| 1. |
- Dahlström, Mia, et al.
(författare)
-
Evidence for different pharmacological targets for imidazoline compounds inhibiting settlement of the barnacle Balanus improvisus
- 2005
-
Ingår i: Journal of Experimental Zoology. - : Wiley. - 0022-104X .- 1097-010X. ; 303A:7, s. 551-562
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the effect of eight different imidazoline/guanidinium compounds on the settlement and metamorphosis of larvae of the barnacle Balanus improvisus. These agents were chosen on the basis of their similar pharmacological classification in vertebrates and their chemical similarity to medetomidine and clonidine, previously described as highly potent settlement inhibitors (nanomolar range). Seven of the tested compounds were found to inhibit settlement in a dose-dependent manner in concentrations ranging from 100 nM to 10 microM without any significant lethal effects. In vertebrate systems these substances have overlapping functions and interact with both alpha-adrenoceptors as well as imidazoline binding sites. Antagonizing experiments using the highly specific alpha(2)-antagonist methoxy-idazoxan or agmatine (the putative endogenous ligand at imidazoline receptors) were performed to discriminate between putative pharmacological mechanisms involved in the inhibition of cyprid settlement. Agmatine was not able to reverse the effect of any of the tested compounds. However, methoxy-idazoxan almost completely abolished the settlement inhibition mediated by guanabenz (alpha(2)-agonist, I(2) ligand), moxonidine (alpha(2)-agonist, I(1) ligand) and tetrahydrozoline (alpha-agonist, I(2) ligand). The actions of cirazoline (alpha(1)-agonist, I(2) ligand) BU 224 (I(2) ligand) and metrazoline (I(2) ligand) were not reversed by treatment with methoxy-idazoxan. These results suggest that the settlement inhibition evoked by the I(2) ligands and alpha(2)-agonists used in this study of the neurologically simple but well-organized barnacle larva is mediated through different physiological targets important in the overall settlement process.
|
|
| 2. |
- Fischer, Antje H. L., et al.
(författare)
-
ZOONET : perspectives on the evolution of animal form. Meeting report
- 2009
-
Ingår i: Journal of Experimental Zoology. - Hoboken, N. J. : Wiley-Blackwell. - 0022-104X .- 1097-010X. ; 312B:7, s. 679-685
-
Tidskriftsartikel (refereegranskat)abstract
- What drives evolution? This was one of the main questions raised at the final ZOONET meeting in Budapest, Hungary, in November 2008. The meeting marked the conclusion of ZOONET, an EU-funded Marie-Curie Research Training Network comprising nine research groups from all over Europe (Max Telford, University College London; Michael Akam, University of Cambridge; Detlev Arendt, EMBL Heidelberg; Maria Ina Arnone, Stazione Zoologica Anton Dohrn Napoli; Michalis Averof, IMBB Heraklion; Graham Budd, Uppsala University; Richard Copley, University of Oxford; Wim Damen, University of Cologne; Ernst Wimmer, University of Gottingen). ZOONET meetings and practical courses held during the past four years provided researchers from diverse backgrounds-bioinformatics, phylogenetics, embryology, palaeontology, and developmental and molecular biology-the opportunity to discuss their work under a common umbrella of evolutionary developmental biology (Evo Devo). The Budapest meeting emphasized in-depth discussions of the key concepts defining Evo Devo, and bringing together ZOONET researchers with external speakers who were invited to present their views on the evolution of animal form. The discussion sessions addressed four main topics: the driving forces of evolution, segmentation, fossils and phylogeny, and the future of Evo Devo.
|
|
| 3. |
- Jönsson, K. Ingemar, 1959-, et al.
(författare)
-
Experimentally induced anhydrobiosis in the tardigrade Richtersius coronifer : phenotypic factors affecting survival
- 2002
-
Ingår i: Journal of Experimental Zoology. - : John Wiley & Sons Inc.. - 0022-104X .- 1097-010X. ; 293:6, s. 578-584
-
Tidskriftsartikel (refereegranskat)abstract
- The ability of some animal taxa (e.g., nematodes, rotifers, and tardigrades) to enter an ametabolic (cryptobiotic) state is well known. Nevertheless, the phenotypic factors affecting successful anhydrobiosis have rarely been investigated. We report a laboratory study on the effects of body size, reproductive condition, and energetic condition on anhydrobiotic survival in a population of the eutardigrade Richtersius coronifer. Body size and energetic condition interacted in affecting the probability of survival, while reproductive condition had no effect. Large tardigrades had a lower probability of survival than medium-sized tardigrades and showed a positive response in survival to energetic condition. This suggests that energy constrained the possibility for large tardigrades toenter and to leave anhydrobiosis. As a possible alternative explanation for low survival in the largest specimens we discuss the expression of senescence. In line with the view that processes related to anhydrobiosis are connected with energetic costs we documented a decrease in the size of storage cells over a period of anhydrobiosis, showing for the first time that energy is consumed in the process of anhydrobiosis in tardigrades.
|
|
| 4. |
- Ledje, Christina, et al.
