As Many Exceptions As Rules

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Exceptions to natural and biological rules are used to increase interest in biology. Recent studies, and not so recent studies, are described in order to demonstrate amazing organisms and practices. Core concepts of biology are emphasized, with side trips into the research of topics that give insight into the evolution and interelatedness of all life.

Mark Lasbury
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  • July 23, 2014
  • 08:00 AM
  • 19 views

Let's Get Loud

by Mark Lasbury in As Many Exceptions As Rules

Loud noises are common in nature. New research is giving clues as to how and why animals make such noise. A new study investigates the reasons that howler monkeys howl. Protection and marking territory are main reasons, including for protection of infants or feeding areas.

A slightly older study notes that blue whale song has become lower in pitch since the whaling ban. The authors suggest that the reason for this may be that males don’t have to sing as loud (higher frequencies are loud........ Read more »

  • July 16, 2014
  • 08:05 AM
  • 114 views

East To West And Back Again

by Mark Lasbury in As Many Exceptions As Rules

Sunflowers were named by Linnaeus for their round shape and bright color that reminded him of the sun, not because they follow the sun. But they do seem to turn to face the sun each day. A new review has looked at the molecular mechanisms that control the movement of the apex of the plant. But questions remain – how does the plant turn back to the east at night? Why is it that the flower turns but the leaves do not? Why does the movement stop when the flower matures?... Read more »

  • July 9, 2014
  • 08:15 AM
  • 88 views

What’s So Repelling About Repellents?

by Mark Lasbury in As Many Exceptions As Rules

It’s amazing that even though citronella and DEET reduce mosquito bites, we have very little idea of how they work. New research is showing that DEET interacts with olfactory receptors so that chemical attractants are still sensed, but their interpretations are confused. You are still there, but you pretty disappear as far as the mosquito is concerned. Other research shows that one of the co-receptors for olfactory receptors is responsible not only for DEET activity, but also for mosquito ........ Read more »

  • July 2, 2014
  • 08:25 AM
  • 126 views

How Do Mosquitoes Find You?

by Mark Lasbury in As Many Exceptions As Rules

Spend much time outside in the summer and you will have to deal with mosquitoes. The mechanisms that females use to find a blood meal are becoming better understood. New research shows how the proboscis probes for a blood vessel, perhaps using the TRPA1 heat sensing ion channel as a signal for nearby blood.

Once they feed, females lay eggs. New research indicates that they actually prefer water that contains the dead larvae of similar mosquitoes, dead from predators. The presence of predator........ Read more »

  • June 25, 2014
  • 08:15 AM
  • 103 views

They Can See The Blood Running Through You

by Mark Lasbury in As Many Exceptions As Rules

Vampire bats sense heat via pit organs in their nose-leaves, but they find their victims by sight, smell and echolocation. New research shows that an alternatively spliced version of the capsaicin receptor TRPV1 is responsible for the heat sensing, but what do they use it for? Their teeth are so short that they must find blood vessels close to the surface – shallow vessels give off more heat than do deep vessels or skin where there is no large vessel.

Vampire bats occasionally feed on ........ Read more »

Patel R, Ispoglou S, & Apostolakis S. (2014) Desmoteplase as a potential treatment for cerebral ischaemia. Expert opinion on investigational drugs, 23(6), 865-73. PMID: 24766516  

Gracheva EO, Cordero-Morales JF, González-Carcacía JA, Ingolia NT, Manno C, Aranguren CI, Weissman JS, & Julius D. (2011) Ganglion-specific splicing of TRPV1 underlies infrared sensation in vampire bats. Nature, 476(7358), 88-91. PMID: 21814281  

  • June 18, 2014
  • 08:15 AM
  • 105 views

Sneaking Up On A Snake

by Mark Lasbury in As Many Exceptions As Rules

Snakes have several ways of finding prey. Some use sight; many use taste and smell via the veromonasal organ. New research has identified the sensitivity of snake hearing, even though they don’t have an outer or middle ear. They sense vibrations by placing their lower jaws on the ground and the vibrations are transduced by the cochlea they do possess. Finally, new research is showing how the heat-sensing pits of pit vipers work. They use a mutated version of the thermosensor and noxious ch........ Read more »

Gracheva EO, Ingolia NT, Kelly YM, Cordero-Morales JF, Hollopeter G, Chesler AT, Sánchez EE, Perez JC, Weissman JS, & Julius D. (2010) Molecular basis of infrared detection by snakes. Nature, 464(7291), 1006-11. PMID: 20228791  

