A major difference between the divergence patterns within the lines-1 families in mice and voles

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.      

Multifactorial diversity sustains microbial community stability

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty.     

Immunohistochemical localization of irisin in skin,eye, and thyroid and pineal glands of the crested porcupine (Hystrix cristata)

Irisin was first identified in muscle cells. We detected irisin immunoreactivity in various organs of the crested porcupine (Hystrix cristata). In the epidermis, irisin immunoreactivity was localized mainly in stratum basale, stratum spinosum and stratum granulosum layers; immunoreactivity was not observed in the stratum corneum. In the dermis, irisin was found in the external and internal root sheath, cortex and medulla of hair follicles, and in sebaceous glands. Irisin immunoreactivity was found in the neural retina and skeletal muscle fibers associated with the eye. The pineal and thyroid glands also exhibited irisin immunoreactivity.     

Genome-Wide Transposon Mutagenesis Identifies a Role for Host Neuroendocrine Stress Hormones in Regulating the Expression of Virulence Genes in Salmonella

Bacterial sensing of environmental signals plays a key role in regulating virulence and mediating bacterium-host interactions. The sensing of the neuroendocrine stress hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) plays an important role in modulating bacterial virulence. We used MudJ transposon mutagenesis to globally screen for genes regulated by neuroendocrine stress hormones in Salmonella enterica serovar Typhimurium. We identified eight hormone-regulated genes, including yhaK, iroC, nrdF, accC, yedP, STM3081, and the virulence-related genes virK and mig14. The mammalian α-adrenergic receptor antagonist phentolamine reversed the hormone-mediated effects on yhaK, virK, and mig14 but did not affect the other genes. The β-adrenergic receptor antagonist propranolol had no activity in these assays. The virK and mig14 genes are involved in antimicrobial peptide resistance, and phenotypic screens revealed that exposure to neuroendocrine hormones increased the sensitivity of S. Typhimurium to the antimicrobial peptide LL-37. A virK mutant and a virK mig14 double mutant also displayed increased sensitivity to LL-37. In contrast to enterohemorrhagic Escherichia coli (EHEC), we have found no role for the two-component systems QseBC and QseEF in the adrenergic regulation of any of the identified genes. Furthermore, hormone-regulated gene expression could not be blocked by the QseC inhibitor LED209, suggesting that sensing of hormones is mediated through alternative signaling pathways in S. Typhimurium. This study has identified a role for host-derived neuroendocrine stress hormones in downregulating S. Typhimurium virulence gene expression to the benefit of the host, thus providing further insights into the field of host-pathogen communication.Bacterial sensing of environmental signals plays a key role in regulating virulence gene expression and bacterium-host interactions. It is increasingly recognized that detection of host-derived molecules, such as the neuroendocrine stress hormones (catecholamines) epinephrine (adrenaline) and norepinephrine (noradrenaline), plays an important role in modulating bacterial virulence (29, 42).Physical and psychological stress has been linked to increased severity and susceptibility to infection in humans and other animals (23, 42), and epinephrine/norepinephrine levels are an important factor in this. Stress triggers an increase in plasma epinephrine levels (31), and plasma levels of epinephrine and norepinephrine have been reported to increase with patients suffering from postoperative sepsis compared to patients with no complications (32). Administration of norepinephrine and epinephrine to otherwise healthy subjects increases the severity of bacterial infections, including Clostridium perfringens in humans and enterohemorrhagic Escherichia coli (EHEC) in calves (42, 63, 65). Treatment with norepinephrine also increases the virulence of Salmonella enterica serovar Enteritidis in chicks and Salmonella enterica serovar Typhimurium in mice, with a substantial increase in bacterial numbers recovered from the cecum and liver in both cases (47, 65).Norepinephrine is found in large concentrations in the gut due to release by gastrointestinal neurones; indeed up to half the norepinephrine in the body may be produced in the enteric nervous system (ENS) (3). Epinephrine, while not normally found in the gut, is present in the bloodstream and is also produced by macrophages in response to bacteria-derived lipopolysaccharide (LPS) (12, 26). S. Typhimurium is an enteropathogen, can also cross the epithelial barrier to cause systemic infection, and will therefore encounter both these molecules in the normal infection cycle.Phenotypes induced by stress hormones in bacteria include increased adherence of EHEC to bovine intestinal mucosa (63), upregulation of type III secretion and Shiga toxin production in EHEC (22, 60), upregulation of type III secretion in Vibrio parahaemolyticus (51), increase in invasion of epithelial cells and breakdown of epithelial tight junctions by Campylobacter jejuni (15), affected motility and expression of iron uptake genes in S. Typhimurium (8, 9, 36), and modulated virulence in Borrelia burgdorferi (59). Epinephrine and norepinephrine can overcome the growth inhibition of many bacteria, including Salmonella, in serum-containing media (13, 43), due to the ability to act as a siderophore to facilitate iron uptake (13, 28, 47).Norepinephrine and epinephrine also interact with bacterial quorum-sensing (QS) systems. QS is a process of bacterial cell-cell communication in which each cell produces small signal molecules termed “autoinducers” (AIs), which regulate gene expression when a critical threshold concentration and therefore population density have been reached. QS affects diverse processes, including motility, virulence, biofilm formation, type III secretion, and luminescence (6, 64).The EHEC AI-3 QS system is important for motility and expression of the type III secretion system encoded by the locus of enterocyte effacement (LEE) (60). AI-3 sensing and signal transduction are mediated via the QseBC and QseEF two-component systems, respectively. Epinephrine and norepinephrine can substitute for AI-3, causing cross talk between the two signaling systems and induction of type III secretion and motility (57, 60). The sensor kinase QseC is autophosphorylated upon binding either epinephrine or norepinephrine (14), demonstrating the presence of adrenergic receptors in bacteria. These adrenergic phenotypes can also be blocked by the mammalian α- and β-adrenergic antagonists phentolamine and propranolol, although it should be noted that QseC is blocked only by the former (14, 60). This suggests the occurrence of cross talk between bacterial and mammalian cell signaling systems and the existence of multiple bacterial adrenergic sensors.To elucidate the role of host-derived stress hormones in the physiology and pathogenicity of S. Typhimurium, we used MudJ transposon mutagenesis to screen globally for epinephrine- and norepinephrine-regulated genes in S. Typhimurium.     

