Today, I’m venturing into the world of Arabidopsis, a plant I usually leave to the geneticists. More specifically, into it and its relatives’ evolutionary past. DNA sequences can be used to estimate how long ago species separated. Once they separate, they stop interbreeding, and their DNA sequences start to evolve separately. So the more differences [...]... Read more »
Beilstein, M., Nagalingum, N., Clements, M., Manchester, S., & Mathews, S. (2010) Dated molecular phylogenies indicate a Miocene origin for Arabidopsis thaliana. Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.0909766107
Chuanwu Xi and Jianfeng Wu (University of Michigan, United States) have found that pathogenic bacteria form dense protective aggregates (biofilms) in response to a physiological warning of their presence. This news feature was written on October 17, 2010.... Read more »
Xi, C., & Wu, J. (2010) dATP/ATP, a Multifunctional Nucleotide, Stimulates Bacterial Cell Lysis, Extracellular DNA Release and Biofilm Development. PLoS ONE, 5(10). DOI: 10.1371/journal.pone.0013355
In clinical science, if you ever hear of something with an unusual name, chances are it has something unique about it. Consider an appendectomy--a boring name for the removal of the appendix, or cholecystectomy--a snooze of a term to describe the removal of the gallbladder; but both names serve a purpose in that they describe the procedure. Now consider the Sugar Baker procedure. Based on name alone, you don't have much to go by, unless you incorrectly suspect that it has something to do with confectionery. In talking with someone, they mentioned the Sugar Baker procedure, and it piqued my interest to the point that I wanted to know more about it. What did it entail? How did it get its name? Why did one do it? Thus, I went to the handy-dandy tool I often use--Google Scholar. I found some helpful articles, but nothing of particular interest. After resigning to the fact that I needed to do a more intensive search, I found a useful article: the treatment of peritoneal mesothelioma using the Sugar Baker procedure. Along with a type of advanced stage colon cancer, these two cancers are the primary indications for the Sugar Baker procedure.Despite scouring sources for information on peritoneal mesothelioma, I found little to describe this rare cancer's pathogenesis. We have long associated asbestos as the primary cause of mesothelioma, but this applies when it develops in the lungs. To date nobody has developed a concrete pathway for the development of mesothelioma in the peritoneum--the lining of the abdomen. At least a third of patients with peritoneal mesothelioma have no history of asbestos exposure. Without an understanding of how asbestos could get into the peritoneum exclusively, and a detailed social history of all patients to rule out asbestos exposure, the link between asbestos and peritoneal mesothelioma remains merely a working hypothesis. Nonetheless, as with its pulmonary counterpart, it has a grim outcome. Being rare doesn't help, since most money goes into the research of the more common malignancies. As with all cancers, the only potential cure revolves around the possibility of the removal of all cancer cells. To successfully rid the body of cancer, you must either completely remove or kill all cancer cells; typically done through surgery, radiology, or chemotherapy. Each of these methods has its limitations; not all cancers respond to chemotherapy, some parts of the body can't take radiation, and sometimes surgery just isn't feasible. In the case of peritoneal mesothelioma, surgery is the treatment of choice--the Sugar Baker procedure; only recently did surgeons come to recognize its efficacy.Named after the physician who first employed it, the Sugar Baker procedure takes a lot of time and will have a heavy impact on the patient's life. Basically, you cut open the abdomen, and remove all visible cancer. Some things cannot be removed, but things that can come out include the colon, the spleen, the gallbladder, the omentum, and the peritoneum...as much as possible in so far as it is possible to remove the cancer. After surgical removal of as much cancer as possible with