Que planter dans ma parcelle ? Arbre de décision pour le choix des espèces et des systèmes agroforestiers en périphérie de Kinshasa

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Identifier les espèces de mammifères d'Afrique centrale morphologiquement proches ou peu fréquentes sur pièges photographiques

Une compilation de fiches d’identification détaillées des espèces de mammifères d'Afrique centrale morphologiquement proches ou peu fréquentes sur pièges photographique

Impacts of selective logging on forest elephants (Loxodonta cyclotis) in two timber concessions of central Africa

Facing increasing human pressure, forest elephant (Loxodonta cyclotis) populations have been seriously declining for many years. As they are key actors in shaping ecosystems, their decline will have severe ecological consequences. Covering 30 percent of the central African rainforest, timber concessions constitute areas with a great stake in the conservation of this emblematic and critically endangered species. Although several studies have documented a high presence of forest elephants in some logged forests, many uncertainties remain about the impacts of logging on forest elephants. Using camera traps, acoustic recorders and dung counts, we explored the short-term consequences of logging on forest elephants’ abundance in two certified timber concessions, one in Cameroon and one in Gabon. In Cameroon, 24 camera traps and 12 acoustic recorders were set up for two months in two nearby areas: one that had just been logged and one where the last logging operation was conducted over 17 years ago. In Gabon, dung counts along 73 km of line transects were conducted in one annual allowable cut, eight months before and nine months after logging. The camera trap study in Cameroon showed no significantly different forest elephant detection rates between the recently and the formerly logged areas. A similar result was obtained with the acoustic data. In Gabon, the post-logging survey recorded more than twice as many forest elephant dung as the pre-logging survey. These results support the suggestion that selective logging, when carried out under controlled and sustainable management (ie., closure of old logging roads, law enforcement, low impact logging, etc.), is compatible with the conservation of the forest elephant. Nevertheless, additional studies are needed, especially to assess long-term and behavioral impacts. Ongoing studies on the use of skidding trails and logging roads by large mammals, forest elephant-mediated seed dispersal and herbivory damage in timber concessions, will provide new insights on the coexistence of forest elephants and selective logging

A morphological study of the shape of the corpus callosum in normal, schizophrenic and bipolar patients

Abnormalities in the morphology of the corpus callosum have been found to be involved in cognitive impairments or abnormal behaviour in patients with mental disorders such as schizophrenia and bipolar disorder. The present study investigated morphological shape differences of the corpus callosum in a large cohort of 223 participants between normal, schizophrenic and bipolar patients on MRI scans, CT scans and cadaver samples. Healthy samples were compared to a mental disorder population sample to determine morphological shapes variations associated with schizophrenia and bipolar disorder. Landmark-based methodology was used to contour the corpus callosum shape that served as standard positions to allow for radial and thickness partitioning in order to determine shape variations within the specific localised anatomical sections of the corpus callosum. Shape analysis was performed using Ordinary Procrustes averaging and superimposing landmarks to define an average landmark position for the specific regions of the corpus callosum. No significant global shape differences were found between the different mental disorders. Schizophrenia and bipolar shapes differed mostly in the genu-rostrum, posterior body, isthmus and splenium. Sample group comparisons yielded significant differences between all groups and global measurement parameters and in various sub-regions. The findings of the present study suggest that the corpus callosum in schizophrenia and bipolar differs significantly compared to healthy controls, specifically in the anterior body and isthmus for schizophrenia and only in the isthmus for bipolar disorder. Shape changes in these regions may possibly, in part, be responsible for the symptoms and cognitive impairments observed in schizophrenia and bipolar disorder.http://wileyonlinelibrary.com/journal/joahj2023AnatomyPhysiolog

Intestinal region-specific Wnt signalling profiles reveal interrelation between cell identity and oncogenic pathway activity in cancer development.

BACKGROUND: Cancer results from the accumulation of mutations leading to the acquisition of cancer promoting characteristics such as increased proliferation and resistance to cell death. In colorectal cancer, an early mutation leading to such features usually occurs in the APC or CTNNB1 genes, thereby activating Wnt signalling. However, substantial phenotypic differences between cancers originating within the same organ, such as molecular subtypes, are not fully reflected by differences in mutations. Indeed, the phenotype seems to result from a complex interplay between the cell-intrinsic features and the acquired mutations, which is difficult to disentangle when established tumours are studied. METHODS: We use a 3D in vitro organoid model to study the early phase of colorectal cancer development. From three different murine intestinal locations we grow organoids. These are transformed to resemble adenomas after Wnt activation through lentiviral transduction with a stable form of β-Catenin. The gene expression before and after Wnt activation is compared within each intestinal origin and across the three locations using RNA sequencing. To validate and generalize our findings, we use gene expression data from patients. RESULTS: In reaction to Wnt activation we observe downregulation of location specific genes and differentiation markers. A similar effect is seen in patient data, where genes with significant differential expression between the normal left and right colon are downregulated in the cancer samples. Furthermore, the signature of Wnt target genes differs between the three intestinal locations in the organoids. The location specific Wnt signatures are dominated by genes which have been lowly expressed in the tissue of origin, and are the targets of transcription factors that are activated following enhanced Wnt signalling. CONCLUSION: We observed that the region-specific cell identity has a substantial effect on the reaction to Wnt activation in a simple intestinal adenoma model. These findings provide a way forward in resolving the distinct biology between left- and right-sided human colon cancers with potential clinical relevance

The Role of Agriculture in the UN Climate Talks

Agriculture, and consequently food security and livelihoods, is already being affected by climate change, according to latest science from the IPCC. The various strands of work already underway on agriculture within the UNFCCC process can be strengthened and made more coherent. A 2015 climate agreement should reference food production and provide the financial, technical and capacity building support for countries to devise ambitious actions for the agricultural sector. A new climate agreement should be consistent with the Sustainable Development Goal (SDG) proces

Interactions between forest elephants (Loxodonta cyclotis) and selective logging in central Africa

With populations reduced by more than 80% over the last 93 years, forest elephants (Loxodonta cyclotis) are facing increasing human pressure. As observed in previous megaherbivore extinctions, the decline of forest elephants will have serious ecological consequences. Regularly referred to as ecosystem engineers, forest elephants shape tropical ecosystems, both in composition and structure, due to their enormous food requirements and the impact of their massive body size. They maintain the forest’s richness and diversity by dispersing the seeds of many species, create micro-habitats and maintain nutrient cycles and forest clearings. Given their extent, timber concessions could be a major actor in forest elephant conservation, but it is still necessary to better understand the impacts of logging on forest elephants and conversely the impacts of forest elephants on timber resources. Therefore, our study aims to (1) assess the impacts of logging activities on the presence, abundance and movement of forest elephants; (2) evaluate the importance of forest elephants in the regeneration of several timber species and (3) characterize the damage caused by forest elephants to trees and forest plantations. The methods applied are diverse and include among others the use of camera traps and acoustic sensors, dung count on transects and bark damage surveys on transects and in plots. Preliminary findings suggest that (1) under specific conditions, timber concessions can host large populations of forest elephants; (2) forest elephants are the main seed dispersers of Detarium macrocarpum and Bobgunnia fistuloides, two timber species, and (3) from branch breaking to bark stripping, forest elephant damage is diverse and affects a wide range of species, which seem to evolve over time