Arad

Zeev Arad

Research Summary

Comparative physiology of heat exposed birds: 

It was believed for a long time that heat-exposed birds are not capable of regulating their blood acid-base status. In my pioneering studies in Abdim’s storks and various strains of domestic fowl I have shown for the first time that they do effectively regulate blood acid-base status.

I have established the fowl as a model for studies of thermoregulatory capacities in avian species using comparative studies of the commercial strains with the unique desert-origin Bedouin Fowl. I have shown that under extreme environmental conditions, Bedouin fowls express their natural (genetic) adaptations and effectively regulate their physiological homeostasis. Including reproductive mechanisms are an essential component in the physiological performance of birds under stressful conditions.. This model comparative system was tested recently at the cellular and molecular level in relation to the heat shock response. The rock pigeon was found to be the most heat resistant bird so far studied. In collaboration with the late Prof. Jacob Marder we have shown that heat acclimated pigeons can regulate a normal body temperature under extreme heat of up to 60oC using its unique capacity for water evaporation through the skin. This capacity enables the rock pigeon to breed and grow nestlings, while maintaining metabolic rate, acid base status and brain temperature. In a long series of studies, we made a major contribution by showing that birds could employ an effective mechanism of brain cooling under stressful conditions of heat and dehydration. This capacity is achieved by cooling the arterial blood flowing to the brain in a vascular heat exchange – the rete ophtalmicum. In a further step, this capacity was used as an index for the ontogenetic development temperature regulation in altricial and precocial species.

Conservation of wetland and ecophysiology of fish-eating birds

In the recent years, my team has focused on the long-lasting, intensive conflict between fishermen and the conservation of the deteriorating wetland habitats for fish-eating birds. To find a solution to this conflict, the strategy adopted was to study thoroughly the biology of the species concerned, with emphasis on their energy requirements, foraging and feeding behaviour and other physiological capacities. These studies constructed a scientific basis for the future management of the problems. Such was the conclusion that migrating pelicans must stop-over for feeding in Israel on route to Africa and consequently, the implementation of the safe feeding sites offered for migrating white pelicans. The current studies of the wintering great cormorant and the resident pygmy cormorant, a bird on the verge of global extinction reveals for the first time their different energetic requirements and prey preference, their underwater foraging performance and their hydromechanics of diving, with far reaching ecological implications for their management and protection. Already, these studies are affecting the routine behaviour of the fishermen and wild killing by fishermen is reduced to a great extent.

 

Ecolphysiology of feeding in mammals and passerine birds

In a series of studies we focused on the physiology of the Egyptian fruit bat that revealed its adaptations to the low protein content of its diet and its capacity to effectively regulate its metabolism and body temperature under heat exposure and dehydration. In the next stage we focused on the nitrogen metabolism of passerine birds in an attempt to evaluate their minimal nitrogen requirements (MNR), total endogenous nitrogen loss (TENL), and the effect of protein and water intake on their nitrogenous waste composition. Physiologists characterize birds as uricotelic because they excrete most of their nitrogenous “waste” products as uric acid. We are testing the possibility that this substance is something else than just a waste and study an alternative physiological role of uric acid, hypothesizing that uric acid is not only a waste product, but also a powerful antioxidant in passerine birds. Recently, we were interested in the ecophysiology of rodents and birds in relation to plant secondary metabolites. With evidence accumulating that shows birds absorb a significant fraction of water-soluble sugars via the passive, paracellular pathway (as opposed to using the transporter-mediated mechanisms that mammals rely on heavily), we wondered if this would expose them to increased levels of plant-derived, water-soluble toxins relative to their mammalian counterparts. Water-soluble toxins are a major class of plant secondary metabolites, and animals that consume a wide variety of plant materials are known to ingest them. To test our idea, we measured paracellular absorption of water-soluble carbohydrate probes in the gastrointestinal tracts of four fruit-eating species (two avian and two mammalian).  In doing so, we found that the birds (both passerines) passively absorbed significantly more of the water-soluble compound than the mammals (both rodents).

 

Ecophysiology of land-snails

In a long series of studies, it was shown that the distribution patterns of land snails in Israel are mainly determined by the aridity gradient (precipitation and temperature) from north to south and from west to east. We revealed a suite of physiological, morphological and behavioural adaptations that work in concert to achieve water balance. These adaptations were shown to occur at all levels of biological complexities and life histories (inetr- and intraspecific differences, differences in life style (bush, rock or soil dwelling), according to the specific microhabitat, and may be of phylogenetic and genetic origin. I was recently studying the possible involvement of stress proteins in the annual cycle of aestivation and activity of desert and non-desert species.

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Education/ Resume

1969-1972             B.Sc. Zoology and Genetics, Hebrew University of Jerusalem.

1972-1974             M.Sc. Zoology, Environmental Physiology, Hebrew University, Jerusalem.

1982                     Ph.D. Zoology, Environmental Physiology, Hebrew University, Jerusalem.

Academic Appointments

1973-1981          Teaching Assistant, Hebrew University of Jerusalem, Department of Zoology.

