Combining historical agricultural and climate datasets sheds new light on early 20th century barley performance

Barley (Hordeum vulgare ssp. vulgare) is cultivated globally across a wide range of environments, both in highly productive agricultural systems and in subsistence agriculture and provides valuable feedstock for the animal feed and malting industries. However, as the climate changes there is an urgent need to identify adapted barley varieties that will consistently yield highly under increased environmental stresses. Our ability to predict future local climates is only as good as the skill of the climate model, however we can look back over 100 years with much greater certainty. Historical weather datasets are an excellent resource for identifying causes of historical yield variability. In this research we combined recently digitised historical weather data from the early 20th century with published Irish spring barley trials data for two heritage varieties: Archer and Goldthorpe, following an analysis first published by Student in 1923. Using linear mixed models, we show that interannual variation in observed spring barley yields can be partially explained by recorded weather variability, in particular July maximum temperature and rainfall, and August maximum temperature. We find that while Archer largely yields more highly, Goldthorpe is more stable under wetter growing conditions, highlighting the importance of considering growing climate in variety selection. Furthermore, this study demonstrates the benefits of access to historical trials and climatic data and the importance of incorporating climate data in modern day breeding programmes to improve climate resilience of future varieties.     

Batch ethanol fermentation of molasses: a correlation between the time necessary to complete the fermentation and the initial concentrations of sugar and yeast cells

Batch fermentations of sugar-cane blackstrap molasses to ethanol, using pressed yeast as inoculum, demonstrated an exponential relationship between the time necessary to complete the fermentation and the initial concentrations of sugar and yeast cells. The parameters of the derived exponential equations depended on the experimental conditions.     

‘Hard’ data for matrix modelling of Laminaria digitata (Laminariales,Phaeophyta) populations

The objective of the study was to produce a size-based matrix model of a Laminaria digitata (L.) Lamour. population. Hard data for insertion in the matrix were collected in a 9 year cohort analysis of size and age specific survival and fertility for a stand in south west Nova Scotia, Canada. The product of the square matrix containing these values and a column vector containing the densities of size classes was used to project the size class structure one year later. The projected estimates were found to fit empirical estimates with some confidence. In contrast, an age-based fertility life table wrongly predicted a population declining in density by 45% per year. The study supports, in theory, the use of size-based matrix models for management of harvested stands. In reality, the amount of work required to obtain hard data and the site specific nature of the projections may preclude the use of such an approach to broad scale management.     

Simulation model of soil compaction and root growth

Soil compaction is a widespread cause of reduced plant productivity. If the effects of soil compaction on plant growth are to be reproduced in simulation models, then the processes through which compaction reduces root elongation must be expressed mathematically and then tested against experimental data. The mathematical theory by which these processes may be represented is given in the accompanying article. In this article, the behavior of a simulation model based on this theory is tested against data for root growth and soil gas concentration recorded from soil columns of which the middle layers were compacted to different bulk densities. The model was able to reproduce the failure of the root system to penetrate the compacted middle layer within the period of the experiment when bulk density exceeded 1.55 Mg m^-3. The model also reproduced decreases in O₂ concentrations, and increases in CO₂ concentrations, in the atmospheres of the compacted layer and of the uncompacted layer below it as bulk density of the compacted layer increased. The simulated time course of O₂ and nutrient uptake and of O₂ concentrations in the compacted layer at different depths is presented and its consistency with experimental findings is examined. As part of a larger ecosystem model, this model will be useful in estimating site-specific effects of soil compaction on carbon cycling in agroecosystems.     

Modelling of sulfur oxidation from elemental sulfur

An elemental S oxidation model has been developed which combines a maximum S release rate with modifiers for temperature and soil moisture conditions. This model has been combined with a pasture growth and CNSP nutrient cycling model to match S oxidation rate to pasture S demand. In two Southern Australian enviroments, 100m elemental S was superior to 200m particles whilst in Northern Australia the 200m particles were superior. These models can be used to match S release to plant demand.     

Thermal time and ecological strategies - a unifying hypothesis

Rates of embryogenesis and of development and growth in several nematodes are linearly related to temperature over a considerable range. On this basis, published data on the thermal time requirements are compared for a tropical and a temperate species of plant parasitic nematode Meloidogyne javanica and M. hapla respectively, the two being closely related and morphologically and biologically similar. M. hapla has a lower base temperature (T_b) and a higher thermal constant (S) than M. javanica with the relative values being almost inversed. Consequently, above their respective T_b values the slope of the relationship between rate of development and temperature was greater for the tropical species than that for the temperate species. A mathematical exploration of the relationship between T_b and S was made assuming that, over a narrow range, T_b×S was a constant. With this assumption, for any given average environmental temperature (T_e) the optimum base temperature for minimum developmental duration was T_e/2, and the temperature at which the duration of development was equal for the otherwise identical species was shown to be the sum of their base temperatures. The practical effect of the differences in T_b and S was to give M. hapla, the temperate species, a shorter life cycle and hence a competitive advantage at temperatures below 21ÅC and M. javanica, the tropical species, the advantage above that temperature. It is argued that a negative correlation between T_b and S is likely to be widespread, and provides a mechanism for regulating the distributions of related, competing organisms. Support for the hypothesis that the value of S tends to decrease as T_b increases is derived from data on the embryogenesis of an animal parasitic nematode Haemonchus contortus and from seed germination studies. Contrary results and exceptions are also briefly discussed. The observed interaction between T_b and S may be fundamental to many poikilothermic organisms and plants and provides an explanation for tropical species generally having higher T_b values than temperate ones. The ecological implications of different values of T_b and of S, including their relationship with organisms which are “r” or “K” strategists are briefly discussed.     

