Big Fish Games 22 Games Cracks Included
Annalisa Vanzanten
"What the movie shows is very interesting. The animal excavates sand to get the shell out, then swims for a long time to find an appropriate area where it can crack the shell," Bernardi said. "It requires a lot of forward thinking, because there are a number of steps involved. For a fish, it's a pretty big deal."
The actions recorded in the video are remarkably similar to previous reports of tool use by fish. Every case has involved a species of wrasse using a rock as an anvil to crush shellfish. A report published in June in Coral Reefs included photos of this behavior in a blackspot tuskfish on Australia's Great Barrier Reef. Bernardi said he first heard of the phenomenon in 1994, when a colleague (James Coyer) observed a yellowhead wrasse in Florida doing the same thing. Similar behavior was also reported in a sixbar wrasse in an aquarium setting.
Wrasses are one of the largest and most diverse families of marine fishes. Bernardi noted that several of the species observed using tools are not closely related, but cover a broad range of evolutionary history within the wrasse family. "They are at opposite ends of the phylogenetic tree, so this may be a deep-seated behavioral trait in all wrasses," he said.
Tool use was once considered an exclusively human trait, and Jane Goodall's reports of tool use in chimpanzees in the 1960s came as a stunning revelation. Since then, many other animals have been observed using tools, including various primates, several kinds of birds, dolphins, elephants, and other animals.
Bernardi, who studies fish genetics, said there may be other examples of tool use in fish that have not yet been observed. "We don't spend that much time underwater observing fishes," he said. "It may be that all wrasses do this. It happens really quickly, so it would be easy to miss."
The project was led by Marc Meyers, a professor of nanoengineering and mechanical engineering at the University of California San Diego, and Robert Ritchie, a professor of mechanical engineering and materials science at the University of California Berkeley.
Left: Six successive views of the stages of Arapaima fish scale cracking during tests. Right: Cracking causes separation in the mineralized layer, while the collagen layer prevents further damage due to stretching, rotation and delamination. Image courtesy of Meyers lab/Matter
They tested this by creating cracks in Arapaima scales and soaking them in water for 48 hours, then slowly pulling the edges apart while applying force through a special fixture. As they increased the force, they observed that part of the mineralized, hard outer layer expanded, cracked, and then gradually peeled off. The scales localized the crack, containing it and preventing damage from spreading in the twisting structural collagen layer. If the applied pressure did break through the scale, it deformed the scale rather than breaking it.
Vitamin B6 is a water-soluble vitamin that is naturally present in many foods, added to others, and available as a dietary supplement. It is the generic name for six compounds (vitamers) with vitamin B6 activity: pyridoxine, an alcohol; pyridoxal, an aldehyde; and pyridoxamine, which contains an amino group; and their respective 5'-phosphate esters. Pyridoxal 5' phosphate (PLP) and pyridoxamine 5' phosphate (PMP) are the active coenzyme forms of vitamin B6 [1,2]. Substantial proportions of the naturally occurring pyridoxine in fruits, vegetables, and grains exist in glycosylated forms that exhibit reduced bioavailability [3].
Vitamin B6 in coenzyme forms performs a wide variety of functions in the body and is extremely versatile, with involvement in more than 100 enzyme reactions, mostly concerned with protein metabolism [1]. Both PLP and PMP are involved in amino acid metabolism, and PLP is also involved in the metabolism of one-carbon units, carbohydrates, and lipids [3]. Vitamin B6 also plays a role in cognitive development through the biosynthesis of neurotransmitters and in maintaining normal levels of homocysteine, an amino acid in the blood [3]. Vitamin B6 is involved in gluconeogenesis and glycogenolysis, immune function (for example, it promotes lymphocyte and interleukin-2 production), and hemoglobin formation [3].
Vitamin B6 concentrations can be measured directly by assessing concentrations of PLP; other vitamers; or total vitamin B6 in plasma, erythrocytes, or urine [1]. Vitamin B6 concentrations can also be measured indirectly by assessing either erythrocyte aminotransferase saturation by PLP or tryptophan metabolites. Plasma PLP is the most common measure of vitamin B6 status.
PLP concentrations of more than 30 nmol/L have been traditional indicators of adequate vitamin B6 status in adults [3]. However, the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences) used a plasma PLP level of 20 nmol/L as the major indicator of adequacy to calculate the Recommended Dietary Allowances (RDAs) for adults [1,3].
