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Fibroblast growth factor 2 (FGF2) is a key regulator of muscle cell proliferation and differentiation. To address how FGF2 and fibroblast growth factor receptor 1 (FGFR1) gene expression influences skeletal muscle development and growth, pectoralis major muscle was isolated at embryonic days (ED) 14, 16, 18, 20, 22, and 24, and at 1-, 8-, 12-, and 16-week posthatch from a turkey line (F) selected only for increased 16-week body weight and its genetic control line (RBC2). The mRNA levels of FGF2 and FGFR1 were measured by semi-quantitative reverse transcription polymerase chain reaction. Compared to the RBC2 line males, the F line males had higher FGF2 mRNA levels at ED 14 and 16, and higher FGFR1 mRNA levels at ED 18, but down-regulated FGF2 and FGFR1 gene expression at ED 22. Although no FGF2 mRNA was detected in posthatch muscle tissue, the F line turkeys had more FGFR1 gene expression at 8-, 12-, and 16-week posthatch than the RBC2 line turkeys. During myogenic satellite cell proliferation, the F line cells had higher FGF2 and FGFR1 mRNA levels than the RBC2 line cells. The satellite cell responsiveness to FGF2 treatment was evaluated by the ability of the cells to proliferate. The male satellite cells were more responsive to FGF2 stimulation than the female cells in both lines. These results suggest that the F line turkeys have increased FGF2 signaling that may affect muscle cell proliferation and differentiation, which may also lead to an enhancement in muscle development and growth rate.

Damage to the turkey pectoralis major muscle was studied in a randombred control line (RBC2), a subline (F) from the RBC2 line selected long-term for increased 16-wk BW only, and a commercial sire line (B) at 25 d of incubation and at 1, 4, 8, 16, and 20 wk posthatch. Pectoralis major muscle samples were obtained from three females and three males from each line in a manner to avoid contraction. After being fixed and sectioned, the muscle samples were stained with hematoxylin and eosin to view muscle fiber and muscle fiber bundle morphology. Beginning at 8 wk posthatch, differences in muscle fiber morphology were observed among the different lines. The RBC2 line throughout the duration of the study maintained well-organized muscle fibers and muscle fiber bundles with large capillary networks. In contrast, the growth-selected F line began to show muscle fiber degeneration at 8 wk posthatch, and limited capillary beds were observed as development proceeded. The B line had intermediate muscle morphology between the RBC2 and F lines, but by 20 wk posthatch significant muscle fiber degeneration was present with limited capillary supply. The degenerative muscle fiber changes were predominant in the growth-selected F-line, suggesting that growth selection for just BW may be associated with posthatch muscle damage.

Several transcription factors are involved in regulating lipid metabolism in various animal tissues. Peroxisome proliferator-activated receptor (PPAR) gamma and PPARalpha regulate lipogenesis and fatty acid oxidation. Gene fragments for PPARgamma, PPARalpha, and acyl-coenzyme A oxidase (ACO) have been cloned in turkeys, and the sequences of these genes were highly homologous to those of chickens, pigs, and humans. Data showed that turkey PPARgamma and PPARalpha were highly homologous (>97%) with that of the chicken, indicating the genetic relationship between those two species was close. The tissue distribution and genetic effect on mRNA concentrations of PPARgamma, PPARalpha, and ACO in two genetic populations of turkeys [randombred control (RBC2) and growth selected (F line)] was determined. The PPARgamma mRNA was highly expressed in adipose tissue in both populations, but there was no difference between the two populations. The PPARalpha mRNA concentration was high in the liver with less expression in adipose tissue and skeletal muscle. The PPARalpha mRNA concentration was similar between the two genetic populations. The ACO mRNA was expressed in adipose tissue, skeletal muscle, and liver with no difference between the genetic populations. The data suggest that both turkey liver and adipose tissue have considerable capability for fatty acid oxidation and synthesis. Long-term selection for increased 16-wk BW in the F line had no effect on the expression of PPARgamma, PPARalpha, and ACO.

