Is there a compromise between nutrient uptake and gas exchange in the gut of Misgurnus anguillicaudatus, an intestinal air-breathing fish?

2007 ◽  
Vol 2 (4) ◽  
pp. 345-355 ◽  
Author(s):  
Ana Filipa Gonçalves ◽  
L. Filipe C. Castro ◽  
Cristina Pereira-Wilson ◽  
João Coimbra ◽  
Jonathan Mark Wilson
Keyword(s):  
Gas Exchange ◽  
Nutrient Uptake ◽  
Misgurnus Anguillicaudatus ◽  
Air Breathing

scholarly journals Respiratory Physiology of Intestinal Air Breathing in the Teleost Fish Misgurnus Anguillicaudatus

1987 ◽  
Vol 133 (1) ◽  
pp. 371-393 ◽  
Author(s):  
BRIAN R. McMAHON ◽  
WARREN W. BURGGREN
Keyword(s):  
Gas Exchange ◽  
Alimentary Canal ◽  
Co2 Exchange ◽  
Gas Diffusion ◽  
Respiratory Physiology ◽  
Misgurnus Anguillicaudatus ◽  
Air Breathing ◽  
Intestinal Gas ◽  
Partial Pressures ◽  
O2 Extraction

The Japanese weatherloaeh (Misgurnus anguillicaudatus Cantor) can exchange gases both with water, via gills and skin, and with air, via the posterior region of the alimentary canal (intestine). Air breathing occurs by unidirectional ventilation of the alimentary canal with air taken in at the mouth and simultaneous expulsion of intestinal gas from the vent. Although the weatherloaeh is not an obligate air-breather, aerial gas exchange normally occurs even at 10°C in air-saturated water. The alimentary canal was examined histologically to assess differences in capillary density and distribution and the diffusion distance for gases across those regions modified for aerial respiration. A respirometer system specifically designed for 2- to 3-g fish allowed continuous measurement of O2 and CO2 exchange via both aquatic and aerial routes at rest and at various ambient temperatures, and respiratory gas partial pressures. Air ventilation volumes, O2 and CO2 partial pressures of exhaled gas, O2 extraction, and O2 and CO2 exchange via the intestine were also determined, allowing the role of the intestine in total gas exchange in the weatherloaeh to be determined and compared with aerial gas exchange organs in other fishes. The alimentary canal is divided into three zones, an anterior glandular portion separated by a spiral section from the posterior, respiratory zone which has the greatest capillary densities and shortest gas diffusion distances. At rest (20°C), the intestine takes up about 20% of total O2 but accounts for less than 3 % of total CO2 elimination (gas exchange ratio = 0.08 for intestine). O2 extraction averages 50%. Increasing temperature causes only slight increases in total metabolic rate (Q10 for MOO2= 1.5-1.8), but highly significant increases in intestinal gas exchange relative to total gas exchange develop as temperature rises. Intestinal gas exchange also rises with decreasing O2 availability. A strong hypoxic drive and weak hypercapnic drive exist for aerial ventilation of the intestine, but are reduced or absent for aquatic ventilation of the gills. In spite of having to function in respiration, absorption, secretion and buoyancy regulation, the potential effectiveness of intestinal gas exchange is shown to be similar to that of other structures used for aerial gas exchange in facultative air-breathing fish.

Vasculature of the Gas-Exchange Organs in Air-Breathing Brachyurans

1990 ◽  
Vol 63 (1) ◽  
pp. 117-139 ◽  
Author(s):  
Peter Greenaway ◽  
Caroline Farrelly
Keyword(s):  
Gas Exchange ◽  
Air Breathing

Respiration in the African Lungfish Protopterus Aethiopicus

1968 ◽  
Vol 49 (2) ◽  
pp. 437-452 ◽  
Author(s):  
CLAUDE LENFANT ◽  
KJELL JOHANSEN
Keyword(s):  
Gas Exchange ◽  
Haemoglobin Concentration ◽  
Temperature Shift ◽  
Mean Value ◽  
Gas Analysis ◽  
Air Exposure ◽  
Air Breathing ◽  
African Lungfish ◽  
High Degree ◽  
Protopterus Aethiopicus

1. Respiratory properties of blood and pattern of aerial and aquatic breathing and gas exchange have been studied in the African lungfish, Protopterus aethiopicus. 2. The mean value for haematocrit was 25%. Haemoglobin concentration was 6.2 g% and O2 capacity 6.8 vol. %. 3. The affinity of haemoglobin for O2 was high. P50 was 10 mm. Hg at PCOCO2, 6 mm. Hg and 25 °C. The Bohr effect was smaller than for the Australian lungfish, Neoceratodus, but exceeded that for the South American lungfish, Lepidosiren. The O2 affinity showed a larger temperature shift in Protopterus than Neoceratodus. 4. The CO2 combining power and the over-all buffering capacity of the blood exceeded values for the other lungfishes. 5. Both aerial and aquatic breathing showed a labile frequency. Air exposure elicited a marked increase in the rate of air breathing. 6. When resting in aerated water, air breathing accounted for about 90% of the O2 absorption. Aquatic gas exchange with gills and skin was 2.5 times more effective than pulmonary gas exchange in removing CO2. The low gas-exchange ratio for the lung diminished further in the interval between breaths. 7. Protopterus showed respiratory independence and a maintained O2 uptake until the ambient O2 and CO2 tensions were 85 and 35 mm. Hg respectively. A further reduction in O2 tension caused an abrupt fall in the oxygen uptake. 8. Gas analysis of blood samples drawn from unanaesthetized, free-swimming fishes attested to the important role of the lung in gas exchange and the high degree of functional separation in the circulation of oxygenated and deoxygenated blood.

Azospirillum brasilense FAVORS MORPHOPHYSIOLOGICAL CHARACTERISTICS AND NUTRIENT ACCUMULATION IN MAIZE CULTIVATED UNDER TWO WATER REGIMES

2020 ◽  
Vol 19 ◽  
pp. 17
Author(s):  
DANIELE MARIA MARQUES ◽  
PAULO CÉSAR MAGALHÃES ◽  
IVANILDO EVÓDIO MARRIEL ◽  
CARLOS CÉSAR GOMES JUNIOR ◽  
ADRIANO BORTOLOTTI DA SILVA ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Plant Growth ◽  
Nutrient Uptake ◽  
Water Deficit ◽  
Azospirillum Brasilense ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nutrient Analysis ◽  
Promising Tool ◽  
Water Conditions ◽  
Maize Plants

The use of plant growth-promoting rhizobacteria (PGPR) is an important and promising tool for sustainable agriculture. The objective of this study was to evaluate the morphophysiological responses and nutrient uptake of maize plants inoculated with A. brasilense under two water conditions. The experiment was carried out in a greenhouse with ten treatments: five A. brasilense inoculants (Control, Az1, Az2, Az3 and Az4) inoculated in the seed and two water conditions - irrigated and water deficit. Treatments with water deficit were imposed at the V6 stage for a period of 15 days. The phytotechnical characteristics, gas exchange, root morphology, shoot, root and total dry matter, as well as nutrient analysis, were evaluated after water deficit. Azospirillum brasilense (Az1, Az2, Az3 and Az4) yielded higher growth, increased gas exchange and nutrient uptake under irrigation conditions. Inoculation by Az1 and Az3 benefited the root architecture of maize plants, with a greater exploitation of the soil profile by these roots. Water deficit caused a reduction in the development of maize plants. Inoculation by Az1, Az2 and Az3 can improve plant growth, nutrient uptake and mitigate the effects of water deficit in the development of maize plants.

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