Burrowing behaviour in the crayfish, Cambarus diogenes diogenes girard

The crayfish, Cambarus diogenes diogenesGirard (1852), spends most of its life cycle in individually constructed underground burrows. The architectural behavioral patterns and sequences with which adult C. d. diogenes excavate an underground chamber were evaluated. Two motor patterns (Pushing and Carrying) and three burrow stages (shallow depression, angular pit, and burrow with two openings) were identified. During the development of burrowing behaviour in juveniles, a third motor pattern (Fanning) occurred. While the three motor patterns are functional soon after hatching, crayfish may learn to orient the Carrying motor pattern for the most efficient excavation of a stage-3 burrow with two openings. The ground-water level determined the final structure of a burrow.     

Role of ultrasonography in diagnosing early rheumatoid arthritis and remission of rheumatoid arthritis - a systematic review of the literature

Introduction

Ultrasonography (US) might have an added value to clinical examination in diagnosing early rheumatoid arthritis (RA) and assessing remission of RA. We aimed to clarify the added value of US in RA in these situations performing a systematic review.

Methods

A systematic literature search was performed for RA, US, diagnosis and remission. Methodological quality was assessed; the wide variability in the design of studies prohibited pooling of results.

Results

Six papers on the added value of US diagnosing early RA were found, in which at least bilateral metacarpophalangeal (MCP), wrists and metatarsophalangeal (MTP) joints were scanned. Compared to clinical examination, US was superior with regard to detecting synovitis and predicting progression to persistent arthritis or RA. Eleven papers on assessing remission were identified, in which at least the wrist and the MCP joints of the dominant hand were scanned. Often US detected inflammation in patients clinically in remission, irrespective of the remission criteria used. Power Doppler signs of synovitis predicted X-ray progression and future flare in patients clinically in remission.

Conclusions

US appears to have added value to clinical examination for diagnosing of RA when scanning at least MCP, wrist and MTP joints, and, when evaluating remission of RA, scanning at least wrist and MCP joints of the dominant hand. For both purposes primarily power Doppler US might be used since its results are less equivocal than those of greyscale US.     

Small,odd and old: The mysterious Tarsius pumilus is the most basal Sulawesi tarsier

In this study, we present the first genetic evidence of the phylogenetic position of Tarsius pumilus, the mountain tarsier of Sulawesi, Indonesia. This mysterious primate is the only Eastern tarsier species that occurs exclusively in cloud forests above 1800 m.a.s.l. It exhibits striking morphological peculiarities—most prominently its extremely reduced body size, which led to the common name of ‘pygmy tarsier’. However, our results indicate that T. pumilus is not an aberrant form of a lowland tarsier, but in fact, the most basal of all Sulawesi tarsiers. Applying a Bayesian multi-locus coalescent approach, we dated the divergence between the T. pumilus lineage and the ancestor of all other extant Sulawesi tarsiers to 9.88 Mya. This is as deep as the split between the two other tarsier genera Carlito (Philippine tarsiers) and Cephalopachus (Western tarsiers), and predates further tarsier diversification on Sulawesi by around 7 Myr. The date coincides with the deepening of the marine environment between eastern and western Sulawesi, which likely led to allopatric speciation between T. pumilus or its predecessor in the west and the ancestor of all other Sulawesi tarsiers in the east. As the split preceded the emergence of permanent mountains in western Sulawesi, it is unlikely that the shift to montane habitat has driven the formation of the T. pumilus lineage.     

