The Effect of Habitual Smoking on VO2max

VO2max is associated with many factors, including age, gender, physical activity, and body composition. It is popularly believed that habitual smoking lowers aerobic fitness. PURPOSE: to determine the effect of habitual smoking on VO2max after controlling for age, gender, activity and BMI. METHODS: 2374 men and 375 women employed at the NASA/Johnson Space Center were measured for VO2max by indirect calorimetry (RER>=1.1), activity by the 11 point (0-10) NASA Physical Activity Status Scale (PASS), BMI and smoking pack-yrs (packs day*y of smoking). Age was recorded in years and gender was coded as M=1, W=0. Pack.y was made a categorical variable consisting of four levels as follows: Never Smoked (0), Light (1-10), Regular (11-20), Heavy (>20). Group differences were verified by ANOVA. A General Linear Models (GLM) was used to develop two models to examine the relationship of smoking behavior on VO2max. GLM #1(without smoking) determined the combined effects of age, gender, PASS and BMI on VO2max. GLM #2 (with smoking) determined the added effects of smoking (pack.y groupings) on VO2max after controlling for age, gender, PASS and BMI. Constant errors (CE) were calculated to compare the accuracy of the two models for estimating the VO2max of the smoking subgroups. RESULTS: ANOVA affirmed the mean VO2max of each pack.y grouping decreased significantly (p<0.01) as the level of smoking exposure increased. GLM #1 showed that age, gender, PASS and BMI were independently related with VO2max (R2 = 0.642, SEE = 4.90, p<0.001). The added pack.y variables in GLM #2 were statistically significant (R2 change = 0.7%, p<0.01). Post hoc analysis showed that compared to Never Smoked, the effects on VO2max from Light and Regular smoking habits were -0.83 and -0.85 ml.kg- 1.min-1 respectively (p<0.05). The effect of Heavy smoking on VO2max was -2.56 ml.kg- 1.min-1 (p<0.001). The CE s of each smoking group in GLM #2 was smaller than the CE s of the smoking group counterparts in GLM #1. CONCLUSIONS: After accounting for the effects of gender, age, PASS and BMI the effect of habitual smoking on reducing VO2max is minimal, about 0.85 ml/kg/min, until the habit exceeds 20 pack.y at which point an additional decrease of 1.71 ml/kg/min is noted. Adding pack.y data improves the accuracy of predicting the VO2max of smokers

Taming the symbiont for coexistence: a host PGRP neutralizes a bacterial symbiont toxin

In horizontally-transmitted mutualisms between marine animals and their bacterial partners, the host environment promotes the initial colonization by specific symbionts that it harvests from the surrounding bacterioplankton. Subsequently, the host must develop long-term tolerance to immunogenic bacterial molecules, such as peptidoglycan and lipopolysaccaride derivatives. We describe the characterization of the activity of a host peptidoglycan-recognition protein (EsPGRP2) during establishment of the symbiosis between the squid Euprymna scolopes and its luminous bacterial symbiont Vibrio fischeri. Using confocal immunocytochemistry, we localized EsPGRP2 to all epithelial surfaces of the animal, and determined that it is exported in association with mucus shedding. Most notably, EsPGRP2 was released by the crypt epithelia into the extracellular spaces housing the symbionts. This translocation occurred only after the symbionts had triggered host morphogenesis, a process that is induced by exposure to the peptidoglycan monomer (TCT), a bacterial ‘toxin’ that is constitutively exported by V. fischeri. Enzymatic analyses demonstrated that, like many described PGRPs, EsPGRP2 has a TCT-degrading amidase activity. The timing of EsPGRP2 export into the crypts provides evidence that the host does not export this protein until after TCT induces morphogenesis, and thereafter EsPGRP2 is constantly present in the crypts ameliorating the effects of V. fischeri TCT

Peptidoglycan Induces Loss of a Nuclear PGRP During Host Tissue Development in a Beneficial Animal–Bacterial Symbiosis

Peptidoglycan recognition proteins (PGRPs) are mediators of innate immunity and recently have been implicated in developmental regulation. To explore the interplay between these two roles, we characterized a PGRP in the host squid Euprymna scolopes (EsPGRP1) during colonization by the mutualistic bacterium Vibrio fischeri. Previous research on the squid-vibrio symbiosis had shown that, upon colonization of deep epithelium-lined crypts of the host light organ, symbiont-derived peptidoglycan monomers induce apoptosis-mediated regression of remote epithelial fields involved in the inoculation process. In this study, immunofluorescence microscopy revealed that EsPGRP1 localizes to the nuclei of epithelial cells, and symbiont colonization induces the loss of EsPGRP1 from apoptotic nuclei. The loss of nuclear EsPGRP1 occurred prior to DNA cleavage and breakdown of the nuclear membrane, but followed chromatin condensation, suggesting that it occurs during late stage apoptosis. Experiments with purified peptidoglycan monomers and with V. fischeri mutants defective in peptidoglycan-monomer release provided evidence that these molecules trigger nuclear loss of EsPGRP1 and apoptosis. The demonstration of a nuclear PGRP is unprecedented, and the dynamics of EsPGRP1 during apoptosis provide a striking example of a connection between microbial recognition and developmental responses in the establishment of symbiosis

