Sexual Dimorphism Flashcards
In c. elegans, what happens when FEM-3 is expressed?
Hermaphrodites will behave as males, but it is not due to the anatomy of males vs. hermaphrodites, just to the neurons tuning, because males have a supplemental neuron, CEM, that when is ablated, it does not change the behavior of males regarding of avoidance and attraction to hermaphrodites.
In c. elegans, what happens when you put a hermaphrodite hormone on a gel?
Hermaphrodites avoid it and males are attracted by it. Avoidance is mediated by ASG, ASI, ASJ and ASK neurons.
What is the role of the MCM neuron in c. elegans?
MCM neuron is a male-specific neuron mediating male-specific learning. In the presence of mates, even if there is no food in salt, they will still be attracted to a high salt concentration because they need to mate. When it is removed, this behavior is significantly decreased.
In fruit flies, how is courtship initiated?
Males are emitting 11-cis vaccenyl acetate (cVA) and won’t mate with a fly smelling like that. Or67d receptor is the one reacting to cVA. When it is absent, males will not sense cVA and try to initiate mating even if it is not a female. Another receptor can help to do a checkup: Or47b which is sensitive to both males and females pheromones.
What is Fruitless?
It is a transcription factor in fruit flies downstream of the sex-determination pathway and is alternatively spliced in males and females.
What happens when male fruit flies do not express the fruM transcript, only the FruF in male-female courtship? In male-male courtship? In male chaining?
They do not try to court females.
They try to court males.
They start to do male chains.
What happens when female fruit flies do not express FruF, only FruM?
for their fertility? Their receptivity to males? Female-female courtship?
Fertility is decreased.
Female receptivity to males is decreased.
Female-female courtship is enhanced.
How did they showed the expression of fruitless genes throughout the nervous system of fruit flies?
Link the fru promoter to GAL4 cDNA. Add a UAS activated by GAL4 to Green Fluorescent Protein cDNA. Record fluorescence. Discovered that Fru is expressed in about 2000 cells which is 2% of the nervous system and it correlates with behavioral outputs.
What is the role of the fru gene in singing in fruit flies?
It controls the sine and the pulse song in males. Females do not have the same song (do not usually sing, only when thoracic ganglion is stimulated), even when they try to express the fruM gene in females. Therefore, the fru gene is not eliciting the singing.
In fruit flies, how did they discover what structure was eliciting singing in fruit flies?
Fru promoter linked to GAL4 cDNA, then UAS promoter linked to a light sensitive channel of the thoracic ganglion. When thoracic ganglion is activated using light, it elicits singing, so a headless fly can sing.
Whach flies are sensitive to songs to elicit mating? Males or females?
Females songs do not elicit mating with mute males, so females only respond to male songs (put a male and a female in the same cage and played songs from male, females and masculinized females and looked if you got mating). PS seems to be an important part of the song to elicit mating.
How does courtship occurs in mice? On what is it relying on?
Mice rely on pheromones for courting and it depends on the vomerol-nasal organ of the bain. If it is ablated, females will try to mount males, but also females. Males will mount males instead of being aggressive when VNO is blated.
In mice, what is the role of VMH neurons?
They are necessary for female mating, especially those expressing a progesterone receptor. Female sexual behavior is greatly reduced when they lack progesterone-receptor expressing VMH neurons while male sexual behavior is greatly reduced when they don’t have a lot of VMH progesterone-receptor expressing neurons expressed.
In humans, do we respond to pheromones?
Yes indeed. Males produce androgens and females estrogens. Females respond to AND with a lower HB, greater activity of the parasympathetic system and a higher body temperature.
In humans, how do brain regions react to pheromones?
Females have a greater blood flow in the brain when they are in contact with androgen while it happens for males in contact with estrogens. It may correlates with sexual orientation because brains of homosexual man react more to androgens than estrogens. However, it was really high concentrations.
