Department of Zoology and Wildlife Conservation

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An albino bat Hipposideros ruber Noack, from Tanzania
(1974-05) Howell, Kim; Mainoya, J. R.
Dwarf Variety of Coconut, Cocos Nucifera (Palmae), a Hostplant for the African Armyworm, Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae)
(Cambridge University Press, 1981) Yarro, Jacob G.; Otindo, B. L.; Gatehouse, A. G.; Lubega, M. C.
The dwarf variety of coconut, Cocos nucifera L. (Palmae), was found to be eaten by the larvae of the African armyworm, Spodoptera exempta (Wlk.). The comparison of the armyworm infestation on the leaves of the coconut seedlings and the adjacent grass species revealed lower larval density and growth rate on coconut seedlings. This observation suggests that a small population of the African armyworm can survive and develop on the leaves of the dwarf variety of coconut.
The Current Status of the Rare Usambara Mountain Forest-Viper, Atheris Ceratophorus WERNER, 1895, Including A Probable New Record Of A. Nitschei Rungweensis BOGERT, 1940, And A Discussion Of Its Validity (Reptilia, Serpentes, Viperidae)
(1981-12) Rasmussen, Jens B.; Howell, Kim
The recent collecting of five specimens of Atheris ceratophorus WERNER, 1895, together with an examination of material already deposited in various museums documents new records outside the Usambara Mountains to which the species had been believed to be endemic. Lepidosis and hemipenial characters have been investigated and tabulated to give an impression of the intraspecific variation. The data of the new specimens provide some information on the natural history of this species. The validity of A. nitschei rungweensis is discussed and a probable new record is given.
Studies on the Littoral Ecology and Ecophysiology of Bostrychia Tenella (Vahl) J. Agardh (Rhodophyta, Ceramiales) in Tanzania [1982]
(1982) Mshigeni, K. E.; Mturi, Fatina A.
Life and Fertility Tables for Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae)
(Cambridge University Press, 1984) Yarro, Jacob G.
Laboratory reared populations of Spodoptera exempta (Wlk.) had higher net reproductive rate and capacity for increase on maize, Zea mais L. and star grass, Cynodon dactylon (L.) Pers. than on Kikuyu grass, Pennisetum clandestinum Chiov., Guinea grass, Panicum maximum Jacq. and Setaria plicatilis (Hochst.) Hack. These parameters were greatly influenced by the larval mortality, but in all cases they were greater than one demonstrating that S. exempta populations can multiply on all the host plants tested. Since no populations with stable age distributions are known for S. exempta the net reproductive rate is more appropriate than the capacity for increase in estimating its population growth.
Survival and Development of the African Armyworm Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae) on Some Grass Species (Graminae
(Cambridge University Press, 1984) Yarro, Jacob G.
At 25°C and 70% r.h. larvae of Spodoptera exempta develop faster and pass through five instars on star grass, Cynodon dactylon (L.); Pers. maize, Zea mais L.; and Kikuyu grass, Pennisetum clandestinum Chiov. whereas on guinea grass, Panicum maximum Jacq.; and Setaria plicatilis (Hochst.) Hack, the development is not only slower, but the larvae pass through six and seven instars, respectively. Samples of larvae reared on the former grass species suffer high mortality only at the first and the last instar stages so that the distribution of per cent mortality is U-shaped. On the latter host plants, the mortality during the first instar stage is equally high and continues through the subsequent instars with no obvious peak towards the end of the larval life. The samples on C. dactylon and Z. mais had much higher growth indices than those on P. maximum and S. plicatilis. C. dactylon is a preferred natural food plant of S. exempta in the field, and these investigations demonstrate its value and importance.
