Reciprocal regulation of the basic helix-loop-helix/Per-Arnt-Sim partner proteins, Arnt and Arnt2, during neuronal differentiation

Basic helix–loop–helix/Per–Arnt–Sim (bHLH/PAS) transcription factors function broadly in development, homeostasis and stress response. Active bHLH/PAS heterodimers consist of a ubiquitous signal-regulated subunit (e.g., hypoxia-inducible factors, HIF-1α/2α/3α; the aryl hydrocarbon receptor, AhR) or tissue-restricted subunit (e.g., NPAS1/3/4, Single Minded 1/2), paired with a general partner protein, aryl hydrocarbon receptor nuclear translocator (Arnt or Arnt2). We have investigated regulation of the neuron-enriched Arnt paralogue, Arnt2. We find high Arnt/Arnt2 ratios in P19 embryonic carcinoma cells and ES cells are dramatically reversed to high Arnt2/Arnt on neuronal differentiation. mRNA half-lives of Arnt and Arnt2 remain similar in both parent and neuronal differentiated cells. The GC-rich Arnt2 promoter, while heavily methylated in Arnt only expressing hepatoma cells, is methylation free in P19 and ES cells, where it is bivalent with respect to active H3K4me3 and repressive H3K27me3 histone marks. Typical of a ‘transcription poised’ developmental gene, H3K27me3 repressive marks are removed from Arnt2 during neuronal differentiation. Our data are consistent with a switch to predominant Arnt2 expression in neurons to allow specific functions of neuronal bHLH/PAS factors and/or to avoid neuronal bHLH/PAS factors from interfering with AhR/Arnt signalling.Nan Hao, Veronica L. D. Bhakti, Daniel J. Peet and Murray L. Whitela

Mifepristone prevents repopulation of ovarian cancer cells escaping cisplatin-paclitaxel therapy

<p>Abstract</p> <p>Background</p> <p>Advanced ovarian cancer is treated with cytoreductive surgery and combination platinum- and taxane-based chemotherapy. Although most patients have acute clinical response to this strategy, the disease ultimately recurs. In this work we questioned whether the synthetic steroid mifepristone, which as monotherapy inhibits the growth of ovarian cancer cells, is capable of preventing repopulation of ovarian cancer cells if given after a round of lethal cisplatin-paclitaxel combination treatment.</p> <p>Methods</p> <p>We established an <it>in vitro</it> approach wherein ovarian cancer cells with various sensitivities to cisplatin or paclitaxel were exposed to a round of lethal doses of cisplatin for 1 h plus paclitaxel for 3 h. Thereafter, cells were maintained in media with or without mifepristone, and short- and long-term cytotoxicity was assessed.</p> <p>Results</p> <p>Four days after treatment the lethality of cisplatin-paclitaxel was evidenced by reduced number of cells, increased hypodiploid DNA content, morphological features of apoptosis, DNA fragmentation, and cleavage of caspase-3, and of its downstream substrate PARP. Short-term presence of mifepristone either enhanced or did not modify such acute lethality. Seven days after receiving cisplatin-paclitaxel, cultures showed signs of relapse with escaping colonies that repopulated the plate in a time-dependent manner. Conversely, cultures exposed to cisplatin-paclitaxel followed by mifepristone not only did not display signs of repopulation following initial chemotherapy, but they also had their clonogenic capacity drastically reduced when compared to cells repopulating after cisplatin-paclitaxel.</p> <p>Conclusions</p> <p>Cytostatic concentrations of mifepristone after exposure to lethal doses of cisplatin and paclitaxel in combination blocks repopulation of remnant cells surviving and escaping the cytotoxic drugs.</p

Exploring the link between otolith growth and function along the biological continuum in the context of ocean acidification

Oceans are acidifying as atmospheric CO2 is drawn down. This process, known as ocean acidification (OA), is well known and documented. Over the next 100 years, pH of the surface ocean is projected to decrease by up to 0.35 units. This CO2 draw down has a direct effect on dissolved inorganic carbon (DIC) balance in the ocean. OA is expected to impact calcifying organisms that rely on constituencies of the DIC system, specifically carbonate ion [CO32-]. It is clear that externally calcified structures, such as coral skeletons, bivalve shells, etc., will be significantly affected as pH, and consequently [CO32− ], of the oceans decline. What is unclear, however, is how these changes will impact internally calcified structures, such as earstones (otoliths) of teleost fish. This dissertation examines the impacts of OA on otolith mineralization in larval reef fish (Amphiprion clarkiiand A. frenatus ). This research included the development of a laboratory controller system for control of experimental aquaria pH through pCO2 dosing, exposure of larvae from hatch to settlement under various pCO2 treatments and evaluation of otolith structure and morphology across treatments within a single genus. No standard method for pH-stat CO2 dosing controllers existed prior to this study. Incorporating low-cost, flexible hardware allowed high precision and accuracy pH controllers to be designed and implemented. Following system stability studies, we found that our system performed at or beyond the level of control exhibited in the literature. Two species of clownfish, Amphiprion clarkii and A. frenatus, were exposed to different pCO2 conditions, reared to settlement and otoliths extracted and studied. I found that the sagittae (largest of the 3 otolith types) of both species exhibited circularity changes towards more oblong otoliths under increased pCO2. For A. clarkii, I found a significant negative relation between pCO 2 and lapilli otolith circularity, indicating a shift toward more circular lapilli under increased pCO2. Since lapilli are critical to gravisensing in teleosts these results explain my anecdotal observations that, at high pCO2, larvae exhibited lethargic, uncoordinated swim patterns. The core development of otoliths (sagittae, lapilli, and asterisci) from both species was analyzed using SEM imagery. Otolith images were scored by 6 independent readers for core development (poorly developed to well-developed). Otolith scores were regressed against aragonite saturation state (ΩAr). Results showed significant and strong relations between ΩAr and development score, indicating a shift toward protruding, unorganized crystal clusters within the core under high pH/low ΩAr. This research is the first to comprehensively examine the impact of OA on the otolith system in larval fish. The research revealed direct impacts on otolith structure and morphology as well as mineralogy. These changes will directly impact survival of the larvae. It remains unknown whether the otolith system recovers post-settlement or whether the anecdotal observations on swimming behavior are directly related to otolith deformation. Future research will include exploration of these relations across genera as well as more deeply examine the recovery of the system and behavioral impacts of otolith deformation across life stages

