Africanizing scientific knowledge: the Multilateral Initiative on Malaria as a model?

In November 2009, the fifth Pan African Malaria conference was held in Nairobi. Thirteen years after the founding initiative in Dakar, the first African Secretariat based in Africa (TANZANIA) organized this major event for the malaria community. Looking back, it has been a long way: changes in the research landscape, new funding opportunities came out and establishment of new partnerships between Europe, America and Africa. Goals identified in 1997 have not all been achieved because the critical mass of scientists has not been reached yet. However a new generation of African scientists have emerged through MIM/TDR funding and advocacy for more support remains on the agenda. Could it be rightly stated today that the MIM concept reflects the africanization of malaria research?     

Invertebrate learning: what can't a worm learn?

The nematode worm Caenorhabditis elegans can learn and remember the stimuli it encounters, the environment it is in, and its own physiological state. Analyses of mutations in C. elegans that affect different aspects of experience are beginning to address the nature of learning.     

Yeast as a model to study apoptosis?

Programmed cell death (PCD) serves as a major mechanism for the precise regulation of cell numbers, and as a defense mechanism to remove unwanted and potentially dangerous cells. Despite the striking heterogeneity of cell death induction pathways, the execution of the death program is often associated with characteristic morphological and biochemical changes termed apoptosis. Although for a long time the absence of mitochondrial changes was considered as a hallmark of apoptosis, mitochondria appear today as the central executioner of programmed cell death. This crucial position of mitochondria in programmed cell death control is not due to a simple loss of function (deficit in energy supplying), but rather to an active process in the regulation of effector mechanisms.The large diversity of regulators of apoptosis in mammals and their numerous interactions complicate the analysis of their individual functions. Yeast, eukaryotic but unicellular organism, lack the main regulators of apoptosis (caspases, Bcl-2 family members, . . .) found in mammals. This absence render them a powerful tool for heterologous expression, functional studies, and even cloning of new regulators of apoptosis.Great advances have thus been made in our understanding of the molecular mechanisms of Bcl-2 family members interactions with themselves and other cellular proteins, specially thanks to the two hybrid system and the easy manipulation of yeast (molecular biology and genetics).This review will focus on the use of yeast as a tool to identify new regulators and study function of mammalian apoptosis regulators.     

Prostaglandins as reducing agents: a model of adenylate cyclase activation?

It has been suggested that adenylate cyclase activation involves reduction of a disulfide linkage. Prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), prostaglandin I2 (PGI2) and prostaglandin F2 alpha (PGF2 alpha) were tested for their ability to act as reducing agents with either cytochrome c, or the disulfide 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), the latter with a catalytic amount of ferric chloride. PGE1, PGE2, and PGI2 significantly reduced cytochrome c while PGF2 alpha did not. PGE1, PGE2 and PGI2 reduced DTNB while PGF2 alpha did not. The results are consistent with the postulate that prostaglandins which are effective in activating adenylate cyclase can act as reducing agents and might be involved in reductive activation of adenylate cyclase.     

Homing pigeons as a model for avian navigation?

The findings on the navigational mechanisms of homing pigeons and the available data on those of wild birds, in particular migrants, are compared. There are important parallels in the use of the magnetic field and the sun for directional orientation. Also the findings on the navigational ‘map’, its preferred use by experienced birds and the strategy of using route information to acquire the necessary knowledge to establish the ‘map’, obtained in pigeons studies, can probably be generalized to wild birds and migrants in their home region. It seems that birds share a common navigational system. Special development of migratory birds, however, is the innate migration program that enables young first‐time migrants to reach their still unknown wintering area.     

Europe as a model for large carnivores conservation: Is the glass half empty or half full?

At first sight, the increasing trend of many large mammal populations in EU Member States are the results from successful application of EU environmental legislation. In this perspective a ‘rewilding’ Europe appears as a laudable conservation goal. It has been therefore suggested that the EU model of carnivores-humans coexistence could be of interest to several other regions of the Planet. In the present paper we critically review alleged successes of the EU conservation policies. Our conclusions suggest that some optimistic reports should be taken cautiously. Firstly, one should not lose sight of the heterogeneity of ‘Europe’ and the different histories and socio-ecological situations of the 28 Member States. Furthermore, we doubt whether the positive status of large carnivores in Eastern Europe is attributable exclusively to EU conservation policies. Long time spans necessary for demographic recovery in large carnivores sharply contradict the quite recent entry of these countries into the EU. The EU model is possible owing to the unique socio-economic development that Western Europe experienced after the Second World War. Economic growth, urbanization, rural abandonment and reforestation are the main forces behind the increase of large mammals in some areas of Western Europe. Yet this has been possible only through a considerable input of natural resources from outside EU (food, raw materials, oil, gas etc.). Therefore, although there are examples that could be considered good experiences, we are of the opinion that the EU policies as a general model is unlikely to be exportable world-wide and may have negative consequences for wildlife, even in Eastern Europe.     

Guinea worm disease – the final chapter?

The global campaign for the eradication of dracunculiasis has succeeded in reducing the incidence of guinea worm disease by >99% in the past 20 years. This has been accomplished by the provision of safe drinking water supplies, filtration of drinking water, chemical control of intermediate hosts, case containment and, crucially, local health-education initiatives.     

