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.     

The differential effects of the carcinogen dimethylnitrosamine on isocitrate and 6-phosphogluconate metabolism in single intact cells

A microspectrofluorimetric study is made of the influence of dimethylnitrosamine on NADP reduction, following sequential microinjections into the same L cell, of two substrates: (1) isocitrate, with activity of isocitrate dehydrogenase both in the extramitochondrial and intramitochondrial compartments, (2) 6-phosphogluconate, with activity of the dehydrogenase in the extramitochondrial compartment. In control L cells a two-step reduction of NAD(P) is obtained followed by relatively slow reoxidation. In the minutes which follow addition of carcinogen, e.g., dimethylnitrosamine, to the cell medium the isocitrate and 6-phosphogluconate-induced transient NADP reoxidation is decreased in magnitude compared to control, while the rate constant of NADPH reoxidation is considerably accelerated, possibly due to requirements at the level of the microsomal metabolizing system. Observations within the first hour of carcinogen addition suggest an interesting system for evaluating the immediate actions of carcinogens at extranuclear sites: i.e., a comparative study of NADP reduction-reoxidation rate constants via injection of substrates for extra- vs. intramitochondrial pathways.     

An unsupervised neural network model for the development of reflex co-ordination

In this paper, we present a model for the development of connections between muscle afferents and motoneurones in the human spinal cord. The model consists of a limb with six muscles, one motoneurone pool, one pooled (Ia-like) afferent for each muscle and a central programme generator. The weights of the connections between the afferents and the motoneurone pools are adapted during centrally induced movements of the limb. The connections between the afferents and the motoneurone pools adapt in a hebbian way, using only local information present at the synapses. This neural network is tested in two examples of a limb with two degrees of freedom and six muscles. Despite the simplifications, the model predicts the pattern of autogenic and heterogenic monosynaptic reflexes quite realistically.     

Complement Factor H-Related Protein 3 Serum Levels Are Low Compared to Factor H and Mainly Determined by Gene Copy Number Variation in CFHR3

The major human complement regulator in blood, complement factor H (FH), has several closely related proteins, called FH-related (FHR) proteins. As all FHRs lack relevant complement regulatory activity, their physiological role is not well understood. FHR protein 3 (FHR-3) has been suggested to compete with FH for binding to Neisseria meningitidis, thereby affecting complement-mediated clearance. Clearly, the in vivo outcome of such competition greatly depends on the FH and FHR-3 concentrations. While FH levels have been established, accurate FHR-3 levels were never unequivocally reported to date. Moreover, CFHR3 gene copy numbers commonly vary, which may impact the FHR-3 concentration. Hence, we generated five anti-FHR-3 mAbs to specifically measure FHR-3 in human healthy donors of which we determined the gene copy number variation at the CFH/CFHR locus. Finally, we examined the acute-phase response characteristics of FHR-3 in a small sepsis cohort. We determined FHR-3 levels to have a mean of 19 nM and that under normal conditions the copy number of CFHR3 correlates to a very large extent with the FHR-3 serum levels. On average, FHR-3 was 132-fold lower compared to the FH concentration in the same serum samples and FHR-3 did not behave as a major acute phase response protein.     

Acid proteases from the yolk and the yolk-sac of the hen's egg. Purification, properties and identification as cathepsin D

Two acid proteases from the yolk and one from the yolk-sac of the hen's egg were purified and characterized. They belong all three to the class of cathepsin D. Mostly, minor differences were found in their properties. Possible endogenous substrates, as some egg-proteins and some other yolk-enzymes, were hydrolysed with variable intensity, in vitro.     

Photoaffinity probes for serotonin and histamine receptors. Synthesis and characterization of two azide analogues of ketanserin

Two azide analogues of ketanserin (6- and 7-azido-3-[2- [4-(4-fluorobenzoyl)-1-piperidinyl]ethyl]-2, 4(1H,3H)-quinazolinedione) were synthesized and tested as possible photoaffinity probes for serotonin-S2 and histamine-H1 receptors. In reversible binding experiments, the azides showed high affinity for both receptor types. When membrane preparations were incubated with nanomolar concentrations of 7-azidoketanserin and subsequently irradiated with UV light, both serotonin and histamine receptors became irreversibly blocked. This irreversible binding was dependent on azide concentrations and time of irradiation and did not change in the presence of the scavenger p-aminobenzoic acid. In contrast, irreversible blockade at low concentrations of 6-azidoketanserin was only obtained for histamine receptors. However, this blockade was abolished by addition of the scavenger p-aminobenzoic acid indicating that it was not due to a real photoaffinity mechanism. In the rat prefrontal cortex, irreversible blocking of serotonin receptors with 7-azidoketanserin could be inhibited by serotonin agonists or antagonists but not by histaminergic compounds. On the contrary, in the guinea pig cerebellum, inactivation of histamine receptors could be inhibited by histamine antagonists and histamine itself but not by serotonergic compounds. This provides a way for differential photolabeling of either of these receptors.