Department of Biological Sciences

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Rate of oxidation and tissue concentrations of ethanol in mice
(Springer Nature, 1970-04-01) Thomas, H. M.
Inhibition of ethanol toxicity by lysine orotate (ORL)
(Wiley, 1970-04-16) Thomas, H M.
Studies on the Development and Establishment of Tapinanthus bangwensis1
(Oxford University Press, 1971) Onofeghara, F. A.
Tapinanthus bangwensis (Engler and K. Krause) Danser is not host-specific in the absolute sense. The pattern of development up to the production of the first two plumular leaves is essentially the same on any host. The parasite, however, shows a preference for some hosts but such preference is independent of any characteristics of the family or order to which the host belongs. Soon after contact with the host surface, the haustorium, the functional root of the parasite begins the penetration process The actual process of invasion is a rapid one and is hidden from view. The effects of crushing, disorganization, and disruption of host tissues that attend invasion point unequivocally to penetration by mechanical action. Considerable though these effects might be cessation of growth of the parasite-bearing host branch is neither early nor common.
Establishment of in vitro Cultures of Tapinanthus bangwensis (Engler and K. Krause) Danser and the Effects of Sugars on Growth1
(Oxford University Press, 1971-11-01) Onofeghara, F. A.
Culturing of organs in vitro has been successfully employed in studies on morphogenesis and nutritional requirements of parasitic and semi-paraaitic angiosperms. Tapinanthus bangwensis, a semi-parasite, has been successfully cultured on chemically defined media. By and large the parasite will thrive well in a medium of mineral salts and sucrose at its optimal concentration (4 per cent). However, the parasite is able to metabolize a wide range of sugars most of which show similar concentration optima Although the growth in vivo was simulated in vitro in the early stages, it was found that in the later stages growth in vitro was much slower than growth in vivo. The growth differences observed in the different media may reflect some of the physiological differences that are responsible for the selective nature of the parasite's development and establishment on different hosts
Studies on schistosomiasis in Sierra Leone—I
(Maney Publishing, 1971-12-01) Onabamiro, Sanya D.
The Effects of Growth Substances on the Growth of Tapinanthus bangwensis (Loranthaceae) in vitro
(Oxford University Press, 1972-06-01) Onofeghara, F. A.
The growth response of Tapinanthus bangwensis (Engler and K. Krause) Danser to exogenous growth substances, indole-3yl-acetic acid (IAA), kinetin, and gibberellic acid (GA3), not only varies with the concentrations of each of these substances in the medium but follows a similar trend in each case. Kinetin, IAA, and GA3 were found to enhance growth but not by very appreciable amounts, kinetin being the most effective growth promoter. High concentrations of these substances (5.0 and 10.0 ppm) except GA3 were toxic to the parasite. Gibberellic acid induced the production of accessory leaves at all the concentrations used. Kinetin was also effective in inducing accessory leaves but only at a concentration of 1.0 ppm. Some of the lower concentrations of the growth substances affected significantly some aspects of the parasite's growth and development. Nevertheless, the growth in vitro was still slower than that in vivo.
HISTOCHEMICAL LOCALIZATION OF ENZYMES IN TAPINANTHUS BANGWENSIS: ACID PHOSPHATASE
(Wiley, 1972-07-01) Onofeghara, F. A.
The distribution of acid phosphatase in the tissues of Tapinanthus bangwensis, a semiparasitic member of the Loranthaceae, and some of its hosts was studied. It has beer possible to work out convenient routine methods of pretreating tissues for histochemical enzyme localization, to modify, where necessary, conventional histochemical techniques for the localization of acid phosphatase, and to evaluate the azo-dye and metal-salt techniques at the optical level. Histochemical localization showed generally widespread activity and similarity in distribution for this enzyme in the parasite and host tissues. Although there is no direct correlation between these localizations and host-parasite relationships, the bearing that the localizations may have on such relationships is discussed in the light of the distributional evidence and the role usually ascribed to this enzyme.
Studies in schistosomiasis in Sierra Leone-II
(Maney Publishing, 1972-09-01) Onabamiro, Sanya D.
Studies on Pyricularia oryzae Cav. in Sierra Leone: Morphological and Physiological Variability of Some Isolates
(Oxford University Press, 1973) Onofeghara, F. A.
The morphological and physiological variability of six isolates of Pyricularia oryzae, the causal organism of rice blast disease, were investigated. The rate of growth, colony characters, and time of sporulation were found to vary with the different isolates though not by appreciable amounts. Each of the isolates showed consistently better growth on Takahashi's B medium than on Czapek-Dox's medium although the growth trend was the same in both media. The colony characters developed by each isolate are not dependent on the medium on which it is growing—a pointer to the fact that such characters may be genetically controlled. Germination was faster in distilled water than in 2 per cent agar. All the isolates produced appresoria in vivo and in vitro; those produced in vivo were, however, considerably larger than those produced in vitro. On the basis of appresorial types, the isolates were found to fall into two physiological races—smooth-walled and rough-walled. Each isolate produced consistently only one appresorial type in vitro from the apical or basal cell of the conidium. The utilization of carbon and nitrogen compounds varied from one isolate to the other, carbon compounds being generally better utilized than nitrogen compounds. Pyricularia oryzae can metabolize a wide range of carbon compounds. However, mannose, sucrose, glucose, fructose, and maltose proved to be most suitable carbon sources. The variations in the utilization of the various carbon and nitrogen compounds seem to reflect inherent biochemical and physiological differences among the isolates.
The Effects of Photoperiod and Coconut Milk on the Growth of Embryos of Tapinanthus bangwensis in Culture
(Oxford University Press, 1973) Onofeghara, F. A.
