Myosin light-chain expression during avian muscle development

Monoclonal antibodies to adult chicken myosin light chains were generated and used to quantitate the types of myosin light-chain (MLC) isoforms expressed during development of the pectoralis major (PM), anterior latissimus dorsi (ALD), and medial adductor (MA) muscles of the chicken. These are muscles which, in the adult, are composed predominantly of fast, slow, and a mixture of fiber types, respectively. Three distinct phases of MLC expression characterized the development of the PM and MA muscles. The first identifiable pase occurred during the period of 5-7 d of incubation in ovo. Extracts of muscles from the pectoral region (which included the presumptive PM muscle) contained only fast MLC isoforms. This period of exclusive fast light-chain synthesis was followed by a phase (8- 12 d of incubation in ovo) in which coexpression of both fast and slow MLC isoforms was apparent in both PM and MA muscles. During the period, the composition of both fast and slow MLC isoforms in the PM and MA muscles was identical. Beginning at day 12 in ovo, the ALD was also subjected to immunochemical analyses. The proportion of fast and slow MLCs in this muscle at day 12 was similar to that present in the other muscles studied. The third development phase of MLC expression began at approximately 12 d of incubation in ovo and encompassed the transition in MLC composition to the isoform patterns incubation in ovo and encompassed the transition in MLC composition to the isoform patterns typical of adult muscle. During this period, the relative proportion of slow MLC rose in both the MA and ALD and fell in the PM. By day 16, the third fast light chain, LC(3f), was apparent in extracts of both the PM and MA. These results show that there is a developmental progression in the expression of MLC in the two avian muscles studied from day 5 in ovo; first, only fast MLCs are accumulated, then both fast and slow MLC isoforms are expressed. Only during the latter third of development in ovo is the final MLC isoform pattern characteristic of a particular muscle type expressed.     

Last‐century changes of alpine grassland water‐use efficiency: a reconstruction through carbon isotope analysis of a time‐series of Capra ibex horns

The ecophysiological response of an alpine grassland to recent climate change and increasing atmospheric CO₂ concentration was investigated with a new strategy to go back in time: using a time‐series of Capra ibex horns as archives of the alpine grasslands' carbon isotope discrimination (¹³Δ). From the collection of the Natural History Museum of Bern, horns of 24 males from the population of the Augstmatthorn–Brienzer Rothorn mountains, Switzerland, were sampled covering the period from 1938 to 2006. Samples were taken from the beginning of each year‐ring of the horns, representing the beginning of the horn growth period, the spring. The horns' carbon ¹³C content (Δ¹³C) declined together with that of atmospheric CO₂ over the 69‐year period, but ¹³Δ increased slightly (+0.4‰), though significantly (P<0.05), over the observation period. Estimated intercellular CO₂ concentration increased (+56 μmol mol^?1) less than the atmospheric CO₂ concentration (+81 μmol mol^?1), so that intrinsic water‐use efficiency increased by 17.8% during the 69‐year period. However, the atmospheric evaporative demand at the site increased by approximately 0.1 kPa between 1955 and 2006, thus counteracting the improvement of intrinsic water‐use efficiency. As a result, instantaneous water‐use efficiency did not change. The observed changes in intrinsic water‐use efficiency were in the same range as those of trees (as reported by others), indicating that leaf‐level control of water‐use efficiency of grassland and forests followed the same principles. This is the first reconstruction of the water‐use efficiency response of a natural grassland ecosystem to last century CO₂ and climatic changes. The results indicate that the alpine grassland community has responded to climate change by improving the physiological control of carbon gain to water loss, following the increases in atmospheric CO₂ and evaporative demand. But, effective leaf‐level water‐use efficiency has remained unchanged.     

Machine learning techniques in disease forecasting: a case study on rice blast prediction

Background  

Diverse modeling approaches viz. neural networks and multiple regression have been followed to date for disease prediction in plant populations. However, due to their inability to predict value of unknown data points and longer training times, there is need for exploiting new prediction softwares for better understanding of plant-pathogen-environment relationships. Further, there is no online tool available which can help the plant researchers or farmers in timely application of control measures. This paper introduces a new prediction approach based on support vector machines for developing weather-based prediction models of plant diseases.     

