Trypanosome infection rate in cattle at Nguruman, Kenya.

Trypanosome infection rate in cattle at Nguruman was investigated in a study conducted in 1984-1986. Shifting pastoralism significantly reduced trypanosome infections in cattle. The cattle were more heavily infected with Trypanosoma congolense (16.5%) than Trypanosoma vivax (4.95%) and Trypanosoma brucei (0.19%). Trypanosoma theileri was observed only once among the cattle examined. Mixed trypanosome infections in cattle were observed to be 2.75% and 0.014% for T. congolense/T. vivax and T. congolense/T. brucei, respectively. The duration of infection in the cattle was 55 days for T. congolense and 79 days for T. vivax. High infections in cattle were observed 2 months after the rains, which were concomitant with high tsetse densities.

Trypanosoma congolense: drug resistance during cyclical transmissions in tsetse flies and syringe passages in mice.

A drug-resistant Trypanosoma congolense strain with predetermined curative doses (CD50 and CD90) of samorin at 13.9 +/- 1.02 and 20.3 +/- 1.13 mg/kg body weight, respectively, was cyclically transmitted through tsetse flies and by syringe passages in mice in the absence of drug pressure. The changing levels of drug sensitivity were determined after every 3rd cyclic and 5th syringe passage intervals. It was noted that when the strain was maintained in tsetse flies through 12 cyclical transmissions, the CD50 and CD90 dropped slightly from 13.9 to 11.9 +/- 1.06 and from 20.3 to 18.0 +/- 1.08 mg/kg body weight, respectively. This decrease in the level of resistance was not significant (P greater than 0.05). However, when the trypanosomes were maintained by syringe passages in mice, there was a significant reduction (P less than 0.05) in the degree of resistance (CD50 from 13.9 to 11.4 +/- 1.07 and CD90 from 20.3 to 16.7 +/- 1.16 mg/kg), by the 15th syringe passage.

Selection for drug resistance in Trypanosoma congolense during cyclic transmissions through Glossina morsitans morsitans and drug treated rabbits.

A drug-sensitive Trypanosoma congolense (IL 1180 strain), with a known CD50 and CD90 (doses required to cure 50 and 90% of the infected animals) was cyclically passaged through tsetse flies. The infected flies were then fed on rabbits which received weekly prophylactic treatment of Samorin. It was observed that the infections arising from flies maintained for over 60 days on drug-treated rabbits required higher curative doses to achieve a 50 and 90% cure. The results of this work suggest that a selection for drug resistance occurs when trypanosome stage in Glossina is continuously exposed to drug-treated animals.

The effect of Trypanosoma brucei infection of the localization of salivary gland cholinesterase in Glossina morsitans morsitans.

When salivary glands of the tsetse fly, Glossina morsitans morsitans, are stained for cholinesterase (ChE) activity, a net-like pattern of reaction product is observed surrounding each epithelial cell of the gland's secretory region. Glands infected with Trypanosoma brucei brucei show a progressive reduction in this ChE activity as the parasites develop. When the infection is mature, ChE is rarely detected in the epithelial layer but appears in the lumen of gland. The luminal ChE responds to substrates and inhibitors in the same manner as the epithelium-associated enzyme and appears to have leaked from the epithelium due to cellular damage in epithelium of the infected gland. The possible effect of glandular damage on feeding behaviour and state of health is discussed.

Increased sensitivity to a natural pyrethrum extract of Trypanosoma-infected Glossina morsitans.

Topical application of a natural pyrethrum extract on male and pregnant female Glossina morsitans morsitans resulted in higher mortality for flies infected with Trypanosoma brucei brucei than for uninfected control flies. Infected males showed a significantly higher mortality while infected pregnant females showed a marginally significant increase in mortality. Results support the hypothesis that infected flies are less healthy than uninfected flies. Results also parallel previous findings using endosulfan as the topical applicant and exclude the likelihood that the results were because of a peculiar effect of endosulfan.

Trypanosoma brucei: in vitro propagation of metacyclic forms derived from the salivary glands of Glossina morsitans.

