The role of sinking particles in the overwintering process of Vibrio parahaemolyticus in a marine environment

Abstract The behavioral pattern of Vibrio parahaemolytics during the winter season (December 1988 to March 1989) in the water column, sediment, plankton and sinking particles was determined in a eutrophic marine environment. A total of 15 environmental parameters and seven microbial characteristics were examined. This halophile was isolated sporadically from bottom water and plankton materials, whereas it was undetectable in the surface water and sediment samples. However, V. parahaemolyticus was isolated from the sinking particles continuously throughout the sampling period with highest counts during February 1989. Out of 195 strains identified, 10 Vibrio spp. and 3 Listonella spp. were observed of which V. alginolyticus was predominantly isolated irrespective of the samples tested. Simple correlation and multiple regression analyses show that the occurrence of V. parahaemolyticus is not governed by any single biotic or abiotic factor of the environment. Possibly, the cumulative effect of all these environmental parameters on the distribution of V. parahaemolyticus is conceivable.     

Statistical Modeling of Observational Data With Spatial Dependencies

Abstract I provide a brief introduction to the concept of spatial autocorrelation and its incorporation into regression-type models. Spatial autocorrelation occurs when the response variable is correlated with itself at other locations in the region of interest. The autocorrelation usually takes a specific form where observations close in space are more correlated than those farther apart, and the rate of decay of the correlation is a function of the distance separating 2 locations. I present 2 commonly used models: 1) geostatistical modeling in which data are collected at points in the study region and 2) conditional autoregression (lattice) models in which data are aggregated over small nonoverlapping sub-areas of the study region. I also describe incorporation of explanatory covariates, such as habitat or physico-chemical attributes. I emphasize frequentist methods, but I briefly describe Bayesian approaches. I also provide some advantages, such as obtaining correct standard errors for estimators, and disadvantages, such as requirements for larger sample sizes, of incorporating spatial autocorrelation into the modeling effort. This information can aid researchers in designing and analyzing models of the relationships between species distributions and habitat. As a result, more informative models can be developed which further aid in management of wildlife.     

Future habitat suitability for coral reef ecosystems under global warming and ocean acidification

Rising atmospheric CO₂ concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature‐driven decline in habitat suitability for many of the most significant and bio‐diverse tropical coral regions, particularly in the central Indo‐Pacific. This is accompanied by a temperature‐driven poleward range expansion of favorable conditions accelerating up to 40–70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered ‘marginal’ for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short‐term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO₂ on potential future habitats, but greater understanding of past and current controls on coral reef ecosystems is essential to their conservation and management under a changing climate.     

A GIS-based Model of the Distribution of the Rare Liverwort Aneura maxima at the Landscape Scale for an Improved Assessment of Its Conservation Status

Testing whether rare species are limited by narrow habitat conditions from correlations between species occurrence and measured environmental factors is usually hampered by the lack of statistical power associated to the low number of observations. Aneura maxima is an exceedingly rare liverwort in Europe whose recent discovery precluded the inclusion within the Red Data Book of European bryophytes. A series of new observations resulting from intensive bryophyte grid-mapping at the border between France and Belgium allowed the statistical investigation of the factors accounting for its distribution at the landscape scale. The species was systematically observed in deep ravines on damp, loamy soils under light tree cover within broadleaf woodlands. These conditions differ from those of other European localities, suggesting that A. maxima is not limited by a narrow ecological range. Attempting to predict the occurrence of A. maxima at the landscape scale from data on land use and soil conditions resulted in a model where the species was actually observed in only a half of the squares where its probability of occurrence was the highest. The species thus does not seem to have colonized all its potential habitats, which may be explained by the poor dispersal ability of this dioecious, rarely fertile species. Given the relative frequency of A. maxima in the Semois river basin, but taking into account its seemingly low dispersal ability and its preference for swampy habitats that are threatened by draining and spruce plantations, a status as 'conservation dependent' to 'near threatened' within the category 'lower risk' is proposed.     

Seasonal incidence of hospital admissions for Stanford type A aortic dissection

The objective of this study was to test the hypothesis that there is seasonal variation in the incidence of Stanford type A aortic dissection (SA-AoD) among patients admitted to our cardiovascular surgical service. A sinusoidal logistic regression model was used to analyze event data for 6081 calendar days. A cyclic peak risk for SA-AoD was observed for calendar day 304 (p?=?0.019). The odds ratios for the 3- and 6-month window surrounding this peak were 1.6 (p?=?0.054) and 1.7 (p?=?0.0040), respectively. Our results suggest than a seasonal variation exists in the incidence of SA-AoD.     

Offspring-parent regression for a binary trait

Summary Offspring-parent regression is often used to estimate the heritability of a quantitative trait. It is shown that for a purely binary trait, the regression of offspring on one parent is always linear, while that on both parents or mid-parent is generally nonlinear. However, the regressions are linear on a logistic scale.     

Nanocell targeting using engineered bispecific antibodies

There are many design formats for bispecific antibodies (BsAbs), and the best design choice is highly dependent on the final application. Our aim was to engineer BsAbs to target a novel nanocell (EnGeneIC Delivery Vehicle or EDV^TMnanocell) to the epidermal growth factor receptor (EGFR). EDV^TMnanocells are coated with lipopolysaccharide (LPS), and BsAb designs incorporated single chain Fv (scFv) fragments derived from an anti-LPS antibody (1H10) and an anti-EGFR antibody, ABX-EGF. We engineered various BsAb formats with monovalent or bivalent binding arms and linked scFv fragments via either glycine-serine (G4S) or Fc-linkers. Binding analyses utilizing ELISA, surface plasmon resonance, bio-layer interferometry, flow cytometry and fluorescence microscopy showed that binding to LPS and to either soluble recombinant EGFR or MDA-MB-468 cells expressing EGFR, was conserved for all construct designs. However, the Fc-linked BsAbs led to nanocell clumping upon binding to EDV^TMnanocells. Clumping was eliminated when additional disulfide bonds were incorporated into the scFv components of the BsAbs, but this resulted in lower BsAb expression. The G4S-linked tandem scFv BsAb format was the optimal design with respect to EDV binding and expression yield. Doxorubicin-loaded EDV^TMnanocells actively targeted with tandem scFv BsAb in vivo to MDA-MB-468-derived tumors in mouse xenograft models enhanced tumor regression by 40% compared to passively targeted EDV^TMnanocells. BsAbs therefore provide a functional means to deliver EDV^TMnanocells to target cells.