Existing competitive indices in the intercropping system of Manihot esculenta Crantz and Lagenaria siceraria (Molina) Standley

An assessment of the competitive indices in intercropping between cassava (Manihot esculenta) and bottle gourd (Lagenaria siceraria) was conducted with the aim of increasing the productivity of these crops. For this purpose, three farmers preferred landraces of cassava (yacé, blêbou and six mois) and three morphotypes of gourd (dark green and round fruit, light green and round fruit, light green and long fruit) were used to test the three intercropping ratios (gourd:cassava with 6:42, 6:24 and 6:18). Intercropping systems were assessed by land equivalent ratio (LER), area time equivalent ratio (ATER), relative crowding coefficient (K), actual yield loss (AYL), aggressivity (A) and competition ratio (CR). LER, ATER and K values were greater than 1 for gourd-cassava (6:24). These findings indicate an advantage of intercropping for exploiting the resources of the environment. Cassava clones were more competitive than gourd component.     

Kinetic Parameters and Lactate Dehydrogenase Isozyme Activities Support Possible Lactate Utilization by Neurons

Lactate is potentially a major energy source in brain, particularly following hypoxia/ischemia; however, the regulation of brain lactate metabolism is not well understood. Lactate dehydrogenase (LDH) isozymes in cytosol from primary cultures of neurons and astrocytes, and freshly isolated synaptic terminals (synaptosomes) from adult rat brain were separated by electrophoresis, visualized with an activity-based stain, and quantified. The activity and kinetics of LDH were determined in the same preparations. In synaptosomes, the forward reaction (pyruvate + NADH + H⁺ → lactate + NAD⁺), which had a V _max of 1,163 μmol/min/mg protein was 62% of the rate in astrocyte cytoplasm. In contrast, the reverse reaction (lactate + NAD⁺ → pyruvate + NADH + H⁺), which had a V _max of 268 μmol/min/mg protein was 237% of the rate in astrocytes. Although the relative distribution was different, all five isozymes of LDH were present in synaptosomes and primary cultures of cortical neurons and astrocytes from rat brain. LDH1 was 14.1% of the isozyme in synaptic terminals, but only 2.6% and 2.4% in neurons and astrocytes, respectively. LDH5 was considerably lower in synaptic terminals than in neurons and astrocytes, representing 20.4%, 37.3% and 34.8% of the isozyme in these preparations, respectively. The distribution of LDH isozymes in primary cultures of cortical neurons does not directly reflect the kinetics of LDH and the capacity for lactate oxidation. However, the kinetics of LDH in brain are consistent with the possible release of lactate by astrocytes and oxidative use of lactate for energy in synaptic terminals. Special issue dedicated to John P. Blass.     

Free-ranging pigs identified as a multi-reservoir of Trypanosoma brucei and Trypanosoma congolense in the Vavoua area,a historical sleeping sickness focus of Côte d’Ivoire

BackgroundThe existence of an animal reservoir of Trypanosoma brucei gambiense (T. b. gambiense), the agent of human African trypanosomiasis (HAT), may compromise the interruption of transmission targeted by World Health Organization. The aim of this study was to investigate the presence of trypanosomes in pigs and people in the Vavoua HAT historical focus where cases were still diagnosed in the early 2010’s.MethodsFor the human survey, we used the CATT, mini-anion exchange centrifugation technique and immune trypanolysis tests. For the animal survey, the buffy coat technique was also used as well as the PCR using Trypanosoma species specific, including the T. b. gambiense TgsGP detection using single round and nested PCRs, performed from animal blood samples and from strains isolated from subjects positive for parasitological investigations.ResultsNo HAT cases were detected among 345 people tested. A total of 167 pigs were investigated. Free-ranging pigs appeared significantly more infected than pigs in pen. Over 70% of free-ranging pigs were positive for CATT and parasitological investigations and 27–43% were positive to trypanolysis depending on the antigen used. T. brucei was the most prevalent species (57%) followed by T. congolense (24%). Blood sample extracted DNA of T. brucei positive subjects were negative to single round TgsGP PCR. However, 1/22 and 6/22 isolated strains were positive with single round and nested TgsGP PCRs, respectively.DiscussionFree-ranging pigs were identified as a multi-reservoir of T. brucei and/or T. congolense with mixed infections of different strains. This trypanosome diversity hinders the easy and direct detection of T. b. gambiense. We highlight the lack of tools to prove or exclude with certainty the presence of T. b. gambiense. This study once more highlights the need of technical improvements to explore the role of animals in the epidemiology of HAT.     

