DNA G-Quadruplex Is a Transcriptional Control Device That Regulates Memory.

The conformational state of DNA fine-tunes the transcriptional rate and abundance of RNA. Here, we report that G-quadruplex DNA (G4-DNA) accumulates in neurons, in an experience-dependent manner, and that this is required for the transient silencing and activation of genes that are critically involved in learning and memory in male C57/BL6 mice. In addition, site-specific resolution of G4-DNA by dCas9-mediated deposition of the helicase DHX36 impairs fear extinction memory. Dynamic DNA structure states therefore represent a key molecular mechanism underlying memory consolidation.One-Sentence Summary: G4-DNA is a molecular switch that enables the temporal regulation of the gene expression underlying the formation of fear extinction memory.

Fear extinction is regulated by the activity of long noncoding RNAs at the synapse.

Long noncoding RNAs (lncRNAs) represent a multidimensional class of regulatory molecules that are involved in many aspects of brain function. Emerging evidence indicates that lncRNAs are localized to the synapse; however, a direct role for their activity in this subcellular compartment in memory formation has yet to be demonstrated. Using lncRNA capture-seq, we identified a specific set of lncRNAs that accumulate in the synaptic compartment within the infralimbic prefrontal cortex of adult male C57/Bl6 mice. Among these was a splice variant related to the stress-associated lncRNA, Gas5. RNA immunoprecipitation followed by mass spectrometry and single-molecule imaging revealed that this Gas5 isoform, in association with the RNA binding proteins G3BP2 and CAPRIN1, regulates the activity-dependent trafficking and clustering of RNA granules. In addition, we found that cell-type-specific, activity-dependent, and synapse-specific knockdown of the Gas5 variant led to impaired fear extinction memory. These findings identify a new mechanism of fear extinction that involves the dynamic interaction between local lncRNA activity and RNA condensates in the synaptic compartment.

Sublithospheric diamond ages and the supercontinent cycle.

Subduction related to the ancient supercontinent cycle is poorly constrained by mantle samples. Sublithospheric diamond crystallization records the release of melts from subducting oceanic lithosphere at 300-700 km depths1,2 and is especially suited to tracking the timing and effects of deep mantle processes on supercontinents. Here we show that four isotope systems (Rb-Sr, Sm-Nd, U-Pb and Re-Os) applied to Fe-sulfide and CaSiO3 inclusions within 13 sublithospheric diamonds from Juína (Brazil) and Kankan (Guinea) give broadly overlapping crystallization ages from around 450 to 650 million years ago. The intracratonic location of the diamond deposits on Gondwana and the ages, initial isotopic ratios, and trace element content of the inclusions indicate formation from a peri-Gondwanan subduction system. Preservation of these Neoproterozoic-Palaeozoic sublithospheric diamonds beneath Gondwana until its Cretaceous breakup, coupled with majorite geobarometry3,4, suggests that they accreted to and were retained in the lithospheric keel for more than 300 Myr during supercontinent migration. We propose that this process of lithosphere growth-with diamonds attached to the supercontinent keel by the diapiric uprise of depleted buoyant material and pieces of slab crust-could have enhanced supercontinent stability.

Synapse-Enriched m6A-Modified Malat1 Interacts with the Novel m6A Reader, DPYSL2, and Is Required for Fear-Extinction Memory.

The RNA modification N6-methyladenosine (m6A) regulates the interaction between RNA and various RNA binding proteins within the nucleus and other subcellular compartments and has recently been shown to be involved in experience-dependent plasticity, learning, and memory. Using m6A RNA-sequencing, we have discovered a distinct population of learning-related m6A- modified RNAs at the synapse, which includes the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (Malat1). RNA immunoprecipitation and mass spectrometry revealed 12 new synapse-specific learning-induced m6A readers in the mPFC of male C57/BL6 mice, with m6A-modified Malat1 binding to a subset of these, including CYFIP2 and DPYSL2. In addition, a cell type- and synapse-specific, and state-dependent, reduction of m6A on Malat1 impairs fear-extinction memory; an effect that likely occurs through a disruption in the interaction between Malat1 and DPYSL2 and an associated decrease in dendritic spine formation. These findings highlight the critical role of m6A in regulating the functional state of RNA during the consolidation of fear-extinction memory, and expand the repertoire of experience-dependent m6A readers in the synaptic compartment.SIGNIFICANCE STATEMENT We have discovered that learning-induced m6A-modified RNA (including the long noncoding RNA, Malat1) accumulates in the synaptic compartment. We have identified several new m6A readers that are associated with fear extinction learning and demonstrate a causal relationship between m6A-modified Malat1 and the formation of fear-extinction memory. These findings highlight the role of m6A in regulating the functional state of an RNA during memory formation and expand the repertoire of experience-dependent m6A readers in the synaptic compartment.

