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Biomedical subjects

S G Velleman

Publications and source records attributed to S G Velleman.

At least 19 recordsLinked to original sources
PubMed1999

Myotube morphology, and expression and distribution of collagen type I during normal and low score normal avian satellite cell myogenesis.

Myogenic satellite cells are essential for postnatal muscle growth and the regeneration of muscle in response to injury. An understanding of how the extracellular matrix affects satellite cell activity, and the temporal and spatial expression of extracellular matrix macromolecules is largely unknown. In the avian genetic muscle weakness, low score normal (LSN), satellite cell proliferation and differentiation rates are significantly lower than that observed in normal chicken satellite cells, which may be attributed to a late embryonic increase in the expression of decorin. Satellite cell-derived morphological properties, collagen type I expression, and the spatial distribution of collagen type I were investigated during normal and LSN satellite cell proliferation and differentiation. These studies showed a decrease in LSN myotube length and the number of nuclei per myotube. Collagen type I expression was similar between the LSN and normal satellite cell cultures during the course of proliferation and differentiation. However, the spatial distribution of collagen type I was altered in the LSN cultures 48 h after the initiation of fusion. The LSN cultures exhibited a premature extracellular distribution of collagen type I compared to the normal satellite cells.

Animals↗
PubMed1999

Analysis of genetic polymorphisms in the major histocompatibility complex of Japanese quail.

The restriction fragment length polymorphisms (RFLP) of the Japanese quail MHC were assayed in seven lines using PvuII-digested DNA and a chicken Class II probe. The lines of Japanese quail surveyed included a randombred control population (R1) and sublines of R1 divergently selected for 4-wk body weight (HW and LW lines) or plasma yolk precursor as measured by total plasma phosphorus (TPP) (HP and LP lines). In addition, two sublines (HW-HP and HW-LP) of the HW line were included in the analysis. Males of both sublines were selected for increased 4-wk body weight whereas the females were selected for increased (HW-HP) or decreased (HW-LP) TPP. The number of birds surveyed per line ranged from 13 to 16. The chicken probe used produced discernible bands or fragments using Southern blot analysis. There were 16 different RFLP patterns as well as 7 different heterozygote patterns detected in the various Japanese quail lines. The band or fragment number of each pattern varied from 7 to 15. A total of 28 different bands or fragments were seen in the RFLP patterns and only 2 bands or fragments were common to all 16 patterns. The distribution of the RFLP patterns differed greatly among the Japanese quail lines. The R1 line differed in frequency of the patterns from all of the selected lines. The divergently selected lines (HW vs LW; HP vs LP; and HW-HP vs HW-LP) also differed in the frequency of the various RFLP patterns. In the comparison of the HW and LW lines, there were no RFLP patterns in common between the two lines. The results of the present study indicated that the Japanese quail MHC Class II genes were highly polymorphic.

Animals↗
PubMed1999

The role of the extracellular matrix in skeletal muscle development.

Skeletal muscle fibers are surrounded by an extracellular matrix. The extracellular matrix is composed of glycoproteins, collagen, and proteoglycans. Proteoglycans have been suggested to play an important functional role in tissue differentiation; however, an understanding of how the extracellular matrix affects skeletal muscle development and function is largely unknown. Proteoglycans can regulate collagen fibrillogenesis, inhibit cell growth, and modulate the response to growth factors. Our studies have focused on the proteoglycan decorin, which interacts with transforming growth factor-beta and regulates collagen fibrillogenesis and cellular growth properties in the avian genetic muscle weakness Low Score Normal. Low Score Normal pectoral muscle development is characterized by a late embryonic increase in the expression of decorin followed by a subsequent increase in collagen crosslinking and modified collagen fibril organization. This paper reviews the interaction of extracellular matrix molecules, cell-extracellular matrix interactions, and modulation of growth factor activity. How proteoglycans may interface with each of these key events during skeletal muscle myogenesis is discussed.

Animals↗
PubMed1998

Changes in distribution of glycosaminoglycans during the progression of cholesterol induced atherosclerosis in Japanese quail.

The temporal and spatial distribution and relative concentration of the proteoglycan glycosaminoglycan component were studied during the progression of atherosclerosis in the systemic arteries of Japanese quail selected for cholesterol induced atherosclerosis (CIA). The CIA quail were placed on either control or 0.5% added cholesterol diets at 3 months of age. The major systemic arteries (dorsal aorta, right and left brachiocephalic) were collected at 1- or 2-week intervals over the 10-week period of cholesterol feeding. In the cholesterol fed quail, alcian blue staining of the dorsal aorta showed elevations of glycosaminoglycans in regions of the artery with atherosclerotic plaque, beginning at the 6-week time point. By biochemical analysis, increases in glycosaminoglycan relative concentration was detected at the 10-week time point. In addition to the change in glycosaminoglycan relative concentration and distribution, the cholesterol fed animals also formed foam cells characteristic of atherosclerotic plaques. Therefore, the conclusion reached was that the CIA line of Japanese quail is a valid animal model for the study of alterations in proteoglycan metabolism in atherosclerotic plaques induced by hypercholesterolemia.

