Biology subjects

Guerrero, G.

Publications and source records attributed to Guerrero, G..

3 recordsLinked to original sources

bioRxiv2022

Formation of sulfoquinovosyl diacylglycerol by acylation of sulfoquinovosyl glycerol

Sulfoquinovosyl diacylglycerol (SQDG) is a membrane-forming lipid present in photosynthetic organisms as well as in distinct bacteria growing in phosphate-limited environments. Four genes for SQDG biosynthesis were previously identified in Rhodobacter sphaeroides, the operon sqdBDC and sqdA. In this work, we found that SMc02490 of Sinorhizobium meliloti is an SqdA orthologue. Expression of the S. meliloti sqdBDC operon in Escherichia coli results in formation of sulfoquinovosyl glycerol (SQGro), while co-expression of this operon together with smc02490 (sqdA) results in formation of SQDG. Furthermore, SqdA allows for incorporation of exogenous SQGro into SQDG in S. meliloti and in E. coli cultures, suggesting that presence of SqdA in bacteria permit them to use environmental SQGro for the biosynthesis of the membrane lipid SQDG. An in vitro enzymatic assay for the acyltransferase SqdA was developed. Cell-free crude extracts of E. coli expressing sqdA can efficiently convert [35S]-sulfoquinovosyl monoacylglycerol into SQDG using as acyl donor acyl carrier protein. Bioinformatic analyses reveal that this sulfoquinovose acylation pathway for SQDG biosynthesis is delimited to the Hyphomicrobiales (Rhizobiales) and Rhodobacterales orders of Alphaproteobacteria.

microbiology↗

bioRxiv2021

Differences in orthodenticle expression promote ommatidial size variation between Drosophila species

The compound eyes of insects exhibit extensive variation in ommatidia number and size, which affects how they see and underlies adaptations in their vision to different environments and lifestyles. However, very little is known about the genetic and developmental bases of differences in compound eye size. We previously showed that the larger eyes of Drosophila mauritiana compared to D. simulans is generally caused by differences in ommatidia size rather than number. Furthermore, we identified an X-linked chromosomal region in D. mauritiana that results in larger eyes when introgressed into D. simulans. Here, we used a combination of fine-scale mapping and gene expression analysis to further investigate positional candidate genes on the X chromosome. We found earlier expression of orthodenticle (otd) during ommatidial maturation in third instar larvae in D. mauritiana than in D. simulans, and we show that this gene is required for the correct organisation and size of ommatidia in D. melanogaster. We discovered that the activity of an otd eye enhancer is consistent with the difference in the expression of this gene between species, with the D. mauritiana enhancer sequence driving earlier expression than that of D. simulans. We also identified potential direct targets of Otd that are differentially expressed between D. mauritiana and D. simulans during ommatidial maturation. Taken together, our results suggest that differential timing of otd expression contributes to natural variation in ommatidia size between D. mauritiana and D. simulans, which provides new insights into the mechanisms underlying the regulation and evolution of compound eye size in insects.

evolutionary biology↗

bioRxiv2019

In situ dissection of domain boundaries affect genome topology and gene transcription in Drosophila

The molecular mechanisms responsible for Topologically Associated Domains (TADs) formation are not yet fully understood. In Drosophila, it has been proposed that transcription is fundamental for TAD organization while the participation of genetic sequences bound by Architectural Proteins (APs) remains controversial. Here, we investigate the contribution of domain boundaries to TAD organization and the regulation of gene expression at the Notch gene locus in Drosophila. We find that deletion of domain boundaries results in TAD fusion and long-range topological defects that are accompanied by loss of APs and RNA Pol II chromatin binding as well as defects in transcription. Together, our results provide compelling evidence on the contribution of discrete genetic sequences bound by APs and RNA Pol II in the partition of the genome into TADs and in the regulation of gene expression in Drosophila.

genomics↗