Ing. Karel Halačka CSc.

Pozice vědecký pracovník grantový
Zaměření ichtyologie
Pracoviště Pracoviště Brno

+420 543 422 532
Halačka Karel

Výzkumné směry

  • ekologie, reprodukce, histochemie a karyologie,
  • studium polyploidního komplexu karase stříbřitého (Carassius auratus gibelio) a jeho dynamika na území České republiky,
  • reprodukce ryb, histologie jejich gonád a integumentu,
  • ochrana ohrožených druhů ryb.

Probíhající projekty

Soutok Moravy a Dyje – současnost a budoucnost (2024–2026)

Ukončené projekty

Jak a proč zvířata opouštějí sex: kauzální role hybridizace v iniciaci asexuality (2017–2019)
Aplikace biomanipulací s využitím top down efektu s cílem omezit negativní dopady zemědělství na eutrofizaci vodárenských nádrží (2016–2018)
Zvýšení a zefektivnění produkce lososovitých ryb v ČR s využitím jejich genetické identifikace (2015–2018)
Biodiverzita ryb v oblasti soutoku Moravy a Dyje - podpora a stabilizace populací vzácných a ohrožených druhů (2007–2009)
Populační a genetická struktura pstruha obecného a lipana podhorního jako základ úspěšného rybářského obhospodařování lososových vod (2005–2009)

Vzdělání

  • 1979-1983: inženýrské studium – Vysoká škola zemědělská v Brně, specializace rybářství. Diplomová práce: Vliv krmiva kontaminovaného aflatoxiny na kapří plůdek.

Zaměstnání

  • 1985-1989: ichtyologické oddělení Ústavu zoologie obratlovců – kandidátská disertační práce: Histologie, histochemie a ultrastruktura pokožky vybraných druhů ryb.
  • 1989-současnost: Ústav biologie obratlovců AV ČR – vědecký pracovník.

Publikace

2023

Halačka K, Janko K, Fedorčák J, Koščo J, Vetešník L (2023). Effect of heparin as an anticoagulant on measurements of the erythrocyte genome size using flow cytometry in bony fishes of different ploidy. Acta veterinaria Brno, 92: 171-179.

2022

Janáč M, Šlapanský L, Kopeček L, Prudík B, Mrkvová M, Halačka K, Jurajda P (2022). Fine-scale microhabitat niche separation allows coexistence of two invasive species. Hydrobiologia, 849: 4407-4425.
Tichopád T, Franěk R, Doležálková-Kaštánková M, Dedukh D, Marta A, Halačka K, Steinbach C, Janko K, Pšenička M (2022). Clonal gametogenesis is triggered by intrinsic stimuli in the hybrid's germ cells but is dependent on sex differentiation. Biology of Reproduction, 107: 446-457.

2021

Halačka K, Janko K, Vetešník L (2021). Non-invasive ploidy determination in live fish by measuring erythrocyte size in capillaries. Acta Ichthyologica et Piscatoria, 51: 275-280.

2020

Blabolil P, Bartoň D, Halačka K, Kočvara L, Kolařik T, Kubečka J, Šmejkal M, Peterka J (2020). The fate of 0+ asp (Leuciscus aspius) after being stocked in a reservoir. Biologia, 75: 989-996.
Kočí J, Röslein J, Pačes J, Kotusz J, Halačka K, Koščo J, Fedorčák J, Iakovenko N, Janko K (2020). No evidence for accumulation of deleterious mutations and fitness degradation in clonal fish hybrids: Abandoning sex without regrets. Molecular Ecology, 29: 3038-3055.
Lusk S, Halačka K, Vetešník L, Lusková V, Hanel L (2020). Třicet let od ukončení projektu „Vodohospodářská výstavba jižní Moravy“ (1989–2019). Lampetra. Bulletin pro výzkum a ochranu biodiverzity vodních toků, 9: 81-1361210 .
Šmiga Ľ, Fedorčák J, Faltýnková A, Stefanov T, Bystrianska J, Halačka K, Koščová L, Koščo J (2020). Endohelminth Parasites in Loaches Cobitis spp. (Actinopterygii: Cobitidae), with the First Record of Allocreadium transversale (Rudolphi, 1802) (Digenea: Allocreadiidae) in Bulgaria. Acta Zoologica Bulgarica, 72: 311-314.

