Biology subjects

Austriaco, N.

Publications and source records attributed to Austriaco, N..

6 recordsLinked to original sources

bioRxiv2026

A Reference Genome for the Critically Endangered Philippine Eagle (Pithecophaga jefferyi), the National Bird of the Philippines

The worlds largest and rarest eagle, the Philippine Eagle (Pithecophaga jefferyi), also known as the monkey-eating eagle, is the national bird of the Philippines. This raptor species is endemic to the Philippine archipelago, with populations on the islands of Luzon, Leyte, Samar, and Mindanao. It is critically endangered, with an average estimated population of 392 potentially breeding pairs or 784 mature individuals. In this paper, we describe a reference genome of the Philippine Eagle (Pithecophaga jefferyi) from a female juvenile from the province of Nueva Ecija on the island of Luzon. We generated a de novo genome assembly with high contiguity and completeness, comprising 178 contigs totaling 1.345 Gbp. The genome was sequenced at a coverage of 75.2x, and Benchmarking Universal Single-Copy Orthologs (BUSCO)/Compleasm analysis yielded a BUSCO score of 99.92% (aves_odb12), corresponding to 99.7% single-copy, 0.21% duplicated, and 0.08% fragmented genes. A consensus mitogenome sequence of 19,377 bp was also generated. The genome assembly included 23,847 putative genes, and our annotation estimated that 15.78% of the genome consisted of repetitive elements. Genome heterozygosity (H) was estimated to be 0.020%, in comparison to other birds with genome heterozygosity values ranging from 0.0103% to 0.923%. Whole-genome comparisons with publicly available genomes suggest that the Philippine eagle belongs to the snake-eagle subfamily (Circaetinae) rather than the harpy-eagle subfamily (Harpiinae). Pairwise sequentially Markovian coalescent (PSMC) analysis suggests that the effective population size was around 4,000 individuals from about 100 KYA to about 1 KYA. Finally, we constructed a minimum spanning network, which revealed that our mitogenome from the northern island of Luzon occupies a peripheral position, separated from the dominant haplotype cluster found in the southern island of Mindanao by multiple mutational steps, indicating substantial mitochondrial divergence.

genomics↗

bioRxiv2025

A Secreted Subunit SARS-CoV-2 RBD-CpE Yeast Oral Vaccine Induces an Adaptive Immune Response in BALB/c Mice

Despite their differences, all the current COVID-19 vaccines need to be refrigerated and administered intramuscularly by a health care worker. They are also relatively expensive. These characteristics often make COVID-19 vaccine storage, distribution, and administration relatively complex, especially in low- and middle-income countries where refrigeration and healthcare workers are limited. To address these challenges, we are developing a COVID-19 oral vaccine utilizing the yeast Saccharomyces boulardii as a delivery platform. We have successfully engineered recombinant strains of Saccharomyces boulardii to express and secrete the Receptor Binding Domain (RBD) of the Spike protein from the original Wuhan-Hu-1 strain of the SARS- CoV-2 virus, fused to the C-terminal fragment of Clostridium perfringens enterotoxin (CpE). Animal trials suggest that our candidate secreted oral yeast vaccine can elicit detectable RBD- specific IgG and IgA, as well as an IFN-{gamma} but not an IL-4 response, in BALB/c mice. As such, our data suggest that Saccharomyces boulardii remains a promising and novel vaccine delivery platform not only for COVID-19 but also for other infectious diseases.

immunology↗

bioRxiv2025

Construction of an MRCUT1 Cutinase-Expressing Saccharomyces boulardii Probiotic Yeast Strain Capable of Degrading Polyethylene Terephthalate (PET) Microplastics

Excessive use of plastics has led to an unprecedented global accumulation of plastic waste, particularly of the polyethylene terephthalate (PET) polymer, resulting in severe environmental and health challenges due to the proliferation of microplastic particles. To respond to this environmental challenge, especially in the Philippines, where single-use plastic sachet pollution is rampant, we genetically engineered Saccharomyces boulardii yeast cells to express and secrete the cutinase enzyme (MRCUT1) derived from the fungus Moniliophthora roreri. Our results suggest that our engineered yeast can degrade pre-weighed PET fragments over a twenty-one-day period in vitro, with significant measurable weight reductions observed within the first week of incubation. Statistical analysis (One-way ANOVA, p = 0.0112) confirmed that our MRCUT1 engineered strain degraded PET at a significantly higher rate than non-engineered control cells. To the best of our knowledge, this is the first time that a cutinase capable of PET degradation has been successfully expressed in and secreted by yeast. It also opens up the possibility that our MRCUT1-expressing probiotic could be used prophylactically to mitigate the microplastic bioaccumulation in the gastrointestinal tracts of common food fish like the rabbitfish (Siganus fuscescens) and the milkfish (Chanos chanos), both of which are popular aquaculture fish in the Philippines.

