System wide cofactor turnovers can propagate metabolic stability between pathways

Metabolic homeostasis, or low-level metabolic steady state, has long been taken for granted in metabolic engineering, and research priority has always been given to understand metabolic flux control and regulation of the reaction network. In the past, this has not caused concerns because the metabolic networks studied were invariably associated with living cells. Nowadays, there are needs to reconstruct metabolic networks, and so metabolic homeostasis cannot be taken for granted. For metabolic steady state, enzyme feedback control has been known to explain why metabolites in metabolic pathways can avoid accumulation. However, we reasoned that there are further contributing mechanisms. As a new methodology developed, we separated cofactor intermediates (CIs) from non-cofactor intermediates, and identified an appropriate type of open systems for operating putative reaction topologies. Furthermore, we elaborated the criteria to tell if a multi-enzyme over-all reaction path is of in vivo nature or not at the metabolic level. As new findings, we discovered that there are interactions between the enzyme feedback inhibition and the CI turnover, and such interactions may well lead to metabolic homeostasis, an emergent property of the system. To conclude, this work offers a new perspective for understanding the role of CIs and the presence of metabolic homeostasis in the living cell. In perspective, this work might provide clues for constructing non-natural metabolic networks using multi-enzyme reactions or by degenerating metabolic reaction networks from the living cell. Keywords: Metabolic stability, Metabolic steady state, Cofactor balance, Cofactor turnover, Enzyme feedback control, Emergent property of metabolic networ

Towards a molecular definition of worker sterility: differential gene expression and reproductive plasticity in honey bees

We show that differences in the reproductive development of honey bee workers are associated with locus-specific changes to abundance of messenger RNA. Using a cross-fostering field experiment to control for differences related to age and environment, we compared the gene expression profiles of functionally sterile workers (wild-type) and those from a mutant strain in which workers are reproductively active (anarchist). Among the set of three genes that are significantly differentially expressed are two major royal jelly proteins that are up-regulated in wild-type heads. This discovery is consistent with sterile workers synthesizing royal jelly as food for developing brood. Likewise, the relative underexpression of these two royal jellies in anarchist workers is consistent with these workers’ characteristic avoidance of alloparental behaviour, in favour of selfish egg-laying. Overall, there is a trend for the most differentially expressed genes to be up-regulated in wild-type workers. This pattern suggests that functional sterility in honey bee workers may generally involve the expression of a suite of genes that effectively ‘switch’ ovaries off, and that selfish reproduction in honey bee workers, though rare, is the default developmental pathway that results when ovary activation is not suppressed

Functional Diversity of Microbial Communities in Sludge-Amended Soils

AbstractThe BIOLOG method was applied to exploration of functional diversity of soil microbial communities in sludge-amended soils sampled from the Yangtze River Delta. Results indicated that metabolic profile, functional diversity indexes and Kinetic parameters of the soil microbial communities changed following soil amendment with sewage sludge, suggesting that the changes occurred in population of the microbes capable of exploiting carbon substrates and in this capability as well. The kinetic study of the functional diversity revealed that the metabolic profile of the soil microbial communities exhibited non-linear correlation with the incubation time, showing a curse of sigmoid that fits the dynamic model of growth of the soil microbial communities. In all the treatments, except for treatments of coastal fluvo-aquic soil amended with fresh sludge and dried sludge from Hangzhou, kinetic parameters K and r of the functional diversity of the soil microbial communities decreased significantly and parameter S increased. Changes in characteristics of the functional diversity well reflected differences in C utilizing capacity and model of the soil microbial communities in the sludge-amended soils, and changes in functional diversity of the soil microbial communities in a particular eco-environment, like soil amended with sewage sludge

Initiation of an early mobilisation programme in intensive care units—A preliminary report

