Dynamic and differential regulation of proteins that coat lipid droplets in fatty liver dystrophic mice

Lipid droplet proteins (LDPs) coat the surface of triglyceride-rich lipid droplets and regulate their formation and lipolysis. We profiled hepatic LDP expression in fatty liver dystrophic (fld) mice, a unique model of neonatal hepatic steatosis that predictably resolves between postnatal day 14 (P14) and P17. Western blotting revealed that perilipin-2/ADRP and perilipin-5/OXPAT were markedly increased in steatotic fld liver but returned to normal by P17. However, the changes in perilipin-2 and perilipin-5 protein content in fld mice were exaggerated compared with relatively modest increases in corresponding mRNAs encoding these proteins, a phenomenon likely mediated by increased protein stability. Conversely, cell death-inducing DFFA-like effector (Cide) family genes were strongly induced at the level of mRNA expression in steatotic fld mouse liver. Surprisingly, levels of peroxisome proliferator-activated receptor γ, which is known to regulate Cide expression, were unchanged in fld mice. However, sterol-regulatory element binding protein 1 (SREBP-1) was activated in fld liver and CideA was revealed as a new direct target gene of SREBP-1. In summary, LDP content is markedly increased in liver of fld mice. However, whereas perilipin-2 and perilipin-5 levels are primarily regulated posttranslationally, Cide family mRNA expression is induced, suggesting that these families of LDP are controlled at different regulatory checkpoints.     

Ladder webs in orb‐web spiders: ontogenetic and evolutionary patterns in Nephilidae

Spider web research bridges ethology, ecology, functional morphology, material science, development, genetics, and evolution. Recent work proposes the aerial orb web as a one‐time key evolutionary innovation that has freed spider‐web architecture from substrate constraints. However, the orb has repeatedly been modified or lost within araneoid spiders. Modifications include not only sheet‐ and cobwebs, but also ladder webs, which secondarily utilize the substrate. A recent nephilid species level phylogeny suggests that the ancestral nephilid web architecture was an arboricolous ladder and that round aerial webs were derived. Because the web biology of the basalmost Clitaetra and the derived Nephila are well understood, the present study focuses on the webs of the two phylogenetically intervening genera, Herennia and Nephilengys, to establish ontogenetic and macroevolutionary patterns across the nephilid tree. We compared juvenile and adult webs of 95 Herennia multipuncta and 143 Nephilengys malabarensis for two measures of ontogenetic allometric web changes: web asymmetry quantified by the ladder index, and hub asymmetry quantified by the hub displacement index. We define a ‘ladder web’ as a vertically elongated orb exceeding twice the length over width (ladder index ≥ 2) and possessing (sub)parallel rather than round side frames. Webs in both genera allometrically grew from orbs to ladders, more so in Herennia. Such allometric web growth enables the spider to maintain its arboricolous web site. Unexpectedly, hub asymmetry only increased significantly in heavy‐bodied Nephilengys females, and not in Herennia, challenging the commonly invoked gravity hypothesis. The findings obtained in the present study support the intrageneric uniformness of nephilid webs, with Herennia etruscilla webs being identical to H. multipuncta. The nephilid web evolution suggests that the ancestor of Nephila reinvented the aerial orb web because the orb arises at a much more inclusive phylogenetic level, and all intervening nephilids retained the secondarily acquired substrate‐dependent ladder web. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 849–866.     

In adult onset myositis, the presence of interstitial lung disease and myositis specific/associated antibodies are governed by HLA class II haplotype, rather than by myositis subtype

The Fcγ receptors play important roles in the initiation and regulation of many immunological and inflammatory processes, and genetic variants (FCGR) have been associated with numerous autoimmune and infectious diseases. The data in rheumatoid arthritis (RA) are conflicting and we previously demonstrated an association between FCGR3A and RA. In view of the close molecular proximity with FCGR2A, FCGR2B and FCGR3B, additional polymorphisms within these genes and FCGR haplotypes were examined to refine the extent of association with RA. Biallelic polymorphisms in FCGR2A, FCGR2B and FCGR3B were examined for association with RA in two well characterized UK Caucasian and North Indian/Pakistani cohorts, in which FCGR3A genotyping had previously been undertaken. Haplotype frequencies and linkage disequilibrium were estimated across the FCGR locus and a model-free analysis was performed to determine association with RA. This was followed by regression analysis, allowing for phase uncertainty, to identify the particular haplotype(s) that influences disease risk. Our results reveal that FCGR2A, FCGR2B and FCGR3B were not associated with RA. The haplotype with the strongest association with RA susceptibility was the FCGR3A–FCGR3B 158V-NA2 haplotype (odds ratio 3.18, 95% confidence interval 1.13–8.92 [P = 0.03] for homozygotes compared with all genotypes). The association was stronger in the presence of nodules (odds ratio 5.03, 95% confidence interval 1.44–17.56; P = 0.01). This haplotype was also more common in North Indian/Pakistani RA patients than in control individuals, but not significantly so. Logistic regression analyses suggested that FCGR3A remained the most significant gene at this locus. The increased association with an FCGR3A–FCGR3B haplotype suggests that other polymorphic variants within FCGR3A or FCGR3B, or in linkage disequilibrium with this haplotype, may additionally contribute to disease pathogenesis.     

