Search

The East Siberia-Beaufort Sea (EsCB) sea ice during boreal autumn has recently been reported to play important roles in the climate over Eurasia and North America. The EsCB sea ice exhibits remarkable year-to-year fluctuations in autumn (August-October), the season in which its minimum extent usually occurs. However, the physical driver of the autumn EsCB sea ice interannual variability remains unclear, impeding the seasonal prediction of local sea ice. Here we find that the autumn EsCB sea ice variability is largely driven by the preceding summer (May-July) dipolar atmospheric anomalies over the North Atlantic, resembling the North Atlantic Oscillation (NAO) pattern. During the negative NAO-like phase, the circumpolar anticyclonic anomalies tend to transport the warm air from Greenland toward the EsCB region, which triggers rapid sea ice melt there. The associated EsCB sea ice anomalies can be maintained or even intensified by the local sea ice-albedo positive feedback until autumn. Therefore, the abnormal signals of Arctic sea ice tend to show significant persistence in summer and autumn. The influence of the summer NAO-like atmospheric circulation on the ensuing autumn EsCB sea ice can be realistically reproduced in the historical simulation of the E3SM-1-0 model, supporting our findings based on the observation. This lagged relationship provides a promising pathway for skillful seasonal prediction of the EsCB sea ice and its related climatic impacts. [ABSTRACT FROM AUTHOR]

An energy-efficient and environmentally conscious bamboo-constructed residential structure was created, comprising bamboo composite panels, steel framework, and mineral wool insulation. To ascertain the efficacy of this particular type of wall in enhancing thermal capabilities, the finite element method was employed to analyze the factors influencing the thermal performance of the exterior wall panels, insulation layer, framework, and interior wall panels. A more judicious design and implementation strategy, known as the 3# and 8# combination scheme, was evaluated in practical applications to assess the thermal efficiency of the wall system. The findings indicated that augmenting the thickness of the inner and outer wall panels and insulation layer, reducing the framework thickness, and incorporating wooden framework as a substitute for steel framework within a certain range enhanced the thermal capabilities of bamboo-constructed walls and mitigated the adverse effects of thermal bridges. The thermal performance of the residences employing the newly developed bamboo-constructed walls surpassed that of conventional iron container houses, thereby warranting broader adoption and application in practical projects. These outcomes offer valuable insights for the optimized design of thermal performance in bamboo-constructed walls. [ABSTRACT FROM AUTHOR]

The Pacific-North American (PNA) teleconnection pattern is one of the prominent atmospheric circulation modes in the extratropical Northern Hemisphere, and its seasonal to interannual predictability is suggested to originate from El Niño-Southern Oscillation (ENSO). Intriguingly, the PNA teleconnection pattern exhibits variance at near-annual frequencies, which is related to a rapid phase reversal of the PNA pattern during ENSO years, whereas the ENSO sea surface temperature (SST) anomalies in the tropical Pacific are evolving much slower in time. This distinct seasonal feature of the PNA pattern can be explained by an amplitude modulation of the interannual ENSO signal by the annual cycle (i.e., the ENSO combination mode). The ENSO-related seasonal phase transition of the PNA pattern is reproduced well in an atmospheric general circulation model when both the background SST annual cycle and ENSO SST anomalies are prescribed. In contrast, this characteristic seasonal evolution of the PNA pattern is absent when the tropical Pacific background SST annual cycle is not considered in the modeling experiments. The background SST annual cycle in the tropical Pacific modulates the ENSO-associated tropical Pacific convection response, leading to a rapid enhancement of convection anomalies in winter. The enhanced convection results in a fast establishment of the large-scale PNA teleconnection during ENSO years. The dynamics of this ENSO-annual cycle interaction fills an important gap in our understanding of the seasonally modulated PNA teleconnection pattern during ENSO years. [ABSTRACT FROM AUTHOR]

Based on combing the concept and development of intelligent ship, this paper brings forward the summary and classification of intelligent ships proposed by different institutions, and the main classification schemes are compared accordingly. Then one of these classification schemes is selected to study what are the key navigational risks under each grading level, with a detailed analysis of these risk factors. Finally, the index system of navigational risk factors for intelligent ships under different classification standards is constructed to lay a foundation for a further study of intelligent ship safe navigation, and at the same time avoid some risk factors in advance for the maritime management department, ship management companies, and ship design and research institutes. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the real-time accuracy of cloud handheld ultrasound system using AI technology in screening carotid plaque. Methods: 2627 ultrasound images of the carotid artery are collected using the cloud handheld system. Bounding boxes of carotid plaques are labeled by qualified sonographers, and the dataset is trained using a lightweight YOLOv3 model. An additional and separate 390 images are collected and tested using the evaluation metrics average recall (AR), average precision (AP), and frames per second (FPS) for quantifying classification performance and time consumption. Results: We use a plaque grading definition with a thickness of 1.2-1.5 mm defined as small plaque, 1.5-3 mm as medium plaque, and more than 3 mm thick as large plaque. Our model achieves APIoU=0.50 with 96.5%, with APlarge is 79.9%, APmedium is 90.7%, APsmall is 93.5%; ARIoU=0.50 is 64.5%, where ARlarge is 60.6%, ARmedium is 58.3%, ARsmall is 70.8%, and FPS is 33.3. Conclusion: We establish a framework for data set construction, model selection, training, and testing of carotid ultrasound images and verify the effectiveness of real-time AI technology in the automatic detection of carotid artery plaque. [ABSTRACT FROM AUTHOR]

Acute liver failure (ALF) is a mortal and critical hepatic disease, in which oxidative stress, inflammation storm and hepatocyte death are crucial in the pathogenesis. Hence, in contrast to the control of a single link, a combination therapy targeting multiple pathogenic links of the disease will be a favorable means to control the progression of the disease. In this study, we constructed dimethyl itaconate-loaded liposomes modified with dodecyl gallate as a cocktail activator to investigate its functional role in acetaminophen (APAP)-induced ALF. Our results demonstrated that the cocktail activator acted on hepatocytes and triggered cocktail efficacy, thereby simultaneously attenuating APAP-induced hepatocyte damage and remodeling the damage microenvironment. The cocktail activator could effectively scavenge reactive oxygen species, inhibit excessive inflammatory responses and reduce cell death in impaired hepatocytes for detoxification. More importantly, the cocktail activator could remodel the damage microenvironment, thus further promoting hepatocyte expansion and specifically switching macrophages from the M1 to M2 phenotype for a favorable liver regeneration of ALF. Furthermore, in APAP-induced ALF mouse model, the cocktail activator improved liver function, alleviated histopathological damage and increased survival rate. In summary, these findings indicate that the cocktail activator may provide a promising therapeutic approach for ALF treatment as a nanomedicine. [ABSTRACT FROM AUTHOR]

