Quantification and origin of the immunoglobulins in porcine respiratory tract secretions

The immunoglobulin content of porcine nasal, tracheal and bronchio-alveolar secretions was determined. IgA was the predominant immunoglobulin in nasal and tracheal secretions, there being no significant difference (P greater than 0.01) between their IgA:IgG ratios of 2.7:1 and 2.4:1, respectively. In contrast, IgG was the predominant immunoglobulin in bronchioalveolar secretions, the IgA:IgG ratio being 0.7:1. The ability of tracheal and lung tissue to synthesize IgA and IgG was determined in vitro. Tracheal cultures synthesized more IgA than IgG whereas in the lungs the reverse occurred, the ratio of IgA:IgG synthesis being 1.4:1 and 0.4:1, respectively. The proportion of serum-derived IgA and IgG in respiratory tract secretions was determined by measuring the transfer of 125I- and 131I-labelled immunoglobulins from serum. It appeared that more than 97% of the IgA was produced locally. More significantly a proportion of the IgG was also synthesized locally. This proportion was smallest in nasal secretions (21.8%) and greatest in bronchio-alveolar secretions (62.6%). The results suggest that IgG, a large proportion of which is locally synthesized, is important in the homeostatic mechanisms of the lower respiratory tract.

Studies on the formation of alpha-amylase by Thermomonospora vulgaris

Conditions affecting the formation of alpha-amylase by static cultures of the thermophilic actinomycete Thermomonospora vulgaris were studied. The organism failed to grow under submerged culture conditions or when the culture medium was devoid of CaCO3-alpha-Amylase was produced during the logarithmic phase of growth and maximum yield was obtained after 3 to 9 days of incubation. Growth and amylase formation took place only in a range from 45 degrees to 55 degrees C; optimum temperature was 55 degrees C. Of the tested carbon sources only starch induced enzyme formation. Maximum enzyme yield was obtained when starch concentration of the medium was 2% and when ammonium citrate served as a nitrogen source. Crushed clay pots could substitute for CaCO3 of the medium, but growth and amylase yield were less.

Amylase of the thermophilic actinomycete Thermomonospora vulgaris

alpha-Amylase of the thermophilic actinomycete Thermomonospora vulgaris was partially purified. Maximal enzyme activity was obtained at 60degreeC and pH 6.0. KM value was l.4%. The effect of some metal salts on enzyme activity was studied. Enzyme activity was inhibited by by KCN, EDTA, and iodoacetate. Inhibition by EDTA was completely nullified by CaCl2, but the inhibition by iodoacetate was not overcome by 2-mercaptoethanol. Exposure of the enzyme to pH 7.0 and 9.0 for 2 hr. did not affect the enzyme, but exposure to pH 3.0 for few minutes completely inactivated the enzyme. Exposure of the enzyme to 60degreeC resulted in an appreciable inactivation and exposure to 80degreeC completely inactivated the enzyme. Addition of CaCl2, 2-mercaptoethanol, or enzyme substrate the 60degreeC exposed enzyme. However, bovine serym albumin had a protective effect when the enzyme was exposed to 60degreeC but not to 80degreeC. The enzyme was stable in the presence of 8 M urea.