Cloning and functional expression of rat eag2, a new member of the ether-à-go-go family of potassium channels and comparison of its distribution with that of eag1.

A second mammalian gene for the ether-à-go-go (eag) potassium channel has been cloned from the rat, and its predicted protein sequence is 70% identical to that of rat ether-à-go-go1 with a further 10% conservatively replaced residues. The rat eag2 mRNA was predominantly expressed in neural tissue and was not detected in adult skeletal, cardiac, or smooth muscle. Within the brain, its distribution overlaps that of rat ether-à-go-go1 in specific regions within the cortex and olfactory bulb, but was differentially distributed in other locations, being scanty within the cerebellum, and most notably present in the thalamus, inferior colliculus, and certain brainstem nuclei. Heterologous expression of rat eag2 in HEK-293 cells gave rise to a voltage-gated, noninactivating potassium current, active at the cells' resting potential and blocked by low nanomolar concentrations of cytosolic calcium. Thus, in neurones, this current is likely to impart a modulation in membrane conductance, which is sensitively responsive to resting internal calcium, and levels of electrical activity.

Elevation of intracellular calcium by muscarinic receptor activation induces a block of voltage-activated rat ether-à-go-go channels in a stably transfected cell line.

We have studied the properties of r-eag voltage-activated potassium channels in a stably transfected human embryonic kidney cell line. It was found that r-eag channels are rapidly and reversibly inhibited by a rise in intracellular calcium from 30 to 300 nM. The inhibition does not appear to depend on the activity of calcium-dependent kinases and phosphatases. The effect of calcium on r-eag channel activity was studied in inside-out membrane patches. Calcium inhibited r-eag channel activity with a mean IC50 of 67 nM. Activation of muscarinic receptors, generating calcium oscillations in the transfected cells, induced a synchronous inhibition of r-eag mediated outward currents. This shows that calcium can mediate r-eag current inhibition following muscarinic receptor activation. The data indicate that r-eag channels are calcium-inhibitable voltage-activated potassium channels.

Discovery of Entomophaga maimaiga in North American gypsy moth, Lymantria dispar.

An entomopathogenic fungus, Entomophaga maimaiga, was found causing an extensive epizootic in outbreak populations of the gypsy moth, Lymantria dispar, throughout many forested and residential areas of the northeastern United States. This is the first recognized occurrence of this or any entomophthoralean fungus in North American gypsy moths, and its appearance was coincident with an abnormally wet spring. Most fungal-infected gypsy moth larvae were killed in mass during the fourth and fifth stadium and were characteristically found clinging to the trunks of trees with their heads pointed downward. The fungus produces thick-walled resistant resting spores within dried gypsy moth cadavers and infectious conidia when freshly killed larvae are held in a wet environment. The morphology and development of the fungus are described. The fungus appears to have had its origin in Japan, and the current epizootic may have resulted from the survival and inapparent spread of an early introduction in 1910-1911.

Orientation behavior and effect of experience and laboratory rearing on responses ofCotesia melanoscela (Ratzeburg) (Hymenoptera: Braconidae) to gypsy moth silk kairomone.

Cotesia melanoscela responds the same way to the silk of its host, gypsy moth larvae,Lymantria dispar L., whether or not it has previously been exposed to hosts. Parasites maintained in the laboratory for six or 25 generations also responded similarly, suggesting that orientation behavior is not modified by laboratory rearing. Details of silk-related orientation behavior were analyzed by tracing paths of female parasites when on or off silk-covered substrates. Females made 31 ° average turns every 0.5 cm whether or not they were examining silk. They tended to turn back onto a silked area when encountering a border, and their speed of movement when not examining silk was about three times higher than when examining silk.

Gypsy moth (Lymantria dispar L.) attraction to disparlure enantiomers and the olefin precursor in the People's Republic of China.

Pheromone traps baited with disparlure,cis-7,8-epoxy-2-methyl-octadecane, captured males ofLymantria dispar, the gypsy moth, at two widely separated locations in the People's Republic of China. The (+) enantiomer of disparlure attracted significantly more males than the racemate; addition of olefin reduced captures. The duration of the flight period was longer (eight weeks) and peaked earlier near Beijing than farther north near Dunhua (five weeks).

Dufour's gland: source of sex pheromone in a hymenopterous parasitoid.

Females of Apanteles melanoscelus and Apanteles liparidis produce a sex pheromone in Dufour's gland of their reproductive system. Males of both species exhibit premating behavior when in contact with filter paper smears of the gland of their respective females.