Laboratory colonization of Anopheles quadriannulatus from sympatry with other sibling species of the Anopheles gambiae complex in Zimbabwe

Abstract. A laboratory colony of the mosquito Anopheles quadriannulatus was established from a wild population occurring sympatrically with An.arabiensis in Zimbabwe. These sibling species are members of the An.gambiae Giles complex and were distinguished primarily by means of their specific polytene chromosome banding patterns. By using an ox-baited trap, we sampled selectively for the more zoophilic An.quadriannulatus. It was confirmed that An.quadriannulatus has the diagnostic slow allozyme of aspartate aminotransferase (AAT^95/95). In a mixed population under laboratory conditions, An.arabiensis displaced An.quadriannulatus within eight generations, without introgression. Colonization of An.quadriannulatus was facilitated by pooling the progeny from wild-caught mothers of confirmed identity and by using a specially adapted cage to promote mating.     

Activity, isoenzymes and purity of mushroom tyrosinase in commercial preparations

Several lots of commercial tyrosinase preparations were examined with regard to their enzyme activity, isoenzyme composition and purity. Enzyme activity toward catechol, -dopa and tyrosine showed significant variations from lot to lot and activation by SDS. Distribution of isoenzyme forms also varied from lot to lot. Comparisons of electrophoretic and isoelectric focusing protein profiles showed considerable differences and distributions of the proteins in each sample. Tyrosinase appeared to be a minor component in each preparation when compared to a partially purified enzyme. Investigators using commercial tyrosinase should exercise caution in interpreting data due to the presence of different isoenzyme forms, their distribution in various lots, and the presence of numerous other proteins.     

Human succinate dehydrogenase: Biochemical and genetic characterization

A simple procedure for the preparation of soluble human succinate dehydrogenase is described. These preparations have proved suitable for analysis by zone electrophoresis, using a specific stain to detect activity after separation. In a survey of succinate dehydrogenase from various tissues and different individuals, no evidence for genetic heterogeneity due to the expression of either multiple loci or alternative alleles at the succinate dehydrogenase locus was found. However, epigenetic heterogeneity in both molecular size and charge was seen and various explanations for the occurrence of the isoenzymes are explored. Estimates of molecular size (93,300 ± 9100) suggest that the smallest active unit of succinate dehydrogenase accounts for the major part of the solubilized activity. Kinetic studies have shown that the apparent K _m values for succinate (0.9mm) and PMS (0.4mm) are comparable to those previously described for the beef heart enzyme, and these parameters were not significantly altered when the enzyme was removed from the membrane milieu. However a marked non-succinate-dependent activation of the membrane-associated enzyme at 38C is apparently lost on solubilization, and this observation may have some bearing on earlier reports of an apparent decrease in V _max on solubilization of succinate dehydrogenase.     

Five Trypanosomatid Species of Insects Distinguished by Isoenzymes*

SYNOPSIS Blastocrithidia culicis, Crithidia deanei, Crithidia fasciculata, Herpetomonas samuelpessoai, Leptomonas seymouri and Leishmania tarentolae grown in cultures were compared by electrophoretic mobility for isoenzymes in 6 enzymes. All species were found distinct in these characteristics. Endosymbiotic C. deanei, which was identical to the aposymbiotic C. deanei in 5 enzymes, had an extra band in aspartate aminotransferase. No differences in isoenzymes were found between members of one species maintained in 2 different culture media.     

The role of peroxidases in pistil-pollen interactions

Summary The majority of pistil peroxidases are involved in processes related to growth, development and senescence. Only the tissue specific peroxidases in the transmitting tissue of the style may play a direct role in the regulation of pollen tube growth. The pollen peroxidases may function mainly in growth regulation and tube wall formation and play a role in the interaction between pollen and pistil by metabolizing the phenolic compounds in the pistil.     

Sur la presence de deux isoenzymes de la phenylalanine-ammoniac-lyase chez Aesculus hippocastanum

By using the normal techniques of protein separation, two forms of PAL with different properties have been separated from the glandular tissue of Aesculus hippocastanum. A hypothesis is proposed for correlating the isoenzyme activities with the accumulation of flavonoid compounds and benzoic acids in the trichomes.     

