Is there specificity in a defensive mutualism against soil versus lab nematodes, Dictyostelium discoideum farmers and their bacteria?

Background: The social amoeba Dictyostelium discoideum is a soil-dwelling microbe, which lives most of its life cycle in the vegetative stage as a predator of bacteria and as prey for nematodes. When bacteria are sparse, amoebae aggregate into a multicellular fruiting body. Some clones of D. discoideum have agriculture (Brock et al., 2011). They carry bacteria through the social stage, eat them prudently, and use some bacteria as defence against non-farming D. discoideum competitors. Caenorhabditis elegans preys on D. discoideum in the laboratory but does not encounter it in nature because C. elegans lives on rotten fruit. The nematode Oscheius tipulae is abundant in the soil. Questions: Do the defensive bacteria that farmers carry also protect farmers from nematodes? Is this protection specific to nematodes that reside with D. discoideum? Hypotheses: Many organisms evolve defensive mutualisms against predators. The natural habitat of D. discoideum is populated with nematodes. Therefore, we hypothesize that farming D. discoideum clones use non-food bacteria for protection from nematodes. We predicted higher fitness of farmers than non-farmers in the presence of nematodes. We also predicted to see this change of fitness only in the presence of the soil nematode, O. tipulae. Organisms: Amoeba Dictyostelium discoideum, nematodes Caenorhabditis elegans and Oscheius tipulae, bacteria Klebsiella pneumoniae and Burkholderia xenovorans. Methods: We compared spore production of D. discoideum farmers and non-farmers with and without nematodes. We also looked at nematode proliferation in the presence of farmers, non-farmers, K. pneumonia, and B. xenovorans. Results: Overall, farmer D. discoideum produced fewer spores than non-farmers. There was a decrease in the spore counts in the presence of nematodes for both farmers and non-farmers. There was a significant decrease in the percentage change in spore production for the farmers in the presence of soil nematodes but not laboratory nematodes. Nematode proliferation with the laboratory nematode and soil nematode did not vary in the presence of farmers, non-farmers, K. pneumoniae or B. xenovorans. Conclusion: The non-food bacteria that farmers carry do not provide defence against nematodes. In fact, it was a disadvantage for farmers to carry bacteria, since the soil nematode decreased spore production for farmers compared with non-farmers. However, the differences between the laboratory nematode and the soil nematode are marked enough to conclude that different species of nematodes respond differently to D. discoideum as a food source

Pedagogies for critical thinking at universities in Kenya, Ghana and Botswana: the importance of a collective 'teaching culture'

While critical thinking is widely regarded as a key outcome of higher education, research has shown that in practice it is only developed when certain conditions are in place, relating to the pedagogical approach, the nature of the curriculum and the level of challenge, amongst other factors. This article reports on findings from a four-year mixed methods study in Botswana, Ghana and Kenya, aiming to investigate the factors underpinning the successful development of critical thinking amongst undergraduate students. A two-stage critical thinking assessment was conducted with students in 15 sites, showing that only some of the institutions were ensuring significant gains in students’ critical thinking, even when endorsing learner-centred methods. The study points to the central importance of teaching orientations amongst lecturers, involving a deep shift in approaches to knowledge, and a facilitation rather than a transmission approach

Silicon Nanowires: Doping Dependent N- And P- Channel FET Behavior

The electrical transport properties of field effect transistor (FET) devices made of silicon nanowires (SiNWs) synthesized by pulsed laser vaporization (PLV) were studied. From as-grown PLV-SiNW FET, we found p-channel FET behavior with low conductance. To improve conductance, spin on glass (SOG) and vapor doping were used to dope phosphorus and indium into SiNW, respectively. From doping after synthesis, we could successfully make both n- and p-channel FET devices

Intimate partner violence as a predictor of marital disruption in sub-Saharan Africa: A multilevel analysis of demographic and health surveys