Re-Visiting Insecticide Resistance Status in Anopheles gambiae from C?te d'Ivoire: A Nation-Wide Informative Survey

Insecticide resistance constitutes a major threat that may undermine current gain in malaria control in most endemic countries. National Malaria Control Programmes (NMCPs) need as much information as possible on the resistance status of malaria vectors and underlying mechanisms in order to implement the most relevant and efficient control strategy. Bioassays, biochemical and molecular analysis were performed on An. gambiae collected in six sentinel sites in Côte d''Ivoire. The sites were selected on the basis of their bioclimatic status and agricultural practices. An. gambiae populations across sites showed high levels of resistance to organochloride, pyrethroid and carbamate insecticides. The kdr and ace-1^R mutations were detected in almost all sentinel sites with mosquitoes on the coastal and cotton growing areas mostly affected by these mutations. At almost all sites, the levels of detoxifying enzymes (mixed-function oxidases (MFOs), non-specific esterases (NSE) and glutathione-S-transferases (GSTs)) in An. gambiae populations were significantly higher than the levels found in the susceptible strain Kisumu. Pre-exposure of mosquitoes to PBO, an inhibitor of MFOs and NSEs, significantly increased mortality rates to pyrethroids and carbamates in mosquitoes but resistance in most cases was not fully synergised by PBO, inferring a residual role of additional mechanisms, including kdr and ace-1 site insensitivity. The large distribution of resistance in Côte d''Ivoire raises an important question of whether to continue to deploy pyrethroid-based long-lasting insecticidal nets (LLINs) and insecticide residual spraying (IRS) towards which resistance continues to rise with no guarantee that the level of resistance would not compromise their efficacy. Innovative strategies that combine insecticide and synergists in LLINs or spatially LLIN and an effective non-pyrethroid insecticide for IRS could be in the short term the best practice for the NMCP to manage insecticide resistance in malaria vectors in Côte d''Ivoire and other endemic countries facing resistance.     

Access to HIV Services at Non-Governmental and Community-Based Organizations among Men Who Have Sex with Men (MSM) in Cameroon: An Integrated Biological and Behavioral Surveillance Analysis

Background

Men who have sex with men (MSM) are more likely to be living with HIV than other adult men in low- and middle-income countries. MSM experience barriers to accessing HIV services including a lack of available specialized care, and community-level stigma and discrimination. This study aims to examine the uptake of HIV services at non-governmental and community-based organizations (NGOs/CBOs) to identify ways to improve coverage of HIV prevention and treatment among MSM.

Methods

An Integrated Biological and Behavioral Surveillance (IBBS) survey was conducted in Yaoundé and Douala, Cameroon in 2011 using the respondent driven sampling (RDS) method to recruit and interview 239 MSM in Yaoundé and 272 MSM in Douala.

Results

MSM in Yaoundé were statistically significantly more likely to have accessed NGO/CBO services or been reached by an outreach worker in the past 12 months if they had any STI symptoms (aOR 2.17 CI 1.02-4.59. p=0.04), or if they had a larger MSM social network (aOR 1.02 CI 1.01-1.04. p<0.01). MSM in Douala were more likely to have accessed NGO/CBO services or been reached by an outreach worker in the past 12 months if they were living with HIV (aOR 3.60 CI 1.35-9.60. p=0.01), or if they reported higher numbers of male sexual partners (aOR 1.17 CI 1.00-1.36. p=0.046). Compared to men in Douala, MSM in Yaoundé were significantly less likely to have accessed NGO/CBO services or been reached by an outreach worker in the past 12 months (aOR 0.22 CI 0 .14-0.34. p=<0.01).

Conclusions

With appropriate funding and resources, community-based organizations that provide care specifically for MSM can improve access to HIV prevention, treatment, and care services. Additionally, using social networks to reach MSM can connect greater numbers of the population to effective HIV interventions, which will improve health outcomes and decrease onward transmission of HIV.     