Heparan sulfate proteoglycans (HSPG) are a group of extracellular matrix molecules that link skeletal muscle cells to their extrinsic environment. To investigate if HSPG expression is affected by muscle growth and gender, a turkey line (F) selected for increased 16-wk BW and its unselected random-bred control line, RBC2, were used in the present study. Heparan sulfate (HS) and HSPG levels were measured in embryonic and posthatch pectoralis major muscle. HS levels plateaued at embryonic day (ED) 16 in both lines. A significant decrease of HS occurred at ED 18 in F males and females, and at ED 20 and 22 in the RBC2 males and females, respectively. Embryonic HSPG levels peaked at ED 18, and were significantly higher from ED 14 through 18 in F males and females compared with those of the RBC2 line. Male pectoralis major muscle had more HSPG at early embryonic stages than female muscle in both lines. During 1 to 16 wk posthatch, F male and female pectoralis major muscle contained more HSPG than the RBC2 samples, and HSPG levels in F males were higher than those of the females. Myogenic satellite cells derived from F and RBC2 male and female pectoralis major muscle were cultured to measure HSPG expression during proliferation and differentiation. No significant difference in HSPG level was found between the RBC2 and F line cells. However, in both lines, male-derived satellite cells had more HSPG than the female cells during proliferation and differentiation. These data show that HS and HSPG expression are affected by muscle growth properties and sex.

Muscle development at 20 and 25 d of incubation was studied in a randombred control line (RBC2), a subline (F) of RBC2 selected only for increased 16-wk BW, a commercial sire line (B), and reciprocal crosses of the F and B lines. Muscle samples from three males and three females of each genetic group were collected in such a manner to avoid contraction. After fixing, the muscles were stained with hematoxylin and eosin, measurements of muscle fiber width, muscle fiber bundle length and width, number of fibers within a 15.6 microm2 area, and extracellular matrix perimysial (PW) and endomysial (EW) width were taken with an Olympus XI 70 microscope equipped with an Olympus Magna Fire digital camera linked to Image Pro software. From each slide, 20 measurements were taken for each characteristic analyzed. In most of the muscle traits measured, additive genetic variation, as indicated by line differences, occurred when the RBC2 line was included in the comparison of pure lines. However, when only the B and F lines were compared, line differences were less frequent. In comparisons of the B and F lines and their reciprocal crosses, heterosis, as measured by contrasts of the average of the pure lines and the average of the reciprocal crosses, was an important source of variation for individual fiber measurements (negative) and extracellular space (positive) at 20 d of incubation but was less important at 25 d of incubation. No significant interactions between genetic group and sex were noted at 20 d of incubation, but such interactions were frequent at 25 d of incubation. These results suggest that muscle organizational differences between the two sexes begin to occur between these two ages and are not the same for different genetic groups.

A line (E) of turkeys selected long-term (37 generations) for increased egg production was reciprocally crossed with its randombred control population (RBC1) that served as the base population of the E line to study the influence of long-term selection on the development of nonadditive genetic variation for egg production and body weight traits. Heterosis was significant for BW at 8, 16, and 20 wk of age and at 50% production (females only). At 16 and 20 wk of age, heterosis for BW was significant only for male offspring. No heterosis was observed in the reciprocal crosses for egg production when measured for 84, 180, or 250 d. Heterosis was significant for rate of response to stimulatory lighting of 14 h light per day (days from stimulatory lighting to production of first egg). Based on data for a 250-d production period, heterosis was observed in average clutch length but not in total days lost from broodiness or the effective length of the laying period (250-d lost in periods of 5 or more consecutive d at the end of the laying period). The present results suggest that long-term selection for increased egg production and the correlated decrease in BW increased the relative nonadditive genetic variation in BW. Reciprocal effects were significant for BW at 8 and 16 wk of age, probably due to a large difference in egg weight between the E and RBC1 lines.