regard to what must stay, the abdomen is then filled with heated chemotherapeutics, such as cisplatin or doxyrubicin; again, in the hopes of killing any remaining cancer. A 2010 study investigated the use of the Sugar Baker procedure for periteonal mesothelioma. In looking at 20 patients, it found that in the years following the procedure, only six of the patients survived without disease recurrence. Just over 25%, with further follow-up necessary to track the possibility of future cancer development. I have heard people debate the use of the Sugar Baker procedure, given its possible outcomes. After all, living without a spleen and a colon does not come without consequence. But then again, it gives the potential of life to someone otherwise destined for death. Tudor EC, Chua TC, Liauw W, & Morris DL (2010). Risk factors and clinicopathological study of prognostic factors in the peritoneal mesothelioma. The American surgeon, 76 (4), 400-5 PMID: 20420251... Read more »
Tudor EC, Chua TC, Liauw W, & Morris DL. (2010) Risk factors and clinicopathological study of prognostic factors in the peritoneal mesothelioma. The American surgeon, 76(4), 400-5. PMID: 20420251
Thorough information about the red panda (habitat, diet, mating habits etc). Photos and images included... Read more »
Sato JJ, Wolsan M, Minami S, Hosoda T, Sinaga MH, Hiyama K, Yamaguchi Y, & Suzuki H. (2009) Deciphering and dating the red panda's ancestry and early adaptive radiation of Musteloidea. Molecular phylogenetics and evolution, 53(3), 907-22. PMID: 19699810
While for most of us, it tends to be a given that the culprit behind the scourge known as the Black Death was the bubonic plague, a number of historians weren’t so sure. The reports from the time talked about the kinds of symptoms we’d expect from a bizarre hybrid of bubonic and hemorrhagic plagues, [...]... Read more »
Haensch, S., Bianucci, R., Signoli, M., Rajerison, M., Schultz, M., Kacki, S., Vermunt, M., Weston, D., Hurst, D., Achtman, M.... (2010) Distinct Clones of Yersinia pestis Caused the Black Death. PLoS Pathogens, 6(10). DOI: 10.1371/journal.ppat.1001134
An international team has confirmed Yersinia pestis biomolecules in Black Death era* ‘plague pits’ (Haensch et al., 2010). Ancient DNA (aDNA) specific for Yersinia pestis and the Yersinial F1 antigen were discovered in skeletons from recognized plague pits in the Netherlands, England, and France. German and Italian skeletons tested positive for Y. pestis [...]... Read more »
Haensch, S., Bianucci, R., Signoli, M., Rajerison, M., Schultz, M., Kacki, S., Vermunt, M., Weston, D., Hurst, D., Achtman, M., Carniel, E., and Bramanti, B. (2010) Distinct clones of Yersinia pestis caused the Black Death. PLoS Pathogens, 6(10). info:/
Pusch CM, Rahalison L, Blin N, Nicholson GJ, & Czarnetzki A. (2004) Yersinial F1 antigen and the cause of Black Death. The Lancet infectious diseases, 4(8), 484-5. PMID: 15288817
Aqua Bounty Technologies, Inc. has recently applied for deregulation of AquAdvantage salmon — salmon that have been genetically engineered to grow faster than wild-type salmon. These salmon have the potential benefit of providing high-quality animal protein without putting additional pressure on declining wild fish stocks. However, these salmon present some potential risks that warrant examination. First, effects on the health and welfare of the animals must be determined. Second, if genetically engineered salmon Continue reading...... Read more »
Devlin, R., Yesaki, T., Donaldson, E., Du, S., & Hew, C. (1995) Production of germline transgenic Pacific salmonids with dramatically increased growth performance. Canadian Journal of Fisheries and Aquatic Sciences, 52(7), 1376-1384. DOI: 10.1139/f95-133
Yaskowiak ES, Shears MA, Agarwal-Mawal A, & Fletcher GL. (2006) Characterization and multi-generational stability of the growth hormone transgene (EO-1a) responsible for enhanced growth rates in Atlantic Salmon. Transgenic research, 15(4), 465-80. PMID: 16906447
Butler TM, & Fletcher GL. (2009) Promoter analysis of a growth hormone transgene in Atlantic salmon. Theriogenology, 72(1), 62-71. PMID: 19324402
