Evidence Of Colonization Research Articles

Emergence of pandrug-resistant carbapenemase-producing Enterobacterales in dogs and cats: a cross-sectional study in Egypt.

One of the most important emerging health problems is the increasing role of animals in the rapid global rise in resistance to last-resort antibiotics, such as carbapenems. However, there is limited information on the role of pet animals in harboring and spreading pandrug-resistant (PDR) carbapenemase-producing Enterobacterales (CPE), especially in Egypt. This cross-sectional study was conducted to screen for CPE in healthy and diseased pets using phenotypic and molecular methods and the NG-Test CARBA 5 immunochromatographic assay. Rectal swabs were collected from 62 dogs and 48 cats, incubated overnight in tryptic soy broth containing 10 μg of meropenem disc and subsequently cultured on MacConkey agar supplemented with meropenem (1 mg/L). Sixty-six isolates (60.6%), including 56 Klebsiella pneumoniae, seven Escherichia coli, and three K. oxytoca isolates, were confirmed to be carbapenem-resistant Enterobacterales (CRE) by the disc diffusion method, broth microdilution test, CNPt-direct, and PCR assay targeting carbapenemase genes. Forty-three (65.2%) dogs and 23 (34.8%) cats carried CPE. Of these, 35 (70.0%) were healthy (including 27 dogs and 8 cats) and 31 (52.5%) were diseased (including 16 dogs and 15 cats). bla OXA-181 was the most common gene detected (42/66, 63.6%), followed by bla IMP (40/66, 60.6%), bla OXA-48-like (29/66, 43.9%), bla KPC and bla VIM (20/66, 30.3% each), and bla NDM (17/66, 25.8%). The identified genotypes were bla KPC-2, bla IMP-1, bla VIM-1, bla NDM-1, and bla NDM-5. The CARBA 5 assay showed higher sensitivity and specificity for the detection of NDM, OXA and KPC than that for VIM and IMP genes. Antimicrobial resistance profiles of CRE isolates revealed 20 PDR, 30 extensively drug-resistant (XDR), and 16 multidrug-resistant (MDR) phenotypes. This study provides evidence of colonization with PDR CPE in dogs and cats. To manage the infection or colonization of pets in veterinary clinical settings, extended surveillance systems should be considered, and the use of critical antibiotics should be strictly controlled.

Phylogeography of the Korean endemic Coreoleuciscus (Cypriniformes: Gobionidae): the genetic evidence of colonization through Eurasian continent to the Korean Peninsula during Late Plio-Pleistocene

BackgroundFreshwater endemism is thought to have been formed through the vicariance of connected water systems or the process by which ancestral populations colonized specific areas. The Korean Peninsula is well recognized for its high level of freshwater endemism with about 40% of freshwater fish species being endemic.ObjectiveIn this study, we attempted to reconstruct the process of speciation and phylogenetic dispersal of Coreoleuciscus species, which is endemic in the Korean Peninsula.MethodsWe used fossil-calibrated divergence time estimation and ancestral distributional reconstruction to infer phylogeographic reconstruction of Coreoleuciscus based on mitochondrial cytochrome c oxidate subunit I (COI) sequences (1551 bp).ResultsOur phylogeographic analysis based on a total of 626 individuals revealed that the two Coreoleuciscus species have originated from the independent colonization of different lineages in the ancestral populations, probably during the Late Plio-Pleistocene. The full-scale expansion of Coreoleuciscus populations appears to have taken place after major river structures were completed on the Korean Peninsula. We also provided evidence that the common ancestors of Coreoleuciscus was distributed in Eastern Eurasian continent and subsequently dispersed into the tip of East Asia. High genetic diversity was mainly concentrated in large drainage populations, while small populations showed an monomorphism, which could give important implications for planning the conservation and management of Coreoleuciscus.ConclusionsThe phylogenetic background of the rheophilic Coreoleuciscus species can be explained by the colonizer hypothesis that the endemic freshwater fish originated from the common ancestor in continental region.