  • June 11, 2014
  • 08:15 AM
  • 113 views

What Cold Really Looks Like

by Mark Lasbury in As Many Exceptions As Rules

It is undetermined to what degree TRPA1 cold sensors actually sense cold or act in thermoregulation. On the other hand, we know that this ion channel is crucial for other aspects of physiology. Recent studies indicate that TRPA1 is crucial for the phototransductive initiation of melanin production in melanocytes. This has led to a new field of experimental biology called optogenetics, using expressed phototransduction proteins to switch on and off genes with light.... Read more »

  • June 4, 2014
  • 08:15 AM
  • 149 views

Sometimes, Cold Hurts

by Mark Lasbury in As Many Exceptions As Rules

Capsaicin receptors (TRPV1) help detect heat and cool the body. Cool receptors (TRPM8) detect cold temperatures and help warm the body. But what about TRPA1 receptors? New research shows that while their function in intense cold sensing may be species specific, they do function in pain production, for heat, cold, and chemicals. So if they are so good at producing pain, why would a spider have a TRPA1 blocker in its venom?... Read more »

de Oliveira, C., Garami, A., Lehto, S., Pakai, E., Tekus, V., Pohoczky, K., Youngblood, B., Wang, W., Kort, M., Kym, P.... (2014) Transient Receptor Potential Channel Ankyrin-1 Is Not a Cold Sensor for Autonomic Thermoregulation in Rodents. Journal of Neuroscience, 34(13), 4445-4452. DOI: 10.1523/JNEUROSCI.5387-13.2014  

Benemei S, Fusi C, Trevisan G, & Geppetti P. (2014) The TRPA1 channel in migraine mechanism and treatment. British journal of pharmacology, 171(10), 2552-67. PMID: 24206166  

Gui J, Liu B, Cao G, Lipchik AM, Perez M, Dekan Z, Mobli M, Daly NL, Alewood PF, Parker LL.... (2014) A tarantula-venom peptide antagonizes the TRPA1 nociceptor ion channel by binding to the S1-S4 gating domain. Current biology : CB, 24(5), 473-83. PMID: 24530065  

  • May 28, 2014
  • 08:00 AM
  • 129 views

Cold Receptors Come In From The Cold

by Mark Lasbury in As Many Exceptions As Rules

TRPM8 is a cool sensing ion channel. It acts in thermoregulation and nasal resistance, but new research is showing some impressive functions outside of temperature sensing. Sperm maturation is inhibited by TRPM8 signaling until the egg is reached and CRISP4 levels rise to the point of TRPM8 inhibition. Then TRPV1 can initiate the acrosome reaction.

In addition, morphine action and opiate withdrawal have related to TRPM8. Morphine in the presence of a TRPM8 inhibitor is much less analgesic. O........ Read more »

Gibbs GM, Orta G, Reddy T, Koppers AJ, Martínez-López P, de la Vega-Beltràn JL, Lo JC, Veldhuis N, Jamsai D, McIntyre P.... (2011) Cysteine-rich secretory protein 4 is an inhibitor of transient receptor potential M8 with a role in establishing sperm function. Proceedings of the National Academy of Sciences of the United States of America, 108(17), 7034-9. PMID: 21482758  

Shapovalov G, Gkika D, Devilliers M, Kondratskyi A, Gordienko D, Busserolles J, Bokhobza A, Eschalier A, Skryma R, & Prevarskaya N. (2013) Opiates modulate thermosensation by internalizing cold receptor TRPM8. Cell reports, 4(3), 504-15. PMID: 23911290  

  • May 21, 2014
  • 08:20 AM
  • 152 views

The Cold Cure All

by Mark Lasbury in As Many Exceptions As Rules

Having a cold is no fun. But exercise is excellent for decreasing nasal resistance so you aren’t so stuffed up. Vicks VapoRub has been a staple for children’s colds since the 1890’s, but it wasn’t until 2008 that research showed that the menthol effect on TRPM8 does not have any effect at all on nasal resistance and the brain just interprets TRPM8 cool sensing as a signal that your nose is open and passing air freely.

