Aspects and altitudes modify the requirement of disturbance in oak (Quercus leucotrichophora A. Camus) belt of Garhwal Himalaya

Present study measures the impact of forest disturbance on population structure and regeneration status of a Himalayan banj oak (Qsuercus leucotrichophora A. Camus) forest at different aspects and altitudes. The whole study was carried out by placing 300 systematically selected sample plots in banj oak forest. The study revealed that moderately disturbed forest patches were present in all elevation ranges and both north and south facing aspects whereas most of the highly disturbed patches were situated near middle and lower stretches of forests or close to habitations. Density of primary diameter class (5–15 cm) was recorded highest in moderately disturbed zone in upper elevation ranges and north facing aspect and ‘fair’ category of regeneration was most frequent in all elevation ranges and aspects. The paper concludes a positive effect of mid-level disturbance on plant community for better regeneration and study recommends a minimum resource extraction and silvicultural practices in banj-oak belt of Himalaya for a minimum canopy opening which not only be able to provide biomass to local communities for their daily needs but also would be able to maintain and improve forest health.     

STUDIES ON SALT ACTION : X. THE INFLUENCE OF ELECTROLYTES UPON THE VIABILITY AND ELECTROPHORETIC MIGRATION OF BACTERIUM COLI.

1. The strain of Bacterium coli used in these experiments multiplies in distilled water at pH 6.0 and pH 8.0 and in Ringer-Locke solution at pH 6.0. Under all the other conditions studied the numbers decrease with the passage of time. 2. The electrophoretic charge of the cells is highest in distilled water at pH 6.0 and pH 8.0. Under all other conditions studied the velocity of migration is decreased, but the decrease is immediate and is not affected by more prolonged exposure. 3. A strongly acid solution (pH 2.0) causes a rapid death of the cells and a sharp decrease in electrophoretic charge, sometimes leading to complete reversal. 4. A strongly alkaline solution (pH 11.0) is almost as toxic as a strongly acid one, although in distilled water the organisms survive fairly well at this reaction. Electrophoretic charge, on the other hand, is only slightly reduced in such an alkaline medium. 5. In distilled water, reactions near the neutral point are about equally favorable to both viability and electrophoretic charge, pH 8.0 showing slightly greater multiplication and a slightly higher charge than pH 11.0. In the presence of salts, however, pH 8.0 is much less favorable to viability and somewhat more favorable to electrophoretic charge than is pH 6.0. 6. Sodium chloride solutions, in the concentrations studied, all proved somewhat toxic and all tended to depress electrophoretic charge. Very marked toxicity was, however, exhibited only in a concentration of .725 M strength or over and at pH 8.0, while electrophoretic migration velocity was only slightly decreased at a concentration of .0145 M strength. 7. Calcium chloride was more toxic than NaCl, showing very marked effects in .145 M strength at pH 8.0 and in 1.45 M strength at pH 6.0. It greatly depressed electrophoretic charge even in .0145 M concentration. 8. Ringer-Locke solution proved markedly stimulating to the growth of the bacteria at pH 6.0 while at pH 8.0 it was somewhat toxic, though less so than the solutions of pure salts. It depressed migration velocity at all pH values, being more effective than NaCl in this respect, but less effective than CaCl₂. 9. It would appear from these experiments that a balanced salt solution (Ringer-Locke''s) may be distinctly favorable to bacterial viability in water at an optimum reaction while distinctly unfavorable in a slightly more alkaline solution. 10. Finally, while there is a certain parallelism between the influence of electrolytes upon viability and upon electrophoretic charge, the parallelism is not a close one and the two effects seem on the whole to follow entirely different laws.     

Protection of olfactory responses from inhibition by ethyl bromoacetate, diethylamine, and other chemically active odorants by certain esters and other compounds

Certain vaporous chemicals (chemically active odorants) arecapable of both stimulating olfactory responses and reactingwith receptors, ion channels, or receptor/ionophore macromoleculesto inhibit olfactory responses. We have studied the physiologicaleffects of several chemically active odorants using electrophysiologicaltechniques to record electroolfactogram (EOG) responses fromthe frog's olfactory mucosa. So far, the most studied agentsare ethyl bromoacetate (EBA), an alkylating agent, and diethylamine(DEA), a compound which is one of the strongest neutral organicbases. Certain odorants, or ‘protectants’, whenpresent before, during, and after exposure of the olfactorymucosa to either EBA or DEA have the property of maintainingolfactory responses which would otherwise be inhibited by exposureto the chemically active odorant alone. Protection from inhibitionby EBA is conferred by the presence of isoamyl acetate and afew closely-related esters, while protection from inhibitionby DEA is produced by the presence of p-dichlorobenzene. Protectionfrom inhibition by DEA is also achieved by lowering the pH ofthe olfactory mucosa through the simultaneous delivery of CO₂which produces carbonic acid. The mechanism of protection byesters and p-dichlorobenzene is unknown, but it seems likelythat these odorants somehow interfere with the access of thechemically active odorant to a site where it would normallyreact. ¹Present address: PSC Box 511, Peterson AFB, Colorado Springs,Colorado 80914, USA. ²Permanent address: Department of Chemistry, New Mexico Instituteof Mining and Technology, Socorro, New Mexico 87801, USA.