Surveillance Functions Research Articles

PatronuS: A System for Privacy-Preserving Cloud Video Surveillance

Privacy has become one of the major concerns in cloud video surveillance. Privacy protection of the surveillance videos strive to protect users’ privacy information without hampering regular security tasks of the surveillance, meanwhile retains the system’s high accuracy and efficiency. The current state of the art in protecting the video privacy is mainly realized through Privacy Region Protection, which only protects the privacy regions while keeps the non-privacy regions visually intact so that processing in the cloud is still feasible. However, the problem of determining the privacy regions has been ignored and not properly addressed. In this paper, we propose a novel notion - concept graph , and with the aid of that, we develop our system – PatronuS to determine the privacy regions subject to satisfying both privacy and security requirements. We further propose an event distilling model and a privacy inference model to assist in determining specific privacy regions. And we evaluate PatronuS in real-world settings and demonstrate its efficiency in privacy protection without degrading system’s surveillance functionality.

Design of a Low Earth Orbit Satellite Constellation Network for Air Traffic Surveillance

The satellite constellation with automatic dependent surveillance-broadcast on-board is of great importance for air traffic surveillance due to its multiple advantages compared with traditional methods. Although some research has been conducted on satellite constellation design based on coverage performance, the findings cannot entirely satisfy all the requirements of air traffic surveillance owing to the lack of analysis on inter-satellite links and network transmission. This paper presents a novel design of a low earth orbit satellite constellation network to solve this problem. Based on the requirements of space-based surveillance, an evaluation model of constellation performance is proposed concerning coverage, link and transmission. The simulation results show that the evaluation model can reflect the performance of a satellite constellation network designed for a space-based surveillance system, and a 55-satellite constellation design scheme with fairly good performance can fulfil the function of global real-time air traffic surveillance.

The Amyloid-beta rich CNS environment alters myeloid cell functionality independent of their origin

Microglia, the innate immune cells of the central nervous system (CNS) survey their surroundings with their cytoplasmic processes, phagocytose debris and rapidly respond to injury. These functions are affected by the presence of beta-Amyloid (Aβ) deposits, hallmark lesions of Alzheimer’s disease (AD). We recently demonstrated that exchanging functionally altered endogenous microglia with peripheral myeloid cells did not change Aβ-burden in a mouse model mimicking aspects of AD at baseline, and only mildly reduced Aβ plaques upon stimulation. To better characterize these different myeloid cell populations, we used long-term in vivo 2-photon microscopy to compare morphology and basic functional parameters of brain populating peripherally-derived myeloid cells and endogenous microglia. While peripherally-derived myeloid cells exhibited increased process movement in the non-diseased brain, the Aβ rich environment in an AD-like mouse model, which induced an alteration of surveillance functions in endogenous microglia, also restricted functional characteristics and response to CNS injury of newly recruited peripherally-derived myeloid cells. Our data demonstrate that the Aβ rich brain environment alters the functional characteristics of endogenous microglia as well as newly recruited peripheral myeloid cells, which has implications for the role of myeloid cells in disease and the utilization of these cells in Alzheimer’s disease therapy.

Bisphenol A induces DNA damage in cells exerting immune surveillance functions at peripheral and central level

Bisphenol A (BPA) is a synthetic xenoestrogen diffused worldwide. Humans are chronically exposed to low doses of BPA from food and drinks, thus BPA accumulates in tissues posing human health risk. In this study, we investigated the effects of BPA on peripheral blood mononuclear cells (PBMC) from human healthy donors, and in glia and microglia of rat offspring at postnatal day 17 (17PND) from pregnant females who received BPA soon after coupling and during lactation and weaning. Results indicated that BPA affected Phytoemagglutinin (PHA) stimulated PBMC proliferation causing an S-phase cell cycle accumulation at nanomolar concentrations while BPA was almost ineffective in resting PBMC. Furthermore, BPA induced chromosome aberrations and the appearance of shattered cells characterized by high number of fragmented and pulverized chromosomes, suggesting that the compound could cause a massive genomic rearrangement by inducing catastrophic events. The BPA-induced DNA damage was observed mainly in TCD4+ and TCD8+ subsets of T lymphocytes and was mediated by the increase of ERK1/2 phosphorylation, p21/Waf1 and PARP1 protein expression. Intriguingly, we observed for the first time that BPA-induced effects were associated to a sex specific modulation of ERα and ERβ in human PBMC. Immunofluorescence analysis of rat hippocampus corroborated in vitro findings showing that BPA induced ɣH2AX phosphorylation in microglia and astrocytosis by decreasing ERα expression within the dentate gyrus. Overall these results suggest that BPA can alter immune surveillance functions at both peripheral and central level with a potential risk for cancer, neuroinflammation and neurodegeneration.