Devlin, R. (2004) Growth, viability and genetic characteristics of GH transgenic coho salmon strains. Aquaculture, 236(1-4), 607-632. DOI: 10.1016/j.aquaculture.2004.02.026
Sundström LF, Lõhmus M, Tymchuk WE, & Devlin RH. (2007) Gene-environment interactions influence ecological consequences of transgenic animals. Proceedings of the National Academy of Sciences of the United States of America, 104(10), 3889-94. PMID: 17360448
Hu W, & Zhu Z. (2010) Integration mechanisms of transgenes and population fitness of GH transgenic fish. Science China. Life sciences, 53(4), 401-8. PMID: 20596905
Witten, P., Gil-Martens, L., Huysseune, A., Takle, H., & Hjelde, K. (2009) Towards a classification and an understanding of developmental relationships of vertebral body malformations in Atlantic salmon (Salmo salar L.). Aquaculture, 295(1-2), 6-14. DOI: 10.1016/j.aquaculture.2009.06.037
Piferrer, F., Beaumont, A., Falguière, J., Flajšhans, M., Haffray, P., & Colombo, L. (2009) Polyploid fish and shellfish: Production, biology and applications to aquaculture for performance improvement and genetic containment. Aquaculture, 293(3-4), 125-156. DOI: 10.1016/j.aquaculture.2009.04.036
Ching B, Jamieson S, Heath JW, Heath DD, & Hubberstey A. (2010) Transcriptional differences between triploid and diploid Chinook salmon (Oncorhynchus tshawytscha) during live Vibrio anguillarum challenge. Heredity, 104(2), 224-34. PMID: 19707232
Nakamura R, Satoh R, Nakajima Y, Kawasaki N, Yamaguchi T, Sawada J, Nagoya H, & Teshima R. (2009) Comparative study of GH-transgenic and non-transgenic amago salmon (Oncorhynchus masou ishikawae) allergenicity and proteomic analysis of amago salmon allergens. Regulatory toxicology and pharmacology : RTP, 55(3), 300-8. PMID: 19679156
Vicini J, Etherton T, Kris-Etherton P, Ballam J, Denham S, Staub R, Goldstein D, Cady R, McGrath M, & Lucy M. (2008) Survey of retail milk composition as affected by label claims regarding farm-management practices. Journal of the American Dietetic Association, 108(7), 1198-203. PMID: 18589029
Juniper, D., Browne, E., Bryant, M., & Beever, D. (2007) Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers given maize silages harvested at three stages of maturity. Animal Science, 82(01). DOI: 10.1079/ASC200513
Giovannucci E, Pollak M, Liu Y, Platz EA, Majeed N, Rimm EB, & Willett WC. (2003) Nutritional predictors of insulin-like growth factor I and their relationships to cancer in men. Cancer epidemiology, 12(2), 84-9. PMID: 12582016
Upton Z, Yandell CA, Degger BG, Chan SJ, Moriyama S, Francis GL, & Ballard FJ. (1998) Evolution of insulin-like growth factor-I (IGF-I) action: in vitro characterization of vertebrate IGF-I proteins. Comparative biochemistry and physiology. Part B, Biochemistry , 121(1), 35-41. PMID: 9972282
Mero A, Kähkönen J, Nykänen T, Parviainen T, Jokinen I, Takala T, Nikula T, Rasi S, & Leppäluoto J. (2002) IGF-I, IgA, and IgG responses to bovine colostrum supplementation during training. Journal of applied physiology (Bethesda, Md. : 1985), 93(2), 732-9. PMID: 12133885
Fleming, I. (1996) Reproductive strategies of Atlantic salmon: ecology and evolution. Reviews in Fish Biology and Fisheries, 6(4), 379-416. DOI: 10.1007/BF00164323
Fraser DJ, Houde AL, Debes PV, O'Reilly P, Eddington JD, & Hutchings JA. (2010) Consequences of farmed-wild hybridization across divergent wild populations and multiple traits in salmon. Ecological applications : a publication of the Ecological Society of America, 20(4), 935-53. PMID: 20597281
(This was first published at The Urban Times) In a study published in the online journal PLoS ONE yesterday, researchers show evidence for cannibalistic behaviour in Tyrannosaurus rex. Indeed, the king of the dinosaurs not only fed on other dinos, but also on fellow T. rex, say the researchers after identifying bite marks on giants’ [...]... Read more »
There's been a whole lot of interesting stuff coming out this week related the Conference of the Parties (COP 10) for the Convention on Biological Diversity (CBD) going on in Nagoya, Japan right now. CBD's goal was to slow the loss of biodiversity loss by 2010, but that goal was not achieved, and nations are hammering out how to revive the CBD with new goals for 2020.
