Increase In Mean Fibre Diameter Research Articles

Study on distinct quality properties of cashmere from local goat breeds of Mongolia

The research was carried out in 2021 to determine the specific quality properties of local Mongolian breeds of cashmere goats. The research covered 122 herder households from 13 soums in 8 aimags. A total of 4,560 samples were collected from 1,522 goats representing the main factors determining cashmere quality: ecological habitat, various herd management practices, local breeds, age and sex of goats, and cashmere colour. Cashmere fibre diameter (FD), fibre curvature (FC), and coefficient of variation of fibre diameter (CVFD) were tested in 1,522 samples, and cashmere length was tested in 1,387 samples. The overall mean fibre diameter (MFD) was 16.1 μm, mean length (FL) was 44.9 mm, and fibre curvature (FC) was 61.9°/mm. Cashmere from one-year-old goats was significantly finer than cashmere from older goats (about 1.0 μm, P<0.05). Cashmere from does in the samples tested was significantly finer than cashmere from the bucks. Over the range in mean fibre diameter, from 13.5 to 19.0 µm, fibre curvature declined from 87.8 to 44.2°/mm. Of all cashmere samples, 40.6% belonged to super fine (≤15.5µm), 43.7% and 12.1% had a fibre diameter between 15.51-16.80 and 16.81-17.50 μm, respectively, and were suitable for knitwear. Only 3.6% of samples tested were between 17.51 to 19.00 μm and may only be suitable for weaving. The average CVFD values of cashmere of Mongolian breeds of cashmere goats was 22.5 ± 0.04%, with an individual range of 17.0-26.9%. This shows that it has lesser variation than Alashan white cashmere goats of Inner Mongolia Autonomous Region, China, where CVFD ranged from 27.09% to 41.39%. Compared to cashmere from China, Tajikistan, and Kyrgyzstan, with mean fibre curvature of 46, 46, and 58mm, respectively, the cashmere of local Mongolian breeds of goats would be considered curvier and longer, which makes stronger yarns. Short, higher crimped, softer cashmere may be preferred for woollen-spun yarns, but longer, lower crimped, softer cashmere may be preferred for woven yarn destined for knitwear. Fibre curvature of Mongolian cashmere goats declined an average of 6.1°/mm for a 1µm increase in MFD, which is similar to the 5.8°/mm observed in Chinese Liaoning goats, but less than the 13.6°/mm measured in controlled experiments with Australian goats. Significant differences were found between the cashmere of local Mongolian breeds of goats kept in open, natural rangelands and herded in a nomadic way in distinct ecological conditions of harsh continental climate compared to those breeds of goats kept in intensive farming. This shows the potential to offer distinct quality cashmere from local Mongolian breeds while maintaining proper management and selective breeding.

Novel core-shell fiber delivery system for synergistic treatment of cervical cancer

Ganoderma lucidum triterpenoids (GLT) possess advantageous characteristics including anti-inflammatory, anti-oxidant and anti-cancer properties. In this study, a drug loaded core-shell fibrous system was engineered using the coaxial electrospinning method. The core comprised polycaprolactone and GTL whilst the shell contained polyethylene oxide with anti-cancer drug methotrexate. The morphology and structure, chemical composition, biocompatibility and in vitro release profile of the encapsulated GLT was assessed. Scanning electron microscopy images showed cylindrical fibers were developed whilst fluorescence microscopy confirmed the successful formation of core-shell fibers. Increasing GLT concentration from 2 wt% to 6 wt% resulted in an increase in mean fiber diameter from 2.29 ± 1.26 μm to 4.65 ± 2.30 μm, respectively. Fourier transform infrared spectroscopy, X-ray diffraction and differential scanning calorimetry analysis all confirmed that both drugs were encapsulated in amorphous form while contact angle hysteresis showed engineered fibres to possess good hydrophilicity. In vitro drug release tests indicated the release of methotrexate (R2 = 0.9941) and GLT (R2 = 0.9924) were controlled by Fick Diffusion. In vitro cell culture experiments proved that the combined use of traditional Chinese medicine and current western medicine has good application prospects in the treatment of cervical cancer.

