Biology Articles
Effects on efficacy endpoints - ...en after several hours a long-term down-regulation of GH secretion. We have published the only comparison of different patterns of GHRP exposure on lo...
Functional activation of cloned cells - ...r human embryonic kidney fibroblasts (HEK-293). Both cell types do not express detectable endogenous GHS-Rs. Binding and functional activation assays ...
Enhancement of hormone release - ...xarelin injection; SRIH levels in HPB did not change throughout the study; the magnitude of GHRH increase after acute hexarelin administration was sim...
How are drones related to queen bees - ...collect pollen or nectar, and he cannot help defend the hive because, being male, he has no sting (the sting is part of the female's egg-laying or...
Can bees bleed and how do they breathe - ...rl Hayden Bee Research Center in Tucson that involved "bleeding" bees to sample their body fluid, and he found that the fluid samples he extracted...
How is honey made out of flower nectar - ...de with honey tend to stay moist. This property of honey creates an unfavorable environment for bacteria and mold, drawing water from inside the...
Latest "Biology" Articles
Page# 1 2 (last added articles shown first)
How do bees collect nectar and what about buzz pollination (08/19/2010)
(...) Farmers have realized that bumble bees and other sonicating bees (bees that produce resonant vibrations) are extremely efficient as "buzz" pollinators, and imported bumble bees are now widely used as the primary pollinators for greenhouse tomatoes and other self-fertilizing fruit such as kiwis (also known as Chinese gooseberries), rape, field beans, raspberries, and currants.
To release the pollen in these flowers, bumble bees grasp the tubular anthers of the plant containing the pollen and rapidly vibrate the flight muscles of the thorax, causing the pollen to be dislodged. The pollen is carried on their hairs to the stigma of another plant, resulting in fertilization. (...)
How is honey made out of flower nectar (08/19/2010)
(...) It usually contains vitamins B6 and C, thiamin, niacin, riboflavin, and pantothenic acid, and it may have traces of essential minerals such as calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, zinc, and several different amino acids. It also contains antioxidants and is fat free.
Honey that has been adequately dehydrated can be safely stored for long periods of time. (...)
What is honeydew and how much do bees work for making honey (08/19/2010)
(...) They have to fly approximately fifty-five thousand miles back and forth from flowers to hive to gather enough nectar for that one jar, and to make one gallon of honey they have to fly the distance to the moon and back. How much honey a hive produces varies greatly, depending on the climate, location, weather, and general health of the bees, but the amount ranges from about fifty pounds to as much as two hundred pounds in a year.
How much honey is gathered in the United States every year?
About 150 million pounds of honey are obtained each year in the United States from commercial sources. (...)
When do bees leave their hive and what is swarming (08/19/2010)
(...)
What is swarming?
Swarming is a natural process by which a new colony is formed. When a hive becomes overcrowded, the worker bees instinctively know that it is time to swarm and to raise a new queen. Several large cells are created around fertilized eggs laid by the queen. (...)
Which bees migrate and how far can they fly (08/19/2010)
(...) Most foragers concentrate on food sources that are within about two miles from their nest, depending on the availability of local flowers, but when hives are located far from food sources, bees can fly longer distances. In a classic series of experiments to study how far bees can fly, honey bees are trained to feed from artificial flowers laced with a sugar solution. When the feeders are gradually moved away from the hive with feeding bees on them, observations by Karl von Frisch and his many students indicate that bees can travel up to twelve miles from the nest to obtain food. (...)
Which bees sting and how do they do it (08/19/2010)
(...)
What does it feel like to be stung by a bee?
Though the amount of venom in a honey bee sting is small, it can cause a great deal of discomfort and occasional harm. Some describe a bee sting as similar to a car door slamming on your fingers. Others describe it as feeling like touching a hot match. (...)
Why does a bee die after it has stung somebody (08/19/2010)
(...) G. Carlson described at least two species within the Oxytrigona genus that secrete caustic salivary substances made up of formic acids and other defensive chemicals, making their bite extremely uncomfortable. The stingless bee Trigona fulviventris marks potential predators with a chemical secretion that elicits additional bees to react defensively by buzzing, biting, and hair pulling. (...)
Can collecting venom from a bee kill it (08/19/2010)
(...)
How can you avoid being stung by a bee?
The best way not to be stung by a bee is to stay away from bee colonies, because bees are very reluctant to sting unless their nest is threatened or disturbed. For the most part, it is easy to avoid honey bee nests because they tend to live in managed colonies, which are typically large, white boxes. Occasionally, people will be surprised to find themselves near a bumblebee nest in the ground. (...)
How do bees survive difficult weather conditions (08/19/2010)
(...) L. Fahrenholz and colleagues at the University of Berlin found that if the central temperature falls below about 15 degrees Celsius (59 degrees Fahrenheit) and the peripheral temperature is even lower, the bees are in danger.
