To meet grand challenges, agricultural scientists must engage in the politics of constructive collective action.

Agriculture now faces grand challenges, with crucial implications for the global future. These include the need to increase production of nutrient-dense food, to improve agriculture's effects on soil, water, wildlife, and climate, and to enhance equity and justice in food and agricultural systems. We argue that certain politics of constructive collective action-and integral involvement of agricultural scientists in these politics-are essential for meeting grand challenges and other complex problems facing agriculture in the 21st century. To spur reflection and deliberation about the role of politics in the work of agricultural scientists, we outline these politics of constructive collective action. These serve to organize forceful responses to grand challenges through coordinated and cooperative action taken by multiple sectors of society. In essence, these politics entail (1) building bonds of affinity within a heterogenous network, (2) developing a shared roadmap for collective action, and (3) taking sustained action together. These emerging politics differ markedly from more commonly discussed forms of political activity by scientists, e.g., policy advisory, policy advocacy, and protest. We present key premises for our thesis, and then describe and discuss a politics of constructive collective action, the necessary roles of agricultural scientists, and an agenda for exploring and expanding their engagement in these politics.

Effects of plant-symbiotic relationships on the living soil microbial community and microbial necromass in a long-term agro-ecosystem.

We examined the impact of arbuscular mycorrhizal fungi and rhizobia on the living microbial community and microbial necromass under different long-term fertilization treatments at the long-term Static Fertilization Experiment Bad Lauchstädt (Germany). Phospholipid fatty acids (PLFA) and amino sugars plus muramic acid, were used as biomarkers for soil microbial bio- and necromass, respectively, and analyzed from six treatments imposed on two crop rotations, varying only in the inclusion/non-inclusion of a legume. Treatments included: two levels of only farmyard manure (FYM), only mineral fertilizer (NPK), the combined application of both fertilizer types and a non-fertilized control. PLFA profiles differed clearly between the investigated crop rotations and were significantly related to labile C, mineral N, and soil pH. This emphasizes the role of carbon, and of mycorrhizal and rhizobial symbioses, as driver for changes in the microbial community composition due to effects on the living conditions in soil. We found some evidence that legume associated symbiosis with arbuscular mycorrhizal fungi and rhizobia act as a buffer, reducing the impact of varying inputs of mineral nutrients on the decomposer community. While our results support former findings that living microbial populations vary within short-term periods and are reflective of a given crop grown in a given year, soil necromass composition indicates longer term changes across the two crop rotation types, mainly shaped by fertilizer related effects on the community composition and C turnover. However, there was some evidence that specifically the presence of a legume, affects the soil necromass composition not only over the whole crop rotation but even in the short-term.

Empowering humanitarian medical development using grid technology.

BACKGROUND: The training of local clinicians is the best way to raise the standard of medical knowledge in developing countries. This requires transferring skills, techniques and resources. OBJECTIVES: Grid technology opens new perspectives for preparation and follow-up of medical missions in developing countries as well as support to local medical centers in terms of teleconsulting, telediagnosis and patient follow-up. Indeed, grids allow to hide the complexity of handling distributed data in such a way that physicians will be able to access patient data while ignoring where these data are stored. METHODS: To meet requirements of a development project of the French NPO Chain of Hope in China, we propose to deploy a grid-based federation of databases. FIRST RESULTS AND CONCLUSIONS: A first protocol was established for describing the patients' pathologies and their pre- and post-surgery states through a web interface in a language-independent way. This protocol was evaluated by French and Chinese clinicians during medical missions in the fall of 2003. The first sets of medical patients recorded in the databases will be used to evaluate grid implementation of services.

Biparietal diameter, fetal maturity, and body weight in rural Tanzanian newborns.

