NEW FINDINGS — AGRICULTURE
Vineyard foe A tiny aphid-like insect called phylloxera is capable of single-handedly decimat- ing entire vineyards by feeding on, and ultimately killing, the grapevine roots and leaves. Phylloxera create tumor-like structures, called galls, in the grape vines which afford them a nutrient source as well as protection from other parasites. The galls disrupt the grapevine’s ability to move nutrients and feed itself.
Lab-based sugar substitute Sugary confections are a central feature of many holiday celebrations, family gatherings, and restaurant menus around the world. And while jellybeans, candy corn, pastries and pies might invoke a sweet sense of comfort and joy, excessive sugar consumption can lead to obesity, type 2 diabetes and heart disease. In order to feed their sweet tooth but also stay health conscious, many people use sugar substitutes in place of sugar. Stevia is a popular natural sweetener obtained from plants grown in South America that is 250 times sweeter than sugar. Scientists analyzed stevia to determine at a molecular level how it achieves this level of sweetness. They found that two molecules, Reb M and Reb D, gave stevia its sweetness without the bitter aftertaste associated with the most common molecule, Reb A. However, Reb M and Reb D are present in less than one percent of the stevia leaf, so extracting them from the plant is not feasible. Two companies discovered a process to create the calorie-free sweet- eners through fermentation. They developed a yeast strain that pro- duces the same enzymes used by the stevia plant. In a fermentation tank, the yeast converts simple sugars, like sucrose or dextrose, into Reb M and Reb D. The sweetener is being tested in over 300 products with some expected to hit shelves this year. REFERENCE: Winnipeg Free Press. Cargill starts making next-generation sweetener for 2020 debut. 16 November 2019. Web. 4 September 2020. https://www.winnipegfreepress.com/business/cargill-starts-making-next-genera- tion-sweetener-for-2020-debut-565030932.html. Dairy-identical cheese For those following an exclusively plant-based diet, trying to create a crispy yet gooey grilled cheese sandwich using vegan cheese has historically been a challenge. Dairy-free, plant- based cheeses had a reputation for having a weird, plasticky texture and lacking a true cheese flavor. As veganism and the animal-free food movement continue to gain momentum, there is a growing desire for tastier and more realistic dairy-identical products made without cows. Several food-tech companies, such as Perfect Day ® , New Culture ® and Motif Foodworks ® , have recently set out to produce dairy-identical products in labs using genetically engineered microflora, like yeast, fungi or bacteria. Using cow DNA as a model, scientists synthesize DNA sequences containing instruc- tions for the production of dairy proteins such as casein and whey. The DNA is inserted into the microflora which is then used to produce the dairy proteins through a process called fermentation. During fermentation, carbohydrates like sugars are converted into energy without the use of oxygen. To begin fermentation, the engineered microflora are fed plant sugars, such as glucose and galactose, and other nutrients to support abundant growth. The microflora not only convert the sugars into energy and other fermentation byproducts but also produce the dairy proteins. The proteins are harvested by either collecting them from within the cells or removing them from the fermentation culture liquid, depending on the type of microflora that produced them.
Ginkgo immune system The oldest living Ginkgo biloba tree is thought to be over 1,500 years old, meaning it was cultivated in the early 6th century. Several ginkgo trees even survived the bombing of Hiroshima. As a species, ginkgo has been around for over 270-million-years and has changed very little genetically. However, scientists are still at odds with how the trees have such extraordinary lifespans. A group of researchers set out to determine
Cosmo the bull In the beef industry, male cattle are more desirable than females because they are about 15 percent more efficient at converting feed into weight gain. More weight gain means more beef yield per cow, allowing ranchers to keep fewer cattle on their farms. Producing more male cattle is not only econom- ically desirable but also environmentally favorable because fewer cattle also means a lower production of greenhouse gas emissions. Like most sexually reproducing animals, cows have a 50 percent chance of giving birth male offspring. However, scientists at the University of California, Davis, seek to increase cows’ likelihoods of producing male offspring using genome-editing technology.