Can zebrafish be used as a model to study the neurodevelopmental causes of autism?

The zebrafish has proven to be an excellent model for analyzing issues of vertebrate development. In this review we ask whether the zebrafish is a viable model for analyzing the neurodevelopmental causes of autism. In developing an answer to this question three topics are considered. First, the general attributes of zebrafish as a model are discussed, including low cost maintenance, rapid life cycle and the multitude of techniques available. These techniques include large-scale genetic screens, targeted loss and gain of function methods, and embryological assays. Second, we consider the conservation of zebrafish and mammalian brain development, structure and function. Third, we discuss the impressive use of zebrafish as a model for human disease, and suggest several strategies by which zebrafish could be used to dissect the genetic basis for autism. We conclude that the zebrafish system could be used to make important contributions to understanding autistic disorders.     

Toxocara in the mouse: a model for parasite-altered host behaviour?

The objective of this paper is to critically evaluate the significance of parasite-altered host behaviour in the Toxocara mouse model particularly in the light of the Manipulation Hypothesis. Murine behaviours were examined in both outbred and inbred strains of mice infected with different doses of Toxocara canis ova. Behaviours investigated included activity, exploration, response to novelty, anxiety, learning, memory and social behaviour. Subsequent modifications to the behaviour of infected mice were investigated with respect to dose administered and larval accumulation in the brain. There was substantial variation in the number of larvae recovered from brains of individual mice, which received similar doses of Toxocara ova. Furthermore, the numbers of larvae recovered at different doses differed significantly between an outbred and inbred strain of mouse. Alterations in infected host behaviour occurred and were related to the number of larvae recovered from the brain. For social behaviour in outbred mice, a high infection in the brain reduced levels of aggressive behaviour and increased levels of flight and defensive behaviours. In contrast, outbred mice with a low infection in the brain displayed a greater level of risk behaviour in respect of predator odour and the light/dark box compared to control or high infection mice. Post-infection, outbred mice were more immobile whereas inbred mice showed reduced immobility and increased digging and climbing. Impaired learning ability was observed in outbred mice with moderate and high levels of infection in the brain compared to control and low infection mice. Toxocara infection has an impact upon a diverse range of murine behaviours with little evidence for a specific and hence an adaptive alteration. Many of the effects on murine host behaviour by Toxocara are likely to be pathological side effects of infection rather than as a consequence of adaptive host-manipulation. Observed changes in murine behaviour may be relevant to human toxocariasis.     

The worm and the protozoa: stereotyped responses or distinct antigens?

Studies of parasitic diseases have provided the best in vivo correlates of the division of CD4+ helper T cells into distinct functional phenotypes, designated T(H)I and T(H)2, that mediate the balanced regulation of cellular and humoral immunity. In this article, Steven Reiner and Richard Locksley focus on why parasitic infections tend to generate such clearly polarized responses and emphasize that early events that mediate maturation signals towards T(H)1- or T(H)2-effector and memory cells remain incompletely defined. Effective vaccination that seeks to mold the developing immune response will need to consider the role of interleukins and various cell-surface molecules that have been identified, thus far, to influence CD4 subset differentiation.     

G?ttingen miniature swine as a model for diet-induced atherosclerosis

Twenty-four G?ttingen Miniature Swine/csk, in order to evaluate their potential usefulness as a model for experimental atherosclerosis studies, were fed diets of three types, a high-fat plus high cholesterol diet, a high-fat diet, and a commercial diet. Each group consisted of 4 males and 4 females. Swine fed the experimental diet were investigated by gross, microscopic and serum biochemical examination on the 1st, 3rd, 6th and 9th month after start of experimentation. Lesions of atherosclerosis were observed in the high-fat plus high-cholesterol diet group. After a month on the experimental diet, intimal thickening was detected in the abdominal aorta just above the origin of internal iliac artery, left coronary artery and ascending aorta by microscopic examination. Thereafter, on the 9th month after the start, there was more extensive and severe atherosclerosis. These lesions were classified into two types by the difference in the histologic architecture of arterial wall. One was fatty streaks that were in thoracic aorta belonging to the elastic type and the other was fibrous plaques that were in abdominal aorta and iliac artery and so on, belong to the transitional or muscular type. High-fat plus high-cholesterol diet feeding led to elevated serum cholesterol and beta-lipoprotein levels, and had an effect on several kinds of metabolism. All of the swine fed high-fat or commercial diet had little gross, microscopic lesions and had no change in serum cholesterol and beta-lipoprotein levels. Hypercholesterolemia and hyper-beta-lipoproteinemia had a close relation to the development and acceleration of atherosclerosis. It was possible to show that the diet induced atherosclerosis was similar in quality to that observed in humans, and that the G?ttingen miniature swine was a suitable animal for the study of atherosclerosis.     

What does a worm want with 20,000 genes?

The number of genes predicted for the Caenorhabditis elegans genome is remarkably high: approximately 20,000, if both protein-coding and RNA-coding genes are counted. This article discusses possible explanations for such a high value.