Secondary Imprinting Research Articles

Dual-Mode Patterns Enabled by Photofluidization of an Azobenzene-Containing Linear Liquid Crystal Copolymer.

Creating dual-mode patterns in the same area of the material is an advanced method to increase the dimension of information storage, improve the level of encryption security, and promote the development of encoding technology. However, in situ, different patterns may lead to serious mutual interference in the process of manufacturing and usage. New materials and patterning techniques are essential for the advancement of noninterfering dual-mode patterns. Herein, noninterfering dual-mode patterns are demonstrated by combining the structural color and chromatic polarization, which is designed with an azobenzene-containing linear liquid crystal copolymer featuring a photofluidization effect. On the one hand, structural color patterns are imprinted via silicon templates with periodic microstructures after a UV-light-induced local transition of the polymer surface from a glassy to rubbery state. On the other hand, different polarization patterns based on the local photoinduced orientation of mesogens are created within the photofluidized region by the Weigert effect. Especially, the secondary imprinting is used to eliminate the partial damage to the structural color patterns during writing of the polarization patterns, thus obtaining dual-mode patterns without interference. This study provides a blueprint for the creation of advanced materials and sophisticated photopatterning techniques with potential cross-industry applications.

Precise selection and separation of ribavirin by nanoconfined imprinted MOFs membrane

Metal-organic frameworks (MOFs) are highly tunable materials with potential as porous media in membrane separations. However, traditional MOFs are usually not specific and selective. Here, we demonstrate a nanocomposite molecularly imprinted MOFs membrane material that can selectively adsorb and separate specific molecules. We demonstrated this adsorption-separation mechanism by introducing ribavirin molecules into multicomponent MOFs by molecular imprinting strategy and performing permeation and dynamic permeation tests. Due to the previously formed nanocages with a specific structure inside the MOFs, combined with the synergistic effect of the subsequent secondary imprinting, excellent selectivity (more than 6) and effective adsorption (46.46 mg g−1) were displayed by the obtained imprinted membrane. The stability of the membrane was measured by the process of dynamic osmosis, and the results showed that the membrane always had a large factor of separation (greater than 7). The experimental results and conclusions of this paper provide new theoretical and practical support for solving the key scientific issues of the “trade-off” effect between the permeation flux and permeation selectivity of template molecules in the traditional molecularly imprinted membranes (MIMs) osmotic separation process.

Natural Tissue-Imprinted Biointerface for the Topographical Education of a Biomimetic Cell Sheet.

Cell sheet engineering as a cell-based scaffold-free therapy is promising in tissue engineering, allowing precise transforming treatments for various tissue damage. However, the current cutting-edge techniques are still hampered by the difficulty in mimicking the natural tissue organizations and the corresponding physiological functions. In this work, cell-imprinting technology using the natural tissue as a template was proposed to rationally educate the cellular alignment in the cell sheet. Through this technique, we obtained temporary templates with morphological structure complementary to native tissues and then directly transferred the structure on the template to the collagen layer on a photothermally convertible substrate by secondary imprinting replication. The resultant biomimetic interface was used for cell culture and release to obtain a cell sheet with a texture similar to the natural tissue morphology. Different from conventional photolithography, the natural tissue-imprinted biointerface guides the geometry of cell sheets in the way of natural principles instead of stereotyped or overuniform cell organization. Simultaneously, a near-infrared laser (NIR) was used to irradiate the photothermally responsive substrate to obtain complete cell sheets efficiently and nondestructively. The natural tissue-educated myocardium cell sheets exhibited good physiological activity and biomimetic biofunctions, such as mechanical properties and physiological performances. This approach might open an inspiring prospect in regenerative medicine and offer a new approach to realizing the biomimetic tissue construction.

Smchd1 is a maternal effect gene required for genomic imprinting.

Genomic imprinting establishes parental allele-biased expression of a suite of mammalian genes based on parent-of-origin specific epigenetic marks. These marks are under the control of maternal effect proteins supplied in the oocyte. Here we report epigenetic repressor Smchd1 as a novel maternal effect gene that regulates the imprinted expression of ten genes in mice. We also found zygotic SMCHD1 had a dose-dependent effect on the imprinted expression of seven genes. Together, zygotic and maternal SMCHD1 regulate three classic imprinted clusters and eight other genes, including non-canonical imprinted genes. Interestingly, the loss of maternal SMCHD1 does not alter germline DNA methylation imprints pre-implantation or later in gestation. Instead, what appears to unite most imprinted genes sensitive to SMCHD1 is their reliance on polycomb-mediated methylation as germline or secondary imprints, therefore we propose that SMCHD1 acts downstream of polycomb imprints to mediate its function.

