Citrate utilization by free and immobilized Streptococcus lactis subsp. diacetylactis in continuous culture

Summary The effects of pH, temperature and concentration of citrate were investigated to achieve an optimal production of diacetyl, acetoin and C₂ compounds such as acetaldehyde, acetate and ethanol for free and immobilized cells. The critical conditions of culture, 22°C, pH 4.8, increased the production of C₄ compounds (diacetyl, acetoin, 2, 3 butylene glycol), C₂ compounds (acetaldehyde, ethanol, acetate) and formate. A higher yield of C₂ and C₄ compounds was observed for the immobilized cells than for the free cells in continuous culture. At 75 mMol/l of citrate, the citrate bioconversion yield was 42.8% and 80% for free and immobilized cells, respectively. This paper discusses citrate and lactose utilization and NADH₂ part on diacetyl reduction.     

Influence of enkephalinase inhibitors on gastric emptying in mice depends on the nature of the meal

The effects of two enkephalinase inhibitors (thiorphan and acétorphan) and DALAMIDE on gastric emptying of fat or non-fat meals were evaluated in mice. When administered intraperitonally at low doses (0.1 and 0.2 mg/kg) 30 min prior to a fatty (milk) meal, both thiorphan and acetorphan increased significantly (P less than 0.01) gastric emptying; these effects were maximal for 0.2 and 0.1 mg/kg respectively and decreased progressively to be not significant for doses higher than 5 mg/kg for thiorphan and 0.5 mg/kg for acetorphan. Similarly DALAMIDE given IP increased significantly (P less than 0.05) gastric emptying at doses of 0.5 and 1 mg/kg while a slowing of gastric emptying was obtained for 10 times higher doses. The effects of thiorphan (0.2 mg/kg) and DALAMIDE (0.5 mg/kg) were blocked by previous administration of naloxone (0.3 mg/kg) and methyl-naloxone (0.5 mg/kg) while only naloxone (0.3 mg/kg) blocked the slowing effect of high dose of DALAMIDE. Administered prior to a non-fat meal, thiorphan (1 mg/kg) stimulated gastric emptying and inhibited it at higher dosage (10 mg/kg). Neither acetorphan nor DALAMIDE at similar dosages affected the gastric emptying of a non-fat meal and the effects of thiorphan (1 and 0.1 mg/kg) were not blocked by naloxone (0.3 mg/kg). It is concluded that enkephalinase inhibitors (thiorphan and acetorphan) administered systemically stimulate the gastric emptying of a fat meal by increasing enkephalin levels in peripheral tissues, while thiorphan exhibits non-opiate effects on gastric emptying of a non-fat meal.     

The convergent trajectories of bird communities along ecological successions in european forests

Summary There is much more variation in the composition of bird communities in the earlier open and semi-open seral stages of ecological successions in forested landscapes of Europe than later on in preforested and forested climactic stages. The demonstration of this trend is achieved from the study of four habitat gradients, two in the mediterranean region (Provence and Corsica) and two in central Europe (Burgundy, France and Poland). A multivariate analysis has been used to illustrate the dynamics of communities along these succession. Displays of the results in bivariate space as well as an illustration of the distributional profiles of some of the most characteristic species show that: i) there is a discrimination between the two mediterranean gradients and the two medioeuropean ones and ii) each succession starts with a very distinct set of species and then the four gradients regularly converge in the last climactic stage where there is almost no discrimination between communities. These results are discussed in the light of the history of European biotas during the Pleistocene. The reason why there is more variation in species composition in the earlier seral stages than in the later forested stages are discussed according to current theories on the role of habitat selection on speciation processes.     

Gene Expression in Developing Zea mays Embryos: Regulation by Abscisic Acid of a Highly Phosphorylated 23- to 25-kD Group of Proteins

We have earlier identified a set of proteins of 23 to 25 kilodaltons (kD), covering an isoelectric point (pI) range of 6.2 to 8.2, which accumulate gradually during normal embryogenesis of Zea mays and disappear in early germination. These polypeptides can be induced prematurely in immature embryos by abscisic acid (ABA) treatment. We report here that the more acidic protein forms are due to post-translational phosphorylation of at least two polypeptides of 23 kD, pI 8.2 and 25 kD, pI 8.0. A polyclonal antiserum was obtained which recognizes all forms of both the 23-kD and 25-kD polypeptides. Recovery of cDNA clones corresponding to these proteins was accomplished by hybridization with cDNA made from size-selected mRNA enriched for these sequences. Hybrid selection experiments demonstrate that clone MA12 specifically hybridizes with mRNAs encoding the 23-kD and 25-kD protein set which are recognized by the antiserum. By Northern hybridization analysis, the RNA encoded by clone MA12 is shown to accumulate in mature embryos and to be induced in young embryos upon ABA incubation.     

Nuclear protein transitions in cuttle-fish spermiogenesis: Immunocytochemical localization of a protein specific for the spermatid stage

The changes in basic nuclear proteins throughout cuttle-fish spermiogenesis were investigated both by immunocytochemical procedures and by isolation of late spermatid nuclei (by virtue of their resistance to sonication). Antibodies were raised in rabbits to a protein, named protein T, isolated from testis chromatin. The anti-protein T immune serum was found to recognize protein T and not histones from the testis. Immunoperoxidase staining of sections or of smears of testis with anti-protein T antibodies showed that protein T appears in the nuclei of round spermatids, is abundant in elongating spermatid nuclei, but cannot be detected in elongated spermatids. Nuclei from these elongated spermatids were isolated by sonication treatment of testis cells. A protein, named protein Sp, with the characteristic mobility of a protamine, was isolated from elongated spermatid nuclei. This protein has the same mobility as the protamine present in mature spermatozoa. Taken together, the results indicate that in cuttle-fish, nuclear protein transitions involve the replacement of histones by a spermatid-specific protein (protein T), which is replaced at the end of elongation of the nucleus by a protamine (protein Sp). Thus, spermiogenesis of the cuttle-fish (and perhaps of other cephalopods), shows two basic nuclear protein transitions, which are similar to the transitions observed in higher vertebrates such as mammals.     