At a prepatory meeting in May, governments agreed on 20 more specific draft targets, which aim to be “SMART” - specific, measurable, ambitious, realistic, and time-bound. A piece in this week's Science, by some of the world's biodiversity experts raised some issues that the current draft targets fail to address. Here are my thoughts on a couple:
Functional diversity is a new advance in recent years in how we quantify biodiversity science. It refers the mix of traits and functions present in an ecosystem. For an ecosystem to function properly it needs the right mix of species that perform different tasks, like pollinators, decomposers, and soil stabilizers. This measure of diversity is potentially much more important than a simple count of species. The authors argue that this concept should be explicitly integrated into the targets for 2020. The one draft target that awknowledges that biodiversity exists at different scales is #13, which says:
By 2020, the loss of genetic diversity of cultivated plants and domestic farm animals in agricultural ecosystems and of wild relatives is halted and strategies have been developed and implemented for safeguarding the genetic diversity of other priority socio-economically valuable species as well as selected wild species of plants and animals.
Genetic diversity is an important component of functional diversity, but I think this statement reflects an underappreciation of the role genetic diversity plays in ecosystems. I think it comes out of a notion that genetic diversity is neccessary for survivial of species, and thus we should ensure that our crops and a few cherished or very important species have enough genetic diversity to persist. However, genetic diversity itself often underlies the functions that species have in ecosystems. I think this should refer to something like "the genetic diversity across species in ecosystems."
The other issue the authors raise that I'd like to comment on is uncertainty. They write:
How much diversity it is critical to maintain depends on the range of environmental conditions expected. The greater the expected variation in environmental conditions, the greater the required diversity within groups providing particular functions. Ecological functioning may change as environmental conditions change. Targets for diversity within functional groups of species should adjust with changes in expectations about the state of the environment.
It's not that ecological functioning "may" change - it WILL change. We live in a world changing faster than anytime in history or what we know of pre-history. To me, this is the biggest thing missing from these goals - an awknowledgement that we no longer have a "baseline scenario" to return to, and no matter what we do, the world and its biodiversity will look very different in 2020 or beyond.
Perrings, C., Naeem, S., Ahrestani, F., Bunker, D., Burkill, P., Canziani, G., Elmqvist, T., Ferrati, R., Fuhrman, J., Jaksic, F., Kawabata, Z., Kinzig, A., Mace, G., Milano, F., Mooney, H., Prieur-Richard, A., Tschirhart, J., & Weisser, W. (2010). Ecosystem Services for 2020 Science, 330 (6002), 323-324 DOI: 10.1126/science.1196431... Read more »
Could be rough times ahead if you are the big fish atop the food chain in your river. A sophisticated new analysis finds that droughts and floods reshuffle river food webs in dramatically different ways – offering a potential preview of how climate change, dams and other forces may affect top predators such as large […] Read More »... Read more »
Sabo, J., Finlay, J., Kennedy, T., & Post, D. (2010) The Role of Discharge Variation in Scaling of Drainage Area and Food Chain Length in Rivers. Science. DOI: 10.1126/science.1196005
In my little bid to participate in Change.org’s Blog Action Day 2010 – Water, I’ve re-hashed a post from 2008 on ‘water neutrality’. This will also benefit my recently joined readers, and re-invigorate a concept I don’t think has received nearly enough attention globally (or even in parched Australia where I live). So here we [...]... Read more »
Nel, D., Marais, C., & Blignaut, J. (2009) Water neutrality: A first quantitative framework for investing in water in South Africa. Conservation Letters, 2(1), 12-19. DOI: 10.1111/j.1755-263X.2008.00035.x
Reboxetine is an antidepressant. Except it's not, because it doesn't treat depression.This is the conclusion of a much-publicized article just out in the BMJ: Reboxetine for acute treatment of major depression: systematic review and meta-analysis of published and unpublished placebo and SSRI controlled trials.Reboxetine was introduced to some fanfare, because its mechanism of action is unique - it's a selective norepinephrine reuptake inhibitor (NRI), which has no effect on serotonin, unlike Prozac and other newer antidepressants. Several older tricyclic antidepressants were NRIs, but they weren't selective because they also blocked a shed-load of receptors.So in theory reboxetine treats depression while avoiding the side effects of other drugs, but last year, Cipriani et al in a headline-grabbing meta-analysis concluded that in fact it's the exact opposite: reboxetine was the least effective new antidepressant, and was also one of the worst in terms of