Predatory behaviour of squid (Illex illecebrosus) feeding on surface swarms of euphausiids

Squid (lllex illecebrosus) were observed and filmed feeding on daytime surface swarms of the euphausiid, Meganyctiphanes norvegien. in the Bay of Fundy. The squid captured euphausiids by tentacular attack, a predatory behaviour described previously for this and other species of squid feeding on mobile prey. This method of prédation is quite different from the only other documented account of squid feeding on euphausiid surface swarms.

Ventilatory and circulatory changes during cold exposure in the Pekin duck Anas platyrhynchos

Inspired ventilation (VI), O2 uptake (VO2), body temperature (TB), arterial blood pressure and arterio-venous differences in blood gases and pH were measured in ducks. Anas platyrhynchos, during exposure to variable ambient temperature (Ta) +20, 0 and -20 degrees C. A stable TB was maintained at all Ta's VO2 increased from 12.07 ml O2 (STPD) X kg-1 X min-1 at 20 degrees C to 28.95 ml O2 X kg-1 X min-1 at 20 degrees C. The ventilatory requirement (VI/VO2) changed from 0.468 L X mmol-1 at 20 degrees C to 0.322 L X mmol-1 at -20 degrees C corresponding to a change in overall O2-extraction from 28.5 to 41.4%. The increase in VI during cold exposure resulted from an increased tidal volume while breathing frequency was unchanged. This caused a smaller fraction of the total inspired air being dead space ventilation during cold exposure. The changed ventilatory requirement was largely the result of an increased parabronchial O2-extraction, whereas the altered ventilatory pattern accounted for a smaller part (21%) of the decreased ventilatory requirement. Arterial and venous O2 content and PaO2 changed little with cold exposure while PVO2 increased significantly. Calculated values for cardiac output increased from 173.7 ml X kg-1 X min-1 at +20 degrees C to 431.4 ml X kg-1 at -20 degrees C. From a thermoregulatory point of view it seems significant that the increased heat production during cold exposure is followed by an increased oxygen extraction in the lungs and in increased cardiac output, rather than by a further elevation of ventilation.

Active cation transport and Na+K+Mg ATPase of the monotreme erythrocytes

The erythrocytes of the echidna (Tachyglossus aculeatus) and platypus (Ornithorhynchus anatinus), which are practically devoid of intracellular ATP content (1), were examined for active Rb86 influx and for the presence of Na+K+Mg ATPase. We found that intact erythrocytes of both species possess the ability to actively transport cations. Ouabain sensitive Rb86 influx in the echidna was approximately 0.17 mumoles/ml cells x hr, whereas the platypus exhibited a higher value of 0.43 mumoles/ml cells x hr. Surprisingly, ouabain sensitive Na+K+Mg ATPase activity of isolated membranes was high amounting to some 15 to 25 fold higher than the human erythrocyte counterpart determined under identical conditions. These findings suggest that a trace amount of ATP is sufficient to maintain active cation transport across the monotreme cell membranes.

Metabolic properties of low ATP erythrocytes of the monotremes

The erythrocytes of the monotremes, having a trace amount of ATP, can metabolize glucose to lactate at a rate comparable to human and other mammalian erythrocytes. The echidna energy metabolism is unique in that adenosine can stimulate glycolytic carbon flow, resulting in a nearly 20-fold net synthesis of ATP.

Erythrocyte phosphates and hemoglobin function in monotremes and some marsupials

Hematologic values, red blood cell (RBC) organic phosphate composition, hemoglobin function, and hemoglobin composition have been determined on blood from the monotremes, the duckbill platypus and the echidna, and three species of marsupials, the Tasmanian devil, the wallaby, and the brush-tail possum. Blood from the platypus had a RBC count of 8.63 X 10(6)/mm3, a mean corpuscular volume of 49.1 millemicron3, and a white blood cell count of 26.0 X 10(3)/mm3. The RBCs from the monotremes and the three marsupials exhibited hemoglobin polymorphism, each with three hemoglobin components. Addition of ATP, 2,3-bisphosphoglycerate (2,3-P2-glycerate), or inositol pentakisphosphate (inositol-P5) to phosphate-free hemoglobin from each species decreased hemoglobin oxygen affinity; the order of effect of these compounds was ATP less than 2,3-P2-glycerate less than inositol-P5. The RBCs of all species had concentrations of 2,3-P2-glycerate ranging from 6.02 mumol/ml RBCs in the wallaby to 10.39 mumol/ml RBCs in the possum. The RBCs from the three species of marsupials had concentrations of ATP ranging from 0.24 mumol/ml RBCs in the possum to 0.80 mumol/ml RBCs in the Tasmanian devil. The level of ATP in RBCs of the platypus and echidna were 0.06 and 0.03 mumol/ml RBCs, respectively.

Comparison of hospitalization measures in schizophrenic patients with and without a family history of schizophrenia

It is well known that an individual with a family history of schizophrenia carries an increased risk of manifesting the disorder in comparison with members of the population at large. Also, within the population of schizophrenic patients, individuals may or may not have other members of the family affected. Obviously also, schizophrenic patients may be distinguished by gradations of severity of the illness. Whether familial incidence of schizophrenia and severity co-vary, however, remains an open question.