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Due to the insufficient quality of varieties with naturally colored fiber, their cultivation on a global scale is limited. For the first time in Azerbaijan, an attempt was made to investigate the possibility of improving the qualitative and economic traits in genotypes with brown fiber. For this, distant hybridization was carried out between tetraploid cultivars of the G. hirsutum L. (white fiber) and artificially obtained amphidiploids with a doubled set of chromosomes from the diploid specie G. arboreum L. (brown fiber), from the local Genbank. On this basis, during 2017-2019, distant hybrids with colored fiber and contrasting quality and productivity potential were studied in detail and identified. Qualitative traits such as micronair (Mic), strength (Str), and Uniformity Index (UI) were found to be comparable to the best parent with white fiber in hybrids with colored fibers, but the Upper Half Mean Length (UHML) still to be improved. The "number of bolls per plant" makes the maximum positive contribution to the total cotton yield. According to the results of the averaged data of two generations (F1 and F2), a change in the degree and direction of correlations between the studied characters, depending on the intensity of the fiber color, was noted.

Brain controllability properties are normally derived from the white matter fiber tracts in which the neural substrate of the actual energy consumption, namely the gray matter, has been widely ignored. Here, we study the relationship between gray matter volume of regions across the whole cortex and their respective control properties derived from the structural architecture of the white matter fiber tracts. The data suggests that the ability of white fiber tracts to exhibit control at specific nodes not only depends on the connection strength of the structural connectome but additionally depends on gray matter volume at the host nodes. Our data indicate that connectivity strength and gray matter volume interact with respect to the brain’s control properties. Disentangling effects of the regional gray matter volume and connectivity strength, we found that frontal and sensory areas play crucial roles in controllability. Together these results suggest that structural and regional properties of the white matter and gray matter provide complementary information in studying the control properties of the intrinsic structural and functional architecture of the brain., Author Summary Network control theory suggests that the functions of large-scale brain circuits can be partially described with respect to the ability of brain regions to steer brain activity to different states. This ability, often quantified in terms of controllability metrics, has normally been derived from the structural architecture of the white matter fiber tracts. However, gray matter as the substrate that engenders much of the neural processes is widely ignored in this context. In the present work, we study the relationship between regional gray matter volume and control properties across the whole cortex and provide evidence that control properties not only depend on the connection strength of the structural connectome but also depend on sufficient gray matter volume at the host nodes.

Objective To analyze the three-dimensional relationships of the operculoinsular compartments, using standard hemispheric and white matter fiber dissection and review the anatomy of association fibers related to the operculoinsular compartments of the Sylvian fissure and the main white matter tracts located deep into the insula. The secondary aim of this study was to improve the knowledge on this complex region to safely address tumor, vascular, and epilepsy lesions with an integrated perspective of the topographic and white matter fiber anatomy using 2D and 3D photographs. Methods Six cadaveric hemispheres were dissected. Two were fixed with formalin and the arteries were injected with red latex dye; the remaining four were prepared using the Kingler method and white fiber dissections were performed. Results The insula is located entirely inside the Sylvian fissure. The topographic hemispheric anatomy, Sylvian fissure, opercula, surrounding sulci and gyri, as well as the M2, M3, and M4 segments were identified. The anatomy of the insula, with the sulci and gyri and the limiting sulci, were also identified and described. The main white matter fiber tracts of the operculoinsular compartments of the Sylvian fissure as well as the main association and commissural fibers located deep in the insula were dissected and demonstrated. Conclusions Complementing topographic anatomy with detailed study of white matter fibers and their integration can help the neurosurgeon to safely approach lesions in the insular region, improving postoperative results in the microsurgical treatment of aneurysmal lesions, insular tumors, or epilepsy surgery.

Background Naturally-colored cotton has become increasingly popular because of their natural properties of coloration, UV protection, flame retardant, antibacterial activity and mildew resistance. But poor fiber quality and limited color choices are two key issues that have restricted the cultivation of naturally-colored cotton. To identify the possible pathways participating in fiber pigmentation in naturally-colored cottons, five colored cotton accessions in three different color types (with green, brown and white fiber) were chosen for a comprehensive analysis of phenylpropanoid metabolism during fiber development. Results The expression levels of flavonoid biosynthesis pathway genes in brown cotton fibers were significantly higher than those in white and green cotton fibers. Total flavonoids and proanthocyanidin were higher in brown cotton fibers relative to those in white and green cotton fibers, which suggested that the flavonoid biosynthesis pathway might not participate in the pigmentation of green cotton fibers. Further expression analysis indicated that the genes encoding enzymes for the synthesis of caffeic acid derivatives, lignin and lignan were activated in the developing fibers of the green cotton at 10 and 15 days post-anthesis. Conclusions Our results strengthen the understanding of phenylpropanoid metabolism and pigmentation in green and brown cotton fibers, and may improve the breeding of naturally-colored cottons.

