Similarities and Differences between Induced Organ Regeneration in Adults and Early Fetal Regeneration by Professor IV Yannas
The interest of this article to the public centres on the discovery that non-functioning organs can be regenerated in adults by use of scaffolds alone (or scaffolds seeded with the subject's own epithelial cells). This development may obviate the use of organ transplants in the future. Also note that, in this treatment, stem cells are not required to be used by the investigator. It has been widely thought previously that only the early mammalian foetus can regenerate an organ spontaneously following severe injury to that organ. It is now clear that the adult is capable of a regenerative potential that was previously considered to have become lost just before birth. This discovery suggests the possibility that adults (you and I) have managed to retain their early foetal potential to regenerate organs; and that this dormant potential can be reactivated provided that medical researchers can identify the appropriate agents (scaffolds, small molecules, etc.) that awaken the early foetal response to injury. The emerging field of Regenerative Medicine is based on this new treatment that leads to organ regeneration and provides an outlook toward increased longevity.
Contact: Professor IV Yannas, Mechanical Engineering, Massachusetts Institute of Technology, USA
Diving behaviour of whale sharks in relation to a predictable food pulse by Dr RT Graham, Professor CM Roberts and Dr JCR Smart
We present diving data for four whale sharks in relation to a predictable food pulse (reef fish spawn) and an analysis of the longest continuous fine-resolution diving record for a planktivorous shark. Fine-resolution pressure data from a recovered pop-up archival satellite tag deployed for 206 days on a whale shark were analysed using the fast Fourier Transform method for frequency domain analysis of time-series. The results demonstrated that a free-ranging whale shark displays ultradian, diel and circa-lunar rhythmicity of diving behaviour. Whale sharks dive to over 979.5 m and can tolerate a temperature range of 26.4 8C. The whale sharks made primarily diurnal deep dives and remained in relatively shallow waters at night. Whale shark diving patterns are influenced by a seasonally predictable food source, with shallower dives made during fish spawning periods.
Contact: Dr. RT Graham, Marine Program - International Conservation, Wildlife Conservation Society, PO Box 37, PUNTA GORDA, Belize
Proceedings of the Royal Society B: Biological Sciences
Females use self-referent cues to avoid mating with previous mates by Professor SK Sakaluk, Ms TM Ivy and Ms. CBW Weddle (rspb.2005.3222)
Female animals often mate with many different males, behaviour that has long puzzled evolutionary biologists. However, recent studies have revealed that by mating with more than one male, females may obtain particularly "good" genes that enhance the prospects of their offspring's health and survival. That being the case, we might expect females to favour novel mating partners over previous mates, and indeed studies of several unrelated species have shown a clear female preference for novel males. But how do females distinguish between novel males and previous mating partners? The answer, according to a recent study of crickets, is that females do so by "tagging" males with their own odours during mating. When a female encounters a former mating partner later on, she need only compare her own scent with that of the male. If she finds that the male has been imbued with her own chemical signature, she can avoid mating with that male in favour of a novel mating partner. This mechanism, formally known as the "armpit" effect, requires no special cognitive ability (i.e., learning) because the female's own smell is always available for direct comparison. Hence, this simple form of self referencing could be a widespread mechanism by which females maximize the diversity of their mating partners.
Contact: Professor SK Sakaluk, Biological Sciences, Illinois State University, 4120 Biological Sciences, NORMAL, IL, 61790-4120, United States
Interactions between intrinsic and extrinsic mechanisms in a cyclic species: testosterone increases parasite infection in red grouse by Dr LJ Seivwright, Dr SM Redpath, Dr F Mougeot, Ms FM Leckie and Professor P Hudson (rspb.2005.3233)
Previous studies have considered that population cycles in red grouse are driven by dynamical changes in either aggressiveness or the parasite Trichostrongylus tenuis. We experimentally tested for an interaction between these mechanisms in free-living male grouse. A total of 123 grouse were caught in autumn, treated to remove parasites, given either testosterone or control implants and one month later re-infected with a standard dose of parasites. One year later males with increased testosterone levels had greater parasite intensities than controls. This interaction within individuals has the potential to affect the unstable population dynamics of red grouse.
Contact: Dr LJ Seivwright, Biodiversity & Population Processes, CEH Banchory
Rodent malaria parasites Plasmodium chabaudi and P. vinckei do not increase their rates of gametocytogenesis in response to mosquito probing by Dr D Shutler, Dr SE Reece, Dr A Mullie, Dr PF Billingsley and Professor AF Read (rspb.2005.3232)
The organisms that parasites live in are called hosts, and parasites have some remarkable strategies to move from host to host. Understanding these strategies may help us stop the spread of some parasitic diseases. We were interested in whether malaria inside mouse hosts would recognise that mosquito feeding signalled transmission opportunities. However, we found no change in malaria reproductive rate when mouse hosts were fed upon by mosquitoes. Our results are surprising because there is substantial evidence that malaria and many other parasites facultatively and adaptively respond to a variety of other environmental influences.
