Molecular cloning of lin-29, a heterochronic gene required for the differentiation of hypodermal cells and the cessation of molting in C.elegans.

The lin-29 gene product of C.elegans activates a temporal developmental switch for hypodermal cells. Loss-of-function lin-29 mutations result in worms that fail to execute a stage-specific pattern of hypodermal differentiation that includes exist from the cell cycle, repression of larval cuticle genes, activation of adult cuticle genes, and the cessation of molting. Combined genetic and physical mapping of restriction fragment length polymorphisms (RFLPs) was used to identify the lin-29 locus. A probe from the insertion site of a Tc1 (maP1), closely linked and to the left of lin-29 on the genetic map, was used to identify a large set of overlapping cosmid, lambda and yeast artificial chromosome (YAC) clones assembled as part of the C.elegans physical mapping project. Radiolabeled DNA from one YAC clone identified two distinct allele-specific alterations that cosegregated with the lin-29 mutant phenotype in lin-29 intragenic recombinants. lin-29 sequences were severely under-represented in all cosmid and lambda libraries tested, but were readily cloned in a YAC vector, suggesting that the lin-29 region contains sequences incompatible with standard prokaryotic cloning techniques.     

DNA haplotypes and frameworks associated with the beta-globin gene in the Kachari population of Assam (India)

DNA haplotypes and frameworks associated with the beta-globin gene were determined in a Tibeto-Burman group, the Kachari, from Upper Assam, India, using restriction analysis at eight restriction sites. Of the total of 59 subjects, 26 were homozygous for HBB*A and 33 homozygous for HBB*E. Complete haplotype determination in 33 subjects revealed a conspicuous difference in haplotype distribution between HBB*A- and HBB*E-bearing chromosomes. The Southeast Asian HBB*E-associated haplotype -+- +- (27-2 in the present terminology) predominated on HBB*E chromosomes. The previously established beta-globin-associated frameworks 1, 2 and 3 were evenly distributed among the HBB*A chromosomes, whereas all HBB*E chromosomes had framework 2. These findings favor a common origin of the HBB*E gene in Southeast Asia and Assam.     

Alpha-thalassemia in northern Thailand. Frequency of deletional types characterized at the DNA level

The frequency of alpha-thalassemias in northern Thailand was estimated using DNA techniques. Among 106 healthy adult Thais from the Chiangmai area, 28 were shown to carry alpha-globin gene anomalies. There were 19 heterozygotes and 1 homozygote for alpha-thalassemia-2. One of the alpha-thalassemia-2 deletions was of the -alpha 4.2 type and the remaining 20 of the -alpha 3.7 type (subtype I). Deletions of both alpha-globin genes on one chromosome (alpha-thalassemia-1) of the Southeast Asian type were observed in 5 cases, and 3 alpha-globin gene triplications were identified. Compared with a previous report on alpha-thalassemia in northern Thailand which was based on the determination of hemoglobin Bart's in cord blood, the present DNA study reveals a similar frequency of alpha-thalassemia-2 but a considerably lower frequency of alpha-thalassemia-1.     

Taurine Levels in Discrete Brain Nuclei of Rats

Concentrations of taurine have been measured in 44 microdissected rat brain nuclei or areas. Taurine is ubiquitously present and distributed unevenly in the rat brain: the ratio of the highest (pyriform cortex) to lowest (midbrain reticular formation) concentrations is 4.7:1. High taurine levels were found in cerebral cortical areas, caudate-putamen, cerebellum, median eminence, and supraoptic nucleus. Acute pain stress reduced taurine levels in the hypothalamus and the lower brainstem nuclei but not in cortical areas. Increased locomotor and behavioral activities following a high dose of amphetamine elevated taurine concentrations significantly in the substantia nigra and locus ceruleus.     

Polarizability of the ionic cloud around a charged membrane sheet

The polarizability of the ionic cloud around a charged membrane sheet parallel to the surface is calculated. The membrane is modeled as an infinitely thin and long strip of width 2d'. The Poisson-Boltzmann equation is solved with an external electric field as a perturbation. The polarizability is given in closed integral form, with numerical results. At higher salt concentration the polarizability varies approximately as kappa(-3), where kappa is the Debye-Hückel constant. The given theoretical result can account for the a.c. electrodichroism of purple membrane suspensions.     

