Transgenic mice expressing a chimaeric anti-E. coli immunoglobulin α heavy chain gene

To induce constitutive immunity against a pathogenic strain ofEscherichia coli (K99), a rearranged immunoglobulin (Ig) heavy chain (HC) gene was constructed. Because the route ofE. coli infection is enteric, an IgA transgene was desirable. A chimaeric gene construct was cloned that coded for a HC that recognized a specificE. coli pilus antigen. The construct comprised a gene promoter, murine VDJ, and bovine -HC constant region. Following microinjection of the HC construct into murine zygotes, of 50 liveborn mice, three were identified as transgenic. In all three transgenic founders, transgene-encoded mRNA expression was detected by northern blot. The transgenic founders were analysed for transgene-encoded RNA expression in splenic tissue before and after challenge with pathogenicE. coli. Founder 4-3 expressed transgene-encoded RNA both before and after challenge; expression was detected in the other two founders only post-challenge. As no differences were found when sera were analysed for bovine IgA in control and transgenic mice, protein expression was assessed by challenge of HC founders with K99E. coli by gavage. Control mice challenged with K99E. coli were moribund within 24 h post-gavage, but there was no observable affect in the three transgenic founders. Unfortunately, after obtaining offspring from all founders, no transgenic offspring were identified (0/108). The low yield of transgenic founders, coupled with the apparent germ-line mosaicism may point to either mechanical or critical developmental anomalies. However, the production of transgenic mice harbouring an Ig HC gene construct confirmed that an Ig transgene coding for an antibody to an animal pathogen could function in a tissue-specific and protective manner in a mammalian system.     

Estimating the relative abundance of emperor penguins at inaccessible colonies using satellite imagery

Emperor penguin (Aptenodytes forsteri) populations are useful environmental indicators due to the bird’s extreme reliance on sea ice. We used remote sensing technology to estimate relative adult bird abundance at two inaccessible emperor penguin colonies in the Ross Sea, Antarctica. We performed supervised classification of 12 panchromatic satellite images of the seven known Ross Sea colonies. We used regression to predict adult bird counts at the inaccessible colonies by relating the number of pixels classified as “penguin” in the satellite images of the accessible colonies to corresponding known adult bird counts from aerial photographs or ground counts. While our analysis was hampered by excessive guano and shadows, we used satellite imagery to differentiate between relatively small (<3,000 adult birds) and larger colonies (>5,000 adult birds). Remote sensing technology is logistically less intense and less costly than aerial or ground censuses when the objective is to document penguin presence and/or large emperor penguin population changes (e.g., catastrophic changes). Improvements expected soon in the resolution of the satellite images should allow for more accurate abundance estimates.     

From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly

Seed dispersal is a key process in plant spatial dynamics. However, consistently applicable generalizations about dispersal across scales are mostly absent because of the constraints on measuring propagule dispersal distances for many species. Here, we focus on fleshy-fruited taxa, specifically taxa with large fleshy fruits and their dispersers across an entire continental rainforest biome. We compare species-level results of whole-chloroplast DNA analyses in sister taxa with large and small fruits, to regional plot-based samples (310 plots), and whole-continent patterns for the distribution of woody species with either large (more than 30 mm) or smaller fleshy fruits (1093 taxa). The pairwise genomic comparison found higher genetic distances between populations and between regions in the large-fruited species (Endiandra globosa), but higher overall diversity within the small-fruited species (Endiandra discolor). Floristic comparisons among plots confirmed lower numbers of large-fruited species in areas where more extreme rainforest contraction occurred, and re-colonization by small-fruited species readily dispersed by the available fauna. Species'' distribution patterns showed that larger-fruited species had smaller geographical ranges than smaller-fruited species and locations with stable refugia (and high endemism) aligned with concentrations of large fleshy-fruited taxa, making them a potentially valuable conservation-planning indicator.     

HEART RATE AND ELECTROCARDIOGRAM CHARACTERISTICS OF A YOUNG CALIFORNIA GRAY WHALE (ESCHRICHTIUS ROBUSTUS)1

Electrocardiogram (ECG) analyses of Holter monitor recordings from a young California gray whale were performed to determine ECG waveform characteristics, evaluate the heart rate pattern for sinus arrhythmia, obtain resting heart rates at known body masses as the whale increased in size, and compare those heart rates with predicted heart rates from allometric equations. The PR and QRS intervals (475 ± 35 msec, 208 ± 24 msec, respectively, n= 20) support the concept (Meijler et al. 1992) that atrioventricular transmission and ventricular excitation times do not increase linearly in very large mammals. A sinus arrhythmia pattern at rest (apneic heart rates of 15–25 beats per min [bpm] and eupneic heart rates of 34–40 bpm) is consistent with a relative eupneic tachycardia and apneic bradycardia during diving activity of whales. The heart rate-body mass measurements (35–24 bpm at body masses of 3,591-8,200 kg) in this study (1) extend the range of allometric heart rate and body mass data in mammals a full order of magnitude, to almost 10,000 kg, (2) support the use of allometric equations (based primarily on mammals <1,000 kg in body mass) in estimating resting heart rates in whales, and (3) demonstrate that previously reported heart rates in large whales are not representative of resting heart rate, probably secondary to circumstances during measurement.     