Kaposi's Sarcoma-Associated Herpesvirus Infection Induces the Expression of Neuroendocrine Genes in Endothelial Cells.

Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with endothelial Kaposi's sarcoma (KS) in immunocompromised individuals. KS lesion cells exhibit many similarities to neuroendocrine (NE) cancers, such as highly vascular and red/purple tumor lesions, spindle-shaped cells, an insignificant role for classic oncogenes in tumor development, the release of bioactive amines, and indolent growth of the tumors. However, the mechanistic basis for the similarity of KS lesion endothelial cells to neuroendocrine tumors remains unknown. Next-generation sequencing and bioinformatics analysis in the present study demonstrate that endothelial cells latently infected with KSHV express several neuronal and NE genes. De novo infection of primary dermal endothelial cells with live and UV-inactivated KSHV demonstrated that viral gene expression is responsible for the upregulation of five selected NE genes (adrenomedullin 2 [ADM2], histamine receptor H1 [HRH1], neuron-specific enolase [NSE] [ENO2], neuronal protein gene product 9.5 [PGP9.5], and somatostatin receptor 1 [SSTR1]). Immunofluorescence and immunohistochemistry examinations demonstrated the robust expression of the NE genes HRH1 and NSE/ENO2 in KSHV-infected KS tissue samples and KS visceral tissue microarrays. Further analysis demonstrated that KSHV latent open reading frame K12 (ORFK12) gene (kaposin A)-mediated decreased host REST/NRSF (RE1-silencing transcription factor/neuron-restrictive silencer factor) protein, a neuronal gene transcription repressor protein, is responsible for NE gene expression in infected endothelial cells. The NE gene expression observed in KSHV-infected cells was recapitulated in uninfected endothelial cells by the exogenous expression of ORFK12 and by the treatment of cells with the REST inhibitor X5050. When the neuroactive ligand-activating receptor HRH1 and inhibitory SSTR1 were knocked out by CRISPR, HRH1 knockout (KO) significantly inhibited cell proliferation, while SSTR1 KO induced cell proliferation, thus suggesting that HRH1 and SSTR1 probably counteract each other in regulating KSHV-infected endothelial cell proliferation. These results demonstrate that the similarity of KS lesion cells to neuroendocrine tumors is probably a result of KSHV infection-induced transformation of nonneuronal endothelial cells into cells with neuroendocrine features. These studies suggest a potential role of neuroendocrine pathway genes in the pathobiological characteristics of KSHV-infected endothelial cells, including a potential mechanism of escape from the host immune system by the expression of immunologically privileged neuronal-site NE genes, and NE genes could potentially serve as markers for KSHV-infected KS lesion endothelial cells as well as novel therapeutic targets to control KS lesions.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) manipulates several cellular pathways for its survival advantage during its latency in the infected human host. Here, we demonstrate that KSHV infection upregulates the expression of genes related to neuronal and neuroendocrine (NE) functions that are characteristic of NE tumors, both in vitro and in KS patient tissues and the heterogeneity of neuroendocrine receptors having opposing roles in KSHV-infected cell proliferation. Induction of NE genes by KSHV could also provide a potential survival advantage, as the expression of proteins at immunologically privileged sites such as neurons on endothelial cells may be an avenue to escape host immune surveillance functions. The NE gene products identified here could serve as markers for KSHV-infected cells and could potentially serve as therapeutic targets to combat KSHV-associated KS.

"If you please… draw me a cell". Insights from immune cells.

Studies in recent years have shed light on the particular features of cytoskeleton dynamics in immune cells, challenging the classical picture drawn from typical adherent cell lines. New mechanisms linking the dynamics of the membrane-cytoskeleton interface to the mechanical properties of immune cells have been uncovered and shown to be essential for immune surveillance functions. In this Essay, we discuss these features, and propose immune cells as a new playground for cell biologists who try to understand how cells adapt to different microenvironments to fulfil their functions efficiently.

