Biology subjects

Ndam, N.

Publications and source records attributed to Ndam, N..

3 recordsLinked to original sources

bioRxiv2024

Placodiscus bijugus (Sapindaceae) a new species of Endangered lowland evergreen forest tree from the western foothills of Mt Cameroon and from Korup National Park, Cameroon.

A new range-restricted species of Placodiscus Radlk. is described, mapped and illustrated. Placodiscus bijugus is a cauliflorous tree (4 -)5 - 10 m tall, characterised by having two pairs of leaflets, 1(- 2)-flowered cymules with minute bracts, a glabrous disk, pedicels 3 - 3.2 mm long and large (3 - 4 cm diam.), shortly stipitate, retuse fruits, orbicular in outline. It is similar to P. caudatus Pierre ex Pellegr. which has been reported from surveys in Cameroon. We discuss the typification and range of the latter species which in fact appears to be absent from Cameroon. Placodiscus bijugus is provisionally assessed as Endangered (EN B1ab(iii)+2ab(iii)) using the IUCN standard, since only three locations, with threats are reported. The species has a small, slightly range, disjunct between Mt Cameroon and Korup National Park in coastal SW region Cameroon. We review other species with this disjunct range.

plant biology↗

bioRxiv2022

Mosquito bites and stages specific antibody responses against Plasmodium falciparum in southern Ghana

BackgroundThe human host elicits specific immune responses after exposure to various life stages of the malaria parasite as well as components of mosquito saliva injected into the host during a mosquito bite. This study describes differences in IgG responses against antigens derived from the sporozoite (PfCSP), asexual stage parasite (PfEBA175) and the gametocyte (Pfs230) in addition to an Anopheles gambiae salivary gland antigen (gSG6-P1) in two communities in Ghana with similar blood stage malaria parasite prevalence. MethodologyThis study used archived plasma samples collected from an earlier cross-sectional study that enrolled volunteers aged from 6 months to 70 years from Simiw, peri-urban community (N=347) and Obom, rural community (N=291). An archived thick and thin blood smear for microscopy was used for the estimation of Plasmodium parasite density and species and DNA extraction from blood spots and P. falciparum confirmation was performed using PCR. This study used the stored plasma samples to determine IgG antibody levels to Plasmodium falciparum and Anopheles salivary antigens using indirect ELISA. ResultsIndividuals from Simiw had significantly higher levels of IgG against mosquito gSG6-P1 (median (95%CI)) (2.590 (2.452-2.783) ng/mL) compared to those from Obom (2.119 (1.957-2.345) ng/mL), p<0.0001. Both IgG responses against Pfs230proC (p=0.0006), and PfCSP (p=0.002) were significantly lower in volunteers from Simiw compared to the participants from Obom. The seroprevalence of PfEBA-175.5R (p=0.8613), gSG6-P1 (p=0.0704), PfCSP (p=0.7798) IgG were all similar in Obom and Simiw. However, Pfs230 seroprevalence was significantly higher at Obom compared to Simiw (p=0.0006). Spearman correlation analysis showed no significant association between IgG responses against gSG6-P1, PfCSP, Pfs230proC and PfEBA-175.5R and parasite density at both Obom and Simiw (p>0.05). ConclusionIn conclusion, malaria transmission dynamics is highly complex. The similar malaria transmission intensity identified in the two communities resulted from a different combination of vector, environmental and host factors. With one community likely having a higher prevalence of uninfected mosquitoes and the other a larger reservoir of gametocyte carriers.

immunology↗

bioRxiv2019

Notes on the threatened lowland forests of Mt Cameroon and their endemics including Drypetes njonji sp. nov., with a key to species of Drypetes sect. Stipulares (Putranjivaceae).

Background and aimsThis paper reports a further discovery of a new endemic threatened species to science in the context of long-term botanical surveys in the lowland coastal forests of Mount Cameroon specifically and generally in the Cross River-Sanaga interval of west-central Africa. These studies focus on species discovery and conservation through the Tropical Important Plant Areas programme.\n\nMethodsNormal practices of herbarium taxonomy have been applied to study the material collected. The relevant collections are stored in the Herbarium of the Royal Botanic Gardens, Kew, London and at the Limbe Botanic Garden, Limbe, and the Institute of Research in Agronomic Development - National Herbarium of Cameroon, Yaounde.\n\nKey resultsNew species to science continue to be discovered from Mt Cameroon. Most of these species are rare, highly localised, and threatened by habitat destruction. These discoveries increase the justification for improved conservation management of surviving habitat. Drypetes njonji is described as an additional species new to science and appears to be endemic to the lowland coastal forests at the foot of Mt Cameroon. It is placed in and keyed out in Sect. Stipulares, a group confined to Lower Guinea. The conservation status of Drypetes njonji is assessed as Endangered (EN B1+2ab(iii)) according to the 2012 criteria of IUCN. An updated overview of the lowland plant endemics of Mt Cameroon is presented.

plant biology↗