Bahir Dar Fishery and Other Aquatic Life Research Center

Bahir Dar, Ethiopia

Bahir Dar Fishery and Other Aquatic Life Research Center

Bahir Dar, Ethiopia

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Shkil F.N.,RAS Severtsov Institute of Ecology | Stolero B.,Hebrew University of Jerusalem | Sutton G.A.,Hebrew University of Jerusalem | Belay Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | And 2 more authors.
Journal of Applied Ichthyology | Year: 2014

Here we describe the results of a preliminary study to evaluate the response of the cellular skeleton of the large African barb, Labeobarbus intermedius, to exposure to high levels of the thyroid hormone T3 for 1 and 3 months. We examined the effects in terms of mineral density and mechanical properties of the operculum bone, as well as evaluated and compared the light microscopy features of this bone between the treatment groups and the untreated control group. We found a significant increase in bone mineral density in the treated groups compared to untreated controls, and a tendency towards a corresponding increase of bone material stiffness (Young's modulus). These findings suggest that thyroid hormone enrichment may contribute to improved skeletal properties in pond-raised fish, and help moderate osteomalacia, a commonly seen problem in aquaculture. © 2014 Blackwell Verlag GmbH.


Smirnov S.V.,RAS Severtsov Institute of Ecology | Borisov V.B.,RAS Severtsov Institute of Ecology | Kapitanova D.V.,Russian Academy of Sciences | Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | Shkil F.N.,RAS Severtsov Institute of Ecology
Journal of Applied Ichthyology | Year: 2012

Large African barbs (genus Labeobarbus) of Lake Tana (Ethiopia) form a species flock, which includes 15 species differing in biology, ecology, and shape features, including skull proportions. Early craniogenesis was studied in three species of Lake Tana barbs: L. intermedius, a proposed ancestor of Tana species flock, L. brevicephalus, a small-sized and early-maturating barb, and L. megastoma, a large-sized, piscivorous species. The general sequence of cranial cartilage and bone appearance is the same for the barb species studied. However, they differ greatly in temporal pattern of craniogenesis. As compared to L. intermedius, bony skull development is accelerated relative to chondrocranial development in L. brevicephalus and retarded in L. megastoma. These differences in temporal pattern of craniogenesis are proposed to account for the different cranial proportions displayed by these barbs. © 2012 Blackwell Verlag, Berlin.


Shkil F.N.,RAS Severtsov Institute of Ecology | Kapitanova D.V.,Russian Academy of Sciences | Borisov V.B.,RAS Severtsov Institute of Ecology | Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | Smirnov S.V.,RAS Severtsov Institute of Ecology
Journal of Applied Ichthyology | Year: 2012

The effects of thyroid hormone (TH) level changes on skeletal development were studied in cyprinids Labeobarbus intermedius (Barbinae) and Danio rerio (Danioninae). TH was revealed to influence development of a skull, axial skeleton, paired fins and girdles, and squamation. Usually, high TH-level promotes the premature onset and acceleration of ontogenetic processes, whereas TH-deficiency delays and retards them. However, skeletal elements differ in TH-responsiveness. Alterations of TH level induce developmental changes in some structures but do not cause any changes in others. As a result, the normal sequence of ontogenetic events and the temporal interrelations between ontogenetic processes undergo changes resulting in changes in adult morphology. © 2012 Blackwell Verlag, Berlin.


Borisov V.B.,RAS Severtsov Institute of Ecology | Shkil F.N.,Russian Academy of Sciences | Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | Smirnov S.V.,RAS Severtsov Institute of Ecology
Journal of Ichthyology | Year: 2012

Developmental information on the structure and composition of the cartilaginous and bony skull in the large African barb Labeobarbus (=Barbus) intermedius (Teleostei; Cyprinidae) is provided. Sequences of cartilages and bones appearance from a large series of cleared and Alizarin red- and Alcian blue-stained laboratory-reared specimens ranging from prehatching larvae to juvenile stages are described. Comparisons of cranial development are made among cyprinids: L. intermedius, Danio rerio, Barbus barbus, and Cyprinus carpio. © 2012 Pleiades Publishing, Ltd.


Smirnov S.V.,RAS Severtsov Institute of Ecology | Kapitanova D.V.,Russian Academy of Sciences | Borisov V.B.,RAS Severtsov Institute of Ecology | Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | Shkil F.N.,Russian Academy of Sciences
Journal of Ichthyology | Year: 2012

Helerochronies caused by changes in the hormonal status are proposed to play a major role in the diversification of the Lake Tana barbs of Labeobarbus (=Barbus) genus (Dgebuadze and Mina, 2008). To test this hypothesis, we (i) compared temporal patterns of cranial development in L. intermedius, likely ancestral for Tana species flock, and L. brevicephalus and L. megastoma proposed to be paedomoiphic and peramoiphic, respectively; (ii) studied the role of thyroid hormone (TH) in the regulation of L. intermedius development; (iii) evaluated the effect of TH changes on the definitive morphology, and (iv) evaluated the possible role of TH in diversification of Tana barbs. Skull development was found to be heterochronicaily changed in L. brevicephalus and L. megastoma as compared to L. intermedius; revealed heteroclironies may account for differences in skull proportions distinguishing these barbs, TH was shown to play a major role in the regulation of ontogeny. Changes in TH level cause heterochronies in the development of a skull, axial skeleton, fins and fin girdles, squamation, and dentition. Heteroclironies were shown to influence adult morphology of these structures. These findings support the hypothesis of the involvement of developmental and hormonal factors in the diversification of the Lake Tana large barbs. © 2012 Pleiades Publishing, Ltd.


Shkil F.N.,RAS A.N. Severtsov Institute of Ecology and Evolution | Lazebnyi O.E.,Russian Academy of Sciences | Kapitanova D.V.,RAS A.N. Severtsov Institute of Ecology and Evolution | Abdissa B.,Bahir Dar Fishery and Other Aquatic Life Research Center | And 2 more authors.
Russian Journal of Developmental Biology | Year: 2015

Species flock of Lake Tana (Ethiopia) large African barbs (Labeobarbus; Cyprinidae; Teleostei), the largest recent cyprinid species flock, was studied as a model system for investigating ontogenetic mechanisms of the explosive morphological divergence often accompanying sympatric speciation in bony fishes. Comparative morphological analysis carried out with the use of geometric morphometric techniques revealed quantitative differences in the head shapes of species under study. Comparative analysis of skull development revealed significant interspecies differences in the temporal characteristics of craniogenesis in these species. These two lines of evidence suggest that heterochronies in craniogenesis underlie divergence in the head shapes of adult Tana barbs. This prediction was verified via experimental changes of temporal characteristics of craniogenesis in L. intermedius, a putative ancestor for the Lake Tana species flock. For this aim, timing and rate of skull development were changed by artificial manipulation of thyroid hormone levels. This experiment verified, that it is heterochronies that underlie an explosive morphological divergence of the Lake Tana barbs species flock. Our findings together with those reported in the literature suggest variability in the activity of the hypothalamic-pituitary-thyroid axis to contribute to these heterochronies. © 2015, Pleiades Publishing, Inc.

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