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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  • October 7, 2015
  • 08:00 AM

Twin Sons Of Different Mothers…… Or Fathers

by Mark Lasbury in As Many Exceptions As Rules

Can a pregnant woman get pregnant? Sounds like a riddle, but really it is superfetation. Getting pregnant in two successive cycles and having twins with different fathers really creates a problem in defining what twins actually are. Twins don’t have to be conceived at the same time, born at the same time, have the same father, or even be of the same “race.”... Read more »

Claas, M., Timmermans, A., & Bruinse, H. (2010) Case report: a black and white twin. Journal of Perinatology, 30(6), 434-436. DOI: 10.1038/jp.2009.156  

  • September 30, 2015
  • 07:55 AM

Twins of Different Seasons

by Mark Lasbury in As Many Exceptions As Rules

Twins are born near the same time, that’s one of the things that makes them twins. But do they have to be born close to one another? The record is twins born 104 days apart. The key is to get the twins past 25 weeks so the lungs will be mature enough, but if one twin is delivered, the second might be subjected to delayed interval delivery to give the lungs longer to grow.... Read more »

Reinhard, J., Reichenbach, L., Ernst, T., Reitter, A., Antwerpen, I., Herrmann, E., Schlösser, R., & Louwen, F. (2012) Delayed interval delivery in twin and triplet pregnancies: 6 years of experience in one perinatal center. Journal of Perinatal Medicine, 40(5). DOI: 10.1515/jpm-2011-0267  

Padilla-Iserte, P., Vila-Vives, J., Ferri, B., Gómez-Portero, R., Diago, V., & Perales-Marín, A. (2014) Delayed Interval Delivery of the Second Twin: Obstetric Management, Neonatal Outcomes, and 2-Year Follow-Up. The Journal of Obstetrics and Gynecology of India, 64(5), 344-348. DOI: 10.1007/s13224-014-0544-1  

Lewi, L., Devlieger, R., De Catte, L., & Deprest, J. (2014) Growth discordance. Best Practice , 28(2), 295-303. DOI: 10.1016/j.bpobgyn.2013.12.003  

  • September 23, 2015
  • 08:10 AM

Twins Versus Siblings, Where’s The Line?

by Mark Lasbury in As Many Exceptions As Rules

What makes two babies twins? Do they have to look similar; be born at the same time; be conceived at the same time? Twins of different races give us idea just how genetics can play out in siblings and how complex the control of skin pigmentation, hair and eye color and hair texture can be.... Read more »

Duffy DL, Montgomery GW, Chen W, Zhao ZZ, Le L, James MR, Hayward NK, Martin NG, & Sturm RA. (2007) A three-single-nucleotide polymorphism haplotype in intron 1 of OCA2 explains most human eye-color variation. American journal of human genetics, 80(2), 241-52. PMID: 17236130  

Maroñas, O., Phillips, C., Söchtig, J., Gomez-Tato, A., Cruz, R., Alvarez-Dios, J., de Cal, M., Ruiz, Y., Fondevila, M., Carracedo, �.... (2014) Development of a forensic skin colour predictive test. Forensic Science International: Genetics, 34-44. DOI: 10.1016/j.fsigen.2014.06.017  

  • September 16, 2015
  • 08:00 AM

You And Mom Are Never Apart

by Mark Lasbury in As Many Exceptions As Rules

You have more in common with your mom than you might think. Microchimerism means that an individual has cells with two different genetic profiles; some are yours and some are your mom’s. They live in your body for more than 40 years and can affect your health. Some of your cells moved into mom too – and they may help her live longer and avoid breast cancer.... Read more »

Cirello V, Rizzo R, Crippa M, Campi I, Bortolotti D, Bolzani S, Colombo C, Vannucchi G, Maffini MA, de Liso F.... (2015) Fetal cell microchimerism: a protective role in autoimmune thyroid diseases. European journal of endocrinology / European Federation of Endocrine Societies, 173(1), 111-8. PMID: 25916393  