Tucker, J. et al. Expression of p21 proteins in Escherichia coli and stereochemistry of th nucleotide-binding site. EMBO J. 5, 1351-1358
(1986-06) Tucker, J.; Sczakiel, Georg; Feuerstein, Juergen W.; John, Jasson; Goody, Roger S.; Wittinghofer, Alfred
v-Ha-ras encoded p21 protein (p21V), the cellular c-Ha-ras encoded protein (p21C) and its T24 mutant form p21T were produced in Escherichia coli under the control of the tac promoter. Large amounts of the authentic proteins in a soluble form can be extracted and purified without the use of denaturants or detergents. All three proteins are highly active in GDP binding, GTPase and, for p21V, autokinase activity. Inhibition of [3H]GDP binding to p21C by regio- and stereospecific phosphorothioate analogs of GDP and GTP was investigated to obtain a measure of the relative affinities of the three diphosphate and five triphosphate analogs of guanosine. p21 has a preference for the Sp isomers of GDP alpha S and GTP alpha S. It has low specificity for the Sp isomer of GTP beta S. Together with the data for GDP beta S and GTP gamma S these results are compared with those obtained for elongation factor (EF)Tu and transducin. This has enabled us to probe the structural relatedness of these proteins. We conclude that p21 seems to be more closely related to EF-Tu than to transducin.
Characterisation of the metal-ion - GDP complex at the active sites of transforming and nontransforming p21 proteins by observation of the 17O-Mn superhyperfine coupling and by kinetic methods
(1987-01) Feuerstein, Juergen W.; Kalbitzer, Hans R.; John, Jasson; Goody, Roger S.; Wittinghofer, Alfred
Kinetic studies on the interaction of three Ha-ras-encoded p21 proteins with GDP and MgGDP have yielded values for the association (10(6)-10(7) M-1 s-1) and dissociation (10(-3)-10(-5) s-1) rate constants at 0 degrees C. Dramatic differences in the rate constants were not observed for the three proteins. Under non-physiological conditions (absence of Mg2+), the rate constant for GDP release was an order of magnitude faster for the viral protein p21v than for the cellular form p21c or the T24 mutant p21t, but this was reduced to a factor of about 3 in the presence of Mg2+. In all cases, there was an increase of about one order of magnitude in the rate of GDP release on removing magnesium. The binding affinities ranged from 5.7 X 10(10) M-1 for p21c to 1.3 X 10(11) M-1 for p21v. Electron paramagnetic resonance (EPR) measurements on Mn2+ bound together with stereospecifically 17O-labelled GDP showed direct coordination of a beta-phosphate oxygen to the metal ion with a superhyperfine coupling constant of 0.16-0.22 mT, but no interaction with the alpha-phosphate oxygens at the active site of all three proteins. The association constant of Mn(II) to p21 proteins in the absence of nucleotides was estimated to be greater than 10(5) M-1. In agreement with the EPR results, experiments on the metal ion dependence of the binding of thiophosphate analogs of GDP provided further evidence for the absence of direct coordination of the metal ion to the alpha-phosphate group. These results have been used to construct a model for the interactions of Mg X GDP with the active site of p21 proteins.
Further Evidence of Exogenous Processes Regulating the Population of Zebra in the Serengeti
(1988-03) Senzota, Ramadhani. B.M
Between 1970 and 1980 the population size of the migratory zebra in the Serengeti remained constant. During the same period the population of wildebeest, also a large migratory ungulate, increased in a manner compatible with existing ecological theories. Sinclair & Norton-Griffiths (1982) have produced evidence to suggest that predation pressure was the factor that prevented the zebra population from increasing. This paper presents further evidence, based on population structure, which shows that the size of zebra population should have increased.
Biological properties of Ha-ras encoded p21 mutants and mechanism of the autophosphorylation reaction
(1988-08) John, Jasson; Frech, Matthias; Wittinghofer, Alfred
Kinetic studies performed on p21H guanine nucleotide complexes with and without Mg2+ show that point mutations at positions 12, 59, and 61 each have a different effect on the rate of nucleotide dissociation. Double mutants with a combination of these amino acid substitutions reveal that the effects of each mutation on these kinetics are interactive (nonadditive) for positions 12 and 59 and approximately additive for the positions 12 and 61. The magnitude and direction of the effects seen are dependent on the nature of the nucleotide and whether or not the complexes contain Mg2+. All the mutants have reduced GTPase activity. It is also shown that the autophosphorylation reaction velocity is of first order with respect to the protein concentration and that this reaction is an intramolecular one, which takes place as a side reaction of the GTPase reaction. The autophosphorylation is not reversible under the experimental conditions. The covalently bound phosphate does not decrease the nucleotide-binding ability of the protein nor does it change the relative affinity of the protein for GTP versus GDP. The results are discussed in terms of the structural model and function of p21H.