Developmental stability of several Japanese quail lines was measured by bilateral asymmetry. Lines included in the study were as follows: a randombred control (R1), sublines of R1 selected for increased (HW line) and decreased (LW line) 4-wk BW, and sublines of R1 selected for increased (HP line) or decreased (LP line) total plasma phosphorus (TPP; a measure of yolk precursor in the blood) at the beginning of lay. In sublines of the HW line, the males were selected for increased 4-wk BW and the females for increased (HW-HP line) or decreased (HW-LP line) TPP. The HW, LW, HP, and LP lines were in their 41st generation of selection and the HW-HP and HW-LP lines in their 31st generation of selection. The number of birds in each line and sex subgroup was 30. The adult breeders (28 to 32 wk of age) were weighed and killed, and bilateral measurements were made of shank length, width (laterally at the dew claw), and depth (perpendicular to the dew claw), face length, and pectoralis major and p. minor weights. Data on asymmetry was expressed for the right side minus the left side as signed and absolute differences. In order to correct for the correlation between trait size and asymmetry, relative asymmetry (RA) was obtained by dividing the absolute differences between sides by the average value of both sides and multiplying by 100. All lines differed in BW at 4 wk of age with the ranking HW > HW-LP > HW-HP > LP > R1 > HP > LW. Line rankings of adult breeders were similar, except the HP and LP lines did not differ from the R1 line and the order of ranking of the HW-HP and HW-LP lines was opposite that at 4 wk of age. Line differences in signed and absolute differences were significant for most bilateral traits. However, after adjustment for trait size, line differences in RA were less frequent. In general, there were few significant differences in RA for the R1 line versus the selected lines, even though inbreeding of the R1 line (19%) was less than half that of the selected lines (44 to 57%), suggesting that homozygosity did not influence developmental stability. Selection for increased or decreased BW had little influence on RA. Developmental stability tended to be higher in the lines (LP and HW-LP) selected for decreased TPP. The data indicated that bilateral asymmetry was not a good measure of developmental stability in the current study.

Cardiac decorin and Type I collagen expression and collagen fibrosis were examined in a chicken line exhibiting the low score normal (LSN) genetic muscle weakness and compared to normal cardiac muscle at 14 and 20 d of embryonic development and at 1 and 6 wk posthatch. These extracellular matrix proteins were selected due to their role in regulating tissue elasticity, which is critical for normal cardiac function. Beginning at 1 wk posthatch, relative levels of decorin were higher in the LSN cardiac muscle than in the control, indicating a time-dependent increase in decorin expression. Type I collagen levels appeared to be unaffected by the LSN condition. Morphologically, myocardial and coronary artery fibrosis did not differ between the control and LSN at all stages examined. These results are suggestive of extracellular matrix remodeling in LSN cardiac muscle that is mediated through a decorin-dependent pathway.

We examined the temporal relationship between messages (type I and type III mRNAs) for the principal fibrillar procollagens and subsequent collagen accretion, cross-linking, and decorin expression in the left ventricle (LV) postmyocardial infarction (post-MI). We sought to determine 1) what role the proteoglycan decorin plays in extracellular matrix (ECM) remodeling known to take place as a consequence of MI and 2) the extent skeletal muscle ECM is altered early post-MI. Therefore, after surgically induced production of small- to moderate-sized infarcts (approximately 20% of LV mass), extent and time course of ECM remodeling was evaluated in remaining viable LV free wall and in slow- [soleus (SOL)] and fast-twitch [gastrocnemius (GAST)] skeletal muscles. Decorin, collagen, and hydroxylysylpyridinium cross-link concentrations and alpha1(I) (type I) and alpha1(III) (type III) procollagen mRNAs were measured in LVs from noninfarcted controls and at 72 h, 1, 2, 5, and 13 wk post-MI. These same data were collected in SOL and GAST muscles at all time points except 13 wk. Type I procollagen mRNA increased at both 72-h and 1-wk time points in LVs. Type III procollagen mRNA was elevated at 1 wk, returning to baseline by 2 wk post-MI. Collagen concentration was significantly increased by 1 wk, more than doubled by 5 wk, and was elevated 129% by 13 wk in the remaining viable LV. LV decorin expression was unaltered at early time points, but increased 38% at 5 wk post-MI and doubled by 13 wk post-MI. In skeletal muscle, procollagen mRNAs were transiently altered in SOL and GAST muscles without any demonstrable effect on the measured ECM parameters. This study reports, for the first time, the upregulation time course of decorin and its relationship to increased HP cross-linking and accumulation of collagen in viable myocardium post-MI.

