In situ structure and priming mechanism of the rhoptry secretion system in Plasmodium revealed by cryo-electron tomography

Apicomplexan parasites secrete the contents of rhoptries into host cells to permit their invasion and establishment of an infectious niche. The rhoptry secretory apparatus (RSA), which is critical for rhoptry secretion, was recently discovered in Toxoplasma and Cryptosporidium. It is positioned at the cell apex and associates with an enigmatic apical vesicle (AV), which docks one or two rhoptries at the site of exocytosis. The interplay among the rhoptries, the AV, and the parasite plasma membrane for secretion remains unclear. Moreover, it is unknown if a similar machinery exists in the deadly malaria parasite Plasmodium falciparum. In this study, we use in situ cryo-electron tomography to investigate the rhoptry secretion system in P. falciparum merozoites. We identify the presence of an RSA at the cell apex and a morphologically distinct AV docking the tips of the two rhoptries to the RSA. We also discover two new organizations: one in which the AV is absent with one of the two rhoptry tips docks directly to the RSA, and a second in which the two rhoptries fuse together and the common tip docks directly to the RSA. Interestingly, rhoptries among the three states show no significant difference in luminal volume and density, suggesting that the exocytosis of rhoptry contents has not yet occurred, and that these different organizations likely represent sequential states leading to secretion. Using subtomogram averaging, we reveal different conformations of the RSA structure corresponding to each state, including the opening of a gate-like density in the rhoptry-fused state. These conformational changes of the RSA uncover structural details of a priming process for major rhoptry secretion, which likely occur after initial interaction with a red blood cell. Our results highlight a previously unknown step in the process of rhoptry secretion and indicate a regulatory role for the conserved apical vesicle in host invasion by apicomplexan parasites.

Semantic relation priming is not constituent-specific: Evidence from ERP

It is humankind's unique wisdom to compose a limited number of words together through specific rules to convey endless information. Researchers have found that this composition process also plays a vital role in the comprehension of compounds. The specific manifestation is relation priming; that is, the previously used relation will promote subsequent word processing using the same relation. This priming phenomenon is bound to morpheme repetition (modifier or head). This study combines a self-paced priming paradigm with electrophysiological technology to explore whether relation priming will occur without sharing morphemes and its time course. We found that relation priming can occur independently of morpheme-repetition, which shows an independent representation of relation information. And it has been activated at a very early stage (about 200ms). As the word processing progresses, this activation gradually strengthens, indicating that the relation's role is slowly increasing in the process of compound word recognition. It may first be used as a kind of context information to help determine the constituent morphemes' meaning. After the meaning access of the constituent morphemes, they begin to play a role in the semantic composition process. This study uses electrophysiological technology to precisely describe the representation of relation and its time course for the first time. Which gives us a deeper understanding of the relation priming process, and at the same time, sheds light on the meaning construction process of compounds.

Automation of Seed Priming Technology for Enhanced Seed Vigour of Blackgram Seeds

Background: Seed priming technique involves soaking of seeds in priming agent to a point where germination related metabolic activities occur in the seeds followed by drying of imbibed seeds to original moisture to prevent the radical protrusion and facilitate storage of primed seed. Draining of priming agent and drying of large quantity of primed seeds is a laborious and time consuming process. The current study was aimed to standardize automation of seed priming process by utilizing house-hold top loading washing machine. Methods: The top loading washing machine referred to as Seed Priming Cabinet, contained a priming drum with provision for draining water. On completion of the soaking period, the ‘SPIN’ button was pressed by setting the duration of spin drying (1, 2, 3, 4 and 5 min.). Then the seeds were removed from the drum of priming cabinet and subjected to shade drying so as to reach the original moisture content and evaluated for seed quality parameters. Result: The blackgram seed subjected to conventional hydropriming was compared with automatic seed priming for 1, 2, 3, 4 and 5 min. and observed that hydropriming and spin drying for 3 min. was found to be optimum and the per cent increase in germination recorded over control was 18.0 per cent thus suggesting that automation of seed priming technology can be recommended for enhanced seed vigour and crop productivity of blackgram.

A prior exposure to Serratia marcescens or xenobiotics primes Drosophila enterocytes against a recurring cytoplasmic purge

The cytoplasmic extrusion of enterocytes is a fast response to an exposure to pore-forming toxin (PFT)-producing bacteria whereby their apical cytoplasm is extruded into the intestinal lumen. As a result of this purge, the intestinal epithelium becomes thin prior to a subsequent recovery. We report here that the ingestion of ethanol or caffeine induces a similar response, which suggests that a common purging process is triggered by bacterial toxins and abiotic toxicants. We also delineate an additional mechanism that is initiated by these stimuli that we refer to as priming. The initial exposure of the intestinal epithelium to either PFT or xenobiotics protects enterocytes against a further round of purging upon a second bacterial infection. Priming prevents the epithelium from being persistently thin in the context of chronic intestinal infections. We have identified the upper part of the p38b MAPK pathway as well as the homeobox-containing transcription factors E5/EMS as being required for priming and not for the regrowth of enterocytes after the cytoplasmic purge. Unexpectedly, the priming process appears to function cell-nonautonomously. Our findings suggest that the cytoplasmic purge extrusion has been selected because it constitutes a fast reaction to accidental exposure to bacterial toxins or toxicants.

