Secondary Nuclei Research Articles

Role of CNS α1-adrenoceptor activity in central fos responses to novelty

The present study investigated, by use of fos immunohistochemistry, whether the functional activity of alpha(1)-adrenoceptors is elevated during heightened behavioral activity in brain regions shown earlier to contain motoric alpha(1)-receptors. In confirmation, marked c-fos responses that were blocked by an alpha(1)-antagonist (prazosin) were found in four of these brain regions (secondary motor, cingulate, piriform cortices, and nucleus accumbens) of animals exposed to a mildly novel environment (clean cage), which elicits a high degree of sustained exploratory activity. Experimental restriction of exploratory activity in the novel cage by a small enclosure did not reduce the fos responses in these areas, and in fact, enhanced gene expression when carried out in home-caged animals suggesting that the fos response may be more closely associated with the motivation to be active rather than activity itself. Experiments with locally administered alpha(1)-agonists and antagonists in the cortex by reverse dialysis showed that the above mentioned alpha(1)-dependent-fos responses were the result of activation of local alpha(1)-receptors in these brain regions. Unlike the aforementioned brain regions, the fos response of the locus coeruleus was not blocked by prazosin, and this nucleus also showed a marked fos increase to prazosin itself possibly as a compensatory response to the blockade of forebrain alpha(1)-receptors.

Calretinin immunoreactivity in the brain of the zebrafish, Danio rerio: Distribution and comparison with some neuropeptides and neurotransmitter‐synthesizing enzymes. II. Midbrain, hindbrain, and rostral spinal cord

The distribution of calretinin (CR) in the brainstem and rostral spinal cord of the adult zebrafish was studied by using immunocytochemical techniques. For analysis of some brainstem nuclei and regions, CR distribution was compared with that of complementary markers (choline acetyltransferase, glutamic acid decarboxylase, tyrosine hydroxylase, neuropeptide Y). The results reveal that CR is a marker of various neuronal populations distributed throughout the brainstem, including numerous cells in the optic tectum, torus semicircularis, secondary gustatory nucleus, reticular formation, somatomotor column, gustatory lobes, octavolateral area, and inferior olive, as well as of characteristic tracts of fibers and neuropil. These results indicate that CR may prove useful for characterizing a number of neuronal subpopulations in zebrafish. Comparison of the distribution of CR observed in the brainstem of zebrafish with that reported in an advanced teleost (the gray mullet) revealed a number of similarities, and also some interesting differences. Our results indicate that many brainstem neuronal populations have maintained the CR phenotype in widely divergent teleost lines, so CR studies may prove very useful for comparative analysis.

UHE nuclei propagation and the interpretation of the ankle in the cosmic-ray spectrum

We consider the stochastic propagation of high-energy protons and nuclei in the cosmological microwave and infrared backgrounds, using revised photonuclear cross-sections and following primary and secondary nuclei in the full 2D nuclear chart. We confirm earlier results showing that the high-energy data can be fit with a pure proton extragalactic cosmic ray (EGCR) component if the source spectrum is \propto E^{-2.6}. In this case the ankle in the CR spectrum may be interpreted as a pair-production dip associated with the propagation. We show that when heavier nuclei are included in the source with a composition similar to that of Galactic cosmic-rays (GCRs), the pair-production dip is not present unless the proton fraction is higher than 85%. In the mixed composition case, the ankle recovers the past interpretation as the transition from GCRs to EGCRs and the highest energy data can be explained by a harder source spectrum \propto E^{-2.2} - E^{-2.3}, reminiscent of relativistic shock acceleration predictions, and in good agreement with the GCR data at low-energy and holistic scenarios.