The colony is more stable in the winter because the queen stops laying eggs and there are no fragile larvae requiring constant care and feeding. (...)
Which animals hunt and eat bees (08/19/2010)
(...) Although they are drab in color, it is said that honeyguides attract the attention of a larger vertebrate predator of bees (such as a sun bear, a honey badger, or even a human) using a distinctive call. The bird will then hop around, call again, and then fly a short distance away and resume calling.
In this way, the honeyguide earned its name - it guides the larger mammal to a bee colony and dines on the leftovers after the mammal has endured the danger of opening the nest. (...)
How can I treat a sick bee colony (08/19/2010)
(...)
In the case of both infections, the larvae ingest the bacteria along with the brood food, and the bacteria then multiply rapidly in the gut of the larvae, causing death in a few days. Hive bees that clean the nest spread the infection, and even the honey becomes contaminated and spreads the disease.
What is dysentery for a bee?
Honey bees are very clean animals and usually only eliminate wastes when they fly outside of the colony. (...)
What differences are there between bee hives (08/19/2010)
(...) Bees entered a skep through a small door along the bottom edge of the basket, and due to the design, the beekeeper would have to destroy the entire colony when harvesting honey from these structures. Currently, skeps are purely decorative, and in many municipalities it is illegal to keep bees in skeps or in other non-traditional hives because they are impossible to inspect for bee health. Bee skeps inspired the iconic 1960s "beehive" hairdo. (...)
How can beekeepers stop the bees from swarming (08/19/2010)
(...) If the queen is killed accidentally, the workers may be able to rear a replacement queen from a newly laid egg.
Under some circumstances, the beekeeper may want to replace the queen with one that has particular characteristics, such as being a better egg layer, but if a new queen is released directly into a bee colony, the workers will treat her like a stranger and forcibly remove her from the colony and possibly kill her. Normally, the guard bees learn the odor of their own colony members and prevent bees from other colonies from entering the hive. (...)
Which bees mate and how do they attract a mate (08/17/2010)
(...) She mates multiple times shortly after she emerges from the pupal stage, storing up enough sperm to keep laying fertilized eggs for the rest of her life. The queen releases a pheromone that suppresses the development of the reproductive systems of the female worker bees.
This chemical keeps the workers from becoming reproductively viable, and the queen's eggs and larvae reinforce her message with chemicals that they pass along to the attending workers, signaling that the queen is providing the colony with an adequate supply of new workers. (...)
Queen bees mate with more drones at the same time (08/17/2010)
(...) The multi-father colonies were healthier, suffered from much less parasitism than the single-father colonies, and were twice as prolific, further confirmation of the benefits of genetic diversity.
How many eggs does a honey bee queen lay in a day?
A honey bee queen can lay fifteen hundred to three thousand eggs on a good day, and she can lay as many as half a million eggs in her two- or three-year lifetime. Her eggs are only reared to adulthood if there are enough workers to feed and incubate them. (...)
How bees choose their queen and how bees determine their gender (08/17/2010)
(...)
But if the queen has mated with a male who has a version of the sex-determining gene that is identical to hers, the fertilized eggs produced from his sperm that have two identical sex-determining genes will yield sterile male offspring, and these drones will be eaten by females in the colony since they cannot reproduce and therefore serve no purpose. Multiple matings reduce the proportion of sterile males that will be produced because not all mates will have a matching sex-determining gene.
How is the queen bee chosen?
There is no election process to become the new queen: she is not chosen, but presents the best traits among the queens that emerge. (...)
What do bees do during the day and the night (08/17/2010)
(...)
European honey bees can't see well enough to forage at night, so this is when some honey bee foragers typically sleep. Barrett Klein working with Tom Seeley determined that honey bees shift their foraging schedules depending on when resources are available, and this dictates to some degree when they can sleep.
Stefan Sauer and colleagues experimentally deprived foragers of sleep for a twelve-hour period in order to study their responses to the lack of sleep. (...)
Why do bees kill their queen after a certain time (08/17/2010)
(...) The sheet of wax that forms the base of the comb hangs vertically from the ceiling of the nest, and the cells fit together snugly and are arranged horizontally so their contents don't spill out, conserving space and maximizing storage capacity.
Stephen Pratt, now on the faculty at Arizona State University, explored the question of how a group of thousands of worker bees with limited information can proceed to build a pattern of comb that is best suited to the needs of the entire colony. What are the signals and cues that guide their collective decision making? After a swarm settles in a new nest site there is an initial surge of comb construction to provide cells for new brood and food storage. (...)
What happens in a bee hive round the year (08/17/2010)
(...)