Evidence of High Out of Pocket Spending for HIV Care Leading to Catastrophic Expenditure for Affected Patients in Lao People's Democratic Republic

Background

The scaling up of antiviral treatment (ART) coverage in the past decade has increased access to care for numerous people living with HIV/AIDS (PLWHA) in low-resource settings. Out-of-pocket payments (OOPs) represent a barrier for healthcare access, adherence and ART effectiveness, and can be economically catastrophic for PLWHA and their family. We evaluated OOPs of PLWHA attending outpatient and inpatient care units and estimated the financial burden for their households in the Lao People''s Democratic Republic. We assumed that such OOPs may result in catastrophic health expenses in this context with fragile economical balance and low health insurance coverage.

Methods

We conducted a cross-sectional survey of a randomized sample of routine outpatients and a prospective survey of consecutive new inpatients at two referral hospitals (Setthathirat in the capital city, Savannaket in the province). After obtaining informed consent, PLWHA were interviewed using a standardized 82-item questionnaire including information on socio-economic characteristics, disease history and coping strategies. All OOPs occurring during a routine visit or a hospital stay were recorded. Household capacity-to-pay (overall income minus essential expenses), direct and indirect OOPs, OOPs per outpatient visit and per inpatient stay as well as catastrophic spending (greater than or equal to 40% of the capacity-to-pay) were calculated. A multivariate analysis of factors associated with catastrophic spending was conducted.

Results

A total of 320 PLWHA [280 inpatients and 40 outpatients; 132 (41.2%) defined as poor, and 269 (84.1%) on ART] were enrolled. Monthly median household income, essential expenses and capacity-to-pay were US$147.0 (IQR: 86–242), $126 (IQR: 82–192) and $14 (IQR: 19–80), respectively. At the provincial hospital OOPs were higher during routine visits, but three fold lower during hospitalization than in the central hospital ($21.0 versus $18.5 and $110.8 versus $329.8 respectively (p<0.01). The most notable OOPs were related to transportation and to loss of income. A total of 150 patients (46.8%; 95%CI: 41.3–52.5) were affected by catastrophic health expenses; 36 outpatients (90.0%; 95%CI: 76.3–97.2) and 114 inpatients (40.7%; 95%CI: 34.9–46.7). A total of 141 (44.0%) patients had contracted loans, and 127 (39.6%) had to sell some of their assets. In the multivariate analysis, being of Lao Loum ethnic group (Coef.-1.4; p = 0.04); being poor (Coef. -1.0; p = 0.01) and living more than 100 km away from the hospital (Coef.-1.0; p = 0.002) were positively associated with catastrophic spending. Conversely being in the highest wealth quartile (Coef. 1.6; p<0.001), living alone (Coef. 1.1; p = 0.04), attending the provincial hospital (Coef. 1.0; p = 0.002), and being on ART (Coef.1.2; p = 0.003), were negatively associated with catastrophic spending.

Conclusion

PLWHA’s households face catastrophic OOPs that are not directly attributable to the cost of ART or to follow-up tests, particularly during a hospitalization period. Transportation, distance to healthcare and time spent at the health facility are the major contributors for OOPs and for indirect opportunity costs. Being on ART and attending the provincial hospital were associated with a lower risk of catastrophic spending. Decentralization of care, access to ART and alleviation of OOPs are crucial factors to successfully decrease the household burden of HIV-AIDS expenses.     

Breeding Strategy To Generate Robust Yeast Starter Cultures for Cocoa Pulp Fermentations