Complement facilitates early prion pathogenesis

New-variant Creutzfeldt-Jakob disease and scrapie are typically initiated by extracerebral exposure to the causative agent, and exhibit early prion replication in lymphoid organs. In mouse scrapie, depletion of B-lymphocytes prevents neuropathogenesis after intraperitoneal inoculation, probably due to impaired lymphotoxin-dependent maturation of follicular dendritic cells (FDCs), which are a major extracerebral prion reservoir. FDCs trap immune complexes with Fc-gamma receptors and C3d/C4b-opsonized antigens with CD21/CD35 complement receptors. We examined whether these mechanisms participate in peripheral prion pathogenesis. Depletion of circulating immunoglobulins or of individual Fc-gamma receptors had no effect on scrapie pathogenesis if B-cell maturation was unaffected. However, mice deficient in C3, C1q, Bf/C2, combinations thereof or complement receptors were partially or fully protected against spongiform encephalopathy upon intraperitoneal exposure to limiting amounts of prions. Splenic accumulation of prion infectivity and PrPSc was delayed, indicating that activation of specific complement components is involved in the initial trapping of prions in lymphoreticular organs early after infection.     

Prions: health scare and biological challenge

Although human prion diseases are rare, the incidence of 'new variant' Creutzfeldt-Jakob disease in the United Kingdom is increasing exponentially. Given that this disease is probably the result of infection with bovine prions, understanding how prions replicate--and how to counteract their action--has become a central issue for public health. What are the links between the bovine and human prion diseases, and how do prions reach and damage the central nervous system?     

Memo Has a Novel Role in S1P Signaling and Crucial for Vascular Development

Memo is a conserved protein that was identified as an essential mediator of tumor cell motility induced by receptor tyrosine kinase activation. Here we show that Memo null mouse embryonic fibroblasts (MEFs) are impaired in PDGF-induced migration and this is due to a defect in sphingosine-1-phosphate (S1P) signaling. S1P is a bioactive phospholipid produced in response to multiple stimuli, which regulates many cellular processes. S1P is secreted to the extracellular milieu where it exerts its function by binding a family of G-protein coupled receptors (S1PRs), causing their activation in an autocrine or paracrine manner. The process, termed cell-autonomous S1PR signaling, plays a role in survival and migration. Indeed, PDGF uses cell-autonomous S1PR signaling to promote cell migration; we show here that this S1P pathway requires Memo. Using vascular endothelial cells (HUVECs) with Memo knock-down we show that their survival in conditions of serum-starvation is impaired. Furthermore, Memo loss in HUVECs causes a reduction of junctional VE-cadherin and an increase in sprout formation. Each of these phenotypes is rescued by S1P or S1P agonist addition, showing that Memo also plays an important role in cell-autonomous S1PR signaling in endothelial cells. We also produced conventional and endothelial cell-specific conditional Memo knock-out mouse strains and show that Memo is essential for embryonic development. Starting at E13.5 embryos of both strains display bleeding and other vascular problems, some of the phenotypes that have been described in mouse strains lacking S1PRs. The essential role of Memo in embryonic vascular development may be due in part to alterations in S1P signaling. Taken together our results show that Memo has a novel role in the S1P pathway and that Memo is needed to promote cell-autonomous S1PR activation.     

Fungicide control of Stenocarpella Maydis in the Nigerian Savanna

A survey of farmers' fields in the Savanna zone of Nigeria in 1999 indicated the presence of stalk and cob rots of maize at incidence rates of 15?–?43% and disease severity of 2.0?–?6.7. The causal organism was identified as Stenocarpella maydis (?=?Diplodia maydis). S. maydis was found to reduce seed germination by up to 29.2%. Laboratory and screen house experiments were used to evaluate the efficacy of six seed treatment fungicides indicated that Luxan (a local fungicide of unknown composition), benomyl (Benlate) and mancozeb (Dithane M-45) were more effective than metalaxyl?+?carboxin?+?furathiocarp (Apron-plus), carbendazin?+?maneb (Delsene M) and tetramethylthiuram disulphide?+?hexachlorobenzene (thiram?+?HCB) in controlling S. maydis. Stalk rot severity increased with increasing fertilization rates.     

Evaluation of neem seed powder for Fusarium wilt and Meloidogyne control on tomato

Fusarium wilt and root-knot are important diseases of tomato. The use of chemical is becoming less appealing because of the health implications. Also, the chemicals required are often not within the reach of farmers in most of the developing part of the world. This research is aimed at finding an alternative mode of control. Tomato variety Roma VF inoculated with Meloidogyne and Fusarium were treated with 2 g/kg soil neem seed powder in the screenhouse and 2 Mg ha ^{? 1} in the field. An untreated and Furadan treated plot in the field served as control. Neem seed powder significantly reduced the disease severity of Fusarium and root-knot in both screenhouse and field. Results suggest the possible use of neem seed powder for control of the root-knot nematodes - Fusarium wilt disease complex.