Sunday, July 19, 2015

Acronym in biology: HHO for Havers-Halberg oscillation

Biological rhythms in animals have fascinated observers of nature for a long time. An example is the circadian rhythm, a diurnal rhythm synchronized with the day/night circle. In mammals, metabolic product rhythms with a twenty-four-hour oscillation pattern are known as the mammalian circadian clock [1]. The concentration of molecular components in body fluids rises and falls on a twenty-four hour cycle.

What about metabolites cycling according to a multidien schedule (multi-day schedule)?  Timothy G. Bromage of the Hard Tissue Research Unit of the New York University College of Dentistry describes findings of his research group showing that certain metabolites in the blood of domestic pigs cycled on a five-day rhythm. Those metabolites belong to two distinct groups: metabolites of one group reached their peak three days later than the other [2,3].

Until recently, such synchronized multi-day rhythms have commonly been overlooked in mammalian chronobiology studies. Most strikingly, the five-day rhythm leaves its marks in enamel and bone structures. The Bromage team found that the pig's teeth show the striae-of-Retzius pattern with a repeat period of exactly five. This evidence suggests a multidien rhythm that regulates growth and body size, which is called the Havers-Halberg oscillation (HHO) by Bromage and his colleagues [2]:

We call this rhythm the Havers-Halberg oscillation (HHO), after Clopton Havers who in 1691 described what we now know are lamellae in bone and striae of Retzius in enamel, and Franz Halberg, father of modern chronobiology. 

Periodic layer structures in hard tissue are documented for various mammal species. Rhythm & stria relationships, which will be similar to the reported correlation between biochemical oscillations and linear marks in pig teeth, can be expected to exist in other mammal species. For humans, the better understanding of such repeat patterns may eventually help to design individual health and healing plans in rhythm with metabolic cycles—think rhythmically tuned diet and medication.    

The English physician Clopton Havers was a pioneer in osteogeny. Anatomists are familiar with Haversian canals traversing compact bone tissue. Havers was born in 1657 in Stambourne, Essex. He is best known for his work on the microstructure of bone. In 1686, he was elected a Fellow of the Royal Society. Havers died in Essex in 1702 [3,4].

Franz Halberg was born in 1919 in Bistriz in Romania. In the 1940s, Halberg performed medicinal research at the University of Innsbruck and became a citizen of Austria. In 1948, he immigrated to the United States, where he continued his inqueries in biology and medicine.  Halberg  founded the fields of  quantitative chronobiolgy, chronomics and chronobioethics. He died in 2013 [5].

The term “Havers-Halberg oscillation” honors two outstanding scientists living in different epochs and gaining insight within until recently unconnected domains, which now find their synthesis in a more holistic view in the science community, deepening and advancing cross-subdiscipline understanding in life science.

Keywords: quantitative chronobiology, biological cycles, chronomics, osteogeny, stria of Retzius, life history.

References and more to explore
[1] Caroline H. Ko and Joseph S. Takahashi: Molecular components of the mammalian circadian clock. Human Molecular Genetics 2006, R271-R277 [].
[2] Timothy G. Bromage: Long in the Tooth: Striation in teeth reveal the pace of life. Natural History June 2015, 123 (5),16-21.
[3] Timothy G. Bromage and Malvin N. Janai: The Havers-Halberg oscillation regulates primate tissue and organ masses across the life-history continuum. Biological Journal of the Linnean Society August 2014, 112 (4), 649-656 [].
[4] Jessie Dobson: Clopton Havers [].
[5] The Blog of Funny Names: Clopton Havers, Bone Master [].
[6] Germaine Cornelissen, Francine Halberg, Julia Halberg and Othild Schwartzkopff: Obituary. Franz Halberg, MD (5 July 1919-9 June 2013) - In Appreciation. Chronobiology International 2013, 1-3 [].

Wednesday, July 8, 2015

Topotaxis: geomagnetically driven orientation and navigation above the ocean floor

The composed noun topotaxis is built from the Greek words topos, meaning place, and taxis, meaning order or responsive movement. The word topotaxis refers to the movement of an animal  from place to place (migration) in response to geographical features the animal is able to sense. The term was coined by the marine biologist and sensory physiologist A. Peter Klimley, who wants to find out if sharks and rays can detect changes in local magnetic underwater topography and use these magnetic-field features as their guiding map—instead of the globally-caused, compass-oriented vector of  Earth's magnetic field, as typically hypothesized [1,2].

