Bioprospecting – why is it so unrewarding?

Some economic analyses have placed high values on the chemicaldiversity residing in threatened habitats[, Conservation Biology 6:128–130; , InBiodiversity and its Importance to Human Health, Columbia University Press, NewYork; , Journal of PoliticalEconomy 108: 173–206]. Consequently, bioprospecting (searching for newbiologically active chemicals in organisms) is considered by some to be a way offunding the preservation of biodiversity, especially in the less developedcountries. However, the large multinational pharmaceutical andagrochemical companies spend very little of their research effort onbioprospecting [, Phytochemistry55: 463–480]. Why is this? The answer lies in the fact that any chemical(whether a synthetic or a natural product) has a very low probability ofpossessing useful biological activity. The common belief that every naturalproduct has been selected by its producer such that only biologically activenatural products are made is not correct. Given that random collections ofsynthetic or natural products have a similar chance of containing a chemicalwith specific activity against any one target, and given that syntheticchemicals are nearly always much easier to synthesise on an industrial scale, itis predictable that major agrochemical and pharmaceutical companies will devoteonly a limited amount of their R &; D budget to bioprospecting. Although argued that scientificadvances will make bioprospecting more cost-effective in future, an alternativescenario is presented where current biotechnological developments will furthererode the value of bioprospecting. It is concluded that there should be noreliance on large-income streams being available from bioprospecting agreementsto help fund the preservation of biodiversity.     

Some like it hot,some not – Tropical and arctic mushrooms

Fungi are of pivotal importance for terrestrial ecosystems. They occur globally and show extremely high species diversities. In this review, we compiled information about the adaptability of pileate basidiomycetes by illustrating their habits in contrasting biomes, the arctic regions and tropical lowland rainforests. Mushrooms are faced with differing stress factors and levels in the two ecozones. They fight such challenges by using, by and large, similar physiological and morphological toolkits. They make them fit for extreme environmental conditions, by expressing traits according to biome characteristics. This way, fungal assemblages are formed and pheno- and genotypic plasticity is capitalised. Still, many questions remain open and need further clarification, such as trade-offs between thermal protection and predator defence, prevailing dispersal modes in the main ecozones, interactions with animals and the mechanisms that create genetic plasticity.     

Do some corals like it hot?

Global increases in sea temperatures threaten coral reef resilience because thermal stress can cause corals to bleach; that is, to lose their photosynthetic microalgal symbionts. Recent evidence suggests that some corals associate with genotypes of microalgae that resist future thermal stress, however, these genotypes might provide less energy for growth when thermal stresses are curtailed. Coral reef resilience depends on whether phenotypic and genotypic changes in host-symbiont associations can match projected increases in the frequency and severity of thermal stress, as well as on our ability to ameliorate continuing human impacts.     

The nested structure of marine cleaning symbiosis: is it like flowers and bees?

In a given area, plant-animal mutualistic interactions form complex networks that often display nestedness, a particular type of asymmetry in interactions. Simple ecological and evolutionary factors have been hypothesized to lead to nested networks. Therefore, nestedness is expected to occur in other types of mutualisms as well. We tested the above prediction with the network structure of interactions in cleaning symbiosis at three reef assemblages. In this type of interaction, shrimps and fishes forage on ectoparasites and injured tissues from the body surface of fish species. Cleaning networks show strong patterns of nestedness. In fact, after controlling for species richness, cleaning networks are even more nested than plant-animal mutualisms. Our results support the notion that mutualisms evolve to a predictable community-level structure, be it in terrestrial or marine communities.     

Doctor in the lab: what is it like for a doctor to work with scientists?

As clinical academic medical departments strive to improve the quality of their research, clinicians and scientists are forced into closer liaison. In many cases, clinical departments now have research laboratories directed by "basic scientists" but often staffed, in part at least, by doctors. To someone who has not worked in one, these laboratories may seem uncompromising and forbidding work environments. This article presents a "case report" written from the viewpoints of the doctor, the scientist, and the professor.     

CFTR: what's it like inside the pore?

The Cystic Fibrosis Conductance Regulator (CFTR) functions as a cAMP-activated, anion-selective channel, but the structural basis for anion permeation is not well understood. Here we summarize recent studies aimed at understanding how anions move through the CFTR channel, and the nature of the environment anions experience inside the pore. From these studies it is apparent that anion permeability selectivity and anion binding selectivity of the pore are consistent with a model based on a "dielectric tunnel." The selectivity pattern for halides and pseudohalides can be predicted if it is assumed that permeant anions partition between bulk water and a polarizable space that is characterized by an effective dielectric constant of about 19. Covalent labeling of engineered cysteines and pH titration of engineered cysteines and histidines lead to the conclusion that the CFTR anion conduction path includes a positively charged outer vestibule. A residue in transmembrane segment 6 (TM6) (R334) appears to reside in the outer vestibule of the CFTR pore where it creates a positive electrostatic potential that enhances anion conduction.     

Aerobic dive limit. What is it and is it always used appropriately?

The original definition of aerobic dive limit (ADL) was the dive duration after which there is an increase in post-dive concentration of lactate in the blood of Weddell seals freely diving in the field. The only other species in which such measurements have been made is the emperor penguin. For all other species, aerobic dive limit has been calculated (cADL) by dividing usable oxygen stores with an estimation of the rate of oxygen consumption during diving. Unfortunately, cADL is often referred to as the aerobic dive limit, implying that it is equivalent to that determined from the measurement of post-dive blood lactate concentration. However, this is not so, as at cADL all of the usable oxygen would have been consumed, whereas Weddell seals and emperor penguins can dive for at least 2-3 times longer than their ADL. Thus, at ADL, there is still some usable oxygen remaining in the stores. It is suggested that to avoid continued confusion between these two terms, the former is called diving lactate threshold (DLT), as it is somewhat analogous to the lactate threshold in exercising terrestrial vertebrates. Possible explanations of how some species routinely dive beyond their cADL are also discussed.     

Vaccination against shigellosis: is it the path that is difficult or is it the difficult that is the path?

Following several decades of research, there is not yet a convincing vaccine against shigellosis. It is still difficult, in spite of the breadth of strategies (i.e. live attenuated oral, killed oral, subunit parenteral) to select an optimal option. Two approaches are clearly emerging: (i) live attenuated deletion mutants based on rational selection of genes that are key in the pathogenic process, and (ii) conjugated detoxified polysaccharide parenteral vaccines, or more recently conjugated synthetic carbohydrates. Some of these approaches have already undergone phase I and II clinical trials with promising results, but important issues have also emerged, particularly the discrepancy between colonization and immunogenic potential of live attenuated vaccine candidates depending upon the population concerned (i.e. non endemic vs. endemic areas). Efforts are needed to definitely establish the proof of concept of these approaches, and thus the need for clinical trials which should also soon explore the possibility to associate different serotypes, in response to serotype specific protection against shigellosis. More basic research is also required to improve what we can still consider as first-generation vaccines, and to explore possible new paradigms including the search for cross-protective antigens.