Effects of the seasonal availability of freshly cut logs and tree species on the early response of saproxylic insects in boreal forest

Deadwood left on site after logging can be colonized by many saproxylic insects including xylophagous species that can damage the wood. This study aims to estimate the risks resulting from the storage of logs at the edge of balsam fir-white birch stands. We used taxonomic richness, as well as visitation and colonization rates of saproxylic insects to determine how their use of freshly cut logs varies with the seasonal availability of logs and the tree species. During the summer of 2019, balsam fir, black spruce, and paper birch logs were experimentally cut at three different periods and were placed in four harvested sites located in the Forêt Montmorency experimental forest in eastern Quebec, Canada. Visitation and colonization rates were assessed using trunk-window traps and log dissection, respectively. A total of 854 saproxylic insects belonging to 53 genera were captured over the three months of sampling. The logs were colonized by xylophagous species within one month after tree death. These xylophagous insects belonged mainly to the species Urocerus prob. albicornis, and Monochamus prob. scutellatus. Colonization rates of logs by Monochamus prob. scutellatus were higher from mid-July to mid-September than earlier during the season. These xylophagous species also responded to tree species, with higher abundance on conifers than on white birch both in terms of visitation and colonization rates. Furthermore, there was no evidence of colonization on paper birch. Our results suggest that a prompt harvesting of conifer logs between mid-July and mid-September on harvested sites will minimize damage to freshly cut logs.

Archaeological landscape, settlement dynamics, and sociopolitical organization in the Chactún area of the central Maya Lowlands.

Until recently, an extensive area in the central lowlands of the Yucatán peninsula was completely unexplored archaeologically. In 2013 and 2014, during initial surveys in the northern part of the uninhabited Calakmul Biosphere Reserve in eastern Campeche, Mexico, we located Chactún, Tamchén and Lagunita, three major Maya centers with some unexpected characteristics. Lidar data, acquired in 2016 for a larger area of 240 km2, revealed a thoroughly modified and undisturbed archaeological landscape with a remarkably large number of residential clusters and widespread modifications related to water management and agriculture. Substantial additional information was obtained through field surveys and test excavations in 2017 and 2018. While hydraulic and agricultural features and their potential for solving various archaeologically relevant questions were discussed in a previous publication, here we examine the characteristics of settlement patterns, architectural remains, sculpted monuments, and ceramic evidence. The early Middle Preclassic (early first millennium BCE) material collected in stratigraphic pits at Tamchén and another locale constitutes the earliest evidence of colonization known so far in a broader central lowland area. From then until the Late Classic period, which was followed by a dramatic demographic decline, the area under study witnessed relatively constant population growth and interacted with different parts of the Maya Lowlands. However, a number of specific and previously unknown cultural traits attest to a rather distinctive regional development, providing novel information about the extent of regional variation within the Maya culture. By analyzing settlement pattern characteristics, inscriptional data, the distribution of architectural volumes and some other features of the currently visible archaeological landscape, which largely reflects the Late Classic situation, we reconstruct several aspects of sociopolitical and territorial organization in that period, highlighting similarities with and differences from what has been evidenced in the neighboring Río Bec region and elsewhere in the Maya area.

Validation of the Giannella Risk Score for the Prediction of Infection by Carbapenemase-producing Enterobacteriaceae in the Pediatric Population.

Despite efforts made to prevent the spread of multi-drug-resistant bacteria, carbapenemase-producing Enterobacteriaceae (CPE) has become one of the most dangerous threat worldwide. However, data on the epidemiology of CPE and on the correlation between CPE colonization and infection are scanty. The objectives of this study were first to describe the epidemiologic characteristics of colonizations and invasive CPE infections in the pediatric population, and second, to apply the Giannella Risk Score (GRS) to the pediatric population for the assessment of the risk of invasive CPE infection in patients with already known colonization. Pediatric patients with evidence of colonization by CPE were retrospectively enrolled. For each colonized patient, the subsequent development of an infection by CPE was then assessed for a 90-day period after the first CPE isolation; GRSs were compared between patients who had developed any type of CPE infection and those without infection. A total of 215 patients (113 males and 102 females) with at least 1 isolation of CPE during hospitalization were analyzed. Median age was 5.6 years [interquartile range (IQR), 1.89-12.2 years]. Overall, 28 CPE infections (13%) were documented: 23 blood stream infections and 5 complicated urinary tract infections. The 30-day mortality of invasive CPE infections was 34.8%. The GRS values in patients with any CPE infection were statistically higher than in noninfected patients: median GRS 9 (IQR, 4-12.5) versus 4 (IQR, 2-4), respectively; P < 0.0001. The analysis of the receiver operating characteristic curves identified a GRS cut-off value ≥8 as the best predictor of CPE infection. The likelihood ratio of the results was <2 and the informedness of the test had a value <0.50. Our study confirms that the spread of CPE is an impelling problem also in the pediatric population, with a high mortality rate of invasive infections. However, the application of the GRS appears to be poorly informative in the pediatric setting; it might sometimes help to identify patients at very low-risk of CPE infection, in whom it is reasonable to spare targeted antimicrobial treatments.