Kamper-Jorgensen, M., Hjalgrim, H., Andersen, A., Gadi, V., & Tjonneland, A. (2013) Male microchimerism and survival among women. International Journal of Epidemiology, 43(1), 168-173. DOI: 10.1093/ije/dyt230  

Eun, J., Guthrie, K., Zirpoli, G., & Gadi, V. (2013) In Situ Breast Cancer and Microchimerism. Scientific Reports. DOI: 10.1038/srep02192  

  • September 9, 2015
  • 08:15 AM

When You’re Not Just Yourself

by Mark Lasbury in As Many Exceptions As Rules

How would you react if you were told that the DNA testing shows that you are not your child’s parent or your parents’ child? Demand another test? – you bet. But wait, you or your parent might be a tetragametic chimeric, carrying around DNA from another person in your body. You might have had a dizygotic twin that you didn’t know about!... Read more »

Yu, N., Kruskall, M., Yunis, J., Knoll, J., Uhl, L., Alosco, S., Ohashi, M., Clavijo, O., Husain, Z., Yunis, E.... (2002) Disputed Maternity Leading to Identification of Tetragametic Chimerism. New England Journal of Medicine, 346(20), 1545-1552. DOI: 10.1056/NEJMoa013452  

Lee, H., Yoon, S., Ko, J., Seong, M., Park, S., Choi, J., & Oh, S. (2014) Monochorionic dizygotic twins with discordant sex and confined blood chimerism. European Journal of Pediatrics, 173(9), 1249-1252. DOI: 10.1007/s00431-014-2312-8  

  • September 2, 2015
  • 08:15 AM

Don’t Disrespect The Dizygotic

by Mark Lasbury in As Many Exceptions As Rules

Spies try to look boring, but in reality they are much more interesting than the average Joe. So it is with dizygotic twins; monozygotic twins (“identical”) get all the glory, but they’re just a split egg, any female can do it. But dizygotic twins – certain families have more, Nigerian women have more, older women have more, taller women and overweight women have more. Now there’s something that looks boring but must be interesting.... Read more »

Simpson, C., Robertson, D., Al-Musawi, S., Heath, D., McNatty, K., Ritter, L., Mottershead, D., Gilchrist, R., Harrison, C., & Stanton, P. (2014) Aberrant GDF9 Expression and Activation Are Associated With Common Human Ovarian Disorders. The Journal of Clinical Endocrinology , 99(4). DOI: 10.1210/jc.2013-3949  

Palmer, J., Zhao, Z., Hoekstra, C., Hayward, N., Webb, P., Whiteman, D., Martin, N., Boomsma, D., Duffy, D., & Montgomery, G. (2006) Novel Variants in Growth Differentiation Factor 9 in Mothers of Dizygotic Twins. The Journal of Clinical Endocrinology , 91(11), 4713-4716. DOI: 10.1210/jc.2006-0970  

Hoekstra, C., Willemsen, G., van Beijsterveldt, C., Lambalk, C., Montgomery, G., & Boomsma, D. (2010) Body composition, smoking, and spontaneous dizygotic twinning. Fertility and Sterility, 93(3), 885-893. DOI: 10.1016/j.fertnstert.2008.10.012  

Groeneveld, E., Lambers, M., Stakelbeek, M., Mooij, T., van den Belt-Dusebout, A., Heymans, M., Schats, R., Hompes, P., Hoek, A., Burger, C.... (2012) Factors associated with dizygotic twinning after IVF treatment with double embryo transfer. Human Reproduction, 27(10), 2966-2970. DOI: 10.1093/humrep/des258  

  • August 26, 2015
  • 08:45 AM

Twins That Share More Than Clothes

by Mark Lasbury in As Many Exceptions As Rules

Not every pair of monozygotic twins have the same chromosomes. Mosaic twins can be boy and girl, yet both babies come from a single zygote. The strange part is that the tests we run to prevent IVF problems may actually contribute to mosaic twinning. And have you heard of polar body twins? They’re ½ identical twins!... Read more »

Souter, V., Parisi, M., Nyholt, D., Kapur, R., Henders, A., Opheim, K., Gunther, D., Mitchell, M., Glass, I., & Montgomery, G. (2006) A case of true hermaphroditism reveals an unusual mechanism of twinning. Human Genetics, 121(2), 179-185. DOI: 10.1007/s00439-006-0279-x  