Pulse Decomposition Analysis of the digital arterial pulse during hemorrhage simulation

Background

Markers of temporal changes in central blood volume are required to non-invasively detect hemorrhage and the onset of hemorrhagic shock. Recent work suggests that pulse pressure may be such a marker. A new approach to tracking blood pressure, and pulse pressure specifically is presented that is based on a new form of pulse pressure wave analysis called Pulse Decomposition Analysis (PDA). The premise of the PDA model is that the peripheral arterial pressure pulse is a superposition of five individual component pressure pulses, the first of which is due to the left ventricular ejection from the heart while the remaining component pressure pulses are reflections and re-reflections that originate from only two reflection sites within the central arteries. The hypothesis examined here is that the PDA parameter T13, the timing delay between the first and third component pulses, correlates with pulse pressure. T13 was monitored along with blood pressure, as determined by an automatic cuff and another continuous blood pressure monitor, during the course of lower body negative pressure (LBNP) sessions involving four stages, -15 mmHg, -30 mmHg, -45 mmHg, and -60 mmHg, in fifteen subjects (average age: 24.4 years, SD: 3.0 years; average height: 168.6 cm, SD: 8.0 cm; average weight: 64.0 kg, SD: 9.1 kg).

Results

Statistically significant correlations between T13 and pulse pressure as well as the ability of T13 to resolve the effects of different LBNP stages were established. Experimental T13 values were compared with predictions of the PDA model. These interventions resulted in pulse pressure changes of up to 7.8 mmHg (SE = 3.49 mmHg) as determined by the automatic cuff. Corresponding changes in T13 were a shortening by -72 milliseconds (SE = 4.17 milliseconds). In contrast to the other two methodologies, T13 was able to resolve the effects of the two least negative pressure stages with significance set at p < 0.01.

Conclusions

The agreement of observations and measurements provides a preliminary validation of the PDA model regarding the origin of the arterial pressure pulse reflections. The proposed physical picture of the PDA model is attractive because it identifies the contributions of distinct reflecting arterial tree components to the peripheral pressure pulse envelope. Since the importance of arterial pressure reflections to cardiovascular health is well known, the PDA pulse analysis could provide, beyond the tracking of blood pressure, an assessment tool of those reflections as well as the health of the sites that give rise to them.     

Short-term oral progesterone administration antagonizes the effect of transdermal estradiol on endothelium-dependent vasodilation in young healthy women

Very few studies have explored the cardiovascular effects of progesterone in premenopausal women. This study aimed to examine the short-term effects of oral progesterone alone, transdermal estrogen alone, and progesterone and estrogen combined on flow-mediated dilation (FMD) in healthy reproductive-aged women. We suppressed endogenous estrogens and progesterone in 17 premenopausal women for 10-12 days using a gonadotropin-releasing hormone antagonist. On day 4 (hormone suppression condition), subjects were tested (n = 17) and were then supplemented with either 200 mg micronized progesterone (n = 8) orally or 0.1 mg estradiol (n = 9) transdermally per day. On day 7 (progesterone-first or estradiol-first condition), subjects were tested and began supplementation with both hormones (n = 17) and were tested again on day 10 (combined hormone condition). FMD of the brachial artery was assessed using B-mode arterial ultrasound, combined with synchronized Doppler analysis. As a result, significant differences in FMD were observed between hormone suppression (7.85 ± 1.06%) and estrogen-first conditions (10.14 ± 1.40%; P < 0.05). The estradiol-induced increase was abolished when oral progesterone was also supplemented (6.27 ± 0.96%). In contrast, we observed a trend toward a decrease in FMD with unopposed progesterone administration, but no statistically significant differences were found between the progesterone-first (6.66 ± 1.23%), hormone suppression (7.80 ± 1.23%), and combined hormone conditions (7.40 ± 1.29%). In conclusion, these data suggest that short-term oral micronized progesterone administration antagonizes the beneficial effect of transdermal estradiol on FMD.     

Effect of a change in step direction from a forward to a lateral target in response to a sensory perturbation

The aim of the current study was to investigate the response of healthy older and young adults to a change in step direction from a forward to a lateral target in response to a sensory perturbation. Nine healthy older (75.1 ± 6.7 years; age range, 65–81 years) and nine young adults (27 ± 3.6 years; age range, 23–31 years) participated in the study. The sensory perturbation was a visual cue presented at random times while subjects stepped over an obstacle from quiet stance. For both young and elderly subjects there was an abrupt change in the slope of both shear ground reaction forces (GRFs) of the stance limb following the perturbation. The slope and peak of the change in GRFs was greater for the young subjects and the onset significantly earlier (205 ms compared to 271 ms). Changes in the GRFs were accompanied by an increase in bilateral gluteus medius and stance limb soleus activity. A late visual cue resulted in a delayed response for elderly subjects. These data show that a stepping response to a sensory perturbation was both delayed and of less magnitude for older adults which has implications for fall risk.     