1985-1994           Assistant Professor, Department of Biology, Technion – Israel Institute of  Technology,  Haifa.

1994-2013           Associate Professor, Department of Biology, Technion – Israel Institute of    Technology, Haifa.

2013                    Full Professor

Awards

1975     Landau prize for distinguished graduate research

1990     British Welcome Trust – “Blood flow in heat stressed fowl”

2020     Honorary member of the Israeli Society of Zoology

Key Publications
  • Marder, J. and Arad, Z.  (1975)  The acid-base balance of Abdim’s stork (Sphenorhynchus abdimii) during thermal panting. Comp. Biochem. Physiol. 51A:887-889.
  • Arad, Z.  (1983)  Thermoregulation and acid-base status in the panting dehydrated fowl.  J. Appl. Physiol. 54:234-243.
  • Arad, Z. and Midtgard, U. (1984)  Differences in the structure of  the rete ophthalmicum among three breeds of domestic fowls Gallus gallus domesticus (Aves). Zoomorphology 104:184-187.
  • Arad, Z., Arnason, S.S., Chadwick, A. and Skadhauge, E. (1985)  Osmotic and hormonal responses to heat and dehydration in the fowl. J. Comp. Physiol. B. 155:227-234.
  • Arad, Z., Gavrieli-Levin, I., Eylath, U. and Marder, J. (1987)  Effect of dehydration on cutaneous water evaporation in heat exposed pigeons (Columba livia). Physiol. Zool. 60:623-630.
  • Arad, Z. and Bernstein, M.H. (1988)  Temperature regulation in Turkey Vultures. Condor 90:913-919.
  • Arad, Z., Horowitz, M., Marder, J. and Eylath, U. (1989)  Osmoregulation and body fluid compartmentalization in dehydrated heat-exposed pigeons (Columba livia). Am. J. Physiol. 257:R377-R382.
  • Arad, Z., Goldenberg, S. and Heller, J. (1989)  Resistance to desiccation and distribution patterns in the land snail Sphincterochila. J. Zool. (Lond.) 218:353-364.
  • Arad, Z. (1989)  Ontogeny of brain temperature regulation in  pigeon hatchlings (Columba livia). Physiol. Zool. 62:908-918.
  • Korine, C., Arad, Z. and Arieli, A. (1996)  Nitrogen and energy balance of the fruit-bat Rousettus aegyptiacus, on natural fruit diets.  Zool. 69:618-634.
  • Katzir, G., Strod, T., Schechtmann, E., Hareli, S. and Arad, Z. (1999) Cattle egrets
  • (Bubulcus ibis) do not cope with light refraction, while other herons do.
  • Behav. 57:687-694.
  • Shmueli, M., Izhaki, I., Zinder, O. and Arad, Z. (2000)  The physiological state of captive
  • and migrant Great White Pelican Pelecanus onocrotalus revealed from blood chemistry.
  • Biochem. Physiol. 125A:25-32.
  • Korine, C. Speakman, J. and Arad, Z. (2004) Reproductive energetics of captive and
  • free-ranging Egyptian fruit bat (Rousettus aegypticaus). Ecology 85:220-230.
  • Ribak, G., Weihs, D. and Arad, Z. (2004) How do cormorants counter buoyancy during
  • submerged swimming?. J. Exp. Biol. 207:2101-2114.
  • Strod, T., Arad, Z., Izhaki, I. and Katzir, G. (2004) Cormorants keep their power: visual
  • resolution in a pursuit-diving bird under amphibious and turbid conditions. Curr. Biol. 14:R376-R377.
  • Tsahar, E., Martinez del Rio, C., Izhaki, I. and Arad, Z. (2005) Can birds be ammonotelic?
  • Nitrogen balance and excretion in two desert frugivores. J. Exp. Biol. 208:1025-1034.
  • Shabtay, A. and Arad, Z. (2005) Ectothermy and endothermy: evolutionary perspectives
  • of thermoprotection by HSPs. J. Exp. Biol. 208:2773-2781.
  • Ribak, G. Weihs, D. and Arad, Z. (2005) Submerged swimming of the great cormorant
  • (Phalcrocorax carbo sinensis) is a variant of the burst and glide gait. J. Exp. Biol.
  • 208:3835-3849.
  • Shabtay, A and Arad, Z. (2006) Reciprocal activation of HSF1 and HSF3 in brain and
  • blood tissues: is redundancy developmentally-related? J. Physiol. 291:566-572.
  • Tsahar, E., Izhaki, I., Arad, and Martinez del Rio, C. (2006) Do nectar-feeding and fruit-
  • eating birds have lower nitrogen requirements? An allometric test. Auk 123:1004-1012.
  • . Ribak, G, Weihs, D. and Arad, Z. (2008) Consequences of buoyancy to the maneuvering
  • capabilities of a foot propelled aquatic predator, the great cormorant (Phalcrocorax carbo
  • sinensis). J. Exp. Biol. 211:3009-3019.
  • Arad, Z., Mizrahi, T., Goldenberg, S. and Heller, J. (2010) Natural annual cycle of heat
  • shock proteins expression in land snails: desert vs. Mediterranean species of
  • Exp. Biol. 213:3487-3496.
  • Karasov, W. H., Caviedes-Vidal, E., Bakken, B. H., Izhaki, I. Samuni-Blank, M. and
  • Arad, Z. (2012) Capacity for absorption of water-soluble secondary metabolites greater
  • in birds than in rodents. PLoS ONE 7: e32417. Doi:10.1371/journal.pone.0032417.
  • Samuni-Blank, M., Izhaki, I., Dearing, M. D., Gerchman, Y., Trablshy, B., Lotan, A.,
  • Karasov, W. H. and Arad, Z. (2012). Intraspecific directed deterrence by the
  • mustard oil bomb in a desert plant. Biol. 22:1218-1220.
  • Mizrahi, T., Heller, J., Goldenberg, S. and Arad, Z. (2012) Heat shock proteins and
  • survival strategies in congeneric land snails (Sphincterochila) from different habitats.
  • Cell Stress and Chaperones 17:523-527. DOI: 10.1007/s12192-012-0341-7.
  • Mizrahi, T. Goldenberg, S. Heller, J and Arad, Z. (2016) Geographic variation in
  • Thermal tolerance and strategies of heat shock protein expression in the land snail Theba
  • pisana in relation to genetic structure. Cell Stress and Chaperones 21:219-238.
  • Samuni-Blank, M., Dearing, D. M., Gerchman, Y., Karasov, W. H., Izhaki, I. and Arad, Z.
  • (2013) Friend or Foe? Different plant-animal interactions in two congeneric rodents.

