Antisense drugs are gene-based molecules that inhibit the synthesis of proteins (including proteins that cause specific diseases) by binding to the ribonucleic acids (RNAs) responsible for their formation. Specifically, these drugs are single-stranded short polymers of RNA or deoxyribonucleic acid (DNA), termed oligonucleotides, designed to contain part of the noncoding strand of messenger RNA (mRNA), which is a molecule involved in translating DNA into protein. Antisense medications are therefore capable of hybridizing with and inactivating the mRNA, preventing the associated gene from producing the unwanted protein. With their anticancer, antiviral, and anti-inflammatory therapeutic capacities, these drugs have been applied in the treatment of various genetic disorders and infections, including diabetes, rheumatoid arthritis, cytomegalovirus retinitis (a virally caused form of blindness that occurs often in AIDS patients), asthma, hypercholesterolemia (a genetic derangement of fat metabolism characterized by very high levels of cholesterol in the blood), and numerous cancers. Research is also being conducted on patients suffering from Parkinson's disease and Huntington's disease to determine whether antisense therapy can mitigate the effects of these conditions. See also: Biotechnology; Deoxyribonucleic acid (DNA); Disease; Gene; Genetic engineering; Oligonucleotide; Protein; Ribonucleic acid (RNA)

Caenorhabditis elegans is a small, unsegmented, transparent member of the order Rhabditida in the phylum Nematoda (Nemata). Measuring approximately 1 millimeter in length in its adult form, this roundworm is typically found in soil, often feeding on bacteria among rotting vegetation and decaying organic matter, and is nonparasitic (free living) and nonpathogenic. Despite being a primitive invertebrate, C. elegans possesses many of the anatomical features and organs found in higher-level animals, such as those pertaining to its nervous, reproductive, muscular, and digestive systems; however, it lacks a circulatory system and a respiratory system. Because C. elegans is transparent, easily observed and manipulated, has a relatively short life cycle (2–3 weeks), and can be cultivated in large numbers under laboratory conditions (with 10,000 nematodes per petri dish), researchers frequently use it to study questions that would be difficult to explore directly in humans and other animals. In particular, because the cells of C. elegans hold steady in number and position in the body throughout its life, it is a popular model organism in developmental biology, embryology, genetics, and neuroscience. See also: Developmental biology; Developmental genetics; Embryology; Genetics; Invertebrate embryology; Nemata (Nematoda); Nervous system (invertebrate); Rhabditida

The critically endangered northern white rhinoceros (Ceratotherium simum cottoni) is a subspecies of white rhino that is on the brink of complete extinction, with only two individuals left in captivity and no known members reported in the wild. The two remaining individuals are a mother (named Najin) and her daughter (named Fatu) residing at the Ol Pejeta Conservancy in Kenya. As both females are unable to reproduce naturally, scientists have taken the extraordinary step of producing viable embryos in the laboratory. In order to generate the embryos, biologists extracted eggs from the female rhinos; then, the eggs were artificially inseminated with cryopreserved (frozen) sperm from two male northern white rhinos that had died in 2014 and 2006, but whose sperm had been kept in storage and subsequently thawed. Out of 10 eggs that were harvested, 7 successfully matured to the point that they were able to undergo fertilization. However, only 2 of these fertilized eggs (both derived from the daughter Fatu) developed into viable embryos. Until a satisfactory surrogate female individual (most likely a member of the southern white rhino subspecies, which has an estimated population of 20,000) is found, and into whose body either or both of the embryos can be transferred, the 2 embryos have been frozen in order to preserve them for future use. See also: Africa; Cryobiology; Endangered species; Extinction; Fertilization (animal); Genetics; Northern white rhinoceros on the brink of extinction; Population ecology; Population viability; Rhinoceros

Scientists have suggested a possible connection between ancient Neandertals (Homo neanderthalensis) and the severity of disease in patients affected by COVID-19. In short, certain genes acquired from Neandertals during instances of interbreeding with ancestors of modern humans (Homo sapiens) approximately 60,000 years ago may be involved in the susceptibility of individuals to severe disease from the virus that causes COVID-19. Specifically, researchers have identified a region on human chromosome 3 that possibly influences whether a person infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will become seriously ill and require artificial ventilation. This chromosomal region is almost identical to a segment found in the DNA of Neandertals from Croatia and Siberia, and present-day carriers of the Neandertal-derived gene variant on human chromosome 3 have an increased likelihood of developing life-threatening forms of COVID-19. See also: Chromosome; Coronavirus; Deoxyribonucleic acid (DNA); Gene; Neandertal DNA; Neandertals; Novel coronavirus is declared a global pandemic