The abnormal muscle condition termed low score normal (LSN) was first detected in an outcross of chickens with hereditary muscular dystrophy (MD) to a commercial White Leghorn stock. At 2 to 3 mo of age, normal birds can right themselves between 15 and 20 times (exhaustion score) when placed on their back on a flat surface, whereas birds with MD cannot right themselves under similar conditions. Birds classified as LSN are intermediate to these extremes. The inheritance of the LSN abnormality has not been established. In order to determine if the LSN condition was controlled by a single gene, the LSN line was reciprocally crossed with a White Leghorn line to produce two F1 populations. Two F2 populations were produced by randomly mating individuals within each F1 population. Each F1 population was backcrossed to the White Leghorn line. When birds with an exhaustion score of 6 or less were considered LSN, ratios obtained in the F1 population were 3 normal and 134 LSN individuals for the cross of the LSN line males and White Leghorn line females, and 8 normal and 118 LSN for the reciprocal cross, suggesting that the LSN condition was influenced by a dominant gene with incomplete penetrance. The frequencies did not differ between sexes in either F1 cross, suggesting autosomal inheritance. In general, ratios of normal to LSN individuals in the two F2 populations and in the two backcross populations supported the hypothesis that the LSN trait was controlled by a dominant autosomal gene. However, there was an excess of normal females relative to that expected in the cross of the White Leghorn line males and LSN line females. Heritability (h2) of the LSN trait was estimated by regression of F2 offspring on F1 parents. The h2 estimates based on regressions were higher (range = 0.520 to 1.107) in the LSN line male x White Leghorn line female cross than in the reciprocal cross (range = 0.161 to 0.621). The h2 estimates based on regression of offspring on dams were higher for male offspring than for female offspring, suggesting the presence of sex-linked effects. It was concluded that the LSN trait was influenced primarily by an autosomal dominant gene but was also influenced by other genes, some of which were on the sex chromosome.

An experimental line (F) of turkeys was reciprocally crossed with sire lines (designated A and B) from each of two commercial breeders in order to study the inheritance of carcass traits and body shape. The birds were weighed and killed at 17 wk of age, and various measurements of muscling, leg bones, and body shape were made. Additive genetic variation, as indicated by line differences, was an important source of variation in most traits. The only traits that did not exhibit a line difference in any comparison were weight of the drumstick muscles, tarsometatarsal width, keel length, and Body Depth 2 (body depth at a point 2.54 cm anterior to the posterior end of the keel). Heterosis of live BW was greater in males than in females. Heterosis in the weight of the pectoralis major and p. minor muscles were similar to those of live BW, but heterosis in the weight of the leg muscles were higher than that of live BW. The average heterosis for bone measurements (length of the femur, tarsometatarsal, and tibiotarsal bones and tarsometatarsal width) was very low and ranged from -0.3 to 1.4%. For measurements of body shape [keel length, Body Depth 1 (body depth measured at the cranial process of the keel), Body Depth 2, ratio of Body Depth 1 to Body Depth 2, length, width, and height of the body cavity, and body cavity volume index), heterosis was low and the average ranged from -2.7 to 2.6%. Based on an analysis of both sexes combined, the commercial sire lines differed in BW, weights of the p. minor and drumstick muscles, weights of the tarsometatarsal, femur, and tibiotarsal bones, lengths of the tarsometatarsal and femur bones, and various measurements of body shape (Body Depth 1, body depth ratio, body cavity length and height, and body cavity volume index). Relative to the commercial sire lines, the F line was smaller, had less breast and leg muscling, and, in general, larger leg bones when sexes were combined. The carcass of the F line was deeper than that of the commercial sire lines when measured at the cranial process of the keel but not at 2.54 cm anterior to the posterior portion of the keel. Body cavity height and body cavity volume index were larger in the F line than in the commercial sire lines.