2019

Adámek Z, Mikl L, Šlapanský L, Jurajda P, Halačka K (2019). The diet of predatory fish in drinking water reservoirs how can they contribute to biomanipulation efforts?. Folia zoologica, 68: 215-224.
Bartoš O, Röslein J, Kotusz J, Pačes J, Pekárik L, Petrtýl M, Halačka K, Štefková Kašparová E, Mendel J, Boron A, Juchno D, Leska A, Jablonska O, Beneš V, Šídová M, Janko K (2019). The Legacy of Sexual Ancestors in Phenotypic Variability, Gene Expression, and Homoeolog Regulation of Asexual Hybrids and Polyploids. Molecular Biology and Evolution, 36: 1902-1920.
Halačka K, Mareš J, Vetešník L, Blabolil P (2019). Application of the alizarin red S mass marking technique and its detection in stocked asp (Leuciscus aspius). Biologia, 74: 1359-1362.
Halačka K, Vetešník L, Muška M (2019). Charakteristika populací vybraných evropsky významných druhů ryb na území České republiky. Příroda, 39: 55-661210 .

2018

Fedorčák J, Pekárik L, Halačka K, Šmiga Ľ, Manko P, Hajdú J, Vetešník L, Koščo J (2018). Microhabitat preferences of triploid Cobitis fish and diploid progenitors in two streams in Slovakia (Danube River Basin). Limnologica, 69: 59-66.
Jurajda P, Roche KF, Halačka K, Mrkvová M, Zukal J (2018). Winter activity of common bream (Abramis brama L.) in a European reservoir. Fisheries Management and Ecology, 25: 163-171.

2017

Fedorčák J, Koščo J, Halačka K, Manko P (2017). Growth differences in different biotypes of the hybrid complex of Cobitis elongatoides x Cobitis tanaitica (Actinopterygii: Cypriniformes: Cobitidae) in the Okna River (Danube River basin), Slovakia. Acta Ichthyologica et Piscatoria, 47: 125-132.
Halačka K, Muška M, Mendel J, Vetešník L (2017). A newly discovered population of the Balkan spiny loach Sabanejewia balcanica (Karaman, 1922) in the River Jihlava, Czech Republic. Folia zoologica, 66: 163-166.
Lusk S, Koščo J, Lusková V, Halačka K, Mendel J, Košúth P (2017). The nonindigenous fish Perccottus glenii in the Tisza River drainage, Eastern Slovakia – I. part: history of invasion, habitat associations and genetic characteristics (results up to the year 2006). Lampetra. Bulletin pro výzkum a ochranu biodiverzity vodních toků, 8: 127-1431210 .
Lusk S, Halačka K, Májsky J, Vetešník L, Mendel J (2017). Sekavčík balkánský (Sabanejewia balcanica) v České republice – minulost, současnost a budoucnost. Lampetra. Bulletin pro výzkum a ochranu biodiverzity vodních toků, 8: 90-1021210 .

2016

Stierandová S, Vukic J, Vasil'eva ED, Zogaris S, Shumka S, Halačka K, Vetešník L, Švátora M, Nowak M, Stefanov T, Koščo J, Mendel J (2016). A multilocus assessment of nuclear and mitochondrial sequence data elucidates phylogenetic relationships among European spirlins (Alburnoides, Cyprinidae). Molecular Phylogenetics and Evolution, 94: 479-491.

2015

Halačka K (2015). Differences in haematology and respiratory system morphology at three neogobiid species. Open Life Sciences, 10: 514-520.
Halačka K, Kopp R, Klíma O, Mareš J (2015). Epidermis structure in the brook trout (Salvelinus fontinalis) and its Arctic char (Salvelinus alpinus) hybrid. Acta veterinaria Brno, 84: 159-166.
Halačka K, Pekárik L (2015). Length-weight relationship of Cobitis elongatoides Heckel & Kner, 1858 from a pure diploid population in the Nová Říše Reservoir, Czech Republic. Journal of Applied Ichthyology, 31: 562-564.
Šimková A, Hyršl P, Halačka K, Vetešník L (2015). Physiological and condition-related traits in the gynogenetic-sexual Carassius auratus complex: different investments promoting the coexistence of two reproductive forms?. BMC Evolutionary Biology, 15: 154.
Šimková A, Vojtek L, Halačka K, Hyršl P, Vetešník L (2015). The effect of hybridization on fish physiology, immunity and blood biochemistry: A case study in hybridizing Cyprinus carpio and Carassius gibelio (Cyprinidae). Aquaculture, 435: 381-389.