Electrospun Combination of Peppermint Oil and Copper Sulphate with Conducive Physico-Chemical properties for Wound Dressing Applications.

The ultimate goal in tissue engineering is to fabricate a scaffold which could mimic the native tissue structure. In this work, the physicochemical and biocompatibility properties of electrospun composites based on polyurethane (PU) with added pepper mint (PM) oil and copper sulphate (CuSO4) were investigated. Field Emission Electron microscope (FESEM) study depicted the increase in mean fiber diameter for PU/PM and decrease in fiber diameter for PU/PM/CuSO4 compared to the pristine PU. Fourier transform infrared spectroscopy (FTIR) analysis revealed the formation of a hydrogen bond for the fabricated composites as identified by an alteration in PU peak intensity. Contact angle analysis presented the hydrophobic nature of pristine PU and PU/PM while the PU/PM/CuSO4 showed hydrophilic behavior. Atomic force microscopy (AFM) analysis revealed the increase in the surface roughness for the PU/PM while PU/PM/CuSO4 showed a decrease in surface roughness compared to the pristine PU. Blood compatibility studies showed improved blood clotting time and less toxic behavior for the developed composites than the pristine PU. Finally, the cell viability of the fabricated composite was higher than the pristine PU as indicated in the MTS assay. Hence, the fabricated wound dressing composite based on PU with added PM and CuSO4 rendered a better physicochemical and biocompatible nature, making it suitable for wound healing applications.

Fabrication and optimization of proton conductive polybenzimidazole electrospun nanofiber membranes

Phosphoric acid (PA)–doped polybenzimidazole (PBI) proton exchange membranes have received attention because of their good mechanical properties, moderate gas permeability, and superior proton conductivity under high temperature operation. Among PBI‐based film membranes, nanofibrous membranes withstand to higher strain because of strongly oriented polymer chains while exhibiting higher specific surface area with increased number of proton‐conducting sites. In this study, PBI electrospun nanofibers were produced and doped with PA to operate as high temperature proton exchange membrane, while changes in proton conductivity and morphologies were monitored. Proton conductive PBI nanofiber membranes by using the process parameters of 15 kV and 100 μL/h at 15 wt% PBI/dimethylacetamide polymer concentration were prepared by varying PA doping time as 24, 48, 72, and 96 hours. The morphological changes associated with PA doping addressed that acid doping significantly caused swelling and 2‐fold increase in mean fiber diameter. Tensile strength of the membranes is found to be increased by doping level, whereas the strain at break (15%) decreased because of the brittle nature of H‐bond network. 72 hour doped PBI membranes demonstrated highest proton conductivity whereas the decrease on conductivity for 96‐hour doped PBI membranes, which could be attributed to the morphological changes due to H‐bond network and acid leaking, was noted. Overall, the results suggested that of 72‐hour doped PBI membranes with proton conductivity of 123 mS/cm could be a potential candidate for proton exchange membrane fuel cell.

Identification of the Ovine Keratin-Associated Protein 26-1 Gene and Its Association with Variation in Wool Traits.

Keratin-associated proteins (KAPs) are structural components of wool and hair fibres, and are believed to play a role in defining the physico-mechanical properties of the wool fibre. In this study, the putative ovine homologue of the human KAP26-1 gene (KRTAP26-1) was sequenced and four variants (named A–D) were identified. The sequences shared some identity with each other and with other KRTAPs, but they had the greatest similarity with the human KRTAP26-1 sequence. This suggests they represent different variants of ovine KRTAP26-1. The association of these KRTAP26-1 variants with wool traits was investigated in the 383 Merino-Southdown cross sheep. The presence of B was associated (p < 0.05) with an increase in mean fibre diameter (MFD), mean fibre curvature, and prickle factor (PF). The presence of C was found to be associated (p < 0.05) with an increase in wool yield (Yield) and mean staple length (MSL), and a decrease in MFD, fibre diameter standard deviation (FDSD), and PF. The results suggest that sheep with C have, on average, higher wool quality. These results may be useful in the future development of breeding programs based on decreasing wool MFD and FDSD, or on increasing wool MSL.