Metal--organic frameworks (MOFs) are excellent electrode materials due to their unique structure and properties. However, in many reports, MOF materials are used as precursor materials for porous carbon and metal oxides owing to their inadequate stability. Herein, S, N-containing Ni-MOF [Ni(thiophene-2,5- dicarboxylate)(4,40-bipyridine)]n nanoflowers have been synthesized using a dual-ligand strategy under low-temperature hydrothermal conditions. The influences of nickel salt (NiSO4, Ni(NO3)2, and NiCl2) on the morphology, specific surface area, pore size, and electrochemical properties of the obtained Ni-MOFs are investigated. The results show that the Ni-MOFs prepared using NiSO4 have excellent electrochemical properties and deliver a high specific capacity of 759 Fg-1 at 0.5 A g-1 and exhibit excellent rate performance (62.7% capacity retention at 10 A g-1). When a hybrid supercapacitor is assembled using a Ni-MOF as a cathode and activated carbon as an anode, it shows a high energy density of 30.72 W h kg-1 at a power density of 400 W kg-1. Furthermore, the device exhibits excellent cycling stability (86.26% retention after 5000 cycles). The synthesized Ni-MOF nanoflowers show great potential in high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

UAV remote sensing technology is used to analyze the characteristics of surface collapse and evaluate the degree of damage in the mining area, and the regularity of surface collapse in the mining area is studied. The distribution and variation characteristics of surface collapse pits and surface cracks and surface deformation characteristics are obtained from UAV images. Taking the area of collapse pits, the depth of collapse pits, the width of cracks, the drop of cracks, the density of cracks, surface subsidence and surface inclination as the evaluation factors, the fuzzy opinion centralized decision-making of the classical fuzzy comprehensive evaluation method is introduced into the combined weighting method, and the fuzzy comprehensive evaluation model based on AHP-CRITIC method is established. The results show that: (1) From August 2020 to June 2021, 125 surface cracks have increased; Three new collapse pits are generated, with a maximum area of about 323m2 and a maximum depth of about 21m; The surface deformation in the south of the mining area is obvious, forming a settlement funnel. (2) The severe damage degree of surface collapse is mainly distributed near the surface collapse pits, the moderate damage degree is mainly distributed in the central and southern part of the study area, and the mild and slight damage degree is mainly distributed in the periphery of the ore body. [ABSTRACT FROM AUTHOR]

As one of the most ubiquitous biominerals, calcium oxalate (CaOx) exhibits different hydrate phases. Although the monohydrate (whewellite, COM) is the thermodynamically favorable phase at ambient temperatures, the metastable dihydrate (weddellite, COD) can still stably exist in pathological mineralization but the stabilization mechanisms remain unclear. Herein, the in situ phase transformation of nano-sized COD to COM in the presence of citrate (CA) and zinc ions (Zn2+) as stabilizers was observed by time-resolved atomic force microscopy (AFM) and Raman spectroscopy. By a combination of zeta potential measurement, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), we demonstrate that CA can form a protective layer on the surface of nano-sized COD crystals to inhibit aggregation and delay the phase transformation of COD to COM. Due to the stabilizing/destabilizing effect of CA on the specific faces of COD, atypical-shaped COD crystals form. In addition, Zn2+ can substitute Ca2+ sites within the COD unit cell, shrinking the COD structure by compressing the "zeolite-like" channels to reduce weakly-bonded interchannel H2O molecules. This generates relatively smaller and more stable COD crystals with a typical pyramid shape to further retard COM formation. The obtained results provide new insights into modulating the stability of the metastable CaOx phases for potential control over pathological mineralization. [ABSTRACT FROM AUTHOR]

Small molecule natural products are a chemically diverse class of biomolecules that fulfill myriad biological functions, including autoregulation, communication with microbial neighbors and the host, interference competition, nutrient acquisition, and resistance to oxidative stress. Human commensal bacteria are increasingly recognized as a potential source of new natural products, which may provide insight into the molecular ecology of many different human body sites as well as novel scaffolds for therapeutic development. Here, we review the scientific literature on natural products derived from residents of the human nasal/oral cavity, discuss their discovery, biosynthesis, and ecological roles, and identify key questions in the study of these compounds. [ABSTRACT FROM AUTHOR]

The formation of needle-shaped calcium oxalate crystals called raphides is unique to plants, in which related matrix proteins control crystallization of raphides at biomacromolecule–mineral interfaces with convoluted internal structure and complex morphology. However, investigations for understanding intermediate structures and the underlying mechanisms of raphide biomineralization have been lacking. We present a more detailed single-raphide composition by nanoscale secondary ion mass spectrometry (NanoSIMS) mapping to reveal the presence of individual organic fibers embedded inside raphides. This is in situ observed by imaging demineralization of individual raphides using atomic force microscopy (AFM) to unveil the template-mediated organized aggregation of calcium oxalate nanoparticles via a nonclassical particle-based pathway; internal structures are analyzed using high-resolution transmission electron microscopy (HRTEM) to demonstrate the multistep phase transformation by beam-induced coarsening through intermediates of nanoparticles from amorphous calcium oxalate (ACO) to calcium oxalate trihydrate (COT)/calcium oxalate dihydrate (COD) to the final product of elongated and tapered hexagonal crystals of calcium oxalate monohydrate (COM). The findings at the single-raphide level may improve the fundamental understanding of the structural and morphological complexity in biominerals evolved for survival and adaptation occurring in most plant taxa. [ABSTRACT FROM AUTHOR]

To solve the limited vibration consumption of the traditional tubular damping structure (TTDS), the tubular transition layer damping structure (TTLDS) is proposed; Based on viscoelastic materials and theories of thin cylindrical shells, the governing equation, the first order matrix differential equation describing vibration of TTLDS under harmonic excitation, is derived by considering the interaction between all layers and the dissipation caused by the shear deformation for transition layer and damping layer. By using the extended homogeneous capacity precision integration method to solve the control equation, a semi-analytical method for studying the vibration and damping characteristics of TTLDS is given. By way of comparison, the correctness of the method provided in paper is verified. At last, the influence of thickness, material and location of transition layer on damping effect is analyzed. The results show that the change for the thickness or material of the transition layer can make the structural damping effect change greatly, while the change for location of the transition layer plays only a few roles on the structural damping effect. [ABSTRACT FROM AUTHOR]

