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Biomedical subjects

G M Khalil

Publications and source records attributed to G M Khalil.

At least 19 recordsLinked to original sources
PubMed2001

Observations on the structure and histology of the female genital system of the cattle tick Boophilus annulatus (Say).

Female genital system of Boophilus annulatus was examined grossly on the day of drop-off from the host and grossly and microscopically on 4th day. It consists of an ovary, 2 oviducts, a common oviduct, a connecting tube, a seminal receptacle, a vagina divided into cervical and vestibular parts, 2 accessory glands and Gene's organ. The ovary oocytes undergo excessive growth during the 4 days after drop-off from the host. Oocytes accumulate eosinophilic material during growth and undergo histological changes similar to those seen in other ixodid ticks. Further ultrastructural studies are required to understand the vector capacity of this species in transmitting disease agents.

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PubMed1996

Effect of 25-azacholestane on Argas (Argas) hermanni (Ixodoidea:Argasidae).

Unfed and fed nymphal Argas hermanni Audouin were treated topically with 1, 5, 10, 15, and 20 micrograms of 25-azacholestane. The azasteroid did not inhibit feeding but had a dose-related lethal effect on unfed nymphs. Generally, it had little effect on nymphs treated after feeding. The 10-micrograms dose reduced the premolting period of nymphs treated before feeding. Some adults emerging from the 5- to 20-micrograms dosage groups that had been treated before feeding failed to shed their exuvia and others also had deformed legs. Greater numbers of adult females emerged from nymphs treated before feeding. The preoviposition period was almost the same in control females and of female mates, with males emerging from treated nymphs. Females from nymphs treated before feeding have a prolonged preoviposition period. Fecundity was reduced when males were treated with 10-20 micrograms as unfed nymphs. Egg hatch was reduced for females treated with 15 and 20 micrograms as fed nymphs, females treated with 5 and 10 micrograms as unfed nymphs, and as progeny of males treated with 10 micrograms as unfed nymphs. Results suggest possible interference with juvenile hormone titer in treated ticks.

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PubMed1994

Biochemical changes in the coxal organ proper and accessory glands of female Ornithodoros (Ornithodoros) savignyi at different physiological conditions.

Changes in the total protein, DNA, RNA, lipid and phospholipid concentrations in the coxal organ proper and accessory glands of Ornithodoros (Ornithodoros) savignyi (Audouin) were studied. There was an increase in the total protein, DNA, RNA, lipid and phospholipid content of the coxal organ proper in the female upto 6-days after feeding, then the concentration decreased. Also, the content of protein, DNA, RNA, lipid and phospholipid in the coxal organ proper of the seventh nymphal instar were similar to unfed females. Accessory glands showed an increase in protein, DNA, RNA, lipid and phospholipid content that reached its maximum on day 8 after feeding in females, then decreased.

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PubMed1991

Nucleic acid levels in the developing ovaries of Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae).

Protein and nucleic acid levels from the ovaries of Hyalomma dromedarii Koch were determined during different stages of oogenesis. The concentrations of total protein, DNA, and RNA increased during oogenesis, reflecting the rapid developmental changes taking place in this tissue. Peak protein and DNA levels were reached in the fully fed females, whereas RNA level peaked slightly earlier. Ribosomal RNA (rRNA) was found to be composed of 27.0s, 17.0s, and 4.1s particles. The ratio of 27.0s to 17.0s varied within the developing ovary, yet the 27.0s/4.1s ratio remained constant. The nucleotides of total RNA and rRNA were determined, and the ratio of purine/pyrimidine equaled approximately 1 and remained unchanged during oogenesis.

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PubMed1990

Biochemical changes in Hyalomma (Hyalomma) dromedarii (Acari: Ixodidae) embryos and effect of 20-hydroxyecdysone applied to the mother.

Changes in DNA, RNA, total lipids, phospholipids, and proteins and the activity of certain enzymes and pattern of their isozymes were studied in Hyalomma dromedarii Koch during embryogenesis. Total proteins fluctuated with a net increase (P less than 0.05) on day 20. Total lipids increased during the first half of embryogenesis and then declined with a net decrease to about 60% of the original level. Total phospholipids decreased to half this original level. DNA content increased greatly during cleavage, gastrulation, and organogeny and RNA increased during cleavage and blastula formation. Glucose-6-phosphate dehydrogenase (G6PDH) activity decreased (P less than 0.05), reaching 20% of its original level on day 12. Malic acid dehydrogenase (MDH) activity remained nearly unchanged throughout embryogenesis. Lactic acid dehydrogenase (LDH) activity increased greatly, with the highest level on day 14 with no further change. Acetylcholinesterase (AchE) activity increased greatly during the first 12 d, with no significant change thereafter. Acid (ACP) and alkaline (ALP) phosphatase activity increased during the first 12 d and declined returning to the original level on day 20. Seven AchE and 5 LDH isozymes were detected during different embryogenesis stages. Two MDH, 2 ACP, 1 ALP, and 2 G6PDH isozymes were detected throughout embryogenesis. Treating the mother with 20-hydroxyecdysone was associated with increases in protein and RNA contents and G6PDH and AchE activity and with decreases in ACP and ALP activity in the embryos.

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PubMed1990

Effect of unfed female weight on the biology of Hyalomma (Hyalomma) dromedarii Koch (Acari: Ixodidae).

