High-fat diets rich in soy or fish oil distinctly alter hypothalamic insulin signaling in rats

Hypothalamic insulin inhibits food intake, preventing obesity. High-fat feeding with polyunsaturated fats may be obesogenic, but their effect on insulin action has not been elucidated. The present study evaluated insulin hypophagia and hypothalamic signaling after central injection in rats fed either control diet (15% energy from fat) or high-fat diets (50% energy from fat) enriched with either soy or fish oil. Soy rats had increased fat pad weight and serum leptin with normal body weight, serum lipid profile and peripheral insulin sensitivity. Fish rats had decreased body and fat pad weight, low leptin and corticosterone levels, and improved serum lipid profile. A 20-mU dose of intracerebroventricular (ICV) insulin inhibited food intake in control and fish groups, but failed to do so in the soy group. Hypothalamic protein levels of IR, IRS-1, IRS-2, Akt, mTOR, p70S6K and AMPK were similar among groups. ICV insulin stimulated IR tyrosine phosphorylation in control (68%), soy (36%) and fish (34%) groups. Tyrosine phosphorylation of the pp185 band was significantly stimulated in control (78%) and soy (53%) rats, but not in fish rats. IRS-1 phosphorylation was stimulated only in control rats (94%). Akt serine phosphorylation was significantly stimulated only in control (90%) and fish (78%) rats. The results showed that, rather than the energy density, the fat type was a relevant aspect of high-fat feeding, since blockade of hypothalamic insulin signal transmission and insulin hypophagia was promoted only by the high-fat soy diet, while they were preserved in the rats fed with the high-fat fish diet.     

Temporal fatty acid dynamics of the octocoral Veretillum cynomorium

The objectives of the present work were to investigate the temporal variation in the fatty acid (FA) composition of the octocoral Veretillum cynomorium, examine the effects of reproduction and environmental factors on FA variation, and establish a chemotaxonomic identification for this species. Mean oocyte size-frequency distributions showed that the majority of the oocytes had an intermediate size (Group II) before spawning (April and June). The late-vitellogenic oocytes (Group III) became absent in August and October and, during this post-spawning period, oocytes were primarily of small size (Group I). Most of the major FA, 16:0, 18:0, 20:4n-6, 20:5n-3, and the tetracosapolyenoic fatty acid (TPA), 24:6n-3, varied significantly throughout the year (p < 0.01), with two peaks in August/October and February. The boost in early oogenesis, also associated with warmer temperatures, seemed to be responsible for the observed increase in FA content between June and August. The highest values of FA content were observed in February when intermediate oogenesis (Group II) was at its peak and there were considerable levels of available food in the environment. Also, the increase in food availability seemed to trigger the final stages of gametogenesis. The high quantity of 18:1n-7, odd-numbered and branched FAs, suggested the presence of a dynamic bacterial community in V. cynomorium, probably as an adaptive response to the lack of symbiotic microalgae. Although the presence of TPAs is the main feature distinguishing octocorals from other coral species, here we showed that there was no single FA clearly dominating the FA composition of V. cynomorium throughout the year. Instead, four main FAs share similar concentrations: 16:0, 20:4n-6, 20:5n-3 and 24:6n-3. The predominance of these four FAs combined with the higher amount of 24:6n-3 when compared to 24:5n-6 may serve as a chemotaxonomic feature to distinguish this octocoral species (or genus).     

Purinergic system ecto-enzymes participate in the thromboregulation of patients with indeterminate form of Chagas disease

Chagas disease (CD) is a chronic and endemic illness caused by the parasite Trypanosoma cruzi. Microvascular disturbances play an important role in the progress of the disease. The purinergic signaling system participates in regulatory functions, such as immunomodulation, neuroprotection, and thromboregulation. This study aimed to investigate the activities of purinergic system ecto-enzymes present on the platelet surface and the platelet aggregation profile from patients with indeterminate form of Chagas disease (IFCD). Thirty patients diagnosed with IFCD and 30 healthy subjects were selected. Ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP), ecto-5′-nucleotidase (E-5′-NT) and ecto-adenosine deaminase (E-ADA) activities were measured in platelets isolated from these individuals as well as the platelet aggregation. Results demonstrated an increase of 21 % in the E-NPP activity and 30 % in the E-5′-NT activity in IFCD group (P < 0.05); however, a decrease of 34 % in the E-ADA activity was determined in the same group (P < 0.001). A significant decrease of 12.7 % and 12.8 % in the platelet aggregation of IFCD group in two different concentrations of ADP (5 and 10 μM) was observed, respectively (P < 0.05). Increased E-NPP and E-5-NT activities as well as decreased E-ADA activity in platelets of patients with IFCD contributed to decrease platelet aggregation, suggesting that the purinergic system is involved in the thromboregulation process in these patients, since adenosine (the final product of ATP hydrolysis) has cardioprotective and vasodilator effects that prevent the clinical progress of the disease.     