The Puccinia graminis f. sp. tritici (Pgt) Ug99 race group is virulent to most stem rust resistance genes currently deployed in wheat and poses a threat to global wheat production. The durum wheat (Triticum turgidum ssp. durum) gene Sr13 confers resistance to Ug99 and other virulent races, and is more effective at high temperatures. Using map-based cloning, we delimited a candidate region including two linked genes encoding coiled-coil nucleotide-binding leucine-rich repeat proteins designated CNL3 and CNL13. Three independent truncation mutations identified in each of these genes demonstrated that only CNL13 was required for Ug99 resistance. Transformation of an 8-kb genomic sequence including CNL13 into the susceptible wheat variety Fielder was sufficient to confer resistance to Ug99, confirming that CNL13 is Sr13. CNL13 transcripts were slightly down-regulated 2-6 days after Pgt inoculation and were not affected by temperature. By contrast, six pathogenesis-related (PR) genes were up-regulated at high temperatures only when both Sr13 and Pgt were present, suggesting that they may contribute to the high temperature resistance mechanism. We identified three Sr13-resistant haplotypes, which were present in one-third of cultivated emmer and durum wheats but absent in most tested common wheats (Triticum aestivum). These results suggest that Sr13 can be used to improve Ug99 resistance in a large proportion of modern wheat cultivars. To accelerate its deployment, we developed a diagnostic marker for Sr13. The identification of Sr13 expands the number of Pgt-resistance genes that can be incorporated into multigene transgenic cassettes to control this devastating disease. [ABSTRACT FROM AUTHOR]

A number of nonlinear acoustic sensing methods exist or are being developed for diverse areas ranging from oceanic sensing of ecosystems, gas bubbles, and submerged objects to medical sensing of the human body. Our approach is to use primary frequency incident waves to generate second order nonlinear sum or difference frequency fields that carry information about an object to be sensed. Here we show that in general nonlinear sensing of an object, many complicated and potentially unexpected mechanisms can lead to sum or difference frequency fields. Some may contain desired information about the object, others may not, even when the intention is simply to probe an object by linear scattering of sum and difference frequency incident waves generated by a parametric array. Practical examples illustrating this in ocean, medical, air and solid earth sensing are given. To demonstrate this, a general and complete second-order theory of nonlinear acoustics in the presence of an object is derived and shown to be consistent with experimental measurements. The total second-order field occurs at sum or difference frequencies of the primary fields and naturally breaks into (A) nonlinear waves generated by wave-wave interactions, and (B) second order waves from scattering of incident wave-wave fields, boundary advection, and wave-force-induced centroidal motion. Wave-wave interactions are analytically shown to always dominate the total second-order field at sufficiently large range and carry only primary frequency response information about the object. As range decreases, the dominant mechanism is shown to vary with object size, object composition, and frequencies making it possible for sum or difference frequency response information about the object to be measured from second-order fields in many practical scenarios. It is also shown by analytic proof that there is no scattering of sound by sound outside the region of compact support intersection of finite-duration plane waves at sum or difference frequencies, to second-order. Analytic expressions for second-order fields due to combinations of planar and far-field wave-wave interactions are also derived as are conditions for when wave-wave interactions will dominate the second order field. [ABSTRACT FROM AUTHOR]

Pyrazolofluostatins A-C (1-3), three new benzo[a]fluorenes with an unprecedented carbon skeleton, were obtained from the South China Sea-derived Micromonospora rosaria SCSIO N160. Their structures were elucidated by extensive spectroscopic analyses. The structure of pyrazolofluostatin A (1) was confirmed by X-ray crystallographic analysis. Notably, 1-3 possessed a benzo[cd]indeno[2,1-f]indazol skeleton with a pyrazole-fused 6/5/6/6/5 pentacyclic ring system. Pyrazolofluostatin A (1) showed moderate antioxidation activity (EC50 48.6 µM). [ABSTRACT FROM AUTHOR]

The purpose of the article is to explain shifts in the priorities and work practices of Chinese school principals in response to national curriculum reform. The research focused on three school case studies based on semi-structured interviews with the principals of the three schools and focus group interviews with the senior management teams, department heads and classroom teachers in each of the schools. Supplementary evidence was obtained from school documentary sources and informal observations. The results of the study indicate a shift in school principal priorities and work practices from routine administration to the leadership of external relations and networking, teaching staff and teaching quality, and curricular and pedagogical change. The conclusions indicate broad commonalities in leadership purpose towards these three objectives, but also indicate significant differences related to leadership style and organisational context. The findings contribute to a deeper international understanding of changing school principal work practices and priorities. [ABSTRACT FROM AUTHOR]

An improved time-delay wavelet neural network (WNN) is proposed to represent the complex nonlinear and timevarying dynamics of ship motion based on sensitivity analysis approach. To improve the generalization performance of WNN, inputs of the wavelet network are selected based on their relative contribution to the overall output. To evaluate the contribution of inputs in the WNN, an index is proposed referred to as relative contribution rate (RCR). The resulted network is utilized as an online ship motion predictor. Based on the predictor, a predictive PID controller is presented and implemented in a ship course-following control. Simulation of online predictive ship course-following control was conducted and results demonstrate the feasibility and efficiency of the WNN predictor and the WNN-based predictive control strategy. [ABSTRACT FROM AUTHOR]

Background: β-Adrenergic receptors (βARs) play paradoxical roles in the heart. On one hand, βARs augment cardiac performance to fulfill the physiological demands, but on the other hand, prolonged activations of βARs exert deleterious effects that result in heart failure. The signal transducer and activator of transcription 3 (STAT3) plays a dynamic role in integrating multiple cytokine signaling pathways in a number of tissues. Altered activation of STAT3 has been observed in failing hearts in both human patients and animal models. Our objective is to determine the potential regulatory roles of STAT3 in cardiac βAR-mediated signaling and function.Methods and Results: We observed that STAT3 can be directly activated in cardiomyocytes by β-adrenergic agonists. To follow up this finding, we analyzed βAR function in cardiomyocyte-restricted STAT3 knockouts and discovered that the conditional loss of STAT3 in cardiomyocytes markedly reduced the cardiac contractile response to acute βAR stimulation, and caused disengagement of calcium coupling and muscle contraction. Under chronic β-adrenergic stimulation, Stat3cKO hearts exhibited pronounced cardiomyocyte hypertrophy, cell death, and subsequent cardiac fibrosis. Biochemical and genetic data supported that Gαs and Src kinases are required for βAR-mediated activation of STAT3. Finally, we demonstrated that STAT3 transcriptionally regulates several key components of βAR pathway, including β1AR, protein kinase A, and T-type Ca(2+) channels.Conclusions: Our data demonstrate for the first time that STAT3 has a fundamental role in βAR signaling and functions in the heart. STAT3 serves as a critical transcriptional regulator for βAR-mediated cardiac stress adaption, pathological remodeling, and heart failure. [ABSTRACT FROM AUTHOR]

