Measurement of α-Amylase Activity in White Wheat Flour, Milled Malt, and Microbial Enzyme Preparations, Using the Ceralpha Assay: Collaborative Study

This study was conducted to evaluate the method performance of a rapid procedure for the measurement of α-amylase activity in flours and microbial enzyme preparations. Samples were milled (if necessary) to pass a 0.5 mm sieve and then extracted with a buffer/salt solution, and the extracts were clarified and diluted. Aliquots of diluted extract (containing α-amylase) were incubated with substrate mixture under defined conditions of pH, temperature, and time. The substrate used was nonreducing end-blocked p-nitrophenyl maltoheptaoside (BPNPG7) in the presence of excess quantities of thermostable α-glucosidase. The blocking group in BPNPG7 prevents hydrolysis of this substrate by exo-acting enzymes such as amyloglucosidase, α-glucosidase, and β-amylase. When the substrate is cleaved by endo-acting α-amylase, the nitrophenyl oligosaccharide is immediately and completely hydrolyzed to p-nitrophenol and free glucose by the excess quantities of α-glucosidase present in the substrate mixture. The reaction is terminated, and the phenolate color developed by the addition of an alkaline solution is measured at 400 nm. Amylase activity is expressed in terms of Ceralpha units; 1 unit is defined as the amount of enzyme required to release 1 μmol p-nitrophenyl (in the presence of excess quantities of α-glucosidase) in 1 min at 40°C. In the present study, 15 laboratories analyzed 16 samples as blind duplicates. The analyzed samples were white wheat flour, white wheat flour to which fungal α-amylase had been added, milled malt, and fungal and bacterial enzyme preparations. Repeatability relative standard deviations ranged from 1.4 to 14.4%, and reproducibility relative standard deviations ranged from 5.0 to 16.7%.

Predictors of Outcomes of Living Kidney Donation: Impact of Sex, Age and Preexistent Hypertension

CONTEXT

Living kidney donation is considered a safe procedure with excellent outcomes. The great demand for organs has changed the suitability criteria for donation and older or hypertensive donors are increasingly accepted.

METHODS

We reviewed the charts of 200 adults who donated a kidney at the University Hospital Hannover. Data regarding diastolic, systolic, mean blood pressure, renal function, and proteinuria at baseline and post-donation follow-up visits were recorded. A Mann-Whitney U test was performed to compare the post-nephrectomy development of blood pressure, estimated glomerular filtration rate (eGFR), and proteinuria between men and women, hypertensives and normotensives, and older (≥65 years) and younger (<65 years) donors. Multivariable time-dependent Cox regression models were used to evaluate eGFR decline post-donation, after adjustment for covariates.

RESULTS

The majority of donors were female (64.5%), and 29.0% had pre-existing hypertension. The mean age at donation was 49 years, and 9.5% were older than 65 years. During a median follow-up of 3 years, no significant differences in proteinuria and change in renal function were observed between both sexes or hypertensive and normotensive donors. In contrast, older donors exhibited a faster decline in renal function. Mean eGFR (chronic kidney disease epidemiology collaboration equation) pre-donation was 99.6 ± 21.9 mL/min in younger donors and 77.6 ± 17.7 mL/min in older donors (P < .001). The respective mean values at the last follow-up visit were 81.3 ± 24.0 and 46.8 ± 17.9 mL/min (P < .001). After adjustment for sex and preexisting hypertension, compared to younger donors, older donors had a 2.39 hazard ratio for eGFR decline.

CONCLUSION

Older adults display a faster decline in renal function after donation and thus should be carefully evaluated for suitability before donation.

Mapping and QTL analysis of the barley population Chebec × Harrington

A doubled haploid population of 120 individuals was produced from the parents Chebec, an Australian 2-row barley of feed quality with resistance to the cereal cyst nematode, and Harrington, a 2-rowed, Canadian variety of premium malting quality. This paper describes 18 field and laboratory experiments conducted with the population and summarises the traits mapped and analysed. The genomic location of 25 traits and genes is described and marker–trait associations for 5 traits (malt extract, diastatic power, resistance to cereal cyst nematode, early flowering, resistance to pre-harvest sprouting) important to Australian efforts to improve malting barley varieties have been used in practical breeding programs. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue.

Mapping and QTL analysis of the barley population Galleon × Haruna Nijo

A genetic linkage map consisting of 435 molecular markers has been constructed using a doubled-haploid mapping population derived from a cross between the Australian barley feed variety Galleon and Haruna Nijo, a Japanese barley cultivar of high malting quality. This map was used to locate the genes conferring CCN and SFNB resistance from Galleon and to locate malting and brewing quality genes from Haruna Nijo. Closely linked markers to the trait loci have been identified and are now being widely implemented in Australian breeding programs.

Quantitative trait loci controlling kernel discoloration in barley (Hordeum vulgare L.)

Barley kernel discoloration (KD) leads to substantial annual loss in value through downgrading and discounting of malting barley. KD is a difficult trait to introgress into elite varieties as it is controlled by multiple genes and strongly influenced by environment and maturity. As the first step towards marker assisted selection for KD tolerance, we mapped quantitative trait loci (QTLs) controlling KD measured by grain brightness [Minolta L; (Min L)], redness (Min a), and yellowness (Min b) in 7 barley populations. One to 3 QTLs were detected for grain brightness in various populations, and one QTL could account for 5–31% of the phenotypic variation. The QTL located around the centromere region of chromosome 2H was consistently detected in 6 of the 7 populations, explaining up to 28% of the phenotypic variation. In addition, QTLs for grain brightness were most frequently identified on chromosomes 3H and 7H in various populations. Australian varieties Galleon, Chebec, and Sloop contribute an allele to increase grain brightness on chromosome 7H in 3 different populations. A major gene effect was detected for grain redness. One QTL on chromosome 4H explained 54% of the phenotypic variation in the Sloop/Halcyon population, and was associated with the blue aleurone trait. A second QTL was detected on the long arm of chromosome 2H in 3 populations, accounting for 23–47% of the phenotypic variation. The major QTLs for grain yellowness were mapped on chromosomes 2H and 5H. There were strong associations between the QTLs for heading date, grain brightness, and yellowness. The molecular markers linked with the major QTLs should be useful for marker assisted selection for KD.

Mapping and QTL analysis of the barley population Alexis × Sloop

Two populations between the German malting variety Alexis and the Australian malting variety Sloop were constructed, mapped, phenotyped, and subjected to quantitative trait loci analysis. One population consisted of 153 F4-derived recombinant inbred lines and the other of 111 doubled haploid lines. This paper describes 18 field and laboratory experiments conducted with the populations and summarises the traits mapped and analysed. The genetic basis of 5 traits (malt extract, resistance to leaf rust, resistance to powdery mildew, early flowering, plant stature) important to Australian efforts to improve malting barley varieties was elucidated. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue.