title: The application of elemental fingerprinting techniques to identify population connectivity using austrovenus stutchburyi recruits

authors: Niemand, Clarisse

subjects: elemental fingerprinting

abstract: The density, distribution and dynamics of benthic bivalve populations are believed to be largely determined by the planktonic larval phase of the life history. As the hard parts of larvae, such as the prodissoconch (larval shell), develop and grow, ambient environmental conditions are recorded as chemical signatures (elemental fingerprints). If the chemical signals of reference sites are known, the larval signatures can be matched to reference sites, hereby reconstructing the origin of the larvae. The collection and identification of larval bivalves is extremely difficult, however, previous studies have shown that the prodissoconch is retained into the juvenile phase, thus enabling juveniles to maintain a record of the larval movement. Before elemental fingerprinting can be used as a larval tracking tool, site specific signatures must be evident in the shells. As a precursor study to test the application of elemental fingerprinting to track bivalve larvae, the presence of spatial variability in shell signatures as well as the scale at which these variations occurred, were established for New Zealand conditions. Furthermore, temporal stability of the shell signatures was explored, as temporal stability is crucial if the signals of shells collected at one time are to be used as predictors of unknown samples collected at a different time.
The venerid bivalve Austrovenus stutchburyi is a common and widespread constituent of New Zealand estuarine communities and were therefore selected as the study species. The chemical signatures of entire Austrovenus stutchburyi shells were examined to determine the inter-site spatial differences in elemental fingerprints of shells and also to characterise the temporal stability of the signatures. Furthermore, shells were ablated at two reference points (the prodissoconch and most recently formed shell material) to determine the intra-shell variation in the chemical signatures. Juvenile individuals were collected from 19 sites in the North Island of New Zealand as part of the whole shell spatial study. One site (in Tauranga Harbour) was examined for the temporal study, whilst four sites were used to compare intra-shell chemical variation. Whole shells were digested and analysed as solution based samples using inductively coupled
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ABSTRACT
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plasma-mass spectrometry (ICP-MS) for the spatial and temporal studies, and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for the point ablation intra-shell variation study.
Results showed that shell concentrations were sufficiently different to yield a classification success of 68% over 19 sites, however the classification success markedly increased as the number of sites included in the analysis decreased (e.g. 12 sites = 75%, 10 sites = 84%, 5 sites = 90%, 3 sites = 95%). Shells were successfully classified across all of the spatial scales that were tested (approximately 10 km to 1150 km). Temporal stability in chemical signatures was observed over a 44 day period. The chemical signatures were not correlated with ambient temperature or salinity, however more vigorous sampling is needed to accurately assess the relationship between shell elemental incorporation and environmental conditions. Intra-shell variation was also observed for some of the shells analysed from two of the four sites. These results were promising and indicated that there may be chemical variations between the larval shells and the more recently formed shell material, thus suggesting the possibility of external recruitment.
The results from this study emphasised the potential for the application of elemental fingerprinting techniques to track and better understand the larval transport and population connectivity for New Zealand invertebrate species, however more research is required before elemental fingerprinting can effectively be applied to New Zealand invertebrate species. With a fundamental understanding of the origin of bivalve recruits, restoration efforts following estuarine disturbance events can be effectively employed.

