Retention of Prey Genetic Material by the Kleptoplastidic Ciliate Strombidium cf. basimorphum

Many marine ciliate species retain functional chloroplasts from their photosynthetic prey. In some species, the functionality of the acquired plastids is connected to the simultaneous retention of prey nuclei. To date, this has never been documented in plastidic Strombidium species. The functionality of the sequestered chloroplasts in Strombidium species is thought to be independent from any nuclear control and only maintained via frequent replacement of chloroplasts from newly ingested prey. Chloroplasts sequestered from the cryptophyte prey Teleaulax amphioxeia have been shown to keep their functionality for several days in the ciliate Strombidium cf. basimorphum. To investigate the potential retention of prey genetic material in this ciliate, we applied a molecular marker specific for this cryptophyte prey. Here, we demonstrate that the genetic material from prey nuclei, nucleomorphs, and ribosomes is detectable inside the ciliate for at least 5 days after prey ingestion. Moreover, single-cell transcriptomics revealed the presence of transcripts of prey nuclear origin in the ciliate after 4 days of prey starvation. These new findings might lead to the reconsideration of the mechanisms regulating chloroplasts retention in Strombidium ciliates. The development and application of molecular tools appear promising to improve our understanding on chloroplasts retention in planktonic protists.

Transitioning Nuclear Power Plant Main Control Room From Paper Based Procedures to Computer Based Procedures

The United States (U.S.) has 99 operating Nuclear Power Plants (NPPs). The majority of these were designed and commissioned in the 1970s and 1980s. Plants are modernizing their control systems and main control rooms to be able to continue operating past their original 40-year license agreements. U.S. NPP main control rooms are migrating towards hybrid controls with both digital and analog systems. Digital upgrades, while costly, provide improved reliability, reduced maintenance cost, and the potential for fewer unplanned outages and fewer human errors. U.S. utilities have been slow to embrace computerized procedure system (CBP) research, even though CBPs demonstrate clear operational and human factors benefits. Most of the CBP research has been oriented to new reactor designs or full digital control rooms and is not applicable to the piecemeal modernization approach favored by U.S. plants. Research is needed to examine how CBPs impact operations in hybrid control rooms, and how current paper based procedures can be efficiently migrated to computerized platforms. Work is underway to develop tools and perform the obligatory research needed to design and validate CBPs for modernized U.S. nuclear control rooms.

Qualitative or Quantitative Data for Nuclear Control Room Usability Studies? A Pragmatic Approach to Data Collection and Presentation

Qualitative and quantitative approaches provide alternative, but often incompatible means to answer design questions during the early formative and later summative evaluation phases of the human-system interface design process. Human factors practitioners and researchers should identify which approach best addresses their particular research needs. Nuclear control room studies, particularly those conducted for control room modernization efforts, pose unique challenges. Due to the challenge of sampling large numbers of operators, the interface improvement goals of a usability evaluation, and the limited resources available for study analyses, a traditional quantitative approach is often not feasible or reasonable. Qualitative data provides a more pragmatic means to address design questions early on during the formative stage of the evaluation. Quantitative data can also be useful to bolster the qualitative data by presenting the data in a simple and intuitive graphic to provide evidence for design choices. An example case study using this approach during a formative evaluation study of a turbine control system human-system interface is described in this paper.