Advantages of the scanning ion microscopy for mapping halogen corticoids in normal and transformed cells in culture

Summary— The intra-cellular distribution of eight halogen glucocorticoids was investigated by ion microscopy in two cellular varieties of cultured non-cancer cells (fibroblast 3T3) and cancer cells (human breast tumor cells MCF-7). Two types of ion microscopy helped to determine this distribution, a direct imaging ion microscope (SMI 300) with low spatial resolution, and a scanning ion microscope (IMS4F), featuring high resolution, serving to obtain maps representing the intra-cellular distribution of the fluorine elements and drugs present in these monolayer cultured cells. The fluorine images representative of the drugs containing fluorine showed that these drugs are essentially concentrated in the cell nuclei. In these nuclei, the distribution of these drugs is different from that of heterochromatin and of the nucleolus.     

Behavior of Colonial Orb-weaving Spiders during a Solar Eclipse

The behavior of colonial orb-weaving spiders (Metepeira incrassata) in tropical Veracruz, Mexico was studied during the total solar eclipse on July 11, 1991. Spiders behaved in a manner typical of daily activity until totality, when many began taking down webs. After solar reappearance, most spiders that had begun taking down webs rebuilt them. There was no significant difference in the overall activity patterns of spiders during totality across a range of colony sizes. Experimental illumination of part of a colony during totality altered web takedown behavior. While spiders in the darkness of totality began to take down webs, those spiders which were artificially illuminated did not. These observations suggest that the primary environmental cue responsible for the daily rhythm of web building behavior in this species is light level.     

An attempt to correlate brain areas containing melatonin-binding sites with rhythmic functions: a study in five hibernator species

High affinity melatonin-binding sites have been described, by means of autoradiography with 2-¹²⁵I-melatonin as the ligand, in more than 60 brain areas of about 20 mammalian species, with dramatic variations in the nature and number of labelled structures among the different species studied. As melatonin is involved in the synchronization of biological rhythms, we have tried to correlate the brain areas containing melatonin-binding sites with some rhythmic functions typical of give species. Therefore, we have studied the location of melatonin-binding sites in the complete brain of five long-day breeders with hibernation cycles, viz. one insectivore and four rodents. With the exception of the suprachiasmatic nuclei and the pars tuberalis of the pituitary, both of which contain binding sites in all five species, few reactive structures are common, even among species from the same family, e.g. the edible dormouse and the garden dormouse.     

Genetic Bit Analysis: a solid phase method for typing single nucleotide polymorphisms.

A new method for typing single nucleotide polymorphisms in DNA is described. In this method, specific fragments of genomic DNA containing the polymorphic site(s) are first amplified by the polymerase chain reaction (PCR) using one regular and one phosphorothioate-modified primer. The double-stranded PCR product is rendered single-stranded by treatment with the enzyme T7 gene 6 exonuclease, and captured onto individual wells of a 96 well polystyrene plate by hybridization to an immobilized oligonucleotide primer. This primer is designed to hybridize to the single-stranded target DNA immediately adjacent from the polymorphic site of interest. Using the Klenow fragment of E. coli DNA polymerase I or the modified T7 DNA polymerase (Sequenase), the 3' end of the capture oligonucleotide is extended by one base using a mixture of one biotin-labeled, one fluorescein-labeled, and two unlabeled dideoxynucleoside triphosphates. Antibody conjugates of alkaline phosphatase and horseradish peroxidase are then used to determine the nature of the extended base in an ELISA format. This paper describes biochemical features of this method in detail. A semi-automated version of the method, which we call Genetic Bit Analysis (GBA), is being used on a large scale for the parentage verification of thoroughbred horses using a predetermined set of 26 diallelic polymorphisms in the equine genome.     

The PIR-International Protein Sequence Database.

PIR-International is an association of macromolecular sequence data collection centers dedicated to fostering international cooperation as an essential element in the development of scientific databases. A major objective of PIR-International is to continue the development of the Protein Sequence Database as an essential public resource for protein sequence information. This paper briefly describes the architecture of the Protein Sequence Database and how it and associated data sets are distributed and can be accessed electronically.     

