Comparison of the adaptive potential of the Arthrobacter oxydans and Acinetobacter lwoffii isolates from permafrost sedimentary rock and the analogous collection strains

A comparative study was conducted on the adaptive mechanisms of the strains Arthrobacter oxydans K14 and Acinetobacter lwoffii EK30A isolated from permafrost subsoil sediments and of those of the analogous collection strains (Ac-1114 Type and BSW-27, respectively). In each pair of the strains compared, the strains differed in terms of (i) growth-related, physiological, and biochemical properties; (ii) resistance to stress factors; (iii) capacity for generation of dormant forms (DFs) under growth arrest conditions, and (iv) intrapopulation production of phase variants. The strains isolated from permafrost displayed a lower growth rate but were more resistant to repeated freezing-thawing treatment than the collection strains. Under the same growth conditions, the permafrost strains formed larger numbers of cystlike anabiotic DFs, extraordinarily small cells, and forms that became nonculturable during long-term storage. Resuscitation of the nonculturable forms resulted in a 2- to-7-fold increase in the percentage of FISH-detectable metabolically active cells. The permafrost strains were also distinguished by increased genome lability. This facilitated their dissociation into intrapopulation variants with phenotypically distinct colonial and morphological properties and different antibiotic resistance. The phenotypic variability was more prominent in Arthrobacter (for which it was not reported previously) than in Acinetobacter. In the populations produced by plating the dormant bacterial forms, the qualitative and quantitative characteristics of the phase variant spectra varied depending on the formation conditions and the composition of the solid media used for the plating. Thus, the permafrost isolates of A. oxydans and Ac. lwoffii were distinguished from their collection analogs by a more manifest adaptive potential including stress resistance, the intensity of DF generation under growth arrest conditions, and increased intrapopulation variability.     

Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi

Trypanosoma evansi contains protein kinases capable of phosphorylating endogenous substrates with apparent molecular masses in the range between 20 and 205 kDa. The major phosphopolypeptide band, pp55, was predominantly localized in the particulate fraction. Anti-alpha and anti-beta tubulin monoclonal antibodies recognized pp55 by Western blot analyses, suggesting that this band corresponds to phosphorylated tubulin. Inhibition experiments in the presence of emodin, heparin, and 2,3-bisphosphoglycerate indicated that the parasite tubulin kinase was a casein kinase 2 (CK2)-like activity. GTP, which can be utilized instead of ATP by CK2, stimulated rather than inactivated the phosphorylation of tubulin in the parasite homogenate and particulate fraction. However, GTP inhibited the cytosolic CK2 responsible for phosphorylating soluble tubulin and other soluble substrates. Casein and two selective peptide substrates, P1 (RRKDLHDDEEDEAMSITA) for casein kinase (CK1) and P2 (RRRADDSDDDDD) for CK2, were recognized as substrates in T. evansi. While the enzymes present in the soluble fraction predominantly phosphorylated P1, P2 was preferentially labeled in the particulate fractions. These results demonstrated the existence of CK1-like and CK2-like activities primarily located in the parasite cytosolic and membranous fractions, respectively. Histone II-A and kemptide (LRRASVA) also behaved as suitable substrates, implying the existence of other Ser/Thr kinases in T. evansi. Cyclic AMP only increased the phosphorylation of histone II-A and kemptide in the cytosol, demonstrating the existence of soluble cAMP-dependent protein kinase-like activities in T. evansi. However, no endogenous substrates for this enzyme were identified in this fraction. Further evidences were obtained by using PKI (6-22), a reported inhibitor of the catalytic subunit of mammalian cAMP-dependent protein kinases, which specifically hindered the cAMP-dependent phosphorylation of histone II-A and kemptide in the parasite soluble fraction. Since the sum of the values obtained in the parasite cytosolic and particulate fractions were always higher than the values observed in the total T. evansi lysate, the kinase activities examined here appeared to be inhibited in the original extract.     

Pure partial trisomy 6p due to a familial insertion (16;6)(p12;p21.2p23)

There have only been eight patients with 6p pure trisomy involving different segments: four cases resulted from a translocation or insertion and four were due to an intrachromosomal duplication. We report here the first postnatally ascertained patient with a pure 6p partial trisomy due to an interchromosomal insertion (16;6)(p12;p21.2p23)mat. This rearrangement was confirmed by fluorescent in situ hybridization (FISH) with whole chromosome 6 and 16 painting probes. The clinical findings in the present patient were similar to those observed in previous cases, including craniofacial dysmorphism, minor anomalies, and lack of severe anatomical defects; yet, the unspecificity of many of these features prevented us from delineating the 6p pure trisomy syndrome.     