Background . Cotton production, processing and trade are essential part of the world economy. The acreage under cultivated cotton over the world has expanded during the past five years, while total production of cotton fiber has increased almost twice. Cotton is the most demanded natural fiber in Russia: the share of pure cotton in Russian commercial textile trade is up to 54%. Effective use of Russia's diverse climate conditions to solve priority tasks of the domestic industry and agriculture has high innovative importance, considering that the share of imported cotton in the country's total textile inputs used by its light industry is 40%. Therefore, it is urgent and important enough to evaluate the effect of soil and climate conditions in the south of Russia on cotton yield and fiber quality. Materials and methods. In 2016, a research was accomplished to evaluate the accessions of Gossypium hirsutum L. listed in the introduction catalogue in the steppe areas of Prikubanskaya Plain, Krasnodar Region (Kuban Experiment Station of VIR, Gulkevichi District), according to VIR's guidelines. The most important features of cotton fiber were estimated in the context of the trends existing on the world market (HVI testing). Results and conclusions . Accessions that produced 75 -100% of mature plants after 120 days of vegetation were described. Fiber yield of the studied white fiber accessions was not high. With some exceptions, accessions yielding naturally colored fiber had lower productivity than white fiber ones. The accession i-604984 exceeded the reference in fiber productivity, boll weight, and fiber harvest. The results of HVI tests showed that the evaluated accessions yielded fiber of good quality (4-5th type of the O'zDSt604-2001 standard, Uzbekistan). Fiber of the accessions i-604971 and i-604975 had the best strength. The fibers of all accessions demonstrated high or very high degree of uniformity in length. All white fiber accessions demonstrated normal micronaire values, quite acceptable for textile industry. Micronaire indicators of colored cotton accessions were only slightly lower than those of white fiber ones in maturity and fineness, but these differences were not significant when compared with the references.

Background . The overwhelming majority of commercial cotton cultivars have white fiber. Production of fabrics from such fiber has some disadvantages, therefore an increasing number of genotypes of cotton with the naturally colored fiber is being created around the world in the last decades. An investigation of correlations between different traits makes it possible to reveal the degree of influence of fiber color on structural and agronomic characters, and determine the possibility of creating varieties with naturally colored fiber for profitable cultivation in the north of the Astrakhan Province. Material and methods . Fourteen early lines of upland cotton (Gossypium hirsutum L.) from the trait-specific collection, which have naturally colored fiber, were studied in the north of the Astrakhan Province at the Caspian Research Institute of Arid Agriculture (CRIAA). The study employed the techniques developed at VIR and took into account productivity elements and agronomic traits. The lines were created at the Prikumskaya Experiment and Breeding Station of the Stavropol Agricultural Research Institute (Budennovsk) and CRIAA on the basis of hybrids between Turkmen varieties with brown and green fiber and accessions of early white fiber cotton from Albania and Italy. Two lines had beige fiber, 6 light brown, and 6 green. Microsoft Excel 10 was used in the work. Results and Discussion . The analysis of genotypic correlations showed that due to the insufficiency of the total effective temperatures in 2013, no significant links of colored fiber with other signs were discovered. All the correlations were typical for cotton plants. In the more favorable conditions of 2014, the variability of quantitative traits increased and the correlations that were absent in the previous year were revealed. The negative correlation of fiber color with the first generative branch height (r = -0.53), and positive with the fiber yield (r = 0.57) indicate that the lines with brown fiber have a lower height of fruiting branches development (and potentially a shorter growing season) and a larger yield of fiber. By their characteristics, they approach the industrial white fiber cultivars. These results show that the creation of a cultivar with brown fiber in the near future in Russia is quite possible.

This present study aimed to investigate the effect of training and detraining on the growth, chemical composition, white muscle fibers, and filet texture of the European sea bass (Dicentrarchus labrax L.). Fish were divided into control and training groups, which were subjected to water velocities of 0.2 and 1.0 body length per second (bl s−1), respectively, for 32 days (phase I). Half of the fish in the training group were then randomly selected and detrained at a velocity of 0.2 bl s−1 for another 32 days (detraining group), while the velocity of the remaining fish in the training group (1 bl s−1), and control group (0.2 bl s−1) remained unchanged (phase II). The results showed that the growth, body composition, and white muscle fiber densities of the control and trained fish were not significantly different in either phase. Training significantly altered the muscle fiber distribution (P < 0.05), with the training group having fewer 80–90 μm fibers than the control and detraining group at the end of the experiment (P < 0.05). The training group also had significantly higher values for white fiber muscle textural parameters (hardness, adhesiveness, cohesiveness, springiness, gumminess, and chewiness) in phase I (P < 0.05), and these parameters correlated significantly with pH (P < 0.05). However, these differences in texture and the pH correlation weakened when the fish were detrained in phase II. These results indicated that an increase in muscle pH after training may alter the flesh texture characteristics of sea bass. In addition, sustained swimming could induce a reversible change in the filet texture of sea bass.

This study was undertaken to investigate the effects of sustained swimming exercise on the growth performance, muscle cellularity and flesh quality of juvenile qingbo fish (Spinibarbus sinensis). Experimental fish were exercised under four water velocities, nearly still (control, 3 cm s− 1) and 1, 2 and 4 body lengths (bl) s− 1, for eight weeks at 25 °C. Then, growth performance indicated by the specific growth rate (SGR), white muscle cellularity suggested by the diameter and density of white muscle fiber, flesh quality evaluated by some textural mechanical properties (hardness, springiness, chewiness, cohesiveness) and physico-chemical parameters (pH, color, moisture, ash, protein, fat, amino acids, and fatty acids) were measured. Sustained swimming at moderate velocities (1 and 2 bl s− 1) resulted in a significantly higher SGR and similar white fiber diameter and density compared with the controls. However, the fish trained at a water velocity of 4 bl s− 1 displayed a similar SGR, smaller white fiber diameter and higher white fiber density compared with the controls. Sustained swimming resulted in significant increase in the values of pH and all textural traits but showed no significant effect on the color of the flesh for juvenile S. sinensis. Fish swimming under moderate water velocities exhibited higher levels of the protein content of the muscle, total essential amino acids (∑ EAA) (at 2 bl s− 1) and total amino acids (∑ AA) (at 1 and 2 bl s− 1) compared with control fish. However, the lowest levels of total amino acids (∑ AA) and total n-6 poly-unsaturated fatty acids (∑ n-6 PUFA) were observed in fish swimming at water velocity of 4 bl s− 1. These data suggest that (1) moderate swimming exercise (1 or 2 bl s− 1) improved growth performance, which could not be attributed to changes in white muscle cellularity; (2) sustained swimming showed a positive effect on texture characteristics, which was partly due to the higher white fiber density and flesh pH compared with controls; and (3) moderate swimming exercise (1 or 2 bl s− 1) was beneficial for improving the nutritional quality of the flesh, whereas high-intensity swimming (4 bl s− 1) resulted in an impairment of the nutritional quality of the flesh in juvenile S. sinensis. Statement of relevance We declare that the experiments complied with the current laws of the country in which the experiments were performed and that our paper complied with the laws of commercial aquaculture.