Nanoscale phenomena during the growth of solid solutions on calcite {101¯4} surfaces

This work deals with the growth behaviour of calcite {101¯4} surfaces in contact with multicomponent aqueous solutions containing divalent cations (Ba 2+, Sr 2+, Mn 2+, Cd 2+, or Mg 2+). The result is the formation of solid solutions, with calcite or aragonite as one of the end-members. In situ atomic force microscopy has revealed a wide variety of surface phenomena occurring during the formation of these solid solutions. Among them are: (1) the thickening of growth steps and the subsequent dissolution of surfaces followed by the nucleation of secondary three-dimensional nuclei on calcite surfaces, (2) the transition between growth mechanisms, (3) the formation of an epitaxial layer that armours the substrate from further dissolution and (4) the inhibitory effect of the newly formed surface on the subsequent growth (template effect). The two last phenomena can considerably limit coprecipitation as an effective mechanism for divalent metal uptake. All the phenomena described are a consequence of the interplay between thermodynamics, supersaturation of the aqueous solution with respect to the possible solid solutions and the crystallographic control of the surfaces on the cation incorporation, and indicates that there are many differences between the crystal growth of solid solutions and phases with fixed composition.

Measuring Chromosome Breaks in Patients with Thalassemia

Iron-mediated oxidative stress plays an important role in the pathophysiology of thalassemia. Oxidative stress can cause lesions in DNA, including double-strand breaks. DNA damage, which is a cause of cancer (although not the only one), is recognized as deleterious. Unlike cancer, DNA damage can be assayed easily and relatively inexpensively in humans. In this study, a sensitive micronucleus assay was used to measure the frequency of chromosomal breaks in patients with alpha- and beta-thalassemia. The micronucleus test is based on the observation that a secondary nucleus (micronucleus) is formed around a chromosomal fragment, outside the main nucleus of a dividing cell. Micronuclei are readily apparent in red blood cells (RBCs), which otherwise lack DNA. We combined an immunomagnetic separation technique with single-laser flow cytometry to isolate and analyze reticulocytes in peripheral blood for the presence of micronuclei before these cells are removed by the spleen. Blood samples were obtained from patients with thalassemia and healthy volunteers. After immunomagnetic enrichment of CD71-positive reticulocytes, the cells were stained for micronuclei using the DNA dye 7-aminoactinomycin D (7-AAD) and evaluated by flow cytometry. Our findings indicate that higher levels of micronuclei frequencies are present in thalassemic RBCs.

Poly(A)+ RNA and cytoskeleton during cyst formation in the cap ray of Acetabularia peniculus

The configuration and distribution of polyadenylated RNA (poly(A)+ RNA) during cyst formation in the cap rays of Acetabularia peniculus were demonstrated by fluorescence in situ hybridization using oligo(dT) as a probe, and the spatial and functional relationships between poly(A)+ RNA and microtubules or actin filaments were examined by immunofluorescence microscopy and cytoskeletal inhibitor treatment. Poly(A)+ RNA striations were present in the cytoplasm of early cap rays and associated with longitudinal actin bundles. Cytochalasin D destroyed the actin filaments and caused a dispersal of the striations. Poly(A)+ RNA striations occurred in the cytoplasm of the cap rays up to the stage when secondary nuclei migrated into the cap rays, but they disappeared after the secondary nuclei were settled in their positions. At that time, a mass of poly(A)+ RNA was present around each of the secondary nuclei and accumulated rRNA. This mass colocalized with microtubules radiating from the surface of each secondary nucleus and disappeared when the microtubules were depolymerized by butamifos, which did not affect the configuration of actin filaments. These masses of poly(A)+ RNA continued to exist even after the cap ray cytoplasm divided into cyst domains. Thus two distinct forms of poly(A)+ RNA population, striations and masses, appear in turn at consecutive stages of cyst formation and are associated with distinct cytoskeletal elements, actin filaments and microtubules, respectively.

Visualization of Chromosome Territories in Interphase Nuclei of Ovarian Nurse Cells in Calliphora erythrocephala Mg. (Diptera: Calliphoridae)

Analysis of localization of chromosomes 2, 3, and 6 of Calliphora erythrocephala Mg. in ovarian nurse cell nuclei with different chromatin structure has shown that the regions of DNA probe hybridization reduced with increasing chromatin compaction. Hybridization of DNA probes of chromosomes 3 and 6 to secondary reticular nuclei demonstrated that chromosomes retain their territories in the nuclei when the chromatin acquires a reticular structure. These results suggest regular organization of the chromosomal apparatus at all stages of the endomitotic cycle, including the stage of highly polyploid reticular nuclei. FISH of DNA probe of the chromosome 2 telomeric region to secondary reticular nuclei revealed a peripheral distribution of the signal. Zones of more intensive DNA probe hybridization have been distinguished. These zones probably are the regions of accumulation of telomeric and (or) centromeric chromosome regions.