A modified trace metal detection test for secondary imprints on porous substrates: A preliminary study

In the investigation of criminal cases involving metallic weapons such as firearms and knives, the trace metal detection test (TMDT) and the transfer detection technique are two effective and on-the-spot methods to link a suspect and a suspected metallic weapon. In general, these tests need to be conducted on suspects’ hands or done by lifting trace metals from their hands within 3 days of the crime being committed. However, if no suspects are arrested within this period, neither of these two techniques is applicable.This paper presents preliminary development of a modified TMDT to overcome the intrinsic disadvantages of conventional TMDTs. The method primarily focuses on the secondary imprints on porous substrates that are transferred unconsciously from the palms of criminals after handling galvanized weapons. The modified TMDT was established by studying the effect of various factors on secondary imprints on porous substrates. We also tested the effectiveness of the modified TMDT for common porous substrates and galvanized weapons and its relative sensitivity in a depletion series. Additionally, the storage conditions of the developed secondary imprints as physical evidence were studied under different time lapses and light conditions. Finally, we proposed an improved procedure for detecting metal traces formed in the use of metallic weapons and subsequent activities at a crime scene.The modified TMDT provides a novel method for investigators to demonstrate the relationship between a suspect and a metallic weapon, thus reducing the heavy reliance of conventional TMDTs on suspects and the time limit available to visualize or lift metal traces. For this reason, it can be used as a complementary and remedial method for conventional TMDTs, especially when suspects are not arrested within 3 days of the commission of a crime. Furthermore, the improved procedure can serve as a guide for investigators to apply the TMDT series properly to solving the cases involving metallic weapons.

A versatile strategy to fabricate dual-imprinted porous adsorbent for efficient treatment co-contamination of λ-cyhalothrin and copper(II)

Smart absorbents with high affinity to specific toxicant, especially with multi-affinity to both metal ions and organic pollutants, are very appealing for the treatment of heavy metal and organic co-contaminated water. A versatile strategy based on Pickering high internal phase emulsions (HIPEs) and controllable pore-filled technique was reported to fabricate molecule and ion dual-imprinted polymer adsorbent (M/I-DIPA). 2-Bromoisobutyryl bromide (BIBB)-modified silica nanoparticles (MSPs) were firstly employed to form Pickering HIPEs template, and then it was used to prepare λ-cyhalothrin (LC)-imprinted polymer foam (MIPA). Secondly, surface-initiated atom transfer radical polymerization (SI-ATRP) was adopted to controllably produce Cu(II)-imprinted adsorbent onto the MSPs which firmly “locked” in the MIPA shell. As-prepared M/I-DIPA effectively avoids the burying of recognition sites in a secondary imprinting process, and possesses highly permeable macroporous morphology. In batch mode experiments, M/I-DIPA exhibits fast binding kinetics (i.e. 60min), and the maximum monolayer adsorption amount from Langmuir model for LC and Cu(II) are 120.8µmolg−1 and 101.7µmolg−1 at 35°C, respectively, indicating this strategy makes the defined imprinted cavities well protected in twice imprinting steps. Moreover, LC and Cu(II) have both higher imprinting factor α (about two times) than the other structural analogues, and the excellent selectivity coefficient β in multi solute system also demonstrates the preferential affinity to templates (i.e. LC and Cu(II)) due to a good imprinting effect. The loss in adsorption amounts of M/I-DIPA for LC and Cu(II) at 120min after four regeneration cycles are 7.295% and 13.05%, respectively, illustrating good retention of the activity of M/I-DIPA.

