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Notes: The pattern of cytospindle assembly and the modifications of the microtubular cytoplasmic network during division of Paramecium are studied by means of indirect immunofluorescence. The assembly of cytospindle starts at two independent areas placed respectively around the proter's and opisthe's buccal overture. The moment of the microtubule bundles’appearance depends on their distance from the buccal opening, with those closest appearing 1st. The existence of microtubule organizing centers that act transiently during division of Paramecium is discussed.

Notes: The spatial distribution of radiation-induced, radiative recombination centers in single-junction p+-n InGaP solar cells irradiated by 1 MeV electrons or 3 MeV protons has been determined from cathodoluminescence (CL) spectra. The energy levels of the radiation-induced, nonradiative recombination centers were determined from the temperature dependence of the CL intensity. © 1999 American Institute of Physics.

Notes: The effects of electron and proton irradiation on p+–n InGaP solar cells grown on GaAs substrates are investigated using cathodoluminescence (CL) and transmission electron microscopy (TEM). The CL measurements confirm the higher radiation resistance and defect annealing properties of InGaP compared to those of GaAs. The CL measurements also indicate the occurrence of a radiation-induced sublattice order–disorder transition in InGaP. TEM reveals the presence of ordering domains in the as-grown cells, which are effectively removed by radiation-induced defects. The results should be useful in the fabrication of radiation-resistant single-junction and dual-junction InGaP solar cells for space. © 1999 American Institute of Physics.

Notes: To verify the compatibility behaviour of the almond cultivar ‘Francolí’ and to clarify its S genotype a combination of pollination tests, stylar ribonuclease and allele specific PCR analysis was used. ‘Francolí’ was released from IRTA's breeding programme in 1994, having been putatively raised from the cross ‘Cristomorto’ (S1S2) × ‘Gabaix’ (S10S25). This cultivar was also reported to be self-incompatible but revealing only one S band in the zymograms after S-RNases analysis. ‘Francolí’ sets nuts after test crossing with two S1S25 cultivars, having a different genotype from that earlier reported. ‘Francolí’ was also observed to be self-compatible after selfing flowers in the field and in the laboratory. ‘Francolí’ was re-assigned the S1Sf genotype after test crossing, stylar ribonuclease and PCR data analysis. After microsatellite analysis, the self-compatible ‘Tuono’ (S1Sf) cultivar is suggested as the male parent of ‘Francolí’ instead of the earlier reported ‘Gabaix’.

Notes: Differentiation of hypophysiotropic neurones that regulate the secretion of growth hormone (GH) and prolactin is influenced by GH and prolactin. Genetic GH and prolactin deficiency in mutant rodent models such as the Ames dwarf (df/df) mouse results in an increase in the number of GH-stimulatory GH-releasing hormone (GHRH) neurones and a reduction of prolactin-inhibitory tuberoinfundibular dopaminergic (TIDA) neurones in the arcuate nucleus during postnatal development. The present study tested the hypothesis that these concomitant changes in numbers of tyrosine hydroxylase (TH)- and GHRH-immunoreactive neurones in df/df hypothalamus might represent a neuronal population of fixed number that undergoes a partial change in phenotype during postnatal development. To evaluate this possibility, the postnatal reduction of the df/df TIDA population was prevented by administering prolactin neonatally to preserve TH phenotype; dwarf and normal sibling mice were treated with daily injections of ovine prolactin or vehicle starting at postnatal day 12 and continuing for 30 days. Following this treatment, numbers of arcuate neurones containing GHRH or TH, or both, were quantified using immunocytochemistry. It was hypothesized that prolactin preservation of TH-immunoreactive cell number would be accompanied by either a decrease in the GHRH-producing population or an increase in numbers of cells producing both TH and GHRH. In prolactin-treated normal (DF/df) mice, numbers of arcuate TH-immunoreactive neurones were similar to those in vehicle-treated normals. Numbers of TH-positive neurones in prolactin-treated dwarfs were higher than in vehicle-treated dwarfs, and did not differ from numbers in DF/df. Numbers of GHRH-immunoreactive cells in vehicle-treated df/df were higher than in vehicle-treated DF/df, and were not different in prolactin-treated groups of either dwarf or normal mice. Neurones containing both TH and GHRH constituted 15% of the TH population, and 76% of the GHRH population, in control normal mice; in control dwarfs, double-labelled cells were 9.3% of TH and 9.9% of GHRH. Numbers of cells immunoreactive for both TH and GHRH were not affected by prolactin treatment in either mouse type. These results demonstrate that the increase in number of GHRH-expressing neurones in the df/df arcuate nucleus does not occur at the expense of the TH phenotype, and that this increase is not influenced by prolactin feedback. Although coexpression of TH and GHRH in a subpopulation indicates that TIDA and GHRH populations are not exclusive, they appear to be influenced independently by prolactin and GH signals during development.

Notes: Indirect estimates of leaf area from measurements with three commercially available instruments (DEMON, LAI-2000 and Sunfleck Ceptometer) were compared with directly measured areas of individual Retama sphaerocarpa bushes. The three indirect methods gave good estimates of the total surface area of individual bushes. For the DEMON, the method of log-linear averaging of transmitted radiation gave estimates closer to directly measured surface area than the method of averaging transmission linearly. For the LAI-2000, estimated surface area index multiplied by canopy projected area gave the best agreement with directly measured values. For measurements with the Sunfleck Ceptometer, values of surface area estimated from the transmission of photosynthetic quantum flux density, without correcting for diffuse radiation, gave the best agreement with directly measured values. Surface areas estimated by the three instruments were not significantly different from directly measured total (leaf + branch + stem) surface areas. Leaf surface area could be calculated from estimated total surface area minus directly measured branch surface area. Measured branch surface area was linearly related to canopy projected area.

Notes: The M-current (IK(M)) is believed to modulate neuronal excitability by producing spike frequency adaptation (SFA). Inhibitors of M-channels, such as linopirdine and 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone (XE991), enhance depolarization-induced transmitter release and improve learning performance in animal models. As such, they are currently being tested for their therapeutic potential for treating Alzheimer's disease. The activity of these blockers has been associated with the reduction of SFA and the depolarization of the membrane observed when IK(M) is inhibited. To test whether this is the case, the perforated patch technique was used to investigate the capacity of IK(M) inhibitors to alter the resting membrane potential and to reduce SFA in mouse superior cervical ganglion neurons in culture. Linopirdine and XE991 both proved to be potent blockers of IK(M) when the membrane potential was held at −30 mV (IC50 2.56 and 0.26 µm, respectively). However, their potency gradually declined upon membrane hyperpolarization and was almost null when the membrane potential was kept at −70 mV, indicating that their blocking activity was voltage dependent. Nevertheless, IK(M) could be inhibited at these hyperpolarized voltages by other inhibitors such as oxotremorine-methiodide and barium. Under current-clamp conditions, neither linopirdine (10 µm) nor XE991 (3 µm) was effective in reducing the SFA and both provoked only a small slowly developed depolarization of the membrane (2.27 and 3.0 mV, respectively). In contrast, both barium (1 mm) and oxotremorine-methiodide (10 µm) depolarized mouse superior cervical ganglion neurons by about 10 mV and reduced the SFA. In contrast to classical IK(M) inhibitors, the activity of linopirdine and XE991 on the IK(M) is voltage dependent and, thus, these newly developed IK(M) blockers do not reduce the SFA. These results may shed light on the mode of action of these putative cognition enhancers in vivo.