Plant height is an important agronomic trait with a significant impact on grain yield, as demonstrated by the positive effect of the REDUCED HEIGHT(RHT) dwarfing alleles (Rht1b) on lodging and harvest index in the "Green Revolution" wheat varieties. However, these gibberellic acid (GA)-insensitive alleles also reduce coleoptile length, biomass production, and yield potential in some environments, triggering the search for alternative GA-sensitive dwarfing genes. Here we report the identification, validation, and characterization of the gene underlying the GA-sensitive dwarfing locus RHT25 in wheat. This gene, designated as PLATZ-A1 (TraesCS6A02G156600), is expressed mainly in the elongating stem and developing spike and encodes a plant-specific AT-rich sequence- and zinc-binding protein (PLATZ). Natural and induced loss-of-function mutations in PLATZ-A1 reduce plant height and its overexpression increases plant height, demonstrating that PLATZ-A1 is the causative gene of RHT25. PLATZ-A1 and RHT1 show a significant genetic interaction on plant height, and their encoded proteins interact with each other in yeast and wheat protoplasts. These results suggest that PLATZ1 can modulate the effect of DELLA on wheat plant height. We identified four natural truncation mutations and one promoter insertion in PLATZ-A1 that are more frequent in modern varieties than in landraces, suggesting positive selection during wheat breeding. These mutations can be used to fine-tune wheat plant height and, in combination with other GA-sensitive dwarfing genes, to replace the GA-insensitive Rht1b alleles and search for grain yield improvements beyond those of the Green Revolution varieties. [ABSTRACT FROM AUTHOR]

A mixtureof calcium oxalate and calcium phosphate is a sourceof chronic human disease, forming kidney stones. However, the mechanismsof pathological biomineralization and its modulation by natural inhibitorssuch as osteopontin (OPN) proteins are poorly defined at the nanoscale.Here, the in vitro formation of calcium oxalate monohydrate (COM)concretions having brushite nidi is observed using in situ atomicforce microscopy (AFM) in a simulated acidic urinary milieu. We quantifythe dissolution kinetics of the [101]Cc, [1̅00]Cc, and [101̅]Ccsteps on the brushite (CaHPO4·2H2O, DCPD) (010) surfaces by oxalate, two urinaryconstituents. In support of clinical observations, we further demonstratethe inhibitory effect of phosphorylated OPN peptides on the step retreatrates through step-specific interactions, this in turn regulatingthe kinetics of COM nucleation and aggregation at the expense of brushitecrystals by means of the interfacial mineral replacement reactions.The definition of respective roles for DCPD and OPN peptides therebyoffers general insights concerning the control of kidney stone formationand the mechanisms through which aberrant crystallization kineticsis inhibited. [ABSTRACT FROM AUTHOR]

It is known that the relation between curvature and wave speed plays a key role in the propagation of two-dimensional waves in an excitable model. For typical excitable models (e.g., the FitzHugh-Nagumo (FHN) model), such a relation is believed to obey the linear eikonal equation, which states that the relation between the normal velocity and the local curvature is approximately linear. In this paper, we show that for a caricature model of intracellular calcium dynamics, although its temporal dynamics can be investigated by analogy with the FHN model, the curvature relation does not obey the linear eikonal equation even in the limiting case. Hence, this caricature calcium model may be an unexpected excitable system, whose wave propagation properties cannot be always understood by analogy with the FHN model. [ABSTRACT FROM AUTHOR]

Liver X receptors (LXRs) are nuclear receptors that function as ligand-activated transcription factors regulating lipid metabolism and inflammation. Recent discoveries found LXRs could regulate tumor growth in a variety of cancer cell lines. In this study, we investigated the effect of LXR activation on melanoma cell proliferation and apoptosis both in vitro and in vivo. Treatment of B16F10 and A-375 melanoma cells with synthetic LXR agonist T0901317 significantly inhibited the proliferation of melanoma cells in vitro. Meanwhile, T0901317 induced the apoptosis of B16F10 melanoma cells in a dose-dependent manner. Furthermore, western blot assay showed that the pro-apoptotic effect of T0901317 on B16F10 melanoma cells was mediated through caspase-3 pathway. Oral administration of T0901317 inhibited the growth of B16F10 melanoma in C56BL/6 mice. Altogether, this study demonstrates the critical role of LXRs in the regulation of melanoma growth and presents the LXR agonist T0901317 as a potential anti-melanoma agent. [ABSTRACT FROM AUTHOR]

A wavelet neural network with time delay is proposed based on nonlinear autoregressive model with exogenous inputs (NARMAX) model, and the sensitivity method is applied in the selection of network inputs. The inclusion of delayed system information improves the network's capability of representing the dynamic changes of time-varying systems. The implement of sensitivity analysis reduces the dimension of input as well as the dimension of networks, thus improving its generalization ability. The time delay wavelet neural network was implemented to real-time ship motion prediction, simulations are conducted based on the measured data of vessel "YUKUN," and the results demonstrate that the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

Unraveling the kinetics and mechanisms of sparingly soluble calcium orthophosphate (Ca-P) dissolution in the presence of organic acids at microscopic levels is important for an improved understanding in determining the effectiveness of organic acids present in most rhizosphere environments. Herein, we use in situ atomic force microscopy (AFM) coupled with a fluid reaction cell to image dissolution on the (010) face of brushite, CaHPO4.2H2O, in citrate-bearing solutions over a broad concentration range. We directly measure the dependence of molecular step retreat rate on citrate concentration at various pH values and ionic strengths, relevant to soil solution conditions. We find that low concentrations of citrate (10-100 μM) induced a reduction in step retreat rates along both the [100]Cc and [101]Cc directions. However, at higher concentrations (exceeding 0.1 mM), this inhibitory effect was reversed with step retreat speeds increasing rapidly. These results demonstrate that the concentration-dependent modulation of nanoscale Ca-P phase dissolution by citrate may be applied to analyze the controversial role of organic acids in enhancing Ca-P mineral dissolution in a more complex rhizosphere environment. These in situ observations may contribute to resolving the previously unrecognized interactions of root exudates (low molecular weight organic acids) and sparingly soluble Ca-P minerals. [ABSTRACT FROM AUTHOR]

Endohedral metallofullerenes (EMFs) encapsulating divalent metal ions have received limited attention because of their low production yields. Here, we report the results of structural determination and chemical functionalization of a typical divalent metallofullerene, Yb@C84(II). Single-crystal X-ray crystallographic studies of Yb@C84/NiII(OEP) cocrystals (OEP is the dianion of octaethylporphyrin) unambiguously established the chiral C2(13)-C84 cage structure and revealed multiple sites for Yb2+, indicating a moving metal ion inside the cage. The chemical property of Yb@C2(13)-C84 was probed with the electrophillic adamantylidene carbene (1). Three monoadduct isomers were isolated and characterized. Crystallographic results of the major isomer (2b) revealed that, although the cycloaddition breaks a [5,6]-bond on the cage, Yb2+ is localized under a hexagonal ring distant from the sites of addition. Thus, it is proved that the dynamic motion of the divalent metal ion in Yb@C84 has been effectively halted by exohedral functionalization. Spectroscopic results show that the electronic property of Yb@C2(13)-C84 is pertained in the derivatives, although the addend exerts a mild reduction effect on the electrochemical behavior of the EMF. Computational works demonstrated that addition of 1 to Yb@C2(13)-C84 is mainly driven by releasing the local strains of cage carbons rather than charge recombination, which is always prominent to the affinity of typical trivalent EMFs such as M@C2v(9)-C82 (M = Sc, Y, La, Ce, Gd) toward 1. Accordingly, it is speculated that the chemical behaviors of divalent EMFs more likely resemble those of empty fullerenes because both are closed-shell compounds, but they differ from those of trivalent EMFs, which have open-shell electronic configurations instead. [ABSTRACT FROM AUTHOR]

