Principal Activity Research Articles

Allosteric Communication of the Dimerization and the Catalytic Domain in Photoreceptor Guanylate Cyclase.

Phototransduction in vertebrate photoreceptor cells is controlled by Ca2+-dependent feedback loops involving the membrane-bound guanylate cyclase GC-E that synthesizes the second messenger guanosine-3',5'-cyclic monophosphate. Intracellular Ca2+-sensor proteins named guanylate cyclase-activating proteins (GCAPs) regulate the activity of GC-E by switching from a Ca2+-bound inhibiting state to a Ca2+-free/Mg2+-bound activating state. The gene GUCY2D encodes for human GC-E, and mutations in GUCY2D are often associated with an imbalance of Ca2+ and cGMP homeostasis causing retinal disorders. Here, we investigate the Ca2+-dependent inhibition of the constitutively active GC-E mutant V902L. The inhibition is not mediated by GCAP variants but by Ca2+ replacing Mg2+ in the catalytic center. Distant from the cyclase catalytic domain is an α-helical domain containing a highly conserved helix-turn-helix motif. Mutating the critical amino acid position 804 from leucine to proline left the principal activation mechanism intact but resulted in a lower level of catalytic efficiency. Our experimental analysis of amino acid positions in two distant GC-E domains implied an allosteric communication pathway connecting the α-helical and the cyclase catalytic domains. A computational connectivity analysis unveiled critical differences between wildtype GC-E and the mutant V902L in the allosteric network of critical amino acid positions.

Impact of credit use on crop productivity and gross income of smallholder farmers: a propensity score matching approach

BackgroundAgriculture is Ethiopia’s principal economic activity, employing the vast majority of the population, however, smallholder farmers in the country face long-standing challenges, including low levels of production, low income, and less credit use. This study aimed to analyze the impact of access to credit on crop productivity and income among small-scale farmers in the study area.MethodsWe conducted a cross-sectional study from January 1st to 30th, 2022. Primary data were collected from purposely selected seven (7) kebele of the district based on potential users of agricultural credit. Then the impact was investigated by applying the propensity score matching technique. A Probit regression model was used to determine factors associated with credit use. The significance of the variables was decided at a 5% level of significance.ResultsIn our study, a total sample of 347 smallholder farmers were randomly selected, out of which 42.9% were credit-users while 59.1% were non-users. Regarding sources of credit use, Vision Fund was the most commonly used source of credit with 67.8% of users, followed by the Omo Microfinance institution with 22.1%. Sex of the farmer, age of the farmer, existence collateral, farm size, attitude towards risk, extension service, membership in credit institutions, road access, and number of total livestock units in tropical livestock units (TLU) had significant effects on credit use at a 5% level of significance. Moreover, the estimates showed that utilizing credit resulted in a rise in crop productivity in current market value and total yearly income by 19,302.44 and 18,009.63 respectively.ConclusionOur study suggested that credit use had a considerable impact on crop productivity and total annual income. As a result, the study recommended that the government’s rural finance policy agenda should prioritize opening different branches near farmers, improving credit usability, and providing more training programs to smallholder farmers to improve their skills and help reduce the problems that impede their use of agricultural credit.

Hubungan Supervisi Akademik Kepala Sekolah, Komunikasi Interpersonal, dan Etos Kerja dengan Kinerja Guru di SDN Kecamatan Banjarbaru Utara

This study aims to describe the principal's academic supervision activities, interpersonal communication, work ethic, and teacher performance; and analyze the direct and indirect relationship between the principal's academic supervision, interpersonal communication, and work ethic with the performance of elementary school teachers in North Banjarbaru District, Banjarbaru City. This research is a quantitativ research. The sample size of this study was 172 teachers. Data collection instruments in the form of questionnaires that have met the requirements of validity and reality tests. Data analysis to test the relationship in this study used path analysis. Based on the results of this study, it was found that there is a direct relationship between: academic supervision of the principal with teacher performance, interpersonal communication with teacher performance, work ethic with teacher performance academic supervision of the principal with work ethic, interpersonal communication with work ethic; and the indirect relationship between the principal's academic supervision and teacher performance through work ethic, interpersonal communication with teacher performance through work ethic.academic principal, interpersonal communication, work ethic and performance of elementary school teachers in North Banjarbaru District, Banjarbaru City Keywords: Principal's academic supervision, interpersonal communication, work ethic, teacher performance

