Associate Professor of Biology

Office: 205-2 Hayes Biology Building

Phone: (409) 880-8260

email: christenab@my.lamar.edu

Courses Taught:  Human Anatomy and Physiology I & II (Biol 2401, 2402); Advanced Physiology (Biol 3440); Comparative Physiology (Biol 4401/5490); Cell Biology  (Biol 4470/5475); Marine Invertebrate Zoology (Biol 4401/5401); Life in the extreme (Biol 4300/5301); Marine Biology (Biol 4450/5455); Tropical Marine Biology (4401/5401); Invertebrate Zoology (Biol 3460)

Research interests:

I am primarily an invertebrate physiologist, specializing in factors affecting respiration in estuarine and marine organisms (especially the echinoderms).  I am also interested in the occurrence of respiratory pigments (such as hemoglobin) in invertebrate organisms and determining how it benefits the organism (i.e. is it used in transporting oxygen, oxygen storage, or some other function?).  My current interest is in the occurrence of hemoglobin in the ophiuroids (more commonly called brittle stars).  Past research centered on defining the biochemical properties of the hemoglobins of Hemipholis elongata (Echinodermata, Ophiuroidea) and describing a novel system of oxygen transport in this species.  Current research efforts are addressing the hemoglobin gene and its expression patterns. 

Even though Beaumont is not on the coast, we are very close to Sabine Lake and the Gulf of Mexico.  Affiliated with Lamar University is the Center for Coastal and Marine Sciences, located at Pleasure Island.

Recent undergraduate student research performed in my lab:

a.   Effects of hypercapnia on respiration and arm regeneration in Hemipholis elongata

b.  Expression of HSP70 in 2 species of amphiurid brittle star

Graduate students:

Kristina Radivojevich (2012).  A tale of two brittle stars: Effects of hypercapnia and temperature on respiration and regeneration in Hemipholis elongata and Amphipholis gracillima

Jonathan Esclovon: Effects of temperature on respiration, righting response and HSP 70 expression in 5 species of tropical brittle stars

Current Research projects:

a.  Expression of afuni in the brittle star Ophiactis simplex during regeneration

I  am a member of the pre-professional advisory committee and the faculty advisor for  the local chapter of the American Medical Student Association (AMSA).

• Radivojevich, K. and A.B. Christensen. 2012.  A tale of two brittlestars: A comparison of the effects of decreased pH and increased temperature on the respiration rates of Hemipholis elongata and Amphipholis gracillima (Echinodermata, Ophiuroidea). Gulf of Mexico Science

• Christensen, A.B., and E.F. Christensen. 2011. Comparisons of Populations of North American Ophiactid Brittle Stars Possessing Hemoglobin Using Intronic Variation.   13^th International Echinoderm Conference, C. Johnson (ed.) Echinoderms in a Changing World. (in press)

• Christensen, A.B., H.D. Nguyen, M. Byrne. 2011. Thermotolerance and the effects of hypercapnia on the metabolic rate of the ophiuroid Ophionereis schayeri: inferences for survivorship in a changing ocean. JEMBE 403:31-38.

• Christensen, A.B., E.F. Christensen, and D.W. Wiesrock.  2008.  Population structure of North American Ophiactis spp. possessing hemoglobin.  Marine Biology 154:755-763.

• Christensen, A.B. and E.F. Christensen.  2008.  Sequence variation in the hemoglobin gene of Ophiactis spp. Gulf of Mexico Science 26: 46.

• Christensen, A.B., E.F. Christensen, and M.V. Sukhodolets.  2006.  The nucleic acid and amino acid sequences of the fraction 1 hemoglobin of the brittle star Hemipholis elongata Say.  Proceedings of the 12th International Echinoderm conference.  In press.

• Bonds, B., A.B. Christensen, and D.K. Flaherty, 2006.  Enterococci species in Gulf coast marine water samples as measured in the Environmental Protection Agency Method 1600. Texas J. Sci. 58:141-146.

