Sex Differences in the Steepness of Dominance Hierarchies in Captive Bonobo Groups

Bonobos have a reputation as a female-dominated and egalitarian species. We examined the 2 aspects of dominance in 6 captive bonobo groups. Females do not consistently evoke submission from all males in all contexts. Though females occupy the highest-ranking positions in the dominance hierarchy, there are in each group males that obtain rather high ranks and are able to dominate ≥1 female. Thus female dominance is not complete and hierarchies can be better described as nonexclusive female dominance. We studied egalitarianism by measuring linearity and steepness of dominance hierarchies. The hierarchies of all groups are highly linear. Hierarchies among males are steeper than among females. On average, male bonobos are more despotic than females, but females too can have despotic relations, both with other females and with males. Hence one can call bonobos in captivity semidespotic rather than egalitarian.     

Microbial populations and activity in two soils of Tanzania as influenced by mercury

Summary The influence of mercury on microbial populations and activity of two soils from Tanzania was studied. Aretan (2-methoxyethylmercury chloride) slightly affected the microbial population of the Morogoro (Oxisol) soil, which was 10⁷ c.f.u./g in control soil and 10⁶ c.f.u./g in the presence of 2000 mg Hg/kg soil. Mercuric chloride at >8 mg Hg/kg soil increased the population slightly, with a sharp decrease at >100 mg Hg/kg soil, dropping ultimately to 10³ c.f.u./g at 2000 mg Hg/kg soil. In the Arusha (Andept) soil, the microbial response to the two mercury compounds was the opposite of that for the Morogoro soil. Aretan sharply reduced the nitrogenase activity of aerobically incubated Morogoro soils at Hg levels >24 mg/kg, resulting in very low activity at >50 mg Hg/kg soil. Mercuric chloride increased the activity, which showed a peak at 24 mg Hg/kg soils, followed by a sharp drop at 30 mg Hg/kg and remained low thereafter. In the Arusha soil, the activity was reduced gradually by both Aretan and HgCl₂. The response of the activity under anaerobic incubation in the Morogoro soil was the opposite of that under aerobic incubation, in that it was Aretan which at first increased the activity. In the Arusha soil the activity under anaerobic incubation decreased gradually over the entire range of added Hg. Nitrification was decreased by HgCl₂ atlevels of <2 and <10 mg Hg/kg soil in the Arusha and Morogoro soils, respectively. The tolerance to Hg by microorganisms in this study was in the order: total population > nitrogen fixers > nitrifiers. This may be explained in terms of species diversity of the microorganisms, which may be expected to follow the same sequence.

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Population et activités microbiennes dans deux sols de Tanzanie sous l'influence du mercure

Résumé On étudie l'influence du mercure sur les populations et les activités microbiennes de deux sols en provenance de Tanzanie. L'Aretan (chlorure de 2-méthoxyéthylmercure) n'affecte que faiblement la population microbienne du sol de Morogoro (oxisol), qui compte 10⁷ individus par g dans le sol témoin et 10⁶ individus en présence de 2000 mg de mercure par kg de sol. Le chlorure mercurique, à une dose supérieure à 8 mg de mercure par kg de sol, augmente quelque peu la population. Celle-ci décroît brutalement au delà de 100 mg de mercure par kg de sol, pour tomber finalement à 10³ individus par g à 2000 mg de mercure par kg de sol. Dans le sol d'Arusha (Andept), la réponse microbienne aux deux composés mercuriels est l'inverse de celle obtenue avec le sol de Morogoro. L'Aretan réduit fortement l'activité de la nitrogénase de sols de Morogoro incubés en aérobiose à des teneurs en mercure au delà de 24 mg par kg. L'activité devient très faible au delà de 50 mg de mercure par kg de sol. Le chlorure mercurique augmente cette activité, avec un pic de 24 mg de mercure par kg de sol, suivi d'une chute sévère à 30 mg de mercure par kg. L'activité demeure faible aux doses plus fortes. Dans le sol d'Arusha, l'activité est réduite progressivement tant par l'Aretan que par HgCl₂. La réponse de l'activité en incubation anaérobie dans le sol de Morogoro est l'inverse de celle en incubation aérobie en ceci que c'est l'Aretan, cette fois-ci, qui augmente d'abord l'activité. Dans le sol d'Arusha, l'activité en incubation anaérobie décroît progressivement sur l'échelle entière des concentrations d'ajout de mercure. La nitrification est réduite par HgCl₂ à des seuils au dessous de 2 et 10 mg de mercure par kg de sol, respectivement pour les sols d'Arusha et de Morogoro. La tolérance des microorganismes au mercure dans cette étude est dans l'ordre: population totale > fixateurs d'azote > nitrificateurs. Ceci peut être expliqué en termes de diversité des espèces de microorganismes qui suit vraisemblablement la même séquence.