text: The application of elemental fingerprinting techniques to identify population connectivity using austrovenus stutchburyi recruits The density, distribution and dynamics of benthic bivalve populations are believed to be largely determined by the planktonic larval phase of the life history. As the hard parts of larvae, such as the prodissoconch (larval shell), develop and grow, ambient environmental conditions are recorded as chemical signatures (elemental fingerprints). If the chemical signals of reference sites are known, the larval signatures can be matched to reference sites, hereby reconstructing the origin of the larvae. The collection and identification of larval bivalves is extremely difficult, however, previous studies have shown that the prodissoconch is retained into the juvenile phase, thus enabling juveniles to maintain a record of the larval movement. Before elemental fingerprinting can be used as a larval tracking tool, site specific signatures must be evident in the shells. As a precursor study to test the application of elemental fingerprinting to track bivalve larvae, the presence of spatial variability in shell signatures as well as the scale at which these variations occurred, were established for New Zealand conditions. Furthermore, temporal stability of the shell signatures was explored, as temporal stability is crucial if the signals of shells collected at one time are to be used as predictors of unknown samples collected at a different time.
The venerid bivalve Austrovenus stutchburyi is a common and widespread constituent of New Zealand estuarine communities and were therefore selected as the study species. The chemical signatures of entire Austrovenus stutchburyi shells were examined to determine the inter-site spatial differences in elemental fingerprints of shells and also to characterise the temporal stability of the signatures. Furthermore, shells were ablated at two reference points (the prodissoconch and most recently formed shell material) to determine the intra-shell variation in the chemical signatures. Juvenile individuals were collected from 19 sites in the North Island of New Zealand as part of the whole shell spatial study. One site (in Tauranga Harbour) was examined for the temporal study, whilst four sites were used to compare intra-shell chemical variation. Whole shells were digested and analysed as solution based samples using inductively coupled
ii
ABSTRACT
iii
plasma-mass spectrometry (ICP-MS) for the spatial and temporal studies, and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for the point ablation intra-shell variation study.
Results showed that shell concentrations were sufficiently different to yield a classification success of 68% over 19 sites, however the classification success markedly increased as the number of sites included in the analysis decreased (e.g. 12 sites = 75%, 10 sites = 84%, 5 sites = 90%, 3 sites = 95%). Shells were successfully classified across all of the spatial scales that were tested (approximately 10 km to 1150 km). Temporal stability in chemical signatures was observed over a 44 day period. The chemical signatures were not correlated with ambient temperature or salinity, however more vigorous sampling is needed to accurately assess the relationship between shell elemental incorporation and environmental conditions. Intra-shell variation was also observed for some of the shells analysed from two of the four sites. These results were promising and indicated that there may be chemical variations between the larval shells and the more recently formed shell material, thus suggesting the possibility of external recruitment.
The results from this study emphasised the potential for the application of elemental fingerprinting techniques to track and better understand the larval transport and population connectivity for New Zealand invertebrate species, however more research is required before elemental fingerprinting can effectively be applied to New Zealand invertebrate species. With a fundamental understanding of the origin of bivalve recruits, restoration efforts following estuarine disturbance events can be effectively employed.

year: 2009

title: Targets of Elf5 in Mouse Trophoblast Stem Cells

authors: Deane, Jessica Robyn

subjects: Elf5

abstract: The Placenta is an essential organ for all mammalian embryonic development as it provides the nutritional link between maternal and foetal blood streams. The cells which go on to proliferate and contribute to all the major cell types of the embryo derived placenta have been located to the trophoblast (TE) cells overlying the Inner Cell Mass (ICM) of the embryo. Immortal cell lines have been subsequentially derived from this tissue and called Trophoblast Stem (TS) cells. In parallel with their  in vivo  counterparts they are also reliant on Fibroblast growth factor 4 (FgF4) (Tanaka et al., 1998) and Activin/Nodal signalling (Guzman-Ayala et al., 2004). 

The Ets family transcription factor, Elf5, has been shown to be specifically expressed in the early placental trophoblast and subsequent derived tissues. Mice deficient in Elf5 failed to form a placenta post implantation. Furthermore TS cells were unable to be derived from Elf5 knockout embryos (Donnison et al., 2005). This work suggested that Elf5 plays an essential role in TS cells and their differentiation. The aim of this study was to determine the downstream target genes of Elf5 in mouse TS cells. The target genes of Fgf4 and Activin/Nodal signalling in TS cells were also investigated.  This work is hoped to contribute to an overall greater understanding of the molecular networks underlying TS cell maintenance and to contribute to our knowledge of early placental development. 