2014

Vítek T, Halačka K, Bartoňová-Marešová E, Vetešník L, Spurný P (2014). Identification of natural hybrids between Cottus poecilopus, Heckel, 1837, and Cottus gobio, Linnaeus, 1758, at a hybrid zone on the Svratka River (Czech Republic). Journal of Applied Ichthyology, 30: 102-108.

2013

Vetešník L, Halačka K, Šimková A (2013). The effect of ploidy and temporal changes in the biochemical profile of gibel carp (Carassius gibelio): a cyprinid fish species with dual reproductive strategies. Fish Physiology and Biochemistry, 39: 171-180.

2012

Halačka K, Vítek T, Vetešník L, Spurný P (2012). Epidermis structure and blood parameter differences between sculpin Cottus gobio and Siberian sculpin Cottus poecilopus from the Morava watershed. Folia zoologica, 61: 9-16.
Mendel J, Papoušek I, Marešová E, Vetešník L, Halačka K, Nowak M, Čížková D (2012). Permanent Genetic Resources added to Molecular Ecology Resources Database 1 April 2012 – 31 May 2012. Molecular Ecology Resources, 12: 972-974.
Sivka U, Halačka K, Sušnik Bajec S (2012). Morphological differences in the skin of marble trout Salmo marmoratus and of brown trout Salmo trutta. Folia Histochemica Et Cytobiologica, 50: 255-262.

2011

Prchalová M, Horký P, Slavík O, Vetešník L, Halačka K (2011). Fish occurrence in the fishpass on the lowland section of the River Elbe, Czech Republic, with respect to water temperature, water flow and fish size. Folia zoologica, 60: 104-114.

2010

Halačka K, Vetešník L, Papoušek I, Mendel J, Šimková A (2010). The epidermal structure of Carassius gibelio: a link with ploidy status in spawning and postspawning periods. Journal of Fish Biology, 77: 2171-2179.
Halačka K, Vetešník L, Mendel J, Papoušek I (2010). Can spawning marks on females of the spined loach (Cobitis sp., Teleostei) be caused by scratches from males during mating?. Folia zoologica, 59: 329-331.
Lusková V, Lusk S, Halačka K, Vetešník L (2010). Carassius auratus gibelio—the most successful invasive fish in waters of the Czech Republic. Russian Journal of Biological Invasions, 1: 176-180.

2009

Vetešník L, Halačka K, Papoušek I, Mendel J, Šimková A (2009). The first record of a natural hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus in the Danube River Basin, Czech Republic: morphological, karyological and molecular characteristics. Journal of Fish Biology, 74: 1669-1676.
Vetešník L, Halačka K, Papoušek I, Mendel J, Šimková A (2009). The first record of a natural hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus in the Danube River Basin, Czech Republic: morphological, karyological and molecular characteristics. Journal of Fish Biology, 74: 1669-1676.

