Anopheles gambiae

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Anopheles gambiae
AnophelesGambiaemosquito.jpg
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Diptera
Family:
Culicidae
Subfamily:
Anophelinae
Genus:
Anopheles
Species complex:
A. gambiae sensu lato
Species:
Binomial name
Anopheles gambiae
The tube-like heart (green) extends along the body, interlinked with the diamond-shaped alary muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei. Structural organization of the heart of the mosquito Anopheles gambiae - image.ppat.v08.i11.g001.png
The tube-like heart (green) extends along the body, interlinked with the diamond-shaped alary muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.

The Anopheles gambiae complex consists of at least seven morphologically indistinguishable species of mosquitoes in the genus Anopheles . The complex was recognised in the 1960s and includes the most important vectors of malaria in sub-Saharan Africa, particularly of the most dangerous malaria parasite, Plasmodium falciparum . [2] It is one of the most efficient malaria vectors known. The An. gambiae mosquito additionally transmits Wuchereria bancrofti which causes lymphatic filariasis, a symptom of which is elephantiasis. [3]

Contents

Discovery and elements

The Anopheles gambiae complex or Anopheles gambiae sensu lato was recognized as a species complex only in the 1960s. The A. gambiae complex consists of:

The individual species of the complex are morphologically difficult to distinguish from each other, although it is possible for larvae and adult females. The species exhibit different behavioural traits. For example, Anopheles quadriannulatus is both a saltwater and mineralwater species. A. melas and A. merus are saltwater species, while the remainder are freshwater species. [7] Anopheles quadriannulatus generally takes its blood meal from animals (zoophilic), whereas Anopheles gambiae sensu stricto generally feeds on humans, i.e. is considered anthropophilic.[ citation needed ] Identification to the individual species level using the molecular methods of Scott et al. (1993) [8] can have important implications in subsequent control measures.

Anopheles gambiae in the strict sense

An. gambiae sensu stricto (s.s.) has been discovered to be currently in a state of diverging into two different species—the Mopti (M) and Savannah (S) strains—though as of 2007, the two strains are still considered to be a single species. [9] [10]

The mechanism of species recognition appears to be sounds emitted by the wings and identified by Johnston's organ. [11]

Genome

An. gambiae s.s. genomes have been sequenced three times, once for the M strain, once for the S strain, and once for a hybrid strain. [9] [10] Currently, ~90 miRNA have been predicted in the literature (38 miRNA officially listed in miRBase) for An. gambiae s.s. based upon conserved sequences to miRNA found in Drosophila .[ citation needed ] Holt et al., 2002 and Neafsey et al., 2016 find transposable elements to be ~13% of the genome, similar to Drosophila melanogaster (also in Diptera). [12] However they find the proportion of TE types to be very different from D. melanogaster with approximately the same composition of long terminal repeat retrotransposons, non-long terminal repeat retrotransposons and DNA transposons. [12] These proportions are believed to be representative of the genus. [12]

The genetics and genomics of sex chromosomes have been discovered and studied by Windbichler et al., 2007 and Galizi et al., 2014 (a Physarum polycephalum homing endonuclease which destroys X chromosomes), Windbichler et al., 2008 and Hammond et al., 2016 (methods to reduce the female population), Windbichler et al., 2011 (trans from yeast), Bernardini et al., 2014 (a method to increase the male population), Kyrou et al., 2018 (a female necessary exon and a homing endonuclease to drive it), Taxiarchi et al., 2019 (sex chromosome dynamics in general) and Simoni et al., 2020 (an X chromosome destroying site specific nuclease). [13] See § Gene drive below for their applications.

An. gambiae has a high degree of polymorphism. This is especially true in the cytochrome P450s, Wilding et al., 2009 finding 1 single nucleotide polymorphism (SNP)/26 base pairs. This species has the highest amount of polymorphism in the CYPs of any insect known, much tending to be found in "scaffolds" that are found only in particular subpopulations. These are termed "dual haplotype regions" by Holt et al., 2002 who sequenced the PEST strain. [14] : 241 

In common with many chromosomes, An. gambiae codes for spindle and kinetochore-associated proteins. Hanisch et al., 2006 locate AgSka1 , the spindle and kinetochore-associated protein 1 gene, at EAL39257. [15]

The entire Culicidae family may or may not conserve epigenetic mechanisms –as of 2012 this remains unresolved. [16] Toward answering this question, Marhold et al., 2004 compare their own previous work in Drosophila melanogaster against new sequences of D. pseudoobscura and An. gambiae. [16] They find all three do share the DNA methylation enzyme DNMT2 ( DmDNMT2 , DpDNMT2 , and AgDNMT2). [16] This suggests all Diptera may conserve an epigenetic system employing Dnmt2. [16]

Hosts

Hosts include Bos taurus , Capra hircus , Ovis aries and Sus scrofa . [17]

