Diversity and dynamics of rhizobial populations in acidic soils with aluminum and manganese toxicities in forest zones

Soil acidity in the humid forest zones of Cameroon is one of the major constraints to agricultural productivity. This study was carried out to assess the rhizobial communities of two acidic soils; with aluminum toxicity (Nkoemvone) and manganese toxicity (Nkolbisson) for their potential to improve soil fertility in Cameroon. These two soils were used to inoculate to the host plants cowpea and siratro. At harvest, 120 rhizobacterial isolates were extracted from the nodules of these two hosts and subjected to morphological characterization. Twenty isolates per site were selected and analyzed for their 16S rDNA genetic profile following restrictions with endonucleases of PCR products and electrophoresis. The restriction patterns of the 16S rDNA of the 40 isolates showed 12 different profiles. Eight occurred in both types of soils, where as 4 were specific to the manganese-toxic-acidic soil. While the Al toxicity reduced the nodulation and growth of both plants, the Mn toxicity mostly affect the cowpea. This study ascertained the distribution of rhizobia based on soil characteristics. Further molecular analyses would allow the identification of the isolates recovered as well as their phylogenetical relationships.Int. J. Agril. Res. Innov. & Tech. 6 (2): 12-23, December, 201

Evaluation of maize (Zea mays L.) accessions using line x tester analysis for aluminum and manganese tolerance

Soil acidity is a limiting factor severely affecting the growth and yield of maize. The present study aimed at estimating the breeding value of inbred lines and to assess the test-cross performance of the hybrid maize under acid soil conditions. A line x tester analysis involving 63 test-crosses generated by crossing 20 maize inbred lines with 3 testers and between testers themselves, and 1 standard check was investigated during the cropping season 2012 in two contrasted regions with aluminum and manganese toxicity in Cameroon. Both treatments, acid soil and non-acid soil, using dolomitic lime were conducted in a randomized complete block design with 3 replications. Seven hybrids producing high grain yield (4.27 to 9.88t/ha), with high specific combining ability (SCA) and slow rate of yield loss were discovered such as tolerant for both types of acidic soils. Likewise, four inbred lines (ATP-46, 87036, and Cam Inb gp117, C4SRRA7) with high general combining ability (GCA) were retained as good progenitors. The GCA and SCA effects showed that the tolerance to aluminum toxicity was controlled by additive effects of genes while on acid soil with manganese toxicity, the contribution of non-additive effects of genes was dominant.Keywords: Inbred lines, hybrids, acid soil, GCA, SCA, humid forest zone

Prevalence and risk factors associated with Haemophilus ducreyi cutaneous ulcers in Cameroon

Epidemics of yaws-like cutaneous ulcers are regularly documented in children in the tropics. They occur mainly in poor and remote communities without access to health facilities. The integration of molecular tools into yaws control efforts has made it possible to describe Haemophilus ducreyi (HD) as a major cause of cutaneous ulcers. The objective of this study was to determine the prevalence of HD as cause of cutaneous ulcers, investigate its presence in asymptomatic individuals and identify associated risk factors. A cross-sectional study was conducted in yaws endemic districts of Cameroon. Participants included people presenting yaws-like ulcers and asymptomatic individuals. Swab samples were collected from each participant and tested for HD and Treponema pallidum (TP) using an established qPCR method. Additionally, demographic, habitat, proximity, and hygiene characteristics were collected using a structured questionnaire. A total of 443 individuals participated in the study, including 271 ulcer cases and 172 asymptomatic contacts. The prevalence of HD in ulcers was 30.3% (Confidence Interval (CI) 95% [24.8-35.7]) and the prevalence of asymptomatic HD carriage was 8.6% (CI95% [4.5-12.9]). TP was also detected in our sample among ulcer cases but in lower proportion (5.2% CI95% [2.5-7.8]) compared to HD. The adjusted logistic regression model showed that women were as much at risk of having HD cutaneous ulcer as men regardless of age. Physical proximity to a confirmed ulcer case was the major factor identified favouring HD transmission. HD ulcers were more likely to be present on Bantu individuals compared to Baka as well as HD colonization. These findings highlight HD as the most common cause of cutaneous ulcers in yaws-endemic communities in Cameroon. The exact implications of detecting HD on intact skin are not yet clear. Further studies are needed to understand the significance of this carriage in the spread dynamics of the disease

La respiration et la tolerance au sel chez la cyanobacterie Synechocystis PCC6803: Etude physiologique, genetique et moleculaire

