Effect of access to a running wheel on behavior of C57BL/6J mice.

BACKGROUND AND PURPOSE: To evaluate how and when mice run on a running wheel and how ad libitum access to the wheel affect behavior, feed intake, and weight gain. METHODS: Seventeen 2-month-old C57BL/6J mice had access to the wheel, whereas 19 control mice did not. After 3 to 6.5 weeks, behavior was video-recorded over 24 h for each mouse. RESULTS: Experimental mice ran an average 2 km/24 h in 114 min. Highest running activity took place at the onset of darkness. Experimental mice spent 22 min more feeding on the cage floor than did control mice. These times were deducted from those for all other behaviors: 74 min from resting time, 39 min from climbing and feeding on the cage lid, 14 min from locomotion on the cage floor, and 10 min from grooming. In relative figures, deduction from sleeping time was only 9%, whereas climbing time was halved. CONCLUSIONS: Climbing on the cage lid has a similar circadian rhythm as does wheel running and high-energy expenditure. Because experimental mice climbed less, their weight gain and feed intake were similar to those of control mice. Thus, wheel running can substitute for other forms of energy-consuming behaviors and vice versa.     

Robo4 stabilizes the vascular network by inhibiting pathologic angiogenesis and endothelial hyperpermeability

The angiogenic sprout has been compared to the growing axon, and indeed, many proteins direct pathfinding by both structures. The Roundabout (Robo) proteins are guidance receptors with well-established functions in the nervous system; however, their role in the mammalian vasculature remains ill defined. Here we show that an endothelial-specific Robo, Robo4, maintains vascular integrity. Activation of Robo4 by Slit2 inhibits vascular endothelial growth factor (VEGF)-165-induced migration, tube formation and permeability in vitro and VEGF-165-stimulated vascular leak in vivo by blocking Src family kinase activation. In mouse models of retinal and choroidal vascular disease, Slit2 inhibited angiogenesis and vascular leak, whereas deletion of Robo4 enhanced these pathologic processes. Our results define a previously unknown function for Robo receptors in stabilizing the vasculature and suggest that activating Robo4 may have broad therapeutic application in diseases characterized by excessive angiogenesis and/or vascular leak.     

Reliability of egg morphology to detect conspecific brood parasitism in goldeneyes Bucephala clangula examined using protein fingerprinting

Eadie (1989) developed a method based on variation between females in egg length, width and weight to detect conspecific brood parasitism in the field: using these three egg measures, Euclidean distance between all pairs of eggs within a clutch is calculated, and if maximum Euclidean distance (MED) between any two eggs exceeds a threshold value the nest is considered parasitized. The MED method has been tested in Finnish and Scottish common goldeneye Bucephala clangula populations but the results have been contradicting. Here we use protein fingerprinting to assess the validity of the MED method. Data comprised 35 clutches of which we knew, based on protein fingerprinting, how many different females laid the clutch (range 1–5 females). The mean MED of non-parasitized clutches (laid by 1 female only) was 1.470 (95% CI: lower 1.169, upper 1.771; n=21) and that of parasitized clutches (laid by 2 or more females) was 3.654 (95% CL: lower 3.083, upper 4.225; n=14). Using a MED>3.0 as a criterion to identify parasitized clutches 89% of all clutches were classified correctly either parasitized or non-parasitized when compared to the identification based on protein fingerprinting. Clutch size and the number of females (beyond 2 females) did not affect the clutch MED, whereas the status of parasitism did. Repeatability of egg length, width and weight were: 0.63, 0.76 and 0.80, respectively, implying that, variation in these egg measures occurs among rather than within females. Our new results confirm that the MED method is reliable enough to detect parasitism in common goldeneye.     

Inoculation of selenium hyperaccumulator Stanleya pinnata and related non‐accumulator Stanleya elata with hyperaccumulator rhizosphere fungi—investigation of effects on Se accumulation and speciation

Little is known about how fungi affect elemental accumulation in hyperaccumulators (HAs). Here, two rhizosphere fungi from selenium (Se) HA Stanleya pinnata, Alternaria seleniiphila (A1) and Aspergillus leporis (AS117), were used to inoculate S. pinnata and related non‐HA Stanleya elata. Growth and Se and sulfur (S) accumulation were analyzed. Furthermore, X‐ray microprobe analysis was used to investigate elemental distribution and speciation. Growth of S. pinnata was not affected by inoculation or by Se. Stanleya elata growth was negatively affected by AS117 and by Se, but combination of both did not reduce growth. Selenium translocation was reduced in inoculated S. pinnata, and inoculation reduced S translocation in both species. Root Se distribution and speciation were not affected by inoculation in either species; both species accumulated mainly (90%) organic Se. Sulfur, in contrast, was present equally in organic and inorganic forms in S. pinnata roots. Thus, these rhizosphere fungi can affect growth and Se and/or S accumulation, depending on host species. They generally enhanced root accumulation and reduced translocation. These effects cannot be attributed to altered plant Se speciation but may involve altered rhizosphere speciation, as these fungi are known to produce elemental Se. Reduced Se translocation may be useful in applications where toxicity to herbivores and movement of Se into the food chain is a concern. The finding that fungal inoculation can enhance root Se accumulation may be useful in Se biofortification or phytoremediation using root crop species.     

