Piwi-interacting RNAs (piRNAs) silence transposons to safeguard genome integrity in animals. However, the functions of the many piRNAs that do not map to transposons remain unknown. Here, we show ...that piRNA targeting in
can tolerate a few mismatches but prefer perfect pairing at the seed region. The broad targeting capacity of piRNAs underlies the germline silencing of transgenes in
Transgenes engineered to avoid piRNA recognition are stably expressed. Many endogenous germline-expressed genes also contain predicted piRNA targeting sites, and periodic An/Tn clusters (PATCs) are an intrinsic signal that provides resistance to piRNA silencing. Together, our study revealed the piRNA targeting rules and highlights a distinct strategy that
uses to distinguish endogenous from foreign nucleic acids.
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BFBNIB, NMLJ, NUK, ODKLJ, PNG, SAZU, UL, UM, UPUK
Electrochemical deposition has emerged as a novel approach to fabricate metal–organic framework (MOF) films. Here, for the first time, an aqueously cathodic deposition (ACD) approach is developed to ...fabricate ZIF‐8 type of MOF membranes without addition of any supporting electrolyte or modulator. The fabrication process uses 100% water as the sole solvent and a low‐defect density membrane is obtained in only 60 min under room temperature without any pre‐synthesis treatment. The membrane exhibits superior performance in C3H6/C3H8 separation with 182 GPU C3H6 permeance and 142 selectivity, making it sit at the upper bound of permeance versus selectivity graph, outperforming majority of the published data up to 2019. Notably, this approach uses an extremely low current density (0.13 mA cm−2) operated under an ultrafacile apparatus set‐up, enabling an attractive way for environmentally friendly, energy efficient, and easily scalable MOF membrane fabrications. This work demonstrates a great potential of aqueously electrochemical deposition of MOF membrane in the future research.
An ultrathin ZIF‐8 membrane with ≈500 nm thickness is fabricated via a novel aqueous cathodic deposition method. The membrane shows superior C3H6/C3H8 separation performance with the permeance of C3H6 up to 182 GPU and a selectivity of C3H6 over C3H8 up to 142, which surpasses all the reported membrane performances prepared by conventional methods.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Despite the progressive development of the organic food sector in Taiwan, little is known about how consumers’ consumption motives will influence organic food decision through various degrees of ...involvement and whether or not consumers with various degrees of uncertainty will vary in their intention to buy organic foods. The current study aims to examine the effect of consumption motives on behavioral intention related to organic food consumption under the mediating role of involvement as well as the moderating role of uncertainty. Research data were collected from organic food consumers in Taiwan via a questionnaire survey, eventually obtaining 457 valid questionnaires for analysis. This study tested the overall model fit and hypotheses through structural equation modeling method (SEM). The results show that consumer involvement significantly mediates the effects of health consciousness and ecological motives on organic food purchase intention, but not applied to food safety concern. Moreover, the moderating effect of uncertainty is statistical significance, indicating that the relationship between involvement and purchase intention becomes weaker in the condition of consumers with higher degree of uncertainty. Several implications and suggestions are also discussed for organic food providers and marketers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Poly(triazine imide) or PTI is an ordered graphitic carbon nitride hosting Å‐scale pores attractive for selective molecular transport. AA’‐stacked PTI layers are synthesized by ionothermal route ...during which ions occupy the framework and occlude the pores. Synthesis of ion‐free PTI hosting AB‐stacked layers has been reported, however, pores in this configuration are blocked by the neighboring layer. The unavailability of open pore limits application of PTI in molecular transport. Herein, we demonstrate acid treatment for ion depletion which maintains AA’ stacking and results in open pore structure. We provide first direct evidence of ion‐depleted open pores by imaging with the atomic resolution using integrated differential phase‐contrast scanning transmission electron microscopy. Depending on the extent of ion‐exchange, AA’ stacking with open channels and AB stacking with closed channels are obtained and imaged for the first time. The accessibility of open channels is demonstrated by enhanced proton transport through ion depleted PTI.