Unfed female Hyalomma (Hyalomma) dromedarii Koch in 3 different weight groups of 2.4-5.0, 5.3-10.0 and 10.3-14.5 mg, respectively, were investigated for the effect of unfed female weight (UFW) on certain biological parameters. The results showed that the correlation between UFW and the duration of the feeding, preoviposition and oviposition periods varies greatly among the different weight groups and the pooled data. Engorged female and egg mass weights were strongly correlated with UFW of the smallest female group, and the degree of correlations decreased with increase of UFW in the other weight groups. The residual female weight (after oviposition cessation) was strongly correlated with UFW for all weight groups. The egg mass weight was strongly correlated with engorged female weight and the conversion efficiency index was similar for all weight groups. The oviposition pattern for the different weight groups and pooled data appeared similar but peak oviposition values were lacking for the largest female group. The results obviate the necessity of accurate random sampling of the entire tick population or specifying the UFW when studying ixodid biology.

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PubMed1989

Biochemical effects of juvenile hormone III on the tick, Argas (Persicargas) arboreus (Acari: Argasidae), during embryogenesis.

The biochemical effects of juvenile hormone III (JH III) on developing embryos from treated female Argas (Persicargas) arboreus Kaiser, Hoogstraal and Kohls were examined. Exogenous JH III resulted in a decrease in total proteins (P less than 0.001) only during the first 2 d of embryogenesis. There was no significant difference (P greater than 0.05) between RNA and DNA content in eggs from control and JH III-treated females. No significant difference (P greater than 0.05) was observed between control and JH III eggs in their lipid or phospholipid contents throughout embryogenesis. A total of 14-17 protein bands and 6-8 glycoprotein bands were separated by electrophoresis during embryogenesis of A. arboreus with some differences in mobility ratio between bands from control and JH III eggs. Differences in activity and isozyme patterns of malic acid, lactic acid, glucose 6-phosphate dehydrogenase, acid phosphatase, and alkaline phosphatase were not observed during embryogenesis of control and JH III-treated A. arboreus. Differences were observed in esterase activity.

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PubMed1988

Effect of 20-hydroxyecdysone on neurosecretory cell activity in female Hyalomma dromedarii synganglion (Acari: Ixodidae).

Twenty micrograms of 20-hydroxyecdysone (20-HE) were applied topically to nymphal Hyalomma dromedarii Koch on the day of detachment. In emerging adult females, some neurosecrtory cells (NSC) in certain synganglion centers exhibited changes in size and/or neurosecretory material (NSM) shape, distribution and/or quantity. These changes were compared with those normally occurring in untreated unfed, semifed virgin and mated, and engorged females. 20-HE effects included (a) accelerating the changes induced by mating and/or feeding in certain NSC, (b) reducing, to various extents, NSC response to mating and feeding, and (c) inducing changes in some NSC which do not normally exhibit any changes in untreated females. The results suggest that (a) most female NSC respond more or less similarly to indigenous 20-HE, (b) 20-HE may have a role as a positive feedback regulator for NSM synthesis and/or release by certain NSC, (c) the response to 20-HE may be primarily a function of NSC location in the synganglion, and/or (d) NSC considered to be of one type may actually belong to different cell types.

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PubMed1984

Fecundity-reducing pheromone in Argas (Persicargas) arboreus (Ixodoidea: Argasidae).

Fed adult Argas (Persicargas) arboreus produce a fecundity-reducing pheromone which affects all or most females in crowded conditions. Unfed adults and unfed and fed nymphs do not produce this pheromone. The effect of this pheromone is probably additive, increasing with additional crowding of adults. Mechanical disturbance is excluded as the cause of fecundity reduction. Fed females separated by a perforated barrier from crowded adults also exhibit very low fecundity. Adult excretory materials used 31 days post-feeding do not contain the fecundity-reducing pheromone. Preliminary experiments suggest that this pheromone is spatially limited in action, does not affect gonadotropic hormone synthesis and/or release, and does not induce oviposition deterrence behaviour. This may be considered to be a primer pheromone, causing alteration in normal vitellogenin synthesis and/or uptake and deposition in oocytes. The source and chemical nature of this pheromone should be investigated.

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PubMed1984

Borrelia crocidurae localization and transmission in Ornithodoros erraticus and O. savignyi.

Borrelia crocidurae infection rates in different organs of adult Ornithodoros (Pavlovskyella) erraticus and O. (Ornithodoros) savignyi were studied at intervals during a 60-day period following an infective meal. The spirochaetes persisted in tick guts for 1 month, were first observed in other organs 1-7 days post-feeding, and persisted for 20-60 days in different organs. The ovaries, Gene's organ, testes and male accessory glands of only O. erraticus were infected. The infection rates in adult and immature O. erraticus and O. savignyi post-feeding on infected hamsters were 26.7-60 X 0% and 26.7-80.0%, respectively. Spirochaete trans-stadial transfer from originally infected larval O. erraticus to first-instar nymphs (N1) was 33.3%; to subsequent N2-N5 it was 40.0-60.0%. Infection rates in the resulting adults were 26.7% (males) and 46.7% (females). In O. savignyi, trans-stadial transfer from originally infected N1 to N2 was 26.7% and to subsequent N3-N7 13.3-33.3%; of the resulting males and females, 20.0% were infected. Transovarial transmission from female O. erraticus infected as adults occurred after the second gonotrophic cycle to 33.3-53.3% of the F1 larvae, and to 26.7 and 46.7% of the F1 males and females, respectively. All infected F1 females transmitted the spirochaetes to 26.7-73.3% of the F2 larval progeny after the first gonotrophic cycle. Transovarial transmission was not observed in O. savignyi.

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