Immobility reactions in socially behaving rabbits: Relation to hippocampal electrical activity

The presence of an intruder conspecific of the same sex caused a series of conflict reactions in rabbits living in a semi-natural environment. In some animals, defensive responses were predominant and two immobility reactions were observed. One consisted of freezing when the intruder was exploring at a distance; the other consisted of subdued posture in close contact with the intruder. Hippocampal EEG, recorded by telemetry, showed two different profiles. During freezing, rhythmic slow activity prevailed and during subdued posture an irregular pattern was predominant. Frequency increased when the intruder was in close contact with the resident. Aspects such as distance or behaviour of the intruder were found to affect both behavioural strategies and hippocampal electrical responses.     

Reactivity and event-related potentials during attentional tests in athletes

A series of attentional tests involving reaction times (RTs) was administered to 12 high-level young (age 17-18 years) volleyball players. During the tests, event-related potentials were recorded by electroencephalogram. In a simple reaction-time test (SRT), the subjects had to respond to a letter that appeared on a white screen. Other tests (attentional shifting tests) consisted of a go/no-go reaction time and a choice reaction time (CRT), divided into a short-latency CRT and a long-latency CRT. In the pre-stimulus period of these tests, there is a shift from broad attention to selective attention, represented by a crowding of black points on the computer screen, followed by the appearance of a letter in the centre of the crowding. The results show that RT increased from SRT to CRT. In the attentional shifting tests, averaged waves of event-related potentials showed a contingent-negative-variation-like wave that was closely related to selective attention (selective attention wave, SAW) before the onset of the stimulus. After the stimulus, a P3 complex was recorded. Correlations were found between the SAW amplitude and P3 latency and amplitude, and between these parameters and RT and its variability. Higher SAW and P3 amplitudes were accompanied by a shorter RT and a lower variability. The characteristics and the correlations that exist between the various parameters are consistent with a possible use of these tests in the analysis of the attentional styles of athletes, and in the evaluation of their progress with training.     

A Method for Marking the Position of Nichrome Microelectrode Tips in Nervous Tissue

A method for revealing nickel deposits from nichrome microelectrodes in the mammalian central nervous system is described. These deposits are stained red by dimethylglyoxime and can be observed directly or in Nissl stained sections. This method allows one to identify the exact position of a nichrome electrode in a microelectrode bundle chronically implanted in the brain.     

Molecular structure,solution chemistry and biological properties of the novel [ImH][trans-IrCl(4)(Im)(DMSO)], (I) and of the orange form of [(DMSO)(2)H][trans-IrCl(4)(DMSO)(2)], (II), complexes

The new iridium(III) complex, imidazolium[trans(DMSO,imidazole)tetrachloroiridate(III)], (I) (DMSO=dimethyl sulfoxide), and the orange form of [(DMSO)(2)H][trans(DMSO)(2)tetrachloroiridate(III)], (II) have been prepared and characterized, both in the solid state and in solution, by X-ray diffraction and by various physicochemical techniques. Single crystal X-ray diffraction studies point out that complex (II) is isomorphous to the ruthenium(III) analogue, [(DMSO)(2)H][trans-RuCl(4)(DMSO)(2)], (III). Crystallographic data are the following: a=16.028(2) A, b=24.699(3) A, c=8.262(1) A, in space group Pbca (Z=8) for (imidazolium)[trans(DMSO,imidazole)tetrachloroiridate(III)], (I); and a=9.189(2) A, b=16.511(4) A, c=14.028(3) A, beta=100.82(2) degrees in space group P2/n (Z=4) for [(DMSO)(2)H][trans(DMSO)(2)tetrachloroiridate(III)], (II). Visible absorption spectra show that both complexes are stable for several days, at pH 7.4, at room temperature. No significant chloride hydrolysis is observed, even at high temperature (70 degrees C), over 24 h. The extreme stability of these iridium(III) complexes within a physiological buffer was further assessed by (1)H NMR; in addition, cyclic voltammetry measurements evidenced a high stability of the oxidation state +3. Preliminary biological studies show that both complexes do not bind appreciably bovine serum albumin nor inhibit significantly the proliferation of representative human tumor cell lines, suggesting that hydrolysis of coordinated chlorides is a crucial feature for the biological properties and the antitumor activity of the parent ruthenium(III) complexes.     