Animals↗
PubMed1998

Measurement of genetic variation within and between Japanese quail lines using DNA fingerprinting.

The objective of the present experiment was to study genetic variation within and among well-defined Japanese quail lines by DNA fingerprinting. The Japanese quail lines included a randombred control line (R1) and lines developed from R1 by divergent selection over 30 generations for 4-wk BW (HW, LW) and total plasma phosphorus (TPP) (HP, LP), a measure of yolk precursor in the blood. In addition, two sublines (HW-HP, HW-LP) of HW, developed in the ninth generation, were included in the analysis. Males of the sublines were selected for increased 4-wk BW whereas females were selected for increased (HW-HP) or decreased (HW-LP) TPP. Sixteen individual DNA samples per line were digested with HaeIII restriction enzyme and hybridized with Jeffreys' 33.6 probe. The DNA fingerprints were analyzed with computer programs designed to measure band sharing (BS). Within lines, BS ranged from 0.384 to 0.525. The BS within the R1 line was less than that of all selected lines, except for the HP and LP lines, indicating that, in general, selection had increased genetic homogeneity within the selected lines. Between lines, BS was less than within lines and the R1 line had the highest average level of BS (0.278) with the other lines. The BS between lines for the selected lines ranged from 0.230 to 0.308 with an average of 0.265. In the comparison of the R1 line with the selected lines, it appeared that selection for increased TPP or decreased BW may have influenced BS levels. The relationships of the HW line with its sublines (HW-HP and HW-LP) were not accurately predicted by the DNA fingerprinting technique used. All lines were separated, as indicated by the genetic distance between lines.

Animals↗
PubMed1998

Transforming growth factor-beta gene expression in avian Low Score Normal pectoral muscle.

The avian Low Score Normal (LSN) genetic muscle weakness is phenotypically characterized by a reduction in the ability of birds to right themselves from a supine position. In previous studies, LSN birds exhibited elevated levels of decorin transcript and protein at embryonic Day 20 and a large increase in collagen crosslinking at 6 wk posthatch. Transforming growth factor-beta (TGF-beta) expression has been reported to control decorin expression. Steady state levels of TGF-beta1 and TGF-beta2 transcripts were determined in ovo and posthatch in order to initiate an investigation of the mechanism underlying decorin expression. On embryonic Day 20 through 1 wk posthatch, TGF-beta2 transcript levels were elevated, whereas an increase in TGF-beta1 was only noted at 1 d posthatch. These data suggest that the increase in decorin expression may be associated with a modification in a TGF-beta signal transduction pathway.

Aging↗
PubMed1998

Genetic diversity of commercial turkey primary breeding lines as estimated by DNA fingerprinting.

The genetic diversity of primary breeding sire and dam lines from the three largest turkey breeders was estimated by band sharing of DNA fingerprints and by genetic distance estimated from band sharing. For comparison, experimental lines selected for increased egg production (E line) or increased 16-wk body weight (F line) were also included in the analysis. Eighteen individual DNA samples per line were digested with HaeIII restriction enzyme and hybridized with Jeffreys' 33.6 probe. The DNA fingerprints were analyzed with computer programs designed to measure band sharing. Within commercial lines, band sharing ranged from 0.370 to 0.508 and was greater in commercial sire lines (average = 0.475) than in commercial dam lines (average = 0.393), indicating that accumulated inbreeding was greater in the sire lines. Band sharing in the F and E lines was 0.479 and 0.522, respectively. The average band sharing among lines was higher for primary breeding sire lines (average = 0.267) than for primary breeding dam lines (0.207), suggesting more genetic diversity in the dam lines. Genetic distance estimated from band sharing was greater among commercial dam lines than commercial sire lines. Based on band sharing between lines and genetic distance estimates, it appears that the experimental E and F lines contain genetic variation not found in the commercial lines. The results of the present study, along with data published in the literature, suggest that commercial primary breeding turkey lines are as diverse, if not more diverse, than similar commercial chicken lines.

Animals↗
PubMed1997

Alterations in sarcomere structure, collagen organization, mitochondrial activity, and protein metabolism in the avian low score normal muscle weakness.

