The Isolation and Characterization of Adenosine Monophosphate-rich Polynucleotides Synthesized by Soybean Hypocotyl Cells: Their Relation to Messenger Ribonucleic Acid

Plant ribonucleic acids which have high adenosine monophosphate concentrations were studied. Purified deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid fractions both contained poly-adenosine monophosphate sequences (those from the latter being longer than those from the former); without these poly-adenosine monophosphate sequences their base compositions were the same. The average poly-adenosine monophosphate sequence from purified tenaciously bound ribonucleic acid was 160 residues long, as measured by gel electrophoresis. However, base hydrolysis and chromatography indicated one 3′-nucleoside (adenosine) per 71 nucleotides, giving a chain length of 72 residues. The dominant species in the cytoplasm, as measured by radioactive precursor incorporation, was tenaciously bound ribonucleic acid, whereas deoxyribonucleic acid-like ribonucleic acid was present in greater amounts in the nucleus. This work provides evidence that deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid represent forms of messenger ribonucleic acid in soybean, with deoxyribonucleic acid-like ribonucleic acid residing in the nucleus, perhaps as the messenger ribonucleic acid precursor, and tenaciously bound ribonucleic acid residing, as the active messenger ribonucleic acid, in the cytoplasm.     

High predictability of direct competition between marine diatoms under different temperatures and nutrient states

The distribution of marine phytoplankton will shift alongside changes in marine environments, leading to altered species frequencies and community composition. An understanding of the response of mixed populations to abiotic changes is required to adequately predict how environmental change may affect the future composition of phytoplankton communities. This study investigated the growth and competitive ability of two marine diatoms, Phaeodactylum tricornutum and Thalassiosira pseudonana, along a temperature gradient (9–35°C) spanning the thermal niches of both species under both high‐nitrogen nutrient‐replete and low‐nitrogen nutrient‐limited conditions. Across this temperature gradient, the competitive outcome under both nutrient conditions at any assay temperature, and the critical temperature at which competitive advantage shifted from one species to the other, was well predicted by the temperature dependencies of the growth rates of the two species measured in monocultures. The temperature at which the competitive advantage switched from P. tricornutum to T. pseudonana increased from 18.8°C under replete conditions to 25.3°C under nutrient‐limited conditions. Thus, P. tricornutum was a better competitor over a wider temperature range in a low N environment. Being able to determine the competitive outcomes from physiological responses of single species to environmental changes has the potential to significantly improve the predictive power of phytoplankton spatial distribution and community composition models.     

Characteristics of Sleep–Wakefulness Cycle and Circadian Activity in the Lesser Mouse-Deer (Tragulus kanchil)

Doklady Biological Sciences - The pattern of sleep and circadian activity of the lesser mouse-deer (Tragulus kanchil) that is the smallest (body mass between 1.5 and 2.2 kg) representative of the...     

A novel allele of the Arabidopsis thaliana MACPF protein CAD1 results in deregulated immune signaling

Immune recognition in plants is governed by two major classes of receptors: pattern recognition receptors (PRRs) and nucleotide-binding leucine-rich repeat receptors (NLRs). Located at the cell surface, PRRs bind extracellular ligands originating from microbes (indicative of “non-self”) or damaged plant cells (indicative of “infected-self”), and trigger signaling cascades to protect against infection. Located intracellularly, NLRs sense pathogen-induced physiological changes and trigger localized cell death and systemic resistance. Immune responses are under tight regulation in order to maintain homeostasis and promote plant health. In a forward-genetic screen to identify regulators of PRR-mediated immune signaling, we identified a novel allele of the membrane-attack complex and perforin (MACPF)-motif containing protein CONSTITUTIVE ACTIVE DEFENSE 1 (CAD1) resulting from a missense mutation in a conserved N-terminal cysteine. We show that cad1-5 mutants display deregulated immune signaling and symptoms of autoimmunity dependent on the lipase-like protein ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), suggesting that CAD1 integrity is monitored by the plant immune system. We further demonstrate that CAD1 localizes to both the cytosol and plasma membrane using confocal microscopy and subcellular fractionation. Our results offer new insights into immune homeostasis and provide tools to further decipher the intriguing role of MACPF proteins in plants.