An experimental line of turkeys selected for increased BW (F) was reciprocally crossed with sire lines (designated A and B) from each of two major commercial breeders in order to study the inheritance of growth traits. All genetic groups were grown intermingled in confinement with the sexes reared in different houses. Traits measured included BW at 8, 16, and 20 wk of age; shank length, width, and depth; breast width; and walking ability scores at 16 wk of age. The F line had a different growth pattern than the two commercial sire lines. The F line had higher (males) or similar (females) BW in comparison to Line A at 8 wk of age, but by 16 wk of age, Line A was heavier than Line F in both sexes. The difference in BW between the F and A lines increased from 16 to 20 wk of age. Lines F and B did not differ in BW at 8 wk of age, but at 16 and 20 wk of age, Line B birds were heavier than those of F line. Reciprocal effects, a measure of sex linkage and maternal effects, were noted only for breast width of females in crosses of Lines A and F and for shank width and depth of males and 8-wk BW and shank depth of females in crosses of Lines B and F. Heterosis was an important source of variation in BW for males from both crosses. The percentage heterosis at the various ages ranged from 3.1 to 7.5. For females, heterosis (range = 2.6 to 4.9%) was only significant at younger ages (8 wk for the crosses of the A and F lines and 8 and 16 wk for the crosses of the B and F lines). No heterosis for breast width was observed in either cross. Heterosis in walking ability scores was significant only for males from the crosses of Lines B and F. The presence of heterosis was inconsistent for shank measurements.

This study reports the concentration of collagen and its hydroxypyridinoline crosslinks, collagen fibril organization in the dorsal aortas, and systolic blood pressure during the progression of atherosclerosis in Japanese quail selected for cholesterol-induced atherosclerosis. The quail were placed on either a control or 0.5% cholesterol-added diet at approximately 16 weeks of age. The concentration of total collagen did not change in the control arteries during the course of the study, whereas at 5 and 10 weeks of cholesterol feeding, collagen levels decreased in the cholesterol-fed birds. Hydroxypyridinoline concentration increased during the duration of the study in the cholesterol-fed birds and by 15 and 20 weeks of cholesterol feeding, levels were significantly increased over those observed in the control arteries. Transmission electron microscopy showed changes in the organization of collagen fibrils. Increased systolic blood pressure was noted beginning at 10 weeks of cholesterol feeding, which is suggestive of other systemic changes induced by hypercholesterolemia. These results demonstrated remodeling of the collagen component of the dorsal aorta extracellular matrix during the progression of atherosclerosis and are suggestive of other systemic cardiovascular system changes.

Skeletal muscle development is, in part, regulated by myoblast-extracellular matrix interactions mediated by the transmembrane integrin family of heterodimeric receptors. The avian genetic muscle weakness, low score normal (LSN), exhibits modified myotube and sarcomere structure that may be associated with altered integrin expression. Protein expression of the beta1 integrin subunit was measured during normal and LSN Pectoralis major muscle development at 14, 16, and 18 d of embryonic development, and 1 d and 1 and 6 wk posthatch. During embryonic development, integrin expression was downregulated. However, by 1 wk posthatch, integrin levels were upregulated and remained elevated through 6 wk posthatch. This pattern was observed in both normal and LSN muscle development. Overall, beta1 integrin levels were lower in the LSN P. major muscle. In normal and LSN satellite cell cultures, beta1 integrin expression was low during proliferation. In early differentiation, beta1 integrin expression increased and was then downregulated. As observed in the muscle extracts, LSN beta1 integrin expression was significantly lower during differentiation. These results suggest that the regulation of beta1 integrin expression is critical to the progression of myogenesis, and, during LSN myogenesis, decreased expression of beta1 integrin may be associated with modifications in muscle structure.

The extracellular matrix of cartilage and bone is composed mostly of collagen with lesser amounts of other constituents such as proteoglycans. The focus of this brief review will be on the dynamic expression of collagens and proteoglycans in the cartilage and bone extracellular matrices. Recent research has shown the presence of different collagen types and proteoglycans that are differentially expressed in cartilage, in the transition from cartilage to bone, and in the bone extracellular matrices. These findings suggest the complexity of the skeletal extracellular matrix as well as its dynamic expression. Although the composition of both the cartilage and bone extracellular matrices are largely known, the function of each of the macromolecules composing these matrices and their developmental regulation is not well understood. Defects that modify the extracellular matrix, like the chicken chondrodysplasia, nanomelia, and tibial dyschondroplasia, have profound affects on skeletal structure. The poultry industry is currently confronting a high percentage of skeletal deformities due to selection for increased growth rate and needs to consider the effect of extracellular matrix modifications and how to maintain extracellular matrix integrity.