side effects. Oh dear.And that was only based on the published data. It turns out that Pfizer, the manufacturers of reboxetine, had chosen to not publish the results of most of their clinical trials of the drug, because the data showed that it was crap.The new BMJ paper includes these unpublished results - it took an inordinate amount of time and pressure to make Pfizer agree to share them, but they eventually did - and we learn that reboxetine is:no more effective than a placebo at treating depression.less effective than SSRIs, which incidentally are better than placebo in this dataset (a bit).worse tolerated than most SSRIs, and much worse tolerated than placebo.The one faint glimmer of hope that it's not a complete dud was that it did seem to work better than placebo in depressed inpatients. However, this could well have been a fluke, because the numbers involved were tiny: there was one trial showing a humongous benefit in inpatients, but it only had a total of 52 people.)Claims that reboxetine is dangerous are a bit far-fetched - it may be, but there was no evidence for that in these data. It caused nasty and annoying side-effects, but that's not the same thing, because if you don't like side-effects, you could just stop taking it (which is what many people in these trials did).Anyway, what are the lessons of this sorry tale, beyond reboxetine being rubbish? The main one is: we have to start forcing drug companies and other researchers to publish the results of clinical trials, whatever the results are. I've discussed this previously and suggested one possible way of doing that.The situation regarding publication bias is far better than it was 10 years ago, thanks to initiatives such as clinicaltrials.gov; almost all of the reboxetine trials were completed before the year 2000; if they were run today, it would have been much harder to hide them, but still not impossible, especially in Europe. We need to make it impossible, everywhere, now.The other implication is, ironically, good news for antidepressants - well, except reboxetine. The existence of reboxetine, a drug which has lots of side effects, but doesn't work, is evidence against the theory (put forward by Joanna Moncrieff, Irving Kirsch and others) that even the antidepressants that do seem to work, only work because of active placebo effects driven by their side effects.So given that reboxetine had more side effects than SSRIs, it ought to have worked better, but actually it worked worse. This is by no means the nail in the coffin of the active placebo hypothesis but it is, to my mind, quite convincing.Link: This study also blogged by Good, Bad and Bogus.Eyding, D., Lelgemann, M., Grouven, U., Harter, M., Kromp, M., Kaiser, T., Kerekes, M., Gerken, M., & Wieseler, B. (2010). Reboxetine for acute treatment of major depression: systematic review and meta-analysis of published and unpublished placebo and selective serotonin reuptake inhibitor controlled trials BMJ, 341 (oct12 1) DOI: 10.1136/bmj.c4737... Read more »
Eyding, D., Lelgemann, M., Grouven, U., Harter, M., Kromp, M., Kaiser, T., Kerekes, M., Gerken, M., & Wieseler, B. (2010) Reboxetine for acute treatment of major depression: systematic review and meta-analysis of published and unpublished placebo and selective serotonin reuptake inhibitor controlled trials. BMJ, 341(oct12 1). DOI: 10.1136/bmj.c4737
This Friday we are continuing coverage of the most recent IgNobel prizes, those awesome prizes given to celebrate the truly odd, yet wonderful findings in scientific research. Sci LOVES these prizes. In fact, someday I want to be invited, so I can LIVE BLOG these prizes. Interview the winners! Have hilarious conversations! YES! You should [...]... Read more »
At the 2009 meeting of the American Geophysical Union, renowned climate scientist Richard Alley (Penn State) gave a keynote address, The Biggest Control Knob: Carbon dioxide in Earth’s Climate History, in which he used a variety of paleoclimatological proxy data to show how CO2 changes over much of Earth history have exerted a strong influence [...]... Read more »
Lacis, A., Schmidt, G., Rind, D., & Ruedy, R. (2010) Atmospheric CO2: Principal Control Knob Governing Earth's Temperature. Science, 330(6002), 356-359. DOI: 10.1126/science.1190653
This time of year, the shrill 'see,see,see' contact calls of Long-tailed tit flocks, coming from all directions from the tree canopy. These fluffy, tiny birds have a fascinating breeding system - facultative co-operative breeding - by which individuals may help rear up offspring of others depending of the circumstances. Their breeding season is rather short, and they are only able to rear a single brood per season. In the spring, all individuals pair up and attempt breeding, if breeding fails early enough - mostly due to predation - , they attempt nesting again.A predated nest of long-tailed tit on the 25th of April this year, the intact nest is a ball with the outside made of a delicately shell of pieces of lichen attached with spider webs, the inside is a down and feather filling. It can take the pair up to three weeks to put together.In contrast, if a brood is lost late in the season, individuals may turn to help other nest owners raise their