Cocoa pulp fermentation is a spontaneous process during which the natural microbiota present at cocoa farms is allowed to ferment the pulp surrounding cocoa beans. Because such spontaneous fermentations are inconsistent and contribute to product variability, there is growing interest in a microbial starter culture that could be used to inoculate cocoa pulp fermentations. Previous studies have revealed that many different fungi are recovered from different batches of spontaneous cocoa pulp fermentations, whereas the variation in the prokaryotic microbiome is much more limited. In this study, therefore, we aimed to develop a suitable yeast starter culture that is able to outcompete wild contaminants and consistently produce high-quality chocolate. Starting from specifically selected Saccharomyces cerevisiae strains, we developed robust hybrids with characteristics that allow them to efficiently ferment cocoa pulp, including improved temperature tolerance and fermentation capacity. We conducted several laboratory and field trials to show that these new hybrids often outperform their parental strains and are able to dominate spontaneous pilot scale fermentations, which results in much more consistent microbial profiles. Moreover, analysis of the resulting chocolate showed that some of the cocoa batches that were fermented with specific starter cultures yielded superior chocolate. Taken together, these results describe the development of robust yeast starter cultures for cocoa pulp fermentations that can contribute to improving the consistency and quality of commercial chocolate production.     

In vitro induction of minitubers in yam (<Emphasis Type="Italic">Dioscorea cayenensis</Emphasis>- <Emphasis Type="Italic">D. rotundata</Emphasis> complex)

Two methods were used to produce yam minitubers from two different yam cultivars (cv. Krengle and cv. Kponan) using in vitro culture techniques. Method 1: Yam microtubers were first initiated in vitro and then transplanted to soil to generate plants from which minitubers were produced. Yam plants were obtained either by directly planting the microtubers to soil, or by inducing the germination of the microtubers using various chemical and physical treatments, before their transfer to soil. Method 2: Yam plantlets were first produced in vitro and then transplanted to soil for further development and tuber production. In both methods, the presence of jasmonic acid (JA) in the culture medium was found to be essential for yam tuberization, as well as for the germination of yam microtubers. In vitro production of yam microtubers was variety dependant. Compared to cv. Krengle, cv. Kponan responded better to microtuberization, and 2.5 μM JA was the optimum concentration resulting in 70 and 90% explants producing microtubers in the MS medium and the Tuberization medium (T-medium), respectively. Germination of the microtubers required treatment of JA at concentrations ranging from 1.0 to 2.5 μM. The overall length of the process to produce minitubers from microtubers took 32 weeks. In contrast, minitubers were obtained within 20 weeks when plantlets were directly transferred to soil. In this case, plantlets were first grown for 8 weeks on medium containing JA (0.1–1.0 μM) and 8% sucrose to initiate plant growth and rooting.     

Intraguild predation and cannibalism between the predatory mites Neoseiulus neobaraki and N. paspalivorus, natural enemies of the coconut mite Aceria guerreronis

Neoseiulus neobaraki and N. paspalivorus are amongst the most common phytoseiid predators of coconut mite, Aceria guerreronis, found in the spatial niche beneath coconut fruit bracts. Both predators may occur on the same coconut palms in Benin and Tanzania and are therefore likely to interact with each other. Here, we assessed cannibalism and intraguild predation (IGP) of the two predators in the absence and presence of their primary prey A. guerreronis. In the absence of the shared extraguild prey, A. guerreronis, N. neobaraki killed 19 larvae of N. paspalivorus per day and produced 0.36?eggs/female/day, while the latter species killed only 7 larvae of the former and produced 0.35?eggs/female/day. Presence of A. guerreronis only slightly decreased IGP by N. neobaraki but strongly decreased IGP by N. paspalivorus, which consumed 4-7 times less IG prey than N. neobaraki. Resulting predator offspring to IG prey ratios were, however, 4-5 times higher in N. paspalivorus than N. neobaraki. Overall, provision of A. guerreronis increased oviposition in both species. In the cannibalism tests, in the absence of A. guerreronis, N. neobaraki and N. paspalivorus consumed 1.8 and 1.2 conspecific larvae and produced almost no eggs. In the presence of abundant herbivorous prey, cannibalism dramatically decreased but oviposition increased in both N. neobaraki and N. paspalivorus. In summary, we conclude that (1) N. neobaraki is a much stronger intraguild predator than N. paspalivorus, (2) cannibalism is very limited in both species, and (3) both IGP and cannibalism are reduced in the presence of the common herbivorous prey with the exception of IGP by N. neobaraki, which remained at high levels despite presence of herbivorous prey. We discuss the implications of cannibalism and IGP on the population dynamics of A. guerreronis and the predators in view of their geographic and within-palm distribution patterns.