פרסומים

Herbicides are the most efficient and cost-effective means of weed management [...]

Artemisinin-based drugs are the most effective medicine against multidrug-resistant Plasmodium spp., the parasite that causes malaria. To this day, wormwood A. annua L. is the sole commercial source of artemisinin, where it is produced in minor amounts. The artemisinin yield depends on numerous poorly regulated agricultural factors and the genetic variability of this non-domesticated plant. This has aroused significant interest in the development of heterologous expression platforms for artemisinin production. Previously, we obtained lines of Chrysanthemum morifolium Ramat. (C. morifolium Ramat.), cvs. White Snowdon and Egyptianka, transformed with artemisinin biosynthesis genes. Here, we report the results of an analysis of artemisinin production in transgenic chrysanthemums. Transcription of heterologous amorpha-4,11-diene monooxygenase and cytochrome P450 reductase genes in transgenic lines was confirmed using high-resolution melting analysis. Artemisinin accumulation was detected using GC-MS in White Snowdon plants, but not in Egyptianka ones, thereby demonstrating the possibility of transplanting active artemisinin biosynthetic pathway into chrysanthemum. Ways of increasing its content in producer plants are discussed.

Treated-wastewater (TW) irrigation transfers antibiotic-resistant bacteria (ARB) to soil, but persistence of these bacteria is generally low due to resilience of the soil microbiome. Nonetheless, wastewater-derived bacteria and associated antibiotic resistance genes (ARGs) may persist below detection levels and potentially proliferate under copiotrophic conditions. To test this hypothesis, we exposed soils from microcosm, lysimeter, and field experiments to short-term enrichment in copiotroph-stimulating media. In microcosms, enrichment stimulated growth of multidrug-resistant Escherichia coli up to 2 weeks after falling below detection limits. Lysimeter and orchard soils irrigated in-tandem with either freshwater or TW were subjected to culture-based, qPCR and shotgun metagenomic analyses prior, and subsequent, to enrichment. Although native TW- and freshwater-irrigated soil microbiomes and resistomes were similar to each other, enrichment resulted in higher abundances of cephalosporin- and carbapenem-resistant Enterobacteriaceae and in substantial differences in the composition of microbial communities and ARGs. Enrichment stimulated ARG-harboring Bacillaceae in the freshwater-irrigated soils, whereas in TWW-irrigated soils, ARG-harboring.-proteobacterial families Enterobacteriaceae and Moraxellaceae were more profuse. We demonstrate that TW-derived ARB and associated ARGs can persist at below detection levels in irrigated soils and believe that similar short-term enrichment strategies can be applied for environmental antimicrobial risk assessment in the future.

Tubulin, an essential cytoskeletal protein, assembles into various morphologies by interacting with an array of cellular factors. One of these factors is the endogenous polyamine spermine, which may promote and stabilize tubulin assemblies. Nevertheless, the assembled structures and their formation pathways are poorly known. Here we show that spermine induced the in vitro assembly of tubulin into several hierarchical architectures based on a tubulin conical-spiral subunit. Using solution X-ray scattering and cryo-TEM, we found that with progressive increase of spermine concentration tubulin dimers assembled into conical-frustum-spirals of increasing length, containing up to three helical turns. The subunits with three helical turns were then assembled into tubules through base-to-top packing and formed antiparallel bundles of tubulin conical-spiral tubules in a distorted hexagonal symmetry. Further increase of the spermine concentration led to inverted tubulin tubules assembled in hexagonal bundles. Time-resolved experiments revealed that tubulin assemblies formed at higher spermine concentrations assembled from intermediates, similar to those formed at low spermine concentrations. These results are distinct from the classical transition between twisted ribbons, helical, and tubular assemblies, and provide insight into the versatile morphologies that tubulin can form. Furthermore, they may contribute to our understanding of the interactions that control the composition and construction of protein-based biomaterials.

Tubulin, an essential cytoskeletal protein, assembles into various morphologies by interacting with an array of cellular factors. One of these factors is the endogenous polyamine spermine, which may promote and stabilize tubulin assemblies. Nevertheless, the assembled structures and their formation pathways are poorly known. Here we show that spermine induced the in vitro assembly of tubulin into several hierarchical architectures based on a tubulin conical-spiral subunit. Using solution X-ray scattering and cryo-TEM, we found that with progressive increase of spermine concentration tubulin dimers assembled into conical-frustum-spirals of increasing length, containing up to three helical turns. The subunits with three helical turns were then assembled into tubules through base-to-top packing and formed antiparallel bundles of tubulin conical-spiral tubules in a distorted hexagonal symmetry. Further increase of the spermine concentration led to inverted tubulin tubules assembled in hexagonal bundles. Time-resolved experiments revealed that tubulin assemblies formed at higher spermine concentrations assembled from intermediates, similar to those formed at low spermine concentrations. These results are distinct from the classical transition between twisted ribbons, helical, and tubular assemblies, and provide insight into the versatile morphologies that tubulin can form. Furthermore, they may contribute to our understanding of the interactions that control the composition and construction of protein-based biomaterials.

