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431.
Noor Mruwat Michael C. G. Carlson Svetlana Goldin Franois Ribalet Shay Kirzner Yotam Hulata Stephen J. Beckett Dror Shitrit Joshua S. Weitz E. Virginia Armbrust Debbie Lindell 《The ISME journal》2021,15(1):41
Long-term stability of picocyanobacteria in the open oceans is maintained by a balance between synchronous division and death on daily timescales. Viruses are considered a major source of microbial mortality, however, current methods to measure infection have significant methodological limitations. Here we describe a method that pairs flow-cytometric sorting with a PCR-based polony technique to simultaneously screen thousands of taxonomically resolved individual cells for intracellular virus DNA, enabling sensitive, high-throughput, and direct quantification of infection by different virus lineages. Under controlled conditions with picocyanobacteria-cyanophage models, the method detected infection throughout the lytic cycle and discriminated between varying infection levels. In North Pacific subtropical surface waters, the method revealed that only a small percentage of Prochlorococcus (0.35–1.6%) were infected, predominantly by T4-like cyanophages, and that infection oscillated 2-fold in phase with the diel cycle. This corresponds to 0.35–4.8% of Prochlorococcus mortality daily. Cyanophages were 2–4-fold more abundant than Prochlorococcus, indicating that most encounters did not result in infection and suggesting infection is mitigated via host resistance, reduced phage infectivity and inefficient adsorption. This method will enable quantification of infection for key microbial taxa across oceanic regimes and will help determine the extent that viruses shape microbial communities and ecosystem level processes.Subject terms: Microbial ecology, Microbial biooceanography, Molecular ecology, Microbial ecology, Microbial biooceanography 相似文献
432.
The zona pellucida (ZP) is the extracellular coat surrounding the mammalian egg. Numerious evidence supports the role of ZP
carbohydrate residues as the specific sperm receptors. In this study we used lectins to study different distribution patterns
of carbohydrate residues in the rat ZP, and to follow changes at fertilization. ZP were collected from follicular, ovulated,
and fertilized eggs, incubated with one of 11 different biotin-labeled lectins, followed by avidin-fluorescein isothiocyanate
(FITC) complex, and visualized by epifluorescent microscopy. For electron microscope (EM) histochemistry, eggs were embedded
in LR white and ultrathin sections were stained with the complexRicinus communis lectin (RCA-1)-colloidal gold. Some lectins (RCA-I,Glycine max) bound to the entire ZP while others were restricted to the inner or outer zones [Griffonia simplicifolia, Concanovalia ensiformis, Triticum vulgaris (WGA), succinyl-WGA]. Other lectins (Lens culinaris, Ulex europhaeus) were totally excluded. The RCA-1 binding pattern changed following sperm penetration, from homogeneous in ZP of ovulated
eggs (57%) to uneven in ZP of fertilized (71%) or activated (68%) eggs. Our results demonstrate an uneven distribution of
different sugar residues in the rat ZP, and a post-fertilization change in the distribution of β-galactose, which is specifically
recognized by RCA-I, presumably correlated with other changes in the ZP that lead to the block to polyspermy.
This work is in partial fulfillment of the requirements for the PhD degree of Tamar Raz at the Sackler School of Medicine,
Tel Aviv University 相似文献
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436.
Tumor autocrine motility factor is an angiogenic factor that stimulates endothelial cell motility. 总被引:4,自引:0,他引:4
T Funasaka A Haga A Raz H Nagase 《Biochemical and biophysical research communications》2001,285(1):118-128
Autocrine motility factor (AMF) is a type of tumor-secreted cytokine which primarily stimulates tumor cell motility via receptor-mediated signaling pathways, and is thought to be connected to tumor progression and metastasis. Using in vivo models, we showed that critical neovascularization responded to a biological amount of AMF. This angiogenic activity was fixed by specific inhibitors against AMF. AMF stimulated in vitro motility of human umbilical vein endothelial cells (HUVECs), inducing the expression of cell surface AMF receptor localizing a single predominant perinuclear pattern closely correlated with its motile ability. AMF also elicited the formation of tube-like structures mimicking angiogenesis when HUVECs were grown in three-dimensional type I collagen gels. We further immunohistochemically detected AMF receptors on the surrounding sites of newborn microvessels. These findings suggest that AMF is a possible tumor progressive angiogenic factor which may act in a paracrine manner for the endothelial cells in the clinical neoplasm, and it will be a new target for antiangiogenic treatment. 相似文献
437.
Bolaji Babajide Salam Francois Barbier Raz Danieli Paula Teper-Bamnolker Carmit Ziv Luk Spíchal Kalaivani Aruchamy Yula Shnaider Diana Leibman Felix Shaya Mira Carmeli-Weissberg Amit Gal-On Jiming Jiang Naomi Ori Christine Beveridge Dani Eshel 《Plant physiology》2021,185(4):1708
Shoot branching is an important aspect of plant architecture because it substantially affects plant biology and agricultural performance. Sugars play an important role in the induction of shoot branching in several species, including potato (Solanum tuberosum L.). However, the mechanism by which sugars affect shoot branching remains mostly unknown. In the present study, we addressed this question using sugar-mediated induction of bud outgrowth in potato stems under etiolated conditions. Our results indicate that sucrose feeding to detached stems promotes the accumulation of cytokinin (CK), as well as the expression of vacuolar invertase (VInv), an enzyme that contributes to sugar sink strength. These effects of sucrose were suppressed by CK synthesis and perception inhibitors, while CK supplied to detached stems induced bud outgrowth and VInv activity in the absence of sucrose. CK-induced bud outgrowth was suppressed in vinv mutants, which we generated by genome editing. Altogether, our results identify a branching-promoting module, and suggest that sugar-induced lateral bud outgrowth is in part promoted by the induction of CK-mediated VInv activity.Sugar-induced lateral bud outgrowth is promoted by the induction of cytokinin and vacuolar invertase activity. 相似文献
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The complex embryonic phenotype of mutations in the faint little ball (flb) locus, encoding the Drosophila EGF receptor homolog (DER), was dissected by temperature shifts of a temperature-sensitive allele. We show that the phenotype can be resolved into at least five components, which are temporally and spatially distinct. Most notably, the central nervous system (CNS) phenotype is determined at two separate phases. A severe collapse results from early defects in the DER-expressing ectodermal cells from which neuroblasts and midline glial cells deaminate. We thus suggest that DER activity is crucial for interactions that occur in the ectoderm at an early stage, and determine the fate of neuronal and glial cell lineages. This finding explains how a severe CNS phenotype is generated in flb embryos, in spite of the absence of expression of the protein in neuronal cells. In a second phase, during germ band retraction, the flb function is required specifically in the three pairs of midline glial cells (MG). In the absence of a functional DER protein, these cells die or fail to differentiate correctly, resulting in a fused commissure phenotype. 相似文献