Sci-non-Fi

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It has been hinted that sexual frustration within young male bottlenose dolphins is the reason behind sightings of recent random acts of violence against stray porpoises. The bottlenose dolphins have been seen chasing, ramming and then drowning porpoises in groups of up to seven. 21 out 23 dolphins sighted in these acts of violence were young males which has led researches at Okeanis to beleive that these attacks are used to release frustration during breeding season when older males out compete younger males in the right to breed with females.

Source

New Scientist.

Stimulate your neurons.

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This image represents data from experiments at SLAC’s Linac Coherent Light Source. Scientists used the light source to probe the structure of a protein complex called Photosystem I, which helps plants convert sunlight to fuel. X-ray laser pulses from the LCLS hit millions of tiny protein crystals at various angles and scattered into a detector, forming diffraction patterns. Scientists combined 15,445 of those patterns to get the 3-D visualization shown here. The colors and sizes of the spheres represent the intensities of the spots in the diffraction patterns. Researchers analyzed this information to come up with a low-resolution match to the known 3-D structure of the protein. The technique, which uses much smaller protein crystals than today’s methods, could allow scientists to decipher the structures of thousands of important proteins that are now out of reach, including many involved in treating disease. This research, reported in the Feb. 3, 2011 issue of Nature, demonstrates the evolving potential of light sources, powerful all-purpose tools for a wide range of research—and the ultimate “killer app” for particle physics technology. (Image: Thomas White, DESY; via Symmetry)

Courtesy of the Scipsy blog.

Sexually Conflicted Beetles.

The Gnatocerus cornutus or Broad-horned flour beetle is a sexually dimorphic species, meaning that both sexes have different phenotypes (appearances). The males display exaggerated mandibles which are used in intrasexual selection (male-male competition). Mandible size is a sex-limited trait among Broad-horned flour beetles which only the males develop. Males with larger mandibles have a higher mating success rate and better fitness but it has been observed that females within populations of males with enlarged mandibles have a lower fitness. This negative intersexual correlation for fitness between the sexes is a sign of an existing intralocus sexual conflict (Harano et al., 2010). This type of sexual conflict arises when the same set of alleles between males and females possess different optima. An example of this is the human hip where females require a larger hip for childbirth while males do not, instead of this trait being sex-limited and expressed differently in each sex a compromise has been reached with both evolving a hip that does not provide optimum fitness for either sex (Arnqvist & Rowe, 2005). It has been noted in an experiment conducted by Harano et al. (2010) that while mandible size is a sex-limited trait females still show signs of decreased fitness.

It has been widely asserted but unsubstantiated that sex-limited trait development will resolve intralocus sexual conflict over time. In the Harano et al. (2010) experiment the claim that sex-limited trait development will resolve intralocus sexual selection is put to the test. They select six beetle populations containing: two populations selected for large male mandible size (L), two populations selected for small male mandible size (S), and two control populations with no selection on male mandible size (C). If the claim is correct then selection on mandible size shouldn’t affect female fitness in any of the populations. In the experiment the fitness of the female beetles was measured by lifetime fecundity (lifetime reproductive success, LRS) and longevity. The results (figure 1) show a strong correlation between female fitness (LRS) and male mandible size. It is apparent from these results that intralocus sexual conflict has not been resolved through the sex-limited trait development of mandibles. Harano et al. (2010) then tested explanations for the decreased female fitness in large mandible populations. The other possible LRS influences which were recorded were female survival, mass, abdomen size and egg size. Of the possible influences only abdomen size showed a connection between mandible size and female fitness (figure 2). Larger abdomen sizes were linked to higher female fitness but in populations with males possessing enlarged mandibles female and male abdomen sizes were much smaller. It is here where the intralocus sexual conflict becomes evident as the alleles for large mandibles also code for reduced abdomen sizes. Males in the need for large mandibles have evolved smaller abdomens and while females do not develop large mandibles the antagonistic selection for large mandibles has had a negative impact nonetheless.  

Sex-limited trait development may resolve some instances of intralocus sexual conflict but in the case of the Broad-horned flour beetle the development of sex distinguishable traits has only moved the focus of this sexual conflict from mandible size towards abdomen size (Harano et al., 2010). For sex limited trait development to be a proper resolve for intralocus sexual conflict traits need to be genetically independent from one another, which is usually not true amongst many extant organisms. The Harano et al. (2010) experiment has successfully tested and provided evidence against sex-limited traits being a resolve for intralocus sexual selection and highlighted that in many situations the focus will shift towards a genetically dependant trait.

Figure 1. The correlation between treatment groups and female fitness: (L) Large mandibles, (C) Control group, (S) Small mandible, and (LRS) Lifetime Reproductive Success.