Efektivitas Supervisi Kepala Sekolah Dalam Peningkatan Profesionalisme Guru IPS di SMP 16 Seluma

Supervision services are provided to schools for the purpose of improving curriculum, learning, and instruction. As a logical consequence of this activity, schools must always be ready to be supervised because the purpose of supervision is clear. Educational problems are easily resolved if schools and principals understand the role and function of supervision. The aim of this research is to find out how effective the principal's supervision is in increasing the professionalism of social science teachers at SMP Negeri 16 Seluma. This research uses qualitative methods, and the respondents consist of school principals, social studies teachers and students. Observation, documentation, and interviews are data collection methods. The results of this research are as follows: 1) The ability of the principal to supervise social studies teachers at SMP Negeri 16 Seluma Regency. The principal must form a supervision team to start the supervision program; working with teachers to improve their competence as teachers; using direct and indirect approaches; and implementing methods, including meetings between principals and teachers. The school principal's professionalism supervision activities to increase the professionalism of social science teachers at SMP Negeri 16 Seluma were quite effective, with an average score of 3.83 and the professionalism of social studies teachers with an average score of 3.31.

Correlating Managerial Activities, Academic Supervision, and Teacher Competence in Public Elementary Schools

The objective of this study is to explore the immediate links between the management practices of principals and the organizational atmosphere, as well as the direct connections between the academic oversight by principals and the professional skills of public elementary school educators in the Kuripan District of Barito Kuala Regency. Utilizing a quantitative approach, this investigation employs a correlational study design that is articulated through a path analysis framework. The study encompasses a total of 55 educators, with the sample including the entire population via a comprehensive sampling method. The methodology for gathering data incorporates the use of surveys and the examination of PKG (Teacher Performance Assessment) records. The analysis of the data involves descriptive statistics, tests for normality, linearity, and multicollinearity prerequisites, alongside assessments of validity and reliability, and the execution of multiple regression analyses for hypothesis testing, including t-tests, F tests, and evaluations of effective and relative contributions, in addition to path analysis. Findings indicate a direct correlation between the principals’ managerial roles and the professional capabilities of teachers at 0.352, between principals’ managerial roles and the organizational environment at 0.424, between academic oversight and teachers’ professional capabilities at 0.335, between academic oversight and the organizational environment at 0.380, and between the organizational environment and teachers’ professional capabilities at 0.346. Indirect correlations were observed between managerial activities of principals through the organizational climate on teachers’ professional capabilities at 0.147, and academic oversight through organizational climate impacting teachers’ professional capabilities (Y) at 0.131. In summary, the study confirms both direct and indirect associations between the managerial tasks of principals and academic oversight, mediated by the organizational climate, with the professional competence of teachers.

Continuous and differential improvement in worldwide access to hematopoietic cell transplantation: activity has doubled in a decade with a notable increase in unrelated and non-identical related donors.

