Conflicting selection on the timing of germination in a natural population of Arabidopsis thaliana.

The timing of germination is a key life-history trait that may strongly influence plant fitness and that sets the stage for selection on traits expressed later in the life cycle. In seasonal environments, the period favourable for germination and the total length of the growing season are limited. The optimal timing of germination may therefore be governed by conflicting selection through survival and fecundity. We conducted a field experiment to examine the effects of timing of germination on survival, fecundity and overall fitness in a natural population of the annual herb Arabidopsis thaliana in north-central Sweden. Seedlings were transplanted at three different times in late summer and in autumn covering the period of seed germination in the study population. Early germination was associated with low seedling survival, but also with high survival and fecundity among established plants. The advantages of germinating early more than balanced the disadvantage and selection favoured early germination. The results suggest that low survival among early germinating seeds is the main force opposing the evolution of earlier germination and that the optimal timing of germination should vary in space and time as a function of the direction and strength of selection acting during different life-history stages.

Predictors of Cerebral Aneurysm Rupture after Coil Embolization: Single-Center Experience with Recanalized Aneurysms.

BACKGROUND AND PURPOSE: Recanalization after coil embolization is widely studied. However, there are limited data on how recanalized aneurysms rupture. Herein, we describe our experience with the rupture of recanalized aneurysms and discuss the type of recanalized aneurysms at greatest rupture risk. MATERIALS AND METHODS: A total of 426 unruptured aneurysms and 169 ruptured aneurysms underwent coil embolization in our institution between January 2009 and December 2017. Recanalization occurred in 38 (8.9%) of 426 unruptured aneurysms (unruptured group) and 37 (21.9%) of 169 ruptured aneurysms (ruptured group). The Modified Raymond-Roy classification on DSA was used to categorize the recanalization type. Follow-up DSA was scheduled until 6 months after treatment, and follow-up MRA was scheduled yearly. If recanalization was suspected on MRA, DSA was performed. RESULTS: In the unruptured group, the median follow-up term was 74.0 months. Retreatment for recanalization was performed in 18 aneurysms. Four of 20 untreated recanalized aneurysms (0.94% of total coiled aneurysms) ruptured. In untreated recanalized aneurysms, class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .025). In the ruptured group, the median follow-up term was 28.0 months. Retreatment for recanalization was performed in 16 aneurysms. Four of 21 untreated recanalized aneurysms (2.37% of total coiled aneurysms) ruptured. Class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .02). CONCLUSIONS: The types of recanalization after coil embolization may be predictors of rupture. Coiled aneurysms with class IIIb recanalization should undergo early retreatment because of an increased rupture risk.

Weak localization in bilayer graphene with Li-intercalation/desorption.

We performed in-situ electrical transport measurements for bilayer graphene grown on SiC(0 0 0 1) substrate, Li-intercalated bilayer graphene, and after that desorbing Li atoms by heating. Bilayer graphene after desorbing intercalated Li atoms showed a higher resistivity and different behavior in magnetoconductance compared to pristine bilayer graphene. We observed the weak localization of carriers at low temperatures in all the three samples and analyzed the experimental results with the extended Hikami-Larkin-Nagaoka equation to investigate the transport properties. The result shows that the magnetoconductance of pristine bilayer graphene is described by the AB stacking structure model and the phase breaking scattering is dominated by the electron-electron scattering. The intra-valley scattering occurs most frequently probably due to dopants in SiC substrate. However, in Li-desorbed graphene, the magnetoconductance can be described by neither AB nor AA-stacking model, suggesting the coexistence of domains with several different stacking structures.

Identification of quantitative trait loci affecting shank length, body weight and carcass weight from the Japanese cockfighting chicken breed, Oh-Shamo (Japanese Large Game).

