title: Calcium modeling and TMS variability

authors: Wilson, Marcus T.

subjects: Modeling

abstract: • We have modelled Calcium-dependent plasticity with a Neural Field scheme
• Developed the approach further to modelling MEPs
• Modelling can reproduce MEP ranges from submillivolt to ~10 mV
• Modelling can reproduce both potentiation and depression following cTBS and iTBS
• In terms of variability of MEPs, the following are important:
• TMS-to-e coupling strength (parameter μ)
• Excitatory-to-excitatory coupling strength wee
• Number of pulses / time since stimulation
• Include reporting of actual thresholds when %RMT is used

text: Calcium modeling and TMS variability • We have modelled Calcium-dependent plasticity with a Neural Field scheme
• Developed the approach further to modelling MEPs
• Modelling can reproduce MEP ranges from submillivolt to ~10 mV
• Modelling can reproduce both potentiation and depression following cTBS and iTBS
• In terms of variability of MEPs, the following are important:
• TMS-to-e coupling strength (parameter μ)
• Excitatory-to-excitatory coupling strength wee
• Number of pulses / time since stimulation
• Include reporting of actual thresholds when %RMT is used

year: 2023

title: Pituitary mRNA expression of FSH and LH in yellowbelly flounder (Rhombosolea leporina)

authors: Curtis, Robert

subjects: yellowbelly flounder

abstract: Recent interest has been expressed in cultivating the native, yellowbelly flounder (Rhombosolea leporina). This is largely due to its high market and cultural value. Currently, there is little research on this species, both in an aquaculture setting and from an ecological perspective. This study focused on assessing pituitary mRNA expression of two gonadotropin-beta subunit genes, follicle-stimulating hormone (fshβ) and luteinising hormone (lhβ), in wild-caught yellowbelly flounder, to better understand captive reproduction for aquaculture.

The first study characterised the expression of both pituitary fshβ and lhβ in wild-caught yellowbelly flounder in different stages of ovarian development: 1) previtellogenic (PVO), 2) early vitellogenic (EVit), 3) vitellogenic (VIT), and 4) final oocyte maturation (FOM). Both genes showed significant increases in expression between stages 1 and 4. The expression patterns of both pituitary fshβ and lhβ were similar, with a trend of increasing levels across all ovarian stages to peak at stage 4. However, peak expression levels were much greater in fshβ. This is unexpected compared to typical fish models, where pituitary lhβ expression is often many-fold greater than fshβ during oocyte maturation. The reason for this apparent anomaly in peak expression levels is unknown. However, the general profile of increasing levels of co-expressed pituitary fshβ and lhβ throughout oogenesis likely reflects the multiple-batch group synchronous ovarian development found in yellowbelly flounder.

The second study focused on quantifying fshβ and lhβ expression over a five-day period following the injection of gonadotropin-releasing hormone analogue (GnRHa). Each female yellowbelly flounder was assigned to one of four treatment groups: 25 μg/kg, 50 μg/kg, 100 μg/kg, or a control group (0 μg/kg). Although there were no statistically significant increases in fshβ or lhβ expression from day 1 to day 5, an upward trend in both lhβ and fshβ expression was observed in fish treated with 25 μg/kg of GnRHa. Similarly, an increasing trend in lhβ expression was observed in fish treated with 50 μg/kg of GnRHa. GnRHa-treated fish accounted for the highest number of individuals entering FOM, comprising 87% of all fish that reached this stage. Additionally, 85% of all fish treated with GnRHa progressed to early maturation (EM) or further. Interestingly, the 100 μg/kg GnRHa treatment resulted in a downward trend of both fshβ and lhβ expression on both days 1 and 5 post-treatment. Despite this, the 100 μg/kg GnRHa treatment exhibited the joint-highest proportion of oocytes reaching maturity (33.3%) and had 90% of individuals reaching the early migratory (EM) stage or beyond. However, none of the fish were observed to ovulate over the 5-day experimental period.

text: Pituitary mRNA expression of FSH and LH in yellowbelly flounder (Rhombosolea leporina) Recent interest has been expressed in cultivating the native, yellowbelly flounder (Rhombosolea leporina). This is largely due to its high market and cultural value. Currently, there is little research on this species, both in an aquaculture setting and from an ecological perspective. This study focused on assessing pituitary mRNA expression of two gonadotropin-beta subunit genes, follicle-stimulating hormone (fshβ) and luteinising hormone (lhβ), in wild-caught yellowbelly flounder, to better understand captive reproduction for aquaculture.