Temporal changes in seabird assemblage structure and trait diversity in the Rapa Nui (Easter Island) multiple‐use marine protected area

AbstractFor Rapa Nui (Easter Island) and its largest islet, Motu Nui, the change of the species assemblage over time was analysed, and a trait‐based approach to evaluate the potential losses in seabird function across the past centuries was applied. At a finer scale, the seasonal changes in seabird species composition in the current seabird assemblage was assessed to better understand the dynamics of the long‐term inferred patterns.For Rapa Nui, the composition of the seabird assemblage between the prehistorical, historical, and current time has changed significantly. The most critical change, probably associated with human colonization, was observed between prehistoric and current times. The current diminished number of nesting seabird species was probably the result of local extirpation without evidence of colonization by new species.For Motu Nui, changes in species composition were also followed by changes in trait structure, which were smaller than observed in Rapa Nui. This is probably due to the presence of a relatively high number of related species (i.e. Procellariids) with high similarities in their foraging behaviour.The nesting seabird assemblages in Rapa Nui and Motu Nui differ in exposure to risk; thus, conservation strategies applied to the islands should be planned on a fine spatial scale. For Rapa Nui, which is an urban wildlife area with several invasive species and a low number of remaining native seabird species, management should focus on fencing and pets control. For Motu Nui, management should instead focus on the establishment of quarantine and other biosecurity tools to avoid both the entry and proliferation of new invasive species.

Deciphering interfungal relationships in the 410-million-yr-old Rhynie chert: Brijax amictus gen. et sp. nov. (Chytridiomycota) colonizing the walls of glomeromycotan acaulospores

Glomeromycotan spores from the Early Devonian Rhynie chert frequently contain evidence of colonization by other fungi. However, relatively few of these relationships have been described and evaluated. Brijax amictus gen. et sp. nov., a probable chytrid (Chytridiomycota) associated with certain thick-walled archaeosporalean acaulospores from the Rhynie chert, develops largely within the host spore wall. Thalli are eucarpic, monocentric, 16.5–40(−50) μm high, and consist of an inoperculate sporangium (zoosporangium or resting spore stage) located in the outer, ephemeral spore wall component, and a rhizoidal system that extends into the persistent spore wall. Sporangia that, at maturity, are completely surrounded by the host spore wall develop a prominent discharge tube, whereas ones not covered by the host wall have simple openings or pores. Thallus morphology resembles certain present-day species of Rhizophydium (Rhizophydiales) and Phlyctochytrium (Chytridiales); however, the systematic affinities of B. amictus remain unresolved. This discovery contributes to the understanding of the various levels of interfungal relationship that existed in early terrestrial ecosystems.

The intersection and parallels of Aboriginal peoples’ and racialized migrants’ experiences of colonialism and child welfare in Canada

Aboriginal children are chronically overrepresented across all points in the child welfare system in Canada. Parallels between the racialized migrant experience and the injustices experienced by Aboriginal peoples are reviewed, starting with the development of Canada as a nation and reviewing colonialism and racism as it relates to Aboriginal peoples’ and racialized migrants’ experiences with child welfare. This comparative analysis will illuminate how injustices continue to be reproduced, focusing on the child welfare system, as part of the devastating effects that colonization has on Aboriginal peoples, but also as evidence of colonization being reproduced through current discriminatory legislation and practices.

Impact of the Mk VI SkinSuit on skin microbiota of terrestrial volunteers and an International Space Station-bound astronaut