Reduction of menin expression enhances cell proliferation and is tumorigenic in intestinal epithelial cells

Menin, the product of the tumor suppressor gene MEN1, is widely expressed in mammalian endocrine and non-endocrine tissues, including intestine. Its known abundant expression in several types of cells with high proliferative capacity led us to investigate the physiological function of the protein menin in intestinal epithelium, one of the most rapidly growing epithelia. Here we showed that the Men1 gene is mainly expressed in the crypt compartment of the proximal small intestine and that its expression was increased during fasting in vivo, both suggesting a role of menin in the control of cell growth. Indeed, specific reduction of menin expression by transfected antisense cDNA in the rat duodenal crypt-like cell line, IEC-17, increased cell proliferation. The latter is correlated to a loss of cell-cycle arrest in G(1) phase by resting cells and an overexpression of cyclin D1 and cyclin-dependent kinase (Cdk)-4. Furthermore, these cells lost the inhibition of proliferation induced by transforming growth factor-beta1, associated with a decrease of transforming growth factor-beta type II receptor expression. As a result of deregulated proliferation, antisense menin transfected IEC-17 cells became tumorigenic as shown in vitro as well as in vivo in immunosuppressed animals. These results indicate that menin contributes to proliferation control in intestinal epithelial cells. The present study reveals an unknown physiological function for menin in intestine that may be important in the regulation of epithelial homeostasis.     

Sugars Communicate through Water: Oriented Glycans Induce Water Structuring

Cells are coated with a glycocalyx—a layer of carbohydrate-containing biomolecules, such as glycoproteins. Although the structure and orientation of the cell-surface glycans are frequently regarded as being random, we have found, using α-1-acid glycoprotein and antitrypsin as model systems for surface glycans, that this is not the case. A glycoprotein monolayer was adsorbed onto hydrophilic and hydrophobic substrates. Surface-force measurements revealed that the orientation of the glycans with respect to the aqueous solution has a profound effect on the structure of vicinal water. The glycan antennae of the surface-adsorbed glycoproteins apparently impose an ordering on the water, resulting in a strong repulsive force over some tens of nanometers with superposed film-thickness transitions ranging from ≈0.7 to 1.8 nm. When the glycan orientation is modified by chemical means, this long-range repulsion disappears. These results may provide an explanation as to why the multiantennary structure is ubiquitous in glycoproteins. Although direct, specific interactions between glycans and other biomolecules are essential for their functionality, these results indicate that glycans’ long-range structuring of water may also influence their ability to interact with biomolecules in their vicinity.     

Emotional behavior in female rabbits: hippocampal EEG and neuroendocrine aspects.

Behavior, hippocampal electrical activity, plasma hormones and hippocampal choline acetyltransferase (ChAT) were considered in two groups of female rabbits, different in age and condition of breeding, both in the presence and absence of emotional stimuli. In the two groups of female rabbits (4 and 18 months old), permanent electrodes were implanted bilaterally in the two dorsal hippocampi and, one week later, the animals were exposed for three consecutive days to the following tests: Day 1, novel environment (NE); Day 2, object with odor (O); Day 3, sparrow hawk (SP). Behavior: in comparison with Day 1, exploration was decreased by the object and by the sparrow hawk in the older females and increased in the younger ones. Quiet and alert immobility was higher during the SP test, while freezing and pointing were lower in the older females than in the young ones. Electrical activity: peak frequency was lower in younger females than in the older ones. The frequency band distribution corresponding to exploration and immobility showed that in the older females the % of high frequency band increased from the first to the third day of testing, while an opposite trend was present in the younger females. In the case of freezing the hippocampal electric activity showed a more rhythmical component in younger females than in the older ones. Hormones: increased corticosterone levels after the SP test were directly correlated with exploration and inversely correlated with freezing. Dorsal hippocampal ChAT was directly correlated with quiet immobility. These data indicate a relationship between the responses to the anxious/fearful stimuli and the age and/or breeding experience of the female rabbits; this is shown by both the hippocampal electrical activity and the behavioral differences between the two groups.     

Fecal Concentrations of Cortisol,Testosterone, and Progesterone in Cotton-Top Tamarins Housed in Different Zoological Parks: Relationships Among Physiological Data,Environmental Conditions,and Behavioral Patterns

The aim of this investigation was to study the welfare of 3 captive groups of cotton-top tamarins housed in different zoological parks. Ethological observations were conducted during 1 year. In addition, fecal samples were collected and the concentrations of glucocorticoids, androgens, and progestogens were measured. Within each group, no significant differences in fecal cortisol concentrations were found between subjects. The fecal concentrations of testosterone and progesterone significantly differed depending on the sexes and ages of the tamarins. A significant association was found among hormone concentrations, exhibit dimensions, and group composition. A highly significant correlation was found between all hormones considered and the space available for each subject. Significant differences in behavioral patterns were observed among groups, including social–individual, affiliative–aggressive, and anogenital–suprapubic scent marking. Correlations between hormone measurements and behaviors were detected. In conclusion, this study confirmed the associations between some behaviors exhibited by these nonhuman primates and both cortisol and testosterone; these data also highlight the role played by progesterone in these behaviors.