1.1. The medial (MGF), lateral (LGF) and motor (RMS-2) giant neurons were confirmed as neural components in the earthworm Amynthas hawayanus polysynaptic reflex circuit by simultaneous potential recording and dye injection.
2.2. The reflex was initiated from the mechanoreceptors when evoked by mechanical stimulation but electrical stimulation also evoked an antidromic response in the motoneuron.
3.3. The primary reflex response propagates decrementally along both giant axons but directly evoked action potentials conduct in an all-or-none fashion.
4.4. The secondary reflex response continues to propagate after the primary response disappears.
5.5. A rhythmically discharging neuron of uncertain function was also identified.
1.1. The histopathology of zebra mussel populations (Dreissena polymorpha) which were transplanted and exposed in baskets in the Dutch sector of the River Maas (5 locations) were compared with indigenous wild mussels at the same locations and at a clean reference site in the Ijsselmeer.
2.2. All groups were sectioned histologically and examined to quantify cytological damage and pathology of a wide range of tissues, as well as to examine parasitology and to assess their reproductive state.
3.3. Results show a significant reduction in general cytological quality and an increase in observed pathological conditions in the wild populations at the 3 downstream stations.
4.4. The transplanted (active biomonitoring) groups of mussels clearly showed a similar trend in condition after only 42 days exposure at these sites.
5.5. The influence of an industrial spillage of Cd in the Maas during the exposures is examined against this background of locally varying “health”.
1.1. Subcellular distribution of (NA+, K+-ATPase and ouabain-insensitive ATPase (Mg2+-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.
1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P3 from the posterior gills.
3.(c) No activation occurs with the fractions P3 as well as P1 or P2 (not shown) from anterior gills of fresh water crab.
4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.
1.1. In smooth muscle of the guinea-pig stomach, intramural nerve stimulation evoked cholinergic excitatory junction potential in the fundus and non-adrenergic non-cholinergic inhibitory junction potential in the antrum, yet cholinergic contractions in both regions.
2.2. This dissociation between electrical and mechanical responses was mainly due to different sensitivity of the membrane for depolarization to acetylcholine.
1.1. Homing pigeons, receiving regular flight-training for participation in racing competitions, were flown from their usual release site, 48 km away from “home”.
2.2. On their return “home” within 60–80 min, blood samples for the measurement of melatonin were taken within 1–3 min of arrival.
3.3. Post-flight circulating levels of melatonin were found to be about 82% higher than those of the resting control pigeons without any change in plasma osmolality.
4.4. This daytime increase in circulating levels of melatonin suggests that melatonin, by virtue of its known hypothermic effect of facilitating peripheral heat dissipation, could prevent excessive flight-induced hyperthermia.
5.5. It is also suggested that the flight-induced increase in plasma levels of melatonin is consistent with the known analgesic and metabolic effects of the hormone.
1.1. Communication is so essential to the living state at all its different levels of organization, from the cell organelle to the population, that in my opinion life could be defined as follows: Death ensues when the ability to communicate at the highest level of organization of the biological system under consideration is irreversibly lost.
2.2. The most primitive means of communication in the first cell which appeared on earth may have been ionic/electrical in nature. In the course of Evolution, a variety of additional means of communication have been generated.
3.3. Communication by whatever means requires gradients together with energy acquired from the environment.
4.4. “Life” might not have originated earlier than the moment that the first ionic gradient was actively established over the limiting membrane of the first cell. It may not be excluded that the ability to drive an ionic flux through itself, this implying polarity, was a second essential prerequisite for the living state to arise.
5.5. The formation of the primitive, polarized and order bringing cytoskeleton may have been as important as that of nucleic acids for the living state to arise and to acquire its full asset of means of communication.
6.6. “Life” may have originated many times in the primordial conditions before an ionically/electrically compartmentalized and polarized aggregate finally achieved orderly division and multiplication. Only then did the long term life traits for perpetuating a population and for generating diversity come into play.
7.7. If the proposed definition is correct, it follows that the term “life” implies flexibility because the ability to communicate depends on the steepness and the nature of the gradients: “life” presents itself in many forms and gradations.
8.8. The definition given under 1. or, more practically, “life: the ability to communicate” may bring more unity in all the different meanings which the different disciplines studying “life” intuitively attribute to their study object.
1.1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function.