Dysregulated long noncoding RNAs in the brainstem of the DBA/1 mouse model of SUDEP

Background Long noncoding RNAs (lncRNAs) play an important role in many neurological diseases. This study aimed to investigate differentially expressed lncRNAs and messenger RNAs (mRNAs) in the susceptibility gaining process of primed DBA/1 mice, a sudden unexpected death in epilepsy (SUDEP) model, to illustrate the potential role of lncRNAs in SUDEP. Methods The Arraystar mouse lncRNA Microarray V3.0 (Arraystar, Rockville, MD) was applied to identify the aberrantly expressed lncRNAs and mRNAs between primed DBA/1 mice and normal controls. The differences were verified by qRT-PCR. We conducted gene ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and coexpression analyses to explore the possible function of the dysregulated RNAs. Results A total of 502 lncRNAs (126 upregulated and 376 downregulated lncRNAs) and 263 mRNAs (141 upregulated and 122 downregulated mRNAs) were dysregulated with P < 0.05 and a fold change over 1.5, among which Adora3 and Gstt4 were possibly related to SUDEP. GO analysis revealed that chaperone cofactor-dependent protein refolding and misfolded protein binding were among the top ten downregulated terms, which pointed to Hspa1a, Hspa2a and their related lncRNAs. KEGG analysis identified 28 upregulated and 10 downregulated pathways. Coexpression analysis showed fifteen dysregulated long intergenic noncoding RNAs (lincRNAs) and three aberrantly expressed antisense lncRNAs, of which AK012034 and NR_040757 are potentially related to SUDEP by regulating LMNB2 and ITPR1, respectively. Conclusions LncRNAs and their coexpression mRNAs are dysregulated in the priming process of DBA/1 in the brainstem. Some of these mRNAs and lncRNAs may be related to SUDEP, including Adora3, Lmnb2, Hspa1a, Hspa1b, Itrp1, Gstt4 and their related lncRNAs. Further study on the mechanism of lncRNAs in SUDEP is needed.

Gibberellic Acid Biosynthesis During Dehydration Phase of Priming Increases Seed Vigour of Tomato

Priming of seed is intended to reduce the time to germination through activation of pre-germinative processes. Seed priming is controlled hydration and followed by a drying (dehydration) process. The physiological processes during hydration (imbibition) were studied in detail in tomato. In contrast, gibberellic acid (GA) changes during the dehydration phase were not studied in detail. We hypothesize that there would be a change in the GA concentration during the dehydration phase of the seed priming process, which may influence the vigour characteristics of the resultant seedling. The objective was to understand the influence dehydration phase of seed priming on GA biosynthesis and its subsequent effect on seed germination and seedling traits of tomato. First, the hydroprimed and unprimed seeds were re-imbibed for 3, 6, 9, and 12 h to initiate the germination process, and the GA concentration and seedling vigour associated parameters were recorded. In the second experiment, the imbibed seeds were dehydrated for 3, 6, 9, and 12 h, then re-imbibed for 3, 6, 9, and 12 h to understand the effect of dehydration on the GA concentration and its associated traits. Results revealed that hydroprimed seeds had a higher GA concentration and seedling vigour than unprimed seeds. The seeds that are completely dehydrated for 12 h had the highest GA and seed vigour parameters. Therefore, increased vigour of hydroprimed seeds is due to the higher levels of GA accumulated during the dehydration phase of seed priming, which can improve seed germination and seedling vigour of tomato.

MO665THE BRAND-NEW NEEDLE CAP ELIMINATES ALL VISIBLE AIR BUBBLES DURING THE AUTOMATIC PRIMING PROCESS OF HEMODIALYSIS MACHINES

