cDNA coding for two digestive lysozymes (MdL1 and MdL2) of the Musca domestica housefly was cloned and sequenced. MdL2 is a novel minor lysozyme, whereas MdL1 is the major lysozyme thus far purified from M. domestica midgut. MdL1 and MdL2 were expressed as recombinant proteins in Pichia pastoris, purified and characterized. The lytic activities of MdL1 and MdL2 upon Micrococcus lysodeikticus have an acidic pH optimum (4.8) at low ionic strength (µ = 0.02), which shifts towards an even more acidic value, pH 3.8, at a high ionic strength (µ = 0.2). However, the pH optimum of their activities upon 4-methylumbelliferyl N-acetylchitotrioside (4.9) is not affected by ionic strength. These results suggest that the acidic pH optimum is an intrinsic property of MdL1 and MdL2, whereas pH optimum shifts are an effect of the ionic strength on the negatively charged bacterial wall. MdL2 affinity for bacterial cell wall is lower than that of MdL1. Differences in isoelectric point (pI ) indicate that MdL2 (pI = 6.7) is less positively charged than MdL1 (pI = 7.7) at their pH optima, which suggests that electrostatic interactions might be involved in substrate binding. In agreement with that finding, MdL1 and MdL2 affinities for bacterial cell wall decrease as ionic strength increases.
The use of accurate and reliable techniques for sex determination of wild birds is of special importance in captive breeding programs, especially in birds with monogamous, aggressive behavior, with absence of copulation, and with a low hatching rate. Using PCR, we evaluated the relative efficacy of primers HPF/HPR and CHD1Wr/NP/CHD1Zr in the amplification of the chromo-helicase-DNA binding 1 (CHD1) gene for sex determination in Penelope albipennis and 8 other species of cracids, 4 species of falconids, 4 species of accipitrids, and 3 species of psittacines. Primer effectiveness was compared using previously sexed bird samples. The HPF/HPR primer set was found to demonstrate a better performance and reliability. Therefore, these primers should be used to determine the sex of juvenile birds to avoid or minimize incompatibilities during the selection of potential breeding pairs.
The Anopheles merus (Diptera, Nematocera, Culicoidea) alpha-amylase gene (AmerAmy, GenBank Accession Number U01210) was amplified with its own or with the Zabrotes subfasciatusalpha-amylase signal peptide (ZsAmerAmy, GenBank Accession Number AY270183) by PCR, using designed primers. The AmerAmy gene was sequenced from its promotor to the TGA codon. As a positive control, the Z. subfasciatusalpha-amylase gene with its own signal peptide (ZsAmy, GenBank Accession Number AF255722) was also amplified by PCR. These three sequences were inserted into the baculovirus genome using the Bac-to-Bac trade mark system. Recombinant baculovirus preparations were used to infect Sf9 Spodoptera frugiperda insect cells. The A. merusalpha-amylase was successfully expressed as an active enzyme detected mainly in cell culture supernatants.
A laboratory class was designed for the study of the ecology of amylolytic bacteria in soil, although other sources may be equally suitable for this purpose. Groups of three students carried out the following: (a) preparation and sterilization of medium and plates, (b) collection and preparation of soil samples, spreading the samples on the plates, (c) incubation of the plates at 373C overnight, a further 1 h incubation at 603C to observe amylolytic activity due to thermophilic bacteria, and (d) interpretation and discussion of the results. These tasks are accomplished in two periods of 4 h on consecutive days. No sophisticated instruments are required for these experiments, which can be carried out in three classes of 4 h each. On the "rst day the students prepare culture media, bu!ers and reagents, as well as collect and grow soil samples. The second day is spent for both taxonomic identi"cation of colonies and the HAI determination.
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