Objective White fiber dissection using a gyrus-based approach was performed to study the various associations, commissural, and projection fiber bundles of the brain. Methods Ten previously frozen and formalin-fixed cadaveric human brains were included. The fiber dissection techniques described by Klingler were used. The primary dissection tools were thin handmade wooden spatulas and curved metallic spatulas with tips of various sizes. The fibers were studied by the naked eye and with the use of magnification. The various fiber bundles were studied using a gyrus-based approach. The dissection was performed through each named gyrus, and the fiber tracts encountered during dissection were identified, and their relationship to other adjacent fiber bundles was studied. Results From our dissections, the white fibers of the brain were divided architecturally into 5 groups—4 horizontal groups and 1 vertical group. The 4 horizontal groups were the superficial, middle, deep, and central groups. The association fibers constituted the superficial, middle, and deep groups. The commissural fibers formed the central group, and the projection fibers formed the vertical group. The course of the fiber bundles and their functional co-relationship were determined. Conclusions When planning the surgical trajectory, knowledge of the location of white matter tracts is essential to help minimize the occurrence of postoperative deficits. Fiber dissection using the Klingler technique is useful in gaining an understanding of the complex 3-dimensional nature of these white matter tracts and can provide a valuable resource in neurosurgical training.

The objective of this work was to evaluate the efficiency of the straw and oxalic acid tests to identify resistance levels of white and colored cotton (Gossypium hirsutum) genotypes to white mold (Sclerotinia sclerotiorum). Ten genotypes were evaluated: five with colored fiber, four with white fiber, and a white-fiber susceptible genotype. The genotypes MAB-1 with white fiber and MAC-2 with colored fiber were the most resistant to white mold, according to the immersion in oxalic acid and straw tests, respectively. These genotypes can be recommended as resistance sources for breeding programs. Both assessed tests are complementary to each other; however, the straw test is more efficient in evaluating the resistance of cotton genotypes to white mold. Resumo: O objetivo deste trabalho foi avaliar a eficácia dos métodos “straw test” e imersão em ácido oxálico na identificação dos níveis de resistência do algodoeiro (Gossypium hirsutum) branco e colorido ao mofo-branco (Sclerotinia sclerotiorum). Foram avaliados dez genótipos: cinco de fibra colorida, quatro de fibra branca e um genótipo suscetível de fibra branca. Os genótipos MAB-1 de fibra branca e MAC-2 de fibra colorida foram os mais resistentes ao mofo-branco de acordo com os métodos imersão em ácido oxálico e straw test, respectivamente. Esses genótipos podem ser indicados como fontes de resistência para programas de melhoramento. Ambos os métodos analisados são complementares entre si; no entanto, o straw test é mais eficiente na avaliação da resistência dos genótipos de algodão ao mofo-branco.

The effect of temperature on muscle development and gill tissue were investigated in larval and juvenile of Lophiosilurus alexandri , a carnivorous Neotropical fish species. Larvae and juveniles were reared at temperatures of 23, 26, 29 and 32 °C for 15 and 35 days, respectively. The larvae were fed Artemia nauplii, while the juveniles received a formulated diet. In both stages, high temperatures resulted in increased fiber diameter of white muscle. Moreover, a pronounced effect of hypertrophy was observed in later stages of development. No alterations to minimum fiber diameter, and similar mosaic standards of muscle growth dynamics, were observed in larvae kept at 23–32 °C, suggesting that hyperplasia was not effected during early stages of development. Gills were analyzed by Degree of Tissue Change (DTC), which is based on the severity of lesions. Significant morphological changes were observed in gills when juveniles were kept at 32 °C, which was considered moderate tissue damage. Temperature modulates cellularity in L . alexandri larvae and juveniles, with pronounced alterations of hypertrophy of white muscle fibers in later stages of development when exposed to elevated temperatures. Higher temperatures may also induce muscle growth dynamics with increased recruitment of new white fiber, increased fiber diameter in the early stages and induced gill lesions.

Skeletal muscle fibers are mainly categorized into red and white fiber types, and the ratio of red/white fibers within muscle mass plays a crucial role in meat quality such as tenderness and flavor. To better understand the molecular difference between the two muscle fibers, this study takes advantage of RNA-seq to compare differences in the transcriptome between extensor digitorum longus (EDL; white fiber) and soleus (Sol; red fiber) muscles of large white pigs. In total, 89,658,562 and 46,723,568 raw reads from EDL and Sol were generated, respectively. Comparison between the two transcriptomes revealed 561 differentially expressed genes, with 408 displaying higher and 153 lower levels of expression in Sol. Quantitative real-time polymerase chain reaction validated the differential expression of nine genes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis discovered several differentially enriched biological functions and processes of the two muscles. Moreover, transcriptome comparison between EDL and Sol identified many muscle-related genes (CSRP3, ACTN2, MYL1, and MYH6) and pathways related to myofiber formation, such as focal adhesion, tight junction formation, extracellular matrix (ECM)-receptor pathway, calcium signaling, and Wnt signaling. In addition, 58,362 and 58,359 single nucleotide polymorphisms were identified in EDL and Sol, respectively, and the sequence of 9069 genes was refined at the 5', 3' or both ends. Numerous novel transcripts and alternatively spliced RNAs were also identified. Our transcriptome analysis constitutes valuable sequence resource for uncovering important genes and pathways involved in muscle fiber type determination, and might help further our understanding of the molecular mechanisms in different types of muscle.

