Genetic variation in Coffea canephora L. (Var. Robusta) accessions from the founder gene pool evaluated with ISSR and RAPD

Discovered in Congo in 1898, Coffea canefora var. robusta accounts for 25 to 40% of the coffee grown in the world. Most genetic diversity of robusta coffee accessions conserved in ex situ collections hasbeen estimated from morphological characteristics. There are limited studies on genetic variability and diversity in C. robusta. Inter-simple sequence repeat (ISSR) and random amplified polymorphic DNA(RAPD) markers were used to assess the level of genetic variability among robusta coffee accessions from the founder gene pool in the Democratic Republic of Congo (DRC). The present study clearlyestablished the high variability in the Congolese genepool. RAPD primers detected a higher level of polymorphic loci (95%) than ISSR markers (52%). Each accession could be genotyped using RAPDmarkers and both markers were efficient in revealing the genetic variability. Jaccard’s similarity coefficients generated to determine the genetic distances among accessions, revealed that most of theaccessions were genetically distant from each other. The accessions tested represent useful genetic materials for breeding for resistance to tracheomycose and other traits in DRC

Field Assessment of the Potential Role of Fusarium Species in the Pathogenesis of Coffee Wilt Disease in Democratic Republic of Congo

Aim: To determine the probable role of 3 species of Fusarium (F. falciforme, F. solani and                       F. stilboides) in the pathogenesis of Coffee Wilt Disease (CWD). Study Design: The field trial was performed using a Randomized Completed Block Design (RCBD) replicates three times. Place and Duration of the Study: The study was conduct in the Experimental Garden of Department of Biology, Faculty of Sciences, University of Kinshasa in Democratic Republic of Congo, between November 2005 and February 2006. Methodology: Four Fusarium species (F. falciforme, F. solani, F. stilboides and F. xylarioides) were inoculated alone, or the first three strains were inoculated in combination with F. xylarioides in coffee seedlings 10 months old. Observations were focused on the time of expression of main CWD symptoms, the rate of each symptom observed, and the presence of each pathogen in dead woods of inoculated seedlings.   Results: Results obtained showed that all Fusarium species induced main symptoms of CWD at varying moment and degrees. Chronologically, leaf yellowing appeared an average 25 dai, followed by leaf browning (46 dai), leaf drying (61 dai), mortality (75 dai) and defoliation (77 dai). Significant differences (P = .05) were observed between treatments considered. All Fusarium induced seedlings mortality and were isolated in dead woods at 1 – 4 cm from the point of inoculation. In general, the search of synergistic interaction between Fusarium spp. inoculated in combination with F. xylarioides showed enhanced ability to induce various symptoms of CWD when species are used together.  Conclusion: The present study demonstrates that CWD could be reconsidered as a parasitic complex, and in natural conditions all Fusarium species used present a danger for coffee growing

Field Assessment of the Potential Role of Fusarium Species in the Pathogenesis of Coffee Wilt Disease in Democratic Republic of Congo

Aim: To determine the probable role of 3 species of Fusarium (F. falciforme, F. solani and                       F. stilboides) in the pathogenesis of Coffee Wilt Disease (CWD). Study Design: The field trial was performed using a Randomized Completed Block Design (RCBD) replicates three times. Place and Duration of the Study: The study was conduct in the Experimental Garden of Department of Biology, Faculty of Sciences, University of Kinshasa in Democratic Republic of Congo, between November 2005 and February 2006. Methodology: Four Fusarium species (F. falciforme, F. solani, F. stilboides and F. xylarioides) were inoculated alone, or the first three strains were inoculated in combination with F. xylarioides in coffee seedlings 10 months old. Observations were focused on the time of expression of main CWD symptoms, the rate of each symptom observed, and the presence of each pathogen in dead woods of inoculated seedlings.   Results: Results obtained showed that all Fusarium species induced main symptoms of CWD at varying moment and degrees. Chronologically, leaf yellowing appeared an average 25 dai, followed by leaf browning (46 dai), leaf drying (61 dai), mortality (75 dai) and defoliation (77 dai). Significant differences (P = .05) were observed between treatments considered. All Fusarium induced seedlings mortality and were isolated in dead woods at 1 – 4 cm from the point of inoculation. In general, the search of synergistic interaction between Fusarium spp. inoculated in combination with F. xylarioides showed enhanced ability to induce various symptoms of CWD when species are used together.  Conclusion: The present study demonstrates that CWD could be reconsidered as a parasitic complex, and in natural conditions all Fusarium species used present a danger for coffee growing

