Breaking News
April 23, 2018 - CDC seeking $400 million to replace lab for deadliest germs
April 23, 2018 - Sensirion to present single-use liquid flow sensor at COMPAMED 2017
April 23, 2018 - FDA approves contact lenses that shade the sun
April 22, 2018 - Concussion recovery and symptom severity found to vary between men and women
April 22, 2018 - C. Difficile Risk Higher With Stoma Reversal Versus Colectomy
April 22, 2018 - Repeated ranibizumab doesn’t impair macular perfusion
April 22, 2018 - New microscope reveals how cells behave in 3D and real time inside living organisms
April 22, 2018 - Study shows clinical benefit and monetary gains of weight-loss surgery
April 22, 2018 - GNA Biosolutions launches world’s first Laser PCR platform at Medica Trade Fair
April 22, 2018 - Researchers present simulation model to investigate hospital responsiveness to mass casualty incidents
April 22, 2018 - Does Pot Really Dull a Teen’s Brain?
April 22, 2018 - Controversial pregnancy test drug shows deformities in zebrafish embryos within hours of exposure
April 22, 2018 - New research partnership makes childbirth safer in Mozambique
April 22, 2018 - Brief bedside visual art intervention reduces pain, anxiety in cancer patients
April 22, 2018 - The memory part of the brain may also hold clues for anxiety and depression
April 22, 2018 - AYOXXA to develop multiplex immunoassay to support treatment of sepsis patients
April 22, 2018 - New Drug Combo Ups Survival in HER2/neu Uterine Serous Cancer
April 22, 2018 - Researchers chart a new way to look at concussion
April 22, 2018 - Every parent needs to know fundamental red flags for autism
April 22, 2018 - Anatotemp expands anatomic dental implant healing abutments with 4Side anti-rotational connection
April 22, 2018 - Gene Twist Can Make Your Blood Pressure Spike From Salt
April 22, 2018 - Study suggests failed osteoarthritis drug could help treat opioid addiction
April 22, 2018 - More Americans aware of growing problem of opioid addiction
April 22, 2018 - KHN’s ‘What the Health?’ Nothing in health care ever goes away
April 22, 2018 - BGS to promote high-quality sterilization services at Health GB in Manchester
April 22, 2018 - New integrated POC tool detects biomarkers of heart failure rapidly and precisely
April 22, 2018 - Direct electrical current can be delivered to nerves for blocking pain signals
April 22, 2018 - Newly Published Phase 2 Study Found Esketamine Demonstrated Significantly Rapid Improvements in Depressive Symptoms and Suicidality
April 22, 2018 - Healthy red blood cells owe their shape to muscle-like structures
April 22, 2018 - Researchers present case study of management of rheumatic mitral regurgitation in woman contemplating pregnancy
April 22, 2018 - New black Porvair Krystal UV Quartz microplates for Circular Dichroism measurements
April 22, 2018 - Advanced flow chemistry modules enhance control of nanoprecipitation
April 22, 2018 - Look! Down in the petri dish! It’s a superplatelet!
April 22, 2018 - Research reveals why people with tetraplegia more likely to suffer from sleep apnea
April 21, 2018 - New non-invasive nerve stimulation may offer relief for people with hand tremor
April 21, 2018 - Smartphone App May Up Medication Adherence in HTN
April 21, 2018 - Western diet depletes artery-protecting immune cells
April 21, 2018 - Excelitas Technologies launches new powerful LED light source for fluorescence microscopy
April 21, 2018 - Academia and high tech companies join forces to increase production capacity for microfluidic systems
April 21, 2018 - Developing cooking skills as young adult may have long-term health benefits
April 21, 2018 - Study compares survival outcomes of different drugs for type 2 diabetes
April 21, 2018 - More Than 40 Percent of Americans Breathe Dirty Air: Report
April 21, 2018 - Obstructive sleep apnea – Genetics Home Reference
April 21, 2018 - More evidence shows exposure to traffic and outdoor air pollution increases risk of asthma
April 21, 2018 - Novel gold nanoparticle technology could guide cancer treatment in real-time
April 21, 2018 - News coverage of Ebola impacted public’s perception on disease and survivors
April 21, 2018 - S.Africa’s DIY battle against HIV
April 21, 2018 - Children with autism have gastrointestinal and immune system deregulation, research finds
April 21, 2018 - Human brain processes sight and sound in the same way, shows study
April 21, 2018 - Evolutionary history of tumor helps predict severity of prostate cancer
April 21, 2018 - Pepper plant metabolizes antibiotic in personal care products
April 21, 2018 - Tradeshow Talks with Integra
April 21, 2018 - EPFL becomes part of Chan Zuckerberg’s project to develop Human Cell Atlas
April 21, 2018 - Pfizer Announces Positive Topline Results From Phase 3 ATTR-ACT Study Of Tafamidis In Patients With Transthyretin Cardiomyopathy
April 21, 2018 - Breaking through the HIV vaccine ‘logjam’
April 21, 2018 - IntelliCyt introduces new QSol buffer to enable robust, consistent sampling
April 21, 2018 - Scientists publish comprehensive lineage tree of whole adult animal in Science journal
April 21, 2018 - Innovative method based on FluidFM technology could revolutionize biological research
April 21, 2018 - Americans world’s biggest TV addicts, watching four hours a day
April 21, 2018 - Investigational drug may help increase protein levels in babies with spinal muscular atrophy
April 21, 2018 - Study shows distinctions between age groups in predicting and responding to stress at home
April 21, 2018 - Aziyo Biologics, BIOTRONIK enter into US co-distribution agreement
April 21, 2018 - Opiate Use Linked to Early Mortality in IBD Patients
April 21, 2018 - Online ads help pregnant smokers quit
April 21, 2018 - Opioid pain medications may not be safe for hemodialysis patients
April 21, 2018 - Rare variants in non-coding DNA inherited from parents heighten autism risk
April 21, 2018 - A needleless glucose monitor for diabetes patients
April 21, 2018 - BD introduces new informatics and automation solutions for clinical laboratories
April 21, 2018 - Turn Chores Into a Fitness Routine
April 21, 2018 - DNA methylation plays key role in stem cell differentiation
April 21, 2018 - Scientists find link between soil metals and cancer mortality
April 21, 2018 - Experts discuss implications of low calcium intake in global population
April 21, 2018 - GNA Biosolutions to display Pharos V8 Laser PCR instrument at Analytica trade fair
April 21, 2018 - People with vitamin D deficiency may be at greater risk of diabetes
April 21, 2018 - Study findings could open new possibilities for treating cancer with adenovirus
April 21, 2018 - People who use medical marijuana have higher rates of prescription drug use, study finds
April 21, 2018 - Study debunks ‘myth’ that strenuous exercise dampens immunity
April 21, 2018 - FDA approves marijuana based medication for epilepsy treatment
April 21, 2018 - Researchers find novel genes for longevity in mammals
April 21, 2018 - GNA Biosolutions and project partners launch new research project to develop TB diagnostic platform for POC applications
Tadpole metamorphosis found to be controlled by fat-sensing hormone

