Effects and duration of resistance acquired by rabbits on feeding and egg laying in Ixodes ricinus L.

Rabbits gradually developed a resistance against Ixodes ricinus ticks as a result of sequential experimental infestations. The resistance was characterized by an increase duration of feeding, by ticks engorging to a smaller extent and by reduced egg production. Once established, the immunity persisted for at least 9 months. Changes in the titre of circulating anti-I. ricinus antibodies was measured by indirect immunofluorescence.     

Passive transfer of resistance in rabbits infested with adult Ixodes ricinus L: humoral factors influence feeding and egg laying.

Parital immunity against the bites of female I. ricinus was transferred to normal rabbits by inoculating immune serum from resistant animals. Transferred humoral factors diminished the weight of the ticks' blood meal by 29% and increased the feeding period by about 1 day in comparison with ectoparasites engorged on controls. They provoked also the failure of egg laying by female I. ricinus. Only 55% of ticks fed on treated rabbits laid eggs (94% on controls). The immunological state of immune serum donors or recipients was studied and the IgG and homocytotropic specific anti-I. ricinus antibodies were identified. The immediate hypersensitivity of rabbits' skin was also controlled.     

Passive transfer of resistance in rabbits infested with adultIxodes ricinus L.: Humoral factors influence feeding and egg laying

Summary Partial immunity against the bites of I. ricinus was transferred to normal rabbits by inoculating immune serum from resistant animals. Transferred humoral factors diminished the weight f the ticks' blood meal by 29% and increased the feeding period by about 1 day in comparison with ectoparasites engorged on controls. They provoked also the failure of egg laying by I. ricinus. Only 55% of ticks fed on treated rabbits laid eggs (94% on controls). The immunological state of immune serum donors or recipients was studied and the IgG and homocytotropic specific anti-I. ricinus antibodies were identified. The immediate hypersensitivity of rabbits' skin was also controlled.The present work was supported by the Swiss National Fund for Scientific Research, grant No. 3.558.75.     

Rabbits infested with adultIxodes ricinus L.: Effects of mepyramine on acquired resistance

Summary The results of this work demonstrate that histamine seems to be involved in the expression of the resistance acquired by rabbits to I. ricunus. Daily treatment of animals with the H₁-antihistaminic mepyramine inhibited the effects of immunity. This observation applies to the effect of resistance on the weight of engorged ticks, the duration of the blood meal and the success of egg laying and hatching.The present work was supported by the Swiss National Fund for Research, grant No. 3.303-78. We are grateful to Dr L. Julou (Rhône-Poulenc) for a gift of mepyramine.     

Passage of hemolysins through the midgut epithelium of femaleIxodes ricinus L. fed on rabbits infested or reinfested with ticks

Summary Antibodies considered in this study are hemolysins synthesized by rabbits against sheep red blood cells. Ingested with the blood meal, they cross the tick midgut epithelium and retain their immunological properties in the hemolymph. During a reinfestation of rabbits, more ticks present these antibodies, and titres are generally higher than during a first infestation. Hemolysins are only found in ticks weighing 180 mg or more.The present work was supported by the Swiss National Foundation for Scientific Research, grant No. 3070.81.     

Correlation of ammonia liberation and calcium deposition by the avian egg and blood ammonia levels in the laying hen

Zusammenfassung Mittels biochemischer Daten wird der Nachweis erbracht, dass im Ovidukt des Huhnes während der Schalenbildung zwar vermehrt NH₄ ⁺ freigesetzt wird, jedoch eine negative Korrelation zwischen NH₄ ⁺-Produktion und Ca⁺⁺-Abscheidung besteht.

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Supported by a training grant from the U.S. Public Health Service No. 5-T1-DE-118. We thank Dr.P. R. Tramell for his help during the initial stage of this investigation.     

Effects of cerebral lateral,ventricular infusions of phloridzin on feeding and body weight in Gallus domesticus (L.)

Summary Contrary to earlier findings in rats, cerebral lateral ventricular infusions of 1×10^–3 M or 2×10^–3 M solutions of phloridzin at a rate of 2.5 l/min for 90 min had no significant stimulating effects on food intake and weight gain in hens and cocks. These different responses to intraventricular phloridzin might reflect a difference of sensitivity to the inhibitory action of phloridzin on glucose transport in cerebral cells or certain peculiarities of mechanisms controlling food intake in chickens.     

Effects of CMH on growth and alkaloid formation ofDatura metel L.

