181 research outputs found
Interactions between above- and belowground organisms modified in climate change experiments
No full textClimate change has been shown to affect ecosystem process rates and community composition, with direct and indirect effects on belowground food webs. In particular, altered rates of herbivory under future climate4 can be expected to influence above–belowground interactions. Here, we use a multifactor, field-scale climate change experiment and independently manipulate atmospheric CO2 concentration, air and soil temperature and drought in all combinations since 2005. We show that changes in these factors modify the interaction between above- and belowground organisms.We use an insect herbivore to experimentally increase aboveground herbivory in grass phytometers exposed to all eight combinations of climate change factors for three years. Aboveground herbivory increased the abundance of belowground protozoans, microbial growth and microbial nitrogen availability. Increased CO2 modified these links through a reduction in herbivory and cascading effects through the soil food web. Interactions between CO2, drought and warming can affect belowground protozoan abundance. Our findings imply that climate change affects aboveground–belowground interactions through changes in nutrient availability
Lysosomal signaling is required for embryonic stem cell differentiation and human development
No full textSelf-renewal and differentiation are the two key properties that characterize stem cells. To initiate differentiation, pluripotent embryonic stem cells (ESC) must be forced out of self-renewal, the transcriptional networks conferring stem cell identity need to be dissolved and lineages must be chosen. Compared to acquisition and maintenance of ESCs pluripotency, the mechanisms driving exit from this cell state are ill defined. Previous work has identified the tumor suppressor Folliculin (Flcn) as a novel gene required for exit from the ESC state during differentiation (Betschinger et al., 2013a). Flcn loss of function in mice is early embryonic lethal consistent with being required for exit from pluripotency in vivo. It has been shown in ESCs that Flcn and two associated proteins, Fnip1 and Fnip2, regulate the subcellular localization of the basic helix-loop-helix transcription factor Tfe3. In wildtype ESCs, Tfe3 is ubiquitously detected in the nucleus and cytoplasm. Upon ESC differentiation, Tfe3 is excluded from the nucleus whereas Flcn loss of function ESCs harbor constitutive nuclear Tfe3 localization and are, consequentially, impaired in differentiation. Consistently, ectopic nuclear Tfe3 similarly inhibits ESC differentiation. Recently, Flcn has been identified in a metabolic pathway leading to the activation of the mTORC1 complex in an amino-acid sensing dependent manner after nutrient starvation (Tsun et al., 2013). However, mTORC1 activity is not required for ESC differentiation.
To gain insights into the regulation of this process, we conducted a genome-wide CRISPR/Cas9 screen in ESCs that aimed to identify genes that, similar to Flcn, are required for the maintenance of stem cell identity upon long term exposure to differentiation stimuli. Although molecularly related to amino-acid sensing dependent mTORC1 regulation, our findings suggest an alternate mode of action that may be founded in the non-starving nature of ESC differentiation. In addition, we show in ESC that the lysosome regulates the assembly of a Flcn-Tfe3 axis, whose impairment induces an embryonic developmental arrest.
Additionally, in a collaborative work with human geneticists, we identified five Tfe3 point mutations in a human syndrome called hypomelanosis of Ito. Symptoms associated with this developmental disorder include severe intellectual disability, coarse facial features, frontonasal dysplasia, obesity, epilepsy and growth retardation, suggesting a pleiotropic developmental disorder. To understand the developmental nature of the disease, we tested these mutations in ESCs and we found them causing defects in exit from self-renewal and nuclear Tfe3 accumulation.
Taken together, the work presented in this thesis has allowed the identification of the lysosome as a critical organelle required for the control of the exit from pluripotency and indicates that lysosomal recruitment of Tfe3 is required for its inactivation, which is a crucial step to enable normal developmental progression
Multi-factor climate change effects on insect herbivore performance
No full textThe impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO2, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split-plot with 6 blocks × 2 levels of CO2 × 2 levels of warming × 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea suturalis Thomson), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO2 (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under the drought treatment, and there was a three-way interaction between time, CO2, and drought. Survival was lowest when drought, warming, and elevated CO2 were combined. Effects of climate change drivers depended on other co-acting factors and were mediated by changes in plant secondary compounds, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers
Assessing the anti-microbial activity of a copper-free foot bath solution: Preliminary results
No full textDigital dermatitis (DD) is the main reason for the lameness in dairy cows (Reichenbach, Jones & Bewley, 2017). Digital dermatitis is caused by different types of bacteria species and results in lesions, mainly on the heels of the rear feet and it affects the skin and causes inflammation in the feet (Palmer and O’ Connell, 2015). Digital Dermatitis affects 70 to 95% of North American farms (Solano, Barkema, Pickel& Orsel, 2017). Foot bath treatments are most commonly used to prevent DD, because treating each animal individually is labour intensive. Data shows that about 38.9% farmers in small operations and 80.8% in large operations use footbath to control DD (Reichenbach,Jones, & Bewley, 2017). Copper is a staple solution for foot baths (Thompson 2015), but copper can be an environmental hazard (Laven 2006). Copper-free options are available, but these have not been fully evaluated (Thompson 2015).This poster won the Vice Provost and Associate Vice-President, Academic award (2020). Advisor: Dr. Renee Prasad, Department of Agriculture
