A simple method for squeezing juice from rice stems and its use in the high-throughput analysis of sugar content in rice stems

Sugar content in rice (Oryza sativa L.) stem is an agronomically important trait for rice used in straw silage or whole-crop silage. However, the mechanisms underlying sugar accumulation in rice stems remain unclear, mainly due to the time-consuming method for measuring sugar content. Here, we established a simple method for squeezing stem juice from rice plants, similar to that used during breeding selection in sugarcane or sorghum. The Brix value of the stem juice, which can easily be measured using a portable refractometer, significantly correlated with the soluble sugar contents in the stem juice and tended to correlate with those in stem tissues. This indicates that the Brix value of the stem juice can be used for estimating the sugar content in rice stems. This simple estimation method will be a useful tool for high-throughput analysis of sugar content in rice stems during mutant screening, QTL analysis, and breeding selection.     

Identification of molecular markers associated with sugar-related traits in a <Emphasis Type="Italic">Saccharum</Emphasis> interspecific cross

The cultivated sugarcane (Saccharum spp. hybrids, 2n = 100–130) is one crop for which interspecific hybridization involving wild germplasm has provided a major breakthrough in its improvement. Few clones were used in the initial hybridization event leading to a narrow genetic base for continued cultivar development. Molecular breeding would facilitate the identification and introgression of novel alleles/genes from the wild germplasm into cultivated sugarcane. We report the identification of molecular markers associated with sugar-related traits using an F₁ population derived from a cross between S. officinarum ‘Louisiana Striped’ × S. spontaneum ‘SES 147B’, the two major progenitor species of cultivated sugarcane. Genetic linkage maps of the S. officinarum and S. spontaneum parents were produced using the AFLP, SRAP and TRAP molecular marker techniques. The mapping population was evaluated for sugar-related traits namely, Brix (B) and pol (P) at the early (E) and late (L) plant growing season in the plant cane (04) and first ratoon (05) crops (04EB, 04LB, 04LP, 05EB and 05EP). For S. officinarum, combined across all the traits, a total of 30 putative QTLs was observed with LOD scores ranging from 2.51 to 7.48. The phenotypic variation (adj. R²) explained by all QTLs per trait ranged from 22.1% (04LP) to 48.4% (04EB). For S. spontaneum, a total of 11 putative QTLs was observed with LOD scores ranging from 2.62 to 4.70 and adj. R² ranging from 9.3% (04LP) to 43.0% (04LB). Nine digenic interactions (iQTL) were observed in S. officinarum whereas only three were observed in S. spontaneum. About half of the QTLs contributed by both progenitor species were associated with effects on the trait that was contrary to expectations based on the phenotype of the parent contributing the allele. Quantitative trait loci and their associated effects were consistent across crop-years and growing seasons with very few QTLs being unique to the early season. When the data were reanalyzed using the non-parametric discriminant analysis (DA) approach, significant marker-trait associations were detected for markers that were either identical to or in the vicinity of markers previously identified using the traditional QTL approach. Discriminant analysis also pointed to previously unidentified markers some of which remained unlinked on the map. These preliminary results suggest that DA could be used as a complementary approach to traditional QTL analysis in a crop like sugarcane for which saturated linkage maps are unavailable or difficult to obtain.     

Assessment of different methods to estimate bovine colostrum quality on farm

AIMS: To evaluate two different hydrometers and an optical and a digital Brix refractometer for the assessment of bovine colostrum quality, in terms of accuracy and precision compared with the measurement of IgG concentrations using radial immunodiffusion (RID), and to evaluate the reliability and repeatability of the Brix refractometers.

