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Effect Of Variable Transmission Rate On The Dynamics Of Hiv In Sub-Saharan Africa, Diego F. Cuadros, Phillip H. Crowley, Ben Augustine, Sarah L. Stewart, Gisela García-Ramos

Biology Faculty Publications

BACKGROUND: The cause of the high HIV prevalence in sub-Saharan Africa is incompletely understood, with heterosexual penile-vaginal transmission proposed as the main mechanism. Heterosexual HIV transmission has been estimated to have a very low probability; but effects of cofactors that vary in space and time may substantially alter this pattern.

METHODS: To test the effect of individual variation in the HIV infectiousness generated by co-infection, we developed and analyzed a mathematical sexual network model that simulates the behavioral components of a population from Malawi, as well as the dynamics of HIV and the co-infection effect caused by other infectious diseases, …

Importance Of Behavior And Morphological Traits For Controlling Body Temperature In Littorinid Snails, Luke Miller, Mark Denny

Faculty Publications, Biological Sciences

For organisms living in the intertidal zone, temperature is an important selective agent that can shape species distributions and drive phenotypic variation among populations. Littorinid snails, which occupy the upper limits of rocky shores and estuaries worldwide, often experience extreme high temperatures and prolonged aerial emersion during low tides, yet their robust physiology—coupled with morphological and behavioral traits—permits these gastropods to persist and exert strong grazing control over algal communities. We use a mechanistic heat-budget model to compare the effects of behavioral and morphological traits on the body temperatures of five species of littorinid snails under natural weather conditions. Model …

Influence Of Agricultural Stream Habitat Alterations On Mosquitoes And Amphibians: Patterns, Processes, And Predictions, Julia Sonn

Biology Theses

Changes to stream structure, riparian habitat, and water quality can alter ecosystem dynamics, resulting in an increase in mosquitoes, while weakening populations of amphibians. Therefore, it is necessary to understand how these components are affected by agricultural practices so that mosquito populations can be controlled and aquatic organisms can be protected. In this study, I examined changes in stream structure by measuring geomorphology at three riparian habitats that were anthropogenically impacted to varying degrees. I also compared water quality between the habitats. Mosquitoes and amphibians were surveyed at each riparian habitat, identified to species, and abundances were compared. Stream structure …

Habitat Use And Population Densities Of Rain Forest Chameleons In The East Usambara Mountains Of Tanzania [Poster], Philip Shirk, David A. Patrick, James R. Vonesh, Kim Howell

Biology Presentations

Conclusions:

• Chamaeleo dilepis and Ri. brevicaudatus are absent from forest at this elevation (852-1103m), while K. matschiei, K. vosseleri, K. tenuis, and R. spinosus are relatively scarce in the forest. Trioceros deremensis and R. temporalis are common, but density varies greatly.
• The endemic and scarce K. matschiei and K. vosseleri may be of concern given their scarcity in forest habitat. Density estimates in other habitat types are needed to determine status.
• For accurate density estimates, it is important to consider seasonal variation in density and animals too high to be observed in surveys.

Optimized Production Of Lignin Peroxidase, Manganese Peroxidase And Laccase In Submerged Cultures Of Trametes Trogii Using Various Growth Media Compositions, F. Patrick, G. Mtui, A. M. Mshandete, A. Kivaisi

Tanzania Journal of Science

A white-rot fungus, Trametes trogii, was isolated from coastal Tanzania and screened for crude lignolytic enzymes production using Rhemazol Brilliant blue R (RBBR) dye, 2,2-azino-bis (3-ethylbenzthiazoline)-6-sulfonate (ABTS) and guaiacol in a semi-solid medium. Lignin peroxidase (LiP), manganese peroxidase (MnP) and Laccase (Lac) were detected by pyrogallol and !- napthol solutions, respectively on the guaiacol supplemented solid media. The effect of temperature, pH, carbon, nitrogen, Cu2+, 2,5-xylidine, ferulic acid, varatryl alcohol and Mn2+ in submerged culture fermentations were investigated for maximum enzymes production. After 7 days of incubation, 72-100% oxidation of RBBR, ABTS and guaiacol was observed. With optimized culture conditions, …