Chiral Symmetry Breaking and Polymorphism in 1,1‘-Binaphthyl Melt Crystallization

We have studied chiral symmetry breaking in the melt crystallization of 1,1'-binaphthyl. We confirm that chiral symmetry breaking can be induced by stirring the melt as it crystallizes. We find an additional process of vapor crystallization to occur alongside the melt crystallization. This complicates the analysis of the enantiomorphism by introducing a further phenomenon: that of polymorphism. Crystallographic studies by X-ray diffraction reveal two polymorphs of 1,1'-binaphthyl that are made up of two different conformers of each of the two enantiomeric forms of the molecule. Crystals from the melt are generally chiral tetragonal crystals (P42(1)2(1)) composed of (R)- or (S)-1,1'-binaphthyl in a transoid conformer, while those from the vapor are racemic monoclinic crystals (C2/c) made up of the cisoid conformer of both (R)- and (S)-1,1'-binaphthyl enantiomers. The main intermolecular interactions in all these crystals are weak aromatic CH/pi hydrogen bonds, which are responsible for the enantiomeric discrimination in the molecular recognition during crystallization. A tendency for whisker crystal formation is notable in 1,1'-binaphthyl. In stirred crystallization, fluid and mechanical forces can break off these whiskers, which provide secondary nuclei for further crystallization. This autocatalytic mechanism induces chiral symmetry breaking during the crystallization.

Diffusion coefficient and acceleration spectrum from direct measurements of charged cosmic ray nuclei

We discuss the potentials of several experimental configurations dedicated to direct measurements of charged cosmic ray (CR) nuclei at energies ≳100 GeV/n. Within a two-zone propagation model for stable CRs, we calculate light primary and secondary nuclei fluxes for different diffusion and acceleration schemes. We show that the new detectors exploiting the long and ultra long duration balloon flights could determine the diffusion coefficient power index δ through the measurement of the boron-to-carbon ratio with an uncertainty of about 10–15%, if systematic errors are low enough. Only space-based or satellite detectors will be able to determine δ with very high accuracy even in the case of important systematic errors, thanks to the higher energy reach and the less severe limitations in the exposure. We show that no uncertainties other than those on δ affect the determination of the acceleration slope α, so that measures of light primary nuclei, such as the carbon one, performed with the same experiments, will provide valuable information on the acceleration mechanisms.

Temperature and seeding effects on the precipitation of scorodite from sulfate solutions under atmospheric-pressure conditions

Arsenic is a major contaminant in the nonferrous extractive metallurgy. In the past 20 years, many studies have shown that it can be precipitated as relatively stable crystalline scorodite (FeAsO4·2H2O) by precipitation under ambient or elevated pressures. In the present study, an extensive program of scorodite precipitation tests under ambient pressure has shown that the rate of scorodite formation increases dramatically by a small increase in temperature from 85 °C to 100 °C. The beneficial effects of temperature are attributed to the higher thermodynamic stability of scorodite at elevated temperatures, but also to higher rates of secondary nuclei formation and crystal growth. In any case, irrespective of the precipitation temperature, the leachability of all scorodite precipitates observed in toxicity characterization leaching procedure (TCLP) tests is below 5 mg/L As. Another parameter examined in this study was seeding. It was observed that the higher the initial concentration of seed, the faster the precipitation. Precipitation of well-crystallized scorodite can be effected equally well on heterogeneous seed such as hematite (Fe2O3) or gypsum (CaSO4·2H2O) added externally or formed in situ.

