Status of large mammals in the mountain sector of Kahuzi-Biega National Park, Democratic Republic of Congo, in 1996

Kahuzi-Biega National Park, located in eastern Democratic Republic of Congo, harbours an abundance of endemic species and maintains important populations of Grauer's gorilla ( Gorilla gorilla graueri ) and elephants ( Loxodonta africana ). This paper reports on the status of large mammals within the mountain sector of the park in 1996, 2 years after the arrival of half a million Rwandan refugees in the area immediately adjacent to the sector. Large mammal surveys found that gorilla populations had remained stable and that elephants were concentrated within a subsector of the area. However, although chimpanzees ( Pan troglodytes ), blue monkeys ( Cercopithecus mitis ), and owl-faced monkeys ( C. hamlyni ) were abundant and widespread, most terrestrial mammal species were found in very low densities and had been subjected to poaching. Nevertheless, important mammal populations remained and complemented the biodiversity conservation value of the park.     

Ecological cues, gestation length, and birth timing in African buffalo (Syncerus caffer)

We examined annual variation in the timing of conception andparturition in the African buffalo (Syncerus caffer) and thesynchrony of birth timing with resource cues, using 8 yearsof monthly birth, rainfall, and vegetation data, measured asNormalized Difference Vegetation Index (NDVI). Monthly birthshad the strongest significant correlations with NDVI and rainfalllevels 12 and 13 months in the past, respectively. In addition,the synchrony of current year births corresponds most stronglyto the synchrony of the previous year's NDVI distribution. Becausethe gestation period of buffalo has been estimated to be around11 months, these findings suggest that improved protein levels,occurring approximately a month after the first green flushof the wet season, are either a trigger for conception or conceptionhas evolved to be synchronous with correlated environmentalcues that ensure females enter a period of peak body conditionaround the time of conception and/or parturition. With a gestationperiod of approximately 340 days, parturition occurs to takeadvantage of the period when forage has its highest proteincontent. A comparative analysis of gestation periods withinthe subfamily Bovinae indicates that African buffalo have aprotracted gestation for their body size, which we suggest isan adaptation to their seasonal environment. We also found thatinterannual variation in the birth distribution suggests a degreeof plasticity in the date of conception, and variation in thenumber of calves born each year suggest further synchrony ata timescale longer than a single year.     

Beta-sheet breaker peptide inhibitor of Alzheimer's amyloidogenesis with increased blood-brain barrier permeability and resistance to proteolytic degradation in plasma.

Short synthetic peptides homologous to the central region of Abeta but bearing proline residues as beta-sheet blockers have been shown in vitro to bind to Abeta with high affinity, partially inhibit Abeta fibrillogenesis, and redissolve preformed fibrils. While short peptides have been used extensively as therapeutic drugs in medicine, two important problems associated with their use in central nervous system diseases have to be addressed: (a) rapid proteolytic degradation in plasma, and (b) poor blood-brain barrier (BBB) permeability. Recently, we have demonstrated that the covalent modification of proteins with the naturally occurring polyamines significantly increases their permeability at the BBB. We have extended this technology to iAbeta11, an 11-residue beta-sheet breaker peptide that inhibits Abeta fibrillogenesis, by covalently modifying this peptide with the polyamine, putrescine (PUT), and evaluating its plasma pharmacokinetics and BBB permeability. After a single intravenous bolus injection in rats, both 125I-YiAbeta11 and 125I-PUT-YiAbeta11 showed rapid degradation in plasma as determined by trichloroacetic acid (TCA) precipitation and paper chromatography. By switching to the all D-enantiomers of YiAbeta11 and PUT-YiAbeta11, significant protection from degradation by proteases in rat plasma was obtained with only 1.9% and 5.7% degradation at 15 min after intravenous bolus injection, respectively. The permeability coefficient x surface area product at the BBB was five- sevenfold higher in the cortex and hippocampus for the 125I-PUT-D-YiAbeta11 compared to the 125I-D-YiAbeta11, with no significant difference in the residual plasma volume. In vitro assays showed that PUT-D-YiAbeta11 retains its ability to partially inhibit Abeta fibrillogenesis and dissolve preformed amyloid fibrils. Because of its five- to sevenfold increase in permeability at the BBB and its resistance to proteolysis in the plasma, this polyamine-modified beta-sheet breaker peptide may prove to be an effective inhibitor of amyloidogenesis in vivo and, hence, an important therapy for Alzheimer's disease.     

The oxygen requirements of a polluted estuary for the establishment of a migratory salmon, Salmo salar L., population

The return of salmon in 1978 to the River Gryfe, a tributary of the Clyde estuary, and to the River Clyde itself in 1983, provides the opportunity for the derivation of the threshold oxygen requirements within the estuary for the successful migration of both adults and smolts.     

Sendai virus P gene produces multiple proteins from overlapping open reading frames

The Sendai virus P gene contains overlapping open reading frames (ORFs), and several unusual mechanisms are used to produce multiple proteins from all three ORFs of this gene. These include the use of a non-AUG start codon, leaky ribosomal scanning, what appears to be scanning-independent ribosomal initiation and/or ribosomal jumping, and a form of mRNA editing.     

Kupffer cell-hepatocyte interactions and the changes in 1-14C-arachidonate incorporation in response to endotoxin in vitro

The present experiments were undertaken to elucidate the effect of either the hepatocyte (HC) or hepatocyte supernatant on prelabeled endotoxin (LPS)-stimulated Kupffer cell (KC) arachidonic acid utilization. HC, KC, or their coculture were incubated for 18 hours with labeled 1-14C- arachidonic acid followed by a 24 hour incubation with 10 micrograms/ml LPS. LPS had no effect on the percent distribution of labeled arachidonate into the HC phospholipid or neutral lipid. KC showed a decreased percent neutral lipid labeled arachidonic acid distribution with generally no effect on the phospholipid. However, KC:HC cocultures or the addition of HC supernatant to KC exposed to LPS dramatically reversed the labeled arachidonate distribution into the KC with an increased incorporation into neutral lipid. Labeled PGE2 and PGD2 were increased in the KC following incubation with HC supernatant while only labeled PGE2 levels were elevated in the cocultures. The changes in the distribution of cell's labeled arachidonate required the addition of LPS. These results suggest that the HC can promote changes in the lipid fraction during sepsis by elaborating a substance that can modulate labeled arachidonate distribution in the KC lipids as well as stimulate prostaglandin production.