Tadpoles of three frog species endemic to the forests of the Eastern Arc Mountains, Tanzania
(1988-12) Drewes, Robert; Altig, Ronn; Howell, Kim
The tadpoles of three poorly known endemic frog species from the forested mountains of the Republic of Tanzania are described: Arthroleptides martiensseni (Anura: Ranidae), Afrixalus uluguruensis (Hyperoliidae) and Leptopelis vermiculatus (Hyperoliidae). Natural history observations are included where possible.
Effect of Waterborne and Dietary Cadmium on Plasma Ions of the Teleost Oreochromis Mossamicus in Relation to Water Calcium Levels
(1989) Pratap, Harish B.; Fu, H.; Lock, R. A. C.; Bonga, Sjoerd W.
The effects of cadmium administered via ambient water or food on plasma ions of the African freshwater cichlidOreochromis mossambicus were studied for 2, 4, 14, and 35 days, in low calcium (0.2 mM) and high calcium (0.8 mM) water. In low calcium water, an environmentally relevant concentration of 10 g/L water-borne cadmium induced a significant and dramatic hypocalcemia on days 2 and 4. Recovery of plasma calcium was observed on days 14 and 35. Hypermagnesemia was observed on day 2, but normal levels were already found on day 4. In high calcium water adapted fish, the extent of hypocalcemia and hypermagnesemia was less pronounced than in fish from low calcium water. Water-borne cadmium caused no significant changes in plasma phosphate, sodium, potassium, or osmolality. On days 2 and 4, dietary cadmium (averaging 10 g Cd/fish/day) caused hypermagnesemia and hypocalcemia in low calcium wateradapted fish. Recovery was observed on days 4 and 14, respectively. In fish from high calcium water, dietary cadmium caused a significant reduction in plasma calcium on day 4 only; plasma magnesium was unaffected. Hyperphosphatemia was apparent on day 14, irrespective of the water calcium concentration. No changes in plasma sodium, potassium, or osmolality were found.The results show that sublethal concentrations of cadmium, administered via the water as well as via the food, affect calcium and magnesium metabolism in tilapia. High water calcium ameliorates the effects of both water and dietary cadmium on plasma calcium and magnesium levels.Among the various heavy metal pollutants, cadmium is frequently present in natural water bodies as a result of discharges from industrial processes or other anthropogenic contamination. The harmful effects of cadmium on mammals and other terrestrial animals have been widely studied and reviewed (Flicket al. 1971; Vallee and Ulmer 1972; Webb 1979; Korte 1983; Foulkes 1986). Aquatic vertebrates such as fish, live in very intimate contact with the environment through their gills. This makes them very susceptible to aquatic pollutants.Since it is well established that freshwater fish take up most of the ions necessary for homeostasis from the water via the gills (Eddy 1982), cadmiuminduced plasma ionic disturbances are apparently caused by impaired uptake and diffusional losses of ions via these organs (Larssonet al. 1981; Giles 1984). Ionic disturbances have also been reported after exposure of fish to sublethal concentrations of heavy metals. For example, changes in the plasma ionic composition have been observed in fish exposed to copper and zinc (Lewis and Lewis 1971; Spry and Wood 1985), mercury (Locket al. 1981), and chromium (Van der Putteet al. 1983). With respect to cadmium, exposure of rainbow trout to sublethal levels induced hypocalcemia, with reduced plasma sodium, potassium, chloride and increased plasma magnesium (Giles 1984). In European flounder, cadmium-induced hypocalcemia and elevated levels of plasma phosphate, magnesium and potassium were observed (Larssonet al. 1981).In addition to water, food could also be a source of cadmium for fish, since it accumulates in aquatic organisms through trophic transfers (Anonymous 1971; Williams and Giesy 1978; Coombs 1979). Indeed, Bryan (1976) concluded that food as a source of Zn, Mn, Co, and Fe for molluscs, crustaceans and fish was more important than water. From various studies on both water-borne and food-containing metals, reviewed by Dallingeret al. (1987), there is evidence that uptake of heavy metals such as Cd, Cu, Co, Pb, Hg, and Zn from food is also the predominant pathway in freshwater fish. Koyama and Itazawa (1977) reported significant hypocalcemia and elevated plasma phosphate levels in cadmium-fed carps. Similarly, plaice and thornback ray both accumulated more cadmium from food than from seawater (Pentreath 1977). In general, cadmium concentrations in natural waters are extremely low and a more important route of cadmium uptake by fish may be represented via the gut. Experiments with dietary cadmium