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BackgroundBlood-based biomarkers have been proposed as an alternative to current sputum-based treatment monitoring methods in active tuberculosis (ATB). The aim of this study was to validate previously described phenotypic, activation, and cytokine markers of treatment response in a West African cohort.MethodsWhole blood immune responses to Mycobacterium tuberculosis ESAT-6/CFP-10 (EC) and purified protein derivative (PPD) were measured in twenty adults at baseline and after 2 months of standard TB treatment. Patients were classified as fast or slow responders based on a negative or positive sputum culture result at 2 months, respectively. Cellular expression of activation markers (CD38, HLA-DR), memory markers (CD27), and functional intracellular cytokine and proliferation (IFN-γ, Ki-67, TNF-α) markers were measured using multi-color flow cytometry.ResultsThere was a significant increase in the proportion of CD4+CD27+ cells expressing CD38 and HLA-DR following EC stimulation at 2 months compared to baseline (p = 0.0328 and p = 0.0400, respectively). Following PPD stimulation, slow treatment responders had a significantly higher proportion of CD8+CD27–IFN-γ+ (p = 0.0105) and CD4+CD27+HLA-DR+CD38+ (p = 0.0077) T cells than fast responders at baseline. Receiver operating curve analysis of these subsets resulted in 80% sensitivity and 70 and 100% specificity, respectively (AUC of 0.82, p = 0.0156 and 0.84, p = 0.0102).ConclusionOur pilot data show reductions in expression of T cell activation markers were seen with treatment, but this was not associated with fast or slow sputum conversion at 2 months. However, baseline proportions of activated T cell subsets are potentially predictive of the subsequent speed of response to treatment.

SummaryThe geographically restrictedMycobacterium africanumlineages (MAF) are primarily found in West Africa, where they account for a significant proportion of tuberculosis. Despite this phenomenon, little is known about the co-evolution of these ancient lineages with West Africans. MAF andM. tuberculosissensu stricto lineages (MTB) differ in their clinical, in vitro and in vivo characteristics for reasons not fully understood. Therefore, we compared genomes of 289 MAF and 205 MTB clinical isolates from the 6 main human-adaptedM. tuberculosiscomplex lineages, for mutations in their Electron Transport Chain and Central Carbon Metabolic pathway in order to explain these metabolic differences. Furthermore, we determined, in silico, whether each mutation could affect the function of genes encoding enzymes in these pathways.We found more mutations with the potential to affect enzymes in these pathways in MAF lineages compared to MTB lineages. We also found that similar mutations occurred in these pathways between MAF and some MTB lineages.Generally, our findings show further differences between MAF and MTB lineages that may have contributed to the MAF clinical and growth phenotype and indicate potential adaptation of MAF lineages to a distinct ecological niche, which we suggest includes areas characterized by low oxygen tension.

Five experiments were carried out to measure the effects of seed rate and fertilizers on the establishment and early growth of reseeded grass mixtures in the Falkland Islands. Experiments 1 and 2 compared seed rates within the range 7·5-35kg ha−1. Experiment 3 assessed the effects of three levels of each of nitrogen (N), P2O5, K2O and CaCO3 applied as seedbed fertilizers. Experiments 4 and 5 were similar in intent to Experiment 3, but treatments consisted of either nil or a very heavy application of the same fertilizer elements. In all experiments, the grass seed mixtures were sown in late summer after rotavation and burning of Cortaderia pilosa dominant indigenous vegetation on peaty soils. Percentage ground cover was estimated in the following spring and dry matter production through the first year was determined by sample harvests. Initially, heavier seed rates resulted in higher percentage ground cover of sown species, but dry matter production over the season following sowing showed a significant increase only between the 25 and 35 kg ha−1 rates in Experiment 2. The modest levels of seedbed fertilizers applied in Experiment 3 had no significant effect on either percentage ground cover of sown species or dry matter production. Even at the higher levels used in Experiments 4 and 5, only N consistently increased dry matter yields, although a significant positive response was also obtained from CaCO3 in the final harvests. The implications of the results to farmers in the Falkland Islands who may be contemplating reseeding are discussed.

SUMMARY The influence of season, and certain agronomic treatments (irrigation, nitrogen fertiliser, density of planting and sowing date) on leaf number were analysed in a series of sugar-beet crops grown during the five seasons 1978-82. Leaf appearance was a linear function of thermal time (accumulated temperature above 1°C) and could be described by four variables: a) the thermal duration of the seedling establishment phase, d′s; b) the thermal time interval between appearance of each of the early leaves, θe; c) the thermal duration of the early phase of leaf appearance, d'a, and d) the thermal time interval between the appearance of each of the later leaves, θ1. The progression of leaf death could also be described by a thermal time interval, θd. There were only small differences in the number of leaves produced by the eleven crops grown during the five seasons. Such differences as appeared, were largely attributable to changes in d'a and θ1, which were interpreted as responses to increasing competition for mineral nutrients and assimilate at the shoot apex. θe was similar in all crops; 30°Cdays were needed between the appearance of each of the early leaves. Only the early leaves died. Each one was retained by the plant longer than its predecessor. Increasing soil moisture deficit under an unirrigated crop shortened θd and depriving crops of nitrogen lengthened it. It is concluded that small differences in the rates of leaf appearance did not greatly influence the rates at which leaf canopies expanded early in the season, but that the rates of leaf death influenced both the time at which the canopies reached their maximum sizes and the rates at which leaf areas subsequently declined.

