Monitoring horizontal antibiotic resistance gene transfer in a colonic fermentation model

The human microbiota is suggested to be a reservoir of antibiotic resistance (ABR) genes, which are exchangeable between transient colonizers and residing bacteria. In this study, the transfer of ABR genes from Enterococcus faecalis to Listeria monocytogenes and to commensal bacteria of the human gut microbiota was demonstrated in a colonic fermentation model. In the first fermentation, an E. faecalis donor harboring the marked 50-kb conjugative plasmid pRE25(*) and a chromosomal marker was co-immobilized with L. monocytogenes and infant feces. In this complex environment, the transfer of pRE25(*) to L. monocytogenes was observed. In a second fermentation, only the E. faecalis donor and feces were co-immobilized. Enumeration of pRE25(*) and the donor strain by quantitative PCR revealed an increasing ratio of pRE25(*) to the donor throughout the 16-day fermentation, indicating the transfer of pRE25(*) . An Enterococcus avium transconjugant was isolated, demonstrating that ABR gene transfer to gut commensals occurred. Moreover, pRE25(*) was still functional in both the E. avium and the L. monocytogenes transconjugant and transmittable to other genera in filter mating experiments. Our study reveals that the transfer of a multiresistance plasmid to commensal bacteria in the presence of competing fecal microbiota occurs in a colonic model, suggesting that commensal bacteria contribute to the increasing prevalence of antibiotic-resistant bacteria.     

Diet of ringed seals (Pusa hispida) from Northeast Greenland

The diet of ringed seals (Pusa hispida) from coastal and offshore areas of Northeast Greenland was determined by identifying, to the lowest taxonomic limit possible, all hard-part contents from the gastrointestinal tract of 51 seals sampled (2002–2004) in spring (April to June, N = 35) and autumn (September to October, N = 16). The autumn diet was characterized by high numbers of Parathemisto libellula, and the spring diet was comprised primarily of polar cod (Boreogadus saida), with few invertebrates consumed. The coastal seal diet samples had a diverse fish prey composition (during both the spring and autumn), whereas the open water seals had eaten mostly crustaceans with P. libellula being most abundant. The sample sizes from the various locations and seasons were not large enough to explore age-class effects on diet in addition. Similar to earlier studies, this study suggests that the ringed seal is a generalist that exploits prey based on availability, with a few key species dominating the diet in an area at least on a seasonal basis.     

Cross-sex pattern of bone mineral density in early onset gender identity disorder

Hormonally controlled differences in bone mineral density (BMD) between males and females are well studied. The effects of cross-sex hormones on bone metabolism in patients with early onset gender identity disorder (EO-GID), however, are unclear. We examined BMD, total body fat (TBF) and total lean body mass (TLBM) in patients prior to initiation of sex hormone treatment and during treatment at months 3 and 12. The study included 33 EO-GID patients who were approved for sex reassignment and a control group of 122 healthy Norwegians (males, n=77; females, n=45). Male patients (n=12) received an oral dose of 50 mug ethinylestradiol daily for the first 3 months and 100 mug daily thereafter. Female patients (n=21) received 250 mg testosterone enantate intramuscularly every third week. BMD, TBF and TLBM were estimated using dual energy X-ray absorptiometry (DXA). In male patients, the DXA measurements except TBF were significantly lower compared to their same-sex control group at baseline and did not change during treatment. In female patients, the DXA measurements were slightly higher than in same-sex controls at baseline and also remained unchanged during treatment. In conclusion, this study reports that body composition and bone density of EO-GID patients show less pronounced sex differences compared to controls and that bone density was unaffected by cross-sex hormone treatment.     

Structural characterization and molecular identification of arbuscular mycorrhiza morphotypes of <Emphasis Type="Italic">Alzatea verticillata</Emphasis> (Alzateaceae), a prominent tree in the tropical mountain rain forest of South Ecuador

The vast majority of the highly diverse trees in the tropical mountain rain forest of South Ecuador form arbuscular mycorrhizas, and previous molecular investigations revealed a high diversity of fungi. In this study, we present a first trial to link fungal DNA-sequences with defined morphotypes characterized on the basis of partly new mycelial features obtained from field material of one tree species, Alzatea verticillata. Fine roots were halved lengthwise to study the mycelium anatomy on one half and to obtain fungal nuclear rDNA coding for the small subunit rRNA of Glomeromycota from the other half. Light microscopy revealed conspicuously large amounts of mycelium attaching to the surface of the rootlets. The mycelium formed fine- or large-branched appressoria-like plates, vesicles of regular or irregular shape, and very fine, multibranched structures ensheathed by septate hyphae. These previously undescribed features of the supraradical mycelia combined with intraradical mycelium structures were used for distinguishing of four main morphogroups and subordinate 14 morphotypes. DNA sequences of Glomus group A, Acaulospora and Gigaspora, were obtained and linked to three morphogroups. Two sequence types within Glomus group A could be tentatively associated to subordinate morphotypes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A eucrustacean from the Cambrian ‘Orsten’ of Sweden with epipods and a maxillary excretory opening