Microgravity induces physiological deconditioning due to the absence of gravity loading, resulting in bone mineral density loss, atrophy of lower limb skeletal and postural muscles, and lengthening of the spine. SkinSuit is a lightweight compression suit designed to provide head-to-foot (axial) loading to counteract spinal elongation during spaceflight. As synthetic garments may impact negatively on the skin microbiome, we used 16S ribosomal RNA (rRNA) gene amplicon procedures to define bacterial skin communities at sebaceous and moist body sites of five healthy male volunteers undergoing SkinSuit evaluation. Each volunteer displayed a diverse, distinct bacterial population at each skin site. Short (8 h) periods of dry hyper-buoyancy flotation wearing either gym kit or SkinSuit elicited changes in the composition of the skin microbiota at the genus level but had little or no impact on community structure at the phylum level or the richness and diversity of the bacterial population. We also determined the composition of the skin microbiota of an astronaut during pre-flight training, during an 8-day visit to the International Space Station involving two 6–7 h periods of SkinSuit wear, and for 1 month after return. Changes in composition of bacterial skin communities at five body sites were strongly linked to changes in geographical location. A distinct ISS bacterial microbiota signature was found which reversed to a pre-flight profile on return. No changes in microbiome complexity or diversity were noted, with little evidence for colonisation by potentially pathogenic bacteria; we conclude that short periods of SkinSuit wear induce changes to the composition of the skin microbiota but these are unlikely to compromise the healthy skin microbiome.

Turnover Dynamics of Breeding Land Birds on Islands: is Island Biogeographic Theory ‘True but Trivial’ over Decadal Time-Scales?

The theory of island biogeography has revolutionised the study of island biology stimulating considerable debate and leading to the development of new advances in related areas. One criticism of the theory is that it is ‘true but trivial’, i.e., on the basis of analyses of annual turnovers of organisms on islands, it has been posited that stochastic turnover mainly comprises rare species, or repeated immigrations and extinctions thereof, and thereby contribute little to the overall ecological dynamics. Here, both the absolute and relative turnover of breeding land birds are analysed for populations on Skokholm, Wales, over census intervals of 1, 3, 6, 12, and 24 years. As expected, over short census intervals (≤6 years), much of the turnover comprised repeated colonisations and extinctions of rare species. However, at longer intervals (12 and 24 years), a sizeable minority of species (11% of the total recorded) showed evidence of colonisation and/or extinction events despite sizeable populations (some upwards of 50 pairs). These results suggest that a longer-term view is required to take into account turnover involving more common species.

New petrified calamitaleans from the Permian of the Parnaíba Basin, central-north Brazil, part II, and phytogeographic implications for late Paleozoic floras

Continuing palaeofloristic studies in the Northern Tocantins Fossil Forest, we describe two new calamitalean species from the Permian of the Parnaíba Basin (central-north Brazil). The fossils comprise axes of various sizes, preserved anatomically as siliceous petrifactions, and found in highly mature sandy fluvial deposits of the Motuca Formation. Based on anatomical and morphological characteristics, Arthropitys tocantinensis sp. nov. and Arthropitys barthelii sp. nov. are described. They share a small central pith cavity (extremely reduced in the latter), scalariform tracheid pitting, and prominent pitting of the ray parenchyma. However, they differ markedly in their branching system: the former having 3–12 branches per node either with or lacking secondary growth, the latter showing 2–17 branches without any secondary growth. However, in A. tocantinensis sp. nov., the presence of large woody branches supports a more complex architecture with at least three successive orders of branches. The extensive secondary tissue in both species is homogeneous; clear segmentation is only visible in the proximal wood of A. tocantinensis sp. nov., but completely absent in A. barthelii sp. nov.The growth architecture of these upright growing, self-supporting trunks are reconstructed based on sizable transverse and longitudinal preparations. Our results confirm that thick woody calamitaleans were elements of disturbed riparian vegetation and much more diverse in terms of anatomy and branching patterns than previously thought. They were well adapted to seasonally dry conditions and formed major plant constituents of Permian low-latitude Southern Hemisphere communities. Additionally, we report the first evidence of colonisation on arborescent calamitaleans by herbaceous sphenophyte axes from the Permian. One of the Arthropitys stems hosts at least 30 Sphenophyllum shoots of various ontogenetic stages, growing inside the destroyed pith, which was previously excavated by arthropod boring.Based on the distribution of key genera within late Paleozoic floras of Euramerica, Gondwana and Cathaysia floral realms cluster analysis and Jaccard Coefficient highlight the distribution of a “Mid-North Brazilian” phytogeographic Region during the early Permian.

Advancing Clostridia to Clinical Trial: Past Lessons and Recent Progress.

