Genome relationship betweenPsathyrostachys huashanica andP. fragilis (Poaceae)

Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.     

An acetyl esterase of Trichoderma reesei and its role in the hydrolysis of acetyl xylans

Summary An acetyl esterase was purified from Trichoderma reesei by cation and anion exchange chromatography. The enzyme had a molecular weight of 45 000 as determined by SDS-electrophoresis, or 67 000 as determined by gel filtration. In chromatofocusing the enzyme was shown to consist of two isoenzymes with isoelectric points of 6.8 and 6.0. The enzyme showed activity towards naphthyl acetate, triacetin and glucose-and xylose acetates. However, it liberated acetic acid from acetylated xylo-oligomers only to a small extent. The liberation of acetic acid from the oligomeric substrate was enhanced by addition of endoxylanase and -xylosidase.     

A propos de l'article ‘The B-chromosomes of Locusta migratoria I. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the B's; a reanalysis of the available data about the transmission of these B-chromosomes’, par. J. Cabrero,E. Viseras et J. P. M. Camacho

Comment on the article ‘The B-chromosomes of Locusta migratoria I. Detection of negative correlation between mean chiasma frequency and the rate of accumulation of the B's; a reanalysis of the available data about the transmission of these B-chromosomes’ — Some critical remarks on the said article (published in Genetica 64: 155–164, 1984) are presented.     

Inheritance of pollen enzymes and polyploid origin of apple (Malus x domestica Borkh.)

Summary Electrophoresis of 7 pollen enzymes was applied to 5 progenies from controlled crosses and one self-progeny of apple. Segregation data were examined according to three kinds of hypotheses: monogenic disomic, bigenic disomic and tetrasomic inheritance Twenty codominant alleles and a recessive null were identified. Results provided evidence of bigenic disomic inheritance in most cases: 6 pairs of homoeologous loci carrying identical homoeoalleles were revealed; only 2 enzymes exhibited a simple monogenic control. Preferential pairing between pairs of homologous chromosomes in meiosis can be postulated. These results indicated an allopolyploid origin of apple genome. Fixed heterozygosity occurred for several enzymes, which is a typical feature of allopolyploidy. Loss of duplicate gene expression can account for the monogenic control of 2 of the enzymes.The results reported in this paper are part of a thesis by the first author for the degree of Docteur Ingénieur     

Comportement des chromosomes surnuméraires et relation avec le taux de mortalité dans une population africaine de Locusta migratoria migratorioides

Transmission of supernumerary chromosomes is studied in adults and embryos of an African population of Locusta migratoria migratorioides; 34% of the animals show one or two B chromosomes (24% one, 10% two). This percentage is the same in both sexes. During mitosis, B chromosomes are very stable. At meiosis, in some cases they show pairing, in other cases they enter as univalents. The eventuality of synapsis or association is discussed. These two kinds of behaviour could not be explained by the presence of two different B chromosomes as is shown from the study of parthenogenetic progeny. Repartition of B chromosomes in the progeny is different depending on whether the male or the female parent supplies them; so the behaviour of these supernumerary should be conditioned, not by their own structure, but by a connection with the cell. — One B chromosome apparently is neutral. When there are two B chromosomes, in case of synapsis, the number of animals with two B in the progeny is slightly lower than previous; in case of asynapsis, there is a higher lethality of individuals and oocytes with two B chromosomes.     

Expression of genes for plastid membrane proteins in barley under intermittent light conditions

Barley plants grown under intermittent light show a plastid membrane composition intermediate between those of etioplasts and chloroplasts. In particular protochlorophyll reductase disappears from the membranes whereas the 32000 protein, coded for by chloroplast DNA, becomes integrated into the membranes. The light-harvesting chlorophyll a/b protein does not accumulate within the membranes even after 11 d of development, while the corresponding mRNA can already be observed after 4 d and is translated under in vivo conditions.Abbreviations LHCP light-harvesting chlorophyll a/b protein - IL intermittent light - LD light-dark (12-h day) - EGTA ethyleneglycol-bis(oxy-ethylenenitrile)tetraacetic acid     

Kinetics of the appearance of mRNA for light-harvesting chlorophyll a/b protein in polysomes of barley

Polysomes from dark-grown and illuminated barley seedlings were translated in cell-free systems. The translation products reacting with the antibody against the light-harvesting chlorophyll a/b protein (LHCP) were analyzed by polyacrylamide gel electrophoresis. It was found that, in addition to the precursor protein of LHCP, a product was obtained that co-migrated with the mature protein. Furthermore, the results show that the light-induced proly(A)RNA for LHCP is integrated into the polysomal complex without delay, indicating that the integration of LHCP into the membrane is controlled at a higher level of gene expression.