A Chandra view of the anomalous half-merger NGC 520

(abridged) High spatial and spectral resolution Chandra X-ray observations of the anomalous merging galaxy NGC520, a similarly-evolved system to the well-known Antennae galaxies, are presented here. Of great interest is the fact that NGC520, on account of it being due to the result of an encounter between one gas-rich disk and one gas-poor disk, appears in X-rays to be only 'half a merger'; Whereas a ULX lies at the primary (SE), more-massive nucleus, no sources are seen at the secondary nucleus. Whereas what appears to be a starburst-driven galactic wind is seen outflowing perpendicular to the molecular disk surrounding the primary nucleus, no such diffuse structure is seen anywhere near the secondary nucleus. Comparing the X-ray properties with those of other merging galaxies, one sees that, relative to its SFR, the number of ULXs seen within the system is rather small. Similarly the total X-ray luminosity and the fraction of this emission that appears diffuse are both a factor ~2 less than that expected based on NGC520's evolutionary merger stage. 15 X-ray sources are detected within the system, including a small number of bright ULXs that flatten the source XLF to a level similar to that of the Antennae and other mergers. Lastly, to see what appears to be a starburst-driven diffuse galactic wind, with a spectrum entirely consistent with that of other known galactic winds, though unusually, emanating from only one of the nuclei, is a surprise, given that one might have expected such structures to have distorted very quickly in such a rapidly evolving environment. The wind is larger and more massive than features seen in evolutionarily earlier systems (eg the Mice), but smaller and less massive than as seen in later systems (eg the Antennae), or classic starbursts.

In vitro culture promotes partial autonomous endosperm development in unfertilized ovules of wild-type Arabidopsis thaliana var. Columbia

Partial endosperm development without paternal genome involvement was induced in unpollinated ovaries of wild-type Arabidopsis thaliana cultured in vitro. Unpollinated pistils were cultured on hormone-free Murashige and Skoog (MS) medium with addition of 6% sucrose and supplemented with: benzylaminopurine (BAP; 2 mg l−1) combined with naphthylacetic acid (NAA; 0.1 mg l−1), 2,4-dichlorophenoxyacetic acid (2,4-D; explants exposed to 1-h auxin shock 20 or 40 mg l−1, and transferred to hormone-free MS medium). Initiation of autonomous endosperm (AE) development was induced on all media used in 54 ovules from 39 cultured ovaries (26%), with an average frequency of 1.4 ovules/ovary. The highest frequency of partial endosperm formation occurred on media combining the two growth regulators BAP and NAA (59% of ovaries had ovules with AE), although endosperm development was also induced on hormone-free medium (in 20.5% of ovaries). The number of AE nuclei ranged from 2 to ~50, depending on the day of culture and medium; neither cellularization nor differentiation on specific regions typical for endosperm of wild-type Arabidopsis, were noted. Fertilization independent endosperm most probably originated from the secondary nucleus, but involvement of the polar nuclei could not be excluded, as indicated by nuclear size and structure. In vitro conditions did not influence egg cell proliferation. Gynogenic embryos were observed neither in the ovules with autonomous endosperm nuclei nor in ovules without endosperm induction.

Laboratory simulation of Mg-rich ferromagnesiosilica dust: The first building blocks of comet dust

We will focus on Mg-rich ferromagnesiosilica principal components (PCs) in the matrix of collected interplanetary dust particles to address the question: “Are these components the original presolar and nebular dust or are they made from precursor dust(s)?” Non-equilibrium condensation experiments show they are fused agglomerates of amorphous MgSiO and FeSiO silicate condensates with unique metastable eutectic compositions. While the dust condensates were not preserved, the PCs survived secondary processing comet nuclei and primitive asteroids wherein they were stored for the last 4.5 billion years.

