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You’ve probably had someone tell you, at some point in your life, that the sense of smell is the sense most tightly linked to memory. Now, scientists have found that at least for mosquitoes, the sense of smell is also linked to the ability of their sperm to swim. The research was published in February in the journal Proceedings of the National Academy of Sciences.
Female mosquitoes use their sense of smell to find people (so they can suck their blood) and suitable sites to lay their eggs. As you might suspect, the majority of the smell-sensing machinery in mosquitoes is in their head, but scientists have found molecules called odorant receptors, which are needed to detect volatiles (ie: smelly stuff), in other body parts. Researchers Laurence Zwiebel and colleagues studied the mosquito that transmits malaria, Anopheles gambiae, to find out what these other odorant receptors were doing. Specifically, they wanted to know if they were doing anything to the sperm, because apparently that’s how they roll.... Read more »
Pitts RJ, Liu C, Zhou X, Malpartida JC, & Zwiebel LJ. (2014) Odorant receptor-mediated sperm activation in disease vector mosquitoes. Proceedings of the National Academy of Sciences of the United States of America, 111(7), 2566-71. PMID: 24550284
Communication is essential to any successful relationship, and insect relationships are no different. And, as in human relationships, much of this communication is non-verbal. Chemical cues in the form of pheromones help females of many insect species decide when to mate who to make with and, when the deed is done, other chemicals let them know it’s time to stop dating and get serious about making some babies.
Joachim Ruther and colleagues at the University of Regensburg in Germany published an article in 2010 that describes how the switch from “let’s do it!” to “I gotta find a place to lay my eggs” happens in the jewel wasp Nasonia vitripennis. Now, Dr. Ruther and Theresa Hammerl have found the exact chemicals that make this happen.... Read more »
Ruther J, & Hammerl T. (2014) An oral male courtship pheromone terminates the response of Nasonia vitripennis females to the male-produced sex attractant. Journal of chemical ecology, 40(1), 56-62. PMID: 24369389
Ruther, J., Thal, K., Blaul, B., & Steiner, S. (2010) Behavioural switch in the sex pheromone response of Nasonia vitripennis females is linked to receptivity signalling. Animal Behaviour, 80(6), 1035-1040. DOI: 10.1016/j.anbehav.2010.09.008
You probably don’t need science to tell you that when you’re stressed out you’re not likely to be in the mood. But can stress cause physical damage to your reproductive cells? A study published this month in the Journal of Sexual Medicine suggests that it just might.... Read more »
Hou G, Xiong W, Wang M, Chen X, & Yuan TF. (2014) Chronic stress influences sexual motivation and causes damage to testicular cells in male rats. The journal of sexual medicine, 11(3), 653-63. PMID: 24373463
Almeida SA, Kempinas WG, & Lamano Carvalho TL. (2000) Sexual behavior and fertility of male rats submitted to prolonged immobilization-induced stress. Brazilian journal of medical and biological research , 33(9), 1105-9. PMID: 10973146
he girth of a mouse penis bone depends on the stiffness of the competition. That’s what Leigh Simmons and Renée Firman at the University of Western Australia found after several generations of experimental evolution in mice. Over the course of the experiment, male mice developed thicker penis bones (or bacula, if you want to be scientific about it) when females were allowed to mate with multiple males. The study was published in the January issue of the journal Evolution.... Read more »
Simmons LW, & Firman RC. (2014) Experimental evidence for the evolution of the Mammalian baculum by sexual selection. Evolution; international journal of organic evolution, 68(1), 276-83. PMID: 24372607
Imagine an STD that made you extra eager for sex. Oh, and it makes you sterile.
This STD exists—in insects.
Researchers working in a lab that studies field crickets came into work one day only to find, much to their dismay I imagine, that their colony had been infected with a virus. But, as they say in science, when life gives you lemons, thoroughly analyze them and publish the results.
