chitosaninterfering-rna-nanoparticle-mediated-gene-silencing-disease

Chitosan/Interfering RNA Nanoparticle Mediated Gene Silencing in Disease Vector Mosquito Larvae

Vector mosquitoes inflict more human suffering than any other organism&#8212;and kill more than one million people each year. The mosquito genome projects ...

We use monoclonal antibodies against synaptic proteins and anterograde tracing with neurobiotin to describe the architecture of the antennal lobes in different castes of two ant species -Camponotus sericeus and Camponotus compressus. The reproductives and worker classes are readily categorized based on size and external morphology. The overall organization of brain neuropile is comparable between castes with differences only in the visual ganglia. Males have a larger fraction of neuropile occupied by the medulla and lobula than females. In the diurnal species, C. sericeus these regions are more highly represented, than in the nocturnal species C. compressus. The most striking differences are in the antennal lobe where males possess a macroglomerulus, which is about ten times larger in volume than the other glomeruli; such a specialization is absent in females. Minor workers possess a significantly larger number of glomeruli than the majors despite the smaller overall volume of the lobe. These caste-specific differences occur mainly within glomerular clusters that receive input from sensory neurons that project in tracts - T4 and T5 - within the antennal nerve. The comparative anatomy of different castes of ants provides an entry point into a future systematic analysis of how divergent brain architectures can arise within a single species.

Caste and sex specific olfactory glomerular organization and brain architecture in two sympatric ant species Camponotus sericeus and Camponotus compressus (Fabricius, 1798).

The antennal lobes of different castes of the ant species Camponotus compressus show a marked diversity in the organization of their olfactory glomeruli. Notably, there is a significant difference in the number and size of glomeruli between the reproductives and the workers and among the different worker castes. In this report, we investigate the notion that these caste-specific differences in glomerular number might be accounted for, at least in part, by the differences in numbers of olfactory sensilla that target the antennal lobe. For this, we examine the number of sensilla on the antennal flagella of all the individual castes of C. compressus. This analysis reveals a striking correlation between sensillar number and the number of antennal glomeruli in a given caste. As a first step in investigating the causal mechanisms that might give raise to this correlation, we carry out an initial characterization of olfactory system development in the minor workers of C. compressus. We analyze the temporal pattern of innervations of the developing antennal lobe by olfactory sensory neuron axons. We document the development of the olfactory glomeruli in the antennal lobe during this process, which occurs during early pupal stages. Our findings provide the basis for future manipulative developmental studies on the role of sensory afferent number in glomerular development of different castes within the same species.

Morphological and developmental analysis of peripheral antennal chemosensory sensilla and central olfactory glomeruli in worker castes of Camponotus compressus (Fabricius, 1787).

Considerable effort has been directed towards understanding the organization and function of peripheral and central nervous system of disease vector mosquitoes such as Aedes aegypti. To date, all of these investigations have been carried out on adults but none of the studies addressed the development of the nervous system during the larval and pupal stages in mosquitoes. Here, we first screen a set of 30 antibodies, which have been used to study brain development in Drosophila, and identify 13 of them cross-reacting and labeling epitopes in the developing brain of Aedes. We then use the identified antibodies in immunolabeling studies to characterize general neuroanatomical features of the developing brain and compare them with the well-studied model system, Drosophila melanogaster, in larval, pupal, and adult stages. Furthermore, we use immunolabeling to document the development of specific components of the Aedes brain, namely the optic lobes, the subesophageal neuropil, and serotonergic system of the subesophageal neuropil in more detail. Our study reveals prominent differences in the developing brain in the larval stage as compared to the pupal (and adult) stage of Aedes. The results also uncover interesting similarities and marked differences in brain development of Aedes as compared to Drosophila. Taken together, this investigation forms the basis for future cellular and molecular investigations of brain development in this important disease vector.

Brain development in the yellow fever mosquito Aedes aegypti: a comparative immunocytochemical analysis using cross-reacting antibodies from Drosophila melanogaster.