2008

Bartoňová E, Papoušek I, Lusková V, Koščo J, Lusk S, Halačka K, Švátora M, Vetešník L (2008). Genetic diversity and taxonomy of Sabanejewia balcanica (Osteichthyes: Cobitidae) in the waters of the Czech Republic and Slovakia. Folia zoologica, 57: 60-70.
Bartoňová E, Papoušek I, Lusková V, Koščo J, Lusk S, Halačka K, Švátora M, Vetešník L (2008). Genetic diversity and taxonomy of Sabanejewia balcanica (Osteichthyes: Cobitidae) in the waters of the Czech Republic and Slovakia. Folia zoologica, 57: 60-70.
Flajšhans M, Rodina M, Halačka K, Vetešník L, Gela D, Lusková V, Lusk S (2008). Charakteristika spermatu polyploidního karase stříbřitého, Carassius gibelio. Bulletin VÚRH Vodňany, 44: 78-81.
Flajšhans M, Rodina M, Halačka K, Vetešník L, Gela D, Lusková V, Lusk S (2008). Characteristics of sperm of polyploid Prussian carp Carassius gibelio. Journal of Fish Biology, 73: 323-328.
Mendel J, Lusk S, Vasil'eva ED, Vasil'ev VP, Lusková V, Ekmekci FG, Erk'kan F, Ruchin A, Koščo J, Vetešník L, Halačka K, Šanda R, Pashkov AN, Reshetnikov SI (2008). Molecular phylogeny of the genus Gobio Cuvier, 1816 (Teleostei: Cyprinidae) and its contribution to taxonomy. Molecular Phylogenetics and Evolution, 47: 1061-1075.
Mendel J, Lusk S, Koščo J, Vetešník L, Halačka K, Papoušek I (2008). Genetic diversity of Misgurnus fossilis populations from the Czech Republic and Slovakia. Folia zoologica, 57: 90-99.
Mendel J, Lusk S, Koščo J, Vetešník L, Halačka K, Papoušek I (2008). Genetic diversity of Misgurnus fossilis populations from the Czech Republic and Slovakia. Folia zoologica, 57: 90-99.
Papoušek I, Vetešník L, Halačka K, Lusková V, Humpl M, Mendel J (2008). Identification of natural hybrids of gibel carp Carassius auratus gibelio (Bloch) and crucian carp Carassius carassius (L.) from lower Dyje River floodplain (Czech Republic). Journal of Fish Biology, 72: 1230-1235.
Papoušek I, Lusková V, Koščo J, Lusk S, Halačka K, Povž M, Šumer S (2008). Genetic diversity of Cobitis spp. (Cypriniformes: Cobitidae) from different drainage areas. Folia zoologica, 57: 83-89.
Papoušek I, Lusková V, Koščo J, Lusk S, Halačka K, Povž M, Šumer S (2008). Genetic diversity of Cobitis spp. (Cypriniformes: Cobitidae) from different drainage areas. Folia zoologica, 57: 83-89.

2007

Halačka K, Vetešník L, Lusk S, Mendel J, Papoušek I (2007). The X1X1X2X2/X1X2Y multiple sex chromosome system in the Zingel zingel (Pisces: Perciformes) from the Morava River (Czech Republic). Caryologia, 60: 222-225.
Koščo J, Lusk S, Halačka K, Pekárik L, Košuthová L (2007). Výskyt chránených a invázných druhov rýb v povodí Ipl’a. Natura Carpatica, 48: 141-152.
Vetešník L, Papoušek I, Halačka K, Lusková V, Mendel J (2007). Morphometric and genetic analysis of the Carassius auratus complex from an artificial wetland in Morava River floodplain, Czech Republic. Fisheries Science, 73: 817-822.

2006

Vetešník L, Halačka K, Lusková V, Lusk S (2006). Erythrocyte profile of diploid and triploid silver crucian carp (Carassius auratus). Acta veterinaria Brno, 75: 203-207.

2005

Koščo J, Lusk S, Halačka K, Lusková V, Košuth P (2005). Distribution of species of the genus Gobio in the Tisza River drainage area, Slovakia. Folia zoologica, 54: 65-72.
Lojkásek B, Lusk S, Halačka K, Lusková V, Drozd P (2005). The impact of the extreme floods in July 1997 on the ichthyocenosis of the Oder Catchment area (Czech Republic). Hydrobiologia, 548: 11-22.
Lusk S, Lusková V, Halačka K, Šlechtová V, Šlechta V (2005). Characteristics of the remnant Vimba vimba population in the upper part of the Dyje River. Folia zoologica, 54: 389-404.
Lusk S, Halačka K, Lusková V, Horák V (2005). Distribution of Gobio species in the Czech Republic. Folia zoologica, 54: 56-64.
Mendel J, Lusková V, Halačka K, Lusk S, Vetešník L (2005). Genetic diversity of Gobio gobio populations in the Czech Republic and Slovakia, based on RAPD markers. Folia zoologica, 54: 13-24.
Šlechtová V, Lusková V, Šlechta V, Halačka K, Lusk S, Koščo J (2005). Intraspecific allozyme diversity of Gobio gobio in Czech and Slovak rivers. Folia zoologica, 54: 25-32.