A comparative study was conducted to identify the effects of processing on physical and combustion properties of needlepunched (NP) and hydroentangled (H-E) nonwoven fabrics produced from fibers of white fiber cotton and a naturally colored brown fiber cotton. A significantly higher degree of flame retardancy (FR) in was observed in fabrics produced from brown cotton fibers compared with white fibers. Calorimetry revealed lower heat release capacity, lower peak heat release rate, and total heat release from brown fibers compared with white fibers. The ash content was also higher in brown fiber samples suggesting higher levels of inorganic elements in the brown fibers. Elemental analyses revealed brown cotton fibers had higher levels of known FR elements including phosphorous and magnesium. The H-E process reduced FR in brown fabrics, which also correlated with a reduction in phosphorous. However, brown H-E fabrics still maintained higher FR than white H-E fabrics. Water content analysis indicated higher water levels in brown fibers, particularly brown greige fibers, which correlated with increased FR. Processing parameters such as energy of H-E did not affect combustion of the two fabric types. Scouring of the brown fiber fabrics reduced, but did not remove coloration, while scouring and bleaching removed the brown color completely. Scouring alone, or scouring and bleaching, completely removed the higher FR properties of the brown fiber fabrics. The results indicate that the mechanism of FR in brown cotton fibers is dependent on multiple compositional factors that may include element content, water content, and compounds related to coloration.

In this study, we examined changes in meat quality and content of muscle types during porcine growth. The influence of the longissimus dorsi muscle fiber composition on meat quality and the correlation between 2 fiber-typing methods (histochemistry and real-time quantitative polymerase chain reaction) were examined. Type IIx and type IIb fibers accounted for most of the total number of fibers; the proportion of these fibers increased during porcine growth (75.42, 80.09, and 79.88%, respectively, at 3 different stages of growth). There was a strong positive correlation between the 2 fiber-typing methods; the correlation coefficients of type I, IIa, and IIx+IIb fiber contents were 0.65, 0.88, and 0.92, respectively. The a* value of meat color was significantly lower at 98 days and negatively correlated with white fiber content (r = -0.69, P < 0.01). Water-holding capacity decreased during porcine growth. The drip loss parameter was positively correlated with type IIx+IIb fiber content (r = 0.55, P < 0.05). Decreased pH was strongly positively correlated with type IIx+IIb fiber content (r = 0.61, P < 0.01) and negatively correlated with type IIa fiber content (r = -0.44, P < 0.05). Therefore, we found that the composition of muscle fibers influenced the establishment of meat quality and its alteration during the early postmortem period.

Brown cotton is a kind of naturally colored cotton. Because of less processing and little dying, it is more friendlier to environment than white cotton. For brown cotton, pigment accumulation in fiber is one of the most important characteristics. In this study, we selected a brown fiber line and a white fiber cultivar to determine the factor that affects the pigmentation in brown fiber. Accordingly, fibers were collected to verify the presence of PAs by p-dimethylaminocinnamaldehyde (DMACA) and toluidine blue O (TBO) staining. The PAs content and related genes expressions were determined. As a result, there were obvious differences on the aspect of PAs synthesis in fiber between white cotton and brown cotton. For white fiber, the PAs content reached maximum at 5 DPA, and then gradually decreased to zero. But for brown fiber, the PAs content was increased from 5 to 15 DPA stage, and reached the maximum at the 15 DPA stage, then gradually decreased from 15 to 40 DPA stage. On the contrary, in white cotton, PAs were synthesized in the whole developmental stage from 5 to 40 DPA. And PAs content in brown fiber were far more than that in white fiber, which may be the reason why the brown pigment accumulated in brown fiber.

As eukaryotes, human beings spend their lifetime using two different pathways for energy production: the anaerobic glycolysis pathway and aerobic mitochondria pathway. Energy produced using the glycolysis pathway is utilized for cell division and prompt force of white fiber muscles whereas that produced by the mitochondria pathway is utilized for suppression of cell division and continuous force of red fiber muscles. Herein, it is proposed that there exists a sequential shift of energy production pathways at the fetal stage and during the lifetime. If we introduce this concept in human biology, then it is may be easy to understand the energy requirement characteristics of fetuses, children, adults and aged persons. For example, during childhood the glycolysis pathway is more predominant than the mitochondria pathway in energy production. Reflecting this fact, children grow and extend their height by division of generalized cells of the body. To achieve this, they have to eat meals many times a day (more than three times a day) due to a less efficient energy production rate in the glycolysis pathway. Similarly, the characteristics of adults and aged persons can be well described using this concept.

Electrospinning is a process that employs a high static electrical potential to produce polymeric fibers of nanoscale diameter. The process has been utilized to achieve color change by electrospinning black polymer solutions to produce white fiber mats. When subsequently heated, the electrospun mats undergo a color change from white to black. This phenomenon is demonstrated with three polymer/solvent systems.