Although it is generally accepted that phonological development is grounded in phonetic learning, there is less agreement for the proposition supported here, that the first phonological structuring constitutes a developmental discontinuity. Data from the phonetic and lexical learning of Finnish consonant duration are presented to illustrate the role of (1) child selection of adult words for early context-supported production based on phonetic learning and (2) child adaptation of adult words to an idiosyncratic template for later production as part of an incipient system. We argue that the latter, but not the former, reflects the construction of a first phonology., (Copyright 2000 S. Karger AG, Basel)

Previous studies have shown that metrical analysis accounts for syllable omissions in young normally developing children better than prior perspectives. This approach has not yet been applied to children with disorders. Inappropriate sentential stress has been proposed as a diagnostic marker for a subgroup of children with suspected developmental apraxia of speech (SD-DAS), suggesting that the application of metrical perspectives to this population may be appropriate. This report extends the goal of identifying diagnostic markers for SD-DAS using analytic procedures from metrical phonology. The lexical metrical patterns of children with SD-DAS were compared to those of a group of children with speech delay (SD) to verify the applicability of metrical constructs to children with disorders while at the same time seeking lexical stress characteristics that might be useful for differential diagnosis. The lexical stress errors of children in both the SD and SD-DAS disorder groups were found to conform to patterns identified in metrical studies of younger normally developing children, confirming the applicability of this approach to children with disorders. Lexical metrical patterns did not differentiate the groups from each other. However, syllable omissions persisted to much later ages in the SD-DAS subjects, especially those children previously identified as having inappropriate phrasal stress. Further metrical studies of the speech of children with suspected SD-DAS are needed, both at the lexical and the sentential level, using both perceptual and acoustic measures.

To delineate the role of proteoglycans in turkey skeletal muscle development, proteoglycan expression was examined in pectoral muscle from 14-, 20-, and 25-d-old embryos. Proteoglycans were separated by DEAE (diethylaminoethyl cellulose) anion exchange and molecular sieve chromatography. Glycosaminoglycan composition was measured by enzyme digestion and nitrous acid deamination. The proteoglycan decorin was analyzed at each of these stages of development for core protein size by polyacrylamide gel electrophoresis and for spatial distribution by immunohistochemistry. Chondroitin sulfate-containing proteoglycans were the predominant proteoglycans found throughout turkey embryonic skeletal muscle development. However, in 20- and 25-d-old pectoral muscle, higher levels of heparan and dermatan sulfate were observed compared with their values at 14 d. Two decorin core protein bands with molecular weights of 45 and 46 kDa were detected. Immunostaining for decorin showed that, as the connective tissue layers developed, decorin was localized in the perimysium and epimysium. These data indicate that turkey embryonic skeletal muscle proteoglycan expression is dynamic and changes from a matrix that is rich in a large chondroitin sulfate proteoglycan to one containing dermatan sulfate, heparan sulfate, and chondroitin sulfate proteoglycans, and suggests the presence of two forms of decorin.

Smooth muscle tumor and ovarian follicular development were studied in lines of Japanese quail selected for increased 4-wk BW (HW, P, and T) and their randombred controls (C and R1). The lines studied were from long-term selection studies at The Ohio State University (HW and R1) and The University of Georgia (P, T, and C). To study the genetic relationship among the lines in the two selection studies, the C, P, HW, and R1 lines were DNA-fingerprinted by digestion of the DNA with the HaeIII restriction enzyme and using Jeffreys' 33.6 probe. The BW of females at 4 wk of age and at the end of a 240-d egg production period were similar for the C and R1 lines. The BW of the selected lines was ranked P > T > HW for both measurements. Smooth muscle tumors were found in the oviducal ligaments adjacent to the magnum. A greater percentage of hens from the BW-selected lines had smooth muscle tumors of greater weight than the randombred control lines, which did not differ in tumor incidence or weight. The P and T lines had a greater incidence of multiple-lobed tumors than the HW line. Based on bandsharing (BS) of DNA fingerprints, the Georgia and Ohio lines did not appear to be closely related, suggesting that, perhaps, the smooth muscle tumors in the BW-selected lines in the two studies might have resulted from pleiotrophic effects of genes affecting growth or to genes closely linked to the growth genes. The BW-selected lines in both selection studies had more ovarian follicles in rapid development, which were of greater weight, than the randombred control lines. The HW line had a larger number of ovarian follicles in rapid development than the P and T lines. The percentage of hens with atretic follicles was greater in the BW-selected lines. The results of the present study suggest that the effect of BW selection on ovarian follicular development may occur early in selection (within the first 30 generations) and is not influenced by additional genetic changes in BW.