Most solid cancers contain regions of necrotic tissue. The extent of necrosis is associated with poor survival, most likely because it reflects aggressive tumour outgrowth and inflammation. Intravenously injected spores of anaerobic bacteria from the genus Clostridium infiltrate and selectively germinate in these necrotic regions, providing cancer-specific colonisation. The specificity of this system was first demonstrated over 60 years ago and evidence of colonisation has been confirmed in multiple tumour models. The use of “armed” clostridia, such as in Clostridium Directed Enzyme Prodrug Therapy (CDEPT), may help to overcome some of the described deficiencies of using wild-type clostridia for treatment of cancer, such as tumour regrowth from a well-vascularised outer rim of viable cells. Successful preclinical evaluation of a transferable gene that metabolises both clinical stage positron emission tomography (PET) imaging agents (for whole body vector visualisation) as well as chemotherapy prodrugs (for conditional enhancement of efficacy) would be a valuable early step towards the prospect of “armed” clostridia entering clinical evaluation. The ability to target the immunosuppressive hypoxic tumour microenvironment using CDEPT may offer potential for synergy with recently developed immunotherapy strategies. Ultimately, clostridia may be most efficacious when combined with conventional therapies, such as radiotherapy, that sterilise viable aerobic tumour cells.

MOLD infections in STAT 3 DEFICIENT patients: A NATIONWIDE STUDY IN FRANCE

Autosomal dominant loss of function mutation of signal transducer and activator of transcription 3 (STAT3) gene (STAT3-deficiency) predisposes to recurrent bacterial pneumonia that are complicated in 67% of patients with bronchiectasis, cavitations and Aspergillus infection or colonization in 22% of patients1. We aimed to report the prevalence, describe clinical, mycological, pathological and radiological presentation and both medical and surgical treatment of mold infections in the National French cohort. Methods Referent physicians of STAT3-deficient patients (n= 74 patients) were contacted to know if patients had evidence of colonization or infection with molds. Clinical and mycological information were collected and imaging was centralized. An expert committee reviewed all charts and classified the cases (EC, SP, CT, AD, FL, OL, MOC). Results Eighteen episodes of filamentous fungal infection in ten (13.5%) STAT3-deficient patients were identified. The median age at first episode was 12 years (IQR 10.2–25). Ninety percent of patients had underlying pulmonary disease, bronchiectasis and cavitations, usually multiple. Mold infections were classified as follow: three aspergillomas, six Chronic Pulmonary Aspergillosis (CPA), five Allergic BronchoPulmonary Aspergillosis (ABPA), two mixed forms ABPA and CPA, one Chronic Allergic Sinus Aspergillosis and one Rasamsonia invasive pulmonary infection. According to EORTC/MSG definitions, no cases of invasive aspergillosis were reported. Aspergillus fumigatus was isolated in 13 cases, Rasamsonia argillocea in one case. Aspergillus precipitins were detectable in 86% of cases (12/14). Two-thirds of fungal episodes (12/18) were breakthrough infections (itraconazole prophylaxis in most cases), and half of the cases (9/18) occurred while on immunoglobulin substitutive therapy. First line antifungal therapy was voriconazole only (8/18) or amphotericin B alone or in association (6/18). Five patients required surgery (4 CPA, 1 aspergilloma). One patient died from respiratory failure at 11 years old. Conclusion Mold infections occurred in 13.5% of STAT3-deficient patients from the French cohort, mostly on anatomical modification of the lung. Notably, patients developed aspergilloma, ABPA or CPA, but no invasive aspergillosis. Despite prolonged antifungal treatment and/or surgery half of the patients (5/10) relapsed.

Evaluation of the Chagas disease control program in Açucena Municipality, Rio Doce Valley, State of Minas Gerais, Brazil.

Açucena Municipality, Rio Doce Valley, State of Minas Gerais, Brazil temporarily (2001-2005) interrupted epidemiological surveillance for Chagas disease. The objective of this work was to evaluate the Chagas Disease Control Program (CDCP) in Açucena and to offer suggestions for improving local epidemiological surveillance. This study was conducted in three phases: I) a serological investigation of schoolchildren aged 5 to 15 years using an enzyme-linked immunosorbent assay (ELISA) test performed on blood collected on filter paper followed by ELISA, indirect immunofluorescence (IIF) and indirect hemaglutination (IHA) on venous blood for borderline cases and those in the gray zone of reactivity; II) vector evaluation using the data obtained by local health agents during 2006-2010; and III) examination by ELISA, IIF and IHA of serum samples from the inhabitants of houses where infected Triatoma vitticeps was found and evaluation of their knowledge about Chagas disease. Five individuals had inconclusive results in the ELISA screening but were seronegative for Chagas disease. The triatomine evaluation revealed the presence of three species: Triatoma vitticeps, Panstrongylus megistus and Panstrongylus diasi. Triatoma vitticeps was the most prevalent and widespread, with a higher (67%) index of Trypanosoma cruzi flagellates and evidence of colonization. Most of the inhabitants of the infested houses recognized triatomines and had basic knowledge about Chagas disease. Although T. vitticeps is not clearly associated with Chagas disease transmission, these results highlight the importance of maintaining CDCP in endemic areas and the need for greater emphasis on epidemiological surveillance, especially in areas with important vectorial changes or that have been modified by human intervention.