Promoting access to and excellence in hematopoietic cell transplantation (HCT) by collecting and disseminating data on global HCT activities is one of the principal activities of the Worldwide Network for Blood and Marrow Transplantation, a non-governmental organization in working relations with the World Health Organization. HCT activities are recorded annually by member societies, national registries and individual centers including indication, donor type (allogeneic/autologous), donor match and stem cell source (bone marrow/peripheral blood stem cells/cord blood). In 2018, 1,768 HCT teams in 89 countries (6 World Health Organization regions) reported 93,105 (48,680 autologous and 44,425 allogeneic) HCT. Major indications were plasma cell disorders and lymphoma for autologous, and acute leukemias and MDS/MPN for allogeneic HCT. HCT numbers increased from 48,709 in 2007. Notable increases were seen for autoimmune diseases in autologous and hemoglobinopathies in allogeneic HCT. The number of allogeneic HCT more than doubled with significant changes in donor match. While HCT from HLA-identical siblings has seen only limited growth, HCT from non-identical related donors showed significant increase worldwide. Strongest correlation between economic growth indicator of gross national income/capita and HCT activity/10 million population was observed for autologous HCT (correlation coefficient [r]=0.79). HCT from unrelated donors showed strong correlation (r=0.68), but only moderate correlation was detected from related donors (r=0.48 for HLA-identical sibling; r=0.45 for other). The use of HCT doubled in about a decade worldwide at different speed and with significant changes regarding donor match as a sign of improved access to HCT worldwide. Although narrowing, significant gaps remain between developing and non-developing countries.

Regulation by the RNA-binding protein Unkempt at its effector interface

How RNA-binding proteins (RBPs) convey regulatory instructions to the core effectors of RNA processing is unclear. Here, we document the existence and functions of a multivalent RBP–effector interface. We show that the effector interface of a conserved RBP with an essential role in metazoan development, Unkempt, is mediated by a novel type of ‘dual-purpose’ peptide motifs that can contact two different surfaces of interacting proteins. Unexpectedly, we find that the multivalent contacts do not merely serve effector recruitment but are required for the accuracy of RNA recognition by Unkempt. Systems analyses reveal that multivalent RBP–effector contacts can repurpose the principal activity of an effector for a different function, as we demonstrate for the reuse of the central eukaryotic mRNA decay factor CCR4-NOT in translational control. Our study establishes the molecular assembly and functional principles of an RBP–effector interface.

Progressive Irreversible Proprioceptive Piezo2 Channelopathy-Induced Lost Forced Peripheral Oscillatory Synchronization to the Hippocampal Oscillator May Explain the Onset of Amyotrophic Lateral Sclerosis Pathomechanism.

Amyotrophic lateral sclerosis (ALS) is a mysterious lethal multisystem neurodegenerative disease that gradually leads to the progressive loss of motor neurons. A recent non-contact dying-back injury mechanism theory for ALS proposed that the primary damage is an acquired irreversible intrafusal proprioceptive terminal Piezo2 channelopathy with underlying genetic and environmental risk factors. Underpinning this is the theory that excessively prolonged proprioceptive mechanotransduction under allostasis may induce dysfunctionality in mitochondria, leading to Piezo2 channelopathy. This microinjury is suggested to provide one gateway from physiology to pathophysiology. The chronic, but not irreversible, form of this Piezo2 channelopathy is implicated in many diseases with unknown etiology. Dry eye disease is one of them where replenishing synthetic proteoglycans promote nerve regeneration. Syndecans, especially syndecan-3, are proposed as the first critical link in this hierarchical ordered depletory pathomechanism as proton-collecting/distributing antennas; hence, they may play a role in ALS pathomechanism onset. Even more importantly, the shedding or charge-altering variants of Syndecan-3 may contribute to the Piezo2 channelopathy-induced disruption of the Piezo2-initiated proton-based ultrafast long-range signaling through VGLUT1 and VGLUT2. Thus, these alterations may not only cause disruption to ultrafast signaling to the hippocampus in conscious proprioception, but could disrupt the ultrafast proprioceptive signaling feedback to the motoneurons. Correspondingly, an inert Piezo2-initiated proton-based ultrafast signaled proprioceptive skeletal system is coming to light that is suggested to be progressively lost in ALS. In addition, the lost functional link of the MyoD family of inhibitor proteins, as auxiliary subunits of Piezo2, may not only contribute to the theorized acquired Piezo2 channelopathy, but may explain how these microinjured ion channels evolve to be principal transcription activators.