Available from INIST (FR), Document Supply Service, under shelf-number : TD 84101 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Hypervirial and Hellmann-Feynman theorems applied to the calculation of energy levels for relativistic particles

The nonrelativistic hypervirial Hellmann-Feynman method developed recently is extended to deal with relativistic particles bound in a spherically symmetric potential. A simple analytical procedure for calculating correction terms of arbitrary high orders is derived. Numerical results obtained through a study of the screened Coulomb potential enable us to illustrate the improvements of our procedure over the previous approaches

Development of a nanosecond oscillator – four pass amplifier XeCl laser system

International audienc

Endemicity and genetic diversity of Hepatitis delta virus among Pygmies in Cameroon, Central Africa

International audienceObjectiveA single study conducted about three decades ago on hepatitis D virus (HDV) infection among Baka pygmies in Cameroon reported a very high anti-HDV antibodies prevalence of 46%, but HDV genetic diversity has not been studied in this population. The genetic diversity of strains from endemic ancient populations may help to understand the origin and evolutionary history of viruses. This study aimed to investigate the HDV seroprevalence and the genetic diversity in three remote Cameroonian Pygmies with chronic HBV infection.ResultsAn unusually high 69% (36/52) level of HDV infection was found among HBsAg-positive pygmies in Cameroon. HDV RNA was detected and sequenced in 38.8% (14/36). The phylogenetic analysis revealed that 9/14 strains (64.3%) were identified and classified as genotype 1 (HDV-1) and 5/14 (35.6%) as genotype 7 (HDV-7), respectively with a bootstrap value of 100%. The further analysis showed the co-circulation of highly diverse HDV genotypes HDV-1 and HDV-7 in this population. These results highlight the endemicity of HDV infection in Central Africa. The highly diverse HDV-1 and HDV-7 in pygmies suggest an African origin of HDV. However, further studies are needed with larger sample size

Diversity and dynamics of rhizobial populations in acidic soils with aluminum and manganese toxicities in forest zones

Soil acidity in the humid forest zones of Cameroon is one of the major constraints to agricultural productivity. This study was carried out to assess the rhizobial communities of two acidic soils; with aluminum toxicity (Nkoemvone) and manganese toxicity (Nkolbisson) for their potential to improve soil fertility in Cameroon. These two soils were used to inoculate to the host plants cowpea and siratro. At harvest, 120 rhizobacterial isolates were extracted from the nodules of these two hosts and subjected to morphological characterization. Twenty isolates per site were selected and analyzed for their 16S rDNA genetic profile following restrictions with endonucleases of PCR products and electrophoresis. The restriction patterns of the 16S rDNA of the 40 isolates showed 12 different profiles. Eight occurred in both types of soils, where as 4 were specific to the manganese-toxic-acidic soil. While the Al toxicity reduced the nodulation and growth of both plants, the Mn toxicity mostly affect the cowpea. This study ascertained the distribution of rhizobia based on soil characteristics. Further molecular analyses would allow the identification of the isolates recovered as well as their phylogenetical relationships.Int. J. Agril. Res. Innov. & Tech. 6 (2): 12-23, December, 201

DIVERSITY AND DYNAMICS OF RHIZOBIAL POPULATIONS IN ACIDIC SOILS WITH ALUMINUM AND MANGANESE TOXICITIES IN FOREST ZONES

Soil acidity in the humid forest zones of Cameroon is one of the major constraints to agricultural productivity. This study was carried out to assess the rhizobial communities of two acidic soils; with aluminum toxicity (Nkoemvone) and manganese toxicity (Nkolbisson) for their potential to improve soil fertility in Cameroon. These two soils were used to inoculate to the host plants cowpea and siratro. At harvest, 120 rhizobacterial isolates were extracted from the nodules of these two hosts and subjected to morphological characterization. Twenty isolates per site were selected and analyzed for their 16S rDNA genetic profile following restrictions with endonucleases of PCR products and electrophoresis. The restriction patterns of the 16S rDNA of the 40 isolates showed 12 different profiles. Eight occurred in both types of soils, where as 4 were specific to the manganese-toxic-acidic soil. While the Al toxicity reduced the nodulation and growth of both plants, the Mn toxicity mostly affect the cowpea. This study ascertained the distribution of rhizobia based on soil characteristics. Further molecular analyses would allow the identification of the isolates recovered as well as their phylogenetical relationships

Modélisation de l'amplification d'une impulsion laser UV nanoseconde dans un milieu à excimères

National audienc