The unexpected long period of elevated CH4 emissions from an inundated fen meadow ended only with the occurrence of cattail (Typha latifolia)

Drainage and agricultural use transform natural peatlands from a net carbon (C) sink to a net C source. Rewetting of peatlands, despite of high methane (CH₄) emissions, holds the potential to mitigate climate change by greatly reducing CO₂ emissions. However, the time span for this transition is unknown because most studies are limited to a few years. Especially, nonpermanent open water areas often created after rewetting, are highly productive. Here, we present 14 consecutive years of CH₄ flux measurements following rewetting of a formerly long-term drained peatland in the Peene valley. Measurements were made at two rewetted sites (non-inundated vs. inundated) using manual chambers. During the study period, significant differences in measured CH₄ emissions occurred. In general, these differences overlapped with stages of ecosystem transition from a cultivated grassland to a polytrophic lake dominated by emergent helophytes, but could also be additionally explained by other variables. This transition started with a rapid vegetation shift from dying cultivated grasses to open water floating and submerged hydrophytes and significantly increased CH₄ emissions. Since 2008, helophytes have gradually spread from the shoreline into the open water area, especially in drier years. This process was periodically delayed by exceptional inundation and eventually resulted in the inundated site being covered by emergent helophytes. While the period between 2009 and 2015 showed exceptionally high CH₄ emissions, these decreased significantly after cattail and other emergent helophytes became dominant at the inundated site. Therefore, CH₄ emissions declined only after 10 years of transition following rewetting, potentially reaching a new steady state. Overall, this study highlights the importance of an integrative approach to understand the shallow lakes CH₄ biogeochemistry, encompassing the entire area with its mosaic of different vegetation forms. This should be ideally done through a study design including proper measurement site allocation as well as long-term measurements.     

Physiological effects of translation initiation factor IF3 and ribosomal protein L20 limitation inEscherichia coli

To investigate the physiological roles of translation initiation factor IF3 and ribosomal protein L20 inEscherichia coli, theinfC, rpmI andrpIT genes encoding IF3, L35 and L20, respectively, were placed under the control oflac promoter/operator sequences. Thus, their expression is dependent upon the amount of inducer isopropyl thiogalactoside (IPTG) in the medium. Lysogenic strains were constructed with recombinant lambda phages that express eitherrpmI andrplT orinfC andrpmI in trans, thereby allowing depletion of only IF3 or L20 at low IPTG concentrations. At low IPTG concentrations in the IF3-limited strain, the cellular concentration of IF3, but not L20, decreases and the growth rate slows. Furthermore, ribosomes run off polysomes, indicating that IF3 functions during the initiation phase of protein synthesis in vivo. During slow growth, the ratio of RNA to protein increases rather than decreases as occurs with control strains, indicating that IF3 limitation disrupts feedback inhibition of rRNA synthesis. As IF3 levels drop, expression from an AUU-infC-lacZ fusion increases, whereas expression decreases from an AUG-infC-lacZ fusion, thereby confirming the model of autogenous regulation ofinfC. The effects of L20 limitation are similar; cells grown in low concentrations of IPTG exhibited a decrease in the rate of growth, a decrease in cellular L20 concentration, no change in IF3 concentration, and a small increase in the ratio of RNA to protein. In addition, a decrease in 50S subunits and the appearance of an aberrant ribosome peak at approximately 41–43S is seen. Previous studies have shown that the L20 protein negatively controls its own gene expression. Reduction of the cellular concentration of L20 derepresses the expression of anrplT-lacZ gene fusion, thus confirming autogenous regulation by L20.     

Cell-free reconstitution of Fas-, UV radiation- and ceramide-induced apoptosis.

Cell-free systems are valuable tools for the dissection of complex cellular processes. Here we show that cytoplasmic extracts from cells exposed to anti-Fas antibody or UV radiation contain an activity capable of reproducing morphological changes typical of apoptosis in nuclei added to these extracts, as well as internucleosomal cleavage of DNA and proteolysis of a protein known to be cleaved during the apoptosis of intact cells. Extracts from control cell populations were inactive in this respect. These effects were partly blocked by the addition of purified Bcl-2 protein or a competitive inhibitor peptide of interleukin-1 beta-converting enzyme to the extracts. Furthermore, apoptotic activity was induced in cytoplasmic extracts from untreated cells by the addition of ceramide, a lipid second messenger implicated recently in apoptosis signaling. These extracts should prove highly useful in the dissection of molecular events that occur during apoptosis.     

Microdistribution of butterflies in a mosaic-like habitat: The role of nectar sources

The microdistribution of five butterfly species through their flying season was analyzed in a mosaic-like habitat, brought about by secondary succession In order to explain the patterns observed, activity patterns and the use and distribution of nectar sources were determined Emphasis was laid on the changing allocation of visits to flower species and changing abundances of flowers during the season The use of nectar sources was basically limited to three flower species, Centaurea scabiosa, C bracteata and Serratula tinctoria As a consequence, niche breadth values were generally low and niche overlaps generally high Some butterflies changed their patterns of flower visits during the season and therefore reduced niche overlap with the other butterfly species The microdistribution of Melanargia galathea, Lysandra condon, Ochlodes venatus and Lictoria achilleae was strongly influenced by the distribution of their preferred nectar sources as well as by areas generally rich in flowers Changing flower preferences of Melanargia galathea and Lysandra coridon males during the course of the season were also expressed by changes in the correlations between the distribution of these butterflies and their nectar plants The distribution of nectar sources was not found to be of importance for Coenonympha arcanta, a species which rarely visited flowers     

Comparative trial of treatment with Prioderm lotion and Kwellada shampoo in children with head lice.

