Xylosylated naphthoic acid-amino acid conjugates for investigation of glycosaminoglycan priming

Three different series of xylosylated naphthoic acid-amino acid conjugates containing one or two amino acid residues were synthesized for the investigation of glycosaminoglycan priming and potential use as anti-tumor drugs. All xylosylated naphthoic acid-conjugates inhibited the growth of normal lung fibroblasts to some extent, whereas the growth of tumor derived T24 carcinoma cells was not affected. There was no correlation between amino acid conjugation, retention time and the antiproliferative activity. Only one compound initiated the priming of glycosaminoglycans. Modification of the naphthalene ring with one or two amino acid residues did not have any effect on proteoglycan biosynthesis or glycosaminoglycan priming in T24 carcinoma cells.     

Simultaneous Fluorescence In Situ Hybridization of mRNA and rRNA in Environmental Bacteria

We developed for Bacteria in environmental samples a sensitive and reliable mRNA fluorescence in situ hybridization (FISH) protocol that allows for simultaneous cell identification by rRNA FISH. Samples were carbethoxylated with diethylpyrocarbonate to inactivate intracellular RNases and pretreated with lysozyme and/or proteinase K at different concentrations. Optimizing the permeabilization of each type of sample proved to be a critical step in avoiding false-negative or false-positive results. The quality of probes as well as a stringent hybridization temperature were determined with expression clones. To increase the sensitivity of mRNA FISH, long ribonucleotide probes were labeled at a high density with cis-platinum-linked digoxigenin (DIG). The hybrid was immunocytochemically detected with an anti-DIG antibody labeled with horseradish peroxidase (HRP). Subsequently, the hybridization signal was amplified by catalyzed reporter deposition with fluorochrome-labeled tyramides. p-Iodophenylboronic acid and high concentrations of NaCl substantially enhanced the deposition of tyramides and thus increased the sensitivity of our approach. After inactivation of the antibody-delivered HRP, rRNA FISH was performed by following routine protocols. To show the broad applicability of our approach, mRNA of a key enzyme of aerobic methane oxidation, particulate methane monooxygenase (subunit A), was hybridized with different types of samples: pure cultures, symbionts of a hydrothermal vent bivalve, and even sediment, one of the most difficult sample types with which to perform successful FISH. By simultaneous mRNA FISH and rRNA FISH, single cells are identified and shown to express a particular gene. Our protocol is transferable to many different types of samples with the need for only minor modifications of fixation and permeabilization procedures.     

The Effect of Hydraulic Loading Rate and Influent Source on the Binding Capacity of Phosphorus Filters

Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 2² factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m⁻² d⁻¹ decreased P binding capacity from 1.152 to 0.070 g kg⁻¹ for wastewater filters and from 1.382 to 0.300 g kg⁻¹ for phosphate solution filters. At a loading rate of 100 L m⁻² d⁻¹, the average P binding capacity of wastewater filters was 1.152 g kg⁻¹ as opposed to 1.382 g kg⁻¹ for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter.     

Influence of drought on plant performance through changes in belowground tritrophic interactions

Climate change is predicted to increase the risk of drought in many temperate agroecosystems. While the impact of drought on aboveground plant‐herbivore‐natural enemy interactions has been studied, little is known about its effects on belowground tritrophic interactions and root defense chemistry. We investigated the effects of low soil moisture on the interaction between maize, the western corn rootworm (WCR, Diabrotica virgifera), and soil‐borne natural enemies of WCR. In a manipulative field experiment, reduced soil moisture and WCR attack reduced plant performance and increased benzoxazinoid levels. The negative effects of WCR on cob dry weight and silk emergence were strongest at low moisture levels. Inoculation with entomopathogenic nematodes (EPNs, Heterorhabditis bacteriophora) was ineffective in controlling WCR, and the EPNs died rapidly in the warm and dry soil. However, ants of the species Solenopsis molesta invaded the experiment, were more abundant in WCR‐infested pots and predated WCR independently of soil moisture. Ant presence increased root and shoot biomass and was associated with attenuated moisture‐dependent effects of WCR on maize cob weight. Our study suggests that apart from directly reducing plant performance, drought can also increase the negative effects of root herbivores such as WCR. It furthermore identifies S. molesta as a natural enemy of WCR that can protect maize plants from the negative impact of herbivory under drought stress. Robust herbivore natural enemies may play an important role in buffering the impact of climate change on plant‐herbivore interactions.     