Activation of PKR causes amyloid ß-peptide accumulation via de-repression of BACE1 expression

BACE1 is a key enzyme involved in the production of amyloid ß-peptide (Aß) in Alzheimer''s disease (AD) brains. Normally, its expression is constitutively inhibited due to the presence of the 5′untranslated region (5′UTR) in the BACE1 promoter. BACE1 expression is activated by phosphorylation of the eukaryotic initiation factor (eIF)2-alpha, which reverses the inhibitory effect exerted by BACE1 5′UTR. There are four kinases associated with different types of stress that could phosphorylate eIF2-alpha. Here we focus on the double-stranded (ds) RNA-activated protein kinase (PKR). PKR is activated during viral infection, including that of herpes simplex virus type 1 (HSV1), a virus suggested to be implicated in the development of AD, acting when present in brains of carriers of the type 4 allele of the apolipoprotein E gene. HSV1 is a dsDNA virus but it has genes on both strands of the genome, and from these genes complementary RNA molecules are transcribed. These could activate BACE1 expression by the PKR pathway. Here we demonstrate in HSV1-infected neuroblastoma cells, and in peripheral nervous tissue from HSV1-infected mice, that HSV1 activates PKR. Cloning BACE1 5′UTR upstream of a luciferase (luc) gene confirmed its inhibitory effect, which can be prevented by salubrinal, an inhibitor of the eIF2-alpha phosphatase PP1c. Treatment with the dsRNA analog poly (I∶C) mimicked the stimulatory effect exerted by salubrinal over BACE1 translation in the 5′UTR-luc construct and increased Aß production in HEK-APPsw cells. Summarizing, our data suggest that PKR activated in brain by HSV1 could play an important role in the development of AD.     

Comparative study on the gametophyte morphology and development of three paramo species of Jamesonia (Pteridaceae,Polypodiopsida)

The sexual phase of three species of Jamesonia (J. imbricata, J. rotundifolia and J. scammaniae) has been studied, from spore germination to gametangia formation, with special attention to the morphological development of prothalli. This is the first work to deal with gametophytes of species in this genus. All three species have trilete, tetrahedrical spores that germinate following the Vittaria type. The developmental pattern of J. imbricata and J. rotundifolia is intermediate between the Adiantum and Ceratopteris types, as the initial mitotic activity is assumed by an obconical apical cell, substituted later by a lateral meristem. In J. scammaniae, no apical cell or lateral meristem is formed, so the prothalli remain ameristic throughout the developmental process. Adult gametophytes are naked and variable in shape, in the same species ranging from typical cordate prothalli to irregularly lobed forms. Gametangia of normal shape and size was observed in both J. imbricata and J. rotundifolia, but not in J. scammaniae. Apogamy could be expected to occur in the genus, a phenomenon to be examined in the future. Comparisons are made with known species of related genera and results are discussed from an ecological perspective in the paramo environment.     

Mutations of the mitochondrial holocytochrome c-type synthase in X-linked dominant microphthalmia with linear skin defects syndrome

The microphthalmia with linear skin defects syndrome (MLS, or MIDAS) is an X-linked dominant male-lethal disorder almost invariably associated with segmental monosomy of the Xp22 region. In two female patients, from two families, with MLS and a normal karyotype, we identified heterozygous de novo point mutations--a missense mutation (p.R217C) and a nonsense mutation (p.R197X)--in the HCCS gene. HCCS encodes the mitochondrial holocytochrome c-type synthase that functions as heme lyase by covalently adding the prosthetic heme group to both apocytochrome c and c(1). We investigated a third family, displaying phenotypic variability, in which the mother and two of her daughters carry an 8.6-kb submicroscopic deletion encompassing part of the HCCS gene. Functional analysis demonstrates that both mutant proteins (R217C and Delta 197-268) were unable to complement a Saccharomyces cerevisiae mutant deficient for the HCCS orthologue Cyc3p, in contrast to wild-type HCCS. Moreover, ectopically expressed HCCS wild-type and the R217C mutant protein are targeted to mitochondria in CHO-K1 cells, whereas the C-terminal-truncated Delta 197-268 mutant failed to be sorted to mitochondria. Cytochrome c, the final product of holocytochrome c-type synthase activity, is implicated in both oxidative phosphorylation (OXPHOS) and apoptosis. We hypothesize that the inability of HCCS-deficient cells to undergo cytochrome c-mediated apoptosis may push cell death toward necrosis that gives rise to severe deterioration of the affected tissues. In summary, we suggest that disturbance of both OXPHOS and the balance between apoptosis and necrosis, as well as the X-inactivation pattern, may contribute to the variable phenotype observed in patients with MLS.     

