Altered Phase-Relationship between Peripheral Oscillators and Environmental Time in Cry1 or Cry2 Deficient Mouse Models for Early and Late Chronotypes

The mammalian circadian system is composed of a light-entrainable central clock in the suprachiasmatic nuclei (SCN) of the brain and peripheral clocks in virtually any other tissue. It allows the organism to optimally adjust metabolic, physiological and behavioral functions to the physiological needs it will have at specific time of the day. According to the resonance theory, such rhythms are only advantageous to an organism when in tune with the environment, which is illustrated by the adverse health effects originating from chronic circadian disruption by jetlag and shift work. Using short-period Cry1 and long-period Cry2 deficient mice as models for morningness and eveningness, respectively, we explored the effect of chronotype on the phase relationship between the central SCN clock and peripheral clocks in other organs. Whereas the behavioral activity patterns and circadian gene expression in the SCN of light-entrained Cry1^-/- and Cry2^-/- mice largely overlapped with that of wild type mice, expression of clock and clock controlled genes in liver, kidney, small intestine, and skin was shown to be markedly phase-advanced or phase-delayed, respectively. Likewise, circadian rhythms in urinary corticosterone were shown to display a significantly altered phase relationship similar to that of gene expression in peripheral tissues. We show that the daily dissonance between peripheral clocks and the environment did not affect the lifespan of Cry1^-/- or Cry2^-/- mice. Nonetheless, the phase-shifted peripheral clocks in light-entrained mice with morningness and eveningness-like phenotypes may have implications for personalized preventive and therapeutic (i.e. chronomodulation-based) health care for people with early and late chronotypes.     

Dr. Alfred Jeske 75 jahre

The chemical composition, phytotoxic and antifungal activities of the essential oils isolated by hydrodistillation from the needles of Tunisian Aleppo pine harvested from different provenances were evaluated. The chemical composition analysed by gas chromatography/mass spectrometry (GC/MS) revealed variability among provenances displaying interesting chemotypes, (Z)-caryophyllene (16.16–28.9%), β-myrcene (8.5–22.9%), α-pinene (11.7–13.14%), β-pinene (3.13–11.8%), bicyclogermacrene (5.2–12.37%), α-terpinolene (8.11–11.01%) and α-humulene (2.85–5.2%), which were the main components in the oil. Antifungal ability of Aleppo pine oils was tested by disc agar diffusion against 10 phytopathogenic fungi. Weak antifungal activity was observed for the essential oils isolated. Furthermore, in contrast, the herbicidal activity investigated for three common weeds in Tunisian cereal crops was very strong and seed germination was inhibited at a low concentration and their herbicidal effects were higher than those of a commercial herbicide.     

The functional significance of lateral line canal morphology on the trunk of the marine teleost Xiphister atropurpureus (Stichaeidae)

We investigated the filter properties of the highly branched trunk lateral lines of the stichaeid Xiphister atropurpureus and compared them to the filter properties of simple lateral line canals. For this purpose artificial canals were constructed, some of which were fitted with artificial neuromasts. In still water, the response of a simple canal versus two types of Xiphister-like canals to a vibrating sphere stimulus were similar, as was the decrease in the responses as a function of sphere distance. Also comparable was the mechanical coupling between neighboring parts of the main canal. However, compared to the simple canal, the Xiphister-like canals showed a lower spatial resolution. Equipping artificial lateral line canals with artificial neuromasts revealed that Xiphister-like canals, i.e., lateral lines canals with tubuli that contained widely spaced pores, improve the signal-to-noise ratio in a highly turbulent environment. Even though a reduced spatial resolution is the price for this improvement, Xiphister may compensate for this compromise by having four instead of the usual single trunk lateral line canal. We suggest that lateral line canals with tubuli that contain widely spaced pores and multiple lateral line canals on each body side are an adaptation to a highly turbulent aquatic environment.     