Shelley Adamo and colleagues at Dalhousie University recently published an article in the Journal of Experimental Biology describing this accidental infection and how it made their crickets not only ignore being sick, but actually made them super randy.... Read more »
Adamo SA, Kovalko I, Easy RH, & Stoltz D. (2014) A viral aphrodisiac in the cricket Gryllus texensis. The Journal of experimental biology. PMID: 24625650
Burand JP, Tan W, Kim W, Nojima S, & Roelofs W. (2005) Infection with the insect virus Hz-2v alters mating behavior and pheromone production in female Helicoverpa zea moths. Journal of insect science (Online), 6. PMID: 16299596
Toxic. It’s a bad word, right? If something is toxic, or poison, it will kill you. Period. Arsenic? Poison. Water? Not poison. See? Easy! How about this one: sugar. Well, if we’re to believe everything we read in the media, sugar is one of the worst poisons there is. And you’re killing yourself with it RIGHT NOW (don’t deny it. I see that double caramel latte you’re sipping).... Read more »
Ruff JS, Suchy AK, Hugentobler SA, Sosa MM, Schwartz BL, Morrison LC, Gieng SH, Shigenaga MK, & Potts WK. (2013) Human-relevant levels of added sugar consumption increase female mortality and lower male fitness in mice. Nature communications, 2245. PMID: 23941916
Scientists know a lot about fly sex. Maybe too much. We know how male fruit flies woo their mates. We've picked apart the seminal fluid to study all of the molecules in it. We know what happens to the female after sex:-and how it can even make her sick.
And we know what happens to a female fly's poop after sex.
Before, during, after...science doesn't know the meaning of TMI. We want to know everything.... Read more »
Apger-McGlaughon J, & Wolfner MF. (2013) Post-mating change in excretion by mated Drosophila melanogaster females is a long-term response that depends on sex peptide and sperm. Journal of insect physiology. PMID: 23891750
Cognigni P, Bailey AP, & Miguel-Aliaga I. (2011) Enteric neurons and systemic signals couple nutritional and reproductive status with intestinal homeostasis. Cell metabolism, 13(1), 92-104. PMID: 21195352
Evolution makes penises take on crazy shapes. But can male genital shape actually drive the evolution of two separate species? Researchers in Australia looked at populations of a millipede species with divergent genital shape to address this question. ... Read more »
Wojcieszek JM, & Simmons LW. (2013) Divergence in genital morphology may contribute to mechanical reproductive isolation in a millipede. Ecology and evolution, 3(2), 334-43. PMID: 23467632
Most people probably think of tastebuds as existing only on their tongues, but did you know there are taste buds in testes? It’s true. Sort of. They aren’t exactly like the taste buds in your mouth. Male germ cells–the cells that are destined to become sperm–have molecules on them that can detect bitter tastes.
... Read more »
Xu J, Cao J, Iguchi N, Riethmacher D, & Huang L. (2013) Functional characterization of bitter-taste receptors expressed in mammalian testis. Molecular human reproduction, 19(1), 17-28. PMID: 22983952
All kinds of things go into a woman’s vagina. Some are friendly (like sperm and vaginal microbes), and some are very bad (STDs). The immune system in the vagina has to be able to tell the difference and react appropriately. As you can imagine, the system isn’t perfect and sometimes things go terribly wrong.
An article published earlier this month in the journal Fronteirs in Immunology (available online for free) reviewed the current state of knowledge of the vaginal immune system. The paper was written by Gary Clark and Danny Schust of the University of Wisconsin. I just wanted to highlight some of the points from the article here and talk about some interesting issues related to vaginal immunity.... Read more »
Clark GF, & Schust DJ. (2013) Manifestations of immune tolerance in the human female reproductive tract. Frontiers in immunology, 26. PMID: 23407606
The study, published this month in PLoS One, was conducted by Adrienn Uzsák and Coby Schal at North Carolina University…and some lovely German cockroaches. They found that when female cockroaches socialize, they produce eggs faster. And they don’t even have to socialize with other roaches! It just has to be an insect of roughly the same size and shape.... Read more »
Uzsák A, & Schal C. (2013) Sensory Cues Involved in Social Facilitation of Reproduction in Blattella germanica Females. PloS one, 8(2). PMID: 23405195
Kate Middleton might love being pregnant, but for the average woman it can be confusing and scary. Every day we learn about some new thing that, if you do it when you’re pregnant, can totally screw up your kid. By this point, pretty much everyone knows that you shouldn’t smoke or drink during pregnancy. Even sushi can be dangerous. But then you get a lot of contradictory information: drinking a little bit is OK…or is it?
