Regulation of μ-Opioid Receptor mRNA in Rat Globus Pallidus: Effects of Enkephalin Increases Induced by Short- and Long-Term Haloperidol Administration

Abstract: The mRNA encoding μ-opioid receptors is expressed in neurons of the globus pallidus, a region of the basal ganglia that receives a dense enkephalinergic innervation from the striatum. The regulation of the mRNAs encoding the opioid peptide enkephalin in the striatum and the μ-opioid receptor in the globus pallidus was examined with in situ hybridization histochemistry following short- or long-term haloperidol treatments, which alter striatal enkephalin mRNA levels. Animals were administered haloperidol daily for 3 or 7 days (1 mg/kg, s.c.) or continuously for 8 months (1 mg/kg, depot followed by oral). Enkephalin and μ-opioid receptor mRNA levels were unchanged after 3 days of haloperidol treatment. In contrast, the enkephalin mRNA level was increased in the striatum, and μ-opioid receptor mRNA levels were markedly decreased in the globus pallidus after 7 days of haloperidol administration. Similar effects were observed in rats treated with haloperidol for 8 months. The results provide the first evidence of regulation of μ-opioid receptor mRNA in vivo.     

Chromosome painting of Amigo wheat

Chromosome painting using multicolor fluorescence in situ hybridization showed that, in addition to the T1AL·1RS translocation derived from rye, a segment from chromosome 3Ae#1 of Agropyron elongatum (2n=10x =70), is present in Amigo wheat. The Agropyron chromosome segment is located on the satellite of chromosome 1B and the translocation chromosome is designated as T1BL·1BS-3Ae#1L. T1BL·1BS-3Ae#1L was inherited from Teewon wheat and carries resistance genes to stem rust (Sr24) and leaf rust (Lr24). The Agropyron chromosome segments in different Sr24/Lr24 carrier wheat lines, including Agent, TAP 48, TAP 67, Teewon, and Amigo, showed a diagnostic C-band, and were derived from the same chromosome, 3Ae#1.     

Micropropagation of Frazinus angustifolia from mature and juvenile plant material

Micropropagation of Fraxinus angustifolia Vahl has been successfully achieved both from mature and juvenile plant material using shoot tip and nodal explants. Several basal media supplemented with benzyladenine (BA) and indolebutyric acid (IBA) were tested for shoot proliferation. The most new explants per mature explant (5.3) was obtained on DKW medium plus 4.4 M BA+0.98 M IBA. The most new explants per juvenile explant (5.6) was produced on QL medium plus 8.9 M BA+0.49 M IBA. Rooting was achieved on WPM supplemented with 0.98–4.9 M IBA. Rooted plantlets were transferred to soil and acclimatized with 85% survival.Abbreviations BA benzyladenine - IBA indolebutyric acid - NAA 1-naphthaleneacetic acid     

A genetic approach to the identification of functional amino acids in protein p6 of Bacillus subtilis phage ?29

Protein p6 of the Bacillus subtilis phage ø29 is essential for in vivo viral DNA replication. This protein activates the initiation of ø29 DNA replication in vitro by forming a multimeric nucleoprotein complex at the replication origins. The N-terminal region of protein p6 is involved in DNA binding, as shown by in vitro studies with p6 proteins altered by deletions or missense mutations. We report on the development of an in vivo functional assay for protein p6. This assay is based on the ability of protein p6-producing B. subtilis non-suppressor (su ^–) cells to support growth of a ø29 sus6 mutant phage. We have used this trans-complementation assay to investigate the effect on in vivo viral DNA synthesis of missense mutations introduced into the protein p6 N-terminal region. The alteration of lysine to alanine at position 2 resulted in a partially functional protein, whereas the replacement of arginine by alanine at position 6 gave rise to an inactive protein. These results indicate that arginine at position 6 is critical for the in vivo activity of protein p6. Our complementation system provides a useful genetic approach for the identification of functionally important amino acids in protein p6.     