Localised Cdr1as activity is required for fear extinction memory.

Circular RNAs (circRNAs) comprise a novel class of regulatory RNAs that are abundant in the brain, particularly within synapses. They are highly stable, dynamically regulated, and display a range of functions, including serving as decoys for microRNAs and proteins and, in some cases, circRNAs also undergo translation. Early work in animal models revealed an association between circRNAs and neurodegenerative and neuropsychiatric disorders; however, little is known about the link between circRNA function and memory. To address this, we examined circRNA in synaptosomes derived from the medial prefrontal cortex of fear extinction-trained male C57BL/6J mice and found 12,837 circRNAs that were enriched at the synapse, including cerebellar degeneration-related protein 1 antisense RNA (Cdr1as). Targeted knockdown of Cdr1as in the neural processes of the infralimbic cortex led to impaired fear extinction memory. These findings highlight the involvement of localised circRNA activity at the synapse in memory formation.

A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem.

Finely preserved fossil assemblages (lagerstätten) provide crucial insights into evolutionary innovations in deep time. We report an exceptionally preserved Early Triassic fossil assemblage, the Guiyang Biota, from the Daye Formation near Guiyang, South China. High-precision uranium-lead dating shows that the age of the Guiyang Biota is 250.83 +0.07/-0.06 million years ago. This is only 1.08 ± 0.08 million years after the severe Permian-Triassic mass extinction, and this assemblage therefore represents the oldest known Mesozoic lagerstätte found so far. The Guiyang Biota comprises at least 12 classes and 19 orders, including diverse fish fauna and malacostracans, revealing a trophically complex marine ecosystem. Therefore, this assemblage demonstrates the rapid rise of modern-type marine ecosystems after the Permian-Triassic mass extinction.

Milankovitch cycles in banded iron formations constrain the Earth-Moon system 2.46 billion years ago.

The long-term history of the Earth-Moon system as reconstructed from the geological record remains unclear when based on fossil growth bands and tidal laminations. A possibly more robust method is provided by the sedimentary record of Milankovitch cycles (climatic precession, obliquity, and orbital eccentricity), whose relative ratios in periodicity change over time as a function of a decreasing Earth spin rate and increasing lunar distance. However, for the critical older portion of Earth's history where information on Earth-Moon dynamics is sparse, suitable sedimentary successions in which these cycles are recorded remain largely unknown, leaving this method unexplored. Here we present results of cyclostratigraphic analysis and high-precision U-Pb zircon dating of the lower Paleoproterozoic Joffre Member of the Brockman Iron Formation, NW Australia, providing evidence for Milankovitch forcing of regular lithological alternations related to Earth's climatic precession and orbital eccentricity cycles. Combining visual and statistical tools to determine their hierarchical relation, we estimate an astronomical precession frequency of 108.6 ± 8.5 arcsec/y, corresponding to an Earth-Moon distance of 321,800 ± 6,500 km and a daylength of 16.9 ± 0.2 h at 2.46 Ga. With this robust cyclostratigraphic approach, we extend the oldest reliable datum for the lunar recession history by more than 1 billion years and provide a critical reference point for future modeling and geological investigation of Precambrian Earth-Moon system evolution.

The effect of training and workstation adjustability on teleworker discomfort during the COVID-19 pandemic.