Contact: Dr D Shutler, Acadia University, 24 University Avenue, WOLFVILLE, NOVA SCOTIA, B4P 2R6, Canada
Cattle domestication in the Near East was followed by hybridization with aurochs bulls in Europe by Dr A Gotherstrom, MSc C Anderung, Dr L Hellborg, Dr R Elburg, Dr C Smith, Dr DG Bradley and Professor H Ellegren (rspb.2005.3243)
Cattle domestication was an important part of the cultural transition from a hunter/gatherer lifestyle to a farming society, and was a prerequisite to the rise of civilization. Cattle were domesticated from aurochsen about 10.000 years ago and, as for most other domestic animal species, domestication was probably limited to a few regions including the Near East and India. From these regions, domestic cattle are thought to have spread by migrating humans, e.g. by migration of the first farmers from southwest Asia into Europe. However, our study focusing on the genetic legacy of the male-specific Y chromosome of cattle tells a different tale. Surprisingly, we find that modern domestic cattle breeds of northern Europe are genetically more similar to ancient specimen of European aurochsen than to modern breeds from southern Europe. This indicates that early European farmers used local wild aurochsen in breeding. For instance, crosses may have been deliberately arranged to improve the breeding stock. Alternatively, during times without close cattle control, the possibility of unintentional mating between aurochsen and cattle may have been difficult to avoid. These results challenge the widely appreciated model that domestication is a rare and difficult process that, once it has occurred, generally spreads by the animals themselves rather than by the continued utilization of additional wild ancestors in new areas.
Contact: Professor H Ellegren, Dept of Evolutionary Biology, Uppsala University, Norbyvagen 18D, UPPSALA, SE-752 36, Sweden
Genetic analysis reveals demographic fragmentation of grizzly bears yielding vulnerably small populations by Dr MF Proctor, Dr BN McLellan, Dr C Strobeck and Dr. RMR Barclay (rspb.2005.3246)
Large carnivores have a difficult time co-existing with people throughout the world. The persistence of several remnant grizzly bear populations in the continental USA depends on their being naturally connected to bears in Canada. Here, we report on a study of grizzly bear population fragmentation across the Canada – USA international border. Using genetic samples from hundreds of wild grizzly bears we determined that a Canadian transportation and settlement corridor just north of the border is fragmenting these international grizzly bear populations. Two of the resulting populations are small enough to warrant special conservation consideration as a result of this fragmentation.
Contact: Dr MF Proctor, Biological Sciences, University of Alberta, PO Box 920, KASLO, BRITISH COLUMBIA, V0G 1M0, Canada
Molecular evolution of the sheep prion protein gene by Dr J Slate (rspb.2005.3259)
This paper describes a molecular evolution analysis of the PRNP in sheep, the gene associated with resistance to the prion disease scrapie. PRNP appears to show the signature of balancing selection in sheep. This is an important discovery for several reasons. First, the signature of natural selection has only rarely been detected in the genomes' of domestic livestock. Second, it provides rare evidence that disease can maintain host genetic variation. Third, these data suggest that scrapie eradication programs: (i) are disrupting the natural process of balancing selection, (ii) will deplete PRNP variation, thereby creating genetically uniform flocks and (iii) may even fail to achieve their primary objective - scrapie eradication. In summary, this timely paper will appeal to scientists, the broader public and even the script-writers of The Archers!
Contact: Dr J Slate, Animal & Plant Sciences, University of Sheffield, SHEFFIELD, S10 2TN
Adaptive male effects on female ageing in bean weevils by Dr A Maklakov, Ms N Kremer and Professor G Arnqvist (rspb.2005.3240)
The phenomenon of ageing has always absorbed both scientists and general public, yet many factors that contribute to ageing remain unveiled. Recent evolutionary theory advocates that different sexes may evolve to affect ageing in each other in a way that is beneficial for members of one sex. Here we use experimental evolution to show that males evolve to slow down ageing in their mates when increased female lifespan is beneficial to males. Thus, adaptive evolution in males causes higher or lower rates of ageing in females, according to males' evolutionary interests, which has far-reaching ramifications for our understanding of ageing.
Contact: Dr AA Maklakov, Department of Ecology and Evolution, Uppsala University, Evolutionary Biology Centre, UPPSALA, SE-752 36, Sweden
Conflict between parasites with different transmission strategies infecting an amphipod host by Dr ER Haine, Mrs K Boucansaud and Dr T Rigaud (rspb.2005.3244)
Simultaneous infections by different parasites are common in nature, and competition between them may occur if one parasite is more harmful to its host than another. We investigated competition between two parasites: a micro-parasite that is transmitted maternally via the eggs, has low virulence and relies on host survival, and a macro-parasite that relies on host death for its transmission. We found that the former can protect its host from the lethal effects of the latter. These results are important because maternally-transmitted parasites are often undetected but may play a major role in protecting their hosts from more virulent parasites.
Contact: Dr T Rigaud, UMR 5561 - Equipe Ecologie Evolutive, Universite de Bourgogne, 6 boulevard Gabriel, DIJON, 21000, France
Journal
Journal of The Royal Society Interface