We performed a quantitative trait locus (QTL) analysis to map QTLs controlling shank length, body weight, and carcass weight in a resource family of 245 F(2) birds developed from a cross of the large-sized, native, Japanese cockfighting breed, Oh-Shamo (Japanese Large Game), and the White Leghorn breed of chickens. Interval mapping revealed three significant QTLs for shank length on chromosomes 1, 4 and 24 at the experiment-wise 5% level, and a suggestive shank length QTL on chromosome 27 at the experiment-wise 10% level. For body weight two QTLs, one significant and the other suggestive, were identified on chromosomes 4 and 24, respectively. As expected, QTLs for carcass weight, which was highly correlated with body weight (r = 0.95), were detected at the same chromosomal locations as the detected body weight QTLs. Interestingly, the chromosomal locations containing these body weight and carcass weight QTLs coincided with those of two of the four shank length QTLs detected. No QTL with an epistatic interaction effect was discovered for any trait. The total contribution of all detected QTLs to genetic variance was 98.4%, 27.0% and 25.9% for shank length, body weight and carcass weight, respectively, indicating that most shank length QTLs have been identified but many body weight and carcass weight QTLs have been overlooked by the present analysis because of a low coverage rate of the 88 microsatellite markers used here (approximately 46% of the whole genome).

Effect of fluorescein on the electrical potential difference across isolated rabbit corneal endothelium.

The authors investigated whether fluorescein sodium affects the in vitro endothelial function of rabbit corneas. As an index of this function, the transendothelial electrical potential difference (TEPD) was used. The TEPD in a balanced salts and glucose (BSG) control solution increased for the first 30 min and then decayed slowly, reaching about 60% of its original value after 5 hr. When a BSG solution containing 5 micrograms/ml of fluorescein sodium was used, the TEPD time course was similar to the control solution. Since this fluorescein sodium concentration is about sevenfold higher than that seen in the anterior chamber of ocular patients, these results reassure users that no toxic effect of fluorescein is discernible at concentrations relevant to ophthalmic practice. With a fluorescein sodium concentration of 500 micrograms/ml, the TEPD decreased below control values after 4 hr of exposure, but such a concentration is approximately 5000-fold higher than that seen in the anterior chamber of patients. The adverse effect of fluorescein on TEPD is probably irrelevant for standard systemic clinical use.

Catalytic asymmetric dihydroxylation using phenoxyethoxymethyl-polystyrene (PEM)-based novel microencapsulated osmium tetroxide (PEM-MC OsO4).

[reaction: see text]. A phenoxyethoxymethyl-polystyrene (PEM)-based novel polymer-supported osmium catalyst has been developed. The catalyst was readily prepared from PEM polymer based on a microencapsulation technique, and asymmetric dihydroxylation of olefins has been successfully performed using (DHQD)2PHAL as a chiral ligand and K3Fe(CN)6 as a cooxidant in H2O/acetone. The catalyst was recovered quantitatively by simple filtration and reused without loss of activity several times.

Observation of triply charged metal ion clusters by electrospray and laser spray

Studies of the gas phase ion chemistry of triply charged metal ions, M(3+) = Sc(3+), Y(3+), La(3+), Ce(3+), and Yb(3+), were made by electrospray and laser spray. Triply charged ion ligand complexes, M(3+)(ligand)(n) were produced in the gas phase by electrospray and laser spray for the following ligands; glucose; sucrose; raffinose; cyclodextrin; ginsenoside Rb(1); dimethyl sulfoxide (DMSO) and hexamethylphosphoramide (HMPA). The ion evaporation mechanism must be invoked to explain the transfer of more surface active ions (e.g., NH(4)(+)(H(2)O)(n)) in solution to the gas phase, while the transfer of low surface active ions (e.g., La(3+)(sucrose)(n)) may be explained by the charged residue model. In general, the laser spray gives stronger ion signals than electrospray for aqueous and water/methanol solutions. The laser spray is found to be more suitable for the observation of ions with larger solvation energies (e.g., Sc(3+)(DMSO)(n)). These results may be due to the enrichment of the sample concentration by the selective vaporization of the volatile solvent on the tip of the stainless steel capillary and also to the finer droplet formation caused by the laser irradiation. Copyright 1999 John Wiley & Sons, Ltd.

Meiotic contraction of CAG repeats in Saccharomyces cerevisiae.