the molecular and metabolic mechanisms behind the longevity. By looking at tree cores from young and old Ginkgo biloba trees in China ranging from 15 to 1,353 years old, the team determined that tree growth did not decline from 10- to 600-year old trees. This indicates that the vascular cambium, the layer of stem cells between the bark and the inner wood of the trunk, can maintain continuous growth for several hundred years. The researchers also performed genetic analysis on the vascular cambium stem cells. They found that the genes responsible for the trees’ immune systems do not diminish over time like they do in other organisms as they age. This means the trees have antioxidants, immune cells and hormones that allow them to fight off pathogens and stressors throughout their centuries-long lives. REFERENCE: Wang, L. et al. Multifeature analyses of vascular cambial cells reveal longevity mechanisms in old Ginkgo biloba trees. PNAS (2020) 117:2201-2210. doi: 10.1073/pnas.1916548117. In some cases, production of products further involves forming casein micelle structures, or clusters of casein protein, which more accurately mimics the natural form casein protein takes when suspended in milk water. The food scientists use calcium and various salts to form the micelles, providing additional nutri- tional value to the proteins. After harvesting the proteins, they can be combined with plant fats, water, vitamins, minerals and other components to produce dairy-free versions of products such as cheese, milk and ice cream. Perfect Day recently began selling ice creammade with its animal-free dairy proteins and the reviews so far indicate that it is a dairy-free product that tastes and feels identical to regular ice creammade from cow’s milk. Whether their motivation to eat animal-free dairy products is driv- en by ethical, environmental or health reasons, consumers will soon have a variety of dairy-identical products from which to choose. REFERENCES: Forbes. Got Milk? This $40M Startup Is Creating Cow-Free Dairy Products That Actually Taste Like The Real Thing. 9 January 2019. Web. 30 August 2020. https://www.forbes.com/sites/alexandrawilson1/2019/01/09/got-milk-this- 40m-startup-is-creating-cow-free-dairy-products-that-actually-taste-like-the-re- al-thing/#2e71ce9540dc. Livekindly. Dairy-identical vegan cheese is coming to save the cows. 29 January 2020. Web. 30 August 2020. https://www.livekindly.co/dairy-identical-vegan-cheese- is-coming-to-save-cows. Food Navigator-USA. ‘Real’ cheese… without cows? New Culture makes mozzarella with milk proteins via microbial fermentation. 24 June 2019. Web. 30 August 2020. https://www.foodnavigator-usa.com/Article/2019/06/24/Real-cheese- without-cows-New-Culture-makes-mozzarella-with-milk-proteins-via- microbial-fermentation.
Smartphone DNA testing A device that can fit in your pocket and perform DNA testing in the middle of nowhere in as little as 80 minutes seems like something out of a futuristic, science fiction movie. But thanks to an international team of researchers, this smartphone-based device is a reality. The device uses simple 3D-printed parts to turn a standard smart- phone into a $10, on-the-spot DNA test that achieves 97 percent accuracy. Samples are loaded into the attachable detector, mixed with pre-filled chemicals and heated by the phone itself. The sam- ple lights up or changes color if complementary DNA in the sample binds a probe within the device. This signal is detected through a lens attached to the camera on the phone, and the results are displayed on the phone. Through preliminary testing, the researchers determined the device can detect long and short fragment deletions, single-base substitu- tions and insertions, as well as pathogen-specific DNA sequences from a variety of samples including blood, cheek swabs, urine, milk, river water and plant leaves. They identified genetic conditions like alpha- and beta-thalassemia in blood, E coli bacteria in river water and milk and a bacterium that attacks kiwi fruit plants from samples of the plants leaves. Although this is an early prototype, it shows promise for portable, affordable DNA testing devices that would be invaluable for doctors, farmers, food safety officials and environmental monitoring agencies. Phylloxera was accidentally introduced to Europe in the 1860s and nearly brought French grape cultivation to an end. Because North American grapevines are resistant to phylloxera, many growers graft American roots onto European grapevines to give them tolerance. This is time consuming and expensive. Understanding the manner by which phylloxera invade and destroy the grapevines would make it possible to engineer phylloxera-resistant grapevines. By sequencing the genome of phylloxera and comparing it with its common ancestor aphids, researchers identified a huge new gene family containing nearly 3,000 genes that have evolved in the phyllox- era genome. These genes code for small secreted proteins, called effectors, which scientists think deactivate the basic defenses of the plants, enabling the insects to colonize and feed on the grape vines. Phylloxera originated in North America and researchers believe a co-evolutionary relationship developed with American grape vines, allowing the parasite and host plant to co-exist. However, cultivated European vines lack the ability to ward off the lethal cocktail of effector proteins. REFERENCE: Rispe, C. et al. The genome sequence of the grape phylloxera provides insights into the evolution, adaptation, and invasion routes of an iconic pest. BMC Biology (2020) 18:90. doi: 10.1186/s12915-020-00820-5.
Cosmo and his mother behind him
Cosmo, a 110-pound bull calf born in April 2020 at UC Davis, was genome-edited as an embryo so that he will produce more male offspring. Scientists used CRISPR-based genome editing to make targeted cuts in a chromosome and insert the SRY gene, in a process called gene knock-in. SRY, typically found on the Y chromosome, encodes for sex determining region Y (SRY) protein that is responsible for the initiation of male sex characteristics, like the formation of testes. Cosmo’s offspring should be 75 percent males, with 50 percent XY males and 25 percent XX animals that co-inherit the SRY gene and develop male traits. The SRY gene was integrated in a region of bovine chromosome 17 known as a genomic safe harbor site, meaning the genetic insertion doesn’t interfere with nearby genes. Scientists will not know if inheriting the SRY gene is enough to trigger the male developmental pathway in XX embryos until Cosmo reaches sexual maturity in a year and can produce offspring. REFERENCE: Owen, J.R. et al. Production of a gene knock-in bull calf by embryo-mediated genome editing. Poster presented at: American Society of Animal Science meeting (2020).
REFERENCE: Xu, H. et al. An ultraportable and versatile point-of-care DNA testing platform. Science Advances (2020) 6:eeaz7445 doi: 10.1126/sciadv.aaz7445.
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