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating disease that can cause severe yield losses. A previously uncharacterized Pgt race, designated Ug99, has overcome most of the widely used resistance genes and is threatening major wheat production areas. Here, we demonstrate that the Sr35 gene from Triticum monococcum is a coiled-coil, nucleotide-binding, leucine-rich repeat gene that confers near immunity to Ug99 and related races. This gene is absent in the A-genome diploid donor and in polyploid wheat but is effective when transferred from T. monococcum to polyploid wheat. The cloning of Sr35 opens the door to the use of biotechnological approaches to control this devastating disease and to analyses of the molecular interactions that define the wheat-rust pathosystem. [ABSTRACT FROM AUTHOR]

The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is an important insect pest of rice, Oryza sativa L., in the United States and Asian countries. Previous reports indicated that most first-generation adults (summer weevils) entered reproductive diapause with only a few of the population reproducing to form a second generation. However, the environmental factors responsible for diapause induction have not been thoroughly studied. Southern cutgrass, Leersia hexandra Swartz, is a widely distributed perennial grass in the rice ecosystem of regions where rice water weevil occurs. After feeding on cutgrass for 30 days, summer weevils initiated oviposition rapidly after being transferred to young rice plants, and the percentage of ovipositing weevils was 80-100% after 2 weeks. Summer weevils feeding on southern cutgrass did not enter diapause but developed into a reproductive state, suggesting the grass might allow rice water weevils to avoid summer diapause. Such "diapause-avoiding" weevils laid an average of 7-21 eggs within 30 days feeding on rice plants, which was substantially less than that of nondiapausing weevils (overwintered weevils, 45 eggs), suggesting great plasticity of the insect during summer diapause. Our data suggested many weed hosts, such as southern cutgrass, affect the population dynamics of summer rice water weevils and their offspring. [ABSTRACT FROM AUTHOR]

Trabeculation and compaction of the embryonic myocardium are morphogenetic events crucial for the formation and function of the ventricular walls. Fkbp1a (FKBP12) is a ubiquitously expressed cis-trans peptidyl-prolyl isomerase. Fkbp1a-deficient mice develop ventricular hypertrabeculation and noncompaction. To determine the physiological function of Fkbp1a in regulating the intercellular and intracellular signaling pathways involved in ventricular trabeculation and compaction, we generated a series of Fkbp1a conditional knockouts. Surprisingly, cardiomyocyte-restricted ablation of Fkbp1a did not give rise to the ventricular developmental defect, whereas endothelial cell-restricted ablation of Fkbp1a recapitulated the ventricular hypertrabeculation and noncompaction observed in Fkbp1a systemically deficient mice, suggesting an important contribution of Fkbp1a within the developing endocardia in regulating the morphogenesis of ventricular trabeculation and compaction. Further analysis demonstrated that Fkbp1a is a novel negative modulator of activated Notch1. Activated Notch1 (N1ICD) was significantly upregulated in Fkbp1a-ablated endothelial cells in vivo and in vitro. Overexpression of Fkbp1a significantly reduced the stability of N1ICD and direct inhibition of Notch signaling significantly reduced hypertrabeculation in Fkbp1a-deficient mice. Our findings suggest that Fkbp1a-mediated regulation of Notch1 plays an important role in intercellular communication between endocardium and myocardium, which is crucial in controlling the formation of the ventricular walls. [ABSTRACT FROM AUTHOR]

Loss-of-function mutation of Jup has been associated with Naxos disease, which is characterized by arrhythmogenic cardiomyopathy and the cutaneous disorder palmoplantar keratoderma. Previously, we have shown that genetic ablation of Jup in cardiomyocytes in mice leads to arrhythmogenic cardiomyopathy similar to Naxos disease in humans. Currently, to determine the pathogenesis of Naxos disease-associated keratoderma, we generated Jup mutant mice by inactivating Jup restrictively in keratinocytes. Jup mutant mice largely recapitulated the clinical features of human palmoplantar keratoderma: overcornification and thickening of the epidermis. Jup mutant mice also suffered skin ulceration and inflammation. Cell apoptosis and proliferation were significantly elevated in Jup mutant epidermis. Ultrastructural analyses revealed the disruption of the assembly of desmosomes and adherens junctions in Jup mutant epidermis. We also demonstrated the compensational increase in β-catenin at Jup mutant cell-cell junctions without altering its signaling activities. Our findings provide important insights for understanding the pathogenesis of human palmoplantar keratoderma. [ABSTRACT FROM AUTHOR]

Bone morphogenetic protein 10 (BMP10) belongs to the TGFβ-superfamily. Previously, we had demonstrated that BMP10 is a key regulator for ventricular chamber formation, growth, and maturation. Ablation of BMP10 leads to hypoplastic ventricular wall formation, and elevated levels of BMP10 are associated with abnormal ventricular trabeculation/compaction and wall maturation. However, the molecular mechanism(s) by which BMP10 regulates ventricle wall growth and maturation is still largely unknown. In this study, we sought to identify the specific transcriptional network that is potentially mediated by BMP10. We analyzed and compared the gene expression profiles between α-myosin heavy chain (αMHC)-BMP10 transgenic hearts and nontransgenic littermate controls using Affymetrix mouse exon arrays. T-box 20 (Tbx20), a cardiac transcription factor, was significantly up-regulated in αMHC-BMP10 transgenic hearts, which was validated by quantitative RT-PCR and in situ hybridization. Ablation of BMP10 reduced Tbx20 expression specifically in the BMP10-expressing region of the developing ventricle. In vitro promoter analysis demonstrated that BMP10 was able to induce Tbx20 promoter activity through a conserved Smad binding site in the Tbx20 promoter proximal region. Furthermore, overexpression of Tbx20 in myocardium led to dilated cardiomyopathy that exhibited ventricular hypertrabeculation and an abnormal muscular septum, which phenocopied genetically modified mice with elevated BMP10 levels. Taken together, our findings demonstrate that the BMP10-Tbx20 signaling cascade is important for ventricular wall development and maturation. [ABSTRACT FROM AUTHOR]