Zusammenfassung Hydrazoniumsalze bewirken eine Zunahme der Alkaloide Hyoscin und Hyoscyamin in Stengeln und Blättern, nicht aber in Wurzeln vonDatura metel.     

Effects of phthalimide on growth and alkaloid formation ofDatura metel L.

Summary When administered toDatura metel L. by foliar or root application, the new plant growth regulator phthalimide exercises a favorable effect on the vegetative growth and also stimulates the formation of tropane alkaloids.     

Effects of vaginal stimulation on hypothalamic single units in unanesthetized rabbits

Résumé Certains neurones hypothalamiques présentent dans la demi-heure qui suit une stimulation vaginale des modifications de leur décharge spontanée indépendantes de l'état de vigilance de l'animal. Ces variations pourraient être en rapport avec les mécanismes nerveux de l'ovulation provoquée chez la Lapine.

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We are very grateful to Dr. J. N.Hayward, Department of Anatomy, University of California, Los Angeles, for his constructive criticisms.     

Effects of fluoride on glycosaminoglycan of cancellous and cortical bone of rabbits

Summary The present report deals with the effect of excessive ingestion of fluoride on glycosaminoglycan (GAG). Increase in fluoride deposition in bone, and in circulating levels of fluoride in serum, are also reported. Among the 3 constituents of GAG investigated; hexosamine, uronic acid and sulphate, the content remained unaltered except for sulphate.Acknowledgment. The authors wish to acknowledge the Department of Science and Technology (DST), Government of India, for the financial aid. One of us (M.J.) acknowledges the receipt of a Junior Research Fellowship from DST, during the tenure of which the investigations were carried out.     

Registration of feeding behaviour in rats by recording food approach behaviour.

A method is described in which food approach behaviour of rats is recorded to study feeding behaviour. Between rats, differences in food approach behaviour were observed. For each rat, food approach behaviour was constant over a long period of time. This allows conversion of approach behaviour data into quantified feeding behaviour. Examples of long-term feeding behaviour and of reproducibility of food intake are given.     

Effects of feeding on healthy and diseased corn plants on a vector and on a non-vector insect

Insect-transmitted plant pathogens can have positive, negative or no effects on the vector insect. Effects could be direct (caused by the pathogen) or indirect (mediated by changes in the plant). Pathogen effects on non-vector insects are less well known.Peregrinus maidis (Ashmead) (Homoptera: Delphacidae), an insect that is not a vector of the corn stunt spiroplasma (CSS), weighed less 15 days after feeding on CSS-infected corn plants relative to insects feeding on healthy corn plants. Fecundity of non-vector insects that were removed from diseased plants was higher than for insects coming from healthy plants. ForDalbulus maidis (DeLong & Wolcott) (Homoptera: Cicadellidae), an insect that transmits CSS, there were no differences in weight, longevity, eggs per day, weekly or total fecundity after feeding on healthy or on CSS-infected corn plants. Significant differences in some phloem amino acids were detected between healthy and CSS-infected plants. Infected plants also showed an increased phloem acidity as disease symptoms progressed. Feeding on CSS-infected corn plants by an insect that does not vector the pathogen infecting the plant can have favorable consequences as evidenced by an increased fecundity.Scientific aritcle no. 8819, contribution no. A-6605 of the Maryland Agricultural Experiment Station.     

Influence of feeding conditions on wing,labellar and tarsal hair resistance inPhormia regina (Meig.)

Summary Feeding enhances resitance of wing, tarsal and labellar hairs ofPhormia regina Meig. The observed increase in resistance might be related to variations in the secretory function of the accessory cells at the hair sockets. The importance of this fact in feeding control is discussed.This work was partly supported by a grant from the Consiglio Nazionale delle Ricerche (CNR), Rome, Italy.     

Effects of various inhibitors of protein cross-linking on the formation of fertilization membrane in sea urchin egg

Résumé La stabilization de la membrane de fécondation de l'uf de l'OursinParacentrotus lividus est inhibée par la pénicillamine, l'isoniazide, les hydrazines benzylique et benzoïque et la semicarbazide. Les effets de ces substances sont interprétés sur la base de leur action inhibitrice sur la formation de certaines liaisons transversales intermoléculaires. Ces liaisons pourraient impliquer, comme chez le collagène et l'élastine, des groupes aldéhydes associés entre eux par condensation de type aldol ou avec de groupes aminés avec formation de base de Schiff.