Distinct localization of T cell Agrin during antigen presentation--evidence for the expression of Agrin receptor(s) in antigen-presenting cells

Agrin is over-expressed by activated and autoimmune T cells, and synergizes with the T cell receptor (TCR) to augment cell activation. In the present study, we show that Agrin accumulates to distinct areas of the plasma membrane and that cell activation causes its redistribution. During antigen presentation, Agrin primarily accumulates to the periphery of the mature immunological synapse, mostly in lamellipodia-like protrusions that wrap around the antigen-presenting cell and, conversely, anti-Agrin sera induced a significant redistribution of TCR at the plasma membrane. We also provide evidence for the expression of Agrin receptors in peripheral blood monocytes, dendritic cells and a fraction of B cells. Interestingly, interferon-α treatment, which induces the expression of Agrin in T cells, also augmented Agrin binding to monocytes. Stimulation of monocytes with recombinant Agrin induced the clustering of surface receptors, including major histocompatibility complex class II, activation of intracellular signalling cascades, as well as enhanced dsRNA-induced expression of pro-inflammatory cytokines interleukin-6 and tumour necrosis factor-α. Collectively, these results confirm the location of Agrin at the immunological synapse between T cells and antigen-presenting cells and justify further characterization of its receptors in the immune system.     

Cyclooxygenase-2 induction by adiponectin is regulated by a sphingosine kinase-1 dependent mechanism in cardiac myocytes

The adipose-derived plasma protein, adiponectin (APN), has various protective effects on cardiovascular diseases. In this study, we show that endogenous APN is required for full cyclooxygenase-2 (COX-2) induction by ischemia-reperfusion injury in the heart in vivo. In rat neonatal cardiac myocytes, APN-induced COX-2 expression was reduced by treatment with a sphingosine kinase-1 (SphK-1) inhibitor or siRNA targeting SphK-1. Treatment with a sphingosine-1-phosphate (S1P) receptor antagonist also diminished COX-2 expression in response to APN stimulation. These findings suggest that APN is a physiological regulator of COX-2 signaling in the heart and that this regulation occurs in part via a SphK-1-S1P receptor dependent mechanism in cardiac myocytes.     

Glutamine Synthetase Activity, Relative Water Content and Water Potential in Maize Submitted to Drought

Primer screening and optimization for random amplified polymorphic DNA (RAPD) analysis of cashew (Anacardium occidentale L.) was investigated. Among four series (A, B, D and N) of 10-mer primers, A-series performed better amplification of fragments than other series. The maximum amplification fragments was obtained using OPA-02, OPA-03, OPA-09, OPB-06, OPB-10, OPD-03, OPD-05 and OPN-03 primers. The primers OPA-02 and OPN-03 produced maximum number of DNA fragments in Anacardium occidentale cv. H-320. Primers (OPB-08 and OPN-05 performed a least number of amplification fragments. RAPD profile also indicate that some primer did not produce good amplification. The primer OPA-02 amplified 12 number of polymorphic bands in 20 cultivars of cashew. Only one DNA fragment was produced in A. occidentale cv. Vridhachalam - 2 (M-44/3) by using the primer OPA-02. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dinitrogen fixation and infection of grass leaves byPseudomonas rubrisubalbicans andHerbaspirillum seropedicae

Bacteria causing mottled stripe disease in sugar cane, known asPseudomonas rubrisubalbicans, were shown to be able to fix molecular N₂ and to grow on it. The root associated diazotroph known asHerbaspirillum seropedicae, after artificial inoculation caused mottled stripe disease symptoms on sorghum and Napier grass but not on sugar cane. Both bacteria could be reisolated from leaves even 60 days after. Sugar cane leaves contained large numbers of these bacteria even in the uninoculated controls. Additional physiological characteristics of six strains ofP. rubrisubalbicans were compared with those of twoH. seropedicae strains and were shown to be very similar.     

Recurrent Circuitry for Balancing Sleep Need and Sleep

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Territory size as a main driver of male-mating success in an Amazonian nurse frog (<Emphasis Type="Italic">Allobates paleovarzensis</Emphasis>, Dendrobatoidea)

In polygamous mating systems, it is most often males that compete for the opposite sex, using strategies to provide access to as many females as possible. Females, on the other hand, constitute the sex that exerts the choice and so require a means of accessing the quality of a potential partner in comparison to its competitors. A common challenge in sexual selection studies is to identify the most relevant trait for mating success, since many are correlated with each other. In addition, little is known about how the female accesses the aspects related to male quality. In this context, we tested the role of different male characteristics on mating success in a natural environment using the Amazonian frog Allobates paleovarzensis as a model. A multiple linear regression model showed a positive relationship between territory size and number of male matings, while calling persistence was slightly related to the mating success. We did not detect a relation of the number of matings with the distance to the nearest body of water nor with male body size. Additionally, we observed that territory size was not related to calling persistence, but had a positive relation with the duration of the couple’s courting process. Thus, we conclude that: (1) territory size is the main determinant of male-mating success, and this is not correlated with the other attributes tested; and (2) females access the size of the males’ territory through the courting process that precedes oviposition.