The biparietal diameter (BPD) in 202 rural Tanzanian newborns was measured and correlated to maturity and body weight. The mean BPD at birth was 9.0 cm. The average body weight was 2642 g. Fetal maturity was determined by Petrussa score, serving as an estimate for gestational age. The mean gestational age of the 202 newborns was 39 weeks. The average body weight of the mature babies (gestational age 38-40 weeks) was 2765 g. All babies less than 38 weeks of gestation were born with a low birth weight (LBW < or = 2500 g) except for one. The LBW-babies comprised 34 per cent of the total births. About two-thirds of all LBW-babies (62 per cent) were born small for date, only 38 per cent preterm. Regression analysis of the data set was performed resulting in significant models of estimates of gestational age and body weight from BPD as well as body weight from gestational age. In a baby older than 35 weeks of gestation a body weight of more than 1500 g can be expected. With regard to maturity (> or = weeks) and body weight (> or = 1500 g) there is a good chance of survival when the BPD exceeds 7.5 cm. The analysis of our data denotes that tables from industrialized countries relating gestational age to sonographically measured BPD are not applicable for pregnancies in developing countries.

A species specific satellite DNA family of Drosophila subsilvestris appearing predominantly in B chromosomes.

This paper describes a species specific satellite DNA family (pSsP216) of Drosophila subsilvestris, a palearctic species of the D. obscura group. The pSsP216 family consists of tandemly arranged 216 bp repetitive units that are predominantly localized on B chromosomes. These chromosomes appear in variable numbers in the karyotype of this species. Some pSsP216 repeats can also be detected in the centromeric heterochromatin of the acrocentric A chromosomes. Two strains, one with and the other without B chromosomes, were investigated for sequence variability and for the location of this satellite DNA on the chromosomes. Among 16 clones of the 216 bp basic repeat unit an overall similarity of about 93% and no strain specific differences were found, indicating that the B chromosomes may have derived from the A chromosomes (probably the dots) by spontaneous amplification of the pSsP216 satellite DNA family.

Aspirin, acetaminophen and proton transport through phospholipid bilayers and mitochondrial membranes.

Mechanisms of proton transport were investigated in planar phospholipid bilayer membranes exposed to aspirin (acetylsalicylic acid), acetaminophen (4-acetamidophenol), benzoic acid and three aspirin metabolites (salicylic acid, gentisic acid and salicyluric acid). The objectives were to characterize the conductances and permeabilities of these weak acids in lipid bilayer membranes and then predict their effects on mitochondrial membranes. Of the compounds tested only aspirin, benzoate and salicylate caused significant increases in membrane conductance. The conductance was due mainly to proton current at low pH and to weak acid anion current at neutral pH. Analysis of the concentration and pH dependence suggests that these weak acids act as HA-2-type proton carriers when pH approximately pK and as lipid soluble anions at neutral pH. Salicylate is much more potent than aspirin and benzoate because salicylate contains an internal hydrogen bond which delocalizes the negative charge and increases the permeability of the anion. Model calculations for mitochondria suggest that salicylate causes net H+ uptake by a cyclic process of HA influx and A- efflux. This model can explain the salicylate-induced uncoupling and swelling observed in isolated mitochondria. Since ingested aspirin breaks down rapidly to form salicylate, these results may clarify the mechanisms of aspirin toxicity in humans. The results may also help to explain why the ingestion of aspirin but not acetaminophen is associated with Reye's syndrome, a disease characterized by impaired energy metabolism and mitochondrial swelling.

Maintenance of DQB1 polymorphisms in primates.

To understand the evolution of the class II major histocompatibility complex (MHC) DQB1 locus in primates, the second exons of seven DQB1 alleles from five non-human primate species were amplified by polymerase chain reaction. Comparisons of these and other primate sequences show that no between-species diversity is greater than within-species diversity, suggesting maintenance of DQB1 alleles through the history of Old-World primates. There is a preponderance of nonsynonymous nucleotide substitutions at antigen-binding-site codons; this pattern is in marked contrast to what is seen at the closely related, presumably nonfunctional DQB2 gene. The results support the hypothesis that DQB1 polymorphism is maintained by overdominant selection relating to antigen presentation.

[Severe ischemic hepatitis after taking cibenzoline]. / Ischémie hépatique grave après prise de cibenzoline.

The authors report the case of a 77 year old man suffering from chronic congestive heart failure, who presented a severe hepatic failure. Since 9 days the patient was treated by cibenzoline for serious ventricular arythmias. Hepatic failure was not due to drug hepatotoxicity but to an indirect effect of cibenzoline diminishing cardiac output. Arguments for ischaemic hepatitis and also two mechanisms of hepatic involvement in cardiac diseases are developed. In most cases association of two mechanisms, vascular stasis and low cardiac output is necessary to create hypoxic hepatitis.

