Corticotropin-Releasing Hormone Affects Short Immobilization Stress-Induced Changes in Lung Cytosolic and Membrane Glucocorticoid Binding Sites

Glucocorticoids act via glucocorticoid receptors (GR), typically localized in the cytosol (cGR). Rapid action is probably mediated via membrane receptors (mGR). In corticotropin-releasing hormone knockouts (CRH-KO), basal plasma glucocorticoid levels do differ from wild type levels (WT), but are approximately ten times lower during exposure to immobilization stress (IMMO) in comparison to WT. We tested the following hypotheses: (1) the mice lung tissue GR basal numbers would not be changed in CRH-KO (because of similar glucocorticoid levels), (2) the number of GR would be changed in WT but not in KO during short (30, 90, and 120 min) IMMO (because of higher increase of glucocorticoid levels in WT). The basal levels of cGR were not changed in CRH-KO (compared to WT), while mGR were significantly lower (62 %) in CRH-KO. In WT, there was the only decrease (to 32 %) in cGR after 120 min when we also found an increase in mGR in WT (to 201 %). In CRH-KO, IMMO caused gradual decrease in cGR (to 52 % after 30 min, to 46 % after 90 min, and to 32 % after 120 min). In CRH-KO, the only increase in mGR appeared already at 30 min of IMMO. These data suggest, on the contrary to our hypotheses, that CRH-KO are more susceptible to GR changes in early phases of stress.     

<Emphasis Type="Italic">Daphnia galeata</Emphasis> in the deep hypolimnion: spatial differentiation of a “typical epilimnetic” species

One of the most serious threats to tropical mangrove ecosystems caused by shrimp farming activities is the poor management of pond waste materials. We hypothesise that mangroves can tolerate chemical residues discharged from shrimp farms and can be used as biofilters, but the capability of mangroves to cope with solid sediments dredged from shrimp ponds is limited. Our study in Pak Phanang, Thailand, confirmed that the excess sediments discharged from nearby shrimp ponds reduced mangrove growth rates and increased mortality rates. A series of transformed multi-temporal satellite images was used in combination with the field data to support this claim. In addition, a comparison between four dominant mangrove species revealed that Avicennia marina could tolerate sedimentation rates of >6 cm year⁻¹, while Bruguiera cylindrica tolerated sedimentation rates of 5 cm year⁻¹ (total sediment depth = 25 cm) before dying, while Excoecaria agallocha and Lumnitzera racemosa performed intermediate. This outcome implied that in our situation A. marina and to lesser extent E. agallocha and L. racemosa could be more effective as biofilters than B. cylindrica, as they may survive the sedimentation longer in the disposal areas. Further studies on the impact of sedimentation and chemical pollution of shrimp farm wastes on mangrove mortality and growth are required.     

Do cyanobacterial lipids contain fatty acids longer than 18 carbon atoms?

Fatty acids of twelve species of cyanobacteria grown under different photoautotrophic conditions were studied and their composition was compared with literature data of many other species. We have come to the conclusion that the lipids of cyanobacteria do not contain fatty acids with a chain longer than 18 carbon atoms. In our opinion, omission of an analytical procedure, i.e. purification of fatty acid methyl esters before gas chromatography, leads to incorrect interpretation of the results. Absence or presence of fatty acids was suggested as a useful taxonomic marker and a proper diagnostic indicator in the commercial application of cyanobacterial biomass.     

Bifidobacteria-mediated immune system imprinting early in life

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An Atypical Tubulin Kinase Mediates Stress-Induced Microtubule Depolymerization in Arabidopsis

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Fine-scale genetic analysis of Daphnia host populations infected by two virulent parasites - strong fluctuations in clonal structure at small temporal and spatial scales

Numerous theoretical studies suggest that parasites impose a strong selection pressure on their host, driving genetic changes within host populations. Yet evidence of this process in the wild is scarce. In the present study we surveyed, using high resolution microsatellite markers, the genetic structure of cyclically parthenogenetic Daphnia hosts within two different Daphnia communities belonging to the Daphnia longispina hybrid complex. One community, consisting of a single host species, was infected with the protozoan parasite Caullerya mesnili. The second community consisted of two parental Daphnia spp. and their hybrids, and was infected with the yeast parasite Metschnikowia. Significant differences in the clonal composition between random and infected sub-samples of Daphnia were detected on several occasions within both communities, indicating that host genotypes differ in resistance to both parasites. In addition, one parental species in the multi-taxon community was consistently under-infected, compared with the other taxa. Overall, our field data confirm that infection patterns are strongly affected by host genetic composition in various Daphnia-microparasite systems. Thus, parasite-driven selection operates in natural Daphnia populations and microparasites influence the clonal structure of host populations.     