may therefore yield more representative information for field situations.In this investigation, we have compared the effects of a sublethal concentration of cadmium administered via the water or via the food in the African cichlid fishOreochromis mossambicus (tilapia). Plasma ions and osmolality were determined. Cadmium was administered at sublethal concentrations, in the order of magnitude that may occur in natural waters (10 g Cd/L). In many studies aimed at evaluating the effects of cadmium on fishes, high concentrations (>1 mg Cd/L) of cadmium have been used. Hence severe physiological, behavioral and detrimental effects have been reported. Such high concentrations are rarely found in nature, except in cases of spillage or heavily polluted waters. The Working Group on Cadmium Toxicity (EIFAC 1977) has suggested that chronic exposure to low cadmium concentrations is more relevant to understanding the mechanisms involved in the intoxication process in teleost fish.We further studied the influence of relatively low and high calcium concentration of the water on the toxic effects of cadmium. The effects of water hardness (mainly Ca2+ and Mg2+ ions) on heavy metal toxicity have been demonstrated in various species of teleosts (Prtet al. 1985). Increased toxicity of cadmium to fish in soft water as compared to hard water has been demonstrated in catfish and guppies (Kinkade and Erdman 1975), goldfish (McCartyet al. 1978), striped bass (Palawskiet al. 1985), brook trout (Carrollet al. 1979) and rainbow trout (Calamariet al. 1980; Pascoet al. 1986). Similar observations on teleosts exposed to zinc, copper and lead (Sinleyet al. 1974; Zitko and Carson 1976; Judy and Davies 1979; Laurn and McDonald 1986) indicate a protective role of calcium against the toxic effects of heavy metals. It was also investigated whether the protective effect of the water-calcium concentration is limited to water-borne cadmium only, or also applies to dietary cadm Effect of waterborne and dietary cadmium on plasma ions of the teleost Oreochromis mossamicus in relation to water calcium levels (PDF Download Available).
A methodology for analyzing rare species distribution patterns utilizing GIS technology: The rare birds of Tanzania
(1989-01) Miller, Ronald I.; Stuart, Simon N.; Howell, Kim
A simple, straightforward, cartographic modelling technique is presented for measuring relations between environmental characteristics and rare species distribution patterns. This approach is corroborated by digitizing rare bird distribution data for Tanzania and statistically analyzing these patterns in relation to geographic and environmental variables. Of the available natural resource data for Africa, only the vegetation and soils data appeared accurate enough to represent regional natural resource distribution patterns. Available data for Tanzania at the regional scale is not currently precise or comprehensive enough to analyze ongoing dynamic ecological processes. Statistical relations, associated with a study quadrangle within Tanzania, are documented for these parameters. Final confirmation of the accuracy of predictions about rare species diversity patterns will ensue from future field observations. When confirmed, this methodology can be used for setting conservation priorities in biologically little known regions of the world.
Borasio, G.D. et al. ras p21 protein promotes survival and fiber outgrowth of cultured embryonic neurons. Neuron 2, 1087-1096
(1989-01) Borasio, Gian D.; John, Jasson; Wittinghofer, Alfred; Barde, Y. A.; Sendtner, Michael; Heumann, Rolf
Although evidence obtained with the PC12 cell line has suggested a role for the ras oncogene proteins in the signal transduction of nerve growth factor-mediated fiber outgrowth, little is known about the signal transduction mechanisms involved in the neuronal response to neurotrophic factors in nontransformed cells. We report here that the oncogene protein T24-ras, when introduced into the cytoplasm of freshly dissociated chick embryonic neurons, promotes the in vitro survival and neurite outgrowth of nerve growth factor-responsive dorsal root ganglion neurons, brain-derived neurotrophic factor-responsive nodose ganglion neurons, and ciliary neuronotrophic factor-responsive ciliary ganglion neurons. The proto-oncogene product c-Ha-ras also promotes neuronal survival, albeit less strongly. No effect could be observed with truncated counterparts of T24-ras and c-Ha-ras lacking the 23 C-terminal amino acids including the membrane-anchoring, palmityl-accepting cysteine. These results suggest a generalized involvement of ras or ras-like proteins in the intracellular signal transduction pathway for neurotrophic factors.