Phylogenetic Relationships Of The Metazoan Parasites Of The Clariid Fishes Of Lake Victoria Inferred From Partial 18s Rdna Sequences, C. J. Mwita, G. Nkwengulila

Tanzania Journal of Science

Phylogenetic relationships among twenty two metazoan parasites recovered from seven species of clariid fish from Lake Victoria were analysed using partial 18S rDNA sequences. The 18S rDNA gene was amplified by polymerase chain reaction, directly sequenced, aligned and phylogenies inferred using maximum parsimony. Heuristic bootstrap MP searches yielded one most parsimonious tree (CI = 61%, HI = 39%), which showed that clariid parasites are monophyletic at higher taxonomic levels (Cestodea, Nematodea, Digenea and Crustacea). However the position of two trematodes (Allocredium mazoensis and Clinostomum sp.) and a nematode (Contracaecum sp.) were not stable. Despite the present findings, the study utilised …

Urban Dietary Heavy Metal Intake From Protein Foods And Vegetables In Dar Es Salaam, F. N. Ngassapa, O. C. Othman, E. Elisante

Tanzania Journal of Science

Contamination of food and food products by heavy metals has made dietary intake as one of the major routes of these harmful elements to human beings. The human dietary intake of heavy metals cadmium, copper, lead and zinc from protein-foods (beans, meat, fish, milk) and green vegetables consumed daily from restaurants and street food-vendor kiosks in Dar es Salaam were determined using the Total Diet Study (TDS) method. The cooked food was bought from the restaurants and street food-vendors at several city locations (i.e. Buguruni, Manzese, Mwenge, Temeke and Ubungo) over several months and analyzed. Heavy metal concentrations were determined …

Geomorphological Potential Of Coelacanth Habitat Across Mozambique-Tanzania Border, N. Nyandwi

Tanzania Journal of Science

The coelacanth is a new fish in Tanzania. It was first discovered in September 2003 after it was spotted by a tourist in a fish market. It was caught by fishermen in the deep waters off Songo Mnara Island offshore of Kilwa Masoko Town in Southern Tanzania. The find potentially added southern Tanzania to the list of known coelacanth areas of the southern Western Indian Ocean Region. Observed current conditions indicate that the waters are swept by strong (2 m/sec) northward flowing current. This suggests that there must exist hideouts for the fish, such as caves in canyons and overhangs. …

A Phylogenetic Study Of The Old World Asclepiadinae (Apocynaceae) Based On Chloroplast And Nuclear Dna Sequence Data, David Chuba

Dissertations and Theses

Relationships within the African Asclepias generic complex (Asclepiadinae, Apocynaceae) have for a long time been only a matter of intuitive speculation and generic delimitations have been diverse and rather contentious. Generic delimitation in this group has been based on morphological characters that are usually not exclusive to any particular clade or genus. The difficulty of identifying taxonomically useful morphological characters for inferring generic delimitations has led to differences in the emphasized characters by different taxonomists. This study is aimed at understanding phylogenetic relationships of species within the African Asclepias complex based upon the nuclear PgiC and three chloroplast DNA regions, …

Serotonin Immunoreactive Cells And Nerve Fibers In The Mucosa Of The Rat Stomach, A P Gesase

Tanzania Journal of Science

The current study has showed the morphological features of serotonin (5-hydroxytryptamine) immunoreactivity in the pyloric mucosa of the rat stomach. The immunoreactive elements included the endocrine cells, mast cells and mucosal nerve fibers in the lamina propria. The immunopositive endocrine cells were oval in shape and located mostly in the basal part of the gastric glands. The cell contained a central non-staining area and the peripheral staining zone. The mast cells stained homogenously and appeared to be oval-round in shape. They were located in the upper, middle and basal parts of the mucosa. Serotonin immunoreactive nerve fibers with varicosities were …

Morphological Features Of Tyrosine Hydroxylase Immunoreactive Cells In The Mouse Islets Of Langerhans, A P Gesase, Y -I Satoh