TECTONIC SETTING AND DEFORMATION OF THE KALLIDROMO MT, CENTRAL GREECE

Kallidromo Mt. consists of alpine formations which in places are unconformably covered by Neogene and Quaternary sediments. The ophiolites are overthrusted on the massive Mesozoic platform carbonate sequence, which forms the basement unit. The base of the tectonic nappe is characterized by a tectonic melange that consists of sandstones, clay stones, limestones, cherts and basaltic rocks that are mainly observed in pillow forms. Two distinct compressional deformation phases (D1, D2) are traced. Deformation D1 whereas the fold axes, the predominant schistocity planes and shear zones clearly follow a N295o (±10o )-115o (±10o ) trend that relates to the Upper Jurrasic-Lower Cretaceous ophiolitic emplacement of the Eo-alpine orogeny and is the predominant feature over the entire study area. Deformation D2 relates to the Cretaceous-Eocene alpine orogeny, follows a N020o (±15o )-N200o (±15o ) trend and has a much weaker and secondary imprint in the study area. The tectonic study of the alpine and post-alpine formations shows a complex deformation pattern with a variety of quantitative and qualitative characteristics. These variations can be correlated with different phases and stages of deformation (compressional to extensional) from the timing of the tectonic emplacement of the ophiolites inUpperJurrasic-Lower Cretaceous up to the present-day field.

Simulated maternal care facilitates the formation of filial imprinting in domestic chicks

The potential effects of maternal care-related stimuli on imprinting in domestic chicks were examined. In the first phase, one group of chicks received a simulated brooding experience with a primary imprinting object during two training sessions, whereas chicks in another group received exposure to the object without being brooded. In subsequent testing, the brooded chicks showed a robust preference for the primary imprinting object, whereas the non-brooded chicks showed a weaker preference for the object. In the second phase, one group of chicks was exposed to a secondary imprinting object associated with a feeding opportunity, whereas another group received exposure to the object in the absence of such an experience. In subsequent testing, the fed chicks showed a strong preference for the secondary imprinting object, whereas the non-fed chicks showed no preference. These results suggest that stimuli experienced through usual maternal care may be an important factor in filial imprinting.

Differential steric effects in Cl reactions with aligned CHD3(v1 = 1) by the R(0) and Q(1) transitions. II. Abstracting the unexcited D-atoms.

A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism. The extent of steric effects is moderate and relatively smaller than the alternative H-atom abstraction channel. All major findings reported here can qualitatively be understood by first noting that the present reaction invokes abstracting a D-atom, which is the spectator in the IR-excitation process. Next, it is recognized that the directional properties of two polarized states of CHD3(v1=1, jK) should manifest primarily in the IR-excited C-H bond, leaving secondary imprints in the unexcited CD3-moiety. The stereo-specificity of the DCl + CHD2 product channel is further reduced by the fact that the abstraction can occur with any one of the three spatially distinct D-atoms.

Microscopic properties of a nanocrystal aluminum thin film during nanoimprint using quasi-continuous method

In this article, we perform a multi-scale simulation of nanoimprint on a single-crystal aluminum thin film using the quasi-continuous method. The effects of contact stiffness between the stamper, thin film, and imprint orientation on the microstructure of the nanocrystal aluminum are examined. Results show that for a smaller value of contact stiffness, plastic deformation occurs relatively late. However, early plastic deformation is found when the stamper imprints perpendicular to the plane (111). In addition, to explore the effect of offset on the microstructure of a single-crystal aluminum thin film during the multi-imprint process, we perform a secondary imprint with an imprint depth of 10Å. The effect of the first nanoimprint process on the secondary process can be found to be negligible when the offset is larger than 100Å. However, we do not obtain a good pattern for a 50-Å offset. Therefore, for simulation cases, we suggest that the appropriate offset between the two imprints is 100Å.

TRIM28 Controls Genomic Imprinting through Distinct Mechanisms during and after Early Genome-wide Reprogramming.

Genomic imprinting depends on the establishment and maintenance of DNA methylation at imprinting control regions. However, the mechanisms by which these heritable marks influence allele-specific expression are not fully understood. By analyzing maternal, zygotic, maternal-zygotic, and conditional Trim28 mutants, we found that the transcription factor TRIM28 controls genomic imprinting through distinct mechanisms at different developmental stages. During early genome-wide reprogramming, both maternal and zygotic TRIM28 are required for the maintenance of methylation at germline imprints. However, in conditional Trim28 mutants, Gtl2-imprinted gene expression was lost despite normal methylation levels at the germline IG-DMR. These results provide evidence that TRIM28 controls imprinting after early embryonic reprogramming through a mechanism other than the maintenance of germline imprints. Additionally, our finding that secondary imprints were hypomethylated in TRIM28 mutants uncovers a requirement of TRIM28 after genome-wide reprogramming for interpreting germline imprints and regulating DNA methylation at imprinted gene promoters.