Pacidamycins are a family of uridyl tetra/pentapeptide antibiotics with antipseudomonal activities through inhibition of the translocase MraY in bacterial cell wall assembly. The biosynthetic gene cluster for pacidamycins has recently been identified through genome mining of the producer Streptomyces coeruleorubidus, and the highly dissociated nonribosomal peptide assembly line for the uridyl tetrapeptide scaffold of pacidamycin has been characterized. In this work a hypothetical protein PacB, conserved in known uridyl peptide antibiotics gene clusters, has been characterized by both genetic deletion and enzymatic analysis of the purified protein. PacB catalyzes the transfer of the alanyl residue from alanyl-tRNA to the N terminus of the tetrapeptide intermediate yielding a pentapeptide on the thio-templated nonribosomal peptide synthetase (NRPS) assembly line protein PacH. PacB thus represents a new group of tRNA-dependent peptide bond-forming enzymes in secondary metabolite biosynthesis in addition to the recently identified cyclodipeptide synthases. The characterization of PacB completes the assembly line reconstitution of pacidamycin pentapeptide antibiotic scaffolds, bridging the primary and secondary metabolic pathways by hijacking an aminoacyl-tRNA to the antibiotic biosynthetic pathway. [ABSTRACT FROM AUTHOR]

Pacidamycins are a family of uridyl peptide antibiotics that inhibit the translocase MraY, an essential enzyme in bacterial cell wall biosynthesis that to date has not been clinically targeted. The pacidamycin structural skeleton contains a doubly inverted peptidyl chain with a β-peptide and a ureido linkage as well as a 3'-deoxyuridine nucleoside attached to DABA3 of the peptidyl chain via an enamide linkage. Although the biosynthetic gene cluster for pacidamycins was identified recently, the assembly line of this group of peptidyl nucleoside antibiotics remained poorly understood because of the highly dissociated nature of the encoded nonribosomal peptide synthetase (NRPS) domains and modules. This work has identified a minimum set of enzymes needed for generation of the pacidamycin scaffold from amino acid and nucleoside monomers, highlighting a freestanding thiolation (T) domain (PacH) as a key carrier component in the peptidyl chain assembly as well as a freestanding condensation (C) domain (PacI) catalyzing the release of the assembled peptide by a nucleoside moiety. On the basis of the substrate promiscuity of this enzymatic assembly line, several pacidamycin analogues were produced using in vitro total biosynthesis. [ABSTRACT FROM AUTHOR]

A number of natural products contain a 2-amino-3-hydroxycyclopent-2-enone five membered ring, termed C5N, which is condensed via an amide linkage to a variety of polyketide-derived polyenoic acid scaffolds. Bacterial genome mining indicates three tandem ORFs that may be involved in C5N formation and subsequent installation in amide linkages. We show that the protein products of three tandem ORFs (ORF33-35) from the ECO-02301 biosynthetic gene cluster in Streptomyces aizunenesis NRRL-B-11277, when purified from Escherichia coli, demonstrate the requisite enzyme activities for C5N formation and amide ligation. First, succinyl-CoA and glycine are condensed to generate 5-aminolevulinate (ALA) by a dedicated PLP-dependent ALA synthase (ORF34). Then ALA is converted to ALA-CoA through an ALA-AMP intermediate by an acyl-CoA ligase (ORF35). ALA-CoA is unstable and has a half-life of 10 min under incubation conditions for off-pathway cyclization to 2,5-piperidinedione. The ALA synthase can compete with the nonenzymatic decomposition route and act in a novel second transformation, cyclizing ALA-CoA to C5N. C5N is then a substrate for the third enzyme, an ATP-dependent amide synthetase (ORF33). Using octatrienoic acid as a mimic of the C56 polyenoic acid scaffold of ECO-02301, formation of the octatrienyl-C5N product was observed. This three enzyme pathway is likely the general route to the C5N ring system in other natural products, including the antibiotic moenomycin. [ABSTRACT FROM AUTHOR]

In this study, we developed 359 detection primers for single nucleotide polymorphisms (SNPs) previously discovered within intron sequences of wheat genes and used them to evaluate SNP polymorphism in common wheat ( Triticum aestivum L.). These SNPs showed an average polymorphism information content (PIC) of 0.18 among 20 US elite wheat cultivars, representing seven market classes. This value increased to 0.23 when SNPs were pre-selected for polymorphisms among a diverse set of 13 hexaploid wheat accessions (excluding synthetic wheats) used in the wheat SNP discovery project (). PIC values for SNP markers in the D genome were approximately half of those for the A and B genomes. D genome SNPs also showed a larger PIC reduction relative to the other genomes ( P < 0.05) when US cultivars were compared with the more diverse set of 13 wheat accessions. Within those accessions, D genome SNPs show a higher proportion of alleles with low minor allele frequencies (<0.125) than found in the other two genomes. These data suggest that the reduction of PIC values in the D genome was caused by differential loss of low frequency alleles during the population size bottleneck that accompanied the development of modern commercial cultivars. Additional SNP discovery efforts targeted to the D genome in elite wheat germplasm will likely be required to offset the lower diversity of this genome. With increasing SNP discovery projects and the development of high-throughput SNP assay technologies, it is anticipated that SNP markers will play an increasingly important role in wheat genetics and breeding applications. [ABSTRACT FROM AUTHOR]

Bacterial aromatic polyketides are important therapeutic compounds including front line antibiotics and anticancer drugs. It is one of the last remaining major classes of natural products of which the biosynthesis has not been reconstituted in the genetically superior host Escherichia coil. Here, we demonstrate the engineered biosynthesis of bacterial aromatic polyketides in E. coli by using a dissected and reassembled fungal polyketide synthase (PKS). The minimal PKS of the megasynthase PKS4 from Gibberella fujikuroi was extracted by using two approaches. The first approach yielded a stand-alone Ketosynthase (KS) malonyl-CoA:ACP transferase (MAT) didomain and an acyl-carrier protein (ACP) domain, whereas the second approach yielded a compact PKS (PKS WJ) that consists of KS, MAT, and ACP on a single polypeptide. Both minimal PKSs produced nonfungal polyketides cyclized via different regioselectivity, whereas the fungal-specific C2-C7 cyclization mode was not observed. The kinetic properties of the two minimal PKSs were characterized to confirm both PKSs can synthesize polyketides with similar efficiency as the parent PKS4 megasynthase. Both minimal PKSs interacted effectively with exogenous polyketide cyclases as demonstrated by the synthesis of predominantly PK8 3 or NonaSEK4 6 in the presence of a C9-C14 or a C7-C12 cyclase, respectively. When PKS WJ and downstream tailoring enzymes were expressed in E. coli, the expected nonaketide anthraquinone SEK26 was recovered in good titer. High-cell density fermentation was performed to demonstrate the scale-up potential of the in vivo platform for the biosynthesis of bacterial polyketides. Using engineered fungal PKS5 can therefore be a general approach toward the heterologous biosynthesis of bacterial aromatic polyketides in E. coli. [ABSTRACT FROM AUTHOR]

