Salivary gland amylase polymorphism in pigs and cattle detected by affinity electrophoresis

New allelic variants of salivary gland alpha-amylase in pigs (AMY-1C, AMY-1D) have been detected using affinity electrophoresis. In yak, zebu and in hybrids (yak x cattle, zebu x cattle) a new AMY-1 allelic variant (AMY-1D) has been found using the same method.     

Thermostability improvement of maltogenic amylase MAUS149 by error prone PCR

The thermostability of maltogenic amylase from Bacillus sp. US149 (MAUS149) was improved by random mutagenesis using error prone PCR. The library constructed for the mutants obtained was subjected to screening, leading to the selection of a thermostable mutant enzyme named MA-A27. The latter was noted to contain four single mutations, namely D46V, P78L, V145A, and K548E. The half-life times recorded for MA-A27 at 50 °C and 55 °C were 70 min and 25 min, compared to 30 min and 13 min for the wild type, respectively. The results from molecular modeling attributed the increase in thermostability observed for MA-A27 to P78L and K548E substitutions that led to new hydrogen bond and salt bridge formations. Further site-directed mutagenesis studies showed that the P78L and K548E single mutations underwent an increase in thermostability, thus confirming the joint contribution of both substitutions to the increase in thermostability observed for MA-A27.     

Further studies on bovine serum amylase. 2. Affinity electrophoresis

The polymorphism of bovine serum amylase, which is controlled by the Ami locus, has previously only been demonstrated by starch gel electrophoresis. The addition of maltose to starch gels has been demonstrated to inhibit any subsequent separation of the Ami isozymes by starch gel electrophoresis. When electrophoresis was conducted in a support medium in the absence of starch no polymorphic variation was detected amongst samples from animals of different Ami phenotypes. The addition of starch to agarose gels has been shown to facilitate the subsequent detection of the Ami polymorphism by agarose/starch gel electrophoresis. The electrophoretic resolution of the Ami isozymes has been demonstrated to depend upon differences in affinity for starch rather than differences in net charge. The starch gel electrophoretic separation of the Ami isozymes is. therefore, another example of affinity electrophoresis. All the Ami amylases have been shown to share a common isoelectric point of pH 3.5.     

Paradoxical Pro-inflammatory Responses by Human Macrophages to an Amoebae Host-Adapted Legionella Effector

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Further studies on bovine serum amylase - the effect of gel buffer pH

This paper describes the effect of gel buffer pH on the resolution of bovine serum amylase (Amylase I) isozymes in starch gel and the consequences for the understanding of the genetics of this locus. The two main findings are: (1) the existence of a satellite isozyme E to isozyme C which at pH 7.3 has the same mobility as the B isozyme but which at pH 8.0 migrates slower than B, and (2) the finding of three alleles AmI A, AmI B and AmI C in British cattle populations previously reported as having only AmI B and AmI C .     

Inhibitory activity of Catharanthus roseus alkaloids on enzyme activity and reproduction in Euproctis fraternal (Lepidoptera: Lymantridae)

Studies on the effect of Catharanthus roseus alkaloids on the biology of Euproctis fraterna showed that at a dose of 10 ppm, only 19.25% fertile eggs were laid. The hatchability was totally suppressed at higher doses. There was a considerable reduction in total carbohydrate and protein content in treated larvae. The activity of digestive enzymes were also found to be inhibited.     

Testing genetic models in populations which contain pedigree errors

In a genetic analysis of a polymorphic system, differences between the observed type of an individual and that expected from the parental types can arise either from an incorrect model or from pedigree errors. Such pedigree errors can cause severe difficulties in studies of the mode of inheritance of a novel polymorphic system. A method is proposed which overcomes the problem by including sire and dam error rates explicitly in the genetic model. The error rates are estimated by maximum likelihood, and likelihood ratio tests used to compare different models or estimates from different data sets. The proposals are applied to a study of the inheritance of the bovine serum AmI amylases.     

The effect of adipokinetic hormones on the activity of digestive enzymes

The role of the adipokinetic hormone (AKH) in the control of protease, amylase and lipase activities is examined using the cockroach Periplaneta americana and the fruit fly Drosophila melanogaster as model species. The effects of Peram‐CAH‐I and ‐II on the activity of cockroach digestive enzymes in the gastric caeca and midgut are measured both in vivo and in vitro. The results show the activity of proteases, amylases and lipases in both parts of the gut: amylase activity is higher in the gastric caeca than in the midgut; lipase activity presents the opposite trend; and protease activity is similar in both organs. The applied hormones stimulate the activity of all digestive enzymes, although this stimulation is not uniform; AKHs affect enzymes selectively, and in some cases unequally, in the gastric caeca and midgut. No substantial differences between Peram‐CAH‐I and ‐II stimulation are recorded. The in vitro results demonstrate that AKH stimulates digestive enzyme activity directly. In agreement with the cockroach results, enzymatic activity in D. melanogaster larvae producing nonfunctional AKH is lower than that in the larvae with ectopically expressed Akh gene, where enzyme activity reaches or even exceeds that of the controls. Overall, the results demonstrate the active role of AKHs in the stimulation of digestive enzyme activity in insects.     

Modes of action of fraxinellone against the tobacco budworm, Heliothis virescens

Fraxinellone significantly reduced the relative growth rate, food consumption rate as well as the efficiency of conversion of ingested food into biomass of Heliothis virescens when incorporated into artificial diets at concentrations of 4.31 × 10⁻⁵ mol/L and above. After being fed with fraxinellone-treated diets for 24 h, the larval midguts of H. virescens possess significantly lower activities of α-amylase and non-specific proteases and higher activities of cytochrome P450s. In vitro , the compound did not inhibit the activities of α-amylase and non-specific proteases extracted from the larval midguts. Clear evidence of post-ingestive toxicity of fraxinellone to midgut cells was observed under an electron microscope. The modes of action of the compound against insects were discussed.