Tissue culture of Pakistani rice varieties: I- Optimization of physical factors

A study for optimizing appropriate explant, conditions for sterilization and physical environments was conducted using rice varieties Bas -370, IR-6 and KS-282. Sterilization of seeds was better obtained in HgC12 than chlorox [Commercial sodium hypochlorite] but due to lesser seed germination after HgC12 treatment, chlorox was prefered over the other. Chlorox treatment increased the subsequent callus induction in seeds. However, nodal portions and root tips were damaged by the treatments. Out of mature seeds, nodal explants and root tips, seeds proved to be the best explant for callus cultures, 28°C was the best temperature for callus induction and callus multiplication in the seeds. However for organogenesis 26°C was the optimum. Light, complete dark or 16 h day length played no significant effect in callus induction. Callus formation frequency was maximum at a pH ranging from 5.5 to 7.0. Beyond this pH range there was a sharp decline in callus induction, multiplication and plant regeneration

Some properties of the extracellular, cell bound and intracellular protease of mucor hiemalis

This study was undertaken to provide some basic aspects of the extracellular, intracellular and cell-bound protease of M. Hiemalis. was also tested for the production of milk-clotting enzymes. It was found that the protease whether obtained extracellularly or intracellulary exhibited milk-clotting action, although it was very weak and took about 8 hours to clot the milk. Intracellular protease showed maximum activity when it was extracted with 7.8 pH phosphate buffer. It was most active when incubated at 35°C. The protease hydrolysed casein and the rate of hydrolysis increased with the increase in time. Similar results were obtained with the extracellular and cell-bound protease

Effects of pectin-esterase on clarification of fruit juices

Effect of pectin esterase [isolated from sour oranges] on clarification of fruit juices both at low [15 °C] and high 45 °C] temperatures was studied. Enzymic clarification of juices at low temperature was comparatively slow, but with no damage to their colour and flavour. While elevation of temperature accelerated the action of enzyme [PE]. Fall in pH-values of the enzyme-treated juices may be due to the production of free carboxyl groups resulting from enzymic deesterification of the methylated pectic substances naturally accuring in the fruit juices

Inhibition of pectin-esterase activity

The inhibitory effects of p-chloromercuribenzoate, iodo-acetic acid, and 2:4 - dinitro - 1 - fluoro-benzene, on pectin-esterase, isolated from sour oranges, were studied. p-chloromercuribenzoate [5 x 102 M] inhibited 95.08% activity of pectinesterase. Application of cysteine to the system containing chloromercuri-benzoate was found ineffective to cause reversion of pectin esterase activity. 2:2 - D, [10-1 M] and iodo-acetic acid [10-1 M] produced 29.06% and 37.36% respectively inhibition of pectinesterase activity. Nitroprusside test was found positive. These findings suggest the presence of thiol group [s] which may form an integral part of active site of the enzyme