The emerging relationship between the airway microbiota and chronic respiratory disease: clinical implications

Until recently, relationships between evidence of colonization or infection by specific microbial species and the development, persistence or exacerbation of pulmonary disease have informed our opinions of airway microbiology. However, recent applications of culture-independent tools for microbiome profiling have revealed a more diverse microbiota than previously recognized in the airways of patients with chronic pulmonary disease. New evidence indicates that the composition of airway microbiota differs in states of health and disease and with severity of symptoms and that the microbiota, as a collective entity, may contribute to pathophysiologic processes associated with chronic airway disease. Here, we review the evolution of airway microbiology studies of chronic pulmonary disease, focusing on asthma, chronic obstructive pulmonary disease and cystic fibrosis. Building on evidence derived from traditional microbiological approaches and more recent culture-independent microbiome studies, we discuss the implications of recent findings on potential microbial determinants of respiratory health or disease.

Holocene emergence in Euboea island (Greece)

Detailed mapping along the northwestern coastline of Euboea has provided new evidence of colonization by Lithophaga lithophaga (L.) reaching about 3.8m above the present biological MSL. Such marine biological marks, together with morphological notches, correspond to the occurrence of two sequences of Holocene vertical displacements higher than those reported by previous studies, on the central part of the southern coast and along the northern coast of the island. A well developed emerged notch is found at +1.7±0.1m above present mean sea level, whereas the uppermost part of the lithophagid holes suggest a former emerged shoreline at least at +3.8±0.1m. Radiocarbon AMS dating of Lithophaga shells found in their burrows, showed that the lower uplifted shoreline corresponds to a tectonic event (probably coseismic) apparently dated at 2200 a BP, while the higher shoreline corresponds to an older relative sea-level transgression, possibly of tectonic origin, apparently dated about 5570 a BP. The apparent radiocarbon age of lithophagid shells can be about 350 to 400years older than the uplift event that exposed them, due to incorporation of host-rock carbon. Nevertheless, the two new paleoshorelines provide evidence that repeated uplift movements, greater than those reported by previous authors, occurred during the late Holocene, uplifting the western part of the island.

Phylogenetic relationships of species within the tribe Labiostrongylinea (Nematoda: Cloacinidae) from Australian marsupials based on ribosomal DNA spacer sequence data

Parasitic nematodes of the tribe Labiostrongylinea (Family Cloacinidae) occur in the stomachs of a wide variety of potoroid and macropodid marsupials in Australia, Papua Indonesia and Papua New Guinea. The aim of the present study was to infer the evolutionary relationships of the five genera of labiostrongyline nematodes that occur in Australian potoroids and macropodids using sequence data of the nuclear first and second internal transcribed spacers of ribosomal DNA. The phylogenetic analyses resulted in the separation of the Labiostrongylinea into two major groups reflecting coevolution between hosts and parasites. Two nematode species belonging to the genus Potorostrongylus formed a sister group to the remaining species of the Labiostrongylinea. This genus occurs exclusively in potoroid marsupials, which are considered to be basal to the macropodid marsupials. The second major group included species of Labiostrongylus, Labiosimplex, Labiomultiplex and Parazoniolaimus, all of which occur in macropodids. These species formed two distinct clades, one predominating in the host genera Thylogale and Onychogalea, and the second in the genus Macropus, which includes the more recent macropodids. However, there is also evidence of colonisation by both nematode clades of relatively unrelated hosts. In addition, genetic differences among individuals of Lm. eugenii from geographically isolated populations of M. eugenii, and among Ls. longispicularis from different subspecies of M. robustus suggest the existence of sibling species that may have arisen by allopatric speciation. The broad coevolutionary relationship between the labiostrongyline nematodes and their marsupial hosts therefore represents a mixture of potential cospeciation and colonisation events.

