262 research outputs found
Ultraviolet, atomic oxygen and outgassing effect on materials for space vehicles in LEO environment
No full textEDITORIAL
No full textMario Coluzzi is well known to readers of this Journal as an outstanding medical entomologist, malariologist, epidemiologist, and perhaps less well known as an evolutionary biologist. He made important advances in a number of sub-disciplines and, equally importantly, inspired a large number of researchers who continue active research enterprises on the forefront of confronting tropical diseases. After a long struggle with Parkinson’s Disease, Mario Coluzzi died in Rome on October 20, 2012. Overarching contribution When Mario Coluzzi was developing as a scientist in the 1950s and 60s, there was a radical and fundamental change occurring in population and evolutionary biology. Up until then evolution and systematics as well as medical entomology was dominated by “typological” thinking wherein practitioners identified entities such as species as having certain static properties that defined their essence. This typological view of species lumped together what in reality was a diverse set of genotypes that are spatially and temporally in flux. The new view was to recognize the actual diversity of the biological world down to the uniqueness of individuals. This was dubbed “populational ” thinking. The consequences of this shift in viewing the living world has fundamental implications for all of biology. The two most influential leaders in this shift were Th. Dobzhansky (evolutionary biology and genetics) and E. Mayr (systematics). Given Coluzzi’s non-traditional, largely self-education, he read these and other kindred authors at a time when their views had yet to penetrate the practice of medical entomology and parasitology. As Coluzzi became more engaged in hands-on understanding of insect vectors, he saw how this new way of viewing diversity was crucial in understanding important medical problems. Indeed he recognized that the divide between what was considered academic versus applied or practical was downright damaging. He set out, an
The use of saliva to soothe blood-sucking arthropod bites and the transmission of Human herpesvirus 8 (HHV-8).
No full textObjectives: The transmission of HHV-8, previously considered a sexually transmitted virus, sometimes appears strictly related to the child’s hypersensitivity response to the bite of a blood feeding arthropod and to the mother’s (or caregiver’s) habits of attempting to relieve itching and reduce scratching, contaminating the bite site with infected saliva (Coluzzi et al. 2002; 2003). Saliva seems to play a major role in the viral transmission and appears to be the reservoir body fluid for HHV-8 (Taylor et al. 2004). In order to confirm the promoter arthropod hypothesis we carried out surveys with questionnaires
Mechanical and environmental validation of a spherical multipurpose inflatable structure
No full textMolecular cloning of a cDNA coding for the Anopheles gambiae homologue of the Aedes aegypti apyrase.
No full textSalivary glands of mosquito vectors play an important role in the adaptation to haematophagy. Indeed the process of feeding on blood presents challenges to the mosquito and one of the most relevant is the demand to face the host haemostatic response to blood vessels damage. In this respect mosquito salivary glands have evolved the ability to produce and secrete substances able to counteract aspects of haemostasis such as vasoconstriction, coagulation and platelet aggregation. Anti-haemostatic activities have been identified by classical biochemical studies in the salivary gland secretions of several blood-feeding arthropods (Ribeiro J.M.C., 1987, Ann. Rev. Entomol. 32: 463-478). However, while distinct anticoagulant or vasodilator activities seem to be present in different species, apyrases appear to be the universal inhibitors of platelet aggregation in haematofagic arthropods. Apyrase is a secreted protein that hydrolyzes ATP and ADP to AMP and its function is to inhibit the ADP-induced platelet recruitment and aggregation. Apyrase activity has been found in the salivary gland extracts of different members of the Anopheles gambiae complex (Cupp E.W. et al, 1994, Am. J. Trop. Med. Hyg. 50: 235-240) but the only apyrase gene isolated and characterized so far belongs to the yellow fever mosquito Aedes aegypti (Smartt C.T. et al, 1995, Exp. Parasitol. 