Statistical measurement of signal transmission in the central nervous system of the crayfish

Summary Transmission of nerve signals in the crayfish brain was studied by means of the transfer function derived from input-output analysis with random stimulation. The transfer function was measured in the form of frequency-response-function and represented by Bode plot. Two classes of the frequency-response-functions were discriminated, corresponding to two types of response patterns evoked by the constant frequency stimuli. The first type had the characteristics of a band pass filter similar to an underdamped resonant circuit. The second one had the characteristics of a phase lag circuit, occasionally, with additional small positive or negative peak at almost the same frequency as the resonance of the first type. A few possibilities for the resonance and the phase lag mechanisms were discussed.     

Pacemaker Potentials for the Periodic Burst Discharge in the Heart Ganglion of a Stomatopod, Squilla oratoria

From somata of the pacemaker neurons in the Squilla heart ganglion, pacemaker potentials for the spontaneous periodic burst discharge are recorded with intracellular electrodes. The electrical activity is composed of slow potentials and superimposed spikes, and is divided into four types, which are: (a) "mammalian heart" type, (b) "slow generator" type, (c) "slow grower" type, and (d) "slow deficient" type. Since axons which are far from the somata do not produce slow potentials, the soma and dendrites must be where the slow potentials are generated. Hyperpolarization impedes generation of the slow potential, showing that it is an electrically excitable response. Membrane impedance increases on depolarization. Brief hyperpolarizing current can abolish the plateau but brief tetanic inhibitory fiber stimulation is more effective for the abolition. A single stimulus to the axon evokes the slow potential when the stimulus is applied some time after a previous burst. Repetitive stimuli to the axon are more effective in eliciting the slow potential, but the depolarization is not maintained on continuous stimulation. Synchronization of the slow potential among neurons is achieved by: (a) the electrotonic connections, with periodic change in resistance of the soma membrane, (b) active spread of the slow potential, and (c) synchronization through spikes.     

Blunted febrile response to intravenous endotoxin in starved rats

The effects of fasting on the febrile responses to intravenous injection of bacterial lipopolysaccharide (LPS; endotoxin) of Escherichia coli were investigated in rats. Ad libitum-fed rats (C) produced a biphasic fever with an increase in the temperature difference between brown adipose tissue and colon and shivering activity (SA). Measurement by a direct calorimeter showed no particular changes in heat loss. Rats starved for 4 days (F4) responded to intravenous LPS with a monophasic fever accompanied by an increase in SA only. However the maximal rise in colonic temperature (Tco) did not differ from C rats. Subsequent 2-day fasting reduced SA and the maximal fever height. Endogenous pyrogen (EP) injected intravenously produced a prompt rise in Tco followed by prolonged hyperthermia in C rats. In the F4 rats, there was no such sustained rise in Tco as a result of intravenous EP. The response in Tco to intravenous prostaglandin E2 (PGE2) was the same in fed and starved rats. The administration of LPS, EP, and PGE2 into the lateral ventricle evoked a similar extent of hyperthermia in C and F4 rats. Because the second phase of fever has been shown to occur after pyrogens are translated into a febrile stimulus within the blood-brain barrier, it is assumed that the functional changes of the blood-brain barrier such as in the permeability of pyrogens or in the sensitivity of pyrogen receptors resulted in the absence of the second phase of fever in starved rats.     

Necessity of IgE antibodies and mast cells for manifestation of resistance against larval Haemaphysalis longicornis ticks in mice

Genetically mast cell-deficient WBB6F1-W/Wv mice showed an apparent defect in manifestation of the resistance against larval Haemaphysalis longicornis ticks, but their serum IgE levels increased more than 100-fold after the second tick infestation. Immune sera obtained from the WBB6F1-W/Wv mice were adoptively transferred to the other WBB6F1-W/Wv mice which had received intracutaneous injections of WBB6F1-+/+ mouse-derived cultured mast cells. Because the resistance against ticks was detectable only when both mast cells and IgE antibodies were available, immediate hypersensitivity reaction appeared to have a physiologic role in the manifestation of the resistance against H. longicornis ticks.     

cDNA cloning and structure of mouse putative Ah receptor.

Mouse cDNA clones for a putative Ah receptor have been isolated from a cDNA library of mRNA from Hepa-1 cells by an oligonucleotide probe produced by PCR with a pair of primers which was synthesized according to the reported N-terminal sequence of 26 amino acids. The cDNA clones encode a polypeptide of 805 amino acids with a helix-loop-helix motif and with some similarity to a certain region designated PAS of Drosophila Per and Sim, and human Arnt protein. Cotransfection of an expression vector of the Ah receptor with a reporter plasmid pMC6.3k consisting of CYP1A1 promoter and CAT structural gene into CV-1 cells enhanced the CAT expression in response to added 3-methylcholanthrene.     

Variations in and Inheritance of NS-Glycoprotein in Self-Incompatible Brassica campestris L.

The stigma of Brassica species contain NS-glycoproteins thatexhibit a high degree of structural homology to the S-glycoproteinsof self-incompatibility. Inheritance of and variations in theNS-glycoprotein were studied with reference to self-incompatibility.The detection of NS-glycoproteins was performed by cross-reactionwith an antiserum raised against a purified NS-glycoprotein.In B. campestris, four isoforms of the NS-glycoprotein weredifferentiated by their pI values, but their molecular weightswere identical to one another. The genes for these isoformsof NS-glycoprotein were controlled by alleles at a single locus,tentatively named the NS allele, which was independent of Salleles at both the protein and the DNA level. Segregation ofF₂ plants with respect to the self-incompatibility behaviorof pollen tubes can be explained by the S allele model, butit appears not to be affected by the NS alleles. NS-glycoproteinswere found in all 21 species of Brassica and its allies examinedto date. The pI values of these glycoproteins varied among differentspecies. In addition to the isoforms of the NS alleles, maturestigmas contained other groups of proteins that reacted weaklywith the antiserum against the NS-glycoprotein. (Received July 30, 1991; Accepted February 21, 1992)