Analysis of the Pan Genome of <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> Isolates Recovered from Poultry by Pulsed-Field Gel Electrophoresis,Multilocus Sequence Typing (MLST), and Repetitive Sequence Polymerase Chain Reaction (rep-PCR) Reveals Different Discriminatory Capabilities

Campylobacter jejuni is one of the leading bacterial causes of food-borne illness in the USA. Molecular typing methods are often used in food safety for identifying sources of infection and pathways of transmission. Moreover, the identification of genetically related isolates (i.e., clades) may facilitate the development of intervention strategies for control and prevention of food-borne diseases. We analyzed the pan genome (i.e., core and variable genes) of 63 C. jejuni isolates recovered from chickens raised in conventional, organic, and free-range poultry flocks to gain insight into the genetic diversity of C. jejuni isolates recovered from different environments. We assessed the discriminatory power of three genotyping methods [i.e., pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and repetitive extragenic palindromic polymerase chain reaction (rep-PCR)]. The rep-PCR fingerprint was generated by determining the presence of repetitive sequences that are interspersed throughout the genome via repetitive extragenic palindromic PCR, enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), and BOX element PCR (BOX-PCR) and combining the data to form a composite fingerprint. The genetic fingerprints were subjected to computer-assisted pattern analysis. Comparison of the three genotypic methods revealed that repREB-PCR showed greater discriminatory power than PFGE and MLST. ERIC-PCR and BOX-PCR yielded the highest number of PCR products and greatest reproducibility. Regardless of the genotyping method, C. jejuni isolates recovered from chickens reared in conventional, organic, and free-range environments all exhibit a high level of genotypic diversity.     

The impact of a fox‐ and cat‐free safe haven on the bird fauna of remnant vegetation in southwestern Australia

Introduced predators are a serious threat to Australian vertebrates. However, the consequences of predation for an area's avifauna have rarely been quantified. We took advantage of the establishment of a 7,832 ha fox‐ and cat‐free safe haven at Mt Gibson, in Western Australia, to assess the consequences of excluding introduced mammal predators on the bird fauna. Bird surveys were conducted over 6 years, before and after the establishment of the introduced predator‐free safe haven. After 3 years, half the sites were enclosed by the fence that excluded introduced predators, while the remainder of sites remained outside the fence and were exposed to fox and cat activity. The sites were stratified by four major vegetation types. A total of 91 bird species were variously detectable with the survey approach, but were typically more detectable during morning surveys. Site occupancy varied considerably among species, but overall, occupancy by all species was most likely to be either not impacted or positively impacted by the safe haven. The most notable change was that avifaunal richness appeared to increase in woodland and shrubland habitats within, as compared to outside, the safe haven. We conclude that: (1) the safe haven had an overall positive impact on bird occupancy; and (2) there were no consistent trends with respect to the kinds of species whose occupancy was positively impacted, beyond them all being small‐ to medium‐sized birds and mostly insectivorous. However, these conclusions must be tempered by the poor detection probability of many species.     

