David B. Dusenbery is a biophysicist with a central interest in how

information Information is an Abstraction, abstract concept that refers to something which has the power Communication, to inform. At the most fundamental level, it pertains to the Interpretation (philosophy), interpretation (perhaps Interpretation (log ...

influences the

behavior Behavior (American English) or behaviour (British English) is the range of actions of Individual, individuals, organisms, systems or Artificial intelligence, artificial entities in some environment. These systems can include other systems or or ...

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s. In later years, he also considered the physical constraints

hydrodynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in ...

imposes on

microorganism A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

s and

gametes A gamete ( ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. The name gamete was introduced by the Ge ...

Research

Most of Dusenbery's research deals with how

controls behavior. At Caltech and the early years at Georgia Tech, Dusenbery focused on experimental studies of the nematode ''

Caenorhabditis elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a Hybrid word, blend of the Greek ''caeno-'' (recent), ''r ...

'' because of its small nervous system and favorable genetics. These experimental studies inspired the development of several innovative techniques: * Countercurrent separation for isolating mutant individuals altered in their tendency to swim toward a chemical. * A method for applying controlled stimulation to an individual nematode and recording its responses. * A method using computer analysis of live video to simultaneously track many individuals and record changes in their locomotion. * The video tracking method was even used as a detector of sensory stimuli emanating from a gas chromatograph. * Dusenbery had several students who developed a variety of techniques employing nematodes for inexpensive testing of samples (industrial or environmental) for several kinds of toxicity. Initially, Dusenbery was attempting to understand the flow of information in the nervous system of this simple animal. Later, he turned to the flow of information outside the organism, and how physics constrains how organisms behave. More recently, he has also considered hydrodynamic constraints on small organisms, which can only swim at low speeds, where viscosity is far more important than inertia (low

Reynolds number In fluid dynamics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between Inertia, inertial and viscous forces. At low Reynolds numbers, flows tend to ...

s). From physical analysis, Dusenbery predicted that the long-held belief that bacteria were too small to employ spatial sensing mechanisms to follow chemical gradients was erroneous and predicted that bacteria following steep gradients of chemicals at high concentrations would benefit from using a spatial mechanism. In 2003, a new bacterial species was discovered that swim sideways and respond to differences in oxygen concentration at the two ends of the cell, allowing them to follow steep gradients of oxygen. Similar considerations have also been applied to the behaviors of

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

s, leading to an explanation of why the

sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...

/egg (

ovum The egg cell or ovum (: ova) is the female reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capa ...

) and thus the

male Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...

female An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and ...

distinctions exist.Dusenbery, D.B. (2006). Selection for high gamete encounter rates explains the evolution of anisogamy using plausible assumptions about size relationships of swimming speed and duration. J. Theoretical Biol. 241:33-8.

References

Notable publications

Books

* Dusenbery, David B. (1992). ''Sensory Ecology: How Organisms Acquire and Respond to Information''. W.H. Freeman, New York. . * Dusenbery, David B. (1996). “Life at Small Scale: The Behavior of Microbes”. Scientific American Library. . * Dusenbery, David B. (2009). “Living at Micro Scale: The Unexpected Physics of Being Small”. Harvard University Press. .

Research papers

*Dusenbery, D.B. (1996). Information is where you find it. Biol. Bull. 191:124-128. *Dusenbery, D.B. (1997). Minimum size limit for useful locomotion by free-swimming microbes. Proc. Natl. Acad. Sci. USA 94:10949-10954. *Dusenbery, D.B. (1998). Fitness landscapes for effects of shape on chemotaxis and other behaviors of bacteria. J. Bacteriol. 180 (22):5978-5983. *Dusenbery, D.B. (2000). Selection for high gamete encounter rates explains the success of male and female mating types. J. Theoret. Biol. 202:1-10. *Dusenbery, D.B. (2002). Ecological Models Explaining the Success of Distinctive Sperm and Eggs (Oogamy). J. Theoretical Biol. 219:1-7. *Dusenbery, D.B. (2006). Selection for high gamete encounter rates explains the evolution of anisogamy using plausible assumptions about size relationships of swimming speed and duration. J. Theoretical Biol. 241:33-8.

External links

A more complete list of David Dusenbery’s research papers.David Dusenbery’s website
{{DEFAULTSORT:Dusenbery, David B. American biophysicists Reed College alumni University of Chicago alumni Georgia Tech faculty Living people Year of birth missing (living people)