Browsing by Author "K. Chandrasekhar"

Now showing 1 - 11 of 11

Algal biofilms: Potential wastewater treatment applications and biotechnological significance
(Elsevier, 2022) Kanishka Srivastava; Sweta Singh; Meenakshi Singh; Farzin Parabia; K. Chandrasekhar
Algae are ubiquitous autotrophic unicellular to multicellular thallophytes. They grow naturally in aquatic environments, including the wastewaters, and their biomass can be harvested easily in benthic conditions. Algae, in association with other microorganisms, form a thin film that attaches itself to solid surfaces enclosed in a matrix of extracellular polymeric substances (EPS). Therefore, the algal–microbial consortium has dominated the biofilm communities that colonize the illuminated surfaces under moisture and nutrients. Like bacterial biofilms, algal biofilms can respond to environmental changes, establish colonies on a surface, and isolate one colony or clumps from a surface. Though algal biomass is a low-cost nutrient removal source for bioproduct processing, its efficient application in wastewater treatments is not accepted worldwide. The chapter discusses the processes of algal-based wastewater treatment biofilm systems on the basis of the available literature, prohibiting efficient systems from being developed and applied to municipal, agricultural, and agrarian waste stream applications. The chapter outlines the need to explore factors influencing algal formation, mass migration, species collection, algal–bacterial interactions, and laboratory testing to establish an algal biofilm-based technical framework to combine wastewater treatment and biomass processing. © 2022 Elsevier Inc. All rights reserved.
Artificial spawning effected in the fresh water teleost, Cyprinus carpio by clomiphene citrate
(Birkhäuser-Verlag, 1980) S. Kumar; K. Chandrasekhar
Triweekly i.m. injections of clomiphene citrate (group 1, 25 μg/0.5 ml and group II, 50 μg/1.0 ml) were administered for a period of 3 months during the preparatory period to female fresh water teleosts exhibiting ovarian recrudescence, while a control group received 0.5 ml of physiological saline throughout the period of experimentation i.e., from February through April. 50 μg clomiphene citrate treatment brought about a steady increase in ovarian size, and oocytes began to enlarge and mature and finally ovulation took place in April. This is 4 months ahead of their normal occurrence. © 1980 Birkhäuser Verlag.
Effect of clomid on thyroids, diencephalic ependyma and subependymal cells in ovariectomized pigeon Columbia livia (Gmelin)
(1976) K. Chandrasekhar; S.S. Hasan
[No abstract available]
Effect of copper acetate and asphalt on gonadal activities and the correlated changes in the pre-optic nucleus of two genera of teleostean fishes, Clarias batrachus (Linn.) and Ophiocephalus punctatus (Bloch)
(1972) D. Khosa; K. Chandrasekhar
Asphalt and copper acetate are shown as chemical inductors which can enhance maturation of ova and increase vitellogenesis in the two genera of teleostean fishes, Clarias batrachus and Ophiocephalus punctatus. Along with the study of their effect on the ovaries, changes seen in the pre-optic nucleus of these fishes have also been studied. It is brought out that a distinct correlation exists between the ovarian activity and the fuchsinophil content of the neurons of the pre-optic nuclei of these two fishes. Copper acetate is seen to hasten enlargement of a large number of oocytes while asphalt increases their yolk content. It is also noticed that in the eggs with more yolk the granulosa is prominent. © 1972 Indian Academy of Sciences.
Effect of high & low doses of clomid on the ovary, diencephalic ependyma & thyroid in the pigeon Columba livia (Gmelin)
(1977) S.S. Hasan; K. Chandrasekhar
[No abstract available]
Effect of mammalian estrogens and progesterone on the hypothalamo-adenohypophysial complex of ovariectomised cat-fish Clarias batrachus (Linn)
(1972) K. Chandrasekhar; D. Khosa
Exogenous estrogen and progesterone are found to influence the Gomori positive secretion in the neurons of the supra-optic nucleus of Clarias batrachus. Prolonged administration of progesterone alone causes abnormal enlargement of the neurons of the pre-optic nucleus and the formation of unusually large vacuoles in the oocytes. The observations in this experiment are thus indicative of a correlatory pre-optico-ovarian activity. Progesterone in combination with estrogen enhances the accumulation of fuchsinophil material in the neurons of the pre-optic nucleus while complete absence of the ovarian hormones causes depletion of the Gomori positive material and brings in reduction in cell size. In the pituitary progesterone in combination with estrogen brings to prominence, the fuchsinophils and the basophils go into insignificance. On the other hand, in the ovariectomised control fishes, the basophils gained prominence. But progesterone alone seems to have no significant effect on either of them. © 1972 Indian Academy of Sciences.
Effect of osmotic stress on parsnervosa and median eminence of Columba livia (Gmelin)
(1978) S.S. Hasan; K. Chandrasekhar
The response made by parsnervosa and median eminence of pigeons to osmotic stresses created by sodium chloride and potassium iodide salt solutions have been studied. Parsnervosa of pigeons showed more drainage of AF-positive secretion in response to a higher concentration of saline solution (O·25M) whereas it became refractory to a lower dose of saline (0·15M). It was further observed that a 5 μg/ml dose of iodide affected the parsnervosa partly and while a 10 μg/ml dose failed to bring about any appreciable change. The amount of secretion contained in the median eminence underwent no essential change in response to osmotic stress. © 1978 Indian Academy of Sciences.