New photometric and spectroscopic observations of the Seyfert galaxy Mrk 315

We present new important results about the intermediate-type Seyfert galaxy Mrk 315, recently observed through optical imaging and integral-field spectroscopy. Broad-band images were used to study the morphology of the host galaxy, narrow-band Hα images to trace the star-forming regions, and middle-band [O iii] images to evidence the distribution of the highly ionized gas. Some extended emission regions were isolated and their physical properties studied by means of flux-calibrated spectra. High-resolution spectroscopy was used to separate different kinematic components in the velocity fields of gas and stars. Some peculiar features characterize this apparently undisturbed and moderately isolated active galaxy. Such features, already investigated by other authors, are re-analysed and discussed in the light of these new observations. The most relevant results we obtained are: the multitiers structure of the disc; the presence of a quasi-ring of regions with star formation much higher than previous claims; a secondary nucleus confirmed by a stellar component kinematically decoupled by the main galaxy; a new hypothesis about the controversial nature of the long filament, initially described as hook shaped, and more likely made of two independent filaments caused by interaction events between the main galaxy and two dwarf companions.

Spallation-dominated propagation of heavy cosmic rays and the Local Interstellar Medium (LISM)

Measurements of ultra heavy nuclei at GeV/n energies in the galactic cosmic radiation address the question of the sources (nucleosynthetic s- and r-processes). As such, the determination of CR source abundances is a promising way to discriminate between existing nucleosynthesis models. For primary species (nuclei present and accelerated at sources), it is generally assumed that the relative propagated abundances, if they are close in mass, are not too different from their relative source abundances. Besides, the range of the correction factor associated to propagation has been estimated in weighted slab models only. Heavy CRs that are detected near Earth were accelerated from regions that are closer to us than were the light nuclei. Hence, the geometry of sources in the Solar neighbourhood, and as equally important, the geometry of gas in the same region, must be taken into account. In this paper, a two zone diffusion model is used, and as was previously investigated for radioactive species, we report here on the impact of the local interstellar medium (LISM) feature (under-dense medium over a scale ~100 pc) on primary and secondary stable nuclei propagated abundances. Going down to Fe nuclei, the connection between heavy and light abundances is also inspected. A general trend is found that decreases the UHCR source abundances relative to the HCR ones. This could have an impact on the level of r-process required to reproduce the data.

Embryology of Megacodon stylophorus and Veratrilla baillonii (Gentianaceae): descriptions and systematic implications

The embryological characters of Megacodon stylophorus (C. B. Clark) H. Smith and Veratrilla baillonii Franch. are described for the first time and the systematic relationships of Megacodon and Veratrilla are discussed. Both species share the following embryological features. The anthers are tetrasporangiate. The formation of anther walls is of the Dicotyledonous Type. The tapetum is of glandular type with uninucleate cells which have a dual origin. The tapetal cells on the connective side show radial elongation or periclinal division and intrude into the anther locule to form ‘placentoids’. Cytokinesis in the microsporocyte meiosis is of the simultaneous type and the microspore tetrads are nearly always tetrahedral, rarely decussate. The ovary is bicarpellate and unilocular. The ovule is unitegmic and tenuinucellar. The formation of the embryo sac is of the Polygonum Type. Before fertilization, the two polar nuclei fuse into a secondary nucleus. Fertilization is porogamous. The development of the endosperm is of the Nuclear Type. However, the two species show variation in the following features: the number of cell layers which form the anther locule wall; construction of the wall of the mature anther; cell number in mature pollen grains; ovule number in cross sections of placentae; degree of ovule curvature; character of the hypostase and seed shape. In a comparison with the other taxa in the tribe Gentianeae using embryological features, Megacodon is referred to as an independent genus and should be treated as a member of the subtribe Swertiinae; Veratrilla is better separated from Swertia s.l. as an independent genus. Veratrilla is more derived than Swertia s.s. and shows a close relationship with S. tetraptera.