[Evaluation of the treatment of aneurysmal meningeal hemorrhage with antifibrinolytic agents, calcium inhibitors and maintenance of effective blood volume]. / Bilan du traitement des hémorragies méningées anévrysmales par antifibrinolytique, inhibiteur calcique et maintien d'une volémie efficace.

To prevent and treat the ischemic complications due to the vasospasm, this report suggest the management of aneurysmal subarachnoid haemorrhage by the association of antifibrinolytics (tranexamic acid) to lower the risk of rebleeding, calcium channel blockers (nimodipine), and the keeping of an effective total blood volume (thanks to volume expansion and dopamine). From 88 patients aged from 4 to 73, two thirds were admitted at latest 48 h after the aneurysmal rupture Emergency surgery was carried out in the case of a compressive hematoma, early surgery (between the first and the third day) on the grades I, II and III of Hunt and Hess without any signs of angiographic vasospasms (40% of this series), delayed surgery for the others (27.5%), 10% didn't undergo any surgery. Only three patients (3.4%) presented rebleeding leading to death. The features of the whole series are: 51% recovered without any after effects, 22% had mild neurological deficiency, 10% had severe neurological deficiency and 17% died after their release from hospital. This protocol allowed a decrease in the ischemic complications due to the vasospasm and in the rate of rebleeding during the waiting interval when an angiographic or a clinical vasospasm allowed no surgery.

Salicylates and proton transport through lipid bilayer membranes: a model for salicylate-induced uncoupling and swelling in mitochondria.

Mechanisms of proton transport were investigated in phospholipid bilayer membranes exposed to salicylates and benzoates. Membranes were formed from diphytanoyl phosphatidylcholine in decane plus chlorodecane (50% vol/vol). Proton and anion conductances (GH and GA) were calculated from the total conductances and the H+ or A diffusion potentials produced by transmembrane H+ or A gradients. At low pH salicylate caused a GH which was proportional to the square of the total weak acid concentration, and GH was maximum when pH = pK. At neutral to alkaline pH salicylate caused a GA which was proportional to the first power of the salicylate concentration, and GA was independent of pH. Both GH and GA were inhibited by phloretin. The results suggest that salicylate acts as an HA2-type proton carrier at low pH and as a lipid-soluble anion at neutral pH. Salicylate has been implicated as a causal factor in Reye's syndrome, as well as in aspirin poisoning, and salicylate has been reported to increase the proton conductance of inner mitochondrial membranes. The present results suggest that in mitochondria salicylate increases passive proton uptake by a combination of HA influx (driven by the concentration gradient) and A efflux (driven by the voltage and concentration gradients). Model calculations suggest that over the range of therapeutic to toxic concentrations, salicylate causes net H+ influx sufficient to explain the reported "loose coupling," uncoupling and swelling of mitochondria. The relative ineffectiveness of aspirin and benzoate can be explained by their low A permeabilities, whereas the ineffectiveness of 2,6-dihydroxybenzoate can be explained by its low pK.

Evolution of the class II major histocompatibility complex alleles in higher primates.

We have shown that chimpanzees and gorillas have DRB alleles very similar to those of humans. The existence of similar DRB alleles in the different species of higher primates cannot be accounted for by convergent evolution of unrelated alleles that arose independently after the speciation. We therefore conclude that ancestral DRB alleles, that had existed before the speciation, were transmitted to the ancestors of humans, chimpanzees, and gorillas. This conclusion indicates that the diversification of MHC alleles does not start at the inception of a species, but rather proceeds beyond the lifespan of a species. A high degree of sequence similarity found between certain human and non-human primate DRB alleles shows that MHC alleles do not diversify rapidly. The bulk of the contemporary DRB polymorphism seems to have been generated by accumulation of random point mutations during long evolutionary periods preceding the divergence of humans, chimpanzees, and gorillas.

The major histocompatibility complex and human evolution.

Many alleles at the human major histocompatibility complex (HLA) loci diverged before the divergence of humans and great apes from a common ancestor. This fact puts a lower limit on the size of the bottleneck in human evolution: the genus Homo must have been founded by no less than ten and probably by more than 10,000 individuals.