However, Vicks is effective as an anti-tussive age........ Read more »

Lindemann J, Tsakiropoulou E, Scheithauer MO, Konstantinidis I, & Wiesmiller KM. (2008) Impact of menthol inhalation on nasal mucosal temperature and nasal patency. American journal of rhinology, 22(4), 402-5. PMID: 18702906  

Buday T, Brozmanova M, Biringerova Z, Gavliakova S, Poliacek I, Calkovsky V, Shetthalli MV, & Plevkova J. (2012) Modulation of cough response by sensory inputs from the nose - role of trigeminal TRPA1 versus TRPM8 channels. Cough (London, England), 8(1), 11. PMID: 23199233  

Plevkova J, Kollarik M, Poliacek I, Brozmanova M, Surdenikova L, Tatar M, Mori N, & Canning BJ. (2013) The role of trigeminal nasal TRPM8-expressing afferent neurons in the antitussive effects of menthol. Journal of applied physiology (Bethesda, Md. : 1985), 115(2), 268-74. PMID: 23640596  

  • May 14, 2014
  • 08:25 AM
  • 184 views

Cold Keeps You Warm

by Mark Lasbury in As Many Exceptions As Rules

Sensing cool temperatures is just as important for thermoregulation as is sensing warm temperatures. But the mechanisms are different. New research is showing that the TRPM8 cool sensing ion channel is important for thermoregulation, but we do not know yet how cool tmepratures open the channel. What is clear is that activation of TRPM8 on adipose tissue can increase UCP expression and increase mitochondria number. This increases BAT activity and makes WAT more like BAT to increase heat productio........ Read more »

Pogorzala LA, Mishra SK, & Hoon MA. (2013) The cellular code for mammalian thermosensation. The Journal of neuroscience : the official journal of the Society for Neuroscience, 33(13), 5533-41. PMID: 23536068  

Rossato M, Granzotto M, Macchi V, Porzionato A, Petrelli L, Calcagno A, Vencato J, De Stefani D, Silvestrin V, Rizzuto R.... (2014) Human white adipocytes express the cold receptor TRPM8 which activation induces UCP1 expression, mitochondrial activation and heat production. Molecular and cellular endocrinology, 383(1-2), 137-46. PMID: 24342393  

  • May 7, 2014
  • 08:05 AM
  • 226 views

Everybody Wants To Be Cool

by Mark Lasbury in As Many Exceptions As Rules

Capsaicin activates TRPV1 ion channels. Why do we care? Because that’s makes our mouth burn when we eat spicy food. But TRPV1 also senses noxious heat. On the other end of the scale, there are also ion channels for sensing cool and cold temperatures. But the TRPM8 cool receptor is also activated by menthol. This is much of the reason for menthol being added to cigarettes.

New research shows that menthol in cigarettes adds to the cytotoxicity of tobacco smoke, while menthol alone causes ........ Read more »

Noriyasu A, Konishi T, Mochizuki S, Sakurai K, Tanaike Y, Matsuyama K, Uezu K, & Kawano T. (2013) Menthol-enhanced cytotoxicity of cigarette smoke demonstrated in two bioassay models. Tobacco induced diseases, 11(1), 18. PMID: 24001273  

Brody AL, Mukhin AG, La Charite J, Ta K, Farahi J, Sugar CA, Mamoun MS, Vellios E, Archie M, Kozman M.... (2013) Up-regulation of nicotinic acetylcholine receptors in menthol cigarette smokers. The international journal of neuropsychopharmacology / official scientific journal of the Collegium Internationale Neuropsychopharmacologicum (CINP), 16(5), 957-66. PMID: 23171716  

Ashoor A, Nordman JC, Veltri D, Yang KH, Al Kury L, Shuba Y, Mahgoub M, Howarth FC, Sadek B, Shehu A.... (2013) Menthol binding and inhibition of α7-nicotinic acetylcholine receptors. PloS one, 8(7). PMID: 23935840  

  • April 30, 2014
  • 08:15 AM
  • 202 views

Capsaicin Receptors – Matters Of Life And Death

by Mark Lasbury in As Many Exceptions As Rules

The functions of the chili pepper (capsaicin) receptor TRPV1 have been expanded in the recent years. Mechanisms of hearing involve TRPV1, but the functional range is narrow, as new research is showing that excess noise and ototoxic drugs are TRPV1 agonists and lead to abberant expression and function – hearing damage and tinnitus.