Activation of MK5/PRAK by the atypical MAP kinase ERK3 defines a novel signal transduction pathway

Erratum27 January 2005free access Activation of MK5/PRAK by the atypical MAP kinase ERK3 defines a novel signal transduction pathway Ole-Morten Seternes Ole-Morten Seternes Search for more papers by this author Theresa Mikalsen Theresa Mikalsen Search for more papers by this author Bjarne Johansen Bjarne Johansen Search for more papers by this author Espen Michaelsen Espen Michaelsen Search for more papers by this author Chris G Armstrong Chris G Armstrong Search for more papers by this author Nick A Morrice Nick A Morrice Search for more papers by this author Benjamin Turgeon Benjamin Turgeon Search for more papers by this author Sylvain Meloche Sylvain Meloche Search for more papers by this author Ugo Moens Ugo Moens Search for more papers by this author Stephen M Keyse Stephen M Keyse Search for more papers by this author Ole-Morten Seternes Ole-Morten Seternes Search for more papers by this author Theresa Mikalsen Theresa Mikalsen Search for more papers by this author Bjarne Johansen Bjarne Johansen Search for more papers by this author Espen Michaelsen Espen Michaelsen Search for more papers by this author Chris G Armstrong Chris G Armstrong Search for more papers by this author Nick A Morrice Nick A Morrice Search for more papers by this author Benjamin Turgeon Benjamin Turgeon Search for more papers by this author Sylvain Meloche Sylvain Meloche Search for more papers by this author Ugo Moens Ugo Moens Search for more papers by this author Stephen M Keyse Stephen M Keyse Search for more papers by this author Author Information Ole-Morten Seternes, Theresa Mikalsen, Bjarne Johansen, Espen Michaelsen, Chris G Armstrong, Nick A Morrice, Benjamin Turgeon, Sylvain Meloche, Ugo Moens and Stephen M Keyse The EMBO Journal (2005)24:873-874https://doi.org/10.1038/sj.emboj.7600591 This article corrects the following: Activation of MK5/PRAK by the atypical MAP kinase ERK3 defines a novel signal transduction pathway02 December 2004 PDFDownload PDF of article text and main figures. ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InMendeleyWechatReddit Figures & Info Correction to: The EMBO Journal (2004) 23, 4780–4791. doi:10.1038/sj.emboj.7600489 Due to a typesetting error, Figure 3c of the above article was published incorrectly in print. The correct Figure 3 is reproduced below in its entirety. Figure 1.Amino acids 330–340 of ERK3 are required for interaction with and relocalisation of MK5. (A) COS-1 cells were transfected with expression vectors encoding Myc-tagged full-length, or C-terminal truncation mutants of ERK3 encoding either amino acids 1–340 or 1–330 of the protein. Cell lysates were then mixed with either recombinant GST-MK5 or GST alone. Binding of ERK3 was detected by Western blotting using an anti-Myc monoclonal antibody. (B) HeLa cells were transfected with expression vectors encoding either amino acids 1–330 or 1–340 of ERK3. ERK3 was visualised by staining with an anti-ERK3 antibody and an Alexa 594-coupled secondary (anti-sheep) antibody (red channel in upper panels) and cell nuclei were visualised by DRAQ5 staining (blue channel in lower panels). In all, 100 cells expressing the indicated mutant of ERK3 from each of three independent transfections were counted and the distribution of the ERK3 protein was scored. The results are presented as the % of cells in which the ERK3 protein was predominantly nuclear (N>C) and mean values with associated errors are shown. (C) HeLa cells were cotransfected with vectors encoding EGFP-MK5 and either ERK3 1–330 or 1–340. EGFP-MK5 was visualised directly (green channel in upper panels), ERK3 was visualised by staining with an anti-ERK3 antibody and an Alexa 594-coupled secondary (anti-sheep) antibody (red channel in middle panels) and cell nuclei were visualised by DRAQ5 staining (blue channel in lower panels). A total of 100 cells expressing either EGFP-MK5 alone or coexpressing both EGFP-MK5 and the indicated mutant of ERK3 from three independent transfections were counted and the distribution of MK5 was scored. The results are presented as the % of cells in which EGFP-MK5 was either predominantly nuclear (N>C) or predominantly cytoplasmic (C>N) and mean values with associated errors are shown. In all experiments, several fields of cells were examined and representative images are shown. Download figure Download PowerPoint The Publisher would like to apologise for any inconvenience this may have caused. Next ArticlePrevious Article Read MoreAbout the coverClose modalView large imageVolume 24,Issue 4,February 23, 2005Molecular Dream by Brian O'Hara. The 9 individual panels of this installation were painted with transparent glass paint on double layers of perspex and are based on coloured slides of common molecular biology themes. Brian O'Hara is a Dublin-based artist who lived in Germany for many years. The photograph was taken in the EMBO Building in Heidelberg on a sunny summer evening in 2004. Visit the artist at http://www.brian-ohara.com or send an e-mail to [email protected] Volume 24Issue 423 February 2005In this issue FiguresRelatedDetailsLoading ...

