Sex determination genes control the development of the Drosophila genital disc, modulating the response to Hedgehog, Wingless and Decapentaplegic signals

In both sexes, the Drosophila genital disc contains the female and male genital primordia. The sex determination gene doublesex controls which of these primordia will develop and which will be repressed. In females, the presence of Doublesex(F) product results in the development of the female genital primordium and repression of the male primordium. In males, the presence of Doublesex(M) product results in the development and repression of the male and female genital primordia, respectively. This report shows that Doublesex(F) prevents the induction of decapentaplegic by Hedgehog in the repressed male primordium of female genital discs, whereas Doublesex(M) blocks the Wingless pathway in the repressed female primordium of male genital discs. It is also shown that Doublesex(F) is continuously required during female larval development to prevent activation of decapentaplegic in the repressed male primordium, and during pupation for female genital cytodifferentiation. In males, however, it seems that Doublesex(M) is not continuously required during larval development for blocking the Wingless signaling pathway in the female genital primordium. Furthermore, Doublesex(M) does not appear to be needed during pupation for male genital cytodifferentiation. Using dachshund as a gene target for Decapentaplegic and Wingless signals, it was also found that Doublesex(M) and Doublesex(F) both positively and negatively control the response to these signals in male and female genitalia, respectively. A model is presented for the dimorphic sexual development of the genital primordium in which both Doublesex(M) and Doublesex(F) products play positive and negative roles.     

Effects of betamethasone,sulindac and quinacrine drugs on the inflammatory neoangiogenesis response induced by polyurethane sponge implanted in mouse

In this study, we showed the effect of the betamethasone, sulindac and quinacrine alone or combined, on the inflammatory angiogenesis promoted by polyurethane sponge on mice. The main finding reported here is that the formation of new blood vessels was strongly inhibited by low concentration of betamethasone, sulindac or quinacrine, whether alone or in combination. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear glucocorticoid receptor (GR) mediated mechanism. This mechanism may occur in endothelial cells as well. Considering that activity of cyclo-oxigenases 1 and 2 is inhibited by sulindac, and that these enzymes are located in the stromal tissue, we propose that the anti-angiogenic effect of these agents may occur via inhibition of both COX isoforms. On the other hand, quinacrine inhibited PLA2 activity, and we propose here that the anti-angiogenic effect occurs via inhibition of the enzyme PLA2. The potentiated effect of the association of betamethasone, sulindac and quinacrine may have some therapeutic benefit in the control of pathological angiogenesis. Further studies are required to validate these propositions.     

First account on the larval biology of a Litomosoides filaria,from a bat

Litomosoides filariae are parasites of unrelated groups of hosts, including bats, marsupials, ancient and modern rodents. The four life cycles to-date elucidated, develop in terrestrial mammals and, at least experimentally, in the mite Ornithonyssus bacoti. A batch of mites was fed on an infected bat, Artibeus jamaicensis captured in Costa Rica, and 18 days later one infective larva was recovered. Its morphology was similar to that of other Litomosoides species, with the characteristic long buccal capsule. These first accounts on the larval biology of Litomosoides from Microchiroptera confirm the unity of the genus which supports the view that it has passed from one group of hosts to another by means of captures.     

Heat shock cognate protein 70 is involved in rotavirus cell entry

In this work, we have identified the heat shock cognate protein (hsc70) as a receptor candidate for rotaviruses. hsc70 was shown to be present on the surface of MA104 cells, and antibodies to this protein blocked rotavirus infectivity, while not affecting the infectivity of reovirus and poliovirus. Preincubation of the hsc70 protein with the viruses also inhibited their infectivity. Triple-layered particles (mature virions), but not double-layered particles, bound hsc70 in a solid-phase assay, and this interaction was blocked by monoclonal antibodies to the virus surface proteins VP4 and VP7. Rotaviruses were shown to interact with hsc70 at a postattachment step, since antibodies to hsc70 and the protein itself did not inhibit the virus attachment to cells. We propose that the functional rotavirus receptor is a complex of several cell surface molecules that include, among others, hsc70.     

Synthesis and testing of 5-benzyl-2,4-diaminopyrimidines as potential inhibitors of leishmanial and trypanosomal dihydrofolate reductase

Dihydrofolate reductase is a drug target that has not been thoroughly investigated in leishmania and trypanosomes. Work has previously shown that 5-benzyl-2,4-diaminopyrimidines are selective inhibitors of the leishmanial and trypanosome enzymes. Modelling predicted that alkyl/aryl substitution on the 6-position of the pyrimidine ring should increase enzyme activity of 5-benzyl-2,4-diaminopyrimidines as inhibitors of leishmanial and trypanosomal dihydrofolate reductase. Various compounds were prepared and evaluated against both the recombinant enzymes and the intact organisms. The presence of a substituent had a small or negative effect on activity against the enzyme or intact parasites compared to unsubstituted compounds.     

