Biological Sciences Staff Publications

On cestode and digenean parasites of Clarias gariepinus (Burchell, 1822) from the Rietvlei Dam, South Africa

Mon, 23 Jan 2006 00:00:00 GMT

On cestode and digenean parasites of Clarias gariepinus (Burchell, 1822) from the Rietvlei Dam, South Africa Barson, M; Avenant-Oldewage, A. Sharptooth catfish, Clarias gariepinus, from the Rietvlei Dam near Pretoria, South Africa were examined for internal platyhelminth parasites. Two adult cestodes, Polyonchobothrium clarias (stomach) (prevalence 71 %, mean intensity = 5, n = 7) and Proteocephalus glanduliger (anterior intestine) (prevalence 14 %, mean intensity = 2, n = 7), were found in the gut while metacercariae of one larval digenean, Ornithodiplostomum sp. (prevalence 14 %, mean intensity = 140, n = 7), were found encysted in the muscles. The morphology of these species, based on light and scanning electron microscopy as well as histological analysis, and how they differ from previously described specimens, are discussed. Ornithodiplostomum is a new record in southern Africa. Infection levels of the host fish were mild compared to records from previous surveys.

The diet of an invasive crayfish, Cherax quadricarinatus (Von Martens, 1868), in Lake Kariba, inferred using stomach content and stable isotope analyses

Sat, 27 Jan 2018 00:00:00 GMT

The diet of an invasive crayfish, Cherax quadricarinatus (Von Martens, 1868), in Lake Kariba, inferred using stomach content and stable isotope analyses Marufu, Lightone T.; Dalu, Tatenda; Phiri, Crispen; Barson, Maxwell; Simango, Rutendo; Utete, Beaven; Nhiwatiwa, Tamuka The diet of an invasive crayfish, Cherax quadricarinatus (Von Martens 1868), in Lake Kariba, was investigated using stomach content analysis (SCA) and stable isotope analysis (SIA). The frequency of occurrence of macrophytes and detritus ranged between 63.6–97.1% and 20–45.5%, respectively, and the index of relative importance ranked these as the two most important food items across all size classes. Significant differences in the ranking of fish, macroinvertebrates and crayfish were found between size classes 29–37.9, 38–46.9 and 47–55.9mm. Stomach content analysis showed 16% of crayfish stomachs were empty. Feeding intensity differed significantly between size classes and ranged from 3.46 to 5.21. Stable isotope analysis was done by comparing δ13C, δ15N and C/N ratios in crayfish muscle and potential dietary items in the lake. Macrophytes were the most dominant food item (57%), followed by macroinvertebrates (20%), then detritus, and finally fish and crayfish. Stable isotope analysis revealed that all crayfish size classes analysed were in the same trophic level. Nevertheless, while SCA showed high dietary overlap among all crayfish size classes (>65%), SIA showed that small crayfish (< 28.9mm) had limited overlap with large crayfish (> 56mm), with the former showing a higher proportion of macroinvertebrates in their diet. In Lake Kariba, C. quadricarinatus predominantly feeds on macrophytes, macroinvertebrates and detritus, which may bring about nutrient cycle alterations in the lake. Littoral habitat changes caused by the feeding characteristics of C. quadricarinatus might also lead to competition with, and eventual displacement of, some nativelittoral fishes in this lake. The following supplementary material is available for this article: Table S1. Location of the study sites in the Sanyati Basin of Lake Kariba, Zimbabwe. Table S2. Results of stable isotope analysis in R of the food source proportions in redclaw crayfish diet. This material is available as part of online article from: http://www.reabic.net/journals/bir/2018/Supplements/BIR_2018_Marufu_etal_SupplementaryTables.xlsx

African potato ( Hypoxis Spp): Diversity and comparison of the phytochemical profiles and cytotoxicity evaluation of four Zimbabwean species

Wed, 22 Jan 2014 00:00:00 GMT

African potato ( Hypoxis Spp): Diversity and comparison of the phytochemical profiles and cytotoxicity evaluation of four Zimbabwean species Zimudzi, Clemence The Hypoxis corm has a catalogue of medicinal uses and also serves as a source of food. Most scientific research on Hypoxis has centred on Hypoxis hemerocallidea although many other species are exploited medicinally. Hypoxis corms look similar and this has resulted in different species being prescribed and sold as the same species raising important public health issues of the efficacy and quality of the medicines sold. The aim of this study was to investigate and compare the phytochemical profiles and cytotoxicity of Hypoxis hemerocallidea, Hypoxis rigidula, Hypoxis galpinii and Hypoxis obtusa. Corm methanolic extracts of the four species were qualitatively screened for different phytochemicals following standard methods. Tests indicated presence of terpenoids, saponins, cardiac glycosides, tannins and reducing sugars and negative for alkaloids, flavonoids and anthraquinones in the four Hypoxis species. Cytotoxic effects of the plants were assessed through Brine shrimp lethality (BSL) bioassay. LC50 values ranged from 6.3 -409 mg/ml showing that the plants are non toxic.

Phytochemical and analgesic activity of root crude extracts of Dicoma niccolifera wild (Asteraceae)

Sat, 09 Mar 2013 00:00:00 GMT

Phytochemical and analgesic activity of root crude extracts of Dicoma niccolifera wild (Asteraceae) Zimudzi, Clemence; Kativu, Shakkie; Jere, Joe; Kunonga, Ngoni; Rupende, S The study aimed at evaluating the phytochemical profile and anti-nociception activity of root crude extracts of D. niccolifera, a plant commonly used to alleviate painful conditions by local communities. Standard phytochemical screening tests revealed presence of tannins, alkaloids, flavonoids, terpenoids, reducing sugars, cardiac glycosides and anthraquinones. Anti-nociception was assessed using the hot plate model on Swiss Albino mice. Mice intraperitoneally injected with root crude extract showed that the D. niccolifera root extract had analgesic activity by taking longer to react to the thermal stimulus than the control group. The extract higher doses of 500 and 1000mg/kg showed peak mean latency times of 2.39 and 2.12 seconds respectively. These latency times were found to be significantly different (p<0.05) from the control. The anti-nociception activity may be attributed to the phenolic compounds in the extract. The study validates the use of D. niccolifera in managing painful conditions.