brood, bringing food for their offspring, and actually increasing the fledging rate. Who do long-tailed tits help? The theory of kin-selection predicts that individuals should help their relatives for cooperative breeding to persist. Do long-tailed tits do this? How good are they discriminating their kin? Is the amount of help correlated with the degree of kinship? Prof. Ben Hatchwell, from the University of Sheffield, has been studying a population of long-tailed tits for over 14 years, and his research has provided wonderfully detailed insights on the reproductive behaviour of the long-tailed tit. Apparently long-tailed tits are able to recognize their kin through their contact calls. In a new study by Prof. Hatchwell's group, kin relationships between most individuals in a valley near Sheffield (U.K.) were assessed using pedigrees and genetic markers. Then they followed the nesting attempts - on real, amazingly cryptic nests, not in nest boxes! - and estimated provisioning rates by the different carers. This way they were able to document the relationships between helpers and the individuals they helped.The first interesting result, is that social ties are very good predictors of paternity in this species, there were no instances of cukoldry. Pairs were monogamous for each breeding season. This meant that pedrigree data was a very good predictor of genetic relationships. In many other cooperative breeders helpers often provision their siblings - that is, they are previous years offspring that delay they reproduction to help their parents raise another brood. In the case of the long-tailed tit, helping another nest is dependent on an own nesting failure, and there is a lot of diversity. Individuals can help their offspring, one or both parents, aunts and even a case of an individual helping a grandparent!. Most of the cases, however, involved individuals helping their siblings rear their nieces and nephews. This is possibly related to the high 'divorce' rates in long-tailed tits. Pairs are monogamous during a particular breeding season, but mortality is high (50% from one season to the next) and individuals often switch partners, therefore, the chances of a individual helping their parents is reduced. Also, siblings often disperse together to new territories so there is more opportunities to help a sibling than any other relative. In conclusion, most cases of help were to relatives, supporting kin-selection theory. However, things are often more complex than that: 23% of the helpers actually helped unrelated individuals. When the researchers looked at this in detail they saw that they were unrelated, but not unknown. Individuals helped other individuals with which they had social ties: previous year's partners - no hard feelings! or they helped in nests where another 'ex' was also helping. Maybe there is an element of reciprocity there. These results could make you think that long-tailed tits help guys they know, and the fact that they often help kin is just but the consequence that they tend to know their siblings socially, but is is more interesting than that.Another, key prediction of kin selection theory: helpers should invest more the more related they are to the individuals they help (that is, helping is a cost and they should adjust the costs to the benefits). With their data of provisioning rates, they could indeed confirm that this is true: helpers provisioning rates increased with the relationship to the nestlings they fed.Therefore long-tailed tits do recognise kin and preferentially assist them, providing support for the role of kin selection in the evolution of their breeding behaviour.At the end of the breeding season, family groups come together in flocks, that will joining other tits and small birds and wander around the canopies throughout the winter.Nam, K., Simeoni, M., Sharp, S., & Hatchwell, B. (2010). Kinship affects investment by helpers in a cooperatively breeding bird Proceedings of the Royal Society B: Biological Sciences, 277 (1698), 3299-3306 DOI: 10.1098/rspb.2010.0737... Read more »
Nam, K., Simeoni, M., Sharp, S., & Hatchwell, B. (2010) Kinship affects investment by helpers in a cooperatively breeding bird. Proceedings of the Royal Society B: Biological Sciences, 277(1698), 3299-3306. DOI: 10.1098/rspb.2010.0737
There are two neat articles about species distributions in the October issue of Ecology Letters, and they complement one another in an interesting way.
The first, by Murphy et al. (2010), examines the abundance of eastern North American tree species at their northern and southern limits. The second, a study by Burton et al. (2010), discusses the importance of evolution at the advancing edge.... Read more »
Murphy, H., VanDerWal, J., & Lovett-Doust, J. (2010) Signatures of range expansion and erosion in eastern North American trees. Ecology Letters, 13(10), 1233-1244. DOI: 10.1111/j.1461-0248.2010.01526.x
Burton, O., Phillips, B., & Travis, J. (2010) Trade-offs and the evolution of life-histories during range expansion. Ecology Letters, 13(10), 1210-1220. DOI: 10.1111/j.1461-0248.2010.01505.x
Single moms all over the animal kingdom do their best to raise offspring without the support of a partner…but is it enough?