The safety and efficacy of treatment with a new pediculicide lotion, Prioderm (0.5% malathion in isopropanol), were compared with those of treatment with Kwellada (1% lindane) shampoo in a randomized trial of children with head lice. The children''s scalps were examined for live lice immediately, 7 days and 4 to 6 weeks following treatment. To determine the in-vitro ovicidal effect of treatment, samples of hair with nits were removed before and immediately following treatment; the subsequent rates of hatching were compared. No live lice were present immediately following either treatment. At 7 days after treatment 2 of the 29 children treated with Prioderm lotion and 4 of the 33 children treated with Kwellada shampoo were infested with live lice, whereas at 4 to 6 weeks after treatment 5 and 3 children respectively were infested. The initial effectiveness of treatment was 93% in the children treated with Prioderm lotion and 88% in those treated with Kwellada shampoo; however, a large difference in efficacy could have been missed owing to the small number of children in the study. Both preparations demonstrated in-vitro ovicidal activity, but neither totally abolished post-treatment hatching. No side effects were reported from either preparation. Because ovicidal activity was incomplete two treatments with the same pediculicides should be given about 7 days apart.     

Active K+ transport in Mycoplasma mycoides var. Capri. Net and unidirectional K+ movements

Analysis of the cation composition of growing Mycoplasma mycoides var. Capri indicates that these organisms have a high intracellular K⁺ concentration ($\text{K}{}_{\mathrm{<mtext>i</mtext>}}\text{: 200–300}\text{mM}$) which greatly exceeds that of the growth medium, and a low Na⁺ concentration ($\text{Na}{}_{\mathrm{<mtext>i</mtext>}}{}^{\mathrm{+}}\text{: 20}\text{mM}$). Unlike $\text{Na}{}_{\mathrm{<mtext>i</mtext>}}{}^{\mathrm{+}}\text{, K}{}_{\mathrm{<mtext>i</mtext>}}{}^{\mathrm{+}}$ varies with cell aging.The K⁺ transport properties studied in washed organisms resuspended in buffered saline solution show that cells maintain a steady and large K⁺ concentration gradient across their membrane at the expense of metabolic energy mainly derived from glycolysis. In starved cells, $\text{K}{}_{\mathrm{<mtext>i</mtext>}}{}^{\mathrm{+}}$ decreases and is partially compensated by a gain in Na⁺. This substitution completely reverses when metabolic substrate is added (K⁺ reaccumulation process). Kinetic analysis of K⁺ movement in cells with steady K⁺ level shows that most of K⁺ influx is mediated by an autologous K⁺-K⁺ exchange mechanism. On the other hand, during K⁺ reaccumulation by K⁺-depleted cells, a different mechanism (a K⁺ uptake mechanism) with higher transport capacity and affinity drives the net K⁺ influx. Both mechanisms are energy-dependent.Ouabain and anoxia have no effect on K⁺ transport mechanisms; in contrast, both processes are completely blocked by dicyclohexylcarbodiimide, an inhibitor of the Mg²⁺-dependent ATPase activity.     

Gene fusion vectors based on the gene for staphylococcal protein A

Two plasmid vectors, containing the gene coding for staphylococcal protein A and adapted for gene fusion, have been constructed. These vectors will allow fusion of any gene to the protein A gene, thus giving hybrid proteins which can be purified, in a one-step procedure, by IgG affinity chromatography. As an example of the practical use of such vectors, the protein A gene has been fused to the lacZ gene of Escherichia coli. E. coli strains containing such plasmids produce hybrid proteins with both IgG binding and β-galactosidase activities. The hybrid protein(s) can be immobilized on IgG-Sepharose by its protein A moiety with high efficiency without losing its enzymatic activity and they can be eluted from the column by competitive elution with pure protein A. The fused protein(s) also binds to IgG-coated microtiter wells which means that the in vivo product can be used as an enzyme conjugate in ELISA tests.     

The Binding Properties of the Particulate and Solubilized Sulfonylurea Receptor from Cerebral Cortex Are Modulated by the Mg2+ Complex of ATP

Glibenclamide closes an ATP-sensitive K+ channel (K-ATP channel) by interaction with the sulfonylurea receptor in the plasma membrane of pancreatic B cells and thereby initiates insulin release. Previous studies demonstrated that the Mg2+ complex of ATP decreases glibenclamide binding to the sulfonylurea receptor from pancreatic islets. The aim of the present study was to examine the effect of adenine and guanine nucleotides on binding of sulfonyl-ureas to the cerebral sulfonylurea receptor. For this purpose, binding properties of the particulate and solubilized site from rat or pig cerebral cortex were analyzed. Maximum recovery of receptors in detergent extracts amounted to 40-50%. Specific binding of [3H]glibenclamide to the solubilized receptors corresponded well to specific binding to microsomes. In microsomes and detergent extracts, the Mg2+ complexes of ATP, ADP, GTP, and GDP inhibited binding of [3H]glibenclamide. These effects were not observed in the absence of Mg2+. In detergent extracts, Mg-ATP (300 microM) reduced the number of high-affinity sites for [3H]-glibenclamide by 52% and increased the dissociation constant for [3H]glibenclamide by eightfold; Mg-ATP was half-maximally effective at 41 microM. Alkaline phosphatase accelerated the reversal of Mg-ATP-induced inhibition of [3H]glibenclamide binding. The data suggest similar control of the sulfonylurea receptor from brain and pancreatic islets by protein phosphorylation.