Carbonic anhydrase inhibitors: Inhibition of the tumor-associated isozymes IX and XII with polyfluorinated aromatic/heterocyclic sulfonamides

The tumor-associated transmembrane carbonic anhydrase (CA, EC 4.2.1.1) isozymes IX (CA IX) and XII (CA XII) are involved in acidification of hypoxic tumors, a process correlated with poor prognosis and clinical outcome of patients harboring such tumors. This process may be reversed by inhibiting these enzymes with potent sulfonamide/sulfamate inhibitors. A series of such aromatic/heterocyclic sulfonamides incorporating 2,3,5,6-tetrafluorobenzoyl-, 2,3,5,6-tetrafluorophenylsulfonyl- and pentafluorophenylureido moieties has been investigated for its interaction with the catalytic domain of the human isozymes hCA IX and hCA XII. Some of these compounds showed excellent inhibitory properties against both isozymes IX and XII, with several subnanomolar inhibitors detected for the first time. These sulfonamides may constitute valuable candidates for the development of novel antitumor therapies based on the inhibition of such tumor-associated CA isozymes.     

Spatial distribution of the Daphnia longispina species complex and other planktonic crustaceans in the heterogeneous environment of canyon-shaped reservoirs

Canyon-shaped reservoirs are often characterised by longitudinalgradients of environmental factors (including trophic level,phytoplankton and zooplankton biomass and abundance of planktivorousfish) affecting the taxonomic composition of the pelagic community.We tested the hypothesis that the spatial distribution of differentspecies and interspecific hybrids of the Daphnia longispinaspecies complex is non-random under such conditions. Duringthe summer stratification, we sampled crustacean zooplanktonfrom 11 reservoirs, covering both longitudinal (upstream, middle,dam) and vertical (epi-, meta- and hypolimnion) environmentalgradients. Allozyme electrophoresis was used to discriminateamong different Daphnia taxa. All three frequently hybridizingEuropean species of the complex (galeata, cucullata, longispina= hyalina) and hybrids with Daphnia galeata were commonly recorded.Smaller-bodied Daphnia cucullata and its hybrids, when present,preferred mostly the nutrient- and food-rich upstream regions;D. longispina and its hybrids were more commonly found in thedownstream part, and often dominated in the meta- or hypolimnion.Redundancy analyses confirmed significant differences in theDaphnia taxon composition, as well as in spatial distributionof other crustacean species, along both gradients. For the firsttime, we demonstrate regular patterns in the horizontal distributionof Daphnia species and hybrids within a water body, thus acceptingour hypothesis. Such spatial distributional patterns may stronglyimpact local hybridization processes.     

Sources and pathways of spread of vancomycin-resistant enterococci in hemato-oncological patients

The presented study aims at analyzing an increasing prevalence of vancomycin-resistant enterococci (VRE) isolated from various kinds of clinical material obtained from patients in the Department of Hemato-oncology (DHO), University Hospital in Olomouc, Czech Republic. Between January 1 and March 31, 2005, enterococci were isolated by standard microbiological procedures using both clinical material obtained from hospitalized patients and samples from the department environment. Resistance to vancomycin and teicoplanin was determined by a standardized microdilution method. Phenotype determination of resistance to vancomycin was verified by PCR detection of vanA and vanB genes. In VanA Enterococcus faecium, macrorestriction analysis was performed by pulsed-field gel electrophoresis. During the monitored period, a total of 128 Enterococcus sp. strains were isolated, of which 38 (30 %) isolates from 22 different patients were determined as VRE. Dominating were Enterococcus faecium VanA (63 %) and Enterococcus casseliflavus VanC (16 %) strains. At the same time, one Enterococcus faecium VanA strain was acquired from a bed-side table used by a patient in whom a similar strain had been isolated repeatedly from various clinical materials including a rectal swab taken in 2004. Based on the macrorestriction analysis of genome DNA in 24 vancomycin-resistant Enterococcus faecium VanA strains isolated from the patients' clinical material, one strain from the bed-side table surface and one strain isolated from stools in 2004, 8 unique restriction profiles with similarity ranging from 90 % to 100 % were identified, which could be classified into 3 clonal types. Thus, we can assume not only the endogenous origin of the VRE in hemato-oncological patients and their potential selection caused by therapy with broad-spectrum antibiotics but also the ability of the strains to survive in a hospital setting and, subsequently, to be spread clonally by various vectors.