Biology subjects

Koerich, L. B.

Publications and source records attributed to Koerich, L. B..

4 recordsLinked to original sources

bioRxiv2025

Retention of a single Cenp-C gene in different syntenic locations in the montium group of Drosophila species

Chromosome segregation in eukaryotes requires the orchestrated interaction of chromosomes with microtubules, mediated by the kinetochore multiprotein complex that assembles on specific chromosomal regions known as centromeres. In most eukaryotes, two centromeric proteins, CenH3 and Cenp-C, are essential for centromere function. In Drosophila, the localization of CenH3 (referred to as Cid in Drosophila) depends on its chaperone CAL1 and Cenp-C. Previous studies have shown that both Cid and Cenp-C underwent a coincident gene duplication and likely functional specialization in the Drosophila subgenus. Independently, Cid duplications led to Cid1, Cid3, and Cid4 paralogs in the montium group (Sophophora subgenus), but it is unknown whether this group also underwent parallel duplications of Cenp-C. Here, we investigate this possibility by analyzing sequenced genomes of 23 montium group species. We identified Cenp-C genes in five distinct syntenic loci; we named these genes Cenp-C1b, Cenp-C1c, Cenp-C1d, Cenp-C1e and Cenp-C3. Despite their distinct synteny, most montium group species only encode a single Cenp-C; their phylogeny mirrors the species phylogeny, and they appear to have retained Cenp-C protein motifs indicative of function. A closer examination revealed that these Cenp-C genes resulted from gene translocations or alternate retention (duplication followed by loss of the ancestral copy); only one species, D. vulcana, retains two intact Cenp-C paralogs. Therefore, unlike the Drosophila genus, the co-retention of three Cid paralogs in the montium group has not resulted in a coincident Cenp-C paralog co-retention. Our work highlights differences in functional retention and likely specialization of the two most conserved centromeric proteins in eukaryotes.

genetics↗

bioRxiv2025

Diversity of trypanosomatids in small mammals from a forest fragment at the wildlife-urban interface in southeastern Brazil: implications for public health surveillance

This study investigated the diversity of trypanosomatids infecting small mammals in a fragmented forest landscape in southeastern Brazil, aiming to clarify their role in transmission cycles and assess potential public health risks. Eighteen individuals from three species - Didelphis albiventris (n = 8), Marmosops incanus (n = 4), and Nectomys squamipes (n = 6) - were captured in the Mata da Tapera Municipal Natural Park (MT), located within the Espinhaco Range Biosphere Reserve, Minas Gerais State. Xenodiagnosis using Lutzomyia longipalpis and Rhodnius neglectus, followed by 18S rDNA nested PCR, enabled the detection of Leishmania infantum, L. braziliensis, and Trypanosoma cruzi DTU TcI in insects fed on naturally infected hosts. Tissue and organ samples were also analyzed by in vitro culture and molecular diagnostics. Leishmania infantum was identified in D. albiventris (n = 2), L. braziliensis in M. incanus (n = 1), T. cruzi TcI in D. albiventris (n = 2), and Trypanosoma lainsoni in both D. albiventris and N. squamipes (n = 1 each), the latter representing the first record of this parasite in that rodent species. This integrated approach provides a valuable model for zoonotic surveillance at the wildlife-urban interface, enhancing diagnostic sensitivity and species identification. These findings confirm the presence of zoonotic trypanosomatids in a highly anthropized landscape and highlight transmission risks to humans and domestic animals, particularly in an area with active ecotourism, underscoring the need for targeted surveillance within a One Health framework. Author summaryIn many parts of Brazil, forested areas are getting smaller and more fragmented due to urban growth. These changes increase the contact between wild animals, domestic animals, and humans, creating new opportunities for diseases to spread. In this study, we examined small wild mammals living in a forest fragment close to human settlements in southeastern Brazil to find out if they carried parasites that can also infect humans. We used a combination of techniques, including allowing laboratory-raised insects to feed on these animals, to detect the presence of different parasites. We found that these mammals were naturally infected with species of Leishmania and Trypanosoma, including those that cause leishmaniasis and Chagas disease in humans. We also detected Trypanosoma lainsoni, a lesser-known parasite, for the first time in one rodent species. Our findings suggest that small mammals living in areas where forests meet cities may play an important role in maintaining and spreading parasites that affect public health. This study shows the importance of monitoring wildlife in changing environments and supports the idea that human, animal, and environmental health are deeply connected.