MicroRNAs (miRNAs) are small non-coding RNAs that can regulate their target genes at the post-transcriptional level. Skeletal muscle comprises different fiber types that can be broadly classified as red, intermediate, and white. Recently, a set of miRNAs was found expressed in a fiber type-specific manner in red and white fiber types. However, an in-depth analysis of the miRNA transcriptome differences between all three fiber types has not been undertaken. Herein, we collected 15 porcine skeletal muscles from different anatomical locations, which were then clearly divided into red, white, and intermediate fiber type based on the ratios of myosin heavy chain isoforms. We further illustrated that three muscles, which typically represented each muscle fiber type (i.e., red: peroneal longus (PL), intermediate: psoas major muscle (PMM), white: longissimus dorsi muscle (LDM)), have distinct metabolic patterns of mitochondrial and glycolytic enzyme levels. Furthermore, we constructed small RNA libraries for PL, PMM, and LDM using a deep sequencing approach. Results showed that the differentially expressed miRNAs were mainly enriched in PL and played a vital role in myogenesis and energy metabolism. Overall, this comprehensive analysis will contribute to a better understanding of the miRNA regulatory mechanism that achieves the phenotypic diversity of skeletal muscles.

Naturally existing colored cotton was far from perfection due to having genetic factors for lower yield, poor fiber quality and monotonous color. These factors posed a challenge to colored cotton breeding and innovation. To identify novel quantitative trait loci (QTL) for fiber color along with understanding of correlation between fiber color and quality in colored cotton, a RIL and two F2 populations were generated from crosses among Zong128 (Brown fiber cotton) and two white fiber cotton lines which were then analyzed in four environments. Two stable and major QTLs (qLC-7-1, qFC-7-1) for fiber lint and fuzz color were detected accounting for 16.01%-59.85% of the phenotypic variation across multiple generations and environments. Meanwhile, some minor QTLs were also identified on chromosomes 5, 14, 21 and 24 providing low phenotypic variation (

Most of cotton (Gossypium hirsutum) fibers produced in the world are white, in spite of the lint and fiber of tetraploid cottons (G. barbadense), exhibiting various shades of green and brown. Cotton fiber color is a genetically inherited trait resulting from the presence of pigments intermingled with cellulose. Inheritance of fiber color is relatively simple, with high heritability, but in wild accessions it is still unknown. The objective of this study was to determine the inheritance of fiber color in G. barbadense accessions representing different shades of brown. We crossed wild G. barbadense accessions and G. hirsutum cultivars (with white fiber) and obtained the F2 generations, and BC1 and BC2 backcrosses. It may be concluded that fiber color is controlled by one gene, with partial dominance of the brown color over white, except for the grayish color of the PI 435267 accession, which showed the white to be partially dominant.

Seven jaw muscles of the American alligator have been analyzed for histochemical characteristics of their fiber types: Musculus depressor mandibulae (MDM), M. pseudotemporalis (MP), M. adductor mandibulae posterior (MAMP), M. adductor mandibulae externus (MAME, profound and superficial portions), M. intramandibularis (MI), M. pterygoideus anterior (MPta), and M. pterygoideus posterior (MPtp). Classification of muscle fibers in previous studies has been based on (1) the staining properties of myosin ATPase after alkaline and acid preincubations and (2) the staining reactions for SDH, α-GPDH, PAS, and myosin ATPase after alkaline preincubations. In this study fiber types in one group of muscles (MP, MAMP, profound portion of MAME and MI) are classified (1) as type I, IIa, or IIb fibers, according to the system of Brooke and Kaiser (Arch. Neurol. 23:369–379, '70) or (2) as fast twitch glycolytic (FG), fast oxidative glycolytic (FOG), slow oxidative (SO), and tonic (few in number) fibers, according to the system of Putnam et al. (J. Exp. Zool. 214:303–309, '80). A second group of muscles (MDM, MAME superficial portion, MPta, and MPtp) reacted differently in similar histochemical tests and are classified, respectively, as (1) types 1, 2, 3 or (2) types A, B, C. We have distinguished the fiber types as red, intermediate, white, and tonic in analyses on muscle sections. The highest percentage of red and intermediate fibers is found in the MI. All three fiber types are approximately equal in superficial and medial portions of the MDM and the MPtp. Three muscles (MP, MAMP, and MAME) have the highest white fiber composition. These results indicate a correlation between the histochemical profiles of individual muscles and their functions during masticatory movements.

An inspection system has been constructed that uses the illumination within an integrating sphere to maximize the visual contrast of colored contaminants in webs of white wool. Background images formed by the white fiber mass can be suppressed almost completely by using an integrating sphere of relatively simple construction.

The kinetics of thermal aggregation of salt-soluble proteins (SSP) isolated from porcine Longissimus dorsi (75% white fiber, Serratus ventralis (43% red fiber, and Vastus intermedius (76% red fiber) muscles were studied in the presence of sodium tripolyphosphate (TPP). SSP solutions containing 0–2·0% TPP were heated at constant temperatures between 40° and 70°C, and protein aggregation was monitored using turbidity measurements. SSP aggregation followed first-order kinetics, and the rate and extent of aggregation increased with the red fiber content. Addition of TPP generally increased the aggregation temperature for both white and red muscle SSP, but the changes in the aggregation rate varied depending on the specific temperature and muscle type. Arrhenius plots revealed 10·2–11·5% reduction in the activation energy for SSP aggregation caused by 0·5% TPP. These results indicate that SSPs from red and white muscle types differ in thermal properties and response to phosphate treatments.

Twelve male 9-week-old Wistar rats were used in this study. Intrinsic (transverse, longitudinal and vertical) and extrinsic (genioglossus) muscles of the tongue were examined using histochemical methods. Intrinsic muscle consists mainly of intermediate and red fiber types; in contrast, there is an increase in the white fiber type in extrinsic muscle. The predominant fiber types, red and intermediate, in the intrinsic muscle are smaller than those of the extrinsic muscle. Among the intrinsic muscles, the longitudinal muscle fibers show a tendency to be smaller in size than the others. The continuous movement of the intrinsic muscle fibers influences the shape of the tongue and contributes to versatile activity in chewing. In contrast, extrinsic muscle of the rat tongue reflects powerful movements in mastication, swallowing and squeaking owing to the increased percentage composition of the white fiber type.