So, in case you’re pregnant or thinking about becoming pregnant, here’s some more news to totally freak you out. You can even affect your child’s chances of developing autism or obesity while you’re pregnant.... Read more »
Surén P, Roth C, Bresnahan M, Haugen M, Hornig M, Hirtz D, Lie KK, Lipkin WI, Magnus P, Reichborn-Kjennerud T.... (2013) Association between maternal use of folic acid supplements and risk of autism spectrum disorders in children. JAMA : the journal of the American Medical Association, 309(6), 570-7. PMID: 23403681
Symonds ME, Mendez MA, Meltzer HM, Koletzko B, Godfrey K, Forsyth S, & van der Beek EM. (2013) Early Life Nutritional Programming of Obesity: Mother-Child Cohort Studies. Annals of nutrition , 62(2), 137-145. PMID: 23392264
Bringhenti I, Moraes-Teixeira JA, Cunha MR, Ornellas F, Mandarim-de-Lacerda CA, & Aguila MB. (2013) Maternal Obesity during the Preconception and Early Life Periods Alters Pancreatic Development in Early and Adult Life in Male Mouse Offspring. PloS one, 8(1). PMID: 23383269
Pike KC, Inskip HM, Robinson SM, Cooper C, Godfrey KM, Roberts G, Lucas JS, & the Southampton Women's Survey Study Group. (2013) The relationship between maternal adiposity and infant weight gain, and childhood wheeze and atopy. Thorax. PMID: 23291350
Goats could potentially transmit a dangerous parasite, Toxoplasma gondii, in their semen, according to research by Flaviana Wanderley and colleagues in Brazil. Well...who cares? Why should scientists devote research dollars and time to purposely giving goats STDs, just to see if they can?
Like with so many other apparently bizarre research projects, the answer is: it's the economy, stupid!
Goat farming is very important in many countries, including Brazil and India. Goats are reared for both meat and milk, and can be much more economical to raise than sheep or cows. As of 2005, there were 9.1 million goats being raised in Brazil--that's more than the population of Switzerland! The parasite Toxoplasma gondii is extremely harmful to goats, causing congenital diseases and even abortions. So, you can see how preventing the transmission of this parasite in their livestock might be of importance to goat farmers.
Previous research found that Toxoplasma can be found in goat semen. They also found that experimental insemination of female goats with artificially contaminated semen can transmit the disease, called toxoplasmosis. But only two strains (G1 and G2) of Toxoplasma have been tested so far in this way. The G1 strain was able to infect about a third of females via the semen. G2 infected 100% of females. G2 infections also resulted in "embryonic resorption" (spontaneous abortion). The third strain, G3, was tested in the current study.... Read more »
Wanderley F, Porto WJ, Câmara D, Cruz NL, Feitosa BC, Freire R, Moraes E, & Mota R. (2013) EXPERIMENTAL VAGINAL INFECTION OF GOATS WITH SEMEN CONTAMINATED WITH THE "CPG" STRAIN OF Toxoplasma gondii. The Journal of parasitology. PMID: 23391103
Octopus sperm is sneaky. It starts off all innocent and normal looking, while it’s sitting there in the testes waiting to go to bat. Then, once in the female, the acrosome reaction begins and the sperm shows its true, screwy self.
And I do mean screwy. Seriously. It looks like a screw.... Read more »
Li Z, Zhu JQ, & Yang WX. (2010) Acrosome reaction in Octopus tankahkeei induced by calcium ionophore A23187 and a possible role of the acrosomal screw. Micron (Oxford, England : 1993), 41(1), 39-46. PMID: 19729317
Tasmanian devils are rapidly face-cancering themselves to extinction. If we don’t do something soon, those weird little down-under devils will be gone forever. Enter: electroejaculation. Yes, it is exactly what it sounds like. An electric probe is inserted into the rectum of an anesthetized male animal (or human; this is also used for some infertility treatments). The probe stimulates the prostate and induces the animal to, um, provide a sample. A paper published this August in the journal Reproduction, Fertility, and Development, presented an evaluation of this technique for use on male tasmanian devils. The hope is that by collecting and saving devil sperm, it can be used in the future for artificial insemination. And given the risk of contracting face cancer during sex, artificial insemination might be the way to go for devil ladies.... Read more »
Keeley T, Harris M, McGreevy PD, Hudson D, & O'Brien JK. (2012) Development and evaluation of electroejaculation techniques in the Tasmanian devil (Sarcophilus harrisii). Reproduction, fertility, and development, 24(7), 1008-18. PMID: 22935162
Keeley T, McGreevy PD, & O'Brien JK. (2012) The effects of season and devil facial tumour disease on the reproductive physiology of the male Tasmanian devil (Sarcophilus harrisii). Reproduction, fertility, and development, 24(7), 999-1007. PMID: 22935161
Are you grossed out by blue cheese? (I’m not, but I know many who are). Does that blue-green marbling of delicious fungus kind of make you gag? Well, this little factoid probably won’t help: there may be sex going on in that cheese.