Fabrication of complex nanostructures of Poly(vinylidenefluoride-trifluoroethylene) by dual step hot-embossing

In this work, complex 3D ferroelectric nanostructures have been successfully fabricated on Poly(vinylidenefluoride-trifluoroethylene), P(VDF-TrFE), thin films using a special hot-embossing process with two sequential shots on the same site with a grating template and a rounded square array template at the same hot-embossing temperature. The nanostructures have been characterized with scanning electron microscopy, atomic force microscopy and piezoresponse force microscopy, respectively. It is shown that sequential hot-embossing offers an effective way to create complex structures for functional ferroelectric materials by conducting secondary or tertiary imprinting toward various applications, including mass production of ferroelectric devices such as nonvolatile memories, photonics, bionic structure and surface wetting.

Recessed area patterning via nanoimprint lithography

Three-dimensional structures in the channels of a patterned substrate are typically fabricated via a variety of approaches that include a combination of soft lithography and multiple photolithographic steps which can be complex and time consuming. Moreover, the design of a three-dimensional hierarchical template to carry out the direct recessed imprinting of polymers at the recessed area would be complicated and costly. To overcome this shortcoming, we report a method to fabricate a three-dimensional template that is capable of carrying out a direct recessed area imprint via the use of a polymer material. A sequential nanoimprinting process was used to first fabricate the template. A primary imprint was carried out to emboss micron-sized primary features onto a polymer template after which a secondary imprinting process was then carried out to imprint smaller nanoscale features onto the primary features thereby creating three-dimensional or hierarchical features on the polymer template. The template with ...

Mechanisms of imprint dysregulation

Genomic imprinting is an epigenetic process by which the male and the female germ line confer specific marks (imprints) onto certain gene regions, so that one allele of an imprinted gene is active and the other allele is silent. Genomic imprints are erased in primordial germ cells, newly established during later stages of germ cell development, and stably inherited through somatic cell divisions during postzygotic development. Defects in imprint erasure, establishment, or maintenance result in a paternal chromosome carrying a maternal imprint or in a maternal chromosome carrying a paternal imprint. A wrong imprint leads to activation of an allele that should be silent or silencing of an allele that should be active. Since the dosage of imprinted genes is very important for development and growth, imprinting defects lead to specific diseases. Imprinting defects can occur spontaneously without any DNA sequence change (primary imprinting defect) or as the result of a mutation in a cis-regulatory element or a trans-acting factor (secondary imprinting defect). The distinction between primary and secondary imprinting defects is important for assessing the recurrence risk in affected families.

A recurrent intragenic genomic duplication, other novel mutations in NLRP7 and imprinting defects in recurrent biparental hydatidiform moles

A complete hydatidiform mole (CHM) is an abnormal pregnancy with hyperproliferative vesicular trophoblast and no fetal development. Most CHM are sporadic and androgenetic, but recurrent HM have biparental inheritance (BiHM) with disrupted DNA methylation at differentially methylated regions (DMRs) of imprinted loci. Some women with recurrent BiHM have mutations in the NLRP7 gene on chromosome 19q13.42. Using bisulfite genomic sequencing at eight imprinted DMRs on DNA from two BiHMs, we found a pattern of failure to acquire or maintain DNA methylation at DMRs (PEG3, SNRPN, KCNQ1OT1, GNAS exon 1A) that normally acquire CpG methylation during oogenesis, but not at H19, which acquires CpG methylation during spermatogenesis. Secondary imprints at the GNAS locus showed variable abnormal patterns with both gain and loss of CpG methylation. We found novel missense and splice-site mutations in NLRP7 in women with non-familial recurrent BiHM. We identified and characterized a homozygous intragenic tandem duplication including exons 2 through 5 of NLRP7 that results in a predicted truncated protein in affected women of three unrelated Egyptian kindreds, suggesting a founder effect. Our findings firmly establish that NLRP7 mutations are a major cause of BiHM and confirm presence of a complex pattern of imprinting abnormalities in BiHM tissues.

