Secretions of the exocrine pancreas contain digestive enzymes integral to the digestive process. The Pacific spiny dogfish (Squalus suckleyi) has a discrete pancreas, divided into two lobes termed the dorsal and ventral lobes. These lobes drain into the anterior intestine via a common duct to enable digestion.
View Article and Find Full Text PDFEnvironmental temperature during early life may have prolonged effects on growth and fatty acid metabolism, which could strongly influence overwintering survival in the first year of life for temperate-zone fish. In the present study, we examined how temperature during early life history might influence growth performance and fatty acid metabolism in age-0 Lake Sturgeon (Acipenser fulvescens) when exposed to cold temperatures at later stages. Fish were initially at 16 °C and subsequently held at 16 °C or 20 °C for 60 days beginning at 34 days post fertilization (dpf).
View Article and Find Full Text PDFActivation of the platelet-derived growth factor (PDGF)-receptors is critically involved into various stromal cell functions including recruitment of stromal cells and vascular endothelial growth factor (VEGF) induction in tumor and perivascular cells. To evaluate the effects of combined PDGFRalpha and -beta inhibition in a non-small cell lung cancer model, we stably transfected A549 lung cancer cells with the PDGF-A mutant PDGF-0. PDGF-0 has been generated by substituting amino acids in the binding region of PDGF-A with the corresponding VEGF-A region, leading to a decreased receptor-binding affinity and activation.
View Article and Find Full Text PDFAngiogenesis is defined as formation of new blood vessels from the preexisting vasculature, a process which is essential for malignant tumor growth. While this has been accepted for solid forms of cancer there is now emerging evidence that progression of hematological malignancies also requires the induction of new blood vessels. Vascular endothelial growth factor (VEGF) is known to be an essential regulator of physiological and pathological angiogenesis.
View Article and Find Full Text PDFThe most highly expressed protein in the productive life cycle of human papillomaviruses (HPVs) is E1--E4, but its function is not well understood. To investigate the role of E1--E4, we undertook a genetic analysis in the context of the complete HPV type 31 (HPV31) genome. A mutant HPV31 genome (E4M9) was constructed that contained a stop codon in the E4 open reading frame at amino acid 9 and was silent in the overlapping E2 coding sequence.
View Article and Find Full Text PDFThe life cycle of human papillomaviruses (HPVs) has been difficult to study in tissue culture owing to its dependence on epithelial differentiation. In this chapter several methods are described to imitate the important steps in the HPV life cycle. Normal human keratinocytes (NHKs) harvested from neonatal foreskins were transfected with HPV type 31 genomes in order to generate stable cell lines containing episomal copies of HPV genomes.
View Article and Find Full Text PDFHuman papillomavirus (HPV) infections play a crucial role in the pathogenesis of cervical neoplasia. Insights into the mechanisms by which HPV infection can, in a small numbers of cases, result in malignancy, comes from the observation that three proteins encoded by high-risk genital HPVs, E6, E7 and to a lesser extent E5, target factors that control the cell cycle and proliferation. These interactions result in abrogation of cell cycle control, chromosomal alterations, telomerase activation, and eventual cell immortalization.
View Article and Find Full Text PDFIntracisternal A-type particles (IAP) are defective endogenous retroviruses that accumulate in the endoplasmic reticulum (ER) of rodent cells. The enveloped particles are produced by assembly and budding of IAP Gag polyproteins at the ER membrane. In this study, we analyzed the specific ER transport of the Gag polyprotein of the IAP element MIA14.
View Article and Find Full Text PDFThe function of the E5 protein of human papillomaviruses (HPV) is not well characterized, and controversies exist about its role in the viral life cycle. To determine the function of E5 within the life cycle of HPV type 31 (HPV31) we first constructed HPV31 mutant genomes that contained an altered AUG initiation codon or stop codons in E5. Cell lines were established which harbored transfected wild-type or E5 mutant HPV31 genomes.
View Article and Find Full Text PDFMurine intracisternal A-type particles (IAPs) are endogenous retroviruses showing sequence homologies to B/D- and avian C-type retroviruses and a gene expression strategy similar to that of D-type retroviruses. These viruses form immature particles in the endoplasmic reticulum and do not release extracellular virions, but are competent for retrotransposition within the virus-producing cell. It had been assumed that lack of polyprotein processing and maturation is due to a defect in the viral proteinase (PR), but recent experiments have shown that polyprotein processing occurs when assembly of the mouse IAP MIA14 is artificially directed to the plasma membrane.
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