microbiology↗

bioRxiv2019

Yeast Bax Inhibitor (Bxi1p/Ybh3p) is a Calcium Channel in E. coli

Human Bax Inhibitor-1 (HsBI-1/TMBIM6) is the founding member of the evolutionary conserved TMBIM superfamily of proteins that share sequence homology within the transmembrane Bax inhibitor-containing motif (TMBIM). Mechanistically, BI-1/TMBIM6 and all the other mammalian TMBIM proteins appear to be involved in the maintenance of calcium homeostasis, and the crystal structure of a bacterial TMBIM protein, BsYetJ, suggests that the protein is a pH-sensitive calcium leak. The budding yeast, Saccharomyces cerevisiae, has a single TMBIM family member (YNL305C) named Bxi1p/Ybh3p. To determine the function of Bxi1p/Ybh3p, we overexpressed Bxi1p-EGFP in E. coli to determine if it is a calcium channel. We show that bacterial cells expressing Bxi1p-EGFP are more permeable to calcium than controls. Thus, our data suggests that yeast Bax inhibitor (Bxi1p) is a calcium channel in E. coli, lending support to our proposal that Bxi1p is a bona fide member of the TMBIM family of proteins. Further, we use our bacterial system to show that gadolinium is an inhibitor of Bxi1p in vivo, suggesting a path forward to identifying other small-molecular inhibitors of this clinically-important and highly conserved superfamily of proteins. Finally, parallel experiments revealed that the human Bax Inhibitor-1 (HsBI-1/TMBIM6) is also a calcium channel in bacteria that can be inhibited by gadolinium.

molecular biology↗

bioRxiv2018

Metabolism-Induced Oxidative Stress and DNA Damage Selectively Trigger Genome Instability in Polyploid Cells

Understanding the forces impacting genome stability is important for diverse processes such as tumorigenesis and reproductive biology. The pathogenic yeast Candida albicans displays unusual genome dynamics in which tetraploid cells, but not diploid cells, become unstable when grown on a glucose-rich pre-sporulation medium. Here, we reveal that C. albicans polyploid cells are metabolically hyperactive on this medium as evidenced by increased expression of metabolic genes as well as higher rates of fermentation and oxidative respiration. These cells also show elevated levels of reactive oxygen species (ROS), activate the ROS-responsive transcription factor Cap1, and accrue DNA double-strand breaks. Suppression of ROS levels reduced oxidative stress, DNA damage and chromosome instability. These studies reveal how metabolic flux can generate endogenous ROS, triggering DNA damage and genome instability in polyploid, but not diploid, cells. We discuss parallels with metabolism-induced instability in cancer cells and propose that ROS-induced DNA damage could have facilitated ploidy cycling in eukaryotes prior to the evolution of meiosis.

microbiology↗

bioRxiv2018

Sulforaphane Alters the Acidification of the Vacuole to Trigger Cell Death

Sulforaphane (SFN) is a compound [1-isothiocyanato-4-(methylsulfinyl)- butane] found in broccoli and other cruciferous vegetables that is currently of interest because of its potential as a chemopreventive and a chemotherapeutic drug. Recent studies in a diverse range of cellular and animal models have shown that SFN is involved in multiple intracellular signaling pathways that regulate cell death, cell cycle progression, and cell invasion. In order to better understand the mechanisms of action behind SFN-induced cell death, we undertook an unbiased genome wide screen with the yeast knockout (YKO) library to identify SFN sensitive (SFNS) mutants. Our mutants were enriched with knockouts in genes linked to vacuolar function suggesting a link between this organelle and SFNs mechanism of action in yeast. Our subsequent work revealed that SFN increases the vacuolar pH of yeast cells and that varying the vacuolar pH can alter the sensitivity of yeast cells to the drug. In fact, several mutations that lower the vacuolar pH in yeast actually made the cells resistant to SFN (SFNR). Finally, we show that human lung cancer cells with more acidic compartments are also SFNR suggesting that SFNs mechanism of action identified in yeast may carry over to higher eukaryotic cells.

cell biology↗