המטרה: לבחון את תפקידה של הקהילה החרדית במחלוקות זוגיות קשות לאחר גירושין בעקבות הפרדות של אחד מבני הזוג מן החברה החרדית.   הנבדקים: 14 הורים גרושים שהתנתקו מן החברה החרדית. שיטת מחקר: נערך מחקר איכותני, משולב, שבמסגרתו בוצעו ראיונות מובנים למחצה עם ההורים הגרושים ונותחו דיווחיהם של 12 עובדים סוציאליים המומחים במקרים של מחלוקות זוגיות קשות.   מן הממצאים  ניתוח הראיונות והדוחות העלה שלושה עולמות תוכן מרכזיים: התפקיד הפעיל של הקהילה; מקומם של הילדים ככלי אינסטרומטלי עבור המעורבות של הקהילה; ואתגרים לעבודה הסוציאלית. המאבק על החינוך של הילדים נמצא כזירה שבה המחלוקת הקהילתית והזוגית מתעצמות במהלכי הגירושים וההפרדות מהחברה החרדית. זאת, על רקע ניסיונותיה של הקהילה החרדית והרבנים להיות מעורבים באופן פעיל בהשארת הילדים בחינוך החרדי, תוך שהם מציעים תמיכה משפטית, כלכלית ורגשית להורה שבחר להישאר נאמן לקהילה. הניסיון למנוע מההורה המתנתק להיפגש עם הילדים מהווה זירה נוספת שבה התערבות הקהילה החרדית ומנהיגיה מחבלת בניסיון לפתור את המחלוקות ומדרדרת את הסכסוך הזוגי. בנוסף, נמצא כי אחד מהאתגרים העיקריים שמולם ניצבו העובדים הסוציאליים המטפלים במקרים של גירושים הכוללים התנתקות מהקהילה החרדית, היה חוסר האמון והחשדנות של הקהילה כלפי העובדים הסוציאליים עצמם, שנתפסו כנציגי הממסד המדינתי. חשדנות זו, הובילה כפי שעלה בדוחות להמנעות ואף לעוינות מנציגי הקהילה החרדית. אתגר נוסף שעימו התמודדו העובדים הסוציאליים בטיפולם במקרים של גירושים בחברה החרדית, נקשר להיעדר התמיכה מצד המערכת והצורך להתפשר על הערכים המקצועיים בעקבות התסכולים שליוו טיפולים אלו.   המחקר מצביע על הצורך להכשיר עובדים סוציאליים העובדים בתחומי החברה החרדית להתמודד עם הקשיים הייחודיים המאפיינים תהליכי גירושים קשים המלווים בהתנתקות מהקהילה החרדית, על רקע התפקיד המחבל לעיתים של רבנים בתהליכים אלו.    

We develop Johnson noise thermometry applicable to mesoscopic devices with variable source impedance with high bandwidth for fast data acquisition. By implementing differential noise measurement and two-stage impedance matching, we demonstrate noise measurement in the frequency range 120-250 MHz with a wide sample resistance range 30 Ω-100 kΩ tuned by gate voltages and temperature. We employ high-frequency, single-ended low noise amplifiers maintained at a constant cryogenic temperature in order to maintain the desired low noise temperature. We achieve thermometer calibration with temperature precision up to 650 µK on a 10 K background with 30 s of averaging. Using this differential noise thermometry technique, we measure thermal conductivity on a bilayer graphene sample spanning the metallic and semiconducting regimes in a wide resistance range, and we compare it to the electrical conductivity.

Northward flow of Antarctic Bottom Water (AABW) across the Southern Ocean comprises a key component of the global overturning circulation. Yet AABW transport remains poorly constrained by observations and state estimates, and there is presently no means of directly monitoring any component of the Southern Ocean overturning. However, AABW flow is dynamically linked to Southern Ocean surface circulation via the zonal momentum balance, offering potential routes to indirect monitoring of the transport. Exploiting this dynamical link, this study shows that wind stress (WS) fluctuations drive large AABW transport fluctuations on time scales shorter than E2 years, which comprise almost all of the transport variance. This connection occurs due to differing time scales on which topographic and interfacial form stresses respond to wind variability, likely associated with differences in barotropic versus baroclinic Rossby wave propagation. These findings imply that AABW transport variability can largely be reconstructed from the surface WS alone.

