Buoyancy adaptations in a swim-bladderless Antarctic fish

The endemic Antarctic teleosts of the suborder Notothenioidei are bottom dwellers. They lack swim bladders, are heavier than seawater, and feed on or near the bottom. The midwaters surrounding the Antarctic continent are productive and underutilized by fishes. There is an evolutionary trend toward pelagism in some notothenioids. We discovered that the largest Antarctic fish, Dissostichus mawsoni, was neutrally buoyant. Attainment of neutral buoyancy was associated with specializations of the skeletal, integumentary, muscular, and digestive systems. The skeleton had a low mineral content and contained considerable cartilage. Scales were also incompletely mineralized. Static lift was obtained from extensive lipid (mostly triglyceride) deposits. A 2–8 mm subcutaneous lipid layer accounted for 4.7% of the body weight. White muscle also contained much lipid–23% on a dry weight basis, or 4.8% of the body weight. Microscopic examination suggested that the liver was active in lipid metabolism, although it was not an organ of buoyancy. Stellate (perisinusoidal) cells with many lipid droplets were a very prominent cytological component of the liver. These specializations made Dissostichus neutrally buoyant and capable of inhabiting the food-rich Antarctic midwaters.     

Smoking cessation and bronchial epithelial remodelling in COPD: a cross-sectional study

Background

Chronic Obstructive Pulmonary Disease (COPD) is associated with bronchial epithelial changes, including squamous cell metaplasia and goblet cell hyperplasia. These features are partially attributed to activation of the epidermal growth factor receptor (EGFR). Whereas smoking cessation reduces respiratory symptoms and lung function decline in COPD, inflammation persists. We determined epithelial proliferation and composition in bronchial biopsies from current and ex-smokers with COPD, and its relation to duration of smoking cessation.

Methods

114 COPD patients were studied cross-sectionally: 99 males/15 females, age 62 ± 8 years, median 42 pack-years, no corticosteroids, current (n = 72) or ex-smokers (n = 42, median cessation duration 3.5 years), postbronchodilator FEV₁ 63 ± 9% predicted. Squamous cell metaplasia (%), goblet cell (PAS/Alcian Blue⁺) area (%), proliferating (Ki-67⁺) cell numbers (/mm basement membrane), and EGFR expression (%) were measured in intact epithelium of bronchial biopsies.

Results

Ex-smokers with COPD had significantly less epithelial squamous cell metaplasia, proliferating cell numbers, and a trend towards reduced goblet cell area than current smokers with COPD (p = 0.025, p = 0.001, p = 0.081, respectively), but no significant difference in EGFR expression. Epithelial features were not different between short-term quitters (<3.5 years) and current smokers. Long-term quitters (≥3.5 years) had less goblet cell area than both current smokers and short-term quitters (medians: 7.9% vs. 14.4%, p = 0.005; 7.9% vs. 13.5%, p = 0.008; respectively), and less proliferating cell numbers than current smokers (2.8% vs. 18.6%, p < 0.001).

Conclusion

Ex-smokers with COPD had less bronchial epithelial remodelling than current smokers, which was only observed after long-term smoking cessation (>3.5 years).

Trial registration

NCT00158847     

Developmental Regulation of Neuregulin1 Isoforms and erbB Receptor Expression in Intact Rat Dorsal Root Ganglia

Neuregulins (NRGs) are a family of growth factors which bind to the erbB family of tyrosine kinase receptors. The exact nature and interaction of specific NRG isoforms and erbB receptors that occur during the development of the nervous system have not been reported. In order to better understand the role that different NRG isoforms and erbB receptors play in the differentiation, proliferation, and survival of neurons and glial cells, we isolated protein and mRNA from dorsal root ganglia of rat pups between embryonic day (E) 13 and postnatal day (P) 15. The relative expression levels of the NRGs and erbB receptors for the different time points were compared using both Western and RT-PCR analyses. NRG1-type1α protein levels were highest at E-13 and then decreased by approximately 40% and remained constant through P-15. In contrast, mRNA levels for NRG1-type1α remained constant from E-15 to P-15. The protein levels for NRG1-type 1β were similar to NRG1-type1α at E-13 with an approximate 40% increase in the levels at E-15 and E-17 followed by a decrease to E-13 levels for the remainder of the developmental time periods. The mRNA levels for NRG1-type1β remained constant from E-15 to P-15. The protein and mRNA expression patterns for each erbB receptor were distinctive. The protein levels for erbB-2 were highest at E-19 while erbB-3 levels were highest at E-17 and E-18. ErbB-4 protein levels were highest at E-13 and decreased through P-15. The developmental pattern for erbB-2 and erbB-4 mRNA levels had no relation to that of the corresponding protein levels while the mRNA levels for erbB-3 were highest at E-17 and E-18 similar to the pattern observed for the erbB-3 protein levels. We concluded that both NRG and erbB expression in dorsal root ganglia are mostly translationally controlled and that NRG1 isoforms and their erbB receptors are not coordinately regulated. Special issue article in honor of Dr. George DeVries.     