     

Flowering and fruiting phenology in the apomictic blackberry, Rubus nessensis (Rosaceae)

Five stands of an apomictic blackberry, Rubus nessensis , were studied. Biennial shoots flower and fruit in their second year on lateral branches developed from axillary buds. Most premature death of reproductive units occurs by withering of entire laterals, presumably due to damage by frost during the preceeding autumn or winter. Health status of the floricane, assessed as percentage live axillary buds in the spring, was positively correlated with the reproduction parameters. Shoot height as well, is positively correlated with number of flower buds and flowers produced on each lateral but, however, negatively correlated with number of berries, probably because tall shoots tend to suffer more damage by frost which seriously afflicts the vascular tissues of the laterals.
The position of the axillary buds on the shoot affects survival and degree of fertility, those situated medially greatly surpassing apical and basal ones.     

Identical subcellular distribution of palmitoyl-CoA and arachidonoyl-CoA synthetase activities in human blood platelets.

Fractionation of human blood platelets showed that palmitoyl-CoA synthetase and arachidonoyl-CoA synthetase activities had an identical distribution among subcellular fractions. The activity was highest with arachidonic acid as substrate in all fractions, with an enzyme activity of 50 nmol/min per mg of protein, in a 'dense-tubular-system'-enriched fraction. The ratio activities with arachidonate and palmitate as substrates was about 1.5 in all fractions. Heat inactivation did not distinguish between arachidonoyl-CoA synthetase and a palmitoyl-CoA synthetase. On the other hand, heat inactivation indicated two pools of long-chain acyl-CoA synthetases: one in a mitochondria- and one in the dense-tubular-system-enriched fraction.     

Effect of the Urtica dioica agglutinin on germination and cell wall formation of Phycomyces blakesleeanus Burgeff

The lectin from stinging nettle rhizomes, Urtica dioica agglutinin (UDA), did not affect the evolution of wet and dry weight, protein, nucleic acid, ATP, cAMP and glycerol content during early germination of Phycomyces blakesleeanus spores. However, earlier investigations established a strongly reduced mycelial growth of several phytopathogenic fungi by this small plant lectin. Total uptake and incorporation of radioactive precursors showed no differences between UDA or control hyphae, but UDA significantly altered the distribution patterns of [¹⁴C]-glucose incorporated into the walls of Phycomyces blakesleeanus (more label was recovered in the chitin fraction). Moreover, a small but significant stimulation of chitin synthase and a similar inhibition of chitin deacetylase was found in cell wall preparations. These observations could lead to a better understanding of plant-pathogen interrelationships and to a further elucidation of cell wall structure in fungi.Abbreviations GlcNAc N-Acetylglucosamine - PDB potato dextrose broth - PMM Phycomyces minimal medium - UDA Urtica dioica agglutinin - TEA tri-ethyl-amine - DAB 1,4-diaminobutanone     

Signal peptidase I overproduction results in increased efficiencies of export and maturation of hybrid secretory proteins in Escherichia coli

Summary The effects of 25-fold overproduction ofEscherichia coli signal peptidase I (SPase I) on the processing kinetics of various (hybrid) secretory proteins, comprising fusions between signal sequence functions selected from theBacillus subtilis chromosome and the mature part of TEM-β-lactamase, were studied inE. coli. One precursor (pre[A2d]-β-lactamase) showed an enhanced processing rate, and consequently, a highly improved release of the mature enzyme into the periplasm. A minor fraction of a second hybrid precursor (pre[Al3i]-β-lactamase), which was not processed under standard conditions of SPase I synthesis, was shown to be processed under conditions of SPase I overproduction. However, this did not result in efficient release of the mature β-lactamase into the periplasm. In contrast, the processing rates of wild-type pre-β-lactamase and pre(A2)-β-lactamase, already high under standard conditions, were not detectably altered by SPase I overproduction. These results demonstrate that the availability of SPase I can be a limiting factor in protein export inE. coli, in particular with respect to (hybrid) precursor proteins showing low (SPase I) processing efficiencies.     

The cytochrome oxidase II gene in mitochondria of the sugar-beetBeta vulgaris L.

