Biological Sciences
http://hdl.handle.net/10211.3/10211.4_16
2024-03-29T13:59:51ZArabidopsis thaliana class III peroxidase, AT5G51890, targeted to cell wall of protoxylem cells may be involved with cell elongation and xylem formation
http://hdl.handle.net/10211.3/214582
Arabidopsis thaliana class III peroxidase, AT5G51890, targeted to cell wall of protoxylem cells may be involved with cell elongation and xylem formation
Lin, Sheng-Hao
Secretory class III peroxidases are hypothesized to be involved with lignification and auxin catabolism. Lignification is polymerization that can strengthen the water conducting tissues and support the plant system. Auxin is growth hormone that promotes plant root growth. There are 73 peroxidases in the Arabidopsis thaliana. Determining where the protein traffics to the final location within the cell can help identify the function of each peroxidase. In this study, peroxidase AT5G51890 contains signal peptide, which directs for trafficking into endoplasmic reticulum (ER). Moreover, there is absence of hydrophobic tail in carboxyl terminal of peroxidase, which suggested that peroxidase AT5G51890 will target at cell wall. In 2009, Tokunage et al showed staining pattern of AT5G51890 promoter fused b-glucuronidase (GUS) gene expressed in vessel elements, which is one of cell types from xylem tissues coated with lignin in cell wall. Therefore, peroxidase AT5G51890 is hypothesized to be secreted out into cell wall. To determine function and cellular location of peroxidases, three genes constructs were developed by two rounds of PCR and transferred into Arabidopsis plant nuclear genomes. Endogenous SP:51890:YFP:RFVN construct contained DNA sequence of yellow fluorescent protein (YFP). Construct SP:51890:mCherry:AFVY contained mCherry DNA sequence and vacuolar sorting sequence. Construct (Delta)SP:51890:mCherry:RFVN had removal of signal peptide sequence and mCherry DNA sequence. Microscopic images showed that all peroxidase targeted variants were all found in protoxylem tissues of apical root region. Targeted variants of peroxidase 51890 designed to exploit lack of cytoplasm in dead protoxylem cells at maturity, required longer term experiments to confirm the subcellular location of peroxidase targeted variants. Initial experiment using plants containing peroxidase targeted variants to the cell wall, vacuole and cytoplasm respectively showed no significant change on cell elongation and protoxylem formation.
2020-01-02T00:00:00ZNovel antagonists of the SH2 domain of GRB2 decrease chronic myeloid leukemia (CML) cell proliferation via the JAK/STAT pathway
http://hdl.handle.net/10211.3/214119
Novel antagonists of the SH2 domain of GRB2 decrease chronic myeloid leukemia (CML) cell proliferation via the JAK/STAT pathway
Aguiar, Stephanie
Chronic myeloid leukemia (CML) is a disease that affects the normal growth of myeloid cells, which are blood cells that protect the body against foreign invaders in the blood and bone marrow. In humans, 95% of CML cases are caused by a chromosomal translocation that inappropriately links the breakpoint cluster region (BCR) to Abelson murine leukemia viral oncogene-1 (ABL1), forming a mutant oncogene called BCR-ABL1 . A protein that physically interacts with BCR-ABL1 is growth receptor bound protein-2 (GRB2), an intracellular adaptor protein involved in cell growth and differentiation. Specifically, BCR-ABL1 binds to a region of GRB2 known as the SRC homology-2 (SH2) domain. This interaction transforms hematopoietic stem and progenitor cells, initiating leukemic transformation. The current frontline therapy to treat CML is a tyrosine kinase inhibitor, imatinib. Some patients have developed a resistance to imatinib, and thus the demand for additional anticancer drugs are needed. To prevent growth of CML cells, Dr. Arpin and her students of the CSU Chemistry and Biochemistry department created two novel SH2 antagonists (NHD2-15 and NHD2-114) and we tested their ability to prevent cell proliferation in the human BCR-ABL1 + K562 myelogenous leukemia cell line. The most significant growth reduction was observed 72 hours after the addition of 30 μM of NHD2 - 15.
Furthermore, adding drugs combinatorially (60 μM NHD2-15, 30 μM NHD2-114, and 1 μM imatinib) to K562 cells showed over 2-fold growth reduction than with imatinib alone. To assess if these compounds are toxic to living organisms, we added the two compounds individually to the water of healthy adult zebrafish, and found that NHD2-15 was non-toxic. After using an enzyme-linked immunosorbent assay (ELISA) we also found that these two novel drugs exhibited prominent binding affinities to GRB2; NHD2-15 with K d = 119 ± 2 μM, and NHD2 - 114 with K d = 440 ± 7 μM (Lewis et al., in revision, 2019). Western blots were performed to determine the pathway these novel antagonists in fluence, and to ultimately indicate if these drugs stop cancerous cell proliferation via the Janus kinase signal transducer and activators of transcription (JAK/STAT) pathway, as well as the mitogen-activated protein kinase and phosphoinositide 3-kinase (M APK/PI3K) pathway. Results of western blotting indicated that the combinatorial treatments of both novel drugs reduces expression of proteins involved in both the JAK/STAT and MAPK/PI3K pathways, suggesting these compounds inhibit different target proteins within BCR-ABL+ cells to decrease leukemic cell proliferation. This research should provide an additional alternative treatment for patients who develop imatinib resistance.