Functional Analysis of the N-Terminal Prepeptides of Watermelon Mitochondrial and Glyoxysomal Malate Dehydrogenases*

Mitochondrial and glyoxysomal malate dehydrogenase (mMDH; gMDH; L-malate: NAD⁺ oxidoreductase; EC 1.1.1.37) of watermelon (Citrullus vulgaris) cotyledons are synthesized with N-terminal cleavable presequences which are shown to specify sorting of the two proteins. The two presequences differ in length (27 or 37 amino acids) and primary structure. Precursor proteins of the two isoenzymes with site-directed mutations in their presequences and hybrid precursor proteins with reciprocally exchanged presequences were analyzed for proper import using two approaches, namely in vitro using isolated watermelon organelles or in vivo after synthesis in the heterologous host, Hansenula polymorpha. The mitochondrial presequence is essential and sufficient to target the mature glyoxysomal isoenzyme into mitochondria (Gietl et al., 1994). As to the function of the mitochondrial presequence a substitution of ^?3R (considered important for one step precursor cleavage in yeast and mammals) with ^?3L permitted import into mitochondria but cleavage of the transit peptide and conversion into active mature enzyme was impeded. Substitution of ^?13R^?12S (in a sequence reminiscent of the octapeptide motif serving as a substrate for the mammalian and yeast intermediate peptidase) into ^?13L¹²F permitted mitochondrial import and processing like the wild type transit peptide. Purified rat mitochondrial processing protease, which can effect single step cleavage of mitochondrial protein precursors, cleaves in vitro translated watermelon mMDH precursor into its mature form. The glyoxysomal presequence is essential and sufficient to target the mature mitochondrial isoenzyme into peroxisomes of Hansenula polymorpha, but these peroxisomes lack a processing enzyme to cleave the presequence (Gietl et al., 1994). We here show that isolated watermelon organelles also import the hybrid proteins in vitro and process the glyoxysomal presequence. Site directed mutations within the conserved RI-X₅-HL-motif impede efficiency of import and cleavage by watermelon organelles.     

Location of genes on chromosome arms in the Anopheles gambiae group of species and their correlation to linkage data for other anopheline mosquitoes

The use of paracentric inversions as genetic markers in the Anopheles gambiae group of mosquitoes is described. The gene for dieldrin resistance is assigned to chromosome 2 which in turn is correlated to the previous assignment of the gene to linkage group II. The locus of the enzyme phosphoglucomutase 2 (Pgm 2) is similarly assigned to chromosome 2 and evidence is presented for possible linkage between Pgm 2 and dieldrin resistance. There was no linkage or correlation of chromosome 2 and loci of the enzymes superoxide dismutase (Sod) and octanol dehydrogenase (Odh). These genes are therefore assumed to be on chromosome 3 (linkage group III). Evidence that such gene linkage group/chromosome correlations may extend to other species for which chromosome maps and homologies have been worked out is discussed.     

Isoenzyme pattern of superoxide dismutase in different varieties of citrus plants

Superoxide dismutases (SOD; EC 1.15.1.1) in leaves from different cultivars of citrus plants were characterized using isoelectric focusing in polyacrylamide gels. The plants studied included Citrus limonum R. (cvs Verna, Fino, and Eureka), C. paradisi Mac (cvs Red Blush and Marsh), C. aurantium L. (cv. Comun), C. sinensis L. Osbeck (cvs Navel, Valencia, and Salustiano), and C. reticulata B. (cv. Satsuma). The three molecular forms of SOD were distinguished from each other by their different sensitivity to cyanide and H₂O₂. In C. limonum leaves, four Cu,Zn-SODs, three Fe-SODs and two Mn-SODs were present. However, in leaves from different varieties of C. sinensis, C. paradisi, C. aurantium and C. reticulata the activity and number of Fe-SOD isoenzymes were lower than in lemon leaves, whereas the number of MN-SOD isozymes was increased. Cu,Zn-SODs did not show significant variations in the different species and cultivars. The identification of Fe-SODs in several species of the plant family Rutaceae extends the small number of higher plants where the presence of these Fe-containing metalloenzymes has been demonstrated. Results obtained may be useful from an evolutionary viewpoint and also in mineral nutrition studies using SOD isozymes as markers of functional metals.