Optically active analogues of ebastine: Synthesis and effect of chirality on their antihistaminic and antimuscarinic activity

A series of optically active analogues of the H₁-antihistamine ebastine, with chiral center(s) at the benzhydryl and/or phenylbutyl part of the molecule, have been synthesized. Their in vitro antihistaminic and antimuscarinic activities were investigated, along with a molecular modelling study. It was found that introduction of the benzhydryl chiral center yielded significant stereoselectivity for both antihistaminic and antimuscarinic activities. The steric preferences of the benzhydryl chiral center for antihistaminic and antimuscarinic actions were mirror images of each other. The (?)-isomer of 4-methylebastine ( 6d ) showed more than 10-fold higher in vitro antihistaminic potency than ebastine. Meanwhile the selectivity of 6d for histamine H₁-receptors was also increased by more than 20 times in comparison with ebastine. The chirality at the phenylbutyl part of the molecule does not significantly alter the antihistaminic or antimuscarinic activity of the compounds although the (S)-isomers showed slightly but unanimously higher antihistaminic activity than the (R)-isomers. These results have been discussed with existing stereoselectivity data of antihistamines and an asymmetric pharmacophore model for H₁-antagonists has been described. © 1994 Wiley-Liss, Inc.     

Methods and strategies available for the process control and optimization of monoclonal antibody production

The objective of this paper is to explore the range of methods and strategies available for the process control and optimization of monoclonal antibody production by hybridoma cell culture. Emphasis will be placed on the choice of the level of complexity incorporated into the process control and optimisation procedure. It will be shown that the behaviour of hybridomas in culture is influenced by sophisticated cellular metabolic activities and various interactive environmental factors and that the understanding and modelling of the way hybridomas grow in the bioreactor should enable optimisation of bioreactor operating conditions to achieve maximum monoclonal antibody formation. However, due to the lack of on-line instrumentation of important biological variables and the incomplete knowledge of hybridoma cultivation process, there exist many limitations and challenges to the advent of applications of process control and optimisation in this field. To solve the problem, introduction of industrially practical biological measurements and development of new control concepts are inevitable. At the end of this paper, we shall discuss possible schemes for the control of the physsiological state of cells in order that balanced cell growth and maximum monoclonal antibody synthesis may be achieved.     

Mathematical modelling of ATP, K and Na interactions with (Na + K)-ATPase occurring under equilibrium conditions

The controlling effect of ATP, K⁺ and Na⁺ on the rate of (Na⁺ + K⁺)-ATPase inactivation by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) is used for the mathematical modelling of the interaction of the effectors with the enzyme under equilibrium conditions.

1. 1. Of a series of conceivable interaction models, designed without conceptual restrictions to describe the effector control of inactivation kinetics, only one fits the experimental data described in a preceding paper.

2. 2. The model is characterized by the coexistence of two binding sites for ATP and the coexistence of two separate binding sites for K⁺ and Na⁺ on the enzyme-ATP complex. On the basis of this model, the effector parameters fitting the experimental data most closely are estimated by means of nonlinear least-squares fits.

3. 3. The apparent dissociation constants for ATP of the enzyme-ATP complex or of the enzyme-(ATP)₂ complex are computed to lie near 0.0024 mM and 0.34 mM, respectively, irrespective of whether K⁺ and Na⁺ were absent or K⁺ and K⁺ plus Na⁺, respectively, were present in the experiments.

4. 4. The origin of the high and the low affinity site for binding of ATP to the (Na⁺ + K⁺)-ATPase molecule is traced back to the coexistence of two catalytic centres which, although primarily equivalent as to the reactivity of their thiol groups with NBD-Cl, are induced into anticooperative communication by ATP binding and thus show an induced geometric asymmetry.

Bioaugmentation for enhancing biological wastewater treatment

The literature on bioaugmentation products has been reviewed. Their manufacture and method of use is explained. The various applications are listed and the independent investigations, as opposed to manufacturers accounts, at laboratory and full scale are reviewed. The economics and kinetic modelling are also discussed. In laboratory investigations bioaugmentation often failed, whereas at full scale it was often successful, probably due to the imposition of steady state at laboratory scale. Most products require a period of acclimatisation before working; this and other possible reasons for failure are discussed.