Muscle fibers of flight (pectoralis major) and leg muscles (gastrocnemius) of the adult pigeon were classified based on succinate dehydrogenase (SDH) activity and myosin adenosine triphosphatase (ATPase) activity following preincubation at various pH's. The fiber structure in semithin as well as ultrathin sections was also evaluated. The pectoral muscle was composed almost entirely of the type IIB red fiber, with type IIB white fibers representing only 3.4% of the total fibers; and the average diameter of the type IIB red fibers was 26.8μm±6.3, whereas that of the type JIB white was 50.9μm±7.9. The pectoral muscle also contained a larger amount of fat droplets and mitochondria in the type IIB red fiber, while relatively smaller amounts of fat droplets and mitochondoria were found in the IIB white fiber. These findings suggest that the major part of pigeon pectoral muscle should be categorized as a fast-twitch (alkali-stable ATPase, Type JIB) and fatigue resistant (high oxidative staining). The leg muscle of pigeon was divided into three types, the type I fiber, the type IIA and IIB fiber. Fiber diameter of the three fiber types was not much different, and the fiber population was 23.0% type I, 33.3% type IIA and 43.6% type IIB. Regarding histochemical properties, the flight and leg muscles were very different in their muscle fibers, thus reflecting the different functions of the two muscles.

Balanced illumination techniques have been used for many years to improve the detection efficiency for colored fiber contaminants in a white fiber mass, e.g., white wool top. The individual fibers in a mass of white wool are essentially transparent, and their images can be partially suppressed by a suitable choice of illumination to increase the contrast of the colored fibers. This paper uses geometrical optics to explain the partial suppression of images formed by transparent fibers under balanced illumination. The paper also shows that these images can be completely suppressed in the ideal situation, where transparent fibers with circular cross section are completely surrounded by a uniformly diffuse source of illumination. The performance of a balanced illumination system can be optimized by choosing illumination conditions that conform more closely to this ideal situation.

Vascularization in the tail musculature, which contains red and white muscle fibers, of the prometamorphic anuran tadpole was analyzed quantitatively by scanning electron microscopy (SEM). The sample was fixed in glutaraldehyde and osmium tetroxide; this was followed by freeze-fracturing in liquid nitrogen. As good ultrastructural preservation and reliable identification of capillaries were given by this technique, various morphometric parameters, cross-sectional capillary area in particular, could be measured exactly. In red muscle fiber that had a small cross-sectional area (2,060.1 micron2), high capillary density (1,283.5 capillaries/mm2) and a large cross-sectional capillary area (96.4 micron2) was found. Although white fiber (9,327.2 micron2) was 4.6 times greater than red fiber in cross-sectional fiber area, capillary density (95.8 capillaries/mm2) and cross-sectional capillary area (29.5 micron2) were 13.4 times and 3.3 times smaller than those of red fiber, respectively. From these morphometric values the following parameters were evaluated; (1) capillary/muscle fiber number ratio of red muscle fiber (2.64) was 3.0 times greater than that of white fiber (0.89); and (2) total cross-sectional capillary area per cross-sectional area of one muscle fiber was 44.0 times greater for red fiber (1,235.4 micron2)/10(4) micron2) than for white fiber (28.1 micron2)/10(4) micron2). Comparison of the latter parameter between the different fiber types may reflect the differences of real blood supply to them; i.e., red fiber was supplied a 44.0-times richer blood flow than white fiber. Advantages of morphometric study by SEM, and the relationship between obtained parameters for vascularization and blood supply to the different muscle fiber types, are discussed.

The capacity of skeletal muscle to synthesize glycogen from lactate was tested in the iliofibularis muscle of the desert iguana, Dipsosaurus dorsalis. Like other reptiles, Dipsosaurus accumulates significant lactic acid concentrations following vigorous exercise. After 5 min of progressively faster treadmill running at 35 degrees C (final speed = 2.2 km/h), blood lactate concentration increased over 14 mM, which decreased 11 mM after 2 h of recovery. Blood glucose concentration remained unchanged throughout at 8.6 +/- 0.46 mM. The role that muscle gluconeogenesis might play in the removal of post-exercise lactate was evaluated. Animals were run to exhaustion at 1.5 km/h on a treadmill thermostatted at 35 degrees C. Animals (n = 43) ran 6.9 +/- 0.75 min prior to exhaustion. Animals were sacrificed and iliofibularis muscles of both hindlimbs removed and stimulated at 2 Hz for 5 min, reducing twitch tension to 6% of prestimulus tension. Fatigued muscles were then split into red and white fiber bundles and incubated 2 h or 5 h at 35 degrees C in Ringer solution or in Ringer plus 20 mM lactate. In muscles tested in August, red fiber bundles incubated in lactate demonstrated a rate of glycogen synthesis of approximately 1 mg/(g muscle . h). In muscles tested in December, red fiber bundles synthesized glycogen at a reduced rate that was not statistically different than in fiber bundles incubated in Ringer solution without lactate. Glycogen synthesis from lactate was not evident in white fiber bundles in either August or December. The period of peak gluconeogenic capacity coincides with the field active season of Dipsosaurus.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle fiber types have been classified mainly according to histochemical staining reactions for glycolytic enzymes, oxidative mitochondrial enzymes and myofibrillar adenosine triphosphatase (ATPase). On this basis, three fiber types can often be distinguished. The red fiber is high in oxidative enzymes and low in glycolytic enzymes and myofibrillar ATPase, whereas the white fiber has the reciprocal characteristics and the intermediate fiber lies somewhere between the two (8, 15, 24). Muscles which contain mostly red fibers are found to be slowly contracting, while a preponderance of white fibers is correlated with fast contracting muscle (17). The ATPase activity of myosin extracted from red and white muscles correlates directly with the speed of shortening of the muscle in rabbits. Red muscle myosin has a lower specific ATPase activity than white muscle myosin (2). Myofibrillar ATPase staining of single fibers also correlates with speed of shortening in cat muscle (5). Myofibrillar ATPase staining has not always been reliable since it does not always correlate with the actomyosin ATPase or with speed of shortening. For instance, the muscle of 5and 10-day-old rabbits stains intensely for myofibrillar ATPase but the actomyosin ATPase is low (16). In newborn animals the speed of shortening is also generally slow (3, 4, 6). Cardiac muscle fibers stain darkly for myofibrillar ATPase (29), but cardiac muscle actomyosin

