Near-infrared reflectance analysis for predicting beef longissimus tenderness

Near-infrared reflectance spectra (1,100 to 2,498 nm) were collected on beef longissimus thoracis steaks for the purpose of establishing the feasibility of predicting meat tenderness by spectroscopy. Partial least squares (PLS) analysis (up to 20 factors) and multiple linear regression (MLR) were used to predict cooked longissimus Warner-Bratzler shear (WBS) force values from spectra of steaks from 119 beef carcasses. Modeling used the combination of log(1/R) and its second derivative. Overall, absorption was higher for extremely tough steaks than for tender steaks. This was particularly true at wavelengths between 1,100 and 1,350 nm. For PLS regression, optimal model conditions (R2 = .67; SEC = 1.2 kg) occurred with six PLS factors. When the PLS model was tested against the validation subset, similar performance was obtained (R2 = .63; SEP = 1.3 kg) and bias was small (<.3 kg). Among the 39 samples in the validation data set, 48.7, 87.7, and 97.4% of the samples were predicted within 1.0, 2.0, and 3.0 kg, respectively, of the observed Warner-Bratzler shear force value. The optimal PLS model was able to predict whether a steak would have a Warner-Bratzler shear force value < 6 kg with 75% accuracy. The R2 of MLR model was .67, and 89% of samples were correctly classified (< 6 vs > 6 kg) for Warner-Bratzler shear force. These data indicate that NIR is capable of predicting Warner-Bratzler shear force values of longissimus steaks. Refinement of this technique may allow nondestructive measurement of beef longissimus at the processing plant level.

Two-dimensional electrophoresis and densitometric analysis of solubilized bovine sperm plasma membrane proteins detected by silver staining and radioiodination

Bovine sperm plasma membranes were extracted with deoxycholate and subjected to two-dimensional gel electrophoresis. Proteins were visualized either by silver staining or autoradiography using 125I. When 1.5-2.0 micrograms of protein extract was applied to the first-dimension get, 250 spots could be detected by autoradiography. Thirty micrograms of protein was required to obtain spot visualization using silver strain, revealing more than 500 spots on the gel. These data establish the limit under which two-dimensional electrophoresis can be used in conjunction with flow cytometric sorting of sperm for the analysis of possible sex-specific membrane differences. The necessity of orienting sperm as they past the laser in the cell sorting system reduces throughput; thus, the number of sperm sorted within a given time is limited. It is suggested that autoradiography will allow the flow cytometer to be used in a time-efficient manner. Longer sorting times would be required to obtain sufficient sample to analyze total protein composition.

Protein Differences between Two Isogenic Cultivars of Barley (Hordeum vulgare L.) that Differ in Sensitivity to Photoperiod and Far-Red Light

A photoperiodically sensitive cultivar of barley (Hordeum vulgare L. Shabet) (BMDR-8) and an isogenic, single-gene recessive mutant of this genotype that is insensitive to photoperiod (BMDR-1) were grown under continuous cool white light with or without supplemental far-red fluorescent light. BMDR-1 initiates flowers 6 days after germination, irrespective of light treatment, whereas BMDR-8 remains vegetative for at least a week longer, even in continuous light. When far-red light is added, the delay of flowering in BMDR-8 is overcome and both genotypes initiate floral primordia at the same time. Total phenol extracted proteins of seedlings of both genotypes were resolved by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. No protein differences were found between the genotypes when isoelectric focusing gels were run in the first dimension. Two qualitative genotypic differences were found when nonequilibrium pH gradient gel electrophoresis was run in the first dimension. An 85-kilodalton polypeptide (A) and a 26-kilodalton polypeptide (B) were always present in BMDR-8 but never found in BMDR-1. The levels of A appeared to decrease from the BMDR-8 during the first 3 days of far-red treatment but did not disappear completely even after 6 days of growth in the presence of farred. Polypeptide B decreases rapidly in continuous cool white light but is stabilized by far-red. The phytochrome content of BMDR-1 was found to be greater than that for BMDR-8. This increase appears to be caused by the type I (etiolated-tissue abundant) phytochrome pool, even in plants grown in continuous light.

Computerized comparison of two autoradiographs

Our laboratory previously reported (Anal Chem 55: 2345-2348, 1983) the development of a digitizer and FORTRAN program for display and quantification of digitized autoradiographic images. We have since added several capabilities to the program. Coarse "rubber sheeting" (i.e., transforming coordinates to superimpose images) of the image by a quadratic transformation of pixel coordinates is developed from interactive identification of a few matching spots. The program determines thresholds to display a given proportion of the total protein in the image, or a given number of proteins, and it creates a protein list containing the spatial coordinates of each protein with a peak value above this threshold, together with the amount of the protein as measured by the ratio of its integrated intensity above its half-maximum to the total integrated intensity of the image. The lists can be stored on a disk and are used as the primary data for fine adjustments to superimpose images, quantitative comparison of images, and abstract display of proteins. Methods are discussed for presenting comparisons between gels in cases where spots for many proteins change in intensity.

Computerized comparison of two autoradiographs

Our laboratory previously reported (Anal Chem 55: 2345-2348, 1983) the development of a digitizer and FORTRAN program for display and quantification of digitized autoradiographic images. We have since added several capabilities to the program. Coarse "rubber sheeting" (i.e., transforming coordinates to superimpose images) of the image by a quadratic transformation of pixel coordinates is developed from interactive identification of a few matching spots. The program determines thresholds to display a given proportion of the total protein in the image, or a given number of proteins, and it creates a protein list containing the spatial coordinates of each protein with a peak value above this threshold, together with the amount of the protein as measured by the ratio of its integrated intensity above its half-maximum to the total integrated intensity of the image. The lists can be stored on a disk and are used as the primary data for fine adjustments to superimpose images, quantitative comparison of images, and abstract display of proteins. Methods are discussed for presenting comparisons between gels in cases where spots for many proteins change in intensity.