Dampak Strategi Maritim Terhadap Peningkatan Keamanan Maritim Indonesia Terkait Ancaman IUU Fishing di Wilayah NKRI Tahun 2014-2017

Since the 1990s, IUU Fishing has been a threat to Indonesian maritim security.Natuna Sea, Arafura Sea, and Sulu Sulawesi Seais vulnerable location which IUU Fishing happen. Not only defense function, but also IUU Fishing has become threat to public welfare. IUU Fishing threatening fishery industry that become source of employment and food stock in fishery sector. Therefore, Indonesia applies maritim strategy in the form of ship sinking policy and improve function of surveillance as a control in the maritim region. This research will explain how the impact ofthe application of ship sinking policy to enhancing maritim security related to the threat of IUU Fishing in the NKRI territory in 2014-2017.The application of maritim strategy has an impact on improving Indonesian maritim security. Improvement in maritim security is measured based on maritim security indicators. The maritim security indicators are measured based on 4 dimensions of the concept of maritim security,namely sea power, marine safety, blue economy, and human resilience. Keywords : IUU Fishing, Maritim Security, Indonesia, Maritim Strategy DOI : https://doi.org/10.33005/jgp.v7i01.1817

The remotely controlled underwater robot system

The remotely controlled underwater robot system is used extensively by the scientific community to study the ocean, in support of diving operations, in military use, in educational outreach, in broadcast use. We built this system which has three components: 1) the surface control interface; 2) the intermediate device; 3) the robot itself. The presence of this robot replaces human activities where access is not allowed or life is endangered. The novelty of this device is the construction of component 2 (intermediate), which represents a storage frame for the underwater robot and part of the control umbilical cord. The frame descends with the robot to the depth of surveillance from where the robot leaves the storage frame and is further controlled to the research objective. The surveillance function is performed from the intermediary with the help of a video camera. The video camera is the IP type and can be accessed through the data over power network. The movement of the underwater device is accomplished by means of 8 electric motors (4 for horizontal control and 4 for vertical control). The robot has data acquisition and storage systems and piloting systems. The purpose of building this robot is educational research.

You Had One Job: The Shortcomings of Public Health England and the World Health Organization During the Covid-19 Pandemic

The World Health Organization and Public Health England have been widely criticised for their response to the Covid-19 pandemic. This paper looks at what went wrong. The WHO has been accused of being credulous in its dealings with China and giving the world a false sense of security about the virus in the early stages of the outbreak. Public Health England was criticised for failing to expand diagnostic testing and contact tracing, discouraging face-mask wearing, failing to share infection data with local authorities, and overcounting the number of deaths from Covid-19 in England. In theory, both organisations prioritise infectious diseases, but have arguably spread their resources to thinly. This has led to a lack of focus. The institutional failure of public health agencies does not easily lend itself to free-market solutions, but funding does not have to come from the state and there is room for some competition. The WHO may be beyond reform, but its most important function of disease surveillance could be carried out by another agency. Alternatively, member-states and private philanthropists could fund a politically neutral pandemic surveillance organisation, focused solely on viral and bacterial epidemics. Public Health England could be replaced with an agency that plans and executes the nation’s response to viral and bacterial epidemics, while its health promotion campaigns could be restored to the NHS and local public health budgets could be supplied by the Department of Health.

IMF Sovereign Debt Restructuring Framework: Origin, Evolution and Latest Updates of its Main Components

Abstract The first introductory manual of the IMF framework for Sovereign Debt Restructurings (SDRs) is introduced in this article. SDR processes, in which billions of dollars are negotiated, constitute key elements for the healthy recovery of an over-indebted economy. However, there are no academic works that analyze in depth the way in which the Fund organizes them. Based on official documents, this paper aims to bridge this gap by explaining how the components that shape the IMF SDR framework are articulated. To this end, the article analyzes: 1) the framework substantial and procedural rules in order to show it as an abstract normative structure as well as an action procedure applicable to specific cases; 2) the framework evolution, synthetically presenting the discussions that gave rise to its main components and justified its principal changes; 3) the framework latest updates, which modified sensitive areas of the Fund’s surveillance and financing functions. This analytical perspective closes a logical circle that shows the IMF SDR framework in a historical and integral manner and also gives an idealistic insider view to what the Fund is and how it operates.