molecular biology↗

bioRxiv2022

The genome of the brackish-water malaria vector Anopheles aquasalis

Anopheles aquasalis is a primary malaria vector in coastal South America that grows in brackish waters of mangroves. Its importance has increased in recent years as it has been established as a model for parasite-vector studies for non-model Plasmodium species, such as P. yoelli. In this study, we present the complete genome of An. aquasalis and offer some insights into evolution and physiology. With a 162Mb and 12,446 coding proteins, the An. aquasalis genome is similar in size and gene content as other neotropical anophelines. 1,038 single-copy orthologs are present in An. aquasalis and all Diptera and it was possible to infer that An. aquasalis diverged from An. darlingi (the main malaria vector in inland South America) nearly 14 million years ago (mya). Ion transport and metabolism proteins is one the major gene families in An. aquasalis with 660 genes. Amongst these genes, important gene families relevant for osmosis control (e.g., aquaporins, vacuolar-ATPases, Na+/K+-ATPases and carbonic anhydrases) were identified in one-to-one orthologs with other anophelines. Evolutionary analysis suggests that all osmotic regulation genes are under strong purifying selection. We also observed low copy number variation in immunity-related genes (for which all classical pathways were described) and insecticide resistance genes. This is the third genome of a neotropical anopheline published so far. The data provided by this study may offer candidate genes for further studies on parasite-vector interactions and for studies on how brackish water anophelines deals with high fluctuation in water salinity. Significance StatementThe brackish water mosquito Anopheles aquasalis is a primary malaria vector in coastal South America. Besides its peculiar ecological features (it is one of the few anopheline mosquitoes that survives high fluctuation of water salinity), An. aquasalis has gained relevance in recent years as a model for parasite-vector studies for non-model Plasmodium parasites. Still, the physiology and genetics of An. aquasalis are poorly understood. Here we present the genome of An. aquasalis with more than 12,000 annotated genes, offering insights in genome evolution, osmoregulation related, immunity, chemosensory and insecticide resistance genes. The data presented here will help to further advance the studies on An. aquasalis genetics and physiology to better understand parasite-vector interactions in non-model organisms.

genomics↗

bioRxiv2019

Analysis of the testis transcriptome of the Chagas’ disease vector Rhodnius prolixus

Rhodnius prolixus is amongst the most important vectors of Trypanosoma cruzi in the Americas, putting thousands of people at risk of contracting Chagas Disease. This insect is also one of the most important models in insect physiology, especially regarding the blood-feeding process. However, studies on R. prolixus genetics lagged, and our understanding on the regulation of gene expression is incipient. Transcriptomes have the power to study the expression of thousands of genes in a single experiment. A comprehensive R. prolixus transcriptome was performed in 2014, sequencing RNA from different tissues (anterior gut, midgut, posterior gut, rectum, ovaries, fat body, maphigian tubules, and testicles). However, on that occasion, only the gut transcriptome was deeply analysed. Here we evaluated the results of the testicles transcriptome of R. prolixus with the objective to find and understand genes that could have an important role in male reproduction. We found, that from the 25,673 transcripts assembled in the whole transcriptome, 5,365 have a testicle specific expression pattern. As expected, amongst the most abundant families of transcripts, are those related to spermatogenesis and male fertility, such as myosins, actins, and dyneins. To our surprise, lipocalins, serine protease inhibitors (serpins), and lysozymes also were highly abundant in testicles. The role of these classes of genes are well known in other tissues, such as salivary glands and gut, but very little is known on their role in male reproduction (and we proposed here a few hypothesis that could be tested to address the role of these genes in male fertility). It would be interesting to study further the role of these genes on R. prolixus male fertility. Finally, as a reflection of the lack of knowledge on triatomine genetics, we found that almost half of the transcripts in R. prolixus testicles have no similarities to any other genes on reference databases. Our study shows that we still have a lot to know and to understand about reproduction in triatomine, especially in males. Besides the large number of genes without described function (possibly novel genes), there are those in which the function is known for other tissues, and we can only guess, at best, the role and importance of such genes for triatomine male fertility. Author SummaryThe understanding of the biology of insects vectors of parasitic diseases is key to the development of strategies of public health. For decades, the studies on the biology of male insects vectors of diseases was neglected, since in many cases female insects are those with relevant role in the spread of diseases. With the development of genomics, large scale studies to compare differential gene expression (transcriptomics) among different tissues, developmental stages, and sex became accessible. In this study, we looked at the physiology of the male reproductive organs of the vector of Chagas disease Rhodnius prolixus. This is a first glimpse, from a perspective of genes differentially expressed in male gonads, in such insects. We also performed an effort to link all identified genes with the insect genome published in 2015. We found ~14,000 genes expressed in the testicles, from which 5,635 genes are expressed exclusively in male reproductive organs. From the ~14,000 genes, we were able to attribute putative biological functions to 6,372 genes, which allowed us to draw a bigger picture on how these genes contribute to male fertility. This study now opens the door for further in-depth studies to find key genes for R. prolixus reproductive biology.

genomics↗