User:Lizbeth Nunez

The account of this former contributor was not re-activated after the server upgrade of March 2022.

Member of Queens College Microbiology class participating on a laboratory report project. I also work in an undergraduate independent research project. I have gained a lot of knowledge through my research. In the Meléndez’ lab, we study the bec-1 gene, which is the C. elegans ortholog of human beclin 1 and yeast Atg6/Vps30. Human beclin 1 is a tumor suppressor autophagy gene. bec-1 homozygous mutants, lacking both the maternal and zygotic expression of bec-1, die as embryos. One of my projects involves single nucleotide polymorphism (SNP) mapping of sub-2 (suppressor of bec-1 dependent lethality), a suppressor mutation of the bec-1 lethal phenotype. Genetics data show that sub-2 is semidominant and X-linked. Using SNP mapping we will determine the chromosomal interval that contains the sub-2 mutation. I have also been working on the nematodes’ development. When C. elegans face stressful conditions (i.e increased temperature, overcrowdness, food deprivation) they enter an alternative third larval stage that is adapted to survive harsh conditions. In a paper published in Science on 2003 by my mentor Dr. Alicia Meléndez, she showed that animals that lacked the activity of bec-1, as well as other autophagy genes, did not form normal dauers. This was done by RNA-mediated interference (RNAi). Part of my project was to determine the role of a chromosomal mutation of bec-1 on dauer development. To this end, we tested mutations of daf-2(m41) or daf -7(m62), which have a constitutive dauer phenotype, in double mutant combinations with chromosomal mutations (instead of RNAi) for bec-1. m41 is a mutation in the IGF tyrosine kinase receptor, DAF-2. m62 is a mutation in the TGF-β ligand, DAF-7. In both types of mutants, animals growing at 25oC form dauers. These are characterized by constriction and elongation of the body and pharynx, an increase in fat accumulation, resistance to incubation with detergent SDS, and long survival. The dauer stage can be reversed if the animals are transferred to the permissive temperature, 15oC. We wanted to know whether daf-2; bec-1 or daf-7; bec-1 mutants would form normal dauers at 25oC. However, surprisingly, daf-7(m62); bec-1(ok691) as well as the daf-2(m41); bec-1(ok691) double mutants were able to form normal dauers. These are not the results that we expected. One possible explanation for this is a maternal effect: the mother provides bec-1 maternally derived that allows the double mutants to undergo the morphological changes associated with dauer development. RNAi treatment inactivates both maternally and zygotically derived expression of the gene in questions. This is an ongoing project and we are now testing the strains with PCR to confirm the mutations in the new strains, and to explore this possibility.