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- Caspillo, Nasim Reyhanian, 1982-
(författare)
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Hitting the mark : studies of alterations in behaviour and fertility in ethinyl estradiol-exposed zebrafish and search related biomarkers
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we have analysed the effects of EE2 on non-reproductive behaviours and fertility. We have showed that two doses of EE2 in male adult short-term exposures evokes opposite behaviours in the novel tank test. A lower dose induced increased bottom-dwelling, a sign of increased anxiety and a higher dose increased surface-dwelling, which would likely expose themselves to predation in a natural environment. Increased shoaling was observed in both exposures, possibly affecting feeding and reproduction opportunities. Fertility analysis of these fish demonstrated a complete inhibition of spawning in the highest dose group. To investigate mechanisms behind the spawning failure, we examined expression levels of genes involved in zebrafish sex differentiation and maintenance of gonadal function. We found downregulated transcription levels of male-predominant genes, suggesting a demasculinization of the testes contributing to functional sterility in these fish. We have demonstrated that non-reproductive behaviour in zebrafish is highly sensitive to EE2 exposure during development. After exposing male and female zebrafish to low doses of EE2 followed by remediation in clean water until adulthood, the fish displayed increased anxiety and shoaling behaviour, demonstrating persistent effects of EE2. Furthermore, behavioural effects were transferred to their progeny. Decreased fertilisation success of the developmentally exposed fish was observed in both sexes when mated to untreated animals of the opposite sex. These fertility effects persisted although the fish had a long remediation period, implying likely reduced fitness of fish populations in aquatic environments. Based on our findings on non-reproductive behaviours and fertility, we performed RNAsequencing analysis of the brain and testes in order to investigate possible biological mechanisms behind the persistent effects. There is a need for biomarkers allowing detection of both reversible and irreversible effects in animals exposed to estrogenic substances, hopefully contributing to better risk assessments for EDCs. Results from RNA-sequencing would serve as a basis for continued studies in pursuit of potential biomarkers.
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- Lättman, Håkan, et al.
(författare)
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At what age becomes Cliostomum corrugatum adult?
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The objective was to investigate at what the age specimen of Cliostomum corrugatum become fertile in order to estimate the time span between the meiosis events. The species has its main distribution in Europe but has also been found on the west coast of British Columbia and is red listed, e.g., in Sweden (nearly threatened), Denmark, Germany and England. In the province of Östergötland, southern Sweden it is most frequent on old Quercus robur trees in open oak forest or meadows. I may also be found on other deciduous trees as Ulmus and Fraxinus species. It is mainly groving on the flat terminal parts of the rough bark of the tree trunks and not on the sides of the cracks. Cliostomum corrugatum does not grow on young oak trees. The smallest tree trunk diameter with Cliostomum corrugatum was is 0.65 m, a tree of at least 100 years of age. On two localities in Östergötland all oaks were studied and the size of the trees and the size of the largest thallus of Cliostomum corrugatum were recorded. Out of this data the size of how small a tree can possibly be for hosting Cliostomum corrugatum. This estimate was compared with the size of the smallest thalli with apothecia and the size of trees on which these appeared. With knowledge of the peripheral secondary growth of oaks it was possible to estimate the age of the youngest fertile Cliostomum corrugatum to about 30 years. Thus, equal to the time span between two meiosis events.
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- Lättman, Håkan, et al.
(författare)
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Generation time estimated to be 25-30 years in Cliostomum cossugatum (Ach.) Fr.
- 2009
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Ingår i: The Lichenologist. - : Britich Lichen Society. - 0024-2829 .- 1096-1135. ; 41:5, s. 557-559
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Knowledge of spore to spore generation time is extremely important for several reasons. As it is the shortest generation time, it indicates the maximum nucleotide substitution rate over time and provides a rate limit for the evolution of a species. In population genetics most calculations involving time use ‘generations’ as the unit of measurement and in order to convert these ‘generations’ into ‘years’, knowledge of generation time is needed but rarely available. Knowledge of generation time may also be essential for conservation purposes and assessments of migration history. This knowledge also makes it possible to estimate both the age of a population and also to determine to what extent a population represents the genetic diversity of a species (Rosenberg & Nordborg 2002). In this paper we present a method for assessing generation length for lichens using Cliostomum corrugatum (Ach.) Fr. as an example. This lichen was selected for investigation because it is restricted to forests with long temporal continuity (Lättman et al. 2009) and information on generation time is essential to estimate the rate of dispersal at the landscape level.
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