Effect of the thyroid on faecal shedding of E. coli O157:H7 and Escherichia coli in naturally infected yearling beef cattle

AIMS: To determine if thyroid function affects faecal shedding of Escherichia coli O157:H7. METHODS AND RESULTS: Eight yearling cattle (n = 4 per treatment group), previously identified as shedding E. coli O157:H7, received either 0 or 10 mg 6-N-propyl-2-thiouracil (PTU) kg(-1) BW day(-1) for 14 days to reduce serum concentrations of the thyroid hormones, T(3) and T(4). Animals were monitored daily for changes in faecal shedding of E. coli O157:H7 and E. coli (EC) for the 14-day treatment period and an additional 7 days post-treatment. Body weight was measured weekly and serum concentrations of T(3) and T(4) were determined every 3 days. No differences in faecal shedding of E. coli O157:H7 were observed during the 14-day treatment period. However, compared with control animals, a greater percentage of PTU-treated cattle ejected E. coli O157:H7 on day 16 (100 vs 25%) and 18 (75 vs 0%) of the post-treatment period. Serum T(3) was lower in PTU-treated cattle during the 14-day treatment period and greater on day 18 of the post-treatment period. CONCLUSION: Cattle with chemically altered thyroid hormones had similar shedding patterns of faecal E. coli O157:H7 and EC during the 14-day treatment period. However, faecal shedding of E. coli O157:H7 tended to be greater, and serum concentrations of T(3), were greater for PTU-treated cattle immediately following the termination of PTU treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Short-term chemical inhibition of thyroid hormones had minimal effects on faecal shedding of E. coli O157:H7 in naturally infected cattle. However, a hyperthyroid state as observed postdosing might play a role in the seasonal shedding of E. coli O157:H7 in cattle.     

Effects of sodium chlorate on toxin production by Escherichia coli O157:H7

Chlorate kills E. coli O157:H7 and has been proposed as a feed additive to be included in cattle rations immediately prior to slaughter to reduce E. coli O157: H7 populations in the gut. Antibiotic usage is not recommended in cases of E. coil O157:H7-induced hemorrhagic colitis because some antibiotics stimulate increased toxin production. This study was undertaken to determine if chlorate treatment affected toxin production. Pure cultures of E. coil O157:H7 were treated with 1/4 MIC of antibiotics (ampicillin, tetracycline, ceftiofur, gentamicin, monensin, tylosin, penicillin, ciprofloxacin, and novobiocin); toxin production was significantly increased by some antibiotics, but not by chlorate. Studies with mixed fecal bacteria demonstrated that chlorate killed E. coli O157:H7, but again did not stimulate toxin production. Chlorate appears to be an effective method to reduce shiga toxin-producing E. coil (STEC) populations in food animals, but additional studies are warranted before it is used to control infections.     

Maternal steroids and contaminants in common tern eggs: a mechanism of endocrine disruption?

We looked for evidence for the hypothesis that exposure of female birds to polychlorinated biphenyls (PCBs) results in alteration of blood steroid hormone concentrations and alters subsequent hormone transfer of steroids to eggs. Eggs of three-egg clutches were collected from a PCB-exposed common tern (Sterna hirundo) colony (Ram Island, Buzzards Bay, MA, USA) and from a relatively clean colony (Bodkin Island, Chesapeake Bay, MD, USA), and were analyzed for concentrations of organochlorine contaminants and steroid hormones (17beta-estradiol, 5alpha-dihydrotestosterone, testosterone and androstenedione). There was no relationship between total PCBs and steroid concentrations considering all eggs together, considering eggs of different laying order or considering differences between sequentially laid eggs in a clutch. Similarly, concentrations of di- and tri-chlorinated biphenyls and steroids in eggs were not related. The concentrations of PCBs, mercury and selenium were below estimated thresholds for toxicity to embryos. Maternal steroids, except estradiol, were present in yolk of all eggs, with increasing concentrations in the second and third eggs laid. Our data provided no evidence for a maternal toxicological event that might alter the amount of maternal steroid hormone transferred to eggs.     

Long-Term Cognitive and Behavioral Outcomes following Resolution of Sleep Disordered Breathing in Preschool Children

This study aimed to determine the long term effects of resolution of SDB in preschool children, either following treatment or spontaneous recovery, on cognition and behavior. Children diagnosed with SDB at 3-5y (N = 35) and non-snoring controls (N = 25), underwent repeat polysomnography (PSG) and cognitive and behavioral assessment 3 years following a baseline study. At follow-up, children with SDB were grouped into Resolved and Unresolved. Resolution was defined as: obstructive apnea hypopnea index (OAHI) ≤1 event/h; no snoring detected on PSG; and no parental report of habitual snoring. 57% (20/35) of children with SDB received treatment, with SDB resolving in 60% (12/20). 43% (15/35) were untreated, of whom 40% (6/15) had spontaneous resolution of SDB. Cognitive reduced between baseline and follow-up, however this was not related to persistent disease, with no difference in cognitive outcomes between Resolved, Unresolved or Control groups. Behavioral functioning remained significantly worse in children originally diagnosed with SDB compared to control children, regardless of resolution. Change in OAHI did not predict cognitive or behavioral outcomes, however a reduction in nocturnal arousals, irrespective of full resolution, was associated with improvement in attention and aggressive behavior. These results suggest that resolution of SDB in preschool children has little effect on cognitive or behavioral outcomes over the long term. The association between sleep fragmentation and behavior appears independent of SDB, however may be moderated by concomitant SDB. This challenges the assumption that treatment of SDB will ameliorate associated cognitive and behavioural deficits and supports the possibility of a SDB phenotype.     