Several human neurodegenerative disorders are caused by expansion of CAG repeats that occurs during meiosis or gametogenesis. We anticipated that the CAG repeats cloned in a plasmid of Saccharomyces cerevisiae might undergo a change in the number of repeats during meiosis and sporulation. To test this possibility, we devised a new method to change in vitro the number of CAG repeats and constructed plasmids carrying (CAG)39, (CAG)65 or (CAG)123 from a plasmid carrying (CAG)18. We monitored the number of colonies showing an altered length of the repeat tracts during mitosis and meiotic growth. Contraction of long CAG repeat was found to occur frequently, whereas a few cases of expansion were observed. The contraction was equally enhanced in both orientations when the host cells grew through meiosis. Thus, our results suggest that long CAG repeats are destabilized during meiosis or gametogenesis in S. cerevisiae.

Effects of BSS and BSS+ irrigation solutions on rabbit corneal transendothelial electrical potential difference.

Measurements of electrical potential difference across isolated rabbit corneal endothelium (transendothelial electrical potential difference, TEPD) were used to evaluate the effect of two commonly used commercially prepared intraocular irrigation balanced salt solutions, BSS and BSS+, together with our own standard bicarbonate-containing control solution (BS). The highest and most durable TEPD values were obtained by using BSS+; TEPD began at 550 microV, peaked at 600 microV 1 h later, and then decreased slowly down to some 300 microV after about 8 h. Gassing BSS+ with an air/5% CO2 mixture was optimal; gassing it with air reduced the TEPD values slightly, by about 10%. On the other hand, perfusion with BSS gassed with air had a rapid and marked adverse effect; the TEPD, which began at some 500 microV, fell down precipitously to about 50 microV after 1 hour. In contrast, perfusion with BSS on the endothelial side with the addition of BS to the stromal side, both sides being gassed with an air/5% CO2 mixture, maintained the TEPD at levels near those obtained with BSS+. We attribute the adverse effect by BSS to the absence of bicarbonate in it. From these and past results, we conclude that BSS cannot be recommended for intraocular use as a properly balanced saline solution.

Non-invasive determination of instantaneous heart rate in developing avian embryos by means of acoustocardiogram.

Previous noninvasive studies of the mean heart rate of embryonic birds have prompted an investigation into the instantaneous heart rate (IHR), which may be informative in developmental studies of cardiac rhythm. Using the acoustocardiogram (ACG), a noninvasive, long-term measuring system for embryonic IHR is developed, and the IHR in chickens during the last half of embryonic development is determined. The system, which uses a micro-computer, samples the ACG at a frequency of 50 Hz, restores the ACG wave by sinc function and calculates the IHR with an error in accuracy of less than 1 beat min-1. It was found that characteristic, transient bradycardia begins to appear late in the second week of incubation, and, with the additional development of transient tachycardia, the embryonic cardiac rhythm becomes more arrhythmic towards hatching. Simultaneous measurements of IHR with somatic movements showed no relationship between arrhythmia and embryonic activities. This system is useful, providing new evidence on long-term IHR developmental patterns.

Ballistocardiogram of avian eggs determined by an electromagnetic induction coil.

As an avian embryo grows within an eggshell, the whole egg is moved by embryonic activity and also by the embryonic heartbeat. A technical interest in detecting minute biological movements has prompted the development of techniques and systems to measure the cardiogenic ballistic movement of the egg or ballistocardiogram (BCG). In this context, there is interest in using an electromagnetic induction coil (solenoid) as another simple sensor to measure the BCG and examining its possibility for BCG measurement. A small permanent magnet is attached tightly to the surface of an incubated egg, and then the egg with the magnet is placed in a solenoid. Preliminary model analysis is made to design a setup of the egg, magnet and solenoid coupling system. Then, simultaneous measurement with a laser displacement measuring system, developed previously, is made for chicken eggs, indicating that the solenoid detects the minute cardiogenic ballistic movements and that the BCG determined is a measure of the velocity of egg movements.

Polymer-supported glyoxylate and alpha-imino acetates. Versatile reagents for the synthesis of alpha-hydroxycarboxylic acid and alpha-amino acid libraries.

