Morphometric estimation of oxygen diffusing capacity for the air-sac in the catfish Heteropneustes fossilis

A detailed morphometric study has been made of the air-sacs of this air-breathing catfish using whole mounts, light and electron microscopy, of six specimens, body weight 40±2 g. Measurements of surface areas of the gas exchange and non-respiratory surfaces have taken into account foldings of the surface at macro and ultramicroscopic levels. Area of the gas exchange surface was estimated as 23.915cm² (=0.598cm²/g) which is 67%of the total surface area of the two air-sacs. Significant differences were found in some morphometric parameters which were related to the three antero-posterior regions into which air-sacs were divided. Harmonic mean thickness of the tissue component of the air/blood barrier was estimated for the whole air-sac as 0.342 μ m. These and other measurements enabled the diffusing capacity for the air-sacs to be calculated as 0.0638 m1O₂/min/mmHg/kg.
These results show that Heteropneustes has an air-breathing organ which is superior to that of Amphipnous cuchia , similar to that of Lepidosiren , but less well developed than that of Protopterus . In addition, Heteropneustes is well adapted to obtain oxygen directly from water by means of its gills and skin as indicated by both morphometric and physiological measurements which also correlate with its life in ponds and streams which are Iiable to dry up.     

Glycoalkaloid and nitrate content of potatoes as affected by method of selenium application

A comparison of two methods of selenium application, banding and foliar spray, of sodium selenite (Na₂SeO₃) on total glycoalkaloid (TGA) and nitrate nitrogen (NO₃-N) was studied during each of two consecutive years. The levels of application used were 0.0, 1.6 (0.75), 3.36 (1.5), and 5.6 (2.5) kg/ha (ppm soil). Both TGA and NO₃-N were significantly reduced by application of 1.5 and 2.5 ppm of sodium selenite. Tuber selenium levels were significantly increased at all levels of application, using either banding or foliar spray, but were well below the toxic range for human consumption. Banding resulted in greater uptake of Se, and greater decreases in TGA and NO₃-N as compared to foliar spray.     

Diurnal variations of serum testosterone levels in the male bonnet monkey (Macaca radiata)

Diurnal variations in serum testosterone levels were studied in six adult maleMacaca radiata. Though the testosterone levels fluctuated considerably during the 24-hr period, a distinctive diurnal pattern characterized by lower concentrations during day hours and higher concentrations during night hours was observed.     

Light and scanning electron microscopic studies on the effect of biocidal plant sap on the gills of a hill stream fish, Garra lamta (Ham.)

The effect of a biocidal plant sap ( Terminalia tomentosa ) on the gills of a swift-current-adapted hill-stream fish, Garra lamia , has been investigated using light and scanning electron microscopy. The biocidal plant sap affected the dissociation of the gill filament and lamellar epithelia to expose their microvasculature. Some findings on the microvasculature are discussed in the light of their probable functions. Fusion of lamellae and prominent chloride cells are further effects of the plant sap, and their impact on respiratory and osmoregulatory functions of the fish are discussed.
Use of biocidal plant sap in mass killing of hill-stream fish is considered in relation to conservation.     

Structure of the integument of a fresh-water teleost,Bagarius bagarius (Ham.) (Sisoridae,pisces)

The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells. The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes. Two layers of the dermis can be distinguished—the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis. The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.     

Studies on blood components of an air-breathing siluroid fish, Heteropneustes fossilis (Bloch) in relation to body weight.

Different haematological parameters have been studied in relation to the body weight of Heteropneustes fossil (Bloch). The erythrocytes and leucocytes number and haemoglobin concentration increases from lower to higher weight groups. The heart weight also increases along with other blood components. With the unit increase in the body weight of this fish, the heart weight, erythrocytes, leucocytes and haemoglobin increase by a fractional power of 0.85700, 0.13480, 0.13215 and 0.22876, respectively. This shows that haemoglobin increases at a higher rate than erythrocyte number. The coefficient of correlation between body weight and erythrocyte (r = 0.70015), leucocytes (r = 0.95861), haemoglobin (r = 0.96615) and heart weight (0.97577) indicate high degree of correlation. The erythrocytes and leucocytes count and haemoglobin concentration per gram body weight is higher in younger fishes and decrease as the animal grows in size. The haematocrit values and mean corpucsular volumes decrease from lower to higher weight groups, whereas mean corpuscular haemoglobin concentration increases with body weight. The erythrocyte cell surface has a decreasing trend from lower to higher weight group. Due to difference in the rate of decrease of greatest and least diameter of erythrocytes, the elliptical shape of R.B.C. which is common in younger animals, becomes circular in higher weight group. The non-granulocytes increase constantly while the percentage of granulocytes decreases from lower to higher weight groups. The lymphocytes constitute the main bulk of all the leucocytes. The total lymphocytes also increase with the body weight. Spindle cells and monocytes are relatively less in numbers. The percentage of eosinophils, basophils and neutrophils also decrease from lower to higher weight groups.