• Baldwin, T., A.B. Christensen, J. Talley, and D.K. Flaherty.  2005.  A two year longitudinal study of marine enterococci density in coastal waters of Jefferson County, Texas.  108th Texas Academy of Sciences Meeting.

• Christensen, A.B. (2004).  A new distribution record and notes on the biology of the brittle star Ophiactis simplex (Echinodermata, Ophiuroidea) in Texas.  Texas  J. Sci. 56: 175-179.

• Christensen, A.B., and Christensen, E.F., 2003.  Molecular comparison of a small ophiactid brittle star with Ophiactis simplex and Ophiactis rubropoda.  in: Heinzeller, T., and J. Nebelsick (eds). Echinoderms: Munich.  Proceedings of the 11th International Echinoderm Conference. Balkema, Leiden, pg. 574.

• Christensen, A.B., J.M. Colacino, and C. Bonaventura.  2003. Functional and biochemical properties of the  hemoglobins of the burrowing brittle star, Hemipholis elongata Say (Ophiuroidea, Echinodermata).   Biological Bulletin. 205:54-65.

• Riker, A. and A.B. Christensen, 2003.  Analysis of population structure of an ophiactid brittlestar (Echinodermata, Ophiuroidea) using RAPDS.  106th Texas Academy of Sciences.

• Christensen, A.B., and D.K. Dean.  2002.  Population structure in a fissiparous ophiactid brittle star possessing hemoglobin.  Abstract submitted to SICB for the annual meeting and to published in the Journal of Comparative and Integrated Biology.

• Christensen, A.B., 2001.  Why do small brittlestars have hemoglobin?  Gulf of Mexico Science. (Dec. 2001).

• Brown, P., E.R. George, K. Chaudry, and A.B. Christensen, 2001.  The effects of creatine supplementation on the kidneys of mice.  Texas Acad. Sci.

• Bean, K.D., and A.B. Christensen, 2001.  The effects of size and temperature on oxygen uptake of the banded Pygmy Sunfish, Elassoma zonatum.  Texas Acad. Sci.

• Christensen, A.B. and J.M. Colacino, 2000.  Respiration in the burrowing brittlestar, Hemipholis elongata (Say) (Echinodermata, Ophiuroidea): A study of the effects of environmental variables on oxygen uptake.  Comp. Biochem. Physiol. A.  127(2): 201-213.

• Christensen, A.B.  1998.  The properties of the hemoglobins of Ophiactis simplex (Echinodermata, Ophiuroidea). Am.Zool., 38: 120A.

• Beardsley, A.M., Colacino, J.M., 1998.  System-wide oxygen transport by the water vascular system of the burrowing ophiuroid, Hemipholis elongata (Say).  In: Mooi, R., Telford, M. (Eds.), Echinoderms: San Francisco.  Proceedings of the 9th International Echinoderm Conference.  Balkema, Rotterdam, pp. 323-328.

• Beardsley, A.M., Colacino, J.M., Gelin, J., 1996.  In situ respiration rates and behavioral responses to declining PO₂ of the burrowing ophiuroid, Hemipholis elongata.  Am. Zool.  35, 37A.

• Beardsley, A.M., and J.M. Colacino, 1994.  Red blood cell circulation and oxygen transport in Hemipholis elongata (Ophiuroidea, Echinodermata).  Am. Zool., 34: 35A.

• Beardsley, A.M., Colacino, J.M., Cashon, R., Bonaventura, C.J., 1993.  The hemoglobins of the brittlestar, Hemipholis elongata (Say) (Ophiuroidea, Echinodermata). Biochemical and ligand binding properties.  Am. Zool.  33, 43A. 

• Graves, J.E., J.R. McDowell, A.M. Beardsley, and D.R. Scoles.  1992.  Stock structure of the bluefish Pomatomus saltatrix along the mid-Atlantic coast.  Fish. Bull., 90: 703-710.