On the ancestral form of true organ of fructification in the saprophytic stage of the dermatophytes of the faviform group: Favomicrosporon pinettii,N.SP. and its perfect form: Anixiopsis stercoraria (hansen) hansen, 1897

Summary The discovery of the hidden, built-in macroconidia in the four members of the Faviform Group of the dermatophytes, i.e.,Achorion schoenleinii, Trichophyton violaceum, Trichophyton verrucosum andMicrosporon ferrugineum, is described.To bring the hidden, built-in macroconidia to full fructification, i.e., to force the production of imperfect and perfect organs of fructification (macroconidia, cleistothecia), two entirely different techniques have been used: 1) the hair-soil method, 2) the yeast extract method.The two techniques, entirely independent from each other, yielded the same result: the ancestral form of the four members of the Faviform Group of dermatophytes. The imperfect form is described asFavomicrosporon pinettii,Benedek, 1965, sp. nov. The perfect form isAnixiopsis stercoraria (Hansen)Hansen, 1897.The ancestral form was found not only in and cultured from the strains of those dermatophytes derived from pathological material, but it was also recovered from its saprophytic habitat, from the soil (potting soil).

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Zusammenfassung Die Entdeckung der verborgenen, eingebauten Makrokonidien in den vier Representanten der Faviformen Gruppe der Dermatophyten, i.e.Achorion schoenleinii, T. violaceum, T. verrucosum, Microsporon ferrugineum, wird beschrieben.Um die verborgenen, eingebauten Makrokonidien zur vollen Fruchtbildung zu bringen, i.e. um die Produktion der imperfekten und perfekten Organe der Fruktifikation (Makrokonidien, Kleistothecien) zu erzwingen, sind zwei völlig verschiedene Methoden benutzt worden: 1) die Haar-Erde-Methode, und 2) die Hefeextrakt-Methode.Beide Methoden, völlig unabhängig von einander, haben zu demselben Ergebnis geführt, i.e. zur Entdeckung der Urform von den vier Representanten der Faviformen Gruppe der Dermatophyten. Die imperfekte Form wird alsFavomicrosporon pinettii,Benedek, 1965, sp. nov. beschrieben. Die perfekte Form istAnixiopsis stercoraria (Hansen)Hansen, 1897.Die ancestrale Form wurde nicht nur aus den Stämmen jener Dermatophyten gezüchtet, die aus pathologischen Produkten gewonnen worden sind, sondern auch aus dem natürlichen Habitat: von der Erde (potting soil).

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Résumé La découverte des macroconidies occultes et encastrées dans les quatre membres du Groupe Faviforme des dermatophytes:Achorion schoenleinii, Trichophyton violaceum, Trichophyton verrucosum etMicrosporon ferrugineum, est décrite.Pour forcer les macroconidies occultes et encastrées à la fructification complète, i.e. de produire des organs de reproduction imparfaits et parfaits, macroconidies et cleistothecia, on a fait l'usage de deux techniques complètement différentes: 1) des cheveux sur sol et 2) de l'extraction de levure.Toutes les deux méthodes, complètement indépendantes l'une de l'autre, ont produit le même résultat: la forme ancestrale des quatre membres de la Groupe Faviforme des dermatophytes. La forme imparfaite est décrite commeFavomicrosporon pinettii,Benedek, 1965, sp. nov. et la forme parfaite commeAnixiopsis stercoraria (Hansen)Hansen, 1897.La forme ancestrale a été trouvée non seulement dans les souches des dermatophytes indiquées et en cultivées, provenantes des produits pathologiques, mais aussi du sol, du terrain jardinier.

     

Modulation of Rat Brain Cortical α-Adrenoceptors by Treatment with Hydrocortisone for 10 Days