Tachon, G., Lefort, G., Puechberty, J., Schneider, A., Jeandel, C., Boulot, P., Prodhomme, O., Meyer, P., Taviaux, S., Touitou, I.... (2014) Discordant sex in monozygotic XXY/XX twins: a case report. Human Reproduction, 29(12), 2814-2820. DOI: 10.1093/humrep/deu275  

  • August 19, 2015
  • 06:30 AM

Epigenetics And The Evil Twin

by Mark Lasbury in As Many Exceptions As Rules

Monozygotic twins share 100% of their genes. Does this make them identical? Not by a long shot. Epigenetics is the field of study that looks at how environment can change how something looks or works without changing its genes. Is epigenetics responsible for evil twin syndrome in American television?... Read more »

Spannhoff, A., Kim, Y., Raynal, N., Gharibyan, V., Su, M., Zhou, Y., Li, J., Castellano, S., Sbardella, G., Issa, J.... (2011) Histone deacetylase inhibitor activity in royal jelly might facilitate caste switching in bees. EMBO reports, 12(3), 238-243. DOI: 10.1038/embor.2011.9  

Kahn, H., Graff, M., Stein, A., Zybert, P., McKeague, I., & Lumey, L. (2008) A fingerprint characteristic associated with the early prenatal environment. American Journal of Human Biology, 20(1), 59-65. DOI: 10.1002/ajhb.20672  

Zwijnenburg, P., Meijers-Heijboer, H., & Boomsma, D. (2010) Identical but not the same: The value of discordant monozygotic twins in genetic research. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics. DOI: 10.1002/ajmg.b.31091  

Thacker, D., Gruber, P., Weinberg, P., & Cohen, M. (2009) Heterotaxy Syndrome with Mirror Image Anomalies in Identical Twins. Congenital Heart Disease, 4(1), 50-53. DOI: 10.1111/j.1747-0803.2008.00229.x  

  • August 12, 2015
  • 08:15 AM

When A Twin Vanishes

by Mark Lasbury in As Many Exceptions As Rules

The things that can happen to twins in the womb before they can be born are bizarre. Some get absorbed by their sibling and some just vanish. Two conjoined twins might grow differently and one may becomes a parasite – one boy just had a second face coming out of his chest that could smile, blink and cry. Even scarier - many of you are harboring a twin right now.... Read more »

Navaei AA, Habibi Z, Moradi E, & Nejat F. (2015) Parasitic rachipagus twins; report of two cases. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery, 31(6), 1001-3. PMID: 25715843  

Daga, B., Chaudhary, V., Ingle, A., Dhamangaokar, V., Jadhav, D., & Kulkarni, P. (2009) Double fetus-in-fetu: CT scan diagnosis in an adult. Indian Journal of Radiology and Imaging, 19(3), 216. DOI: 10.4103/0971-3026.54890  

Zahed, L., Oreibi, G., Darwiche, N., & Mitri, F. (2004) Potential trisomy 21 misdiagnosis by amniocentesis due to a resorbed twin. Prenatal Diagnosis, 24(12), 1013-1013. DOI: 10.1002/pd.918  

Lakhoo, K., Ringo, Y., Sillo, T., & Drake, D. (2012) Parasitic twin within spina bifida. African Journal of Paediatric Surgery, 9(3), 240. DOI: 10.4103/0189-6725.104728  

  • August 5, 2015
  • 08:10 AM

One Egg, Two People, A Bunch of Reasons

by Mark Lasbury in As Many Exceptions As Rules

Man has been cloning himself for thousands of years. They’re called monozygotic twins. But how it occurs naturally is still a mystery. Identical twinning isn’t common, but is increased by in vitro fertilization techniques. Maybe this will give clues as to why one embryo splits. And if it doesn’t split completely – conjoined twins.... Read more »

  • July 29, 2015
  • 10:30 AM

It’s 11 PM, Do You Know Where Your Organs Are?