Avoidance conditioning in bamboo sharks (Chiloscyllium griseum and C. punctatum): behavioral and neuroanatomical aspects

Animals face different threats; to survive, they have to anticipate how to react or how to avoid these. It has already been shown in teleosts that selected regions in the telencephalon, i.e., the medial pallium, are involved in avoidance learning strategies. No such study exists for any chondrichthyan. In nature, an avoidance reaction may vary, ranging from a ‘freeze’ reaction to a startling response and quick escape. This study investigated whether elasmobranchs (Chiloscyllium griseum and C. punctatum) can be conditioned in an aversive classical conditioning paradigm. Upon successful conditioning, the dorsal, medial and lateral pallium were removed (group 1) and performance tested again. In a second group, the same operation was performed prior to training. While conditioning was successful in individuals of both groups, no escape responses were observed. Post-operative performance was assessed and compared between individual and groups to reveal if the neural substrates governing avoidance behavior or tasks learned in a classical conditioning paradigm are located within the telencephalon, as has been shown for teleosts such as goldfish.     

Root system development of Lotus corniculatus L. in calcareous sands with embedded finer-textured fragments in an initial soil

Background and aims

In post mining landscapes as in the Lusatian region (Brandenburg, Germany), Pleistocene coarse-textured, sandy sediments are used for soil rehabilitation and land reclamation. The homogeneously-appearing initial soils are characterized by finer-textured soil clumps (fragments) of different sizes that are embedded in a sandy matrix. These soils with typical local-scale heterogeneity may serve as a model for studying how spatially-distributed soil fragments may be utilized by pioneering plant species. The aim of this study was to gain insight into the physical and chemical properties of sandy matrix and fragments that could possibly explain why embedded fragment may act as hot spots for root growth.

Methods

In 2009, three soil monoliths of dimension 50 cm?×?50 cm?×?50 cm that were exclusively vegetated by Lotus corniculatus L. planted in 2008 were studied. Each layer of 10 cm was sampled successively using a cubic metal frame with 10 cm edge length (25 samples per layer each with a volume of 1 l). The samples were analyzed for root biomass, root lengths and diameter, and for chemical and physical properties of sandy matrix and fragments.

Results

Bulk density, water contents, total carbon, total nitrogen, and plant available calcium contents were higher for the fragments compared to the sandy matrix. The roots of L. corniculatus were heterogeneously distributed in the monoliths. The root density distributions for the 1 L samples indicated a positive influence of fragments on directed root growth. Fragments embedded in the sandy matrix were found to be strongly penetrated by roots despite their relatively high bulk density. The presence of fragments also led to an increased root biomass in the sandy matrix in the direct vicinity of fragments. Such direct effects on root development were accompanied by more indirect effects by locally-elevated moisture and nutrient contents.

Conclusion

The results suggest that finer-textured fragments embedded in coarser-textured sediments, can have favorable effect on plant and root development during the initial stages of establishment of vegetation cover. The fragments can act as water and nutrient hot spots to improve supply of pioneering plants especially in coarse-textured soil. The existence of small-scale heterogeneities owing to incomplete sediment mixing e.g., in soil reclamation, could be generally important for controlling the speed and direction of early plants-establishment, for instance, in the succession of post-mining areas.     

Identification of a Dithiol-disulfide Switch in Collapsin Response Mediator Protein 2 (CRMP2) That Is Toggled in a Model of Neuronal Differentiation

Vertebrate-specific glutaredoxin 2 (Grx2) is expressed in at least two isoforms, mitochondrial Grx2a and cytosolic Grx2c. We have previously shown that cytosolic Grx2 is essential for embryonic development of the brain. In particular, we identified collapsin response mediator protein 2 (CRMP2/DPYSL2), a mediator of the semaphorin-plexin signaling pathway, as redox-regulated target of Grx2c and demonstrated that this regulation is required for normal axonal outgrowth. In this study, we demonstrate the molecular mechanism of this regulation, a specific and reversible intermolecular Cys-504-Cys-504 dithiol-disulfide switch in homotetrameric CRMP2. This switch determines two conformations of the quaternary CRMP2 complex that controls axonal outgrowth and thus neuronal development.