Technological advancements have increased occupational flexibility for employees and employers alike. However, while effective telework requires planning, the COVID-19 pandemic required many employees to quickly shift to working from home without ensuring that the requirements for telework were in place. This study evaluated the transition to telework on university faculty and staff and investigated the effect of one's telework setup and ergonomics training on work-related discomfort in the at-home environment. Fifty-one percent of respondents reported increases in their existing discomfort while 24% reported new discomfort since working from home. These results suggest a need for ergonomic interventions including ergonomic training and individual ergonomic assessments for those who work from home.

Methyltrimethoxysilane (MTM) as a Reagent for Direct Amidation of Carboxylic Acids.

Methyltrimethoxysilane [MTM, CH3Si(OMe)3] has been demonstrated to be an effective, inexpensive, and safe reagent for the direct amidation of carboxylic acids with amines. Two simple workup procedures that provide the pure amide product without the need for further purification have been developed. The first employs an aqueous base-mediated annihilation of MTM. The second involves simple product crystallization from the reaction mixture providing a low process mass intensity direct amidation protocol.

Volume of Pancreas-Adjacent Operations Favorably Influences Pancreaticoduodenectomy Outcomes at Lower Volume Pancreas Centers.

OBJECTIVE: This study assesses how the volume of pancreatic-adjacent operations (PAO) impacts the outcomes of pancreaticoduodenectomy (PD). SUMMARY BACKGROUND DATA: It is well-established that regionalization benefits outcomes after PD. However, due to a multitude of factors, including geographic, financial, and personal, not all patients receive their care at high-volume pancreas surgery centers. METHODS: The National Cancer Database was queried for pancreatic cancer patients who underwent PD. Hospital volume was calculated for PD and PAO (defined as gastric, hepatic, complex biliary, or pancreatic operations other than PD) and dichotomized as low- and high-volume centers based on the median. Three study cohorts were created: low-volume hospitals (LVH) for both PD and PAO, mixed-volume hospital (MVH) with low-volume PD but high-volume PAO, and high-volume PD hospital (HVH). RESULTS: In total, 24,572 patients were identified, with 41.5%, 7.2%, and 51.3% patients treated at LVH, MVH, and HVH, respectively. Thirty-day mortality for PD was 5.6% in LVH, 3.2% in MVH, and 2.5% in HVH. On multivariable analyses, LVH was predictive for higher 30-day mortality compared to HVH [odds ratio (OR) 2.068; 95% confidence interval (CI) 1.770-2.418; P< 0.0001]. However, patients at MVH demonstrated similar 30-day mortality to patients treated at HVH (OR 1.258; 95% CI 0.942-1.680; P = 0.1203). CONCLUSIONS: PD outcomes at low-volume centers that have experience with complex cancer operations near the pancreas are similar to PD outcomes at hospitals with high PD volume. MVH provides a model for PD outcomes to improve quality and access for patients who cannot, or choose not to, receive their care at high-volume centers.

Long-term repeatability and interlaboratory reproducibility of high-precision ID-TIMS U-Pb geochronology.

Age determination of minerals using the U-Pb technique is widely used to quantify time in Earth's history. A number of geochronology laboratories produce the highest precision U-Pb dates employing the EARTHTIME 202Pb-205Pb-233U-235U tracer solution for isotope dilution, and the EARTHTIME ET100 and ET2000 solutions for system calibration and laboratory intercalibration. Here, we report ET100 and ET2000 solution data from the geochronology laboratory of University of Geneva obtained between 2008 and 2021 and compare the most recent data with results from the geochronology laboratories of Princeton University and ETH Zürich. This compilation demonstrates that (i) the choice of the thermal ionization mass spectrometer model has no influence on precision and accuracy of the data; (ii) the often observed excess scatter of apparent ET100 solution 206Pb/238U dates can be mitigated by more careful tracer-sample equilibration; and (iii) natural zircon reference materials are not suitable for evaluating intra-laboratory repeatability and inter-laboratory reproducibility, since they combine several phenomena of natural system complexities (especially domains of different age within the same zircon grain, and residual loss of radiogenic lead in domains of high decay damage after chemical abrasion pre-treatment). We provide our best estimates of apparent dates for the ET100 solution (206Pb/238U date, 100.173 ± 0.003 Ma), for ET2000 solution (207Pb/206Pb date, 1999.935 ± 0.063 Ma), as well as for natural reference zircon Temora-2 (206Pb/238U date, 417.353 ± 0.052 Ma). These data will allow U-Pb laboratories to evaluate their analytical performance and to independently calibrate non-EARTHTIME tracer solutions in use.