Parasites

Parasites include Plasmodium berghei (for which it also serves as a vector), [18] [19] [20] and the bioinsecticides/entomopathogenic fungi Metarhizium robertsii [18] and Beauveria bassiana . [18] All three of these parasites combine with insecticides to reduce fitness – see § Insecticides below. [18] CRISPR/Cas9 and U6-gRNA are increasingly (as of 2020) being used together for knockout experiments in mosquitoes. [20] Dong et al., 2018 develops and presents a new U6-gRNA+Cas9 technique in An. gambiae, and utilizes it to knock out fibrinogen related protein 1 (FREP1), thereby severely reducing infection of the mosquito by P. berghei and P. falciparum . [20] However this also demonstrates the centrality of FREP1 to the insect's success, impairing all measured activities across all life stages. [20] Yang et al., 2020 uses the Dong method to do the same with mosGILT , also severely reducing Plasmodium infection of the mosquito but also finding a vital life process is impaired, in mosGILT's case ovary development. [20]

Control

Insecticides

Parasites/bioinsecticides and chemical insecticides synergistically reduce fitness. Saddler et al., 2015 finds even An. gambiae with knockdown resistance (kdr) are more susceptible to DDT if they are first infected with Plasmodium berghei [18] [19] and Farenhorst et al., 2009 the same for Metarhizium robertsii or Beauveria bassiana . [18] This is probably due to an effect found by Félix et al., 2010 and Stevenson et al., 2011: An. gambiae alters various activities – especially CYP6M2 – in response to P. berghei invasion. CYP6M2 is known to somehow produce pyrethroid resistance, and pyrethroids and DDT share a mechanism of action. [19]

Gene drive

Research relevant to the development of gene drive controls of An. gambiae have been performed by Windbichler et al., 2007, Windbichler et al., 2008, Windbichler et al., 2011, Bernardini et al., 2014, Galizi et al., 2014, Hammond et al., 2016, Kyrou et al., 2018, Taxiarchi et al., 2019 and Simoni et al., 2020. [13] For specific genes involved see § Genome above. These can all be used in pest control because they induce infertility. [13]

Fecundity

Fecundity of An. gambiae depends on the detoxification of reactive oxygen species (ROS) by catalase. [21] Reduction in catalase activity significantly reduces reproductive output of female mosquitoes, indicating that catalase plays a central role in protecting oocytes and early embryos from ROS damage. [21]

Historical note

An. gambiae invaded northeastern Brazil in 1930, which led to a malaria epidemic in 1938/1939. [22] The Brazilian government assisted by the Rockefeller Foundation in a programme spearheaded by Fred Soper eradicated these mosquitoes from this area. This effort was modeled on the earlier success in eradication of Aedes aegypti as part of the yellow fever control program. The exact species involved in this epidemic has been identified as An. arabiensis . [23]

Peptide hormones

Kaufmann and Brown 2008 find the An. gambiae adipokinetic hormone (AKH) mobilizes carbohydrates but not lipids. Meanwhile AKH/Corazonin Peptide (ACP) does not mobilize (or inhibit mobilization) of either. Mugumbate et al., 2013 provides in solution and membrane bound structures from a nuclear magnetic resonance investigation. [24]

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<i>Anopheles</i> Genus of mosquito

Anopheles or Marsh Mosquitoes is a genus of mosquito first described and named by J. W. Meigen in 1818. About 460 species are recognized; while over 100 can transmit human malaria, only 30–40 commonly transmit parasites of the genus Plasmodium, which cause malaria in humans in endemic areas. Anopheles gambiae is one of the best known, because of its predominant role in the transmission of the most dangerous malaria parasite species – Plasmodium falciparum.

<i>Wolbachia</i> Genus of bacteria in the Alphaproteobacteria class

Wolbachia is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.

<span class="mw-page-title-main">Microsporidia</span> Phylum of fungi

Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore. They were once considered protozoans or protists, but are now known to be fungi, or a sister group to fungi. These fungal microbes are obligate eukaryotic parasites that use a unique mechanism to infect host cells. They have recently been discovered in a 2017 Cornell study to infect Coleoptera on a large scale. So far, about 1500 of the probably more than one million species are named. Microsporidia are restricted to animal hosts, and all major groups of animals host microsporidia. Most infect insects, but they are also responsible for common diseases of crustaceans and fish. The named species of microsporidia usually infect one host species or a group of closely related taxa. Approximately 10 percent of the species are parasites of vertebrates —several species, most of which are opportunistic, can infect humans, in whom they can cause microsporidiosis.

