Volume 44, Issue 5
November 1956, pages 247-315
pp 247-256 November 1956
1. InS. sorrakowah andR. djddensis lipolytic activity is maximum in pancreas, minimum in spleen and kidney, intermediate in liver and absent in muscle and brain.
2. Aqueous glycerol and aqueous ethanol are good extractants ofS. sorrakowah pancreatic lipase.
3.S. sorrakowah pancreatic lipase is obtained as a yellowish white powder. Activity of enzyme is a function of H+ concentration, time and enzyme concentration. Both CaCl2 and bile salt are activators of the enzyme. Comparative rates of hydrolysis of different fats by enzyme have been studied.
pp 257-270 November 1956
pp 271-275 November 1956
An isolate ofCercospora personata, the causal organism of the “Tikka disease” or leaf spot ofArachis hypogea, has been shown to be easily culturable in a sporulating condition on a synthetic substrate with added yeast extract provided the inoculum is always a spore from a fresh lesion and not a mycelial bit. The fungus has been shown to be heterotrophic to both thiamine and inositol but after repeated sub-culturing becomes autotrophic to the latter.
pp 276-277 November 1956
pp 278-288 November 1956
1. Living yeast cells from 24-hr. agar slants were studied under ordinary, phase contrast and dark ground illumination. The majority of the cells in a population are non-budding, vacuolated and contain variable numbers of granules. The various cell types are described and illustrated.
2. The multi-vacuolate condition arises as a result of septation of a single vacuole. There are no canals connecting the vacuoles in a cell.
3. Evidence for the existence of a vacuolar membrane is adduced from observations under dark ground illumination. The vacuole encloses a dancing body in certain cells.
4. The glycogen areas are located outside the vacuole. The nucleus though not visible in living cells is revealed after fixation in dilute Lugol’s solution. It appears as a homogeneous body situated outside the vacuole.
pp 289-299 November 1956
Carbon nitrogen metabolism of two fungiFusarium vasinfectum andFusarium udum associated with the wilt of cotton andCajanus cajan respectively has been studied under varying conditions. The hydrogen-ion concentration of the culture media was found to depend on both carbon and nitrogen sources as well as the fungus. Nitrates and ammonium salts have opposite effects on the acidity of culture media, other conditions being the same the consumption of nitrate ions leads to increased alkalinity while the utilization of ammonium ions leads to higher acidity. The utilization of carbohydrates is found to depend on the nitrogen source as well as the fungus, nitrates in general requiring larger amounts. Nitrogen proportion of the mat is also variable. It is found to depend on both carbon and nitrogen sources, the nature of carbohydrate and the age and specificity of the fungus strain. Young cultures generally show a higher percentage of nitrogen than older cultures, irrespective of sources of nitrogen and carbon. Fusaria utilise both nitrate nitrogen and ammonia nitrogen in the presence of sucrose and glucose.
One may conclude that both Fusaria displayed different physiological relationship. This is evident from their rates of growth, their nitrogen and sugar utilization and the associated changes of the media caused by them.
pp 300-310 November 1956
Sucrose-ammonium nitrate medium behaves like a true nitrate medium in that pH after an initial lowering rises towards neutrality unlike other ammonium salts. After the initial utilization of ammonia nitrogen, ammonia nitrogen concentration remains apparently steady for any particular level (sucrose) and hence Fusaria appear to utilise nitrate nitrogen preferentially. It is quite probable that there is a steady state between the production of ammoniacal nitrogen and the utilization of the same by the fungus. The rate of growth varies with the concentration of carbohydrate with an optimum C/N ratio for maximum growth. The rate of sucrose depletion and the rate of nitrogen accumulation of the mat follow an exponential law with both fungi. Presence of nitrogen compounds in the filtrate (other than ammonia nitrogen and nitrate nitrogen) is minimum at the optimum concentration level III (sucrose).
pp 311-315 November 1956
1.Schizosaccharomyces octosporus sporulates in both solid and liquid media. The morphological changes that precede sporulation show considerable variation. A pictographic summary is presented.
2. Rare instances of the dissolution of the septum separating two cells—as a prelude probably to conjugation—are illustrated.
3. The origin of cells within a cell during sporulation is a possible example of differentiation-in-time. If meiosis constitutes the stimulus for spore formation, the question whether the transformation of cells into gametes and the putting out of conjugating tubes are not themselves initiated by other crytological changes requires consideration.