African
Journals Online
Transactions of the Zimbabwe
Scientific Association
ABSTRACTS (Vol 72)
Phenology and Mortality of Common
Woody Plants during and After severe Drought in
South-eastern Zimbabwe
CLIFFORD TAFANGENYASHA
Department of National Parks and Wild Life
Management, Private Bag 7003, Chiredzi, Zimbabwe
Abstract
The phenological patterns of 14 woody species that are
common components of deciduous woodland in a southern
African lowveld region were studied in the Gonarezhou
National Park, Zimbabwe. Biweekly assessments of the
number of leaf buds, young, mature and dead leaves,
flower buds, open flowers, unripe and ripe fruits showed
a gradual deterioration in the food supply in a season of
low rainfall. Production of vegetation followed a simila,
but less marked, pattern of environmental variation. The
tree population in the major vegetation types declined
because a large proportion of the woody species was
killed during the 1991-92 drought. This suggests that
climatic extremes are more important to plants than the
average conditions.
Quantitative Determination of
Proteins, Lipids and Ascorbic Acid in Indigenous Legumes
and Fruits of Zimbabwe.
T. DJAROVA, T. KUDANGA & F. CHIRIMBA
Department of Applied Biology and Biochemistry,
National University of Science and Technology, P 0 Box AC
939, Ascot, Bulawayo, Zimbabwe.
e-mail: [email protected]
Abstract
The nutritional profile of indigenous legumes and fruits
has been poorly documented. Indigenous legumes Arachis
hypogaea (ground nuts), Vigna subterranea
(round nuts), Vigna unguiculata (cow peas), Sticolobium
deeringianum (velvet beans) and fruits Adansonia
digitata (baobab), Flacourtia indica
(governor's plum), Azanza garckeana (snot apple), Strychnos
spinosa (sweet monkey orange) were collected and
dried, after which their protein, lipid and ascorbic acid
contents were determined. The protein content of the
legumes and fruits ranged from 4.10 to 9.60 % with the
highest value in snot apple, followed by governor's plum,
ground nuts and cow peas. Ground nuts were found to be
the richest source of lipids (mean = 45.97%) while lipids
were low in all the other legume and fruit samples (0.83
to 1.63 %). The level of ascorbic acid was highest in
baobab (mean = 578.29 mg per 100 g) and lowest in snot
apples (mean = 3.61 mg per 100 g). Among the other
legumes and fruits the vitamin C content ranged from
12.05 to 25.30 mg per 100 g. Indigenous legumes and
fruits in Zimbabwe are therefore important sources of
protein, lipid and ascorbic acid, and the regular intake
of these cheap and freely available food is well-advised
and may help in preventing severe malnutrition.
An Assessment of the Mineral Status
of Goats Under Smallholder Management
I.D.T. MPOFU, M.F. SIMOYI & L.R. NDLOVU,
University of Zimbabwe, Department of Animal
Science, P.O. Box MP 167, Mt Pleasant, Harare, Zimbabwe.
Abstract
Blood samples were collected from 40 goats, kept under
smallholder grazing conditions on natural veld at Sanyati
to ascertain their calcium, magnesium, phosphorus, iron,
selenium, zinc, copper and cobalt status. The goats were
deficient in phophorus throughout the year, marginally
deficient in magnesium and copper in the dry season while
calcium, sodium, iron, zinc, and selenium concentrations
were all above critical levels. the levels of phosphorus,
magnesium and copper were higher (P<0.01) in the rainy
season than in the dry season while calcium, selenium and
cobalt were higher (P<0.01) in the dry season. the
plasma levels of iron and copper was higher in kids
(P<0.05). Strategic supplementation of phosphorus,
magnesium and copper is therefore recommended for goats
in the Sanyati smallholder farming areas.
The Behaviour of the Ozone Layer
above Tropical Southern Africa.
P.F. CUNNINGHAM
Department of Physics, University of Namibia,
Private Bag 13301,Windhoek, Namibia
e-mail: [email protected]
Abstract
Recently released TOMS (total ozone mapping spectrometer)
data from NASA's Nimbus 7 satellite have been accessed
for the 14-year period between 1979 and 1992. Locations
in the Southern African tropics between latitudes 18o
and 23o south have been studied. Temporal and
location-related variations in total column ozone are
shown to be of major importance when compared with any
long-term declines.