Polymorphism of KRT83 and its association with selected wool traits in Merino-cross lambs

Keratins are structural proteins in the cortex of wool fibres. It is thought that variation in the keratin genes (KRTs) affects wool structure and characteristics. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis was used to investigate three regions of ovine KRT83. These regions were a portion of the promoter, the exon 2 region (including part of intron 1) and a region encompassing exon 3-4 (including all of exon 3, intron 3, exon 4 and part of intron 4). Initially, in 300 New Zealand Romney, Merino and White Dorper sheep obtained from 26 farms, one, two and four PCR-SSCP banding patterns were observed for these regions respectively. The exon 2 region contained two single nucleotide polymorphisms (SNPs) and the exon 3-4 region contained five SNPs. Investigation of the effect of the variation in the exon 3-4 region on variation in some wool traits were subsequently undertaken in 489 Merino×Southdown-cross sheep from seven sire-lines. The four variants identified in the original 300 sheep (designated A-D) and a new variant (E containing a new SNP) were observed with a frequency of 64.6%, 15.4%, 6.6%, 10.1% and 3.3%, respectively. General linear mixed-effects models (GLMMs) were used to investigate associations between the presence or absence of the variants and the wool traits, with a second set of models testing associations between common genotypes and those traits. The presence of A was associated with a decrease in fibre diameter standard deviation (FDSD) and coefficient of variation of fibre diameter (CVFD). The presence of C was associated with an increase in mean fibre diameter (MFD), mean fibre curvature (MFC) and prickle factor (PF), and a decrease in wool yield (Yield) [clean fleece weight (CFW)/greasy fleece weight (GFW)×100%]. A trend for association between the presence of C and increased FDSD was also detected. The presence of D was associated with an increase in MFD and PF, and a decrease in Yield. The presence of E was associated with a decrease in CVFD. Genotype AD had a higher GFW and a lower Yield than AA, and AC and AD tended to have increased MFD compared to AA and AB. These results suggest that ovine KRT83 might be a useful candidate gene for improving wool traits.

Processing of polycaprolactone and hydroxyapatite to fabricate graded electrospun composites for tendon-bone interface regeneration

Abstract The process of electrospinning is utilized with different approaches including conventional electrospinning, extrusion electrospinning, and electroblowing to form nanofibrous meshes and composites. Here, we report on the quality and properties of spatially graded polycaprolactone (PCL) and nano-hydroxyapatite (nHA) composite meshes fabricated with multiple-spinneret electrospinning. The composite meshes were characterized in terms of the amount of spatially allocated nHA concentration across the mesh, fiber diameter, porosity, pore size, and hydrophilicity of meshes. Results show that linearly and continuously varying nHA concentration distribution, i.e. graded structure, can be accomplished across the mesh thickness using multiple-spinneret electrospinning, which is in accordance with the change of mineral concentration observed in native tendon-bone interface. Furthermore, incorporation of nanoparticles into nanofibers led to increased fiber diameter as depicted by a shift in fiber diameter distribution, a significant increase in mean fiber diameter from 361±9 nm to 459±21 nm, and an increase in contact angle from 120.01±2.77° to 115.24±1.17°. These findings suggest that the composite meshes formed in this study could serve as model systems to be used as scaffolds in tendon-bone tissue engineering application in particular, and for other tissue-tissue interfaces in a broader context.

A 57-bp deletion in the ovine KAP6-1 gene affects wool fibre diameter.

