PubMed Health⌕ Search

Biomedical subjects

J C Jacques

Publications and source records attributed to J C Jacques.

4 recordsLinked to original sources

Transcripts of the malaria vector Anopheles gambiae that are differentially regulated in the midgut upon exposure to invasive stages of Plasmodium falciparum.

Understanding the interactions between the most deadly malaria parasite, Plasmodium falciparum, and its main vector, Anopheles gambiae, would be of great help in developing new malaria control strategies. The malaria parasite undergoes several developmental transitions in the mosquito midgut and suffers population losses to which mosquito factors presumably contribute. To identify such factors, we analysed An. gambiae midgut transcripts whose expression is regulated upon ingestion of invasive or non-invasive forms of P. falciparum using a differential display approach. Sixteen cDNA were studied in detail; 12 represent novel genes of An. gambiae including a gene encoding profilin. Four transcripts were specifically regulated by P. falciparum gametocytes (invasive forms), whereas the others were regulated by either non-invasive or both non-invasive and invasive forms of the parasite. This differential regulation of some genes may reflect the adaptation of P. falciparum to its natural vector. These genes may be involved in the development of P. falciparum in An. gambiae or in the defence reaction of the mosquito midgut towards the parasite.

Animals↗

[The Borrelia of ornithodoros in tropical Africa: value and limits of cross protection tests in the mouse].

The identification of Borrelia strains isolated from ticks or relapsing fever patients is not easy. Seizing the opportunity of recent isolation of such strains from Western Africa, we tried to evaluate the interest and the limits of a method classically proposed for that aim; cross protection test in mouse. This technique is proving rather difficult to perform because of different technical reasons; the results are critical to read. In some cases, these results seem undeniable, but the observed differences in protection levels are often weak, inconstant, insufficiently reliable to constitute a diagnostic tool. So it appears important to develop other identification methods, based on molecular analysis of Borrelia DNA, which will be more subtle and more specific.

Africa, Western↗

Localization of two noise sources overlapping in time.

The accuracy of localization of two independent, wide-band noise sources, overlapping in time, was measured. Subjects given preliminary practice had little difficulty in localizing when sources separated by 55 degrees were located in front of them or in back of them, with one source 10 degrees from the midline. But when sources were at the side of the subject, perception that there were two sources present tended to improve significantly as time between onset of the sounds was increased to 100 msec. Once a sound was perceived to be present, it was localized with fairly high accuracy.

Acoustic Stimulation↗