A study was made of weaning weights in a beef herd, using a rotational crossbreeding system including the Boran breed (zebu) and two temperate beef breeds (Devon and Limousin), and a seasonal calving period spanning the onset of the rains.Significant sources of variation in calf weaning weights were crossbred type, age at weaning, sex, dam's age, season of birth, year and a year × crossbred type interaction (all P < 0·001).The adjusted mean weaning weight was 203 kg. Weaners sired by a temperate bull were generally 1·08 times the weight of those sired by a zebu bull. Steers were 1·06 times the weight of heifers. Marked increases in weaning weights occurred as dams increased in age from 3 to 6 years and slight increases continued up to 9 years of age. Weaners born to 9-year-old cows were 1·09 times the weight of those from first calvers.Alternative methods for investigating the effect of season of birth were examined and the final choice was a covariate for time from birth to the onset of the rains. Calves born in the earliest part of the calving period were approximately 1·14 times the weight of those born just after the onset of the rains.

SUMMARYThe Land Equivalent Ratio (LER) concept is presented and interpreted. Several different intercropping systems are considered and the need for methods to evaluate them is discussed. A general form of the LER is proposed for the evaluation, in particular, of a system that combines two intercrops having different yield proportions. Appropriate LER curves, obtained by varying the yield proportions, are used to compare different intercropping systems, and the importance of this approach is discussed.

SUMMARY The symbiotic effectiveness of four cultivars of red clover were compared and breeding programmes undertaken to increase nitrogen fixation and yield of agar- and pot-grown plants. Programme I used the moderately effective Rhizobium trifolii strain 0403 and Programme II the highly effective strain 5. Aggregate scores of plant size (leaf area) were chosen as the criterion of selection. All cultivars, inoculated with strain 0403, differed in time of initial nodulation and in dry matter yield and three differed in leaf area. None differed in nodule number or N-content. Dry matter and leaf area were highly correlated. Diallel crosses among highly effective selections in Programme 1 gave progeny yields that exceeded those of crosses between modal selections by averages of 6% in the first generation, 5% in the second generation and 23% in the third generation. Yields of the high cross category exceeded those of the original cultivar by an average of 9% in the second generation and by 25–101% in the third generation. Effects on leaf area were similar. Highly effective progeny tended to nodulate earlier and have more nodules than the remainder but differences were very small. Crosses between cultivars were generally more effective than those within cultivars, indicating heterotic effects. Similar results for yield were obtained in Programme II. The average increase in yield of crosses of third-generation material between highly effective selections compared with cv. S123 was 63%. The modal crosses were intermediate. In each Programme and generation there were large differences between parents within each cross category.

SUMMARY Leaf growth of nine varieties of sugar beet (Beta vulgaris L.) was studied at constant temperatures of 7, 11, 15 and 20·C, using generalised logistic curves fitted to the data to estimate the parameters of growth. The rate of leaf appearance increased linearly with temperature and was the same in all varieties. There were differences between varieties in the weighted mean rates of expansion of leaf area per plant (Ā), the temperature coefficient of Ā and the leaf area duration (D); these differences were caused more by differences in rates of expansion and final sizes of individual leaves than by differences in rates of leaf production. The growth of the first six leaves produced by each plant was examined in detail. The greater size of successive leaves of plants and genotypic differences between comparable leaves were more attributable to differences in the rate than differences in the duration of leaf expansion. Increasing temperatures increased leaf size because they accelerated the rate of expansion more than they shortened the duration of the expansion phase. It is inferred that all effects arose through differences in the initial sizes of leaves before they unrolled from the shoot apex. Dry matter production was proportional to D but was partitioned more to the storage root at the colder temperatures. This may have been related to the differential effects of temperature on cell division and expansion and the relative contribution of these two processes to the final sizes of the leaves and storage root.

Methods of assessing stability are reviewed. These include using measures based on variances, regressions against environmental indices, and risk probabilities. A new approach using bivariate distributions of intercrop and monocrop yields is developed, leading to the calculation of relative risks for the two systems. The bivariate distribution methods proposed are illustrated by application to five sets of data on intercrop combinations each including sorghum.