The haemagglutination activity in the different developmental stages and changes of this activity caused by analogues of insect hormones in two members of the Culex pipiens complex of mosquitoes

Abstract. Haemagglutination activity was studied in last larval instars, pupae and adults of both sexes of the Culex pipiens mosquito complex. In females of Culex pipiens quinquefasciatus Say, an anautogenous member of C. pipiens complex, activity was detected in the homogenate of the head‐thorax complex, gut and remaining abdomen (after removing the gut), before and after sucking water, glucose solution or blood. Similar investigations were made in females of autogenous Culex pipiens molestus Forskal, a member of the same mosquito complex. The results were compared with data obtained for males of these subspecies, plus the larvae and pupae. The results show that haemagglutination activity in adult females depends not on the sucking of blood, but on the age of the females. In newly emerged females, the level of activity was very low, but after 24 h or 48 h of activity was highly enhanced, even in females that had no possibility to suck water or other liquids including blood. Furthermore, in C. p. molestus, the haemagglutination activity does not change in hungry or engorged females, and a high level of activity was found in the gut of last larval instars, a developmental stage that never takes blood. Treatment with methoprene reduces haemagglutination activity in both sexes, but 20‐hydroxycdysone application decreased activity in the gut of females. It is suggested that haemagglutination activity may be regulated indirectly by the endocrine system. The possibility that haemagglutination activity may depend on some aspect of the digestive system that has no direct connection to blood uptake is discussed. In addition, the activity may be important not only for the elimination of infections, but also for the processing of food and the utilization and transport of nutrients.     

Daily activity of the pest slug Arion lusitanicus under laboratory conditions

The daily activity of the slug Arion lusitanicus was studied using time‐lapse video analysis in the laboratory. Under constant temperature (18°C) and 16–h photoperiod, the activity of slugs was measured in half‐hourly periods as locomotor activity, feeding or resting. Track lengths were determined using image analysis. Locomotion of A. lusitanicus was greatest at 5:30, 1.5 h after sunrise, and at 20:30, 1 h after sunset; least locomotor activity occurred between 13:00 and 14:00. The mean distance travelled by A. lusitanicus in 24 h was 10.8 m. The largest slug was the most active and the smallest the least. Slugs spent 68% of 24 hours resting, mainly under artificial shelter traps, 27% in locomotion and 4% feeding. Feeding occurred mainly during the hours of dakness (76%). All categories of behaviour investigated varied greatly between individuals and also between times of day. Homing to artificial shelters and other roost sites was regularly observed within 24 h (41%), but decreased considerably thereafter. The behavioural patterns proved to be in agreement with those found in a previous field investigation and are therefore also discussed with a view to their importance in pest control.     

Fine structural recognition specificities of IgE antibodies distinguishing amoxicilloyl and amoxicillanyl determinants in allergic subjects.

IgE antibodies in the sera of subjects allergic to beta-lactam antibiotics detect a spectrum of specificities ranging from side-chain groups to an entire penicillin or cephalosporin molecule. In addition to such structural heterogeneity of allergenic determinants, IgE antibodies in the sera of different allergic subjects show heterogeneous recognition responses. Detailed immunochemical studies were carried out on the sera of penicillin-allergic subjects that showed selective and unexpected reactions with the frequently prescribed penicillin, amoxicillin. Antibodies from one subject reacted only with the amoxicilloyl determinant while IgE from another subject showed multiple reactivity with penicilloyl and penicillanyl determinants of different penicillins but not with the amoxicilloyl determinant. Quantitative hapten inhibition studies revealed that the combining sites of the former antibodies were complementary to amoxicillin in a form that permits binding to the hydroxyaminobenzyl side-chain and the thiazolidine ring carboxyl. These conditions are satisfied with the drug in the '-oyl' but not in the '-anyl' form which involves linkage through the 2-carboxyl of the thiazolidine ring. With the second serum, adsorption studies showed that the wide-ranging reactivity of IgE was due to a single population of antibodies that detected a common specificity on the different penicillins. Combining site studies revealed clear recognition of the benzyl portion of the side-chain of benzylpenicilloyl, benzylpenicillanyl, ampicilloyl, ampicillanyl and amoxicillanyl determinants when free antibody access to the side-chain was possible but little or no recognition of the ring hydroxyl of amoxicillin. Such uninhibited access may not occur, however, when amoxicillin is conjugated in the '-oyl' form since opening the beta-lactam ring allows increased flexibility and rotation of the molecule and the possibility of close association of the hydroxyaminobenzyl side-chain of amoxicillin with the linked peptide carrier. In such close steric association, H-bonding involving the ring hydroxyl and amino acids of the carrier may prevent antibody access to the side-chain region of the amoxicilloyl determinant.     

