A massively multi-scale approach to characterizing tissue architecture by synchrotron micro-CT applied to the human placenta.

Multi-scale structural assessment of biological soft tissue is challenging but essential to gain insight into structure-function relationships of tissue/organ. Using the human placenta as an example, this study brings together sophisticated sample preparation protocols, advanced imaging and robust, validated machine-learning segmentation techniques to provide the first massively multi-scale and multi-domain information that enables detailed morphological and functional analyses of both maternal and fetal placental domains. Finally, we quantify the scale-dependent error in morphological metrics of heterogeneous placental tissue, estimating the minimal tissue scale needed in extracting meaningful biological data. The developed protocol is beneficial for high-throughput investigation of structure-function relationships in both normal and diseased placentas, allowing us to optimize therapeutic approaches for pathological pregnancies. In addition, the methodology presented is applicable in the characterization of tissue architecture and physiological behaviours of other complex organs with similarity to the placenta, where an exchange barrier possesses circulating vascular and avascular fluid spaces.

Requirement of salicylic Acid for the induction of systemic acquired resistance.

It has been proposed that salicylic acid acts as an endogenous signal responsible for inducing systemic acquired resistance in plants. The contribution of salicylic acid to systemic acquired resistance was investigated in transgenic tobacco plants harboring a bacterial gene encoding salicylate hydroxylase, which converts salicylic acid to catechol. Transgenic plants that express salicylate hydroxylase accumulated little or no salicylic acid and were defective in their ability to induce acquired resistance against tobacco mosaic virus. Thus, salicylic acid is essential for the development of systemic acquired resistance in tobacco.

Vip3A, a novel Bacillus thuringiensis vegetative insecticidal protein with a wide spectrum of activities against lepidopteran insects.

A novel vegetative insecticidal gene, vip3A(a), whose gene product shows activity against lepidopteran insect larvae including black cutworm (Agrotis ipsilon), fall armyworm (Spodoptera frugiperda), beet armyworm (Spodoptera exigua), tobacco budworm (Heliothis virescens), and corn earworm (Helicoverpa zea) has been isolated from Bacillus thuringiensis strain AB88. VIP3-insecticidal gene homologues have been detected in approximately 15% of Bacillus strains analyzed. The sequence of the vip3A(b) gene, a homologue of vip3A(a) isolated from B. thuringiensis strain AB424 is also reported. Vip3A(a) and (b) proteins confer upon Escherichia coli insecticidal activity against the lepidopteran insect larvae mentioned above. The sequence of the gene predicts a 791-amino acid (88.5 kDa) protein that contains no homology with known proteins. Vip3A insecticidal proteins are secreted without N-terminal processing. Unlike the B. thuringiensis 5-endotoxins, whose expression is restricted to sporulation, Vip3A insecticidal proteins are expressed in the vegetative stage of growth starting at mid-log phase as well as during sporulation. Vip3A represents a novel class of proteins insecticidal to lepidopteran insect larvae.

Choline monooxygenase, an unusual iron-sulfur enzyme catalyzing the first step of glycine betaine synthesis in plants: prosthetic group characterization and cDNA cloning.

Plants synthesize the osmoprotectant glycine betaine via the route choline --> betaine aldehyde --> glycine betaine. In spinach, the first step is catalyzed by choline monooxygenase (CMO), a ferredoxin-dependent stromal enzyme that has been hypothesized to be an oligomer of identical subunits and to be an Fe-S protein. Analysis by HPLC and matrix-assisted laser desorption ionization MS confirmed that native CMO contains only one type of subunit (Mr 42,864). Determination of acid-labile sulfur and nonheme iron demonstrated that there is one [2Fe-2S] cluster per subunit, and EPR spectral data indicated that this cluster is of the Rieske type--i.e., coordinated by two Cys and two His ligands. A full-length CMO cDNA (1,622 bp) was cloned from spinach using a probe generated by PCR amplification for which the primers were based on internal peptide sequences. The ORF encoded a 440-amino acid polypeptide that included a 60-residue transit peptide. The deduced amino acid sequence included two Cys-His pairs spaced 16 residues apart, a motif characteristic of Rieske-type Fe-S proteins. Larger regions that included this motif also showed some sequence similarity (approximately 40%) to Rieske-type proteins, particularly bacterial oxygenases. Otherwise there was very little similarity between CMO and proteins from plants or other organisms. RNA and immunoblot analyses showed that the expression of CMO in leaves increased several-fold during salinization. We conclude that CMO is a stress-inducible representative of a new class of plant oxygenases.