Intimate partner violence has gained momentum as health, social, and human right issue across the globe. Women within sub-Saharan Africa often do not report any case of violence due to the acceptance of violence which is rooted in their socio-cultural beliefs and practices. With a high prevalence of marital disruption in sub-Saharan Africa, it is important that we understand the role intimate partner violence plays in this phenomenon. Hence, this present study assessed the association between intimate partner violence and marital disruption among women in sub-Saharan Africa. Methods This study involved a cross-sectional analysis of data from the Demographic and Health Survey of 25 countries in sub-Saharan Africa. Multilevel binary logistic regression analysis was carried out and the results were presented as adjusted odds ratios (aOR) at 95% Confidence Interval (CI). Results The prevalence of physical, emotional, and sexual violence in the 25 countries considered in this study were 29.3%, 28%, and 11.5%, respectively. The highest prevalence of physical violence was in Sierra Leone (50.0%) and the lowest prevalence was in Comoros (5.7%). For emotional violence, the highest prevalence was in Sierra Leone (45.9%) and the lowest prevalence was in Comoros (7.9%). The highest prevalence of sexual violence was in Burundi (25.5%) and the lowest prevalence was in Comoros (1.8%). The average prevalence of marital disruption was 7.7%. This ranged from 1.3% in Burkina Faso to 20.2% in Mozambique. We found that women who had ever experienced physical violence were more likely to experience marital disruptions compared to those who had never experienced physical violence [aOR = 1.42, 95% CI = 1.35–1.50]. Women who had ever experienced sexual violence were more likely to experience marital disruption compared to those who had never experienced sexual violence [aOR = 1.29, 95% CI = 1.21–1.37]. Finally, women who had ever experienced emotional violence were more likely to experience marital disruption compared to those who had never experienced emotional violence [aOR = 1.86, 95% CI = 1.76–1.96]. Conclusion Findings from this study call for proven effective intimate partner violence reduction interventions such as strengthening laws against intimate partner violence in sub-Saharan Africa. Again, marital counseling and health education interventions should be implemented to address the role of intimate partner violence on the wellbeing of women and the stability of couples in sub-Saharan Africa

Carbon dynamics, net primary productivity (NPP) and human appropriated NPP (HANPP) across a forest‐cocoa farm landscape in West Africa

Terrestrial net primary productivity (NPP) is an important metric of ecosystem functioning; however, there is little empirical data on the NPP of human-modified ecosystems, particularly smallholder,perennial crops like cocoa (Theobroma cacao), which are extensive across the tropics. Human appropriated NPP (HANPP) is a measure of the proportion of a natural system’s NPP that has either been reduced through land-use change or harvested directly and, previously, has been calculated to estimate the scale of the human impact on the biosphere. Additionally, human-modification can create shifts in NPP allocation and decomposition, with concomitant impacts on the carbon cycle. This study presents the results of three years of intensive monitoring of forest and smallholder cocoa farms across disturbance, management intensity, distance from forest and farm age gradients. We measured among the highest reported NPP values in tropical forest, 17.57 ± 2.1 and 17.7 ± 1.6 Mg C ha-1 yr-1 for intact and logged forest respectively; however, the average NPP of cocoa farms was still higher, 18.8 ± 2.5 Mg C ha-1 yr-1, which we found was driven by cocoa pod production. We found a dramatic shift in litterfall residence times, where cocoa leaves decomposed more slowly than forest leaves and shade tree litterfall decomposed considerably faster, indicating significant changes in rates of nutrient cycling. The average HANPP value for all cocoa farms was 2.1 ± 1.1 Mg C ha-1 yr-1; however, depending on the density of shade trees it ranged from -4.6 to 5.2 Mg C ha-1 yr-1. Therefore, rather than being related to cocoa yield, HANPP was reduced by maintaining higher shade levels. Across our monitored farms 18.9% of farm NPP was harvested (i.e. whole cocoa pods) and only 1.1% (i.e.cocoa beans) was removed from the system; suggesting that the scale of HANPP in smallholder cocoa agroforestry systems is relatively small

Studentsâ Clinical Learning in an Emerging Dental School: An Investigation in International Collaboration Between Michigan and Ghana

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153593/1/jddj0022033720137712tb05644x.pd