Pristup odnosa konstanthih lažnih alarma za poboljšano praćenje ciljeva

Each radar has the function of surveillance of certain areas of interest. In particular, the radar also has the function of tracking moving targets in that territory with some probability of detection, which depends on the type of detector. Constant false alarm ratio (CFAR) is a very commonly used detector. Changing the probability of target detection can directly affect the quality of tracking the moving targets. The paper presents the theoretical basis of the influence of CFAR detectors on the quality of tracking, as well as an approach to the selection of CFAR detectors, CATM CFAR, which enables better monitoring by the Interacting Multiple Model (IMM) algorithm with two motion models. Comparative analysis of CA and CATM algorithm realized by numerical simulations has shown that CATM CFAR gives less tracking error with proportionally the same computer resources.

A Role for the Ribosome-Associated Complex in Activation of the IRE1 Branch of UPR

The ubiquitous ribosome-associated complex (RAC) is a chaperone that spans ribosomes, making contact near both the polypeptide exit tunnel and the decoding center, a position prime for coordination of translation and folding. Loss of RAC results in growth defects and sensitization to translational stress. The mechanism of RAC in responding to specific stresses remains obscure. Data presented here uncover an essential function of mammalian RAC in the unfolded protein response (UPR), coupling the inositol-requiring protein 1α (IRE1α) branch to translation. Knockdown of RAC sensitizes mammalian cells to ER stress by selectively interfering with IRE1α activation. Higher-order oligomerization of IRE1α kinase/endoribonuclease and accurate ribosome stalling of Xbp1 mRNA, as required for IRE1α mediated Xbp1 mRNA splicing activity, depends upon RAC. These results reveal a surveillance function for RAC on the ribosomes: modulating IRE1α clustering and the fitness of Xbp1 mRNA splicing in coordination with translation.

A Prospective Randomized Blinded Trial of Remote Ischemic Preconditioning in Children Undergoing Cardiac Surgery

Remote ischemic preconditioning (RIPC) has been proposed as an intervention to protect myocardium and attenuate end-organ dysfunction associated with cardiopulmonary bypass. We investigated the effect of RIPC in children undergoing cardiopulmonary bypass involving clinical outcome, cardiac and end-organ function, inflammatory response, and myocardial gene expression. A prospective, investigator-blinded, randomized, controlled trial was performed. Patients were randomized into RIPC or Control; RIPC consisted of three 5-minute cycles of limb ischemia-reperfusion taking place 1 and 12 hours preoperatively. Clinical outcomes included cardiac function, ICU surveillance, and renal function. In addition, inflammatory markers and myocardial gene expression were evaluated. RIPC patients required shorter ICU stay (days), RIPC: 1.8 (0.94-3.88) vs Control: 4.9 (1.63-7.20), P = 0.029. Echocardiography parameters demonstrated reduced biventricular function following surgery showing no difference between groups. A nonsignificant trend for reduced troponin was observed following RIPC: AUC analysis, RIPC: 393.05 (98.85-1038.73) vs Control: 596.10 (225.38-954.24) P = 0.75. B-type natriuretic peptide and renal function parameters were similar between groups. Postoperative TNF-α was significantly reduced after RIPC, RIPC: 15.42 (7.81-114.86) vs Control: 108.98 (42.28-301.19) P = 0.02. Remaining inflammatory markers demonstrated no significant difference between groups. HSP-60 showed lower myocardial expression following RIPC, RIPC: 3.95 (2.69-6.28) vs Control: 6.83 (4.74-8.81), P = 0.05. Expression of other analyzed genes was not influenced by RIPC. RIPC was associated with shorter ICU stay and reduced TNF-α but did not influence other clinical outcomes, not confer protection against cardiac injury or renal dysfunction. The association between RIPC and ICU stay may be influenced by unaccounted latent variables, including cardiac morphology.

A Sparsity-Based Passive Multistatic Detector

In this paper, we examine the problem of target detection for the multistatic passive radar. Passive radar systems leverage the existing wireless sources, such as radio/TV stations and cellular signals that are referred to as illuminators of opportunity (IOs), to illuminate the environment and provide surveillance functions. Usually, these IO source signals are sparse or locally sparse in the frequency domain. We develop a passive multistatic detector by exploiting the sparsity or local sparsity of the IO signals. To improve the computational efficiency, two fast implementations of the proposed detector are also introduced. Simulation results show that the proposed approaches outperform the conventional passive detection methods that model the IO signals as unknown without any specific structures.