Regulation of exercise carbohydrate metabolism by estrogen and progesterone in women

To assess the roles of endogenous estrogen (E2) and progesterone (P4) in regulating exercise carbohydrate use, we used pharmacological suppression and replacement to create three distinct hormonal environments: baseline (B), with E2 and P4 low; estrogen only (E), with E2 high and P4 low; and estrogen/progesterone (E + P), with E2 and P4 high. Blood glucose uptake (R(d)), total carbohydrate oxidation (CHO(ox)), and estimated muscle glycogen utilization (EMGU) were assessed during 60 min of submaximal exercise by use of stable isotope dilution and indirect calorimetry in eight eumenorrheic women. Compared with B (1.26 +/- 0.04 g/min) and E + P (1.27 +/- 0.04 g/min), CHO(ox) was lower with E (1.05 +/- 0.02 g/min). Glucose R(d) tended to be lower with E and E + P relative to B. EMGU was 25% lower with E than with B or E + P. Plasma free fatty acids (FFA) were inversely related to EMGU (r(2) = 0.49). The data suggest that estrogen lowers CHO(ox) by reducing EMGU and glucose R(d). Progesterone increases EMGU but not glucose R(d). The opposing actions of E(2) and P(4) on EMGU may be mediated by their impact on FFA availability or vice versa.     

Sialic acid inhibits agrin signaling in C2 myotubes

Acetylcholine receptor (AChR) clustering is an early event in neuromuscular synapse formation that is commonly studied using muscle cell culture. Motor neuron-derived agrin induces the postsynaptic tyrosine phosphorylation of both a muscle-specific kinase (MuSK) and the AChR beta-subunit. These phosphorylation events are required for AChR clustering, suggesting an agrin-driven signaling pathway. Both the phosphorylation events and AChR clustering can also be induced by neuraminidase, an enzyme that cleaves sialic acid from glycoconjugates, suggesting that neuraminidase is able to activate the agrin signaling pathway. A postulated signal for postsynaptic differentiation at sites of nerve-muscle contact during vertebrate development is the enzymatic removal of basal lamina components. We show here that bath-applied sialic acid has an effect directly opposite that of agrin or neuraminidase. Sialic acid not only decreases AChR clustering but also diminishes the tyrosine phosphorylation of MuSK and the AChR beta-subunit signal-transduction events normally driven by agrin. However, sialic acid does not prevent agrin-binding molecules from colocalizing with the decreased number of AChR clusters that do form, suggesting that sialic acid is acting to inhibit the agrin signaling pathway downstream of agrin binding to the muscle cell membrane. We propose a regulatory role for sialic acid in the signal transduction events of neuromuscular synapse formation, in which agrin or neuraminidase can overcome this sialic acid repression, resulting in the clustering of AChRs and other postsynaptic molecules.     

Jun N‐terminal kinase activity is required for invagination but not differentiation of the sea urchin archenteron

Although sea urchin gastrulation is well described at the cellular level, our understanding of the molecular changes that trigger the coordinated cell movements involved is not complete. Jun N‐terminal kinase (JNK) is a component of the planar cell polarity pathway and is required for cell movements during embryonic development in several animal species. To study the role of JNK in sea urchin gastrulation, embryos were treated with JNK inhibitor SP600125 just prior to gastrulation. The inhibitor had a limited and specific effect, blocking invagination of the archenteron. Embryos treated with 2 μM SP600125 formed normal vegetal plates, but did not undergo invagination to form an archenteron. Other types of cell movements, specifically ingression of the skeletogenic mesenchyme, were not affected, although the development and pattern of the skeleton was abnormal in treated embryos. Pigment cells, derived from nonskeletogenic mesenchyme, were also present in SP600125‐treated embryos. Despite the lack of a visible archenteron in treated embryos, cells at the original vegetal plate expressed several molecular markers for endoderm differentiation. These results demonstrate that JNK activity is required for invagination of the archenteron but not its differentiation, indicating that in this case, morphogenesis and differentiation are under separate regulation. genesis 53:762–769, 2015. © 2015 Wiley Periodicals, Inc.     

