Comparison of Directly Prepared and Cultured Cells in Karyotypic Analysis of All

An evaluation of methods for studying bone marrow obtained from patients with acute lymphoblastic leukemia indicates that both directly prepared and cultured cells are necessary for complete karyotypic analysis, but that both synchronized and unsynchronized cultures may not be necessary.     

Dictyostelium Myb transcription factors function at culmination as activators of ancillary stalk differentiation

ecmB and mrrA are expressed in the cups that cradle Dictyostelium spore heads, and MybE is necessary for their expression in lower but not upper cup cells. A Myb site within the mrrA promoter is necessary for expression in both cups. Thus, multiple Myb proteins are required for ancillary stalk differentiation.     

Carbon Dioxide Infra-Red Gas Analysis: EFFECTS OF WATER VAPOUR

Theory shows that it is nearly always necessary to correct carbondioxide infra-red gas analyses for the presence of water vapour.The necessary corrections are derived for both an analyser fittedwith selective filters and where the air is dried for use inleaf-chamber experiments and also for measurements of absolutecarbon dioxide concentrations and determinations of field profiles.The magnitudes of the corrections are determined for typicalexamples.     

Evolution of the neural basis of consciousness: a bird-mammal comparison

The main objective of this essay is to validate some of the principal, currently competing, mammalian consciousness-brain theories by comparing these theories with data on both cognitive abilities and brain organization in birds. Our argument is that, given that multiple complex cognitive functions are correlated with presumed consciousness in mammals, this correlation holds for birds as well. Thus, the neuroanatomical features of the forebrain common to both birds and mammals may be those that are crucial to the generation of both complex cognition and consciousness. The general conclusion is that most of the consciousness-brain theories appear to be valid for the avian brain. Even though some specific homologies are unresolved, most of the critical structures presumed necessary for consciousness in mammalian brains have clear homologues in avian brains. Furthermore, considering the fact that the reptile-bird brain transition shows more structural continuity than the stem amniote-mammalian transition, the line drawn at the origin of mammals for consciousness by several of the theorists seems questionable. An equally important point is that consciousness cannot be ruled out in the absence of complex cognition; it may in fact be the case that consciousness is a necessary prerequisite for complex cognition.     

Notch-mediated segmentation and growth control of the Drosophila leg.

The possession of segmented appendages is a defining characteristic of the arthropods. By analyzing both loss-of-function and ectopic expression experiments, we show that the Notch signaling pathway plays a fundamental role in the segmentation and growth of the Drosophila leg. Local activation of Notch is necessary and sufficient to promote the formation of joints between segments. This segmentation process requires the participation of the Notch ligands, Serrate and Delta, as well as Fringe. These three proteins are each expressed in the developing leg and antennal imaginal discs in a segmentally repeated pattern that is regulated downstream of the action of Wingless and Decapentaplegic. Our studies further show that Notch activation is both necessary and sufficient to promote leg growth. We also identify target genes regulated both positively and negatively downstream of Notch signaling that are required for normal leg development. Together, these observations outline a regulatory hierarchy for the segmentation and growth of the leg. The Notch pathway is also deployed for segmentation during vertebrate somitogenesis, which raises the possibility of a common origin for the segmentation of these distinct tissues.     

Characterization of the existence of galled-tree networks

In this paper, we give a complete characterization of the existence of a galled-tree network in the form of simple sufficient and necessary conditions for both root-known and root-unknown cases. As a by-product we obtain a simple algorithm for constructing galled-tree networks. We also introduce a new necessary condition for the existence of a galled-tree network similar to bi-convexity.     

RACK1 is necessary for the formation of point contacts and regulates axon growth

Receptor for activated C kinase 1 (RACK1) is a multifunctional ribosomal scaffolding protein that can interact with multiple signaling molecules concurrently through its seven WD40 repeats. We recently found that RACK1 is localized to mammalian growth cones, prompting an investigation into its role during neural development. Here, we show for the first time that RACK1 localizes to point contacts within mouse cortical growth cones. Point contacts are adhesion sites that link the actin network within growth cones to the extracellular matrix, and are necessary for appropriate axon guidance. Our experiments show that RACK1 is necessary for point contact formation. Brain‐derived neurotrophic factor (BDNF) stimulates an increase in point contact density, which was eliminated by RACK1 shRNA or overexpression of a nonphosphorylatable mutant form of RACK1. We also found that axonal growth requires both RACK1 expression and phosphorylation. We have previously shown that the local translation of β‐actin mRNA within growth cones is necessary for appropriate axon guidance and is dependent on RACK1. Thus, we examined the location of members of the local translation complex relative to point contacts. Indeed, both β‐actin mRNA and RACK1 colocalize with point contacts, and this colocalization increases following BDNF stimulation. This implies the novel finding that local translation is regulated at point contacts. Taken together, these data suggest that point contacts are a targeted site of local translation within growth cones, and RACK1 is a critical member of the point contact complex and necessary for appropriate neural development. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1038–1056, 2017     

