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Category: biotech/medical

A new discovery explains what determines the number and position of genetic exchanges that occur in sex cells, such as pollen and eggs in plants, or sperm and eggs in humans.

When are produced by a special cell division called meiosis, chromosomes exchange large segments of DNA. This ensures that each new cell has a unique genetic makeup and explains why, with the exception of identical twins, no two siblings are ever completely genetically alike. These exchanges of DNA, or crossovers, are essential for generating , the driving force for evolution, and their frequency and position along chromosomes are tightly controlled.

Co-first author of the study Dr. Chris Morgan explains the significance of this phenomenon: “Crossover positioning has important implications for evolution, fertility and selective breeding. By understanding the mechanisms that drive crossover positioning we are more likely to be able to uncover methods to modify crossover positioning to improve current plant and animal breeding technologies.”

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In the latest of ongoing efforts to expand technologies for modifying genes and their expression, researchers have developed chemically modified guide RNAs for a CRISPR system that targets RNA instead of DNA. These chemically-modified guide RNAs significantly enhance the ability to target — trace, edit, and/or knockdown — RNA in human cells.

In a study published today in Cell Chemical Biology, the team explores a range of different RNA modifications and details how the modified guides increase efficiencies of CRISPR activity from 2-to 5-fold over unmodified guides. They also show that the optimized chemical modifications extend CRISPR targeting activity from 48 hours to four days. The researchers worked in collaboration with scientists at Synthego Corporation and New England BioLabs, bringing together a diverse team with expertise in enzyme purification and RNA chemistry. To apply these optimized chemical modifications, the research team targeted cell surface receptors in human T cells from healthy donors and a “universal” segment of the genetic sequence shared by all known variants of the RNA virus SARS-COV-2, which is responsible for the COVID-19 pandemic.

Increasing the efficiencies and “life” of CRISPR-Cas13 guides is of critical value to researchers and drug developers, allowing for better gene knockdown and more time to study how the gene influences other genes in related pathways.

“CRISPR RNA guide delivery can be challenging, with knockdown time limited due to rapid guide degradation. We were inspired by the guide modifications developed for other DNA-targeting CRISPRs and wanted to test if chemically modified guides could improve knockdown time for RNA-targeting CRISPR-Cas13 in human cells,” says Alejandro Méndez-Mancilla, PhD, a postdoctoral scientist in the lab and co-first author of the study.

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“The reason a glucose-responsive insulin is important is that the biggest barrier to the effective use of insulin, especially in Type 1 diabetes, is the fear of the consequences of blood sugar going too low,” says study author Michael A. Weiss.

For sufferers of diabetes, keeping blood glucose levels within a healthy range can be a difficult and labor-intensive balancing act that often requires regular insulin injections, but some scientists imagine a future where medicine does the heavy lifting for them. A team at Indiana University School of Medicine has taken a promising step towards this future, demonstrating a type of “synthetic hinge” that swings into action when blood glucose levels call for corrective action.

The hormone insulin plays a vital role in keeping glucose at healthy levels in the blood, pulling it out of the bloodstream and helping turn it into energy. In diabetes patients, insufficient amounts or insulin that results in a reduction in effectiveness means that blood glucose levels are left to rise to potentially dangerous levels, which can have serious consequences.

Injections of insulin are a way for Type 1 diabetics to manage the condition, but one dangerous side effect of this is the potential for them to drive blood-sugar levels too low, a condition known as hypoglycemia. These concerns have moved scientists to explore a concept known as “glucose-responsive insulin,” an engineered form of the hormone that would self-adjust depending on the blood sugar levels of the patient.

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The idea is to offer the predictions for the structure of practically every protein with a known sequence of amino acids free of charge. “We believe that this is the most important contribution to date that artificial intelligence has contributed to scientific knowledge,” he said following the publication of DeepMind’s research in the medical journal Nature.

DeepMind, a company bought by Google, predicts with unprecedented precision the 3D structure of nearly all the proteins made by the human body.

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The company that makes SG was testing it mainly against other cancers, but Dr. Tagawa, who is also a professor of urology and a member of the Sandra and Edward Meyer Cancer Center at Weill Cornell Medicine, and his colleagues showed in a 2015 pilot trial that it shrank tumors in three of six patients with advanced urothelial carcinoma that had not responded to platinum-based chemotherapy. That trial led to the enrollment of a group of 45 patients with treatment-refractory urothelial carcinoma (amongst many others with various advanced cancers) with encouraging results.

A new treatment for advanced urothelial cancer was effective with tolerable side effects in an international, multi-center phase 2 clinical trial led by investigators at Weill Cornell Medicine and NewYork-Presbyterian.

The trial results prompted a U.S. Food and Drug Administration (FDA) accelerated approval of the treatment on April 13, giving patients with this very aggressive type of cancer a new therapeutic option.

In the study, published online April 30 in the Journal of Clinical Oncology, the researchers gave the treatment, sacituzumab govitecan (SG), previously known as IMMU-132 and now by the trade name Trodelvy, to 113 patients with advanced urothelial carcinoma, the most common type of bladder cancer. The trial population had progressed despite treatment with platinum-based chemotherapy and immune-boosting checkpoint inhibitors, and overall had a median of 3 prior lines of therapy. Treatment with SG was followed by sustained reductions in tumor size for 31 patients (27 percent), including complete tumor disappearance in six patients. The most common severe side effects included very low white blood cell count in 34 percent (with fever in 10 percent) and severe diarrhea in 9 percent, which were managed with dose adjustment and best supportive care.

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Last week, a young woman with sickle cell anemia became the first person in the United States to have her cells altered with CRISPR gene editing technology. Here’s what that means for the future treatment of genetic diseases.

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Right now, protection against Covid-19 comes via an injection. But in future, those vaccines could come from inhalers or even pills.

In a white, airy laboratory in Medicon Village, one of southern Sweden’s largest science parks, chemist Ingemo Andersson holds up a thin, plastic inhaler, half the size of a matchbox.

Her team is hoping this tiny product could play a big role in the global fight against coronavirus allowing people to take powdered versions of future vaccines at home.

Researchers are looking at easier ways for people to get the vaccine, including via inhalers and tablets.

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