Skeletal muscle fibers are surrounded by an extracellular matrix. The extracellular matrix is composed of glycoproteins, collagen, and proteoglycans. Proteoglycans have been suggested to play an important functional role in tissue differentiation. However, an understanding of how the extracellular matrix affects skeletal muscle development and function is largely unknown. In the avian genetic muscle weakness, low score normal (LSN), a late embryonic increase in the expression of decorin is followed by a subsequent increase in collagen crosslinking. The sarcomere organization, collagen fibril diameter and organization were investigated using transmission electron microscopy. Measurements were made at 20 days of embryonic development and 6 weeks posthatch. These studies showed changes in sarcomere organization and deterioration of muscle fibril structure in the LSN pectoral muscle. In vitro satellite cell cultures were developed and assayed for mitochondrial activity, and protein synthesis and degradation. In these analyses, mitochondrial activity from LSN satellite cells was significantly higher than those from normal pectoral muscle satellite cells. Protein synthesis rates between the normal and LSN satellite cell-derived myotubes were similar, but protein degradation rates were higher in the LSN cultures. Based on the reported functions of decorin as a regulator of cell proliferation and collagen fibril organization, it is possible that the late embryonic increase in decorin may be influencing the alterations in LSN sarcomere and collagen organization.

Animals↗
PubMed1997

Identification of decorin and chondroitin sulfate proteoglycans in turkey skeletal muscle.

Turkey pectoral muscles were examined at 15 through 25 d of embryonic age in order to delineate the developmental pattern of proteoglycan expression during skeletal muscle development. Glycosaminoglycan concentration, decorin, and muscle chondroitin sulfate proteoglycan (M-CSPG) levels were measured at each developmental age. Glycosaminoglycan levels rose during the developmental period studied, whereas decorin and M-CSPG levels were initially high at Day 15 and then decreased. The results from this study demonstrate the presence of both decorin and M-CSPG during turkey skeletal muscle development.

Animals↗
PubMed1997

Decorin and collagen type I gene expression in avian low score normal pectoral muscle.

The avian Low Score Normal (LSN) genetic muscle weakness is phenotypically characterized by a reduction in the ability of the birds to right themselves from a supine position. Compared to normal skeletal muscle, LSN muscle has normal myosin isoform switching and cell-cell recognition, elevated glycosaminoglycan and decorin levels at embryonic Day 20, and a large increase in collagen crosslinking at 6 wk posthatch. To begin to determine the biological mechanism involved in the elevated decorin protein concentration at embryonic Day 20, the steady-state levels of transcripts encoding both decorin and collagen Type I at embryonic Days 14, 19, and 20, and at 1 d and 6 wk posthatch were measured. On embryonic Day 20, collagen Type I transcripts were not different from the control but there was a significant elevation in decorin transcript levels. At 1 d and 6 wk posthatch, transcript levels of decorin and collagen Type I were not different between LSN and controls. The change in decorin transcript steady-state levels is limited to late embryonic development and suggests an alteration in a signal transduction pathway regulating decorin transcription.

Analysis of Variance↗
PubMed1997

Characterization of satellite cells derived from chickens with the low score normal (LSN) muscle weakness.

Myogenic satellite cell clones were established from the pectoralis major muscle of chickens with the low score normal (LSN) muscle weakness and controls. The percentage of cells which attached to substrata and began to proliferate was higher for the control line than the LSN line (55% vs 30%). Furthermore, of those clones which initiated growth, 63% of the control cells and only 32% of the LSN cells proliferated to confluence in 25 cm2 tissue culture flasks. Proliferation rates were significantly lower with LSN satellite cells than with controls (p < 0.05). LSN satellite cells were less responsive to the mitogenic effects of chicken serum (p < 0.05) and differentiation rates were lower compared with controls (p < 0.05). There was a greater (p < 0.05) number of insulin-like growth factor receptors on LSN satellite cells compared with controls. The IGF receptor binding affinities (Kds) between the two cell lines were similar (p > 0.05). The results suggest that a defect in satellite cell physiology may contribute to the skeletal muscle weakness seen in the LSN line.

Animals↗
PubMed1996

Extrinsic regulation of domestic animal-derived satellite cells.

Satellite cells are the postnatal myogenic cells, as they provide myonuclei to support skeletal muscle hypertrophy and are principal cells responsible for myofiber repair and regeneration. Even though research with satellite cells from meat animals is new, considerable data exist to suggest that these cells are regulated through both intrinsic and extrinsic mechanisms. This review covers the present status of the extrinsic factors known or postulated to modulate meat animal satellite cell growth and development.

Animals↗
PubMed1996

Partial characterization of ovine skeletal muscle proteoglycans and collagen.

