Learning and anticipatory behaviour in a “sit-and-wait” predator: The Atlantic halibut

We studied the learning capacities and anticipatory behaviour in a “sit-and-wait” predatory fish, the Atlantic halibut, Hippoglossus hippoglossus. In Experiment 1 two groups of halibut received series of light flashes (conditioned stimulus, CS) that started before delivery of food (unconditioned stimulus, US) and persisted until after food delivery, i.e. delay conditioning. Control groups received unpaired CS and US presentations. The anticipatory behaviour of delay conditioned halibut consisted mainly of take-offs towards the surface shortly after onset of the CS. In Experiment 2 six groups of halibut were trained in three trace conditioning procedures: Two groups with 20 s, two groups with 60 s and two groups with 120 s trace interval. Learning was evident in the 20 and 60 s trace groups and in one of the 120 s trace groups. In contrast to delay conditioning the anticipatory behaviour of trace conditioned halibut was characterized by subtle movements near the tank floor with orientation towards the CS. The cautious responses of halibut after trace conditioning differed markedly from what is observed in other fish species and are suggested to reflect a “sit-and-wait” foraging strategy that requires the predator to remain undetected until the prey is within lunging range.     

Development and validation of ultrasound speckle tracking to quantify tendon displacement

Ultrasound can be used to study tendon movement. However, measurement of tendon movement is mostly based on manual tracking of anatomical landmarks such as the musculo-tendinous junction, limiting the applicability to a small number of muscle-tendon units. The aim of this study was to quantify tendon displacement without anatomical landmarks using a speckle tracking algorithm optimized for tendons in long B-mode image sequences. A dedicated two-dimensional multi-kernel block-matching scheme with subpixel motion estimation was devised to handle large displacements over long sequences. The accuracy of the tracking on porcine tendons was evaluated during different displacements and velocities. Subsequently, the accuracy of tracking the flexor digitorum superficialis (FDS) of a human cadaver hand was evaluated. Finally, the in-vivo accuracy of the tendon tracking was determined by measuring the movement of the FDS at the wrist level. For the porcine experiment and the human cadaver arm experiment tracking errors were, on average, 0.08 and 0.05 mm, respectively (1.3% and 1.0%). For the in-vivo experiment the tracking error was, on average, 0.3 mm (1.6%). This study demonstrated that our dedicated speckle tracking can quantify tendon displacement at different physiological velocities without anatomical landmarks with high accuracy. The technique allows tracking over large displacements and in a wider range of tendons than by using anatomical landmarks.     

BAC to the future! or oligonucleotides: a perspective for micro array comparative genomic hybridization (array CGH)

The array CGH technique (Array Comparative Genome Hybridization) has been developed to detect chromosomal copy number changes on a genome-wide and/or high-resolution scale. It is used in human genetics and oncology, with great promise for clinical application. Until recently primarily PCR amplified bacterial artificial chromosomes (BACs) or cDNAs have been spotted as elements on the array. The large-scale DNA isolations or PCR amplifications of the large-insert clones necessary for manufacturing the arrays are elaborate and time-consuming. Lack of a high-resolution highly sensitive (commercial) alternative has undoubtedly hindered the implementation of array CGH in research and diagnostics. Recently, synthetic oligonucleotides as arrayed elements have been introduced as an alternative substrate for array CGH, both by academic institutions as well as by commercial providers. Oligonucleotide libraries or ready-made arrays can be bought off-the-shelf saving considerable time and efforts. For RNA expression profiling, we have seen a gradual transition from in-house printed cDNA-based expression arrays to oligonucleotide arrays and we expect a similar transition for array CGH. This review compares the different platforms and will attempt to shine a light on the ‘BAC to the future’ of the array CGH technique.     

Coronary microvascular dysfunction in a porcine model of early atherosclerosis and diabetes

Detailed evaluation of coronary function early in diabetes mellitus (DM)-associated coronary artery disease (CAD) development is difficult in patients. Therefore, we investigated coronary conduit and small artery function in a preatherosclerotic DM porcine model with type 2 characteristics. Streptozotocin-induced DM pigs on a saturated fat/cholesterol (SFC) diet (SFC + DM) were compared with control pigs on SFC and standard (control) diets. SFC + DM pigs showed DM-associated metabolic alterations and early atherosclerosis development in the aorta. Endothelium-dependent vasodilation to bradykinin (BK), with or without blockade of nitric oxide (NO) synthase, endothelium-independent vasodilation to an exogenous NO-donor (S-nitroso-N-acetylpenicillamine), and vasoconstriction to endothelin (ET)-1 with blockade of receptor subtypes, were assessed in vitro. Small coronary arteries, but not conduit vessels, showed functional alterations including impaired BK-induced vasodilatation due to loss of NO (P < 0.01 vs. SFC and control) and reduced vasoconstriction to ET-1 (P < 0.01 vs. SFC and control), due to a decreased ET(A) receptor dominance. Other vasomotor responses were unaltered. In conclusion, this model demonstrates specific coronary microvascular alterations with regard to NO and ET-1 systems in the process of early atherosclerosis in DM. In particular, the altered ET-1 system correlated with hyperglycemia in atherogenic conditions, emphasizing the importance of this system in DM-associated CAD development.     