Standing Out in the Academic LIS Job Market: An Interactive Panel Not Just for Doctoral Students

This proposal builds on the previous successes of the interactive panels sponsored by the ASIS&T Special Interest Group on Education (SIG ED) at the 2017, 2015, 2013, 2012, and 2011 annual meetings. The all-new 2020 panel features faculty in various stages of their academic careers, including a relatively new assistant professor, one who has just completed the tenure process, two associate professors, a full professor, and a professor emerita. The panelists are prepared to address audience questions on topics such as the traditional academic job market, alternative career paths including post-doctoral opportunities, development of personal research agendas, challenges of online instruction (Sithole et al., International Journal of Online Pedagogy and Course Design, 2019, 9, 62–77), as well as the challenges and disruption caused in higher education due to the COVID-19 situation (Amour, Coronavirus News Roundup for April 21, 2020). The panel discussion will focus around the academic job market and how applicants can present themselves in the best light depending upon the type of position sought. Doctoral students will gain valuable insights on finishing their dissertation, weighing postdoctoral opportunities, and preparing for their first academic position. The panel will be useful not only to doctoral students but also to postdocs, adjuncts, and assistant-to- associate-to-full professors, as the panelists share their insights and experience through various career stages

Secondary school teachers’ attitudes to information literacy: a study of a questionnaire validity

The objective of this paper is to determine the validity and reliability of an originally created questionnaire as an instrument to develop an understanding of secondary school teachers’ knowledge on information literacy and practices implemented with developing student’s information literacy skills in Hungary, Poland, and Lithuania. This research will support a research project that aims the harmonisation of various theories of information literacy with the proper application of information literacy to public (K12) education. This paper presents a pilot survey among Lithuanian teachers on a sample of 102 participants in the spring of 2018. We gathered data for this study using a computer-assisted web interviewing (CAWI) technique and administered an online survey using the 1KA.SI web survey tool. The collected data was analysed by IBM SPSS Statistics ver. 19. Internal consistency of the questionnaire measured by Cronbach’s alpha coefficient. Scale and construct validity evaluated using Principal components analysis with Varimax Rotation. The authors feel assured in using the questionnaire for the wider scope survey

An In Vitro Perfusion System to Enhance Outflow Studies in Mouse Eyes.

Purpose: The molecular mechanisms controlling aqueous humor (AQH) outflow and IOP need much further definition. The mouse is a powerful system for characterizing the mechanistic basis of AQH outflow. To enhance outflow studies in mice, we developed a perfusion system that is based on human anterior chamber perfusion culture systems. Our mouse system permits previously impractical experiments. Methods: We engineered a computer-controlled, pump-based perfusion system with a platform for mounting whole dissected mouse eyes (minus lens and iris, ∼45% of drainage tissue is perfused). We tested the system\u27s ability to monitor outflow and tested the effects of the outflow-elevating drug, Y27632, a rho-associated protein kinase (ROCK) inhibitor. Finally, we tested the system\u27s ability to detect genetically determined decreases in outflow by determining if deficiency of the candidate genes Nos3 and Cav1 alter outflow. Results: Using our system, the outflow facility (C) of C57BL/6J mouse eyes was found to range between 7.7 and 10.4 nl/minutes/mm Hg (corrected for whole eye). Our system readily detected a 74.4% Y27632-induced increase in C. The NOS3 inhibitor L-NG-nitroarginine methyl ester (L-NAME) and a Nos3 null mutation reduced C by 28.3% and 35.8%, respectively. Similarly, in Cav1 null eyes C was reduced by 47.8%. Conclusions: We engineered a unique perfusion system that can accurately measure changes in C. We then used the system to show that NOS3 and CAV1 are key components of mechanism(s) controlling outflow. Invest Ophthalmol Vis Sci 2016 Oct 1; 57(13):5207-5215