The role of glucocorticoids in the modulation of central alpha 2-receptor mechanisms was investigated by in vitro receptor binding studies. [3H]Clonidine and [3H]idazoxan were used as radioligands. The alpha 2-receptor subtypes and guanine nucleotide sensitivity were studied in homologue and heterologue displacement experiments following hydrocortisone treatment (25 mg/kg s.c.) for 10 days. High and low agonist affinity states of the alpha 2-receptor could be identified in 3H-antagonist-agonist and 3H-agonist-antagonist displacement experiments, which may correspond to different regulatory protein-nucleotide associated forms of the receptor. In the presence of 10 microM GTP, the high-affinity binding was depressed. Following hydrocortisone treatment, there was no detectable change either in the affinity or the binding site concentration of clonidine in homologue displacement ("cold saturation") experiments. The affinity of idazoxan, however, was depressed. The effect of GTP was similar to the controls in this experimental arrangement. In contrast, in heterologue binding studies the high-affinity binding site was not demonstrable and the amount of low-affinity binding increased following the hydrocortisone treatment. The high-affinity site reappeared in the presence of GTP. The change in GTP sensitivity suggests that the nucleotide regulatory system may be involved in the action of adrenal steroids on central alpha 2-receptoral mechanisms.     

Inheritance and expression of a transgene insert in an aneuploid tobacco line

A T-DNA locus comprising nptII, uidA and nos genes — all under the control of the nos promoter (this locus was designated K because it encodes resistance to Kanamycin) - was found to be inherited erratically in a transgenic tobacco line. This anomalous behavior was partially explained following a karyotype analysis of plants representing several generations: these plants were aneuploids, presumably for the K-containing chromosome. During four generations of sexual propagation, transgenic plants that were either trisomic or tetrasomic for the K-containing chromosome (i.e. 2n=49 or 2n=50, respectively) were obtained. The trisomic plants (2n=48+1) were virtually indistinguishable phenotypically from normal euploids (2n=4x=48), whereas the tetrasomic plants (2n=48+2) were smaller, had somewhat misshapen leaves and exhibited reduced fertility. Although the amount of NPTH protein in different trisomic (K--, KK-, KKK) and tetrasomic (KK--, KKK-) plants was generally consistent with a K dosage effect, the genetic behavior of each trisomic — with respect to segregation of Kan^R and marker gene activity in progeny — was unique and not completely explicable by invoking aneuploidy. Specifically, unexpected gains or losses of K could occur, suggesting the formation of double reductional gametes and/or frequent gene conversion at this locus. The susceptibility of K locus marker genes to trans-inactivation in the trisomic and tetrasomic lines was tested by crossing in partially homologous silencing loci. In all transgenotypes tested, the three K marker genes were sensitive to trans-silencing, which was accompanied by methylation in all copies of the nos promoter. In addition to this directed inactivation/methylation, the K locus could also undergo infrequent, spontaneous partial methylation, which produced stable epialleles. In most plants, however, the multiple copies of the nos promoter at this locus remained unmethylated and active through four generations in all transgenotypes examined. The significance of these results for irregular inheritance patterns, aneuploid syndromes and homology-dependent gene silencing is discussed.     

Cross-linking myosin subfragment 1 Cys-697 and Cys-707 modifies ATP and actin binding site interactions.

Skeletal muscle myosin is an enzyme that interacts allosterically with MgATP and actin to transduce the chemical energy from ATP hydrolysis into work. By modifying myosin structure, one can change this allosteric interaction and gain insight into its mechanism. Chemical cross-linking with N,N'-p-phenylenedimaleimide (pPDM) of Cys-697 to Cys-707 of the myosin-ADP complex eliminates activity and produces a species that resembles myosin with ATP bound (Burke et al., 1976). Nucleotide-free pPDM-modified myosin subfragment 1 (S1) was prepared, and its structural and allosteric properties were investigated by comparing the nucleotide and actin interactions of S1 to those of pPDM-S1. The structural properties of the nucleotide-free pPDM-S1 are different from those of S1 in several respects. pPDM-S1 intrinsic tryptophan fluorescence intensity is reduced 28%, indicating a large increase of an internal quenching reaction (the fluorescence intensity of the related vanadate complex of S1, S1-MgADP-Vi, is reduced by a similar degree). Tryptophan fluorescence anisotropy increases from 0.168 for S1 to 0.192 for pPDM-S1, indicating that the unquenched tryptophan population in pPDM-S1 has reduced local freedom of motion. The actin affinity of pPDM-S1 is over 6,000-fold lower than that of S1, and the absolute value of the product of the net effective electric charges at the acto-S1 interface is reduced from 8.1 esu2 for S1 to 1.6 esu2 for pPDM-S1. In spite of these changes, the structural response of pPDM-S1 to nucleotide and the allosteric communication between its ATP and actin sites remain intact.(ABSTRACT TRUNCATED AT 250 WORDS)