Sugar feeding protects against arboviral infection by enhancing gut immunity in the mosquito vector Aedes aegypti

As mosquito females require a blood meal to reproduce, they can act as vectors of numerous pathogens, such as arboviruses (e.g. Zika, dengue and chikungunya viruses), which constitute a substantial worldwide public health burden. In addition to blood meals, mosquito females can also take sugar meals to get carbohydrates for their energy reserves. It is now recognised that diet is a key regulator of health and disease outcome through interactions with the immune system. However, this has been mostly studied in humans and model organisms. So far, the impact of sugar feeding on mosquito immunity and in turn, how this could affect vector competence for arboviruses has not been explored. Here, we show that sugar feeding increases and maintains antiviral immunity in the digestive tract of the main arbovirus vector Aedes aegypti. Our data demonstrate that the gut microbiota does not mediate the sugar-induced immunity but partly inhibits it. Importantly, sugar intake prior to an arbovirus-infected blood meal further protects females against infection with arboviruses from different families. Sugar feeding blocks arbovirus initial infection and dissemination from the gut and lowers infection prevalence and intensity, thereby decreasing the transmission potential of female mosquitoes. Finally, we show that the antiviral role of sugar is mediated by sugar-induced immunity. Overall, our findings uncover a crucial role of sugar feeding in mosquito antiviral immunity which in turn decreases vector competence for arboviruses. Since Ae. aegypti almost exclusively feed on blood in some natural settings, our findings suggest that this lack of sugar intake could increase the spread of mosquito-borne arboviral diseases.     

Airborne pollen sampling in Toledo, Central Spain

Toledo is one of the main tourist spots of Spain, attracting around two million visitors per year. Its geographical situation in the vast and scarcely monitored Region of Castilla La Mancha and the high number of tourists (especially in the spring) has resulted in the Spanish Aerobiology Network (REA) making this city a major study objective. Air monitoring studies carried out using REA sampling procedures commenced in October 2002. Thirty-two pollen types were identified during the sampling period (October 2002 to October 2004). The annual Pollen Index (PI) was 44124 for the agricultural year October 2002–October 2003, and 29666 in the same period of 2003–2004. The most abundant taxa were, in decreasing order of dominance: Cupressaceae, Quercus, Poaceae, Populus, Olea, Urticaceae, Platanus, Pinus and Ulmus. Other, less well-represented pollen taxa included Salix, Alnus, Fraxinus and Tamarix, which were characteristic of riverside areas, and Morus, Artemisia and Chenopodiaceae. The presence of Castanea pollen grains originating from chestnut crops far away from the city was clearly an example of long-distance transport. The highest concentrations of airborne pollen were detected from March to May and also in January, due to the flowering of Cupressaceae species. In general, there was a correlation between pollen and meteorological parameters: a positive correlation with temperature and a negative correlation with rainfall and humidity during the pre-peak period. A negative correlation between temperature and some tree pollen taxa was detected in the principal pollen period correlation analysis due to their long pollination periods.     

Microbiological Characteristics and Susceptibility Patterns of Strains of Rhodotorula Isolated from Clinical Samples

The members of the genus Rhodotorula show a marked ubiquity. In man, they have been isolated from faeces, nails, skin, sputum, digestive tract and adenoids, forming part of the normal human flora, although in recent years cases have been reported of both local and systemic infection by this yeast. There are virtually no studies in the literature on the sensitivity of this genus to the antifungal agents in common clinical use. Therefore, it is considered of interest to study the microbiological characteristics and the susceptibility patterns of Rhodotorula isolated from clinical samples. A total of 35 different strains of Rhodotorula were studied. In vitro susceptibility testing to 5-fluorocytosine, amphotericin B, ketoconazole, fluconazole and itraconazole was performed. All the strains were considered sensitive to 5-fluorocytosine, amphotericin B, ketoconazole and itraconazole and resistant to fluconazole. As a conclusion, we can state that all the antifungal agents tested, except fluconazole, are useful medicaments for the treatment of infections by the Rhodotorula genus. This revised version was published online in June 2006 with corrections to the Cover Date.