OBJECTIVE -- Glucose homeostasis is achieved by triggering regulation of glycogen synthesis genes in response to insulin when mammals feed, but the underlying molecular mechanism remains largely unknown. The aim of our study was to examine the role of the signal transducers and activators of transcription 3 (STAT3) in insulin signaling. RESEARCH DESIGN AND METHODS -- We generated a strain of mice carrying a targeted disruption of Star3 gene in the liver (L-Stat3[sup -/-] mice). Hepatocytes of the L-Stat3[sup -/-] mice were isolated to establish cell lines for mechanistic studies. Nuclear translocation and DNA-protein interaction of STAT3 was analyzed with immunofluorescent and chromatin immunoprecipitation methods, respectively. Levels of glucose, insulin, leptin, and glucagon were profiled, and putative downstream molecules of STAT3 were examined in the presence of various stimuli in L-Star3[sup -/-] and control mice. RESULTS -- STAT3 was found to sensitize the insulin signaling through suppression of GSK-3β, a negative regulator of insulin signaling pathway. During feeding, both mRNA and protein levels of GSK-3β decreased in Stat3[sup f/+] mice, which reflected the need of hepatocytes for insulin to induce glycogen synthesis. In contrast, the L-Stat3[sup -/-] mice lost this control and showed a monophasic increase in the GSK-3β level in response to insulin. Administration of GSK-3β inhibitors lithium chloride and L803-mts restored glucose homeostasis and rescued the glucose intolerance and impaired insulin response in L-Star3[sup -/-] mice. CONCLUSIONS -- These data indicate that STAT3 sensitizes insulin signaling by negatively regulating GSK-3β. Inactivation of STAT3 in the liver contributes significantly to the pathogenesis of insulin resistance. Diabetes 57:1227-1235, 2008 [ABSTRACT FROM AUTHOR]

In most existing in-band wavelet video coding schemes, over-complete wavelet transform is used for the motion-compensated temporal filtering (MCTF) of each spatial subband. It can overcome the shift-variance of critical sampling wavelet transform and improve the coding efficiency of the in-band scheme. However, a dilemma exists in the current implementations of in-band MCTF (IBMCTF), which is whether or not to exploit the spatial highpass subbands in motion compensation of the spatial lowpass subband. The absence of the spatial highpass subbands will result in significant quality loss in the reconstructed full-resolution video, whereas the presence of the spatial highpass subbands may bring serious mismatch error in the decoded low-resolution video since the corresponding highpass subbands may be unavailable at the decoder. In this paper, we first analyze the mismatch error propagation in decoding the low-resolution video. Based on our analysis, we then propose a frame-based cross-resolution leaky prediction scheme for IIBMCTF. It can make a good tradeoff between alleviating the low-resolution mismatch and improving the full-resolution coding efficiency. Experimental results show that the proposed scheme can dramatically reduce the mismatch error by 0.3-2.5 dB for low resolution, while the performance loss is marginal for high resolution. [ABSTRACT FROM AUTHOR]

We propose a simple yet effective deblocking method for JPEG compressed image through postfiltering in shifted windows (PSW) of image blocks. The MSE is compared between the original image block and the image blocks in shifted windows, so as to decide whether these altered blocks are used in the smoothing procedure. Our research indicates that there exists strong correlation between the optimal mean squared error threshold and the image quality factor Q, which is selected in the encoding end and can be computed from the quantization table embedded in the JPEG file. Also we use the standard deviation of each original block to adjust the threshold locally so as to avoid the over-smoothing of image details. With various image and bit-rate conditions, the processed image exhibits both great visual effect improvement and significant peak signal-to-noise ratio gain with fairly low computational complexity. Extensive experiments and comparison with other deblocking methods are conducted to justify the effectiveness of the proposed PSW method in both objective and subjective measures. [ABSTRACT FROM AUTHOR]

Signal transducer and activator of transcription (STAT) 3 is involved in mediating a broad range of biological processes, including cell survival, proliferation, and immune response. Recent evidence has indicated that STAT3 in cardiomyocytes can be activated by ischemicoxidative stress and exerts cardioprotection in the ischemic heart. There is no information, however, regarding the effect of endothelial cell-derived STAT3 on the myocardial response to ischemia-reperfusion (I/R) injury. We hypothesized that the ablation of the STAT3 gene in endothelial cells would worsen postischemic myocardial function by affecting capillary network integrity, suppressing antiapoptotic signaling. Isolated hearts from wild-type and endothelial cell STAT3 knockout (STAT3KO) mice were subjected to 20 rain of global ischemia followed by 60 min of reperfusion. Endothelial cell STAT3 deficiency decreased recovery of myocardial function in response to I/R, which was associated with higher levels of LDH release, decreased activation of myocardial STAT3, and elevated p38 MAPK activation in STAT3 endothelial knockout (KO) hearts. In addition, although no significant apoptosis was observed in wild-type and KO hearts, our results showed more expression of myocardial caspase-8 and more apoptosis in the myocardium around the capillary in STAT3KO mice subjected to I/R. Furthermore, endothelial cell STAT3 ablation resulted in increased myocardial expression of IL-6 and suppressor of cytokine signal 3. This study demonstrates that endothelial cell-derived STAT3 plays an important role in postischemic myocardial function. [ABSTRACT FROM AUTHOR]

Recent studies have shown that females have improved myocardial functional recovery, TNF receptor 1 (TNFR1) signaling resistance, and increased STAT3 phosphorylation following acute ischemialreperfusion (I/R) compared with males. We hypothesized that 1) STAT3 deficiency in endothelial cells (EC) impairs myocardial functional recovery in both sexes, 2) EC STAT3 deficiency equalizes sex differences in functional recovery, and 3) knockout of EC STAT3 decreases activation of myocardial STAT3 and increases p38 MAPK activation following acute I/R. Isolated male and female mouse hearts from WT and EC STAT3 knockout (STAT3KO) were subjected to 20-min ischemia/60-min reperfusion, and ± dP/dt were continuously recorded. Heart tissue was analyzed for the active forms of STAT3 and p38 MAPK as well as expression of caspase-8 (Western blot) following I/R. EC STATKO had significantly decreased myocardial functional recovery in both sexes (%recovered +dP/dt: male 51.6 ± 3.1 vs. 32.1 ± 13.1%, female 79.1 ± 3.6 vs. 43.6 ± 9.1%; -dP/dt: male 52.2 ± 3.3 vs. 28.9 ± 12%. female 75.2 ± 4.1 vs. 38.6 ± 10%). In addition, EC STAT3KO neutralized sex differences in myocardial function, which existed in WT mice. Interestingly, EC STAT3 deficiency decreased myocardial STAT3 activation but increased myocardial p38 MAPK activation in both sexes; however, this was seen to a greater degree in females. We conclude that EC STAT3 deficiency resulted in decreased recovery of myocardial function in both sexes and neutralized sex differences in myocardial functional recovery following I/R. This observation was associated with decreased activation of myocardial STAT3 and increased activation of p38 MAPK in EC STAT3KO heart after I/R. [ABSTRACT FROM AUTHOR]