The growth response of Tapinanthus bangwensis (Engler and K. Krause) Danser to photoperiodic treatment varies not only with the photoperiod but also with the composition of the culture medium. By and large, the parasite seems highly tolerant to a wide range of photoperiods. Nevertheless, consistent and significant promotary effects were only observed under a 12-h photoperiod. All other photoperiods (16 h, 8 h, and diffuse daylight) had either promotary or inhibitory effects on different aspects of the parasite's growth. The over-all pattern of growth, however, was the same in all cases. Various concentrations of coconut milk were found to exert different effects on the growth of the parasite, but all the concentrations used supported less growth than the basal medium alone.
Histochemical Localization of Enzymes in the Cucurbitaceae Acid Phosphatases
(Oxford University Press, 1974-03-01) Onofeghara, F. A.
Histochemical Localization of Alkaline Phosphatases and β-Glucosidases in Cucurbitaceae
(Oxford University Press, 1974-06-01) Onofeghara, F. A.
The distribution of alkaline phosphatases and β-glucosidases in the tissues of the stems of Colocynthls citrullus, Cucumis sativus and Cucurbita pepo was studied. There was similarity in the pattern of distribution for these two groups of enzymes and that of acid phosphatases. The activities of these enzymes varied not only from plant to plant but also from tissue to tissue. However both enzymes showed increasing activity with plant age and localization was correspondingly more restricted. The significance of these localizations is discussed.
Haematological studies on wild African elephants (Loxodonta africana)
(Wiley, 1978-08-01) White, P.T.
Various haematological parameters have been measured in a sample of wild African elephants from two game parks in Uganda. The results are compared with those of other authors for the African and Indian elephant and other mammals. No intersex differences were found to occur but calves (1–5 years) differed from the population as a whole in several respects. Some values varied with season and this may be attributed to the effect of dehydration during the dry season. A number of elephants from one of the parks had abnormally high red cell numbers and the possibility is considered that this may reflect an incidence of habitat induced cardiovascular disease.
Elephant blood haematology and chemistry
(Elsevier BV, 1980) Brown, I.R.F.
Value of laboratory germination and viability tests in predicting field emergence of Urena lobata L.
(Elsevier BV, 1981) Harris, P.J.C.
Seed viability, dormancy, and field emergence of Urena lobata L. in Sierra Leone
(University of the West Indies Press, 1981-07-30) Harris, P.J.C.
The percentage field emergence from seeds of two cultivars of Urena lobata L. sown as a fibre crop in Sierra Leone was found to be low. In the case of seeds from indigenous plants, poor emergence was primarily due to seed dormancy and was markedly improved by scarification. In contrast, a low percentage viability was the major cause of poor emergence from seeds of the introduced cv., 'Ex-Mokwa'. Although initially high the percentage viability of embryo from this cv. declined during development. The insect pest Dysdercus superstitiosus F. was implicated in the loss of embryo viability. The percentage field emergence from scarified seed of both cv was considerably less than the percentage viability determined in laboratory tests, indicating a significant failure of emergence due to environmental factors.
Dysdercusspp. as pests ofUrena Iobatain Sierra Leone
(Taylor & Francis, 1983-03-01) Harris, Phil J.C.
The status of Dysdercus superstitiosus (F.) and D. voelkeri Schmidt as pests of the jute‐substitute crop Urena Iobata L. in Sierra Leone is discussed. A significant correlation between the proportion of seeds with evidence of Dysdercus feeding and the proportion with non‐viable or abnormal embryos revealed these insects to be serious pests of U. Iobata seed crops. Damage is confined to the seeds and resulted in up to 70% non‐viability of seeds in some samples. The fibre yield is unaffected. Typical damage symptoms are described. Dysdercus adults migrated to U. Iobata cv. Ex‐Mokwa soon after the onset of flowering and remained throughout the period of seed production. High population densities were reached, and migration to later flowering varieties may have occurred. A wide range of alternative food sources enables Dysdercus populations to survive between successive U. Iobata crops. It is suggested that chemical control may be necessary for successful seed production.
Shoot-tip culture and subsequent regeneration in cowpea
(Elsevier BV, 1983-08-01) Sebastian, K.T.
The orang-utan in Sabah
(Cambridge University Press, 1986) Davies, Glyn
A survey of orangutans in Sabah, Borneo, which was carried out by the author and John Payne, resulted in an encouraging picture. In the primary forest of eastern Sabah alone, there are at least 4000 orangutans, but habitat destruction is fragmenting the population. Hunting is also common, especially in the central and western areas where orangutans are already scarce. Some orangutans are protected in conservation areas, but the future of the species outside these places depends on logging being carried out in a more conservation-oriented way. Among other things, we need to discover the size of primary-forest patches that need to be left in logged forest to support a viable population of orang-utans, which will be able to recolonize the logged forest as it regenerates.
Seed production of Urena lobata in Sierra Leone: Effect of sowing date
(University of the West Indies Press, 1986-01-30) Harris, F.J.C.
Seeds of Urena lobate L. cv. ‘Ex-Mokwa’ and a local strain termed ‘Indigenous’ were sown at four-weekly intervals from 1 May to 14 November. Some seed was set by all ‘Ex-Mokwa’ crops and by those ‘Indigenous’ crops clown on or before 18 September. Highest seed yield was obtained with 1 May sowings and was progressively lower with later sowing dates. A reduction in the period of vegetative growth before flowering was a major cause of reduced seed yield from late-sown crops. Results suggest that the onset of flowering is under photoperiodic control. U. lobata behaving as a short-day plant. Between May and July, sowing date had little effect on the date of flowering seed harvest of ‘Indigenous’ crops, although both flowing and harvest were delayed somewhat with ‘Ex-Mokwa’. Growth of late-sown crops was further reduced by crops unfavourable conditions of the dry season which prevented or seriously reduced seed production by crops sown in October or November.