Ovine longissimus dorsi and biceps femoris muscles were analyzed for proteoglycan content, collagen and lysine aldehyde-derived collagen crosslinking concentrations at 2-4 days, six-month-old, and six-year-old stages of development. Tissue extracted proteoglycan molecular sieve distribution on a Sephacryl S-200HR column revealed two proteoglycan populations with estimated relative molecular weight ranges of 200,000 to 250,000 daltons and 23,000 to 70,000 daltons. The molecular sieve distribution was similar between the two muscles within a developmental age, but changed as a function of developmental age. Primary culture from both the longissimus dorsi and biceps femoris muscle liberated proteoglycans into the culture medium. In contrast to the tissue extracted proteoglycans, at the six-year-old stage of development, culture medium liberated proteoglycan Sephacryl S-200HR molecular sieve distribution differed between the two muscles. In both the tissue extracted and medium liberated proteoglycans at all developmental stages, nitrous acid deamination demonstrated the presence of heparan sulfate. Immunoblot analysis of the tissue extracted proteoglycans indicated the presence of decorin at each developmental stage. Longissimus dorsi and biceps femoris collagen concentrations (5.13 +/- 0.9 vs. 5.53 +/- 1.5%, respectively) and crosslink concentrations (0.07 +/- 0.01 moles HP/mole collagen) were initially similar between the two muscles; however, by six-months the muscles differed in both collagen concentration (1.72 +/- 0.5 and 2.53 +/- 0.7%, respectively) and crosslinking (0.24 +/- 0.02 and 0.27 +/- 0.03 moles HP/mole collagen, respectively). At six years of age, both the longissimus dorsi and biceps femoris exhibited slightly elevated collagen concentrations (2.49 and 3.05%, respectively) while crosslinking values were decreased relative to values at six-months of age (0.11 +/- 0.01 and 0.18 +/- 0.01 moles HP/mole of collagen, respectively). The results from this study indicate that skeletal muscle proteoglycans and collagen show developmental changes, which suggests that they are subject to developmental regulation.

Animals↗
PubMed1996

The avian low score normal muscle weakness alters decorin expression and collagen crosslinking.

Extracellular matrix development of chicken pectoral muscle was examined in the Low Score Normal (LSN) genetic muscle weakness and compared to both normal and avian muscular dystrophy (MD). At 20 days of embryonic development significant elevations were noted in LSN total glycosaminoglycan concentration and decorin, while at 14 days, LSN glycosaminoglycan and decorin levels were indistinguishable from the controls. Levels of a large skeletal muscle chondroitin sulfate proteoglycan (M-CSPG) appear to be unaffected. Morphologically, at 20 days, the extracellular matrix space between muscle fibers increased to a level characteristic to that observed in avian muscular dystrophy. At six weeks posthatch a marked increase in LSN collagen crosslinking relative to MD or control tissues was observed, while collagen concentration was not altered. By one year posthatch LSN collagen crosslink levels did not significantly differ from normal tissue. These data support the concept that the LSN muscle weakness is associated with changes in both proteoglycan and collagen characteristics.

Animals↗
PubMed1992

The cartilage proteoglycan deficient mutation, nanomelia, contains a DNA polymorphism in the proteoglycan core protein gene that is genetically linked to the nanomelia phenotype.

The avian mutation, nanomelia (nm), is an autosomal recessive embryonic lethal. Homozygous embryos show hypoplasia of the limbs and a parrot-like beak. Biochemical studies have associated this phenotype with the absence of the major cartilage specific proteoglycan core protein (Argraves et al., 1981). Stirpe et al. (1987) demonstrated a reduction in core protein transcripts in nanomelic embryos. Southern analyses did not detect a rearrangement of the core protein gene or a restriction fragment length polymorphism (RFLP) in the core protein gene linked to the nanomelia mutation. These data suggest that the genetic lesion associated with the nanomelia mutation is either a subtle alteration in the core protein gene affecting the biosynthesis of core protein transcript or a defect in a regulatory gene that produces a trans-acting factor requisite for the proper expression of the core protein gene. To distinguish between these two alternative molecular mechanisms for the nanomelia mutation, experiments were conducted to demonstrate genetic linkage or non-linkage of the core protein gene to the nanomelia mutation. Using denaturing gradient gel electrophoresis (DGGE) technology, a DNA polymorphism has been identified at the 3' end of the core protein gene. The polymorphism defines two alleles, one allele is associated with the normal core protein gene, while the other allele always segregates with the nanomelia mutation. These results suggest that the identified DNA polymorphism in the core protein gene is genetically linked to the inheritance of the nanomelic phenotype and the nanomelia mutation contains a lesion in the core protein gene.

Aggrecans↗