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Gal Sapir

Bio: Gal Sapir is an academic researcher from Hebrew University of Jerusalem. The author has contributed to research in topics: Lactate dehydrogenase & Pyruvate dehydrogenase complex. The author has an hindex of 9, co-authored 29 publications receiving 232 citations.

Papers
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TL;DR: It is shown that Sn-RNase does not prevent fertilization by Si-pollen haplotype, thus presenting a case in which RHV is not required for the determination of specific pollen rejection by S- RNase, and implying that other regions in the enzyme may be sufficient for this specificity.
Abstract: In the gametophytic self-incompatibility system, growth of self-pollen tubes in the style is inhibited in a haplotype-specific manner by S-RNase. The mechanism by which S-RNase confers its specificity is unknown. However, a hypervariable region (RHV in Rosaceae and HVa-HVb in Solanaceae) that differs among the many cloned S-RNase alleles has been proposed to be involved in conferring the S-haplotype specificity of the S-RNase. Region swapping experiments between S-RNases and crystallography of the enzyme support this assumption. However, the deduced amino acid sequences of Sn-RNase and Si-RNase alleles from the European pear (Pyrus communis) were recently found to have an identical RHV. In the present study it is shown that Sn-RNase does not prevent fertilization by Si-pollen haplotype, thus presenting a case in which RHV is not required for the determination of specific pollen rejection by S-RNase, and implying that other regions in the enzyme may be sufficient for this specificity.

49 citations

01 Jan 2007
TL;DR: In Japanese plum, highest bee activity, fruit set and yield, were achieved when colonies were introduced at four different times (multiple introductions), and there was a positive and statistically significant correlation between the average number of bees tree -1 and fruit set or yield.
Abstract: Most of the Rosaceae fruit trees, such as apple, pear, plum, almond and cherry, exhibit full self-incompatibility. Therefore, their fruit production completely depends on cross pollination. The ultimate pollen carrier in Rosaceae is the honey bee. In the present review, different bee-hive management techniques for improving fruit set and yield are discussed. The main manipulations are of colony density and the timing and number of colony introductions. In pear, it was found that increasing the density from 2.5 colonies ha -1 to 5 colonies ha -1 in one introduction at 10% full bloom (FB), did not increase bee activity on the trees and did not improve fruit set and yield. However, introducing the colonies sequentially (1.25 colonies ha -1 at 10% FB and 1.25 colonies ha -1 at FB) increased bee activity and consequently improved fruit set and yield. In apple, the combination of both treatments: increasing the density to 2.5 colonies ha -1 at 10% FB and a second introduction of 2.5 colonies ha -1 at FB, for a total of 5 colonies ha -1 , increased the number of bees tree -1 , their mobility between the rows and the proportion of “topworkers” compared with “sideworkers”. As a result, fruit set and yield were enhanced. In Japanese plum, highest bee activity, fruit set and yield, were achieved when colonies were introduced at four different times (multiple introductions). Each introduction was of a density of 1.25 colonies ha -1 at 10% FB, 50% FB, FB and FB+3 days (total of 5 colonies ha -1 ). For all three species, there was a positive and statistically significant correlation between the average number of bees tree -1 and fruit set or yield. The optimum number of bees tree -1 min -1 at FB was 6-7 for pear, 7-8 for Japanese plum and 12-14 for apple.

27 citations

Journal ArticleDOI
TL;DR: The authors show dissolution-dynamic nuclear polarization technology can enable nuclear magnetic resonance detection of hyperpolarized 31P of important biological phosphates in aqueous solutions and opens up avenues for real-time monitoring of phosphate metabolism, distribution, and pH sensing in the live body without ionizing radiation.
Abstract: The dissolution-dynamic nuclear polarization technology had previously enabled nuclear magnetic resonance detection of various nuclei in a hyperpolarized state. Here, we show the hyperpolarization of 31P nuclei in important biological phosphates (inorganic phosphate and phosphocreatine) in aqueous solutions. The hyperpolarized inorganic phosphate showed an enhancement factor >11,000 (at 5.8 T, 9.3% polarization) in D2O (T1 29.4 s). Deuteration and the solution composition and pH all affected the lifetime of the hyperpolarized state. This capability opens up avenues for real-time monitoring of phosphate metabolism, distribution, and pH sensing in the live body without ionizing radiation. Immediate changes in the microenvironment pH have been detected here in a cell-free system via the chemical shift of hyperpolarized inorganic phosphate. Because the 31P nucleus is 100% naturally abundant, future studies on hyperpolarized phosphates will not require expensive isotope labeling as is usually required for hyperpolarization of other substrates. Real-time monitoring of phosphate metabolism and distribution in the live body without ionizing radiation is highly desirable. Here, the authors show dissolution-dynamic nuclear polarization technology can enable nuclear magnetic resonance detection of hyperpolarized 31P of important biological phosphates in aqueous solutions.