The Gender Wage Gap Among Early-Career Family Physicians.

Numerous studies have documented salary differences between male and female physicians. For many specialties, this wage gap has been explored by controlling for measurable factors that influence pay such as productivity, work-life balance, and practice patterns. In family medicine where practice activities differ widely between physicians, it is important to understand what measurable factors may be contributing to the gender wage gap, so that employers and policymakers and can address unjust disparities. We used data from the 2017 to 2020 American Board of Family Medicine (ABFM) National Graduate Survey (NGS) which is administered to family physicians 3 years after residency (n = 8608; response rate = 63.9%, 56.2% female). The survey collects clinical income and practice patterns. Multiple linear regression analysis was performed, which included variables on hours worked, degree type, principal professional activity, rural/urban, and region. Although early-career family physician incomes averaged $225,278, female respondents reported incomes that were $43,566 (17%) lower than those of male respondents (P = .001). Generally, female respondents tended toward lower-earning principal professional activities and US regions; worked fewer hours (2.9 per week); and tended to work more frequently in urban settings. However, in adjusted models, this gap in income only fell to $31,804 (13% lower than male respondents, P = .001). Even after controlling for measurable factors such as hours worked, degree type, principal professional activity, population density, and region, a significant wage gap persists. Interventions should be taken to eliminate gender bias in wage determinations for family physicians.

AI-Driven Exploration and Prediction of Company Registration Trends with Registrar of Companies (RoC)

This study presents a comprehensive analysis of company registration trends in India, focusing on data sourced from the Registrar of Companies (RoC). The study investigates the temporal patterns of company registrations, emphasizing principal business activities and classifications into public and private sectors. Leveraging advanced data pre-processing techniques, The Study explores the spatial and temporal dynamics of company registrations. Furthermore, a suite of machine learning algorithms, including Linear regression, Decision tree, Random Forest, GBM, SVM, KNN, Naive Bayes, and Weka, is employed to predict future registration trends. Visualization of insights is facilitated through the use of Tableau. The findings provide valuable insights for stakeholders in business, policy, and investment sectors, aiding informed decision-making and strategic planning.

Ethical considerations related to drone use for environment and health research: A scoping review protocol.

The use of drones in environment and health research is a relatively new phenomenon. A principal research activity drones are used for is environmental monitoring, which can raise concerns in local communities. Existing ethical guidance for researchers is often not specific to drone technology and practices vary between research settings. Therefore, this scoping review aims to gather the evidence available on ethical considerations surrounding drone use as perceived by local communities, ethical considerations reported on by researchers implementing drone research, and published ethical guidance related to drone deployment. This scoping review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) and the Joanna Briggs Institute (JBI) guidelines. The literature search will be conducted using academic databases and grey literature sources. After pilot testing the inclusion criteria and data extraction tool, two researchers will double-screen and then chart available evidence independently. A content analysis will be carried out to identify patterns of categories or terms used to describe ethical considerations related to drone usage for environmental monitoring in the literature using the R Package RQDA. Discrepancies in any phase of the project will be solved through consensus between the two reviewers. If consensus cannot be reached, a third arbitrator will be consulted. Ethical approval is not required; only secondary data will be used. This protocol is registered on the Open Science Framework (osf.io/a78et). The results will be disseminated through publication in a scientific journal and will be used to inform drone field campaigns in the Wellcome Trust funded HARMONIZE project. HARMONIZE aims to develop cost-effective and reproducible digital infrastructure for stakeholders in climate change hotspots in Latin America & the Caribbean and will use drone technology to collect data on fine scale landscape changes.