High glycine-tyrosine keratin-associated proteins (HGT-KAPs) are predominantly present in the orthocortex of wool fibres. They vary in abundance in different wools and have been implicated in regulating wool fibre properties, but little is known about the functional roles of these proteins in the fibre matrix. In this study, we used polymerase chain reaction--single-strand conformational polymorphism (PCR-SSCP) analysis to screen for variation in a gene encoding the ovine HGT-KAP6-1 protein. We identified three gene variants (A, B and C). Variants A and B were similar to each other, with only three nucleotide differences occurring downstream of the coding sequence. However, variant C had a 57-bp deletion that would notionally result in a loss of 19 amino acids in the protein. The presence of C was found to be associated with an increase in mean fibre diameter (MFD), fibre diameter standard deviation (FDSD), coefficient of variation of fibre diameter (CVFD) and prickle factor (percentage of fibres over 30 microns; PF). Sheep of genotype BC produced wool of greater MFD, FDSD and PF than sheep of genotypes AA, AB and BB. The CVFD was greater in the BC sheep than the AB sheep. The results suggest that variation in ovine KRTAP6-1 affects wool fibre diameter-associated traits and that the 57-bp deletion in this gene would lead to coarser wool with greater FDSD, CVFD and PF.

The relationship of the incidence of medullated fibres to the dimensional properties of mohair over the lifetime of Angora goats

In a range of animals, increasing mean fibre diameter (MFD) of fibre is associated with an increasing incidence of medullated fibres (Med). It would thus be expected that Med in mohair fleeces, from animals in a flock, would be related to the MFD of those fleeces. MFD of mohair is not the only dimensional attribute of fibres. Med in mohair is phenotypically and genetically related to the size of animals. This study examined how Med is related to dimensional properties of mohair over the lifetime of Angora goats and how the relationship varies with other lifetime factors. The relationship found is then examined to determine the extent that the relationship can be explained by variations in animal size of the goats. Measurements were made over 11 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birth weight, birth parity, weaning weight, live weight, fleece growth and fleece attributes were taken for castrated males (wethers). Animals’ fleece-free live weight (FFLwt, kg) were determined for each goat at shearing time by subtracting the greasy fleece weight from the live weight recorded immediately prior to shearing. The average of the FFLwt at the start of the period and the FFLwt at the end of the period was calculated. Two restricted maximum likelihood (REML) models were developed to relate Med to MFD, staple length (SL) and other lifetime factors. One model allowed FFLwt in the model and the other excluded FFLwt. With the exception of the 1.5 years shearing, Med strongly increased with increasing MFD whether or not adjustments were made for FFLwt measurements. In particular Med increased by 2.0% for each 1μm increase in MFD, with no adjustment for FFLwt measurements, and increased by 1.5% for each 1μm increase in MFD, with adjustment for FFLwt measurements. Within each shearing interval increasing average FFLwt was associated with increasing incidence of Med in a similar way to that which has been previously reported without including MFD in the model. There was no evidence that SL needed to be included in the models for Med. Mohair grown by the goats of Mixed genetic background grew mohair which had a higher incidence of Med at ages 2 and 2.5 years and the trend was apparent in other shearing periods. We can conclude that there is both a large response of Med to live weight and a large response to MFD, and that these responses are largely functionally separate. While the response to MFD is in accord with earlier work, there is an unrelated and unreported physiological mechanism that favours the production of Med in larger Angora goats. Clearly, larger Angora goats are biologically different compared with smaller animals from the same flock, in ways that are not purely related to the allometrics of size.

Production, properties and processing of American bison (Bison bison) wool grown in southern Australia

American bison grow a thick coat of fibres which assists them to withstand severe climatic conditions. Bison fibre was traditionally used in textiles by native North Americans. This study aimed to quantify the production, fibre attributes and dehairing processing of bison fibre produced from bison grazed in north-eastern Victoria. Three age/sex classes were sampled (n = 16) at seven body positions in spring. The fibre growing area was measured. Fibre was tested for diameter distribution, clean washing yield, proportion of fine fibres &lt;36 µm and fine fibre length, and processed by cashmere dehairing. Bison were 1–2 years of age, liveweights 160–450 kg and had mean fibre growing area of 1.4 m2. They produced an average 1184 g (range 530–1640 g) of fine fibre with mean fibre diameter 18.5 µm, clean washing yield 76.5%, wax content 9.8%, suint content 14.5%, clean fine fibre yield 56.4%, fine fibre length 37 mm and fibre curvature was 93°/mm. Mid-side fibre had a crimp frequency of 6.5/cm and mean resistance to compression of 6.6 kPa. Fibre had a tenacity of 8.7 cN/tex and an extension of 39.3%. Restricted maximum likelihood mixed model analysis showed age/sex class and sampling site significantly affected all fibre attributes. Finer and longer fibre was produced in anterior sites and in younger bison. Fibre curvature declined 5.3°/mm for each 1-µm increase in mean fibre diameter. Dehaired fibre had a mean fibre diameter of 17.8 µm and mid-length of 28 mm, suitable for woollen spinning. The production by bison of coats containing significant amounts of fibre indicates that careful harvesting of fibre could form an important source of income in bison enterprises.