Diurnal Variation of Cell Proliferation in Three Bacterial Taxa from Coastal North Sea Waters

Pulse-labeling with bromodeoxyuridine (BrdU) in combination with fluorescence in situ hybridization was applied to quantify the percentage of proliferating cells in coastal North Sea waters. In order to assess diurnal variability, we sampled eight or nine times, respectively, within 3 consecutive days at two seasons. Bacteria affiliated with the Roseobacter, SAR86, and NOR5 lineages constituted on average 19% ± 3%, 8% ± 2%, and 6% ± 1% of all cells in May 2002 and 17% ± 3%, 10% ± 2%, and 11% ± 3% in August. The relative abundances of the three populations either remained stable, or they changed very gradually during the observation periods. On average, 38 and 39% of all Bacteria exhibited DNA de novo synthesis in May and August, respectively. The fractions of proliferating cells in bacteria of the SAR86 (May, 59%; August, 72%) and the Roseobacter (48 and 53%) lineages were significantly above the community average. A substantial cell proliferation of population NOR5 (34%) was only encountered in August, concomitant with a dinoflagellate bloom. Significant short-term fluctuations of DNA-synthesizing cells were observed in Roseobacter during May and in NOR5 during August, hinting at a pronounced (temporal or spatial) mesoscale patchiness of growth rates in these populations. Since the BrdU proliferation assay is susceptible to misinterpretation, we also modeled the expected number of labeled cells at increasing BrdU incubation times in a slowly growing bacterial population. We suggest that the absence of visible DNA synthesis in marine bacterioplankton cells after DNA pulse-labeling must not be interpreted as an indication of cell “inactivity.”     

Extensive carbon isotopic heterogeneity among methane seep microbiota

To assess and study the heterogeneity of δ¹³C values for seep microorganisms of the Eel River Basin, we studied two principally different sample sets: sediments from push cores and artificial surfaces colonized over a 14 month in situ incubation. In a single sediment core, the δ¹³C compositions of methane seep-associated microorganisms were measured and the relative activity of several metabolisms was determined using radiotracers. We observed a large range of archaeal δ¹³C values (> 50‰) in this microbial community. The δ¹³C of ANME-1 rods ranged from −24‰ to −87‰. The δ¹³C of ANME-2 sarcina ranged from −18‰ to −75‰. Initial measurements of shell aggregates were as heavy as −19.5‰ with none observed to be lighter than −57‰. Subsequent measurements on shell aggregates trended lighter reaching values as ¹³C-depleted as −73‰. The observed isotopic trends found for mixed aggregates were similar to those found for shell aggregates in that the initial measurements were often enriched and the subsequent analyses were more ¹³C-depleted (with values as light as −56‰). The isotopic heterogeneity and trends observed within taxonomic groups suggest that ANME-1 and ANME-2 sarcina are capable of both methanogenesis and methanotrophy. In situ microbial growth was investigated by incubating a series of slides and silicon (Si) wafers for 14 months in seep sediment. The experiment showed ubiquitous growth of bacterial filaments (mean δ¹³C = −38 ± 3‰), suggesting that this bacterial morphotype was capable of rapid colonization and growth.     

Degeneration pattern in somatic embryos of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.

Somatic embryos can be used for propagating forest trees vegetatively, which is of great importance for capturing the genetic gain in breeding programs. However, many economically important Pinus species are difficult or impossible to propagate via somatic embryogenesis. In order to get a better understanding of the difficulties to propagate Pinus species via somatic embryogenesis, we are studying the developmental pathway of somatic embryos in different cell lines. In a previous study, we showed that the morphology of early somatic embryos in Scots pine (Pinus sylvestris) differs between cell lines giving rise to normal or abnormal cotyledonary embryos. In this study, we have compared the proliferation and degeneration pattern of early and late embryos in a normal and abnormal cell line. In both cell lines, a high frequency of the embryos degenerated. Among the degenerating embryos, two main degeneration patterns could be distinguished. In the normal cell line, the embryos degenerated similar to how the subordinate embryos are degraded in the seed. In the abnormal cell line, the degeneration of the embryos resulted in a continuous loop of embryo degeneration and differentiation of new embryos. We observed a similar degeneration pattern when embryogenic tissue was initiated from megagametophytes containing zygotic embryos at the stage of cleavage polyembryony. Based on our results, we suggest that the degeneration pattern in abnormal cell lines starts during initiation of embryogenic cultures.