Mobility of endogenous ecotropic murine leukemia viral genomes within mouse chromosomal DNA and integration of a mink cell focus-forming virus-type recombinant provirus in the germ line

Characterization of endogenous ecotropic Akv proviruses in DNA of low and high leukemic mouse strains revealed the presence of one to six copies of the Akv genome per haploid genome equivalent integrated in the germ line. Low leukemic strains analyzed so far contained only one complete copy of the Akv proviral DNA. The site of integration varied among strains, although genetically related strains often carried the Akv proviral gene in the same chromosomal site. The different substrains of the AKR mouse displayed the presence of variable numbers (two to six) of Akv genomes. In all substrains one Akv genome was present in an identical chromosomal site; this locus probably comprised the progenitor genome. Closely related substrains had several Akv proviral DNAs integrated in common sites. The accumulation of Akv genomes in the germ line of the AKR/FuRdA strain is likely the result of independent integration events, since backcross studies with the Akv-negative 129 strain showed random segregation of all six proviral loci. The AKR/Cnb strain carried a recombinant provirus in the germ line. This provirus resembled in structure the AKR mink cell focus-forming viruses, which are generated by somatic recombination during leukemogenesis. Therefore, the germ-line amplification of Akv proviral DNAs occurs most likely through infection of embryonic cells by circulating virus.     

Lipoxygenase activity in apples in relation to storage and physiological disorders

Different methods for the preparation of active lipoxygenase (LOX) extracts from apples were compared. Highest activities were obtained using a 0.25 M phosphate buffer (pH 7) containing 1% Triton X-100 and 10^?2 M metabisulphite as extraction solvent. LOX activity during storage was investigated in the core, flesh, and peel. Activity was always highest in the core and peel. On storage, activity was increased in each part of the fruit but especially in the core and peel. Increase in LOX preceded the browning of the core. LOX may be responsible for the browning and may be concerned in the induction of superficial scald.     

Use of trypsin for rapid and efficient purification of murine sarcoma and leukemia virus

A method is described for purification of MSV-MuLV from culture supernatant of chronically infected 78A₁ rat embryo cell line. This method involves direct polyethylene glycol-NaCl precipitation of the low speed supernatant of culture fluid followed by digestion of the pellet with trypsin. This procedure efficiently disrupts large aggregates which normally entrap most of the virus. Highly purified virus can be obtained in very good yield by a combination of sedimentation velocity and isopycnic centrifugation : yields up to 100 A₂₈₀ units (17 mg of protein) of purified virus per liter of culture fluid can be observed. This procedure appears well suited for large scale isolation of virion associated enzymatic activities.     

Androgen on the estrogen receptor I — Binding and in vivo nuclear translocation

In the immature rat uterus, high concentrations of androgens competed specifically with estradiol on the estrogen receptor (RE). This competition was stereospecific for C₁₉ steroids bearing a 17β and/or 3 hydroxyl group. Very low affinity ligands, such as testosterone, could not compete with estradiol at equilibrium but decreased the association rate of estradiol on its receptor. High doses (> 0.4mg) of 5 α aihydrotestosterone provoked $\text{in vivo}$ as $\text{in vitro}$ the nuclear translocation of RE. The nuclear receptor thus formed displayed the same 5.2 S sedimentation constant as that induced by estradiol. We conclude that the weak affinity binding of androgens to the estrogen receptor is sufficient to induce its nuclear translocation $\text{in vivo}$ provided androgen concentration is high enough in uterus to occupy the estradiol binding site. Conversely, progesterone which does not bind RE could not provoke its nuclear translocation.     

Ostracodes devoniens du Sud-Ouest de l'ile Ellesmere (archipel arctique-canadien): Première partie

On south western Ellesmere Island, near the head of Eids Fiord, the Eids Formation and thelower member of the Blue Fiord Formation, to which an Emsian age may be assigned on conodont evidence, yield large and diversified ostracode faunas. Over ninety species and subspecies are distinguished, including the fauna described by I. P. Tolmachoff (1926) from the «Series Db in the Goose Fiord area near the southern shore of the island. The present report, the first one of a series of four, deals with the families Beyrichiidae, Hollinidae, Pribylitidae, Rozhdestvenskayitidae and Youngiellidae. Twenty eight taxa, among them three new genera, eleven new species and one new subspecies, are described.     

Fractionation of subcellular membranes of the secretory pathway from the peroxidase-producing white-rot fungus Phanerochaete chrysosporium

Abstract Mycelia from the basidiomycete Phanerochaete chrysosporium , producing lignin and manganese peroxidases, were homogenized and fractionated on a sucrose gradient. The main subcellular fungal membrane fractions were successfully separated. Lipid composition analyses of the isolated membranes as well as associated marker enzymes distribution gave evidence to similarities with membranes originating from plants. Lignin and manganese peroxidases were investigated by immunodetection in subcellular fractions. Our results show that lignin and manganese peroxidases are mainly associated with Golgi apparatus vesicles and, to a lesser extent, with endoplasmic reticulum and light density vesicles, but not with plasma membranes.     

Information Structure Influences Depth of Syntactic Processing: Event-Related Potential Evidence for the Chomsky Illusion

Information structure facilitates communication between interlocutors by highlighting relevant information. It has previously been shown that information structure modulates the depth of semantic processing. Here we used event-related potentials to investigate whether information structure can modulate the depth of syntactic processing. In question-answer pairs, subtle (number agreement) or salient (phrase structure) syntactic violations were placed either in focus or out of focus through information structure marking. P600 effects to these violations reflect the depth of syntactic processing. For subtle violations, a P600 effect was observed in the focus condition, but not in the non-focus condition. For salient violations, comparable P600 effects were found in both conditions. These results indicate that information structure can modulate the depth of syntactic processing, but that this effect depends on the salience of the information. When subtle violations are not in focus, they are processed less elaborately. We label this phenomenon the Chomsky illusion.