Cigarette smoking reduces DNA methylation levels at multiple genomic loci but the effect is partially reversible upon cessation

Smoking is a major risk factor in many diseases. Genome wide association studies have linked genes for nicotine dependence and smoking behavior to increased risk of cardiovascular, pulmonary, and malignant diseases. We conducted an epigenome wide association study in peripheral-blood DNA in 464 individuals (22 current smokers and 263 ex-smokers), using the Human Methylation 450 K array. Upon replication in an independent sample of 356 twins (41 current and 104 ex-smokers), we identified 30 probes in 15 distinct loci, all of which reached genome-wide significance in the combined analysis P < 5 × 10⁻⁸. All but one probe (cg17024919) remained significant after adjusting for blood cell counts. We replicated all 9 known loci and found an independent signal at CPOX near GPR15. In addition, we found 6 new loci at PRSS23, AVPR1B, PSEN2, LINC00299, RPS6KA2, and KIAA0087. Most of the lead probes (13 out of 15) associated with cigarette smoking, overlapped regions of open chromatin (FAIRE and DNaseI hypersensitive sites) or / and H3K27Ac peaks (ENCODE data set), which mark regulatory elements. The effect of smoking on DNA methylation was partially reversible upon smoking cessation for longer than 3 months. We report the first statistically significant interaction between a SNP (rs2697768) and cigarette smoking on DNA methylation (cg03329539). We provide evidence that the metSNP for cg03329539 regulates expression of the CHRND gene located circa 95 Kb downstream of the methylation site. Our findings suggest the existence of dynamic, reversible site-specific methylation changes in response to cigarette smoking , which may contribute to the extended health risks associated with cigarette smoking.     

The cosmopolitan maternal heritage of the Thoroughbred racehorse breed shows a significant contribution from British and Irish native mares

The paternal origins of Thoroughbred racehorses trace back to a handful of Middle Eastern stallions, imported to the British Isles during the seventeenth century. Yet, few details of the foundation mares were recorded, in many cases not even their names (several different maternal lineages trace back to 'A Royal Mare'). This has fuelled intense speculation over their origins. We examined mitochondrial DNA from 1929 horses to determine the origin of Thoroughbred foundation mares. There is no evidence to support exclusive Arab maternal origins as some historical records have suggested, or a significant importation of Oriental mares (the term used in historic records to refer to Middle East and western Asian breeds including Arab, Akhal-Teke, Barb and Caspian). Instead, we show that Thoroughbred foundation mares had a cosmopolitan European heritage with a far greater contribution from British and Irish Native mares than previously recognized.     

Local interactions drive size dependent space competition between coral and crustose coralline algae

For many species, the outcome of competition for space in homogeneous habitats depends upon relative rates of growth and overgrowth. Size dependence in competition occurs when this balance shifts due to the growth of one or both species. For example, the ability of coral to compete with certain species of crustose coralline algae (CCA) may depend on whether coral colonies are large enough to avoid being overgrown. Spatially implicit models suggest size refuges from competition can improve the persistence of species with a vulnerable life stage. We use spatially explicit simulation models to explore size dependence in competition between coral and competitively dominant CCA in well lit habitat. We determine what conditions allow coral to use size refuges and whether refuges improve the recovery of coral after disturbance. Local interactions in explicit space prevent the maturation of coral into size refuges unless coral grows more rapidly than CCA or coral colonies are allowed to fuse, and mortality mechanisms can limit long‐term persistence even if the refuge is achieved. We contrast results with analogous differential equation models, with and without an explicit maturation delay, to demonstrate how the predicted outcome of competition is frequently reversed when local interactions and individual‐based dynamics are included in models of size‐dependent competition.     

Identification and quantification of methanogenic Archaea in adult chicken ceca

By using molecular methods for the identification and quantification of methanogenic archaea in adult chicken ceca, 16S rRNA genes of 11 different phylotypes, 10 of which were 99% similar to Methanobrevibacter woesei, were found. Methanogen populations, as assessed by cultivation, and the 16S rRNA copy number were between 6.38 and 8.23 cells/g (wet weight) and 5.50 and 7.19 log(10)/g (wet weight), respectively.     

Detection of methane and quantification of methanogenic archaea in faeces from young broiler chickens using real-time PCR

AIMS: To detect the presence of methanogens in the faeces of broiler chicks during the first 2 weeks of age. METHODS AND RESULTS: Chicken faecal samples from 120 broiler chicks were incubated for methane gas formation and methanogenic archaea were analysed using real-time PCR. The copy number of the order Methanobacteriales 16S rDNA gene in chicken faeces when the broilers were 3-12 days of age, litter and house flies collected in the bird house ranged from 4.19 to 5.51 log(10) g(-1) wet weight. The number of positive methane culture tubes increased from 25% to 100% as the birds aged. CONCLUSIONS: Methanogens were successfully detected in faecal samples from 3- to 12-day-old broilers, as well as litter and house flies using real-time PCR. The copy number of methanogenic 16S rDNA gene in these samples was also similar to the number observed in litter and house flies. SIGNIFICANCE AND IMPACT OF THE STUDY: The same methanogens consistently appeared in chicken faeces a few days after birth. Detection of the methanogenic bacteria in litter and house flies implicated them as potential environmental sources for methanogen colonization in broiler chicks.