Dental Hygiene, Dental, and Medical Students’ OMFS/Hospital Dentistry‐Related Knowledge/Skills, Attitudes, and Behavior: An Exploration

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153557/1/jddj002203372017812tb06260x.pd

Land systems as surrogates for biodiversity in conservation planning

Environmental surrogates (land classes) for the distribution of biodiversity are increasingly being used for conservation planning. However; data that demonstrate coincident patterns in land classes and biodiversity are limited. We ask the overall question, "Are land systems effective surrogates for the spatial configuration of biodiversity for conservation planning?" and we address three specific questions: (1) Do different land systems represent different biological assemblages.? (2) Do biological assemblages on the same land system remain similar with increasing geographic separation? and (3) Do biological assemblages on the same land system remain similar with increasing land system isolation? Vascular plants, invertebrates, and microbiota were surveyed from 24 sites in four land systems in and northwest New South Wales, Australia. Within each land system, sites were located to give a hierarchy of inter-site distances, and land systems were classified as either "low isolation" (large and continuous) or "high isolation" (small patches interspersed among other land systems). Each type of land system supported components of biodiversity either not found, or found infrequently, on other land systems, suggesting that land systems function as surrogates for biodiversity, and that conservation-area networks representing land-system diversity will also represent biological diversity. However, the majority of taxa were found on more than one land-system type, suggesting that a large proportion of the plant, arthropod, and microbial biodiversity may be characterized by widespread species with low fidelity to particular land systems. Significant relationships between geographic distance among sites and differences among assemblages were revealed for all taxa except the microbiota. Therefore, as sites on the same land system were located farther apart, the assemblages at those sites became more different. This finding strongly suggests that conservation planning based on land-system diversity should also sample the geographic range occupied by each land system. Land-system isolation was not revealed to be a significant Source of variation in assemblage composition. Our research finds support for environmental surrogates for biodiversity in conservation planning, specifically the use of land systems and similarly derived land classifications. However, the need for explicit modeling of geographic distance in conservation planning is clearly indicated

Diverse, yet-to-be-cultured members of the Rubrobacter subdivision of the Actinobacteria are widespread in Australian arid soils

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Preclinical Class 1 Integron with a Complete Tn402-Like Transposition Module▿

The presence of integrons was assessed in gut bacteria isolated from wild-caught prawns. A pseudomonad was recovered that contained a Tn402-like class 1 integron with a complete transposition module and two gene cassettes. One cassette was identical to a previously described cassette from a chromosomal class 3 integron in Delftia tsuruhatensis

Identification and differentiation of Cryptosporidium species by capillary electrophoresis single-strand conformation polymorphism

Cryptosporidium species generally lack distinguishing morphological traits, and consequently, molecular methods are commonly used for parasite identification. Various methods for Cryptosporidium identification have been proposed, each with their advantages and disadvantages. In this study, we show that capillary electrophoresis coupled with single-strand conformation polymorphism (CE-SSCP) is a rapid, simple and cost-effective method for the identification of Cryptosporidium species and genotypes. Species could be readily differentiated based on the SSCP mobility of amplified 18S rRNA gene molecules. Clones that differed by single-nucleotide polymorphisms could be distinguished on CE-SSCP mobility. Profiles of species known to have heterogenic copies of 18S rRNA gene contained multiple peaks. Cloning and sequencing of Cryptosporidium parvum, Cryptosporidium hominis, Cryptosporidium fayeri and Cryptosporidium possum genotype 18S rRNA gene amplicons confirmed that these multiple peaks represented type A and type B 18S rRNA gene copies. CE-SSCP provides a reliable and sensitive analysis for epidemiological studies, environmental detection and diversity screening.8 page(s

Recombination Activity of a Distinctive Integron-Gene Cassette System Associated with Pseudomonas stutzeri Populations in Soil