Role of heparin in the realization of the hypoglycemic action of insulin

The presence of reactive heparin in blood circulation is necessary for realization of the hypoglycemic action of insulin. This is confirmed by the fact that after heparin binding by protamin sulfate both endogenous and exogenous insulin do not exhibit any hypoglycemic activity. In animals with different basal concentration of heparin in the blood, the blockade of insulin action is attained by application of different doses of protamin sulfate, respectively. Based on the data obtained one can determine an approximate blood heparin concentration necessary for realization of the hypoglycemic action of insulin.     

The sorting sequence of the peroxisomal integral membrane protein PMP47 is contained within a short hydrophilic loop

No targeting sequence for peroxisomal integral membrane proteins has yet been identified. We have previously shown that a region of 67 amino acids is necessary to target Pmp47, a protein that spans the membrane six times, to peroxisomes. This region comprises two membrane spans and the intervening loop. We now demonstrate that the 20 amino acid loop, which is predicted to face the matrix, is both necessary and sufficient for peroxisomal targeting. Sufficiency was demonstrated with both chloramphenicol acetyltransferase and green fluorescent protein as carriers. There is a cluster of basic amino acids in the middle of the loop that we predict protrudes from the membrane surface into the matrix by a flanking stem structure. We show that the targeting signal is composed of this basic cluster and a block of amino acids immediately down-stream from it.     

Attractive and repulsive functions of Slit are mediated by different receptors in the Drosophila trachea

Oxygen delivery in many animals is enabled by the formation of unicellular capillary tubes that penetrate target tissues to facilitate gas exchange. We show that the tortuous outgrowth of tracheal unicellular branches towards their target tissues is controlled by complex local interactions with target cells. Slit, a phylogenetically conserved axonal guidance signal, is expressed in several tracheal targets and is required both for attraction and repulsion of tracheal branches. Robo and Robo2 are expressed in different branches, and are both necessary for the correct orientation of branch outgrowth. At the CNS midline, Slit functions as a repellent for tracheal branches and this function is mediated primarily by Robo. Robo2 is necessary for the tracheal response to the attractive Slit signal and its function is antagonized by Robo. We propose that the attractive and repulsive tracheal responses to Slit are mediated by different combinations of Robo and Robo2 receptors on the cell surface.     

Antiviral Activity produced by the Polycytidylic Acid-Hexainosinate System

Experiments with poly C oligo I indicate that both components are necessary for interferon induction and that the secondary structure of the polymer is not critical.     

生防菌对土壤微生态影响的风险评估

土壤微生物在地理生物化学循环过程中起着极其重要的作用。在农业生态系统中,土壤微生物通过降解植物残体为植物提供营养,同时维持植物生产所需的土壤性质。生防菌的引入可能会破坏土壤原有微生物的群落结构和功能,从而对整个生态系统造成有害的影响,因此不论生防菌有无经过基因修饰,在商业化应用前必须对其在农业生态环境中的行为和对土壤生态系统的潜在影响进行风险评估。     

Poly(ADP-ribose) polymerase-1-mediated cell death in astrocytes requires NAD+ depletion and mitochondrial permeability transition

Extensive activation of poly(ADP-ribose) polymerase-1 (PARP-1) by DNA damage is a major cause of caspase-independent cell death in ischemia and inflammation. Here we show that NAD(+) depletion and mitochondrial permeability transition (MPT) are sequential and necessary steps in PARP-1-mediated cell death. Cultured mouse astrocytes were treated with the cytotoxic concentrations of N-methyl-N'-nitro-N-nitrosoguanidine or 3-morpholinosydnonimine to induce DNA damage and PARP-1 activation. The resulting cell death was preceded by NAD(+) depletion, mitochondrial membrane depolarization, and MPT. Sub-micromolar concentrations of cyclosporin A blocked MPT and cell death, suggesting that MPT is a necessary step linking PARP-1 activation to cell death. In astrocytes, extracellular NAD(+) can raise intracellular NAD(+) concentrations. To determine whether NAD(+) depletion is necessary for PARP-1-induced MPT, NAD(+) was restored to near-normal levels after PARP-1 activation. Restoration of NAD(+) enabled the recovery of mitochondrial membrane potential and blocked both MPT and cell death. Furthermore, both cyclosporin A and NAD(+) blocked translocation of the apoptosis-inducing factor from mitochondria to nuclei, a step previously shown necessary for PARP-1-induced cell death. These results suggest that NAD(+) depletion and MPT are necessary intermediary steps linking PARP-1 activation to AIF translocation and cell death.