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R Galun

Publications and source records attributed to R Galun.

At least 37 records · Page 2Linked to original sources
PubMed1990

Systemic activity of ivermectin on the human body louse (Anoplura: Pediculidae).

Eighty-one to 100% of nymphs and females of the human body louse (Pediculus humanus humanus) that fed artificially on blood containing 2.5-10 ng ivermectin/ml died. The mortality of nymphs and female lice fed on rabbits treated with 200 micrograms/kg ivermectin was very high during the first two to three days, then declined sharply, reaching the level of the controls on day six. Nymphs were more sensitive than females. The average number of eggs laid by surviving females and the percentage that hatched from those eggs were lower than in controls.

Animals↗
PubMed1988

Purinergic reception by culicine mosquitoes.

1. Adult female Culex pipiens and Culiseta inornata have purinergic receptors that respond to extracellular ADP and related compounds. Stimulation of these receptors caused ingestion of artificial diets. Addition of bicarbonate to the saline solvent enhanced the phagostimulatory effect. Saline-bicarbonate was as effective a solvent as blood plasma for Cx. pipiens, and was used in the dose-effect determinations. Ranking of the potencies was: ADP greater than AMP-PNP greater than ATP = AMP greater than AMP-PCP much greater than 2'dAMP greater than 2'dADP greater than 2'dATP. At 1 mM concentration, ITP, GTP, CTP, UTP, c-AMP, 2'AMP, 3'AMP, DPG, or GSH + glucose caused fewer than 50% of the insects to gorge, as did 2'3'dd-ATP, A tetra P, and AMP-CPP at 100 microM. 2. The potency ranking for Cu. inornata was: ADP greater than AMP-PNP greater than ATP greater than AMP-PCP much greater than AMP much greater than AMP-S. The concentrations required to produce the ED50 response (inducing 50% of the test insects to gorge) were much higher than those required for Cx. pipiens; however, saline, not saline-bicarbonate, was used as the solvent. With the exception of the very low potency of AMP for Cu. inornata, the ADP potency index values for the other chemicals tested on both species are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Physiological characteristics of Culex pipiens populations in the Middle East.

We determined whether exposure to a short day-light regime of 14 h 15 min induces ovarian diapause in Culex pipiens L. mosquitoes from Israel and whether differences occur in certain morphological, physiological and behavioural traits. Samples from nineteen localities in Israel, from 33 degrees 05' N to 29 degrees 35' N latitude, conformed to the morphological criteria of Cx pipiens, sensu stricto (i.e. wider spread of dorsal than of ventral arms of the aedeagus) as determined by negative DV/D ratios of the male. Autogenous females occurred at frequencies of 4-55% in all areas of Israel throughout the breeding season. No mating barriers were detected between individuals of autogenous and anautogenous genotypes. Autogenous females were no more prevalent from polluted or enclosed breeding sites than from others with various degrees of openness. In general, Cx pipiens females fed equally well on human (35% engorgement) and avian (22% engorgement) hosts (P less than 0.01). Although females from the southern part of the study region appeared to be incapable of ovarian diapause, at least some of those from the north experienced diel-mediated diapause. We conclude that, in the Middle East, the 33rd parallel provides a southern limit to the range of Cx pipiens with capability for diel-mediated ovarian diapause, but that non-diapausing Cx pipiens s.l. are present at least as far south as Elat (20 degrees 25' N) on the coast of the Gulf of Aquaba.

Animals↗
PubMed1987

The saliva of the medicinal leech Hirudo medicinalis--I. Biochemical characterization of the high molecular weight fraction.

1. A method is described for obtaining dilute Hirudo medicinalis saliva by feeding leeches through a membrane on arginine/saline and squeezing them immediately after from the posterior end forwards. The process can be repeated at intervals. Yields are considerably higher than from salivary gland extracts. 2. Hirudo saliva contains hirudin, eglin, hyaluronidase, collagenase and apyrase. Leech collagenase and apyrase are here reported for the first time. 3. On gel filtration of lyophilized saliva, activity peaks were well defined. Approximate molecular weights were determined. Apyrase appears in two forms with optimum activity around pH 7.5. Collagenase was identified as belonging to the mammalian type.

Adenylate Kinase↗
PubMed1987

The saliva of the medicinal leech Hirudo medicinalis--II. Inhibition of platelet aggregation and of leukocyte activity and examination of reputed anaesthetic effects.

1. Leech saliva inhibits platelet aggregation induced by collagen, ADP and epinephrine. 2. Leech saliva inhibits superoxide production by neutrophils stimulated by tetradecanoyl phorbol acetate or polyhistidine. The effect is due in part at least to eglin. 3. Reputed anaesthetic effects of leech saliva were not detected.

Adenosine Diphosphate↗
PubMed1987

The evolution of purinergic receptors involved in recognition of a blood meal by hematophagous insects.

Many blood feeders use adenine nucleotides as cues for locating blood meal. Structure-activity relationship of adenine nucleotides as phagostimulants varies between closely-related species of blood feeders. It is suggested that a preexisting diverse pool of nucleotide-binding proteins present in all living cells, serves as a source of receptor proteins for the gustatory receptors involved in blood detection. It is proposed that the selection of any such nucleotide-binding protein is random.

Adenine Nucleotides↗
PubMed1980

Feeding behaviour of tsetse flies infected with salivarian trypanosomes.

Although much is known about factors which determine infection rates of salivarian trypanosomes (subgenera Nannomonas, Duttonella and Tryanozoon) in the tsetse fly Glossina, it is not clear why infection rates of Trypanozoon are high in mammalian hosts but low in wild-caught Glossina and why trypanosomiasis occurs where Glossina is not readily detectable. We report here that the feeding behaviour of trypanosome-infected Glossina differed from that of uninfected control flies. Infected flies probed more frequently and fed more voraciously. We describe a specific relationship between trypanosomes and the mechanoreceptors responsible for detecting the rate of blood flow, and show how infection affects that rate in the labrum. We suggest that the observed differences in feeding behaviour result from impaired function of the labral mechanoreceptors in infected Glossina.

Animals↗
PubMed1976

Protease activity in female Ornithodoros tholozani ticks.

The protease activity in guts of Ornithodoros tholozani females was studied in vitro. The intracellular protease in Ornithodoros tholozani guts has a pH optimum of about 3.0. Hemoglobin is the preferred substrate, and bovine serum albumin is digested very slowly. In this respect the protease resembles cathepsin D. Unfed ticks contain a small amount of protease in the gut. After feeding the level of protease increases gradually for several days until peak protease activity is attained. The level of gut protease activity depends on the size of the blood meal taken and on the interval after feeding. After a period of peak protease activity, the level of protease declines. The level of gut protease in unmated females (kept at 27 degrees C) did not reach prefeeding levels within 100 days. The level of gut proteolytic activity, as determined by in vitro protease assays, does not reflect the degree of blood digestion which takes place in vivo. After a period of rapid digestion, lasting for about two weeks, the undigested part of the blood meal remains unchanged in the lumen of the gut. At that time the gut tissue contains considerable levels of protease, which can be demonstrated by in vitro assays. Presumably, the protease remains active inside the gut cells, although the uptake of hemoglobin from the gut lumen has ceased. The results are compared to those obtained in other tick species.

Animals↗