Despite the devastating impact of mosquito-borne illnesses on human health, surprisingly little is known about mosquito developmental biology, including development of the olfactory system, a tissue of vector importance. Analysis of mosquito olfactory developmental genetics has been hindered by a lack of means to target specific genes during the development of this sensory system. In this investigation, chitosan/siRNA nanoparticles were used to target semaphorin-1a (sema1a) during olfactory system development in the dengue and yellow fever vector mosquito Aedes aegypti. Immunohistochemical analyses and anterograde tracing of antennal sensory neurons, which were used to track the progression of olfactory development in this species, revealed antennal lobe defects in sema1a knockdown fourth instar larvae. These findings, which correlated with a larval odorant tracking behavioral phenotype, identified previously unreported roles for Sema1a in the developing insect larval olfactory system. Analysis of sema1a knockdown pupae also revealed a number of olfactory phenotypes, including olfactory receptor neuron targeting and projection neuron defects coincident with a collapse in the structure and shape of the antennal lobe and individual glomeruli. This study, which is to our knowledge the first functional genetic analysis of insect olfactory development outside of D. melanogaster, identified critical roles for Sema1a during Ae. aegypti larval and pupal olfactory development and advocates the use of chitosan/siRNA nanoparticles as an effective means of targeting genes during post-embryonic Ae. aegypti development. Use of siRNA nanoparticle methodology to understand sensory developmental genetics in mosquitoes will provide insight into the evolutionary conservation and divergence of key developmental genes which could be exploited in the development of both common and species-specific means for intervention.

Disruption of Aedes aegypti olfactory system development through chitosan/siRNA nanoparticle targeting of semaphorin-1a.

Essentially nothing is known about the genetic regulation of olfactory system development in vector mosquitoes, which use olfactory cues to detect blood meal hosts. Studies in Drosophila melanogaster have identified a regulatory matrix of transcription factors that controls pupal/adult odorant receptor (OR) gene expression in olfactory receptor neurons (ORNs). However, it is unclear if transcription factors that function in the D. melanogaster regulatory matrix are required for OR expression in mosquitoes. Furthermore, the regulation of OR expression during development of the larval olfactory system, which is far less complex than that of pupae/adults, is not well understood in any insect, including D. melanogaster. Here, we examine the regulation of OR expression in the developing larval olfactory system of Aedes aegypti, the dengue vector mosquito.

Chitosan/siRNA nanoparticle targeting demonstrates a requirement for single-minded during larval and pupal olfactory system development of the vector mosquito Aedes aegypti.

Despite the devastating impact of mosquito-borne illnesses on human health, very little is known about mosquito developmental biology, including development of the mosquito visual system. Mosquitoes possess functional adult compound eyes as larvae, a trait that makes them an interesting model in which to study comparative developmental genetics. Here, we functionally characterize visual system development in the dengue and yellow fever vector mosquito Aedes aegypti, in which we use chitosan/siRNA nanoparticles to target the axon guidance gene semaphorin-1a (sema1a).

Role of semaphorin-1a in the developing visual system of the disease vector mosquito Aedes aegypti.

Most animal species exhibit sexually dimorphic behaviors, many of which are linked to reproduction. A number of these behaviors, including blood feeding in female mosquitoes, contribute to the global spread of vector-borne illnesses. However, knowledge concerning the genetic basis of sexually dimorphic traits is limited in any organism, including mosquitoes, especially with respect to differences in the developing nervous system.

Article	Year
Caste and sex specific olfactory glomerular organization and brain architecture in two sympatric ant species Camponotus sericeus and Camponotus compressus (Fabricius, 1798). Arthropod structure & development\| PubMed ID: 19539048	2009
Morphological and developmental analysis of peripheral antennal chemosensory sensilla and central olfactory glomeruli in worker castes of Camponotus compressus (Fabricius, 1787). Arthropod structure & development\| PubMed ID: 20438861	2010
Brain development in the yellow fever mosquito Aedes aegypti: a comparative immunocytochemical analysis using cross-reacting antibodies from Drosophila melanogaster. Development genes and evolution\| PubMed ID: 21956584	2011
Disruption of Aedes aegypti olfactory system development through chitosan/siRNA nanoparticle targeting of semaphorin-1a. PLoS neglected tropical diseases\| PubMed ID: 23696908	2013
Chitosan/siRNA nanoparticle targeting demonstrates a requirement for single-minded during larval and pupal olfactory system development of the vector mosquito Aedes aegypti. BMC developmental biology\| PubMed ID: 24552425	2014
Role of semaphorin-1a in the developing visual system of the disease vector mosquito Aedes aegypti. Developmental dynamics : an official publication of the American Association of Anatomists\| PubMed ID: 25045063	2014
Examination of the genetic basis for sexual dimorphism in the Aedes aegypti (dengue vector mosquito) pupal brain. Biology of sex differences\| PubMed ID: 25729562	2014

Keshava Mysore

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