Tanzania Journal of Science

The current immunohistochemical study used the antibody against tyrosine hydroxylase (TH) to observe the immunoreactive elements in the mouse pancreas. The results indicated the presence of immunoreactive nerve fibers and endocrine cells. The immunopositive nerve fibers appeared as thick and thin bundles; thick bundles were seen to run along the blood vessels giving out fine fibers to the wall. Varicose nerve fibers were seen in the islets of Langerhans and also in close association with the exocrine endpieces. The TH immunoreactive cells were oval-round in shape and some showed the central non-staining area and the dense staining peripheral zone. More …

Involvement Of Methyltransferases Enzymes During The Energy Metabolism Of The Anaerobic Archaeon Methanosarcina Semesiae Sp. Nov., Tj Lyimo

Tanzania Journal of Science

The methyl group transfer from dimethylsulfide (DMS), trimethylamine and methanol to 2-mercaptoethanesulfonic acid (coenzyme M) were investigated from cell extracts of Methanosarcina semesiae sp. nov. to evaluate whether the enzyme systems involved were constitutive or inductive. The extracts from cells grown on DMS exhibited methanogenic activity exclusively with DMS and methanethiol. Likewise when cells were pre-grown on trimethylamine or methanol the extracts only produced methane from the respective metaboilic substrate. Dimethylsulfide:methyl-coenzyme M transferase activity was dependent on ATP, but hydrogen did not stimulate activity. The fact that ATP could be replaced by the reductant Ti(III)-citrate indicates that reductive activation of …

Delineating The Jurassic To Mid Cretaceous Part Of The Pacific Apparent Polar Wander Path, Dcp Masalu

Tanzania Journal of Science

The Jurassic to Mid-Cretaceous apparent polar wander path of the Pacific plate irrespective of ages have been delineated. Two poles have been established: one pole, which is relatively older than the other, is at 75.01°N/287.5°E (α = 6.9°) and the other pole is at  61.0°N°/304.7°E (!95 = 4.5°). These results indicate that the Pacific plate drifted southward during the Jurassic to Early-Cretaceous period. Additionally, the results demonstrate that there is an apparent consistent correspondence between changes of plate motion and significant shifts of the Jurassic to Mid-Cretaceous apparent polar wander path

Occurrence Of Digenean Larvae In Freshwater Snails In The Ruvu Basin, Tanzania, G. Nkwengulila, E. S. P. Kigadye

Tanzania Journal of Science

A survey was carried out on digenean larvae infecting freshwater snails in five habitats in Dar es Salaam, Ruvu and Morogoro. 9424 snails belonging to 12 species from five families were examined for digenean infection from July 1996 – June 1997. 20 morphologically distinguishable cercariae were recovered. Multiple infections were not recorded. While the general prevalence of digeneans in snails was low (3.5%), variations occurred between seasons, among habitats and snail host species. Prevalence was high during the dry season but low in the rain season. Among habitats, highest prevalence was recorded at Kinondoni pond and lowest at Ruvu ponds, …

Abundance And Diversity Of Seagrass And Macrofauna In The Intertidal Areas With And Without Seaweed Farming Activities In The East Coast Of Zanzibar, Thomas J Lyimo, Esther F Mvungi, Yunus D Mgaya

Tanzania Journal of Science

The diversity and abundance of seagrass and associated macrofauna were studied in transects with and without seaweed farms at Chwaka Bay and Jambiani, in the East Coast of Zanzibar. Eight seagrass species, namely Cymodocea rotundata, Cymodocea serrulata, Thalassia hemprichii, Thalassodendron ciliatum, Syringodium isoetifolium, Halodule uninervis, Halophila ovalis and Enhalus acoroides were recorded in the transects. The mean total biomass of seagrass at Chwaka Bay ranged from 142.4 ± 70.71 to 1652 ± 772.7 g dw/m2 and 212.9 ± 146.2 to 1829 ± 1692 g dw/m2 in station with and without seaweed farms, respectively. At Jambiani, the mean total biomass ranged …

A New Species Of Giant Sengi Or Elephant-Shrew (Genus Rhynchocyon) Highlights The Exceptional Biodiversity Of The Udzungwa Mountains Of Tanzania, F Rovero, G B. Rathbun, A Perkin, T Jones, David O. Ribble, C Leonard, R R. Mwakisoma, N Doggart

