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Scat analysis was used to determine the prey of leopards and lions in the moist savanna habitat of Comoé and Marahoué National Parks, Ivory Coast in 1983, 1990–1993 and 1995–1998. Scat contents were analysed in terms of both the relative frequency of occurrence and the relative prey biomass consumed. Selectivity for prey species was inferred by comparing observed scat counts to expected scat frequencies generated from prey density estimates. Leopards in the Comoé National Park preyed predominately upon small to medium-sized ungulates, preferring species from the forest/savanna ecotone (duikers, bushbuck), whereas species from the savanna (kob, oribi) were hunted below their relative abundance. Several different primate species (colobus monkeys, guenons) from forested habitats and large rodents (cane rats, giant pouched rats) constituted additional prey. After ungulate and primate populations dwindled due to heavy poaching, leopard predation upon large rodents and various types of minor prey items (birds, reptiles) increased significantly, while predation upon the most frequently taken ungulate prey species (kob, bushbuck) became non-selective at the same time. Similar to leopards, the lions in Comoé National Park preyed predominantly upon small to medium-sized ungulates, while large ungulates (hartebeest, buffalo and warthog) made up a surprisingly small proportion of their diet and were not preferentially killed as recorded for eastern and southern Africa. In Marahoué National Park, leopard prey did not show a clear preponderance of ungulates, but large rodents and minor prey items made up a very large proportion of its diet.

The distribution and relative abundance of the common hippo (Hippopotamus amphibius)and the pygmy hippo (Hexaprotodon liberiensis)was studied in the Ivory Coast between 1978 and 1986 by questionnaire survey, interviews, local field investigations and aerial censuses. In addition, the size of the pygmy hippo population in the Tai Forest area was monitored between 1995 and 2001. At the time of the initial study, the common hippo inhabited the Sassandra, Bandama and Comoé rivers, but was abundant only in the Upper Comoé. The pygmy hippo was restricted to the Guinean Forest zone between 7°25’N (Tiapleu Forest Reserve (Forêts Classée)) in the north and 4°18’W (estuary of the Agnebi River) in the east, where it was abundant in undisturbed rainforest areas. Population data are presented from the Comoé, Tai and Azagny national parks where the ecology of both species was studied in greater detail. The total popu lation of the common hippopotamus was estimated at about 1100 animals in 1978 1984, of which at least 70% concentrated during the dry season in the Upper Comoé, Leraba and Iringou rivers. The average dry season population density in the Comoé varied at that time between three and four animals per river kilometre, in groups of five to six, but had dropped to one to two per kilometre in 2002. During the rainy season hippos disperse upstream into smaller tributaries and downstream as far as the coast. As the forest zone is modified by forestry and agriculture, small herds of common hippos have become resident and in some localities are sympatric with the pygmy hippo. Pygmy hippos are solitary animals, confined to home ranges of 50 150 ha. In optimal habitat their population density can be as high as seven animals/km2, averaging about three animals/km2over larger areas of undisturbed rainforest. At present, however, hunting pressure has reduced population densities to 0.8 2.5 animals/km2even in the most favourable ecological conditions of the Tai National Park. Extrapolation of these densities suggests that the total population of pygmy hippos in the Ivory Coast is greater than previously thought, but does not exceed 15 000 animals. Most of these inhabit the Tai National Park and its adjacent protected areas. The remainder occur mainly in various forest reserves (Forêts classées). Ecological factors, which influence population density or limit pop ulation growth of the two different hippo species, are discussed and recommendations made for their conservation.

β-Secretase (BACE) initiates the amyloidogenic processing of the amyloid precursor protein leading to the generation of the β-amyloid, the main component of Alzheimer's disease senile plaques. BACE is a type I transmembrane aspartyl protease of 501 amino acids. Here we describe a novel BACE mRNA lacking 132 base pairs that is expressed in the pancreas but not in the brain. Sequence alignment indicates that the deleted fragment matches the terminal two-thirds of exon 3. The new BACE variant is short of a 44-amino acid region located between the two catalytic aspartyl residues. Accordingly, a 50-kDa form of BACE (BACE457) is detected in the human pancreas. When expressed in cells, BACE457 colocalizes with the marker for the endoplasmic reticulum BiP. Moreover, BACE457 remains in a proenzymatic and endoglycosidase H-sensitive state, suggesting that its transport along the secretory pathway is blocked at the level of the endoplasmic reticulum. Notably, this novel form of BACE does not contribute to the processing of the amyloid precursor protein. Our findings suggest that tissue-specific splicing of the BACE mRNA may explain the observation that in the human pancreas robust transcription of the BACE gene does not translate into recovered enzymatic activity.

Clustering of neurotransmitter receptors in postsynaptic densities involves proteins that aggregate the receptors and link them to the cytoskeleton. In the case of glycine and GABAAreceptors, gephyrin has been shown to serve this function. However, it is unknown whether gephyrin is involved in the clustering of allglycine and GABAAreceptors or whether it interacts only with specific isoforms. This was studied in the retinae of mice, whose gephyrin gene was disrupted, with immunocytochemistry and antibodies that recognize specific subunits of glycine and GABAAreceptors. Because homozygous (geph−/−) mutants die around birth, an organotypic culture system of the mouse retina was established to study the clustering of gephyrin and the receptors in vitro. We found that all gephyrin and all glycine receptor clusters (hot spots) were abolished in the geph(−/−) mouse retina. In the case of GABAAreceptors, there was a significant reduction of clusters incorporating the γ2, α2, and α3 subunits; however, a substantial number of hot spots was still present in geph(−/−) mutant retinae. This shows that gephyrin interacts with allglycine receptor isoforms but with only certain forms of GABAAreceptors. In heterozygous geph(+/−) mutants, no reduction of hot spots was observed in the retina in vivo, but a significant reduction was found in the organotypic cultures. This suggests that mechanisms may exist in vivo that allow for the compensation of a partial gephyrin deficit. J. Comp. Neurol. 427:634–648, 2000. © 2000 Wiley‐Liss, Inc.