Studies on the feeding biology of an airbreathing fish Heteropneustes fossilis (Bloch)

The food and feeding habits of an air-breathing fish, Heteropneustes fossilis were studied from an eutrophic lake, Hussainsagar, Hyderabad, (Andhra Pradesh, India), during 1981-1983. The major preferred items of food were insect larvae, insects, ostracods, plant material and gastropods. Due to the mixed feeding habits of both plant and animal matter, this species is considered as an omnivorous feeder. Bryozoans were recorded for the first time in the diet of H. fossilis.

Influence of size, station time and satiation amount on prey handling time in Anabas testudineus (Bloch)

Satiation amount, satiation time and handling time of Anabas testudineus (Bloch), an air breathing predatory fish was experimentally estimated using guppy (Lebistes reticulatus) as prey. Weight of the fish and satiation time influenced prey handling time. As satiation time is related to the level of hunger, level of hunger was found to influence handling time of prey.

Studies on paddy-cum-fish culture under different land situations

Paddy fields can be broadly classified on the basis of land situations viz. Upland - Shallow water (10-30 cm), Medium land-medium deepwater (30-100 cm) and Low land-deepwater (above 100 cm). Three major systems of paddy-cum-fish culture, viz. (A) high yielding paddy varieties (H.Y.V) and air-breathing fish under Upland, (B) H.Y.V./local paddy and Tilapia/common carp under Medium land and (C) deepwater paddy and major Indian carps under Low land situations have been successfully investigated in the farmers' fields and at the Research Stations (1982-92). Effects of low-cost artificial feeding on growth, yield and management practices of different types of fish showed a considerable increase of rice and fish yields and a decrease in insect-pest incidence. Under Upland situation, short duration H.Y.V. in combination with fast-growing air breathing fish was studied thrice a year (summer, winter & autumn seasons). Combined rice and fish culture produced highest yields in all the seasons than in the control.

Physiology of the blood of cat fishes

The vast areas of derelict swamps covered by macrophyton and swarmed by insects scattered in different parts of India are at present either under total negligence or utilized as waste disposal dumps. Eventhough Indian subcontinent is ranked among the first ten fish producing countries in the world, the fish production is not at par with the increasing need of protein in the average Indian diet. So the water areas which become unusable for conventional human activities like the swamps could be used for fish culture which would increase the availability of protein in the form of fish flesh, thus providing new opportunities to the fishermen. But the conversion of swamps for fish culture would entail considerable expenditure. Hence the significance of a group of fresh water fishes which have made their favourable abode the muddy swamps of tropics depending partly on accessory _respiration to survive in the inimical environment. The homeostasis achieved in such a hostile, hypoxic medium make them excellent choices for culture in the derelict freshwater bodies of India. These air breathing fishes form an economically important group which are highly esteemed as food fishes in many parts of South Asia and Africa. Though their natural habitat seems to be the marshes, they have also conquered other freshwater bodies like ponds, tanks, rivers and flooded paddy fields. They can also tolerate slightly brackish waters. They are known for their nutritive, invigorating and therapeutic qualities and are recommended by physicians as diet during convalescence (Jhingran, 1982)

Regulation of ventilation in the caiman (Caiman latirostris): effects of inspired CO2 on pulmonary and upper airway chemoreceptors

In order to study the relative roles of receptors in the upper airways, lungs and systemic circulation in modulating the ventilatory response of caiman (Caiman latirostris) to inhaled CO2, gas mixtures of varying concentrations of CO2 Were administered to animals breathing through an intact respiratory system, via a tracheal cannula by-passing the upper airways (before and after vagotomy), or via a cannula delivering gas to the upper airways alone. While increasing levels of hypercarbia led to a progressive increase in tidal volume in animals with intact respiratory systems (Series 1), breathing frequency did not change until the CO2 level reached 7%, at which time it decreased. Despite this, at the higher levels of hypercarbia, the net effect was a large and progressive increase in total ventilation. There were no associated changes in heart rate or arterial blood pressure. on return to air, there was an immediate change in breathing pattern; breathing frequency increased above air-breathing values, roughly to the same maximum level regardless of the level of CO2 the animal had been previously breathing, and tidal volume returned rapidly toward resting (baseline) values. Total ventilation slowly returned to air breathing values. Administration of CO2 via different routes indicated that inhaled CO2 acted at both upper airway and pulmonary CO2-sensitive receptors to modify breathing pattern without inhibiting breathing overall. Our data suggest that in caiman, high levels of inspired CO2 promote slow, deep breathing. This will decrease deadspace ventilation and may reduce stratification in the saccular portions of the lung.

Control of respiration in fish, amphibians and reptiles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Autonomic control of cardiorespiratory interactions in fish, amphibians and reptiles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ecology of a stream from upper Paraná River basin inhabited by Aspidoras fuscoguttatus Nijssen & Isbrüker, 1976 (Siluriformes, Callichthyidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

DEVELOPMENT OF BLOOD-PRESSURE AND CARDIAC REFLEXES IN THE FROG PSEUDIS-PARADOXSUS

Systemic arterial blood pressure and heart rate (f(H)) were measured in unanesthetized, unrestrained larvae and adults of the paradoxical frog, Pseudis paradoxus from São Paulo State in Brazil. Four developmental groups were used, representing the complete transition from aquatic larvae to primarily air-breathing adults. f(H) (49-66 beats/min) was not significantly affected by development, whereas mean arterial blood pressure was strongly affected, being lowest in the stage 37-39 larvae (10 mmHg), intermediate in the stage 44-45 larvae (18 mmHg), and highest in the juveniles and adults (31 and 30 mmHg, respectively). Blood pressure was not significantly correlated with body mass, which was greatest in the youngest larvae and smallest in the juveniles. In the youngest larvae studied (stages 37-39), lung ventilation was infrequent, causing a slight decrease in arterial blood pressure but no change in heart rate. Lung ventilation was more frequent in stages 44-45 larvae and nearly continuous in juveniles and adults floating at the surface. Bradycardia during both forced and voluntary diving was observed in almost every advanced larva, juvenile, and adult but in only one of four young larvae. Developmentally related changes in blood pressure were not complete until metamorphosis, whereas diving bradycardia was present at an earlier stage.

Molecular modeling and small angle X-ray scattering studies of Hoplosternum littorale cathodic haemoglobin

Considerable interest is currently focused on fish haemoglobins in order to identify the structural basis for their diversity of functional behavior. Hoplosternum littorale is a catfish that presents bimodal gill (water)/gut (air) -breathing, which allows this species to survive in waters with low oxygen content. The hemolysate of this fish showed the presence of two main haemoglobins, cathodic and anodic. This work describes structural features analyzed here by integration of molecular modeling with small angle X-ray scattering. Here is described a molecular model for the cathodic haemoglobin in the unliganded and liganded states. The models were determined by molecular modeling based on the high-resolution crystal structure of fish haemoglobins. The structural models for both forms of H. littorale haemoglobin were compared to human haemoglobin. (C) 2004 Elsevier B.V. All rights reserved.

Purification, crystallization and Patterson search of haemoglobin IV from the armoured catfish Liposarcus anisitsi

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)