25 citations

Journal ArticleDOI
TL;DR: The purpose of this study was to demonstrate the use of PCLS for hyperpolarized metabolic investigation in a mouse model, for potential future application in liver biopsy cores.
Abstract: Precision-cut liver slices (PCLS) are widely used in liver research as they provide a liver model with all liver cell types in their natural architecture. The purpose of this study was to demonstrate the use of PCLS for hyperpolarized metabolic investigation in a mouse model, for potential future application in liver biopsy cores. Fresh normal liver was harvested from six mice. 500 μm PCLS were prepared and placed in a 10 mm NMR tube in an NMR spectrometer and perfused continuously. 31 P spectra were acquired to evaluate the presence of adenosine triphosphate (ATP) and validate viability in all samples. Hyperpolarized [1-13 C]pyruvate was flushed into the NMR tube in the spectrometer. Consecutive 13 C NMR spectra were acquired immediately after the injection using both non-selective (five injections, two livers) and selective RF excitation (six injections, three livers). The 31 P spectra showed the characteristic signals of ATP, confirming the viability of the PCLS for more than 2.5 h in the spectrometer. After each of the [1-13 C]pyruvate injections, both [1-13 C]lactate and [1-13 C]alanine signals were detected. Selective RF excitation aimed at both [1-13 C]lactate and [1-13 C]alanine enabled better visualization and quantification of the metabolic activity. Using this acquisition approach only the newly formed metabolites are observed upon excitation, and their intensities relative to those of hyperpolarized pyruvate enable quantification of metabolite production rates. This rate of lactate and alanine production appeared to be constant throughout the measurement time, with alanine production about 2.3 times higher than lactate. In summary, the viability of PCLS in an NMR spectrometer was demonstrated and hyperpolarized [1-13 C]pyruvate metabolism was recorded. This study opens up the possibility of evaluating alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) activities in human liver biopsies, while preserving the tissue architecture and viability. In healthy, well-perfused liver slices the ratio of ALT to LDH activity is about 2.3.

17 citations

Journal ArticleDOI
TL;DR: In the present study, fruit-set of semi- and fully compatible plum couples was determined for a wide range of cultivars, in unfavorable and favorable conditions.

17 citations


Cited by
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Journal ArticleDOI
TL;DR: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors.
Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

6,968 citations

Journal ArticleDOI
TL;DR: The impact of CD39 expression and ectonucleotidase activity on immunity with a focus on the setting of oncology is reviewed and the implications for immunotherapy strategies targeting CD39 are discussed, including their inclusion in rational combination therapies.
Abstract: The ATP-adenosine pathway functions as a key modulator of innate and adaptive immunity within the tumour microenvironment. Consequently, multiple clinical strategies are being explored to target this pathway for the treatment of cancer; in particular, recent clinical data with CD73 antagonists and inhibitors of A2A receptors have demonstrated the therapeutic potential of modulating this pathway. Now, inhibitors of the ectonucleotidase CD39, the rate-limiting enzyme in the conversion of ATP to immunomodulatory adenosine, are entering clinical trials. Consequently, there is currently a focus on understanding the impact of CD39 enzymatic function on innate and adaptive immunity and how therapeutic modulation of this pathway alters their functional potential within the tumour microenvironment. Recent findings reveal multipronged mechanisms of action of CD39 antagonism that rely not only on preventing the accumulation of adenosine but also on the stabilization of pro-inflammatory extracellular ATP to restore antitumour immunity. Here, we review the impact of CD39 expression and ectonucleotidase activity on immunity with a focus on the setting of oncology. Additionally, we discuss the implications for immunotherapy strategies targeting CD39, including their inclusion in rational combination therapies.

146 citations

Journal ArticleDOI
TL;DR: This review concludes that pollen incompatibility is the default condition unless the S-locus F-box protein confers resistance to S-RNase, and two alternative mechanisms have been proposed to explain compatibility and incompatibility.

146 citations

Journal ArticleDOI
TL;DR: This study proposes a model for the divergence, dissemination, and independent domestication of Asian and European pears in which pear has eventually spread to western Asia, and then on to Europe, thus promoting outcrossing and accounting for pear genome diversity across the Eurasian continent.
Abstract: Pear (Pyrus) is a globally grown fruit, with thousands of cultivars in five domesticated species and dozens of wild species. However, little is known about the evolutionary history of these pear species and what has contributed to the distinct phenotypic traits between Asian pears and European pears. We report the genome resequencing of 113 pear accessions from worldwide collections, representing both cultivated and wild pear species. Based on 18,302,883 identified SNPs, we conduct phylogenetics, population structure, gene flow, and selective sweep analyses. Furthermore, we propose a model for the divergence, dissemination, and independent domestication of Asian and European pears in which pear, after originating in southwest China and then being disseminated throughout central Asia, has eventually spread to western Asia, and then on to Europe. We find evidence for rapid evolution and balancing selection for S-RNase genes that have contributed to the maintenance of self-incompatibility, thus promoting outcrossing and accounting for pear genome diversity across the Eurasian continent. In addition, separate selective sweep signatures between Asian pears and European pears, combined with co-localized QTLs and differentially expressed genes, underline distinct phenotypic fruit traits, including flesh texture, sugar, acidity, aroma, and stone cells. This study provides further clarification of the evolutionary history of pear along with independent domestication of Asian and European pears. Furthermore, it provides substantive and valuable genomic resources that will significantly advance pear improvement and molecular breeding efforts.

115 citations

Journal ArticleDOI
TL;DR: Molecular and genetic analyses of Prunus SC S haplotypes and polyploid sour cherry (Prunus cerasus) reveal the possible existence of a distinct SI/SC recognition mechanism in the S-RNase-based GSI system of Prinus.

114 citations