Effect of Pulsatilla 30 and 200 potencies (a homoeopathic drug) on the ovaries, the uteri and the thyroids of female albino rats
(1977) Suresh Prasad; K. Chandrasekhar
200 and 30 potencies of the drug Pulsatilla were used and their effect on the ovaries, the uteri and the thyroids of female albino rats were assessed. The higher potency was found significantly to reduce the weight of the uterus as well as the ovary. Drug treated rats exhibited variation in the sequences of vaginal cytology by shortening the proestrus phase of estrus cycle. The drug was found to increase the number of atretic follicles and decrease the number and size of the corpera lutea. Pulsatilla was seen to reduce the height of endometrium as well as those of the luminal epithelium. The two potencies of the drug were found to increase the number as well as the size of the stromal cells. In the drug treated rats the height of epithelial cells of the thyroids were lesser in comparison to the control. In the control group the intrafollicular colloid exhibited vacuoles whereas the intrafollicular colloid in the experimental groups had a homogeneous consistency. © 1977 Indian Academy of Sciences.
Facets of diatom biology and their potential applications
(Springer Science and Business Media Deutschland GmbH, 2022) Navonil Mal; Kanishka Srivastava; Yagya Sharma; Meenakshi Singh; Kummara Madhusudana Rao; Manoj Kumar Enamala; K. Chandrasekhar; Murthy Chavali
Diatoms are the reservoir of bioactive compounds which have immense application in nutrition, industrial commodities and ecological studies. In the oceans, diatoms form a large bloom of silica under favourable conditions, whereas, in lentic and lotic systems, they colonize according to seasonal disturbances. Notably, the survival of diatoms in a stressed environment is because of their uniqueness; therefore, diatoms serve as an ideal candidate to understand the evolutionary paradigm and successional dynamics. This review outlines the biological uniqueness of diatoms, their role in biogeochemical cycles and the recolonization pattern of diatoms in anthropic disturbed habitats. Furthermore, a detailed discussion on different technologies for extracting valuable biomolecules with an emphasis on lipid extraction has been carried out. Moreover, the diatom-based photosynthetic biorefinery approach for a better understanding of the renewable usage of biomass is done. Graphical abstract: [Figure not available: see fulltext.]. © 2021, Springer-Verlag GmbH Germany, part of Springer Nature.
Histomorphological studies on the neurosecretory system of three genera of freshwater teleostean fishes
(1972) K. Chandrasekhar; D. Khosa
The pre-optic nucleus of Clarias batrachus is club-shaped and that of Heteropneustis fossilis is spindle-shaped and the neurons in both take on a brilliant hue with aldehyde fuchsin stain. On the other hand, the nuclei are bizarre with diffuse neurons in Ophiocephalus punctatus. The pre-optic nuclei themselves are located anterior to the emergence of the optic nerve in O. punctatus while in the other two fishes they occupy positions posterior to it. A single neuron on the dorso-lateral aspect of the spindle in H. fossilis distorts its regular shape. The hypothalamo-hypophysial tract in C. batrachus and H. fossilis have an anterior bend and mingle with the optic nerve fibres before coursing caudad while in O. punctatus it takes on a straight posterior course. The distal parts of the tract in C. batrachus and H. fossilis pass through the middle of the adeno-hypophysis while in O. punctatus it lies bordering the infundibular recess giving off fuchsionphil haemofibres which mingle with capillary network and have a parallel course in between the cells of pars-distalis, thus making it resemble the 'Median Eminence' of higher vertebrates. © 1972 Indian Academy of Sciences.
Ultrastructural studies of the granulosa and the diencephalic ependyma in rats
(1975) K. Chandrasekhar
Light microscopy observations during the proestrous show the basal granulosa to be regularly arranged with a clear demarcation line between it and the underlying theca interna. Further, it was noticed that the granulosa has a smooth contour towards the antrum. On the other hand during the estrous period the demarcation line becomes strikingly irregular and the inner contour becomes wavy, striking a close resemblance to the intestinal 'villi'. Under the EM during the proestrous, the Golgi bodies appear well developed. In addition, coated vesicles, ribosomes and dense bodies are also discernible. But during estrous period the granulosa cells exhibit considerable accumulation of lipid droplets and peculiar complex bodies make their appearance. The endoplasmic reticulum becomes well delineated. Light microscopy observations of the ependyma show that it is attached to the sub-ependymal region but there is no basement membrane and the cells bear tufts of cilia on the luminal side. During the estrous period, the cells are seen to contain darkly staining bodies, while in the ovariectomised rats, the ependyma is clearly seen to detach itself from the sub-ependymal region. The detached ependyma is more than one layered. Under the EM, the ependyma of rats in proestrous were seen to contain a few dense bodies, mitochondria and endoplasmic reticulum. A few neuronal processes extending into the lumen were detectable. During the estrous, there was increase in the number of vesicles and mito-chondria and the cytoplasm became finely granular. The striking difference was seen in the widening of the intercellular space below the zonula adherens and zonula occludentes and this space getting filled with processes of neuronal origin. In the castrated rats, the cell got filled with fine filaments obliterating the detection of other structures. © 1975 Indian Academy of Sciences.