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.     

A Systematic Approach towards Optimizing a Cohabitation Challenge Model for Infectious Pancreatic Necrosis Virus in Atlantic Salmon (Salmo salar L.)

A cohabitation challenge model was developed for use in evaluating the efficacy of vaccines developed against infectious pancreatic necrosis virus (IPNV) in Atlantic salmon (Salmo salar L) using a stepwise approach. The study involved identifying a set of input variables that were optimized before inclusion in the model. Input variables identified included the highly virulent Norwegian Sp strain NVI015-TA encoding the T₂₁₇A₂₂₁ motif having the ability to cause >90% mortality and a hazard risk ratio of 490.18 (p<0.000) for use as challenge virus. The challenge dose was estimated at 1x10⁷ TCID₅₀/mL per fish while the proportion of virus shedders was estimated at 12.5% of the total number of fish per tank. The model was designed based on a three parallel tank system in which the Cox hazard proportional regression model was used to estimate the minimum number of fish required to show significant differences between the vaccinated and control fish in each tank. All input variables were optimized to generate mortality >75% in the unvaccinated fish in order to attain a high discriminatory capacity (DC) between the vaccinated and control fish as a measure of vaccine efficacy. The model shows the importance of using highly susceptible fish to IPNV in the optimization of challenge models by showing that highly susceptible fish had a better DC of differentiating vaccine protected fish from the unvaccinated control fish than the less susceptible fish. Once all input variables were optimized, the model was tested for its reproducibility by generating similar results from three independent cohabitation challenge trials using the same input variables. Overall, data presented here show that the cohabitation challenge model developed in this study is reproducible and that it can reliably be used to evaluate the efficacy of vaccines developed against IPNV in Atlantic salmon. We envision that the approach used here will open new avenues for developing optimal challenge models for use in evaluating the efficacy of different vaccines used in aquaculture.     

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.     

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.     

Intramolecular base pairing between the nematode spliced leader and its 5'' splice site is not essential for trans-splicing in vitro.

The spliced leader RNAs of both trypanosomes and nematodes can form similar secondary structures where the trans-splice donor site is involved in intramolecular base pairing with the spliced leader sequence. It has been proposed that this base pairing could serve to activate autonomously the SL RNA splice donor site. Here, we have examined exon requirements for trans-splicing in a nematode cell free system. Complete disruption of secondary structure interactions at and around the trans-splice donor site did not affect the ability of the SL RNA to function in trans-splicing. In addition, the highly conserved 22 nt sequence could be productively replaced by artificial exons ranging in size from 2 to 246 nucleotides. These results reinforce the view that the 'intron' portion of the SL RNA functions as an independent Sm snRNP whose role is to deliver exon sequences to the trans-spliceosome.