Short report: A practical technique for the cryopreservation of Dirofilaria immitis, Brugia malayi, and Wuchereria bancrofti microfilariae.

A technique to cryopreserve microfilariae has been developed. This method was used to cryopreserve microfilariae of Dirofilaria immitis, Brugia malayi, and Wuchereria bancrofti at a controlled rate of 1 degree C/min by use of a freezing tank. Microfilariae of each of these species retained their ability to infect susceptible mosquito species and develop to the infective stage after cryopreservation. The method presented here is quickly and easily carried out with inexpensive equipment.

Induction of some digestive enzymes in the midgut of the sandfly Phlebotomus langeroni after sugar and blood meals.

Changes associated with blood and sugar meal digestion in the sandfly, Phlebotomus langeroni were characterized. Different types of sugars: sucrose, glucose, melibiose, cellobiose, lactose, starch, fig fruits, honey dew and a mixture of sucrose and sugar sources were used for the sandfly feeding. Activities of glycosidases and proteases in the sandfly guts after blood and sugar meals were determined using the endpoint method. The results showed that glycosidases (alpha-glycosidase, beta-glycosidase, alpha-galactosidase, and beta-galactosidase) are present in the sandfly midguts. No activities of the glycosidases (alpha-mannosidase and alpha-amylase) were detected in the sandfly gut. Proteases: trypsin and aminopeptidase showed activities in the sandfly midguts. It is concluded that the midgut glycosidase may play an important role in the vector-parasite interaction. Trypsin and aminopeptidase induction after a blood meal is controlled by a secretogogue mechanism which indirectly influences the outcome of the Leishmania parasite infection.

Carbohydrate digestion in sandflies: alpha-glucosidase activity in the midgut of Phlebotomus langeroni.

Midgut alpha-glucosidase (EC 3.2.1.20) activities were measured after ingestion of blood and sugar meals by the phlebotomine sandfly Phlebotomus langeroni. alpha-Glucosidase activity increased significantly within 1 hr after a blood meal and was maintained at significantly high activities until 48 hr postfeeding, when it fell to basal activity levels. Midgut alpha-glucosidase activity also increased within 1 hr of feeding on a sucrose meal, but there was no discernable peak in activity during the days postingestion. Differences in the induction of enzyme activity after a sugar meal compared to a blood meal might reflect the mode of ingestion of the two types of meal. The sugar meal is released intermittently into the midgut from the crop, in contrast to the bloodmeal, which is directed into the midgut immediately after ingestion and digested in a "batch" process. Nearly 90% of the alpha-glucosidase activity was associated with midgut cells of sugar fed sandflies compared to only 46% in blood fed insects. Isoelectrofocusing revealed the presence of seven alpha-glucosidases with isoelectric points between 4.3-5.8. No alpha-glucosidase activity was detected in the crop, indicating that glucosidases originate from the midgut epithelium rather than the salivary glands.

Adult diet as a factor affecting biology of the sandfly Phlebotomus papatasi (Diptera: Psychodidae).

The effects of adult nutrients on egg retention, immature development and adult survival of P. papatasi, the important vector of leishmaniasis in Egypt were investigated. The tested nutrients were distilled water, overripe fig fruits, guinea pig blood, sucrose solution and alternative meals of blood and sucrose. Egg retention was observed in females irrespective to the type of offered nutrient (r = 0.21) but higher proportion (47%) of blood fed females had retained eggs. Duration of the life cycle was higher for the progeny of fig fed females (P less than 0.05) and mean generation time was longer for sucrose fed females (P less than 0.05). Such nutritional effect on life cycle was observed only for pre-oviposition periods and no extend effect on larval or pupal durations. The survivorship rates for eggs through adults were similar (P greater than 0.05). It is estimated that the population would increase by Ca. 15, 11, 10 and 7 folds if the mother female was fed blood, sucrose, fig or distilled water respectively. The mean life time differed significantly (P less than 0.05) among females fed on different nutrients with the highest co (life expectancy at emergence) value (14.98 +/- 2.75 days) for sucrose fed females. Males fed on distilled water, fig fruits or sucrose solution were with similar longevities P greater than 0.05). In respect to leishmania transmission, the calculated expectancies for female life beyond the infective age indicated that blood-sucrose fed females have higher capability than those fed on sucrose blood or blood alone.

Amines in Algae. 8. Effects of a Modified Light Regime and of Inhibitors of DNA Synthesis on Polyamine Levels in Synchronous Chlorella emersonii.

Chlorella emersonii (strain 211-8b) was grown synchronously in a 16 : 8 h light-dark cycle. The normal kinetic coincidence between the concentration changes per initial cell of DNA, putrescine, and spermidine disappeared to a greater or lesser degree upon shifting the light-dark cycle from 16 :8 h to 10 : 14 h as well as in the presence of inhibitors of DNA synthesis. For example, timing, and initial rates of synthesis of putrescine and spermidine remained normal, when DNA synthesis was blocked by 5-fluoro deoxy uridine. Also during recovery from the unspecific inhibition by hydroxy urea the DNA/putrescine/spermidine coincidences disappeared. Hence, these coincidences which are observed under standard conditions, may be essentially incidental. By contrast, the RNA/norspermidine coincidence was maintained to a greater or lesser extent under all conditions tested. The concentration of norspermidine was found to be 25 ± 5 mg per gram of RNA.