Attachment sites and interconnections of the microtubular system in pigment-containing epidermal cells of Carausius morosus (Insecta,Phasmida)

Summary The apical plasma membranes of epidermal cells in the stick insect Carausius morosus Brunner, 1908 forms deep invaginations, the inner surfaces of which are covered with a zone of fine filamentous, electron-dense material. These and similar electron-dense zones, forming circumscribed areas of the basal membrane, are for the attachment of microtubules. These structures may be microtubuleintiating sites, where microtubules start to polymerize. Microtubules have sidearms that project freely or are attached to the stem, to sidearms of other microtubules or to filaments 4–6 nm in diameter and to a fine filamentous electron-dense meshwork. Their attachment to the apical and basal plasma membranes and to each other make them a firmly anchored cytoskeleton, an important prerequisite for pigment movement.     

Contamination effects on soil density fractions from high N or C content sodium polytungstate

Sodium polytungstate (SPT) is currently the material of choice for soil density fractionation (DF). We recently detected high levels of N in several types of commercially available SPT (0.74–1.4 mg g^?1), raising a concern that undesirable chemical effects on soils may occur during the DF procedure. To address this concern, we conducted two experiments to examine effects of SPT on C and N in the resulting soil fractions. First we suspended A-horizon material from three soil types of greatly differing mineralogy for 24 h in solutions containing three types of commercially obtained SPT and commercial SPT that had been passed through cation exchange resin columns. We compared %C, %N, ¹⁵N and ¹³C values in treated and untreated soils. We also spiked SPT with tracer-level ¹⁵NH₄ ⁺ to measure potential NH₄ ⁺ absorption by the soil fractions. Results suggest that the N-rich commercially available SPT can have a considerable effect on δ¹⁵N values, likely due to the presence of ¹⁵N-enriched NH₄ ⁺ in the SPT. In one of our soils, ¹⁵N enrichment of 3‰ was observed associated with overnight soaking in N-rich SPT (0.74 mg g^?1). By contrast, when using SPT with low levels of N (0.05 mg g^?1), no significant changes in ¹⁵N were observed. The remaining soil (after suspension and rinsing) was similar in %C, %N, ¹⁵N and ¹³C to the untreated bulk soil, suggesting that suspension of soil in SPT with low N levels purchased from the manufacturer or else through treatment with cation exchange resins does not greatly alter these variables. Low-N SPT is available commercially although it must be specifically requested from the manufacturer and is currently more expensive to purchase. Our results confirm that SPT tested and known to be low in C and N (<0.06 mg g^?1) does not adversely contaminate soils during the soil density fractionation procedure. If using newly purchased or recycled SPT with higher N or C levels than this, we recommend thorough testing for possible contamination effects prior to use. However we caution against using SPT that contains N or C levels >0.5 mg g^?1.     

Do warmer winters change variability patterns of physical and chemical lake conditions in Sweden?

In this study, the effect of a warmer winter climate on variability patterns of physical and chemical lake conditions was examined by using monthly air temperature data from 72 meteorological Swedish sites, ice breakup data from 77 Swedish lakes and monthly data of 17 water chemical variables from 11 nutrient-poor Swedish reference lakes during 1988–2005. The results showed significantly increasing variations of lake ice breakup dates and nitrate concentrations over Sweden along with increasing winter air temperatures. Variability patterns of other water chemical variables were not affected by warmer winters. Nitrate concentrations increased their variability in spring and early summer not only between lakes but also within lakes, which was attributed to a climate-induced increase in spring nitrate concentrations in particular in southern Sweden, while summer nitrate concentrations remained rather constant and low all over Sweden (median 10 μg l⁻¹). Since nitrate concentrations play an important role for primary production, highly varying concentrations will be a challenge for biota to adapt.     

Temporal pattern of ICAM-I mediated regulatory T cell recruitment to sites of inflammation in adoptive transfer model of multiple sclerosis

Migration of immune cells to the target organ plays a key role in autoimmune disorders like multiple sclerosis (MS). However, the exact underlying mechanisms of this active process during autoimmune lesion pathogenesis remain elusive. To test if pro-inflammatory and regulatory T cells migrate via a similar molecular mechanism, we analyzed the expression of different adhesion molecules, as well as the composition of infiltrating T cells in an in vivo model of MS, adoptive transfer experimental autoimmune encephalomyelitis in rats. We found that the upregulation of ICAM-I and VCAM-I parallels the development of clinical disease onset, but persists on elevated levels also in the phase of clinical remission. However, the composition of infiltrating T cells found in the developing versus resolving lesion phase changed over time, containing increased numbers of regulatory T cells (FoxP3) only in the phase of clinical remission. In order to test the relevance of the expression of cell adhesion molecules, animals were treated with purified antibodies to ICAM-I and VCAM-I either in the phase of active disease or in early remission. Treatment with a blocking ICAM-I antibody in the phase of disease progression led to a milder disease course. However, administration during early clinical remission aggravates clinical symptoms. Treatment with anti-VCAM-I at different timepoints had no significant effect on the disease course. In summary, our results indicate that adhesion molecules are not only important for capture and migration of pro-inflammatory T cells into the central nervous system, but also permit access of anti-inflammatory cells, such as regulatory T cells. Therefore it is likely to assume that intervention at the blood brain barrier is time dependent and could result in different therapeutic outcomes depending on the phase of CNS lesion development.     

The multifunctional sensory complex in the antennae ofAllacma fusca (Insecta)

Summary The antennal-tip sensory complex inAllacma fusca (Collembola) was reconstructed from serial ultrathin sections. The complex contains 16 sensory cells which belong to three spatially separated subunits: (1) a sensory hair; (2) a cuticular protrusion, containing two highly-specialized dendritic outer segments from a single sensory cell encapsulated by an enveloping cell and a gland cell (Figs. 4 and 5); and (3) two sensory cells with partly lamellated, double dendritic outer segments located well away from the cuticular surface (Fig. 3). A phylogenetic evaluation reveals a mosaic of apparently primitive characters, and trends toward higher structural complexity as well as toward reduction (Table 1). There is support for a hypothesis that the receptors of the sensory hair are chemosensitive. The functional interpretation of the other components of the complex is problematic due to their unusual structural properties. The sensory cell beneath the cuticular protrusion is considered to be proprioceptive.Supported by the Deutsche Forschungsgemeinschaft (Al 56/6)     

Methanococcus thermolithotrophicus,a novel thermophilic lithotrophic methanogen

An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H₂/CO₂ and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.Abbreviations G+C Guanine + Cytosine - SDS Sodium dodecylsulfate (Sodium lauryl sulfate)