Author summary Human intervention in ecosystems is motivated by various functional needs, such as provisioning ecosystem services, but often has unexpected detrimental outcomes. A major question in ecology is how to manage human intervention so as to achieve its goal without impairing ecosystem function. The main idea pursued here is the need to identify the inherent response ways of ecosystems to disturbances, and use them as road maps for conducting interventions. This approach is demonstrated mathematically using two contexts, grazing management and vegetation restoration, and compared to remote sensing data for the latter. Among the surprising insights obtained is the beneficial effect of grazing, in terms of resilience to droughts, that can be achieved by managing it non-uniformly in space. Humans play major roles in shaping and transforming the ecology of Earth. Unlike natural drivers of ecosystem change, which are erratic and unpredictable, human intervention in ecosystems generally involves planning and management, but often results in detrimental outcomes. Using model studies and aerial-image analysis, we argue that the design of a successful human intervention form calls for the identification of the self-organization modes that drive ecosystem change, and for studying their dynamics. We demonstrate this approach with two examples: grazing management in drought-prone ecosystems, and rehabilitation of degraded vegetation by water harvesting. We show that grazing can increase the resilience to droughts, rather than imposing an additional stress, if managed in a spatially non-uniform manner, and that fragmental restoration along contour bunds is more resilient than the common practice of continuous restoration in vegetation stripes. We conclude by discussing the need for additional studies of self-organization modes and their dynamics.

We propose and experimentally demonstrate high-speed operation of random-channel cryptography (RCC) in multimode fibers. RCC is a key generation and distribution method based on the random channel state of a multimode fiber and multi-dimension to single-dimension projection. The reciprocal intensity transmittance of the channel shared between the two legitimate users is used to generate and distribute correlated keys. In previous work, RCC’s key rate-distance product was limited by the speed of light. In this work, we show that adding a fast modulator at one end of the channel decouples the key rate and distance, resulting in a significant improvement in the key rate-distance product, limited only by the fiber’s modal dispersion. Error-free transmission at a key rate-distance product of 64.7 Mbps 12 km, which is seven orders of magnitude higher than the previous demonstration, was achieved. The proposed method’s security arises from a fundamental asymmetry between the eavesdroppers and legitimate users measurement complexity.

We propose and experimentally demonstrate high-speed operation of random-channel cryptography (RCC) in multimode fibers. RCC is a key generation and distribution method based on the random channel state of a multimode fiber and multi-dimension to single-dimension projection. The reciprocal intensity transmittance of the channel shared between the two legitimate users is used to generate and distribute correlated keys. In previous work, RCC’s key rate-distance product was limited by the speed of light. In this work, we show that adding a fast modulator at one end of the channel decouples the key rate and distance, resulting in a significant improvement in the key rate-distance product, limited only by the fiber’s modal dispersion. Error-free transmission at a key rate-distance product of 64.7 Mbps 12 km, which is seven orders of magnitude higher than the previous demonstration, was achieved. The proposed method’s security arises from a fundamental asymmetry between the eavesdroppers and legitimate users measurement complexity.

Maimonides famously says some rather radical things about God – radical even by philosophical standards – both about what God is like “in Himself” and about God’s relationship with the created universe. Maimonides’ most detailed and sustained presentation of these radical ideas is in his discussion of divine attributes in chapters 50–70 of the Guide. Indeed, it seems evident that Maimonides’ point in that section is to make plain these radical ideas. To put matters rather simply and straightforwardly, the radical ideas are these: Strictly speaking, God shares nothing substantive in common with created beings, neither existence nor life nor power nor knowledge. Indeed, strictly speaking, God has no intrinsic nature at all, no attributes at all, and stands in no relations whatsoever to the created universe – save for negative attributes and attributes of action. Even speaking strictly, God does have negative attributes and does stand in whatever relations to the created universe are ent

In mammals, neural crest cells populate the gut and form the enteric nervous system (ENS) early in embryogenesis. Although the basic ENS structure is highly conserved across species, we show important differences between mice and humans relating to the prenatal and postnatal development of mucosal enteric glial cells (mEGC), which are essential ENS components. We confirm previous work showing that in the mouse mEGCs are absent at birth, and that their appearance and homeostasis depends on postnatal colonization by microbiota. In humans, by contrast, a network of glial cells is already present in the fetal gut. Moreover, in xenografts of human fetal gut maintained for months in immuno-compromised mice, mEGCs persist following treatment with antibiotics that lead to the disappearance of mEGCs from the gut of the murine host. Single cell RNAseq indicates that human and mouse mEGCs differ not only in their developmental dynamics, but also in their patterns of gene expression.