Variation of fibre characteristics among sampling sites for Huacaya alpaca fleeces from the High Andes

In the Huancavelica region of Peru alpacas form the main and often only means of deriving an income for 3300 poor families in 60 communities. Ninety percent of alpacas in the region are Huacaya which are grazed at altitudes 4000–4800m. Little attention has been paid to alpacas grazed in the High Andes. We aimed to: (i) quantify the variation in alpaca mean fibre diameter (MFD), fibre diameter coefficient of variation (CVD), fibre curvature (FC) and staple length (SL) among 24 sampling sites, (ii) quantify the difference between the mid-side sampling site and other fleece components for each fleece attribute, (iii) identify the sampling site with the highest correlation to the fibre attributes of the fleece in general, and (iv) quantify the relationship between FC and MFD for alpaca. Adult female alpacas (n=31, mean live weight 71kg) were sampled and had their fleece weighed in 8 components. Total mean fleece weight was 3.35kg (range 2.13–6.01). Staples were measured for length (mm) and tested on the OFDA2000 to determine MFD, CVD and FC. The effect of the site was determined using ANOVA analysis. Values for FC were log10 transformed. Correlations between sites and regression analysis between MFD and FC were performed. The mean values for the mid-side site were: MFD 26.3μm; CVD 20.2%; FC 34.9°/mm; SL 91mm, which were finer and longer than other fleece components. The variation in MFD between the 24 sampling sites was 20.2–50.6μm and between 9 sampling sites in the main fleece saddle was 24.8–31.7μm. Fleece attributes varied significantly between all fleece components and among fleece sites (P<0.001). Differences between the mid-side MFD and the MFD of other sites were affected by live weight. The general pattern was a marked dorso–ventral increase in MFD and decrease in FC and SL and a decrease in SL on the neck. The MFD of the mid back site was more correlated with the MFD of the whole fleece than the MFD of the mid-side and the withers sites and may be the preferred site for fleece sampling. There was a significant relationship between log10FC with MFD and site accounting for 86.2% of the variance. This suggests that variation in FC (fibre crimp) can be used for selection of fleece components with different MFD but the slope of the regression (FC declined 1.0°/mm for each 1μm increase in MFD over the range of MFD 11–70μm) indicates that this will only be detected by eye when there are large differences in MFD. The results indicate that care is needed in sampling alpaca fibre for testing and that farmers should separate alpaca fibre carefully at harvest to keep separate fibre of vastly different commercial value.

Influence of grain supplements during winter on liveweight, mohair growth and mohair quality of weaner Angora goats