Figure 2. The correlation between (a) female survival and treatment group; (b) female egg size and treatment group; (c) female body mass and treatment group; and (d) female abdomen size and treatment group: (L) Large mandibles, (C) Control group, (S) Small mandible.

References

·         Arnqvist G. & Rowe L. (2005) Sexual Conflict. Princeton University Press, Princeton, New Jersey.

·         Harano T. Okada K. Nakayama S. Miyatake T. & Hosken D.J. (2010) Intralocus Sexual Conflict Unresolved by Sex-Limited Trait Expression. Current Biology, 20: 2036-2039.

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Ichneumon wasp, compound eye and antenna base (40X).

Charles Krebs Photography.

Here’s a clip depicting the inner workings of a cell, the smallest unit of life. The animation was a collaboration between Harvard University and XVIVO animations. If you want a better quality video then I suggest you head over to the XVIVO website and check it out in HD.

While you are watching this clip remember that these very same processes are happening within your body at an accelerated rate. The numerous mechanisms for growing organs, repairing tissues and replacing old cells are a continuous occurrence and they won’t stop till the day you die.

Sit back and enjoy this fantastic biological animation.

The Mechanics of Déjà vu.

It’s a phenomenon experienced by mostly every human being on the planet. The feeling that everything you are currently experiencing has happened before but there is no prior recollection of said experience. Déjà vu occurs when there is a disturbance (delay) in the brain’s “time labelling” mechanism. For an animal to survive in its external environment two of the things it must be able to do are; identify an event and then determine when this event happened in accordance to other events. Take a ship’s log for instance, if you wanted to piece together a ship’s entire history you would find every major event that has occurred and the time it happened within the log (Efron, 1963). The brain is similar to this in that it logs and labels events.

How does déjà vu occur?

When events are perceived the information is relayed to the two hemispheres within the brain, the non-dominant and dominant hemispheres. Usually information is first received by the non-dominant hemisphere and then passed to the dominant hemisphere within a matter of milliseconds. Déjà vu occurs when there is a delay of this information pass over. So essentially both hemispheres perceive the same event but the information pass over is delayed between the two hemispheres. This delay gives the sensation that you have logged the event but the event has never been labelled (Efron, 1963).

Reference

Efron R., (1963). Temporal Perception, Aphasia and Déjà vu. Neurophysiology-Biopysics Research Unit, Veterans Administraion Hospital, Boston, Massachusetts.

Thumb through any biology text book pre-2010 and you’ll learn that the six basic elements for life include carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus. This was true up until December 2, 2010 when Wolfe-Simon et al. (2010) published a paper on their discovery of an organism that substitutes one of these vital elements for something previously thought to be too toxic and unstable for life; arsenic. The organism was discovered in Mono Lake, CA, and is a bacterium of the strain GFAJ-1 belonging to the family Halomonadaceae. Instead of using phosphorus as its DNA backbone it has instead adapted to use arsenic.

Some fields of science, such as astrobiology which is dedicated to finding life on other planets, are especially excited about this discovery as it now gives them the possibilities of extraterrestrial life containing different biological make-ups to the one previously believed to be universal.

Reference

Wolfe-Simon F, Blum JS, Kulp TR, Gordon GW, Hoeft SE, Pett-Ridge J, Stolz JF, Webb SM, Weber PK, Davies PC, Anbar AD, Oremland RS. (2010) A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus. Science: 1197258.

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scientificillustration:

Mycoplasma mycoides

Watercolor by David S. Goodsell, 2011

David Goodsell wrote and illustrated an excellent book called ‘The Machinery of Life’ a preview is available on Google Books.

The Mycoplasma mycoides has had some recent fame with scientists from the J. Craig Venter Institute using it as a donor to create the first man-made synthetic genome (M. myciodes JCVI-syn1.0). The genome is 1.08-Mbp long (1,077,947-bp) and has been successfully transplanted into a new recipient cell which is now controlled by the synthetic genome (Gibson et al., 2010).

Reference

Gibson D.G., Glass J.I., Lartigue C., Noskov V.N., Chuang R, Algire M.A., Benders G.A., Montague M.G., Ma L., Moodie M.M., Merryman C, Vashee S., Krishnakumar R., Assad-Garcia N., Andrews-Pfannkoch C., Denisova E.A., Young L., Qi Z., Segall-Shapiro T.H., Calvey C.H., Parmar P.P., Hutchison III C.A., Smith H.O., Venter J.C. (2010). Creation of a Bacterial Cell Controlled by a Chemically Synthesized Genome. Science 2 July 2010: 329 (5987), 52-56.