A Drosophila model targets Eiger/TNFα to alleviate obesity-related insulin resistance and macrophage infiltration

Obesity is associated with various metabolic disorders, such as insulin resistance and adipose tissue inflammation (ATM), characterized by macrophage infiltration into adipose cells. This study presents a new Drosophila model to investigate the mechanisms underlying these obesity-related pathologies. We employed genetic manipulation to reduce ecdysone levels to prolong the larval stage. These animals are hyperphagic and exhibit features resembling obesity in mammals, including increased lipid storage, adipocyte hypertrophy and high circulating glucose levels. Moreover, we observed significant infiltration of immune cells (hemocytes) into the fat bodies, accompanied by insulin resistance. We found that attenuation of Eiger/TNFα signaling reduced ATM and improved insulin sensitivity. Furthermore, using metformin and the antioxidants anthocyanins, we ameliorated both phenotypes. Our data highlight evolutionarily conserved mechanisms allowing the development of Drosophila models for discovering therapeutic pathways in adipose tissue immune cell infiltration and insulin resistance. Our model can also provide a platform to perform genetic screens or test the efficacy of therapeutic interventions for diseases such as obesity, type 2 diabetes and non-alcoholic fatty liver disease.

Reduction of nucleolar NOC1 leads to the accumulation of pre-rRNAs and induces Xrp1, affecting growth and resulting in cell competition

NOC1 is a nucleolar protein necessary in yeast for both transport and maturation of ribosomal subunits. Here, we show that Drosophila NOC1 (annotated CG7839) is necessary for rRNAs maturation and for a correct animal development. Its ubiquitous downregulation results in a dramatic decrease in polysome level and of protein synthesis. NOC1 expression in multiple organs, such as the prothoracic gland and the fat body, is necessary for their proper functioning. Reduction of NOC1 in epithelial cells from the imaginal discs results in clones that die by apoptosis, an event that is partially rescued in a Minute/+ background, suggesting that reduction of NOC1 induces the cells to become less fit and to acquire a 'loser' state. NOC1 downregulation activates the pro-apoptotic Eiger-JNK pathway and leads to an increase of Xrp1, which results in the upregulation of DILP8, a member of the insulin/relaxin-like family known to coordinate organ growth with animal development. Our data underline NOC1 as an essential gene in ribosome biogenesis and highlight its novel functions in the control of growth and cell competition.

An Enhanced Model of Middle Cerebral Artery Occlusion in Nonhuman Primates Using an Endovascular Trapping Technique

BACKGROUND AND PURPOSE

Current nonhuman primate stroke models are limited by either stroke variability or survivability. A new nonhuman primate stroke model was developed by using endovascular trapping techniques to limit collateral vessels with serial MR imaging and neurologic assessments.

MATERIALS AND METHODS

Eight adult rhesus monkeys (female, 7-13 years of age) underwent MR imaging and Spetzler neurologic assessment followed by endovascular stroke induction consisting of superselective endovascular placement of surgical silk sutures into the right MCA by using a trapping technique. Two initial subjects were euthanized immediately following postocclusion MR imaging. The subsequent 6 subjects recovered and underwent follow-up MR imaging and Spetzler neurologic assessments at 48 hours, with 4 being followed to 96 hours. Stroke infarct volumes were measured, and the longitudinal Spetzler clinical neurologic scores were assessed. The brain tissues were harvested and prepared with hematoxylin-eosin staining.

RESULTS

Focal permanent cerebral ischemia was induced in the targeted right MCA territory in all subjects. The volumes of the ischemic lesions at 6, 48, and 96 hours were 3.18 ± 1.007 mL (standard error of the mean) (n = 8), 6.70 ± 1.666 mL (standard error of the mean) (n = 6), and 7.23 ± 1.371 mL (standard error of the mean) (n = 4). For the survival animals, the immediate postsurgical Spetzler grading score improved from 60.7 at 24 hours to 68.7 at 48 hours.

CONCLUSIONS

We report a trapping modification to an established endovascular suture stroke model that yielded reproducible ischemia and clinically quantifiable neurologic deficits with no strokes in nontarget areas. This technique may be useful in evaluating translational stroke and penumbral imaging research in addition to preclinical testing of neuroprotective therapies.

dMyc expression in the fat body affects DILP2 release and increases the expression of the fat desaturase Desat1 resulting in organismal growth