Chemopreventive and renal protective effects for docosahexaenoic acid (DHA): implications of CRP and lipid peroxides

Background

The fish oil-derived ω-3 fatty acids, like docosahexanoic (DHA), claim a plethora of health benefits. We currently evaluated the antitumor effects of DHA, alone or in combination with cisplatin (CP) in the EAC solid tumor mice model, and monitored concomitant changes in serum levels of C-reactive protein (CRP), lipid peroxidation (measured as malondialdehyde; MDA) and leukocytic count (LC). Further, we verified the capacity of DHA to ameliorate the lethal, CP-induced nephrotoxicity in rats and the molecular mechanisms involved therein.

Results

EAC-bearing mice exhibited markedly elevated LC (2-fold), CRP (11-fold) and MDA levels (2.7-fold). DHA (125, 250 mg/kg) elicited significant, dose-dependent reductions in tumor size (38%, 79%; respectively), as well as in LC, CRP and MDA levels. These effects for CP were appreciably lower than those of DHA (250 mg/kg). Interestingly, DHA (125 mg/kg) markedly enhanced the chemopreventive effects of CP and boosted its ability to reduce serum CRP and MDA levels. Correlation studies revealed a high degree of positive association between tumor growth and each of CRP (r = 0.85) and leukocytosis (r = 0.89), thus attesting to a diagnostic/prognostic role for CRP. On the other hand, a single CP dose (10 mg/kg) induced nephrotoxicity in rats that was evidenced by proteinuria, deterioration of glomerular filtration rate (GFR, -4-fold), a rise in serum creatinine/urea levels (2–5-fold) after 4 days, and globally-induced animal fatalities after 7 days. Kidney-homogenates from CP-treated rats displayed significantly elevated MDA- and TNF-α-, but reduced GSH-, levels. Rats treated with DHA (250 mg/kg, but not 125 mg/kg) survived the lethal effects of CP, and showed a significant recovery of GFR; while their homogenates had markedly-reduced MDA- and TNF-α-, but -increased GSH-levels. Significant association was detected between creatinine level and those of MDA (r = 0.81), TNF-α ) r = 0.92) and GSH (r = -0.82); implying causal relationships.

Conclusion

DHA elicited prominent chemopreventive effects on its own, and appreciably augmented those of CP as well. The extent of tumor progression in various mouse groups was highly reflected by CRP levels (thus implying a diagnostic/prognostic role for CRP). Further, this study is the first to reveal that DHA can obliterate the lethal CP-induced nephrotoxicity and renal tissue injury. At the molecular level, DHA appears to act by reducing leukocytosis, systemic inflammation, and oxidative stress.     

Delayed onset of adult antifreeze activity in juveniles of the Antarctic icefish <Emphasis Type="Italic">Chaenocephalus aceratus</Emphasis>

Many Antarctic notothenioid species endemic to the Seasonal Pack-ice Zone have converged on adult blood serum freezing points that are several tenths of a degree above the freezing point of seawater. While these fishes share high adult serum freezing points, the development of their freeze avoidance during ontogeny has not been studied. We investigated this in wild caught juveniles of one such species, Chaenocephalus aceratus (family Channichthyidae), using blood serum antifreeze activity as a proxy for their freeze avoidance. Juvenile serum antifreeze activity was significantly below that of adults through the oldest year 2+ specimens collected. This increased at an estimated rate of 0.368 × 10⁻³ ± 0.405 × 10⁻⁴°C day⁻¹ which, if sustained, would leave C. aceratus below their adult serum antifreeze activity levels of 0.57 ± 0.08°C until 4.2 years after hatching. Underlying the 2.7-fold increase in their serum antifreeze activity from late year 0+ juveniles to adults was an even greater 10.4-fold increase in the concentration of their serum antifreeze glycopeptides, which increased proportionally across all of their serum AFGP size isoforms. With insufficient antifreeze activity to avoid freezing in the ice-laden surface waters, both adult and juvenile C. aceratus are most likely restricted to the year round ice-free waters where a metastable supercooled state can be maintained.     