The biotechnology used in the creation of genetically modified crops is being expanded to encompass the bioengineering of plants that contain therapeutically important proteins and molecules that can be utilized in the manufacturing of pharmaceutical drugs. Often termed "pharming" (a blending of the words pharmaceutical and farming), this process allows scientists to transform a plant's genome via the insertion of a foreign deoxyribonucleic acid (DNA) molecule that carries the genetic information for a pharmaceutical substance. Once the new DNA is inserted, the cultivated plant can produce (by use of its inherent protein-making machinery) large quantities of active pharmaceutical ingredients. Then, these ingredients can be extracted from the plant and processed into a pharmaceutical formulation that has medical application. Specific products include medicinal drugs, vaccines, therapeutic proteins, antibiotics, antibodies, and diagnostic compounds. In other words, the methodology creates a scenario in which farmed plants and crops act as miniature bioreactors or factories to produce pharmaceuticals in an efficient and economically viable manner. See also: Agricultural science (plant); Biologicals; Biotechnology; Deoxyribonucleic acid (DNA); Genetic engineering; Genetically engineered plants; Genetically modified crops; Medicine; Pharmacology; Pharmacy; Protein

Genealogists and anthropologists have long disputed the provenance of domestic dogs (Canis lupus familiaris). Although genetic analyses and fossil evidence indicate that the domestic dog descended from the gray wolf (Canis lupus), the exact location (or locations) and time (or times) of origin for canine domestication are contentious topics. Southeast Asia and Europe have often been noted as early centers for the domestication of dogs, with most researchers assigning a probable range of dates between 15,000 and 32,000 years ago as the time for dog domestication. However, a recent study pinpoints northern Siberia as the origin of the domestication of dogs and estimates that domestication took place approximately 23,000 years ago. Early domesticated dogs later dispersed eastward to the Americas and westward to Eurasia as ancient Siberian peoples migrated away from their original geographic homes. See also: Anthropology; Dogs; Domestication; Fossil; Phylogeny; Zooarcheology

Sickle cell disease, also termed sickle cell anemia, is a genetic disorder in which hypoxia, or oxygen deprivation, causes red blood cells (erythrocytes) to assume a rigid sickle shape, blocking blood flow within blood vessels. The disease results from a single nucleotide mutation in the gene for beta-globin (β-globin), which causes production of an abnormal form of hemoglobin—an oxygen-carrying protein in red blood cells. Millions of people worldwide suffer from sickle cell disease, enduring lifelong anemia, as well as possible organ damage and potentially early death. The abnormal rigidity of sickle cells also causes painful obstruction of small blood vessels, and recurrent painful episodes are frequent in the absence of proper therapies. The most common treatment options include analgesics for pain, antibiotics for fighting infections, transfusions for episodes of severe anemia, and hydroxyurea (an oral medication that hinders formation of sickle-shaped red blood cells and reduces inflammation). See also: Anemia; Blood; Blood vessel; Hemoglobin; Human genetics; Mutation; Nucleotide; Sickle cell disease

Researchers are learning more about how plants respond to "alarm signals" released by other plants that are under attack by herbivores. To warn conspecifics about predators, many animals issue alarms by vocalizing or emitting odors. In the case of plants, warnings come in the form of volatile organic compounds emitted when an herbivore causes damage to a plant by eating a portion of the plant. Prior research has established that nearby plants can detect these volatiles and subsequently activate herbivore defense systems. Those systems produce chemicals that protect the warned plants from potential predators. A new study based on experiments involving the model organism Arabidopsis thaliana, commonly known as thale cress, has now shed light on the poorly understood mechanisms underlying this defense activation. The study shows that the volatiles induce specific epigenetic changes in the plant, meaning changes in the levels of genes that are expressed, or "switched on," due to an external environmental influence. The findings could help agriculturalists devise ways to boost plant's natural herbivory resistance and thus reduce farmers’ use of pesticides. See also: Agricultural science (plant); Agriculture; Epigenetics; Pesticide; Plant-animal interactions; Plant communication; Volatilization

Circadian clocks, or rhythms, govern the daily activities of nearly all life on Earth. In animals, these systems, often referred to as internal or biological clocks, regulate a wide array of physiological processes, such as the sleep-wake cycle, hormone secretion, body temperature regulation, metabolism, immune system activity, cell regeneration, and behavior. Plants, too, are known to have circadian clocks. While the role of circadian rhythms has been studied extensively in humans and other multicellular organisms, investigating their function in bacteria is a relatively new pursuit. Despite having a small genome, bacteria show evidence of complex circadian clock activity that parallels their multicellular counterparts. See also: Bacteria; Biological clock; Circadian clock (plants)

CRISPR/Cas9 gene editing is a modern technique that targets specific stretches of genetic code and allows editing of deoxyribonucleic acid (DNA) at designated locations. It has been at the forefront of genetic research, providing scientists with the ability to undertake various genome-engineering projects, including opportunities for the modification of genes and the potential correction of mutations to prevent genetic diseases. However, the CRISPR (which stands for clustered regularly interspaced short palindromic repeats) genomic tool is limited by its precision. Specifically, the limiting factor is the DNA-cutting enzyme. The most commonly used enzyme is known as Cas9, but it only attaches to and targets a particular three-base sequence in the DNA that occurs in one-sixteenth of the human genome. This hampers the ability of researchers to carry out many applications that would entail editing of sequential segments of the DNA that occur more often. See also: CRISPR-based immunity in prokaryotes; CRISPR/Cas9 gene editing; CRISPR genome-editing methods against superbugs; Deoxyribonucleic acid (DNA); Enzyme; Gene; Genetic code; Genetic engineering; Genetics; Mutation