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Quantum dots (QDs) are colloidal semiconductor nanocrystals of a few nanometers in diameter, being their size and shape controlled during the synthesis. They are synthesized from atoms of group II–VI or III–V of the periodic table, such as cadmium telluride (CdTe) or cadmium selenium (CdSe) forming nanoparticles with fluorescent characteristics superior to current fluorophores. The excellent optical characteristics of quantum dots make them applied widely in the field of life sciences. Cellular uptake of QDs, location and translocation as well as any biological consequence, such as cytotoxicity, stimulated a lot of scientific research in this area. Several studies pointed to the cytotoxic effect against micoorganisms. In this mini-review, we overviewed the synthesis and optical properties of QDs, and its advantages and bioapplications in the studies about microorganisms such as protozoa, bacteria, fungi and virus.

BackgroundChagas disease is a complex anthropozoonosis with distinct domestic and sylvatic mammal species acting as potential reservoirs. The diversity of vector species and their habitats are among the factors that hinder the control of the disease. Control programs periodically monitor the prevalence of T. cruzi infection in insect bugs through microscopical observation of diluted feces. However, microscopy presents limited sensitivity in samples with low parasite numbers, difficulties in examining all evolutionary stages of the insect and may in turn be limited to differentiate T. cruzi from other morphologically similar trypanosomatids. Here, we report two highly sensitive and accurate methodologies to infer T. cruzi infection rates and to quantify parasite load in the gut of field-collected triatomines.MethodsTriatomines were manually collected in the period 2011–2012 and 2014–2015, in domestic, peridomestic or sylvatic habitats in rural areas of 26 municipalities, encompassing three distinct Brazilian biomes: Caatinga, Cerrado and Atlantic Rainforest. Following morphological and taxonomical identification, the search for flagellated protozoa was performed by optical microscopy. A conventional PCR targeting T. cruzi kDNA and a TaqMan qPCR directed to the parasite nuclear satellite DNA (SAT) were developed, both in multiplex, with the triatomine 12S subunit ribosomal RNA gene, used as internal amplification control. Both methods were used for detection (kDNA-PCR) and parasite load quantification (SAT-DNA-qPCR), to investigate T. cruzi infection in captured triatomines.ResultsThe combined methods were assayed on a panel of 205 field-collected triatomine samples. Diagnostic analysis revealed 21% positivity for the kDNA-PCR, whereas microscopic examination enabled identification of T. cruzi in only 7.0% of the PCR-positive samples. Negative PCR results were confirmed by the absence of T. cruzi flagellates using microscopy. Caatinga biome yielded the highest T. cruzi infection rate (60%), followed by the Atlantic Rainforest and Cerrado with 7.1 and 6.1%, respectively. In addition, a wide range distribution of parasite load, varying from 8.05 × 10-2 to 6.31 × 1010 was observed with a median of 2.29 × 103 T. cruzi/intestine units. When parasite load was analyzed by triatomine species, a significantly higher median was found for Panstrongylus lutzi in comparison with Triatoma brasiliensis.ConclusionsOur results demonstrate highly sensitive PCR-based methodologies to monitor T. cruzi infection in triatomines. In addition, the qPCR assay offers the possibility of further evaluation parasite load, as a promising biomarker of the vectorial capacity of triatomines in Chagas disease endemic areas.Electronic supplementary materialThe online version of this article (10.1186/s13071-017-2343-x) contains supplementary material, which is available to authorized users.

Morphological studies in male reproductive system of insect, and accessory glands functions, can contribute to the knowledge of reproductive aspects in Triatominae. The present study aims to describe the structure of male reproductive system under scanning electron microscopy, and the ultrastructure of accessory glands during the process of maturation, in T. brasiliensis and T. melanica of different ages. These system consist of two testis, two vas deferens, two seminal vesicles, four pair of accessory glands and one ejaculatory duct. The four mesodermal male accessory glands of T. melanica and T. brasiliensis, present secretion storage in the first days of adult life in starved males. During the maturation process of male accessory glands of T. brasiliensis and T. melanica, granules with different sizes, shapes and electron density were seen. In T. melanica small vacuoles are released into the gland lumen in one-day-old males, however, after three and five days few granules are found in the cell cytoplasm. The secretory granules in T. brasiliensis increase in size and amount, in the five days old adult. The secretory pathway in the male accessory glands of the two species seems to be merocrine and apocrine suggesting that different substances are being produced at different times. The cell microvilli in T. brasiliensis are longer and narrower, these can be absent in some regions of the cell surface of T. melanica. Maturation of male accessory glands in the triatomine species studied occurred without adult blood meal. Its function can led to new insights for the comprehension of reproductive aspects in Triatominae.