Biology Faculty Research

A new species of sengi, or elephant-shrew, is described. It was discovered in the northern Udzungwa Mountains of Tanzania in 2005. Sengis (Order Macroscelidea, super-cohort Afrotheria) include four genera and 15 species of mammals that are endemic to Africa. This discovery is a significant contribution to the systematics of this small order. Based on 49 camera trap images, 40 sightings and five voucher specimens, the new sengi is diurnal and distinguished from the other three species of Rhynchocyon by a grizzled grey face, pale yellow to cream chest and chin, orange-rufous sides, maroon back and jet-black lower rump and thighs. …

Assessment Of Fecal Bacteria Contamination In Sewage And Non-Sewage Impacted Mangrove Ecosystems Along The Coast Of Dar Es Salaam, A. A. Abbu, Thomas J. Tj Lyimo

Tanzania Journal of Science

Microbiological quality of the intertidal pool water was evaluated in sewage impacted (Mtoni Kijichi) and non-sewage impacted (Rasi Dege) mangrove forest sites along the coast of Dar es Salaam, Tanzania. The Most Probable Number method was used for estimating the total coliform (TC), fecal coliform (FC) and fecal enterococci (ENT) levels. In addition, physicochemical parameters (temperature, pH, salinity and nutrients) were measured. The results for microbial fecal indicators were compared to the World Health Organisation (WHO) and United States Environmental Protection Agency (USEPA) guidelines for marine recreational and shellfish harvesting waters. Fecal bacteria contamination was significantly higher at Mtoni Kijichi …

Characteristics And Dyes Biodegradation Potential Of Crude Lignolytic Enzymes From White-Rot Fungus Crepidotus Variabilis Isolated In Coastal Tanzania, G. Y. S. Gys Mtui

Tanzania Journal of Science

Lignocellulosic enzymes from Crepidotus variabilis collected from mangrove forests of coastal Tanzania were investigated by using standard methods, and their ability to degrade aromatic compounds were elucidated. The fungal crude enzyme filtrates had maximum laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP) activities of 70 U/mL, 16 U/mL and 8, U/mL respectively. The crude enzyme extracts were able to oxidize rhemazol brilliant blue-R (RBB-R) dye, phenol, "-naphthol and pyrogallol. Also, they could remove up to 58% and 92% color from raw textile effluent and aromatic dyes, respectively, after 14 days of incubation at 30ºC and pH 4.5. Desalted and …

Chemical Constituents And Biological Activity Of Three Tanzanian Wild Mushroom Species, L.D. Baraza, C. C. Joseph, M. J. Moshi, M. H. H. Nkunya

Tanzania Journal of Science

The three Tanzanian wild mushroom species Termitomyces letestui, Lactarius edulis and Agaricus sp. aff. arvensis yielded ergosterol, 5,8-peroxyergosterol and ergosta-5,22-dien-3β-ol, and a mixture of ergosterol, ergosta-7,22-dien-3β-ol and ergosta-7-en-3β-ol whose composition was deduced from gas chromatography/mass spectroscopic (GC/MS) analysis of the trimethysilylated mixture. GC/MS analysis of the lipid fraction from T. letestu revealed the presence of linoleic (C18:2), stearic (C18:0), oleic (C18:1), palmitic (C16:0), pentadecanoic (C15:0) and myristic (C14:0) acid. Polar T. letestui and L. edulis fractions yielded α,α,1'trehalose andmannitol. Some of the crude extracts from the three mushroom species showed mild antimicrobial, mosquito larvicidal and cytotoxic activities. The chemical composition …

Effect Of High Pressurized Carbon Dioxide On Escherichia Coli, I. P. Bateebe, O Kibazohi

Tanzania Journal of Science

Carbon dioxide at high pressure can retard microbial growth and sometimes kill microorganisms depending on values of applied pressure, temperature and exposure time. In this study the effect of high pressurised carbon dioxide (HPCD) on Escherichia coli was investigated. Culture of E. coli was subjected to high pressurised carbon dioxide at 15, 25 and 35 bar, and varying exposure times of 20, 40, 60 and 90 minutes at room temperature (27 oC). Microbial inactivation increased with pressure and exposure time. For the first 20 minutes reduction of viable microbial cells was 18%, 30% and 36% at 15, 25 and 35 …