Modelling the transition from simple to complex Ca2+oscillations in pancreatic acinar cells

A mathematical model is proposed which systematically investigates complex calcium oscillations in pancreatic acinar cells. This model is based on calcium-induced calcium release via inositol trisphosphate receptors (IPR) and ryanodine receptors (RyR) and includes calcium modulation of inositol (1,4,5) trisphosphate (IP₃) levels through feedback regulation of degradation and production. In our model, the apical and the basal regions are separated by a region containing mitochondria, which is capable of restricting Ca²⁺ responses to the apical region. We were able to reproduce the observed oscillatory patterns, from baseline spikes to sinusoidal oscillations. The model predicts that calcium-dependent production and degradation of IP₃ is a key mechanism for complex calcium oscillations in pancreatic acinar cells. A partial bifurcation analysis is performed which explores the dynamic behaviour of the model in both apical and basal regions.     

Regeneration in the auditory system of nymphal and adult bush crickets Tettigonia viridissima

Regeneration and reestablishment of synaptic connections is an important topic in neurobiological research. In the present study, the regeneration of auditory afferents and the accompanying effects in the central nervous system are investigated in nymphs and adults of the bush cricket Tettigonia viridissima L. (Orthoptera: Tettigoniidae). In all animals in which the tympanal nerve is crushed, neuronal tracing shows a regrowth of the afferents into the prothoracic ganglion. This regeneration is seen in both adult and nymphal stages and starts 10–15 days after nerve crushing. Physiological recordings from the leg nerve indicate a recovery of tympanal fibres and a formation of functional connections to interneurones in the same time range. Electrophysiological recordings from the neck connective suggest additional contralateral sprouting of interneurones and the formation of aberrant connections. The regeneration processes of the tympanal nerve in nymphal stages and adults appear to be similar.     

Changes of the proteinase binding properties and conformation of bovine alpha 2-macroglobulin on cleavage of the thio ester bonds by methylamine

Cleavage of the thio ester bonds of human alpha2-macroglobulin (alpha 2M) by methylamine leads to an extensive conformational change and to inactivation of the inhibitor. In contrast, cleavage of these bonds in bovine alpha 2M only minimally perturbs the hydrodynamic volume of the protein [Dangott, L. J., & Cunningham, L. W. (1982) Biochem. Biophys. Res. Commun. 107, 1243-1251], as well as its spectroscopic properties, as analyzed by ultraviolet difference spectroscopy, circular dichroism, and fluorescence in this work. A conformational change analogous to that undergone by human alpha 2M thus does not occur in the bovine inhibitor. However, changes of several functional properties of bovine alpha 2M are induced by the amine. The apparent stoichiometry of inhibition of trypsin thus is reduced from about 1.2 to about 0.7 mol of enzyme/mol of inhibitor. In spite of this decrease, the interaction with the proteinase induces similar conformational changes in methylamine-treated alpha 2M as in intact alpha 2M, as revealed by spectroscopic analyses, indicating that the mode of binding of the proteinase to the inhibitor is essentially unperturbed by thio ester bond cleavage. The reaction with methylamine also greatly increases the sensitivity of bovine alpha 2M to proteolysis by trypsin at sites other than the "bait" region. Moreover, the second-order rate constant for the reaction with thrombin is reduced by about 10-fold. These results indicate that the thio ester bonds of bovine alpha 2M, although not required per se for the binding of proteinases, nevertheless are responsible for maintaining certain structural features of the inhibitor that are of importance for full activity.     

Effect of head-group structure and counterion condensation on phase equilibria in anionic phospholipid-water systems studied by 2H, 23Na, and 31P NMR and X-ray diffraction

The phase equilibria, hydration, and sodium counterion association for the systems DOPA-2H2O, DOPS-2H2O, DOPG-2H2O, and DPG-2H2O were investigated with 2H, 23Na, and 31P NMR and X-ray diffraction. The following one-phase regions were found in the DOPA-water system: a reversed hexagonal liquid-crystalline (HII) phase up to about 35 wt % water and a lamellar liquid-crystalline (L alpha) phase between about 55 and 98 wt % water. The area per DOPA molecule was 36-65 A2 in the HII phase (10-40 wt % water) and 69 A2 in the L alpha phase (60 wt % water). DOPS and DOPG with 10-98 wt % water, and DPG with 20-95 wt % water formed an L alpha phase at temperatures between 25 and 55 degrees C. At temperatures above 55 degrees C, DPG with 20 and 30 wt % water formed a mixture of L alpha, HII, and cubic liquid-crystalline phases, the mole percent of lipid forming nonlamellar phases being smaller at 30 wt % water than at 20 wt % water. DPG with 10 wt % water probably formed a mixture of an L alpha phase and at least one nonlamellar liquid-crystalline phase at 25 and 35 degrees C, and a pure HII phase at 45 degrees C and higher temperatures. At water concentrations above about 50 wt % the 23Na quadrupole splitting was constant for all four lipid-water systems studied, implying that the counterion association to the charged lipid aggregates did not change upon dilution. These experimental observations can be described with an ion condensation model but not with a simple equilibrium model. The fraction of counterions located close to the lipid-water interface was calculated to be greater than 95%. The 2H and 23Na NMR quadrupole splittings of 2H2O and sodium counterions, respectively, indicate that the molecular order in the polar head-group region decreases for the L alpha phase in the order DOPA approximately DPG greater than DOPS greater than DOPG.     

Leukotrienes and myometrial activity of the term pregnant uterus

Biopsies from different segments of the pregnant human uterus were superfused in organ chambers and contractile activity was registered. Leukotriene C₄(LTC₄) caused inhibition of spontaneous but not noradrenaline induced contractile activity in strips from the cervix. This effect occured both in early pregnancy and at term. However, the lower and the upper uterine segment of the term pregnant uterus did not respond to LTC₄. The results represent a documentation of the segmental differentiation in the uterine response to eicosanoids.