 

  • Ecol. 27:1069–1080 (DOI 10.1007/s10682-013-9655-x)

 

  • Samuni-Blank, M., Izhaki, I., Gerchman, Y., Dearing, M. D., Karasov, W. H., Trabelcy,
  • , Edwards, T. and Arad, Z. (2014) Taste and physiological responses to
  • glucosinolates: seed predator versus seed disperser. PLoS ONE 9(11): e112505.
  • doi:10.1371/journal.pone.0112505.
  • Arad, Z. (2009) Resistance to desiccation and heat. In: Landsnails of the Land of Israel
  • (Joseph Heller, Ed.). Pensoft, Sofia and Moscow. Pp. 74-93.
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Recent Publications

Samuni-Blank, M., Izhaki, I., Dearing, M. D., Gerchman, Y., Trablshy, B., Lotan, A., Karasov, W. H. and Arad, Z. (2012). Intraspecific directed deterrence by the mustard oil bomb in a desert plant. Curr. Biol. 22:1218-1220.

  • Samuni-Blank, M., Izhaki, I., Dearing, D., Karasov, W., Gerchman, Y., Kohl, K., Lymberakis, P., Kurnath, P. and Arad, Z. (2013) Physiological and behavioural           effects of fruit toxins on seed-predating versus seed-dispersing congeneric rodents. J. Biol. 216:3667-3673 (doi:10.1242/jeb.089664)
  • Samuni-Blank, M., Dearing, D. M., Gerchman, Y., Karasov, W. H., Izhaki, I. and Arad, Z. (2013) Friend or Foe? Different plant-animal interactions in two congeneric rodents. Ecol. 27:1069–1080 (DOI 10.1007/s10682-013-9655-x)
  • Samuni-Blank, M., Izhaki, I., Gerchman, Y., Dearing, M. D., Karasov, W. H., Trabelcy, , Edwards, T. and Arad, Z. (2014) Taste and physiological responses to           glucosinolates: seed predator versus seed disperser. PLoS ONE 9(11): e112505.doi:10.1371/journal.pone.0112505
  • Mizrahi, T. Goldenberg, S. Heller, J and Arad, Z. (2015) Natural variation in resistance to desiccation and heat shock protein expression in the land snail Theba pisana along a           climatic gradient. Physiol. Biochem. Zool. 88: 66-80.
  • Lessner, K. L., Dearing, M. D., Izhaki, I., Samuni-Blank, M., Arad, Z. and Karasov H. (2015) Small intestinal hydrolysis of plant glycosides: Higher glucohydrolase           activities in rodents than birds. J. Exp. Biol. 218: 2666-2669
  • Mizrahi, T. Goldenberg, S. Heller, J and Arad, Z. (2016) Geographic variation in Thermal tolerance and strategies of heat shock protein expression in the land snail Theba  pisana in relation to genetic structure. Cell Stress and Chaperones 21:219-238.
  • Kohl, K. D., Samuni-Blank, M., Lymberakis, P., Kurnath, P., Izhaki, I., Arad, Z.,          Karasov, W. and Dearing, M. D. (2016) Effects of fruit toxins on intestinal and microbial β-glucosidase activities of seed-predating and seed-dispersing rodents (Acomys ). Physiol. Biochem. Zool. 89:198-205 (DOI: 10.1086/685546).  
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