2.2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular nitration rate (GFR).
3.3. Humans and mammals of a similar and larger size had “lost” the ability to reabsorb iodide efficiently.
4.4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR.
5.5. Thyroid weights in relation to body weight were highest in humans suggesting that humans and other mammals of a similar size are especially susceptible to iodine deficiency.
1.1. Two “en passant” electrodes were implanted around the cerebrobuecal connective (CBC) of Aplysia and used to record the activity, in the unrestrained animal, under three behavioural conditions; (a) absence of feeding behaviour, (b) appetitive feeding behaviour and (c) consummatory feeding behaviour.
2.2. The two simultaneous recordings were subjected to cross-correlation analysis, to subdivide spikes on the basis of their direction and speed of propagation.
3.3. There was virtually no CBC activity in the absence of food and feeding behaviour.
4.4. During appetitive feeding the metacerebral giant cell (MCC) was active and traffic was heaviest in the cerebral-to-buccal direction.
5.5. During consummatory feeding, traffic was also sustained in the buccal-to-cerebral direction; there was a reduction in the activity of the MCC, and a peak in the activity travelling to the cerebral ganglia, in the region of higher conduction velocity, was especially pronounced.
6.6. Further analysis showed this peak to have its largest amplitude during the actual ingestion of food and to be the result of the firing of several different units.
7.7. CBC traffic in both directions was also activated in one case of “spontaneous” biting.
1.1. White muscle of yellowfin tuna is subject to a form of deterioration known as “burnt tuna”.
2.2. TEM and SDS-PAGE were used to quantify cellular differences in deteriorated white muscle of yellowfin tuna.
3.3. Electron micrographs showed a significant loss of Z-disc integrity and an increase in intracellular edema in burnt tuna.
4.4. Electrophoresis established that a specific doublet of proteins, 42 kD and 46 kD was lost.
5.5. Proteolysis of isolated myofibrils incubated in calpain (EC 3.4.22.17) was greatest at pH 7.5 and was selective for intermediate molecular weight proteins.
6.6. This evidence suggests that burnt tuna is a specific and limited proteolysis of myofibrillar structural proteins characteristic of calpain proteolysis.
1.1. Specific Dynamic Action (SDA) effects of diet were investigated in the supralittoral isopod, Ligia pallasii, using defined chemical diets.
2.2. “Apparent SDA”, or the total rise in metabolic rate following a meal, was resolved in animals eating a nutritionally complete chemical diet into three components: 8% mechanical costs of moving food through the gut, 40% “excitement costs” due to investigator disturbance and presence of food, and 52% SDA.
3.3. Excitement costs in animals exposed to food but which chose not to eat showed non-significant variation between diets containing different levels of chemical nutrients, but were significantly less on a diet containing only cellulose and agar.
4.4. SDA increased with increasing concentration of amino acids in the diet.
5.5. Substitution of whole-protein casein for free amino acids in the diet had no significant SDA effect, while substitution of free amino acids in the ratio found in casein more than doubled the SDA effect.
6.6. Deletion of alanine from the diet caused no significant effect on SDA, while deletion of phenylalanine caused a highly significant elevation in SDA.
1.1. The decompression syndrome hypothesis, as an explanation of the etiology of avascular necrosis, is further substantiated through analysis of its occurrence in turtles.
2.2. No examples were identified in terrestrial or aquatic forms diving to depths insufficient for development of decompression syndrome.
3.3. The “population” frequency of avascular necrosis has substantially diminished over geologic time.
4.4. A frequent occurrence in Cretaceous marine turtles, it is only rarely observed in specimens younger than Miocene age.
5.5. Evolution of physiologic and/or behavioral protective mechanisms appears to be responsible for reduced susceptibility to the underlying decompression syndrome.
1.1. Two morphotypes of Myliobatis from the demersal fishery off the Rio Grande (Brazil) were studied.
2.2. Thirty-two alleles were detected and resolved by 27 loci.
3.3. Nei's measure of genetic identity was 0.8306 and Thorpe's similarity was 0.6990. Mean heterozygosities observed were 0.1327 for the “DE” morphotype and 0.0409 for the “DL” morphotype.
4.4. Seven loci were fixed differently in the two taxa studied. This indicates the existence of a barrier to gene-flow between them, showing that both morphotypes belong to different species.