Ecology of Australia: the effects of nutrient-poor soils and intense fires

Australia, the flattest, driest, and geologically oldest vegetated continent, has a uniquely high proportion of nutrient-poor soils. We develop a "Nutrient-Poverty/Intense-Fire Theory," which postulates that most anomalous features of organisms and ecosystems of Australia are the evolutionary consequences of adaptations to nutrient poverty, compounded by intense fire that tends to occur as a result of nutrient poverty. The fundamental tenet of the theory is that plants growing in environments with plentiful light and periodic adequate moisture, but on soils poor in phosphorus, zinc, and other indispensible nutrients, can synthesize carbohydrates in excess of the amount that can be combined with, or catalyzed by, these nutrients for metabolism and production of nutrient-rich foliage and reproductive tissues. They use this "expendable energy" to produce well-defended foliage, large quantities of lignified tissues, and readily digestible exudates. Rapid accumulation of nutrient-poor biomass, a result of low rates of herbivory, provides fuel for intense fire. Intense fire exacerbates nutrient poverty by volatilizing certain micronutrients critical for animals. Anomalous features of organisms of Australia that can be explained by this theory, rather than by climate or phylogenetic history alone, include the following: most woody plants have long-lived, durable foliage; plants defend their tissues primarily with carbon-rich but nutrient-poor compounds; an unusually high proportion of plants protects seeds from fire and granivores in sturdy, woody capsules or follicles; plants allocate unusually large amounts of expendable energy to production of carbon-based exudates, such as nectar and gums; an unusually high proportion of plant species is pollinated by vertebrates that average larger size than pollinators on other continents; herbivores are small and have slow metabolism; there are no ruminants, mammals that eat mainly subterranean plant matter, or fungus-culturing termites and ants; vegetation dominated by leaf-spinescent plants is more extensive than vegetation dominated by stem-spinescent plants; nitrogen-fixing plants are major components of most vegetation types; there is a higher proportion of myrmecochorous plant species than on any other continent; there are hardly any stem-succulent and few leaf-succulent, perennial, non-halophytic plant species; and an unusually high proportion of bird species breeds cooperatively. Although the Nutrient-Poverty/Intense-Fire Theory can provide plausible explanations for these anomalous features, some puzzles remain, among them the great success of introduced herbivores, the lack of grazers on extensive grasslands on cracking clays, the apparently low productivity of ants, and the prominence of the parasitic plants of Australia. By examining the ratios of available energy to nutrients, particularly scarce nutrients, ecologists may identify processes not previously recognized as important for life forms or biotic adaptation on other continents.     

AQP1 gene expression is upregulated by arginine vasopressin and cyclic AMP agonists in trophoblast cells

Aquaporins (AQPs) are water channels that regulate water flow in many tissues. As AQP1 is a candidate to regulate placental fluid exchange, we sought to investigate the effect of arginine vasopressin (AVP) and cAMP agonists on AQP1 gene expression in first trimester-derived extravillous cytotrophoblasts (HTR-8/Svneo) and two highly proliferative carcinoma trophoblast-like cell lines but with a number of functional features of the syncytiotrophoblast namely; JAR and JEG-3 cells. Our data demonstrated that AVP (0.1 nM) significantly increased the expression of AQP1 mRNA at 10 h in HTR-8/SVneo and JEG-3 cells (P<0.05). Both SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP, and forskolin, an adenylate cyclase stimulator significantly increased AQP1 mRNA expression in all cell lines after 2 h in a dose-dependent manner (P<0.05) with a parallel increase in protein expression. In the time course study, 5 microM of either SP-cAMP or forskolin significantly stimulated AQP1 mRNA expression after 2 h in HTR-8/SVneo cells and after 10 h in JAR and JEG-3 cells. AQP1 protein expression was highest after 20 h in both HTR-8/SVneo and JEG-3 cells (P<0.05). AVP-stimulated cAMP elevation was blocked in the presence of 9-(tetrahydro-2'-furyl) adenine (SQ22536) (100 microM), a cell-permeable adenylate cyclase inhibitor (P<0.05). These results indicate that in trophoblasts-like cells AQP1 gene expression is upregulated by both AVP and cAMP agonists. Furthermore, our data demonstrate that a cAMP-dependent pathway is responsible for the AVP effect on AQP1. Thus, modulation of AQP1 expression by maternal hormones may regulate invasion and fetal-placental-amnion water homeostasis during gestation.     

Activation of big MAP kinase 1 (BMK1/ERK5) inhibits cardiac injury after myocardial ischemia and reperfusion

Big MAP kinase 1 (BMK1/ERK5) plays a critical role in pre-natal development of the cardiovascular system and post-natal eccentric hypertrophy of the heart. Of the two isoforms upstream of MAPK-kinase 5 (MEK5) known to exist, only the longer MEK5alpha isoform potently activates BMK1. We generated cardiac-specific constitutively active form of the MEK5alpha (CA-MEK5alpha transgenic (Tg) mice), and observed a 3 to 4-fold increase in endogenous BMK1 activation and hyperphosphorylation of connexin 43 in the ventricles of the Tg compared to wild-type mice. The CA-MEK5alpha-Tg-mice demonstrated a profoundly accelerated recovery of left ventricular developed pressure after ischemia/reperfusion. We propose a novel role for BMK1 in protecting the heart from ischemia/reperfusion-induced cardiac injury.