Variation spatiale du risque pour les porcs de contracter la trypanosomiase dans la zone périurbaine de Kinshasa

Afin de mieux comprendre le risque de transmission de la trypanosome animale africaine (TAA) et humaine (THA) en zone périurbaine de Kinshasa, une étude sérologique a été réalisée dans des élevages porcins entre 2003 et 2005. Un test ELISA indirect a été utilisé pour détecter la présence d’anticorps dirigés contre les trypanosomes sur un échantillon de 1240 porcs provenant de 404 fermes. 155 fermes (soit 38 %) se sont révélées séropositives avec une grande variation suivant la commune. Dans 6 % des fermes, des cas de TAA ont pu être démontrés par l’examen parasitologique. Des piégeages (n = 367) aux alentours des fermes ont permis de capturer 1935 mouches tsé-tsé (Glossina fuscipes quanzensis). Sur 562 mouches disséquées, 23 contenaient des trypanosomes soit un taux d’infestation de 4,1 %. Le risque de transmission de la trypanosomose animale, escompté à partir des captures du vecteur, est confirmé dans la plupart des communes par les résultats sérologiques. Des zones à forte probabilité de transmission de TAA ont été identifiées dans plusieurs quartiers situés dans trois communes périurbaines de Kinshasa : Mont-Ngafula, Ngaliema et N’Sele. Une intensification de la lutte anti-vectorielle s’impose dans les endroits à risque

Variation spatiale du risque pour les porcs de contracter la trypanosomose dans la zone périurbaine de Kinshasa

Afin de mieux comprendre le risque de transmission de la trypanosome animale africaine (TAA) et humaine (THA) en zone périurbaine de Kinshasa, une étude sérologique a été réalisée dans des élevages porcins entre 2003 et 2005. Un test ELISA indirect a été utilisé pour détecter la présence d’anticorps dirigés contre les trypanosomes sur un échantillon de 1240 porcs provenant de 404 fermes. 155 fermes (soit 38 %) se sont révélées séropositives avec une grande variation suivant la commune. Dans 6 % des fermes, des cas de TAA ont pu être démontrés par l’examen parasitologique. Des piégeages (n = 367) aux alentours des fermes ont permis de capturer 1935 mouches tsé-tsé (Glossina fuscipes quanzensis). Sur 562 mouches disséquées, 23 contenaient des trypanosomes soit un taux d’infestation de 4,1 %. Le risque de transmission de la trypanosomose animale, escompté à partir des captures du vecteur, est confirmé dans la plupart des communes par les résultats sérologiques. Des zones à forte probabilité de transmission de TAA ont été identifiées dans plusieurs quartiers situés dans trois communes périurbaines de Kinshasa : Mont-Ngafula, Ngaliema et N’Sele. Une intensification de la lutte anti-vectorielle s’impose dans les endroits à risque

Long-term expression of melanopsin and channelrhodopsin causes no gross alterations in the dystrophic dog retina

International audienceSeveral preclinical studies have investigated the potential of algal channelrhodopsin and human melanopsin as optogenetic tools for vision restoration. In the present study, we assessed the potentially deleterious effects of long-term expression of these optogenes on the diseased retina in a large animal model of retinal degeneration, the RPE65-deficient Briard dog model of Leber congenital amaurosis. Intravitreal injection of adeno-associated virus vectors expressing channelrhodopsin and melanopsin had no effect on retinal thickness over a 16-month period post injection. Our data support the safety of the optogenetic approach for the treatment of blindness

Long-term expression of melanopsin and channelrhodopsin causes no gross alterations in the dystrophic dog retina

International audienceSeveral preclinical studies have investigated the potential of algal channelrhodopsin and human melanopsin as optogenetic tools for vision restoration. In the present study, we assessed the potentially deleterious effects of long-term expression of these optogenes on the diseased retina in a large animal model of retinal degeneration, the RPE65-deficient Briard dog model of Leber congenital amaurosis. Intravitreal injection of adeno-associated virus vectors expressing channelrhodopsin and melanopsin had no effect on retinal thickness over a 16-month period post injection. Our data support the safety of the optogenetic approach for the treatment of blindness