5.5. Jaccard's measure of similarity was calculated and a phenogram with the two morphotypes and M. freminvillii was constructed using isoelectric focusing of total soluble proteins. This showed a higher similarity between the two morphotypes of Myliobatis than M. freminvillii.
1.1. In order to investigate the function of the dorsal tricorn-type sensilla on Ligia exotica, the morphology and distribution of the setae and neural responses to certain stimulus modalities were studied.
2.2. These foraminate sensilla are found to occur over the body surface, except for several appendages and the ventral carapace (sternite); the dorsal carapace (tergite) is covered by only this type of sensilla.
3.3. The tricorn-type sensilla located on the dorsal carapace responded to mechanical, gustatory and olfactory stimulation.
4.4. The function of the tricorn-type sensilla on the dorsal carapace was discussed.
1.1. The electric organ discharge (EOD) frequency modulations evoked by brief water vibration were analysed in the pulse-type fish Gymnotus carapo.
2.2. The response consisted of a transient increase of the EOD frequency at short latency (30 msec). Response profiles were characteristic of the specimen and relatively independent on stimulus intensity.
3.3. Conversely, they were dependent on stimulation sequence, showing a rapid decrement along successive stimuli and high temporal discrimination.
4.4. The brief latencies indicate a relatively simple neural circuit.
5.5. The response may be an electrolocation enhancement strategy for the detection of moving objects based on “sampling” the periphery at a higher frequency.
1.1. The oxygen consumption of red and green Carcinus in normoxic and hypoxic sea water was determined, using an oxygen electrode in a sealed respirometer.
2.2. The red crabs had significantly higher “excited” oxygen uptake rates and a lower ability to compensate for hypoxia than the green crabs.
3.3. Red Carcinus display an emersion response to declining oxygen at lower oxygen tensions than the green crabs.
4.4. Mortality of red crabs exposed to prolonged anoxia was much greater.
5.5. The relationship of these findings to the zonation of the two colour forms on the shore is discussed.
1.1. Monoclonal antibodies (mAb) to antigen binding protein (ABP) of the earthworm Lumbricus terrestris have been prepared.
2.2. The specificity of mAb for a determinant located outside the antigen binding site was determined and verified in inhibition experiments.
3.3. The mAb were used for isolation of a 56 kDa ABP by an immunoprecipitation technique.
4.4. The binding of mAb to coelomocytes has demonstrated the existence of two cell populations, one with low and the other with high densities of ABP molecules on the cell membranes.
1.1. As previously shown, 14 mM d-glucose, a non-insulinotropic concentration in isolated chicken pancreas, permits an insulin release in response to d-glyceraldehyde, (d-GA; a glycolytic fuel) and l-leucine or α-ketoisocaproic acid (α-KIC) (non-glycolytic fuels), which alone are not initiators of insulin release in this species.
2.2. The “permissive” effect of d-glucose was also observed in the presence of d-mannose (which, as shown herein, is not insulinotropic alone).
3.3. The specificity of glucose for this “permissive” effect was, therefore, subsequently questioned in the presence of 10mM α-KIC by substituting various glycolytic and non-glycolytic fuels to glucose.
4.4. d-GA (at 5 and 15mM), d-mannose (30 and 50 mM), or the association of l-glutamine + l-asparagine permitted an insulin release in response to α-KIC.
5.5. The response was, however, delayed with d-GA, only occasionally with 50 mM d-mannose, and required high concentrations and was delayed in the presence of l-glutamine + l-asparagine as compared to that obtained with 14mM d-glucose + α-KIC.
6.6. In conclusion, the threshold of fuel-induced insulin release is much higher in the chicken than in mammals and this threshold is most efficiently lowered by glucose.
1.1. The magnesium ion [Mg2+] plays an important role as a co-factor in enzyme systems and as a modulator of the haemocyanin of crustacean arthropods.
2.2. Mg2+ is actively regulated in most decapod crustaceans via the antennal gland. The degree of regulation can be correlated to some extent with the “activity” of a particular species although there are “exceptions to the rule”.
3.3. Intraspecific studies indicate that there is a clear relationship between haemolymph [Mg2+] and the level of activity in particular crustacean species.
4.4. A plea is made for the investigation of temporal changes in the [Mg2+] of the haemolymph of a number of crustaceans and for more studies of Mg2+ homoeostasis in general.