PRESERVATION OF PROTISTS WITHIN DECAYING PLANTS FROM GEOTHERMALLY INFLUENCED WETLANDS OF YELLOWSTONE NATIONAL PARK, WYOMING, UNITED STATES

Decaying and partially silica-permineralized subfossil plant stems collected from geothermally influenced wetlands of Yellowstone National Park contain evidence of colonization by protists, including heliozoa and chrysophytes. Wetland pools in which the plants and heliozoans occur represent an extreme environment characterized by steady influxes of hot-spring water. Recorded physicochemical conditions in wetland pools reveal relatively high temperatures (often >35 °C), high pH (≤9.1), high conductivity (>3000 µS/cm−1), brackish salinity and elevated concentrations of toxic elements including antimony (Sb), thallium (Tl), mercury (Hg), and arsenic (As). This report contains the first observations of heliozoans and chrysophytes from intercellular sites within decaying plants and adds a previously unreported and extreme environment to their known habitats. Such settings are potential taphonomic windows for preservation of fossil protists.

No evidence of colonization with community-acquired methicillin-resistant Staphylococcus aureus in HIV-1-infected men who have sex with men

To assess the prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) colonization in HIV-1-infected men who have sex with men (MSM), a cross-sectional study was conducted on 104 persons attending a large STI/HIV unit in Rome, Italy in the period June 2007-June 2008. Swabs obtained from both anterior nares and S. aureus isolates were characterized by phenotypic and genotypic methods. A total of 24 individuals (23.1%) were colonized with S. aureus but none carried MRSA. No statistically significant association between colonization with S. aureus and behavioural, clinical, virological or immunological characteristics was identified. This study indicates a lack of circulation of CA-MRSA in HIV-1-infected MSM in Italy and underscores large epidemiological differences between the USA and a European country, so that only locally conducted epidemiological studies can provide insight into the local circulation of CA-MRSA in general and selected populations.

Bottom-up and top-down effects on algal community dynamics in an aridland river: the Middle Rio Grande, New Mexico*

Abstract Background/Question/Methods In this study, we examined interactive effects of nutrient availability, river flow and food web structure on algal growth and species composition in the Middle Rio Grande, New Mexico. Algal community dynamics can be affected by both bottom-up and top-down factors. Algal production may be limited by low levels of nutrients or low light availability. Conversely, production is expected to increase when nutrient levels are high and light availability is not limited. Top-down factors such as grazing by invertebrates can also alter periphyton growth and community composition. Generally, a reduction in grazers results in periphyton biomass increases and shifts in growth forms (to more upright taxa).Nutrient diffusing substrates (NDS) were used in combination with grazer exclusion to investigate bottom-up and top-down effects on periphyton growth and species composition. Previously, NDS has been used in small, headwater streams and not in large sandy rivers like the Middle Rio Grande. NDS were made from inverted terracotta saucers, with four nutrient treatments – control, N, P and N+P. Large invertebrates were excluded from a subset of the saucers using an electrical field. The saucers were placed in a slow-flowing area of the Middle Rio Grande, and samples were collected weekly for a month. Results/Conclusions River conditions made it challenging to conduct the NDS experiment. Water levels were variable and turbidity levels were extremely high (&gt;4000NTU). Algal growth was extremely low on all treatments, largely due to light limitation caused by consistently high turbidity levels and a series of flooding and drying events which also decimated organismal growth on the substrates. Initial surveys of the diatom communities indicate extremely low densities and chlorophyll biomass was very low (mean ± se = 0.31 ± 0.09mg/m2). While dense periphyton communities did not develop on the NDS saucers, there was evidence of colonization by invertebrate populations. Blackfly larvae (Simuliidae) were most abundant in earlier samples whereas chironomid larvae (Chironomidae) were more abundant later in the experiment. Also, blackfly larvae were significantly more abundant on control saucers than on N+P saucers in the grazer/non-grazer experiment (P = 0.044). However, it was difficult to detect differences in the abundance of invertebrate grazers among nutrient treatments. Relationships among invertebrate population densities and the availability and diversity of periphyton for grazing will be described. These results are not definitive, but there are indications that nutrients, flow and grazers do influence algal community dynamics.