Silicon compounds as stoichiometric coupling reagents for direct amidation.

Despite being one of the most frequently carried out chemical reactions in industry, there is currently no amidation protocol that is regarded as safe, high yielding, environmentally friendly and inexpensive. The direct amidation of a carboxylic acid with an amine is viewed as an inherently good solution for developing such a protocol. Since the 1960s, there has been a gradual development in the use of silicon reagents for direct amidation. This review covers the methods published to April 2021 for silicon reagent mediated direct amidation of a carboxylic acid with an amine. This review also covers the use of polymeric SiO2 to promote direct amidation.

Observation of microstructure evolution during inertia friction welding using in-situ synchrotron X-ray diffraction.

The widespread use and development of inertia friction welding is currently restricted by an incomplete understanding of the deformation mechanisms and microstructure evolution during the process. Understanding phase transformations and lattice strains during inertia friction welding is essential for the development of robust numerical models capable of determining optimized process parameters and reducing the requirement for costly experimental trials. A unique compact rig has been designed and used in-situ with a high-speed synchrotron X-ray diffraction instrument to investigate the microstructure evolution during inertia friction welding of a high-carbon steel (BS1407). At the contact interface, the transformation from ferrite to austenite was captured in great detail, allowing for analysis of the phase fractions during the process. Measurement of the thermal response of the weld reveals that the transformation to austenite occurs 230 °C below the equilibrium start temperature of 725 °C. It is concluded that the localization of large strains around the contact interface produced as the specimens deform assists this non-equilibrium phase transformation.

Development of Electrochemical DNA Biosensor for Equine Hindgut Acidosis Detection.

The pH drop in the hindgut of the horse is caused by lactic acid-producing bacteria which are abundant when a horse's feeding regime is excessively carbohydrate rich. This drop in pH below six causes hindgut acidosis and may lead to laminitis. Lactic acid-producing bacteria Streptococcus equinus and Mitsuokella jalaludinii have been found to produce high amounts of L-lactate and D-lactate, respectively. Early detection of increased levels of these bacteria could allow the horse owner to tailor the horse's diet to avoid hindgut acidosis and subsequent laminitis. Therefore, 16s ribosomal ribonucleic acid (rRNA) sequences were identified and modified to obtain target single stranded deoxyribonucleic acid (DNA) from these bacteria. Complementary single stranded DNAs were designed from the modified target sequences to form capture probes. Binding between capture probe and target single stranded deoxyribonucleic acid (ssDNA) in solution has been studied by gel electrophoresis. Among pairs of different capture probes and target single stranded DNA, hybridization of Streptococcus equinus capture probe 1 (SECP1) and Streptococcus equinus target 1 (SET1) was portrayed as gel electrophoresis. Adsorptive stripping voltammetry was utilized to study the binding of thiol modified SECP1 over gold on glass substrates and these studies showed a consistent binding signal of thiol modified SECP1 and their hybridization with SET1 over the gold working electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to examine the binding of thiol modified SECP1 on the gold working electrode and hybridization of thiol modified SECP1 with the target single stranded DNA. Both demonstrated the gold working electrode surface was modified with a capture probe layer and hybridization of the thiol bound ssDNA probe with target DNA was indicated. Therefore, the proposed electrochemical biosensor has the potential to be used for the detection of the non-synthetic bacterial DNA target responsible for equine hindgut acidosis.

Symptomatic Diaphragmatic Hernia after Thoracofemoral Bypass.

