Biomedical subjects

Federica Santolamazza

Publications and source records attributed to Federica Santolamazza.

6 recordsLinked to original sources

PubMed2006

Breakpoint structure reveals the unique origin of an interspecific chromosomal inversion (2La) in the Anopheles gambiae complex.

Paracentric chromosomal inversions are major architects of organismal evolution and have been associated with adaptations relevant to malaria transmission in anopheline mosquitoes. The processes responsible for their origin and maintenance, still poorly understood, can be illuminated by analysis of inversion breakpoint sequences. Here, we report the breakpoint structure of chromosomal inversion 2La from the principal malaria vector Anopheles gambiae and its relatives in the A. gambiae complex. The distal and proximal breakpoints of the standard (2L+a) arrangement contain gene duplications: full-length genes and their truncated copies at opposite ends. Intact genes without pseudogene copies in the alternative arrangement (2La) imply that 2L+a is derived and was viable despite damage to genes, because duplication preserved gene function. A unique origin for the interspecific 2La inversion was challenged previously by indirect genetic evidence, but breakpoint sequences determined from members of the A. gambiae complex strongly suggest their descent from a single event. The derived position of 2L+a, long considered ancestral in this medically important group, has significant implications for the phylogenetic history and the evolution of vectorial capacity in the A. gambiae complex.

Animals↗

PubMed2005

Species and populations of the Anopheles gambiae complex in Cameroon with special emphasis on chromosomal and molecular forms of Anopheles gambiae s.s.

We studied the geographical distribution of species, chromosomal, and molecular forms of the Anopheles gambiae Giles (Diptera: Culicidae) complex in 23 sites in Cameroon, Central Africa. Almost all the specimens collected in the four northern-most arid sites were Anopheles arabiensis. Anopheles melas was found in a rural locality surrounded by mangrove swamps, on the Atlantic Coast. In total, 1,525 An. gambiae s.s. females were identified down to their molecular form, and inversion polymorphisms on polytene chromosomes were scored from 186 half-gravid females. The Forest chromosomal form, with standard arrangements almost fixed on both arms of chromosome-2, was the only one observed in the southern, more humid localities. Karyotypes typical of Savanna and Mopti were recorded northwards, in the humid savannas of the Adamawa Province. The molecular forms M and S were widespread throughout Cameroon, and assort independently from the chromosomal forms. S-form populations were characterized by karyotypes typical of Forest and Savanna chromosomal forms, and M-form populations were characterized by karyotypes typical of Forest, Savanna, and Mopti. No M/S hybrid patterns were detected, although M and S mosquitoes were sympatric in 15 sites, providing further evidence for positive assortative mating within molecular forms. The observed ecogeographical distribution of M and S was peculiar: the ecological parameters involved in this distribution still need to be clarified as well as the possible role of competitive exclusion between chromosomally homosequential molecular forms. No difference was observed in host preference or in Plasmodium falciparum infection rates between sympatric M and S populations.

Animals↗

PubMed2004

Short report: A new polymerase chain reaction-restriction fragment length polymorphism method to identify Anopheles arabiensis from An. gambiae and its two molecular forms from degraded DNA templates or museum samples.

We present a polymerase chain reaction-restriction fragment length polymorphism method to simultaneously distinguish the two Anopheles gambiae M and S molecular forms and Anopheles arabiensis. This method uses different diagnostic sites than previously published methods, and it is based on the amplification of a smaller ribosomal DNA fragment. We have tested this protocol in a variety of samples from different geographic regions and various ages of preservation to ascertain the robustness of this protocol over a wide geographic window and on DNA templates of poor quality. This procedure is as efficient as previous ones in discriminating An. arabiensis from the two taxa in An gambiae s.s. However, it performs better than others on poor quality templates such as the ones from museum collections, and poorly stored field collected material. However, it must be noted that it does not allow the simultaneous discrimination of all the species in the An. gambiae complex.

Animals↗

PubMed2003

A comparative study of the porin genes encoding VDAC, a voltage-dependent anion channel protein, in Anopheles gambiae and Drosophila melanogaster.

The protein called voltage-dependent anion-selective channel (VDAC), or mitochondrial porin, forms channels that provide the major pathway for small metabolites across the mitochondrial outer membrane. We have identified and sequenced agporin, a gene of the malaria vector mosquito Anopheles gambiae that conceptually encodes a protein with 73% identity to the VDAC protein encoded by the porin gene in Drosophila melanogaster. By in situ hybridization, we have localized agporin at region 35D on the right arm of A. gambiae chromosome 3, which is homologous to the 2L chromosomal arm of D. melanogaster where the porin gene resides. The comparison of agporin with its putative Drosophila counterpart revealed that both the nucleotide sequence and the structural organization of the two genes are strikingly conserved even though the ancestral lines of A. gambiae and D. melanogaster are thought to have diverged about 250 million years ago. Our results suggest that, while in yeast, plants, and mammals, VDAC isoforms are encoded by small multigene families and are able to compensate for each other at least partially, in A. gambiae a single gene encodes the VDAC protein.

Amino Acid Sequence↗

PubMed2002

Novel cDNAs encoding salivary proteins from the malaria vector Anopheles gambiae.

Several genes encoding salivary components of the mosquito Anopheles gambiae were identified using a selective trapping approach. Among these, five corresponded to genes expressed specifically in female glands and their role may possibly be linked to blood-feeding. Our collection included a fourth member of the D7 protein family and two polypeptides that showed weak similarity to anti-coagulants from distantly related species. Moreover, we identified two additional members of a novel group of proteins that we named glandins. The isolation of tissue-specific genes represents a first step toward a deeper molecular analysis of mosquito salivary secretions.

Amino Acid Sequence↗

PubMed2002

Molecular characterisation and chromosomal mapping of transcripts having tissue-specific expression in the malaria mosquito Anopheles gambiae: possible involvement in visual or olfactory processes.

We have compared the transcriptional activity of heads, antennae + palps, and carcasses in the mosquito Anopheles gambiae by means of differential display PCR (DD-PCR). Three transcripts specifically or preferentially expressed in the heads and in the antennae + palps have been selected. All are very similar to genes related to visual and olfactory mechanisms of several different organisms. They have been named Ag arrestin, Ag rLDL, and Ag dynamin. The potential of the DD-PCR technique in identifying genes involved in mosquito behaviour and the usefulness of the molecular characterisation of these transcripts are discussed.

Amino Acid Sequence↗