Estuarine fouling communities are dominated by nonindigenous species in the presence of an invasive crab

Interactions between anthropogenic disturbances and introduced and native species can shift ecological communities, potentially leading to the successful establishment of additional invaders. Since its discovery in New Jersey in 1988, the Asian shore crab (Hemigrapsus sanguineus) has continued to expand its range, invading estuarine and coastal habitats in eastern North America. In estuarine environments, H. sanguineus occupies similar habitats to native, panopeid mud crabs. These crabs, and a variety of fouling organisms (both NIS and native), often inhabit man-made substrates (like piers and riprap) and anthropogenic debris. In a series of in situ experiments at a closed dock in southwestern Long Island (New York, USA), we documented the impacts of these native and introduced crabs on hard-substrate fouling communities. We found that while the presence of native mud crabs did not significantly influence the succession of fouling communities compared to caged and uncaged controls, the presence of introduced H. sanguineus reduced the biomass of native tunicates (particularly Molgula manhattensis), relative to caged controls. Moreover, the presence of H. sanguineus favored fouling communities dominated by introduced tunicates (especially Botrylloides violaceous and Diplosoma listerianum). Altogether, our results suggest that H. sanguineus could help facilitate introduced fouling tunicates in the region, particularly in locations where additional solid substrates have created novel habitats.     

Expression of polypeptide GalNAc-transferases in stratified epithelia and squamous cell carcinomas: immunohistological evaluation using monoclonal antibodies to three members of the GalNAc-transferase family

Mucin-type O-glycosylation is initiated by a large family of UDP- GalNAc: polypeptide N -acetyl-galactosaminyltransferases (GalNAc- transferases). Individual GalNAc-transferases appear to have different functions and Northern analysis indicates that they are differently expressed in different organs. This suggests that O-glycosylation may vary with the repertoire of GalNAc-transferases expressed in a given cell. In order to study the repertoire of GalNAc-transferases in situ in tissues and changes in tumors, we have generated a panel of monoclonal antibodies (MAbs) with well defined specificity for human GalNAc-T1, -T2, and -T3. Application of this panel of novel antibodies revealed that GalNAc- transferases are differentially expressed in different cell lines, in spermatozoa, and in oral mucosa and carcinomas. For example, GalNAc-T1 and -T2 but not -T3 were highly expressed in WI38 cells, and GalNAc-T3 but not GalNAc-T1 or -T2 was expressed in spermatozoa. The expression patterns in normal oral mucosa were found to vary with cell differentiation, and for GalNAc-T2 and -T3 this was reflected in oral squamous cell carcinomas. The expression pattern of GalNAc-T1 was on the other hand changed in tumors to either total loss or expression in cytological poorly differentiated tumor cells, where the normal undifferentiated cells lacked expression. These results demonstrate that the repertoire of GalNAc-transferases is different in different cell types and vary with cellular differentiation, and malignant transformation. The implication of this is not yet fully understood, but it suggests that specific changes in sites of O-glycosylation of proteins may occur as a result of changes in the repertoire of GalNAc-transferases.      

Physical Activity and Reduced Intra‐abdominal Fat in Midlife African‐American and White Women

The purpose of our study was to determine whether self‐reported physical activity (PA), including recreational, household, and exercise activities, is associated with intra‐abdominal fat (IAF) in community‐dwelling white and black midlife women. We performed a cross‐sectional study of 369 women from the Chicago site of the Study of Women's Health Across the Nation (SWAN) ancillary study, the SWAN Fat Patterning Study. PA level was the independent variable, and IAF, assessed by computerized tomography (CT) scan, was the dependent variable. Measures were obtained at SWAN Fat Patterning Baseline visit between August 2002 and December 2005. Linear regression models explored the association between PA and IAF. The first model included IAF as the outcome and total score PA as the main predictor, adjusting for total percent fat mass, age, and ethnicity. The second model included education, parity, sex hormone–binding globulin (SHBG) level, and depressive symptoms, measured by Center for Epidemiological Studies‐Depression (CES‐D) scale. Each 1‐point higher total PA score was associated with a 4.0 cm² lower amount of IAF (P = 0.004), independent of total percent fat mass, age, ethnicity, SHBG level, educational level, CES‐D, and parity. Associations did not differ between white and black women. This study demonstrates a significant negative association between PA and IAF independent of multiple covariates in midlife women. Our findings suggest that motivating white and black women to increase PA during midlife may lessen IAF, which may have a positive impact on subsequent development of diabetes and cardiovascular disease.