Poly(triazine imide) or PTI is an ordered graphitic carbon nitride with nanoporous framework. However, pores in PTI are blocked by Li+ and halide ions, and a complete removal of ions leads to an impermeable AB stacking. We report an ion‐exchange route which tunably opens pore channels while maintaining the AA′ configuration leading to an improved proton conductivity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Organisms employ a fascinating array of strategies to silence invasive nucleic acids such as transposons and viruses. Although evidence exists for several pathways that detect foreign sequences, ...including pathways that sense copy number, unpaired DNA, or aberrant RNA (e.g., dsRNA), in many cases, the mechanisms used to distinguish “self” from “nonself” nucleic acids remain mysterious. Here, we describe an RNA-induced epigenetic silencing pathway that permanently silences single-copy transgenes. We show that the Piwi Argonaute PRG-1 and its genomically encoded piRNA cofactors initiate permanent silencing, and maintenance depends on chromatin factors and the WAGO Argonaute pathway. Our findings support a model in which PRG-1 scans for foreign sequences and two other Argonaute pathways serve as epigenetic memories of “self” and “nonself” RNAs. These findings suggest how organisms can utilize RNAi-related mechanisms to detect foreign sequences not by any molecular signature, but by comparing the foreign sequence to a memory of previous gene expression.
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► Epigenetic silencing triggered by piRNA-mediated recognition of nonself RNA ► piRNAs scan using imperfect base pairing to initiate gene silencing ► Maintenance of silencing requires chromatin factors and RdRP-generated small RNAs ► Activating and silencing signals may compete in self versus nonself discrimination
Evidence for a provocative theory that places piRNAs at the center of a “self” versus “nonself” sensor, with some piRNAs functioning to silence foreign DNA and others as part of a mechanism that protects endogenous germline-expressed genes from aberrant silencing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Piwi-interacting RNAs (piRNAs) engage Piwi proteins to suppress transposons and are essential for fertility in diverse organisms. An interesting feature of piRNAs is that, while piRNA lengths are ...stereotypical within a species, they can differ widely between species. For example, piRNAs are mainly 29 and 30 nucleotides in humans, 24 to 30 nucleotides in D. melanogaster, and uniformly 21 nucleotides in C. elegans. However, how piRNA length is determined and whether length impacts function remains unknown. Here, we show that C. elegans deficient for PARN-1, a conserved RNase, accumulate untrimmed piRNAs with 3′ extensions. Surprisingly, these longer piRNAs are stable and associate with the Piwi protein PRG-1 but fail to robustly recruit downstream silencing factors. Our findings identify PARN-1 as a key regulator of piRNA length in C. elegans and suggest that length is regulated to promote efficient transcriptome surveillance.
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•PARN-1 is required for piRNA 3′ end trimming in C. elegans•PARN-1 is expressed in germline nuage and acts as a 3′ to 5′ exo-RNase•3′ trimming of piRNAs is important for both fertility and gene silencing
In C. elegans, piRNA length is determined by the RNase PARN-1 and is important for piRNA-directed gene silencing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the paper, we show that a uniformly bounded and nonnegative triangle functor between Gorenstein derived categories of two CM-algebras induces a Gorenstein-projectively stable functor between the ...corresponding Gorenstein-projectively stable categories. Furthermore, we show that a ladder of Gorenstein derived categories of CM-finite algebras induces a recollement of Gorenstein-projectively stable categories under certain nice conditions. As a byproduct, a Gorenstein derived equivalence induces a Gorenstein-projectively stable equivalence for CM-finite Gorenstein algebras.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The development of a rapid and reproducible crystallization route for the synthesis of polycrystalline metal-organic framework (MOF) films is attractive for the scalable production of nanoporous ...membranes on porous supports. Prior crystallization studies have primarily focused on heterogeneous nucleation, and consequently, the time-consuming growth step has been overlooked. Here, we report a crystallization using sustained precursors (CUSP) route that maintains a high precursor concentration in the growth step, hindering the undesired Ostwald ripening observed in the late stage of growth. As a result, well-intergrown polycrystalline MOF films hosting a uniform grain size and a thickness of a few hundred nanometers could be obtained at room temperature in just a few minutes. Attractive gas separation performance is obtained from ZIF-8 membranes grown in 8 min with H
2
/C
3
H
8
selectivity of 2433 and C
3
H
6
/C
3
H
8
selectivity of 30. The versatility of this approach is demonstrated by synthesizing a ZIF-67 membrane, as well as for the first time, a sub-1 μm-thick continuously intergrown ZIF-90 membrane, also in a few minutes, yielding H
2
/CH
4
and H
2
/C
3
H
6
selectivities of 19.2 and 107.1, respectively. Such advances are expected to bring the scalable production of the high-performance polycrystalline MOF membranes a step closer to reality.
