Is Sugar Bad For You? Not For Plants And Trees, Study Shows

A new study reveals the role of sugars as initial regulator of apical dominance

Everyone loves to decorate their Christmas tree. Have you noted its particular growth pattern? It is broad at the bottom while narrower at the tip which is at the top. This peculiar growth pattern of certain plants is due to a phenomenon known as Apical dominance. Apical dominance can in simpler words be understood by growth of tips towards sunlight. For almost a century, we believed that the main factor responsible for apical dominance was the plant hormone, Auxin.  But, according to new report published in the Journal PNAS, scientists claim that apical dominance is correlated with sugar availability to the plant and not apical supply of Auxin. They showed that apical dominance was controlled by the intensive demand of sugar by growing terminal tips which indirectly also limits their supply towards lateral or axillary buds. Therefore, this helps several trees to survive by out-competing others in dense forests in their race to sunlight, a vital component for photosynthesis.

Apical dominance is maintained by limiting the distribution of sugars to axillary buds, thereby making most of the sugar available to terminal growing tips. Garden pea plants of more than 150 cm in height were selected for the decapitations experiments. The approximate distance of shoot tip with the second node of plant was approximately 20 cm, a relatively far distance. Auxin content and axillary bud growth was investigated in intact and decapitated plants. It was found that when the shoot tip was cut or decapitation was done, there was strong correlation with the rapid bud outgrowth in the plant. Scientists used digital-time photography to observe bud growth in buds 40 cm below the shoot tip within 2.5 hour of decapitation. It was observed that sugars rapidly accumulate in axillary buds after the loss of shoot tip and the buds are released. Stem girdling experiments also proved that any shoot-tip derived inhibitor (Auxin in this case) was not the only responsible factor for bud release.

Examination of sugar content of axillary buds by mass spectrometry revealed that total sucrose (sugar) level was increased by 44% within 4 hours of decapitation. This study leads to an understanding which rules out Auxin as the sole and master regulator of apical dominance in plants. Rather, it gives an edge to sugars for being necessary as well as sufficient factor for axillary bud release from apical dominance.

Reference: 
Mason MG, Ross JJ, Babst BA, Wienclaw BN, & Beveridge CA (2014). Sugar demand, not auxin, is the initial regulator of apical dominance. Proceedings of the National Academy of Sciences of the United States of America PMID: 24711430

Just A Blood Test Is Enough to Detect Dementia

New effective method to detect future Alzheimer’s patients.

In a recent research published online in the journal Nature Medicine, scientists claim to have developed a technique by which they can forecast if a person is capable of developing dementia in two to three years. This will be very useful to mankind since dementia affects over 35 million people worldwide and is expected to affect 150 million by 2050. Dementia is a neurodegenerative disorder which leads to loss of important structures and functions in the brain. It is not a single disease but a non-specific syndrome which worsens with time. The Alzheimer’s disease is the most common form of dementia and is incurable.

The study comprised of a simple blood test from 525 healthy individuals all aged above seventy. Their blood samples were taken once every year for at least five years. About 74 individuals developed Alzheimer’s disease, enabling scientists to compare blood lipid profiles of 53 individuals who developed mild symptoms of the disease to those that were absolutely healthy.

Upon matching they found there are certain lipids that were strongly linked with Alzheimer disease appearance. More specifically, about ten molecules or biomarkers were identified as potential candidates that were responsible for breaking down the neural cell membranes and thereby leading to the development of Alzheimer’s symptoms. The presence of these ten biomarkers could predict with 90% accuracy that people having these compounds in their blood are likely to get affected with mild cognitive impairment (MCI) or Alzheimer’s disease (AD) in the near future.

The Alzheimer’s disease has no fool proof cure so far and the condition worsens as it progresses, eventually leading to death. Several therapies have been tested in clinical trials in the past few years but none have been successful. This may be because the patients that are brought for trial have already acquired the disease. The need is to develop biomarkers that can identify at large scale the at-risks individuals. This study will help to design and develop a drug that might delay or prevent the onset of disease symptoms in those individuals that are at risk.

References:

Mapstone, M., Cheema, A., Fiandaca, M., Zhong, X., Mhyre, T., MacArthur, L., Hall, W., Fisher, S., Peterson, D., Haley, J., Nazar, M., Rich, S., Berlau, D., Peltz, C., Tan, M., Kawas, C., & Federoff, H. (2014). Plasma phospholipids identify antecedent memory impairment in older adults Nature Medicine DOI: 10.1038/nm.3466

Yogurt Is Good For Type 2 Diabetes

Higher consumption fermented dairy products reduces risk of type-2 diabetes by 28 percent.