81: 239-248). Interestingly, the A. aegypti apyrase shows sequence similarity to the 5'-nucleotidases, a family of ubiquitous membrane-linked proteins that hydrolyze extra cellular nucleotides into membrane permeable nucleosides. It has been proposed that apyrase derived by a 5'-nucleotidase by gene duplication and subsequent divergent evolution; this probably involved the loss of a carboxyl-terminus hydrophobic domain with membrane-anchoring properties, the acquisition of tissue-specific expression and the evolution towards a new function with high adaptive role in haematophagy (Champagne D.E. et al, 1995, Proc. Natl. Acad. Sci. USA 92: 694-698). Using the Signal Sequence Trap technique (see Arcà B. et al., this meeting), that allows for the trapping of cDNAs coding for secreted and membrane-linked proteins, we have identified two different cDNA fragments, cF3 and iC6, both showing significant sequence similarity to the A. aegypti apyrase. Using specific oligonucleotide primers we were able to show by RT-PCR that cF3 is expressed only in the salivary glands of An. gambiae females, while iC6 is expressed also in males and in other female tissues. It is very likely that the cF3 cDNA fragment represents the An. gambiae apyrase while iC6 corresponds to the 5'-nucleotidase. The cF3 cDNA fragment was used as probe to screen a thoracic cDNA library from An. gambiae females and allowed for the isolation of a clone of about 2.3 kb representing the putative full-length apyrase cDNA. The deduced protein is 557 aa in length, contains at the amino-terminus a putative 22 aa long signal peptide, has a predicted molecular weight of approximately 62 kDa and contains five possible N-linked glycosylation sites. Sequence comparison to the A. aegypti apyrase shows that the two proteins, which also have very similar molecular weight, share about 51% identity and 61% similarity throughout most of their length. These observations strongly suggest that our cDNA really represents the An. gambiae homologue of the A. aegypti apyrase and its identification may be of great help in the isolation of apyrase genes from other haematophagous arthropods. We are presently screening a genomic library in the attempt to obtain the apyrase genomic clone with the main goal of isolating an An. gambiae salivary gland specific promoter that may be of great help in the design of new malaria control strategies as soon as a genetic transformation system will become available also for the malaria vector An. gambiae
Lambda display and RNAi as tools in the study of the Anopheles gambiae salivary glands.
No full textWith the aim of investigating invasion of Anopheles salivary glands by Plasmodium parasites, we displayed on the surface of lambda phages selected sporozoite protein domains putatively involved in recognition/invasion of mosquito salivary glands. Adhesive domains from Plasmodium falciparum and Plasmodium berghei TRAP (Trombospondin Related Anonimous Protein), CS (CircumSporozoite), MAEBL (Membrane Antigen and Erythrocyte Binding Like) and CRMPs (Cysteine Rich Modular Proteins) were fused to the C-terminus of the lambda phage capsid protein gpD in D4. Therefore, two mini-collections were produced, independent recombinant lambda clones were isolated and expression of the expected fusion proteins was verified by western analysis. To test the capability of the displayed domains to recognize and bind mosquito salivary glands, we used an in vivo biopanning assay. The phage collections were injected into the haemocoel of An. gambiae adult females and, after a few hours, mosquitoes were dissected and phages bound to glands or other control tissues (i.e. ovaries) were recovered. Initial analysis indicates a slightly stronger binding of the recombinant phage collections as compared to wild type D4. Further in vivo and in vitro binding assays will be performed to optimize experimental conditions suitable for the selection of higher affinity binding domains. In order to develop additional tools to study salivary gland invasion and proceed toward functional analysis, we are also setting up in the lab salivary gene silencing by RNAi. As recently suggested (Boisson B et al, 2006) down-regulation of salivary gland genes in An. gambiae requires the injection of large amounts of dsRNA (approx 5-15 times higher as compared to knock down of midgut- or haemocyte-expressed genes). As a prototype we decided to use gSG6, a female salivary gland-specific gene encoding a short protein with similarity to an anticoagulant from a distantly related species. The function of this salivary protein is still uncharacterized but it appeared especially suitable since a mouse polyclonal anti-serum was available. Preliminary analysis by western blot suggests a significant reduction of gSG6 protein level in salivary extracts from mosquitoes injected with gSG6-dsRNA as compared to buffer-injected controls. Optimization of injection conditions, validation of silencing specificity and mRNA level determination by real-time quantitative RT-PCR are in progress
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