The number and localization of vertebrate motor endplates on the muscle fiber, and their structure, vary according to phylum and species, and among the different fiber types in a given species. Vertebrate skeletal muscle fibers are classified into two major groups: the twitch (fast) and the slow (tonic) fibers. The twitch fiber has straight Z-lines and a well developed T-SR system, and is singly innervated with en plaque (plate-like) type motor endplate. The twitch fibers are further subdivided into three types: the red (mitochondria-rich), intermediate (mitochondria-moderate) and white (mitochondria-poor) fibers. The motor endplate of the white fiber is large and has a complicated structure, that of the red fiber is small and less complicated, and that of the intermediate fiber possesses intermediate characteristics. The slow fiber has zigzag Z-lines and poorly developed sarcoplasmic reticulum (SR), and is multiply innervated with en grappe (grape-like) type motor endplates. The morphological features of the motor endplate in each of these fiber types of the mammalian, avian, reptilian, amphibian, and fish skeletal muscles are reviewed. Special emphasis has been placed on the three-dimensional structure of the motor endplates of the different fiber types as observed by high-resolution scanning electron microscopy.

The Z disk ultrastructure of white, intermediate, and red fibers from mammalian muscle is examined. Three models are proposed that explain the differences between the three types of Z disk. The three models are all based on the same concept, i.e., looping filaments from both sides of the Z disk. The differences between the models are in terms of the spatial relationships of adjacent loops within the Z disk. In the white fiber Z disk model all the loops from one side of the Z disk are on the same plane. In intermediate fibers there are two planes of loops from both sides of the Z disk, whereas in red fibers there are three planes of loops from both sides. The implications of these three structures are discussed in relation to known physiological differences between the fiber types.

SUMMARY The red fiber content of several porcine muscles was estimated by a histochemical method (affinity for Sudan Black B due to high intracellular lipid content) and a biochemical method (high succinic dehydrogenase activity). Even though the muscles varied widely in total lipid content, the histochemical method was comparable to the biochemical method in categorizing porcine muscles as red or white. Red muscles (> 40% red fibers) contained greater myoglobin concentrations and generally had longer post-rigor sarcomeres than white (< 30% red fibers) muscles. Interrelationships of percent red fibers, succinic dehydrogenase activity, fat content, glycolytic rate, and post-rigor contraction state were discussed.

The semitendinosus muscle of the albino rat is divided grossly into two clearly distinguishable parallel longitudinal bands, one red (anterior) and the other white (posterior). By using mitochondrial content as a criterion for distinguishing fiber types, it is demonstrated that the red portion of the muscle is composed predominantly of red (52%) and intermediate (40%) fibers, while the white portion consists primarily of white fibers (82%). Red fibers have the smallest and white fibers have the largest average diameter. Ultrastructural characteristics of the three fiber types resemble closely those previously described for the rat diaphragm. Red fibers are rich in large mitochondria with abundant cristae, and possess the widest Z lines. In red fibers, the H-band region of the sarcoplasmic reticulum consists of an elaborate network of narrow tubules. In white fibers, mitochondria are smaller, less numerous, and have fewer cristae; Z lines are about half as wide as in red fibers. In the H-band region of the sarcoplasmic reticulum there is a more compact arrangement of broad more or less parallel tubules. Intermediate fibers are similar to red fibers except that their diameters are larger; mitochondria are somewhat smaller and cristae are less abundant; the width of the Z lines is close to that of white fibers. The consistent difference in Z line width establishes this dimension as an important criterion for distinguishing fiber types and facilitates ultrastructural identification, especially of the intermediate fiber.

The ultrastructure of the different kinds of muscle fiber found in the specialised eyestalk levator muscle of Podophthalmus vigil was determined by electron microscopy. Pink fibers have wide, 13 μ sarcomeres, an extensive cleft system, branching Z tubules and a thick layer of mitochondria. Their ratio of thin to thick filaments is 4–5:1. Two distinct kinds of white fiber were found, with sarcomere lengths of 7.9 μ and 9.8 μ. The former have a very well-developed SR, few mitochondria, a thin: thick filament ratio of 3–5:1 and numerous diads. The second kind have a 7:1 ratio, the thin filaments not being in orbits around thick ones. Their SR is quite well developed, but the cleft system only moderately so. There are more mitochondria in them than in the other white fibers.