The increasing prevalence of diabetes is a cause of concern worldwide. Many breakthroughs in understanding and preventing this chronic disease have taken place but none really significant or foolproof. Recent research published online in Diabetologia shows that higher consumption of yogurt reduces the chance of getting new-onset type-2 diabetes by almost 28 percent as compared to absolutely no consumption.

No one will doubt that dairy products are important sources of high-quality proteins, vitamins (A, D, B12, phylloquinones & menaquinones and riboflavin) and minerals (calcium, magnesium and potassium). However, dairy products are also a source of saturated fats, the intake of which is discouraged in current dietary guidelines. It is often recommended that saturated fat intake be replaced with unsaturated fat intake.

In this new study, researchers at the School of Medicine, University of Cambridge found that dairy product intake was associated with a lower risk of type 2 diabetes in three meta-analyses of large prospective epidemiological studies. About 25,000 men and women living in Norfolk, UK were examined. A daily record of all their food and drink consumption  over a week showed new-onset type-2 diabetes in 753 people over 11 years. The researchers not only examined the risk of diabetes in relation to consumption of total dairy products, but also distinguished between different dairy products.

Surprisingly, factors like high-fat dairy, total dairy, obesity, lifestyles and eating habits were not associated with diabetes risk, whereas higher consumption of low-fat fermented dairy products such as yoghurt, all yoghurt varieties and some low-fat cheeses did reduce the risk of type-2 diabetes. The researchers suggest as a mechanical explanation that fermented dairy products exert beneficial effects against diabetes through probiotic bacteria and a special form of vitamin K (part of the menaquinone family) associated with fermentation.

These findings suggest that the consumption of these specific dairy types are beneficial for the prevention of diabetes.

References:

O’Connor LM, Lentjes MA, Luben RN, Khaw KT, Wareham NJ, & Forouhi NG (2014). Dietary dairy product intake and incident type 2 diabetes: a prospective study using dietary data from a 7-day food diary. Diabetologia PMID: 24510203

Why Mosquitoes Bite Specific People

Mosquitoes are attracted to carbon-dioxide and body odors.

Are you the one that always seems to be the sweet target of mosquito terror? Do you wake up from a night out camping to find your ankles and wrists completely covered with mosquito bites, while your tent mates are untouched? In the peak of mosquito season, some outdoor venturers are lucky, while others get relentlessly assaulted by these bloodsucking creatures. Have you ever wondered why? Scientists at the University of California (Riverside) have identified that mosquitoes are attracted to people that exhale more carbon-dioxide and release skin odors.

Olfactory receptor neurons

Mosquitoes transmit deadly diseases such as malaria and dengue. It is therefore important to find the reason for their selective attractiveness towards some people. Earlier studies found that female mosquitoes detect exhaled CO2 using a class of olfactory receptor neurons (ORNs) known as cpA.  These cpA neurons are located in maxillary palps (sensory organs) and express the CO2 receptors. The identity of olfactory receptor neurons required for attraction to skin odor remained a mystery, until now.  The recent report links both CO2 as skin odor detection to the same receptor neurons.

Foot odor

Researchers developed a novel chemical based strategy to selectively stop the activity of cpA in dengue spreading mosquito (Aedes aegypti) to check the levels of skin odor responses. The role of this neuron was checked to see the mosquito’s behavior on human foot odor which was found to be substantially reduced.

This new information leads to possibilities for practical solutions to prevent mosquito bites. About 0.5 million compounds were screened to identify several CO2 receptor ligands, including an antagonist, ethyl pyruvate, that reduces attraction to skin and an agonist, cyclopentanone, that lures mosquitoes to traps as effectively as CO2. Several of these compounds were safe, pleasant-smelling and affordable enough to use in new generation of mosquito control strategies worldwide.

New strategies

Current findings have wide-reaching implications for control of mosquito-borne disease. Present mosquito control strategies use CO2 traps, but they are costly, as generation of CO2 requires energy input. The new alternatives are affordable to use in surveillance and control traps in countries affected most by mosquito-borne diseases. These approaches will protect large areas and might present an economical and environmentally friendly way to control deadly mosquitoes.

Reference:

Tauxe GM, Macwilliam D, Boyle SM, Guda T, & Ray A (2013). Targeting a Dual Detector of Skin and CO2 to Modify Mosquito Host Seeking. Cell, 155 (6), 1365-79 PMID: 24315103