2019-11-07T00:00:00ZHost selection by the walnut twig beetle, Pityophthorus juglandis, in California
http://hdl.handle.net/10211.3/213386
Host selection by the walnut twig beetle, Pityophthorus juglandis, in California
Lona, Irene
Walnut (Juglans) and wingnut (Pterocarya) trees have been declining in response to Thousand Cankers Disease (TCD). The TCD pathogen, Geosmithia morbida, is vectored by a phloeophagous bark beetle, the walnut twig beetle (Pityophthorus juglandis Blackman). To understand P. juglandis host selection, the following were investigated at two orchards in Northern California: 1) The susceptibility of two walnut species (Juglans californica and J . major) native to the western USA by comparing P. juglandis flight and landing responses to unbaited branch sections and 2) The relationship between English walnut (Juglans regia) tree health, represented by several levels of plant water stress, and P. juglandis colonization success. P. juglandis preferred to land on J. californica over J. major. With J. regia, there was no significant difference in P. juglandis activity between branches from trees in high water stress and low water stress groups (both baited with P. juglandis aggregation pheromone). No P. juglandis colonization activity was observed in unbaited branches from the negative control group (unbaited). Activity by P. juglandis was found primarily on 4 cm diameter branches. Other invasive bark and ambrosia beetles such as Hypothenemus eruditus and Xyleborinus saxeseni; and an invasive longhorned beetle, Nathrius brevipennis preferred to land on J. major over J. californica. Collections of H. eruditus and an invasive ambrosia beetle, Xyleborus affinis, in Butte County reflect the northernmost records of these species in California. No significant relationships were found in J. regia between water stress and activity by N. brevipennis and a parasitoid Gildoria sp; however, activity by N. brevipennis and Gildoria sp. was found primarily on secondary 1 cm diameter branches (twigs). In conjunction with this study, significant flight responses of N. brevipennis and X. saxeseni to ethanol were recorded in a J. regia orchard. Overall, this study demonstrated that volatile cues from Juglans may influence host selection by P. juglandis and associated insects.
2019-09-18T00:00:00ZUse of riparian woodlands by cavity-nesting birds in the Sacramento Valley, California
http://hdl.handle.net/10211.3/213249
Use of riparian woodlands by cavity-nesting birds in the Sacramento Valley, California
Cochran, Holly Jean
My study aimed to quantify nesting habitat availability for cavity-nesting birds in restored and remnant patches of riparian forest on the Sacramento River. I explored three hypotheses: 1) that older restored forests will attract more cavity-nesting birds in comparison to younger restored forests because more mature habitat features are available; 2) that the vegetation structure between remnant forests, younger restored forests, and older restored forests are distinct, owing to temporal developmental processes that differ in each subset of forest; and, 3) that the vegetation structure within each forest type affects the presence of secondary cavity- nesting birds and primary cavity-nesting birds differently because of their distinct nesting requirements. I performed vegetation surveys, cavity surveys, and bird point-count surveys to describe habitat structure and estimate bird density, cavity availability, and suitable cavity- building substrate (potential nesting substrate) in the form of snags and broken tree limbs. Surveys were conducted in each of six different aged riparian forests (remnant and 13- to 21- year old restored) in Glenn and Tehama Counties in Northern California.
In restored forests, I determined that restoration sites between the ages of 13- and 21- years old (time since initial planting) do not have significantly different habitat availability for cavity-nesting birds. Features included in this analysis were potential nesting substrate and cavity density (p=0.176 and p=0.121 respectively). When comparing remnant forests with restored forests, the potential nesting substrate and cavity density were significantly different (p=0.005 and 0.003, respectively). A multivariate analysis of the vegetation structure comparing restoration forests and remnant forests showed there are trends in vegetation features that can differentiate remnant forests and 13-year old restored forests. Through a mixed model linear regression, I determined that primary cavity nesters were more sensitive to specific habitat features than secondary cavity nesters. Tree density, snag density, and forest age were important for both groups, but secondary cavity nesters were also sensitive to the number of different tree species present and the amount of potential nesting substrate available. It may be inferred that secondary cavity nesters are more likely to be observed in remnant forests, since these forests have a wider variety of tree species and far more potential nesting substrate available than restored forests.
2019-09-12T00:00:00Z