To identify methods to improve growth and mohair production of weaned Angora goats (mean liveweight 18–20 kg) during their first winter, two supplementary feeding experiments using whole-grain barley and lupins were conducted on a farm in southern New South Wales, in a region where weaner illthrift had been reported. Experiment 1 was a 2 × 2 + 1 factorial with 16 replicate goats; two feeding levels (115 or 230 g/day of whole-barley grain) × two periods of feeding (4 or 8 weeks) + Control (grazing only). Experiment 2 had five treatments × 13 replicate goats; three treatments fed 230 g/day of whole-barley grain for periods of 2 or 3 months and two treatments fed a 50 : 50 mixture of lupin and barley grain at 350 g/day for 2 or 4 months. Goats were individually fed and then all returned together for grazing. There were no effects of feeding in Experiment 1 and variations of feeding 230 g/day of barley in Experiment 2 provided no benefit. Feeding lupin/barley for 4 months increased liveweight (gain 59 g/day), mohair production, mohair fibre diameter and the incidence of medullated fibre. About 25% of this ration was not eaten by eight goats, reducing treatment average intake to 295 g/day. By the end of spring, there was no difference in treatment liveweights. Regression constants indicated that for each 1 μm increase in mean fibre diameter, greasy fleece weight increased 35 g and for each 1 kg increase in pre-shearing liveweight, greasy fleece weight increased 26 g. The results show that Angora weaner goats can grow during winter, provided their energy and protein needs for growth are met. Improved pasture management and higher levels of supplementary feeding to weaned Angoras are indicated compared with current practices on farms in Australia.

Frequency of shearing increases growth of fibre and changes objective and subjective attributes of Angora goat fleeces

SUMMARYThe impact of genotype and of frequency and timing of shearing, on mohair attributes and production of modern Angora goats was studied. Goats in the southern hemisphere grazed pastures between February 2004 and 2006. There were seven shearing treatments by three genetic strains with four or eight replicates of individual goats. Treatments were: three different 6-month shearing intervals and two of 12-month shearing intervals with different months of shearing, a 7-month winter shearing interval and a 3-month shearing interval. Genetic strain was based on sire line: 1·0 South African; 1·0 Texan; and Mixed 0·5 South African and 0·5 Texan. Annual greasy mohair production was 5·08 kg, and average clean fleece production was 4·37 kg. The Angora goats produced an annual clean fleece equivalent to 0·122 of their mean fleece-free live weight which was equal to 0·34 g/kg/day. Measurements were analysed over the period of spring 2004 shearing to spring 2005 shearing, excluding the June–December shearing treatment. Increased frequency of shearing increased fleece growth and affected 13 objective and subjective attributes of mohair that were evaluated including clean washing yield, fibre diameter and fibre diameter variation, incidence of medullated fibres, staple length, fibre curvature, crimp frequency, style, staple definition, staple fibre entanglement and staple tip shape. The direction of these effects were generally favourable and for most attributes the magnitude of the response was linear and commercially important. Each additional shearing resulted in an additional 149 g of clean mohair representing 0·034 of the annual clean mohair production. This increase was associated with a 0·6 cm increase in staple length and 0·32 μm increase in mean fibre diameter. In conclusion, Angora goats shorn less frequently grew less mohair that was more likely to be entangled in spring. Managers of Angora goats should take note of these findings.

Production, attributes and relative value of alpaca fleeces in southern Australia and implications for industry development

An investigation of commercially important alpaca fibre attributes aimed to identify the influence of management and production variables on alpaca fibre and to quantify the relative economic value of fibre production. Fleeces from five farms in southern Australia ( n = 1100) were measured using midside samples and standard tests and were assigned a relative economic value based on an analysis of market price data. Greasy fleece (GFW) and saddle weights of Huacayas peaked at 2 years and Suris at 3 years of age and then declined with increases in age until 6 years of age. GFW of Huacaya were not affected by mean fibre diameter (MFD). In Suris, GFW increased with MFD reaching a peak at 29–33 μm. Mean ± S.D. of clean washing yield was 92.0 ± 1.5%. The proportion of the fleece as saddle, neck and skirting components was (mean ± S.E., %): saddle 55.9 ± 0.9, neck 16.3 ± 0.5, skirtings 27.8 ± 0.6. About, 10% of Huacayas had fleeces with MFD < 24.0 μm, while 14% of Suris had fleeces < 24.0 μm. Both Huacayas and Suris had about 50% of fleeces with mean fibre diameter > 29.9 μm. One-third of Huacaya and Suri saddles had <20% of their fibres medullated. Only, 30% of white Huacaya and Suri samples had >50% of their fibres medullated. For Huacaya and Suri alpaca, the incidence of medullated fibres increased linearly from 10 to 60% by weight as MFD increased from 20 to 36 μm. The ratio of medullated fibre diameter to MFD declined as MFD increased. For Huacaya, there was no change in average staple length as MFD increased. Huacaya alpaca had a greater fibre curvature than Suri alpaca. Data on resistance to compression and staple strength was correlated with other fibre attributes. The price declined by 11% per 1 μm increase in MFD from 22 to 26 μm and by 5% per 1 μm increase between 27 and 34 μm. The total relative economic value increased with increasing GFW and with increasing saddle weight up to 2.5 kg. Total relative economic value declined as MFD increased above 23 μm, increasing live weight above 60 kg and with increasing age above 2 years for Huacaya and 3 years for Suri. The productivity and economic returns from fleece production of Huacaya and Suri breeds was similar. The Australian industry needs to implement commercial mating, shearing and culling strategies to maximise production and returns from animals aged less than 3 years. The main driver of economic value from fleece production was lower MFD of the fleece.