Small interfering RNA (siRNA) targeted reduction of Elf5 mRNA expression in mTS cells was achieved using two independent siRNAs; with Elf5 reduction exceeding 80%. The resulting changes in gene expression were measured in order to determine the downstream targets of Elf5. Selected genes known to be important for trophoblast differentiation and maintenance were measured using real-time PCR in a candidate gene approach .Global changes in gene expression as a consequence of Elf5 silencing were measured using an Affymetrix microarray. Global changes in gene expression due to growth factor (Fgf4 and/or Activin) removal were also measured. Expression of 22 genes was changed using either of the Elf5 siRNA oligonucleotides. Of these, 9 were also significantly changed by growth factor removal. Included in this set were Synopl, Hst3st3b1, Cyr61 and Sox2. In the overall analysis, many genes whose expression changed upon loss of Elf5 are known to play important roles in trophectoderm cell specification. Real-time PCR validation agreed closely with the up or down regulation measured using the microarray. This work has thus led to the discovery of sets of Elf5 target genes potentially involved in trophoblast stem cell function and has provided the foundation for future work exploring the molecular pathways of trophoblast development.

text: Targets of Elf5 in Mouse Trophoblast Stem Cells The Placenta is an essential organ for all mammalian embryonic development as it provides the nutritional link between maternal and foetal blood streams. The cells which go on to proliferate and contribute to all the major cell types of the embryo derived placenta have been located to the trophoblast (TE) cells overlying the Inner Cell Mass (ICM) of the embryo. Immortal cell lines have been subsequentially derived from this tissue and called Trophoblast Stem (TS) cells. In parallel with their  in vivo  counterparts they are also reliant on Fibroblast growth factor 4 (FgF4) (Tanaka et al., 1998) and Activin/Nodal signalling (Guzman-Ayala et al., 2004). 

The Ets family transcription factor, Elf5, has been shown to be specifically expressed in the early placental trophoblast and subsequent derived tissues. Mice deficient in Elf5 failed to form a placenta post implantation. Furthermore TS cells were unable to be derived from Elf5 knockout embryos (Donnison et al., 2005). This work suggested that Elf5 plays an essential role in TS cells and their differentiation. The aim of this study was to determine the downstream target genes of Elf5 in mouse TS cells. The target genes of Fgf4 and Activin/Nodal signalling in TS cells were also investigated.  This work is hoped to contribute to an overall greater understanding of the molecular networks underlying TS cell maintenance and to contribute to our knowledge of early placental development. 

Small interfering RNA (siRNA) targeted reduction of Elf5 mRNA expression in mTS cells was achieved using two independent siRNAs; with Elf5 reduction exceeding 80%. The resulting changes in gene expression were measured in order to determine the downstream targets of Elf5. Selected genes known to be important for trophoblast differentiation and maintenance were measured using real-time PCR in a candidate gene approach .Global changes in gene expression as a consequence of Elf5 silencing were measured using an Affymetrix microarray. Global changes in gene expression due to growth factor (Fgf4 and/or Activin) removal were also measured. Expression of 22 genes was changed using either of the Elf5 siRNA oligonucleotides. Of these, 9 were also significantly changed by growth factor removal. Included in this set were Synopl, Hst3st3b1, Cyr61 and Sox2. In the overall analysis, many genes whose expression changed upon loss of Elf5 are known to play important roles in trophectoderm cell specification. Real-time PCR validation agreed closely with the up or down regulation measured using the microarray. This work has thus led to the discovery of sets of Elf5 target genes potentially involved in trophoblast stem cell function and has provided the foundation for future work exploring the molecular pathways of trophoblast development.

year: 2007

title: He Whakaoranga Kia Puta Kia Ora (prepared for Health Research Council of New Zealand)

authors: Kilgour, Jonathan T.

abstract: This research project explored the relationship between cultural connectedness and wellbeing (as a social determinant of health). In particular, the research explored the diverse ways in which tribal members connected with and expressed their Waikatotanga.

text: He Whakaoranga Kia Puta Kia Ora (prepared for Health Research Council of New Zealand) This research project explored the relationship between cultural connectedness and wellbeing (as a social determinant of health). In particular, the research explored the diverse ways in which tribal members connected with and expressed their Waikatotanga.

year: 2015