Synergising the creation of knowledge processes in a Technical and Vocational Education and Training College with industry demands for sustainable lecturer learning environments
No full textThesis (Ph.D.(Education))--University of the Free State, 2023This study explores mechanisms or means by which knowledge-creation processes could be synergised for sustainable lecturer learning environments. The study assumes that lecturers are better positioned to contribute to the sustenance of the business/industry and colleges. The colleges because they are sites whereby employees and employers are prepared. The college plays a vital role only if lecturers are adequately knowledgeable and do so diligently. And competently that graduates are entirely and better prepared for workplace demands. The purpose is to contribute to the debate or discussion on optimising the utilisation of limited resources for human capital training. In particular, the inequities still lingering from the apartheid past. For instance, in this case, a TVET College has one campus in a relatively big area (Metropolitan area) and two other campuses. In what is known as formerly homelands. As a result, it is sufficient to say that there are disparities in resources. The point is how a college pulls together the resources in providing. The output is more significant than the sum – so some colleges can address challenges, particularly Lecturer development, which is often criticised for being limited. This study used the bricolage methodology to attain a critical perspective on all the issues, primarily when qualitative data is generated. This study is the sub-project of the mega study. Therefore, there are bound to be power differentials in a study like this. Bricolage assisted in exploring social injustice-related issues and power differentials Ideologically and Methodologically. Thus, bricolage guides this study. The methods relied upon were focus group discussions with lecturers and a business owner and senior manager. Furthermore, this considered the survey results because this college formed part of the study of the mega project. Through the mega project, there were seminars and seminar reflections
Eternal Livingness in Love: Refleksi Teologi Kristen terhadap Pemikiran David Benatar mengenai Kematian dan Kekekalan
No full textAbstract. David Benatar's philosophical views on death and immortality seem to contradict Christian theology. However, Benatar argues that if theists take a closer look at his views, there is no significant contradiction between the two. Based on this argument, this article aimed to reflect Benatar's view of death and immortality from the point of view of Christian theology. Conducted by Jürgen Moltmann's theological views on death and immortality, this article attested that there is no significant contradiction between Benatar's philosophical views and Moltmann's Christian theology on death and immortality and can even contribute to one another. This conclusion also echoes that philosophy and theology can go hand in hand without contradicting each other.Abstrak. Pandangan filosofis David Benatar tentang kematian dan kekekalan tampaknya bertentangan dengan teologi Kristen. Namun, Benatar berpendapat bahwa jika para teis melihat lebih cermat, tidak ada kontradiksi yang signifikan di antara keduanya. Berdasarkan argumen Benatar tersebut, artikel ini bertujuan untuk merefleksikan pandangan Benatar tentang kematian dan kekekalan dari sudut pandang teologi Kristen. Dengan menggunakan pandangan teologis Jürgen Moltmann tentang kematian dan kekekalan, artikel ini membuktikan bahwa tidak ada pertentangan yang berarti antara pandangan filosofis Benatar dan teologi Kristen Moltmann mengenai kematian dan kekekalan, bahkan keduanya dapat berkontribusi satu sama lain. Kesimpulan ini juga menegaskan bahwa filsafat dan teologi dapat berjalan beriringan satu sama lain
Factors affecting the use of open source software in tertiary education institutions
No full textOpen Source Software (OSS) is software that has been released under a license which requires the distribution of the software’s source code with any binaries. It is often available at no cost and is mostly supported by developers providing their services for free. Considerable interest has been shown in OSS by tertiary education institutions (TEIs) because of the promise of a reduced total cost of ownership of the software, potentially better support, freedom from vendor lock–in, ability to tailor the software and pedagogic benefits of being able to view the source code. To find out the extent of use of OSS by TEIs in Australia, New Zealand and the United Kingdom, a survey was sent out to technical personnel at all TEIs in these countries. The results of the survey show that OSS is already being used by all TEIs who responded to the survey and that the major reasons for this was lower Total Cost of Ownership and freedom from software vendor dependence. It is clear however that the majority of the OSS software being used is in server infrastructure with a lesser amount being used on normal desktop machines
Changing the Rules of the Game: Rule-Adjustment Mechanics in Tabletop Games
No full textIn most tabletop games, the rules of the game are typically defined and agreed upon by all players before play begins. However, there are some games which allow players to change the rules of the game during play. Through an exploratory design research methodology, the author defines a rule-adjustment mechanic and explores its application across a wide variety of tabletop games. The research culminates in the design and development of several game prototypes including SMOG, an educational game focused on passing environmental regulations. The paper concludes with a discussion around the creative, strategic, and educational opportunities that rule-adjustment mechanics offer players and a set of recommendations for educators and game designers looking to integrate such mechanics into their work.S.M
SATB2‐LEMD2 interaction links nuclear shape plasticity to regulation of cognition‐related genes
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