Legumes symbioses: absence of Nod genes in photosynthetic bradyrhizobia

Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.     

Assessing the diet of the endangered Beale’s eyed turtle (Sacalia bealei) using faecal content and stable isotope analyses: Implications for conservation

1. Turtles from Asia are on the brink of extinction with 53% of species considered endangered or critically endangered. Unfortunately, the ecology of many threatened species remains largely unknown.
2. In this study, the diet of the endangered Beale’s eyed turtle (Sacalia bealei) was investigated using two methods, visual faecal content analysis and stable isotope analysis.
3. Results from both methods indicated that S. bealei is highly reliant on riparian resources, especially fruits and terrestrial insects. Stable isotope data indicated that terrestrial resources made up around half (47–53%) of all assimilated food resources. These findings suggest that S. bealei facilitates energy flow from riparian forests to stream ecosystems. Moreover, S. bealei is likely to be a seed disperser for riparian plants.
4. This study represents the first application of stable isotope methods to examine the diet of Asian freshwater turtles and their resource use. We stress the importance of similar studies to improve our understanding of remnant turtle populations before they disappear as a result of human activities.

     

Habitat use of globally threatened juvenile Chinese horseshoe crab,Tachypleus tridentatus under the influence of simulated intertidal oyster culture structures in Hong Kong

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Alpha-synuclein blocks ER-Golgi traffic and Rab1 rescues neuron loss in Parkinson's models

Alpha-synuclein (alphaSyn) misfolding is associated with several devastating neurodegenerative disorders, including Parkinson's disease (PD). In yeast cells and in neurons alphaSyn accumulation is cytotoxic, but little is known about its normal function or pathobiology. The earliest defect following alphaSyn expression in yeast was a block in endoplasmic reticulum (ER)-to-Golgi vesicular trafficking. In a genomewide screen, the largest class of toxicity modifiers were proteins functioning at this same step, including the Rab guanosine triphosphatase Ypt1p, which associated with cytoplasmic alphaSyn inclusions. Elevated expression of Rab1, the mammalian YPT1 homolog, protected against alphaSyn-induced dopaminergic neuron loss in animal models of PD. Thus, synucleinopathies may result from disruptions in basic cellular functions that interface with the unique biology of particular neurons to make them especially vulnerable.     

DISC1 and PDE4B are interacting genetic factors in schizophrenia that regulate cAMP signaling

The disrupted in schizophrenia 1 (DISC1) gene is a candidate susceptibility factor for schizophrenia, but its mechanistic role in the disorder is unknown. Here we report that the gene encoding phosphodiesterase 4B (PDE4B) is disrupted by a balanced translocation in a subject diagnosed with schizophrenia and a relative with chronic psychiatric illness. The PDEs inactivate adenosine 3',5'-monophosphate (cAMP), a second messenger implicated in learning, memory, and mood. We show that DISC1 interacts with the UCR2 domain of PDE4B and that elevation of cellular cAMP leads to dissociation of PDE4B from DISC1 and an increase in PDE4B activity. We propose a mechanistic model whereby DISC1 sequesters PDE4B in resting cells and releases it in an activated state in response to elevated cAMP.     

Hydrolysis of nitriles using an immobilized nitrilase: applications to the synthesis of methionine hydroxy analogue derivatives

Mild and selective hydrolysis of a large range of nitriles leading to carboxylic acids was achieved under neutral conditions by an immobilized and genetically modified enzyme preparation from Alcaligenes faecalis ATCC8750. This immobilized nitrilase has been shown to be an effective catalyst for the stereoselective hydrolysis of mandelonitrile 1a to R-(-)-mandelic acid 1c. This method is particularly useful for the production of hydroxy analogues of methionine derivatives 2c-4c that could have an interest in cattle feeding and for the transformation of compounds containing other acid- or base-sensitive groups 3a-10a. A series of aliphatic dinitriles 11a-15a was hydrolyzed to the corresponding cyano acids. The suitability of the immobilized catalyst as a robust and versatile biocatalyst is discussed, and models to account for the stereoselectivity of the enzymic hydrolysis have been proposed.