Chromomycin, mithramycin, and olivomycin binding sites on heterogeneous deoxyribonucleic acid. Footprinting with (methidiumpropyl-EDTA)iron(II)

The DNA binding sites for the antitumor, antiviral, antibiotics chromomycin, mithramycin, and olivomycin on 70 base pairs of heterogeneous DNA have been determined by using the (methidiumpropyl-EDTA)iron(II) [MPE x Fe(II)] DNA cleavage inhibition pattern technique. Two DNA restriction fragments 117 and 168 base pairs in length containing the lactose operon promoter-operator region were prepared with complementary strands labeled with 32P at the 3' end. MPE x Fe(II) was allowed to partially cleave the restriction fragment preequilibrated with either chromomycin, mithramycin, or olivomycin in the presence of Mg2+. The preferred binding sites for chromomycin, mithramycin, and olivomycin in the presence of Mg2+ appear to be a minimum of 3 base pairs in size containing at least 2 contiguous dG x dC base pairs. Many binding sites are similar for the three antibiotics; chromomycin and olivomycin binding sites are nearly identical. The number of sites protected from MPE x Fe(II) cleavage increases as the concentration of drug is raised. For chromomycin/Mg2+, the preferred sites on the 70 base pairs of DNA examined are (in decreasing affinity) 3'-GGG, CGA greater than CCG, GCC greater than CGA, CCT greater than CTG-5'. The sequence 3'-CGA-5' has different affinities, indicating the importance of either flanking sequences or a nearly bound drug.     

The role of ``conservatism' in herring migrations

Herring (Clupea harengus) migrationstend to remain constant over periods of severalyears or even decades, despite environmentalvariation. When a migration pattern is changed,apparently in response to an environmentalstimulus, the change in migratory behaviorsometimes lasts longer than the environmentalstimulus itself. This paper reviews evidencethat the response of herring to environmentalchange is restrained by conservatism. Herringapparently develop certain migratory habitsduring the early stage of adult life and tendto adhere to these habits for life, even whenthe environment changes. Two elements ofconservatism are distinguished: the formationof habits within one generation, and thetransfer of habits between generations. Anumber of case studies on North Sea herring andNorwegian spring spawning herring are reviewedin order to find evidence for habit formationand tradition in the migrations of thesepopulations. By eliminating the possibilitythat homing to spawning, wintering and feedinggrounds is due to innate behavior orenvironmental constraints, it is shown that thereturn of these fish to the same areas eachyear is most likely a form of learned behavior.In many cases, new year-classes adopt the samemigration pattern as their predecessors, whichis explained by the social transfer of habitsfrom old herring to young ones. A change ofmigration pattern is usually initiated by arecruiting year-class that lacks the ``guidance'of older herring at the time it has to startits first migration. This may be the effect ofa special environmental condition that affectsthe distribution of the recruiting age groupmore than that of the adult stock component, andthereby results in a separation of the twostock components. After the recruitingyear-class has adopted the new migration route,it tends to repeat it in subsequent years. Thenew migration thus becomes habitual. Subsequentgenerations may copy the migration and continuethis behavior even after the originalenvironmental cause has disappeared.     

Intra- and interspecific host discrimination in Asobara (Hymenoptera) larval endo-parasitoids of Drosophilidae: Comparison between closely related and less closely related species

Host discrimination studies were conducted with different species of Asobara, which are larval endo-parasitoids of Drosophilidae. Results indicated variable host discrimination which depended on the relatedness of the species. The closely related sibling species Asobara tabida (Nees) and A. rufescens (Foerster) were not only capable of intraspecific discrimination, but also avoided multiparasitism by discriminating between unparasitized host larvae and larvae previously parasitized by females of the other species. This ability to discriminate interspecifically does not seem functional as each species occupies its own microhabitat. As it was shown to be absent in less closely related Asobara species we concluded that interspecific discrimination by A. tabida and A. rufescens was due to their close relationship.     

Assay of DNA-RNA hybrids by S1 nuclease digestion and adsorption to DEAE-cellulose filters.

A fast and accurate assay procedure for DNA-RNA hybrids is described in which exhaustive digestion of unhybridized DNA with S1 nuclease is followed by binding of hybrids to filter discs of DEAE-cellulose. The digested DNA can be efficiently washed from the filters so that background levels of 0.1-0.2% of input tracer DNA can be achieved, in contrast to the much higher (approximately 1-5%) backgrounds obtained using TCA precipitation procedures. Short duplexes, as small as 36 nucleotides in length, which are inefficiently bound to hydroxyapatite, are quantitatively bound to the DEAE-cellulose filters.     

Preferential expression of cellular retinoic acid binding protein in a subpopulation of neural cells in the developing mouse embryo

The cellular retinoic acid binding protein is thought to be involved in the retinoic-acid-mediated signal transduction pathway. We have isolated the mouse cellular retinoic acid binding protein cDNA from an embryonal-carcinoma-derived cell line by using differential cDNA cloning strategies. In situ hybridization on sections of mouse embryos of various developmental stages indicated that the cellular retinoic acid binding protein gene, which we localized on mouse chromosome 9, is preferentially expressed in a subpopulation of neurectodermal cells. This restricted expression pattern suggests an important role for cellular retinoic acid binding protein in murine neurogenesis.     

X-linked recessively inherited non-specific mental retardation. Report of a large family.

A large kindred is described in which 22 males and 3 females show non-specific mental retardation with impaired speech. An X-linked recessive is the most likely mode of inheritance of this condition. Similar families have been described in the literature, characteristic physical abnormalities are absent and performance I.Q. tends to be higher than verbal I.Q. This possible heterogenous condition may be a major individual cause of mental deficiency in males, and may account for the excess of male retardates in the population.