The temporal and spatial distribution, and relative levels of the proteoglycan decorin and collagen type I were examined during the progression of atherosclerosis in the dorsal aortas of Japanese quail selected for cholesterol induced atherosclerosis. The quail were placed on either a control or 0.5% added cholesterol diet at approximately 16 weeks of age. Dorsal aortas were collected at 1- or 2-week intervals over a 15-week period after initiating cholesterol feeding. Biochemical analysis for decorin and collagen type I showed that both increased in the cholesterol-fed birds compared to control-fed birds beginning at 9 weeks and continued through the duration of the study. Through immunohistochemical staining for decorin and collagen type I, the spatial localization of decorin and collagen type I in control and less severe plaques in cholesterol-fed birds was most prominent in the arterial adventitia. However, in severe atherosclerotic plaques, decorin was localized in foam cell regions and collagen type I was found surrounding the foam cell regions where decorin accumulated. These results demonstrated a localization of decorin in the core of the atherosclerotic plaque foam cell region with collagen type I being located on the plaque surface.

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.

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.

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.

Expression, and temporal and spatial distribution of type I collagen were investigated in chicken satellite cell cultures during differentiation. There was no difference in the relative amounts of type I collagen after treatment with basic fibroblast growth factor (FGF), insulin-like growth factor-I (IGF-I), or transforming growth factor beta 1 (TGF-beta 1). However, myotube morphology was influenced by the presence of the growth factors. The temporal and spatial distribution of type I collagen was also modified. Control cultures maintained a predominant distribution of type I collagen surrounding the cellular area until approximately 48 h after the initiation of fusion whereas cultures with FGF or IGF-I maintained a cellular localization of type I collagen throughout the fusion process. TGF-beta 1 resulted in the early formation of an extracellular network of type I collagen preceding control cultures by approximately 24 h. These results suggest that type I collagen expression but not localization is independent of satellite cell proliferation and differentiation.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Approaches to the treatment of developmental verbal dyspraxia based upon current theories about phonological development are explored. The author presents the concept of "bridging"; for example, making the transition from one sound to another or from one word to the next, as a reflection of the child's ability to generate hierarchical linguistic structures. The author suggests that children who have developmental dyspraxia must build phonological systems despite the fact that their ability to discover and use these hierarchical structures is impaired. Idiosyncratic patterns are expected, and should be used by the clinician to determine appropriate approaches to remediation for individual children. Case studies illustrate two children's shared difficulties in developing and using phonological hierarchies and the individual differences that provided a basis for appropriate remediation for each child.

The avian mutation, nanomelia, 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. In a previous study, a DNA polymorphism was identified at the 3' end of the core protein gene by using denaturing gradient gel electrophoresis. This polymorphism is characterized by three electrophoretic variants (alleles), two of which are associated with the normal core protein gene and one of which segregates with the nanomelia mutation. This study documents that segregation of the latter electrophoretic variant can be used to substitute for progeny testing in the identification of carriers of the nanomelia mutation. Standard progeny phenotype tests were carried out in conjunction with genotype screening for the putative nanomelia-associated electrophoretic variant. We found the genotype data defining the nanomelia core protein gene locus to correlate with progeny phenotype test results.

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.

Babies are born nonverbal, yet they spontaneously and seemingly effortlessly acquire the complex skills necessary for oral communication. Interestingly, many of these skills have "golden periods" of maximally efficient learning--failure to acquire the skill at that time may lead to speech delay. This article discusses the normal pattern of speech development.