The Tropical Agriculturalist series Livestock product/on systems examines how individual species of domestic livestock can be integrated into the whole concept of sustainable agriculture in the tropics. The main part of the book is devoted to a series of case studies covering most, if not all, of the systems of livestock husbandry used in the tropics. The reasons why these systems have been developed are outlined, their limitations highlighted and the ways in which they could be improved are discussed. This part of the book is a useful short reference work presenting the main features of the extremely varied livestock production systems found across the tropics. Readers of the book will obtain a good insight into how livestock and crop husbandry can be linked in the wetter regions of the tropics to improve the use of resources. In the dry regions of the tropics, where crop husbandry is not an option, animal husbandry is the best way of utilizing these regions for the benefit of people. The book shows how livestock are essential for the development of ecologically sound systems of food production. All types of livestock are covered including buffalo, camels and poultry. Livestock production systems by Trevor Wilson 1995 141pp ISBN 0 333 60012 6 Animal health volume/explains the causes of animal diseases, how they are spread and the means available for their control. It covers not only diseases caused by micro-organisms, arthropods and helminths, but also deals with metabolic diseases and those caused by toxins. The signs of health and the symptoms to look for when an animal is suspected of being diseased are clearly presented using simple diagnostic keys. Tables are included to assist in diagnosis of diseases in the major farm animals found in the tropics. The book concludes by dealing with general veterinary procedures, including the administration of medicines. The book is a valuable guide for anyone involved with maintaining and establishing the health of animals in tropical and subtropical countries. It should be read in conjunction with volume 2 (which appeared earlier) and those volumes in the series which deal with individual animal species. Animal health volume l: general principles by Archie Hunter 1996 167pp ISBN 0 333 61202 7 Avocado is a succinct guide to the cultivation and marketing of a fruit of growing commercial importance throughout the world. It covers the plant's origins and distribution, botany, and selection and breeding. as well as providing more detailed guidance on the field operations needed to grow this sensitive crop successfully. Land preparation, the choice of cultivars and rootstocks, grafting techniques, irrigation requirements, and major pests and diseases are some of the topics covered. Lastly, the book turns to harvesting and processing considerations, with special emphasis on the requirements for export. A wealth of photographs, line drawings, tables and charts support the text, which is based on the authors' 20 years of experience as well as extensive reference to the global literature. Avocado by J P Gaillard and d Godefroy 1995 120pp ISBN 0 333 57468 0 The above titles are part of the Macmillan The Tropical Agriculturalist series which is published in association with, and are available from, CTA.The Tropical Agriculturalist seriesLivestock product/on systems examines how individual species of domestic livestock can be integrated into the whole concept of sustainable agriculture in the tropics. The main part of the book is devoted to a..

Wolfenstein Parametrization at Higher Order: Seeming Discrepancies and Their Resolution

In different Wolfenstein parametrizations derived from different exact parametrizations of the Cabibbo-Kobayashi-Maskawa matrix, we explicitly study seeming discrepancies between the matrix elements at the higher order of the expansion parameter $\lambda$. A systematic way of resolving the seeming discrepancies is proposed. We find that most of the discrepancies can be naturally resolved by a proper redefinition of the numerically small (of order $\lambda$) parameters. Our approach is further applied to the cases for the Wolfenstein-{\it like} parametrizations, such as the Qin-Ma parametrization.Comment: 5 pages, two paragraphs added to explain the motivation for considering various Wolfenstein-like parametrizations; version to appear in PL

Remarks on the Qin-Ma Parametrization of Quark Mixing Matrix

Recently, Qin and Ma (QM) have advocated a new Wolfenstein-like parametrization of the quark mixing matrix based on the triminimal expansion of the Cabibbo-Kobayashi-Maskawa (CKM) parametrization. The CP-odd phase in the QM parametrization is around $90^\circ$ just as that in the CKM parametrization. We point out that the QM parametrization can be readily obtained from the Wolfenstein parametrization after appropriate phase redefinition for quark fields and that the phase $\delta$ in both QM and CKM parametrizations is related to the unitarity angles $\alpha$, $\beta$ and $\gamma$, namely, $\delta= \beta+\gamma$ or $\pi-\alpha$. We show that both QM and Wolfenstein parametrizations can be deduced from the CKM and Chau-Keung-Maiani ones. By deriving the QM parametrization from the Fritzsch-Xing (FX) parametrization of the quark mixing matrix, we find that the phase of the FX form is in the vicinity of $-270^\circ$ and hence $\sin\delta\approx 1$. We discuss the seeming discrepancy between the Wolfenstein and QM parametrizations at the high order of $\lambda\approx |V_{us}|$.Comment: 8 pages, a shortened version accepted by PL

Efficient rooting for establishment of papaya plantlets by micropropagation

A low cost micropropagation protocol to produce high quality root systems which are easy and economical to acclimatize is essential for large-scale micropropagation of papaya (Carica papaya L.). In this study, individual shoots (> 0.5 cm) with 2 similar to 3 leaves from in vitro papaya multiple shoots were cultured on MS agar medium containing 2.5 mu M IBA under dark conditions for 1 week for root induction. They were then transferred to agar or vermiculite media, containing half strength MS medium, under aerated or non-aerated conditions, for root development. Rooting percentage of shoots cultured for 2 weeks in aerated vermiculite was 94.5%, compared with 90.0% in non-aerated vermiculite, 71.1% in aerated agar, and 62.2% in non-aerated agar. Shoots with roots were acclimated in vermiculite under 100% RH for 1 week and then under ambient conditions for 2 weeks in a temperature-controlled growth chamber (28 degrees C). The survival rates of the plantlets were 94.5% from aerated vermiculite, 87.8% from non-aerated vermiculite, 42.2% from aerated agar, and 35.6% from non-aerated agar. Thus, root induction in low-concentration IBA agar medium followed by root development in vermiculite containing half strength MS medium under aerated conditions results in efficient rooting of in vitro papaya shoots