The Effects of Temperature and
Dehydration on Renal Function in the Nile Crocodile, Crocodylus
niloticus Laurenti
J.P. LOVERIDGE and LORNA MAURER1
Department of Biological Sciences, University of
Zimbabwe, P.O. Box MP 167, Harare, Zimbabwe
e-mail: [email protected]
1.Present address: 54, Kennedy Drive, Greendale,
Harare
Abstract
Change of ambient temperature between 32ºC and 15ºC
reduced urine production of Crocodylus niloticus
from 1.15 to 0.27 cm3 kg-1 h-1,
the glomerular filtration rate from 5.21 to 2.21 cm3
kg-1 h-1, and the effective
renal blood flow from 24.21 to 4.60 cm3 kg-1
h-1. The tubular secretion of
phenolsulfonthalein was markedly depressed by
temperature, 20.2% of an injected amount being excreted
after 6h at 32ºC, but only 2.4% after 6h at 15ºC. Mild
dehydration (2.7% loss in body mass over 24 h) reduced
urine production from 1.15 to 0.17 cm3 kg-1
h-1 and the glomerular filtration rate
from 5.21 to 1.09 cm3 kg-1 h-1.
Mild dehydration had a small but statistically
insignificant effect on phenolsulfonthalein secretion.
Rapid Purification of High Activity
Taq DNA Polymerase Expressed in
Transformed E. coli cells
P. OTTINO1, A. MATIBIRI and A. MBAYA
Biotechnology Department, Tobacco Research Board, P.O.
Box 1909, Harare, Zimbabwe
1Present address: LSU Eye Center, 2020 Granier
St., New Orleans, LA70112-2234,USA
e-mail: [email protected]
Abstract
A simplified method is described here for the preparation
of a thermostable Taq DNA polymerase enzyme from Escherichia
coli (E. coli) strain DH5a carrying the pTTQ18
expression vector transformed with the Taq
polymerase gene. Standard purifications were done with 1
litre batch cultures of E. coli cells and produced
yields in excess of 100 000 units of Taq
polymerase. Optimal induction times with isopropyl
b-D-thiogalactopyranoside were determined at varying
times of 11, 14 and 18 hours and found to be optimal at
11 hours. Induction times greater than 11 hours resulted
in complete degradation of enzyme. The resulting enzyme
preparation from 11 hour incubation of E. coli cells
with IPTG gave a 94 kDa protein band on an 8%
SDS-polyacrylamide gel consistent with the size of
commercially available Taq polymerase.
The Effect of Sugars on Maturation
and Conversion of Geranium (Pelargonium
x hortorum Bailey) Somatic Embryos.
RUFARO. M. MADAKADZE1 T. SENARATNA2
and P. K. SAXENA2
1 Department of Crop Science, University
of Zimbabwe, P. Bag MP 167, Mount Pleasant, Harare,
Zimbabwe.
2 Department of Horticulture, University of
Guelph, Ontario, Canada, N1G 2W1
Abstract
The effect of various concentrations of sucrose and
glucose on maturation and conversion of geranium (Pelargonium
x hortorum Bailey) somatic embryos was
investigated at Guelph, Ontario, Canada in 1994 and 1995.
Somatic embryos were induced on medium with 20 M
thidiazuron for 3 days then matured on media with 3, 6
and 9 % sucrose or glucose, 21 days from the start of
culture. Glucose (6 %) and sucrose (6 and 9 %)
significantly improved maturation frequency of somatic
embryos compared to 3 % sucrose. Sucrose at 6 and 9 %
also reduced precocious germination of somatic embryos in
culture. Glucose at 3 and 6 % and sucrose at 6 and 9 %
both significantly increased protein content in somatic
embryos compared to 3 % sucrose. Only 3 % glucose
significantly improved conversion frequency while 6 %
sucrose and 9 % of both sucrose and glucose reduced
conversion frequency of somatic embryos. This study shows
the importance of inclusion of sugars in the maturation
of geranium somatic embryos.
|