Life and health

Flaviviridae

Flaviviridae, family of enveloped positive-sense single-stranded RNA viruses in four genera (Orthoflavivirus, Pestivirus, Hepacivirus, Pegivirus); includes dengue, Zika, yellow fever, West Nile, and hepatitis C viruses, mostly mosquito- or tick-borne.

Flavivirus

Flavivirus (Orthoflavivirus), a genus of Flaviviridae: enveloped ~40–60 nm positive-sense RNA arboviruses transmitted by mosquitoes or ticks, including yellow fever, dengue, Zika, and West Nile viruses.

Flavobacteriaceae

Flavobacteriaceae, the largest family of the phylum Bacteroidota (flavobacteria), are Gram-negative aerobic rods from soil, freshwater, and sea, marked by gliding motility via the T9SS, polysaccharide-degrading PULs, and fish pathogens such as F. columnare and F. psychrophilum.

Flavobacterium inter-domain disulphide bond domain

FIDD (Flavobacterium inter-domain disulphide bond domain) is a Pfam protein domain found in Flavobacterium surface proteins, occurring in large multidomain adhesin-like proteins alongside CHU_C, fn3, Lectin_C and type IX secretion-associated modules.

Flavocytochrome c

Flavocytochrome c, or flavocytochrome c sulfide dehydrogenase (FCSD, EC 1.8.2.-), is a bacterial FAD- and heme c-containing periplasmic enzyme that oxidizes sulfide to polysulfide and passes electrons to cytochrome c, distinct from SQR; found in phototrophic sulfur bacteria and Gram-negative heterotrophs like Cupriavidus necator H16.

Oct 20, 2026

Flavodoxin

Flavodoxin (Fld), a small FMN-containing electron-transfer flavoprotein of bacteria and algae, replaces iron–sulfur ferredoxin under iron starvation; first isolated from Clostridium pasteurianum in 1966, absent from land plants.

Flavonoid

Flavonoids are plant polyphenols with a C6–C3–C6 chalcone-derived skeleton, spanning flavonols, flavones, flavanones, flavan-3-ols, isoflavones, and anthocyanidins; dietary intake, low bioavailability, and cardiovascular evidence are covered.

Flavonoid modification enzymes

Flavonoid modification enzymes are plant enzymes that decorate flavonoid skeletons with sugars, methyl groups, and acyl groups through glycosylation, methylation, and acylation, changing stability, color, and biological activity.

Flavoprotein

Flavoproteins are enzymes carrying tightly bound FMN or FAD (riboflavin-derived flavins) that mediate one- and two-electron redox chemistry; 90 human flavoprotein genes span TCA cycle, beta-oxidation, and respiratory chain.

Flavor

Flavor is the multisensory experience of eating, combining taste, retronasal smell, and trigeminal somatosensation, shaped by visual and sound cues; most people mistake it for taste alone and never notice the olfactory component.

FLAVOUR II trial

FLAVOUR II: 2020-2023 Chinese multicenter randomized non-inferiority trial (1,839 randomized, Lancet 2025) showing AI angiography-derived FFR-guided PCI non-inferior to IVUS guidance at 12 months with fewer stents.

Flavoxate

Flavoxate (Urispas, W-61) is a synthetic flavone urinary tract spasmolytic and competitive muscarinic antagonist, FDA-approved in 1970, used for symptomatic relief of dysuria, urgency, and bladder spasms.

Flavr Savr

Flavr Savr (FLAVR SAVR) was Calgene's genetically modified tomato, the first GM whole food sold, FDA-approved May 18, 1994. Antisense PG gene slowed softening; high costs and poor yields ended sales by 1997.

Flax

Flax (Linum usitatissimum, from wild L. bienne) is a founder crop grown for linen fibre and linseed. Fibre types are tall and unbranched, oil types short and branched; seeds hold 40-45% oil, over 50% linolenic acid, and flax is the richest known lignan source.

Flaxseed

Flaxseed (linseed, Linum usitatissimum) is the ALA- and lignan-rich seed of the flax plant; GRAS-recognized in the US, with meta-analyses supporting cholesterol and CRP/IL-6 lowering.

Flazasulfuron

Flazasulfuron (Shibagen) is a sulfonylurea, WSSA Group 2 ALS-inhibiting herbicide developed by Ishihara Sangyo, registered in Japan in 1989, used on turf, vines, and orchards; EU-approved 2017 to 2032, CAS 104040-78-0.

FLCN

FLCN (folliculin) is a tumor suppressor gene on chromosome 17p11.2; germline variants cause Birt-Hogg-Dubé syndrome with fibrofolliculomas, lung cysts, pneumothorax, and renal tumors requiring lifelong MRI surveillance.

Flea

Flea (order Siphonaptera): small wingless blood-feeding insect parasite of mammals and birds. Over 2,500 species; four-stage lifecycle; vectors plague, murine typhus, and cat scratch disease.

Flecainide

Flecainide (flecainide acetate, trade name Tambocor) is a class IC antiarrhythmic drug blocking fast sodium channels, used for atrial fibrillation and approved by the FDA in 1984, but avoided after heart attacks.

Fleck corneal dystrophy

Fleck corneal dystrophy (FCD), or François-Neetens speckled corneal dystrophy, is a rare autosomal dominant PIKFYVE-related stromal corneal dystrophy with tiny non-progressive white flecks, normal vision, and no treatment required.

Flehmen response

Flehmen response, also called flehmening or the flehmen grimace: a mammalian lip-curling, head-raising behavior that draws pheromones into the vomeronasal organ, used mainly by male ungulates and felids to detect estrus.

Flemish Giant rabbit

The Flemish Giant rabbit is a domestic rabbit breed from Flanders, Belgium, and the largest in the world, with adults typically weighing 15 to 22 pounds.

Flesh fly

Sarcophagidae, flesh flies, a calyptrate fly family with three subfamilies; many are larviparous, depositing live larvae on carrion; forensically important for PMI estimation but hard to identify to species.

Flexibilia

Flexibilia: an extinct clade of flexible-calyx stalked crinoids, sister to Eucladida within Cladida, comprising orders Taxocrinida and Sagenocrinida; about 82 genera, middle Silurian to end-Permian fossil record.

Flexibility (anatomy)

Flexibility (anatomy): joint range of motion and resistance to rotation, shaped by extracellular matrix, titin, and stretch tolerance; improved mainly by static, dynamic, and PNF stretching.

Flexible assertive community treatment

Flexible assertive community treatment (FACT), also called Function ACT, is a Dutch adaptation of assertive community treatment serving all people with severe mental illness in a catchment area.

Flexible bronchoscopy

Flexible bronchoscopy, also known as flexible fiberoptic bronchoscopy, is a pulmonary procedure in which a thin flexible endoscope is passed through the nose or mouth to visualize and sample the airways.

Flexible cystoscopy

Flexible cystoscopy is an endoscopic examination in which a thin, steerable camera tube is passed through the urethra into the bladder to inspect its lining, in use since 1973.

Flexible endoscopy

Flexible endoscopy is a diagnostic and therapeutic procedure in which a bendable fiber-optic or video endoscope is passed into hollow organs to inspect their lining, take biopsies, and deliver treatment.