Class 1 integrons have strongly influenced the evolution of multiple antibiotic resistance. Diverse integrons have recently been detected directly in a range of natural environments. In order to characterize the properties of these environmental integrons, we sought to isolate organisms containing integrons from soils, which resulted in the isolation of Pseudomonas stutzeri strain Q. Further isolation efforts targeted at this species resulted in recovery of two other strains (P and BAM). 16S rRNA sequences and chromosome mapping showed that these three strains are very closely related clonal variants in a single genomovar of P. stutzeri. Only strains Q and BAM were found to contain an integron and an associated gene cassette array. The intI and attI components of these strains showed 99 and 90% identity, respectively. The structure of these integrons and their associated gene cassettes was similar to that reported previously for other integron classes. The two integrons contained nonoverlapping sets of cassette-associated genes. In contrast, many of the cassette-associated recombination sites in the two integrons were similar and were considered to constitute a distinct subfamily consisting of 59-base element (59-be) recombination sites (the Pseudomonas subfamily). The recombination activity of P. stutzeri integron components was tested in cointegrate assays. IntIPstQ was shown to catalyze site-specific recombination between its cognate attI site and 59-be sites from antibiotic resistance gene cassettes. While IntIPstQ did not efficiently mediate recombination between members of the Pseudomonas 59-be subfamily and other 59-be types, the former sites were functional when they were tested with IntI1. We concluded that integrons present in P. stutzeri possess recombination activity and represent a hot spot for genomic diversity in this species

The Evolution of Class 1 Integrons and the Rise of Antibiotic Resistance▿ †

Class 1 integrons are central players in the worldwide problem of antibiotic resistance, because they can capture and express diverse resistance genes. In addition, they are often embedded in promiscuous plasmids and transposons, facilitating their lateral transfer into a wide range of pathogens. Understanding the origin of these elements is important for the practical control of antibiotic resistance and for exploring how lateral gene transfer can seriously impact on, and be impacted by, human activities. We now show that class 1 integrons can be found on the chromosomes of nonpathogenic soil and freshwater Betaproteobacteria. Here they exhibit structural and sequence diversity, an absence of antibiotic resistance genes, and a phylogenetic signature of lateral transfer. Some examples are almost identical to the core of the class 1 integrons now found in pathogens, leading us to conclude that environmental Betaproteobacteria were the original source of these genetic elements. Because these elements appear to be readily mobilized, their lateral transfer into human commensals and pathogens was inevitable, especially given that Betaproteobacteria carrying class 1 integrons are common in natural environments that intersect with the human food chain. The strong selection pressure imposed by the human use of antimicrobial compounds then ensured their fixation and global spread into new species

Mobilization of a Tn402-Like Class 1 Integron with a Novel Cassette Array via Flanking Miniature Inverted-Repeat Transposable Element-Like Structures ▿

A Tn402-like class 1 integron was recovered from a prawn-associated bacterium. One of its cassettes included methionine sulfoxide reductase genes, the first example of such genes being captured by an integron. The integron was flanked by direct repeats that resemble miniature inverted-repeat transposable element sequences. Excision of the integron by homologous recombination through these sequences was demonstrated

Class 1 Integrons Potentially Predating the Association with Tn402-Like Transposition Genes Are Present in a Sediment Microbial Community

Integrons are genetic elements that contribute to lateral gene transfer in bacteria as a consequence of possessing a site-specific recombination system. This system facilitates the spread of genes when they are part of mobile cassettes. Most integrons are contained within chromosomes and are confined to specific bacterial lineages. However, this is not the case for class 1 integrons, which were the first to be identified and are one of the single biggest contributors to multidrug-resistant nosocomial infections, carrying resistance to many antibiotics in diverse pathogens on a global scale. The rapid spread of class 1 integrons in the last 60 years is partly a result of their association with a specific suite of transposition functions, which has facilitated their recruitment by plasmids and other transposons. The widespread use of antibiotics has acted as a positive selection pressure for bacteria, especially pathogens, which harbor class 1 integrons and their associated antibiotic resistance genes. Here, we have isolated bacteria from soil and sediment in the absence of antibiotic selection. Class 1 integrons were recovered from four different bacterial species not known to be human pathogens or commensals. All four integrons lacked the transposition genes previously considered to be a characteristic of this class. At least two of these integrons were located on a chromosome, and none of them possessed antibiotic resistance genes. We conclude that novel class 1 integrons are present in a sediment environment in various bacteria of the β-proteobacterial class. These data suggest that the dispersal of this class may have begun before the “antibiotic era.