Species Richness And Abundance Of Large Mammals In Zaraninge Forest, Coast Region, Tanzania, H. Y. D. Kiwia

Tanzania Journal of Science

A study on the large mammals of Zaraninge Forest was conducted using the line transect method between 1995 and 2001. They comprised 16 species from 7 families, including Bovidae (5), Canidae (1), Cercopithecidae (4), Felidae (1), Galagonidae (2), Orycteropodidae (1) and Suidae (2). Only nine species of primates and antelopes were encountered frequently enough for densities to be estimated. A total of 404 sightings from 40 counts were recorded, the majority being for blue monkey (34.9%) and Angolan colobus (26.0%). For galagos, 210 sightings from 58 counts were recorded, the majority being for Rondo galago (62.2%). Absolute density (individuals km-2) …

Species Richness And Abundance Estimates Of Small Mammals In Zaraninge Coastal Forest In Tanzania, H. Y. D. Kiwia

Tanzania Journal of Science

A study on small mammals (<2 kg) was conducted in Zaraninge Forest, Coast Region, Tanzania, in the dry and wet seasons from 1994 to1996. The forest was found to harbour 11 small mammal species from 11 genera and seven families. There was high similarity in the number of species caught during the two seasons (Sørensen Coefficient (CCs)=0.92), implying there to be minimal migration of the species in the area. A total of 159 individuals were caught during the dry season, rodents accounting for 89.3% of the total catch and insectivores 10.7%. The most common species were Cricetomys gambianus and Grammomys dolichurus that had trap successes of 2.83 and 1.11 respectively. During the wet season 185 animals were caught, rodents accounting for 92.4% of the total catch and insectivores 7.6%. Cricetomys gambianus was significantly more abundant during the dry season. Graphiurus murinus was not caught in this season and no trend in abundance was detected for the other species. Forest specialist species included Paraxerus palliatus and Petrodromus petersi. No species was endemic to the forest, near-endemic species that occur in coastal and Eastern Arc forests included P. petersi and Beamys hindei. B. hindei also occurs in a few other East African forests. Threatened species are B. hindei and P. palliatus that are vulnerable and P. petersi that is endangered. Lepus capensis is in Appendix I of CITES list and Hystrix cristata and Mellivora capensis in Appendix III. The forest, though small is in good health and fairly well protected, therefore the species are not in danger of being locally extinct in the near future.

Assessment Of The Status Of Lates Stappersii (Centropomidae) Stock In Lift-Net Fishery In Lake Tanganyika, Kigoma, Tanzania, I. A. Kimirei, Y. D. Mgaya

Tanzania Journal of Science

An assessment of the status of Lates stappersii (Boulenger, 1914) stock in the lift-net fishery in Lake Tanganyika, Kigoma area, was carried out from January to December 2003. Results indicated that breeding is seasonal with peaks in February, July-August and December, and so was catch composition, with peaks in March, May and July–August that followed the abundance of its prey, Stolothrissa tanganicae. Catch per unit effort was similar between wet and dry seasons and peaked synchronously at all study sites probably as an indication of its abundance during those months; but also it could mean that the fishes were caught …

Genetics And Inheritance Of Seed Dormancy Inflicted By Seed- Coat Factors In Rice (Oryza Sativa L.), Z. L. Kanyeka

Tanzania Journal of Science

The study was undertaken to investigate the genetic mode of inheritance of dormancy imposed by the hull (seed coat) in rice seeds. Freshly harvested seeds of parents, F1 and F2 populations of a cross between a dormant cultivar Kisegese and non-dormant strain K2004 were used. Germination test of the de-hulled (without seed coat) and un-dehulled (whole or with seed coat) seeds were conducted at 10 days intervals starting at 15 days after harvesting (15DAH) for 65 days. The seeds were sown in petri dishes. Numbers of germinated and un-germinated seeds were recorded at 7 days after sowing. Germination of seeds …

Pathogenecity Of Two Strains Of Rice Yellow Mottle Virus On Aromatic Rice Cultivars, Z. L. Kanyeka

