Hypoxic water and episodic air exposure are potentially life-threatening conditions that fish in tropical regions can face during the dry season. This study investigated the air-breathing behavior, oxygen consumption, and respiratory responses of the air-breathing (AB) armored catfish Pterygoplichthys anisitsi. The hematological parameters and oxygen-binding characteristics of whole blood and stripped hemoglobin and the intermediate metabolism of selected tissue in normoxia, different hypoxic conditions, and after air exposure were also examined. In normoxia, this species exhibited high activity at night and AB behavior (2-5 AB h(-1)). The exposure to acute severe hypoxia elicited the AB behavior (4 AB h(-1)) during the day. Under progressive hypoxia without access to the water surface, the fish were oxyregulators with a critical O2 tension, calculated as the inspired water O2 pressure, as 47 ± 2 mmHg. At water O2 tensions lower than 40 mmHg, the fish exhibited continuous apnea behavior. The blood exhibited high capacity for transporting O2, having a cathodic hemoglobin component with a high Hb-O2 affinity. Under severe hypoxia, the fish used anaerobic metabolism to maintain metabolic rate. Air exposure revealed physiological and biochemical traits similar to those observed under normoxic conditions.

Natural insecticides from plant extracts represent an alternative to the highly toxic synthetic products in order to reduce environmental contamination; however some might also be toxic for nontarget organisms. The present study determined the 50% lethal concentration (48h; LC50) for adults Nile tilapia (Oreochromis niloticus) exposed to the natural insecticide Fumydro ® , based on the tobacco plant (Nicotiana tabacum), and evaluated its effect on hematological variables. After preliminary tests, adult specimens of O. niloticus were exposed to four Fumydro ® concentrations (200, 300, 400 and 500 μL L-1). The 48h; LC50 of Fumydro ® was determined at 370 ± 50 μL L-1. The surviving fish after exposure to Fumydro ® showed an increase in the number of red blood cells, hemoglobin concentration, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration. The number of thrombocytes and leukocytes has not changed, unlike the differential leukocyte count that presented an increased percentage of neutrophils. The results indicated that the insecticide Fumydro ® is highly toxic to Nile tilapia and changes in erythrocyte variables suggested the induction to hypoxemia with low effect on the immune system.

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In the sixteenth and seventeenth centuries, dioceses were centres of conflicts and struggles for power between bishops and the cathedral clergy. The dynamics of dioceses may be better understood by examining how the decrees of the Council of Trent were interpreted and applied in them. The main purpose of this paper is to study how the Portuguese cathedral chapters reacted to the application of the Tridentine decrees by their bishops. I show that the application of the decisions of Trent at the diocesan level was part of a rebalance of power that was taking place in the sixteenth and seventeenth centuries within the Catholic Church.

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