Molecular and Biochemical Diagnosis of Esterase-Mediated Pyrethroid Resistance in a Mexican Strain of Boophilus microplus (Acari: Ixodidae)

We examined pyrethroid resistant Mexican strains of Boophilus microplus using biochemical and molecular tests to determine the mechanisms conferring resistance. Permethrin hydrolysis assays and esterase activity gels indicated enhanced esterase-mediated metabolic detoxification in the Cz strain, while one other pyrethroid resistant strain, SF, and two pyrethroid susceptible strains had lower levels of permethrin hydrolysis. Results from assays using a PCR-based test to detect a pyrethroid target site resistance-associated mutation in the tick sodium channel gene found only low levels of mutations in the Cz strain, while the SF strain had a high level of the mutated sodium channel alleles. A specific esterase, designated CzEst9, believed to be responsible for the esterase-mediated pyrethroid resistance in the Cz strain was purified, and the gene encoding CzEst9 cloned. This revised version was published online in July 2006 with corrections to the Cover Date.     

Litomosoides yutajensis n. sp., first record of this filarial genus in a mormoopid bat

Twenty-five bats were trapped in Yutaje (Amazonas, Venezuela) and examined for Litomosoides (Filarioidea: Onchocercidae). Of the nine recovered bat species, only Pteronotus parnelli was infected; it is a cave-dwelling species belonging to a family, Mormoopidae, which has not previously been included in the host range of the genus. The new species, L. yutajensis n. sp., has two median cephalic bosses covered with rugosities and differs from the 15 recognized species and subspecies from bats in several characters. Alike L. molossi Esslinger, 1973, L. chandleri Esslinger, 1973 and L. chitwoodi Bain, Guerrero, Rodriguez 2003, the new species has cuticular lateral bosses on the body. Eight of 10 P. parnelli were microfilaraemic, but only three had adult worms, showing that microfilariae survive longer than adults, which could lengthen the period of transmission. No infective larvae were detected in the following macronyssid mites: 58 Ornithonyssus bacoti, Ornithonyssinae, experimentally fed on microfilaraemic bats and dissected 15 days later, and a few Radfordiella sp., Macronyssinae, recovered from P. parnelli.     

Neo-clerodane diterpenoids from Croton schiedeanus

Two new neo-clerodane type furano diterpenoids were isolated from the aerial part of Croton schiedeanus, besides the clerodane diterpenes cis- and trans-dehydrocrotonin, previously isolated from other species of Croton. Structural elucidation was achieved on basis of extensive NMR experiments, including X-ray diffraction analysis and molecular mechanics calculations. The previously known flavonoids ayanin and quercetin-3,7-dimethyl ether were also obtained from the extract of this plant.     

Effect of Trypanosoma lewisi (Kinetoplastida: Trypanosomatidae) on the infection of white rats with Toxoplasma gondii (Eucoccidia: Sarcocystidae) oocysts

White rats were inoculated with 10(6) trypomastigotes of Trypanosoma lewisi, simultaneously or two days before and after inoculation with 10(5) oocysts of T. gondii. A greater number of cysts was found in the brain of the animals having concomitant inoculations, as compared with rats inoculated with either one of the two parasites. An apparent immunosuppressive effect is likely. Since both organisms can be found in rats, it is possible that infections with T. lewisi, could make this rodent another intermediate host for Toxoplasma infections.     

Existence and significance of Acartia grani resting eggs (Copepoda: Calanoida) in sediments of a coastal station in the Alboran Sea (SE Spain)

The seasonal abundance of copepod eggs in bottom sediments ofMalaga harbour was documented during an annual cycle betweenJune 1989 and June 1990. The concentration noted ranged from6.6.10⁶ to 0.1910⁶ m^–2. The number of adults in thewater column and eggs recovered from the bottom sediments fluctuatedmarkedly with season. The highest egg abundance in sedimentswas found coincidentally with the early population growth season,although the values remained high until the adults disappearedfrom the water column. During the winter, the number of eggsdecreased until the development of the next copepod population.When bottom sediments were incubated in the laboratory, a largenumber of Acartia nauplii hatched, which showed that eggs laidin the autumn remain viable at the bottom until late spring,thus providing a large pool of potential recruits for the planktonicpopulation. ¹Present address: Departamento de Biologa Animal, Vegetal yEcologa, Facultad de Ciencias Experimentales, Universidad deMan Paraje Las Lagunillas s/n, 23071 Man, Spain