The post-larval development of lateral musculature in gilthead sea bream Sparus aurata (L.) and sea bass Dicentrarchus labrax (L.).

Fibre-type differentiation of lateral musculature has been studied in gilthead sea bream Sparus aurata (L.) and sea bass Dicentrarchus labrax (L.) during post-larval development using ultrastructural, histochemical and morphometric techniques. The study showed three muscle layers: red, intermediate (or pink) and white. Initially, most of the red muscle showed low myosin ATPase (m-ATPase) activity fibres, whereas near the transverse septum some small high m-ATPase activity fibres appeared and later acquired a rosette aspect. Afterwards, during adult growth the red muscle showed a histochemical mosaic appearance. The pink muscle in sea bass was observed at the beginning of juvenile development by the oxidative technique (NADH-RT reaction) whereas in gilthead sea bream it was also observed at the end of larval development. The pink layer consists of high m-ATPase activity fibres. However, along the muscle development other low and moderate m-ATPase activity fibres were observed close to the red and white muscles, respectively. The white muscle of juvenile fish showed a histochemical mosaic appearance near the pink muscle. In adult specimens the mosaic white muscle spread out occupying the whole of the myotome. Morphometric analysis shows a significant increase in mean fibre diameter during post-larval development, as shown by the Student's t-test (hypertrophic growth). Skewness and kurtosis values of fibre diameters point to the generation of a new fibres from the myosatellite cells (hyperplastic growth).

Effect of the β2-adrenergic agonist clenbuterol on the growth of fast- and slow-twitch skeletal muscle of the dystrophic (C57BL6J [formula omitted]) mouse

Clenbuterol (4mg/kg in diet for 21 days) had no statistically significant effect on whole body growth. It did cause a significant increase (18.2%) in wet weight of the fast twitch muscle extensor digitorum longus (EDL) and a corresponding 14.9% increase in total muscle protein. In transverse sections through dystrophic muscle fibre sizes were more variable than in normal muscle. Clenbuterol treatment resulted in a reduction in the proportion of small diameter fibres, and therefore an increase in mean fibre diameter, in dystrophic EDL. Clenbuterol had no significant effect upon the slow twitch muscle soleus.

The larval development of lateral musculature in gilthead sea bream Sparus aurata and sea bass Dicentrarchus labrax

Fibre-type differentiation of the lateral musculature has been studied in Sparus aurata (L.) and Dicentrarchus labrax (L.) during larval development. Histochemical and ultrastructural techniques show two presumptive muscle layers and two germinative zones of presumptive myoblasts. At hatching, myotomal muscle consists of a monolayer of thin undifferentiated cells near the skin (first germinative zone) overlying another mono-layer of small diameter fibres extending hypaxially and epaxially away from the transverse septum. Below this, there is a much thicker, deep layer of fibres, generally large in diameter and polygonal in shape. The presumptive myoblasts are located between these two layers of fibres in the second germinative zone. Initially, the superficial and deep muscle fibres show high and low myosin ATPase activity, respectively. Both layers grow by generating new fibres from the two mentioned germinative zones. At the end of larval life, the superficial layer changes its histochemical profile from high to low myosin ATPase activity and, at the same time, intermediate or pink muscle fibres can be observed by oxidative activity (the NADH-TR reaction). Morphometric analysis shows a significant increase in mean fibre diameter during successive ages, as shown by the Student's t-test (hypertrophic growth). Skewness and kurtosis values of fibre diameters point to the generation of a new fibre population from the germinative zones (hyperplastic growth).

