Universiẗat, Diss., 2004--Köln.

University, Diss., 2004--Köln.

The aim of this study was to determine the specific interactions among clock gene alleles in Drosophila melanogaster and their effect on the function of the circadian clock. The second part of this study deals with the expression pattern (both temporal and spatial) of two core clock factors known from Drosophila, period and timeless, in the central nervous system of the red flour beetle, Tribolium castaneum.

No description available.

No description available.

No description available.

Universiẗat, Diss., 2003--Köln.

Master of Science / Biochemistry and Molecular Biophysics Interdepartmental Program / Gerald R. Reeck / Armet has been found in mammalian systems to be a bi-functional protein that is secreted extracellularly and is also found in the endoplasmic reticulum. It has been shown to be a neurotrophic factor and also a member of the unfolded protein response. Transcript knockdown of Armet via RNA interference in late instar larvae of Tribolium castaneum produces a fatal phenotype during eclosion from pupa to adult. Initial observations of pupae cuticle indicate disorganization of cuticles in insects with the Armet transcript knocked down. Here I expand studies on the effects of dsArmet RNA injection; both in a wild type strain and a fluorescent strain of Tribolium, and discuss possible mechanisms for the fatal phenotype.

No description available.

Vertebrates, annelids, and arthropods have evolved to form their body plans via segmentation. The question is whether this process stems from a common, segmented ancestor or if segmentation in these three phyla evolved from a series of independent events. To determine which of these theories is true, we look to determining whether these phyla share any pathways in the development of their segments. The Notch signaling pathway is a well-known pathway that vertebrates utilize for segmentation. Without it, somitogenesis does not occur properly as the segmentation oscillator is not functioning. Drosophila does not use this pathway for segmentation, but several other arthropods have recently been found to utilize it in the formation and maintenance of their segments (17-24). There has been debate as to whether Tribolium castaneum also uses the Notch pathway during segmentation as previous knockdowns of the Notch and Delta genes have led to a loss of segments and appendages/mouthparts (25-27). To determine this pathway’s involvement in Tribolium segmentation, I knocked down the Delta gene via eRNAi and attempted to determine Notch and Delta expression patterns via in situ hybridization. My results were inconclusive for determining the role of the Notch signaling pathway in segmentation. In the Delta dsRNA embryos, a loss of the labial segment, head and mouthpart defects, a loss of leg formation, and midline defects were seen. Future experiments need to be performed to determine whether an overexpression of mesoderm, ectoderm, or both is the cause of the defective ventral midline and whether this could lead to a loss of segments later in development. Overall, I can conclude that the Notch signaling pathway plays a role in mouthpart/leg development, the labial segment, and what I believe to be lateral inhibition between mesoderm and ectoderm determination.