Tanzania Journal of Science

Development of rice cultivars with resistance to rice yellow mottle virus (RYMV) requires characterization of pathogenecity of existing strains against susceptible cultivars. The pathogenecity of two RYMV strains; S4 and S“New” identified in Tanzania were assessed against seven local and introduced rice genotypes including cultivars Zambia, ITA173 and TXD 88. The two virus strains showed similar effects on the rice cultivar Zambia killing all the plants at 25d after inoculation. The strains significantly reduced the plant height, panicle length, and number of tillers per pot and total dry matter of all the two cultivars. In another trial, the pathogenecity of …

Occurrence Of Metacercariae Of Diplostomum And Tylodelphys Species (Diplostomidae) In Clarias Species (Clariidae) Fishes From Lake Victoria, M. J. Musiba, G. Nkwengulila

Tanzania Journal of Science

The localisation and abundance of the metacercariae of Diplostomum and Tylodelphys species among the clariids of Lake Victoria were investigated between April and December 2001. Four species viz. Clarias gariepinus (271), C. alluaudi (65), C. werneri (50) and C. liocephalus (47) were examined, but only C. gariepinus was infected in the brain case and along the nasal cavity. Prevalence of metacercariae was high (>70%). Prevalence and mean intensity were similar between male and female fish. Mean intensity increased with fish size and declined in larger fish for D. mashonense; but declined with the increase in fish size for Tylodelphys …

Diversity And Abundance Of Small Mammals In The Serengeti Kopjes, Tanzania, C. D. Timbuka, J. D. Kabigumila

Tanzania Journal of Science

Diversity and abundance of small mammals in the Serengeti kopjes were studied between November 2000 and February 2002. From 22,500 trap-nights and 3,300 bucket-nights, 4,903 small mammals in 18 species, 14 genera, 6 families and 3 orders were recorded. Muridae was the most dominant family with nine species. The highest number of species was recorded in the Maasai (14), Mbuzi Mawe (13) and Seronera (12) kopjes. The least number of species recorded in the Simba, Barafu and Wogakuria kopjes, with eight species each. Species diversity was highest in the Maasai kopjes (H'=2.337) and lowest in the Wogakuria kopjes (H'=1.794), with …

Chemical Constitutents And Cytotoxicity Of Some Tanzanian Wild Mushrooms, V. Nyigo, L. D. Baraza, M. H. H. Nkunya, S. J. M. Mdachi, C. C. Joseph, A. Waziri

Tanzania Journal of Science

The sterol ergosterol and ergosta-4,22-diene-3β,7α-diol, together with 4-hydroxybenzaldehyde were isolated from the mushroom species Polyporus molluscensis, Cantharellus isabelinus, C. symoensii and a Podaxis species. Their structures were established on the basis of spectroscopic data. The ethanol extracts of mushroom samples of Agaricus sp. and Termitomyces letestui also showed cytotoxicity against the brine shrimp larvae.

Influence Of Fructose On The Mechanisms For Ethanol-Induced Hypertriglyceridaemia, I. Onyesom

Tanzania Journal of Science

Twelve adult albino rabbits with an average weight of 1.42 kg were purchased and divided equally into the normal saline, ethanol and ethanol+fructose-treated groups. The ethanol-treated group orally received 1.5 g (40%) ethanol/kg body weight as single daily dose, while the ethanol +fructose-treated animals also received the same ethanol dose, but were given in addition, 0.25 gfructose/kg body weight after about 10 min of the ethanol administration. The normal saline-treated rabbits were given the equivalent amount of normal saline in lieu of ethanol. The animals were exposed to these various treatments along with their usual feeding pattern for a regular …

Use Of Hot Air Engine To Generate Electricity From Biogas: A Critique For Rural Development In Tanzania, L. L. N. Mkiramweni, P. Msaki, I. B. Mshoro

Tanzania Journal of Science

Rural electrification has high national priority because of several reasons. First, more than 90 per cent of the populations in Tanzania have no access to grid electricity and about 80% of this population lives in rural areas. Second, the poverty alleviation projects demand the incorporation of use of electricity in different economic projects. Third, a combination of high prices of fuel and environmental degradation and deforestation demand use of alternative renewable energy sources. The aim of this paper is to give a critical review and selected a suitable renewable energy by considering its ability to provide affordable, reliable and adequate …