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Zur Biologie der Diplopoden
(1891)
The land use in the Tangale-Waja area is analysed according to the two basic categories of geography: Firstly the manifold interaction between men and environment which form the spatial characteristics of an area, and secondly the decrease of influence with increasing distance. The importance of these two elementary factors is described by indicators as accessibility for the period from the precolonial situation until the time after World War II, when new roads were constructed through the mountainous area. Living in a hilly environment the self contained population (formerly called "hill pagans") had developed special agricultural techniques which can be considered ecologically well adapted. The opening up of the area after the pacification, Christianity and education, led to a considerable increase in population, the expansion of land under cultivation, and the change of settlement structure by down-hill population movement. This resulted in overuse of the fragile natural resources. The size of farm steads became too small for the family unit and the still low accessibility of the hinterland of the main interregional roads as well as inappropriate techniques of agricultural production are shortcomings causing heavy damage to the physical environment and decreasing living standards of the local population.
Occupation du sol et potentiel de l'environnement chez les Gulmance dans l'est du Burkina Faso
(1993)
Dans l'est de Burkina Faso, dans le pays Gulma, le potentiel naturel, c'est à dire la géologie, le relief, les sols, l'hydrologie, la végétation et l'utilisation par l'homme est l'objet d'un levé scientifique. Les conditions données sont mises en évidence pour rendre claire le modèle de colonisation du peuple dans son cadre naturel. Dans ce sens il est particulièrement important de savoir quelle connaissance exacte les paysans ont de leur environnemt et quels facteurs ils font intervenir dans l'exploitation de cet environnement. Dans l'ensemble il apparait une différenciation selon la répartition de la densité du pays; à côté des zones fortement peuplées, d'autres restent pratiquement vides. De là découle aussi la densité et la nature des savanes.
In an effort to link quantitative morphometric information with molecular data on the population level, we have analysed 19 populations of the conchologically variable land snail Candidula unifasciata from across the species range for variation in quantitative shell traits and at the mitochondrial 16S ribosomal (r)DNA locus. In genetic analysis, including 21 additional populations, we observed two fundamental haplotype clades with an average pairwise sequence divergence of 0.209 ± 0.009 between clades compared to 0.017 ± 0.012 within clades, suggesting the presence of two different evolutionary lineages. Integrating additional shell material from the Senckenberg Malacological Collection, a highly significant discriminant analysis on the morphological shell traits with fundamental haplotype clades as grouping variable suggested that the less frequent haplotype corresponds to the described subspecies C. u. rugosiuscula, which we propose to regard as a distinct species. Both taxa were highly subdivided genetically (FST = 0.648 and 0.777 P < 0.001). This was contrasted by the partition of morphological variance, where only 29.6% and 21.9% of the variance were distributed among populations, respectively. In C. unifasciata, no significant association between population pairwise FST estimates and corresponding morphological fixation indices could be detected, indicating independent evolution of the two character sets. Partial least square analysis of environmental factors against shell trait variables in C. u. unifasciata revealed significant correlations between environmental factors and certain quantitative shell traits, whose potential adaptational values are discussed.
Ribosomal proteins are assumed to stabilize specific RNA structures and promote compact folding of the large rRNA. The conformational dynamics of the protein between the bound and unbound state play an important role in the binding process. We have studied those dynamical changes in detail for the highly conserved complex between the ribosomal protein L11 and the GTPase region of 23S rRNA. The RNA domain is compactly folded into a well defined tertiary structure, which is further stabilized by the association with the C-terminal domain of the L11 protein (L11ctd). In addition, the N-terminal domain of L11 (L11ntd) is implicated in the binding of the natural thiazole antibiotic thiostrepton, which disrupts the elongation factor function. We have studied the conformation of the ribosomal protein and its dynamics by NMR in the unbound state, the RNA bound state and in the ternary complex with the RNA and thiostrepton. Our data reveal a rearrangement of the L11ntd, placing it closer to the RNA after binding of thiostrepton, which may prevent binding of elongation factors. We propose a model for the ternary L11–RNA–thiostrepton complex that is additionally based on interaction data and conformational information of the L11 protein. The model is consistent with earlier findings and provides an explanation for the role of L11ntd in elongation factor binding.
In the inundation area - the basin of the former larger Lake Chad - a special type of sorghum is grown on the clay soils (firgi). This dry-season guinea corn is also called dwarf sorghum or masakwa. In Kanuri, the dominant language in the region, sorghum is called ngawuli. The dry-season types are called ngawuli firgibe (lit. translated: sorghum of the firgi). During the dry season when the natural vegetation becomes dry and yellow, masakwa fields appear in prominent green covering large areas of the clay plains. The most important natural factor for this specialized dry season cropping is the presence of soils with a high clay content. For a better understanding of masakwa and its related issues, a multidisciplinary sub-project (G1) has been established within the SFB 268 (Joint Research Project: History of Culture and Language in the Natural Environment of the West-African Savannah). This project in which all disciplines participate is entitled: "Natural basis for masakwa cultivation and its meaning for the settlement history of the clay plains (firgi) in the Chad basin".