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Cimex hemipterus (Fabricius) is a hematophagous insect that can be an experimental host of Trypanosoma cruzi and may play a role as vector of Chagas' disease. This work analyzed the structure of the salivary glands of C. hemipterus. The secretory portion of main salivary glands has a single oval lobe that is translucent and is formed from a simple columnar epithelium lined by muscle cells. The gland cells are high, with one or two spherical nuclei, nucleolus, and some condensed chromatin. The cell cytoplasm has a well-developed rough endoplasmic reticulum, electron lucent vesicles, lysosomes, and glycogen deposits. The apical plasma membrane has microvilli, zonula adherens, and desmosomes, whereas the basal plasma membrane has some infoldings associated with mitochondria. The duct of the main salivary glands has flattened cells. The secretory portion of the accessory salivary glands is a single vesicular lobe that is translucent and is formed from a single layer of cells that varies from flattened to cubical onto muscle cells. The cytoplasm contains a well-developed smooth endoplasmic reticulum, vacuoles of different sizes containing secretions, electron lucent, and abundant mitochondria. The baso-lateral plasma membrane of adjacent cells shows septate junctions. The duct is formed from a flattened epithelium like the duct of the principal salivary gland. The secretory cells of the main salivary glands are related to protein synthesis and transport of ions. However, the secretory cells of the accessory salivary glands are related mainly to transport of ions and water from the hemolymph to glandular lumen.

Deoxyribonucleic acid (DNA) barcode (cytochrome c oxidase subunit I [COI]) sequences have been used to associate adult and immature stages of stoneflies as a rapid and effective alternative to rearing immatures. However, no molecular associations have been made for Neotropical species, which have very few described immature stages. Kempnyia Klapálek (Perlidae) is an endemic South American genus. Currently, 20 females have been associated with males of the 40 valid species, but only 5 nymphs have been described. We collected stonefly nymphs at Macaé River Basin, Rio de Janeiro State, Brazil, and Kempnyia nymphs were separated those in 6 morphotypes. These morphotypes were associated to nominal Kempnyia species using 38 COI sequences (471 base pairs [bp]) of immatures and identified adults of 10 species occurring in southern and southeastern Brazil. Based on a neighbor-joining analysis of Kimura-2-parameter (K2P) pairwise divergences, we found 6 genetic Kempnyia lineages at Macaé River Basin represented by all morphotypes of nymphs included in our study. These nymphs were associated with males of Kempnyia alterosarum, K. colossica, K. gracilenta, K. petersorum, K. obtusa, and K. varipes. Intraspecific divergences in Kempnyia varied from 0 to 15%, but ∼½ of comparisons had values >3%. These data are in agreement with previous studies with stonefly populations, which tend to show high COI divergences. Based on our results, we described previously unknown immatures of K. alterosarum, K. petersorum, and K. obtusa, and the male genitalia of K. varipes for the first time. We also described a new adult color morph of K. petersorum. Our study increased the number of Kempnyia species recorded at Macaé River Basin from 5 to 11. We recorded for the first time K. alterosarum and K. reticulata from Rio de Janeiro State and K. jatim from Espírito Santo State.

Male of Triatoma rubrofasciata has four elongated sac-like reproductive mesodermic accessory glands, lined by an inner single layer of secretory cells, with basal plasma membrane infolds and short apical microvilli, and externally enveloped by a thin visceral muscle layer. The secretory cells have a well-developed rough endoplasmic reticulum, Golgi complex, mitochondria, and secretory granules. In one day old adult the gland cells are poorly developed, presenting small, electron-transparent secretory granules scattered among the rough endoplasmatic reticulum, whereas in three days old adult these cells have the cisternae of the rough endoplasmatic reticulum varing size degree, filled with granular electrondense content. In five days old males the secretory granules increase in diameter, being released to the gland lumen. Therefore, there is an increase of the secretory activity according to male maturation.