Testosterone may increase selective attention to threat in young male macaques

Animal studies indicate that sex hormones have widespread effects on the brain, cognition and emotion, but findings in humans are inconsistent. Well-controlled studies in nonhuman primates are crucial to resolve these discrepancies. In this study, we examined the effects of testosterone (T) on emotion in male rhesus monkeys. Six young adult males were tested on two emotional tasks during three hormonal conditions in a crossover design: when intact at baseline and when pharmacologically hypogonadal with add-back of T or placebo. The emotional tasks were the Approach–Avoidance task, which tested behavioral responses to three categories of objects (familiar, novel, and negative) and a Social Playback task which tested behavioral responses to scenes of unfamiliar conspecifics engaged in three types of social activities (neutral, positive, or negative). Following a 4-week baseline period, monkeys were treated with Depot Lupron, 200 μg/kg before being randomly assigned to one of two treatment groups: Depot Lupron + Testosterone Enanthate (TE, 20 mg/kg) or Depot Lupron + oil vehicle. In each treatment group, monkeys received one injection of Lupron and one injection of TE or one injection of Lupron and one injection of oil at the onset of a 4-week testing period, before crossing over to the alternate treatment for an additional 4 weeks of testing. TE treatment had no effect on behavioral measures in the Approach–Avoidance task. For the Social Playback task, however, TE significantly increased watching time of video clips which depicted fights between unfamiliar conspecifics. The enhancing effect of T on watching time for negative social scenes is consistent with human data suggesting that T decreases aversion or facilitates approach to threatening social stimuli. Further studies are needed to understand the mechanisms by which T may mediate responsiveness to social threat in male primates.     

Lipoprotein geometry. II. Apoprotein exchange in human plasma high density lipoprotein.

The relationships between the apoproteins of intact human serum high density lipoprotein particles, HDL₂ and HDL₃, have been studied by observing the exchange of radioactively labeled apoproteins between one subclass and the other. This exchange process can be inhibited by chemically crosslinking the apoproteins of either the labeled or unlabeled subclass. These results are consistent with a dynamic relationship between HDL₂ and HDL₃ which appears dependent upon the association and perhaps the conformation of the apoprotein components of the lipoprotein particles.     