2004

Horák V, Lusk S, Halačka K, Lusková V (2004). Artificial wetlands - yes or no?. Ecohydrology & Hydrobiology, 4: 119-127.
Lojkásek B, Lusk S, Halačka K, Lusková V (2004). Fish communities in the Poodří Protected Landscape Area (the Odra River basin). Czech Journal of Animal Science, 49: 121-130.
Lusk S, Halačka K, Lusková V, Vetešník L (2004). Re-occurrence of Zingel streber (Teleostei: Pisces) in the Czech Republic. Folia zoologica, 53: 417-422.
Lusk S, Hartvich P, Halačka K, Lusková V, Holub M (2004). Impact of extreme floods on fishes in rivers and their floodplains. Ecohydrology & Hydrobiology, 4: 173-181.
Lusk S, Koščo J, Lusková V, Halačka K, Košuth P (2004). Alien fish species in the floodplains of the Dyje and the Bodrog rivers. Ecohydrology & Hydrobiology, 4: 199-205.
Lusková V, Halačka K, Vetešník L, Lusk S (2004). Changes of ploidy and sexuality status of "Carassius auratus" populations in the drainage area of the River Dyje (Czech Republic). Ecohydrology & Hydrobiology, 4: 165-171.
Lusková V, Koščo J, Halačka K, Stráňai I, Lusk S, Flajšhans M (2004). Status of populations of the genus Cobitis in Slovakia. Biologia, 59: 621-626.
Vetešník L, Lusk S, Halačka K, Spurný P (2004). Morphometric characteristics and growth of Carassius auratus in the lower part of the River Dyje (Czech Republic). Ecohydrology & Hydrobiology, 4: 215-221.

2003

Halačka K, Lusková V, Lusk S (2003). Carassius "gibelio" in the fish communities of the Czech Republic. Ecohydrology & Hydrobiology, 3: 133-138.
Koščo J, Lusk S, Halačka K, Lusková V (2003). The expansion and occurrence of the Amur sleeper (Perccottus glenii) in eastern Slovakia. Folia zoologica, 52: 329-336.
Lusk S, Lusková V, Halačka K, Smutný M (2003). Anglers' catches as an indicator of fish population status. Ecohydrology & Hydrobiology, 3: 113-119.
Lusk S, Halačka K, Lusková V (2003). Rehabilitating the floodplain of the lower River Dyje for fish. River Research and Applications, 19: 281-288.
Lusk S, Koščo J, Halačka K, Lusková V, Flajšhans M (2003). Identification of Cobitis from the Slovakian part of the Tisza basin. Folia Biologica-Krakow, 51: 61-65.

2002

Lusk S, Lusková V, Halačka K, Horák V (2002). Osteichthyes. Folia Facultatis Scientiarum Naturalium Universitatis Masarykianae Brunensis, 106: 29-49.

2001

Lusk S, Halačka K, Lusková V, Horák V (2001). Annual dynamics of the fish stock in a backwater of the River Dyje. Regulated Rivers: Research and Management, 17: 571-581.

2000

Halačka K, Lusková V, Lusk S (2000). Fecundity of Cobitis elongatoides in the Nová Říše Reservoir. Folia zoologica, 49: 141-150.
Halačka K, Lusková V, Lusk S (2000). Contribution to the occurrence of parasites in Cobitis elonatoides and Cobitis elongatoides x C. sp. Folia zoologica, 49: 215-218.
Lojkásek B, Lusk S, Halačka K, Lusková V (2000). Fish communities in the drainage area of the Osoblaha river and effect of the 1997 flood. Czech Journal of Animal Science, 45: 229-236.
Lusk S, Lusková V, Halačka K (2000). On the occurrence of populations of the genera Cobitis and Sabanejewia (Pisces, Cobitidae) in the Czech Republic. Folia zoologica, 49: 97-106.
Šlechtová V, Lusková V, Šlechta V, Lusk S, Halačka K, Bohlen J (2000). Genetic differentiation of two diploid-polyploid complexes of spined loach, genus Cobitis (Cobitidae), in the Czech Republic, involving C. taenia, C. elongatoides and C. spp.: allozyme interpopulation and interspecific differences. Folia zoologica, 49: 67-78.

1999

Lusk S, Lusková V, Halačka K (1999). Vývoj a stav ichtyofauny ve vodách Národního parku Podyjí. Thayensia, 2: 96-1071210 .
Lusk S, Lusková V, Halačka K (1999). Development and status of the ichthyofauna in the waters of the Podyjí National Park. Thayensia, 2: 108-1191210 .