1 Metacyclic forms of Trypanosoma brucei obtained from the salivary glands of the tsetse fly, Glossina morsitans have been cultured for the first time in their infective forms for more than 200 days in continuous culture. The parasites were grown at 25 C and 30 C on a bovine embryonic spleen (BESP) feeder layer in buffered RPMI 1640 medium supplemented with 20% heat-inactivated bovine fetal serum (BFS) and 5% lactalbumin hydrolysate. Initial growth rate was enhanced when normal, noninfected, salivary glands were added to the cultures. The parasites thus cultured appeared like slender or intermediate blood stream forms which were infective to rats and mice. Addition of rat anti-T. brucei specific antiserum to the cultures caused agglutination of the parasites and rendered them noninfective. This study opens up new areas of investigating sleeping sickness. The cultured metacyclic parasites have the potential of being applied as antigens for controlling African trypanosomiasis.

Ultrastructural localization of acetylcholinesterase in cultured cells. III. DFP treated embryo muscle.

Brief treatment with 10(-4)M diisopropylfluorophosphate (DEP) irreversibly inactivates acetylcholinesterase (E.C.3.1.1.7; acetylcholine hydrolase) (AChE) activity in 10 day old chick embryonic muscle cultures. Electron microscopic cytochemistry was employed to follow the distribution of new AChE during recovery from DEP treatment. In normal 10 day cultures of embryo pectoralis muscles AChE is localized in the nuclear envelope, perinuclear sarcoplasm, sarcotubular system, subsurface vesicles and bound outside the cells. Immediately after DFP treatment AChE activity is absent in large myotubes. Within 15 min, activity is randomly present in small amounts in the sarcotubular system and nuclear envelope. There is a dramatic increase in activitv in the nuclear envelope during the 1st hr of recovery, and connections between the nuclear envelope and sarcotubular system are often seen. The next few hr of recovery show increased AChE activity. By 4 hr activity approaches that of controls. Six to 8 hr after treatment, AChE activity can be detected spectrophotometrically in the medium and can be seen bound outside the cells with the electron microscope. The spatial and temporal patterns of AChE activity demonstrate that the recovery of AChE and its mobilization and release from DFP-treated cells are not governed solely by the levels attained by the enzyme in the cultured embryo muscle.

Ultrastructural localization of acetylcholinesterase in cultured cells. II. Cycloheximide-treated embryo muscle.

The acetylcholinesterase activity (AChE) of cultured chick embryo muscle fibers that remains after the cells have been treated with the protein synthesis inhibitor cycloheximide was examined with cytochemical stains and the electron microscope. AChE activity that decreased rapidly after addition of the inhibitor was associated with enzyme within the cells, and AChE activity that was relatively insensitive to the inhibitor was associated with AChE outside of the cells. The results support the view that there are at least two fractions of AChE in developing muscle fibers, one intracellular and labile, the other extracelullar and stable.

Ultrastructural localization of acetylcholinesterase in cultured cells. I. Embryo muscle.

Several techniques were employed to examine the localization of acetylcholinesterase (EC 3.1.1.7, AChE) in cultured chick embryonic skeletal muscle. Glutaraldehyde produced the best cellular preservation but less enzyme activity was lost when the cells were fixed in paraformaldehyde. Two staining methods were examined: in one (Karnovsky MJ, Roots L: J Histochem Cytochem 12:219, 1964) potassium ferricyanide was added with the primary reactants, and in the other (Tsuji S: Histochemistry 42:99, 1974) the potassium ferricyanide was added at the end of the staining procedure. Localizations of AChE were similar with both stains; activity was present in the nuclear envelope, the perinuclear sarcoplasm, the sarcoplasmic reticulum, subsurface vesicles and bound outside the cells. /owever, a granular artifact was found with the method of Karnovsky and Roots that did not appear with the method of Tsuji. The localization of AChE are consistent with kinetic data that AchE binds, moves and is released from cultured muscle fibers.

Woodruffia metabolica: an exception to the rule of desmodexy.

Woodruffia metabolica (Protozoa, Ciliophora) has a compound fiber on the left side of its ciliary rows composed of parallel, overlapping ribbons of kinetosome-based microtubules. No similar structure is found connecting the kinetosomes on the right side of the ciliary rows. This arrangement is in opposition to the rule of desmodexy.