感染球孢白僵菌后红火蚁体内蛋白质含量的变化

为了解球孢白僵菌Beauveria bassiana成功感染红火蚁Solenopsis invicta的生理生化机制, 本研究在室内条件下测定了经球孢白僵菌感染后红火蚁工蚁、蛹和幼蚁体内蛋白质含量的变化。结果表明: 红火蚁各虫态感染球孢白僵菌后体内蛋白质含量变化存在差异。在接种后12-72 h, 工蚁体内蛋白质含量在24 h时最高, 为47.12 mg/g, 显著低于对照的56.40 mg/g(P＜0.05), 此后呈下降趋势, 72 h时蛋白质含量下降至25.16 mg/g。幼蚁在接种36 h时体内蛋白质含量最高, 为24.13 mg/g, 此后呈下降趋势, 72 h时蛋白质含量为8.95 mg/g, 显著低于对照的24.80 mg/g。蛹感染球孢白僵菌后体内蛋白质含量一直呈下降趋势, 从12 h的36.57 mg/g降到72 h的10.42 mg/g, 与对照的38.61 mg/g相比差异显著(P＜0.05)。结果显示球孢白僵菌感染能显著降低红火蚁各虫态体内蛋白质含量。     

Cicada ear geometry: species and sex effects

Many insect species rely on their sense of audition to find a mate, to localize prey or to escape from a predator. Cicadas are particularly known for their loud call and the conspicuous tympanal hearing system located in their abdomen. The vibration pattern of the tympanal membrane (TM) has been investigated recently revealing mechanical properties specific to species and sex. Although TM size and shape is likely to affect these patterns, the geometry of the cicada ear has never been examined per se. Focusing on three Mediterranean cicada species, namely Cicadatra atra, Cicada orni and Lyristes plebejus, we investigated the structure of TM shape variation at two levels, within and across species. Applying an elliptic Fourier analysis to the outlines of both male and female TMs, we estimated sexual dimorphism and species effects. Cicadatra atra showed a large TM compared with its small size, probably as a result of selective constraints related to the role of the TM in sound production. Sexual dimorphism seemed to be greater than interspecific variation, indicating that constraints operating on sex might be more selective than those acting on species identification. In addition, C. orni appeared to be significantly different from the two other species. This morphological peculiarity could be related to the unique vibrational pattern of its membrane. This would establish for the first time a direct link between the shape and mechanism of a hearing organ. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 922–934.     

Phylogeography of the mottled spinefoot Siganus fuscescens: Pleistocene divergence and limited genetic connectivity across the Philippine archipelago

Historical isolation during Pleistocene low sea level periods is thought to have contributed to divergence among marine basin populations across the Coral Triangle. In the Philippine archipelago, populations in the South China Sea, Sulu Sea–inland seas, and Philippine Sea‐Celebes Sea basins might have been partially isolated. Meanwhile, present‐day broadscale oceanographic circulation patterns suggest connectivity between these basins. To evaluate hypotheses regarding the influence of historical and contemporary factors on genetic structure, phylogeographic patterns based on mitochondrial control region sequences for a reef‐associated fish, Siganus fuscescens, were analysed. Three distinct lineages were recovered. One lineage was identified as the morphologically similar species Siganus canaliculatus, while two lineages are monophyletic with S. fuscescens. Clade divergence and demographic expansion in S. fuscescens occurred during the Pleistocene. A strong signal of latitudinal structure was detected (Φ_CT = 0.188), driven by marked differences in clade distribution: one clade is widely distributed (clade A), while a second clade (clade B) has a restricted northern distribution. Regional structure of clade A is consistent with the basin isolation hypothesis (Φ_CT = 0.040) and suggests isolation of the South China Sea (Φ_CT = 0.091). Fine‐scale structure was observed in the South China Sea and south Philippine Sea, while Sulu Sea and inland seas were unstructured. Genetic structure across multiple spatial scales (archipelagic, regional, and fine‐scale within basins) suggests the influence of vicariant barriers and contemporary limits to gene flow in S. fuscescens that may be influenced by oceanographic circulation, geographical distance between available habitats, and latitudinal temperature differences.     

<Emphasis Type="Italic">In vitro</Emphasis> and <Emphasis Type="Italic">ex vivo</Emphasis> effect of hyaluronic acid on erythrocyte flow properties

Background  

Hyaluronic acid (HA) is present in many tissues; its presence in serum may be related to certain inflammatory conditions, tissue damage, sepsis, liver malfunction and some malignancies. In the present work, our goal was to investigate the significance of hyaluronic acid effect on erythrocyte flow properties. Therefore we performed in vitro experiments incubating red blood cells (RBCs) with several HA concentrations. Afterwards, in order to corroborate the pathophysiological significance of the results obtained, we replicated the in vitro experiment with ex vivo RBCs from diagnosed rheumatoid arthritis (RA) patients, a serum HA-increasing pathology.