Tetracyclines are aromatic polyketides biosynthesized by bacterial type II polyketide synthases. The amidated tetracycline backbone is biosynthesized by the minimal polyketide synthases and an amidotransferase homologue OxyD. Biosynthesis of the key intermediate 6-methylpretetramid requires two early tailoring steps, which are cyclization of the linearly fused tetracyclic scaffold and regioselective C-methylation of the aglycon. Using a heterologous host (CH999)/vector pair, we identified the minimum set of enzymes from the oxytetracycline biosynthetic pathway that is required to afford 6-methyipretetramid in vivo. Only two cyclases (OxyK and OxyN) are necessary to completely cyclize and aromatize the amidated tetracyclic aglycon. Formation of the last ring via c-i/c-18 aldol condensation does not require a dedicated fourth-ring cyclase, in contrast to the biosynthetic mechanism of other tetracyclic aromatic polyketides, such as daunorubicin and tetracenomycin. Acetyl-derived polyketides do not undergo spontaneous fourth-ring cyclization and form only anthracene carboxylic acids as demonstrated both in vivo and in vitro. OxyF was identified to be the C-6 C-methyltransferase that regioselectively methylates pretetramid to yield 6-methylpretetramid. Reconstitution of 6-methylpretetramid in a heterologous host sets the stage for a more systematic investigation of additional tetracycline downstream tailoring enzymes and is a key step toward the engineered biosynthesis of tetracycline analogs. [ABSTRACT FROM AUTHOR]

Genetic diversity and genome-wide linkage disequilibrium (LD) were investigated among 43 U.S. wheat (Triticum aestivum L.) elite cultivars and breeding lines representing seven U.S. wheat market classes using 242 wheat genomic simple sequence repeat (SSR) markers distributed throughout the wheat genome. Genetic diversity among these lines was examined using genetic distance-based and model-based clustering methods, and analysis of molecular variance. Four populations were identified from the model-based analysis, which partitioned each of the spring and winter populations into two subpopulations, corresponding largely to major geographic regions of wheat production in the United States. This suggests that the genetic diversity existing among these U.S. wheat germplasm was influenced more by regional adaptation than by market class, and that the individuals clustered in the same model-based population likely shared related ancestral lines in their breeding history. For this germplasm collection, genome-wide LD estimates were generally less than 1 cM for the genetically linked loci pairs. This may result from the population stratification and small sample size that reduced statistical power. Most of the LD regions observed were between loci less than 10 cM apart. However, the distribution of LD was not uniform based on linkage distance and was independent of marker density. Consequently, LD is likely to vary widely among wheat populations. [ABSTRACT FROM AUTHOR]

A digital terrestrial television broadcasting (DTTB) standard named ‘Frame structure, channel coding and modulation for digital television terrestrial broadcasting system‘ was published in China in August 2006. This is the first paper of a series that provide a complete and in depth description to the standard including laboratory and field measurement results, detailed analysis on technologies in achieving stable fixed reception and fast mobile reception, as well as methodologies in spectrum allocation, and principles and technologies in performing single frequency network operation. Among the hundreds of operation modes to support multi-program SDTV/HDTV terrestrial services in the standard, the key features and major applications of a series of modes named ‘PN595 + C1’ are described in detail. Measurement re- suits of PN595 + C1 are also presented to demonstrate the satisfactory performances in fixed reception and high speed mobile reception. [ABSTRACT FROM AUTHOR]

Tetracyclines are aromatic polyketides biosynthesized by bacterial type II polyketide synthases (PKSs). Understanding the biochemistry of tetracycline PKSs is an important step toward the rational and combinatorial manipulation of tetracycline biosynthesis. To this end, we have sequenced the gene cluster of oxytetracycline (oxy and otc genes) PKS genes from Streptomyces rimosus. Sequence analysis revealed a total of 21 genes between the otrA and otrB resistance genes. We hypothesized that an amidotransferase, OxyD, synthesizes the malonamate starter unit that is a universal building block for tetracycline compounds. In vivo reconstitution using strain CH999 revealed that the minimal PKS and OxyD are necessary and sufficient for the biosynthesis of amidated polyketides. A novel alkaloid (WJ35, or compound 2) was synthesized as the major product when the oxy-encoded minimal PKS, the C-9 ketoreductase (OxyJ), and OxyD were coexpressed in CH999. WJ35 is an isoquinolone compound derived from an amidated decaketide backbone and cyclized with novel regioselectivity. The expression of OxyD with a heterologous minimal PKS did not afford similarly amidated polyketides, suggesting that the oxy-encoded minimal PKS possesses novel starter unit specificity. [ABSTRACT FROM AUTHOR]

Chromosome 7E from Lophopyrum ponticum carries a valuable leaf rust resistant gene designated Lr19. This gene has not been widely used in common wheat breeding because of linkage with the yellow pigment gene Y. This gene tints flour yellow, reducing its appeal in bread making. However, a high level of yellow pigment is desirable in durum wheat breeding. We produced 97 recombinant chromosomes between L. ponticum transfer 7D.7E#1 and its wheat homoeologues, using the ph1b mutation that promotes homoeologous pairing. We characterized a subset of 37 of these lines with 11 molecular markers and evaluated their resistance to leaf rust and the abundance of yellow pigment. The Lr19 gene was mapped between loci Xwg420 and Xmwg2062, whereas Y was mapped distal to Xpsr687, the most distal marker on the long arm of chromosome 7. A short terminal 7EL segment translocated to 7A, including Lr19 and Y (line 1-23), has been transferred to durum wheat by backcrossing. The presence of this alien segment significantly increased the abundance of yellow pigment. The Lr19 also conferred resistance to a new durum leaf rust race from California and Mexico that is virulent on most durum wheat cultivars. The new durum lines with the recombinant 7E segment will be useful parents to increase yellow pigment and leaf rust resistance in durum wheat breeding programs. For the common wheat breeding programs, we selected the recombinant line 1-96, which has an interstitial 7E segment carrying Lr19 but not Y. This recombinant line can be used to improve leaf rust resistance without affecting flour color. The 7EL/7DL 1-96 recombinant chromosome did not show the meiotic self-elimination previously reported for a 7EL/7BL translocation. [ABSTRACT FROM AUTHOR]