Our method hinders the Ostwald ripening of polycrystalline MOF film during the solvothermal synthesis, allowing the growth of high-quality MOF films in just 8 min at room temperature.
Abstract
Metazoans guard their germlines against transposons and other foreign transcripts with PIWI-interacting RNAs (piRNAs). Due to the robust heritability of the silencing initiated by piRNAs in ...Caenorhabditis elegans (C. elegans), previous screens using C. elegans were strongly biased to uncover members of this pathway in the maintenance process but not in the initiation process. To identify novel piRNA pathway members, we have utilized a sensitized reporter strain which detects defects in initiation, amplification, or regulation of piRNA silencing. Using our reporter, we have identified Integrator complex subunits, nuclear pore components, protein import components, and pre-mRNA splicing factors as essential for piRNA-mediated gene silencing. We found the small nuclear processing cellular machine termed the Integrator complex is required for both type I and type II piRNA production. Notably, we identified a role for nuclear pore and nucleolar components NPP-1/Nup54, NPP-6/Nup160, NPP-7/Nup153, and FIB-1 in promoting the perinuclear localization of anti-silencing CSR-1 Argonaute, as well as a role for Importin factor IMA-3 in nuclear localization of silencing Argonaute HRDE-1. Together, we have shown that piRNA silencing in C. elegans is dependent on evolutionarily ancient RNA processing machinery that has been co-opted to function in the piRNA-mediated genome surveillance pathway.
Brown et al. use a sensitized piRNA reporter to identify factors involved in piRNA silencing in C. elegans. The authors reveal diverse factors critical for the localization and function of piRNA pathway factors, as well as novel connections between nucleoli, the nuclear pore, and germ granules in piRNA silencing. The results also support an emerging model that the proper balance between gene silencing and gene licensing pathways is critical for optimal piRNA-guided genome surveillance.
Many studies have shown that oestrogen affects late follicular development, but whether oestrogen is involved in other aspects of folliculogenesis remains unclear. In this study, two antagonists of ...oestrogen, tamoxifen and G15, were used to determine the effects of oestrogen on folliculogenesis. Mouse preantral follicles and cumulus-oocyte complexes (COCs) were cultured in vitro. The results showed that follicle growth stimulated using pregnant mare serum gonadotrophin (PMSG) was inhibited using tamoxifen, whether in vivo or in vitro. The average diameters, the maximum diameters of follicles and the numbers of follicles with a diameter of more than 300 μm decreased significantly following a 4-day culture with tamoxifen. G15, the antagonist of oestrogen via the membrane receptor, did not change follicular growth stimulated by PMSG in vitro. Results of in vitro maturation of COCs showed that germinal vesicle breakdown (GVBD) occurred spontaneously (95.1%) after 2 h in culture, and the GVBD ratio changed little with the addition of either oestrogen or 10 μM G15. However, first polar body (PBI) extrusion was driven by oestrogen markedly and supplementation with 10 μM G15 inhibited PBI extrusion (82.4% vs 55.0%) significantly. These results demonstrated that oestrogen promotes follicle growth through the nuclear receptor during follicle growth and then triggers the transition of metaphase to anaphase through the membrane receptor during meiotic resumption. So oestrogen plays a progressive role in the two phases of follicle growth and oocyte meiotic resumption.
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