Cortical Symbionts and Hydrogenosomes of the Amitochondriate Protist Staurojoenina Assimilis

Adhering epibionts with distinctive attachment structures form surface striations on Staurojoenina, a termite hindgut hypermastigote. These striations, first called cuticle thickenings by Kirby, are always present on Staurojoenina assimilis and are intrinsic to the description of the species in this genus of amitochondriate protists. Studies of the live protist by videomicroscopy, fluorescence light microscopy, scanning and transmission electron microscopy as well as 16S rRNA analysis confirm their identity. Each of the conspicuous, uniformly distributed, surface striations (0.2-0.3 [mu]m x 2.5-7.0 [mu]m) is attached longitudinally by a hook to the protist membrane. They contain nucleoids that fluoresce with SYTOX, a DNA stain. The striations are rod-shaped, gram-negative enterobacteriaceae. Phylogenetic analysis using the 16S rRNA genes show that the epibionts can be placed firmly within the Citrobacter clade. Although they have not been isolated and grown in culture we argue that enough morphological, ecological and molecular biological information about these surface symbionts of Stattrojoenina assimilis exist for them to merit identification by name. Accordingly we formally describe the epibionts as Candidatus Cuticobacterium kirbyi. These specimens were taken from a newly discovered source of Staurojoenina assimilis from two Caribbean islands

Devescovinid Trichomonad with Axostyle-Based Rotary Motor (“Rubberneckia”): Taxonomic Assignment as Caduceia Versatilis Sp. Nov.

An amitochondriate trichomonad cell of the family Devescovinidae (Class Parabasalia), helped demonstrate the fluid model of lipoprotein cell membranes [24]. This woodingesting symbiont in the hindgut of the dry wood-eating termite Cryptotermes cavifrons is informally known to cell biologists as “Rubberneckia”. As the microtubular axostyle complex generates force causing clockwise movement of the entire anterior portion of the cell at the shear zone the protist displays “head” rotation. Studies by phase contrast and videomicroscopy of live cells, of whole mounts by scanning, and thin sections by transmission electron microscopy extend the observations of Tamm and Tamm [24–26] and Tamm [19–23]. Habitat, cell shape, size, nuclear features, parabasal apparatus and other morphological details permit the assignment of “Rubberneckia” to Kirby’s cosmopolitan genus Caduceia. This large-sized devescovinid has distinctive parabasal gyres, an axostylar rotary motor, and regularly-associated nonflagellated, fusiform and flagellated rod epibiotic surface bacteria. In addition to regularly aligned epibionts intranuclear and endocytoplasmic bacteria are abundant and hydrogenosomes are present. “Rubberneckia” is compared here to the other seven species of Caduceia, Since it is clearly sufficiently distinctive to warrant new species status, we named it C. versatilis

Cysts and Symbionts of Staurojoenina Assimilis Kirby from Neotermes

Staurojoenina assimilis Kirby, a hindgut hypermastigote parabasalid symbiont in two kalotermitids (Neotermes mona St. John, US Virgin Islands and N. jouteli Puerto Rico) was studied live and by electron microscopy. In this first description of hypermastigote protist cysts in termite intestines we report numerous of these translucent walled spheres in a population of S. assimilis in the hindgut of one pseudergate from a Puerto Rican mangrove community. Tightly adhering, regularly spaced rod bacteria were observed on the surfaces of all live S. assimilis cells. The bacterial nature of these ectosymbiotic rods was verified by TEM and SEM. They are present on the four anterior lobes and most of the rest of the surface of this hypermastigote. The processes by which these ectosymbionts may be retained after ingestion, propagated and transported to the protist\u27s outer membrane are suggested. The ultrastructure of other unknown symbionts, endonuclear microbes that resemble Caryococcus, perhaps pleiomorphic Gram negative bacteria, is also described

Spirochete Attachment Ultrastructure: Implications for the Origin and Evolution of Cilia

The fine structure of spirochete attachments to the plasma membrane of anaerobic protists displays variations here interpreted as legacies of an evolutionary sequence analogous to that from free-living spirochetes to undulipodia (eukaryotic “flagella” and homologous structures). Attached spirochetes form a vestment, a wriggling fringe of motile cells at the edge of the plasma membrane of unidentified cellulolytic protist cells in the hypertrophied hindgut of the digestive system of Mastotermes darwiniensis, the large wood-feeding termite from northern Australia. From the membrane extend both undulipodia and a complex of comparably sized (10–12 μm × 0.2–0.3 μm) ectosymbiotic spirochetes that resembles unruly ciliated epithelium. In the intestines are helical (swimming) and round-body morphotypes. Round bodies (RBs) are slow or immotile spirochetes, propagules known to revert to typical swimming helices under culture conditions favorable for growth. The surfaces of both the spirochete gram-negative eubacteria and the parabasalid protists display distinctive attachment structures. The attached hypertrophied structures, some of which resemble ciliate kinetids, are found consistently at sites where the spirochete termini contact the protist plasma membranes