In the realm of cancer, capsaicin is showing two faces as well. TRPV1 agonists can induce apoptosis, reactive oxygen species-mediated damage, and cell cycle ........ Read more »

  • April 23, 2014
  • 08:25 AM
  • 264 views

Chili Peppers Run Hot And Cold

by Mark Lasbury in As Many Exceptions As Rules

Hot peppers are hot because their capsaicin binds to the TRPV1 heat sensing ion channel. Agonists of TRPV1 can lead to a hypothermia, while antagonists result in a hyperthermia. Normally these would be poor outcomes, but there are particular instances that new researchs are showing to be beneficial. Brown adipose tissue is promoted by TRPV1 agonists, and studies are showing that capsaicin can hinder formation of white adipose tissue. Likewise, agonists of TRPV1 can induce a protective hypothermi........ Read more »

Yoneshiro T, Aita S, Matsushita M, Kayahara T, Kameya T, Kawai Y, Iwanaga T, & Saito M. (2013) Recruited brown adipose tissue as an antiobesity agent in humans. The Journal of clinical investigation, 123(8), 3404-8. PMID: 23867622  

Feng Z, Hai-Ning Y, Xiao-Man C, Zun-Chen W, Sheng-Rong S, & Das UN. (2014) Effect of yellow capsicum extract on proliferation and differentiation of 3T3-L1 preadipocytes. Nutrition (Burbank, Los Angeles County, Calif.), 30(3), 319-25. PMID: 24296036  

Muzzi M, Felici R, Cavone L, Gerace E, Minassi A, Appendino G, Moroni F, & Chiarugi A. (2012) Ischemic neuroprotection by TRPV1 receptor-induced hypothermia. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism, 32(6), 978-82. PMID: 22434066  

  • April 16, 2014
  • 08:05 AM
  • 214 views

Using Pain To Stop Pain

by Mark Lasbury in As Many Exceptions As Rules

Chronic pain can involve TRPV1 pathways, yet traditional TRPV1 antagonists cannot be used due to incidence of hyperthermia. New research has identified new routes of administration, new agonists and new allosteric functions that will make TRPV1 a viable target for chronic, acute, and cancer-mediated pains. Alternative mechanisms, such as counter irritants and acupuncture are also gaining in evidence for mechaisms that involve TRPV1 signaling pathways... Read more »

Andreev YA, Kozlov SA, Korolkova YV, Dyachenko IA, Bondarenko DA, Skobtsov DI, Murashev AN, Kotova PD, Rogachevskaja OA, Kabanova NV.... (2013) Polypeptide modulators of TRPV1 produce analgesia without hyperthermia. Marine drugs, 11(12), 5100-15. PMID: 24351908  

Lee MG, Huh BK, Choi SS, Lee DK, Lim BG, & Lee M. (2012) The effect of epidural resiniferatoxin in the neuropathic pain rat model. Pain physician, 15(4), 287-96. PMID: 22828682  

Kelly S, Chapman RJ, Woodhams S, Sagar DR, Turner J, Burston JJ, Bullock C, Paton K, Huang J, Wong A.... (2013) Increased function of pronociceptive TRPV1 at the level of the joint in a rat model of osteoarthritis pain. Annals of the rheumatic diseases. PMID: 24152419  

  • April 9, 2014
  • 08:10 AM
  • 314 views

Capsaicin – Adding To Or Taking Your Pain

by Mark Lasbury in As Many Exceptions As Rules

Activation of TRPV1 ion channels can lead to potentiation of noxious stimuli while activation of multiple nociceptors can result in sensitization of TRPV1. Both situations can lead to hyperalgesia or allodynia. New research is highlighting the role of TRPV1 in burning mouth syndrome, both in its hyperalgesic and allodynic symptoms, as well as in its treatment. ... Read more »

Borsani E, Majorana A, Cocchi MA, Conti G, Bonadeo S, Padovani A, Lauria G, Bardellini E, Rezzani R, & Rodella LF. (2013) Epithelial expression of vanilloid and cannabinoid receptors: a potential role in burning mouth syndrome pathogenesis. Histology and histopathology. PMID: 24190005  

Silvestre FJ, Silvestre-Rangil J, Tamarit-Santafé C, & Bautista D. (2012) Application of a capsaicin rinse in the treatment of burning mouth syndrome. Medicina oral, patologia oral y cirugia bucal, 17(1). PMID: 21743415  

Alpizar YA, Boonen B, Gees M, Sanchez A, Nilius B, Voets T, & Talavera K. (2014) Allyl isothiocyanate sensitizes TRPV1 to heat stimulation. Pflugers Archiv : European journal of physiology, 466(3), 507-15. PMID: 23955021  