Not if you’re a Nicaraguan cichlid. Recent research shows that adjustment of brood care in the absence of a mate is not enough to account for the care that would be provided by [...]... Read more »
Lehtonen, T., Wong, B., Svensson, P., & Meyer, A. (2010) Adjustment of brood care behaviour in the absence of a mate in two species of Nicaraguan crater lake cichlids. Behavioral Ecology and Sociobiology. DOI: 10.1007/s00265-010-1062-5
A Night View of Planet Earth (Image Courtesy of NASA )
What will it take to curb carbon dioxide emissions? Over 90% of the light being emitted in the picture above was generated using fossil fuels. The facts are that, on average, each person on the planet requires 1,819 kg of oil per year. So there are two choices - reduce the carbon footprint of each person, or reduce the total number of people. Since the world population is not expected to decline, there has been a real effort to reduce the carbon footprint.
The problem with that scenario is the magnitude of human population growth. Most science classes explain the human population growth using an exponential growth curve - yet, in many cases, the reality of the fact that humans are behaving much like insects or bacteria escapes most college freshman. The YouTube video below, however, visually demonstrates what has occurred in the last 100 or so years. The video starts off slow, so some narration is needed on behalf of the instructor....
Human Population Growth
So given that fact the the human population, despite our best interests, will continue to grow, and that growth means more people using carbon-based resources (at least for the near future), what are the options? Many have suggested that urbanization may actually help reduce the overall carbon footprint - after all, people in cities tend to own fewer cars, have smaller living spaces, and live closer to their workplaces. Others suggest that only an aggressive approach to the human population issue will work. The problem has been that few simulations have attempted to actually quantify which approach will work best, and whether different approaches need to be implemented for developing and industrialized countries.
A study released this week by scientists from NCAR (National Center for Atmospheric Research), NOAA, (National Oceanographic and Atmospheric Administration) and the IIASA( International Institute for Applied Systems Analysis) has placed some numbers on these scenarios (see the link below). Since population reduction is not an option, the researchers looked at whether a decrease in population growth by aging (and the associated reductions in fertility), or increased urbanization of the population, would have a greater impact on carbon emissions.
Their results indicated that overall, the aging of the human population, and the reduction in overall fertility and slowing of population growth, may contribute to up to 29% of the needed reductions in carbon dioxide emissions by the year 2050. While a decrease in population growth was a major factor, this could easily be offset by increased urbanization in developing countries (which could potentially raise carbon emissions by up to 25%), mostly because of an increase in economic output, and an increase in demands for goods, associated with the the urbanization of the workforce in these countries.
The age diagrams of textbooks often demonstrate the developing countries with high birthrates will place an increased demand on resources over time. What this study does is to link the increased demand to global climate change, carbon emissions, and population growth. It also brings into account the idea of population demographics - the fact that it where the population lives - may play a major role in the modeling of how the climate would change over time.
