcus spp and Proteus spp.) and some fungal species (Penicillin spp., Aspergillus spp. and Rhizopus spp.) isolated from two rivers and refinery effluent to degrade two Nigerian Crude oils was studied. The results showed changes in pH, optical density and total viable count for the bacterial isolates after a 17-day period. There was an increase in biomass for the fungal isolates after a 35-day period. It was observed that these organisms were able to utilize and degrade the crude oil constituents, with bacterial isolates showing increase in cell number and optical density as pH decreases. Single cultures were observed to be better crude oil degraders than the mixed cultures (bacteria or fungi). It was also observed that oil degraders could be isolated from a non-oil polluted environment, although those from oil-polluted environments have higher degradation potentials.

Key words: Petroleum, refinery, biodegradation, plasmids, effluent.

Drilling fluid base oil biodegradation potential of a soil Staphylococcus species

C. O. Nweke¹ and G. C. Okpokwasili*

Department of Microbiology, University of Port Harcourt, P. M. B. 5323, Port Harcourt, Nigeria.

*Corresponding Author: E-mail:  [email protected]. 

¹Present address: Department of Biological Sciences, Federal University of Technology, P.M.B.1526, Owerri, Nigeria.

Abstract 

Staphylococcus sp. isolated from oil-contaminated soil was grown in 1% drilling fluid base oil, HDF- 2000, as a sole source of carbon and energy. The organism has strong affinity for the substrate, growing at the rate of 0.16 h-1. It uses adherence and emulsification as mechanisms for oil uptake. In a nutrient-rich marine broth, base oil (up to 2.0% v/v) and glucose (up to 1.6% w/v) have no significant effect on the growth rates. This showed that the Staphylococcus sp. is a strong primary utilizer of the base oil and has potential for application in bioremediation processes involving oil-based drilling fluids.

Key words: Drilling fluid base oil, Staphylococcus sp., biodegradation.

Enzyme activity of a Phanerochaete chrysosporium cellobiohydrolase (CBHI.1) expressed as a heterologous protein from Escherichia coli

Howard R.L. ¹*, Masoko P. ¹ and Abotsi E. ²

¹Microbiology, School of Molecular and Life Sciences, University of the North, P/Bag X1106, Sovenga, 0727, South Africa 

²Biochemistry, School of Molecular and Life Sciences, University of the North, P/Bag X1106, Sovenga, 0727, South Africa.

Corresponding author: E-mail: [email protected],  Tel/fax +27 15 2682862.

Abstract 

The aim of this study was to produce a secreted, heterologously expressed Phanerochaete chrysosporium cellobiohydrolase (CBHI.1) protein that required no in vitro chemical refolding and to investigate the cellulolytic activity of the clone expressing the glutathione S-transferase (GST) fused CBHI.1 protein.   Plate enzyme activity screening of E. coli cells transformed with pGEXcbhI.1 vector on carboxy-methyl-cellulose (CMC) produced several clones which produced clearing zones on CMC when induced.  A randomly selected representative pGEXcbhI.1 clone produced hydrolysis on both Avicel and CMC when induced. Crude protein extracts obtained from the induced pGEXcbhI.1 clone exhibited time dependent enzymatic activity against both CMC and Avicel.

Key words: Phanerochaete chrysosporium, cellobiohydrolase, cellulase activity, heterologous expression.

Effect of ripening on the composition and the suitability for jam processing of different varieties of mango (Mangifera indica)

Germain Kansci¹*, Benoit Bargui Koubala¹, Israel Mbome Lape²

¹University of Yaounde I, Department of Biochemistry, PO Box 812 Yaounde, Cameroon.

²Food and Nutrition Research Centre, Ministry of Scientific and Technical Research, Yaounde, Cameroon.

Corresponding author; E-mail: [email protected],  Fax: 00 33 (2) 40 67 50 84. Present address: INRA/LEIMA, B.P. 71627, F44316 Nantes cedex 03, France.

Abstract 

As part of an effort to solve the problem of post harvest losses of fruits, physicochemical characteristics of four mango varieties (Palmer, Améliorée, Mango and Keitt) were determined at two ripening stages. Their suitability for jam processing was also evaluated based on viscosity measurements. The pulps of pre-ripe mangoes were highly acidic (pH: 3.50 – 3.85), rich in starch (4.4 – 11.1 % w/w) as well as in dry matter. They contained less soluble sugars (4.04 – 7.56 g/100 g) and recorded lower viscosity values than those of the ripe mangoes. The pre-ripe Palmer and Améliorée mango varieties had high dry matter content, while the Mango and Améliorée varieties had higher soluble sugars contents. Due to their higher starch contents, all the jams prepared with pre-ripe mangoes were more viscous than the ripe mango preparations. Ripe Palmer and Améliorée varieties were the best for jam processing, based on their viscosity values. These results could help to improve the quality of mango jams.

Key words: Mango, proximate analysis, ripening stage, jam processing.

Response of Tripanosoma brucei brucei–induced anaemia to a commercial herbal preparation

Patrick O Erah¹*, Canice C Asonye² and Augustine O Okhamafe¹

¹Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, Nigeria.

²Department of Biochemistry, Faculty of Science, University of Benin, Benin City, Nigeria.

*Correspondence author: E-mail: [email protected]  or [email protected],  Tel: 234 52 600638, Fax: 234 52 602257.

