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.     

Hydrogen Peroxide in Human Blood

Blood and plasma of humans and rats were analyzed for hydrogen peroxide. The samples were analyzed after deproteinization with trichloroacetic acid, immediately after they were withdrawn from human volunteers or rats. A radio-isotopic technique based on peroxide-dependent decarboxylation of 1-¹⁴C-alpha-ketoacids and consequent liberation of ¹⁴CO₂ was used. The results demonstrate the presence ofmicromolar levels of H₂O₂, both, in the plasma as well as in the whole blood. The values in the whole blood were substantially greater than the plasma. This was true for rats as well as humans. The presence of such significant quantities of H₂O₂ in the blood have been demonstrated for the first time. The investigation, therefore, opens a newer avenue of research on diseases purported to be related to the generation of oxygen radicals in vivo.     

New World Stictocladius Edwards (Diptera: Chironomidae)

The orthocladiine Chironomidae genus Stictocladius Edwards was described originally from South America. Although recognised subsequently as present also in Australia and New Zealand, the true diversity in the Neotropics has remained unclear. After more than a decade of collections of both isolated adults and aquatic immature stages, we can recognise several new taxa and associate some immature stages. Thus, we describe Stictocladius prati n. sp. as male, female, pupa and larva; Stictocladius acutus n. sp. and Stictocladius acrilobus n. sp. as male, female and pupa; Stictocladius fimbriatus n. sp. as male and female; Stictocladius fovigus n. sp. and Stictocladius nudiventer n. sp. as male and pupa; and Stictocladius privicalcar n. sp. and Stictocladius prostatus n. sp. each as male imago alone. The male and female of Stictocladius pulchripennis Edwards is redescribed and the pupa described. The male and female of Stictocladius flavozonatus Edwards and the male of Stictocladius calonotum Edwards are described. Five pupal types are described: Stictocladius sp. A (near S. acrilobus), Stictocladius sp. B (possibly S. calonotum), Stictocladius sp. C (near S. calonotum), Stictocladius sp. D (possibly S. flavozonatus) and Stictocladius sp. E with uncertain affinity. A larva from Chile of the Stictocladius ??sofour type?? (Stictocladius sp. F) and an unreared larva from North America (Stictocladius sp. G) possibly belonging to S. acutus are described. Keys to named Neotropical male and female imagines of Stictocladius and to all pupal forms of Neotropical Stictocladius are provided. Some data concerning fourth instars of Stictocladius are presented. Means of differentiation from putative sister taxon Lopescladius are discussed.     

The Fragilis interferon-inducible gene family of transmembrane proteins is associated with germ cell specification in mice

Background  

Specification of primordial germ cells in mice depends on instructive signalling events, which act first to confer germ cell competence on epiblast cells, and second, to impose a germ cell fate upon competent precursors. fragilis, an interferon-inducible gene coding for a transmembrane protein, is the first gene to be implicated in the acquisition of germ cell competence.