Tadpole metamorphosis found to be controlled by fat-sensing hormone

image_pdfDownload PDFimage_print

When tadpoles are but tadpoles, they’re voracious eaters, chomping down all of the plant matter in their paths.

Now, a University of Michigan study has shown that this voraciousness is because the hormonal and neural brakes to their eating are absent at this stage of development.

“One of the findings from our work is that during the tadpole stage, before they initiate metamorphosis, they don’t have any of these homeostatic negative controls of food intake: they have their feeding controls stuck in the ‘on’ position,” said lead author Robert Denver. “This allows the tadpoles to reach, as quickly as possible, a minimum body size for metamorphosis. If you watch some species of tadpole while they’re eating, they look like tiny piranhas.”

But just as they prepare to vault into frogdom, leptin, a hormone produced by fat that signals energy stores to the brain and suppresses the feeling of hunger, spikes in the tadpoles. This spike in leptin may signal to the brain that the tadpoles have enough energy stores to go through the exhausting process of metamorphosis.

The spike in leptin just before the beginning of metamorphosis helps regions in the brain that control hormone production and food intake mature. As the animal progresses through metamorphosis, its brain develops the ability to respond to leptin by shutting off feeding. This action of leptin is important for the tadpoles because they need to pause their eating at the climax of metamorphosis so that their bodies can overhaul their guts.

The guts are remodeled from a meters-long system that digests a vegetarian diet to a much shorter gut that digests only animal matter. This timing is a tricky balance to get right, says Denver, professor and chair of the U-M Department of Molecular, Cellular and Developmental Biology.

“Most research supports that tadpoles will capitalize on growth conditions because the bigger you are, the less likely you’ll get picked off by predators, and you’ll be a more effective predator once you become a frog,” he said. “On the other hand, if the larval habitat is not favorable–if there are a lot of predators, or if it’s going to dry out–tadpoles will initiate metamorphosis early.”

To test whether it was leptin that shut off feeding in the tadpoles’ brains, Denver and his team injected one group of tadpoles with a saline control. They gave another group of tadpoles a leptin injection. The tadpoles injected with saline continued to eat, but the tadpoles with the leptin injection stopped completely. This occurred in tadpoles that were going through metamorphosis, but not in younger tadpoles.

The researchers also demonstrated that leptin controls the suppression of feeding at metamorphic climax when the gut remodels to support a carnivorous diet. They did this by blocking the leptin signal in the tadpoles’ brains, which caused the tadpoles to resume feeding.

Denver says there are interesting parallels between this process in amphibians and the same process in mammals. Neonatal rats similarly feed (suckle) voraciously until leptin kicks in, at which point they develop negative homeostatic controls so that they don’t overeat. This allows the hypothalamus, a brain region that controls feeding, to mature and prepare the rat to eat solid food.

“What’s happening in the amphibian tadpole is a very ancient process–it’s a developmental, hormonal process that controls the timing of the development of the neural feeding circuitry, which also influences life history transitions,” Denver said. “In a tadpole, compared to mammals, the morphological change is much more dramatic.”

Tagged with:

About author

Related Articles