By some time in the very early spring, the queen begins laying eggs (brood production), as many as several hundred each day as long as there are ample supplies of honey and pollen remaining in the nest's storage cells and there are environmental signals that fresh supplies will soon become available as the flowers begin to come into bloom and there are enough workers to keep the eggs warm. If food is scarce, her egg-laying activity level is reduced, creating an ongoing seasonal balance between the food supply and the numbers of eggs, larvae, and pupae.
Assuming the queen is healthy as the warm weather sets in, the bees will become very active, filling the storage cells with nectar, attending to the brood, and carrying out all the normal activities of the colony. (...)
How are bees attracted to flowers and which ones do they prefer (08/17/2010)
(...) fasciata with its dark brown body preferred shady locations.
Mason bees, Chalicodoma sicula, studied by Pat Willmer in an arid area of Israel preferred more dilute nectar, and in that habitat collecting adequate amounts of water from flowers was more vital even than the energy reward of nectar. There are certain flowers that bees learn to avoid. (...)
What are bees and how to distinguish them from wasps (08/15/2010)
(...) Both also have two sets of wings that fold back on top of one another when not in use and hook together during flight, and many species have similar coloration on their bodies.
Bees and social wasps, like hornets and yellow jackets, evolved from a common, solitary wasp ancestor that was dependent on other insects as a protein source for its developing larvae. Bees now rely only on pollen as a source of protein for their young. (...)
How many species of bees are there and are they different (08/15/2010)
(...) Then she lays an egg directly on the food supply, and the egg develops into an adult bee that repeats the cycle. When there are limited areas in the habitat that are suitable for nesting, hundreds or even thousands of solitary bees may nest in close proximity. Male solitary bees usually are short-lived, whether they mate once or several times. (...)
Where can bees live and which of them make honey (08/15/2010)
(...) There are some other related bees that also produce and store small amounts of honey, but only members of the genus Apis are considered true honey bees.
In Europe and America, the most common type of honey bee managed by beekeepers is the Western, or European, bee, which has many subspecies, or regional varieties, including the European dark bee, the Italian bee, the Carniolan honey bee, and the African bee. There are other species of tropical honey bees in Asia, including the red dwarf honey bee, the Eastern hive bee, and the common giant honey bee. (...)
How are drones related to queen bees (08/15/2010)
(...) The reality is that most drones die before getting a chance to mate. Unless a colony is preparing to swarm or has recently swarmed, it is relatively rare to find drones in the nest.
What is the role of the queen?
The queen is of great importance to the colony because she controls and regulates reproduction. (...)
What is the food of bees and how long do they live (08/15/2010)
(...)
In a remarkable experiment in published in 2003, evolutionary biologist Brendan Borrell surgically removed the tongues from over seventy orchid bees, a species that has a proboscis that is longer than its body. These bees typically feed from flowers with thinner nectar than most bees prefer, and Borrell's experiments showed that these bees could effi- ciently drink the thin nectar without a tongue, strongly suggesting that sucking plays a big role in their normal eating. Bees with tongues to lap the nectar in the usual bee-like manner did better with thicker solutions. (...)
Can bees bleed and how do they breathe (08/15/2010)
(...) Air enters through openings called spiracles on the sides of the bee body, and a network of tubes called trachea weave their way around organs and through tissues, allowing air to ooze throughout the bee's body. For larvae and inactive insects, this is how they breathe, taking in oxygen and expelling carbon dioxide through this simple system.
But when a bee flies, it needs more oxygen and its flight muscles move more air through its body by expanding air sacs that are part of the respiratory system and drawing air in more forcefully. (...)
Particularities about the external organs of honey bees (08/15/2010)
(...)
With rare exceptions, such as the male desert bee Perdita portalis, which has atrophied flight muscles and does not fly, bees are hardy fliers with large flight muscles and excellent maneuverability. Insect wings don't simply flap up and down, but rather the tips of the wings move in an oval pattern and turn over during each stroke. When the wing travels downward, the topside faces up, and then the wing rotates on an axis before the upstroke, creating a large amount of lift. (...)
How do bees feed one another and clean themselves (08/15/2010)
(...)
How do bees keep themselves clean?
Bees are very hygienic animals - they don't like to be dirty or dusty. Keeping their bodies clean is a good way to keep debris out of the colony, reducing the chance that bee nurseries will develop infections and decreasing the likelihood that food supplies will be contaminated. Moreover, if a honey bee's eyes or antennae are soiled, their sensors might not function correctly, and that would be detrimental to the entire colony unit because it might put them at risk. (...)
What is the waggle dance of honey bees (08/15/2010)
(...) First, the bees note the direction of the sun's azimuth in relation to North, being the 0 degree position. Based on this system, the sun rises in the East at approximately 90 degrees and sets in the West at about 270 degrees.