Constitutive expression of IL-22 in the human intervertebral disc and its reduction by exposure to pro-inflammatory cytokines in vitro

The importance of cytokines in disc degeneration is well recognized. Little is known about IL-22 expression in the human intervertebral disc. We investigated IL-22 immuno-localization in disc tissue, and molecular expression and production of IL-22 by annulus cells cultured in three-dimensional (3D) culture. We examined human disc tissue using immunohistochemistry and we cultured isolated annulus cells in 3D to analyze IL-22 expression and production, and its receptor, IL-22R, in conditioned media. Ingenuity pathway analysis (IPA) also was used to identify significant gene expression networks within the molecular data. IL-22 and IL-22R were immunolocalized in many cells in the human outer and inner annulus; fewer cells exhibited localization in the nucleus. Three-dimensional culture of annulus cells demonstrated production of IL-22 in conditioned media; exposure to IL-1ß or TNF-α significantly reduced IL-22 levels. Significant decreases also were identified in conditioned media assayed for IL-22R in TNF-α treated cells. IPA analysis showed that IL-22 ranked among the top canonical pathways. We found constitutive expression and production of IL-22 and IL-22R in the disc, which expands our understanding of the effect of pro-inflammatory cytokines on IL-22 expression and production. Three-dimensional cultured annulus cells exposed to IL-1ß or TNF produced significantly lower levels of IL-22 into their conditioned media compared to levels produced by control cells. Our findings have clinical relevance because of the elevated pro-inflammatory milieu within the degenerating human disc.     

Fuel homeostasis in the harbor seal during submerged swimming

1. The turnover rates and oxidation rates of plasma glucose, lactate, and free fatty acids (FFA) were measured in three harbor seals (average mass = 40 kg) at rest or during voluntary submerged swimming in a water flume at 35% (1.3 m.s-1) and 50% (2 m.s-1) of maximum oxygen consumption (MO2max). 2. For seals resting in water, the total turnover rates for glucose, lactate, and FFA were 23.2, 26.2, and 7.5 mumols.min-1.kg-1, respectively. Direct oxidation of these metabolites accounted for approximately 7%, 27%, and 33% of their turnover and 3%, 7%, and 18% of the total ATP production, respectively. 3. For swimming seals, MO2max was achieved at a drag load equivalent to a speed of 3 m.s-1 and averaged 1.85 mmol O2.min-1.kg-1, which is 9-fold greater than resting metabolism in water at 18 degrees C. 4. At 35% and 50% MO2max, glucose turnover and oxidation rates did not change from resting levels. Glucose oxidation contributed about 1% of the total ATP production during swimming. 5. At 50% MO2max, lactate turnover and anaerobic ATP production doubled, but the steady state plasma lactate concentration remained low at 1.1 mM. Lactate oxidation increased 63% but still contributed only 4% of the total ATP production. Anaerobic metabolism contributed about 1% of the total ATP production at rest and during swimming. 6. The plasma FFA concentration and turnover rate increased only 24% and 37% over resting levels, respectively, at 50% MO2max. However, the oxidation rate increased almost 3.5-fold and accounted for 85% of the turnover.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gondwanan survivor lineages and the high-risk biogeography of Anthropocene Southeast Asia

The Southeast Asian rainforest region is extremely complex and biodiverse. Fossils have shown that paleo-Antarctic rainforest lineages (PARLs) now extant in Asia tracked the ever-wet conditions needed to survive and diversify through deep time. However, the threat of future climate change to the remaining rainforest and PARLs in Southeast Asia has yet to be evaluated to set conservation priorities. We first quantified the woody-genus floristic relationships of Southeast Asian Island Groups by vetting and analyzing recent compilations of bioregional species data. We then evaluated the contributions to community assembly of woody fossil lineages and Island Group relationships to environmental gradients. To better understand climatic constraints of fossil lineage distributions and forecast distributions under projected future climate, we used exemplar living woody PARLs, including two angiosperms and two gymnosperms. Generalized linear models were used to project potential distributions under future climate pathways that assume no reduction in carbon dioxide emissions. The floristic analyses highlighted strong similarities among Island Groups in the ever-wet forest areas of Malesia, where PARLs are often concentrated. Ordination outliers represented more seasonal locations. Species distribution models showed that potential future distributions of ancient lineages are constrained by increasing rainfall seasonality and higher seasonal temperatures, with significant differences among exemplar genera. Notably, potential distributions often mapped onto de facto inaccessible areas, where forest clearing and the ubiquitous marine dispersal barriers that characterize the region will drastically inhibit potential relocation. These realities gravely threaten paleo-conservation values and contemporary rainforest community assembly processes in Southeast Asia.