Despite its relative underutilization in the primary management of aortoiliac occlusive disease, thoracofemoral bypass is an attractive extra-anatomic surgical option in select patients. Thoracofemoral bypass classically entails passing a graft from the left chest into the retroperitoneal space through a small opening created in the diaphragm. While theoretically possible that this maneuver may predispose to a peri-graft diaphragmatic hernia, currently there are no cases of this complication reported in the literature, nor has its surgical repair been described. This case illustrates the rare complication of symptomatic diaphragmatic hernia following a thoracobifemoral bypass.

Use of a Laparoscopic Witzel Gastrostomy Without Gastropexy in Bariatric and General Surgery.

BACKGROUND: Gastrostomy placement is the preferred means of long-term enteral feeding for patients who cannot eat by mouth. During laparoscopic gastrostomy, it is standard to perform gastropexy, apposing visceral and parietal peritoneum. In some settings, due to altered anatomy from prior surgery, direct apposition of the stomach to the abdominal wall is not possible. This study reports a series of cases where laparoscopic gastrostomy was performed via a Witzel approach without gastropexy. METHODS: A retrospective chart review was performed of all patients at a tertiary academic medical center who underwent Witzel gastrostomy without gastropexy over a 3-year period. In each case, an 18-French tube was placed into the fundus of the stomach and secured with a purse-string suture. A 5-cm serosalized Witzel tunnel was created around the tube using running silk suture. No gastropexy was performed. RESULTS: Six patients underwent 7 Witzel gastrostomy procedures. In three cases, patients had undergone prior major upper abdominal surgery where adhesive disease prevented gastropexy. In the other four cases, the patients had undergone prior gastric bypass with antecolic antegastric position of the roux limb. No patient suffered leak of gastric contents into the peritoneum, and there were no postoperative complications or mortality related to the gastrostomy. CONCLUSION: In cases where enteral access is necessary, and where the stomach cannot reach the anterior abdominal wall for gastropexy due to prior surgeries, a Witzel gastrostomy without gastropexy is a safe option which resulted in no morbidity or mortality in our series.

Anchoring the Late Devonian mass extinction in absolute time by integrating climatic controls and radio-isotopic dating.

The Devonian Frasnian-Famennian (F-F) boundary marks one of the five main extinction intervals of the Phanerozoic Aeon. This time was characterized by two pulses of oceanic anoxia, named the Lower and Upper Kellwasser events, during which massive marine biodiversity losses occurred. This paper presents high-resolution magnetic susceptibility, X-ray fluorescence elemental geochemistry and carbon isotope datasets obtained from the Steinbruch Schmidt F-F boundary section (Germany). These records lead to an astronomical time calibration of the environmental changes associated with the two ocean anoxia pulses. Cyclostratigraphic interpretation indicates deposition of the black argillaceous Lower and Upper Kellwasser horizons over ~ 90 and ~ 110 kyr, respectively; approximately equivalent to the duration of one short eccentricity cycle. This study confirms that the succession of events within the Upper Kellwasser event is paced by obliquity, under a low-eccentricity orbit. Hence, astronomical insolation forcing likely contributed to the expansion of ocean anoxia and other environmental perturbations associated with these two crises. The new floating chronology established for the Steinbruch Schmidt section is anchored in numerical time by means of a radio-isotopic date, obtained from a bentonite layer interbedded between the two Kellwasser horizons. After anchoring, this time scale gives a high-precision age of 371.870 ± 0.108 Ma for the F-F boundary.

Top Quark Mass Effects in Higgs Boson Production at Four-Loop Order: Virtual Corrections.

We compute four-loop corrections to the Higgs boson gluon vertex, including finite top quark mass effects. Analytic results are presented which serve as a building block for the next-to-next-to-next-to-leading order corrections to Higgs boson production at the Large Hadron Collider at CERN.

Gauge Coupling ß Functions to Four-Loop Order in the Standard Model.

We compute the ß functions of the three standard model gauge couplings to four-loop order in the modified minimal subtraction scheme. At this order a proper definition of γ_{5} in D=4-2ε space-time dimensions is required; however, in our calculation we determine the γ_{5}-dependent terms by exploiting relations with ß function coefficients at lower loop orders.