Polymer-supported glyoxylate.monohydrate (3) and alpha-imino acetates (7) have been readily prepared from chloromethylated resin via two or three steps. The ene reactions of 3 with alkenes were successfully performed in the presence of Yb(OTf)3 (50 mol %) to afford, after cleavage from the polymer support, the corresponding alpha-hydroxycarboxylic acid esters in good yields. The reactions of 7 with silyl enolates, Danishefsky's diene, and alkenes also proceeded smoothly in the presence of Sc(OTf)3 (20 mol %) to give the corresponding alpha-amino acid, pyridone, and tetrahydroquinoline derivatives, respectively, in good yields.

Dynamical systems analysis of arterial blood pressure signals in relation to heart rate fluctuations in chick embryos.

We attempted a new approach based on a modern dynamical system theory to reconstruct the arterial blood pressure signals in relation to heart rate fluctuations of developing chick embryos. The dynamical systems approach in general is to model a phenomenon that is presented by a single time series record and approximate the dynamical property (e.g. heart rate fluctuations) of a system based only on information contained in a single-variable (arterial blood pressure) of the system. The time-series data of the arterial blood pressure was reconstructed in 3-dimensional space to draw characteristic orbits. Since the reconstructed orbits of the blood pressure should retain information contained in the pressure signals, we attempted to derive instantaneous heart rate (IHR) from the reconstructed orbits. The derived IHR presenting HR fluctuations coincided well with the IHR obtained conventionally from the peak-to-peak time intervals of the maximum blood pressure. Movements of the reconstructed orbits of the arterial blood pressure in 3-dimensional space reflected HR fluctuations (i.e. transient decelerations and accelerations).

Time scales for structural formation in an electrorheological suspension probed by optical and electrical responses

Responses of the diffuse transmitted light intensity and the current passing through an electrorheological suspension to the stepwise electric field were measured in the quiescent state, and the time scales for the structural formation of the polarized particles were reported. It was found experimentally that both of the responses consist of plural modes, the faster and slower modes even in the quiescent state. The optical response was also expressed as an exponential function with two modes, which take place in succession.

Molecular weight distribution and the electrorheological response for anisotropic solutions of poly(gamma-benzyl-L-glutamate) induced by the convection of the electrohydrodynamic instability.

Transient responses of stress to a sinusoidal electric field were reported for anisotropic solutions of poly(gamma-benzyl-L-glutamate)s (PBLG's) with different distributions of the molecular weight. The transient stress, which was induced by the convection of the electrohydrodynamic instability, showed a steep and large increase when it was plotted against the instantaneous amplitude of the electric field. The maximum stress of a PBLG solution tended to increase with an increase in the maximum molecular weight of the PBLG in the molecular weight distribution.

Heart rate responses to altered ambient oxygen in early (days 3-9) chick embryos in the intact egg.

Normal heart rate (HR), and the HR responses to hypoxia and hyperoxia during early heart development in chick embyros have not been studied in detail, particularly in undisturbed embryos within the intact egg. HR was measured in day 3-9 chick embryos at 38 degrees C using relatively noninvasive impedance cardiography. Embryos were exposed to air (control) and to hypoxic (10% O2) or hyperoxic (100% O2) gas for a 2-h or 4-h period, during which HR was continually monitored. Control (normoxic) HR increased from about 150 beats per min (bpm) on day 3 to about 240 bpm on days 7-9. HR in very early embryos showed a variety of moderate responses to hypoxia (all survived), but as development progressed beyond day 6, hypoxic exposure induced a profound bradycardia that frequently terminated in death before the end of the measurement period. In contrast to the marked developmental changes in hypoxic sensitivity, HR showed little response to hyperoxia throughout development, suggesting no "hypoxic drive" to HR. We speculate that hypoxia has little effect early in development because of the embryo's small absolute O2 demand, but as the embryo grows, hypoxia represents a progressively more severe perturbation. Although general trends were identified, there was considerable variation in both HR and HR responses to ambient O2 changes between individuals of the same developmental stage.