Background and Aims The air contamination from the dialysis circuit into the patient's body is an unsolved serious problem. Recently, Automatic priming function of dialysis machines is widely used. There are rarely any air bubbles left in the extracorporeal circuit after automatic priming of the dialysis machines. To use this method, the arterial and venous sides of the extracorporeal circuit are connected to create a closed circuit so that dialysate can circulate and overflowed through a line from this closed circuit. However, air bubbles may enter when disconnecting the closed extracorporeal circuit and attaching the needles. We tried to solve this problem by simply connecting the arterial and venous needles to the extracorporeal closed circuit before the process of automatic priming process. To prime the whole extracorporeal circuit with needles, we had made a brand-new suitable cap of the needle, which is tightly connected with a needle and has an open end. (Fig) This special cap allows the needle to be incorporated into the closed circuit prior to the automatic priming process, allowing the dialysis machine to completely remove the air during priming process. The purpose of this study is to present the details of this new method and compare its effectiveness in preventing air bubble contamination between the traditional method and this new method. Method A prospective, non-randomized, comparative study was conducted to verify whether air remained grossly visible after the needle was connected to the extracorporeal circuit. The traditional method: DCS-100NX (Nikkiso Co Ltd, Tokyo Japan) was used for extracorporeal circuit priming. After the automatic priming was finished. Nurses disconnect the arterial and venous side of the extracorporeal circuit and connect both ends to the needles by hands. The nurse operates the dialysis machine to blow the small amount of dialysate out of the needle and tried to remove the air. It takes nearly 2minutes in each case. We examined the extracorporeal circuits consecutively. New cap-based method: The needles were connected to the closed circuit with the new cap and auto-primed by the dialysis machine N100. Automatic priming, including the needle were performed consecutively. In each method, we thoroughly checked for any remaining macro bubbles with the naked eye. Since bubbles in the extracorporeal circuit on the arterial side are likely to be supplemented by the air trap chamber, only bubbles on the venous side were compared. Results The study was conducted in October 15th to 24th 2020 at the Yokohama Minami Clinic. The traditional method: We checked 50 extracorporeal circuits consecutively. There were bubbles in the venous side of the extracorporeal circuits 29 times out of 50 times. New cap-based method: 10 consecutive automatic priming, including the needle was performed. DCS-100NX was used as the dialysis machine. There were no bubbles visible to the naked eye in the arterial and venous side of the circuit. Statistical Results There was a statistically significant difference of the bubble count between the traditional method and new cap-based method. (p=0.0001, Pearson's chi-square test) Conclusion All visible bubbles were removed automatically by simply connecting the needles using this brand-new cap before a process of automatic priming. This easy-to-use and highly effective cap could be considered an essential device for hemodialysis treatment like seat belts in automobiles.

Evaluation of the Octreotide Acetate Pen Injector in a Formative Human Factors Study

Introduction: Subcutaneous injection of octreotide acetate is indicated to treat adults with acromegaly and diarrhea associated with carcinoid tumors or vasoactive intestinal peptide tumors. In this formative human factors study, we evaluated the readability and comprehension of the instructions for use (IFU) and ease of use of the octreotide pen injector. Methods: The study enrolled patients and healthcare practitioners who would be using the pen injector. The IFU contained a stepwise process with illustrations to detail injection administration and safe storage of the octreotide pen injector. Participants read the IFU and familiarized themselves with the device. Participants administered 2 unaided injections into skin-like pads. Injection success was defined as an attempt that delivered the correct dose into the pad. Each injection was evaluated by objective performance and subjective measures. Objective performance measures included assessment of steps necessary to deliver the correct medication dose and ensure user safety. Subjective measures included soliciting participant feedback on perceived success and difficulties administering a dose with the octreotide pen injector, as well as suggestions for improvements. Additional goals included evaluation of the IFU and octreotide pen injector usability aspects. Results: A total of 8 patients and 3 healthcare practitioners enrolled in the study. All (n = 11) participants successfully administered both injections, leading to an overall injection success rate of 100% across twenty-two injections. Subtask errors included participants priming the pen injector with the incorrect dose (n = 1) and not holding the injection button for 10 seconds after the injection (n = 2), but neither error resulted in dosing failure. Participant suggestions for improving the IFU included changes to the illustration of the plunger, reordering statements to clarify the priming process, and detailing how long to let the pen injector come to room temperature. Conclusion: Overall, participants felt the octreotide pen injector was easy to use and the instructions were clearly written and illustrated. Participant feedback and observations by moderators of the study led to recommendations for improvements to the clarity of the IFU.

Priming Strategies for Benefiting Plant Performance under Toxic Trace Metal Exposure

Combating environmental stress related to the presence of toxic elements is one of the most important challenges in plant production. The majority of plant species suffer from developmental abnormalities caused by an exposure to toxic concentrations of metals and metalloids, mainly Al, As, Cd, Cu, Hg, Ni, Pb, and Zn. However, defense mechanisms are activated with diverse intensity and efficiency. Enhancement of defense potential can be achieved though exogenously applied treatments, resulting in a higher capability of surviving and developing under stress and become, at least temporarily, tolerant to stress factors. In this review, I present several already recognized as well as novel methods of the priming process called priming, resulting in the so-called “primed state” of the plant organism. Primed plants have a higher capability of surviving and developing under stress, and become, at least temporarily, tolerant to stress factors. In this review, several already recognized as well as novel methods of priming plants towards tolerance to metallic stress are discussed, with attention paid to similarities in priming mechanisms activated by the most versatile priming agents. This knowledge could contribute to the development of priming mixtures to counteract negative effects of multi-metallic and multi-abiotic stresses. Presentation of mechanisms is complemented with information on the genes regulated by priming towards metallic stress tolerance. Novel compounds and techniques that can be exploited in priming experiments are also summarized.