The Cambrian species Paulinecaris siveterae n. gen. n. sp., known from two trunk fragments, represents the first record of epipods (serving as gills and osmoregulatory structures) in a crustacean from the Swedish ‘Orsten’. Moreover, it is the first report of the maxillary excretory opening of a crustacean based on Cambrian material of ‘Orsten’‐type preservation. One specimen comprises the maxillary segment with an appendage and several thoracic segments with parts of their limbs; a second specimen is a fragment possibly of a more posterior part of the trunk. As in other known small eucrustaceans, the tergites of the new species lack prominent tergopleurae, so that the limbs insert directly ventral to the tergal margins. Limb preservation includes the maxilla and several thoracopods, all possessing a prominent, fleshy basipod with six setose endites along their median rim distally to the proximal endite. The presence of long and prominent limbs of P. siveterae suggests that it had good swimming ability, while the slight C‐like curvature of their basal limb part, basipod, indicates involvement of the limbs also in so‐called ‘sucking chambers’ for suspension feeding coupled with locomotion. The estimated total length of P. siveterae, 2–3 mm, is comparable to that of extant cephalocarids, but its appendages are twice as long and wide. The limbs of P. siveterae also differ in size and armature from extant eucrustaceans as well as early representatives of this group known from the ‘Orsten’ assemblages. The general morphology of the limbs, for example in having a fleshy and C‐shaped basipod with several setae‐bearing endites medially, identifies P. siveterae as an entomostracan eucrustacean, but a lack of further details precludes its affinity with any of the in‐group taxa. Three epipods on the outer edge of the basipod, as in P. siveterae, are also known from the Cambrian eucrustacean Yicaris dianensis from China and early ontogenetic stages of extant fairy shrimps (Anostraca); their adult stages have two epipods. This hints at an original number of three epipods in the ground pattern of Entomostraca, but some uncertainty remains with regard to the eucrustacean ground pattern because Malacostraca possess a maximum number of two.     

Shedding of glycan‐modifying enzymes by signal peptide peptidase‐like 3 (SPPL3) regulates cellular N‐glycosylation

Protein N‐glycosylation is involved in a variety of physiological and pathophysiological processes such as autoimmunity, tumour progression and metastasis. Signal peptide peptidase‐like 3 (SPPL3) is an intramembrane‐cleaving aspartyl protease of the GxGD type. Its physiological function, however, has remained enigmatic, since presently no physiological substrates have been identified. We demonstrate that SPPL3 alters the pattern of cellular N‐glycosylation by triggering the proteolytic release of active site‐containing ectodomains of glycosidases and glycosyltransferases such as N‐acetylglucosaminyltransferase V, β‐1,3 N‐acetylglucosaminyltransferase 1 and β‐1,4 galactosyltransferase 1. Cleavage of these enzymes leads to a reduction in their cellular activity. In line with that, reduced expression of SPPL3 results in a hyperglycosylation phenotype, whereas elevated SPPL3 expression causes hypoglycosylation. Thus, SPPL3 plays a central role in an evolutionary highly conserved post‐translational process in eukaryotes.     

Antibacterial activity in four marine crustacean decapods

A search for antibacterial activity in different body-parts of Pandalus borealis (northern shrimp), Pagurus bernhardus (hermit crab), Hyas araneus (spider crab) and Paralithodes camtschatica (king crab) was conducted. Dried samples were extracted with 60% (v/v) acetonitrile, containing 0.1% (v/v) trifluoroacetic acid, and further extracted and concentrated on C18 cartridges. Eluates from the solid phase extraction were tested for antibacterial, lysozyme and haemolytic activity. Antibacterial activity against Escherichia coli, Vibrio anguillarum, Corynebacterium glutamicum and Staphylococcus aureus was detected in extracts from several tissues in all species tested, but mainly in the haemolymph and haemocyte extracts. V. anguillarum and C. glutamicum were generally the most sensitive micro-organisms. In P. borealis and P. bernhardus most of the active fractions were not affected by proteinase K treatment, while in H. araneus and P. camtschatica most fractions were sensitive to proteinase K treatment, indicating antibacterial factors of proteinaceous nature. In P. bernhardus the active fractions were generally heat labile, whereas in H. araneus the activities were resistant to heat. Differences between active extracts regarding hydrophobicity and sensitivity for heat and proteinase K treatment indicate that several compounds are responsible for the antibacterial activities detected. Lysozyme-like activity could be detected in some fractions and haemolytic activity against human red blood cells could be detected in haemolymph/haemocyte and exoskeleton extracts from all species tested.     

Anti-Myeloma Activity of Akt Inhibition Is Linked to the Activation Status of PI3K/Akt and MEK/ERK Pathway

The PI3K/Akt/mTOR signal transduction pathway plays a central role in multiple myeloma (MM) disease progression and development of therapeutic resistance. mTORC1 inhibitors have shown limited efficacy in the clinic, largely attributed to the reactivation of Akt due to rapamycin induced mTORC2 activity. Here, we present promising anti-myeloma activity of MK-2206, a novel allosteric pan-Akt inhibitor, in MM cell lines and patient cells. MK-2206 was able to induce cytotoxicity and inhibit proliferation in all MM cell lines tested, albeit with significant heterogeneity that was highly dependent on basal pAkt levels. MK-2206 was able to inhibit proliferation of MM cells even when cultured with marrow stromal cells or tumor promoting cytokines. The induction of cytotoxicity was due to apoptosis, which at least partially was mediated by caspases. MK-2206 inhibited pAkt and its down-stream targets and up-regulated pErk in MM cells. Using MK-2206 in combination with rapamycin (mTORC1 inhibitor), {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 (PI3K inhibitor), or U0126 (MEK1/2 inhibitor), we show that Erk- mediated downstream activation of PI3K/Akt pathway results in resistance to Akt inhibition. These provide the basis for clinical evaluation of MK-2206 alone or in combination in MM and potential use of baseline pAkt and pErk as biomarkers for patient selection.