Biology subjects

Higa, L.

Publications and source records attributed to Higa, L..

5 recordsLinked to original sources

bioRxiv2026

Multiplex Genome Editing Overcomes Photoperiod Sensitivity in Tropical Maize

Tropical maize is a rich source of genetic diversity that could enhance temperate maize breeding programs, but its sensitivity to long-day photoperiods, resulting in delayed flowering, limits its widespread use. To overcome this barrier, the Genome Engineering to Sustain Crop Improvement (GETSCI) project used CRISPR/Cas9 to mutate three flowering repressor genes, ZmCCT9, ZmCCT10, and ZmRAP2.7, in the tropical inbred Tzi8. A single sgRNA targeting the first exon of each target gene was combined with an excision cassette carrying the morphogenic genes Babyboom (Bbm) and Wuschel2 (Wus2) to enable efficient transgenic plant regeneration. Transgenic plants carrying frameshift edits in each target gene were recovered, and subsequent crosses produced two non-transgenic genotypes: a double-edited zmcct10, zmrap2.7 line and a triple-edited zmcct9, zmcct10, zmrap2.7 line. Multiple flowering traits were measured for the edited genotypes and unedited Tzi8 inbred in short-day (Hawai i) and long-day (Iowa) field conditions. Both edited genotypes flowered significantly earlier than Tzi8 in both environments. Notably, under long-day conditions, flowering of the two edited lines overlapped with that of the temperate inbred B73, whereas Tzi8 did not. Together, these results demonstrate that targeted, multiplex gene editing can reduce photoperiod sensitivity in a tropical inbred, expanding access to previously untapped genetic diversity for temperate maize improvement.

plant biology↗

bioRxiv2023

Saxitoxin potentiates Zika virus-induced cell death in human neurons but not in neural progenitors and astrocytes

The Zika virus (ZIKV) outbreak in Brazil between 2015 and 2016 was associated with an increased prevalence of severe congenital malformations, including microcephaly. Notably, the distribution of microcephaly cases was not uniform across the country, with a disproportionately higher incidence recorded in the Northeast region (NE). Our previous work demonstrated that saxitoxin (STX), a toxin ubiquitously present in the drinking water reservoirs of the NE, exacerbated the damaging effects of ZIKV on the developing brain. In the present study, we hypothesized that STXs impact might vary among different neural cell types. Our experimental observations suggest that exposure to STX potentiates the neurotoxic effect of Zika Virus (ZIKV) on human neuronal cells. However, while ZIKV infection demonstrated severe impacts on astrocytes and neural stem cells (NSCs), the addition of STX did not exacerbate these effects. We observed that neurons subjected to STX exposure were more prone to apoptosis and displayed a higher number of ZIKV-infected cells. These findings suggest that STX exacerbates the harmful effects of ZIKV on neurons, thereby providing a plausible explanation for the heightened severity of ZIKV-induced congenital malformations observed in Brazils NE. This study underscores the importance of understanding the interactive effects of environmental toxins and infectious pathogens on neural development, with potential implications for public health policies and interventions.

neuroscience↗

bioRxiv2022

Polycomb Repressive Complex 1 subunit Cbx4 positively regulates effector responses in CD8 T cells

CD8 T cell differentiation is controlled by the crosstalk of various transcription factors and epigenetic modulators. Uncovering the different players in regulating this process is fundamental to improving immunotherapy and designing novel therapeutic approaches. Here, we show that Polycomb Repressive Complex (PRC)1 subunit Chromobox (Cbx)4 favors differentiation to effector CD8 T cells. Cbx4 deficiency in CD8 T cells induced transcriptional signature and phenotype of memory cells, increasing the formation of memory population during acute viral infection. It has been previously shown that besides chromodomain-mediated binding to H3K27me3, Cbx4 function as a SUMO E3 ligase in a SUMO interacting motifs (SIM)-dependent way. The overexpression of Cbx4 mutants in distinct domains showed that this protein regulates CTL differentiation primarily in a SIM-dependent way and partially through its chromodomain. Our data revealed a novel role of a Polycomb group protein Cbx4 controlling CD8 T lymphocyte differentiation and indicates the SUMOylation process as a key molecular mechanism connected to chromatin modification in this process. SummaryUnderstanding the epigenetic control of CTL differentiation is critical for the manipulation of these cells in immunotherapy protocols. This article demonstrates a novel role for Cbx4, a Polycomb-group protein, in supporting CD8 T cell commitment to an effector cell phenotype.

immunology↗

bioRxiv2019

The cyanobacterial saxitoxin exacerbates neural cell death and brain malformations induced by Zika virus

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak was described in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the amount of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.\n\nAuthor summaryThe uncontrolled spreading of cyanobacteria in drinking water reservoirs has been the cause of serious public health problems worldwide. Toxin-producing cyanobacterial blooms commonly occur during drought periods in the northeast (NE) region of Brazil. During Zika Virus (ZIKV) outbreak in 2015-16, Brazilian NE showed disproportionately higher microcephaly incidence. Here, we test the hypothesis that the cyanotoxin saxitoxin (STX) may act as a co-insult for ZIKV. Water quality surveillance data showed increased cyanobacteria population and higher STX amount in NE region during 2014-2018. In vitro, we observed that neural progenitor cell death was doubled after STX exposure to ZIKV-infected brain organoids. In vivo, chronic ingestion of STX during gestational period potentiated ZIKV-derived brain abnormalities in newborn mice. Our study provides new insights that may explain the discrepancies among Brazilian regions regarding CZS severity. Moreover, the data highlight the importance of cyanobacteria and cyanotoxin freshwater monitoring for future arbovirus outbreaks.

neuroscience↗

bioRxiv2018

Yellow fever virus is susceptible to sofosbuvir both in vitro and in vivo

Yellow fever virus (YFV) is a member of the Flaviviridae family, that causes major mortality. In Brazil, YFV activity increased in the last years. It has been registered that sylvatic, instead of urban, yellow fever (YF) leads our contemporary public health concern. Low vaccinal coverage leaves the human population near the jangle vulnerable to the outbreak, making it necessary to identify therapeutic options. Repurposing of clinically approved antiviral drugs represents an alternative for such identification. Other Flaviviruses, such Zika (ZIKV) and dengue (DENV) viruses, are susceptible to Sofosbuvir, a clinically approved drug against hepatitis C virus (HCV). Moreover, sofosbuvir has a safety record on critically ill hepatic patients, making it an attractive option. Our data show that YFV RNA polymerase uses conserved amino acid resides for nucleotide binding to dock sofosbuvir. This drug inhibited YFV replication in different lineages of human hepatoma cells, Huh-7 and HepG2, with EC50 value of 4.8 {micro}M. Sofosbuvir protected YFV-infected neonatal Swiss mice from mortality and weight loss. Our pre-clinical results indicate that sofosbuvir could represent an option against YFV.

microbiology↗