<i>Plasmodium ovale</i> Species of single-celled organism

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<i>Plasmodium berghei</i> Single celled parasite, rodent malaria

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<i>Anopheles stephensi</i> Species of fly

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References

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  2. ↑ "Anopheles gambiae complex". Walter Reed Army Institute of Research. Archived from the original on 2007-09-29.
  3. ↑ "Lymphatic filariasis". www.who.int. Retrieved 2020-04-10.
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  5. ↑ Wilkins EE, Howell PI, Benedict MQ (2006). "IMP PCR primers detect single nucleotide polymorphisms for Anopheles gambiae species identification, Mopti and Savanna rDNA types, and resistance to dieldrin in Anopheles arabiensis". Malaria Journal . 5 (1): 125. doi: 10.1186/1475-2875-5-125 . PMC   1769388 . PMID   17177993.
  6. ↑ Yakob, Laith (2011). "Epidemiological consequences of a newly discovered cryptic subgroup of Anopheles gambiae". Biology Letters . 7 (6): 947–949. doi:10.1098/rsbl.2011.0453. PMC   3210673 . PMID   21693489.
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  9. 1 2 "Anopheles gambiae: First genome of a vector for a parasitic disease". Genoscope. Archived from the original on 2011-08-07.
  10. 1 2 Lawniczak, M. K.; et al. (Oct 22, 2010). "Widespread divergence between incipient Anopheles gambiae species revealed by whole genome sequences". Science . 330 (6003): 512–4. Bibcode:2010Sci...330..512L. doi:10.1126/science.1195755. PMC   3674514 . PMID   20966253.
  11. ↑ Pennetier, Cédric; Warren, Ben; Dabiré, K. Roch; Russell, Ian J.; Gibson, Gabriella (2010). ""Singing on the Wing" as a Mechanism for Species Recognition in the Malarial Mosquito Anopheles gambiae". Current Biology . 20 (2): 131–136. doi: 10.1016/j.cub.2009.11.040 . PMID   20045329. S2CID   15185976.
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  13. 1 2 3 Hay, Bruce A.; Oberhofer, Georg; Guo, Ming (2021-01-07). "Engineering the Composition and Fate of Wild Populations with Gene Drive". Annual Review of Entomology . 66 (1): 407–434. doi:10.1146/annurev-ento-020117-043154. ISSN   0066-4170. PMID   33035437. S2CID   222257628.
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  15. ↑ Cheeseman, Iain M.; Desai, Arshad (2008). "Molecular architecture of the kinetochore–microtubule interface". Nature Reviews Molecular Cell Biology . Nature Portfolio. 9 (1): 33–46. doi:10.1038/nrm2310. ISSN   1471-0072. PMID   18097444. S2CID   34121605.
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  19. 1 2 3 Minetti, Corrado; Ingham, Victoria A; Ranson, Hilary (2020). "Effects of insecticide resistance and exposure on Plasmodium development in Anopheles mosquitoes" (PDF). Current Opinion in Insect Science . 39: 42–49. doi:10.1016/j.cois.2019.12.001. ISSN   2214-5745. PMID   32109860. S2CID   211563675.
  20. 1 2 3 4 5 Caragata, E.P.; Dong, S.; Dong, Y.; Simões, M.L.; Tikhe, C.V.; Dimopoulos, G. (2020-09-08). "Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease". Annual Review of Microbiology . Annual Reviews. 74 (1): 455–475. doi:10.1146/annurev-micro-011320-025557. ISSN   0066-4227. PMID   32905752. S2CID   221625690.
  21. 1 2 DeJong RJ, Miller LM, Molina-Cruz A, Gupta L, Kumar S, Barillas-Mury C (February 2007). "Reactive oxygen species detoxification by catalase is a major determinant of fecundity in the mosquito Anopheles gambiae". Proceedings of the National Academy of Sciences . 104 (7): 2121–6. Bibcode:2007PNAS..104.2121D. doi: 10.1073/pnas.0608407104 . PMC   1892935 . PMID   17284604.
  22. ↑ Killeen GF (October 2003). "Following in Soper's footsteps: northeast Brazil 63 years after eradication of Anopheles gambiae". The Lancet Infectious Diseases . 3 (10): 663–6. doi:10.1016/S1473-3099(03)00776-X. PMID   14522266.
  23. ↑ Parmakelis A, Russello MA, Caccone A, et al. (January 2008). "Historical analysis of a near disaster: Anopheles gambiae in Brazil". The American Journal of Tropical Medicine and Hygiene . 78 (1): 176–8. doi: 10.4269/ajtmh.2008.78.176 . PMID   18187802.
  24. ↑ Strand, M.R.; Brown, M.R.; Vogel, K.J. (2016). "Mosquito Peptide Hormones". Advances in Insect Physiology . Vol. 51. Elsevier. pp. 145–188. doi:10.1016/bs.aiip.2016.05.003. ISBN   9780128024577. ISSN   0065-2806. PMC   6338476 . PMID   30662099. S2CID   58546659.
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