Identification of ADPR-transferase activity in the rat tapeworm, Hymenolepis diminuta

1. The nuclear fraction of the rat tapeworm Hymenolepis diminuta (Cestoda) contains the enzyme adenosine diphosphoribosyl transferase (ADPR-transferase). 2. The enzyme catalyzes the postsynthetic modification of some nuclear proteins by the covalent attachment of the (ADP-ribose) moiety of NAD to such proteins. 3. The reaction is dependent on DNA which contains strand-breaks, and chain lengths equivalent to (ADP-ribose) is estimated. 4. The formation of polynucleotide products was competitively inhibited by 3-acetamidobezamide, with a Km of 125 microM. 5. The catalytic properties of ADPR-transferase in Hymenolepis diminuta are similar to those in T. brucei.     

The Partial Characterization of a Badnavirus Infecting the Greater Asiatic or Water Yam (Dioscorea alata)

A bacilliform virus from Dioscorea alata, designated Dioscorea alata bacilliform virus (DaBV), from Barbados and West Africa and from other Dioscorea spp. from West African, Carribean, Asian and South American countries, has been characterized. The virus was transmitted by the mealybug, Planococcus citri and by mechanical transmission of partially purified preparations to several Dioscorea spp. DaBV was serologically related to a distinct bacilliform virus from Dioscorea bulbifera, to one isolate of sugarcane bacilliform badnavirus and two isolates of banana streak badnavirus (BSV) but was not related to another isolate of BSV or to Kalanchoe top spotting or cacao swollen shoot badnaviruses. The coat protein of DaBV was about 56 kDa and the nucleic acid was double-stranded DNA of about 7.5 kbp, part of which showed distant homology with other badnaviruses. Thus, DaBV is a distinct hitherto uncharacterized badnavirus.     

Differentiation-related changes in glycoprotein synthesis by human keratinocytes.

Human keratinocytes were cultured in media in which the Ca2+ concentration controlled the stage of differentiation. In media containing less than 0.1 mM-Ca2+ keratinocytes grew as a monolayer, but in the presence of 2mM-Ca2+ the cells differentiated and formed stratified colonies. Glycoproteins of both stratified and unstratified cells were radiolabelled by metabolic incorporation of radioactive precursors and by cell-surface labelling using galactose oxidase/NaB3H4. The radiolabelled keratinocytes were extracted with 0.5% Triton X-100, and the glycoproteins in both the Triton X-100-soluble and Triton X-100-insoluble fractions were analysed by polyacrylamide-gel electrophoresis in the presence of SDS. Two Triton X-100-soluble glycoproteins with high Mr values (greater than 200,000) were major glycoproteins in stratified keratinocytes, but were present in only trace amounts in unstratified keratinocytes. Characterization of these glycoproteins by examination of the effect of tunicamycin on their synthesis and the effect of neuraminidase on their migration characteristics showed that they were cell-surface sialoglycoproteins containing O-glycosidically linked oligosaccharides. Analysis of the adherent cytoskeletons left after Triton X-100 extraction of stratified and unstratified keratinocytes revealed that a glycoprotein of Mr 184,000 was decreased in stratified keratinocytes. Incubation of unstratified keratinocytes in high-Ca2+ medium resulted in a rapid modification of the glycoprotein of Mr 184,000, and it is suggested that this event may be related to desmosome formation and stratification.     

The microfauna of algal mats and artificial substrates in Southern Victoria Land lakes of Antarctica

The first microfaunal colonization study of continental lakes in Antarctica is reported. In addition to the general taxonomic composition of six Antarctic lakes, detailed community composition analyses of two adjacent lakes, Lake Fryxell and Lake Hoare, using polyurethane foam artificial substrates suspended in the open water and placed directly over benthic algal mats are also presented. Protozoans, rotifers, tardigrades and nematodes constituted the microfaunal community in all lakes. Higher metazoans do not occur in lakes that we studied. Protozoans were the most diverse of the four groups, and the first dinoflagellates reported from southern Victoria Land, Gymnodinium and Glenodinium, were collected from Lake Fryxell. The greatest number of protozoan taxa (55) were associated with the algal mats in the more productive Lake Fryxell. Both the physical and chemical properties and taxonomic diversity showed marked variability between all lakes that were studied, especially the adjacent lakes, Fryxell and Hoare. Ecological variables which regulate taxonomic diversity in other lakes of the world also appear to exert similar influences in remote Antarctic lakes.