Islands, seamounts and subsurface ridges are examples of  geographic formations causing distinct local geomagnetic underwater-landmarks. By diving with the sharks and tagging & tracking them to follow their ocean floor navigation, Klimley explains how is idea of geomagnetic topotaxis has surfaced [3]: 

Our survey of the magnetic field surrounding El Bajo [an volcanic underwater mountain in Mexico's Sea of Cortez rising from the depths of the ocean floor to just 20 meters from the surface] revealed that the outbound and return path of the sharks we were studying coincided with these magnetic ridges and valleys, I hypothesized, therefore, that the magnetic variations in the ocean floor presented the sharks with the equivalent of a route map, and in a 1993 paper in Marine Biology [4], I coined the term topotaxis for an animal's orientation to these magnetic-topographic features.

Understanding navigation and resting behavior of sharks and other marine life—driven by topotactic guidance or other means—will help to design marine sanctuaries, which may protect dwindling shark populations and at the same time provide sites for educational and recreational shark ecotourism.

Keywords: magnetic topography, magnetoreception, travel pattern, migration, Baha California.

References and more to explore
[1] A. Peter Klimley, Director of the Biotelemetry Laboratory, University of California, Davis:
[2] A. Peter Klimley: Experimental Study of Geomagnetic Topotaxis With Elasmobranchs. Grantome:
[3] A. Peter Klimley: Shark Trails of the Eastern Pacific. American Scientist July-August 2015, 103 (4), pp. 276-287 [].
[4] A. P. Klimley: Highly directional swimming by scalloped hammerhead sharks, Sphyrna lewini, and subsurface irradiance, temperature, bathymetry, and geomagnetic field. Marine Biology 1993, 117, pp. 1-22 [].

Monday, July 6, 2015

Acronym in experimental physics: MINOS for Main Injector Neutrino Oscillation Search

Neutrinos are subatomic particles (leptons) with half-integer spin and without electric charge. They come in three types or flavors: electron-neutrino, muon-neutrino and tau-neutrino. The flavor of a neutrino oscillates, while the neutrino is flying through space—for example, after being generated by beta-decay of a radioactive atom. Different neutrino flavors have slightly different masses [1].

Neutrino oscillation has been observed by different experiments.  The oscillation probability of  neutrinos and the exact tiny neutrino masses have not yet been measured with the desired accuracy. The MINOS experiment has the aim to do this: the abbreviation MINOS stands for Main Injector Neutrino Oscillation Search [1-3] .

MINOS is based on two detectors: the first being stationed at the neutrino source at the Fermilab and the second being located 450 miles (735 km) away at the Soudan Underground Mine, a former iron mining site, in norther Minnesota. Frank Close explains the MINOS design in his acclaimed “neutrino cracker” [3]:

A huge 5000 tonne detector was built in a new, bigger, cavern in the Soudan mine. This utises yet another detection method. Charged particles passing through plastic, which had been loaded with small quantities of special chemicals, emit flashes of light (scintillate). These scintillations can be collected and delivered to phototubes which are similar in principle to those used to detect the Cerenkov light in the water detectors. By forming the plastic into narrow strips, sandwiched between plates of steel, the path of the charged particles through the detector can be followed, and by magnetising the steel plates, the curvature of the paths and thus the energy of the produced particles can be measured. From all this information, the details of the neutrino interaction, and in particular its energy, can be reconstructed. Then both the distance travelled (the 735 km from Fermilab) and the neutrino energy are known. A very similar (but smaller) detector was also built at Fermilab, so that by comparing the energy distribution of the neutrinos measured at Fermilab with that measured at Soudan, they could measure how any deficit depended on the energy of the neutrinos. If, as expected, this showed an oscillatory pattern, it would measure the difference in mass between the produced and oscillated neutrino.

What are the special chemicals loaded into the steel-plate-sandwiched plastic strips?

Neutrino mass is not included in the Standard Model of particle physics: neutrinos are assumed to have zero mass. But the phenomenon of neutrino oscillation suggests non-zero masses. MINOS is expected to clarify the neutrino mass conundrum and, thus, add new insight to particle physics and beyond.

Keywordselementary particles, Cerenkov radiation, oscillation pattern, nuclear physics, cosmology.

References and more to explore
[1] Cambridge MINOS Group:
[2] Fermilab: The MINOS Experiment and NuMI Beamline:
[3] Frank Close: Neutrino. Oxford University Press, Oxford, U.K., 2010.