Crystallization and preliminary X-ray analysis of the human c-H-ras-oncogene product p21 complexed with GTP analogues
(Elsevier, 1989-03) Scherer, Anna; John, Jasson; Linke, Rosita; Goody, Roger S.; Wittinghofer, Alfred; Pai, Emil F.; Homes, K. C.
The catalytic domain (amino acid residues 1 to 166) of the human ras-oncogene product p21 complexed with the GTP analogues beta,gamma-imido-GTP (GMPPNP), beta,gamma-methylene-GTP (GMPPCP), and guanosine-5'-(gamma-thiotriphosphate) (GTP gamma S) have been been crystallized. Crystals of the GMPPNP and GMPPCP complexes are well suited for high resolution X-ray crystallography. They belong to space group P3(1)21 (or its enantiomorph P3(2)21) with unit cell axes a=b=40.3 A and c = 162.2 A.
Effects of Water-borne Cadmium on Plasma Cortisol and Glucose in the Cichlid Fish Oreochromis Mossambicus
(1990) Pratap, Harish B.; Bonga, Sjoerd W.
1.1. Freshwater cichlids Oreochromis mossambicus (tilapia) were exposed to 10 μg Cd/l in ambient water for 2,4, 14 and 35 days. Plasma cortisol and glucose levels were determined to evaluate if cadmium induced a typical stress response in these fish.2.2. Exposure to cadmium for 2, 4 and 14 days elicited a significant elevation of plasma cortisol levels.3.3. A significant hyperglycemia occurred on days 2 and 4 in cadmium-exposed fish.4.4. During long-term exposure to cadmium (35 days), the plasma cortisol and glucose levels returned to control values. This recovery after 35 days indicates the ability of tilapia to adapt to low cadmium concentrations in the ambient water.
The Feeding Ecology and Behavior of the Red Colobus Monkey (Colobus Badius Kirkii)
(1991) Mturi, Fatina A.
Diurnal Activity of Elephants in Ngorongoro Crater, Tanzania
(Wiley, 1993) Kabigumila, Jonathan D.
Ecology of the Zanzibar Red Colobus Monkey, Colobus Badius Kirkii (Gray, 1968), In Comparison With Other Red Colobines
(Cambridge University Press, 1993) Mturi, Fatina A.
Effect of Ambient and Dietary Cadmium on Pavement Cells, Chloride Cells, and Na+/K+-Atpase Activity in the Gills of the Freshwater Teleost Oreochromis Mossambicus at Normal and High Calcium Levels in the Ambient Water
(Elsevier, 1993) Pratap, Harish B.; Bonga, Sjoerd W.
The effects of cadmium on the gills of the African freshwater cichlid Oreochromis mossambicus in water with normal and relatively high calcium concentrations were studied for periods up to 35 days. The exposure was either through the ambient water or via the diet. Changes in the ultrastructure of the gill epithelium upon exposure to cadmium in the ambient water indicated degeneration of pavement cells and chloride cells, and acceleration in the turnover of the chloride cells. Studies of the Na+/K+-ATPase activity of the gills indicated that a transient increase in the total number of chloride cells was not associated with an increase, but rather a decrease of the total ion-exchange capacity of the chloride cells. Macrophages, lymphocytes, rodlet cells and neutrophilic granulocytes infiltrated the filament epithelium. Recovery of the gills was observed after 35 days. Dietary cadmium caused similar, although delayed, effects. High water calcium concentration reduced the impact of water-borne cadmium, but had no ameliorating effect on dietary cadmium. The data indicate that the disturbance of ion regulation in fish caused by sublethal levels of dietary cadmium is the result of effects of the metals on the gills rather than on the kidney.

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