Identification of the 5-HT1A Receptor Binding Subunit in Rat Brain Membranes Using the Photoaffinity Probe [3H]8-Methoxy-2-[N-n-Propyl, N-3-(2-Nitro-4-Azidophenyl)Aminopropyl]Aminotetralin

The synthesis of a tritiated derivative of the 5-HT1A photoaffinity probe 8-methoxy-2-[N-n-propyl, N-3-(2-nitro-4-azidophenyl)aminopropyl]aminotetralin ([3H]8-methoxy-3'-NAP-amino-PAT) allowed the use of this probe for attempting the irreversible labeling of specific binding sites in rat brain membranes. Sodium dodecyl-sulfate-polyacrylamide gel electrophoresis of proteins solubilized from hippocampal microsomal membranes that had been incubated with 20 nM [3H]8-methoxy-3'-NAP-amino-PAT under UV light revealed a marked incorporation of 3H label into a 63-kilodalton protein termed PI. As expected of a possible correspondence between PI and 5-HT1A receptor binding sites, 3H labeling by the photoaffinity probe could be prevented by selective 5-HT1A ligands such as 8-hydroxy-2-(di-n-propylamino)tetralin, ipsapirone, buspirone, and gepirone and by N-ethylmaleimide, but not by the 5-HT2 antagonist ketanserin, noradrenaline- and dopamine-related drugs, monoamine oxidase inhibitors, and chlorimipramine. Furthermore, the regional and subcellular distributions of PI were identical to those of specific 5-HT1A binding sites. These results indicated that the binding subunit of the 5-HT1A receptor is a 63-kilodalton protein with a functionally important sulfhydryl group(s).     

Ca2+/Calmodulin Distinguishes Between Guanyl-5''-yl-Imidodiphosphate-and Opiate-Mediated Inhibition of Rat Striatal Adenylate Cyclase

The inhibition of adenylate cyclase from rat striatal plasma membranes by guanyl-5'-yl-imidodiphosphate [Gpp(NH)p] and morphine was compared to determine whether Gpp(NH)p-mediated inhibition accurately reflected hormone-mediated inhibition in this system. Inhibition of adenylate cyclase activity by Gpp(NH)p and morphine was examined with respect to temperature, divalent cation concentration, and the presence of Ca2+/calmodulin (Ca2+/CaM). Gpp(NH)p-mediated inhibition was dependent on the presence of Ca2+/CaM at 24 degrees C; the inhibition was independent of Ca2+/CaM at 18 degrees C; and inhibition could not be detected in the presence, or absence, of Ca2+/CaM at 30 degrees C. In contrast, naloxone-reversible, morphine-induced inhibition of adenylate cyclase was independent of both temperature and the presence of Ca2+/CaM. Mg2+ dose-response curves also reinforced the differences in the Ca2+/CaM requirement for Gpp(NH)p- and morphine-induced inhibition. Because Gpp(NH)p-mediated inhibition was independent of Ca2+/CaM at low basal activities (i.e., 18 degrees C, or below 1 mM Mg2+) and dependent on the presence of Ca2+/CaM at higher basal activities (24 degrees C, or above 1 mM Mg2+), the inhibitory effects of Gpp(NH)p were examined at 1 mM Mg2+ in the presence of 100 nM forskolin. Under these conditions, both Gpp(NH)p- and morphine-induced inhibition of adenylate cyclase were independent of Ca2+/CaM. The results demonstrate that the requirement for Ca2+/CaM to observe Gpp(NH)p-mediated inhibition depends on the basal activity of adenylate cyclase, whereas hormone-mediated inhibition is Ca2+/CaM independent under all conditions.(ABSTRACT TRUNCATED AT 250 WORDS)     

A novel wheat alpha-amylase gene (alpha-Amy3)

Summary A genomic clone of a wheat -amylase gene (Amy3/33) was identified, on the basis of hybridisation properties, as different from -Amy1 and -Amy2 genes which had been characterised previously. The nucleotide sequence revealed that this gene has the normal sequence motifs of an active gene and an open reading frame interrupted by two introns. The protein sequence encoded by this open reading frame is recognisably similar to that of -amylase from the -Amy1 and -Amy2 genes and there is high sequence homology in all three proteins at the putative active sites and Ca⁺⁺ binding region. In addition, the introns are at positions equivalent to the position of introns in the -Amy1 and -Amy2 genes. However, the sequence was less similar to -Amy1 and -Amy2 than these are to each other. Southern blot analysis showed that the Amy3/33 DNA is one of a small multigene family carried on a different chromosome (group 5) from either the -Amy1 or -Amy2 genes. A further difference from the -Amy1 and -Amy2 genes was the pattern of expression. Amy3/33 was expressed only in immature grains and, unlike the -Amy1 and -Amy2 genes, not at all in germinating aleurones. These data suggested therefore that this gene represents a third type of -amylase gene, not described before, which shares a common evolutionary ancestor with the -Amy1 and -Amy2 genes.     

Molecular genetics of met 17 and met 25 mutants of Saccharomyces cerevisiae: intragenic complementation between mutations of a single structural gene

Summary A method for transposon mutagenesis in Azospirillum lipoferum 29708 is reported with transposon Tn5. The suicide plasmid pSUP2021 was used to deliver Tn5 in A. lipoferum using Escherichia coli SM10 as the donor. Neomycin-resistant transconjugants were detected at a frequency of 6x10^-6 per recipient. Different types of mutants were isolated, e.g. auxotrophic, coloured, IAA-negative, and IAA-overproducers. Among the auxotrophic mutants, cysteine and methionine requirers prevailed. Random Tn5-insertion with only one copy per mutant was demonstrated by Southern blotting and hybridization. Tn5-induced mutants are relatively stable, with reversion rates of 2–20×10^-8. A gene which is a part of the carotenoid pathway is closely linked to the histidine genes. The existence of two pathways for IAA production in A. lipoferum is discussed.