Artificial protein sensors

Protein recognition by synthetic molecules is a challenging endeavour, since these materials must bind to a large relatively flat surface domain and recognize a unique distribution of amino acid residues of varying charge, size and shape. The most promising routes involve specific metal coordination, epitope-docking on miniature proteins, aptamer selection, nonnatural peptide isosteres, functionalized platforms, secondary structure mimetics, molecular imprinting and receptors embedded in lipid layers.

The effects of early post-hatching changes of imprinting object on the pattern of monocular/unihemispheric sleep of domestic chicks

The pattern of monocular/unihemispheric sleep (Mo–Un sleep) was studied behaviourally in male and female chicks after early post-hatching changes of the imprinting object. Chicks were reared with an imprinting object on day 1 post-hatching which was removed or changed on day 2. On day 1, time spent in binocular sleep (both eyes closed) was similar in male and female chicks, though the number of episodes was lower in females than in males. There was no eye-closure bias in the pattern of Mo–Un sleep (one eye shut and the other open) in chicks of both sexes. On day 2, chicks subjected to the removal of imprinting object showed less time and number of episodes of binocular sleep than control chicks and chicks subjected to changes of imprinting object. There was no eye-closure bias in control chicks whilst a significant bias for more right Mo–Un sleep was recorded in chicks after removal and changes of imprinting object of both sexes. It is suggested that the removal or changes of imprinting object would cause a decrease of binocular sleep and trigger processes associated to secondary imprinting involving the left hemisphere. The bias for more right Mo–Un sleep (right eye-closure) could be the by-product of consolidation processes of secondary imprinting memories in the left hemisphere and/or of more left eye-opening as a result of periodical awakening of right hemisphere to control the environment after a stressful condition such as the removal or change of imprinting object.

Visual lateralisation, form preferences, and secondary imprinting in the domestic chick

Newly hatched chicks (Exp. 1) were exposed to an imprinting object of a certain shape (sphere/cylinder) on Day 1 (primary imprinting) and then to a different-shaped object (cylinder/sphere) on Day 2 (secondary imprinting). They were tested on Day 3 for preferences between primary and secondary imprinting objects in binocular and monocular conditions. Right-eyed males, but not females, showed relatively stronger preferences for the primary imprinting object than left-eyed males; however, the asymmetry was modulated by a spontaneous preference for the sphere. In Experiment 2, a more traditional imprinting paradigm was used: chicks were exposed to the same object for the first 2 days, and on Day 3 underwent a free-choice test between the imprinting object (sphere/cylinder) and a novel one (cylinder/sphere). Results showed that no asymmetries in the use of eyes were apparent, only a general preference for the sphere. In Experiment 3 chicks were exposed, as in Experiment 1, to a primary (Day 1) and a secondary (Day 2) imprinting object; on Day 3 they were exposed to both objects simultaneously; they were also tested for preferences for the two stimuli on Day 4. Left- and right-eyed chicks showed different choice, with the latter preferring the cylinder, thus showing that the eye-asymmetry was in some way peculiar to the secondary imprinting procedure.

Imprint Control Element-mediated Secondary Methylation Imprints at the Igf2/H19 Locus

Understanding the molecular basis of monoallelic expression as observed at imprinted loci is helpful in understanding the mechanisms underlying epigenetic regulation. Genomic imprinting begins during gametogenesis with the establishment of epigenetic marks on the chromosomes such that paternal and maternal chromosomes are rendered distinct. During embryonic development, the primary imprint can lead to generation of secondary epigenetic modifications (secondary imprints) of the chromosomes. Eventually, either the primary imprints or the secondary imprints interfere with transcription, leading to parent-of-origin-dependent silencing of one of the two alleles. Here we investigated several aspects pertaining to the generation and functional necessity of secondary methylation imprints at the Igf2/H19 locus. At the H19 locus, these secondary imprints are, in fact, the signals mediating paternal chromosome-specific silencing of that gene. We first demonstrated that the H19 secondary methylation imprints are entirely stable through multiple cell divisions, even in the absence of the primary imprint. Second, we generated mouse mutations to determine which DNA sequences are important in mediating establishment and maintenance of the silent state of the paternal H19 allele. Finally, we analyzed the dependence of the methylation of Igf2DMR1 region on the primary methylation imprint about 90 kilobases away.

Retention of primary preferences after secondary filial imprinting

Retention of primary preferences after secondary filial imprinting