Starch as a sugar reservoir for nematode-induced syncytia

The plant parasitic nematode Heterodera schachtii invades the roots of Arabidopsis thaliana to induce nematode feeding structures in the central cylinder. During nematode development, the parasites feed exclusively from these structures. Thus, high sugar import and specific sugar processing of the affected plant cells is crucial for nematode development. In the present work, we found starch accumulation in nematode feeding structures and therefore studied the expression genes involved in the starch metabolic pathway. The importance of starch synthesis was further shown using the Atss1 mutant line. As it is rather surprising to find starch accumulation in cells characterised by a high nutrient loss, we speculate that starch serves as long- and short-term carbohydrate storage to compensate the staggering feeding behaviour of the parasites.Key words: Heterodera schachtii, Arabidopsis, nematode, starch metabolism, syncytiaThe obligate plant parasitic nematode Heterodera schachtii is entirely dependent on a system of nutrient supply provided by the plant. Host plants—among those the model plant Arabidopsis thaliana—have to endure invasion of second stage juveniles and the establishment of nematode feeding structures in the plant''s vascular cylinder. For induction of the specific feeding structures, the juveniles pierce one single plant cell with their stylet and inject secretions, thus triggering the formation of a syncytium by local cell walls dissolutions.¹ Further, the central vacuole of the syncytial cells disintegrates, nuclei enlarge and many organelles proliferate.¹ About 24 hours after feeding site induction, the nematode juveniles start feeding in repetitive cycles.² Syncytia have previously been described as strong sinks in the plant''s transport system.³ Thus, in the recent years several studies were carried out to discover solute supply to syncytial cells.^4–7 To our present knowledge, syncytia are symplasmically isolated in the first days of nematode development. During that period, the nematodes depend on transport protein activity in the syncytia plasmamembranes. At later stages plasmodesmata appear to open to the phloem elements, facilitating symplasmic transport.Incoming solutes may either be taken up by the feeding nematode or are synthesised and catalysed by the syncytium''s metabolism. Due to the microscopically observable high density of the cytosol¹ and the increased osmotic pressure,⁸ syncytia appear to accumulate high solute concentrations. In fact, significantly increased sucrose levels have been found in syncytia in comparison to non-infected control roots.⁷ In case of high sugar levels, plant cells generally synthesize starch in order to reduce emerging osmotic stress.⁹ The aim of the work of Hofmann et al.,¹⁰ was to elucidate if starch is utilised as carbohydrate storage in nematode-induced syncytia and to study expression of genes involved in starch metabolism with an emphasis on nematode development.Starch levels of nematode induced syncytia and roots of non-infected plants grown on sand/soil culture were measured by high performance liquid chromatography (HPLC). The results showed a high accumulation of starch in syncytia that was steadily decreasing during nematode development. The accumulation of starch could further be localised within syncytial cells by electron microscopy. Based on these results, we studied the gene expression of the starch metabolic pathway by Affymetrix gene chip analysis. About half of the 56 involved genes were significantly upregulated in syncytia compared to the control and only two genes were significantly downregulated. Thus, the high induction of the gene expression is consistent with the high starch accumulation. Finally, we applied an Arabidopsis mutant line lacking starch synthase I expression that has been described previously.¹¹ Starch synthase I was the second highest upregulated gene in syncytia. It catalyses the linkage of ADP-glucose to the non-reducing end of an a-glucan, forming the linear glucose chains of amylopectin. In a nematode infection assay we were able to prove the significant importance of the gene for nematode development.With the presented results, we can unambiguously prove the accumulation of starch and the induction of the gene expression of the starch metabolic pathway in nematode-induced syncytia. The primary question however is: why do syncytia accumulate soluble sugars and starch although their metabolism is highly induced and nematodes withdraw solutes during continuously repeating feeding cycles?One explanation may be found where least expected—in nematode feeding. It is the feeding activity that induced solute import mechanisms into syncytia resulting in a newly formed sink tissue. However, during moulting events to the third, the fourth juvenile stage and to the adult stage nematodes interrupt feeding for about 20 hours.² During this period sugar supply mechanisms will most probably not be altered thus leading to increasing levels of sugars in the syncytium. Starch may serve as short-term carbohydrate buffering sugar excess. Further, starch may serve as long-term carbohydrate storage during nematode development. In the early stages of juvenile development nematodes withdraw considerably small quantities (about 0,8-times the syncytium volume a day).¹² At later stages, nutrient demand increases so that adult fertilised females require 4-times the syncytium volume per day in order to accomplish egg production.¹² Thus, excessive sugar supply in the first days may be accumulated as starch that gets degraded at later stages when more energy is required from the parasites. Consequently, starch reserve serves as both short-term and long-term carbohydrate storage in nematode-induced syncytia in order to buffer changing feeding pattern of the parasites.? Open in a separate windowFigure 1Arabidopsis wild-type Columbia-0 plants were grown in sand/soil culture. Nematode-induced syncytia and non-infected control roots were harvested at 10, 15 and 20 days after inoculation (dai) and starch content was measured as glucose (Glc) equivalents. Values are means ± SE, n = 3. Different letters indicate significant variations (p < 0.05). © ASPBOpen in a separate windowFigure 2Transmission electron microscope picture of a cross-section of a syncytium associated with female fourth stage juvenile (H. schachtii) induced in roots of Arabidopsis. Bar = 2 µm. S, syncytium; Se, sieve tube; arrow, plastid; asterisk, starch granule. © ASPB     

Immunoglobulin G galactosylation and sialylation are associated with pregnancy-induced improvement of rheumatoid arthritis and the postpartum flare: results from a large prospective cohort study

Introduction  

Improvement of rheumatoid arthritis (RA) during pregnancy has been causatively associated with increased galactosylation of immunoglobulin G (IgG) N-glycans. Since previous studies were small, did not include the postpartum flare and did not study sialylation, these issues were addressed in the present study.