Drosophila dMyc (dMyc) is known for its role in cell-autonomous regulation of growth. Here we address its role in the fat body (FB), a metabolic tissue that functions as a sensor of circulating nutrients to control the release of Drosophila Insulin-like peptides (Dilps) from the brain influencing growth and development. Our results show that expression of dMyc in the FB affects development and animal size. Expression of dMyc, but not of CycD/cdk4 or Rheb, in the FB diminishes the ability to retain Drosophila Insulin-like peptide-2 (DILP2) in the brain during starvation, suggesting that expression of dMyc mimics the signal that remotely controls the release of Dilps into the hemolymph. dMyc also affects glucose metabolism and increases the transcription of Glucose-transporter-1 mRNA, and of Hexokinase and Pyruvate-Kinase mRNAs, key regulators of glycolysis. These animals are able to counteract the increased levels of circulating trehalose induced by a high sugar diet leading to the conclusion that dMyc activity in the FB promotes glucose disposal. dMyc expression induces cell autonomous accumulation of triglycerides, which correlates with increased levels of Fatty Acid Synthase and Acetyl CoA Carboxylase mRNAs, enzymes responsible for lipid synthesis. We also found the expression of Stearoyl-CoA desaturase, Desat1 mRNA significantly higher in FB overexpressing dMyc. Desat1 is an enzyme that is necessary for monosaturation and production of fatty acids, and its reduction affects dMyc's ability to induce fat storage and resistance to animal survival. In conclusion, here we present novel evidences for dMyc function in the Drosophila FB in controlling systemic growth. We discovered that dMyc expression triggers cell autonomous mechanisms that control glucose and lipid metabolism to favor the storage of nutrients (lipids and sugars). In addition, the regulation of Desat1 controls the synthesis of triglycerides in FB and this may affect the humoral signal that controls DILP2 release in the brain.

A giant planet orbiting the ‘extreme horizontal branch’ star V 391 Pegasi

After the initial discoveries fifteen years ago, over 200 extrasolar planets have now been detected. Most of them orbit main-sequence stars similar to our Sun, although a few planets orbiting red giant stars have been recently found. When the hydrogen in their cores runs out, main-sequence stars undergo an expansion into red-giant stars. This expansion can modify the orbits of planets and can easily reach and engulf the inner planets. The same will happen to the planets of our Solar System in about five billion years and the fate of the Earth is matter of debate. Here we report the discovery of a planetary-mass body (Msini = 3.2M(Jupiter)) orbiting the star V 391 Pegasi at a distance of about 1.7 astronomical units (au), with a period of 3.2 years. This star is on the extreme horizontal branch of the Hertzsprung-Russell diagram, burning helium in its core and pulsating. The maximum radius of the red-giant precursor of V 391 Pegasi may have reached 0.7 au, while the orbital distance of the planet during the stellar main-sequence phase is estimated to be about 1 au. This detection of a planet orbiting a post-red-giant star demonstrates that planets with orbital distances of less than 2 au can survive the red-giant expansion of their parent stars.

Trace eyeblink classical conditioning in the monkey: a nonsurgical method and behavioral analysis

Classical eyeblink conditioning has been used extensively to study the neurobiology of associative learning and memory in rabbits and in humans. During the last several years, new developments have renewed interest in the possibility of studying classical conditioning in monkeys. Specifically, it is now known that impaired conditioning can be observed in humans with various neurologic problems, including amnesia, and thus there is now considerable interest in the neurobiology of human eyeblink conditioning. Research involving monkeys, in which discrete lesions of anatomically defined neural structures can be produced, has the potential to provide information that might not be readily available from work in humans. Here, the authors present a simple, nonsurgical method for classically conditioning the eyeblink response in monkeys and report behavioral results using a trace conditioning paradigm that is sensitive to hippocampal damage in both rabbits and humans. This method is reliable and effective for recording eyeblinks and shows that robust eyeblink classical conditioning can be readily established in the monkey.

Trace eyeblink classical conditioning in the monkey: a nonsurgical method and behavioral analysis

Classical eyeblink conditioning has been used extensively to study the neurobiology of associative learning and memory in rabbits and in humans. During the last several years, new developments have renewed interest in the possibility of studying classical conditioning in monkeys. Specifically, it is now known that impaired conditioning can be observed in humans with various neurologic problems, including amnesia, and thus there is now considerable interest in the neurobiology of human eyeblink conditioning. Research involving monkeys, in which discrete lesions of anatomically defined neural structures can be produced, has the potential to provide information that might not be readily available from work in humans. Here, the authors present a simple, nonsurgical method for classically conditioning the eyeblink response in monkeys and report behavioral results using a trace conditioning paradigm that is sensitive to hippocampal damage in both rabbits and humans. This method is reliable and effective for recording eyeblinks and shows that robust eyeblink classical conditioning can be readily established in the monkey.

fMRI of monkey visual cortex

While functional magnetic resonance imaging (fMRI) is now used widely for demonstrating neural activity-related signals associated with perceptual, motor, and cognitive processes in humans, to date this technique has not been developed for use with nonhuman primates. fMRI in monkeys offers a potentially valuable experimental approach for investigating brain function, which will complement and aid existing techniques such as electrophysiology and the behavioral analysis of the effects of brain lesions. There are, however, a number of significant technical challenges involved in using fMRI with monkeys. Here, we describe the procedures by which we have overcome these challenges to carry out successful fMRI experiments in an alert monkey, and we present the first evidence of activity-related fMRI signals from monkey cerebral cortex.