Formation mechanism of shish in the oriented melt (II)—two different growth mechanisms along and perpendicular to the flow direction

In part 1 of this series of paper, we have solved the formation mechanism of shish from the oriented melt based on the kinetic observation. In this work, we have shown for the first time the molecular mechanism of the growth of shish by kinetic study. We found that there are two different type of the growth of shish against the flow direction. The growth rate along the flow direction (U) is proportional to ΔT, where ΔT is the degree of supercooling. This indicates that U is mainly controlled by the rearrangement process of the chain near the end surface of the shish. On the other hand, the growth rate perpendicular to the flow direction (V) obeyed a well-known equation V∝exp(−B/ΔT), where B is a constant proportional to the free energy necessary for forming a critical secondary nucleus ΔG*. This indicates that V is mainly controlled by the secondary nucleation process on the side surface of shish. Moreover, we also found that there is a critical shear rate γ˙* for the growth of shish. Below γ˙*, U and V approached to zero and the growth rate of spherulite, respectively. From this experimental fact, we proposed that the chain conformation near the interface between the melt and shish, i.e. near the end and side surface of shish is elongated and oriented by the shear flow above γ˙*.

Environmental light and suprachiasmatic nucleus interact in the regulation of body temperature

The mammalian biological clock, located in the suprachiasmatic nucleus (SCN), is crucial for circadian rhythms in physiology and behavior. However, equivocal findings have been reported on its role in the circadian regulation of body temperature. The goal of the present studies was to investigate the interaction between the SCN and environmental light in the regulation of body temperature. All recordings were performed by telemetry in free moving male Wistar rats. Firstly, we demonstrated an endogenous circadian rhythm in body temperature independent of locomotor activity. This rhythm was abolished by stereotactic lesioning of the SCN. Secondly, we demonstrated a circadian phase-dependent suppressive effect of light (‘negative masking’) on body temperature. Light suppressed body temperature more at the end of the subjective night (circadian time [CT] 22) than in the middle (CT 6) and at the end (CT 10) of the subjective day. This circadian-phase dependent suppression was not demonstrated in SCN-lesioned animals. Surprisingly, after half a year of recovery from lesioning of the SCN, light regained its suppressing action on body temperature, resulting in a daily body temperature rhythm only under light–dark conditions. In contrast to body temperature, light could not substantially mimic a daytime inhibitory SCN-output in the regulation of heart rate and locomotor activity. The present results suggest that, after lesioning of the SCN as main relay station for the immediate body temperature-inhibition by light, secondary relay nuclei can fully take over this function of the SCN. These findings provide a possible explanation for the controversy in literature over the question whether the SCN is required for the diurnal rhythm in body temperature. Furthermore, they show that light may have an acute effect on behavior and physiology of the organism via the SCN, which extends beyond the generally acknowledged effect on melatonin secretion.

Secondary nucleation and growth of organic crystals in industrial crystallization

Semi-batch crystallizations were used to measure the metastable limit of activated secondary nucleation of an industrial organic compound. Supersaturation profiles, Crystal Size Distribution (CSD) measurements and Scanning Electron Microsopic (SEM) pictures of crystals withdrawn during the experiments have been used to show that this previously poorly understood mechanism is a two-step process. The first part is the activation necessary to form secondary nuclei, the second part consists of the detachment of these secondary nuclei which have generally grown on the surface. This part is dependent on the energy input. This mechanism is also closely related to imperfect growth.