Na+/K+/Cl- cotransport in resealed ghosts from erythrocytes of the Milan hypertensive rats.

The erythrocytes (RBC) of the Milan hypertensive rats (MHS) have a smaller volume and faster Na+/K+/Cl- cotransport than RBC from normotensive controls (MNS). The difference in Na+/K+/Cl- cotransport is no longer present in inside-out Vesicles (IOV) of RBC membrane. To differentiate between cytoplasmic or membrane skeleton abnormalities as possible causes of these differences. Resealed ghosts (RG) were used to measure ion transport systems. The following results have been obtained: (1) RG from MHS have a smaller volume than MNS (mean +/- S.E. 20.7 +/- 0.45 vs. 22.09 +/- 0.42 fl, P < 0.05). (2) RG showed a bumetanide-sensitive Na efflux that retains the characteristics of the Na+/K+/Cl- cotransport of the original RBC: it is K(+)- and Cl(-)-sensitive and dependent on the intracellular Na+ concentration. (3) The Na+/K+/Cl- cotransport was faster in RG from MHS than in those from MNS (mean +/- S.E. 0.095 +/- 0.01 vs. 0.066 +/- 0.01 rate constant h-1, P < 0.01). These results, together with those of IOV, support the hypothesis that an abnormality in the membrane skeletal proteins may play a role in the different Na+/K+/Cl- cotransport modulation between MHS and MNS erythrocytes.     

High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

Conformational studies on actinomycin

A model of the Actinomycin structure is derived on the basis of theoretical calculations taking into account available IR, NMR and x-ray experimental data. This model contains two intercycle hydrogen bonds and accounts for all the experimental evidence.     

Comparison of the pick-and-smear and Saccomanno methods for sputum cytologic analysis

The two methods of preparing sputum specimens for cytologic study, the (fresh) pick-and-smear technique and the (blended) Saccomanno technique, were compared using 249 consecutive specimens. Two slides were prepared for each specimen by each technique. Of the specimens, 103 showed squamous metaplasia, carcinoma in situ or carcinoma. A semiquantitative rating system (0 to 4+) was used to determine the number of diagnostic cells for each method for those 103 cases. More diagnostic cells were found on the Saccomanno preparations (217) than on the fresh preparations (154). There were 121 diagnostic cells in the Saccomanno preparations versus 95 diagnostic cells in the fresh preparations from 63 squamous metaplasias; 7 versus 3 for the preparations from 5 carcinomas in situ; 64 versus 42 from 28 squamous cell carcinomas; 3 versus 1 from 1 large cell undiffernomas; and 12 diagnostic cells in Saccomanno preparations versus 5 in fresh preparations from 3 small cell cancers. Twelve squamous metaplasias, two carcinomas in situ, four squamous carcinomas, one adenocarcinoma and one small cell cancer had no diagnostic cells on the fresh preparations; four squamous metaplasias and one squamous carcinoma had no diagnostic cells on the Saccomanno preparations. More diagnostic information and fewer false-negative results were achieved with the Saccomanno technique.     

Small molecule scaffolds that disrupt the Rev1-CT/RIR protein-protein interaction

Translesion synthesis (TLS) is a DNA damage tolerance mechanism that allows replicative bypass of DNA lesions, including DNA adducts formed by cancer chemotherapeutics. Previous studies demonstrated that suppression of TLS can increase sensitivity of cancer cells to first-line chemotherapeutics and decrease mutagenesis linked to the onset of chemoresistance, marking the TLS pathway as an emerging therapeutic target. TLS is mediated by a heteroprotein complex consisting of specialized DNA polymerases, including the Y-family DNA polymerase Rev1. Previously, we developed a screening assay to identify the first small molecules that disrupt the protein–protein interaction between the C-terminal domain of Rev1 (Rev1-CT) and the Rev1-interacting region (RIR) present in multiple DNA polymerases involved in TLS. Herein we report additional hit scaffolds that inhibit this key TLS PPI. In addition, through a series of biochemical, computational, and cellular studies we have identified preliminary structure–activity relationships and determined initial pharmacokinetic parameters for our original hits.     

Activities of glycolipid glycosyltransferases and sialidases during the early development of Xenopus laevis

The activities of glycosyltransferases and sialidases, together with the ganglioside content and distribution, have been extensively studied in mammals, while the informations on tissues of other animals, including amphibian, are scarce. In this paper we present data on the activities of SAT-1, SAT-2, SAT-4, SAT-5, GlcNAcT-1, GalNAcT-1, GalT-6, and sialidases studied in Xenopus laevis embryos at different stages of development. The highest activity was found at days 4 and 5 of embryogenesis for glycosyltransferases and sialidases respectively; a tentative correlation between the in vitro activity of these enzymes and the content of neutral and acidic glycolipids is discussed. (Mol Cell Biochem 166: 117-124, 1997)