Transposase-induced excision and circularization of the bacterial insertion sequence IS911.

We have investigated the role of three IS911-specified proteins in transposition in vivo: the products of the upstream (OrfA) and downstream (OrfB) open reading frames, and a transframe protein (OrfAB) produced by -1 translational frameshifting between orfA and orfB. The production of OrfAB alone is shown to lead both to excision and to circularization of the element and to be sufficient for intermolecular transposition into a plasmid target. Simultaneous and independent production of OrfA is shown to stimulate OrfAB-mediated intermolecular transposition while greatly reducing the appearance of transposon circles. We have not been able to detect a role for OrfB. Although under certain conditions, the vector plasmid undergoes precise resealing after IS911 excision, the data suggest that this is not normally the case and that the donor plasmid is not generally conserved. The use of IS911 derivatives carrying mutations in the terminal 2 bp suggested that circle formation represents a site-specific intramolecular transposition event. We present a model which explains both intra- and intermolecular transposition events in terms of a single reaction mechanism of the 'cut and paste' type.     

Distribution of histamine in the rat kidney during pregnancy and development

Summary An antiserum against conjugated histamine and two oligonucleotide probes that detect the mRNA encoding L-histidine decarboxylase (HDC) involved in histamine synthesis were used to study the appearance of histamine and its location in the kidneys of fetal, newborn and young postnatal rats and in the kidneys of pregnant rats. On embryonic days 16 and 18 (E16 and E18), some HA-immunoreactive (HA-ir) cells were found within the largest S-shaped bodies. Histamine was found to appear rapidly between the 18th and 20th embryonic days in the convoluted tubules of the kidneys. On postnatal day 0 (P0), the distal convoluted tubules and collecting ducts exhibited bright fluorescence, the intensity of which decreased quickly so that it was faint on day P4 and absent at later stages. In kidneys of pregnant rats HA-ir was found in the epithelium of both the Bowman's capsule, collecting ducts and in a few cells within the tubules. Nonuniform HA-ir was also detected within glomeruli. No evidence for the presence of L-histidine decarboxylase mRNA in kidneys of fetuses or pregnant rats was seen. It is concluded that distinct structures in the developing rat kidney contain histamine during a period around birth from day E20 to day P4. In the pregnant rat, the epithelium that is in direct contact with the urine flow is immunoreactive for histamine from day 16 to 20 of pregnancy. The results suggest that histamine is not synthesized locally in the kidneys but rather originates from other tissues.     

The polymorphism ApoB/4311 in patients with myocardial infarction and controls: the ECTIM study

Summary The polymorphism affecting codon 4311 of the apolipoprotein B gene (ApoB/4311) was investigated in a large case-control study in two French and one Northern Irish geographically defined populations. Cases were recruited 3 to 9 months after a myocardial infarction (MI) and controls were randomly selected from the population. The polymorphism was assessed using allele-specific oligonucleotides (ASO). The genotype frequencies of the ApoB/4311 polymorphism did not differ in Northern Ireland and France and were in Hardy-Weinberg equilibrium in all groups; strong associations with three other polymorphisms of the ApoB gene (XbaI, EcoRI, VNTR(34 repeats)) were observed and it was possible to identify highly sensitive and specific markers of the ApoB/4311 rare variant. Homozygotes for the ApoB 4311 rare variant were slightly less frequent in cases than in controls: 22 (4.4%) and 35 (6.7%) respectively (population adjusted ²=3.3 P<0.07), especially in Belfast: 6 (3.1%) and 12 (7.6%), respectively (P<0.06). Several lipid and lipoprotein parameters were measured. Consistently among control groups, rare homozygotes had lower mean levels of ApoB (P<0.02), triglycerides (P<0.02), and lipoprotein particles containing ApoE and ApoB (LpE:B; P<0.001) and a higher mean level of lipoprotein particles containing ApoAI and not ApoAII (LpAI; P<0.02) than heterozygotes and frequent homozygotes combined. The strong association between the ApoB/4311 polymorphism and LpE:B was also observed in patients with MI. When present in the homozygous form, the ApoB/ 4311 AsnSer variant is associated with a lipoprotein profile that is apparently favourable.     

Variants of the anti-Müllerian hormone gene in a compound heterozygote with the persistent Müllerian duct syndrome and his family

Summary The human genome contains a large number of interspersed simple repeat sequences that are variable in length and can therefore serve as highly informative, polymorphic markers. Typing procedures include conventional multilocus and single locus probing, and polymerase chain reaction aided analysis. We have identified simple sequences in a cosmid clone stemming from the human Y chromosome and consisting of (gata)_n repeats. We have compared these with two equivalent simple repeat loci from chromosome 12. After amplifying the tandemly repeated motifs, we detected between four and eight different alleles at each of the three loci. Codominant inheritance of the alleles was established in family studies and the informativity of the simple repeat loci was determined by typing unrelated individuals. The polymorphisms are suitable for application in linkage studies, practical forensic case work, deficiency cases in paternity determination, and for studying ethnological questions. The mutational mechanisms that bring about changes in simple repeats located both on the autosomes and on the sex chromosomes, are discussed.Professor Dr. Otto Prokop (Humboldt-Universität Berlin) on the occasion of his 70th birthday