A Study on the Revitalization of the Administrative Surveillance Function of the Local Council in the Decentralized Age

A Study on the Revitalization of the Administrative Surveillance Function of the Local Council in the Decentralized Age

The Utility and Validation of Intraepithelial Lymphocyte Count in Duodenal Biopsies in A Tertiary Care Centre in South India

Background: Intraepithelial lymphocytes (IELs) are seen in between the epithelial cells in small and large intestine with the functions of immune surveillance and activation. Increased IELs can be the sole histological finding in latent celiac disease (CD). Aims: To study the utility and clinical relevance of IELs in diagnosing non-neoplastic lesions of duodenum and to determine a cut off for IEL to differentiate CD from other conditions. Materials & methods: This was a prospective descriptive study. Duodenal biopsies from 106 patients with symptoms of malabsorption were studied. Informed written consent was taken. Clinical details were collected. Histomorphological parameters were studied on hematoxylin and eosin stained sections. Intraepithelial lymphocyte counts were done on CD3, CD4 and CD8 IHC stained sections. Statistical analysis was done using IBM- SPSS software version 21. P value <0.05 was considered statistically significant. The threshold score of IELs with maximum sensitivity and specificity was validated using the Receiver operator characteristic curve to distinguish CD from non-celiac disease conditions. Results: We studied 101 duodenal biopsies. Our spectrum included 16 patients of CD (15.8%), 15 of autoimmune duodenitis (14%), 13 of nutritional deficiency associated duodenitis (12.8%), 5 of infectious duodenitis (5%) and 41 patients of non-specific duodenitis (40.6%). The threshold levels were 5/20 villous tip IELs, 24 IELs/100 enterocytes on H& E and >31 IELs by CD3 IHC staining. Conclusion: Our study proposes IEL counts of >31/100 enterocytes in CD3 IHC staining to be significant in South Indian population to differentiate CD from other conditions.

Describing the current state of post-rehabilitation health system surveillance in Ontario – an invited review

Context: Spinal cord injury (SCI) presents numerous physiological, psychosocial, and environmental complexities resulting in significant healthcare system resource demands.Objective: To describe the current health system surveillance mechanisms in Ontario, Canada and highlight gaps in health surveillance among adults with SCI across their lifespan.Methods: A review of administrative data sources capturing SCI-specific information took place via internet searching and networking among SCI rehabilitation and health services experts with emphasis on functionality, health service utilization, and quality of life data.Results: The review identified a distinct paucity of data elements specific to the health surveillance needs of individuals with SCI living in the community. The gaps identified are: (1) a lack of data usability; (2) inadequate linkage between available datasets; (3) inadequate/infrequent reporting of outcomes; (4) a lack of relevant content/patient-reported outcomes; and, (5) failure to incorporate additional data sources (e.g. Insurance datasets).Conclusion: Currently, SCI-specific health data is disproportionately weighted towards the first 3–6 months post injury with detailed data regarding pre-hospital care, acute management and rehabilitation, but little existing infrastructure supporting community-based health surveillance. Given this reality, the bolstering of meaningful community health surveillance of this population across the lifespan is needed. Addressing the identified gaps in health surveillance must inform the creation of a comprehensive community health dataset incorporating patient-reported outcome measures and enabling linkage with existing administrative and/or clinical databases. A future harmonized data surveillance strategy would, in turn, positively impact function, health services, resource utilization and health-related quality of life surveillance.

Serial Changes in Pulmonary Function Testing in A Patient with Tracheobronchial Amyloidosis: Relevance for Early Diagnosis

Amyloidosis is a disease of abnormal extracellular deposition of proteins within tissues, commonly affecting solid organs such as the heart, liver, and kidneys. Less commonly, amyloidosis may affect the proximal tracheobronchial tree. Clinical symptoms are vague and may include shortness of breath, stridor, hoarseness. Pulmonary function testing at the time of diagnosis usually reveals an obstructive pattern. Diagnosis is difficult, and patients with tracheobronchial amyloidosis are frequently misdiagnosed with asthma or chronic obstructive pulmonary disease. Early changes in pulmonary function testing in patients with tracheobronchial amyloidosis have not been described. We present a case of a firefighter who with obstructive symptomatology who was subsequently diagnosed with proximal tracheobronchial amyloidosis. As a component of his occupational health surveillance, yearly examinations and pulmonary function testing had been performed. Serial pulmonary function testing dating back fourteen years prior to diagnosis reveal an early decrease in peak expiratory flow. Over time and in retrospect, progressive blunting of the expiratory limb of his flow-volume loops is identified beginning ten years prior to presentation. These changes significantly predated his clinical symptomatology and may be useful for early identification of patients with tracheobronchial amyloidosis. The relationship between chronic smoke inhalation and the development of tracheobronchial amyloidosis is unclear.

