Genetic control of β-diketone and hydroxy-β-diketone synthesis in epicuticular waxes of barley

Summary Five eceriferum, (cer) mutants in barley which influence -diketone and hydroxy--diketone synthesis in spike and internode epicuticular waxes have been characterized. The mutation cer-u ⁶⁹ blocks the synthesis of hydroxy--diketones and leads to a compensatory increase in the amount of -diketones, indicating that -diketones are precursors of the hydroxy--diketones. Furthermore, highly lobed wax plates were observed for the first time on barley lemmas, in addition to the characteristic wax tubes. Both diketone classes are selectively and proportionally reduced in the spike wax of cer-i ¹⁶, which has shorter wax tubes. The three mutants cer-c ³⁶, -q ⁴², and -c,u ¹⁰⁸ synthesize neither diketone class and form no wax tubes. In contrast to the variable composition of most individual barley wax classes, only a single -diketone was identified, namely hentriacontan-14,16-dione.     

The use of combined xylazine and lignocaine epidural injection in ewes with vaginal or uterine prolapses

Two millilitres of solution calculated to contain 0.07 mg/kg xylazine and 0.5 mg/kg lignocaine injected at the sacrococcygeal epidural site provided caudal analgesia within 2 min in 61 sheep. This analgesic protocol eliminated forceful abdominal straining behavior following replacement of vaginal prolapse for at least 24 h in 48 of 52 ewes (92%) and in all 9 ewes with uterine prolapse. Moderate pelvic limb ataxia was observed in 25 sheep (41%) for up to 24 h after epidural injection. Sedation was noted in one ewe but no other systemic effects of xylazine injection, such as excessive salivation or ruminal distension, were observed. No long-term adverse reactions to xylazine injection were noted. The combined epidural injection regimen of xylazine and lignocaine is recommended as an adjunct for pain relief and control of abdominal straining following replacement of vaginal and uterine prolapse in ewes.     

Membrane raft actin deficiency and altered Ca2+-induced vesiculation in stomatin-deficient overhydrated hereditary stomatocytosis

In overhydrated hereditary stomatocytosis (OHSt), the membrane raft-associated stomatin is deficient from the erythrocyte membrane. We have investigated two aspects of raft structure and function in OHSt erythrocytes. First, we have studied the distribution of other membrane and cytoskeletal proteins in rafts by analysis of detergent-resistant membranes (DRMs). In normal erythrocytes, 29% of the actin was DRM-associated, whereas in two unrelated OHSt patients the DRM-associated actin was reduced to <10%. In addition, there was a reduction in the amount of the actin-associated protein tropomodulin in DRMs from these OHSt cells. When stomatin was expressed in Madin-Darby canine kidney cells, actin association with the membrane was increased. Second, we have studied Ca2+-dependent exovesiculation from the erythrocyte membrane. Using atomic force microscopy and proteomics analysis, exovesicles derived from OHSt cells were found to be increased in number and abnormal in size, and contained greatly increased amounts of the raft proteins flotillin-1 and -2 and the calcium binding proteins annexin VII, sorcin and copine 1, while the concentrations of stomatin and annexin V were diminished. Together these observations imply that the stomatin-actin association is important in maintaining the structure and in modulating the function of stomatin-containing membrane rafts in red cells.     

Purine nucleosides and nucleotides stimulate proliferation of a wide range of cell types

Summary Presumptive astrocytes isolated from 10-day white Leghorn chick embryos, Factor VIII-positive human brain capillary endothelial cells, meningeal fibroblasts from 10-day chick embryos, Swiss mouse 3T3 cells, and human astrocytoma cell lines, SKMG-1 and U373, were rendered quiescent when placed in culture medium that contained 0 or 0.2% serum for 48 h; their proliferation was markedly reduced and they incorporated [³H]thymidine at a low rate. [³H]Thymidine incorporation and cell proliferation were induced in all types of cells by addition of guanosine, GMP, GDP, GTP, and to a lesser extent, adenosine, AMP, ADP or ATP to the culture medium. The stimulation of proliferation by adenosine and guanosine was abolished by 1,3-dipropyl-7-methylxanthine (DPMX), an adenosine A₂ receptor antagonist, but not by 1,3,-dipropyl-8-(2-amino-4-chorophenyl)xanthine (PACPX), an A₁ antagonist. Stimulation of proliferation by the nucleotides was not abolished by either DPMX or PACPX. The P₂ receptor agonists,α,β-methyleneATP and 2-methylthioATP, also stimulated [³H]thymidine incorporation into the cells with peak activity at approximately 3.5 and 0.03 nM, respectively. These data imply that adenosine and guanosine stimulate proliferation of these cell types through activation of an adenosine A₂ receptor, and the stimulation of cell proliferation by the nucleotides may be due to the activation of purinergic P_2y receptors. As the primary cultures grew older their growth rate slowed. The capacity of the purine nucleosides and nucleotides to stimulate their growth diminished concomitantly. The 3T3 cells showed neither decreased growth with increased passages nor reduced response to the purines. In contrast, although the doubling time of the immortalized human astrocytoma cell lines SKMG-1 and U373 remained constant, the responsiveness to purinergic stimulation of the U373 cells decreased but that of the SKMG-1 did not. These data are compatible with a decrease in the number, or the ligand-binding affinity of the purinergic receptors, or a decreased coupling of purinergic receptors to intracellular mediators in primary cells aged in tissue culture.     

What effect does classroom separation have on twins' behavior, progress at school, and reading abilities?

We investigated the effects of classroom separation on twins' behavior, progress at school, and reading abilities. This investigation was part of a longitudinal study of a nationally-representative sample of twins (the E-risk Study) who were assessed at the start of school (age 5) and followed up (age 7). We examined three groups of twins: pairs who were in the same class at both ages; pairs who were in separate classes at both ages; and pairs who were in the same class at age 5, but separated by age 7. When compared to those not separated, those separated early had significantly more teacher-rated internalizing problems and those separated later showed more internalizing problems and lower reading scores. Monozygotic (MZ) twins showed more problems as a result of separation than dizygotic (DZ) twins. No group differences emerged for externalizing problems, ADHD or prosocial behaviors. The implications of the findings for parents and teachers of twins, and for school practices about separating twins, are discussed.     

Activation of the galanin receptor 2 (GalR2) protects the hippocampus from neuronal damage

Expression of the neuropeptide galanin is up-regulated in many brain regions following nerve injury and in the basal forebrain of patients with Alzheimer's disease. We have previously demonstrated that galanin modulates hippocampal neuronal survival, although it was unclear which receptor subtype(s) mediates this effect. Here we report that the protective role played by galanin in hippocampal cultures is abolished in animals carrying a loss-of-function mutation in the second galanin receptor subtype (GalR2-MUT). Exogenous galanin stimulates the phosphorylation of the serine/threonine kinase Akt and extracellular signal-regulated kinase (ERK) in wild-type (WT) cultures by 435 +/- 5% and 278 +/- 2%, respectively. The glutamate-induced activation of Akt was abolished in cultures from galanin knockout animals, and was markedly attenuated in GalR2-MUT animals, compared with WT controls. In contrast, similar levels of glutamate-induced ERK activation were observed in both loss-of-function mutants, but were further increased in galanin over-expressing animals. Using specific inhibitors of either ERK or Akt confirms that a GalR2-dependent modulation in the activation of the Akt and ERK signalling pathways contributes to the protective effects of galanin. These findings imply that the rise in endogenous galanin observed either after brain injury or in various disease states is an adaptive response that reduces apoptosis by the activation of GalR2, and hence Akt and ERK.