1. Ca and K condition the irritability of Pelagia both in regard to rhythmical contractions and general luminescence. If either ion is omitted from the solution conduction of stimuli for pulsations and luminescence does not occur, although local responses still persist. 2. When Mg is omitted from the solution, Pelagia shows hyper-irritability with respect to rhythmical contraction and general luminescence. This is referable to the unantagonized action of K and Ca ions. 3. Exposure to the carbon arc suppresses general luminescence, the effect depending upon the quantity of light i.e. intensity x time of exposure. 4. The luminescent material secreted by Pelagia is inactive in sea water, but when put into salt solutions is activated by some of them. The efficiency of the salts, measured by brightness of light, is in the following order: MgSO(4), K(2)SO(4), Na(3) citrate, KCl, BaCl(2), SrCl(2), CaCl(2), and LiCl while NaCl and MgCl(2) act as inhibitors. 5. Acidity inhibits the reaction, alkalinity promotes it. NH(4)OH in concentrations 0.27 N to 0.9 N causes luminescence for 10 minutes at 20 degrees . 6. The average temperature coefficient for the reaction of the luminescent substance when activated by ammonia or MgSO(4) is 2.18 for a temperature interval of 10 degrees C. 7. The luminescence reaction cannot be the result of cytolysis, because (a) raising the temperature of sea water in which luminous material is immersed does not cause luminescence, although sufficient to produce cytolysis. (b) The salt solutions used in our experiments to cause luminescence, do not act cytolytically on cells in general.
Eserine (2.5 × 10−5 M to 2.5 × 10−3 M) and atropine (2.5 × 10−3 M) produce a marked increase in the “spontaneous” activity of the ganglion cells of the ventral nerve cord of Callianassa californiensis. These substances have no appreciable effect on conduction characteristics of the giant fibers in the nerve cord, on the transmission across the synapse between the giant fibers and the nerves to the flexors of the telson, nor on denervated muscle. Nicotine (4 × 10−2 M), methylamine (1 × 10−3 M), triethylamine (4 × 10−3 M) and di-isopropyl fluorophosphate (DFP) (1.3 × 10−2 M) reversibly block synaptic transmission for varying periods of time.
Coordinated swimming movements in Yungia are not dependent upon the presence of the brain. The neuromuscular mechanism necessary for spontaneous movement and swimming is complete in the body of the animal apart from the brain. Normally this mechanism is set in motion by sensory stimulation arriving by way of the brain. The latter is a region of low threshold and acts as an amplifier by sending the impulses into a great number of channels. When the head is cut off these connections with the sensorium are broken, consequently peripheral stimulation does not have its usual effect. If, however, the motor nerves are stimulated directly as by mechanical stimulation of the median anterior region, then swimming movements result. Also if the threshold of the entire nervous mechanism is lowered by phenol or by an increase in the ion ratios See PDF for Equation and See PDF for Equation then again peripheral stimulation throws the neuromuscular mechanism into activity and swimming movements result.
ABSTRACT The immune system and placenta have a dynamic relationship across gestation to accommodate fetal growth and development. High-resolution characterization of this maternal- fetal interface is necessary to better understand the immunology of pregnancy and its complications. We developed a single-cell framework to simultaneously immuno-phenotype circulating, endovascular, and tissue-resident cells at the maternal-fetal interface throughout gestation, discriminating maternal and fetal contributions. Our data reveal distinct immune profiles across the endovascular and tissue compartments with tractable dynamics throughout gestation that respond to a systemic immune challenge in a gestationally-dependent manner. We uncover that mononuclear phagocytes and neutrophils drive the temporal immune composition of the placenta with remarkably diverse populations, including PD-L1-expressing subsets having compartmental and early gestational bias. Our approach and accompanying datasets provide a resource for additional investigations into gestational immunology and evoke a more significant role for the innate immune system in establishing the microenvironment of early pregnancy. Abstract Figure
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