SUMMARYA rapid method is described for preparing and staining salivary glands of Rhipicephalus appendiculatus ticks infected with Theileria parva. The technique, involving the use of a modified methyl green pyronin stain, minimizes the risk of losing material and allows examination of stained glands within minutes of preparation. The technique was applied in a series of studies in which ticks were either infected with T. parva under different conditions, or maturation of parasites in adult ticks was stimulated by different means. When nymphal ticks were fed on the ears of cattle the subsequent infection rate of the adult ticks showed no correlation with the parasitaemia of the cattle at the time of nymphal engorgement. There was no difference in infection rates between adult ticks in which parasite maturation had been stimulated either by incubation at 37 °C or by feeding on rabbits. However, parasite maturation took about 1 day longer in incubated ticks than in rabbit-fed ticks. Female ticks were consistently more highly infected than males, both in terms of the percentage of ticks infected and the mean number of infected acini/tick. Ticks were infected with T. parva by injection of nymphs with parasitaemic bovine blood, but the resultant adult infection was lower than that in ticks which had been infected naturally by feeding on cattle.

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The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.

The acute effects on plasma LH concentrations of an injection of oestradiol\x=req-\ 17\g=b\ were studied in 7 non-cyclic heifers and 19 freemartins. One freemartin showed a normal LH surge due to the positive feedback effect of oestrogen on the hypothalamus. Of the other 18 freemartins, 4 showed positive increases in plasma LH and 6 were unclassified. There was no correlation between the degree of chimaerism and responsiveness to oestrogen. The results also showed that injected oestradiol suppressed the spontaneous fluctuations of plasma LH.

SummaryRecent microscopic studies of Theilerial parasites in. ticks appear to provide convincing evidence for a sexual cycle for these parasites. This evidence would remove most of the objections to placing piroplasms in the same class as malarial and coccidial parasites. It is suggested, therefore, that the class Piroplasmasida (Piroplasmea) be abolished and that piroplasms be located in a sub-order Piroplasmorina alongside Haemosporina within the class Sporozoa (Teleospora).If the close relationship of Theilerial and malarial parasites is correct then by analogy meiotic or reduction division of Theileria probably occurs during sporogony in the tick salivary gland acinar cells. This means that all bovine stages are haploid. If these can be cloned and characterized by isoenzyme or drug resistance markers, then genetic recombinant studies, similar to those performed with malarial and coccidial parasites, could be conducted.The potential of genetic recombination greatly increases the scope of the parasite for developing new variants. This potential is greatest in areas where there is a variety of tick and host species which apply different types of selection pressure to parasites. Atypical strains of Theileria are usually isolated from such areas, and although the characteristics of these strains may not be expressed in the wild, unnatural selection by laboratory passage may reveal their presence. The apparent lability of such strains may simply be cloning of different genetic recombinants.If different strains can be cloned and characterized it may be possible by genetic recombination techniques to develop new clones which retain desired characters for use as avirulent protective vaccines, but from which undesirable characters have been eliminated.

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Summary: A method is outlined whereby Mycoplasma species growing in broth culture can be rapidly counted, using the relationship between the number of organisms and the mean lactate dehydrogenase (LDH) content of each organism. The uses of this technique are discussed.