Implications of local knowledge of the ecology of a wild super sweetener for its domestication and commercialization in West and Central Africa

Despite its local use as a fiber and international trade in thaumatin, the intensely sweet protein derived from its fruit, little ecological information aboutThaumatococcus daniellii (Benn.) Benth. is in the public domain. Here, we combine systematic studies of the local knowledge of plant collectors and cultivators in Ghana with a thorough evaluation of the plant’s natural distribution in order to explore possibilities for increasing the contribution that it makes to sustaining rural livelihoods in West and Central Africa. The natural range goes well beyond where commercial collection and cultivation have been previously reported. Local knowledge was found to be detailed and explanatory. Its acquisition has refined our understanding of the ecology of the plant, although some significant gaps remain, particularly with respect to pollination. The market for thaumatin is ripe for expansion, and the plant has untapped potential as an intercrop for rubber and cocoa. Further domestication needs to be accompanied by consideration of impacts on the livelihoods of those who presently collect fruit from the wild, and of opportunities for increasing the value that accrues within Africa through the development of local processing capacity.     

The Pretoria Bone Collection: a modern South African skeletal sample.

The Pretoria Bone Collection began with the inception of the Department of Anatomy and the Medical School at the University of Pretoria in August 1942. Since then the collection has grown from a student aid to a resource for research. In the year 2000, the Pretoria Bone Collection was reorganised. The research material was divided into skulls, complete postcranial and incomplete postcranial remains. The collection presently contains 290 complete skeletons, 704 complete skulls and 541 complete postcranial remains. This paper presents information on the composition of this collection and hopes to heighten both national and international awareness of the collection and research opportunities in South Africa.     

Efficient analysis of hepatic glucose output and insulin action using a liver slice culture system.

BACKGROUND: Liver slices have been reported to retain histological integrity and metabolic capacity for over 24 hours in flask culture systems, and they have been used for pharmacological and toxicological studies before. However, whether this method is suitable to measure hepatic glucose output is unknown. METHODS: Precision-cut liver slices were prepared from fresh male rat liver. After high-glucose pre-incubation (11.2 mmol/l), medium was changed to low-glucose conditions (0.5 mmol/l). Glucose and lactate levels as well as aspartate aminotransferase activity were monitored for 50 minutes with or without addition of insulin (600 pmol/l) and/or epinephrine (0.5 micromol/l). Slice potassium content and histology were examined to prove liver viability. RESULTS: We observed a stable glucose production from the liver slices of 0.3-0.4 micromol/g liver/min. Epinephrine increased (by 82+/-30%) and insulin decreased (by 80+/-8%) liver slice glucose output. Significant signs of ischemia were not detected. CONCLUSIONS: Hepatic glucose release can be reliably measured in a liver slice culture system, and it is regulated by major hormone systems. This method may be helpful for further characterization of direct insulin action and resistance in a complex tissue as the liver; however, pharmacological applications such as the analysis of drug effects on hepatic glucose metabolism can also be envisioned.     

Can increased niche opportunities and release from enemies explain the success of introduced Yellowhammer populations in New Zealand?

Some introduced species succeed spectacularly, becoming far more abundant in their introduced than in their native range. 'Increased niche opportunities' and 'release from enemy regulation' are two hypotheses that have been advanced to explain the enhanced performance of introduced species in their new environments. Using an introduced bird species, the Yellowhammer Emberiza citrinella , which was first released in New Zealand in 1862, as a model, we tested some predictions based on these hypotheses. By quantifying habitat availability and quality, and measuring nest predation rates, we investigated whether increased niche opportunities or release from nest predation could explain the higher density of the Yellowhammer in New Zealand farmland, compared to farmland in their native Britain. Yellowhammer territory densities were over three times higher in New Zealand (0.40 territories per ha) than in comparable British farmland (0.12 territories per ha), and Yellowhammer densities remained significantly higher in New Zealand, after accounting for differences in habitat availability. The density and diversity of invertebrates, a key food resource for nestling Yellowhammers, was significantly lower in New Zealand than in Britain. Hence, these aspects of niche availability and quality cannot explain the higher density of Yellowhammers in New Zealand. Nest predation rates in New Zealand were similar to those in Britain, suggesting that release from nest predation also could not account for the higher density of Yellowhammers in New Zealand. Differences in winter survival, due to differences in winter food supply or the severity of the winter climate, along with release from other types of 'enemy' regulation are possible alternative explanations.     

An investigation of habitat occupancy by the nightingale Luscinia megarhynchos with respect to population change at the edge of its range in England

The nightingale Luscinia megarhynchos has undergone population decline and range contraction at the north-western limit of its distribution in England during the last 25 years. We examine patterns of habitat occupancy and habitat availability across sites with a range of population histories to see whether habitat loss is a plausible explanation for these declines. The number of singing males in 1999 correlated with area of primary nightingale habitat in the East Midlands (where the species has declined), but not in East Anglia (where the population has been stable). Change in population size between 1980 and 1999 and current habitat availability were weakly correlated in the East Midlands but not in East Anglia. These results are consistent with habitat loss having contributed to the decline of the nightingale in the East Midlands, but suggest that other, wider-scale, factors may be at least partially responsible for determining the abundance of the species within England as a whole.     

Evolutional Genetics and Diseases of Civilization

Inclination for hyperinsulinemia that was formed in the human population at early stages of development and was fixed genetically in the process of evolution is suggested to underlie pathogenesis of the currently most widely spread diseases of the cardiovascular system (atherosclerosis and hypertension) as well as diabetes mellitus of the 2 type and obesity that are concomitant with a high frequency. Under conditions of civilization, chronic hyperinsulinemia can develop in response to the regularly excessive nutrition. The consequence of the excessive food consumption and the chronic hyperinsulinemia can be overcrowding with lipids (triglycerides) of adipose tissue—the organism lipid store. The natural protective reaction of the cell that contains the limitedly possible amount of lipids is a decrease of the number of insulin receptors and development of insulin resistance. The insulin resistance, in turn, provides the appearance of hyper- and dislipoproteinemia alongside with hyperglycemia. One of the most clinically significant ways of achievement of homeostasis is storage of lipids in the arterial wall. Atherogenic and other concomitant metabolic disorders, specifically changes of blood coagulation properties providing susceptibility to hypercoagulation, affect the blood rheological properties and seem to lead to pathology of the entire vascular system: chronic venous insufficiency, disturbance of microcirculation, and arterial atherosclerosis. There is substantiated the natural interconnection of atherosclerosis, type 2 diabetes, obesity, and arterial hypertension that at present are accepted as the main clinical manifestations of the so-called “metabolic syndrome.” It is suggested that the basis for arterial hypertension might be disturbances of microcirculation leading to an increase of peripheral vascular resistance as well as insufficiency of renal blood supply at the level of arterial and microcirculatory bed.__________Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 41, No. 2, 2005, pp. 186–191.Original Russian Text Copyright © 2005 by Liberman.