Until pretty recently, a big chunk of fungal species were thought to reproduce without sex–until people really started to look. It turns out, there’s a lot more sex going on in the fungal world (on the down-low) than people thought. And that includes fungi that are used to make delicious blue cheese. Jeanne Ropars and colleagues in France, the home of Roquefort cheese, looked at the genomes of the mold species used in this particular cheese to see what kind of funny business was going on in their snack of choice. They found much more diversity than could be explained by asexual reproduction. And even more telling, the genes used by fungi to find mating partners have been kept intact and functional by evolution, meaning there’s probably some sex going on. The results were published November 21 in the online journal PLoS One.... Read more »
Ropars J, Dupont J, Fontanillas E, Rodríguez de la Vega RC, Malagnac F, Coton M, Giraud T, & López-Villavicencio M. (2012) Sex in Cheese: Evidence for Sexuality in the Fungus Penicillium roqueforti. PloS one, 7(11). PMID: 23185400
Alexei Maklakov and colleagues in Sweden recently performed an experiment to see what effect sexual harassment (ie: constant, unwanted efforts by males to gain sex) had on the mutation rate of fruit flies in the next generation. The results were published online last week in the Proceedings of the Royal Society (see citation below).... Read more »
Maklakov AA, Immler S, Løvlie H, Flis I, & Friberg U. (2013) The effect of sexual harassment on lethal mutation rate in female Drosophila melanogaster. Proceedings. Biological sciences / The Royal Society, 280(1750), 20121874. PMID: 23173200
Since I missed last week’s sperm post, I thought I’d make up for it by writing about everyone’s favorite kind of sperm: giant. Who makes giant sperm? It’s not who you might think. The giants of the animal kingdom–whales, elephants–make sperm that are very similar to that of men and mice. Tiny. It’s the little guys who make the biggest sperm. In fact, as I’ve pointed out before, the largest sperm of all (and no, this is not relative to body size) are over 5cm long and made by a fruit fly called Drosophila bifurca.
But who else makes giant sperm? Well, it’s mainly arthropods, like the fruit fly, but also some flatworms and mollusks (maybe they’re compensating?), and some other unlikely suspects as well. For example: this tiny aquatic invertebrate known as Psuedocandona marchica, an animal without a Wikipedia page. These animals, which look like little aquatic blobs, belong to a class called the ostracods. Ostracods are a type of crustacean which are very tiny (0.1 to 30mm). But what they lack in size, they make up for in kinky sex lives.... Read more »
Yamada S, & Matzke-Karasz R. (2012) How is a giant sperm ejaculated? Anatomy and function of the sperm pump, or "Zenker organ," in Pseudocandona marchica (Crustacea, Ostracoda, Candonidae). Die Naturwissenschaften, 99(7), 523-35. PMID: 22684272
Joly D, Bressac C, Jaillard D, Lachaise D, & Lemullois M. (2003) The sperm roller: a modified testicular duct linked to giant sperm transport within the male reproductive tract. Journal of structural biology, 142(3), 348-55. PMID: 12781661
You may have seen this paper about scientists turning stem cells into fertile eggs hyped in media today (for example, this article at NPR). And of course, it deserves the hype. This is certainly a big breakthrough in stem cell research–especially induced pluripotent stem (iPS) cell research. iPS cells are similar to embryonic stem cells, except that they can be made out of any cell in the body.... Read more »
Katsuhiko Hayashi, Sugako Ogushi, Kazuki Kurimoto, So Shimamoto, Hiroshi Ohta, & Mitinori Saitou. (2012) Offspring from Oocytes Derived from in Vitro Primordial Germ Cell–Like Cells in Mice. Science. DOI: 10.1126/science.1226889
Hayashi K, Ohta H, Kurimoto K, Aramaki S, & Saitou M. (2011) Reconstitution of the mouse germ cell specification pathway in culture by pluripotent stem cells. Cell, 146(4), 519-32. PMID: 21820164
Sperm are pretty cool. Some are tiny, some are huge. Some have hooks, some crawl, and some can’t actually fertilize an egg. But all of them are awesome products of evolution. That’s why I want to start a collection of posts (let’s say weekly, and see how that goes) dedicated to quirky sperm. For the first post, a relatively recent paper (about a year old) on naked mole rat sperm.
... Read more »
van der Horst G, Maree L, Kotzé SH, & O'Riain MJ. (2011) Sperm structure and motility in the eusocial naked mole-rat, Heterocephalus glaber: a case of degenerative orthogenesis in the absence of sperm competition?. BMC evolutionary biology, 351. PMID: 22142177
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