Dendritic position is a major determinant of presynaptic strength

Different regulatory principles influence synaptic coupling between neurons, including positional principles. In dendrites of pyramidal neurons, postsynaptic sensitivity depends on synapse location, with distal synapses having the highest gain. In this paper, we investigate whether similar rules exist for presynaptic terminals in mixed networks of pyramidal and dentate gyrus (DG) neurons. Unexpectedly, distal synapses had the lowest staining intensities for vesicular proteins vGlut, vGAT, Synaptotagmin, and VAMP and for many nonvesicular proteins, including Bassoon, Munc18, and Syntaxin. Concomitantly, distal synapses displayed less vesicle release upon stimulation. This dependence of presynaptic strength on dendritic position persisted after chronically blocking action potential firing and postsynaptic receptors but was markedly reduced on DG dendrites compared with pyramidal dendrites. These data reveal a novel rule, independent of neuronal activity, which regulates presynaptic strength according to dendritic position, with the strongest terminals closest to the soma. This gradient is opposite to postsynaptic gradients observed in pyramidal dendrites, and different cell types apply this rule to a different extent.     

Production of cyanophycin in <Emphasis Type="Italic">Rhizopus oryzae</Emphasis> through the expression of a cyanophycin synthetase encoding gene

Cyanophycin or cyanophycin granule peptide is a protein that results from non-ribosomal protein synthesis in microorganisms such as cyanobacteria. The amino acids in cyanophycin can be used as a feedstock in the production of a wide range of chemicals such as acrylonitrile, polyacrylic acid, 1,4-butanediamine, and urea. In this study, an auxotrophic mutant (Rhizopus oryzae M16) of the filamentous fungus R. oryzae 99-880 was selected to express cyanophycin synthetase encoding genes. These genes originated from Synechocystis sp. strain PCC6803, Anabaena sp. strain PCC7120, and a codon optimized version of latter gene. The genes were under control of the pyruvate decarboxylase promoter and terminator elements of R. oryzae. Transformants were generated by the biolistic transformation method. In only two transformants both expressing the cyanophycin synthetase encoding gene from Synechocystis sp. strain PCC6803 was a specific enzyme activity detected of 1.5 mU/mg protein. In one of these transformants was both water-soluble and insoluble cyanophycin detected. The water-soluble fraction formed the major fraction and accounted for 0.5% of the dry weight. The water-insoluble CGP was produced in trace amounts. The amino acid composition of the water-soluble form was determined and constitutes of equimolar amounts of arginine and aspartic acid.     

Novel ATP competitive MK2 inhibitors with potent biochemical and cell-based activity throughout the series

Optimization of our previously described pyrrolopiperidone series led to the identification of a new benzamide sub-series, which exhibits consistently high potency in biochemical and cell-based assays throughout the series. Strong inhibition of LPS-induced production of the cytokine TNFα is coupled to the regulation of HSP27 phosphorylation, indicating that the observed cellular effects result from the inhibition of MK2. X-ray crystallographic and computational analyses provide a rationale for the high potency of the series.     

Backbone and side chain NMR assignments for the intrinsically disordered cytoplasmic domain of human neuroligin-3

Neuroligins act as heterophilic adhesion molecules at neuronal synapses. Their cytoplasmic domains interact with synaptic scaffolding proteins, and have been shown to be intrinsically disordered. Here we report the backbone and side chain ¹H, ¹³C and ¹⁵N resonance assignments for the cytoplasmic domain of human neuroligin 3.     

Altruistic Punishment and Between-Group Competition

Collective action, or the large-scale cooperation in the pursuit of public goods, has been suggested to have evolved through cultural group selection. Previous research suggests that the costly punishment of group members who do not contribute to public goods plays an important role in the resolution of collective action dilemmas. If large-scale cooperation sustained by the punishment of defectors has evolved through the mechanism of cultural group selection, two implications regarding costly punishment follow: (1) that people are more willing to punish defecting group members in a situation of intergroup competition than in a single-group social dilemma game and (2) that levels of "perverse" punishment of cooperators are not affected by intergroup competition. We find confirmation for these hypotheses. However, we find that the effect of intergroup competition on the punishment of defectors is fully explained by the stronger conditionality of punishment on expected punishment levels in the competition condition.