∼14 000 years of geochemical and isotopic data from Lake Simcoe, Canada.

This dataset contains measurements of modern water and ancient core materials from Lake Simcoe, the fourth largest lake wholly in Ontario, Canada. These data consist of: (i) oxygen, hydrogen and carbon isotope (δ 18O, δ 2H and δ 13C) compositions for modern water samples; (ii) physical measurements of one piston core, PC-5; (iii) δ 13C and δ 18O values of ostracods collected from PC-5, and (iv) δ 13C and δ 18O values of ancient DIC and water, respectively, inferred from item (iii). Physical measurements performed on core PC-5 include magnetic susceptibility, mineralogy and grain size. Mass accumulation rates are also reported. These data will be of interest to those aiming to better characterize the timing and pathway of meltwater flow during and following deglaciation of the Laurentide Ice Sheet in the Laurentian Great Lakes region. These data will also be useful to researchers investigating the influence of deglaciation on the oxygen and carbon isotope systematics of ancient lake environments. A discussion of these data is available in "A ∼14 000-year record of environmental change from Lake Simcoe, Canada" [1].

Isotopic and geochemical data from Barry Lake, Canada: A 900-year record of environmental change.

The data reported here consist of oxygen and hydrogen isotope compositions for 145 modern water samples, and geochemical measurements for gravity cores of sediment, all collected from Barry Lake, a small kettle lake located in Ontario, Canada. The geochemical measurements for the sediment organic matter include organic carbon and total nitrogen isotope compositions, organic carbon and total nitrogen contents and chlorophyll a content. The carbon and oxygen isotope compositions of marl contained in these sediments are also reported, along with the calcite and quartz contents of the sediment sample. Mass accumulation rates of total organic carbon, total nitrogen, chlorophyll a and calcite are reported. Dating of these sediments shows that they span ∼900 years. The stable isotope compositions of the modern waters and marl are useful to researchers studying how effective moisture (the net of water inputs vs outputs) changed in southern Ontario across the last ∼900 years. Proxies derived from the organic fraction of the lake sediments will be of interest to researchers of small Ontario lakes seeking to contextualize recent increases in primary production related to eutrophication. A discussion of these data, and a comparison of these data to other cores in the Great Lakes Region, is available in "A 900-year record of effective moisture in the Great Lakes Region" (Doyle et al., 2021).

Term and preterm labour are associated with distinct microbial community structures in placental membranes which are independent of mode of delivery.

Infection is considered a possible trigger for preterm labour, supported by evidence showing the presence of bacteria in the placenta and placental membranes from preterm births. In this study, 16S rDNA pyrosequencing was used to identify bacteria in placental membranes. Caesarean sections and vaginal deliveries at term were found to harbour common genera. Mycoplasma hominis, Aerococcus christensenii, Gardnerella vaginalis and Fusobacterium nucleatum were either only present in preterm membranes or in greater abundance than at term. These data support previous studies that used either targeted qPCR or broad-range 16S rDNA PCR and cloning but not a recent microbiome analysis of placental tissue using high-throughput sequencing.

Comparison of virulence of Legionella longbeachae strains in guinea pigs and U937 macrophage-like cells.

A guinea pig model of experimental legionellosis was established for assessment of virulence of isolates of Legionella longbeachae. The results showed that there were distinct virulence groupings of L. longbeachae serogroup 1 strains based on the severity of disease produced in this model. Statistical analysis of the animal model data suggests that Australian isolates of L. longbeachae may be inherently more virulent than non-Australian strains. Infection studies performed with U937 cells were consistent with the animal model studies and showed that isolates of this species were capable of multiplying within these phagocytic cells. Electron microscopy studies of infected lung tissue were also undertaken to determine the intracellular nature of L. longbeachae serogroup 1 infection. The data showed that phagosomes containing virulent L. longbeachae serogroup 1 appeared bloated, contained cellular debris and had an apparent rim of ribosomes while those containing avirulent L. longbeachae serogroup 1 were compact, clear and smooth.

Molecular characterization of a Shiga toxigenic Escherichia coli O113:H21 strain lacking eae responsible for a cluster of cases of hemolytic-uremic syndrome.

Shiga toxigenic Escherichia coli (STEC) strains are a diverse group of organisms capable of causing severe gastrointestinal disease in humans. Within the STEC family, certain strains appear to have greater virulence for humans. STEC strains carrying eae and belonging to serogroup O157 or O111 have been responsible for the vast majority of outbreaks of STEC disease reported to date. Here we describe a STEC O113:H21 strain lacking eae that was responsible for a cluster of three cases of hemolytic-uremic syndrome. This strain produces a single Stx2-related toxin and adheres efficiently to Henle 407 cells.

Genetic analysis of the thermolabile variant of 5, 10-methylenetetrahydrofolate reductase as a risk factor for ischemic stroke.