We have cloned and analyzed the sugar-beet mitochondrial gene for cytochrome oxidase subunit II (coxII). The sugar-beet and its deduced amino acid sequence were compared to its homologouscoxII gene sequences from both monocot and dicot plants. It was found to be highly conserved (89–95%) compared to homologue in other plant species. The 780 bp coding sequence of the sugar beetcoxII gene is interrupted at position 383 by a 1463 bp intron. This intron contains an additional 107 bp sequence that is not found in any of the plantcoxII genes studied thus far. The structure of the intron suggests that a large intron existed in an ancestralcoxII gene before monocots and dicots diverged in evolution. Three CGG codons in the sugar-beetcoxII coding sequence align with conserved tryptophan residues in the homologous gene of other species, suggesting that RNA editing takes place also in sugar-beet mitochondria. In 13 out of 24 codons ofcoxII mRNA that were found to be edited in four other plants, the sugar-beet gene already utilizes the edited codons. This phenomenon may indicate that the mitochondrial genome in sugar-beet is phylogenetically more archaic relative to these plants. An additional sequence of 279 bp that is identical to the first exon ofcoxII was identified in the mtDNA of the sugar-beet. This pseudo-gene is transcribed and its existence in the mitochondrial genome is unexplained.     

Energetic costs of the winter arboreal microclimate: The gray squirrel in a tree

Heated taxidermic mounts of the gray squirrel were used to analyze the thermal environment of a small arboreal endotherm. Changes in the standard operative temperature (T _es) calculated from the temperatures of heated and unheated mounts agreed well with the power consumption (M–E) of mounts on the ground and on the wind-ward side of a 48-cm diameter tree trunk. As wind speed (u) rose and sky solar radiation (Q _r) decreased, the windward side of the tree trunk became an increasingly more stressful thermal environment than the leeward side of the trunk or the ground, producingM–E differences of more than 30%. Although theM–E of a ground mount and a limb mount 4 m in the air are dependent onQ _ras well asu, the ratio of the two value ofM–E is independent ofQ _r, poorly predicted byu and well predicted byu ^1/2.     

Physicochemical aspects of carbohydrate binding to some plant lectins with binding preference forN-acetylgalactosamine and galactose

This contribution illustrates the advantages of some chromophoric and fluorophoric carbohydrate derivatives such asp-nitrophenyl (pNO₂Phe) or 4-methylumbelliferyl (MeUmb) glycosides andN-dansylgalactosamine in studies of the binding equilibrium and kinetics with some plant lectins. The methods used involve continuous titrations of changes in ligand or protein absorption and ligand fluorescence, including substitution titrations as well as stopped-flow, temperature-jump or pressure-jump relaxation kinetics. When monitored by temperature-jump relaxation, binding of MeUmbαGal to the bloodgroup A specific lectin GSAI-A₄ fromGriffonia simplicifolia is a simple bimolecular association with parametersk ₊ = 9.4 × 10⁴ M^-1 s^-1 andk _-1 = 5.3 s^-1 at 23°C, but binding to the GSAI-B₄ lectin is biphasic. The complementarity of the peanut agglutinin binding site with Galβ1 → 3GalNAc that occurs in manyO-glycoproteins follows from enthalpic considerations and also from the value of the dissociation-rate parameterk _-1 = 0.24 s^-1 of the MeUmbβGalβl → 3GalNAc.lectin complex. This value, obtained by stopped-flow kinetics is 100 times smaller than for other mono-and disaccharides investigated. The binding mechanism is simple and the derivatisation of Galβ1 → 3GalNAc does not affect the affinity to a considerable degree. The binding preference of tetravalentsoybean agglutinin for MeαGalNAc over MeαGal by a factor of 25 is mainly of enthalpic origin with an additional 7 kJ mol^-1; the NAc group causes perturbation of a tryptophanyl residue, evidenced by protein difference absorption spectrometry. In the glycosides, a large aglycon likeβpNO₂ Phe orβMeUmb hardly affects the affinity of SBA but a largeN-dansyl group increases the affinity by a factor 20 as compared to GalNAc. The 10-fold increase in carbohydrate-specificN-dansylgalactosamine fluorescence, together with a very favourable entropic contribution point at the presence of a hydrophobic region in the vicinity of the carbohydrate-binding site. The dissociation-rate parameter of the MeUmbβGalNAc SBA complex is slower than for any reported monosaccharide-lectin complex: 0.4 s^-1. The divalent lectin fromErythrina cristagalli preferentially binds the Galβ1 → 4GlcNAc structure that occurs in manyN-glycoproteins. The combining site was mapped thermodynamically with carbohydrates ranging from mono-to pentasaccharides as derived fromN-glycoproteins. Here, N-dansylgalactosamine was used as a fluorescent indicator ligand in substitution titrations. When Galβ1 → 4GlcNAc was linkedα1 → 2 orα1 → 6 to Man, the binding enthalpy and entropy remained practically constant. Application of stopped flow kinetics and pressure-jump relaxation withN-dansylgalactosamine gave mono-exponential signal changes with a concentration dependence corresponding tok ₊ = 4.8 x 10⁴ M^-1 s^-1 k _- = 0.4 to 0.66 s^-1 and a change in reaction volume of+7ml/mol.