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Suppression of Brugia malayi (sub-periodic) larval development in Aedes aegypti (Liverpool strain) fed on blood of animals immunized with microfilariae.

Preliminary studies were carried out to investigate the role of filarial specific antibodies, raised in an animal model against the filarial parasite, Brugia malayi (sub-periodic), in blocking their early development in an experimental mosquito host, Aedes aegypti (Liverpool strain). In order to generate filarial specific antibodies, Mongolian gerbils, Meriones unguiculatus, were immunized either with live microfilariae (mf) of B. malayi or their homogenate. Mf were harvested from the peritoneal cavity of Mongolian gerbils with patent infection of B. malayi and fed to A. aegypti along with the blood from immunized animals. Development of the parasite in infected mosquitoes was monitored until they reached infective stage larvae (L3). Fewer number of parasites developed to first stage (L1) and subsequently to L2 and L3 in mosquitoes fed with blood of immunized animals, when compared to those fed with blood of control animals. The results thus indicated that filarial parasite specific antibodies present in the blood of the immunized animals resulted in the reduction of number of larvae of B. malayi developing in the mosquito host.

Aedes↗

Larval development of Brachidontes solisianus (Bivalvia, Mytilidae), with notes on differences between its hinge system and that of the mollusk Perna perna.

This work, which is part of a study program on meroplankton larvae, aims to gain more in-depth knowledge about planktonic larvae. This study began with the mollusk Brachidontes solisianus (Bivalvia-Mytilidae), which is abundant on the rocky shores of the Cabo Frio region (state of Rio de Janeiro, Brazil). Brachidontes solisianus larvae were grown under controlled conditions for a period of 26 days and were fed with Isochrysis galbana and Tetraselmis chui. The temperature was kept at 26 degrees C and the saltiness at 28. Images of the larvae were taken daily with a light camera and measured with a micrometric lens until settlement occurred. The average size of the first D-shaped veliger stage was 90 microm in length and 70 microm in height, while the size in the last stage before settlement (pediveliger) was 273 microm in length and 257 microm in height. The comparative study of the hinge system involved the most abundant intertidal species of the study area: Brachidontes solisianus and Perna perna. The B. solisianus species were found to have more visible denticles at the extremities of the provinculum, whereas the denticles of the P. perna species occur along the entire provinculum.

Animals↗

[Effect of actinomycin D and sibiromycin on the embryonic and larval development of Nereis virens (Sars.)].

The morphogenetic function of nuclear apparatus has been studied by means of "chemical enucleation" using actinomycin D (60 microgram/ml, 3 hrs) and sibiromycin (10--100 microgram/ml, 3 hrs) at different developmental stages of Nereis virens (Sars.). The embryos were subjected to the effect of the inhibitors at the successive stages every 6 hrs beginning from the fertilization. The development proceeded in the normal way til the throchophore stage in spite of the inhibition of DNA-dependent RNA synthesis what agrees with the concept of P. P. Ivanov on the existence in Polychaeta of a developmental tendency to trochophore. The first period of morphogenetic activity of the genome which ensures the transition from trochophore to metatrochophore coincides with the gastrula stage and the second period which ensures the transformation of metatrochophore into nectochaete with the final phases of the trochophore stage.

Animals↗

Preliminary observations on the effects of vector-averaged gravity on the embryonic and larval development of the gastropod mollusk, Ilyanassa obsoleta Stimpson.

Fertilized eggs of Ilyanassa obsoleta Stimpson were collected immediately after their deposition in egg capsules. Unopened egg capsules then were affixed to glass slides, and incubated either statically (controls) or on a clinostat (experimentals). After incubation for 9-14 days, hatching occurred sooner and in a higher percentage of clinostated capsules than in controls. Embryos that hatched while undergoing clinostat incubation were abnormal in morphology, whereas other embryos present in non-hatched capsules in the same tubes appeared normal, as did embryos in the control tubes. Although the results are compatible with a conclusion that vector-averaged gravity in the experimental tubes caused the altered development, some other aspects of how the incubations were done may have contributed to the differences between the control and experimental results.

Animals↗

Preliminary observations on the effects of vector-averaged gravity on the embryonic and larval development of the gastropod mollusk, Ilyanassa obsoleta Stimpson.

Fertilized eggs of Ilyanassa obsoleta Stimpson were collected immediately after their deposition in egg capsules. Unopened egg capsules then were affixed to glass slides, and incubated either statically (controls) or on a clinostat (experimentals). After incubation for 9-14 days, hatching occurred sooner and in a higher percentage of clinostated capsules than in controls. Embryos that hatched while undergoing clinostat incubation were abnormal in morphology, whereas other embryos present in non-hatched capsules in the same tubes appeared normal, as did embryos in the control tubes. Although the results are compatible with a conclusion that vector-averaged gravity in the experimental tubes caused the altered development, some other aspects of how the incubations were done may have contributed to the differences between the control and experimental results.

Animals↗

[Behavioral reactions of Bufo bufo L. tadpoles to chemical excretion of adult toads and changes during larval development].

The reactions of toad (Bufo bufo L.) tadpoles to chemical excretes of adults were studied. In double-choice test aquarium tadpoles demonstrated avoidance reactions (swimming away from the place of stimulus delivering, reduction time of spent in stimulus part of aquarium and reduction of movement activity). Efficiency of stimulus reduced when its concentration decreased. The thresholds of tadpoles sensitivity estimated according to the reduction of time spent in stimulus part of aquarium decreased in onthogeny: they were near 500 x 10(-5) g hour/l at 36-39 developmental stages and 500 x 10(-4) g.hour/l at 40-41 stages.

Animals↗

[Cholinergic regulation of the sea urchin embryonic and larval development].

Choline esters of polyenoic fatty acids block cleavage divisions of sea urchins and evoke the formation of one-cell multinuclear embryos. If the fatty acids AA-Ch or DHA-Ch are added at the mid or late blastula stage, many cells are extruded, forming extra-embryonic cell clusters near the animal pole of embryos or larvae. Both effects are prevented by dimethylaminoethyl esters of polyenoic fatty acids (AA-DMAE or DHA-DMAE) or their 5-hydroxytryptamides. Nicotinic acetylcholine receptor antagonists, imechine, d-tubocurarine or QX-222 provide partial protection against AA-Ch or DHA-Ch. The organophosphate pesticide, chlorpyrifos, or a combination of (-)-nicotine + phorbol 12-myristate 13-acetate, also evoke the mass extrusion of transformed embryonic cells at the animal pole of larvae. These effects are similarly antagonized by AA-DMAE, DHA-DMAE, or fatty acids 5-hydroxytryptamides. Taking together, these results suggest that AA-Ch and DHA-Ch act on sea urchin embryos and larvae as agonists of acetylcholine receptors, whereas AA-DMAE and DHA-DMAE act as antagonists. The ability of fatty acids 5-hydroxytryptamides to prevent the effects of AA-Ch or DHA-Ch may be due to restoration of the normal dynamic balance of cholinergic and serotonergic signaling during cleavage divisions and gastrulation.

Acetylcholine↗