Production losses in Merino ewes and financial penalties caused by trichostrongylid infections during winter and spring

The productivity of Merino ewes treated with ivermectin and a controlled-release capsule containing albendazole was compared with untreated ewes grazing the same pastures on each of 3 farms. Treated breeding ewes had significantly increased greasy fleece weights (GFW, 6.5% and 7.1%) compared with untreated breeding ewes, on 2 of 3 farms but treatment caused no significant increase in the GFW of non-breeding ewes. Other benefits of treatment on all farms were a significant increase in body weight gain (from 1.7 to 3.7 kg) and a significant decrease in the weight of dag removed at crutching (from 42 to 622 g). These benefits occurred despite the presence on each farm of worms resistant to benzimidazoles. One disadvantage of treatment was an increase in mean fibre diameter of wool from treated ewes of from 0.12 to 0.41 microns. This increase reduces the value of the wool. Partial budgets indicated a net loss of from 8 to 62 cents per ewe for treatment. However, potential benefits such as increased growth rate and wool production from lambs of treated ewes were not included in the analysis. On one farm ewes were classified as 'susceptible' to severe dag if they had a dag score > or = 4 at the time of capsule treatment. Ewes classified as 'susceptible' were about 7 times more likely to develop severe dag than were other ewes. There was no significant difference between the GFW of untreated 'susceptible' ewes and untreated ewes not classified as 'susceptible'.(ABSTRACT TRUNCATED AT 250 WORDS)

Mailing muscle biopsy samples for histochemical processing. Conditions and morphometric approach to the alterations induced by storage.

Muscle samples obtained in patients with different neuromuscular diseases were stored at 0 degree C for periods of 6-12h and were subsequently frozen for histochemical processing. Compared to reference samples which had been immediately frozen, the individual test sections displayed different degrees of swelling of the muscle fibres. After 12h of storage the mean diameters had increased by 20% in type-1 and type-2A fibres and by 16% in type-2B fibres. With shorter periods type-2B fibres also showed the smallest amounts of increase in mean fibre diameter. The distribution of fibre diameters, variability coefficients and atrophy and hypertrophy factors showed corresponding changes but rarely fell outside the range defined from the reference sections. The histological, histochemical and cytological quality of the sections remained satisfactory. The decrease in glycogen content during storage appeared to be crucial. Time for mailing samples can be extended up to 27h without essential loss of histo-and cytochemical quality of the sections at the light microscopic level.

Age-related changes in peripheral nerves of the dog. II. A morphologic and morphometric study of cross-sectional nerve.

Qualitative histologic studies and quantitative measurements were made on cross-sectional preparations of common peroneal and ulnar nerves of 32 neuromuscular disease-free dogs from birth to 15 years of age, to provide normative data not available previously. Minimal lesions were seen in nerves of dogs from birth to seven years; however, in older dogs, the incidence of axonal degeneration and segmental demyelination and remyelination increased. Total fiber density of both nerves was over 40,000 fibers/mm2 at birth and declined rapidly during the first six to nine months to level off at about 10,000 fibers/mm2 by one year of age. Density of small (less than 5 micrometers) and large (greater than or equal to 5 micrometers) diameter fibers attained adult values by one year of age. The frequency distribution of the myelinated fibers was unimodal at birth and became bimodal between three and six months of age. The peak of the small and large fiber groups occurred at 3 micrometers and 6 micrometers, respectively. Larger diameter fibers (10 micrometers to 12 micrometers) reached adult values between nine months and one year of age. A 2.5 fold increase in mean fiber diameter occurred during the first year of life. There was no statistically significant change in any histometric parameter after maturity (approximately one year of age).