1998

Halačka K, Lusk S, Lusková V (1998). Fish communities in artificial pools in the floodplain along the lower reaches of the River Dyje. Folia zoologica, 47: 125-134.
Lusk S, Lusková V, Halačka K, Šlechta V, Šlechtová V (1998). Trends and production of a fish communities of the barbel zone in a stream of the Czech Republic. Folia zoologica, 47: 67-72.
Lusk S, Lusková V, Halačka K (1998). The status of tench (Tinca tinca (L.)) in aquatic habitats of the floodplain along the lower reaches of the River Dyje (Czech Republic). Polskie Archiwum Hydrobiologii, 45: 407-414.
Lusk S, Halačka K, Lusková V (1998). The effect of an extreme flood on the fish communities in the upper reaches of the Tichá Orlice River (The Labe drainage area). Czech Journal of Animal Science, 43: 531-536.

1997

Halačka K, Lusková V, Lusk S (1997). Manifestations of senescence in the reproduction of nase, Chondrostoma nasus. Folia zoologica, 46: 169-173.
Lusk S, Halačka K, Jurajda P, Lusková V, Peňáz M (1997). Diversity of fish communities in the waters of the Podyjí National Park. Živočišná výroba, 42: 269-275.
Lusk S, Halačka K, Lusková V (1997). Vliv malých vodních elektráren na vodní toky a jejich rybí osídlení. Bulletin VÚRH Vodňany, 33: 111-119.

1996

Baruš V, Halačka K, Prokeš M (1996). Presence and distribution of the nematode Anguillicola crassus in the European eel in the Morava River drainage basin, Czech Republic. Živočišná výroba, 41: 219-224.
Halačka K (1996). Structure and histochemistry of the epidermis of Barbel (Barbus barbus). Folia zoologica, 45: 97-101.
Lusk S, Lusková V, Halačka K (1996). Distribution of species of the family Percidae in the waters of the Czech republic. Acta Universitatis Carolinae, Biologica, 40: 139-145.
Lusk S, Halačka K, Lusková V, Pražák O (1996). Fish assemblages of the "Soutok" area in Southern Moravia, Czech Republic. Acta Universitatis Carolinae, Biologica, 40: 147-155.
Lusková V, Halačka K (1996). Some hematological indices in barbel, Barbus barbus. Folia zoologica, 45: 103-108.

1995

Halačka K, Lusková V (1995). Interrelations and bioindicative application of epidermal, hematological and biochemical indices in grayling (Thymallus thymallus L.). Acta Universitatis Carolinae, Biologica, 39: 159-167.
Halačka K (1995). Embryonic development of brown trout (Salmo trutta m. fario). Folia zoologica, 44: 175-184.
Halačka K, Lusk S (1995). Mortality in eggs of nase, Chondrostoma nasus, during incubation. Folia zoologica, 44: 51-56.
Halačka K (1995). Structure and histochemistry of the epidermis of nase (Chondrostoma nasus). Folia zoologica, 44: 99-104.
Lusk S, Halačka K (1995). The first finding of the Tubenose Goby, Proterorhinus marmoratus, in the Czech Republic. Folia zoologica, 44: 90-92.
Lusk S, Halačka K (1995). Anglers' catches as an indicator of population size of the nase, Chondrostoma nasus. Folia zoologica, 44: 185-192.
Lusk S, Halačka K (1995). The river bottom and fish populations in streams. Folia Facultatis Scientiarum Naturalium Universitatis Masarykianae Brunensis, 91: 95-100.
Lusk S, Halačka K, Lusková V (1995). Influence of small hydroelectric power stations on fish communities in streams. Živočišná výroba, 40: 363-367.
Lusková V, Halačka K, Lusk S (1995). Dynamics of the haemogram in the nase, Chondrostoma nasus. Folia zoologica, 44: 69-74.
Lusková V, Lusk S, Halačka K (1995). Yearly dynamics of enzyme activities and metabolite concentrations in blood plasma of Chondrostoma nasus. Folia zoologica, 44: 75-82.

1994

Halačka K, Jurajda P (1994). Charakteristika elektrolovných zařízení pro odlov ryb. Živočišná výroba, 39: 733-741.