by Mark Lasbury in As Many Exceptions As Rules

It’s a miracle that a human body ever works like it’s supposed to. So many things can go wrong and there’s so few ways for things to be right. Ever hear of a defect called situs ambiguus? It’s a big problem. And what’s more, when something like transposition of the great arteries occurs, it’s only a second defect that keeps the patients alive.... Read more »

  • July 22, 2015
  • 08:10 AM

Organs Don’t Always Follow The Plan

by Mark Lasbury in As Many Exceptions As Rules

Do you know where your heart is located? Do you know exactly? Maybe not. It isn’t where most people think it is, and in some people it’s on the opposite side. Situs inversus is a mirror imaging of internal organs, and it’s caused by a faulty motorboat rotor on the embryo.... Read more »

  • July 15, 2015
  • 08:25 AM

Ovaries March To A Different Drummer

by Mark Lasbury in As Many Exceptions As Rules

A woman’s right ovary kicks her left ovary’s behind. It puts out more hormones and more pregnancies result from right-sided ovulations than from left-sided ovulations. And there’s none of this right-left stuff you’ve been taught, the ovaries don’t have to take turns ovulating every other month. In fact, a study showed that the best chance for pregnancy is if the ovulation pattern is left-left-right over a three-cycle interval. ... Read more »

Zheng, X., O’Connor, J., Huchzermeyer, F., Wang, X., Wang, Y., Wang, M., & Zhou, Z. (2013) Preservation of ovarian follicles reveals early evolution of avian reproductive behaviour. Nature, 495(7442), 507-511. DOI: 10.1038/nature11985  

  • July 8, 2015
  • 08:30 AM

What the Heck Are Those Doing There?

by Mark Lasbury in As Many Exceptions As Rules

The neuroendocrine system has lots of exceptions, and this includes the male testes. Just why are they housed outside the main body cavities where they are vulnerable to all sorts of dangers, including your siblings’ kicks? You may think you know, but you probably have only part of the answer. Why is one bigger than the other and why do some animals only have one? ... Read more »

Bogaert, A. (1997) Genital asymmetry in men. Human Reproduction, 12(1), 68-72. DOI: 10.1093/humrep/12.1.68  

  • July 1, 2015
  • 08:30 AM

Thinking Asymmetrically About Hormones

by Mark Lasbury in As Many Exceptions As Rules

Your endocrine glands are stimulated or suppressed by hormones. They in turn dump hormones into the blood. Blood goes everywhere equally. So why is your left adrenal gland bigger than your right? And why is the size difference larger in domesticated foxes as opposed to wild foxes? For that matter, why is the size of the right lobe of your thyroid gland depend on which hand you use to write!?... Read more »

Trut LN, Prasolova LA, Kharlamova AV, & Plyusnina IZ. (2002) Directional left-sided asymmetry of adrenals in experimentally domesticated animals. Bulletin of experimental biology and medicine, 133(5), 506-9. PMID: 12420075  

Hojaij, F., Vanderlei, F., Plopper, C., Rodrigues, C., Jácomo, A., Cernea, C., Oliveira, L., Marchi, L., & Brandão, L. (2011) Parathyroid gland anatomical distribution and relation to anthropometric and demographic parameters: a cadaveric study. Anatomical Science International, 86(4), 204-212. DOI: 10.1007/s12565-011-0111-0  

  • June 24, 2015
  • 08:00 AM

The CPU In Your Head

by Mark Lasbury in As Many Exceptions As Rules

It’s hard to believe, but part of your brain – the part that controls your body systems – actually comes from your mouth! What’s more, that same part of the brain talks to cells in your lungs that can smell what you breathe in and may have something to do with Sudden Infant Death Syndrome.... Read more »

Gu, X., Karp, P., Brody, S., Pierce, R., Welsh, M., Holtzman, M., & Ben-Shahar, Y. (2014) Chemosensory Functions for Pulmonary Neuroendocrine Cells. American Journal of Respiratory Cell and Molecular Biology, 50(3), 637-646. DOI: 10.1165/rcmb.2013-0199OC  