Design of Religious Moderation Education in Muhammadiyah Middle School and Ma'arif NU Middle School Educational Institutions

<span lang="EN-US">This study aims to analyze the application of religious moderation education curriculum design in educational institutions, including Mandiri Berbagi and Mandiri Berubah Curriculum Models, collaborative and separate curriculum design, and hidden curriculum design in SMP Muhammadiyah 6 Wuluh and SMP 09 Ma'arif NU Ambulu in Jember. This study used a qualitative approach with the type of case study to describe and analyze the design of religious moderation education in educational institutions. Data collection was conducted by observing the activities of teachers and principals in designing a religious moderation education curriculum. At the same time, interviews were carried out with the principal, subject teacher, and the vice principal of curriculum involved in the design of religious moderation education. Data analysis follows the Miles, Huberman, and Saldana models, including data condensation, data presentation, and inference. Furthermore, the validity of the data was ensured using source and technical triangulation. The findings of this study revealed 1) the application of religious moderation education curriculum with Mandiri Berbagi and Mandiri Berubah Curriculum Models, 2) the design of moderation education curriculum with collaborative model of ISMUBARIS (Islam, to-Muhammadiyah, Arabic and Islamic Cultural History) and a separate model between religious education and the teachings of Nahdatul Ulama, and 3) hidden curriculum on all subjects with the message of Islam wasathiyah and moderate Islamic messages of an-Nahdiya. This research contributes to policymakers, such as the government, the Ministry of Education and Culture, the Ministry of Religion, and all educational institutions, such as junior high schools and MTs, in implementing religious moderation education for application in the curriculum and learning of Islam.</span>

Eco-tourism in Nepal

Eco-tourism involves visiting unique natural habitats with the purpose of aiding conservation efforts and observing wildlife. There are several benefits of eco-tourism which include the conservation of the environment, a rise in funding by the government, cultural exchange, and support for local businesses. The principal tourism activities in Nepal are mountain climbing, trekking, visiting religious and cultural sites, rafting, bungee jumping, rock climbing, jungle safari, and so on. Ecotourism in Nepal depends on coordinated policies, integrated conservation, and sustainable community development, requiring international and grassroots collaboration to maximize benefits while conserving natural beauty. Various projects have been organized to develop eco-tourism in Nepal. Some of the major projects that have been organized are Ghalegaon-Sikles Ecotourism Project, Annapurna Conservation Area Project, Kanchenjunga Community Based Ecotourism Project, Manaslu Nature Based Ecotourism Project and Upper Mustang Biodiversity Conservation Project.

Learning trajectory in the material of comparing and ordering fractions using paper folding for elementary school students

Background:Understanding fractions in mathematics often poses greater complexity compared to integral numbers. The primary difficulty lies in students' inadequate grasp of fractional basics, notably in comparing and sequencing fractions.Aim: This research seeks to create and evaluate a learning pathway's effect on fourth graders' comprehension of fractions, with a focus on their comparison and sequencing.Method: Employing a design research validation study approach, the research progresses through preliminary design, experimental design, and retrospective analysis. Conducted in a Palembang school involving six fourth graders recommended by their teacher, data collection encompassed essay-based pre and post-tests, Student Activity Sheets, observations, interviews, and documentations. The data analysis was retrospectively carried out, anchored on HLT as the benchmark.Result: Findings reveal a student learning trajectory encompassing three principal activities. Initially, students used folding and gluing of paper to discern fraction values. Subsequently, they engaged in coloring and illustrating folds for fraction comparison. The final activity involved drawing, coloring boxes, and fraction comparison and sequencing. Overall, students showed proficiency in understanding and determining fraction values and comparing them, yet struggled with ordering certain fractions.Conclusion: The structured learning path facilitated students' understanding of basic fraction concepts, especially in comparing them. Nevertheless, reinforcing methods or approaches for teaching fraction ordering is essential.