METHODS: To determine reliability and repeatability, 145 colostrum samples were tested by two independent observers twice, using the optical and digital Brix refractometers. A further 193 colostrum samples from Holstein cows were collected on one commercial dairy farm at first milking and tested with two hydrometers and an optical and digital Brix refractometer. An aliquot of each sample was frozen for RID measurement of IgG concentrations and samples were classified as poor (≤50 g IgG/L) or good (>50?g?IgG/L) quality colostrum. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-observer reliability and repeatability. Optimised cut-off values for the four devices were determined using receiver operating characteristics (ROC) analysis with the RID results as the reference. Using these cut-offs, sensitivities and specificities for determining good quality colostrum were calculated.

RESULTS: The ICC for inter-observer reliability was 0.98 for the optical Brix refractometer, and for intra-observer repeatability was 0.97 and 0.98 for the optical and the digital Brix refractometers, respectively. For the 193 colostrum samples, 67 (34.7%) had concentrations of IgG ≤50 g/L determined by RID. Optimised cut-off values evaluated by ROC analysis were higher for all devices compared with manufacturer reference or previously published values. Using these values, the sensitivities for the two hydrometers, and the optical and the digital Brix refractometers were 0.73, 0.71, 0.56 and 0.79, respectively; specificities were 0.72, 0.61, 0.90 and 0.69, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: The Brix refractometers provided the most accurate assessment of colostrum quality of the devices evaluated, and demonstrated excellent precision in terms of repeatability. To provide optimal health for newborn calves, a sufficient intake of good quality colostrum is essential. The Brix refractometers provide rapid, convenient tools for classification of colostrum quality.     

Use of the Vettest 8008 and refractometry for determination of total protein,albumin, and globulin concentrations in feline effusions

Background— Pleural and peritoneal effusion is a common clinical finding in feline practice. Determination of fluid albumin (ALB) and globulin (GLOB) concentrations in addition to total protein (TP) concentration can be helpful in diagnosing or ruling out certain diseases in cats, especially feline infectious peritonitis (FIP). Objective— The objective of this study was to compare effusion TP, ALB, and GLOB results obtained by a refractometer and a bench‐top dry chemistry analyzer with those results obtained by a reference method. Methods— Twenty‐six pleural and 14 peritoneal effusion samples were analyzed from 40 cats with various diseases. TP and ALB concentrations were determined by a reference automated wet chemistry analyzer (Kone Specific, Kone Instruments, Espoo, Finland), a bench‐top dry chemistry analyzer (Vettest 8008, IDEXX Laboratories Ltd, Chalfont St Peter, UK), and a refractometer (Atago SPR‐T2, Atago Co, Tokyo, Japan). GLOB, albumin to globulin (A/G) ratio, and globulins as a percentage of total proteins (GLOB%) were calculated. Results were analyzed by paired t tests, difference plots, and Deming's regression analysis. Results— Correlation coefficients (r) for TP with Vettest versus Kone and refractometer versus Kone methods were .97 and .94, respectively. GLOB and GLOB% values were significantly higher and A/G ratios were significantly lower with Vettest versus Kone methods. Correlation coefficients for ALB, GLOB, GLOB% and A/G ratio with Vettest versus Kone methods were .86, .93, .82, and .73, respectively. Although correlation with other methods was good, the refractometer underestimated TP concentrations in 3 samples. Conclusions— The refractometer is an acceptable method for determination of TP concentration in feline effusions. The Vettest 8008 also is an acceptable method for the determination of TP and ALB concentrations, however, calculated A/G ratios obtained with the Vettest are unacceptable.     

湛江市甘蔗上下节锤度比与糖分关系研究

以3个湛江地区甘蔗生产种植品种粤糖79／177、新台糖10号和粤糖71／210为材料,通过分期下种的大田试验,研究湛江地区不同植期甘蔗的糖分积累,建立相应的数学模型,探讨湛江市甘蔗上下节锤度比与糖分关系。结果表明,各品种各植期到达各上下节锤度比值0．95的日期,均早于到达最高糖分日期,粤糖79／177为37～80d,新台糖10号为33～86d,粤糖71／210为37～64d。糖分相比也有一定的差距,各品种分别少0．55～1．92,0．55～2．07,0．58～1．25。