Mild hyperhomocysteinemia is a risk factor for atherosclerotic vascular disease. Homozygosity for the C677T mutation in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR) is frequently associated with hyperhomocysteinemia, particularly in individuals with low levels of serum folate, and has been directly associated with cardiovascular disease in certain populations. The purpose of this study was to establish whether the C677T mutation, which causes thermolabile MTHFR, is a risk factor for ischemic stroke in the Irish population. The homozygous C677T genotype has previously been associated with coronary heart disease in Ireland. We collected blood from 174 individuals (minimum age 60 years) who had suffered an ischemic stroke that was confirmed by computed tomography brain scan. Control subjects (n=183) aged >/=60 years, who had never suffered a stroke or transient ischemic attack, were recruited from hospitals and active retirement groups in the same geographical area. MTHFR genotypes were determined and other known risk factors for stroke were documented. In the control group, the frequency of subjects with the homozygous C677T genotype was 10.4%. In patients who had suffered ischemic stroke, the frequency was 15.5%. This difference was not statistically significant. The odds ratio of stroke for C677T homozygotes, with other genotypes as a reference group, was 1.59, 95% CI=0.85, 2.97. The data indicate that the homozygous C677T MTHFR genotype is at most a moderate risk factor for ischemic stroke.

Sequence analysis of the mip gene of the soilborne pathogen Legionella longbeachae.

To understand the basis of pathogenesis by Legionella longbeachae serogroup 1, the importance of the Mip protein in this species was examined. Amino-terminal analysis of the purified, cloned L. longbeachae serogroup 1 ATCC 33462 Mip protein confirmed that the cloned gene protein was expressed and processed in an Escherichia coli background. DNA sequence analysis of plasmid pIMVS27, containing the entire L. longbeachae serogroup 1 mip gene, revealed a high degree of homology to the mip gene of Legionella pneumophila serogroup 1, 76% homology at the DNA level and 87% identity at the amino acid level. Primer extension analysis determined that the start site of transcription was the same for both species, with some differences observed for the -10 and -35 promoter regions. Primers designed from the mip gene sequence obtained for L. longbeachae serogroup 1 ATCC 33462 were used to amplify the mip genes from L. longbeachae serogroup 2 ATCC 33484 and an Australian clinical isolate of L. longbeachae serogroup 1 A5H5. The mip gene from A5H5 was 100% identical to the type strain sequence. The serogroup 2 strain of L. longbeachae differed by 2 base pairs in third-codon positions. Allelic exchange mutagenesis was used to generate an isogenic mip mutant in ATCC 33462 and strain A5H5. The ATCC mip mutant was unable to infect a strain of Acanthamoebae sp. both in liquid and in a potting mix coculture system, while the A5H5 mip mutant behaved in a manner siilar to that of L. pneumophila serogroup 1, i.e., it displayed a reduced capacity to infect and multiply within Acanthamoebae. To determine if this mutation resulted in reduced virulence in the guinea pig animal model, the A5H5 mip mutant and its parent strain were assessed for their abilities to establish an infection after aerosol exposure. Unlike the virulent parent strain, the mutant strain did not kill any animals under two different dose regimes. The data indicate that the Mip protein plays an important role in the intracellular life cycle of L. longbeachae serogroup 1 species and is required for full virulence.

Molecular microbiological investigation of an outbreak of hemolytic-uremic syndrome caused by dry fermented sausage contaminated with Shiga-like toxin-producing Escherichia coli.

Shiga-like toxin-producing Escherichia coli (SLTEC) strains are a diverse group of organisms which are known to cause diarrhea and hemorrhagic colitis in humans. This can lead to potentially fatal systemic sequelae, such as hemolytic-uremic syndrome (HUS). Strains belonging to more than 100 different O:H serotypes have been associated with severe SLTEC disease in humans, of which only O157 strains (which are uncommon in Australia) have a distinguishable cultural characteristic (sorbitol negative). During an outbreak of HUS in Adelaide, South Australia, a sensitive PCR assay specific for Shiga-like toxin genes (slt) was used to test cultures of feces and suspected foods. This enabled rapid confirmation of infection and identified a locally produced dry fermented sausage (mettwurst) as the source of infection. Cultures of feces from 19 of 21 HUS patients and 7 of 8 mettwurst samples collected from their homes were PCR positive for slt-I and slt-II genes. SLTEC isolates belonging to serotype O111:H- was subsequently isolated from 16 patients and 4 mettwurst samples. Subsequent restriction fragment length polymorphism analysis of chromosomal DNA from these isolates with slt-specific probes indicated that at least three different O111:H- genotypes were associated with the outbreak. Pulsed-field gel electrophoresis of genomic DNA restricted with XbaI showed that two of these restriction fragment length polymorphism types were closely related, but the third was quite distinct. However, SLTEC strains of other serotypes, including O157:H-, were also isolated from some of the HUS patients.