Intake recommendations for vitamin B6 and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the FNB [1]. DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and gender, include the following:
Table 1 lists the current RDAs for vitamin B6 [1]. For infants from birth to 12 months, the FNB established an AI for vitamin B6 that is equivalent to the mean intake of vitamin B6 in healthy, breastfed infants.
Vitamin B6 is found in a wide variety of foods [1,3,4]. The richest sources of vitamin B6 include fish, beef liver and other organ meats, potatoes and other starchy vegetables, and fruit (other than citrus). In the United States, adults obtain most of their dietary vitamin B6 from fortified cereals, beef, poultry, starchy vegetables, and some noncitrus fruits [1,3,5]. About 75% of vitamin B6 from a mixed diet is bioavailable [1].
The U.S. Department of Agriculture's (USDA's) FoodData Central lists the nutrient content of many foods and provides a comprehensive list of foods containing vitamin B6 arranged by nutrient content and by food name.
Vitamin B6 is available in multivitamins, in supplements containing other B complex vitamins, and as a stand-alone supplement [7]. The most common vitamin B6 vitamer in supplements is pyridoxine (in the form of pyridoxine hydrochloride [HCl]), although some supplements contain PLP. Vitamin B6 supplements are available in oral capsules or tablets (including sublingual and chewable tablets) and liquids. Absorption of vitamin B6 from supplements is similar to that from food sources and does not differ substantially among the various forms of supplements [1]. Although the body absorbs large pharmacological doses of vitamin B6 well, it quickly eliminates most of the vitamin in the urine [8].
PLP concentrations tend to be low in people with alcohol dependence; those with obesity; and pregnant people, especially those with preeclampsia or eclampsia [1]. They are also low in people with malabsorption syndromes such as celiac disease, Crohn's disease, and ulcerative colitis [3].
Isolated vitamin B6 deficiency is uncommon; inadequate vitamin B6 status is usually associated with low concentrations of other B-complex vitamins, such as vitamin B12 and folic acid [2]. Vitamin B6 deficiency causes biochemical changes that become more obvious as the deficiency progresses [2].
Vitamin B6 deficiency is associated with microcytic anemia, electroencephalographic abnormalities, dermatitis with cheilosis (scaling on the lips and cracks at the corners of the mouth) and glossitis (swollen tongue), depression and confusion, and weakened immune function [1,2]. Individuals with borderline vitamin B6 concentrations or mild deficiency might have no deficiency signs or symptoms for months or even years. In infants, vitamin B6 deficiency causes irritability, abnormally acute hearing, and convulsive seizures [2].
End-stage renal diseases, chronic renal insufficiency, and other kidney diseases can cause vitamin B6 deficiency [3]. In addition, vitamin B6 deficiency can result from malabsorption syndromes, such as celiac disease, Crohn's disease, and ulcerative colitis. Certain genetic diseases, such as homocystinuria, can also cause vitamin B6 deficiency [2]. Some medications, such as antiepileptic drugs, can lead to deficiency over time.
Frank vitamin B6 deficiencies are relatively rare in the United States but some individuals might have marginal vitamin B6 status [2]. The following groups are among those most likely to have inadequate intakes of vitamin B6.
People with poor renal function, including those with end-stage renal disease and chronic renal insufficiency, often have low vitamin B6 concentrations [3]. Plasma PLP concentrations are also low in patients receiving maintenance kidney dialysis or intermittent peritoneal dialysis, as well as those who have undergone a kidney transplant, perhaps due to increased metabolic clearance of PLP [11]. Patients with kidney disease often show clinical symptoms similar to those of people with vitamin B6 deficiency [11].
People with rheumatoid arthritis often have low vitamin B6 concentrations, and vitamin B6 concentrations tend to decrease with increased disease severity [3]. These low vitamin B6 levels are due to the inflammation caused by the disease and, in turn, increase the inflammation associated with the disease. Although vitamin B6 supplements can normalize vitamin B6 concentrations in patients with rheumatoid arthritis, they do not suppress the production of inflammatory cytokines or decrease levels of inflammatory markers [3,12].
Patients with celiac disease, Crohn's disease, ulcerative colitis, inflammatory bowel disease, and other malabsorptive autoimmune disorders tend to have low plasma PLP concentrations [3]. The mechanisms for this effect are not known. However, celiac disease is associated with lower pyridoxine absorption, and low PLP concentrations in inflammatory bowel disease could be due to the inflammatory response [3].
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