Low-Dose Subcutaneous Anti-CD20 Treatment Depletes Disease Relevant B Cell Subsets and Attenuates Neuroinflammation.

To explore the B cell depleting capacity of a low-dose (20μg) subcutaneous mouse anti-CD20 antibody treatment on disease-relevant B cell populations within lymph nodes and the spleen. B cell depleting capacity was explored in healthy female C57BL/6 and BALB/c mice; following immune activation in two different mouse models: trinitrophenylated lipopolysaccharide model (thymus-independent response) and dinitrophenyl-keyhole limpet hemocyanin model (thymus-dependent response); and in a chronic neuroinflammation experimental autoimmune encephalomyelitis model. CD20 protein expression on B cell subpopulations was also studied. The subcutaneous anti-CD20 regimen resulted in rapid depletion of B cells in blood, lymph nodes and spleen. Low-dose subcutaneous treatment did not reduce antigen-specific immunoglobulin M and immunoglobulin G titers in all subgroups, and relatively spared splenic marginal zone (MZ) B cells in both T cell dependent and T cell independent B cell immunization models. Analysis of immune compartments during anti-CD20-modulated autoimmune neuroinflammation showed that the maximal B cell depletion was achieved within 2days of treatment and was highest in the lymph node. Regardless of the tissues analyzed, low-dose subcutaneous treatment was characterized by rapid B cell repletion following treatment cessation. CD20 protein expression was consistent on all B cell subsets in blood, and was more pronounced in germinal center B cells of lymph nodes and MZ B-cells of the spleen. Low-dose subcutaneous anti-CD20 therapy effectively depleted B cells within lymphatic tissues and reduced the severity of neuroinflammation. These data suggest that subcutaneous anti-CD20 therapies can effectively target disease-relevant B cell populations, have shorter repletion kinetics and maintain vaccination responses, thereby achieving autoimmune amelioration without severely impacting immune surveillance functions. Graphical Abstract *p < 0.05; **p < 0.01. CD, cluster of differentiation; DNP-KLH, dinitrophenyl-keyhole limpet hemocyanin; EC50, concentration of a drug that gives half-maximal response; Ig, immunoglobulin; MZ, marginal zone; s.c., subcutaneous; SEM, standard error of mean; TNP-LPS, trinitrophenylatedlipopolysaccharide.

The NRPD1 N-terminus contains a Pol IV-specific motif that is critical for genome surveillance in Arabidopsis.

RNA-guided surveillance systems constrain the activity of transposable elements (TEs) in host genomes. In plants, RNA polymerase IV (Pol IV) transcribes TEs into primary transcripts from which RDR2 synthesizes double-stranded RNA precursors for small interfering RNAs (siRNAs) that guide TE methylation and silencing. How the core subunits of Pol IV, homologs of RNA polymerase II subunits, diverged to support siRNA biogenesis in a TE-rich, repressive chromatin context is not well understood. Here we studied the N-terminus of Pol IV’s largest subunit, NRPD1. Arabidopsis lines harboring missense mutations in this N-terminus produce wild-type (WT) levels of NRPD1, which co-purifies with other Pol IV subunits and RDR2. Our in vitro transcription and genomic analyses reveal that the NRPD1 N-terminus is critical for robust Pol IV-dependent transcription, siRNA production and DNA methylation. However, residual RNA-directed DNA methylation observed in one mutant genotype indicates that Pol IV can operate uncoupled from the high siRNA levels typically observed in WT plants. This mutation disrupts a motif uniquely conserved in Pol IV, crippling the enzyme's ability to inhibit retrotransposon mobilization. We propose that the NRPD1 N-terminus motif evolved to regulate Pol IV function in genome surveillance.