  • June 19, 2015
  • 06:30 PM

Fibonacci Numbers And Odd Lungs

by Mark Lasbury in As Many Exceptions As Rules

Most people think that because they have a pair of lungs, they must be symmetrical – but they’re far from it. The Fibonacci sequence has a lot to do with structural asymmetries in the lungs. On the other hand, some animals have only one lung, some have three lungs, and some have no lungs at all.... Read more »

Wilkinson M, Kok PJ, Ahmed F, & Gower DJ. (2014) Caecilita Wake . Zootaxa, 383-8. PMID: 24871732  

Bickford, D., Iskandar, D., & Barlian, A. (2008) A lungless frog discovered on Borneo. Current Biology, 18(9). DOI: 10.1016/j.cub.2008.03.010  

Goldberger AL, West BJ, Dresselhaus T, & Bhargava V. (1985) Bronchial asymmetry and Fibonacci scaling. Experientia, 41(12), 1537-8. PMID: 4076397  

  • June 10, 2015
  • 08:00 AM

Everybody Is Just A Little Twisted

by Mark Lasbury in As Many Exceptions As Rules

You may have your head on straight, but your brain is still twisted. Everyone’s is. The symmetry of the brain is not absolute and the two halves are shaped differently, this results in your brain torquing (not twerking) inside your skull. The reasons are many, but one is gender: boy brains and girl brains really are different!... Read more »

Maller, J., Anderson, R., Thomson, R., Rosenfeld, J., Daskalakis, Z., & Fitzgerald, P. (2015) Occipital bending (Yakovlevian torque) in bipolar depression. Psychiatry Research: Neuroimaging, 231(1), 8-14. DOI: 10.1016/j.pscychresns.2014.11.008  

Maller, J., Thomson, R., Rosenfeld, J., Anderson, R., Daskalakis, Z., & Fitzgerald, P. (2014) Occipital bending in depression. Brain, 137(6), 1830-1837. DOI: 10.1093/brain/awu072  

Mock, J., Zadina, J., Corey, D., Cohen, J., Lemen, L., & Foundas, A. (2012) Atypical Brain Torque in Boys With Developmental Stuttering. Developmental Neuropsychology, 37(5), 434-452. DOI: 10.1080/87565641.2012.661816  

Witelson, S., Kigar, D., & Harvey, T. (1999) The exceptional brain of Albert Einstein. The Lancet, 353(9170), 2149-2153. DOI: 10.1016/S0140-6736(98)10327-6  

  • June 3, 2015
  • 08:15 AM

Left-Handers Have Prettier Brains

by Mark Lasbury in As Many Exceptions As Rules

Take a quick look at the human brain and it seems very symmetrical. Well, it’s not. Which hand you use can help determine just how symmetrical your brain actually is, and for some people that’s really important – they were born with only half a brain!... Read more »

Rogers, L., Zucca, P., & Vallortigara, G. (2004) Advantages of having a lateralized brain. Proceedings of the Royal Society B: Biological Sciences, 271(Suppl_6). DOI: 10.1098/rsbl.2004.0200  

Muckli, L., Naumer, M., & Singer, W. (2009) Bilateral visual field maps in a patient with only one hemisphere. Proceedings of the National Academy of Sciences, 106(31), 13034-13039. DOI: 10.1073/pnas.0809688106  

  • May 27, 2015
  • 08:00 AM

Hermit Houses And Fiddler Claws

by Mark Lasbury in As Many Exceptions As Rules

Fiddler crabs are an evolutionary marvel. Their major claw is huge, it plays a role in mate selection, but not just in the way you’d think.
Some species are right-clawed and some can have the major claw on either side, but if they lose one and grow it back, the major claw might switch sides! The new major claw isn’t as good for fighting, so he fakes being strong and tries to win without fighting.
... Read more »

Backwell, P., Matsumasa, M., Double, M., Roberts, A., Murai, M., Keogh, J., & Jennions, M. (2007) What are the consequences of being left-clawed in a predominantly right-clawed fiddler crab?. Proceedings of the Royal Society B: Biological Sciences, 274(1626), 2723-2729. DOI: 10.1098/rspb.2007.0666  

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