O'Neill BC, Dalton M, Fuchs R, Jiang L, Pachauri S, & Zigova K (2010). Global demographic trends and future carbon emissions. Proceedings of the National Academy of Sciences of the United States of America, 107 (41), 17521-6 PMID: 20937861
NSF Press Release : Population Change: Another Influence on Climate Change
Seed Magazine articles on Population Growth:
Is Population a Problem ? by Maywa Montenegro ( June 10, 2010)
All Consuming by David Biello (August 23, 2010)
... Read more »
O'Neill BC, Dalton M, Fuchs R, Jiang L, Pachauri S, & Zigova K. (2010) Global demographic trends and future carbon emissions. Proceedings of the National Academy of Sciences of the United States of America, 107(41), 17521-6. PMID: 20937861
There are lots of things I enjoy about studying bacteria. I love their biochemistry and the secret inner workings of their metabolic pathways. I love that everything they do the manage within the confines of a single cell, and I love that you can go in there with a wrench and hit some genes until they make what you want.But what I'm really enjoying exploring at the moment is more ecological bacteriology; how bacteria interact with their environment. How they respond to changes to stresses and, most importantly, to other bacteria. In my last post I covered how natural throat bacteria can help destroy dangerous pathogens such as MRSA Staph aureus so today I'm going to look at almost the opposite; how some bacteria can give each other a helping hand in order to infect humans.Campylobacter jejuni is a bacteria that I feel a special affinity for because I've worked with it, back in my first ever summer project. Unfortunately it's not a very nice bacteria and can lead to bad stomach illnesses with some rare but quite threatening complications. It's found in chicken meat and cheese as it is perfectly capible of surviving happily in animals without causing them any diseases.One of the problems with working with Campylobacter jejuni (henseforth shortened to Campy which is what we called it in the lab) is that it's very fussy about the amount of oxygen it's it. Campy is microaerophilic, which means it needs oxygen, but only small amounts, give it too much and all the cels die on you. This problem was solved in the lab by using tightly sealed containers and special packs of ... stuff ... which were put inside the containers to create the right conditions. But this does raise an important question; if the bacteria is so difficult to culture on a plate in the lab then what the hell is it doing surviving on the surface of chicken meat!A recent study (reference below) found what you've probably guessed if you were reading this post closely, the Campy were being aided by the surrounding bacteria. The picture below shows both Campy and a bacteria called Pseudomonas putida in close interaction, with long fibrelike structures connecting them. Noone seems to be really sure what the fibre-like structures are, they may be being used for chemical communication, or they may just be keeping the bacteria in close physical contact.The campy is the more slender and slighly spiral shaped bacteria in the centre, the others are PutidaBoth bacteria were identified as being in close contact, as well as being seen together under the microscope. Further experiments were done to show that the Putida was required for Campy survival - different Campy strains were grown in both the presence and absence of the supporting Putida to see how long they could survive in completely aerobic conditions. The results are kind of hilarious, without the help of the Putida bacteria the Campylobacter just die, really quickly:Figure A (top) shows the Campy with Putida grown as well, Figure (B) shows the Campy grown alone. You don't really have to be particularly good at science to interpret that one! Interestingly it was found that the interaction between different strains of both Campy and Putida was fairly specific as well, as you can see in the graph above, only three of the Campy strains have survived past 50 hours with the help of this particular Putida. Three of the Campy's still die, although they surive longer than with no help at all.As Putida are areobic, the most likely explanation for how they are helping is that they create a microaerophilic microenvironment within their immediate surroundings. This is the kind of environment that it is thought Campy will naturally migrate to. This might be less of a helping relationship and more of a seriously exploitative one, with the Campylobacter swarming as quickly as possible towards the environment created by the Putida and then wrapping them all up in a sticky mesh to stop them moving away.This special relationship is not applicable for all Campys, in other environments such as in humans and in chicken poo the Campy exist fine on their own, but in the highly aerobic environment of the meat surface they rely on other bacteria to survive. The implications for treatment of bacteria are intreguing (especially for antibiotic resistant strains of Campy) but it is another reminder that despite laboratory conditions bacteria do not just exist in isolation. They inhabit a whole tiny world, with challenges of it's own, surrounded by other bacteria that chenge their envirnment both for better and for worse.---Hilbert F, Scherwitzel M, Paulsen P, & Szostak MP (2010). Survival of Campylobacter jejuni under conditions of atmospheric oxygen tension with the support of Pseudomonas spp. Applied and environmental microbiology, 76 (17), 5911-7 PMID: 20639377---Follow me on Twitter!... Read more »
Hilbert F, Scherwitzel M, Paulsen P, & Szostak MP. (2010) Survival of Campylobacter jejuni under conditions of atmospheric oxygen tension with the support of Pseudomonas spp. Applied and environmental microbiology, 76(17), 5911-7. PMID: 20639377
Want to rediscover an “extinct” mammal? Start by looking for a critter that researchers believe was done in by habitat loss within the last 100 years. Your odds of bringing it back from the dead aren’t too bad, concludes a provocative new study. It also suggests that conservation biologists stop wasting their time and money […] Read More »... Read more »
Fisher, D., & Blomberg, S. (2010) Correlates of rediscovery and the detectability of extinction in mammals. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2010.1579
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