The first study characterised the expression of both pituitary fshβ and lhβ in wild-caught yellowbelly flounder in different stages of ovarian development: 1) previtellogenic (PVO), 2) early vitellogenic (EVit), 3) vitellogenic (VIT), and 4) final oocyte maturation (FOM). Both genes showed significant increases in expression between stages 1 and 4. The expression patterns of both pituitary fshβ and lhβ were similar, with a trend of increasing levels across all ovarian stages to peak at stage 4. However, peak expression levels were much greater in fshβ. This is unexpected compared to typical fish models, where pituitary lhβ expression is often many-fold greater than fshβ during oocyte maturation. The reason for this apparent anomaly in peak expression levels is unknown. However, the general profile of increasing levels of co-expressed pituitary fshβ and lhβ throughout oogenesis likely reflects the multiple-batch group synchronous ovarian development found in yellowbelly flounder.

The second study focused on quantifying fshβ and lhβ expression over a five-day period following the injection of gonadotropin-releasing hormone analogue (GnRHa). Each female yellowbelly flounder was assigned to one of four treatment groups: 25 μg/kg, 50 μg/kg, 100 μg/kg, or a control group (0 μg/kg). Although there were no statistically significant increases in fshβ or lhβ expression from day 1 to day 5, an upward trend in both lhβ and fshβ expression was observed in fish treated with 25 μg/kg of GnRHa. Similarly, an increasing trend in lhβ expression was observed in fish treated with 50 μg/kg of GnRHa. GnRHa-treated fish accounted for the highest number of individuals entering FOM, comprising 87% of all fish that reached this stage. Additionally, 85% of all fish treated with GnRHa progressed to early maturation (EM) or further. Interestingly, the 100 μg/kg GnRHa treatment resulted in a downward trend of both fshβ and lhβ expression on both days 1 and 5 post-treatment. Despite this, the 100 μg/kg GnRHa treatment exhibited the joint-highest proportion of oocytes reaching maturity (33.3%) and had 90% of individuals reaching the early migratory (EM) stage or beyond. However, none of the fish were observed to ovulate over the 5-day experimental period.

year: 2025

title: Phytoplankton nutrient limitation in Lake Rotorua

authors: Tempero, Grant Wayne

abstract: Lake Rotorua is one of 12 lakes jointly managed by the Rotorua Lakes Council, Te Arawa Lakes Trust and the Bay of Plenty Regional Council under the Rotorua Te Arawa Lakes Programme. The lake is currently classified as eutrophic and a Trophic Lake Index (TLI) value of 4.2 has been set as an integrated target for lake water quality. A number of catchment and lake management strategies have been implemented to achieve the targeted TLI including land use changes, wetland enhancement, lake weed harvesting, sediment detainment bunds, sewage reticulation and alum dosing. Alum (aluminium sulphate) is commonly applied to freshwater and wastewater systems to remove phosphorus, reducing its availability for phytoplankton growth. The initiation of alum dosing to the Utuhina Stream in 2006 and the Puarenga Stream in 2010 was associated with a significant decline in water column dissolved reactive phosphorus (DRP) and improvements in water quality of Lake Rotorua. 
The use of alum to control external and internal phosphorus loading has been identified as key component in the restoration of Lake Rotorua and recently observed improvements in water quality suggest that the lake could be transitioning to a more phosphorus limited state. Determination of phytoplankton nutrient limitation in Lake Rotorua was identified as a priority through the 2017 Plan Change 10 Science Review. An initial seasonal nutrient limitation study was carried out in 2019 with nutrient limitation assays conducted at 3-monthly intervals over the course of the year. Nitrogen limitation was indicated for the March assay and nutrient co-limitation for the December period, but results for the winter and spring periods were inconclusive. There has also been increasing recognition that nutrient availability in limnetic systems may vary in response to seasonal changes in external and external loading and even to isolated storm events. 
The University of Waikato was contracted to investigate potential changes in nutrient limitation within Lake Rotorua at sub-monthly time-scales, and to determine if alum dose rates could be optimised to take advantage of periods of phosphorus limitation. Phytoplankton nutrient limitation growth assays were conducted on a fortnightly basis from mid-October 2020 to May 2021. In addition to determination of lake surface nutrient and chlorophyll a concentrations, triplicate 1 L phytoplankton samples were spiked with either phosphorus (0.1 mg-P L⁻¹), nitrogen (1 mg-N L⁻¹) or phosphorus (0.1 mg-P L⁻¹) and nitrogen (1 mg-N L⁻¹) and incubated for 5-days under a single light intensity of 100 μmol m⁻²s⁻¹ PAR at lake surface temperature and photoperiod. Phytoplankton growth responses were measured as comparative chlorophyll a, comparative biomass and net biomass growth. Summarised results from the 16 assays along with the predicted nutrient state from the stoichiometric mass ratio of TN:TP are presented in the table below. 
Under the test conditions nitrogen limitation was indicated for most of the summer months (December–March) and nutrient co-limitation during the spring and late autumn. Only short (~2 weeks) periods of P-limitation were observed, one of which was associated with an intensive storm event at the end of March. These seasonal fluctuations in nitrogen and phosphorus supply are similar to those observed in other temperate limnetic systems. In the spring, external nitrogen and phosphorus loading is high, then decline in the summer as rainfall and associated inflows wane. During the summer, internal loading becomes more important in polymictic lakes due to repeated internal nutrient cycling from stratification and mixing events. This results in phosphorus limitation in the spring, transitioning to nitrogen limitation or colimitation (primarily nitrogen) in the summer, and then returning to phosphorus/colimitation during the winter due to increased nitrogen-loading from the catchment from increased catchment discharge. 
Due to the modest periods of phosphorus limitation indicated by the assays, there appears to be little potential for optimisation of alum dose rates in order capitalise on natural periods of phosphorus limitation. Further, changes in phytoplankton community composition and abundance appear to be more strongly driven by physical environmental factors such as temperature, light and wind speed, than nutrient availability. Although alum dosing is effective in removing DRP from the Utuhina and Puarenga inflows, its assumed effectiveness in reducing internal phosphorus loading in Lake Rotorua requires further evaluation.

