Bibliothek

Notizen: 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.

Notizen: 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.

Notizen: Isozyme variability was assessed among the principal species of the cereal cyst nematode complex to complete and enhance the information provided by classical nematode systematics, in order to clarify inter- and intraspecific relationships within this complex. Twenty populations of cereal cyst nematodes (Heterodera avenae, H. filipjevi, H. latipons and H. mani) were compared by means of five different isoenzymatic systems (esterase, malate dehydrogenase, phosphoglucoisomerase, phosphoglucomutase and superoxide dismutase) using isoelectrofocusing (IEF) on the electrophoretic separation. The results are in agreement with previous morphological and biochemical characterizations, which established genetic diversity between the Gotland strain and H. avenae and identified the Gotland strain with H. filipjevi. Populations from Israel, all included in the H. avenae group, exhibited well-defined intraspecific dissimilarity. The highest degree of polymorphism was found in the H. avenae group for all five enzymatic systems studied. The H. mani population was also included in the H. avenae group by these isozyme analyses. Malate dehydrogenase, phosphoglucoisomerase and phosphoglucomutase isozymes, fractionated for the first time by IEF in the cereal cyst nematode complex, displayed a higher level of polymorphism than using conventional electrophoresis. Isoelectric focusing has proved to be a useful tool for detecting genetic diversity within and among species of the cereal cyst nematode complex and for taxonomic purposes.

Notizen: 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’.

Notizen: HLA-DPB1 allele frequencies in 181 unrelated control individuals and 70 rheumatoid factor-positive RA patients from Seville (Spain) were determined using oligonucleotide typing methods. All frequencies shown concern the percentage of individuals positive for a certain allele. HLA-DPB1*0401 was the most common DPB1 allele in the healthy individuals, possessed by 65.7% of them. In addition to HLA-DPB1 *0401, only the following alleles were found in normal subjects at frequencies greater than 10%: DPB1*0101 (15.5%), DPB1*0201 (12.2%), DPB1*0301 (16.6), and DPB1*0402 (29.3%). When HLA-DPB1 allelic frequencies were compared between seropositive RA patients and controls, a negative association for DPB1*0301 and DPB1*0401 was found in RA patients, although it failed to reach statistical significance after correction for the number of comparisons made. The other DPB1 alleles exhibited almost identical frequencies in both groups. However, when only DR4+ patients and controls were considered, the decrease in the frequency of the DPB1*0301 and DPB1*0401 alleles lacked statistical significance. On the other hand, when DR4- RA patients and controls were compared, the frequency of DPB1*0301 was found decreased significantly again, even more than in the whole group of patients.

Notizen: 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.

Notizen: 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.