Involvement of putrescine in the inductive rooting phase of poplar shoots raised in vitro

Micropropagated poplar shoots rooted 100% on a rooting medium (A) containing NAA, but they did not root in the absence of auxin (NA). Putrescine, but not spermidine and spermine, promoted rooting up to 42% when added to the NA medium. Cyclohexylamine (CHA), an inhibitor of spermine synthase, also promoted (up to 36%) rooting in the absence of auxin. The inhibitors of polyamine biosynthesis DFMA (α-difluoromethylarginine) and DFMO (α-difluoromethylomithine), aminoguanidine (AG) and methylglyoxal-bis-guanylhydrazone (MGBG), inhibited rooting when applied in the presence of auxin and had no effect in its absence.
The rooting inductive phase (in the presence of auxin) was determined by periodical transfer of shoots from A to NA medium, and by changes in peroxidase activity, to be 7 h. Putrescine (not spermidine and spermine) accumulated to a maximum during the inductive phase. Both putrescine and CHA promoted rooting on NA medium when applied during the first 7 h. In contrast DFMA and AG inhibited rooting during this period. The results point to the involvement of putrescine and its Δ¹-pyrroline pathway, in the inductive phase of rooting in poplar shoots.     

Reversible cytoplasmic rearrangements precede wall apposition,hypersensitive cell death and defense-related gene activation in potato/Phytophthora infestans interactions

We used video microscopy techniques as a tool for live examination of the dynamic aspects of plant/fungus interactions. Early, dynamic responses of epidermal midrib cells of leaves from a potato cultivar (Solanum tuberosum L. cv. Datura) carrying resistance gene R1 to Phytophthora infestans (race 1: compatible interaction, race 4: incompatible interaction) were monitored. Similar responses were observed in both types of interaction, ranging from no visible reaction of invaded plant cells to hypersensitive cell death. The overall defense response of each individual cell exhibited a highly dynamic behavior that appeared to be tightly coordinated with the growth of the fungus. Initial localized reactions, including major rearrangements within the cytoplasm, occurred directly at the fungal penetration site, where rapid apposition of autofluorescent material and callose took place. If fungal invasion stopped at this stage, the host cell restored its normal cytoplasmic activity and survived. Hypersensitive cell death occurred only when fungal growth had proceeded to the formation of a clearly identifiable haustorium. In such cases, cytoplasm and nucleus conglomerated around the intracellular fungal structure, followed by a sudden collapse of the whole conglomerate and an instantaneous collapse of the fungal haustorium. Only small quantitative differences between the compatible and incompatible interactions of the two fungal races were observed for these early responses of epidermal cells. In the incompatible interaction, a slightly larger number of epidermal cells responded to fungal attack. More pronounced quantitative differences between compatible and incompatible interactions occurred upon fungal invasion of the mesophyll. These differences in the number of responding cells were not reflected at the level of gene expression: the spatial and temporal activation patterns of two defense-related genes, encoding phenylalanine ammonia-lyase and pathogenesis-related protein 1, were similar in both types of interaction.Dedicated to Professor Peter Sitte, Freiburg, Germany, on the occasion of his 65th birthday     

Abscisic acid biosynthesis during corn embryo development

In this study we examined the biosynthesis of abscisic acid (ABA) by developing corn (Zea mays L.) embryos. Three comparisons were made: ABA biosynthesis in embryos isolated from kernels grown in vitro with those grown in the field; the developmental profile of ABA content with that of biosynthesis; and ABA biosynthesis in corn embryos lacking carotenoid precursors with ABA biosynthesis in normal embryos. Embryos were harvested at various times during seed development and divided into two groups. Endogenous levels of ABA were measured in one group of embryos and ABA biosynthetic capacity was measured in the other group. The ABA biosynthetic capacity was measured with and without tetcyclacis (an inhibitor of ABA degradation) in embryos from both field-grown and in-vitro-grown corn kernels. Reduced-carotenoid (either fluridone-treated or genetically viviparous) embryos were also included in the study. Corn kernels developing under field and in-vitro conditions differed from each other in their responses to tetcyclacis and in their profiles of ABA biosynthesis during development. Therefore, in-vitro kernel culture may not be an appropriate substitute for field conditions for studies of embryo development. The developmental profiles of endogenous ABA content differed from those of ABA biosynthesis in isolated embryos of both in-vitro-and field-grown kernels. This indicated that ABA levels in the developing embryos were determined by import from the maternal tissues available to the embryos rather than by in-situ biosynthesis. In embryos with reduced levels of carotenoids, either fluridone-treated or genetically viviparous embryos, ABA biosynthesis was low or nonexistent. This result is expected for the presence of an indirect pathway of ABA biosynthesis and in the absence of ABA precursors.Abbreviations ABA abscisic acid - DAP days after pollination