text: Phytoplankton nutrient limitation in Lake Rotorua Lake Rotorua is one of 12 lakes jointly managed by the Rotorua Lakes Council, Te Arawa Lakes Trust and the Bay of Plenty Regional Council under the Rotorua Te Arawa Lakes Programme. The lake is currently classified as eutrophic and a Trophic Lake Index (TLI) value of 4.2 has been set as an integrated target for lake water quality. A number of catchment and lake management strategies have been implemented to achieve the targeted TLI including land use changes, wetland enhancement, lake weed harvesting, sediment detainment bunds, sewage reticulation and alum dosing. Alum (aluminium sulphate) is commonly applied to freshwater and wastewater systems to remove phosphorus, reducing its availability for phytoplankton growth. The initiation of alum dosing to the Utuhina Stream in 2006 and the Puarenga Stream in 2010 was associated with a significant decline in water column dissolved reactive phosphorus (DRP) and improvements in water quality of Lake Rotorua. 
The use of alum to control external and internal phosphorus loading has been identified as key component in the restoration of Lake Rotorua and recently observed improvements in water quality suggest that the lake could be transitioning to a more phosphorus limited state. Determination of phytoplankton nutrient limitation in Lake Rotorua was identified as a priority through the 2017 Plan Change 10 Science Review. An initial seasonal nutrient limitation study was carried out in 2019 with nutrient limitation assays conducted at 3-monthly intervals over the course of the year. Nitrogen limitation was indicated for the March assay and nutrient co-limitation for the December period, but results for the winter and spring periods were inconclusive. There has also been increasing recognition that nutrient availability in limnetic systems may vary in response to seasonal changes in external and external loading and even to isolated storm events. 
The University of Waikato was contracted to investigate potential changes in nutrient limitation within Lake Rotorua at sub-monthly time-scales, and to determine if alum dose rates could be optimised to take advantage of periods of phosphorus limitation. Phytoplankton nutrient limitation growth assays were conducted on a fortnightly basis from mid-October 2020 to May 2021. In addition to determination of lake surface nutrient and chlorophyll a concentrations, triplicate 1 L phytoplankton samples were spiked with either phosphorus (0.1 mg-P L⁻¹), nitrogen (1 mg-N L⁻¹) or phosphorus (0.1 mg-P L⁻¹) and nitrogen (1 mg-N L⁻¹) and incubated for 5-days under a single light intensity of 100 μmol m⁻²s⁻¹ PAR at lake surface temperature and photoperiod. Phytoplankton growth responses were measured as comparative chlorophyll a, comparative biomass and net biomass growth. Summarised results from the 16 assays along with the predicted nutrient state from the stoichiometric mass ratio of TN:TP are presented in the table below. 
Under the test conditions nitrogen limitation was indicated for most of the summer months (December–March) and nutrient co-limitation during the spring and late autumn. Only short (~2 weeks) periods of P-limitation were observed, one of which was associated with an intensive storm event at the end of March. These seasonal fluctuations in nitrogen and phosphorus supply are similar to those observed in other temperate limnetic systems. In the spring, external nitrogen and phosphorus loading is high, then decline in the summer as rainfall and associated inflows wane. During the summer, internal loading becomes more important in polymictic lakes due to repeated internal nutrient cycling from stratification and mixing events. This results in phosphorus limitation in the spring, transitioning to nitrogen limitation or colimitation (primarily nitrogen) in the summer, and then returning to phosphorus/colimitation during the winter due to increased nitrogen-loading from the catchment from increased catchment discharge. 
Due to the modest periods of phosphorus limitation indicated by the assays, there appears to be little potential for optimisation of alum dose rates in order capitalise on natural periods of phosphorus limitation. Further, changes in phytoplankton community composition and abundance appear to be more strongly driven by physical environmental factors such as temperature, light and wind speed, than nutrient availability. Although alum dosing is effective in removing DRP from the Utuhina and Puarenga inflows, its assumed effectiveness in reducing internal phosphorus loading in Lake Rotorua requires further evaluation.

year: 2022