Focus: Addiction: Relapse Prevention and the Five Rules of Recovery

There are four main ideas in relapse prevention. First, relapse is a gradual process with distinct stages. The goal of treatment is to help individuals recognize the early stages, in which the chances of success are greatest. Second, recovery is a process of personal growth with developmental milestones. Each stage of recovery has its own risks of relapse. Third, the main tools of relapse prevention are cognitive therapy and mind-body relaxation, which are used to develop healthy coping skills. Fourth, most relapses can be explained in terms of a few basic rules. Educating clients in these rules can help them focus on what is important: 1) change your life (recovery involves creating a new life where it is easier to not use); 2) be completely honest; 3) ask for help; 4) practice self-care; and 5) don’t bend the rules.     

A particulate DNA polymerase activity in adult rat brain

A particulate fraction of adult rat brain (sucrose buoyant density 1.24 gm/ml) catalyzed the incorporation of [³H]dTTP into an acid-insoluble product in an endogenously templated reaction sensitive to ribonuclease pretreatment. Upon fractionation, this activity was identified in the cerebellum, pons, frontal lobes and base. The DNA polymerase present in these brain fractions exhibited a strong preference for the synthetic template dT_12–18·poly rA rather than dT_12–18·poly dA; dT₁₀ was completely inactive. Purification and equilibrium Cs₂SO₄ gradient centrifugation of the [³H]DNA product-endogenous template complex suggested that RNA was serving as primer for endogenous DNA synthesis.     

Rapid separation of the chloroplast and cytoplasmic fractions from intact leaf protoplasts

Intact protoplasts are ruptured by rapid centrifugation through a narrow-aperture nylon mesh and the intact chloroplasts are then separated from the cytoplasm by sedimentation through a layer of silicone oil below the mesh. Within 6 to 8 s of starting the centrifuge, 90% of the chloroplasts are separated into the pellet fraction which contains only 10 to 15% contamination by mitochondria and peroxisomes and less than 5% contamination by soluble cytoplasm as judged by the distribution of marker enzymes. This technique should allow determination of the distribution of metabolites between the chloroplast and cytoplasmic compartments of intact protoplasts.     

Competition for sulphur in a grass-clover association

Summary A 3 × 3 factorial experiment with nitrogen and sulphur fertilizers was carried out on a grass-clover association in an area where there is little if any cyclic return of sulphur. In the absence of sulphur, grass took up 98 per cent of the total uptake of sulphur, and nitrogen fixation by associated clover was negligible. In the absence of fertilizer nitrogen, dressings of sulphur as gypsum stimulated clover growth; at a low rate of application of sulphur, nitrogen fertilizer increased grass growth and clover was suppressed. This suppression was largely overcome with a higher dressing of sulphur. Sulphur therefore must be added to the group of elements (phosphorus, nitrogen and potassium) for which grass may compete intensely when grown with clover and when nitrogen fertilizers are applied to a grass-clover association adequate supplies of sulphur must be assured in order to minimise suppression of clover. Sulphate of ammonia may stimulate clover growth under these conditions. Solubility of gypsum was low in a dry season and residual effects were pronounced.     

The Escherichia coli dnaW mutation is an allele of the adk gene

Summary A dnaW mutant, isolated on the basis of inability to effect conjugal DNA transfer at high temperature, has been shown by complementation and enzyme assay to be defective in the adk (adenylate kinase; EC 2.7.4.3) locus. The adk mutant, known to have reduced ATP concentration at the nonpermissive temperature (Cousin and Belaich 1966), was used to demonstrate a donor energy requirement for stable aggregate formation and for chromosome transfer in conjugation.     

CHARACTER DISCRIMINATORY POWER,CHARACTER-SET CONGRUENCE,AND THE CLASSIFICATION OF INDIVIDUALS FROM HYBRID ZONES: AN EXAMPLE USING STONE CRABS (MENIPPE)

Many investigators categorize individuals from hybrid zones to facilitate comparisons among genotypic classes (e.g., parental, F₁, backcross) for comparative studies in which components of fitness or geographic variation are being analyzed. Frequently, multiple character sets representing genetically independent traits are used to classify these individuals and various methodologies are employed to combine the classifications obtained from the different character sets. We adapted the principles of total evidence and taxonomic congruence (two formalized approaches used by systematists in formulating phylogenetic hypotheses) to address the problem of discriminating hybridizing species and classifying individuals from hybrid zones. As our model, we used two morphological (coloration and morphometric) and two molecular (allozyme and mitochondrial DNA restriction-fragment-length polymorphism) character sets that differentiate two stone crab species (Menippe adina and M. mercenaria). Using principal-components analysis, we determined that combining character sets and eliminating characters or character sets that did not have large eigenvector coefficients for the principal component that best separated the two species yielded the highest level of discrimination between species and allowed us to classify a broad range of morpho-genotypes as hybrids. For the stone crabs, three diagnostic allozyme loci and five diagnostic coloration characters best separated the species. The two character sets were not completely congruent, but they agreed in their classification of 50% of the individuals from the hybrid zone and rarely strongly disagreed in their classifications. Classification discrepancies between the two character sets probably represent variation between traits in interspecific gene flow rather than intraspecific, ecologically mediated variation. Our results support the assertions of previous investigators who espoused the benefits associated with using multiple character sets to classify individuals from hybrid zones and demonstrate that, if character sets are reasonably congruent and numerically balanced, combining diagnostic characters from multiple character sets (a total-evidence approach) can enhance discriminatory power between species and facilitate the assignment of hybrid-zone individuals to genotypic classes. On the contrary, classifying hybrid-zone individuals using character sets separately (a taxonomic-congruence approach) provides the opportunity to compare levels of introgression between species and to assess reasons for discordance among the data sets.