  • April 2, 2014
  • 08:10 AM
  • 263 views

It’s Not Just Chili Peppers That Are Hot

by Mark Lasbury in As Many Exceptions As Rules

The same receptor that senses capsaicin and regulates body temperature is also involved in osmoregulation. New studies indicate that a variant of TRPV1 in the magnocellular neurosecretory cells work in osmoregulation but do not bind capsaicin or sense heat. Another study has elucidated that TRPV1 acts only in hypertonicty; it senses cell shrinkage. Swelling due to hypotonicity is sensed by TRPV4. Together, these form a crucial part of the osmoregulatory system.... Read more »

Holland C, van Drunen C, Denyer J, Smart K, Segboer C, Terreehorst I, Newlands A, Beerahee M, Fokkens W, & Tsitoura DC. (2013) Inhibition of capsaicin-driven nasal hyper-reactivity by SB-705498, a TRPV1 antagonist. British journal of clinical pharmacology. PMID: 23909699  

Chung G, Im ST, Kim YH, Jung SJ, Rhyu MR, & Oh SB. (2014) Activation of transient receptor potential ankyrin 1 by eugenol. Neuroscience, 153-60. PMID: 24384226  

Alpizar YA, Boonen B, Gees M, Sanchez A, Nilius B, Voets T, & Talavera K. (2014) Allyl isothiocyanate sensitizes TRPV1 to heat stimulation. Pflugers Archiv : European journal of physiology, 466(3), 507-15. PMID: 23955021  

  • March 26, 2014
  • 08:15 AM
  • 261 views

Naked Mole Rats Don’t Feel The Burn

by Mark Lasbury in As Many Exceptions As Rules

Recent evidence is shedding light on the various mechanisms through which naked mole rats avoid the pain associated with capsaicin and other activators of TRPV1. The mole rats have deep dorsal horn connections that modulate TRPV1nociceptove signaling after capsaicin ingestion. They also suppress neural firing of pain neurons through a 2 amino acid change in the Nav1.7 sodium channel downstream of TRPV1. But they also have low levels or lack completely the substance P neurotransmitter that works ........ Read more »

Smith ES, Omerbašić D, Lechner SG, Anirudhan G, Lapatsina L, & Lewin GR. (2011) The molecular basis of acid insensitivity in the African naked mole-rat. Science (New York, N.Y.), 334(6062), 1557-60. PMID: 22174253  

Park TJ, Lu Y, Jüttner R, Smith ES, Hu J, Brand A, Wetzel C, Milenkovic N, Erdmann B, Heppenstall PA.... (2008) Selective inflammatory pain insensitivity in the African naked mole-rat (Heterocephalus glaber). PLoS biology, 6(1). PMID: 18232734  

  • March 19, 2014
  • 08:05 AM
  • 297 views

Maybe We Do Taste The Burn

by Mark Lasbury in As Many Exceptions As Rules

Common perception is that capsaicin is a pain sensation, not a taste. But recent research is showing that capsaicin, while perhaps not tasted on its own, does influence what is tasted. It is know that capsaicin can suppress sweet and bitter tastes. A 2010 study indicated that TRPV1 expressing neurons are expressed in circumvallate taste buds, and can be co-expressed with sweet or bitter taste receptors. Other work shows that alterations in sweet, bitter, and metallic tastes do occur in TRPV1 kno........ Read more »

  • March 12, 2014
  • 08:00 AM
  • 210 views

Are Chilies Spicy, Hot, Or Piquant?

by Mark Lasbury in As Many Exceptions As Rules

Why do we say that spicy foods are “hot?” The painful sensation and sting of chili peppers in the mouth is likened to the burn from a heated source. This is much closer to the truth than just a verbal similarity. The capsaicin of chili peppers serve to protect the seeds from killing by Fusarium fungi; the evolutionary pressure of fungal pathogens drives higher capsaicin levels. Other studies indicate that plant growth conditions also affect capsaicin levels. Higher growth temperatur........ Read more »

Tewksbury JJ, Reagan KM, Machnicki NJ, Carlo TA, Haak DC, Peñaloza AL, & Levey DJ. (2008) Evolutionary ecology of pungency in wild chilies. Proceedings of the National Academy of Sciences of the United States of America, 105(33), 11808-11. PMID: 18695236  

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