(författare)
-
Characterization of Hox genes in the bichir, Polypterus palmas
- 2002
-
Ingår i: Journal of Experimental Zoology. - : Wiley. - 0022-104X .- 1097-010X. ; 294:2, s. 107-111
-
Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that the increase in the number of Hox genes may have been one of the key events in vertebrate evolution. Invertebrates have one Hox cluster, while mammals have four. Interestingly, the number of Hox gene clusters is greater in the teleost fishes, zebrafish and medaka, than in mouse and human. The greater number of Hox clusters in the teleosts suggests that Hox gene duplication events have occurred during the radiation of ray-finned fishes. The question is when the Hox gene duplication event(s) that lead to seven Hox clusters in the teleosts actually occurred. We have addressed this question by studying the Hox genes in the bichir, Polypterus palmas. A preliminary PCR-estimation of the number of Hox genes suggests that Polypterus has five different Hox9 cognate group genes, which may be an indication of more than four Hox clusters in the bichir.
|
|
| 5. |
|
|
| 6. |
- Nakano, Hiroaki, 1977, et al.
(författare)
-
Regrowth of the stalk of the sea lily, Metacrinus rotundus (Echinodermata: Crinoidea).
- 2004
-
Ingår i: Journal of experimental zoology. Part A, Comparative experimental biology. - : Wiley. - 1548-8969. ; 301:6, s. 464-71
-
Tidskriftsartikel (refereegranskat)abstract
- Sea lilies are critical to understanding the evolution of the echinoderm body plan, because they are the only extant group whose adults possess a stalk, a prevalent feature in the radiation of a number of primitive echinoderm lineages. Extensive crown regeneration ability has been reported in Metacrinus rotundus, but the regenerative potential of the stalk has never been determined in any species of sea lilies. In this study, we show that M. rotundus whose stalks have been completely excised are capable of stalk regeneration. The process is similar to the growth of the original stalk, but much slower, and the regenerated stalks are not morphologically identical to the original stalk. Since stalk regeneration, in contrast to well-studied regeneration events, probably requires little additional activation of morphogenetic programs, we refer to the stalk regeneration phenomenon as "stalk regrowth" to distinguish it as a special form of regeneration. Since specimens whose entire stalk below the basal plates had been removed were able to regrow, the basal plates, and probably the aboral nerve center within them, are essential for stalk regrowth. Sea lily stalk regrowth is described in detail, and the evolution of feather stars is discussed in light of the growth pattern of the sea lily stalk.
|
|
| 7. |
- Akhverdyan, M, et al.
(författare)
-
EM studies of female meiosis in wood lemmings with different sex chromosome constitutions
- 2001
-
Ingår i: JOURNAL OF EXPERIMENTAL ZOOLOGY. - : WILEY-LISS. - 0022-104X. ; 290:5, s. 504-516
-
Tidskriftsartikel (refereegranskat)abstract
- The chromosomes were studied throughout meiotic prophase by electron microscopy of surface-spread oocytes from one XX, four X*X, and three X*Y female wood lemmings, Myopus schisticolor. The X* chromosome had originated from X by a deletion and an inversio
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Jönsson, Ingemar, et al.
(författare)
-
Experimentally induced anhydrobiosis in the tardigrade Richtersius coronifer: Phenotypic factors affecting survival
- 2002
-
Ingår i: Journal of Experimental Zoology. - : Wiley. - 0022-104X. ; 293:6, s. 578-584
-
Tidskriftsartikel (refereegranskat)abstract
- The ability of some animal taxa (e.g., nematodes, rotifers, and tardigrades) to enter an ametabolic (cryptobiotic) state is well known. Nevertheless, the phenotypic factors affecting successful anhydrobiosis have rarely been investigated. We report a laboratory study on the effects of body size, reproductive condition, and energetic condition on anhydrobiotic survival in a population of the eutardigrade Richtersius coronifer. Body size and energetic condition interacted in affecting the probability of survival, while reproductive condition had no effect. Large tardigrades had a lower probability of survival than medium-sized tardigrades and showed a positive response in survival to energetic condition. This suggests that energy constrained the possibility for large tardigrades to enter and to leave anhydrobiosis. As a possible alternative explanation for low survival in the largest specimens we discuss the expression of senescence. In line with the view that processes related to ahhydrobiosis are connected with energetic costs we documented a decrease in the size of storage cells over a period of anhydrobiosis, showing for the first time that energy is consumed in the process of anhydrobiosis in tardigrades. (C) 2002 Wiley-Liss, Inc.
|
|