The ontogeny of fibers has been studied by following changes in phosphorylase activity of avian muscle. In the embryo, phosphorylase reactions of breast, heart, and leg muscle are weak. In breast muscle, the increase in phosphorylase activity is rapid after hatching and can be associated with a concomitant development of the white fiber. At maturity, the predominant fiber shows strong phosphorylase activity. The white fiber, unlike the red, is concluded to be a highly differentiated fiber specialized for anaerobic activity. The abnormal muscles of dystrophic chickens show reactions similar to the normal during the embryonic period. At this time, the white fiber has not yet begun to differentiate. A lag in the formation of the enzyme seen during the first week ex ovo indicates a prolonged embryonic state or a failure of embryo cells to grow. With further development, a rapid increase in enzyme activity does not result in phosphorlyase levels equal to those of normal tissue. Instead, the activity shows a decrease followed by a visible impairment of motor function. It is emphasized that the abnormality in enzyme activity is noted at a developmental stage when red, white, and intermediate fibers are present. Alterations in morphology and histochemical distribution are correlated with changes in total phosphorylase activity. Comments are also made on lactate dehydrogenase, α-glycerophosphate dehydrogenase, and succinate dehydrogenase measured histochemically.

Distinct ultrastructural differences exist at the neuromuscular junctions of red, white, and intermediate fibers of a mammalian twitch skeletal muscle (albino rat diaphragm). The primary criteria for recognizing the three fiber types are differences in fiber diameter, mitochondrial content, and width of the Z line. In the red fiber the neuromuscular relationship presents the least sarcoplasmic and axoplasmic surface at each contact. Points of contact are relatively discrete and separate, and axonal terminals are small and elliptical. The junctional folds are relatively shallow, sparse, and irregular in arrangement. Axoplasmic vesicles are moderate in number, and sarcoplasmic vesicles are sparse. In the white fiber long, flat axonal terminals present considerable axoplasmic surface. Vast sarcoplasmic surface area is created by long, branching, closely spaced junctional folds that may merge with folds at adjacent contacts to occupy a more continuous and widespread area. Axoplasmic and sarcoplasmic vesicles are numerous. Both axoplasmic and sarcoplasmic mitochondria of the white fiber usually contain intramitochondrial granules. The intermediate fiber has large axonal terminals that are associated with the most widely spaced and deepest junctional folds. In all three fiber types, the junctional sarcoplasm is rich in free ribosomes, cisternae of granular endoplasmic reticulum, and randomly distributed microtubules.

From the histochemical study of oxidative enzymes and phosphorylase on the striated muscle of various kinds of animals, the following results were obtained.1) Vertebrate muscles were composed of three types of muscle fibers, the red fiber showed a higher activity of oxidative enzymes the medium fiber showed a moderate activity and the white fiber a lower activity.2) In invertebrate muscle, the prawn and squid muscles were composed of enzymatically different muscle fibers.

Pigment types in various colors of fiber from sheep, goats, and llamas were assayed by a method using high performance liquid chromatography. In these three species the black/gray group is due to eumelanin, which is fully intense in all three species. Red phenotypes are due to pheomelanin and fade considerably with age in fiber from sheep and goats, but not in llamas. This phenomenon has implications on the genetic mechanisms used in generating white fiber. Brown phenotypes in sheep are due to eumelanin, in goats these phenotypes are equivocal, and they were not observed in llamas.

The activity of branched-chain aminotransferase in mitochondria isolated from rat tissues was examined, and the mitochondrial contribution to total tissue branched-chain aminotransferase activity was calculated using the mitochondrial marker enzyme citrate synthase. Mitochondrial aminotransferase activity was highest in heart followed by skeletal muscle, kidney and brain. In heart muscle all of the aminotransferase activity was accounted for by the mitochondrial fraction. Activity was found to be mitochondrial in skeletal muscle with high red fiber content and also in kidney cortex. Activity was predominantly cytosolic in brain and muscles with high white fiber composition. Thus, the distribution of branched-chain aminotransferase activity in skeletal muscle was dependent on fiber type. No branched-chain aminotransferase activity was detected in liver mitochondria, and in liver tissue activity was too low to be relevant at physiological concentrations of branched-chain amino acids. Within a tissue, regardless of the subcellular distribution of aminotransferase activity, the relative rates of transamination with subsaturating or "saturating" concentrations of KIV or isoleucine were similar. Finally, amino acid preference was also similar within a tissue, but not necessarily between or among different tissues.

In a protein-glycogen complex preparation isolated from rabbit skeletal muscle phosphorylase kinase and phosphorylase phosphatase activities are found in membrane fractions of the sarcoplasmic reticulum and proteins adsorbed to the carbohydrate (Meyer et al., 1970). This pattern led to the question where phosphorylase kinase is localized intracellularly. In addition the synthesis of this enzyme was studied, which is a large oligomer (M.W. 1.26 × 106) containing three types of subunits (Hayakawa et al., 1973a,b) of the stoichiometry α4β4γ4 (Cohen, 1973).

The three-dimensional structure of the sarcoplasmic reticulum (SR) in the red, white and intermediate striated muscle fibers of the extensor digitorum longus muscle of the rat was examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure. In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of the A-I junction. Numerous slender sarcotubules, originating from the A-band side terminal cisternae, extend obliquely or longitudinally and form oval or irregular shaped networks of various sizes in front of the A-band, then become continuous with the tiny mesh (fenestrated collar) in front of the H-band. The A- and H-band SR appears as a single sheet of anastomotic tubules. Numerous sarcotubules, originating from the I-band side terminal cisternae, extend in three-dimensional directions and form a multilayered network over the I-band and Z-line regions. At the I-band level, paired transversely oriented mitochondria partly embrace the myofibril. The I-band SR network is poorly developed in the narrow space between the paired mitochondria, but is well developed in places devoid of these mitochondria. The three-dimensional structure of the SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a much smaller total volume of SR than the mitochondria-poor white fiber. Moreover, the volume of SR of the intermediate fiber is intermediate between the two.