Principal components approach of physiological and physical metrics collected through GPS technology in soccer referees

The aim of this study was to define and classify the different physical and physiological performance metrics on national and non-national soccer referees (SRs) through GPS technology. Sixty SRs (age: 28.9 ± 4.9 years; weight: 70.2 ± 8.0 kg; height: 175.7 ± 5.5 cm) were tested using the 18 Hz global positioning system (GPS) (WimuPro, Realtrack, Almería, Spain). An exploratory factor analysis was performed using principal component analysis (PCA) on performance indicators with orthogonal rotation (VariMax). Thirteen metrics (total distance, distance covered at different speeds, maximum heart rate, and heart rate recorded in different zones) were integrated in three principal components, activation (PCA1), recovery (PCA2), and high intensity (PCA3). They represented 86% and 89% of total explained variance of the competition performance in national and non-national SRs, respectively. Distance covered at very high speed and heart rate between 80% and 89.9% of the maximum integrated the high-intensity principal component and were higher in non-national SRs. The main finding of this study was that it defined for the first time in the scientific literature the main components that discriminate physical performance between national and non-national referees, where high intensity metrics have greater weight in non-national referees. In addition, GPS technology together with PCA analysis were presented as useful methods to discriminate the most representative physical and physiological performance metrics in sports competition in SRs.

Multi-criteria analysis of different land-use activities on groundwater resources in Maiduguri, Borno State

Land use and their related anthropogenic activities are likely to continue to impact shallow groundwater quality at different scales. Multi-criteria analysis (MCA) is a framework for evaluating decision options against multiple criteria. This study employed the Simple Multi-Attribute Rating Technique (SMART) methodology in ranking the different land-use activities based on their adverse effects on groundwater quality. In this respect, the strategic stakeholders engaged in this study were allowed to prioritise these activities based on the magnitude of their negative effect on the groundwater resources of the study area. The stakeholders' ranking shows that the residential area is the principal activity (44.7%) that has an impact on groundwater resources in Maiduguri. This is followed by agricultural land and forested areas with negative impacts in the range of 9% and 2.18%, respectively. Geographic Information System data was obtained from secondary data sources to show the impact of different land uses in the study area This study will be helpful to policymakers and decision-makers in adopting mitigation strategies that will provide solutions to the negative effects of groundwater contamination in Borno State.

Principal time use and student academic achievement in Singapore

PurposeThis study aims to test the mediated effect of school climate in the relationship of principal time use (PTU) to student academic achievement using data from Singapore's 2011 Trends in International Mathematics and Science Study (TIMSS).Design/methodology/approachCapitalizing on the large-scale data, the study examined how Singapore principals distributed their time across 13 leadership activities and tested using structural equation modeling (SEM) how Singapore principals' time use was related to student achievement through molding intermediate school conditions, such as school climate.FindingsThe authors' findings suggest that Singaporean principals, when allocating time, generally emphasized (1) monitoring students' learning progress, (2) promoting school vision, (3) developing curricular goals and (4) monitoring teachers in areas related to curricular goals. Furthermore, after classifying the 13 principal activities into three broad domains, the authors find that Singaporean principals prioritize the domain of vision and goals over the other two domains – facilitating teaching and learning through a safe, positive school environment and problem-solving with teachers, as well as self and organizational improvement. Finally, the authors' SEM manifested a partial mediated model, suggesting principals' strategic time use could serve as a malleable factor in yielding optimal student outcomes through developing a positive school climate.Originality/valueThis study at present is one of the early attempts linking PTU, intermediate school conditions (e.g. school climate) and student outcomes using a mediated design and corresponding statistical modeling.

A conceptual model of cow-calf systems functioning on native grasslands in a subtropical region.