Abstract 

Jubi Formula® is a herbal preparation made from three medicinal herbs (Parquetina nigrescens, Sorghum bicolor and Harungana madagascariensis). It has been reported to have been successfully used in the treatment of anaemia in humans. A study was therefore carried out to determine the effect of the preparation on packed cell volume (PCV) and haemoglobin (Hb) concentrations in anaemic rabbits. The PCV and Hb concentrations of healthy rabbits infected with Trypanosoma brucei brucei were monitored for 49 days. T. b. brucei produced a significant reduction in PCV and Hb concentrations in all infected rabbits when compared with the controls (p<0.05). These hematological parameters were restored to normal levels in the anaemic rabbits by the herbal preparation. The anaemic rabbits not treated with the herbal preparation presented with a progressive decline in their PCV and Hb concentrations and majority of them died before the end of the study.  Healthy rabbits that received daily doses of the herbal preparation showed gradual elevation in PCV and Hb concentrations which were maintained within normal range. Jubi Formula® can restore the PCV and Hb concentrations in anaemic conditions and is a potential substitute for blood transfusion. However, further studies are needed to investigate the potentials of the herbal preparation in reversing anaemia.

Key words: Anaemia, PCV, rabbits, haemoglobin, herbal preparation.

The influence of African Herbal Formula on the haematological parameters of trypanosome infected rats

Okochi VI¹, Okpuzor J²*, Okubena MO³, Awoyemi AK⁴

¹ Department of Biochemistry, University of Lagos, Akoka, Yaba, Lagos, Nigeria.

² Department Of Cell Biology and Genetics, University of Lagos, Akoka, Yaba, Lagos, Nigeria.

³ Bena Farms Limited, Ijebu-Ode, Ogun State, Nigeria.

⁴ Samaritan Spiritual Healing Home, Ibadan, Oyo State, Nigeria.

*Corresponding Author: E-mail:[email protected]. 

Abstract 

A herbal mixture of herbs code named African Herbal Formula (AFH) influenced the state of anaemia in trypanosome infected rats. Observations showed that the formula has an effect on the haemopoietic system manifested by a positive increase in the levels of haemoglobin, packed cell volume and red blood cell while the white blood cell and lymphocyte levels were decreased. AHF also delayed the proliferation of the parasites and improved the level of the characteristic weight loss associated with trypanosomiasis.

Key words: African Herbal Formula, trypanosomiasis, anaemia.

In vitro trypanocidal effect of methanolic extract of some Nigerian savannah plants

S.E. Atawodi¹*, T. Bulus¹, S. Ibrahim¹, D.A. Ameh¹, A.J. Nok¹, M. Mamman², M. Galadima³

¹Biochemistry Department, Ahmadu Bello University, Zaria, Nigeria.

²Veterinary Physiology and Pharmacology Department, Ahmadu Bello University, Zaria, Nigeria.

³Microbiology Department, Ahmadu Bello University, Zaria, Nigeria.

*Correspondence author; E-mail: [email protected],  Tel: +234-69-550 837.

Abstract 

Methanol extracts from twenty three plants harvested from the Savannah vegetation belt of Nigeria were analyzed in vitro for trypanocidal activity against Trypanosoma brucei brucei and Trypanosoma congolense at concentrations of 4 mg/ml, 0.4 mg/ml and 0.04 mg/ml. Extracts of Khaya senegalensis, Piliostigma reticulatum, Securidaca longepedunculata and Terminalia avicennoides were strongly trypanocidal to both organisms while extracts of Anchomanes difformis, Cassytha spp, Lannea kerstingii, Parkia clappertioniana, Striga spp, Adansonia digitata and Prosopis africana were trypanocidal to either T. brucei brucei or T. congolense. These findings provide evidence of the effects of some plants in the traditional management of trypanosomiasis.

Key words: Savannah, medicinal plants, trypanocidal effects, trypanosomiasis, trypanosome, in vitro model.

Plasmid profile of Escherichia coli 0157:H7 from apparently healthy animals

Smith SI¹*, Aboaba OO², Odeigha P³, Shodipo K², Adeyeye JA³, Ibrahim A³, Adebiyi T¹, Onibokun H¹ and Odunukwe NN¹

¹Molecular Biology and Biotechnology Division, Nigerian Institute of Medical Research, P.M.B. 2013, Yaba, Lagos, Nigeria.

²Department of Microbiology, University of Lagos, Nigeria.

³Department of Cell Genetics, University of Lagos, Nigeria.

*Corresponding author; E-mail: [email protected],  Fax: 00 2341 862 865.

Abstract 

One hundred samples from healthy animals were screened for the presence of enterohaemorrhagic Escherichia coli 0157: H7 and 17 were positive for EHEC 0157:H7 after confirmation using serology kits. Antibiotic susceptibility patterns showed the isolates to be highly susceptible to the various antibiotics screened with a few showing multiple antibiotic resistance. The plasmid profiles revealed that 8/17 (47%) of the animal isolates harboured detectable plasmids ranging in size from 0.564 kb to >23 kb.

Key words: Escherichia coli, EHEC, animals, plasmid profile.

Larvaecidal effects of aqueous extracts of Azadirachta indica (neem) on the larvae of Anopheles mosquito

Aliero, B.L.

Department of Biological Sciences, Usmanu Danfodiyo University, Sokoto-Nigeria.

*Corresponding author;Tel.: 234-060-237970; e-mail: [email protected]. 

Abstract 

The effect of crude aqueous extracts of Azadirachta indica (neem) against the larvae of Anopheles mosquito was investigated. Exposure of the larvae to undiluted extracts of seed oil, leaf and bark for 12 hours led to 100, 98, and 48% mortality, respectively. Dilution of these extracts also resulted in mortality of the larvae. We suggest that the seed oil and leaf extract of neem contain properties that could be developed and used in the control of mosquitoes in the tropics.

Key words: Anopheles mosquito, neem, Azadirachta indica.