If you point toward the sun and then draw an imaginary line from the sun to the horizon, you can measure the direction of that point with a compass. (...)
How are bees capable of indicating the time of day (08/15/2010)
(...) Like the babies, the nursing workers do not exhibit circadian rhythms, but they acquire them as they age and integrate into the light-dark cycle of the nest. The older adult workers, the foragers, have strong cycles, based on the daily clock, that are tuned to cycles of pollen and nectar production. Guy Bloch and a team of researchers, using the honey bee genome sequence, identified a core group of "clock" genes that is responsible for circadian rhythms in honey bees. (...)
How are bees able to orient themselves and navigate (08/15/2010)
(...) This finding is particularly interesting, as it indicates that bees can assess their own knowledge and can act to increase the contents of their memories. Certainly, this selective learning behavior indicates a higher level of cognitive ability than might be expected in an insect.
Adrian Dyer and colleagues trained bees to recognize images of complex natural scenes and found that the bees were quite accurate in recognizing these landmarks and discriminating between a known scene and similar views that were introduced to confuse or distract them. (...)
Characteristics of the skin and body connection to the environment (03/13/2010)
(...) Modern cosmetology has the task of interacting with physiology in maintaining its good condition.
Macroscopic Characteristics
The skin is the largest, most extensive organ of our body. In fact, the average adult has about 170-200 square cm of skin with a weight that varies between 15 kg and 17 kg (obviously varying according to the subject's height and dimensions). (...)
What is the epidermis and what is it made of (03/13/2010)
(...) This mechanism is defined as epidermal cell turnover and is the basis of the continuous and incessant renewal of the epidermis.
Under the microscope the epidermis is an obvious superimposition of cell layers, each clearly different from the others, these being the maturing phases of the keratinocytes.
The basal layer is composed of a single line of more or less cylindrical cells that are densely packed and adherent to the basal membrane. (...)
Differences between the structure of head hair and body hair (03/13/2010)
(...) Lanugo hair
The lanugo is the thin and unpigmented hair present in the foetus before and just after birth, which is subsequently transformed into terminal hair (like that of an adult). Vellus hair is that present in women, adolescents, and also on the scalp of bald individuals. All three hair types have the same structure and even the same histological profile. (...)
Percentage of hairs found in the growth phases and our health (03/13/2010)
(...) Hair breakage alopecia
Dysfunctional alopecias are the most frequent forms, with both common baldness (androgenic alopecia) and temporary hair loss (telogen effluvium) belonging to this category. The latter condition very often occurs after giving birth. Destructive alopecias are those conditions of the scalp that may be either congenital or acquired. (...)
Sweat glands functions and their importance for health (03/13/2010)
(...) Therefore, strictly speaking, they should not be classified as sweat glands.
Eccrine Sweat Glands
Eccrine sweat glands are merocrinous glands in that they produce an aqueous solution of low density that does not appreciably cause disintegration of the epithelial cells. Their principle function is that of thermoregulation: sweating to allow the body to rid itself of excessive heat. (...)
Keratin filaments and basic protein containing histidine (03/13/2010)
(...) Of these intermediate filaments the most important examples are vimentin, present in the mesenchymal cells, GFAP acidic protein, which composes the glial filaments of the glial cells, the neurofilaments present in the neurones, desmin of the muscle cells, and the proteins of and the nuclear matrix, nuclear laminins A,B,C.
The polypeptide structures of all the intermediate filaments have a similar skeletal part composed of structural blocks of polypeptide subunits. The number of subunits varies between 1 and 30. (...)
The seven basic functions of human skin (03/13/2010)
(...) Finally, the skin plays the essential role of mechanical protection that we all appreciate every day when large or small mechanical traumas are cushioned by our skin.
Immunological Function
The first site of entry for foreign substances and bacteria is the skin. With the Langerhan cells the skin is able to identify these and to prepare a defence. (...)
Change in the extracellular portion of the receptor (12/19/2009)
(...) The rise in intracellular Ca culminates in the extrusion of GH-containing secretory granules. GH secretagogues bind to a separate G-protein-coupled receptor only recently identified. This receptor is linked through the heterotrimeric Gj protein to phospholipase C, resulting in phosphoinositol hydrolysis and stimulation of protein kinase C. (...)
Enhancement of hormone release (12/18/2009)
(...)
By contrast, studies questioning GHS putative influence on SRIH neurons are far less conclusive. Indeed, no change in SRIH release into HPB has been observed in both studies performed in sheep. GHS receptor expression was either barely or not detectable in neurons of the periventricular nucleus, the major source of SRIH released into HPB and no increase in Fos immunoreactivity was detected in these neurons following GHRP-6 injection. (...)
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