Brief Summary of Minutes of Annual Meeting

The annual meeting, chaired by Dave Gerrard, was held at Purdue University, West Lafayette, IN. Alan Grant, Animal Sciences Department Head, provided a welcome to Purdue University. Larry Miller described the reorganization of CSREES, the forthcoming meeting of the International Congress of Meat Science and Technology at Baltimore, MD in 2005, and a history of meat science research he has published. Dr. Debora Hamernik will replace Larry as CSREES liaison to NC-131. The committee thanked Larry for his years of participation and service to NC-131. Elton Aberle discussed the current federal budget deliberations for FY03. He indicated that Hawaii, Idaho, and Oregon were new participants in NC-131. John Killefer has resigned his position at West Virginia to accept a position at the University of Illinois and Illinois will be joining the project. He reminded the committee that mid-term reviews of NC-131 by the Administrative Advisor and the NCA-6 committee would be submitted before February, 2003. The committee should plan to discuss revision of the project at its meeting in October, 2003 and plan to have a revision completed by December 1, 2004, if it wishes to continue beyond September 30, 2005. Katherine Byrne has left Washington State University and will no longer participate in this project. Matt Doumit, who served as secretary for 2001-02, was elected chair and Marion Greaser was elected secretary for 2002-03.

The full annual report and minutes are available on the NC-131 web page,
http://ars.sdstate.edu/nc131/main.htm

Progress reports were presented by all institutions in attendance; in addition, written reports were distributed from the Pennsylvania, South Dakota and Utah stations, whose representatives were not able to attend the meeting. Project participants continue to aggressively acquire information about the fundamental biological process that regulate muscle growth and development of meat-producing animals.

Substantial progress was made to better understand the extracellular signals, intracellular signal transduction pathways, and nuclear mechanisms that govern myoblast and satellite cell activity. These include signals that stimulate satellite cells to enter the cell cycle and the roles of insulin-like growth factors (IGFs), IGF binding proteins, and fibroblast growth factors in satellite cell and myoblast proliferation. Anabolic steroid effects on muscle growth appear to be mediated through the IGF pathway. Significant progress was also made to document differences in extracellular matrix proteins in skeletal muscles of rapid and slow growing genetic strains. Investigations of the intracellular roles of the calpains in living cells were continued. Inhibition of calpain activity prevents formation of integrin clusters and the ability of cells in culture to spread, form focal adhesions, actin filament networks, and stress fibers.

Several stations continue to investigate gene expression and control in myogenic cells. Down regulation of important muscle genes was demonstrated in myoblasts expressing elevated levels of Raf and MAPK; the mechanism of down regulation is being investigated. The gene JAK2 is markedly elevated during work induced hypertrophy. When this gene is blocked with a specific inhibitor, however, myoblast differentiation and myotube maturation were prevented, demonstrating the importance of this gene in differentiation of skeletal muscle. Investigation continued of the biochemistry and molecular biology of the myosin heavy chain multi-gene family. It was demonstrated that a muscle fiber contains a series of nuclear domains, each responding to distinct localized signaling mechanisms that may result in differential gene expression within a single fiber. For example, the tapered ends of fibers contain neonatal myosin heavy chain isoform in addition to the adult isoform found throughout the length of the fiber. It appears that during development, neonatal myosin is initially repressed near the nerve motor endplate and that trophic factors emanating from the vicinity of the motor endplate represent a potential localized signaling pathway that differentially modulates myosin heavy chain gene expression in nuclear domains along the length of the muscle fiber. There are significant increases in the size of nuclear domains within a muscle fiber as it transforms from neonatal to adult type.

Project participants continue to investigate how calpain is regulated in living cells. Significant progress was made in purification of m- and 5-calpains and calpastatins on immunoaffinity columns and their subsequent quantification in various muscles and tissues. Cell lines have been developed in which the activities of m- and 5-calpains may be regulated and their functions in muscle wasting identified. These cell lines are being used to delineate the roles of calpains in muscle protein degradation. The roles of two novel intermediate filament proteins, synemin and paranemin, in developing skeletal are being investigated. Paranemin is expressed first and localized in intermediate filaments and then co-localized with synemin and desmin throughout myofibrillogenesis in myotubes. Thus, paranemin and synemin may play a role in integrating intermediate filaments into the cytoskeleton during myofibrillogenesis. Finally, atomic force microscopy is being used to characterize single molecule force-extension curves of titin molecules. Titin contains unique repeated amino acid sequences that are responsible for physiological levels of passive force in moderately to highly stretched muscle fibers. These techniques are demonstrating differences among titin molecules from different species and types of muscle that account for differing levels of passive force.

Committee members continue to be highly collaborative through the sharing of techniques, culture models, antibodies, molecular probes, and expertise. They use and frequently improve upon current methods in cell and molecular biology, genomics, and proteomics to address fundamental questions. They are highly productive as indicated by the large number of publications, including a significant number of joint publications among institutions.


A full description of project accomplishments may be found on the NC-131 web page, http://ars.sdstate.edu/nc131/main.htm.

Committee members published 42 full-length papers in refereed journals during the period of this report; 17 other full-length papers were accepted for publication. In addition, they published 40 abstracts of papers presented at professional meetings and 15 non-referred publications as proceedings and book chapters.

The full listing of publications can be found in the NC-131 annual report for 2001-02, which is available on the NC-131 web page,
http://ars.sdstate.edu/nc131/main.htm .