Restriction generated oligonucleotides utilizing the two base recognition endonuclease CviJI*.

The conversion of an anonymous DNA sample into numerous oligonucleotides is enzymatically feasible using an unusual restriction endonuclease, CviJI. Depending on reaction conditions, CviJI is capable of digesting DNA at a two or three base recognition sequence. CviJI normally cleaves RGCY sites between the G and C to leave blunt ends. Under 'relaxed' conditions CviJI* cleaves RGCY, and RGCR/YGCY, but not YGCR sites. In theory, CviJI* restriction of pUC19 (2686 bp) should produce 157 fragments, 75% of which are smaller than 20 bp. Instead, 96% of the CviJI* fragments were 18-56 bp long and none of the fragments were smaller than 18 bp. Thermal denaturation of these fragments generates sequence specific oligonucleotides homologous for the cognate template. The enzymatic conversion of anonymous DNA into sequence specific oligomers has implications for several conventional and novel molecular biology procedures.     

The new politics of exclusion: Antecedents to the rebellion in Mexico

Thatcherism's search for the enemies within; its operations across the different lines of division and identification in social life...its rooting of itself inside a particularly narrow, ethnocentric and exclusivist conception of national identity; and its constant attempts to expel symbolically one sector of society after another from the imaginary community of the nation-these are as central to Thatcherism's hegemonic project as the privatization programme or the assault on local democracy...     

Is the flavin-deficient red blood cell common in Maremma, Italy, an important defense against malaria in this area?

There is a high prevalence of a familial flavin-deficient red blood cell in Ferrara province in the Po delta in northern Italy, believed to have been selected for by malaria which was endemic from the 12th century. In the present study, activities of FAD-dependent red-cell glutathione reductase (EGR) in the Grosseto area of Maremma on the west coast of Italy where malaria was endemic from 300 B.C. are compared both with activities in the Ferrara area and with activities where there was no history of endemic malaria--in the Florence area and in London in people of Anglo-Saxon origin. EGR activities were similar in Grosseto and Ferrara and were significantly lower than in Florence and London. As previously found in Ferrara, low EGR activity in Grosseto was shown to be unrelated to low dietary riboflavin intake. These findings in Grosseto, suggesting selection by malaria, are particularly interesting because, unlike the situation in Ferrara and most other malarial areas, the prevalence of thalassemia and glucose-6-phosphate dehydrogenase deficiency is very low, and they do not appear to have been selected for in Maremma. It is possible that a flavin-deficient red cell, known to inhibit growth of the malaria parasite, was an important protecting factor in the population of this area over the centuries.     

Agglutination, Adherence, and Root Colonization by Fluorescent Pseudomonads

Two fractions of agglutination activity towards fluorescent pseudomonads were detected in root washes of potato, tomato, wheat, and bean. High-molecular-mass (>10⁶ Da) components in crude root washes agglutinated only particular saprophytic, fluorescent Pseudomonas isolates. Ion-exchange treatment of the crude root washes resulted in preparations of lower-molecular-mass (10⁵ to 10⁶ Da) fractions which agglutinated almost all Pseudomonas isolates examined. Also, components able to suppress agglutination reactions of pseudomonads with the lower-molecular-mass root components were detected in crude root washes of all crops studied. Pseudomonas isolates were differentially agglutinated by both types of root components. The involvement of these two types of root components in short-term adherence and in colonization was studied in potato, tomato, and grass, using Pseudomonas isolates from these crops. Short-term adherence of isolates to roots was independent of their agglutination with either type of root components. With agglutination-negative mutants, the high-molecular-mass components seemed to be involved in adherence of Pseudomonas putida Corvallis to roots of all crops studied. Short-term adherence to roots of four Pseudomonas isolates could be influenced by addition of both crude and ion-exchange-treated root washes, depending on their agglutination phenotype with these root wash preparations. Potato root colonization by 10 different isolates from this crop, over a period of 7 days, was not correlated with their agglutination phenotype. Agg^- mutants of P. putida Corvallis were not impaired in root colonization. It is concluded that the root agglutinins studied can be involved in short-term adherence of pseudomonads to roots but do not play a decisive role in their root colonization.