Cow-calf systems utilise grazing of native grasslands for beef cattle propagation and constitute the principal livestock activity in the Pampas and Campos areas. Cow-calf system sustainability is questioned because of their low production levels and negative environmental impact. Ecological intensification has been proposed as a way out that constitutes an alternative to dominant discourses based on increasing external-input use. There is, however, a considerable gap between the availability of scientific knowledge to promote the ecological intensification of cow-calf systems and farmers' practices. This gap between scientific knowledge availability and farmers' practices can be made explicit, and its consequences for systems performance can be explored through a conceptual model. Conceptual models are tools to build a systems view of the interactions among the production system's state variables, farm management, and resulting system performance. In this paper, we develop a conceptual model of cow-calf systems on native grasslands of the Pampas and Campos regions to support the diagnosis and redesign of farm systems towards ecological intensification. We apply the conceptual model to analyse cow-calf systems in Uruguay, drawing on a survey among 250 Uruguayan livestock farmers. Using the model, we show that in Uruguay, the level of implementation of strategic, tactical, and decision-supporting techniques is low. Consequently, most farms have poor control of the grazing intensity and timing of main events in the production cycle. This results in ample room to improve the productive and environmental performance of most cow-calf farms in Uruguay. We distinguished three broad types of cow-calf systems based on the degree of implementation of techniques, the evolution of state variables throughout the year, and productive indicators. These types imply different departure points and strategies for a sustainability transition process. The conceptual model designed in this paper may support the cow-calf systems sustainability transition in the context of co-innovation processes by aiding the interactive diagnosis and redesign of farm systems.

The globalisation of Italian agriculture. Transformations of migrant labour composition in agriculture in Trentino

AbstractThe cultivation of apples is one of the principal economic activities in Trentino, which is responsible for 25% of Italian apple production and 4% of European apple production. The industry is structurally based on migrant work, especially from Eastern European countries in the EU. This model has come up against obstacles due to EU migrant workers redrawing their trajectories: They now tend to remain in their country of origin or move towards central European countries, where they find better wages and working conditions. This is also due to the inadequacy of Italian migration policies, which make it difficult for employers to recruit migrant workers. As a result, employers started to recruit refugees and asylum seekers from countries in the sub‐Saharan and Indian subcontinent who had recently arrived in Trentino. This article analyses these transformations and the trend of ‘refugeeisation’ process of the agricultural workforce, as well as the partial replacement of seasonal workers in Trentino. It then focuses on the impact of the pandemic on international recruitment and on the organisation of the migrant workforce.

CA3 principal cell activation triggers hypersynchronous-onset seizures in a mouse model of mesial temporal lobe epilepsy.

Mesial temporal lobe epilepsy (MTLE) is the most common form of focal epilepsy and it is characterized by seizures that are often refractory to medications. Seizures in MTLE have two main patterns of onset that have been termed hypersynchronous (HYP) and low-voltage fast (LVF) and are believed to mainly depend on the activity of excitatory principal cells and inhibitory interneurons, respectively. In this study, we investigated whether unilateral open-loop optogenetic activation of CaMKII-positive principal cells in the hippocampus CA3 region favors the generation of spontaneous HYP seizures in kainic acid-treated (KA) CaMKII-ChR2 mice. Optogenetic activation of CA3 principal cells (1 Hz, 180 s ON, 220 s OFF) was implemented for 15 days after KA-induced status epilepticus. We found that both LVF and HYP seizures occurred in nonstimulated CaMKII-ChR2 (n = 6) and stimulated CaMKII-Cre (n = 5) mice. In contrast, optogenetic activation of principal cells in CaMKII-ChR2 mice (n = 5) triggered only HYP seizures that were characterized by high fast ripple (250-500 Hz) rates during the pre-ictal and ictal periods. These results provide firm evidence that in MTLE spontaneous seizures with different onset patterns depend on distinct neuronal network mechanisms of generation. They also demonstrate that HYP seizures occurring in vivo along with their associated fast ripples depend on the activity of principal cells in the CA3 region.NEW & NOTEWORTHY Previous evidence suggested that different seizure onset patterns rely on the activity of distinct neuronal populations. In this study, we show for the first time that in vivo optogenetic stimulation of CaMKII principal cells in kainic acid-treated mice triggers hypersynchronous-onset seizures that are associated with fast ripples. Our findings indicate that in patients with predominant HYP-onset seizures, anticonvulsant treatments should be aimed at limiting the firing of principal neurons in the seizure onset zone.